Content:
Presentation type:
SSS – Soil System Sciences

EGU24-11742 | ECS | Orals | SSS5.2 | Arne Richter Awards for Outstanding ECS Lecture

Digging into the Future: The transition between bedrock and soil as an underexplored frontier zone in geoscience 

Daniel Evans

Terrestrial environments and their ecosystems demand healthy, sustainable, and resilient soils. Over the past couple of decades, significant efforts have been made to safeguard global soils, yet the materials and resources responsible for soil formation have been widely overlooked.  The transition from bedrock to soil – a zone often described as ‘soil parent material’ – holds an exciting yet untapped potential for helping us address some of the largest environmental challenges, including climate change and the biodiversity crisis. In this award lecture, I will present a strand of my research programme ‘Building Tomorrow’s Soils’ which seeks to establish how soil parent materials enhance the sustainability, health, and resilience of soil systems. First, with a focus on carbon sequestration, I will highlight how the bedrock–soil transition zone has the potential to be a long-term store of organic carbon. I will then present research which shows that some soil parent materials release petrogenic (i.e. rock-derived) organic carbon into soils. These understudied inputs of organic carbon to soils are currently absent from most, if not all, soil carbon models, which threatens our ability to optimize soil carbon management in the long-term. Finally, I will argue that developing a mechanistic understanding about this transition zone – this underexplored material which is neither rock nor soil in structure and function, but a blend of both – requires a similarly cross-disciplinary approach.

How to cite: Evans, D.: Digging into the Future: The transition between bedrock and soil as an underexplored frontier zone in geoscience, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11742, https://doi.org/10.5194/egusphere-egu24-11742, 2024.

EGU24-12483 | Orals | MAL32-SSS | Philippe Duchaufour Medal Lecture

Beasts, Balances and Boundaries in Soil Science 

Jan Willem Van Groenigen

This is both an exciting and a challenging time to be a soil scientist. Societal interest in soil is thriving because of its pivotal role in food security, climate change, and biodiversity. But this interest comes with serious responsibilities, within the context of a scientific climate dominated by perverse incentives for funding and publishing. In this Philippe Duchaufour lecture I would like to reflect on some of the balances we should aim for, and the boundaries we should acknowledge, as soil scientists. I will do this for field of climate-related soil research; for the role of soil ecology in the transition towards sustainable agriculture; as well as for academic publishing.

The soil takes center stage in discussions regarding climate change mitigation. However, the focus is mostly on large-scale carbon sequestration (LSCS). There almost seems to be a dichotomy within the scientific community regarding the potential and desirability of LSCS, with exceedingly optimistic assessments finding their way to policy documents, and more critical publications on the limits or usefulness of LSCS apparently ignored. I will highlight some fundamental boundaries to large scale carbon sequestration, notably the amount of carbon available through photosynthesis. As a possible way forward, I will stress the importance of focusing on improving soil functioning rather than on increasing the carbon stock size.

The need for a transition towards more sustainable forms of agriculture while maintaining high productivity is broadly acknowledged within the scientific community. Such forms of agriculture should both include a high degree of circularity as well as a larger reliance on the benefits that soil biota provide. However, these two aspects are often not studied in relation to each other.  Earthworms provide an instructive case in this respect. It is clear that they are beneficial to crop growth – the literature even suggests an overall increase of 25% in crop yield in the presence of earthworms. Yet, this number is not realistic as many primary earthworm studies do not represent realistic systems. In particular, we should not claim that earthworms can compensate for the removal of nutrients through harvest. This can only be done through replenishment of nutrients from elsewhere – preferably in a circular manner. I will discuss how earthworms and other biota could positively affect nutrient recycling in future agricultural systems that will receive new, circular forms of soil amendments.  

Finally, scientific publishing is in crisis. Scientific articles are in many ways the basic building blocks of scientific careers, and yet the publishing process is overstretched and flawed. This is mostly related to imbalances: especially between those who pay and those who earn; and between those who write and those who review. I will highlight some of these imbalances, which are to some extend geographic, and will discuss to what extent switching to an open publishing model will resolve them. I will end with some thoughts on how to improve the publishing process, including a call for more cooperation between editors across journals to keep scientific publishing viable.

How to cite: Van Groenigen, J. W.: Beasts, Balances and Boundaries in Soil Science, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12483, https://doi.org/10.5194/egusphere-egu24-12483, 2024.

SSS0.1 – Inter- and Transdisciplinary Sessions

EGU24-180 | ECS | Orals | ITS1.23/SSS0.1.4

Developing a Rangeland Carbon Tracking and Monitoring System Using Remote Sensing Imagery Coupled With a Modeling Approach 

Yushu Xia, Jonathan Sanderman, Jennifer Watts, Megan Machmuller, Stephanie Ewing, Andrew Mullen, Charlotte Rivard, and Haydee Hernandez

Rangelands play a crucial role in providing various ecosystem services and have significant potential for carbon sequestration. However, monitoring soil organic carbon (SOC) stocks in rangelands is challenging due to the large size of ranches and the high spatial variability influenced by climate and management factors. To address these challenges, we have developed the Rangeland Carbon Tracking and Management (RCTM) system, which integrates remote sensing inputs, survey data sources, and both empirical and process-based SOC models. In this work, we will introduce the structure of RCTM v1.0, its data input requirements, data processing pipelines, and the resulting data outputs. Additionally, we will discuss the high-resolution soil moisture data layers, baseline SOC maps, and the targeted field sampling plan generated through an empirical digital soil mapping approach. The Bayesian calibration and validation scheme for obtaining grassland plant functional type (PFT)-specific parameters using flux tower network data will also be explained. After calibration, the RCTM system generated estimates of rangeland carbon fluxes across PFTs (R2 between 0.6 and 0.7) and surface depth SOC stocks (R2 = 0.6) with moderate accuracy at the regional scale. The visualization of modeling results associated with long-term rangeland C dynamics at different scales will be demonstrated using the Google Earth Engine platform to inform management decisions and policymaking.

How to cite: Xia, Y., Sanderman, J., Watts, J., Machmuller, M., Ewing, S., Mullen, A., Rivard, C., and Hernandez, H.: Developing a Rangeland Carbon Tracking and Monitoring System Using Remote Sensing Imagery Coupled With a Modeling Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-180, https://doi.org/10.5194/egusphere-egu24-180, 2024.

Soil erosion is a widespread environmental challenge with far-reaching implications for agricultural productivity, water quality and ecosystem health. Addressing this complex issue requires the use of modelling tools that empower diverse stakeholders, such as researchers and decision-makers, to simulate soil erosion systems under different scenarios. For these tools to be effective, not only they need to make good predictions, but they need to be accessible and educational, so users, regardless of their technical skills and modelling expertise, can understand and even more importantly, trust the model. In traditional soil erosion modelling, the primary emphasis to build trust is by demonstrating the model’s ability to replicate past observations, and less attention is given to build trust by providing an educational and exploratory experience. We introduce a project that aims at democratizing soil erosion modelling, making it more accessible and trustworthy to researchers, educators, decision-makers, and local communities. Leveraging the versatility and accessibility of Jupyter Notebooks, we are developing iMPACT-erosion, a soil erosion modelling toolbox to support education, land management and informed decision making. A series of dedicated Notebooks not only explain and simulate the main soil erosion processes but guides users through the main steps to enhance the credibility of the model results, i.e. sensitivity analysis, model calibration, uncertainty analysis, model evaluation and scenario analysis. The integration of interactive visualization enhances this experience by facilitating exploration of both the model configuration and the soil erosion system's response under different scenarios/decisions. This model development approach is not confined to the field of soil erosion and offers the potential to facilitate knowledge transfer and collaboration between model developers and decision makers in various domains.

How to cite: Peñuela, A.: Democratizing soil erosion modelling: A Jupyter Notebook approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1907, https://doi.org/10.5194/egusphere-egu24-1907, 2024.

EGU24-3186 | ECS | Orals | ITS1.23/SSS0.1.4

Prediction of soil phosphorus sorption capacity in agricultural soils using mid-infrared spectroscopy.  

Sifan Yang, Blánaid White, Fiona Regan, Nigel Kent, Rebecca Hall, Felipe de Santana, and Karen Daly

             Advice for phosphorus (P) fertilisation based on soil testing using extractive methods but does not consider P sorption processes. Traditional soil P sorption capacity examined from a Langmuir isotherm batch experimental design, which is time-consuming, labour intensive and expensive. Mid-infrared (MIR) spectroscopy is a rapid analysis technique that can potentially replace the extractive technique traditionally used in soil analysis. The objective of this work was to predict the isothermal parameter of P sorption maximum capacity (Smax, mg·kg-1) from MIR spectroscopy.

              This study created spectral libraries from benchtop (Bruker) and handheld (Agilent) MIR spectrometers by scanning samples in two particle sizes, < 0.100 mm (ball-milled) and < 2 mm. The four spectral libraries created used an archive of samples with a database of sorption parameters where soils were classified into low and high sorption capacities using a threshold value of Smax = 450.03 mg·kg-1. To assess the optimal algorithmic method with highest Smax prediction accuracy, regression models were based on the partial least squares (PLS) regression, Cubist, support vector machine (SVM) regression and random forest (RF) regression algorithms. After the first derivative Savitzky-Golay smoothing, Bruker spectroscopies with both soil particle sizes yielded ‘excellent models’, with SVM predicting Smax values with high accuracy (RPIQVal = 4.50 and 4.25 for the spectral libraries of the ball-milled and <2mm samples, respectively). In comparison, the Agilent handheld spectrometer produced spectra with more noise and less resolution than the Bruker benchtop spectrometer. Unlike Bruker, for Agilent MIR spectroscopy, more homogeneous samples after ball-milling resulted in a higher accurate Smax prediction. For Agilent spectroscopy of ball-milled samples, an ‘approximate quantitative model’ (RPIQVal = 2.74) was obtained from the raw spectra using the Cubist algorithm. However, for Agilent spectroscopy of < 2 mm samples, the best performing Cubist algorithm can only achieve a ‘fair model’ (RPIQVal = 2.23) with the potential to discriminate between high and low Smax values.

              The results suggest that the Bruker bench-top spectrometer can predict the Langmuir Smax value with high accuracy without the need to ball-mill samples, highlighting the availability of the MIR spectrometer as a rapid alternative method for understanding soil P sorption capacity. However, for handheld spectrometers, the Agilent instruments can only make approximate quantitative predictions of Smax for ball milled samples. For <2mm samples, Agilent can only be used to classify low and high sorption capacity soils.

How to cite: Yang, S., White, B., Regan, F., Kent, N., Hall, R., de Santana, F., and Daly, K.: Prediction of soil phosphorus sorption capacity in agricultural soils using mid-infrared spectroscopy. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3186, https://doi.org/10.5194/egusphere-egu24-3186, 2024.

This study employs the PHYGROW simulation model to assess the 40-year dynamics of arid grassland in Jordan, focusing on the Leaf Area Index (LAI) as a pivotal indicator of vegetation health. The observed results reveal a notable decline in LAI over the study period, with the highest recorded value in 2005 (2.27) and a subsequent reduction to 1.68 in 2021. Rigorous statistical analyses, including regression analysis, confirm the significance of this downward trend, prompting further investigation into potential contributing factors such as changes in climate, land use, and soil conditions.

 

Interannual variability analysis identifies specific years marked by noteworthy LAI fluctuations, providing insights into the dynamic responses of the arid grassland ecosystem. Comparison with concurrent climate data underscores the intricate relationship between LAI trends and environmental variables. The study emphasizes the importance of continuous monitoring and understanding the underlying drivers of vegetation dynamics in arid regions.

The observed decrease in LAI holds implications for the overall health and resilience of the ecosystem, highlighting the need for informed decision-making in sustainable land management practices. These findings contribute significantly to the broader understanding of arid land dynamics, guiding future research and collaborative efforts with experts in related fields. Such collaborations are essential for enhancing the robustness and applicability of the results, ultimately informing conservation and resource management strategies tailored to the unique challenges of arid environments.

How to cite: Alhamad, M. N. and Abdullah, S.: Simulation Modeling of Arid Grassland Dynamics in Jordan: A 40-Year Analysis of Leaf Area Index Trends, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4117, https://doi.org/10.5194/egusphere-egu24-4117, 2024.

In the Sahel region, landscape configuration is closely linked to factors such as climate, ecology, soil composition, agronomy, livestock, and biology. Over the past decades, significant changes in these factors have been observed, including shorter rainy seasons, irregular precipitation, a decrease in biomass productivity, and rapid population growth, negatively impacting local agricultural and pastoral systems. In response to this pressure, mitigation strategies have been implemented to contribute to the improvement of local food, nutritional, and economic security. Agroforestry systems, involving a combination of trees, shrubs, crops, and animals in the same plot, represent one of these strategies. Therefore, characterizing these systems in the current context of climate change is crucial for sustainable natural resource management.

In this study, three agroforestry landscapes of the Senegalese Sahel were described, spanning a bioclimatic gradient from the Louga region (Ouarkhokh) in the north to the Fatick region (Niakhar) in the center, and the Tambacounda region (Koussanar) in the south. The data utilized included satellite imagery synthesis (Sentinel-2 and Spot), landscape variables (rainfall, evapotranspiration, biomass, and vegetation), spectral indices (NDVI, NDRE, GNDVI), and field data on land use and woody cover. The methodology consisted of three main approaches: (i) landscape stratification involving Sentinel image segmentation in 2021, selection of relevant landscape variables, and mixed discriminant factor analysis to establish landscape heterogeneity; (ii) land use and land cover mapping through supervised pixel-based classification using a Random Forest (RF) machine learning classifier with 500 trees; (iii) floristic diversity analysis by assessing floristic composition and calculating diversity indices (i.e., Shannon, Pielou, and Simpson indices).

Landscape stratification identified seven classes with distinct landscape characteristics. Classes (1, 2, and 4) in the Ouarkhokh site had lower average biomass, rainfall, and actual evapotranspiration values than classes (3 and 4) in the Niakhar site. Similarly, classes (5, 6, and 7) in the Koussanar area had higher average biomass, rainfall, and actual evapotranspiration values than the first two sites. Land use mapping showed vegetation predominance in the Ouarkhokh site, significance in the Koussanar site, and low presence in the Niakhar area. Other identified units (cultivated areas, built-up areas, water, and bare land) were dominant in the Niakhar area, present in the Koussanar site, and low in the Ouarkhokh area. Likewise, vegetation dominated in classes 1, 5, 6, and 7. Class 1 was exclusively found in Ouarkhokh, while classes 5, 6, and 7 were located in the Koussanar site. The majority of cultivated surfaces were in class 3, exclusively located in the Niakhar area. Species richness was higher in the Niakhar area (60 species, 21 families) and lower in the Koussanar area (56 species, 16 families) and Ouarkhokh area (31 species, 13 families). This landscape distribution of land use, landscape classes, and identified species highlights the influence of anthropogenic, soil-related, and climatic factors specific to each site.

How to cite: sylla, D., Diouf, A. A., and Ndao, B.: Variation of woody plants diversity and land use along a bioclimatic gradient of agroforestry landscapes in Senegalese Sahel, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5133, https://doi.org/10.5194/egusphere-egu24-5133, 2024.

The landscape-scale evaluation and modeling of the impact of agricultural management and climate change on soil-derived ecosystem services requires soil information at a spatial resolution addressing individual agricultural fields. A pattern recognition approach is presented that generates a nationwide data product. It agglomerates the multivariate soil parameter space into a limited number of functional soil process units (SPUs) that facilitate operating agricultural process models. Each SPU is defined by a multivariate parameter distribution along its depth profile from 0 to 100 cm. It has a depth resolution of 1 cm and a spatial resolution of 100 m. The methodological approach is based on an unsupervised classification procedure involving remote sensing, cluster analysis, and machine learning. It accounts for differences in variable types and distributions and involves genetic algorithm optimization to identify those SPUs with the lowest internal variability and maximum inter-unit difference with regards to both, their soil characteristics and landscape setting. The high potential of the method is demonstrated for the agricultural soil landscape of Germany. It can be applied to other landscapes and ecosystem contexts.

How to cite: Ließ, M.: A pattern recognition approach to generate soil process units for ecosystem modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5461, https://doi.org/10.5194/egusphere-egu24-5461, 2024.

EGU24-5750 | ECS | Orals | ITS1.23/SSS0.1.4

Identifying landscape hot and cold spots of soil greenhouse gas fluxes by combining field measurements and remote sensing data 

Elizabeth Wangari, Ricky Mwanake, Tobias Houska, David Kraus, Gretchen Gettel, Ralf Kiese, Lutz Breuer, and Klaus Butterbach-Bahl

Upscaling chamber measurements of soil greenhouse gas (GHG) fluxes from point scale to landscape scale remain challenging due to the high variability in the fluxes in space and time. This study measured GHG fluxes and soil parameters at selected point locations (n = 268), thereby implementing a stratified sampling approach on a mixed-landuse landscape (∼ 5.8 km2). Based on these field-based measurements and remotely sensed data on landscape and vegetation properties, we used random forest (RF) models to predict GHG fluxes at a landscape scale (1 m resolution) in summer and autumn. The RF models, combining field-measured soil parameters and remotely sensed data, outperformed those with field-measured predictors or remotely sensed data alone. Available satellite data products from Sentinel-2 on vegetation cover and water content played a more significant role than those attributes derived from a digital elevation model, possibly due to their ability to capture both spatial and seasonal changes in the ecosystem parameters within the landscape. Similar seasonal patterns of higher soil/ecosystem respiration (SR/ER–CO2) and nitrous oxide (N2O) fluxes in summer and higher methane (CH4) uptake in autumn were observed in both the measured and predicted landscape fluxes. Based on the upscaled fluxes, we also assessed the contribution of hot spots to the total landscape fluxes. The identified emission hot spots occupied a small landscape area (7 % to 16 %) but accounted for up to 42 % of the landscape GHG fluxes. Our study showed that combining remotely sensed data with chamber measurements and soil properties is a promising approach for identifying spatial patterns and hot spots of GHG fluxes across heterogeneous landscapes. Such information may be used to inform targeted mitigation strategies at the landscape scale.

How to cite: Wangari, E., Mwanake, R., Houska, T., Kraus, D., Gettel, G., Kiese, R., Breuer, L., and Butterbach-Bahl, K.: Identifying landscape hot and cold spots of soil greenhouse gas fluxes by combining field measurements and remote sensing data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5750, https://doi.org/10.5194/egusphere-egu24-5750, 2024.

EGU24-5949 | ECS | Posters on site | ITS1.23/SSS0.1.4

The Joint FAO/IAEA Center and the Soil Fertility Project: Integrating Nuclear and Related Techniques for Modelling to Support Practical Decision Management Support 

Magdeline Vlasimsky, Gerd Dercon, Hami Said Ahmed, Sarata Daraboe, Yusuf Yigini, Yuxin Tong, Yi Peng, Franck Albinet, Maria Heiling, and Christian Resch

The Soil Fertility (SoilFer) project, led by the Land and Water Division at FAO, seeks to enhance agricultural practices and resilience globally, starting with five countries (Guatemala, Honduras, Zambia, Kenya, and Ghana). The project collaborates with governments and relevant national partners to establish comprehensive national monitoring and mapping systems for soil management, catering to the diverse needs of agriculture stakeholders. The Soil and Water Management Laboratory at the Joint FAO/IAEA Center serves as a crucial hub for advancing research and technical expertise in soil and water management using nuclear and related techniques. Through its multifaceted approach in collaboration with the Land and Water Division, the laboratory contributes significantly to the SoilFer project, through the development and implementation of technical training programs for and expert advising on the application of Mid-Infrared Spectroscopy (MIRS), Cosmic Ray Neutron Sensor (CRNS), and Gamma Ray Spectroscopy (GRS) to soil monitoring and mapping.

The integration of MIRS, CRNS, and GRS technologies within the SoilFer project forms a robust framework for soil monitoring and mapping, as MIRS has been shown to provide detailed insights into soil composition and carbon content, CRNS offers real-time data on soil moisture dynamics, and GRS contributes to the analysis of radioactive isotopes and elemental composition. Given the integrated nature of landscape processes, the adoption of technological approaches must mirror this complexity. Interconnected ecological, hydrological, and geological processes within landscapes necessitate a holistic and integrated technological framework. This approach ensures that diverse data streams, derived from technologies such as remote sensing, geographic information systems (GIS), and advanced sensor networks, can be harmoniously synthesized. Only through such integration can a comprehensive understanding of landscape dynamics be achieved, facilitating informed decision-making and sustainable management practices across multifaceted environmental systems. The project emphasizes the seamless integration of these advanced technologies with soil monitoring and mapping systems, ensuring a comprehensive and effective approach to soil management practices, while improving national capacity and stakeholder engagement in data-based decision making. 

The key objectives of the SoilFer project encompass the development of robust national soil information systems, the implementation of decision support systems targeting soil health, and the promotion of sustainable soil management practices. By fostering collaboration and knowledge exchange, the project aspires to build technical, increase agricultural resilience and ensure food security in the participating countries.

How to cite: Vlasimsky, M., Dercon, G., Said Ahmed, H., Daraboe, S., Yigini, Y., Tong, Y., Peng, Y., Albinet, F., Heiling, M., and Resch, C.: The Joint FAO/IAEA Center and the Soil Fertility Project: Integrating Nuclear and Related Techniques for Modelling to Support Practical Decision Management Support, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5949, https://doi.org/10.5194/egusphere-egu24-5949, 2024.

EGU24-6126 | Posters on site | ITS1.23/SSS0.1.4

NewLife4Drylands Protocol for dryland restoration in Protected Areas: an innovative tool to support restoration activities. 

Serena D'Ambrogi, Francesca Assennato, Rocco Labadessa, Paolo Mazzetti, Valentina Rastelli, Nicola Riitano, and Cristina Tarantino

Land degradation processes have experienced a significant increase in recent decades, a trend that is projected to escalate further in the absence of any intervention. The need of adopting practices to contain, mitigate and restore degraded land have been stressed also by the new European Mission 'A Soil Deal for Europe'. To guide and support restoration actions, through a common and effective framework, an efficient monitoring approach and an adaptive ecological restoration process is needed. 

The NewLife4Drylands LIFE project provides a Protocol for design, implementation, and maintenance of restoration activities based on Nature-Based Solutions (NBS) within drylands. The Protocol, developed following the principles and inputs of some international restoration standards (SER, IUCN), is based on the identification and monitoring of degradation processes exploiting remote sensing capabilities, with the aim to integrate data derivation procedures into ecological restoration and maintenance activities. The Protocol is supported by a Decision-Making web-tool guiding trough the degradation processes, NBS along with indices/indicators with the aim to reduce the knowledge effort and helps in prioritizing options. 

The Newlife4drylands experience highlighted the heterogeneity and complexity of degradation processes, as resulted from a selected set of degraded pilot sites within Mediterranean Protected Areas, together with the issue for harmonization and standardization of ecological/physical indicators, especially those derived from satellite observations, when used as proxies of land degradation. The integrated use of both available field data (for short-term monitoring) and satellite data (for medium and long-term monitoring) have been explored to identify indicators for evaluating the effectiveness of planned restoration actions. This approach is geared, towards fostering adaptive and collaborative management of the ecological restoration process. 

Therefore, the Protocol acts as support tool for decision-makers, including public administration of Protected Areas, as well as technicians and planners. The proposed approach aims to raise awareness about the needs of drylands and opportunities provided by NBS. It serves as a guide for the identification of specific/local NBS for the restoration of drylands, beginning with the identification of degradation processes.

How to cite: D'Ambrogi, S., Assennato, F., Labadessa, R., Mazzetti, P., Rastelli, V., Riitano, N., and Tarantino, C.: NewLife4Drylands Protocol for dryland restoration in Protected Areas: an innovative tool to support restoration activities., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6126, https://doi.org/10.5194/egusphere-egu24-6126, 2024.

EGU24-6475 | Posters on site | ITS1.23/SSS0.1.4

Introducing the ’miniRECgap’ package with GUI-supported R-scripts for simple gap-filling of Eddy Covariance CO2 flux data 

Alina Premrov, Jagadeesh Yeluripati, and Matthew Saunders

The Eddy covariance (EC) is a well-known technique used (among others) to investigate the ecosystem exchange of greenhouse gasses (GHGs) between the biosphere and the atmosphere (Burba et al., 2007), often required in studies on soil-plant-atmosphere interactions and GHG emissions/removals from different soil systems. The long data records from EC measurements often experience data gaps due to various reasons (BaldocchiI, 2003) resulting in  many gap-filling methods being developed over the past decades. This study is introducing the new ’miniRECgap’ (Premrov, 2024) computational tool, which is using so-called ‘classic’, traditional robust and validated modelling approaches for gap-filling the missing EC CO2 flux measurements,  based on the application of environmental temperature and light response functions (Lloyd and Taylor, 1994; Rabinowitch, 1951) in combination with empirical/semi-empirical parameter-optimisation. ‘miniRECgap’ is a very small R package that operates in a user-friendly way via GUI (Graphical User Interface) supported scripts. It is purposely designed to be simple, operating in only 5 steps. The application of ‘miniRECgap’ will be demonstrated using EC CO2 flux data from an Irish peatland site Clara Bog. Due to its simplicity, it is thought that the new tool may be beneficial for new R users and that it may allow for easier and less time-consuming testing of the potential suitability of ‘classic’ empirical/semi-empirical gap-filling on different datasets.

 

Acknowledgements

The authors are grateful to the Irish Environmental Protection Agency (EPA) for funding the CO2PEAT project (2022-CE-1100) under the EPA Research Programme 2021-2030.

 

References

BaldocchiI, D.D. (2003) Assessing the eddy covariance technique for evaluating carbon dioxide exchange rates of ecosystems: past, present and future.  9, 479-492.

Burba, G., Anderson, D., Amen, J., (2007) Eddy Covariance Method: Overview of General Guidelines and Conventional Workflow, AGU Fall Meeting Abstracts, pp. B33D-1575.

Lloyd, J., Taylor, J.A. (1994) On the temperature dependence of soil respiration. Functional Ecology 8, 315-323.

Premrov, A., (2024) miniRECgap. R package  with GUI suported scripts for gap-filling the of Eddy Covariance CO2 flux data.  Copyright: Trinity College Dublin. URL:  'miniRECgap package will be uploaded on GitHub in near future'.

Rabinowitch, E.I. (1951) Photosynthesis and Related Processes. Interscience Publishers.

How to cite: Premrov, A., Yeluripati, J., and Saunders, M.: Introducing the ’miniRECgap’ package with GUI-supported R-scripts for simple gap-filling of Eddy Covariance CO2 flux data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6475, https://doi.org/10.5194/egusphere-egu24-6475, 2024.

EGU24-6832 | ECS | Posters on site | ITS1.23/SSS0.1.4

A Comprehensive Assessment of the AquaCrop Model in drylands: Performance Examination and Sensitivity Analysis 

Ahmed S. Almalki, Marcel M. El Hajj, Kasper Johansen, and Matthew F. McCabe

The AquaCrop model is a powerful tool for crop monitoring, providing a daily estimation of soil-crop-atmosphere dynamics. The model requires a substantial number of input variables and parameters, highlighting the need for identifying those that significantly influence model outputs. Sensitivity analysis is a vital method for this purpose. A key objective of this study is to examine the performance of the AquaCrop model in simulating wheat yield and irrigation water requirement in drylands under two scenarios: first running the model employing a minimal amount of in situ data, and second using all available in situ data. A second focus is to analyze the sensitivity to all crop and soil related input variables and parameters. To do this, a pilot-scale study was undertaken, focusing on a commercial farm in the Al-Jouf province of Saudi Arabia. The farm comprised 200 center-pivot fields of mainly wheat crops. In situ data was collected to calibrate the model for two consecutive growing seasons (2019-2020 and 2020-2021). Using the variance-based Sobol technique, the sensitivity of the AquaCrop model outputs, particularly wheat yield and irrigation water requirement, to crop and soil related input variables and parameters was examined, as were the influential and non-influential inputs on these outputs. Results showed that the second scenario (all data) outperformed the first (minimal data), demonstrating more accurate wheat yield predictions with rRMSE values of 17% and 21% for the 2019-2020 and 2020-2021 growing seasons, respectively. Regarding irrigation water requirement estimations, the second scenario also exhibited lower rRMSE values of 20% and 19% for the same growing seasons. Results also demonstrated that the sensitivity indices of variables and parameters varied with model outputs and growing seasons. By synthesizing inputs sensitivities under different conditions, the influential input variables and parameters were distinguished. Overall, six variables and parameters held significant influence on the analyzed model outputs based on their total-order sensitivity indices. These included duration from sowing to senescence (senescence), duration from sowing to harvesting (maturity), duration from sowing to yield formation (HIstart), base temperature below which growth does not progress (Tbase), minimum air temperature below which pollination failure begins (Tmin_up), and shape factor describing reduction in biomass production (fshabe_b). It was revealed that most variables and parameters were non-influential, which might allow them to be fixed within their ranges to optimize model calibration. The research represents the performance assessment and sensitivity analysis of the AquaCrop model over a desert farming system and offers guidelines for model calibration by delivering information on influential and non-influential input variables and parameters.

How to cite: Almalki, A. S., El Hajj, M. M., Johansen, K., and McCabe, M. F.: A Comprehensive Assessment of the AquaCrop Model in drylands: Performance Examination and Sensitivity Analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6832, https://doi.org/10.5194/egusphere-egu24-6832, 2024.

EGU24-8466 | Posters on site | ITS1.23/SSS0.1.4

Metamodel simulation of carbon fluxes across an eroding and pristine blanket bog in Scotland 

Bhaskar Mitra, Jagadeesh Yeluripati, James Cash, Linda Toca, Mhairi Coyle, and Rebekka Artz

Accurately quantifying carbon dynamics in peatlands is critical to assess their role in regulating global climate. Within hotspots of peatland degradation, such as in Europe and South-east Asia, skilful assessment of the spatial and temporal impacts of climate change and different land management options is required to meet emissions reductions targets and improve regional management planning.

To address this challenge, a random forest-based metamodel was evaluated to assess its utility in simulating various greenhouse gas (CO2) emission components, including Net Ecosystem Exchange (NEE), Gross Primary Productivity (GPP), and Ecosystem Respiration (ER) across two Scottish peatlands. The metamodel mimicked the complex Wetland-DNDC model at a higher level of abstraction with increased efficiency and lower computational time.

While Wetland-DNDC also simulates NEE, GPP and ER, it typically involves a considerable number of parameters related to soil properties, climate data, vegetation characteristics, biogeochemical processes, hydrology, nutrient cycling, and microbial activity. Many of these parameters (more than 100) are challenging to measure in the field, and literature values are often adopted, which may not necessarily reflect local site conditions. In essence, this multidimensional parameter space introduces high uncertainties in modelling carbon fluxes.

In contrast, random forest-based metamodel preserved the key relationships between NEE and input variables (air and soil temperature, water table, precipitation, vegetation, and soil properties) as described in the Wetland-DNDC model with lower parameter requirements (less than 20) and increased accuracy. Similar unique relationships were established for GPP and ER. The random forest-based metamodel represented the Wetland-DNDC model  within the spectrum of input values and parameters across which it was simulated.

The simulation was conducted in two locations across Scotland with contrasting contemporary carbon dynamics: a near natural blanket bog in Cross Lochs, Forsinard, currently functioning as a resilient net carbon dioxide sink (UK-CLS; Lat. = 58.37, Long. = -3.96; altitude = 207 m) and an eroding oceanic blanket bog located in the Cairngorms, currently net emitting carbon dioxide (UK-BAM; Lat. = 56.92, Long. = -3.15, altitude = 642 m). The simulation was validated against eddy covariance flux measurements under varying climate conditions.

In contrast to Wetland-DNDC (R2 = 0.43), the metamodel provided a much-improved fit to the 1:1 line for NEE (R2 = 0.83). Model accuracy was slightly lower for the former (RMSE = 0.72) compared to its metamodel version (RMSE = 0.699). Similar trends were observed for GPP and ER simulations. At a monthly resolution, Wetland-DNDC-derived NEE, GPP, and ER consistently deviated by more than 20% from the eddy covariance-derived estimates, whereas its metamodel version showed deviations of less than 10%. Currently, work is in progress to incorporate management and drought simulation within a metamodel framework, as well as to upscale carbon fluxes from tower to landscape resolution.

The simulation of carbon fluxes using the metamodel-based approach holds the promise of enhancing emission reporting to Tier 3 standards and offers a hopeful avenue for modelling carbon dynamics in peatlands.

How to cite: Mitra, B., Yeluripati, J., Cash, J., Toca, L., Coyle, M., and Artz, R.: Metamodel simulation of carbon fluxes across an eroding and pristine blanket bog in Scotland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8466, https://doi.org/10.5194/egusphere-egu24-8466, 2024.

EGU24-10001 | Orals | ITS1.23/SSS0.1.4

MIR spectroscopy combined with meteorological data can estimate soil compaction risks in top and subsoils. 

Felipe de Santana, Rebecca Hall, Longnan Shi, Victoria Lowe, Jim Hodgson, and Karen Daly

Soil compaction is an important physical characteristic that affects agricultural productivity by increasing soil density, which reduces the volume of a given soil mass. Due to the higher compaction, plant roots find resistance in penetrating deeply into the soil, limiting their access to essential nutrients and moisture, impacting the plant health with lower levels of N, P and K, resulting in lower productivity. Soil compaction can also reduce soil porosity, aeration, carbon mineralisation/sequestration and increasing the production of greenhouse gases through denitrification in anaerobic sites. Besides that, soil compaction can cause surface runoff and erosion, increasing the risk of flooding and soil loss. A partial recuperation of compacted soils is an expensive and labour-intensive task. In addition, agricultural land expansion for crops is limited. Hence, mapping agricultural areas at risk of soil compaction is essential to implement strategies to mitigate the adverse effects of soil compaction.

Soil particle size and soil drainage were used to classify topsoil's (T) compaction risk class. For subsoil (S) soils (after horizon A), the subsoil particle size, packing density (bulk density + 0.009 * clay (%)), soil drainage and field capacity days were used to estimate the compaction risks. The main problem of this strategy is that these analyses are expensive and time-consuming, i.e., soil particle size analysis requires an average time of 1 month per 100 samples and costs ~ 40.00 per sample. Bulk density analysis costs ~ € 7.00 per sample and is also time-consuming; consequently, bulk density values are mainly predicted using pedo-transfer functions in mapping studies.

To speed up the analysis and minimise the costs, vibrational spectroscopy combined with chemometrics was used to determine soil particle size and bulk density. Both parameters were combined with field capacity days (obtained from 104 national wide meteorological stations) and drainage class (obtained from Irish - Environmental Protection Agency) to map soil compaction risk areas in the northern half of the Republic of Ireland with a resolution of 4 km2 (2x2km) and 1 km2 grid for regional and periurban regions, respectively (Tellus achieve). To confidentially map these regions, spectral control charts based on PCA were used to identify unrepresentative sample spectra based on the spectral models used. Only samples classified as representative were predicted by the spectral models. Using this strategy, we could predict ~ 90% (T) and ~66% (S) compaction risks in non-peat soils. The prediction results showed that ~33% (T) and ~43% (S) were classified as high risks of compaction, ~19% (T) and ~23% (S) as moderate, and ~37% (T) and <1% (S) as low risks or other classes.

How to cite: de Santana, F., Hall, R., Shi, L., Lowe, V., Hodgson, J., and Daly, K.: MIR spectroscopy combined with meteorological data can estimate soil compaction risks in top and subsoils., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10001, https://doi.org/10.5194/egusphere-egu24-10001, 2024.

EGU24-10906 | Posters virtual | ITS1.23/SSS0.1.4

SDG 15.3.1 indicator at local scale for monitoring land degradation in protected areas 

Cristina Tarantino, Mariella Aquilino, Saverio Vicario, Rocco Labadessa, Vito Emanuele Cambria, Christos Georgiadis, Marcello Vitale, Francesca Assennato, and Paolo Mazzetti

In the framework of the NewLife4Drylands LIFE Preparatory project (LIFE20 PRE/IT/000007, 2021-2024) the estimation of SDG 15.3.1 indicator [1], adopted in the UNCCD’s Good Practice Guidance [2], was applied for evaluating Land Degradation (LD) in different Mediterranean Protected Areas (PA). To effectively support PAs managers, joint effort was made in the evaluation of SDG 15.3.1 indicator at the local scale by using satellite Remote Sensing data in the computation of the three main sub-indicators as trend in Land Cover (LC), Primary Production (PP) and Soil Organic Carbon (SOC) stock. Where feasible, local scale sub-indicators were not sourced from open-access global/European databases due to their lack of accuracy at the site scale [3]. LD was estimated not only for the whole PA but also for specific LC classes of interest, considering additional sub-indicators related to pressures and threats affecting the class. This study focuses on the dryland Alta Murgia (IT9120007) PA, in southern Italy, and the wetland Nestos River Delta (GR1150001) PA, in Greece. For Alta Murgia site, featuring semi-natural dry grassland habitats of community interest that are frequently subjected to fire events during the summer season, the Burn Severity (BS) index was included. BS trends were measured by assessing the difference in pre/post–fire Normalized Burn Ratio (NBR) index from Landsat data during summer. Baseline data from 2004, coinciding with the establishment of a National Park within PA, was compared with 2018 for validating field data availability. Nestos River Delta hosts the largest natural riparian forest in Greece and is frequently subjected to hydrological cycle modifications, involving water scarcity due to both inappropriate river management and climate change, in turn hampering the transport of nutrient-rich sediments and the enrichment of soils being at risk of aridification. Within this framework, Hydroperiod and Soil Salinity indices were considered for LD and specific impacts on aquatic vegetation LC. Baseline data from 2017, after the dry climate conditions of 2016-2017, was compared with 2021 for validating field data availability. Both in Alta Murgia and Nestos, LC mappings were obtained by a data-driven pixel-based approach considering Landsat/Sentinel-2, respectively, multi-seasonal imagery and a multi-class Support Vector Machine (SVM) classifier trained with data from in-field campaigns and historical orthophotos interpretation. Time series of MSAVI from Landsat (which replaced standard NDVI for its soil correction benefits [4]) and PPI from Sentinel-2 by Copernicus services, respectively, were used to track grassland PP trends. Lastly, for SOC stock trends, the open-source Trends.Earth QGIS plugin [5], incorporating customized LC data and global SoilGrids product, was adopted to supplement local data limitations. According to its specification, the SDG 15.3.1 indicator was computed by integrating all the sub-indicators according to the principle “one out, all out” obtaining the 3-classes output mapping (Degradation, Improvement, Stable). The findings can support the monitoring and evaluation of LD, guiding protective measures aligned with the Agenda 2030 for Sustainable Development. They, also, highlight the importance of the integration of local scale data and sub-indicators within the UNCCD methodology.

References

[1] https://unstats.un.org/sdgs/metadata/files/Metadata-15-03-01.pdf

[2]https://www.unccd.int/publications/good-practice-guidance-sdg-indicator-1531-proportion-land-degraded-over-total-land

[3] https://doi.org/10.3390/rs13020277

[4] https://doi.org/10.3390/rs12010083

[5] http://trends.earth/docs/en

 

How to cite: Tarantino, C., Aquilino, M., Vicario, S., Labadessa, R., Cambria, V. E., Georgiadis, C., Vitale, M., Assennato, F., and Mazzetti, P.: SDG 15.3.1 indicator at local scale for monitoring land degradation in protected areas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10906, https://doi.org/10.5194/egusphere-egu24-10906, 2024.

EGU24-11219 | ECS | Posters on site | ITS1.23/SSS0.1.4

Exploring soil organic carbon dynamics through a multi-model simulation of multiple long-term experiments  

Matteo Longo, Ilaria Piccoli, Antonio Berti, Michela Farneselli, Vincenzo Tabaglio, Domenico Ventrella, Samuele Trestini, and Francesco Morari

Agricultural system models are widely recognized as valuable tools for identifying best management practices and addressing the challenges posed by climate change. In this context, the use of model ensembles has been recently recommended for their enhanced performance and accuracy. However, assessing their effectiveness over a large geographical area, such as national scale is often currently lacking. This study focuses on simulating soil organic carbon (SOC) dynamics using an ensemble of models comprising DSSAT, CropSyst, EPIC, and APSIM models, utilizing data derived from five Long-Term Experiments (LTEs) spread across a north-to-south pedoclimatic range transect in Italy. This region is of particular importance as it represents a significant hotspot for climate change. The LTEs featured a robust array of 63 unique experimental protocols, incorporating variation effect in fertilization rates, cropping rotations, and tillage prescriptions. This resulted in a total of 2184 years of simulated data for each model. The dataset employed included SOC stocks and crop yield and biomass. Models underwent independent calibration, with crop and SOC parameters selected based on expert knowledge. Main crop cultivars, such as maize, soybean, sugarbeet, and wheat, were further categorized and calibrated by maturity classes. A similar approach was used for cover crops. The extensive dataset enabled a nuanced exploration of the models’ performance across varied agro-ecological contexts. The models proved capable of accurately reproducing the varied pedo-climatic conditions of the Italian peninsula, contributing to the advancement of our understanding of SOC dynamics.

How to cite: Longo, M., Piccoli, I., Berti, A., Farneselli, M., Tabaglio, V., Ventrella, D., Trestini, S., and Morari, F.: Exploring soil organic carbon dynamics through a multi-model simulation of multiple long-term experiments , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11219, https://doi.org/10.5194/egusphere-egu24-11219, 2024.

EGU24-11605 | Orals | ITS1.23/SSS0.1.4

A Geospatial Overview of Agricultural Long-Term Field Experiments across Europe 

Cenk Donmez, Carsten Hoffmann, Nikolai Svoboda, Tommy D'Hose, Xenia Specka, and Katharina Helming

Long-Term Field Experiments (LTEs) are agricultural infrastructures for studying the long-term effects of different management practices and soil and crop properties in changing climate conditions. These experiments are essential to examine the impact of management and environment on crop production and soil resources on different soil textures and types. Some of those LTEs have average times of 20-50 years, even more than 100 years. These infrastructures are thus scientific heritages with high values of agricultural data; however, LTE-related information was difficult to find since it was scattered. To close this gap, we developed a geospatial data infrastructure, including an LTE overview map to compile and analyze the meta-information of the LTEs across Europe. The map provides a spatial representation of LTEs and the meta-information, collected by extensive literature review and factsheets in collaboration with BonaRes and EJPSoil projects, clustered in different categories (management operations, land use, duration, status, etc.) (Grosse et al. 2021; Donmez et al., 2022; Blanchy et al., 2023; Donmez et al., 2023). A threshold filter with a minimum duration of 20 years was applied, which results in a total of 500 LTEs across Europe and included into the map. The clusters of LTEs were geospatially analyzed to provide inputs for the agricultural sector, scientists, farmers and policy-makers. The fertilization treatment was the major research theme of collected and studied LTEs, followed by crop rotation and tillage trials. Bringing the meta information of dispersed LTEs through the development of the LTE overview map is expected to help developing a mutual management framework of efficient agricultural production by revealing the LTE potential internationally. This will contribute to scaling up the agricultural practices from site to landscape level for increasing the climate change adaptation to agricultural yield and management.

References

Donmez C., Schmidt M., Cilek A., Grosse M., Paul C., Hierold W., Helming K., (2023): Climate Change Impacts on Long-Term Field Experiments in Germany. https://doi.org/10.1016/j.agsy.2022.103578. Vol.205, 103578. Agricultural Systems.

Blanchy G., D’Hose T., Donmez C., Hoffmann C., Makoschitz L., Murugan R., O’Sullivan L., Sanden T., Spiegel A., Svoboda N., Boltenstern S.Z., Klummp K., (2023): An open-source database of European long-term field experiments. https://doi.org/10.1111/sum.12978  Soil Use and Management

Donmez C., Blanchy G., Svoboda N., D’Hose T., Hoffmann C., Hierold W., Klummp K., (2022): Provision of the metadata of European Agricultural Long-Term Experiments through BonaRes and EJP SOIL Collaboration. Data in Brief. https://doi.org/10.1016/j.dib.2022.108226.

Grosse, M., Ahlborn, M.C., Hierold, W. (2021): Metadata of agricultural long-term experiments in Europe exclusive of Germany. Data in Brief 38, https://doi.org/10.1016/j.dib.2021.107322

How to cite: Donmez, C., Hoffmann, C., Svoboda, N., D'Hose, T., Specka, X., and Helming, K.: A Geospatial Overview of Agricultural Long-Term Field Experiments across Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11605, https://doi.org/10.5194/egusphere-egu24-11605, 2024.

EGU24-12129 | Posters on site | ITS1.23/SSS0.1.4

Soil water holding capacity as descriptor of soil health at district scale – a sensitivity study 

Thomas Weninger, Irene Schwaighofer, Florian Darmann, Thomas Brunner, and Peter Strauss

The proposal for the European Soil Monitoring Law includes an integrated value of soil water holding capacity to be determined as a proxy for soil quality for whole soil districts. As this is a relatively new but interesting approach, a number of details of the assessment procedure remain open at the current stage of formulation. The aim of this study is to quantify the effects of the choice of different options on the overall result, focusing on the delineation of soil districts in different sizes, the detailed definition of the respective soil property, and the treatment of sealed areas.

High-resolution data for soil hydrological properties for two Austrian provinces are used as a basis, including different approaches to calculate soil water holding capacity. The size of the study area corresponds to the maximum size of a soil district as proposed. Thus, a variation of three size levels is possible, namely the whole area, major river catchments, and agro-geographical sub-units. The term soil water holding capacity is basically defined in the proposed EU Directive, but several options for its determination are possible. We used two different pedotransfer functions to derive soil water holding capacity values and an additional method based on averaging results from randomly located sampling points. Soil sealing is a major threat to hydrological soil functionality, and its assessment over large areas is still not standardized. Here, the European LUISA land use/land cover dataset for 2020 (1 km resolution) and a national dataset with higher resolution are used. Both datasets are optionally overlaid with the Copernicus imperviousness layer involves gradual information about surface imperviousness.

By combining all these factors with each other, different ways were evaluated to determine the target value of soil water holding capacity integrated on a regional scale. Differences in the results and their sensitivity to input variations are quantified to inform policy decisions in the implementation of the European Soil Monitoring Law in the member states.

How to cite: Weninger, T., Schwaighofer, I., Darmann, F., Brunner, T., and Strauss, P.: Soil water holding capacity as descriptor of soil health at district scale – a sensitivity study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12129, https://doi.org/10.5194/egusphere-egu24-12129, 2024.

Soil erosion constitutes an increasing threat to soil productivity and food security. This work describes the potential of using Artificial Neural Networks (ANN) for upscaling soil loss outputs from medium to low scale. The Revised Universal Soil Loss Equation (RUSLE) model was implemented to calculate soil loss rates in two scales in Crete, Greece. Specifically, the RUSLE model was applied in six (6) watersheds across the island using medium spatial resolution satellite images (5m), namely Planetscope. These results were used to feed an ANN model to upscale the mesoscale outputs (5m) to regional outputs (30m-island level). The ANN system was trained using spatial environmental parameters such as the Normalized Difference Vegetation Index, Digital Elevation Model, and topographical slope angle. This "optimized" soil loss derivative later made it possible to compare it with the corresponding final derivative of Crete (regional spatial scale), which emerged from the straightforward processing of RUSLE model with the more "coarse" and generalized data as estimated from the  Landsat-8 satellite images (30m). The statistics revealed that the detailed and high-quality soil loss data, as derived from the upscaling process, provide more precise and reliable results.

How to cite: Alexakis, D. D. and Polykretis, C.: Using Artificial Neural Networks to upscale soil erosion model results from local to regional scale. An example from Crete, Greece., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14678, https://doi.org/10.5194/egusphere-egu24-14678, 2024.

EGU24-15537 | ECS | Orals | ITS1.23/SSS0.1.4

Integrating UAV data and soil-crop modelling for Enhanced Soil Health Monitoring 

Nikolaos-Christos Vavlas, Lammert Kooistra, Fenny van Egmond, and Gerlinde De Deyn

The necessity of soil health monitoring is paramount in reversing soil degradation and promoting sustainable farming. Including cover crops in the crop rotation is one of the sustainable soil management practices contributing to soil health. Cover crops contribute to soil health by nutrient retention and carbon accumulation during their growth and return of organic matter to the soil upon their incorporation. During monitoring, the sampling frequency can change from annual in the case of SOC to weekly or daily for fertilization and irrigation. Remote sensing techniques offer a solution, enabling the monitoring of vegetation over time and space, thereby enhancing our understanding of the impact of cover crops on the main crop. However, this technology makes it possible to see the surface of the field which can assist with the above-ground changes of the system. Process-based modelling and data assimilation can subsequently link the above-ground component with soil functions. In-situ data collection that includes crop characteristics such as biomass and N-uptake is essential both for transforming remote sensing data into crop characteristics and for calibrating models. Using Unmanned Aerial Vehicles (UAVs) can potentially collect data at high frequency, which can be used to enhance soil process modelling. The development of this UAV-based method has the potential to be scaled up to a satellite level in the future.

In our research, we have combined the study of nutrient cycling and the effect of cover crops on soil health. To achieve this, we have used the WOFOST-SWAP-ANIMO model to simulate the varying influence of cover crop monocultures and mixtures on Soil Organic Carbon (SOC) and Nitrogen cycling in a 7-year crop rotation on sandy soil. The model simulates vegetation characteristics such as biomass, leaf area index, and yield, as well as soil moisture and mineral Nitrogen concentrations. This will give us a good estimation of the vegetation input into the soil as well as the nutrient uptake from both cover crops and main crops. Soil sampling is also important to model calibration/validation to be able to simulate the N dynamics of biological activity under the surface. Our findings suggest that the model, in conjunction with UAV data and field sensors, can effectively monitor soil health indicators crucial for field management practice selection, such as the Carbon cycle and Nitrogen use efficiency.

How to cite: Vavlas, N.-C., Kooistra, L., van Egmond, F., and De Deyn, G.: Integrating UAV data and soil-crop modelling for Enhanced Soil Health Monitoring, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15537, https://doi.org/10.5194/egusphere-egu24-15537, 2024.

EGU24-18038 | Orals | ITS1.23/SSS0.1.4

Empowering soil health in Mediterranean environments through collaborative stakeholder engagement: insights from Sardinian Living Lab of the InBestSoil project 

Valentina Mereu, Gianluca Carboni, Alessio Menini, Marta Canu, Marco Dettori, Giulia Urracci, and Serena Marras

Preserving soil health and enhancing the ecosystem services that soil produces is of primary importance in European strategies and policies. More than 60% of the European soils are unhealthy due to unsustainable land use, pollution, climate change, and extreme events. This causes loss of ecosystem services, costing the EU at least €50 billion annually. Collaboration among businesses, policymakers, public administration, and the scientific community is crucial to develop practices that recognize the essential role of soils in sustaining livelihoods, biodiversity, and climate regulation.

In this framework, the Horizon Europe funded project InBestSoil (https://inbestsoil.eu/) aims to co-create a framework for investments in soil health preservation and restoration by developing a system for the economic valuation of the ecosystem services provided by healthy soil and the impacts of soil interventions, and its incorporation into business models and incentives. To achieve this, InBestSoil has selected 7 existing Soil Health Lighthouses (LHs) and 2 Soil Health Living Labs (LLs, in different maturity stages) covering four land uses (agricultural, forestry, urban, mining) across four biogeographic regions over Europe. The LLs are collaborative initiatives focused on co-creating knowledge and innovations, while LHs represent individual sites known for exemplary performance. The LL1, located in Sardinia (Italy), is coordinated by the CMCC Foundation and Agris Sardegna Research Agency. It focuses on Mediterranean agricultural soils and aims addressing the challenges related to climate change and extreme events, soil pollution, land abandonment, and water scarcity. It includes 2 LHs on conservation agriculture managed by Agris and 9 Living Lab Experimental Sites (LLES), which evaluate the introduction of sustainable soil practices. The LHs included in the LL are two Long-Term Experiments (>20 years) on conservation agriculture (reduced and no tillage versus conventional tillage) on durum wheat in rotation with legumes, in soils with different fertility levels that are representative of Mediterranean cereal farming conditions. Conservation agriculture is among the most promising climate-smart agricultural practices because it contributes to both climate change mitigation and adaptation objectives while helping to maintain and increase farmers' incomes. However, it is important both to acquire additional information to assess the medium- to long-term effects of these practices in different environments and cropping systems as well as to disseminate the scientific evidence and support the wider application of these practices in the Mediterranean region.

The LHs aim to provide scientific evidence and disseminate knowledge and experience gained in the long-term application of conservation agriculture in Mediterranean agricultural systems.  Moreover, in the selected 9 LLES, located in different areas and including cereal, olive tree and vineyard farms, soil samplings and analyses are being conducted to measure soil indicators and provide information to assess the economic evaluation of ecosystem services provided by soils managed with sustainable agricultural practices, primarily including conservation agriculture.

We aim to create a permanent space of discussion on the topic of soil health, involving all relevant actors, from farmers to researchers to policy makers, in order to identify common solutions and innovations that can face the economic and environmental challenges the Mediterranean agriculture is facing.

How to cite: Mereu, V., Carboni, G., Menini, A., Canu, M., Dettori, M., Urracci, G., and Marras, S.: Empowering soil health in Mediterranean environments through collaborative stakeholder engagement: insights from Sardinian Living Lab of the InBestSoil project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18038, https://doi.org/10.5194/egusphere-egu24-18038, 2024.

Mountain grasslands play a pivotal role in delivering both economic and cultural ecosystem services, including food production, carbon sequestration, the provision of clean water, and preserving local traditions. However, these ecosystems are facing increasing threats from climate change around the world. Among the main challenges is the intensification of extreme precipitation events. They can aggravate the process of soil erosion and trigger landslides in mountain grasslands, with possible negative consequences on both ecosystems and human activities. However, the high variability of these ecosystems, as well as their wide distribution, makes it complex to adequately map their locations and investigate possible soil erosion hotspots, especially under future scenarios with varied rainfall regimes. In this context, the use of remote sensing technologies and modeling approach could open new frontiers to investigate critical areas and therefore guide mitigation solutions. The satellite Earth Observation (EO) through international space missions, coupled with cloud-based data analysis platforms like Google Earth Engine (GGE), facilitates ecosystem mapping at a resolution and frequency previously inaccessible. Furthermore, the utilization of multi-temporal models for potential soil erosion analysis in present and future scenarios can enhance our understanding of erosion dynamics attributed to climate change. In this research, we first map at high resolution the global mountain grasslands distribution taking advantage of Sentinel-based EO’s products. In such locations, we evaluate the multi-temporal soil erosion dynamics caused by water employing diverse climate scenarios (RUSLE model; 2015 vs. 2070-RCP8.5). Our findings indicate a potential global escalation in soil erosion within mountain grasslands, notably in South America and Africa, alongside identifiable localized hotspots. Remote sensing-based research paired with a modeling approach aimed at mapping critical areas and analyzing environmental challenges in ecosystems is therefore imperative. Such investigations not only delineate vulnerable regions but also guide targeted solutions crucial for safeguarding these ecosystems and their ecosystem services in the face of climate change.

How to cite: Straffelini, E., Luo, J., and Tarolli, P.: Satellite-based remote sensing and multitemporal modeling approach for mapping soil erosion hotspots in global mountain grasslands under climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18161, https://doi.org/10.5194/egusphere-egu24-18161, 2024.

Peatland restoration and rehabilitation action has become more widely acknowledged as a necessary response to mitigating climate change risks and improving global carbon storage. Peatland ecosystems require restoration timespans on the order of decades and thus cannot be dependent upon the shorter-term monitoring often carried out in research projects. Hydrological assessments using geospatial tools provide the basis for planning restoration works as well as analysing associated environmental influences. “Restoration” encompasses applications to pre- and post-restoration scenarios for both bogs and fens, across a range of environmental impact fields. A scoping review was carried out to identify, describe, and categorise current process-based modelling uses in peatlands in order to investigate the applicability and appropriateness of eco- and/or hydrological models for northern peatland restoration. Two literature searches were conducted using the Web of Science entire database in September 2022 and August 2023. Of the final 211 papers included in the review, models and their applications were categorised according to this review’s research interests in 7 distinct categories aggregating the papers’ research themes and model outputs. Key themes emerging from topics covered by papers in the database included: modelling restoration development from a bog growth perspective; the prioritisation of modelling GHG emissions dynamics as a part of policymaking; the importance of spatial connectivity within or alongside process-based models to represent heterogeneous systems; and the emerging prevalence of remote sensing and machine learning techniques to predict restoration progress with little physical site intervention. Based on this assessment, CoupModel, DigiBog, and MPeat2D were calibrated for the case of Abbeyleix Bog, Co. Laois, Ireland (ongoing with results expected before April 2024). The exploration of subsequent simulations to represent varying peatland restoration conditions is discussed from an ecohydrological lens.

How to cite: Silva, M.: Ecohydrological modelling on peatlands: scoping review and application of three process-based models to Irish raised bog restoration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18533, https://doi.org/10.5194/egusphere-egu24-18533, 2024.

Carbon use efficiency has recently been proposed as a central parameter that promotes soil organic carbon storage based on data assimilation with a global soil organic carbon database and a vertical, microbial explicit soil organic carbon model (Tao et al., 2023). In this research, we present a sensitivity study with a vertical soil organic carbon model, COMISSION v2.0 (Ahrens et al., 2020), that not only models microbial interactions explicitly but also represents organo-mineral interactions with a maximum capacity, Qmax, to form mineral-associated organic carbon (MAOC).

The COMISSION model represents the formation of MAOC from microbial necromass and dissolved organic carbon analogous to Langmuir sorption. Empirical studies have provided Qmax parameterizations derived from quantile or boundary line regressions with clay and silt content. For the sensitivity study, we vary Qmax along the full range of observed Qmax values while simultaneously varying carbon use efficiency (CUE). Our results highlight that CUE and Qmax promote soil organic carbon storage to similar degrees along their respective observed ranges. The remaining parameters of the COMISSION model were kept at their calibrated values from a multi-site calibration with soil organic carbon, mineral-associated organic carbon, and radiocarbon profiles (Ahrens et al., 2020). While Qmax and CUE are of similar importance for promoting soil organic carbon storage, they also interact in promoting SOC storage. Higher Qmax values strengthen the promotion of soil organic carbon storage with higher CUE. This positive interaction results from higher microbial necromass with higher CUE and the subsequent association of microbial necromass on mineral surfaces mediated through Qmax. The sensitivity study revealed that CUE is the dominant driver for microbial biomass levels. Qmax affects microbial biomass only to a small degree through 'competition' between mineral surfaces and microbial biomass for dissolved organic carbon. While the effect of Qmax on microbial biomass is small, the relationship between Qmax and microbial biomass is generally negative. At the lower end of the tested range of carbon use efficiencies (CUE < 0.15), further model experiments reveal that imposing a stronger microbial limitation of depolymerization can lead to a negative relationship between CUE and soil organic carbon storage.

Overall, our results highlight that in soil organic carbon models with microbial interactions and a limited capacity to form organo-mineral associations, both processes can be of similar importance in promoting soil organic carbon storage. The current debate in the observational realm, whether there is indeed an upper limit for mineral-associated organic carbon formation, can spark a similar debate in the modeling realm on how to represent mineral-associated organic carbon formation in models mechanistically.

 

References

Ahrens B, Guggenberger G, Rethemeyer J et al. (2020) Combination of energy limitation and sorption capacity explains 14C depth gradients. Soil Biology and Biochemistry, 148, 107912.

Tao F, Huang Y, Hungate BA et al. (2023) Microbial carbon use efficiency promotes global soil carbon storage. Nature, 618, 981-985.

Funding acknowledgment: Bernhard Ahrens has received funding through the AI4SoilHealth project. The AI4SoilHealth project has received funding from the European Union's Horizon Europe research and innovation programme under grant agreement No. 101086179.

How to cite: Ahrens, B. and Chettouh, M. A.: Carbon use efficiency and mineralogical capacity are of similar importance for promoting soil organic carbon stocks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18844, https://doi.org/10.5194/egusphere-egu24-18844, 2024.

EGU24-19814 | ECS | Posters on site | ITS1.23/SSS0.1.4

Performance of the DNDC in Estimating CO 2 and N 2 O emissions of Integrated Crop-Livestock Systems 

Priscila S Matos, Johnny R Soares, Maria C S Carvalho, Beata E Madari, Bruno J R Alves, Claudia P Jantalia, Antônio C R Freitas, Bhaskar Mitraa, and Jagadeesh Yelupirati

Integrated crop-livestock (ICL) systems can have a complex of effects on soil properties that can influence greenhouse gas emissions (GHG). The ICL aim to capture atmospheric CO2 and sequester it in the soil, holding promise for reducing GHG emission intensity from livestock products. Moreover, modeling N2O emissions can help assess the potential impact of N management on the ICL system to optimize the sustainability of agriculture production. Field data were obtained from an ICL experiment of EMBRAPA-Rice and Beans, located on Capivara farm, Santo Antônio de Goiás/GO, Brazil (16°28´S; 49°17´W; 823 m alt.). The ICL experiment was evaluated for four years (2013-2016) with the following crop rotation sequence: pasture-fallow-maize, fallow-soybean, maize-fallow-maize, and beans-fallow. The N2O data was obtained from the 2013-14 season, which was measured in a static chamber during maize cultivation. The experiment consisted of 9 treatments (N sources and rates) with 5 replicates. The N2O was measured in 30 sampling events over almost 100 days. The daily N2O fluxes from the treatments control (No N), urea (UR), calcium ammonium nitrate (CAN), and ammonium sulfate (AS) at an N rate of 150 kg/ha were used to parametrize the DNDC. Model crop and soil parameters were adjusted to better simulate maize production and N2O emission according to observed data. DNDC simulated CO2 emissions, quantified as Net Ecosystem Exchange (NEE), were validated against CO2 emissions derived from eddy-covariance data, using statistical parameters such as R2, RMSE, MAE, and Bias. While data refinement is ongoing, preliminary findings indicate that DNDC shows promise for estimating CO2 emissions IPS under tropical conditions The DNDC had a satisfactory performance in predicting N2O emission in the ICL system, resulting in a significant correlation with the observed data (r = 0.63, p < 0.001), MAE of 0.024, and RMSE of 0.036. The average daily N2O-N emission observed was 0.026 kg ha-1 day-1 and simulated was 0.025 kg ha-1 day-1. The UR, CAN and AS applications showed a peak of N2O emission on 31th day after sowing (2 days after fertilization) corresponding to 0.175, 0.217, and 0.163 kg ha-1 day-1, respectively, where the model simulated N2O peaks of 0.151, 0.123, and 0.173 kg ha-1 day-1. The accumulated N2O emissions were 0.513, 1.148 1.738, and 0.890 kg ha-1 for control, UR, CAN, and AS respectively, in which the simulated by DNDC were 0. 778, 1.612, 1.391, and 1.755 kg ha-1. In general, the model had a good fit with daily N2O emissions, but it tended to overestimate the N2O emission from UR and AS, and underestimate from CAN. Further model parametrization and calibration may be necessary to better predict N2O and CO2 emissions. The DNDC satisfactory simulated the N2O emissions from different N sources applied to ICL system, which can be used to evaluate the potential emissions and mitigation according to N management in ICL.

How to cite: Matos, P. S., Soares, J. R., Carvalho, M. C. S., Madari, B. E., Alves, B. J. R., Jantalia, C. P., Freitas, A. C. R., Mitraa, B., and Yelupirati, J.: Performance of the DNDC in Estimating CO 2 and N 2 O emissions of Integrated Crop-Livestock Systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19814, https://doi.org/10.5194/egusphere-egu24-19814, 2024.

EGU24-19820 | ECS | Posters on site | ITS1.23/SSS0.1.4

The LOESS project to boost soil health literacy across Europe: The case of Italy 

Marco Peli, Arianna Dada, Francesca Barisani, Vera Ventura, Michèle Pezzagno, Stefano Barontini, and Giovanna Grossi

The Horizon Europe project LOESS ‘Literacy boost through an Operational Educational Ecosystem of Societal actors on Soil health’ officially started in June 2023 involving twenty partner organizations in fifteen countries across Europe, lead by the WILA Bonn Science Shop. The final goal of the project is to raise awareness on the importance of soil and of its functions and to increase soil literacy across Europe. To do so, the first step of the project activity is designed to map and connect multiple actors in Communities of Practice (CoPs) at the national level, and engage them to provide an overview of the current level of soil related knowledge and teaching programmes and materials, in order to identify the gap between this material and the educational needs amongst different levels of the society (from pupils to students to citizens).

The Italian chapter is led by two university research groups with different expertise (civil and environmental engineering at the University of Brescia on one hand and social sciences at the University of Sassari on the other) and one NGO (Controvento) whose mission is children not-formal education. The Italian CoP, led by the University of Brescia, is composed of 62 members from both the higher education and the research community, as well as from the primary and secondary education levels (teachers and pupils), from the productive sectors (farmers and spatial planners), from the politics world (local administrators) and from the civil society (NGOs and associations).

This contribution presents the activities performed so far, viz the stakeholder mapping, the creation of the CoP and its first meetings and the community-based participatory activity which was organized on the World Soil Day 2023.

How to cite: Peli, M., Dada, A., Barisani, F., Ventura, V., Pezzagno, M., Barontini, S., and Grossi, G.: The LOESS project to boost soil health literacy across Europe: The case of Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19820, https://doi.org/10.5194/egusphere-egu24-19820, 2024.

EGU24-20664 | Posters on site | ITS1.23/SSS0.1.4

A framework for setting soil health targets and thresholds in agricultural soils  

Amanda Matson, Maria Fantappiè, Grant A. Campbell, Jorge F. Miranda-Vélez, Jack H. Faber, Lucas Carvalho Gomes, Rudi Hessel, Marcos Lana, Stefano Mocali, Pete Smith, David Robinson, Antonio Bispo, Fenny van Egmond, Saskia Keesstra, Nicolas P.A. Saby, Bozena Smreczak, Claire Froger, Azamat Suleymanov, and Claire Chenu

Soil health is a key concept in worldwide efforts to reverse soil degradation, but to be used as a tool to improve soils, it must be definable at a policy level and quantifiable in some way. Soil indicators can be used to define soil health and quantify the degree to which soils fulfil expected functions. Indicators are assessed using target and/or threshold values, which define achievable levels of the indicators or associated soil functions. However, defining robust targets and thresholds is not a trivial task, as they should account for differences in soil type, climate, land-use, management, and history, among other factors.

We assessed (through theory and stakeholder feedback) four approaches to setting targets and thresholds: fixed values based on research, fixed proportions of natural reference values, values based on the existing range (e.g. lower quartile of the observed distribution), and targets based on relative change (e.g. a 20% increase of the indicator’s value). Three approaches (not including relative change) were then further explored using case study examples from Denmark, Italy, and France, which highlighted key strengths and weaknesses of each approach. Here, we present a selection of the assessment and case study results, as well as a framework, which facilitates both choosing the most appropriate target/threshold method for a given context, and using targets/thresholds to trigger follow-up actions to promote soil health.  

How to cite: Matson, A., Fantappiè, M., Campbell, G. A., Miranda-Vélez, J. F., Faber, J. H., Gomes, L. C., Hessel, R., Lana, M., Mocali, S., Smith, P., Robinson, D., Bispo, A., van Egmond, F., Keesstra, S., Saby, N. P. A., Smreczak, B., Froger, C., Suleymanov, A., and Chenu, C.: A framework for setting soil health targets and thresholds in agricultural soils , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20664, https://doi.org/10.5194/egusphere-egu24-20664, 2024.

EGU24-21616 | Posters on site | ITS1.23/SSS0.1.4

Searching for pedotransfer functions to predict sorption of pharmaceuticals from soil properties 

Pierre Benoit, Charline Godard, Marjolaine Deschamps, Nathalie Bernet, Ghislaine Delarue, Valenti Serre, and Claire-Sophie Haudin

In the context of recycling organic waste products or irrigation by treated wastewaters (re-use), the fate of human and veterinary pharmaceuticals in agricultural soils and consequent ground-water contamination are influenced by many factors, including soil properties controlling sorption and dissipation processes (Verlicchi et al., 2015, Mejías et al., 2021, Rietra et al., 2022). Sorption coefficients are among the most sensitive parameters in models used for risk assessment. However, for different classes of pharmaceuticals, the variations in sorption among different soil types are poorly described and understood (Kodesova et al., 2015). Here we reviewed sorption parameters for different classes of pharmaceuticals and their variation with selected soil properties. We also evaluated the sorption isotherms for three pharmaceuticals, ofloxacin, tetracycline, diclofenac and a bactericide,  riclocarban and ten soils from temperate and tropical regions, and assessed the impact of soil properties on Freundlich equation parameters Kf and n. Batch experiments were set up adapting OECD protocol and using initial concentration ranges from 5 to 1000 μg/L. For strongly sorbed molecules, namely ofloxacin, tetracycline and triclocarban, there were strong technical constraints for the quantification of equilibrium concentrations by LC-MS-MS. We used this knowledge from both literature review and experimental data to build pedotransfer functions that allow predicting sorption parameters for a wide range of soils. Sorption of ionizable pharmaceuticals was, in many cases, highly affected by soil pH and CEC whereas soil organic matter content remained a driving factor of sorption for neutral molecular forms.


References:
Kodesova, R., et al. (2015) Science of the Total Environment 511, 435–443.
Mejías, C. et al. (2021) Trends in Environmental Analytical Chemistry 30, e00125.
Rietra, R.P.P.J., et al. (2024) Heliyon 10 (2024) e23718.
Verlicchi, P. & Zambello, E., (2015) Science of The Total Environment 538, 750–767

How to cite: Benoit, P., Godard, C., Deschamps, M., Bernet, N., Delarue, G., Serre, V., and Haudin, C.-S.: Searching for pedotransfer functions to predict sorption of pharmaceuticals from soil properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21616, https://doi.org/10.5194/egusphere-egu24-21616, 2024.

EGU24-22341 | Posters on site | ITS1.23/SSS0.1.4

Transport and bioaccessibility of nano-contaminants in Brazilian latosol through pore water evaluation 

Aline de Andrade, Marco A. Z. Arruda, Sophie Miguel, Stéphanie Reynaud, and Javier Jiménez-Lamana

Plastic production worldwide has increased from 1.5 million tons in 1950 to 390.7 million tons in 2021.1 Nanoplastics (NPTs) have been considered an emergent contaminant entering the environment without any control since they can be formed by the degradation of large-sized plastic inadequately disposed of and considering that only 9% are effectively recycled.2 Just as the NPTs, nanoparticles (NPs) are considered emergent contaminants, and their application in different industrial products raises concern regarding the NPs entering the environment matrices.3 The soil bioaccessibility is an important parameter when considering the contaminants assessment evaluation with biological soil phase, and the study of soil liquid solution, which is called the soil pore water, can elucidate not only the bioaccessibility but also NPTs and NPs mobility, fate, and stability.4 The NPTs’ and NPs’ concentrations in the range of ng L-1 might be a limitation for their evaluation. However, spICP-MS can provide information on size, number concentration, and mass concentration, even in environmental conditions.5 In this study, a typical Brazilian soil used for plant cultivation (Latosol) was employed, and the soil moisture was controlled according to the field capacity determined in advance. Polystyrene (PS) nanoparticles with gold core and silver NPs (AgNPs), considering their abundance in different goods, were used as model nano-contaminants. The soil pore water was collected in two sampling points through a low-pressure lysimetric method using Rhizon® samplers once a week for 45 days of the experiment. In addition, the soil moisture was controlled by monitoring and adding more water to maintain the soil humidity, considering the three field capacity percentages studied. Results showed a downward trend in the number of particles detected in successive collections over time for both nano-contaminants. However, they also demonstrated different behaviours between them. The NPTs were bioaccessible in the pore water after the first days from the beginning of the experiments, and their concentration decreased constantly. At the same time, the NPs presented an inconstant transport through the soil column, gradually becoming bioaccessible. Finally, the concentration proved to be an important and decisive parameter, bringing essential discussion regarding the nano-contaminant's increasing concentration and behaviour in an environmental matrix, demonstrating the necessity to comprehend their interactions with the soil and between each other.

 

1 S. Maity, R. Guchhait, M. B. Sarkar and K. Pramanick, Plant. Cell Environ., 2022, 45, 1011–1028.
2 P. Zhou, L. Wang, J. Gao, Y. Jiang, M. Adeel and D. Hou, Soil Use Manag., 2023, 39, 13–42.
3 Q. Abbas, B. Yousaf, Amina, M. U. Ali, M. A. M. Munir, A. El-Naggar, J. Rinklebe and M. Naushad, Environ. Int., 2020, 138, 105646.
4 M. Di Bonito, N. Breward, N. Crout, B. Smith and S. Young, in Environmental Geochemistry, Elsevier, 2008, pp. 213–249.
5 J. Jiménez-Lamana, L. Marigliano, J. Allouche, B. Grassl, J. Szpunar and S. Reynaud, Anal. Chem., 2020, 92, 11664–11672.

How to cite: de Andrade, A., Arruda, M. A. Z., Miguel, S., Reynaud, S., and Jiménez-Lamana, J.: Transport and bioaccessibility of nano-contaminants in Brazilian latosol through pore water evaluation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22341, https://doi.org/10.5194/egusphere-egu24-22341, 2024.

EGU24-467 | Orals | ITS4.6/SSS0.1.5

Nature-based solutions for leveed river corridors 

Matt Chambers, Dave Crane, Charles van Rees, Matt Shudtz, Craig Landry, Susana Ferreira, Don Nelson, Burton Suedel, Brock Woodson, and Brian Bledsoe

Climate driven changes in hydrologic regimes are increasing riverine flood risks in many parts of the world. Societies that have historically relied on structural flood management infrastructure, e.g., levees and dams, may face significant challenges as these types of infrastructure can be expensive and politically difficult to retrofit for non-stationary and uncertain future flood hazards. Hybridizing conventional infrastructure systems with nature-based solutions (NbS) can help communities adapt to non-stationarity and improve flood resilience. However, despite advances in the academic literature, NbS have failed to become mainstream in many societies. The United States (US) is no exception and has an extensive history of engineering rivers with structural systems to support immediate-term economic growth and with limited consideration for non-stationarity. For example, there are thousands of kilometers of continuously leveed river corridors in the US and many of these levees were built as close to river banks as possible to maximize the commercial prospects of flood protected land use. Such levees are relatively sensitive to non-stationarity and the communities they protect are becoming increasingly vulnerable to climate change-driven flooding. Our research focuses on how to bridge the gap between the scientific development of NbS and implementation in professional practice. We are doing so by example, with levee setbacks on America’s longest river -- the Missouri -- and in collaboration with the US’s primary action agency of flood risk management -- the US Army Corps of Engineers. Setbacks are implicitly an adaptation strategy that buffer a community against uncertainty and non-stationarity by providing additional room for floodwater conveyance. Unfortunately, they are fraught with social and political challenges because -- as a form of managed retreat -- they require some community members to relinquish private property rights so that the broader community can have greater flood protection. Critical to bridging the gap between levee setback research and implementation is understanding the performance of setbacks at scale and the development of simple and repeatable methods for designing setbacks to successfully deliver multiple ecosystem services. The most fundamental of which is how to “size” a setback – in other words – how big of a floodplain reconnection is required to achieve a desired improvement in flood protection services? In this talk, we will discuss sizing methodologies for achieving multiple services, as well as practical engineering, social, ecological, and administrative constraints that have arisen in the process of translating NbS research to practice. The example of levee setbacks on American rivers is particularly useful because it affords experimentation with repeatability (given the thousands of kilometers of continuously leveed river corridors) and the spatial scale of reconnection required to achieve multiple benefits (given the massive size of many levees and floodplains). The results of which may be relatable to many engineered river corridors around the world and will hopefully support mainstreaming NbS in other social and political contexts.

How to cite: Chambers, M., Crane, D., van Rees, C., Shudtz, M., Landry, C., Ferreira, S., Nelson, D., Suedel, B., Woodson, B., and Bledsoe, B.: Nature-based solutions for leveed river corridors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-467, https://doi.org/10.5194/egusphere-egu24-467, 2024.

As urbanization and climate change continue to pose significant challenges for cities worldwide, green roofs (GRs) has emerged as a viable sustainable solution for supporting traditional infrastructure in managing stormwater runoff. Although their hydrological behavior has been sufficiently documented in literature, conflicting results emerge regarding the potential variations in their retention capacity (RC) over the medium and long-term. Based on preliminary investigations, this research aimed at assessing medium-term changes in the hydrological performance of two experimental GRs (GR1 and GR2), further investigating the potential role played by precipitation severity. The GRs, located in Southern Italy and consisting of three layers (vegetation, substrate and drainage), were set up in 2017 and monitored for two operational periods, 2017-2019 and 2022-2023. The measurements gathered between 2017 and 2019 provide valuable insights into the initial performance of the GRs and their ability to retain water during the early years of operation. Data collected in 2022 and 2023 instead reflect the retention capacity of the GRs after a few years of operation. A total of 29 mild precipitation events were collected during both periods and for both GRs, detecting from the monitoring data their cumulative precipitation (P) and runoff (R) with the objective of assessing the RC (RC = 1 - R/P). Based on the preliminary findings, it appears that there is an overall decline in the RC for both GR1 and GR2, without significant differences between the two. The Aging Indexes (AI) were calculated for GR1 and GR2, representing the average reduction of the runoff coefficient (RC) over time. GR1, which has a drainage layer composed of expanded clay, exhibited an AI of 12%. On the other hand, GR2, characterized by a drainage layer made of MODI' plastic panel filled with expanded clay, exhibited a slightly higher AI of 13%. Further analysis revealed that within each dataset, two groups were identified based on a threshold determined by the growth coefficient g(T) of the precipitation events. For the group of events with g(T) values above 0.12 (sample size of 14), the AI values were 15% and 16% for GR1 and GR2, respectively. On the other hand, the group of events with g(T) values equal to or lower than 0.12 (sample size of 15) experienced AI values of 10% and 11% for GR1 and GR2, respectively. These findings suggest that as the growth coefficient g(T) increases, indicating higher return periods T, the AI and consequently the reduction in hydrological performance of GRs also increase. The highly possible increase in the future of extreme precipitations would pose a considerable limit to the spread of this kind of sustainable drainage infrastructures. However, additional modeling investigations focused at detecting the effects of alternative GRs designs and materials on their long-lasting average hydrological performance would be essential for making informed decisions and investments.

How to cite: D'Ambrosio, R. and Longobardi, A.: Assessing the Medium-Term Changes in Hydrological Performance of Green Roofs: The Influence of Precipitation Severity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1019, https://doi.org/10.5194/egusphere-egu24-1019, 2024.

EGU24-1035 | ECS | Posters on site | ITS4.6/SSS0.1.5 | Highlight

Multi-scale analysis of green infrastructure morphology for climate change adaptation 

Lou Valide, Pierre-Antoine Versini, and Olivier Bonin

Nature-based Solutions, even if not identified as such, are becoming more and more popular in land planning, especially in cities. Conserving and restoring green infrastructure in urban context is now recognised as being a good practice in the face of climate change adaptation: ecosystem services provided by green spaces can help reduce urban heat island effect and risks of flood, improve resilience of ecosystems to preserve biodiversity and enhance human well-being through access to nature. Simultaneously, cities have to face another challenge: containing land take and urban expansion. The European Commission, in its Roadmap to a Resource Efficient Europe (2011), claimed the “aim to achieve no net land take by 2050”, a goal already transcribed in French law since 2021. Hence, the competition for land use which already existed between housing, industry, roads and recreational purposes will only become fiercer and have to include a new competitor: Nature-based Solutions. In this context, the ability of optimizing the implementation of such solutions – through the different scales at which they provide ecosystem services (building, neighbourhood, city and landscape) – is becoming primordial. Where should we conserve or restore green spaces in priority to ensure the providing of the ecosystem services needed for urban climate change adaptation? This question implies a multi-scale spatial analysis of the impact of green infrastructures on cities. To do so, the question of urban form is tackled by focusing on what is between buildings and streets, where green infrastructure can be deployed and woven into the urban fabric. To establish a multi-scale typology of green infrastructures based on their morphologies, classical approaches are combined with mathematical tools such as fractal analysis for characterizing their dispersion or graph theory for characterizing their connections, essential when studying biodiversity issues. This typology, associated with ecosystem services and biodiversity assessment for different French case studies (including the conurbations of Niort and Dijon), could help understand how to spatially implement Nature-based Solutions within cities, and be integrated into land-planning scenarios.

How to cite: Valide, L., Versini, P.-A., and Bonin, O.: Multi-scale analysis of green infrastructure morphology for climate change adaptation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1035, https://doi.org/10.5194/egusphere-egu24-1035, 2024.

EGU24-2018 | ECS | Posters on site | ITS4.6/SSS0.1.5

WebGIS for Marine Coastal Ecosystems: A Dynamic Interface for Communicating and Collaborating on Nature-Based Solutions in Climate Change Mitigation and Adaptation 

Jéssica Uchôa, Catarina Fonseca, Rafaela Tiengo, Bruna Almeida, and Artur Gil

As the global community grapples with the complex challenges of climate change, the integration of nature-based solutions (NBS) has emerged as a critical strategy. This work introduces a Web Geographic Information System (WebGIS) designed to showcase and communicate the results of initiatives focused on NBS within the scope of the Marine Coastal Ecosystems Biodiversity and Services in a Changing World (MaCoBioS) project. The platform serves as an interface for decision-makers and stakeholders, providing a spatially contextualized visualization of geospatial data related to marine and coastal ecosystems, climate risks, and adaptation. The MaCoBioS webGIS is based on an open-source platform, using JavaScript and the Leaflet map library to showcase key scenarios developed for case study ecoregions. The platform allows remote access to data irrespective of geographical constraints and is capable of integrating multidisciplinary data, ensuring a comprehensive and up-to-date view of evolving climate-related scenarios. The MaCoBioS webGIS not only facilitates the identification, evaluation, and direction of potential solutions to extant and emergent issues but also affords public access and participation. It serves as a foundational platform for prospective local and regional areas monitoring and management. By integrating qualitative information with scientific data, the aim is to present the results clearly and in a straightforward language, to reach a broader audience, including those who may not have specialized expertise. In so doing, it establishes the groundwork for future initiatives, promoting collaboration and leveraging cutting-edge technology for the betterment of coastal communities and ecosystems. In summary, the webGIS not only serves as a powerful tool for visualizing geospatial data but also acts as an effective means of communication and collaboration. By promoting informed decision-making, and supporting initiatives related to climate change and NBS, the platform contributes to the collective effort in addressing the complexities of our changing climate.

How to cite: Uchôa, J., Fonseca, C., Tiengo, R., Almeida, B., and Gil, A.: WebGIS for Marine Coastal Ecosystems: A Dynamic Interface for Communicating and Collaborating on Nature-Based Solutions in Climate Change Mitigation and Adaptation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2018, https://doi.org/10.5194/egusphere-egu24-2018, 2024.

The Great Green Wall (GGW) is a multibillion-dollar African initiative to combat desertification in the Sahel by restoring 100 million hectares of degraded land. The idea of a physical green wall of trees has now been developed into the implementation of scattered green zones throughout arid areas, providing sustainable reforestation, revegetation, and land management. In West Africa, the most important climate feature is the West African Monsoon (WAM), which brings rainfall over the Sahel during the Northern Hemisphere summer. Climate dynamics associated with WAM changes could also play a role on the Atlantic Tropical Cyclones (ATCs) formation and variability. The potential climate impacts of the most recent GGW plan on northern Africa and tropical Atlantic have not yet been adequately evaluated, raising concerns about unforeseen climate ramifications that could affect stability in northern Africa and impact on the ATC variability. Here, we use a high-resolution (~13 km) regional climate model to evaluate the climate impacts of four GGW scenarios with varying vegetation densities under two extreme emission pathways (low and high). Higher vegetation density GGW scenarios under both emission pathways show enhanced rainfall, reduced drought lengths and decreased summer temperatures beyond the GGW region relative to the cases with no GGW. However, all GGW scenarios show more extreme hot days and heat indices in the pre-monsoonal season. Furthermore, in spite of a strong variation in the African Easterly Waves activity, no significant changes are found in terms of ATCs frequency, intensity, meridional motion and translation speed over the North Atlantic area. Small changes in the TC densities are found in front of the cost of West Africa,  in the eastern side of the Main Development Region. These findings highlight the GGW's contrasting climatic effects, emphasizing the need for comprehensive assessments in shaping future policies.

 

How to cite: Ingrosso, R. and Pausata, F. S.: On the climate impacts of four different Great Green Wall scenarios on the northern Africa and the Atlantic Tropical Cyclones variability., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2883, https://doi.org/10.5194/egusphere-egu24-2883, 2024.

Given the local pollution near the school in Follonica(Gr)-Italy, specifically at the Gora river’s mouth, students have designed a study (IBSE method) of the chemical and ecological indicators of the river's situation. Analyzing the city's history about climate, the changes of the water regime and the shape of the river during the XX century, they have measured the indicators (physical and chemical parameters of the water, Extended Biotic Index). Creating a website and an interactive map of the river, they have communicated the situation to the local authorities, so the school has become involved in the "Pecora River Agreement", a local project aiming to the redevelopment of the river ecosystem. Students make proposal: plants in the riverbank, activities to sensitize local community and monitoring through ecological index for the future of the city.

How to cite: severi, A.: Requalify our river: from a school project to a city project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3616, https://doi.org/10.5194/egusphere-egu24-3616, 2024.

The recently released IPCC Mitigation report placed agroforestry as one of the top three Agriculture, Forestry and Other Land Use (AFOLU) mitigation pathways, noting that it delivers multiple biophysical and socioeconomic co-benefits such as increased land productivity, diversified livelihoods, reduced soil erosion, improved water quality, and more hospitable regional climates, concluding there is ‘high confidence’ in agroforestry’s mitigation potential at field scale. As such, agroforestry is one of the most cited nature-based solutions in development strategies and in reporting of nationally determined contributions (NDC),  both for its potential mitigation benefits, but not least for the adaptation, resilience and livelihood benefits it can provide, across scales from agro-industrial farming to small farmer holdings. Here we present recent global and regional estimates of above- and below-ground biomass on agricultural land based upon IPCC Tier 1 estimates and compare results with an updated carbon density map based on remote sensing, with results indicating the methodology and initial estimations are robust. Two future scenarios are evaluated to estimate carbon sequestration potential of increasing tree cover on agricultural land: 1.) incremental change and 2.) systematic change to agroforestry. Estimates of above- and below ground biomass carbon were combined with a remote sensing-based tree cover analysis to estimate the increase in biomass. Global increases (4-6 Pg C for incremental change; 12-19 Pg C for systematic change) highlight substantial mitigation potential. Increasing global tree cover on agricultural land by 10% would sequester more than 18 Pg C over a decade. South America has the highest potential, followed by Southeast Asia, West and Central Africa, and North America. Brazil, Indonesia, Philippines, India, the United States and China are among the top countries. Additionally, we provide an overview and analysis of the unique and significant contribution agroforestry can provide in mountainous regions and in reducing pressure on irrecoverable carbon.

How to cite: Zomer, R., Xu, J., Spano, D., and Trabucco, A.: Nature-Based Solutions: Evaluating the global carbon sequestration potential of agroforestry and increased tree cover on agricultural land., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6018, https://doi.org/10.5194/egusphere-egu24-6018, 2024.

EGU24-6169 | ECS | Orals | ITS4.6/SSS0.1.5

Modelling CO2 flows from extensive green roofs within the TEB (town energy balance) urban canopy model 

Aurélien Mirebeau, Cécile de Munck, Stephan Weber, Aude Lemonsu, and Valéry Masson

To mitigate climate change impacts in cities, nature-based solutions are broadly promoted due to their supposed benefits for biodiversity, rainwater management, evaporative cooling, and sequestration of carbon. Among existing solutions, green roofs show the advantage of tackling the lack of space available for greening in urban areas. But green roofs are still underdeveloped due to their cost and the lack of scientific knowledge around their potential, especially for carbon sequestration. Quantifying the various contributions of green roofs using reliable scientific approaches is a major challenge. Thus, it is essential to build a numerical model capable of simulating green roofs development and functioning at city scale in order to provide information to decision-makers with relevant indicators.

 

Here, the urban canopy model Town Energy Balance (TEB) with the module TEB-GREENROOF is used to model green roofs. The TEB-GREENROOF model, evaluated in previous study for heat and water transfers, is improved by activating the photosynthesis model ISBA-A-gs in order to represent the CO2 exchanges of the vegetation implemented on the green roof. The modelling is informed by 6 years of continuous CO2 flux data on a non-irrigated extensive green roof located in Berlin (Germany) in partnership with the Technische Universität Braunschweig. In order to evaluate and improve the thermal, hydrological and respiration characteristics of the ISBA-A-gs model on a green roof, an initial simulation is carried out by forcing the monthly evolution of the leaf area index (LAI) by LAI data estimated experimentally. The model is then applied with a dynamic calculation of LAI in order to enable it for simulations of roof greening scenarios on a city-wide scale under any climate with no information on the LAI.

 

Results show that the model is able to estimate the annual net ecosystem exchange of the Berlin green roof and to correctly reproduce the CO2 fluxes for both diurnal cycles and annual variation under climate variability, with drier years showing less carbon sequestration.

How to cite: Mirebeau, A., de Munck, C., Weber, S., Lemonsu, A., and Masson, V.: Modelling CO2 flows from extensive green roofs within the TEB (town energy balance) urban canopy model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6169, https://doi.org/10.5194/egusphere-egu24-6169, 2024.

EGU24-6608 | Orals | ITS4.6/SSS0.1.5

Nature-based solutions for erosion mitigation : insights from a systematic review for the Andean region 

Veerle Vanacker, Armando Molina, Miluska Rosas, Vivien Bonnesoeur, Francisco Román-Dañobeytia, Boris Ochoa-Tocachi, and Wouter Buytaert

The Andes Mountains stretch over about 8900 km and cross tropical, subtropical, temperate and arid latitudes. More than 85 million people lived in the Andean region by 2020, with the northern Andes being one of the most densely populated mountain regions in the world. The demographic growth and a stagnating agricultural productivity per hectare led to an expansion of the total agricultural land area, either upward to steep hillsides at high elevations covered by native grassland-wetlands ecosystems, or downward to lands east and west of the Andes covered by tropical and subtropical forests. Land use and management have significantly altered the magnitude and frequency of erosion events. 

This study systematically reviews the state of evidence on the effectiveness of interventions to mitigate soil erosion by water and is based on Andean case studies published in gray and peer-reviewed literature. After screening 1798 records, 118 empirical studies were eligible and included in the quantitative analysis on soil quality and soil erosion. Six indicators were pertinent to study the effectiveness of natural infrastructure: soil organic carbon and bulk density of the topsoil, soil loss rate and run-off coefficient at the plot scale, and specific sediment yield and catchment-wide run-off coefficient at the catchment scale. The protection and conservation of natural vegetation has the strongest effect on soil quality, with 3.01 ± 0.893 times higher soil organic carbon content in the topsoil compared to control sites. Soil quality improvements are significant but lower for forestation and soil and water conserva- tion measures. Soil and water conservation measures reduce soil erosion to 62.1 % ± 9.2 %, even though erosion mitigation is highest when natural vegetation is maintained.

Further research is needed to evaluate whether the reported effectiveness holds during extreme events related to, for example, El Niño–Southern Oscillation.

 

 

 

How to cite: Vanacker, V., Molina, A., Rosas, M., Bonnesoeur, V., Román-Dañobeytia, F., Ochoa-Tocachi, B., and Buytaert, W.: Nature-based solutions for erosion mitigation : insights from a systematic review for the Andean region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6608, https://doi.org/10.5194/egusphere-egu24-6608, 2024.

EGU24-7898 | ECS | Posters on site | ITS4.6/SSS0.1.5

Nature-based Solutions on privately owned land: Stakeholder engagement matters 

Marion Wallner, Thomas Thaler, Arthur Schindelegger, and Katharina Gugerell

To tackle hydrometeorological extreme events and adapt to climate change, Nature-based Solutions (NbS) are widely considered a promising approach. Yet, their implementation remains challenging. One key reason is that NbS require a lot more land than grey infrastructure – making their implementation dependent on privately owned land and prone to cause or exacerbate conflicts of interest over land use. This request of privately owned land widens the numbers of actors involved in the decision-making process. For this very reason, the realisation of NbS highlights the necessity of meaningful stakeholder engagement. However, in the past, technical mitigation measures were traditionally enforced top down by engineers within the public administration at national or regional level. Stakeholder engagement thus fundamentally changes the way how risk managers and citizens collaborate and is often reported to not live up to its expectations. Therefore, this study will address the role of stakeholder engagement as a decisive factor for the implementation of NbS on privately owned land. More specifically, it aims (i) to analyse what approaches to stakeholder engagement are currently employed on the side of flood risk authorities and (ii) to evaluate how stakeholder engagement processes account for conflicts of interest over land use. For this purpose, a qualitative research design approach will be exerted. This will involve desk research to identify areas in Austria where NbS on privately owned land have already been (and will be) implemented, semi-structured interviews with public water authorities and workshops in our case study site – the Lafnitz catchment in Austria. Lessons learnt will be compared with those of five other regions across Europe, as our study is embedded in the EU Horizon Project “Land4Climate” (Utilization of private land for mainstreaming Nature-based Solutions in the systemic transformation towards a climate-resilient Europe, HORIZON-MISS-2022-CLIMA-01-06). By doing so, our research will provide hands-on knowledge on NbS implementation and foster its mainstreaming across the European Union.

How to cite: Wallner, M., Thaler, T., Schindelegger, A., and Gugerell, K.: Nature-based Solutions on privately owned land: Stakeholder engagement matters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7898, https://doi.org/10.5194/egusphere-egu24-7898, 2024.

Idea and Objectives: The health and well-being of urban populations are increasingly under pressure from climate change, for example, due to temperature extremes resulting in heat stress. The demand for heat mitigation is particularly high for urban areas in humid, tropical climates, as they are affected by heat stress already today, and for which a further amplification of heat stress is expected. For the case of Hue, a humid tropical Central-Vietnamese city, based on a typology of selected green-blue infrastructure elements, potential benefits for the regulation of outdoor temperature and outdoor thermal comfort are systematically virtually implemented and modelled. In order to promote acceptance of greening interventions by the public in Hue, citizen demands and preferences towards urban green elements, including potential co-benefits, are considered in this study, and in so-doing, best practices for local action shall be identified.

 

Background: Vietnam is a country that faces multiple challenges. Climate change is anticipated to exacerbate natural hazard risks, i.e., of flooding, storms, and prolonged periods of extreme heat, which are known to increase the risk of mortality, particularly among vulnerable groups. This is compounded by ongoing, rapid urban growth, that urgently necessitates safeguarding urban ecosystem services to facilitate climate change adaptation, and to support human health and well-being. Elements of the urban green-blue infrastructure are typically regarded as efficient nature-based interventions for the delivery of often multiple ecosystem services, including benefits for urban heat mitigation, i.e., the improvement of outdoor thermal comfort. Accordingly, such measures are increasingly being funded, politically recognised and implemented in Southeast Asian countries, including Vietnam. However, specifically for Vietnam, certain knowledge gaps remain with respect to the effectiveness of greening interventions for heat mitigation under local conditions, as well as in regard to ensuring the implementation of locally relevant and thus sustainable and resilient nature-based solutions.

How to cite: Sumfleth, L., Scheuer, S., Nguyen, L., and Haase, D.: Urban green-blue infrastructure as nature-based solutions for urban heat adaptation in Hue city, Central Vietnam – Potential impacts in contrast to citizen demands for urban greenery, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7963, https://doi.org/10.5194/egusphere-egu24-7963, 2024.

EGU24-8691 | ECS | Posters on site | ITS4.6/SSS0.1.5

Development of wind and fire risk indices for climate-mitigation forestry 

Els Ribbers, Hanna Lee, Priscilla Mooney, Helene Muri, Lei Cai, Jin-Soo Kim, and Lars Nieradzik

Afforestation has long been discussed as a nature-based climate mitigation solution. Although it could be an economic, green, and safe climate mitigation method, several studies suggest the possibility of unforeseen consequences depending on how it is implemented. An important aspect to be taken into account when designing af- and reforestation plans is the risk of damage to the new forest system in the face of climate warming. Recent studies have already shown an increase in both wind and fire damage risks in northern latitudinal forests related to climate warming, with strong winds leading to breakage of individual branches as well as in the knock-over of individual trees or even entire forest areas.

However, the forest system is complex, with a high number of feedback loops between different types of damage and between forest structure and ecological parameters. A few examples: Trees that are weakened by damage from pest outbreaks and snowfall are more susceptible to damage from wind and fire; Gaps in the forest that are created by management or damage both increase wind flow due to an eddy effect and create new forest edges with poorly adapted trees, increasing the risk of wind-throw.

Due to this complexity, the resilience to damage and therefore ability of forests to mitigate climate on a regional scale are still poorly understood. Understanding this complexity requires model work and extensive literature research, as most studies only focus on a few aspects of the forest system, such as the management type or wind effects. The aim of the study is therefore to develop adequate and future-proof wind- and fire risk indices that boreal forest managers can use to improve management strategies to make climate-mitigation forests more effective, resilient and damage resistant.

To do this, output from the Weather Research and Forecasting (WRF) model is used in combination with data on damage, forest management and forest structure to shed some light on possible feedbacks between forest systems and climate on a small-scale basis, in this case 3kmx3km. This information is then used to expand the Canadian Forest Fire Weather Index (FWI) to include ecological, management-related and forest structural parameters. As the structure of the existing FWI is climate-based, the wind risk index will be based on the developed fire risk index.

Our preliminary results show that wind damage was most common and extensive in the south-western coastal area of Norway over the last two decades. In contrast, fire damage was most prevalent in the south, with increased damage extent in the south-west of the country. Furthermore, the FWI shows that under an afforestation scenario in Norway, the mountainous region will have the highest frequency of days with medium to high danger of forest fires under climate warming. In this presentation we will discuss these preliminary results, as well as the methodology we will be using to develop the risk indices. Policymakers and forest owners alike will be able to use the risk indices to make the climate-mitigation forests more resilient against damage in a warming climate.

How to cite: Ribbers, E., Lee, H., Mooney, P., Muri, H., Cai, L., Kim, J.-S., and Nieradzik, L.: Development of wind and fire risk indices for climate-mitigation forestry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8691, https://doi.org/10.5194/egusphere-egu24-8691, 2024.

The proliferation of climate-induced stressors has deterred countries' green spaces (GS), which in turn degrade and deplete natural green barriers. Hence, Urban Green Infrastructure (UGI) modelling is grabbing global attention perceiving it as a nature-based mitigation/adaptation strategy to enhance the resilience of urban areas to fight climatic risks. UGI protects and improves the socio-ecological wellness of urban and rural regions. This research intends to investigate thirteen sustainable UGI indicators and their functional linkage with the five vital taxonomies of nature-based green solutions (at the neighborhood level) under a community participatory (CP) approach; out of ten GS elements and twenty-two sustainable UGI indicators developed by the author in his earlier research study [2-5]. It is to develop a sustainable UGI indicator-based framework (tailored to the native-built context) for climate-resilient urbanisation.

The results of the in-depth household survey (192 questionnaires), executed in three KP districts, Charsadda, Peshawar, and Mardan, and results were generated through Relative Importance Index (RII) and Interquartile Range Technique (IQR) show a very good level of coefficient alpha (α) value, (α = 0.7) — an acceptable threshold level [6, 7]. Furthermore, this study acknowledges key GS taxonomies that have achieved RII value ≥ 0.72. This performs a pivotal role in quality improvement and strengthening the resilience (health) of the respective UGI indicators. This scientific research study provides a foundation for an eco-regional paradigm in KP territory that paves the way for an effective implementation of green urbanism to naturally ameliorate the vulnerability to potential climatic stresses (like flooding, drought, the UHI effect) and disastrous impacts on the socio-ecological wellness.

Keywords: sustainable green infrastructure (GI) indicators; participatory planning (PP); nature-based green initiatives; climate change (CC); socio-ecological wellness; KP, Pakistan

References

1. Mell, I. C., Henneberry, J., Hehl-Lange, S., & Keskin, B. (2013). Promoting urban greening: Valuing the development of green infrastructure investments in the urban core of Manchester, UK. Urban Forestry & Urban Greening, 12(3), 296–306. http://dx.doi.org/10.1016/j.ufug.2013.04.006

2. Rayan, M., Gruehn, D., Khayyam, U., (2021b). Green infrastructure planning. A strategy to safeguard urban settlements in Pakistan. In: Jafari, M., Gruehn, D., Sinemillioglu, H., Kaiser, M. (Eds.), Planning in Germany and Iran. Responding Challenges of Climate Change through Intercultural Dialogue. Mensch und Buch Verlag. Berlin, pp. 197–220.

3. Rayan, M., Gruehn, D., & Khayyam, U. (2021a). Green infrastructure indicators to plan resilient urban settlements in Pakistan: Local stakeholder’s perspective. Urban Climate, 38, 100899. https://doi.org/https://doi.org/10.1016/j.uclim.2021.100899

4. Rayan, M.; Gruehn, D.; Khayyam, U (2022a). Frameworks for Urban Green Infrastructure (UGI) Indicators: Expert and Community Outlook toward Green Climate-Resilient Cities in Pakistan. Sustainability 2022,14, 7966. https://doi.org/10.3390/su14137966.

5. Rayan, M.; Gruehn, D.; Khayyam, U (2022b). Planning for Sustainable Green Urbanism: An Empirical Bottom-Up (Community-Led) Perspective on Green Infrastructure (GI) Indicators in Khyber Pakhtunkhwa (KP), Pakistan. Int. J. Environ. Res. Public Health 2022, 19, 11844. https://doi.org/10.3390/ijerph191911844

6. Cortina, J. M. What is coefficient alpha? An examination of theory and applications. J. Appl. Psychol (1993).

7. Peterson, R. A. A Meta-analysis of Cronbach’s Coefficient Alpha. J. Consum. Res (1994).

8. Wu, J., & Wu, T. (2012). Sustainability indicators and indices: an overview. Handbook of Sustainability Management, 65–86. http://dx.doi.org/10.1142/9789814354820_0004

How to cite: Rayan, M., Gruehn, D., and Khayyam, U.: Community-driven sustainable green infrastructure (GI) indicators to plan an eco-friendlier and climate-resilient city-state in Khyber Pakhtunkhwa (KP), Pakistan., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8806, https://doi.org/10.5194/egusphere-egu24-8806, 2024.

EGU24-9173 | ECS | Orals | ITS4.6/SSS0.1.5

Opportunities to Restore and Protect Coastal Ecosystems with Enhanced Interdisciplinary Management - The Mediterranean Model. 

Maria Makaronidou, Vito Emanuele Cambria, Evangelia Korakaki, Christos Georgiadis, and Nikos Petrou

Coastal zone ecosystems’ global importance is the primary driver of the wide scientific efforts for their restoration and protection. Over the past three decades, there has been a growing global momentum in the pursuit of initiatives aimed at conserving nature. Regardless of the wide scientific interest, and despite the notable exposure of these ecosystems to degradation and deterioration, numerous habitats, and species, in Europe, have 'vulnerable', or 'near threatened' conservation status. Even in the most favourable circumstances, factors including strong human pressure, urbanization and agriculture, and climate change, exhilarate the current, already, negative trends indicators, related to biodiversity and their associated ecosystem functions and services provision. This project proposes a set of existing and emerging methodologies and solutions for the restoration, conservation, and management practices, which are crucial to improving these profoundly delicate ecosystems in the Mediterranean and similar environmental contexts.

Traditional and innovative ecological restoration solutions have been designed and applied in two such areas along the Greek and Italian coasts, ‘Nestos Delta’ and ‘Bosco di Palo Laziale’, respectively, to improve the conservation status of 'Pannonian-Balkanic turkey oak-sessile oak forests' (habitat 91M0), ‘Alluvial forests with Alnus glutinosa and Fraxinus excelsior’ (habitat 91E0), and 'Mediterranean temporary ponds' (*3170) that have been increasingly exposed to climate change and inappropriate forest and water management.

Analogous, ecological restoration practices include selective trimming of encroaching shrub vegetation (and alien invasive shrubs in the Nestos area), remote-controlled irrigation system, origin-controlled and pathogen-free forestry nursery, ex-situ micro-propagation and in-situ reinforcement of keystone plant populations. An in-depth assessment and quantification of abiotic and biotic factors of the sites' ecosystems were preliminarily conducted to tailor these interventions to the habitats' geo-morphological, climatic, pedological, and physiological conditions.

The EU project LIFE PRIMED (LIFE17 NAT/GR/000511), operates at the Delta of River Nestos in Greece, and the Forest of Palo Laziale in Italy. The results in both areas, thus far, have demonstrated that the collaborative development of innovative water harvesting systems, coupled with adaptation measures, has the potential to enhance water resilience in already degraded forest ecosystems. To date, the project has successfully tackled the effects of escalating irregular rainfall patterns on Mediterranean coastal habitats by implementing a hydraulic system and a wellpoint-based water distribution network in Palo Laziale and Nestos Delta, respectively.

Monospecific approaches for climate and human-related phenomena, such as extreme weather events and agriculture pressure, are disfavoured. Therefore, the LIFE PRIMED project, comprised of an interdisciplinary team of Botanists, Zoologists, Foresters, and Environmental Engineers, has developed and delivered Nature-based transnational, ecosystem-oriented holistic solutions that will have the potential to be replicable and transferable with the greatest aim to recover dysfunctional, poorly managed coastal forest areas, across the Mediterranean region.

How to cite: Makaronidou, M., Emanuele Cambria, V., Korakaki, E., Georgiadis, C., and Petrou, N.: Opportunities to Restore and Protect Coastal Ecosystems with Enhanced Interdisciplinary Management - The Mediterranean Model., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9173, https://doi.org/10.5194/egusphere-egu24-9173, 2024.

EGU24-11439 | ECS | Orals | ITS4.6/SSS0.1.5 | Highlight

Assessing the vulnerability to climate change of tree species for urban afforestation 

Cristiano Gala, Gabriele Curci, Loretta Pace, Alessandro Marucci, and Dina Del Tosto

Nature-based solutions are now a key part in climate change adaptation, particularly for urban environments. The integration of natural systems within the urban fabric has the potential to increase cities’ resilience to the predicted changes in climate. Urban forests are one of the most used methods for adding ecosystem services to an urban environment and at the same time address urban-specific climate change challenges such as heat-island effect, intense rainfall and water management. However, the effects of climate change in the long-term on urban forests are not often taken into account when planning interventions such as afforestation. Species selection for urban forests should, among other factors, be based on an assessment of local future climatic conditions, so to ensure the long-term viability of the project. Here we propose a methodology easily applicable to any place in Europe. We use data from interpolated publicly available climate datasets and species distribution data from the European Tree Atlas in order to analyse climatic niches for tree species in Italy. These climatic ranges are then compared to local climatic data, obtained from homogenised time-series measured by a weather station in the city of L’Aquila. The results are summarised in a suitability matrix providing vulnerability scores for each species based on predicted climate changes for the local area. The analysis ranks the species which are less vulnerable to projected future climate conditions. The application to the pilot area of L’Aquila suggests that some species already present will still be suitable also in future climate (e.g. Quercus pubescens) while others will not (e.g. Quercus petraea), and species not traditionally present may become suitable (e.g. Quercus ilex). The importance of obtaining accurate local climate data from observations is a key aspect for municipalities to consider as results of this analysis are greatly dependent on this.

How to cite: Gala, C., Curci, G., Pace, L., Marucci, A., and Del Tosto, D.: Assessing the vulnerability to climate change of tree species for urban afforestation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11439, https://doi.org/10.5194/egusphere-egu24-11439, 2024.

EGU24-13018 | ECS | Orals | ITS4.6/SSS0.1.5

Leveraging the co-benefits of large tree protection to inform nature-based management of a forest ecosystem 

Tessa Maurer, Patricia Manley, Christopher Anderson, Nicholas Povak, Philip Saksa, Anu Kramer, and Zachary Peery

In fire-adapted forests around the world, nature-based solutions (NbS) are increasingly used as a tool to promote resilience to catastrophic fire through actions like fuels reduction and prescribed burning. This work also has many potential co-benefits, including climate change mitigation through stable carbon storage and biodiversity through habitat protection. One key mechanism for realizing both of these co-benefits is the protection of large and ancient trees, keystone components that sequester a disproportionate amount of carbon and serve as unique habitat for old forest associated species, many of which are declining or at risk of extinction. However, climate change poses a substantial risk to both tree recruitment and survival, either directly (temperature and drought tolerance) or indirectly (wildfire and insect occurrence). These impacts are not fully understood in the scientific literature nor, as a result, fully accounted for in the design of NbS management projects.

Therefore, to help inform near-term NbS restoration priorities, we investigated how a changing climate will impact the retention of large trees on the landscape and the ecosystem functions they support. Focusing on the Sierra Nevada, California, USA, a biophysically diverse and at-risk mountain ecoregion, we evaluated the intersection of current and future climate with large tree occurrence and two critical functions: carbon storage and habitat for the California spotted owl (Strix occidentalis occidentalis; CSO), an old growth associated species whose core population is limited to the Sierra Nevada and that requires large trees for nesting habitat. We mapped large trees across the Sierra Nevada, evaluated the climatic drivers of large tree biogeography, and forecasted how conditions supportive of large tree populations might shift geographically in the future under two emission levels (RCP 4.5 and 8.5). Using a bivariate fuzzy logic approach, we mapped the joint probability of current CSO occupancy and carbon storage and then evaluated future climate vulnerabilities and associated management strategies. We found that carbon and CSO occupancy corresponded closely with the current distribution of large trees in the Sierra, primarily at mid-elevations in the central Sierra. Similarly, we found that these mid-elevation montane forests are likely to continue to support large trees and CSO habitat and carbon storage through mid-century (e.g., consistent with "monitor" and "protect" climate-informed management strategies). Conversely, climate conditions in the southern Sierra and the upper elevations of the central Sierra are likely to constrain the persistence and recruitment of large trees, affecting the potential to recruit CSO habitat and enhance the carbon storage of higher elevation forests. 

We hope these findings will encourage the design of and investment in climate-informed NbS projects, and we propose that this method could be used in other ecosystems to jointly assess the climate change mitigation and biodiversity impacts of NbS-based management.

How to cite: Maurer, T., Manley, P., Anderson, C., Povak, N., Saksa, P., Kramer, A., and Peery, Z.: Leveraging the co-benefits of large tree protection to inform nature-based management of a forest ecosystem, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13018, https://doi.org/10.5194/egusphere-egu24-13018, 2024.

Modern cities are highly vulnerable to the adverse effects of climate change, primarily due to the escalating frequency of extreme weather events, including heatwaves. The current state of knowledge leaves no doubt that these effects are exacerbated by ongoing urbanization, leading to the continuous sealing of surfaces and a decrease in green areas in urbanized regions, contributing to the formation of Urban Heat Islands (UHI). These phenomena result in urban space degradation, causing economic, environmental, and demographic losses. Consequently, implementing solutions to enhance cities' resilience to climate threats should be a priority for local governments. Crucial in this context is the development of blue-green infrastructure, with a specific emphasis on micro-retention and the improvement of biologically active surfaces and vegetation habitat conditions. The implementation of such solutions, especially in the face of increasing extreme weather events, is essential for ensuring the sustainable development of smart cities.

This paper will present the results of research on the spatiotemporal distribution of the effectiveness of various components of blue-green infrastructure on a city-wide scale (including: river valleys, forests, urban parks, squares, pocket parks, and larger water bodies) in mitigating the UHI phenomenon in Wrocław, Poland. The study assesses the potential of blue-green infrastructure to mitigate the impact of heatwaves on the population most vulnerable to such threats. As an indicator of urbanized areas' vulnerability to the negative health effects of UHI, we focused on the population aged over 65. The research aims to provide crucial insights into how blue-green infrastructure can be optimized to effectively reduce UHI impacts and minimize health risks, especially within the most vulnerable age groups. This operation constitutes one of the initial stages in creating a prototype of a digital twin of the urban environment of Wrocław. The ultimate goal is to model information about blue-green infrastructure for the purpose of optimizing spatial policy in the context of adapting urbanized areas to climate change. This approach aligns with the Destination Earth initiative developed within the framework of the European Green Deal and EU Digital Strategy.

In the research, data integration was performed using various sources, including multispectral imagery from PlanetScope SuperDove, thermal data from ECOSTRESS LST, point clouds from airborne laser scanning (ALS), Topographic Objects Database (BDOT10k), and demographic data from municipal databases. Importantly, the utilized data are openly accessible and free of charge under the principles of Open Science, enabling the replication of procedures in other cities in Poland and, after identification and adjustment of relevant local data, numerous cities worldwide. In Wrocław, the project aims to provide support in creating and modifying existing and new planning documents, including local spatial development plans, the general plan, and the commune development strategy. This action supports the adaptation of local spatial policy to the growing needs of adaptation to climate change. The research is conducted within the program "Implementation Doctorate – 6th edition" by the Ministry of Education and Science.

How to cite: Budzik, G., Kowalczyk, T., Krajewski, P., Lebiedzińska, M., and Soszyńska, A.: Assessing spatiotemporal distribution of the effectiveness of Blue-Green Infrastructure in mitigating the Urban Heat Island phenomenon in Wroclaw, Poland under the Digital Twin concept for spatial policy optimization, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13070, https://doi.org/10.5194/egusphere-egu24-13070, 2024.

EGU24-17239 | ECS | Posters on site | ITS4.6/SSS0.1.5

NBS for secondary wastewater effluents infiltration based on soil and woodchips as drainage material: laboratory study    

Pauline Louis, Laurent Lassabatère, Arnold Imig, and Rémi Clément

Wastewater management and treatment are key points in maintaining the quality and the sustainability of water resources. To preserve receiving  water environments, efforts are being conducted to improve the  treatment efficiency . Soil infiltration can therefore be used as a  nature-based solution tertiary treatment, in some areas without surface  water available, or with supplementary water bodies’ protection  regulations. Secondary wastewater effluents (SWE) infiltration surfaces mainly consist of infiltration trenches or flood-meadows. Among the main issues encountered with soil infiltration, two can be highlighted:  the possible low hydraulic conductivity induced by soil clogging, on the  one hand, and the use of non-renewable draining materials such as  pebbles or gravel to ensure the distribution of water in trenches, on  the other hand. In France, in order to overcome those issues,  stakeholders are now considering the replacement of the gravel with  woodchips, a renewable biodegradable material, also prone to  biodiversity in soils. It has been demonstrated through a previous field study that the use of woodchips in infiltration trenches helps maintain infiltration over time, and even improves their performance. However, understanding the underlying mechanisms remains a significant scientific challenge. To better understand the soil and woodchip evolution processes, four columns were set up in a laboratory and fed with secondary treated effluents from a wastewater treatment plant.

 These four columns (with a diameter of 37 cm) are composed as follows:

  • a) Column #1: 80 cm of soil,
  • b) Column #2: 40 cm of wood chips and 40 cm of soil,
  • c) Column #3: 80 cm of soil inoculated with a selection of earthworms ,
  • d) Column #4: 40 cm of wood chips and 40 cm of soil, inoculated with a selection of earthworms .

During the presentation, hydraulic monitoring of the columns will be presented (inlet and outlet flow, column weight monitoring), showing the evolution of the infiltration rate. To analyze the evolution of physical properties within the columns, including parameters like saturated hydraulic conductivity, a modeling study was carried out using Comsol Multiphysics. Specifically, the Richards model (van Genuchten-Mualem) was employed to simulate and understand the changes occurring over time. The models fit the data well. They mainly show that the soil columns (1 and 3) tend to clog early if the hydraulic loads are too excessive. This is reflected by a reduction of hydraulic conductivity at saturation and porosity. In comparison, columns with wood chips seem to maintain their properties, with no major difference between columns with or without earthworms, after two years of monitoring. These results will be compared to the monitoring of physicochemical parameters of the inflow and outflow waters from the columns, allowing for a better understanding of the processes involving woodchips, soil, and macrofauna.

How to cite: Louis, P., Lassabatère, L., Imig, A., and Clément, R.: NBS for secondary wastewater effluents infiltration based on soil and woodchips as drainage material: laboratory study   , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17239, https://doi.org/10.5194/egusphere-egu24-17239, 2024.

EGU24-18619 | ECS | Posters on site | ITS4.6/SSS0.1.5

Nature-Based Solutions for stormwater management: A case study with Multi-Hydro in Parc Molière, France 

Ismael Ávila Vasconcelos, Pierre-Antoine Versini, and Igor da Silva Rocha Paz

Over the last few decades, the urban hydrological cycle has undergone significant changes due to the influence of the built environment, resulting in rapid runoff and increased risk of flooding. Faced with these challenges, nature-based solutions (NBS) are emerging as an appropriate response, especially in densely populated areas, facing the impacts of climate change and biodiversity loss. The application of green infrastructures, as evidenced by Parc Molière in Les Mureaux, France, with its 700 trees, 11,500 m² of flowerbeds, 8,700 m² of grassland and 5,000 m² of gardens, represents a sustainable approach to urban stormwater management. By reintroducing extensive impermeable areas to the open air, Parc Molière strengthens biodiversity, facilitates animal movement, promotes air cooling and reduces urban heat islands, while also modifying hydrological behavior. Carried out in the framework of the LIFE ARTISAN project, this study uses the Multi-Hydro software, developed at the École des Ponts ParisTech, to computationally model the Parc Molière area in two different scenarios: before and after the creation of the green spaces. Based on a fully distributed and physical hydrological model, Multi-Hydro is able to illustrate the influence of NBS by comparing the obtained simulations with instrumented hydrological data. The results should demonstrate that the NBS have a significant impact on peak flow and total runoff volume, mitigating the negative effects in an urban hydrological scenario.

How to cite: Ávila Vasconcelos, I., Versini, P.-A., and da Silva Rocha Paz, I.: Nature-Based Solutions for stormwater management: A case study with Multi-Hydro in Parc Molière, France, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18619, https://doi.org/10.5194/egusphere-egu24-18619, 2024.

EGU24-18701 | ECS | Orals | ITS4.6/SSS0.1.5 | Highlight

A multi-ecosystem service assessment for urban climate adaptation in Singapore  

Emma Ramsay, Leanne Tan, Yuan Wang, and Perrine Hamel

Nature-based solutions are an important tool to adapt to climate change in cities. Green spaces including nature reserves, parks and green streetscapes are essential to mitigate urban heat and also provide important recreation opportunities that benefit peoples physical and mental health. Effectively planning climate resilient and liveable cites thus requires quantitative, spatially explicit information about these ecosystem services. Such data are especially important in dense cities where vacant land is limited and trade-offs must be made to prioritise certain services. Here we present a multi-ecosystem service assessment for Singapore using the urban InVest models to evaluate urban cooling and urban nature access. We generate future greening scenarios based on policy targets to plant one million trees and increase the land area of parks by 50% by 2030 and compare ecosystem service provision for each scenario when either cooling or nature access is maximised in the spatial configuration of scenarios. We compare the benefits and trade-offs achieved by each scenario and explore the potential to quantify these through health indicators. Finally, we discuss how multi-ecosystem service assessment cans be integrated into urban planning and the implications for cities in an uncertain climate future.

How to cite: Ramsay, E., Tan, L., Wang, Y., and Hamel, P.: A multi-ecosystem service assessment for urban climate adaptation in Singapore , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18701, https://doi.org/10.5194/egusphere-egu24-18701, 2024.

EGU24-18875 | Orals | ITS4.6/SSS0.1.5

Suitability assessment of the location for the Natural Based Solution application on drainage systems 

Milica Vranešević, Milica Knežević, Radoš Zemunac, and Maja Meseldžija

The introduction of Natural Based Solution (NBS) into sustainable agricultural practices is a key issue on which the balancing of intensive agricultural activities with environmental protection depends. In lowland areas with intensive agricultural production, occurrences of extreme amounts of excess water, caused by climate change, increase the need for efficient drainage systems. Within the comprehensive framework of drainage system improvement, NBS are emerging as key and versatile interventions. The principal challenge lies in reconciling these solutions with the prevalent technical paradigms in both land reclamation and agriculture. The most important change is the strategic integration of the use of riparian buffers as supplementary melioration measures in delineated areas, especially aimed at reducing the inflow of excess water into the canal network. Deciding where to implement NBS for better drainage systems comes down to assessing the risks that may occur as a consequence to natural resources such as water and soil. When the implementation of NBS determines the crucial factors and evaluates them effectively, then it can categorize and map the optimal places where improvement of the drainage system is possible and efficient. In this study the aim was to delineate suitable zones for implementing nature-based solutions along watercourses through the application of Geographic Information System (GIS) methodology. By overlaying different layers, including pedological and geomorphological maps, digital terrain models indicating land slope, land use classifications, and drainage classes, it is intended to analyze and identify optimal locations. Some of the characteristic drainage systems in Vojvodina have been selected to provide a relevant case study illustrating how GIS can be applied to demonstrate the potential of nature-based solutions in improving drainage systems. This approach not only enhances the efficiency of the existing drainage systems. It also provides insights for strategic afforestation and the increase of biodiversity in agricultural areas.

How to cite: Vranešević, M., Knežević, M., Zemunac, R., and Meseldžija, M.: Suitability assessment of the location for the Natural Based Solution application on drainage systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18875, https://doi.org/10.5194/egusphere-egu24-18875, 2024.

The main concern with public policies and strategies for integrating nature-based solutions is to facilitate access to innovative interventions to reach cities and communities that are more sustainable and climate resilient. However, there is an impediment to linking information on the results of projects and the expected impact of the European Commission in the framework programmes for research funding. Here we show how projects targeting nature-based solutions help to implement and review public policies under the EU Strategy for Adaptation to Climate Change 2013 – 2020 and European Green Deal. These policies have a positive impact in various areas, especially in green transition, with the potential to analyse the link between the scientific results of nature-based projects and the strategic orientations of research and innovation. We focused on the evaluation of 150 projects funded at the Horizon 2020 and Horizon Europe level, within three main programmes that provide funding for projects based on nature, resilience and adaptation to climate change: (1) Climate action, Environment, Resource Efficiency  and Raw Materials, (2) Climate, Energy and Mobility and (3) Food, Bioeconomy, Natural Resources, Agriculture and Environment. The main analyzed elements are the number and type of partners, the level of funding, the main objectives of the projects, types of nature-based solutions and their distribution by geographical regions in Europe. This analysis leads to the filling in the existing knowledge of the results that produce science, so that it can be exploited throughout the community. Our results consist in (1) overview of climate challenges in EU R&I framework programmes Horizon 2020 and Horizon Europe, (2) Main NBS designed by European R&I organizations, (3) NBS for climate resilience implemented through EU R&I funding in Horizon 2020 and Horizon Europe, (4) NBS for climate resilience – key pathways of knowledge valorization for ecosystem restoration, preservation and management. Overall, they show that the aspects analyzed in the selected funded projects support the development of nature-based solutions and what are the main actions that lead to long-term impact.

How to cite: Barbu, G.-R. and Niță, M.-R.: Nature-based solutions for climate resilience in EU R&I framework programmes Horizon 2020 and Horizon Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19213, https://doi.org/10.5194/egusphere-egu24-19213, 2024.

Rural European landscapes are increasingly faced with the interlinked and cascading hazards of flooding and drought, exacerbated by both unsustainable land use practices and climate change. Sponge measures are particularly promising for addressing such multi-hazard risk from a participatory and social-ecological perspective. Sponge measures are nature-based solutions (NbS) that preserve, restore, enhance or create ecosystems to increase landscape and soil water retention while providing co-benefits for people and nature through biodiversity and ecosystem services. As NbS, they interact in complex ways with the socio-ecological systems (e.g. watershed boundaries) in which they are implemented. Thus, participatory processes are needed to ensure a systemic and interdisciplinary understanding of impacts while capturing diverse stakeholder values and interests. NbS design and planning often lacks 1) a shared understanding of the spatially-explicit impacts of NbS on the social-ecological system among stakeholders; 2) consideration of a broad spectrum of impacts as (co-)benefits and trade-offs; and 3) consideration of scales beyond the immediate measure and within diverging future scenarios.

As a promising approach to address these shortcomings, we propose the use of geodesign - an iterative framework for multidisciplinary, stakeholder-driven, and context-sensitive spatial decisions based on the integration of stakeholder inputs, geospatial data, and technology to generate real-time feedbacks and inform smart decision-making. This process also can support participation through fostering shared understandings and reconciling stakeholder conflicts. Despite promising applications in urban and landscape planning, knowledge is lacking on how and with what impacts geodesign can be applied to facilitate the planning of sponge measures at landscape scale. The aim of our research is to assess the utility of geodesign in the context of adaptive sponge measures by combining a systematic literature review with practical application of geodesign in two European catchments faced with increasing risk of hydrometeriological extremes. The review will quantify the adoption and past effectiveness of geodesign practices in similar landscape planning contexts. Based on these insights, a geodesign approach will be developed and implemented within the EU SpongeScapes project (spongescapes.eu) in selected case studies to generate future scenarios to increase landscape resilience against climate change. We present the research plan, including initial hypotheses and preliminary findings as conducted within the context of ongoing PhD research. With the increasing implementation of NbS in Europe in response to unfolding climate change and its consequences, our research will provide insights into the potential benefits and limitations of geodesign to improve their co-design, support policy creation, and inform decision-making.

How to cite: Jajeh, S., Anderson, C. C., and Albert, C.: Collaborative planning of nature-based solutions for climate resilience at landscape scale: exploring the potential of geodesign, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19504, https://doi.org/10.5194/egusphere-egu24-19504, 2024.

Nature-Based Solutions as a tool to reduce coastal risks have gained in popularity in the last 10 years. However, in France, their development still faces some limits and oppositions from local populations and stakeholders. The main reasons for this are the lack of knowledge and feedback, and the fear of being less protected with against floods with Nature-Based Solutions than with sea walls. This work will present the example of Criel-sur-Mer, in the North of France, where a project of restoration of intertidal habitats to reduce coastal risks is currently discussed and capitalize on feedbacks from three finalized projects from the Netherlands and England.

This study is part of a PhD work on the mobilization of Nature-Based Solutions in coastal protection projects. This presentation is based: on field trips conducted between March and April in the Netherlands and England, on the sites of Hedwige & Prosperpolder (Netherlands, Belgian border), Freiston Shore and Abbotts Hall (England), and in September 2022 and March 2024 in Criel-Sur-Mer (France); on semi-structured interviews conducted with stakeholders on those sites; on semi-structured interviews conducted with 39 coastal engineers and environmentalists between June and August 2023 in Artelia, the engineering firm in charge of the project of intertidal habitats restoration in Criel-sur-Mer; and on observative participation to a public consultation workshop with local actors and stakeholders for the project of Criel-sur-Mer.

The cross-study of the three Dutch and English projects gives us useful examples of the effectiveness of Nature-Based Solutions used as a tool to reduce coastal risks, that can be reused to enrich the project of Criel-sur-Mer. As the two English projects have been finalized in 2002, they are a source of extensive feedback on the evolution of intertidal ecosystems with managed realignment and their efficiency facing storms. The Dutch example started in 2005, but was finalized only in 2023, as it faced numerous social and political oppositions. These projects can thus be used as feedback on governance, project structuration and finding the right balance between different interests for the Criel-sur-Mer example.

How to cite: d'Avdeew, M.: Nature-Based Solutions for coastal risks protection: lessons learned from Dutch and English examples, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20731, https://doi.org/10.5194/egusphere-egu24-20731, 2024.

EGU24-20974 | Orals | ITS4.6/SSS0.1.5

Role of blue and green spaces in mitigating heat stress and providing biodiversity co-benefits in India’s cities  

Jagdish Krishnaswamy, Kiran Chandrasekharan, Dhananjayan Mayavel, and Ravi Jambhekar

Cities and urbanizing spaces combine heat stress from both heat island effect due to the built environment as well as global warming.  India with its high rate of urbanization is no exception. However, many Indian cities have blue and green spaces with various levels of protection from land-use and land-cover change. 

Blue and green spaces (BGS) are potentially nature-based solutions for mitigating heat stress through evaporation and transpiration besides sequestering carbon and as a habitat for urban biodiversity.  The effectiveness of BGS in mitigating heat stress depends on size, shape, weather, and climate variables, especially humidity.  

We use satellite derived land surface temperature (LST) to quantify and map negative temperature anomalies (cooling) with respect to spatial average across the city in years with different levels of summer temperature, especially due to El Nino.   We analyse the diverse types of blue and green spaces in three metropolitan cities in India and classify them in terms of biodiversity value (using e-bird data and other published sources). 

Cooling more than few degrees Celsius with respect to city wide averages from blue and green infrastructure has been observed and is much higher if compared to nearby built areas.  The geometry and landscape ecology of existing urban blue and green infrastructure can help inform future planning for blue and green spaces as adaptation in a warming urban environment. 

How to cite: Krishnaswamy, J., Chandrasekharan, K., Mayavel, D., and Jambhekar, R.: Role of blue and green spaces in mitigating heat stress and providing biodiversity co-benefits in India’s cities , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20974, https://doi.org/10.5194/egusphere-egu24-20974, 2024.

SSS1 – History, Education and Society of Soil Science

EGU24-758 | ECS | Orals | EOS4.4

Méditerranée 2000: Nurturing climate & ocean awareness 

Pimnutcha Promduangsri, Pariphat Promduangsri, and Estelle Bellanger

Humans have been suffering increasingly from the escalating impacts of climate and ocean change.  Well known examples are droughts, flooding, wildfires, acidification, heatwaves, sea-level rise, extreme storms and biodiversity loss.  If global average temperature rises by more than 1.5°C above pre-industrial levels, multiple climate tipping points will be triggered, and indeed, some already are.  This is and will be devastating for people around the world, especially those in coastal areas.  Thus, the need for immediate and informed action has become urgent.

This presentation will outline some of the many concrete, local actions in the area of climate and ocean, undertaken by Méditerranée 2000 (Med2000), an environmental association in the South of France.  Since 1989, the association has committed its efforts and educational programs to promoting sustainable development.  Each year, the association educates more than 25,000 young people and adults, led by a team of ten specialized speakers.  Med2000’s initiatives include awareness campaigns about climate and ocean change, hands-on educational activities in local schools and events for the general public.

How to cite: Promduangsri, P., Promduangsri, P., and Bellanger, E.: Méditerranée 2000: Nurturing climate & ocean awareness, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-758, https://doi.org/10.5194/egusphere-egu24-758, 2024.

Academic researchers have long been advocates of various causes in the public arena; their public advocacy to take normative positions regarding various moral, political or social issues is not new. Today, however, in the face of the many challenges facing our society, the question of researchers' public positions, particularly in relation to the environment and climate change, is being raised anew. A number of climate scientists are committed in a variety of ways, from signing op-eds to participating in the work of NGOs or think tanks, supporting legal actions or writing blog posts. In addition, the development of traditional and social media has significantly increased the public exposure of these researchers. At the same time, serious questions are being raised within the research community. Many of its members are debating the ways in which researchers can engage in such public advocacy, its advisability, and even its very principle. However, these debates are currently taking place in informal settings and, given the extensive individual experience of a number of colleagues, it is probably time to engage in this discussion in a more collective and organised way, as is done in other research communities.

Here are some examples of questions that might be discussed. How can researchers engage in public advocacy safely and responsibly? What is the role of the scientist versus the expert versus the citizen versus the activist? Can a researcher be neutral when taking a public stance? What is the risk of appearing naive, manipulated or irrelevant? How should researchers deal with vested interests and private actors? Should the climate community research geoengineering? For whom should researchers develop climate services?

Because addressing these issues involves a tension between personal values that may go beyond those shared by the scientific community, they are essentially novel ethical questions. Some may be so intimidating that many researchers choose not to engage publicly. Care must therefore be taken to organise the exchange properly, for example by creating safe internal spaces for debate or by inviting experts from other disciplines.

The French CNRS Ethics Committee has recently published on opinions on these issues[1], which I will use as a starting point for a broader discussion.


[1]  https://comite-ethique.cnrs.fr/en/comets-opinion-freedom-and-responsibility-academic-researchers-public-advocacy/

How to cite: Guilyardi, E.: Freedom and Responsibility: the Ethics of Academic Researchers’ Public Advocacy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1344, https://doi.org/10.5194/egusphere-egu24-1344, 2024.

EGU24-2053 | Orals | EOS4.4

Perceiving Cape-Town-Geoethics (CTG) through Symbolic Universes (SU) 

Martin Bohle, Rika Preiser, and Eduardo Marone

Cultural milieus determine the worldviews and practices of individuals and groups, including the reception of norms that guide them. Semiotic Cultural Psychological Theory (SCPT) methods, such as Symbolic Universes (SU), describe relationships of reception, worldviews and practice, which also applies to geo-philosophical matters [1]. This essay outlines how geoethics, for example, the Cape Town Geoethics (CTG), might be received in different cultural milieus.

The Cape Town Statement on Geoethics was proposed in 2016 at the 36th IGC [2] and is the most accessible resource on geoethics. It bundles various concepts in a Kantian/Aristotelian virtue ethics framework, illustrated, for example, by the Geoethical Promise [3].

The SU method describes the understanding, insights, and behaviour of groups of people expressing their respective cultural milieus. Extensive fieldwork identified five SU for people of European (Western) cultures [4]. The SUs called "Ordered Universe", "Interpersonal Bond", "Caring Society", "Niche of Belongingness", and "Others' World" categorise milieus, for example, in terms of relation to power and institutions or sources of trust. They corroborated with the Kohlberg hierarchy of the level of societal coordination [5] that is applicable to associate CTG and the worldviews of individuals and groups [6].

Comparing CTG and SU indicates: (1) CTG resonates most positively with people of the cultural milieu “Ordered Universe” (highest Kollberg level); (2) in other milieus, the reception of the CTG will be “measured”; (3) reception will be adverse for the milieu “Others' World” (lowest Kohlberg level). Hence, considering the quantitative distribution of SUs (in Europe), European citizens' reception of CTG is likely restrained.

Given complex-adaptive social-ecological systems of the World and Nature couple world views, human practices, and societal and natural systems [7] (see example: [8]), whether variants of CTG “fitted to different milieus” should be developed is of practical relevance. The perception of norms and their acceptance or rejection is a system feature, of which geoethics should not be agnostic.

[1] Bohle M (2019) “Homo Semioticus” Migrating Out of Area? In: Salvatore S, et al. (eds) Symbolic Universes in Time of (Post)Crisis. Springer Berlin Heidelberg, Cham, pp 295–307

[2] Di Capua G, et al. (2017) The Cape Town Statement on Geoethics. Ann Geophys 60:1–6. https://doi.org/10.4401/ag-7553

[3] Matteucci R, et al. (2014) The “Geoethical Promise”: A Proposal. Episodes 37:190–191. https://doi.org/10.18814/epiiugs/2014/v37i3/004

[4] Salvatore S, et al (2019) The Cultural Milieu and the Symbolic Universes of European Societies. In: Salvatore S, et al. (eds) Symbolic Universes in Time of (Post)crisis. Springer, Cham, pp 53–133

[5] Kohlberg L (1981) The Philosophy of Moral Development: Moral Stages and the Idea of Justice. Harber & Row, San Francisco

[6] Bohle M, Marone E (2022) Phronesis at the Human-Earth Nexus: Managed Retreat. Front Polit Sci 4:1–13. https://doi.org/10.3389/fpos.2022.819930

[7] Preiser R, Woermann M (2019) Complexity, philosophy and ethics. In: Galaz V (ed) Global Challenges, Governance, and Complexity. Edward Elgar Publishing., Cheltenham, pp 38–62

[8] Talukder B, et al. (2023) Complex Adaptive Systems-Based Conceptual Framework for Modeling the Health Impacts of Climate Change. J Clim Chang Heal 100292. https://doi.org/10.1016/j.joclim.2023.100292

How to cite: Bohle, M., Preiser, R., and Marone, E.: Perceiving Cape-Town-Geoethics (CTG) through Symbolic Universes (SU), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2053, https://doi.org/10.5194/egusphere-egu24-2053, 2024.

EGU24-2607 | Posters on site | EOS4.4

Geoethics literacy:  Clarifying values, principles and behaviour 

David Crookall, Pimnutcha Promduangsri, and Pariphat Promduangsri

Learning about geoethics is not easy partly because the area is relatively new (having emerged in the early 2010s), the concepts are sometimes difficult to fathom and geoethics touches on such a wide area of geoscience phenomena and on such a variety of human issues.

Learning through active, participatory engagement has been developing since the 1960s, and is now deployed, albeit sporadically, across the full educational and training spectrum (from the humanities, through the social sciences to the hard sciences).  Methods that have developed in this learning paradigm include project work, internships, experiential learning, simulation/gaming, values clarification and many more.  We contend that participatory methods are an effective way in which to learn, as supported by much research.

Our poster invites you to participate in a game-like, values clarification exercise.  We have developed a new version of an exercise that we have used in several places (Austria, Costa Rica, France, online) to unravel the knotty relations among values, principles and behaviours related to geoethical issues and dilemmas.

It is possible to play alone, but it is more enlightening and engaging to play in pairs or small groups.  Please bring a friend or two to our poster and participate in our exercise.  The basic process of the exercise can be adapted to your own specific areas of interest.  We look forward to seeing you – please bring a pencil.

(This poster was originally intended as a workshop in a short course, but our SC proposal was declined.)

How to cite: Crookall, D., Promduangsri, P., and Promduangsri, P.: Geoethics literacy:  Clarifying values, principles and behaviour, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2607, https://doi.org/10.5194/egusphere-egu24-2607, 2024.

EGU24-3568 | Posters on site | EOS4.4

Exploring the horizon of geosciences through the lens of geoethics 

Silvia Peppoloni and Giuseppe Di Capua

Geosciences play an indispensable role in the functioning of contemporary societies. Nevertheless, the technological aspects associated with the practical application of geoscientific knowledge, should not overshadow the fundamental contribution of geosciences to shaping human thought. Geosciences have not only influenced but continue to shape our perception of the world, its interrelationships, and evolution.

The ongoing ecological crisis, with its environmental, social, cultural, economic, and geopolitical implications, has stemmed from an imprudent trajectory in human development. Regrettably, there have been instances where geosciences have contributed to this irresponsible path. This oversight has led to an undervaluation of the social and cultural significance inherent in geological disciplines and the crucial role they can play in addressing current global challenges to support human societies.

Geoethics, as the ethics of responsibility towards the Earth system, is grounded in the comprehensive understanding provided by geoscientific knowledge of the complexity of reality. It stands out as the optimal tool for cultivating a new perspective on geosciences, recognizing them as fundamental disciplines crucial for addressing global environmental challenges. This recognition extends beyond technical considerations, emphasizing their cultural significance. By virtue of their epistemological foundations, the geosciences collectively represent an invaluable reservoir of knowledge for human civilization. They are indispensable for redefining the intricate relationship that binds us, as humans, to the Earth.

For this reason, geoethical thought should serve as a complementary element to knowledge in the education of geoscientists. It aims to furnish them with a principled framework and ethical values, offering guidance for any application of geoscientific knowledge to the natural environment and human communities. Additionally, geoethical thought is the ground on which to set a shared, global ethical foundation, facilitating the advancement of our interactions with nature. It seeks to actualize an ecological humanism that forms the basis for human well-being and a more sustainable development of socio-ecological systems. The geoethical perspective redefines the cultural significance and objectives of the geosciences. Geoeducation and communication emerge as fundamental tools for bridging the gap between geosciences and society. They play a crucial role in promoting geoscientific knowledge, highlighting not only its scientific value in providing technical solutions to the ecological crisis but also emphasizing the philosophical dimension of geosciences, the geosophy of living consciously and responsibly within the Earth system.

How to cite: Peppoloni, S. and Di Capua, G.: Exploring the horizon of geosciences through the lens of geoethics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3568, https://doi.org/10.5194/egusphere-egu24-3568, 2024.

EGU24-3586 | Posters on site | EOS4.4

An infrastructure for researching on geoethics and facilitating its international promotion 

Giuseppe Di Capua and Silvia Peppoloni

The development of the theoretical foundations of geoethics and its practical applications have had a notable boost in recent years, seeing the involvement of a growing number of scholars from different disciplines. This has increasingly necessitated the creation of spaces where reflections, discussions, results, and study materials can be shared. The network of scholar relationships has progressively developed physical and conceptual spaces for discussions. The goal has been to sustain conceptual consistency in geoethical thinking by anchoring reflections in the discipline's historical evolution and fostering further developments through open analysis, welcoming contributions from diverse disciplinary backgrounds. Today, what can be defined as a research infrastructure on geoethics and the promotion of its contents possesses a complex structure, serving as a convergence point for various cultural and scientific experiences.

At the core of this infrastructure lies the International Association for Promoting Geoethics - IAPG (https://www.geoethics.org), established in 2012. It consists of an Executive Committee, national sections, and Task Groups focusing on specific topics within geoethics. More recently, two new entities have augmented this infrastructure: i) the Commission on Geoethics of the International Union of Geological Sciences (IUGS), established in February 2023, that is the supporting branch of the IAPG to the IUGS and the IUGS body that officially deals with geoethics and social geosciences for the Union; ii) the Chair on Geoethics of the International Council for Philosophy and Human Sciences (CIPSH, an organization operating under the umbrella of UNESCO), established in December 2023, with the aim of expanding and reinforcing an international research network of institutions, not-governmental organizations, and individual scholars to foster interdisciplinary initiatives for bridging geosciences, humanities, and social sciences through geoethics.

The research infrastructure on geoethics has been enriched over time with two editorial initiatives: a) SpringerBriefs in Geoethics series by Springer Nature (https://www.springer.com/series/16482), founded in 2020 and supported by the IAPG, that envisions a series of short publications that aim to discuss ethical, social, and cultural implications of geosciences knowledge, education, research, practice and communication; b) the Journal of Geoethics and Social Geosciences (https://www.journalofgeoethics.eu/), a diamond open access publication of the National Institute of Geophysics and Volcanology (Rome, Italy) and supported by the IAPG, founded in 2021.

Finally, the research infrastructure on geoethics is complemented by the School on Geoethics and Natural Issues (the “Schola”), founded in 2019 (https://www.geoethics.org/geoethics-school). The “Schola” is a place for teaching and learning of the principles and values of geoethics in the light of the philosophy and history of Earth sciences. The intent is to provide background knowledge and the evaluation skills necessary to understand the complex relationship between human action on ecosystems and the decisions geoscientists make in the discipline that impact society, including improving the awareness of professionals, students, decision-makers, media operators, and the public on an accountable and ecologically sustainable development.

How to cite: Di Capua, G. and Peppoloni, S.: An infrastructure for researching on geoethics and facilitating its international promotion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3586, https://doi.org/10.5194/egusphere-egu24-3586, 2024.

The ocean has started to attract more attention in the recent past with the notions of Blue Economy and Blue Growth becoming rallying points for a new frontier for investments [1]. Many countries and institutions prepare policy papers promising to end poverty, a push for new technologies and profits to fund the development. A recent systematic review of the literature [2], however, found no trace of articulated ethics and justice notions in midst of all the lofty hope and hype surrounding the often blurred concepts. The increasing financialisation of technological developments accelerated through digitalisation and the internet are creating increasing injustices to humans and harm to nature. But, as Rushkoff argues [3], the possibilities for feedback and more circular reasoning have potential to teach everybody that there is no escape from the natural world, thus weaning us from the hyperbole of permanent exponential growth. Here it is argued that critically engaged ocean and geo-sciences with their inherent message of a changing planet through deep time can contribute to debunking the ahistorical promise of fixing self-created problems by starting on a presumed ‘clean slate’. We frequently observe a pattern of wanting to solve the damage provoked by one technology with more technology, e.g. deep sea mining [4] or further technology development in fisheries and aquaculture [5]. At country level, these deliberately disruptive industrial approaches often pay little attention to working with the affected small-scale wild food producers who account for a quarter of global production. Instead, harnessing a combination of traditional and indigenous knowledges and providing intelligible access to the sciences holds significant potential for less destructive pathways. That would also be consonant with the promotion of knowledge co-creation during the UN Ocean Decade in pursuit of a vision of ‘the science we need for the ocean we want’. Practice of co-creation will require some rethinking of the self-image of many sciences and adaptations to typical project formulation and flows. In return, this is expected to produce valuable new insights in addition to opportunities for cooperation and blue justice as steps towards transformations based on ethical principles.

 

[1] World Bank. (2016). Oceans 2030: Financing the blue economy for sustainable development. Blue Economy Development Framework, Growing the Blue Economy to Combat Poverty and Accelerate Prosperity. World Bank Group, Washington DC.

[2] Das, J. (2023). Blue Economy, Blue Growth, Social Equity and Small-scale Fisheries: A Global and National Level Review. Studies in Social Science Research, 4(1):45 p. DOI: https://doi.org/10.22158/sssr.v4n1p38

[3] Rushkoff, D. (2022). Survival of the richest. Escape fantasies of the tech billionaires. Scribepublications, UK, ISBN 978-1-915590-24-4, 212 p.

[4] Zenghui Liu, Kai Liu, Xuguang Chen, Zhengkuo Ma, Rui Lv, Changyun Wei, Ke Ma. (2023). Deep-sea rock mechanics and mining technology: State of the art and perspectives. International Journal of Mining Science and Technology, 33(9):1083-1115. https://doi.org/10.1016/j.ijmst.2023.07.007.

[5] FAO. (2022). The State of World Fisheries and Aquaculture 2022: Towards Blue Transformation. Rome, FAO. doi:10.4060/cc0461en

How to cite: Nauen, C. E.: Can geosciences help inserting social justice notions into Blue Economy narratives?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4054, https://doi.org/10.5194/egusphere-egu24-4054, 2024.

Science indicates that human impact on the planet's climate is clear. Over the past 30 years, climate change has shifted from being primarily a scientific concern to emerging as one of the defining environmental challenges within our society. However, science alone cannot guide us on how to address this crisis. This challenge is also about how we envision living together, what we collectively value, and the level of risk we are prepared to assume. It fundamentally pertains to the kind of society we aspire to, making education a pivotal component. Inspired by the Paris Agreement, the time has arrived for Climate Change Education. It derives its momentum from the aspirations and mobilization of the youth, making it the most potent transformative action in response to climate change.

Climate Change Education comes with unique and exciting opportunities. Firstly, it offers a chance to learn about science in general and climate science specifically, drawing from authoritative sources like IPCC reports. Secondly, it provides an avenue to acquire life skills, humanities knowledge, and insights into global citizenship, imparting a holistic perspective to the young generation on a global scale. Lastly, it fosters critical thinking, hopeful hearts, and empathy in an ever-evolving educational landscape. However, Climate Change Education presents numerous challenges as it strives to balance the development of cognitive, emotional, and practical aspects within existing educational systems. Educators need to be prepared for this unique combination of ‘head’, ‘heart’, and ‘hands’.

The mission of the Office for Climate Education (OCE) is precisely to empower educators in preparing young generations with a robust understanding of climate change and the skills needed to act as global citizens in a changing world. The OCE, driven by collaboration between climate science and educational communities, develops sets of pedagogical resources, offers teacher professional development opportunities, and facilitates networks of practice worldwide. As a pivotal participant in the newly established Greening Education Partnership, the OCE serves as a bridge between the global landscape of IPCC-based science and the specific needs of local primary and secondary educational systems in over 20 countries.

How to cite: Guilyardi, E. and Wilgenbus, D.: Exciting times for Climate Change Education – from global opportunities to local challenges, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6101, https://doi.org/10.5194/egusphere-egu24-6101, 2024.

The National Association of State Boards of Geology (ASBOG) plays an essential role in supporting the licensing of applied geoscientists in more than 30 states in the United States [1] through promulgating model law, rules, and regulations for professional licensure, [2] by developing and implementing the Fundamentals of Geology (FG) and Practice of Geology (PG) exams, and [3] by providing related educational materials.  The content of the FG and PG exams is driven substantially by the results of Task Analysis Surveys (TAS) taken by practicing geologists and academic geologists.  Before 2023, the exams included content related to ethics reflected in the earlier TAS analytical summaries;  however, ethics content is not included in the 2023 TAS or, reportedly, in the current FG or PG exams.
     ASBOG has a history of including applied ethics in its products and organizational structure.  There is a "Code of Conduct/Harassment Policy and Performance Guidelines" for the ASBOG organization on its website (ASBOG.org).  The "Professional Geologist Model Licensure Law" states that each applicant must "submit a signed statement that the applicant has read and shall adhere to any code of professional conduct/ethics and rules established by the Board..." and that the application "be signed and sworn to by the applicant before a notary public" (ASBOG 2017, lines 844-847).  Its "Model Rules and Regulations" includes a sample "Code of Ethics" for licensed professional geologists (ASBOG 2019, p. 27-29).  
     Geoscience professional organizations in the US and internationally affirm the fundamental importance of ethics in academic and applied geoscience.  Virtually all professional organizations relevant to applied-geoscience practice in the United States (e.g., AAPG, AGI, AGU, AIPG, AEG, ASBOG, GSA, SIPES...) have some form of ethics code that their members are obligated to know and adhere to.  The International Association for the Promotion of Geoethics (IAPG -- www.geoethics.org) curates a list of codes of ethics/professional practice and provides publications and educational opportunities supporting geoethics.  Another essential resource is the "Teaching Geoethics" website (serc.carleton.edu/geoethics -- Mogk and Bruckner, 2014-23).
     Robert Tepel (1995) described the essential connection between licensure laws and professional ethics.  To the extent that there is a lack of ethics content in the current 2023 TAS, candidate handbook, exam preparation resources, and FG and PG exams, ASBOG sends a message that applied ethics might not be a core competency for licensed geoscientists -- a message for which there is essentially no support among geoscience professional organizations.
          I suggest that ASBOG collaborate with IAPG and other relevant organizations to address the problems or concerns that resulted in the reported elimination/reduction of ethics content in the application, preparation, and implementation of its FG and PG exams.  Licensed professional geoscientists must continue to understand that geoethics is foundational for their work within society.  For references and resources, visit CroninProjects.org/EGU-Geoethics2024/.

How to cite: Cronin, V.: The need to include ethics content in professional licensure exams in the US (and worldwide), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6136, https://doi.org/10.5194/egusphere-egu24-6136, 2024.

EGU24-6573 | ECS | Orals | EOS4.4

Proposal for a Geoethics Code for the Geoscientist Community of Chile 

Hernán Bobadilla, Luisa Pinto Lincoñir, Pablo Ramirez, Thiare González, José Benado, Nilda Lay, Tania Villaseñor, Millarca Valenzuela, Mohammad Ayaz Alam, and Alejandro Pérez

The proposal of the Geoethics Code (hereinafter “Code”) of the Geological Society of Chile arises as a strategic objective of the Geoethics Group within this institution. The Code encapsulates the principles and values that ethically guide and protect the professional decisions of geoscientists in Chile to protect society and the environment. Likewise, it establishes standards of conduct from the personal to the environmental dimension of professional and scientific practice. Consequently, the Code serves as a valuable tool to the geoscientist community in Chile, facilitating reflection and decision-making within an ethical framework.

Grounded in the principles and values defined by the Geoethics Group of the Geological Society of Chile and the Cape Town Geoethics Declaration of the International Association Promoting Geoethics (IAPG) from 2016 (Di Capua et al., 2017), the Code is built upon four titles: a) Professional and scientific work; b) Geosciences and its relationship with society; c) Geosciences and its relationship with the environment; and d) Contribution to new generations of scientists and professionals in Geosciences.

The construction strategy of the Code underscores the pivotal role of the Chilean geoscientist community. Thus, the Code proposal was enriched through consultations, including surveys, meetings, discussions, and seminars, engaging the Geoscientist Community of Chile to understand their perspectives on pertinent topics and challenges. Furthermore, consultations and reflections were conducted to validate the Code proposal before and during the XVI Chilean Geological Congress in 2023. Ultimately, the Code underwent validation with experts from the IAPG, including geoscientists representing Latin America. Consequently, the Code authentically represents the concerns and challenges of the national geoscientific community while also resonating with the international geoscientific community.

Financing

This project is sponsored by the Geological Society of Chile.

Acknowledgements

To the geoscientist community of Chile, the IAPG experts and other professionals who have participated in the process of construction and reflection on the titles of the proposed Geoethics Code.

References

Di Capua, G., Peppoloni, S., Bobrowsky, P.T., 2017. The Cape Town Statement on Geoethics. Annals of Geophysics, 60, Fast Track 7: Geoethics at the heart of all geoscience. doi: 10.4401/ag-7553.

Keywords

Geoethics Code, Principles and Values, IAPG, Geoscientist Community.

How to cite: Bobadilla, H., Pinto Lincoñir, L., Ramirez, P., González, T., Benado, J., Lay, N., Villaseñor, T., Valenzuela, M., Alam, M. A., and Pérez, A.: Proposal for a Geoethics Code for the Geoscientist Community of Chile, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6573, https://doi.org/10.5194/egusphere-egu24-6573, 2024.

EGU24-6593 | ECS | Posters on site | EOS4.4

Invitation to a research project on geography and climate education 

Pimnutcha Promduangsri

Educational approaches around the world are shaped by diverse geographical factors, including topography, climate, distance, urbanization and societal characteristics.  As a consequence, the methods employed for climate change education (CCedu) are expected to vary according to these geographical factors.

The United Nations Educational, Scientific and Cultural Organization (UNESCO) emphasizes the crucial role of CCedu in fostering an understanding of and effective response to the impacts of the climate crisis.  The Intergovernmental Panel on Climate Change (IPCC) highlights the importance of a globally conscious population for effectively addressing and adapting to climate change challenges.

However, rather than exploring the concept of CCedu or its effectiveness, my research project will focus on identifying the influence of geographical factors on climate change education/literacy.  In the long run, this project could potentially contribute to improving the effectiveness of CCedu.  I invite participants to visit my poster to discuss, share ideas and collaborate on this research project.

How to cite: Promduangsri, P.: Invitation to a research project on geography and climate education, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6593, https://doi.org/10.5194/egusphere-egu24-6593, 2024.

Environmental (in)justice arising from Climate change and urbanization exhibit uneven distributions, specifically impacting disadvantaged communities. While studies in the USA highlight the elevated heat exposure faced by low-income and ethnic minority groups, similar insights are lacking for other countries. This knowledge gap impedes a comprehensive understanding of environmental (in)justice experienced by various socio-economic and ethnic groups and hampers the identification of inadequacy in urban planning policies.

This research seeks to bridge the gap between social and environmental sciences to address environmental (in)justice by establishing a link between extreme heat (at both regional and country level) and socio-economic disparities for Australia and New Zealand. Using remotely sensed satellite data for Land Surface temperature mapping for summer (night time) and Census data of countries, the analysis explores various socio-economic indicators—such as education levels, age demographics, and the proportion of foreign populations.

Australia and New Zealand serve as pertinent case studies due to their distinct socio-economic landscapes and Indigenous populations. By recognizing the unequal distribution of urban heat and its disproportionate impact on vulnerable communities, there emerges a critical mandate to prioritize equitable urban planning policies. This research underscores the urgency for policymakers and urban planners to prioritize environmental justice interventions and integrate strategies that aim to reduce race and class disparities concerning urban heat. The findings also serve as a template for similar analyses globally; fostering inclusive, equitable and resilient urban landscapes.

How to cite: Chawla, J. and Benz, S.: Examining Race and Class Disparities in Urban Heat in Australia and New Zealand: Towards Environmental Justice in Urban Planning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6662, https://doi.org/10.5194/egusphere-egu24-6662, 2024.

EGU24-7655 | Orals | EOS4.4

Delivering Critical Raw Materials: Ecological, Ethical and Societal Issues 

Richard Herrington and Sarah Gordon

Leaders across geographical and political boundaries are united behind a pledge to deliver a net zero carbon world by 2050.  Society’s conundrum is that mining is an essential part of that delivery, yet is an activity regarded by many as unpalatable. Projects that have fallen short on ecological, ethical, or social grounds, serve to confirm to many that mining is currently not an industry to be trusted, rather than being the industry that could and should be empowering significant societal development.

Examples of societal failure include the incidents around the 2012 miners’ strike at the Marikana platinum mine in South Africa which escalated into violence and loss of life.  Failure on ethical grounds was most recently highlighted by the settlement of corruption claims in the Democratic Republic of Congo (DRC) where international mining company staff bribed country officials to secure “improper business advantages.”  Ecological failures are all too common and most visible in the failure of tailings storage facilities such as the 2015 Mariana (Brazil), 2019 Brumadinho (Brazil), and 2022 Jagersfontein (South Africa) dam disasters.

The challenge for those who explore, extract, and process the raw materials so vital for the energy transition, is to do so whilst delivering on true Sustainability right from the start of any project.  Mining disasters are rarely a surprise.  The proactive management of both threats and opportunities is therefore key to the urgent delivery of materials to secure our net zero future in a responsible manner.  We must ensure that this delivery is achieved by projects with wholly net positive outcomes for the environment and people.

How to cite: Herrington, R. and Gordon, S.: Delivering Critical Raw Materials: Ecological, Ethical and Societal Issues, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7655, https://doi.org/10.5194/egusphere-egu24-7655, 2024.

EGU24-8075 | Orals | EOS4.4

Can landslides provide geosystem services? 

Martin Mergili, Christian Bauer, Andreas Kellerer-Pirklbauer-Eulenstein, Jana Petermann, Hanna Pfeffer, Jörg Robl, and Andreas Schröder

The concepts of biodiversity and ecosystem services, focusing on the diversity of life and the services provided to humans by such diversity, in interaction with abiotic ecosystem components, are well established. Only recently, geosciences have started to challenge this rather biocentric view by highlighting that geodiversity – understood as the diversity of minerals, rocks, geological structures, soils, landforms, and hydrological conditions – provides substantial services to society and should be treated as equal partner to biodiversity. It was proposed to use the more general term natural services or, where geodiversity is much more relevant than biodiversity, geosystem services. Even though the term geosystem services is more and more employed in literature, it evolves only slowly into a commonly used concept with a clearly defined meaning. Interpretations range from all services associated with geodiversity which are independent of interactions with biotic nature, to the restriction to subsurface services. None or few of these concepts, however, include risks as negative services, or as costs of services, which is surprising as this would enable a more integrated vision on human-nature relationships. Only very recently, the potential of geosystem service maps to highlight both services and risks related to geomorphological processes was pointed out.

This work picks up landslides as a type of geomorphological process and landform, which is rather negatively connotated in society and associated with risks rather than with chances. We use landslides to develop a broader understanding of geosystem services, together with the common understanding of hazards and risks. We will (i) present a sound and integrated conceptual framework to consider landslides within the field of tension between risks and resources, and (ii) highlight a case study where landslides are used as cultural geosystem services for environmental education in the context of UNESCO Global Geoparks, which are considered important instruments for conserving and promoting geodiversity.

How to cite: Mergili, M., Bauer, C., Kellerer-Pirklbauer-Eulenstein, A., Petermann, J., Pfeffer, H., Robl, J., and Schröder, A.: Can landslides provide geosystem services?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8075, https://doi.org/10.5194/egusphere-egu24-8075, 2024.

EGU24-10646 | Posters virtual | EOS4.4

Protects and Heats 

Walter Tavecchio

The project “Protects and Heats” aims to safeguard the environment, to reduce the carbon dioxide emissions and the risk of collapse of buildings affected by earthquakes.

This is a new way to heat and cool buildings and at the same time mitigate the seismic vibrations.

 

The logic of the project is to create a discontinuity (Moat) in the ground in front of the structures to be protected, similar to damping methods that are implemented to dampen the vibrations produced by mechanical machines and without compromising the stability of the buildings themselves.

The project involves the construction of a double row of aligned micro piles and the insertion of HDPE and steel pipes inside the vertical drilling holes.

Closed circuit geothermal probes will be positioned, inside some vertical holes, with a low enthalpy closed circuit geothermal system.

The method of the project is achieved by combining two types of technologies:

-   The first concerns the interposition, between the direction of the seismic waves and the buildings, of a damping barrier.

The vertical barrier starting from the topographic surface will be positioned outside the buildings, generally orthogonal to the direction of the seismic waves.

-  The second concerns the installation of geo-exchange pipes, in the holes.

How to cite: Tavecchio, W.: Protects and Heats, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10646, https://doi.org/10.5194/egusphere-egu24-10646, 2024.

EGU24-12918 | Orals | EOS4.4

The most consequential ethical decision for geoscience  

Emlyn Koster and Philip Gibbard

A geological definition of the Anthropocene, shorthand for humanity’s cumulative disruption of the Earth-Human Ecosystem, looms as the planet-and-people focused UN approaches its Summit of the Future in New York City on 22-23 September 2024. The International Union of Geological Sciences (IUGS) “aims to promote development of the Earth sciences through the support of broad-based scientific studies relevant to the entire Earth system”. With the UN recently declaring that the planet is in peril and in need of a rescue plan, Anthropocene considerations with a geoethical lens are urgently needed.

Each potential new interval in the Geological Time Scale begins with a working group mandated by the International Stratigraphic Commission (ICS), in the case of the Anthropocene also by its Subcommission on Quaternary Stratigraphy (SQS). The Anthropocene Working Group (AWG) was formed in 2009. In 2010, its first chair Jan Zalasiewicz with co-authors Mark Williams, Will Steffen and Paul Crutzen recognized that “the Anthropocene represents a new phase in both humankind and of the Earth, when natural forces and human forces become intertwined, so that the future of one determines the fate of the other”. In 2015, the AWG’s second and current chair Colin Waters with ten co-authors posed the question "Can nuclear weapons fallout mark the beginning of the Anthropocene Epoch?" in the Bulletin of the Atomic Scientists. This was affirmed in 2019 and the AWG presented its recommendation to the SQS in early 2024. The remaining review and decision steps are the ICS and IUGS. Reflecting concerns of other geoscience scholars as well as of other professions and an anxious public, an opposing mindset advocates for an Anthropocene event that spans the cumulative and ongoing environmental impacts of Homo sapiens. It views Geological Time Scale protocols as unsuitable for archaeological and contemporary developments, regards unemotive references to humanity’s most abhorrent invention as distasteful, and visualizes the Anthropocene Event as valuably informing a new zeitgeist for our troubled world.

In 1950 astronomer Fred Hoyle anticipated that humanity’s first view of the Earth from space would revolutionize the course of history. Insofar as a ‘giant leap of mankind’ did not result from NASA’s Apollo 1969 lunar mission with its estimated 600 million viewers, the Anthropocene Event fuels an opportunity for geoscience to inform a realistic outlook during NASA’s upcoming Artemis lunar mission. With unique knowledge of once pristine environments, current climate change and incipient sea level rise, ongoing biodiversity loss and ecosystem disruption, finite energy and mineral resources, the geoscience profession should arguably have already become a crucial asset in this troubled world.

How to cite: Koster, E. and Gibbard, P.: The most consequential ethical decision for geoscience , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12918, https://doi.org/10.5194/egusphere-egu24-12918, 2024.

EGU24-13965 | Orals | EOS4.4

Ocean Futures: A New Paradigm and Teaching in the Age of Ocean Change 

Susanne Neuer, Stephanie Pfirman, Roberta Martin, Katie Kamelamela, Amy Maas, and Nick Bates

The new School of Ocean Futures (oceans.asu.edu) at Arizona State University (Tempe, AZ, USA) has embarked on a novel way of teaching ocean science with a forward-looking philosophy that centers on the current and future states of the ocean. While situated in Arizona State University’s main campus, it leverages the location of its two offshore campuses, the Center of Global Discovery and Conservation Science in Hilo, Hawaii, and the Bermuda Institute of Ocean Sciences (BIOS) in Bermuda. The Ocean Futures programs combine aspects of traditional ocean science teaching with ocean stewardship, partnerships, and Indigenous knowledge, and focus on the communities that live with the ocean and are affected by its rapid change. In this presentation we will introduce the curriculum of the new degree, as well as the challenges encountered, and best practices learned. Novel courses include “Introduction to Ocean Futures”, a capture course that aims at increasing the interdisciplinary knowledge of oceans, while actively seeking to increase diversity and retention in the field via inclusive pedagogical practices, the historical context of oceanography and an emphasis on developing a mindset of empowerment for change. It is followed by “Ocean Communities”, a course that immerses students through an ethnobotanical lens in global mountain to ocean cultural connections, while elaborating on how various human communities engage, exchange, and build relationships with regional resources. The students will receive hands-on aquatic knowledge through field courses at BIOS, the Sea of Cortez, Hawaii, and Antarctica. The curriculum culminates with an ocean workshop and capstone course that will allow the students to work directly with partners to address real-world challenges facing coastal communities and marine systems.

 

 

How to cite: Neuer, S., Pfirman, S., Martin, R., Kamelamela, K., Maas, A., and Bates, N.: Ocean Futures: A New Paradigm and Teaching in the Age of Ocean Change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13965, https://doi.org/10.5194/egusphere-egu24-13965, 2024.

In the Anthropocentric era, the human-driven climate crisis has become a serious global issue. To mitigate the impacts of climate change, it is crucial for humans to adopt a more sustainable way of living. Human behaviors are shaped by their culture, where religious beliefs play important roles. As a result, people turned to religions for addressing with climate change issues.

Seeming to be unrelated, religions and climate issues have found connections through social systems and communication. By endowing climate issues with religions meanings, religions are able to resonate with the ecological crisis and take meaningful actions. Through this "resonance," religions contribute to climate issues by shaping worldviews, establishing sustainable habits, initiating actions, and influencing policies.

Religious communities have recognized the severity of the human-driven climate crisis. Their call for action reflects the fact that Taiwanese society has failed to respond to the climate crisis due to its endless pursuit of consumerism. To deal with the challenges, religious communities have advocated for “Ecological Conversion”, which persuade people to save the nature for the sake of God.

How religions can empirically contribute to environment issues has been a long-discussed topic. However, previous literatures only focus on the Western-Christian World. Countries with religious beliefs other than Judeo-Christian ethics are seldom discussed. To explore the relationship between religion and climate in Asian contexts, this research will focus on Taiwan, a multicultural country with various religions.

Using the sample data from the 2020 Taiwan Social Change Survey, this study aims to explore the relationship between religion and climate by conducting factor analysis and ordinary least squares regressions.

The evidence reveals a weak connection between religions and people's climate attitudes in Taiwan. Among all the religions in Taiwan, Buddhists and Christians tend to have the most eco-friendly attitudes. The social networks within these two religious communities foster an eco-friendly atmosphere, which highlights the importance of environmental conservation. However, when it comes to peoples’ willingness to pay, faith holders are less likely to show their supports.

By illustrating the religion-climate relationship in Taiwan, this study demonstrates how these two fields intersect in a non-Western society. It also provides implications for how religions can inspire people's willingness to engage in environmental conservation efforts.

How to cite: Tsui, C. H.: Do religions matter? The empirical study of the religion-climate relation in Taiwan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14027, https://doi.org/10.5194/egusphere-egu24-14027, 2024.

EGU24-14752 | Posters on site | EOS4.4

Towards sustainable management of georesources: the importance of Cooperation Projects to boost education on responsible and sustainable mining. The example of the SUGERE and GEODES projects. 

Giovanna Antonella Dino, Susanna Mancini, Dolores Pereira, Manuela Lasagna, Francesca Gambino, Guido Prego, Domingos Gonçalves, Aida Jacinto, Daud Jamal, Josè Loite, Hélio Nganhane, Nelson Rodrigues, and Pedro Dinis

Sustainable and responsible management of geo-resources requires a rethinking and redesign of our production and consumption patterns. Awareness of the natural environment as a common good to be preserved, and knowledge of the close link between the natural environment and the socio-economic system are prerequisites for a profound change in human attitudes at both individual and societal levels. In this context, training and education of all actors involved in the management of geo-resources is an indispensable starting point for the acquisition of critical, ethical, and conscious thinking and the technical skills necessary to solve local problems and initiate sustainable development.

The present research focuses on two consequential ERASMUS+ projects: SUGERE and GEODES. Both had the common goal of the international standardization of Higher Education training and teaching in Earth Sciences and Mining Engineering.

SUGERE (Sustainable Sustainability and Wise Use of Geological Resources) was successfully completed in September 2023, involved 3 European universities (from Portugal, Spain, and Italy) and 6 non-European universities (from Mozambique, Cape Verde, and Angola). The objective was to enhance capacity building for the responsible and sustainable use of geological resources by supporting the didactic organization and standardization of 5 degree courses at Bachelor, Master and Doctorate levels in Earth Sciences and Mining Engineering. Both online and face-to-face training sessions were organized in European and African universities.

GEODES, started in June 2023, represents the continuation of the SUGERE project and involves a total of 9 partners. The same 3 European universities and 6 African institutions, formally attributing teaching and training roles to 2 universities that participated in SUGERE, already achieved a good standard in terms of infrastructures and have long teaching experience in the field of geosciences, and receiving 4 young institutions from less favored regions of Angola and Mozambique.

SUGERE and GEODES projects aim to strengthen the role of geosciences in the development of up-to-date strategies for the sustainable management of natural resources and to implement new collaborations thanks to an international network focused on local economic and social development and respect for the natural environment in the geological-mining context. The culture of sustainability and the deepening of skills in the field of geological mining form the basis for the development of the critical thinking necessary for local problem solving, the acquisition of ethical values and the technical skills that underpin sustainable development.

Deepening technical skills in geomining from a sustainable perspective is crucial for developing critical thinking and acquiring ethical values necessary for solving local problems. SUGERE and GEODES contribute to this outcome with a solid network of research, training, sharing and exchange of expertise and research activities between European and non-European universities interested in mining issues. A careful analysis of the local economic development of the countries involved in the projects is required to achieve the most effective methods for the exploration and sustainable exploitation of underground georesources.

 

How to cite: Dino, G. A., Mancini, S., Pereira, D., Lasagna, M., Gambino, F., Prego, G., Gonçalves, D., Jacinto, A., Jamal, D., Loite, J., Nganhane, H., Rodrigues, N., and Dinis, P.: Towards sustainable management of georesources: the importance of Cooperation Projects to boost education on responsible and sustainable mining. The example of the SUGERE and GEODES projects., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14752, https://doi.org/10.5194/egusphere-egu24-14752, 2024.

Since time immemorial, nature, and by extension the ocean, have made positive contributions to the health of mankind. Whether it be fertile soil, pollination, medicine, taking part in mindfulness activities, or food, we as a species depend on the many services provided by the natural world.  Our environment can be linked to some fundamental determinants of health, such as clean air, clean water, and balanced nutrition, and emotional wellbeing.  Therefore, any environmental degradation as a result of climate change has undeniable tangible and intangible effects on human health all over the globe, and this is especially true in relation to mental health in populations occupying Large Ocean Island States (LOIS).   As climate change has led to an increase in extreme weather events, and the accompanying devastation, there has been a corresponding decrease in health and quality of life.  This presentation will explore how the impact of climate change and its corresponding impact on the ocean has enduring impacts, both physiologically and mentally.   Therefore, all of the processes and recommendations to combat climate
change will have important co-benefits to mental and physical health, and help to build resilience in the face of the dearth of resources faced by LOIS. This lack of resources must be urgently addressed, and solutions can be explored by fostering collaboration between mental health professionals and climate scientists to collect sufficient data. The resulting findings can be used to expedite access to the funds needed to implement the necessary levels of mitigation and adaptation specifically tailored to the infrastructural realities of LOIS.

How to cite: Alvarez de la Campa, S.: Climate Change, Ocean Health and Quality of Life - An Inextricable Connection in Large Ocean Island States, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16730, https://doi.org/10.5194/egusphere-egu24-16730, 2024.

EGU24-17346 | Posters on site | EOS4.4

The importance of making geoethics a central concern of Sri Lankan education strategy 

Giuseppe Di Capua and Udaya Gunawardana

Like numerous regions worldwide, Sri Lanka faces significant environmental challenges that endanger its biodiversity, natural resources, and the well-being of its population. Predominant issues encompass water and air pollution, land degradation, deforestation, improper waste disposal, consequences of climate change, disaster risks, as well as the loss of biodiversity and geodiversity. The nexus between political, economic, and social factors contributes to these geo-environmental challenges, often exacerbated by the politicization of the environmental issues in Sri Lanka. However, it is crucial to acknowledge that human activities primarily drive these conditions. Gunnar Myrdal’s Soft State theory asserts that despite the existence of multiple governing bodies, regulations, and laws, humans strategically transcend the environment leading to the depletion of geo-environmental resources within a context of strong societal inequalities, particularly in developing countries influenced by the historical conditioning of colonial interests by developed nations. A philosophical exploration of this issue emphasizes the pivotal role of human indifference towards the environment and natural resources in causing these challenges. To address this issue effectively, a transformation in people's attitudes is imperative, and education emerges as the most potent tool for this purpose. However, a careful analysis of Sri Lanka's primary and secondary school curricula reveals an absence of a dedicated discipline addressing the philosophical and social dimensions of the geo-environmental matter. In light of this, the incorporation of subjects such as geoethics, which specifically addresses the ethical problems in the human-environment interaction, becomes paramount. Integrating geoethics into the educational framework, particularly at primary and secondary levels, stands as the foundation of a sustainable and responsible strategic approach to many societal and environmental problems. This educational strategy should envision as the most important solution to mitigate the majority of geo-environmental problems in Sri Lanka, fostering environmentally sensitive and responsible citizens.

How to cite: Di Capua, G. and Gunawardana, U.: The importance of making geoethics a central concern of Sri Lankan education strategy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17346, https://doi.org/10.5194/egusphere-egu24-17346, 2024.

EGU24-17614 | Orals | EOS4.4

Choice Question (MCQ) Peer Construction for Training Students as Climate Change decision-makers or Knowledge Spreaders 

Gérard Vidal, Charles-Henri Eyraud, Carole Larose, and Éric Lejan

After more than 40 years of reasoned alerts from the scientific community directed towards society, with minimal impact, a recent surge in the size and frequency of extraordinary climatic events has begun to reshape the perspectives of ordinary citizens. This situation underscores the challenge of directly influencing society with scientific evidence or models, emphasizing the crucial role of universities in training students who will occupy intermediate or elevated positions that may impact society at large.

While "Climate Fresk" has gained widespread popularity in higher education institutions as an effective tool for raising awareness about climate change and the intricate processes affecting our global earth ecosystem, concerns have arisen at the university level. The repetition of "Climate Fresk" or similar tools may be perceived as greenwashing practices, as university students are already well-acquainted with the issue. Hence, there is a need to surpass mere awareness in higher education.

As TASK Change Leaders at ENS-Lyon, we explored pedagogical and assessment tools provided by Sulitest. This initiative, extends beyond climate and ocean changes, it places a significant emphasis on various topics, including Sustainable Development Goals, earth limits, and driving processes of climate change. One of the major interest of the approach is to address all disciplines (scientific or non scientific).

We built a three-step strategy involving:

  • Administering a positioning test to enable students to assess their performance relative to the institution and the wider community.

  • Utilizing the looping tool from Sulitest, wherein small teams of students generate Multiple Choice Questions accompanied by a list of academic publications validating the terms of their questions. Subsequently, these questions are discussed in large interdisciplinary open groups, compelling students to articulate questions and answers intelligible across all disciplines.

  • Participating in the TASK to receive an assessment of their proficiency in sustainable development, evaluated by an external body.

This strategy, particularly the second step, empowers students to assume the role of a teacher or knowledge spreader in the face of a diverse peer community. It serves as a simulation of their potential future roles as educators, knowledge spreaders or decision-makers, instilling an understanding of the importance of providing validated sources and the challenges associated with crafting questions and answers comprehensible to all, preparing them for future teaching or decision-making scenarios. A notable byproduct is the creation of valuable pedagogical resources in a "connectivist MOOC flavor."

Beyond the training benefits, membership in the TASK Change Leaders group provides opportunities for discussions on the sustainability of education, green education, and competency frameworks, to apply to ourselves the concepts we are teaching.

How to cite: Vidal, G., Eyraud, C.-H., Larose, C., and Lejan, É.: Choice Question (MCQ) Peer Construction for Training Students as Climate Change decision-makers or Knowledge Spreaders, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17614, https://doi.org/10.5194/egusphere-egu24-17614, 2024.

EGU24-20953 | Posters on site | EOS4.4

Shaping Thriving Ocean Futures – Education to advance healthy coastal communities and marine systems 

Susanne Neuer, Stephanie Pfirman, Roberta Martin, Katie Kamelamela, Amy Maas, Andrew Peters, and Nick Bates

The new Ocean Futures program at Arizona State University (Tempe, AZ, USA) prepares students to become coastal and marine stewards, community leaders, innovators, and researchers capable of shaping the future of the world's oceans.  The program is taught and mentored by faculty and community leaders in an environment that supports our students’ individual and collaborative strengths, creativity, and diversity.  Students learn and work across disciplines, exploring global and local ocean dynamics, ecosystems, and stressors, engaging with community contexts and livelihoods, and advancing culturally-appropriate, reciprocal stewardship.  In support of ASUʻs mission of embeddedness and linking innovation to public value, graduates of the School of Ocean Futures are equipped with the knowledge and skills to work with diverse communities and partners to create innovative solutions for our changing world.

The School of Ocean Futures educational goal is to build student capacity to apply knowledge of coastal and marine systems coupled with community partnerships to help shape thriving futures, both locally and globally.  Students engage in research and work with partners in Arizona, the Bermuda Institute of Ocean Sciences (BIOS) in Bermuda, the Center of Global Discovery and Conservation Science in Hilo, Hawaii, the Sea of Cortez, and Antarctica.

Ocean Futures education at ASU is based on an innovative “cascade” curriculum.  The cascade starts with core classes in Introduction to Ocean Futures and Ocean Communities, followed by foundational courses in sciences and mathematics, an upper-level core class in Oceanography, electives focused on partnerships, stewardship, and advanced problem-solving, and culminates in an applied workshop and capstone course where students work with partners to transfer knowledge to action in addressing problems facing coastal communities and marine systems.

How to cite: Neuer, S., Pfirman, S., Martin, R., Kamelamela, K., Maas, A., Peters, A., and Bates, N.: Shaping Thriving Ocean Futures – Education to advance healthy coastal communities and marine systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20953, https://doi.org/10.5194/egusphere-egu24-20953, 2024.

Fifty years ago, Peter Berg developed a way to locate yourself within your bio-region, starting with your watershed. To begin, trace your water from precipitation to tap—and back to precipitation. Then, how much rain fell in your area last year? How much water does your household consume per month? What percentage of your town’s water supply goes to households? to manufacturing? to farming? to golf courses? to mining operations? to extinguishing fires? What pollutants affect your water supply? Once you can map your local water supplies, consider how manufacturing transistors, operating data storage centers and streaming videos impact international waters. With awareness of our daily lives’ impacts on local and international waters, we can create realistic limits.  

How to cite: Singer, K.: Mapping water from our tap to the watershed: A first step toward ecological limits  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21221, https://doi.org/10.5194/egusphere-egu24-21221, 2024.

This ongoing project integrates the concept of science diplomacy, conducting an in-depth exploration of the intricate interrelations among geo-bio-cultural diversity and its pivotal role in peace building, risk management, and climate action in Colombian cities and territories. Leveraging geodiversity assessment and its correlation with biodiversity, we explore how the bio-geo duplex interacts with ethnic diversity in Colombia. The aim is to develop initiatives aligned with the ancestral knowledge of indigenous, African-descended, farmers, and mixed-Colombian communities across cities and territories withing the geoethics concept.
In the realm of science diplomacy, our emphasis lies in cultivating international collaboration and knowledge exchange to tackle intricate societal challenges. We seek to foster dialogue and cooperation among traditional and nontraditional actors, advocating for the integration of scientific expertise with local and indigenous knowledge. The study provides a comprehensive analysis, considering historical, environmental, economic, social, and political contexts. It sheds light on how these interactions unfold and their diverse representations across Colombia, including the Caribbean, Pacific, and Andean regions.

How to cite: Marin-Ceron, M. I.: Science Diplomacy with Nontraditional Actors: Enhancing Geo-Bio-Cultural Diversity in Colombian Cities and Territories, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22117, https://doi.org/10.5194/egusphere-egu24-22117, 2024.

EGU24-410 | ECS | Orals | EOS3.1 | Highlight

Family-Friendly Conferences in the Geosciences 

Elena Päffgen, Leonie Esters, and Lisa Schielicke

Participation in (inter-) national conferences, seminars, and workshops such as the EGU General Assembly is important for professional exchange and personal networking, especially for early career scientists. Enabling scientists with family obligations to take part in conferences will increase gender equity and diversity, as women remain to be the main caregivers in most families.

The questions of family planning and kickstarting a professional career arise simultaneously in almost any field. What makes this particularly challenging for young families in academia is that this line of work frequently requires for parents to move, making traditional forms of supportive caregiving by extended family members often unavailable. The vital role conference attendance plays for an academic career only aggravates that challenge. Therefore, a lack of opportunities to attend conferences and workshops clearly puts young parents at a disadvantage, especially young women in academia.

The Project for Family-Friendly Conferences has been initiated by Leonie Esters and Lisa Schielicke from the Department of Geosciences at the University of Bonn in April 2023. Elena Päffgen joined as a research assistant (WHK) later the same year. With an initial duration of one and a half years the project is funded by the Gleichstellungsbüro (office for equal opportunities) of the university. Our principal goal is to find out, how conference and workshop participation can be made more family-friendly.

The present work analyses an online survey with 245 participants who were interviewed on the topic of family-friendly conferences. The survey was addressed to all scientists with a focus on geosciences, 58% of all participants claimed to have children, while 42% were childless. 61 comments expressing wishes and needs of parents and guardians we received from the participants underscore the urgency of the matter. Key concerns of the participants were clear communication (e.g., whether children could be brought along to the events in question), awareness among event-organizers, and easy access to financial assistance (e.g. for babysitting). For instance, more hybrid events, on-site childcare and designated family-friendly activities at conferences were named as possible improvements. However, considering that families and their challenges are diverse, a wide array of offers and flexibility are required to address their needs.

Our project aims to educate the wider academic community on family-specific challenges. Based on the results of this survey, we will provide conference organizers with guidelines to improve family-friendliness of conferences and facilitate their exchange among each other. Additionally, we want to keep parents informed about the offers for families that are already in place at conferences in our field of study. Overall, we are convinced that outcomes of our project will be beneficial for conference and workshop organizers likewise as for researchers who are parents and will contribute to gender equity and diversity in academia.

Children, parents and guardians are particularly welcome to the poster presentation and discussion.

If you would like to participate in our survey: https://www.empirio.de/s/VxLGGLxWv2

 

 

How to cite: Päffgen, E., Esters, L., and Schielicke, L.: Family-Friendly Conferences in the Geosciences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-410, https://doi.org/10.5194/egusphere-egu24-410, 2024.

The European Geosciences Union (EGU) is the leading organisation supporting Earth, planetary and space science research in Europe, upholding and promoting the highest standards of scientific integrity, open science and open access research. EGU’s vision is to realise a sustainable and just future for humanity and the planet through advances in Earth, planetary and space sciences.

The EGU awards and medals programme acknowledges distinguished scientists every year for their exceptional research contribution to the Earth, planetary and space sciences. Furthermore, it recognises the awardees as role models for the following generation of early-career scientists, encouraging geoscience research. 

Except for EGU council and award committee members everyone (including non-EGU members) is eligible for receiving an EGU award. Nominations need to be submitted by EGU members online by 15 June every year. Each EGU medal or award is selected through a rigorous assessment of the candidates and their merits through the respective committee. The procedures for nomination, selection of candidates and the time schedule are described in detail on the EGU website. 

EGU is committed to recognizing scientific excellence providing equal opportunities. The processes and procedures that lead to the recognition of excellence must be transparent and free of biases. However, establishment of clear and transparent evaluation criteria and performance metrics to provide equal opportunities to researchers across gender, continents and ethnic groups can be challenging since the definition of scientific excellence is often elusive. 

The purpose of this presentation is to share the experiences and efforts of the European Geosciences Union to ensure equal opportunities. The presentation will showcase data and statistics to provide constructive directions towards the objective of offering equal opportunities to researchers from diverse demographic backgrounds.

How to cite: Blunier, T.: Equality of opportunities in EGU recognitions: The EGU Awards Committee experience, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1620, https://doi.org/10.5194/egusphere-egu24-1620, 2024.

EGU24-9435 | ECS | Orals | EOS3.1 | Highlight

Navigating parenthood as an early career scientist: insights and challenges from hydrological sciences 

Diana Spieler, Lina Stein, and Rodolfo Nóbrega

Combining an academic career with caretaking responsibilities is an often-overlooked challenge. Juggling the workload, conference attendance, or the potential requirement to move to a new job all become more demanding when children or other caretaking responsibilities are a part of your life. We, members of the Young Hydrology Society (YHS), wanted to hear some views from academic parents in hydrology. What are the challenges they face, what is their advice to other parents and what systematic changes would they like to see? This non-scientific initiative gathered responses from academics within the hydrology community from different parts of the world at different career stages, including PhD candidates, postdoctoral researchers, assistant professors, and group leaders. The survey revealed diverse challenges and strategies employed by academic parents to balance their professional and personal lives. We identified a complex interplay of personal, institutional, and cultural factors that influence these experiences in academia. A common theme across responses was the strategic timing of parenthood, often aligned with phases of planning security, such as after having won a longer-term grant. Despite the varying international backgrounds, many responses highlighted the supportive role of national policies, particularly in countries like Sweden, which offer substantial parental support and flexible work arrangements. However, challenges such as reduced research productivity, lack of support to attend conferences, and the need to relocate were frequently mentioned as limiting factors for career development and progression. Among the strategies employed to minimise these challenges, we highlight adjusting work schedules, reducing workloads, and relying on support from partners and extended family. Childcare distribution varied, with many striving for an equitable split between partners, though this was often influenced by career demands and cultural standards or expectations. The responses also contained suggestions for systemic improvement, including extended childcare facilities at conferences, more flexible job contracts, and institutional support for parents, particularly during fieldwork and conferences. While there are notable advancements in some areas, there remains a significant need for systemic changes to better support academic parents and ensure a more inclusive and equitable academic environment. It is fundamental to highlight, however, that the results of this initiative do not capture the entire spectrum of experiences faced by those with caretaking responsibilities, and that our survey is likely to be biased towards ECS who still were engaged and successful in their work. We aim to release these results as a series of blog posts on the YHS webpage (https://younghs.com/blog/) to disseminate this topic with the main aim of offering valuable reassurance to current and future parents in academia facing similar challenges.

How to cite: Spieler, D., Stein, L., and Nóbrega, R.: Navigating parenthood as an early career scientist: insights and challenges from hydrological sciences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9435, https://doi.org/10.5194/egusphere-egu24-9435, 2024.

EGU24-9557 | Orals | EOS3.1

Diversity at a Small Geoscience Conference 

Alice Lefebvre and Renée Bernhard

Conferences are places where intellectual and communication standards are shown. Ultimately, they can contribute to create a sense of belonging or inadequateness. However, several analyses of specific diversity measures have demonstrated that large conferences often lack diversity in terms of gender, geographic location or race. The present contribution presents an analysis of the gender, country of affiliation and student status of the participants and presenters during four instances of a small European geoscience conference, as well as the length of presentation and number and tone of questions of the latest instance of this conference. We found that women make up about one-third of participants, session chairs, invited keynote speakers, and presenters (oral and poster) on average, but percentages vary greatly from one year to the next. Students represent around 30% of participants, but over 40% of poster presenters and 28% of long presentations. In total, only half of the participants asked a question, and most of the questions were asked by senior men. Around 25% of the questions were asked with a friendly tone; the remainder were neutrally asked. Friendly questions were asked more frequently after keynote lectures and long presentations than following short talks. We suggest concrete actions that can be taken to promote the development of an inclusive and supportive environment at small conferences.

How to cite: Lefebvre, A. and Bernhard, R.: Diversity at a Small Geoscience Conference, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9557, https://doi.org/10.5194/egusphere-egu24-9557, 2024.

EGU24-10508 | ECS | Posters on site | EOS3.1 | Highlight

An Evaluation of the ADVANCEGeo Partnership Bystander Intervention Model 

Blair Schneider, Christine Bell, Stefanie Whitmire, Horinek Hannah, Meredith Hastings, Rebecca Barnes, Allison Mattheis, Billy Williams, and Erika Marin-Spiotta

The ADVANCEGeo Partnership program, funded by a National Science Foundation ADVANCE award in 2017, was designed to empower geoscientists to transform workplace climate, and has been recently adapted to other STEMM disciplines as well. To date, the ADVANCEGeo Partnership has led over 230 workshops to institutions across the USA and Europe, in both virtual and in-person formats. A main strategy of ADVANCEGeo for organizational climate change is to enact interventions at the individual and collective level through behavior change education informed by intersectionality and ethics of care frameworks. The program uses a community-based model for bystander intervention and workplace climate education designed to give members of the academic community the knowledge and tools to identify, prevent, and mitigate harm from exclusionary behaviors that directly affect the retention of historically excluded groups in STEMM. 

Evaluation data from 81 workshops held between 2018-2022 were analyzed using a transtheoretical framework of behavioral change. All of these workshops used a consistent structure and length of presentation (averaging 2.5 hours overall). Thirty six workshops were conducted in-person (44%) and forty five workshops were conducted virtually (56%) using the Zoom platform. The workshops were conducted for a variety of audiences, including institutional leadership, academic departments, professional societies, research groups, and student groups. Each workshop included the same core components, though some materials in the presentation portion were tailored to the needs of the audience as requested. Evaluation results show positive increases in participant knowledge, satisfaction, and intent to change behavior directly after the workshop. An additional follow up survey that was disseminated approximately 6 months after the workshop provides evidence of longitudinal behavior change. These results demonstrate that the ADVANCEGeo Bystander Intervention model design successfully shifts behaviors in workshop participants, with an aim to create more positive workplace climates for all seeking to be a part of STEMM.

How to cite: Schneider, B., Bell, C., Whitmire, S., Hannah, H., Hastings, M., Barnes, R., Mattheis, A., Williams, B., and Marin-Spiotta, E.: An Evaluation of the ADVANCEGeo Partnership Bystander Intervention Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10508, https://doi.org/10.5194/egusphere-egu24-10508, 2024.

EGU24-11929 | ECS | Orals | EOS3.1 | Highlight

Promoting and Supporting Equity, Diversity, Inclusion, and Accessibility: A Collaborative Approach in the Hydrogeological Community and Beyond 

Luka Vucinic, Viviana Re, Barbara Zambelli, Theresa Frommen, Fatima Ajia, and Shrikant Limaye

The International Association of Hydrogeologists (IAH) is a scientific and educational charitable organisation for scientists, engineers, water managers and other professionals working in the fields of groundwater resources planning, management and protection. Comprising various commissions and networks, IAH engages in activities such as contributing to groundwater science, outreach, education, and training. While IAH takes meaningful steps towards equity, diversity, inclusion, and accessibility, recognising the importance of putting these principles into practice, it is essential to acknowledge that there are still numerous challenges and barriers that need to be addressed. It is worth noting that IAH shares similar challenges with many other organisations and associations in navigating the path towards greater equity, diversity, and inclusion. Therefore, the establishment of a dedicated working group became imperative to address and overcome these challenges effectively.

The Socio-Hydrogeology Network (IAH-SHG), an official IAH network, aims to integrate social sciences into hydrogeological research, and has two active working groups: the Working Group on Groundwater and Gender, and the newly established Equity, Diversity, Inclusion, and Accessibility (EDIA) Working Group. This group is designed to further enhance the EDIA landscape within the IAH and beyond. It is the result of collaborative endeavours, extensive discussions, and productive meetings within the IAH and IAH-SHG, and it builds on the work and experience of the Working Group on Groundwater and Gender and the IAH-SHG in general. We will showcase the key insights gained from our IAH-SHG experiences and demonstrate how we applied these lessons to facilitate the establishment of the EDIA Working Group.

By harnessing the power of collective effort, the EDIA Working Group aims to foster a positive impact that resonates throughout the IAH and wider hydrogeological community. We will present our experience regarding the pivotal role of networks, such as IAH-SHG, in advancing equity, diversity, inclusion, and addressing barriers within the geosciences. We will also share our plans for collaboration with other IAH commissions, networks, IAH members, and other individuals (i.e. membership in the IAH is not a prerequisite for individuals interested in joining the IAH-SHG or any of its working groups), as well as ideas and recommendations for new and innovative strategies to identify and overcome barriers. Furthermore, we will share the EDIA Working Group's experience so far, providing insights that may be valuable for other associations, organisations, and groups facing similar challenges.

How to cite: Vucinic, L., Re, V., Zambelli, B., Frommen, T., Ajia, F., and Limaye, S.: Promoting and Supporting Equity, Diversity, Inclusion, and Accessibility: A Collaborative Approach in the Hydrogeological Community and Beyond, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11929, https://doi.org/10.5194/egusphere-egu24-11929, 2024.

EGU24-12182 | ECS | Orals | EOS3.1 | Highlight

Is my teaching gender-fair? A self-assessment questionnaire. 

Sílvia Poblador, Maria Anton-Pardo, Mireia Bartrons, Xavier Benito, Susana Bernal, Eliana Bohorquez Bedoya, Miguel Cañedo-Argüelles, Núria Catalán, Isabel Fernandes, Anna Freixa, Ana Genua-Olmedo, Elisabeth León-Palmero, Anna Lupon, Clara Mendoza-Lera, Ada Pastor, Pablo Rodríguez-Lozano, Aitziber Zufiaurre, and María del Mar Sánchez-Montoya

The study of inland waters - Limnology - is full of fascinating women who have vastly contributed to our understanding of these valuable ecosystems. Although women’s visibility was low during the early years of Limnology, it has increased over time. Nowadays, women represent half of the early-career limnologists in Europe. However, as in many other fields, their scientific contributions have been traditionally neglected from schools to universities (i.e., the Matilda effect). The project “Gender LimnoEdu”, developed by the Gender&Science AIL group and funded by EGU (2020), aims to increase the visibility of women in Limnology and related subjects - such as Ecology, Hydrology or other Geosciences - in academic courses and lectures. We have created a set of online ready-to-use resources: (1) a self-evaluation form to detect gender biases and raise self-awareness for teachers of Limnology and Geosciences courses (the form is applicable to a wide range of courses and disciplines), (2) teaching nutshells highlighting key female limnologists (and their history) to help lecturers to acknowledge the role of women in Limnology in their courses, and (3) a complete teaching unit about the past and present situation of women in the field of Limnology. All these resources are freely available (https://www.genderlimno.org). Here, we will present this toolbox of resources and guide you on how to use them for your teaching needs. Moreover, we will share the preliminary results of the self-evaluation form to showcase how gender-fair Limnology lessons in high-education courses are. We welcome everybody to take it! https://www.genderlimno.org/gender-fair-lessons.html

How to cite: Poblador, S., Anton-Pardo, M., Bartrons, M., Benito, X., Bernal, S., Bohorquez Bedoya, E., Cañedo-Argüelles, M., Catalán, N., Fernandes, I., Freixa, A., Genua-Olmedo, A., León-Palmero, E., Lupon, A., Mendoza-Lera, C., Pastor, A., Rodríguez-Lozano, P., Zufiaurre, A., and Sánchez-Montoya, M. M.: Is my teaching gender-fair? A self-assessment questionnaire., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12182, https://doi.org/10.5194/egusphere-egu24-12182, 2024.

Many universities openly pledge commitments to improving diversity, with science, technology, engineering, and math (STEM) fields receiving significant attention. Despite these efforts, geoscience remains one of the least diverse fields in STEM. This recognition has prompted an increase in studies stressing the systemic lack of representation across the field and the barriers that exist for those within. However, much of this work has been limited by the use of demographic datasets that have been either passively collected or derived from government sources. Constraints include country-specific data collection policies, failures to collect field-specific data, and the absence of additional information necessary for intersectional analysis. Advancing diversity, equity, and inclusion (DEI) in our field requires meaningful datasets that clearly identify social inequalities. Limited, incomplete, or anecdotal data are too easily dismissed by those in power, stalling constructive efforts.

In Canada, demographic data is not regularly collected at academic institutions and is seldom field-specific. This absence of data undermines efforts to identify the current state of diversity in the field and prioritise initiatives for improvement. Collecting comprehensive demographic data is a crucial step in determining whether progress is evident. It can also help to highlight areas of concern, especially in fields lacking in diversity, such as geoscience. To address this absence of data, we disseminated a 22-question demographic survey to 35 academic geoscience departments across Canada in late 2022.

We received 482 eligible responses to the survey, accounting for approximately 20% of the research population. Overall, men make up a slight majority across all respondents (53%), and the percentage of individuals who identify as white (73%) is greater than the national average (67%). Additionally, results shows that research students (MSc and PhD) are a diverse group, while salaried positions (postdoc, research staff and faculty) lack diversity in a wide range of categories including, gender, race, LGBTQ+, Indigeneity, and disability. Moreover, tenured positions are overwhelmingly occupied by white men, with racial inequalities prominent in the data.

These data highlight several areas of concern in the academic career path. The transition from research student to salaried research remains a clear area of concern, while the tenure process appears to continually favour white able-bodied cisgender men. Moreover, the representation of Indigenous persons and those with self-identified disabilities remains very low. Solutions require institutional changes to recruitment, tenure applications, postdoctoral hiring, field work design, and mentoring practices. Importantly, they also require changes to how we collect and analyse demographic datasets in geoscience, as a continued reliance on data that is passively collected or obtained from government sources will continue to limit our abilities to identify areas of concern and create effective strategies.

How to cite: Jess, S., Heer, E., and Schoenbohm, L.: Active demographic data collection in geoscience: results, implications, and recommendations from a survey of Canadian academia  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12643, https://doi.org/10.5194/egusphere-egu24-12643, 2024.

EGU24-13028 | Orals | EOS3.1

Embedding EDI in Geoscience Publications – Examples from the AGU  

Matthew Giampoala, Mia Ricci, and Paige Wooden

The American Geophysical Union understands an expansive and inclusive geoscience community is key to furthering knowledge about the Earth and the universe and finding solutions to current societal challenges. Though the geosciences have historically been dominated by a few homogenous groups, the collaborative and global nature of our science impels us to change our systems to include historically marginalized voices. Supported by AGU’s 2018 Diversity and Inclusion Strategic Plan, in 2023, AGU Publications signed the Joint Commitment for Action on Inclusion and Diversity in PublishingSignatories agree to collect self-reported gender and race/ethnicity data, develop baselines, and set minimum standards for inclusion. We provide a demographic overview of our authors, reviewers, and editors over time, detail how we collect data while following privacy laws, and discuss how data informs our DEIA strategies. We provide reports to our journal editors who set baselines and develop journal goals. We launched various initiatives to increase diversity and equity and decrease bias in peer review processes, and used the data to assess outcomes of these initiatives. In addition, we present examples of policy and structural changes we have implemented to weave DEIA in the scientific publishing environment, including our equitable approach to Open Access, our Community Science Exchange, and the recently launched Inclusion in Global Research policy to improve equity and transparency in research collaborations.

How to cite: Giampoala, M., Ricci, M., and Wooden, P.: Embedding EDI in Geoscience Publications – Examples from the AGU , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13028, https://doi.org/10.5194/egusphere-egu24-13028, 2024.

EGU24-14684 | Posters on site | EOS3.1

Nakkihomma: attitudes towards and distributions of academic household work 

Katja Anniina Lauri, Xuefei Li, Paulina Dukat, Nahid Atashi, Laura Karppinen, Katrianne Lehtipalo, Anna Lintunen, Dmitri Moisseev, Janne Mukkala, Tuomo Nieminen, Rosa Rantanen, Timo Vesala, Ilona Ylivinkka, and Hanna Vehkamäki

The equality and work well-being group at the Institute for Atmospheric and Earth System Research (INAR) at the University of Helsinki conducted a survey about academic household work (AHW) tasks among the institute’s staff in autumn 2023. The main aim of the survey was to find out how different AHW tasks are divided among the staff members and how the staff members consider these tasks.

Before the actual survey, we asked the staff to list tasks they consider AHW (nakkihomma in Finnish; direct translation: Frankfurter task). A few examples of AHW tasks we got: sending calendar invitations for meetings, making coffee for others, helping to organize social events at the institute, emotional service work (being involved in discussion with colleagues or students about their personal affairs or problems). For the survey, we grouped the proposed tasks in three categories (number of tasks in parentheses): research-related tasks (3), society-related tasks (4) and community-related tasks (29). The last category was further divided into four subcategories: tasks related to meetings (7), social events (6) and facilities (9), and miscellaneous (7). We asked which tasks the staff members consider as AHW, and how frequently they are committed to each task.

We received a total of 91 answers to the survey. This corresponds to 33% of our staff, but according to the background information we collected, the different groups in terms of gender, career stage, language status (Finnish/non-Finnish speaker) and staff group (research/technical/administrative) were represented well.

The general attitude towards AHW was surprisingly positive: 57% of respondents had a positive attitude while 35% had a neutral attitude. Senior research staff members use a considerable amount of time participating in different committee meetings while early-career researchers do not so much; however, they do a great deal of practical duties related to meetings. Furthermore, we found out that a lot of emotional service work is being done. Interestingly, early career researchers do not consider this generally as AHW while senior researchers do. Male staff members contribute more to technical writing and guiding tasks while female staff use more of their time in emotional service work and general collective AHW tasks. Finnish speakers contribute more to writing and guiding tasks while non-Finnish speakers are more frequently committed in “catering” AHW like making coffee. Technical and administrative personnel generally contribute more to AHW than research staff.

We hope that the results of this survey will help us developing a more equitable and inclusive atmosphere in our institute by enabling us to pay more attention in distributing AHW tasks in a more equal and just manner.

How to cite: Lauri, K. A., Li, X., Dukat, P., Atashi, N., Karppinen, L., Lehtipalo, K., Lintunen, A., Moisseev, D., Mukkala, J., Nieminen, T., Rantanen, R., Vesala, T., Ylivinkka, I., and Vehkamäki, H.: Nakkihomma: attitudes towards and distributions of academic household work, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14684, https://doi.org/10.5194/egusphere-egu24-14684, 2024.

EGU24-16168 | Posters on site | EOS3.1

Inclusive excellence at the ERC: latest actions and results of sustained measures 

Claudia Jesus-Rydin, Luis Fariña-Busto, and Eystein Jansen

The European Research Council (ERC), Europe’s premiere funding agency for frontier research, views equality of opportunities as an essential priority and a vital mission to ensure fairness in the review process. The ERC monitors various demographic data yearly on every call and has taken actions to tackle imbalances and potential implicit and explicit biases.

The presentation focuses on ERC general historical data for the three individual funding schemes: Starting Grant, Consolidator Grant and Advanced Grant. Demographic geosciences data of proposals and grants, disaggregated by gender and country, is presented. After more than 14 years of existence and various specific actions to tackle societal imbalances, ERC data provides an insight of the impact of various actions.

In the first framework programme (FP7, 2007-2013), 25% of applicants were women. In the last years (Horizon 2020, 2014-2020), this percentage increased by 4%, with 29% of women applying for ERC grants. In the same periods of time, the share of women as grantees has also increased from 20% to 29%. In the last years, men and women enjoy equal success rates (data for non-binary applicants is also presented).

The most recent actions taken by the ERC to address gender and diversity (including disabilities and neo-colonialism) in its operations and processes are also presented.

The ERC knows that work to ensure inclusive excellence and equality of opportunities is never-ending. This presentation analyses the institutional efforts critically and discusses possible steps to consolidate the accomplished results.

How to cite: Jesus-Rydin, C., Fariña-Busto, L., and Jansen, E.: Inclusive excellence at the ERC: latest actions and results of sustained measures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16168, https://doi.org/10.5194/egusphere-egu24-16168, 2024.

EGU24-17197 | ECS | Orals | EOS3.1

Science Sisters: Interviews with diverse role models on career paths and academic life 

Marina Cano, Iris van Zelst, and Hinna Shivkumar

Science Sisters is a YouTube interview series and podcast hosted by Dr. Iris van Zelst. Lighthearted in tone, it explores different career paths, academic life, and science communication in the planetary and geosciences. The majority of the guests on the episodes are female and/or non-white to show a diverse range of role models in STEM and celebrate women in science. Together with the guest, Iris goes into the highs and lows of being a researcher and discusses issues in academia, such as the lack of permanent jobs in science and sexism. So far, two seasons of Science Sisters have been produced with topics including ethical fieldwork, switching careers, science communication, postdoc life, leadership, women in science, job applications, postdoc hopping, outreach, publishing, feeling incompetent, astronaut training, toxic academia, and how to build a research group.

Here, we present the project and some of the choicest nuggets of wisdom from the guests about academic life and careers. We also discuss the production phase of the series, highlighting for instance the considerations that go into selecting topics and guests, and the postproduction phase of editing and uploading the videos.

In addition, we present how we use Science Sisters as a way to start conversations in our own institutes. We organise a parallel seminar series where we watch the premieres of the episodes live on YouTube and afterwards have a discussion on the episode topic with the episode guest attending online. This has resulted in a greater understanding of each other and more cohesion within the institute. Early career scientists in particular say that Science Sisters is extremely useful to learn about life as a researcher and they enjoy the chatty, entertaining quality of the interviews.

How to cite: Cano, M., van Zelst, I., and Shivkumar, H.: Science Sisters: Interviews with diverse role models on career paths and academic life, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17197, https://doi.org/10.5194/egusphere-egu24-17197, 2024.

EGU24-18544 | ECS | Orals | EOS3.1

Time’s up, bottom-up! A successful bottom-up approach for diversity and inclusions at Utrecht University 

Manon Verberne, Jana R. Cox, Frances E. Dunn, Merel Postma, and Tina Venema

Young Women of Geoscience (YWOG) is a group of young professionals (PhDs, postdocs, assistant professors and supporting staff) at Utrecht University with the aim to inspire, connect and support women and historically underrepresented groups in the field of geosciences, by creating an equal and inclusive working environment. We do this by opening up conversations and creating a safe and positive space for discussion. Now in our seventh year, the committee has established itself as a constant and stable presence within the faculty with regular events and initiatives that can easily be organized from our reputable base.

Our regular events consist of meet-and-greet sessions with senior staff members, that are well-attended by a variety of colleagues, which result in inspiring conversations. Additionally, book give-aways combined with book discussions are a recurring event, where books on diversity, inclusions and climate change are used to open conversations. These events often engage individuals who may not have initially identified with the committee's target audience, but afterwards their interest was sparked. In recent years we also organized successful events due to requests from staff members. Parenting during COVID was a successful online event with a panel discussion consisting of colleagues sharing tips and struggles. Additionally, this year we organized an event on pronouns, reaching a wide audience, from PhDs to supporting staff, professors and the faculty dean. It was also this session, with informative presentations and lively discussion, that led to immediate action from higher level staff on practical matters concerning pronouns in the workplace.

Our experience highlights the importance of a bottom-up approach in instigating meaningful change. The pronouns event is a prime example of this, opening the eyes of many attendees and making people feel the urgency for action. The event stemmed from a need within the faculty. However, to be able to organize such an event there must be a platform to do so. We have the opportunity to organize many events helped by funding through an Equality, Diversity and Inclusion (EDI) scheme and an internal award won by the committee. We aim to continue with the regular events like the meet-and-greets and book shares, and hope to organize more events that are based on the needs in the faculty to open conversations. YWOG's experience demonstrates the efficacy of a bottom-up approach, emphasizing the importance of diverse perspectives in fostering substantial changes toward a more inclusive working environment. The committee looks forward to sharing its experiences, connecting with other faculties and universities, and inspiring collective efforts to promote diversity and inclusion within geosciences.

How to cite: Verberne, M., Cox, J. R., Dunn, F. E., Postma, M., and Venema, T.: Time’s up, bottom-up! A successful bottom-up approach for diversity and inclusions at Utrecht University, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18544, https://doi.org/10.5194/egusphere-egu24-18544, 2024.

EGU24-20027 | Orals | EOS3.1

Planning virtual and hybrid events: steps to improve inclusion and accessibility 

Aileen Doran, Victoria Dutch, Bridget Warren, Robert A. Watson, Kevin Murphy, Angus Aldis, Isabelle Cooper, Charlotte Cockram, Dyess Harp, Morgane Desmau, and Lydia Keppler

Over the last decade, the way we communicate and engage with one another has changed on a global scale. It is now easier than ever to network and collaborate with colleagues worldwide. But, the COVID-19 pandemic led to a rapid and unplanned move to virtual platforms, resulting in several accessibility challenges and the inadvertent exclusion of several people during online events. While virtual/hybrid events have strong potential to facilitate new opportunities and networks for everyone, they are also greatly positioned to increase the inclusion of groups traditionally excluded from purely in-person conferences. However, early and careful planning is needed to achieve this, with inclusion and accessibility considered from the start. Including a virtual element in a conference does not automatically equal inclusion or accessibility. Without effective planning, virtual and hybrid events will replicate many biases and exclusions inherent to in-person events.

This presentation will share lessons learned from previous events’ successes and failures, based on the combined experiences of several groups and individuals who have planned and run such events. This presentation is based on an EGU Sphere article, of the same title, that aims to provide guidance on planning online/hybrid events from an accessibility viewpoint based on the authors experiences. The goal of this presentation is to initiate discussion on event accessibility and inclusion and to help generate new ideas and knowledge from people outside of the authors network. Every event is unique and will require its own accessibility design, but early consideration is crucial to ensure everyone feels welcome and included. Our suggested accessibility considerations have been broken down into three stages of event planning: 1) Pre-event planning, 2) on the day/during the event, and 3) after the event.

Ensuring accessibility and inclusivity in designing and running virtual/hybrid events can help everyone engage more meaningfully, resulting in more impactful discussions including groups with limited access to in-person events. However, while this article is intended to act as a starting place for inclusion and accessibility in online and hybrid event planning, it is not a fully comprehensive guide. As more events are run, it is expected that new insights and experiences will be gained, helping to continually update standards.

How to cite: Doran, A., Dutch, V., Warren, B., Watson, R. A., Murphy, K., Aldis, A., Cooper, I., Cockram, C., Harp, D., Desmau, M., and Keppler, L.: Planning virtual and hybrid events: steps to improve inclusion and accessibility, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20027, https://doi.org/10.5194/egusphere-egu24-20027, 2024.

EGU24-20337 | Posters on site | EOS3.1

The stagnation of low percentage of female scientists in Japan and JpGU's initiatives 

Rie Hori and Chiaki Oguchi

The percentage of female scientists in Japan is 17.5% in the 2021 survey. This percentage is the lowest among OECD countries. The percentages of female doctoral students in science and engineering graduate programs nationwide are 21.0% and 19.2%, indicating a gap between the percentage of female prospective researchers and the percentage of women actually employed. It is pointed out that this is due to gender bias at the time of recruitment. On the other hand, the percentage of female members of JpGU remains around 20%, which is higher than the average in Japan, but still low compared to the percentage of female geoscientists in EGU and AGU. One of the reasons for the low number of female scientists in Japan is the low percentage of female students entering science and engineering fields in Japan (27% in science and 16% in engineering). The Science Council of Japan's Subcommittee on Gender and Diversity in Science and Engineering analyzed this problem and pointed out that its cause lies in the environment of education system during elementary and junior high schools (Opinion of SCJ, 2023). In Japan, the following factors are considered to have contributed to the decline in the number of female students going on to study science and engineering, even though surveys such as PISA (2018) and TIMSS (2019) show that both male and female 15-year-olds have equal academic achievement and interested in science and mathematics in the early education stage. (1) The percentage of female science teachers in junior high school and above is significantly lower than in the OECD countries → Few role models. (2) Often exposed to obvious “implicit bias” that has no evidence to support it (for example, girls are not good at mathematics. Science and engineering professions are not suitable for girls).

JpGU and Japanese universities actively conduct outreach programs for female junior igh and high school students every year to foster future female scientists. However, only a small percentage of them in whole Japan participate in such events, and these initiatives does not give us a full solution.

How to cite: Hori, R. and Oguchi, C.: The stagnation of low percentage of female scientists in Japan and JpGU's initiatives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20337, https://doi.org/10.5194/egusphere-egu24-20337, 2024.

EGU24-22185 | Posters on site | EOS3.1

Signatures of Equality, Diversity and Inclusivity at EGU General Assemblies 

Johanna Stadmark, Alberto Montanari, and Caroline Slomp

The EGU recognises the importance of equality, diversity, and inclusion as a crucial foundation for scientific research to address fundamental scientific questions and societally relevant environmental challenges. The increasing diversity of our membership in all its facets fosters collaborative research and discovery that benefits humanity and our planet.

Since its founding, the EGU has worked to ensure equitable treatment for everyone in the community with the goal of increasing diversity. In autumn 2018, the EGU Council established a working group whose aim is to promote and support equality, diversity, and inclusion (EDI) in the Earth, planetary, and space sciences, with a focus on EGU activities. Less than three years later, the EDI group was upgraded into a committee and has delivered numerous actions.

The most recent achievements of EDI@EGU are the Champion(s) for Equality, Diversity and Inclusion Award that is bestowed to recognize excellent contributions to put into exemplary practice the principles of EDI. Furthermore, the EDI Committee is currently working on a new travel support scheme to promote diversity at the EGU General assemblies.

The above actions resulted in a more diverse attendance at EGU General Assemblies along the years. The total number of presenters has increased over the time period 2015-2023, and this increase was observed throughout all career stages. The proportion of women presenters has increased from 2015 to 2023. A similar trend was observed for the convenors, an increase in total numbers over the years and a higher proportion of women in 2023 than in 2015.

In the hybrid meeting in 2023 both early career scientists and more senior scientists to a higher extent participated physically in the meeting than online. While there were no differences in how women and men participated (online or physically), there are differences connected to the country affiliations. More than half of participants from countries in most of western Europe attended in Vienna, while participants from North America and Asia attended online.

Since EGU General Assembly is the largest geosciences conference in Europe understanding the demographic evolution and their participation to EGU activities, including the GA, of various groups is an important tool for EGU governing body to draw targeted actions to ensure that the current procedures are fair and that all in the community are being and feeling included. We therefore aim to analyse the changes in demographics with regards to gender, career stage as well as to geographical distribution of the presenters and convenors also in coming years to better understand the potential impacts of meetings organized online or physically, or as a combination of both these modes.

How to cite: Stadmark, J., Montanari, A., and Slomp, C.: Signatures of Equality, Diversity and Inclusivity at EGU General Assemblies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22185, https://doi.org/10.5194/egusphere-egu24-22185, 2024.

SSS2 – Soil Erosion and Conservation

Land degradation is a primary form of global environmental deterioration. Soil erosion and land desertification are common land degradation processes in many regions. In this research, we take the Zhuoshui River basin in central Taiwan as the study area, and investigate the environmental sensitivity of different land use/land cover to land degradation subjected to historical and future climate scenarios. In order to understand the quality of land resources in the study area, we used the evaluating framework of the Mediterranean Desertification and Land Use (MEADALUS) model with revisions according to the localized mountainous characteristics in central Taiwan, and calculated the Environmentally Sensitive Areas Index (ESAI) of the study area. The ESAI is comprised of five indicators, which include climate, soil, vegetation, management, and landslide indicators. For the climate index, observed data from 2001 to 2020 of weather factors were used in the historical scenarios. On the other hand, data of weather factors generated by MIRCO5 GCM considering RCP2.6 and RCP8.5 scenarios in near-term and long-term time scales were used for the climate indicator in the future scenarios. The results depict the spatial variation of environmental sensitivity to land degradation in the Zhuoshui River basin using numerical values ranging from 1 to 2, where higher values correspond to more severe degradation. It is evident that the upper reaches of the Zhuoshui River exhibit lower degrees of land degradation due to dense vegetation, higher elevations, and limited human presence. In contrast, the downstream areas show a higher trend of land degradation, with the wet season exhibiting lower degradation trends compared to the dry season. Furthermore, there is a slight upward trend in land degradation since 2015, primarily attributed to climate indicators, as soil and vegetation indicators, as well as anthropogenic management indicators, show no significant changes. The land degradation index shows relatively subtle differences between future scenarios and historical scenarios, with land degradation index variations ranging from -13% to 22%. Negative values in the degradation index differences indicate an improvement in the degree of degradation, while positive differences denote an exacerbation of land degradation. According to the land use distribution in the Zhuoshui River basin, the land degradation trends for forests and national parks show relatively consistent variations between the dry and wet seasons. However, in the middle and lower reaches of the basin, apart from the RCP85 scenario for the long-term period, the other three scenarios exhibit higher differences in land degradation index changes for agricultural and urban areas compared to historical values. The research provides a reference for preventing continued land degradation and conserving terrestrial ecosystems and biodiversity in the study area.

How to cite: Wang, Y.-C. and Lu, Y.-H.: Evaluating the environmental sensitivity to land degradation: a case study in central Taiwan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8, https://doi.org/10.5194/egusphere-egu24-8, 2024.

EGU24-44 | ECS | Posters on site | SSS2.1

Application of Dempster-Schafer theory for predicting ephemeral gullies with remote sensing data 

Solmaz Fathololoumi, Hiteshkumar B. Vasava, Prasad Daggupati, and Asim Biswas

Mapping Ephemeral Gullies (EGs) is essential for enhancing the management and conservation of natural and agricultural resources. This study aimed to devise a novel approach utilizing the Dempster-Shafer (D-S) theory to achieve more accurate EGs mapping. To accomplish this, a high-resolution satellite image and ground data collected during a field visit to the Niagara region in Canada were utilized. Firstly, spectral features that effectively identify EGs were extracted from the satellite imagery. Subsequently, three machine learning classifiers including the artificial neural network (ANN), support vector machine (SVM), and random forest (RF) were employed to generate the EGs map. Finally, the D-S theory was applied to integrate the outcomes from these classifiers, aiming for a more precise EGs map. The results highlighted that the most significant variable importance was attributed to the Normalized Near-Infrared (NIR) (18%) and Soil line (15%). The average producer and user accuracies for the EGs and non-EGs classes across the three classifiers were 0.53 and 0.67, and 0.97 and 0.95, respectively. Incorporating the D-S theory enhanced these accuracy values by 0.15 and 0.19 for EGs and 0.02 and 0.02 for non-EGs. Furthermore, the overall accuracies for the EGs maps generated by the ANN, SVM, RF, and D-S theory models were 94%, 93%, 95%, and 97%, respectively. The results of this study showed that D-S theory is useful for improving the EGs mapping using remote sensing data.

How to cite: Fathololoumi, S., B. Vasava, H., Daggupati, P., and Biswas, A.: Application of Dempster-Schafer theory for predicting ephemeral gullies with remote sensing data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-44, https://doi.org/10.5194/egusphere-egu24-44, 2024.

EGU24-190 | ECS | Orals | SSS2.1

Effects of the Initial Soil Moisture Contents on Rill Erodibility and Critical Shear Stress of the Clay-rich Soils   

selen deviren saygin, Fikret Ari, Cagla Temiz, Sefika Arslan, Mehmet Altay Unal, and Gunay Erpul

Rill erosion is one of the most significant water erosion types in the agricultural areas as a complex type of concentrated flow erosion process. And, it is known that hydraulic conditions are closely related to rill development in terms of the initial soil moisture contents. However, the impact of the subsoil hydrology on sediment discharge potentials is somewhat entangled. Thus, many recent studies point out that the change in soil erosion depends on hydrological conditions in the subsoil and suggest that the evaluation of those changes would increase the success of soil erosion estimates to more efficiently manage natural resources. This study was aimed to investigate the effects of different soil moisture settings (referred as dry, saturated and drainage) on rill erodibility (Kr) and critical shear stress (τcr) values of the soils as the significant variables of process-based WEPP model, and the relations between basic soil properties (e.g. particle size distribution, aggregate stability, soil mechanical cohesion, organic matter etc.) and these model variables for the heavy textured 12 soil types (clay contents change between 33 and 52 %). Flume experiments were performed by using a V-shaped mini-flume apparatus, which was 0.046 m wide, 0.5 m long, and 0.12m deep, specifically designed for rill experiments. Two V-shaped channels with a length of 0.2 m were cemented to the flumes, one on each side. The soil samples were packed in boxes to attain natural bulk densities of the soils after passing through a 2 mm screen opening. The slope steepness was set to 3% for the slope bed and the flow rate was controlled with a flow meter from 0.10 L min-1 to 0.65 L min-1. Within the scope of the study, the mechanical soil cohesion values of the soils were determined by the fluidized bed approach. Obtained results clearly showed that the initial moisture contents had significant effects on sediment concentrations. The lowest Kr values were observed for the drainage condition in all soils while the highest Kr value was obtained for the soils with higher clay than silt content in the saturated conditions. Under dry conditions, on the contrary, the latter reversed and there was the highest Kr value for the soils having higher silt contents than clay. The inverse relationship between Kr and τcr was very pronounced and the highest τcr value was measured under drainage conditions. In addition, it was observed that there were significant correlations between rill erodibility (Kr) and silt contents and mechanical soil cohesion variables of the soils. Conclusively, rill erodibility potential of the soils observed under concentrated flow conditions had statistically close relationships with initial moisture conditions and primary physical soil properties (p<0.01). The research findings experimentally confirmed that variations in subsoil hydrology would play a crucial role in new generation studies of process-based modelling of the rill erosion.

Key words: Rill erodibility, critical shear stress, WEPP, initial soil moisture content

Acknowledgements: This work was supported by the Scientific and Technological Research Council of Turkey [TUBİTAK-3001, Project no: 118O111].

How to cite: deviren saygin, S., Ari, F., Temiz, C., Arslan, S., Unal, M. A., and Erpul, G.: Effects of the Initial Soil Moisture Contents on Rill Erodibility and Critical Shear Stress of the Clay-rich Soils  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-190, https://doi.org/10.5194/egusphere-egu24-190, 2024.

EGU24-890 | ECS | Posters on site | SSS2.1

 Soil Hydrophobicity Effects on Soil Erosion: Interplay between Hydrological and Mechanical Effects 

Mahboobeh Fallah, Marco Van De Wiel, and Ran Holtzman

 

Soil erosion poses a significant threat to agricultural and natural resources. Soil water repellency (SWR), namely the resistance to wetting due to hydrophobicity, has become widespread due to variety of processes including droughts, wildfires, pollution and greywater irrigation. Recent studies showed that that SWR exerts a strong effect on soil erosion by its hydrological impact: reduction in infiltration implies increase in overland flow, the driving force for erosion. Another, much less explored and more complex effect of SWR on erosion is through its impact on soil cohesion and strength, the resisting force for erosion. Here, we focus on the combined effects of SWR on erosion. We compile the published experimental data of erosion in hydrophobic soils, which provides contradictory evidence of both increase and decrease of erosion with increasing SWR. We find that while drought- and fire-induced SWR predominantly increases erosion, there is no clear trend for pollution-induced SWR, suggesting that pollution can improve the soil’s resistance to erosion, and that this mechanical effect of SWR is stronger than the hydrological effect of increased overland flow. We establish a rational connection between the SWR and its hydrological and mechanical effects on erosion through a simple 1D numerical model. The results of the model indicate that the net erosional impacts of SWR depends on the balance between the soil hydrological and soil mechanical effects of SWR. The key insights obtained from literature and this straightforward model enhanced our understanding of the dual nature of SWR's influence on soil erosion dynamics.

Keywords: Cohesion, Erodibility, Hydrophobicity, Hydrology, Runoff, Soil Erosion

How to cite: Fallah, M., Van De Wiel, M., and Holtzman, R.:  Soil Hydrophobicity Effects on Soil Erosion: Interplay between Hydrological and Mechanical Effects, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-890, https://doi.org/10.5194/egusphere-egu24-890, 2024.

As a result of intensive agricultural practices, cultivated soils of the European loess belt can experience high levels of degradation by erosive runoff. Given the sometimes severe and costly on- and off-site impacts, the agricultural community is urged to adopt alternative cropping techniques to mitigate runoff and erosion. Several cropping practices related to conservation agriculture are known for their ability to mitigate surface flows, but the magnitude of their effectiveness is associated with a wide variability due to environmental or management factors. The influence of these factors on the practices’ effectiveness is still poorly understood in quantitative terms. We therefore quantitatively reviewed the effectiveness of three common conservation farming practices at controlling runoff and soil loss. A systematic search was performed, focused on the plot scale and the Western European context, and meta-analyses were carried out on the 35 collated relevant studies involving 239 individual trials (plot-years). Two different approaches suitable for hierarchically structured datasets were used for the meta-analyses: hierarchical nonparametric bootstrapping and linear random effects models. Both methods yielded very similar outcomes, but the lack of primary data sometimes restricted the ability to account for all hierarchical levels of the dataset in the random effects models. We found that, on average, winter cover crops decrease cumulative seasonal (autumn-winter) runoff by 68% and soil erosion by 72% compared to a bare soil. The level of stubble tillage on the control plot, the number of successive years of cover cropping, and the maximum vegetation cover reached are three key variables explaining the mitigation effect of winter cover crops. In potato crops, tied-ridging (=(micro)basin tillage) cut cumulative seasonal (spring-summer) overland flow by a mean of 70% and soil loss by 92% compared to conventional furrows, but no moderators could be identified to explain the variability across studies or trials. Conservation (non-inversion) tillage techniques alleviate cumulative seasonal runoff by 27% and associated sediments losses by 66% on average, but a publication bias is strongly suspected for this meta-dataset. These mitigation effects are much greater for spring crops than for winter crops, and increase over time since ploughing stopped. The type of conservation tillage schemes also affects the capacity to attenuate surface flows. Intensive non-inversion tillage schemes based on multiple (powered) tillage operations turns out to be the least effective at reducing both water and soil losses. The best performing scheme against runoff appears to be a deep non-inversion tillage (-61%), while against erosion it would be a direct drilling system (-82%). Coarser-textured soils (sandy loam) also respond slightly better to conservation tillage than (clay-)loams. Although several factors could partly explain the effectiveness of two of the three conservation practices considered in this study, there remains a high (unexplained) variability between trial effect sizes, thus not attributable to sampling variability. Meanwhile, this review provides farm advisors or policy makers with guidance on the conditions in which such conservation practices are expected to achieve the greatest benefits.

How to cite: Clement, T., Bielders, C., and Degré, A.: Effectiveness of conservation tillage, tied-ridging, and winter cover crops at controlling runoff and soil loss in the Western European context: a meta-analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2129, https://doi.org/10.5194/egusphere-egu24-2129, 2024.

EGU24-3077 | ECS | Orals | SSS2.1

Spatial distribution of fallout 137Cs and 239+240Pu in Equatorial and Southern Hemisphere soils 

Gerald Dicen, Florianne Guillevic, Pierre-Alexis Chaboche, Katrin Meusburger, Pierre Sabatier, Olivier Evrard, and Christine Alewell

Past nuclear weapons testing and nuclear power plant accidents resulted in the ubiquitous deposition of radionuclides in the environment. While the risks associated with radionuclide contamination are apparent, these fallout radionuclides (FRNs) provide the privileged markers (“golden spikes”) of the Anthropocene stratigraphic layers. The onset of their emissions in the 1950s coincided with the “Great Acceleration”, which is characterized by large-scale shifts in the biophysical and socio-economic aspects of the Earth System, including an increase in soil degradation, triggered mainly by land-use change. Among the host of FRNs deposited globally, 137Cs has been the most commonly used and 239+240Pu is a new emerging tracer and chronological marker to assess soil erosion and/or chronology of sediment deposition.

In this meta-analysis, we compiled existing 137Cs and 239+240Pu data analyzed from undisturbed soils in the literature to get an overview of the spatial distribution and constraints of fallout 137Cs and 239+240Pu in Equatorial and Southern Hemisphere soils, as well as the possible sources of these FRNs through their isotopic ratios. A database composed of 1087 reference cores was built from the literature published on Equatorial and Southern hemisphere soils.

Aside from the cores collected from the north equatorial regions, high 137Cs inventories were also found in reference soils collected at the 40-50° S latitudinal band, which were mostly from South America. On the other hand, high 239+240Pu inventories were found at the 20-30° S latitudinal band, but this was influenced by the unusually high inventories measured from the French Polynesia, where many nuclear weapons testing occurred. The 240/239Pu atomic ratios indicated that sources other than the global fallout (240/239Pu = 0.18) contributed to the reference inventories in the Southern Hemisphere. As some areas lacked measurements, specific points where additional data could be obtained were identified through a GIS-based approach to represent the entire land surface areas of interest adequately. Together with new measurements, the compiled reference soil data will be used to construct a detailed baseline map of 137Cs and 239+240Pu fallout mainly for regional soil erosion assessments.

How to cite: Dicen, G., Guillevic, F., Chaboche, P.-A., Meusburger, K., Sabatier, P., Evrard, O., and Alewell, C.: Spatial distribution of fallout 137Cs and 239+240Pu in Equatorial and Southern Hemisphere soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3077, https://doi.org/10.5194/egusphere-egu24-3077, 2024.

EGU24-3799 | ECS | Orals | SSS2.1

Identification of thresholds to conduct efficient soils and water conservation strategies against erosion impacts: new insights from a modelling prospective in Normandy (France) 

Aurélien Maurié, Edouard Patault, Jérôme Ledun, Marielle Deman, and Matthieu Fournier

Erosion is recognized as a major threat worldwide and can be dramatically observed in Northwestern France as a consequence of water runoff. Recent regional studies in Normandy suggested that off-site erosion and runoff impacts led to significant economic costs over the last 25 years. Even if the regional planning strategy against erosion and runoff impacts could be seen as effective with a cost-benefice balance greater than 1, this strategy will no longer be as effective by 2050 due to climate change effects in the near future. To address this issue and conduct efficient land and water degradation neutrality strategies, local stakeholders now have to identify complementary strategies based on the deployments of nature-based solutions. However, there is a lack of references on the effectiveness of these complementary strategies.

In this study, we conducted a modelling exercise with the WaterSed model at the regional scale (12,318 km²) aiming to: (i) quantify the hydro-sedimentary transfers reaching the karstic systems throughout the 15,000 sinkholes distributed across the territory, (ii) established the first regional cartography of vulnerability of sinkholes to runoff and erosion, and (iii) to evaluate the effectiveness of strategies considering nature-based solutions to prevent land and ground water degradation.

The model was calibrated and validated using data of hydro-sedimentary transfer monitoring station on a local catchment. Multiples scenarios were explored (impacts of different nature-based solutions densities, localization of grasslands, ploughing of grass lands, soil and water conservation techniques, etc.) using semi-automatic positioning algorithm.

The WaterSed model provided specific outputs like volume of runoff (m3) and volume of sediments (t) reaching the karstic system for different designed storms. The mean runoff per sinkhole was estimated between 7,700 and 23,200 m3 and the mean volume of sediment reached between 0.8 and 4.7 t per sinkhole.

Our results suggest that increasing the density of nature-based solutions from 2 to 8 per km² can reduce from 0.5 to 1.3 % the runoff volume and from 5 to 15 % the sediment load reaching the sinkholes. Our results also suggest that a complement of 20 m to 250 m of grassland upstream a sinkhole can reduce the sediment load from 5 to 13 % and the runoff from 0.5 to 1.5 %. Our results suggest that the localization of ploughed-up grasslands can have a significant impact on the generation of hydro-sedimentary transfers (up to 10 % more sediment discharge).

The results of this modeling exercise provided: (i) the first regional cartography of vulnerability of the 15,000 sinkholes to runoff and erosion, and (ii) local thresholds and valuable references to build and conduct efficient land and ground water degradation neutrality strategies with stakeholders.

How to cite: Maurié, A., Patault, E., Ledun, J., Deman, M., and Fournier, M.: Identification of thresholds to conduct efficient soils and water conservation strategies against erosion impacts: new insights from a modelling prospective in Normandy (France), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3799, https://doi.org/10.5194/egusphere-egu24-3799, 2024.

The middle reaches of the Yellow River (MYR) cover a significant portion of the Loess Plateau, rendering it among the most heavily impacted regions by soil erosion globally. Consequently, the MYR are characterized by high-intensity soil and water conservation measures, such as terracing and silt check dams, which exert a profound impact on soil erosion and sediment transport in this region. However, there is currently no accurate and clear assessment of sediment interception and sediment reduction contributions for large-scale and complex cascading silt check dams. This study enhances the Revised Universal Soil Loss Equation (RUSLE) model by coupling the processes of soil erosion, slope sediment production, and channel sediment transport. The study evaluates the slope erosion and sediment production through the combination of RUSLE and the Sediment Connectivity Index (IC). Additionally, it calculates the sediment interception and sediment output in the channel based on silt check dams sediment interception efficiency. Accurate classification of complex cascading silt check dams is crucial for assessing their sediment reduction contributions. The research employs a flow-based method for precise dam classification and incorporates the latest terracing distribution data to accurately assess the sediment reduction contributions of high-intensity engineering measures in the MYR. The research findings indicate: (1) The average annual soil erosion rate in the MYR from 1981 to 2017 is 13.32±31.94 t ha-1 yr-1, with moderate to severe soil erosion covering 15.1% of the area. (2) Over the past 40 years, there has been an overall decreasing trend in soil erosion in the MYR, with a significant reduction covering 8.65% of the area. Significant decreases in soil erosion began to appear after 2000, with an average annual soil erosion rate reduction of 0.34 t ha-1 yr-1. (3) Based on the cascading situation of silt check dams, the 2187 large silt check dams in the MYR are classified into 6 categories. Taking the initial siltation year as an example, for basins controlled by silt check dams, the sediment output rate without silt check dams is 3.444 t ha-1 yr-1, while with silt check dams, the sediment output rate is 0.468 t ha-1 yr-1, achieving a sediment reduction contribution of 86.4%. The upcoming tasks include: (1) investigating the interannual fluctuations in sediment reduction attributed to silt dams and validating the model; (2) formulating diverse scenario assumptions to evaluate the sediment reduction contributions from engineering measures and vegetation restoration. This study seeks to precisely evaluate the impact of high-intensity soil and water conservation measures on mitigating soil erosion and sediment transport in the MYR, offering insights for regional soil and water conservation practices and sustainable management.

How to cite: Huang, Y., Gao, G., and Wang, Y.: Effect of high intensity soil and water conservation engineering measures on soil erosion and sediment transport, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4527, https://doi.org/10.5194/egusphere-egu24-4527, 2024.

The Western Ghats are in the final stage of weathering. Hence, the Laterite, clay, and Saprolite layers can vary to depths greater than 50 meters. Thus, the Western Ghats have unique hillslope hydrology, with more than three-quarters of rainfall entering the subsurface flow, thus developing well-networked sub-surface conduits. These sub-surface conduits help maintain slope stability of the Shayadris' (Western Ghats) laterites, which are usually exposed to high-intensity rainfall for longer durations during the monsoon season. The slope failures and floods in 2018, 2019 and 2020 are due to Catchment Fragmentation leading to a disturbed hydrological cycle in both surface and subsurface levels. 

A unique observation showed that most of the landslides (mostly toe failures) were concentrated near the Harangi reservoir and had a valley stream connecting to the reservoir. During field observations in these slope failure sites, soil pipe was observed in the crest of the landslide scarp for most of the accessible locations. The slope failures could be due to backflows in the soil pipes during heavy rainfall and mismanagement of dam gates. Observations from local residents who had witnessed the slope fail gave an idea of backflows in these slopes, which they locally termed as JALASPHOTA – The burst of groundwater up these soil slopes. During field observations post-monsoon, streams were visible at the surface of the scarp through these soil pipes after the landslide. 
GSD of Lateritic soils of Kodagu is Clay, sandy clay, sand-silt clay, clayey sand, sand-silt-clay and clayey sand. A slow-moving landslide was observed on the highway connecting to Mangalore, where more clay content was observed. 
Juvenile and fully developed soil pipes were observed at the landslide scarp, and slopes with fully mature soil pipes were observed to have more runout distance. 
A few case studies of how catchment Fragmentation has disturbed the sub-surface hydrology, leading to slope failure, are discussed in this study. 

How to cite: Manjunath, K.: Field Observations of Soil Piping and associated disasters in the Western Ghats region of Karnataka (Kodagu district) , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4633, https://doi.org/10.5194/egusphere-egu24-4633, 2024.

EGU24-4784 | ECS | Orals | SSS2.1

Quantifying above-ground biomass, SOC and erosion using a new detailed crop pattern map including double and triple cropping in the Yangtze River basin using the PESERA model 

Jichen Zhou, Jantiene Baartman, Yinan Ning, João Carvalho Nunes, Lihua Ma, and Xuejun Liu

Soil erosion represents a primary threat to soil systems with adverse implications for ecosystem services, crop production, potable water, and carbon storage. While numerous studies have quantified the spatial distribution of Above-Ground Biomass (AGB), soil erosion, and Soil Organic Carbon (SOC) in the Yangtze River Basin (YRB) in China, limited attention has been given to assessing the contributions of different land use types and especially crop types to AGB, soil erosion, and SOC. In most studies, cropland is taken as a land use class, while detailed crop types and rotation patterns, and their effect on soil erosion and SOC, vary significantly. In this study, we used the Metronamica model to generate a detailed crop rotation and distribution map across the YRB and subsequently employed the PESERA model to simulate the spatial distribution of AGB, soil erosion, and SOC on a monthly basis. PESERA model simulations indicate an average soil erosion rate across the entire YRB of 7.7 t/ha/yr, with erosion hotspots concentrated in the Sichuan Basin and the central-southern regions. The southwestern region and western Sichuan show elevated levels of AGB and SOC, while the eastern plains display lower levels. Erosion rates are lowest in areas designated as artificial land, pasture and grassland, whereas cropland and fruit trees experience the highest erosion rates. In terms of crop types, the highest erosion rates and lowest AGB are observed in fallow and potato cultivation, while the lowest erosion rates and highest AGB are found in rice-wheat rotation fields. To the best of our knowledge, this is the first study including detailed crop types and patterns into account while evaluating their effect on relatively large scale (i.e. YRB). These findings can help to develop sustainable soil management and (cropping) conservation strategies.

How to cite: Zhou, J., Baartman, J., Ning, Y., Carvalho Nunes, J., Ma, L., and Liu, X.: Quantifying above-ground biomass, SOC and erosion using a new detailed crop pattern map including double and triple cropping in the Yangtze River basin using the PESERA model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4784, https://doi.org/10.5194/egusphere-egu24-4784, 2024.

EGU24-6779 | Orals | SSS2.1

Predicting soil erosion under climate change: Using climate data to forecast future climate change scenarios and RUSLE2 modeling to estimate soil erosion on agricultural lands in the United States 

Mahsa Ghorbani, Racha El Kadiri, Henrique Momm, Daniel Yoder, Vieira Dalmo, Ronald Bingner, Robert Wells, Giulio Ferruzzi, and Christophe Darnault

Soil erosion is one of the major processes of land degradation. Climate change, marked by alterations in the precipitation spatial and temporal patterns as well as rainfall amounts projected to increase, is expected to exacerbate soil erosion and loss of soil in the agricultural landscape. Understanding soil loss using physically-based water erosion prediction models and improving knowledge of soil erosion of agricultural lands under future climate change scenarios is critical to developing best management practices for the conservation of soil resources as well as to inform decision and policy makers. This study aims at investigating the impacts of future climate changes on soil erosion in the United States. By integrating up-to-date climate datasets this study characterized differences and current trends in precipitation with respect to climate change and applied a climate model ensemble based on the CMIP6 climate scenarios to predict the future climate. These data are downscaled with machine learning algorithms. It also estimates soil erosion in different soil-climate-agricultural management systems from predicted precipitation under future climate change scenarios using the Revised Universal Soil Loss Equation, Version 2 (RUSLE2). Research findings on the impacts of future climate change scenarios on soil erosion in agricultural landscapes will allow the development of climate-driven best management practices and conservation agriculture techniques as well as inform decision and policy makers to reduce soil loss, therefore protecting the limited soil and water resources, and contributing to a sustainable agricultural production and food security.

How to cite: Ghorbani, M., El Kadiri, R., Momm, H., Yoder, D., Dalmo, V., Bingner, R., Wells, R., Ferruzzi, G., and Darnault, C.: Predicting soil erosion under climate change: Using climate data to forecast future climate change scenarios and RUSLE2 modeling to estimate soil erosion on agricultural lands in the United States, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6779, https://doi.org/10.5194/egusphere-egu24-6779, 2024.

EGU24-6852 | Orals | SSS2.1

Revised Universal Soil Loss Equation, Version 2 (RUSLE2) Development: Advanced science components and web-based user interface for use in conservation planning 

Christophe Darnault, Mahsa Ghorbani, Gizem Genc Kildirgici, Avinash Kethineedi, Bigyan Ghimire, Jon Calhoun, Henrique Momm, Daniel Yoder, Vieira Dalmo, Ronald Bingner, Robert Wells, and Giulio Ferruzzi

The Revised Universal Soil Loss Equation, Version 2 (RUSLE2) is the water erosion prediction tool for use by the USDA National Resources Conservation Service (NRCS) for all conservation planning in the United States. USDA NRCS utilizes the Integrated Erosion Tool (IET) that combines RUSLE2 with USDA data sets for soil, climate, and agricultural management. The Agricultural Research Service (ARS) is the USDA’s research agency charged with the development of the RUSLE2 model. RUSLE2 is an advanced computer model that estimates rill and interrill erosion by water, combining empirical and process-based science, for use on personal computers. This research aims at improving RUSLE2 science components, including the development of a web-based user interface for RUSLE2, for use by USDA NRCS. Advanced science components will be developed to quantify rainfall and land management effects on spatial and temporal variability of dynamic soil properties in agricultural watersheds in the United States, with emphasis on the assessment of soil erodibility and the risk of soil erosion under climate change. State-of-the-art technologies needed to measure, identify, and link dynamic soil erodibility to soil loss in the agricultural landscape, such as machine learning algorithms, remote sensing, and non-intrusive visualization and imaging technologies will provide advanced science components for RUSLE2. For the development of a web-based RUSLE2 modeling system, a new cloud based infrastructure is being deployed using the Amazon Web Services (AWS) platform, which will support online databases for climate, soil, and agricultural management data. A new database structure is being designed for RUSLE2, to support server based erosion calculations. AWS services will also provide web servers, spatial databases, geoprocessing capabilities, cooperative source code development and all compute and storage resources. These research findings and products will help understand how climate change and modern management practices impact soil erodibility dynamics. Improvements to RUSLE2 technology will lead to advances in determining soil loss across agricultural landscapes through improved physically based water erosion models. New web-based tools will provide best management practices for soil and water resources conservation under changing environments, contributing to sustainable agriculture and food security, while ensuring environmental health.

How to cite: Darnault, C., Ghorbani, M., Genc Kildirgici, G., Kethineedi, A., Ghimire, B., Calhoun, J., Momm, H., Yoder, D., Dalmo, V., Bingner, R., Wells, R., and Ferruzzi, G.: Revised Universal Soil Loss Equation, Version 2 (RUSLE2) Development: Advanced science components and web-based user interface for use in conservation planning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6852, https://doi.org/10.5194/egusphere-egu24-6852, 2024.

EGU24-9422 | Orals | SSS2.1

Assessing soil erosion in a small agricultural catchment in Austria using OSL-dating, modelling, 137Cs and field measurements: a critical comparison 

Ronald Pöppl, Chris Renschler, Bruno Abatti, Nadine Asimus, Sabine Kraushaar, Peter Strauss, and Markus Fuchs

Soil erosion causes severe on- and off-site effects, such as reductions in soil depth, eutrophication of water bodies, loss of organic matter, and clogging and smothering of riverine habitats. Attempts to assess water-induced soil erosion by water include modelling, measuring/monitoring, the use of tracers, and dating. All of these approaches have shown to have shortcomings (Parsons, 2019). The main objective of this research is to assess soil erosion in a small agricultural catchment (HOAL, Lower Austria) using modelling, OSL-dating, 137Cs and field measurements and to compare the gained results in the light of the shortcomings of each method. The study has been conducted in a small catchment (ca. 66 ha), located in the Northern foothills of the Eastern Alps in Austria (i.e. an area intensively agriculturally used since the Middle Ages). The catchment elevation ranges from 268 to 323 m a.s.l. and has a mean slope angle of 8 %. The lithology mainly consists of Tertiary marly to sandy deposits which are superimposed by Quaternary sediments (e.g. loess). The climate in this region is characterized as humid. The results of this study reveal significant – partly even dramatic - differences in soil erosion rates as derived from the different assessment methods. Details as well as a critical method comparison will be provided at the EGU General Assembly 2024.

References:
Parsons, A. J. (2019). How reliable are our methods for estimating soil erosion by water? Science of the Total Environment, 676, 215-221.

How to cite: Pöppl, R., Renschler, C., Abatti, B., Asimus, N., Kraushaar, S., Strauss, P., and Fuchs, M.: Assessing soil erosion in a small agricultural catchment in Austria using OSL-dating, modelling, 137Cs and field measurements: a critical comparison, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9422, https://doi.org/10.5194/egusphere-egu24-9422, 2024.

EGU24-9512 | ECS | Orals | SSS2.1

AI-driven insights into soil health and soil degradation in Europe in the face of climate and anthropogenic challenges 

Mehdi H. Afshar, Amirhossein Hassani, Milad Aminzadeh, Pasquale Borrelli, Panos Panagos, David A. Robinson, and Nima Shokri

A healthy soil supports life on Earth through maintaining ecosystems that provide food, feed and fibre whilst supporting Earth system functions such as waste recycling, climate, flood, and water regulation. The intensification of anthropogenic activities and climate challenges pose serious threats to soil health (Hassani et al., 2021), exacerbating the processes of soil degradation that are putting at risk soil management, biodiversity, and food security.

This study thus aims at enhancing our understanding of the state and changes of soils by combining machine learning methods with a comprehensive series of climate and environmental variables. We employ machine learning methods to analyze the relationships between soil health indicators and a wide range of climatic parameters, and chemical, physical, and biological soil attributes in Europe. Capitalizing on the LUCAS (Land Use/Cover Area frame statistical Survey) topsoil database (2009-2018) and digital soil mapping techniques, our preliminary results highlight the regions across Europe showing consistent decline in soil nutrients and carbon content, signaling potential risks of soil degradation. The proposed framework enables us to understand, document and respond to soil changes in ecosystems under different land management and climate scenarios. This contributes to devising necessary action plans for sustainable soil management and preservation.

This research is part of the project AI4SoilHealth (Accelerating collection and use of soil health information using AI technology to support the Soil Deal for Europe and EU Soil Observatory) funded Horizon Europe (Grant No. 101086179).

 

Reference

Hassani, A., Azapagic, A., Shokri, N. (2021). Global Predictions of Primary Soil Salinization Under Changing Climate in the 21st Century, Nat. Commun., 12, 6663. https://doi.org/10.1038/s41467-021-26907-3.

How to cite: H. Afshar, M., Hassani, A., Aminzadeh, M., Borrelli, P., Panagos, P., Robinson, D. A., and Shokri, N.: AI-driven insights into soil health and soil degradation in Europe in the face of climate and anthropogenic challenges, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9512, https://doi.org/10.5194/egusphere-egu24-9512, 2024.

EGU24-10802 | Orals | SSS2.1

Hydrosedimentary functioning of a lowland field with both surface and subsurface drainage. 

Arthur Gaillot, Olivier Cerdan, Sébastien Salvador-Blanes, Pierre Vanhooydonck, Thomas Grangeon, Marc Desmet, and Célestine Delbart

Erosion is one of the most important threats for soil. Over the long term, soil erosion can have serious on-site (e.g. decrease in agricultural yield) and off-site impacts in morphogenic zones but also important off-site (e.g. mudflow) impacts in plains. Much more efforts have been devoted to study erosion processes in morphogenic zones that have naturally higher erosion rates than plains. However, the intensification of agriculture during the latter part of the 20th century significantly altered landscapes and increased hydrosedimentary connectivity in agricultural plains. The off-site consequences are numerous: mudflows, increasement a river turbidity, siltation in rivers, transfers of pollutants associated with sediments, etc. Generally, in temperate climate, the main source of sediments is the surface runoff that occurs on fields during winter or spring but in lowland areas the subsurface drainage network is a supplementary pathway for runoff and sediments. The few studies that have quantified erosion over a complete hydrological year show subsurface drainage contribution to erosion is very variable. It is still difficult to propose a hierarchy and to quantify factors affecting soil erosion by subsurface drainage. In this study, suspended solids (SS) concentration and water flow of a lowland field have been measured during two consecutive years both at the outlets of surface and subsurface drainage networks. SS yield was 0.49 t ha-1 and 1.08 t ha-1 in 2019–2020 and 2020–2021, respectively. During 2019–2020 and 2020–2021, subsurface drainage contribution to the total runoff was 46% and 21%, respectively and its contribution to SS yield was 9% and 11%, respectively. High temporal resolution measurements of SS concentrations showed the suspended sediment concentration increased at the outlet of both surface and subsurface drains from the first to the second year. These variations and the increase of surface runoff rate suggest a shift in water and sediment connectivity at the field scale. Based on water tracing, water balance and analysis of rainfall characteristics, the main driver is likely cropping practices. This study confirms the majority of sediment exports occurs during a short period, cause by only few runoff event of winter and adds a new quantification of hydrosedimentary fluxes in a surface and subsurface drained field separating surface and subsurface drainage contribution. It also shows that in hydromorphic drained areas, despite the very slight slope, surface runoff can represent the major pathway for soil erosion. Adapted soil tillage practices must be developed to preserve the agricultural production capacity of the fields, maintaining water exports, while simultaneously reducing sediment exports.

How to cite: Gaillot, A., Cerdan, O., Salvador-Blanes, S., Vanhooydonck, P., Grangeon, T., Desmet, M., and Delbart, C.: Hydrosedimentary functioning of a lowland field with both surface and subsurface drainage., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10802, https://doi.org/10.5194/egusphere-egu24-10802, 2024.

EGU24-10943 | ECS | Posters on site | SSS2.1

Study about perception of soil compaction in grasslands: what can be learnt to foster sustainability and policy intervention? 

Manjana Puff, Glenda Garcia-Santos, and Andreas Bohner

The study of the sustainable strategies at regional level complies with the current European Green deal to monitor soil compaction. However, recent studies showed that the implementation of sustainable practices by farmers that are useful for an ecological transition can be slow down by development and technology transfer capacity and or an attitude of resistance of farmers themselves to innovations.

In the context of soil compaction in grasslands, we studied the influence of different management strategies (use of cattle and machinery) and the farmers’ perception of soil compaction. The studied bio-physical indicators in the top soil were organic carbon, plant indicators, bulk density, soil texture, plant indicators, infiltration capacity, water repellence, water content and electrical conductivity at the surface level of permanent grasslands in a total of 16 grasslands in the time period 2022-24 within Görtschitztal and Magdalensberg in south Austria (Carinthia).

First results showed correlation between the use of cattle and number of entries in the field with heavy machinery and the increase of the bulk density, though always within low levels of compaction and at the surface. We also found cases of mismatch perception of soil compaction, which may hinder sustainable practices in the future. The results of this study may serve to increase understanding about the theoretical factors influencing the farmer’s perception of soil compaction problems, providing a valuable addition to the available literature. In terms of policy implications, a clear picture of the factors underlying the dynamics of farmer’s perception can be useful in the future to better targeting policy measures tailored to encourage sustainable practices and innovations in the agricultural sector. We show possible directions affecting perceptions at farmer-based level.

How to cite: Puff, M., Garcia-Santos, G., and Bohner, A.: Study about perception of soil compaction in grasslands: what can be learnt to foster sustainability and policy intervention?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10943, https://doi.org/10.5194/egusphere-egu24-10943, 2024.

EGU24-12285 | Orals | SSS2.1

Comparison of soil erosion rates by wind and water in a semi-arid loess soil  

Itzhak Katra, Meni Ben-Hur, and Smadar Tanner

Soil erosion is a significant process in the loss of soil/land resources, degradation and desertification. Traditionally, wind and water erosions have been studied and modelled separately. A quantitative sediment flux measure from a specific soil due to both water and wind erosion is lacking. The study aimed to drive such erosion rates in a semi-arid loess soil that is subjected to both forces of erosion. Soil samples from top-and sub-layers of the soil were analyzed for physical and chemical properties, including characteristics of soil aggregation. We performed targeted laboratory experiments using a boundary layer wind-tunnel for wind erosion and rainfall simulator for water erosion. Rates of sediment flux that were calculated for the topsoil and the subsoil revealed an opposite trend between water and wind erosion. This indicates that soil erodibility strongly depends on the erosional force applied rather than a certain soil property. The study conducted in a semi-arid region and may serve as a case study under climate change scenarios, in which more (non-arid) regions will be subjected to increase soil erosion.    

How to cite: Katra, I., Ben-Hur, M., and Tanner, S.: Comparison of soil erosion rates by wind and water in a semi-arid loess soil , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12285, https://doi.org/10.5194/egusphere-egu24-12285, 2024.

EGU24-12401 * | ECS | Orals | SSS2.1 | Highlight

Towards a unifying approach of land degradation in Europe 

Remus Pravalie, Pasquale Borrelli, Panos Panagos, Mihai Niculiță, Georgeta Bandoc, Cristian Patriche, and Bogdan Roșca

The impact of land degradation on the environment is multidimensional and is fundamentally influenced by various land degradation processes, which usually interact spatially in a convergent manner. However, the spatial pattern of multiple converging (co-occurring) land degradation pathways remains largely unexplored in Europe. To address the synergistic (convergent) nature of land degradation, in this work we modelled and mapped the spatial pattern of twelve interacting processes in agricultural/arable environments of Europe. Therefore, using state-of-the-art and large-scale datasets that were modelled via appropriate GIS (Geographic Information System) techniques, we performed an unprecedented investigation on land multi-degradation in 40 European countries. Essentially, we found that up to 27%, 35% and 22% of pan-European agricultural/arable landscapes are synergistically affected by one, two and three land degradation processes, while 10–11% of continental agricultural/arable environments are cumulatively threatened by four and at least five co-occurring processes. Our multi-process framework can be a valuable scientific tool for complex modelling of land degradation, but also for applying various agricultural, climate or sustainable development policies at European level.

How to cite: Pravalie, R., Borrelli, P., Panagos, P., Niculiță, M., Bandoc, G., Patriche, C., and Roșca, B.: Towards a unifying approach of land degradation in Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12401, https://doi.org/10.5194/egusphere-egu24-12401, 2024.

EGU24-12976 | ECS | Posters on site | SSS2.1

A piping erosion susceptibility map of Europe 

Anita Bernatek-Jakiel, Matthias Vanmaercke, Jean Poesen, Anna Biernacka, Pasquale Borrelli, Anastasiia Derii, Joanna Hałys, Joseph Holden, Gergely Jakab, Michał Jakiel, Panos Panagos, Dawid Piątek, Taco H. Regensburg, Jan Rodzik, Estela Nadal-Romero, Mateusz Stolarczyk, Els Verachtert, Patryk Wacławczyk, and Wojciech Zgłobicki

Soil erosion represents a crucial environmental issue worldwide that threatens land, freshwater, and oceans. Subsurface erosion by soil piping occurs in almost all climatic zones of the world and in various soil types. Its occurrence changes the conditions for controlling measures to reduce soil degradation. However, it remains one of the most overlooked soil erosion processes, and its global and regional recognition is poorly documented. This project aims to construct a piping erosion susceptibility map of Europe in order to identify locations affected by this process, and where specific erosion control measures should be taken. Firstly, we compiled a database of soil piping-related features, i.e. pipe roof collapses (PCs) and pipe outlets in the European Union and the UK that consists of 6841 locations having piping-related features (6171 PCs and 670 outlets), among which the location of 88% features is known at a resolution of 25 m. Then, this database is used to model the susceptibility of soils to piping erosion at the European scale. We applied the logistic regression model using the scikit-learn library in Python. The following environmental factors are tested: topography (such as slope and height difference), pedology (content of silt, clay, sand, and coarse fragments), land use and land cover, and climate (such as effective precipitation). Our preliminary result clearly shows that it is feasible to accurately identify the European hotspots susceptible to piping erosion, based on a combination of land use, topographic and soil variables (AUC >0.75). The presented map is an important step towards incorporating subsurface soil erosion into regional and global soil erosion models.

 

This research is part of a project “Building excellence in research of human-environmental systems with geospatial and Earth observation technologies” funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 952327. The research has also been supported by a grant from the Faculty of Geography and Geology under the Strategic Programme Excellence Initiative at Jagiellonian University.

How to cite: Bernatek-Jakiel, A., Vanmaercke, M., Poesen, J., Biernacka, A., Borrelli, P., Derii, A., Hałys, J., Holden, J., Jakab, G., Jakiel, M., Panagos, P., Piątek, D., Regensburg, T. H., Rodzik, J., Nadal-Romero, E., Stolarczyk, M., Verachtert, E., Wacławczyk, P., and Zgłobicki, W.: A piping erosion susceptibility map of Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12976, https://doi.org/10.5194/egusphere-egu24-12976, 2024.

EGU24-13351 | Posters on site | SSS2.1

Novel use of portable gamma sensors to rapidly assess soil status and recovery in degraded East African agro-pastoral land 

Will Blake, Aloyce Amasi, Claire Kelly, Shaun Lewin, Francis Mkilema, Furaha Msale, Kelvin Mtei, Linus Munishi, Mona Nasseri, Patrick Ndakidemi, and Alex Taylor

Soil resources in East African agro-pastoral lands are being rapidly depleted by erosion, threatening food, water and livelihood security. Here we explore the utility of innovation in portable gamma sensors to rapidly assess soil health via proxy measurement of soil organic matter (SOM) providing visual information that enables local communities to take action to mitigate land degradation before it reaches a critical tipping point.

This study is grounded in the outcomes of an integrated, interdisciplinary approach to support co-design of land management policy tailored to the needs of specific communities and places. The work has shown that limitations to delivering socially acceptable and environmentally desirable solutions can be addressed by (1) closing fundamental gaps between the evidence bases of different disciplines and indigenous knowledge and (2) addressing, through participatory action, the implementation gap between science-based recommendations, policy makers and practitioners. Key adaptations implemented in the study region include new bylaws to enforce altered grazing regimes, grassland recovery and tree planting.

Against this context, we report a first trial of a portable gamma spectrometer to rapidly assess spatial variability in soil health using total and radionuclide-specific gamma emissions from naturally occurring radioisotopes as a proxy for soil organic matter. A Medusa MS-700 portable gamma spectrometer was deployed on foot across a landscape of known variability in soil health status encompassing a spectrum of impact from severely gullied soil/subsoil, heavily grazed surface soil, recovered grazed soil (ca 3 years exclusion of livestock) and conservation agriculture plots. In-situ field results showed a clear gradient in raw total gamma count rate with sample areas in each zone at 1200 ± 100, 980 ± 70, 814 ± 60 and 720 ± 60 counts per second across the above four areas respectively.  Correlations between radioisotope-specific gamma spectrometer data and organic matter (range 15 ± 2 to 30 ± 3 g kg-1 from degraded land to conservation agriculture) were evaluated to explore the dominant control on sensor response. Further comparisons are made to major and minor element geochemistry. Feedback from local Maasai community members who participated in the research further underpins the value of the sensor as a qualitative assessment tool e.g. using visual colour coding in the live data feed in the field. Quantitative comparison of sensor and laboratory data will permit development of protocols for airborne (drone) gamma spectrometry that offers community scale evaluation of grazing pressure on soil health to inform livestock future exclusion policy in common land prone to soil erosion.

How to cite: Blake, W., Amasi, A., Kelly, C., Lewin, S., Mkilema, F., Msale, F., Mtei, K., Munishi, L., Nasseri, M., Ndakidemi, P., and Taylor, A.: Novel use of portable gamma sensors to rapidly assess soil status and recovery in degraded East African agro-pastoral land, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13351, https://doi.org/10.5194/egusphere-egu24-13351, 2024.

EGU24-13949 | ECS | Orals | SSS2.1

A GIS-modeling strategy to locate vulnerable agricultural fields and prioritize conservation efforts across the Midwest United states. 

Eduardo Luquin, Brian Gelder, Daryl Herzmann, Emily Zimmerman, David James, Kelsey Karnish, and Richard Cruse

To appropriately place soil conservation measures, locating the most vulnerable areas prone to soil erosion is required. Available tools to locate vulnerable areas are tedious to use and time-consuming, and most water erosion estimations are based on empirical models with limited applicability. The present study takes advantage of two large-scale soil and water conservation tools available for the Midwest U.S.: the Daily Erosion Project (DEP) and the Agricultural Conservation Planning Framework (ACPF).

In this study, we will showcase a recently developed large scale modeling approach implemented in the Midwest U.S. that currently downscales DEP from Hydrologic Unit Code (HUC) 12 (~90 km2) average estimation of hillslope runoff and soil loss into a much finer resolution, a field and pixel scale. The DEP uses the Water Erosion Prediction Project (WEPP) and simulates hundreds of thousands of hillslopes across the Midwest, covering the wide range of factors including topography, climate, soils and land use and management.

This presentation will introduce the newly developed quantitative soil erosion assessment tool (named OFEtool - Overland Flow Element tool) that uses geographic information systems (GIS) and a physical-based model with real climate data (DEP). The OFEtool analyzes a watershed and groups areas with similar attributes, such as slope, soil type, land use, and management practices (information provided by the ACPF). Following watershed analysis, the tool uses DEP simulations to obtain average hillslope soil erosion or deposition rates for these grouped characteristics. Finally, it associates and assigns these rates to the respective areas within the watershed.

The current version of the tool is used by the ACPF to locate the most vulnerable fields across the watershed for conservation planning scenarios to prioritize interventions in fields and specific areas with the highest erosion rates. The applicability of the tool will be shown for the state of Iowa (approximately 145,746 square kilometers). Preliminary results corroborate spatial variability of soil erosion within watersheds and Major Land Resource Areas (MLRA). The presentation will also provide new insights into the main factors governing soil erosion in Iowa (climate, soils, topography, land use and management).

 

References

Gelder, B., Sklenar, T., James, D., Herzmann, D., Cruse, R., Gesch, K., & Laflen, J. (2018). The Daily Erosion Project – daily estimates of water runoff, soil detachment, and erosion. Earth Surface Processes and Landforms, 43(5), 1105–1117. https://doi.org/10.1002/esp.4286

Daily Erosion Project. (n.d.). Retrieved January 9, 2024, from https://www.dailyerosion.org/

Tomer, M. D., Porter, S. A., James, D. E., Boomer, K. M. B., Kostel, J. A., & McLellan, E. (2013). Combining precision conservation technologies into a flexible framework to facilitate agricultural watershed planning. Journal of Soil and Water Conservation, 68(5). https://doi.org/10.2489/jswc.68.5.113

Agricultural Conservation Planning Framework. (n.d.). Retrieved January 9, 2024, from https://acpf4watersheds.org/

How to cite: Luquin, E., Gelder, B., Herzmann, D., Zimmerman, E., James, D., Karnish, K., and Cruse, R.: A GIS-modeling strategy to locate vulnerable agricultural fields and prioritize conservation efforts across the Midwest United states., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13949, https://doi.org/10.5194/egusphere-egu24-13949, 2024.

EGU24-14123 | Posters on site | SSS2.1

Improved interrill erosion prediction by considering the impact of the near-surface  

Bin Wang, Yujie Wang, and Chenfeng Wang

The mechanism of the interrill erosion process is still unclear under complex conditions. Spatio-temporal variations of the near-surface hydraulic gradient are a common occurrence; however, few attempts have been made to characterize the near-surface hydraulic gradient for erosion prediction. Therefore, the objective of this study is to determine the influence of exogenic erosional forces (rainfall, overland flow, and seepage) on interrill erosion processes by considering the impact of the near-surface hydraulic gradient. Five near-surface hydraulic gradients (70% of field capacity, field capacity, saturated, artesian seepage at 20 cm and 40 cm of the hydrostatic pressure head) were applied in clay loam soil at two representative slope gradients of 8.75% and 17.63% under three rainfall intensities of 30, 60, and 90 mm h-1. The results showed that the near-surface hydraulic gradient was the dominant factor in the interrill erosion process in addition to rainfall intensity (I), runoff (Q), and slope gradient (S). There was a significant improvement in the prediction accuracy of the interrill erosion rate when the factor of near-surface hydraulic gradient was introduced into the interrill erosion prediction equation based on the Water Erosion Prediction Project (WEPP) concept. The R2 and NSE values were 22.36% to 210.00% higher than those of existing empirical equations (main parameters: I, I&S, I&Q, I&S&Q). The correlation matrix results indicated that the flow velocity was a key hydraulic parameter for predicting the interrill erosion rate. The interrill erosion rate was predicted well by a simple power function of the flow velocity, although this relationship lacks clear physical meaning. We also found that the interrill erosion rate increased as a power function with the runoff depth, rainfall intensity, hydrostatic pressure head and slope gradient. Considering the integrated effect of the exogenic erosional dynamics on the interrill erosion, a power function that included the physical description of the hydrodynamic parameters, rainfall intensity and hydrostatic pressure head was used to predict the interrill erosion rate. The results of this research provide new insights into developing process-based and mechanistic models for interrill erosion processes.

How to cite: Wang, B., Wang, Y., and Wang, C.: Improved interrill erosion prediction by considering the impact of the near-surface , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14123, https://doi.org/10.5194/egusphere-egu24-14123, 2024.

EGU24-14241 | Posters on site | SSS2.1

Impact of near-surface hydraulic gradient on the interrillerosion process 

Yujie Wang, Bin Wang, Chenfeng Wang, and Yunqi Wang

The impact of near-surface hydraulic gradients on interrill erosion is still obscure. The objective of this study is to distinguish the dominant interrill erosion process in areas impacted by near-surface hydraulic gradients. A series of rainfall simulations were conducted on a clay loam soil subjected to near-surface hydraulic gradients that shifted from drainage/saturation conditions to seepage conditions under three rainfall intensities (30, 60 and 90 mm hr−1) and two slope gradients (5 and 10). The results showed significant differences in soil loss between all the treatments. The sediment concentrations for seepage conditions were 0.57 to 7.02 times greater than those for drainage conditions. The correlation analysis indicated that the near-surface hydraulic gradient was a governing factor affecting interrill erosion. The critical flow rate was larger than 90 mm hr−1, suggesting that thin sheet flow does not have sufficient power to detach soil particles without raindrop impact. Furthermore, the detachment rates by raindrop impact were 1.12 to 4.60 times greater for seepage conditions than for drainage conditions. As the near-surface hydraulic gradient shifted from drainage conditions to seepage conditions, it transitioned from transport-limited to detachment-limited, and the contribution of interrill erosion to overall erosion increased from 20.19 to 75.30%. The critical point of dominant interrill erosion process transition existed between saturation (SA) and artesian seepage in 20 cm of hydrostatic pressure head (SP20). The results emphasize the importance of the near-surface hydraulic gradients’ impact on the interrill erosion process. Further investigations need to be verified in different soil types, steeper slopes and natural storms.

How to cite: Wang, Y., Wang, B., Wang, C., and Wang, Y.: Impact of near-surface hydraulic gradient on the interrillerosion process, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14241, https://doi.org/10.5194/egusphere-egu24-14241, 2024.

EGU24-15313 | ECS | Orals | SSS2.1

Parent material modulated effects of soil degradation on fertility and organic carbon of tropical cropland soils in Eastern Africa 

Laura Summerauer, Fernando Bamba, Bendicto Akoraebirungi, Ahurra Wobusobozi, Travis W. Drake, Clovis Kabaseke, Daniel Muhindo, Landry Cizungu Ntaboba, Leonardo Ramirez-Lopez, Johan Six, Daniel Wasner, and Sebastian Doetterl

Deforestation for cropland expansion in the sloping landscapes along the East African Rift system causes severe soil erosion and thus the loss of fertile, organic rich topsoil. However, the varying effect of land degradation in the region on soils developed from different parent material - which may influence soil fertility and carbon stabilization - are still largely unknown. To examine these factors, we compared soil organic carbon (SOC) and soil fertility indicators in undisturbed forest topsoils with cropland hillslope topsoils along a chronosequence after deforestation (2–7, 10–20, 20–40, > 60 years of cropping, land abandonment) on mafic (South Kivu, Democratic Republic of Congo) and felsic parent material (western Uganda). From previous studies, we expected higher soil fertility and SOC contents and therefore slower degradation on mafic soils due to the higher amounts of clay and pedogenic metal phases which stabilize SOM and thus further maintain soil fertility.
However, we found similar SOC contents on both parent materials and a consistent decrease with time after deforestation. SOC values were significantly lower in soils that were cleared more than 60 years ago, compared to cropland which was cleared 2–7 years ago and nearby undisturbed forest topsoils (0–10 cm soil depth). While the effective cation exchange capacity (ECEC) positively correlated with SOC in soils on felsic parent material, this was not observed in soils with mafic parent material, where it correlated with mineralogical proxies (total reserves in bases). In both regions, SOC did not correlate with clay content. Mid-Holocene carbonate volcanism appears to have offset soil degradation in the felsic region, contributing to higher pH and ECEC and impeding land abandonment due to the maintenance of acceptable soil fertility levels. Surprisingly, abandoned cropland sites in the mafic region still had an average SOC content of 14–29 g kg-1 in topsoils, likely due to strong fixation of SOC with reactive metal phases; however, they were characterized by extremely low pH values and high Al3+ mobility, combined with low available nutrient status.
Our results emphasize that soil fertility and carbon stabilization are reliant on the mineral composition of the underlying parent material, even in deeply weathered soils of the humid tropics. Soil organic matter in degraded tropical cropland soils does not appear to be a reliable indicator of soil fertility.

How to cite: Summerauer, L., Bamba, F., Akoraebirungi, B., Wobusobozi, A., Drake, T. W., Kabaseke, C., Muhindo, D., Cizungu Ntaboba, L., Ramirez-Lopez, L., Six, J., Wasner, D., and Doetterl, S.: Parent material modulated effects of soil degradation on fertility and organic carbon of tropical cropland soils in Eastern Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15313, https://doi.org/10.5194/egusphere-egu24-15313, 2024.

Olive tree plantations, an ancient and traditional crop in the Mediterranean region, have become erosion-prone due to their soil management and location. Many olive groves are often planted on slopes, where soil management often keeps the soil bare by conventional tillage and/or herbicide use. Further, the natural conditions of the region as long drought periods followed by intensive rainfall episodes, intensify the susceptibility to erosion. As a result of these factors, soil erosion has become a major threat to the sustainability of olive cultivation in southern Spain.

On-site soil erosion measurements through conventional methods usually do not exceed one decade and present several discrepancies among them and with modelling outcomes. Here, we aim to use fallout radionuclide (FRN) inventories (137Cs, 239+240Pu) together with 3D reconstruction of surface levels to estimate soil erosion rates at appropriate temporal and spatial scales for the last 55-60 years and/or from the beginning of tree plantation. Twelve soil cores up to 40 cm depth were taken across olive groves and in identified reference sites, and the model MODERN (Modelling Deposition and Erosion rates with RadioNuclides) (Arata et al., 2016) was used to estimate soil erosion rates from 1960. For the geomorphological reconstruction, manual measurements were taken to recreate the historical soil surface using the germination point in the olive trees as a reference point to the current soil surface. Both methods allowed us to estimate and understand past erosion processes and possible long-term trends.

The radiochemical analysis content of 137Cs, 239+240Pu inventories and its correlation with a geomorphological reconstruction on selected olive tree fields under different soil management in southern Spain will be presented.

 

Arata, L., Meusburger, K., Frenkel, E., A’Campo-Neuen, A., Iurian, A.-R., Ketterer, M. E., Mabit, L., & Alewell, C. (2016). Modelling Deposition and Erosion rates with RadioNuclides (MODERN) – Part 1: A new conversion model to derive soil redistribution rates from inventories of fallout radionuclides. Journal of Environmental Radioactivity, 162–163, 45–55. https://doi.org/10.1016/j.jenvrad.2016.05.008

How to cite: Moreno Romero, G., Alewell, C., and Borrelli, P.: Land degradation due to soil erosion in the Mediterranean olive groves: A comparison of 137Cs, 239+240Pu radionuclides and 3D reconstruction of surface levels, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16310, https://doi.org/10.5194/egusphere-egu24-16310, 2024.

EGU24-16461 | ECS | Orals | SSS2.1

Improving our understanding of sediment and dissolved solids export in Mediterranean croplands: comparative analysis of the response of watersheds with contrasting characteristics 

Mikel Percaz, Iñigo Barberena, Miguel A Campo-Bescós, Rafael Giménez, and Javier Casalí

Adequately assessing the export of sediments and dissolved solids at the outlet of representative watersheds provides extremely interesting information on the behavior of these watersheds, with important environmental and management implications. To this end, the Government of Navarre (Spain) began to implement in 1995 a network of five watersheds representative of different agricultural and forestry conditions in Navarre. La Tejería and Latxaga watersheds, occupy about 200 ha each in a humid sub-Mediterranean climate and are almost completely cultivated with winter grain. Oskotz Principal watershed comprises 1,688 ha under sub-Atlantic climate, most of it covered with forest (61%) whereas the remaining area is covered by pastures and arable land. Within the Oskotz watershed, a 434 ha sub-watershed almost fully covered with forest namely Oskotz Forested, is also monitored. Landazuria watershed covers an area of 480 ha being its climate dry Mediterranean. Over 88% of the watershed area is cultivated, with about 60% of the total cultivated area under pressurized irrigation systems. The rest of the cultivated surface is rainfed agriculture. Average anual suspended sediment concentration are 182 mg/L for La Tejería, and 38, 12, 12, and 30 (median) for Latxaga, Oskotz Principal, Oskotz Forested and Landazuria, respectively. Average anual exported sediment are 4.3 ± 3.7, 1.4 ± 1.7, 1.2 ± 0.9, 0.7 ± 0.6 and 0.3 ± 0.5 Mg/ha for the same watersheds. The average annual export of dissolved solids for the same watersheds is 1.1, 1.1, 2.2, 1.9 and 2.2 Mg/ha.

As for 2010, the 5,500 ha Cemborain river basin (583 mm of precipitation at its outlet) has been incorporated into the monitoring, with the intention of understanding the behavior of a much larger and more complex basin. The dominant land uses are forestry and scrubland (70% of the basin), while cultivated soils cover about 25% of the surface area. The data corresponding to this basin, still very preliminary, are presented for the first time and contextualized in this work. The mean suspended sediment concentrations in Cemboráin are 120 mg/l, with a great temporal variability, increased by suspiciously high values in summer, possibly due to the presence in the samples of various residues instead of sediments. The average sediment export at the outlet of the basin is 3 kg/ha/day in the winter months (January to March), which is 5.0 and 2.8 times lower than those found in La Tejería and Latxaga watersheds (the most similar in terms of climate and soils) for the same period. The average export of dissolved solids was 2.2 kg/ha/day, a figure 3.7 and 4.6 times lower than those found in La Tejería and Latxaga watersheds, respectively. Practically all exports in Cemborain have occurred between December and March. The low sediment export figures are consistent with what is to be expected given that the soil is much more protected than in the cereal basins.

How to cite: Percaz, M., Barberena, I., Campo-Bescós, M. A., Giménez, R., and Casalí, J.: Improving our understanding of sediment and dissolved solids export in Mediterranean croplands: comparative analysis of the response of watersheds with contrasting characteristics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16461, https://doi.org/10.5194/egusphere-egu24-16461, 2024.

EGU24-17090 | ECS | Posters on site | SSS2.1

Hillslope-channel coupling and geomorphic processes in a sub-humid badlands landscape: Evidence from 10 years of high-spatial resolution topography and hydrologic record 

Manel Llena, Jesús Revuelto, Álvaro Gómez-Gutiérrez, J. Ignacio López-Moreno, M. Paz Errea, Esteban Alonso-González, and Estela Nadal-Romero

Badlands landscapes are usually subjected to high erosion rates and soil degradation, representing the main source of fine sediments in some catchments, especially in Mediterranean regions. High erosion rates imply high sediment transfer downstream, with associated environmental and management implications. Coupling between hillslope and channel processes has been proved as a critical factor in the evolution of badlands landscapes. This work examines the hillslope-channel coupling and geomorphic processes in a sub-humid badlands landscape using a 10-year dataset of high-resolution topography in relation with hydro-meteorological drivers. Study catchment (0.45 km2) is located in the Central Southern Pyrenees. Topographic datasets were obtained through multi-temporal surveys (i.e., seasonally and annually) carried out by means of Terrestrial Laser Scanner (TLS) and Structure from Motion (SfM) photogrammetry. Hydrologic records were obtained from a gauging station located at the catchment outlet while rainfall was recorded in three tipping-bucket distributed along the study area. The study analyses the relationships between the hillslope erosion and the main-channel incision processes, and how they interact to shape the badlands landscape over time in relation with the hydro-meteorological registers. The study also highlights the importance of high-resolution topography in understanding erosion and the complex interactions between hillslope and channel processes, and the need for continued monitoring to better understand the long-term geomorphic and hydrological processes in these areas.


This work is supported by the MOUNTWATER (TED2021-131982B-I00) research project funded by the MICINN-Plan de Recuperación, Transformación y Resiliencia and the EU-NextGenerationEU.

How to cite: Llena, M., Revuelto, J., Gómez-Gutiérrez, Á., López-Moreno, J. I., Errea, M. P., Alonso-González, E., and Nadal-Romero, E.: Hillslope-channel coupling and geomorphic processes in a sub-humid badlands landscape: Evidence from 10 years of high-spatial resolution topography and hydrologic record, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17090, https://doi.org/10.5194/egusphere-egu24-17090, 2024.

EGU24-17115 | Orals | SSS2.1

Comparison of national and regional assessments of soil loss rate by water erosion: an application to the Tuscany region (Italy). 

Eduardo Medina-Roldán, Gabriele Buttafuoco, Lorenzo Gardin, Romina Lorenzetti, and Fabrizio Ungaro

Soil erosion, in its various forms, has been identified as one of the major soil threats worldwide because it is one of the most significant forms of land degradation (soil truncation, loss of fertility, slope instability, etc.) and loss of soil- based ecosystem services; causing irreversible effects on the poorly renewable soil resource. The Revised Universal Soil Loss Equation (RUSLE) is one of the most widespread adopted empirical model approaches for assessing long-term average soil loss rate by water erosion. The assessed soil loss rate is an indicator that describes (or measures) the state of the soil erosion in a specific area (field, catchment, region, country) which we are interested in. The quality of this indicator relies on the scale which it represents and its required data. Many European countries, such as Italy, do not have harmonised national soil erosion databases at the different scales required by decision makers (regional, provincial, local) and national scale assessments have been carried out using EU data (JRC 2015, LUCAS 2018). However, national scale assessments are not often coherent with the more detailed information available at regional scale for some Italian regions in which RUSLE based potential soil erosion maps have been produced. Although it would be predictable, it is of particular interest to assess how reliable a national scale assessment can be in providing information on the state of soil erosion at a regional scale. A regional soil database is available for the Tuscany region (IT) and it is suitable for soil erosion assessment at regional scale. In this context, within the framework of the EJP SOIL project SERENA, the study was aimed at comparing three RUSLE applications carried out i) at regional scale by means of the available regional soil/climate/digital terrain model data; ii) at national scale by means of the same datasets upscaled at country level; iii) at national scale based on datasets actually available for all the Italian territory.

This scale effect is likely due to 2 components. First, the spatial density and quality of the observations needed to estimate the RUSLE factors. To this regard, soil and climate data quality and availability are usually higher for small territories than for the whole national territory. Secondly, the reference scale adopted for the aggregation and spatialization of the data, which is particularly important for the LS factor. These two reasons lead to a lower reliability of the RUSLE applications at national scale as compared to a regional one. The assessment at the regional scale of the soil loss rate using the Tuscany Region dataset was used as reference to evaluate the results obtained with the other two datasets at the same regional scale. Such comparisons were made using both the differences among the erosion maps, and through statistical indices that measure the deviations between the reference map and the other spatial products.

How to cite: Medina-Roldán, E., Buttafuoco, G., Gardin, L., Lorenzetti, R., and Ungaro, F.: Comparison of national and regional assessments of soil loss rate by water erosion: an application to the Tuscany region (Italy)., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17115, https://doi.org/10.5194/egusphere-egu24-17115, 2024.

EGU24-18768 | ECS | Posters on site | SSS2.1

Bridging the Gap: A Multilevel Approach to Soil Health Assessment across Various Land Uses 

Niklas Schmücker, Peter Lehmann, Patrick Duddek, Norbert Kirchgessner, Andrea Carminati, and Madlene Nussbaum

To address the challenge of soil degradation among different land uses, development of precise indicators that accurately reflect the current state of soil health is crucial. Soil structural attributes, such as the volume of percolating pores and the connectivity of the pore network are inextricably linked to processes such as nutrient dynamics, carbon cycling, root penetration, biological activity, and rainfall partitioning. Hence, they play a significant role in determining the soil susceptibility to erosion and offer great potential as soil health indicators. These attributes are directly reflected in the hydraulic properties of the soil, particularly in its capacity for water infiltration and retention. Notably, high rates of infiltration and drainage are associated with the presence of well-connected macropores. However, these structural attributes typically have to be quantified using costly and time-consuming imaging methods, while obtaining accurate estimates in lab and field experiments has proven challenging. Our multilevel approach is designed to link directly measured structural attributes (macropore volume and connectivity) to standard field or lab measurements.

More specifically, macropore volume and connectivity were quantified using X-ray imaging across diverse land use types, including arable land, grassland, and forest. Structural characteristics were then correlated with key hydraulic properties, such as water retention and both saturated and unsaturated hydraulic conductivity, measured using the Hyprop system. We further compared the imaged and measured hydraulic properties with predictions from the European soil texture-based pedotransfer function EUPTF, to contrast texture- and structure-related soil hydraulic properties. As an additional exploratory angle, we related mid-infrared (MIR) spectral reflectance to our previously obtained hydraulic property data, to evaluate if MIR could serve as a less laborious alternative to traditional lab-based analyses. Finally, to develop applicable user-friendly and sensitive indicators, we correlated our findings with the classifications from in-situ Visual Evaluation of Soil Structure (VESS) and infiltration experiments.

Preliminary results of X-ray CT data and Hyprop measurements revealed significant differences in the volumetric fraction and drainage capacity of macropores as well as in the saturated hydraulic conductivity between arable land, grassland, and forest. Forest soil showed the largest drainage capacity of macropores, but also the largest variability between samples. Despite exhibiting similar pore size distributions, arable land samples showed, as a result of tillage, larger pore connectivity than grassland. Larger connectivity did, interestingly, not result in larger hydraulic conductivity of macropores. 

Our novel multilevel approach reveals clear distinction of land use regarding the complex interplay between soil structural continuity, soil texture, and hydraulic behavior. Such knowledge is crucial in formulating sensitive, quantifiable, and scalable indicators for soil health evaluation and management. These indicators are instrumental for creating more accurate models, for designing sensitive monitoring networks and ultimately advancing sustainable practices in agriculture, forestry, and environmental conservation.

How to cite: Schmücker, N., Lehmann, P., Duddek, P., Kirchgessner, N., Carminati, A., and Nussbaum, M.: Bridging the Gap: A Multilevel Approach to Soil Health Assessment across Various Land Uses, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18768, https://doi.org/10.5194/egusphere-egu24-18768, 2024.

The Government of Navarre (Spain) began to implement in 1995 a network of five watersheds representative of different agricultural and forestry conditions in Navarre. In this paper we focus on 4 of them. La Tejería and Latxaga watersheds occupy about 200 ha in a humid sub-Mediterranean climate and are almost completely cultivated with winter grain. Oskotz Principal watershed comprises 1,688 ha under sub-Atlantic climate, most of it covered with forest (61%) whereas the remaining area is covered by pastures and arable land. Within the Oskotz watershed, a 434 ha sub-watershed almost fully covered with forest namely Oskotz Forested, is also monitored.

Ten-minute data on flow (Q), water turbidity (T) and the most important meteorological variables are recorded in all the watersheds. Samples are collected daily to determine the concentration of suspended sediments (SSC) and various dissolved substances.  In addition, and since 2006, during particularly heavy rainfall-runoff events, another parallel sampling is activated to determine the sedimentogram in much greater detail. The number of samples taken depends on the Q and T variations detected.

For this study, events have been selected that meet the following requirements: i) there is a clear raising flow phase and a clear decreasing flow phase; ii) at least six samples have been collected and processed throughout the event for SSC determination; iii) the linear regression between Q and T yields a value of r2> 0.75. From this regression equation it is possible to obtain a very detailed sedimentogram (tenminute basis).

A total of 30 events meet the requirements, 7 in La Tejería, 9 in Latxaga, 5 in Oskotz Forestal and 9 in Oskotz Principal.  Hysteresis is observed in all of them. In the cereal watersheds, 75% of the hysteresis curves are of hourly character, that is, with the peak of the sedimentogram located in the rising part of the hydrograph. In these watersheds, the remaining 25% correspond to curves with a complex structure linked to the occurrence of several flow peaks in the same event, which will require further study. In the Oskotz Forestal watershed 3 of the curves are clockwise and two are "eight" shaped, while in Oskotz Forestal 8 of the nine curves are clockwise and one is "eight" shaped.

These preliminary results suggest that in the cereal watersheds the main sediment sources are in the proximity to the watershed outlet, probably in the same channels. In the Oskotz watersheds, the main sources are also mostly located in the vicinity of the outlet, although occasionally other sources far from the outlet are also activated, mainly in the forest watershed.

 

How to cite: Casali, J., Otazu, M., Barberena, I., Campo-Bescós, M. A., and Giménez, R.: Analysis of high-resolution flow vs. suspended sediment concentration curves to determine sediment sources in agricultural and forestry watersheds with contrasting characteristics , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18835, https://doi.org/10.5194/egusphere-egu24-18835, 2024.

EGU24-19354 | ECS | Orals | SSS2.1

Soil loss due to sugar beet harvesting is an underestimated but significant soil erosion process in mechanized agricultural systems. 

Philipp Saggau, Fritjof Busch, Joachim Brunotte, Rainer Duttmann, and Michael Kuhwald

Soil loss due to crop harvesting (SLCH) is a globally occurring, but underestimated process that contributes to soil degradation, adversely affecting soil functionality and fertility. In northern Europe, sugar beets play a crucial role for SLCH due to their high production rates, yet there is a lack of research in commercial mechanized farming of sugar beets. The aim of this study is to measure SLCH for sugar beets using typical commercial harvesters and identify relationships to crop and soil variables. Therefore, sugar beets and soil samples were collected for 14 sampling sites between 2018 and 2020 in Northern Germany.

The results show that SLCH is in average 0.064 kg per kg sugar beet (SLCHspec), which corresponds to a loss of 5.7 Mg ha-1 harvest-1 (SLCHcrop). These numbers are higher than former comparable studies and 83.9 % higher than SLCH estimates by sugar beet factories. In addition, we found that i) SLCH considerably varies among years, fields, but also within fields, ii) the most influential drivers for SLCH are soil water content and clay content, iii) soil properties impact SLCH differently in dependence to soil water content, iv) SLCH of sugar beets can lead to significant nutrient and soil organic carbon losses. Thus, the results underline that SLCH is an important and underestimated determinant of soil erosion processes, which urgently needs to be considered in models and estimates additionally to concurrent processes like water, wind and tillage erosion. This is important for the adaptation of soil conservation measures in order to reduce ongoing soil degradation, especially in highly mechanized agriculture.

How to cite: Saggau, P., Busch, F., Brunotte, J., Duttmann, R., and Kuhwald, M.: Soil loss due to sugar beet harvesting is an underestimated but significant soil erosion process in mechanized agricultural systems., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19354, https://doi.org/10.5194/egusphere-egu24-19354, 2024.

EGU24-20092 | ECS | Posters on site | SSS2.1

A novel soil erosion apparatus for high-velocity surface erosion and fissure-containing soil-structure interfaces 

Chenghao Chen, Wenbin Huang, and Shengshui Chen

Soil erosion is a natural geomorphological process, consisting of soil particle transport in the presence of water runoff. Despite its inherency, intensive human activity as well as acute climate change has led to an acceleration of soil erosion, and this becomes a major threat to environment and sustainability. In recent years, a rapid increase of rainfall frequency at the global scale enhances the production of surface runoff, thus yielding an active surface flow with higher velocity. Wetting-dry cycle induced by climate shifts also contributes to a vast distribution of fissure-containing surfaces, especially on soil-structure interfaces. Erosion triggered in this position can be detrimental, as the structure may lose its resilience against flood and earthquake, or even fails to maintain its gravitational stability. We herein introduce a novel laboratory-scale apparatus designed to investigate the surface erosion under high flow velocity, as well as the erosion of soil-structure interfaces featuring fissures. Our apparatus comprises three modules: a water circulation system, a testing chamber, and a set of data acquisition module. The testing chamber accommodates specimens measuring up to 24×80×80 mm with adjustable fissure widths. Monitoring module of particle removal and transport is emphasized in our study. With the reliable performance regarding repeatability tests using clayey soil, we found that the size of fissure significantly impacts the soil loss process, while its effect on the overall degree of erosion is minor. At different flow velocity intervals, similar successive steps, which involve alteration of single particle detachment and particle aggregate removal were witnessed at the soil surface. This was further validated by images captured by high speed camera and particle removal collection results. We believe that despite the simple framework of test apparatus, it is of great potential to further explore the surface erosion mechanism and the fissure development between soil-structure interfaces.

How to cite: Chen, C., Huang, W., and Chen, S.: A novel soil erosion apparatus for high-velocity surface erosion and fissure-containing soil-structure interfaces, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20092, https://doi.org/10.5194/egusphere-egu24-20092, 2024.

EGU24-20133 | ECS | Posters on site | SSS2.1

Study on the Regulatory Role of Vegetative Measures in the Development of Gravity Erosion 

Yunqi Wang, Bin Wang, and Yujie Wang

In natural environments, the occurrence of gravity erosion on slopes with vegetation is influenced by various external driving factors. Some are primarily controlled by the water field, such as rainfall infiltration, water level fluctuations, and freeze-thaw cycles, affecting the effective stress of the soil. Others are influenced by external loads transmitted to the soil through plants, affecting the original stress balance conditions, such as self-weight or wind force control. Additionally, extreme physical processes, such as wildfires and subsurface erosion, can degrade the soil strength and reduce the anti-sliding force. The investigations and experiments were conducted in the Chongqing section of the Three Gorges Reservoir Area in China. The triggering mechanisms and development patterns of gravity erosion on vegetated slopes under the influence of multiple factors were summarized from both field surveys and numerical models. Using remote sensing interpretation and numerical simulation, we estimated the potential volume of gravity erosion in the Chongqing section of the Three Gorges Reservoir Area in China. The research results indicate that the triggering factors for gravity erosion induced by rainfall and water level fluctuations are related to the soil entering the saturation process through the structural interface of the upper soil layer. This process leads to a reduction in matrix suction or the occurrence of positive pore water pressure. The essence of this phenomenon is the decrease in effective stress. The long-term instability of the surface soil layer in fire-affected areas is primarily due to the combined effects of root strength degradation and recovery, resulting in the deterioration of the overall shear strength of the soil. Wind disasters causing gravity erosion are attributed to local stress concentration and significant deformation induced by external loads, leading to traction and compression. Building upon the study of gravity erosion triggering mechanisms, the developmental process of gravity erosion was authentically reconstructed using aerial DEM and three-dimensional numerical models. The gravity erosion volume was estimated with a simulation accuracy of up to 92%. Additionally, the estimation of gravity erosion volume was extended to a regional scale, obtaining the potential gravity erosion volume in the Chongqing section of the Three Gorges Reservoir Area, with an estimated accuracy ranging from 35% to 60%. A protective solution utilizing vegetation measures is proposed to address gravity erosion induced by various external factors. For layered forested shallow slopes, consider permeable drainage through structural interfaces to address prolonged rainfall. For steep slopes with high wind exposure, consider the canopy-root plate type of afforestation species. In areas affected by fire disturbance, replanting and maintenance should be considered before the prone period of landslides. For riverbank slopes experiencing fluctuations in water levels, consider planting regenerative live stakes in the upper-middle part between the alert water level and the normal water level. Activate landslide disaster warnings when water levels drop rapidly.

How to cite: Wang, Y., Wang, B., and Wang, Y.: Study on the Regulatory Role of Vegetative Measures in the Development of Gravity Erosion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20133, https://doi.org/10.5194/egusphere-egu24-20133, 2024.

EGU24-21528 | Posters on site | SSS2.1

Mitigating muddy flooding in a changing climate. 

Neil Brannigan, Donal Mullan, Karel Vandaele, and Conor Graham

Soil erosion by water and muddy flooding significantly threaten agricultural productivity and broader environmental health. This issue is widespread in the European Loess Belt, especially in Flanders, Belgium. The off-site impacts of muddy flooding – notably on water quality, ecosystems, and infrastructure – are catastrophic. Encouragingly, existing mitigation strategies that combine curative measures and farming practices have effectively managed soil loss and sediment transport. However, climate change is expected to greatly exacerbate these impacts, likely rendering existing mitigation measures insufficient. Despite a well-recognised need for adaptation, there is a continued lack of research dedicated to designing effective mitigation strategies for arable catchments facing an increased frequency and magnitude of muddy flood events in future. Our study explores adapting these measures for improved resilience to climate change, with a focus on a heavily impacted catchment in Limburg, Belgium. A modelling approach was used to predict future muddy flooding scenarios from 2021 to 2100, employing a novel methodology to select and downscale appropriate climate models for site-specific, daily resolution future climate scenarios. Soil erosion projections were generated using the WEPP model for four hillslopes under each climate scenario, while Erosion3D illustrated spatial erosion patterns across the catchment. Various likely land use choices and potential mitigation strategies under future climatic conditions were evaluated, with strategies shortlisted based on efficacy and farmer practicability. Our findings indicate a considerable increase in erosion magnitude and muddy flooding duration between 2041-2100 under current land management practices, with a marked increase in high-magnitude events. Conservation tillage emerged as the most effective strategy for 2021-2040, followed by no tillage for 2061-2080. Mixing summer crops with winter wheat is highly effective until 2080, but banning summer crops in vulnerable fields is necessary for 2081-2100. These findings underscore the need for better data – especially long-term muddy flood measurements – and enhanced public education on these issues, thereby offering insights applicable to other affected regions.

How to cite: Brannigan, N., Mullan, D., Vandaele, K., and Graham, C.: Mitigating muddy flooding in a changing climate., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21528, https://doi.org/10.5194/egusphere-egu24-21528, 2024.

Soil erosion, a global challenge with profound consequences, impacts soil nutrient depletion, land degradation, agricultural productivity, runoff, and geological hazards. Our study assesses soil erosion and land use changes in the Beas Valley, Kullu, Himachal Pradesh, situated in the Western Himalayas. Employing diverse datasets and a comprehensive methodology, we scrutinize the intricate interactions of climate, soil, topography, and land use to comprehend and mitigate soil erosion risks. Data sources include rainfall data from the Climate Research Unit at the University of East Anglia, soil data from the Food and Agriculture Organization, Digital Elevation Model (DEM) data from the Shuttle Radar Topography Mission, and Landsat satellite imagery. We utilize the Revised Universal Soil Loss Equation (RUSLE) for soil erosion assessment, which includes factors like erosivity (R-factor), erodibility (K-factor), slope and flow accumulation (LS-factor), vegetation cover (C-factor), and conservation practices (P-factor).To bolster the credibility of our findings, we complement our methodology with field observations and interviews. These on-ground assessments and stakeholder insights provide practical context and verification for our research. This interdisciplinary approach yields crucial insights into soil erosion and land use changes in the Beas Valley, enriching our understanding of soil erosion in this fragile Himalayan ecosystem. Our findings offer vital support for informed land management decisions and conservation efforts.

 

Keywords: Soil erosion assessment, Himalayan, RUSLE, GIS and Remote Sensing

How to cite: Maurya, S., Singh, V., Chand, K., and Mishra, P.: Assessment of the spatial distribution of soil erosion using the RUSLE model and field survey study - A case study of Beas Valley, Kullu, India, Western Himalaya , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-135, https://doi.org/10.5194/egusphere-egu24-135, 2024.

Soil erosion causes worldwide land degradation. Long term monitoring of soil erosion is costly and labor intensive. Multiple models using Cs-137 fallout from atomic bomb tests are developed to retrospectively estimate average soil erosion since 1954. However, those models have not been rigorously validated due to the lack of compatible long-term measured soil loss data and thus their usefulness has been seriously challenged. Using 70 years of rare soil loss data measured in two small watersheds of <0.78 ha during 1954 and 2015, the author found that all theoretical models overestimate mean net soil erosion rates by at least 400%, and further confirmed that a key assumption of the homogeneous Cs-137 transfer from rainwater to soil during fallout is invalid and a critical process of the enhanced Cs-137 loss and redistribution during transfer is overlooked. The enhanced Cs-137 uptake by suspended sediment during transfer was responsible for about 8 times more enriched Cs-137 loss in sediment, to which Cs-137 inventory and erosion estimation are extremely sensitive. A new mass balance model is developed to include the dynamic uptake of Cs-137 by suspended sediment in surface runoff and losses of Cs-137 in both runoff solution and uptake by plants. The new model reduced overestimation of soil erosion to about 30%.  The finding of the enhanced radionuclide loss with suspended sediment during transfer is also valid to other fallout radionuclides such as Pb-210 and Be-7, which have been widely used in soil erosion estimation. Taking into account the enhanced radionuclides loss by suspended sediment during fallout will substantially lower soil loss estimation by all fallout radionuclides. 

How to cite: Zhang, X. C. J.: Evaluating and improving cesium-137 technology for estimating soil redistribution using soil loss data measured during 1954-2015, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4180, https://doi.org/10.5194/egusphere-egu24-4180, 2024.

EGU24-10794 | ECS | PICO | SSS2.2

Correlating different evaluation methods for SWC as support for soil processes modelling  

Agnese Innocenti, Veronica Pazzi, and Riccardo Fanti

Soil erosion modelling has a large sensitivity to soil water content as it greatly affects soil erodibility. Knowing soil moisture and water content along a soil profile can help to understand the soil ability to absorb water before runoff occurs, then, to predict runoff and potential erosion.

This study presents a combined approach of direct and indirect methods to monitor soil moisture content on a slope, with the goal of using this data in the future for modelling water erosion processes in soils.

Generally, soil moisture data used for erosion models can be acquired through direct methods (e.g., gravimetric method, time or frequency domain reflectometry, moisture sensors) and/or indirect methods (meteorological data, remote sensing, electrical conductivity).

In this research project, an experiment was carried out with the aim of combining direct and indirect methods to maximize the information on the rate of change of soil moisture in a 9*9 m plot by exploring depths from 0 to 50 cm. We used the water content sensor, SoilVUE10 by Campbell, recently released on the market, and based on Time Domain Reflectometry (TDR) technology conjointly with the Electrical Resistivity Tomography (ERT). Moisture sensors are known to create a disturbance in the ground, while geophysical techniques such as ERT are indirect, non-destructive measurements. Furthermore, they have the great advantage of being able to investigate a significantly larger area than classic humidity sensors.

The conductivity varied in average between 0.02 and 0.08 S/m with a little more evident relationship between the values measured with the two methods in deeper layers than at soil surface (i.e., r=0.31 at -30cm).

Overall, further investigations will be conducted, the ERT system needs data acquisition integration, i.e., remote data acquisition so that much more data can be acquired (at least one data set per day). The moisture values acquired by the SoilVUE10 probe require further analysis and comparison, possibly with other TDR probes. Furthermore, it may be necessary to install a surface moisture sensor capable to improve data acquisition even for the first 10cm soil layer.

How to cite: Innocenti, A., Pazzi, V., and Fanti, R.: Correlating different evaluation methods for SWC as support for soil processes modelling , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10794, https://doi.org/10.5194/egusphere-egu24-10794, 2024.

EGU24-11138 | ECS | PICO | SSS2.2

Experimental simulation of soil erosion in the context of climate change in NW France. 

Gabriel Portzer, Jean-Louis Grimaud, Albert Marchiol, Olivier Stab, Jean-Alain Fleurisson, Samuel Abiven, Simon Chollet, Yara Maalouf, Nicole Khoueiry, and Neda Yadari

This study focuses on the evolution of soil erosion rates on artificial covers for low level radioactive waste in the context of climate change. The objective is to test the impacts on erosion of (i) increasing rainfall intensities during storms and (ii) decreasing soil moisture content before storms. The “Centre de stockage de la Manche” (CSM) in Normandy, France, where Low-Level Nuclear waste are stored and monitored for the next centuries, is used as a reference case. There, climatic models anticipate an increase of temperature and seasonality (i.e., dryer Summers and wetter conditions from Fall to Spring) in the next centuries.

First, the soils of the CSM are sampled to be characterized. The densities, moisture, grainsize distribution and organic content of the soil are measured. We find that these values are rather homogeneous at the scale of the CSM. Second, a series of experimental rainfall simulations is performed on the CSM soils, focusing of rates and distribution of erosion processes. We simulate rainfall events of decennial, centennial, millennial and decamillennial intensities on 18° slopes, corresponding to the steeper banks of the CSM. Using the capacities of the climatic chambers at the Ecotron Lab in Nemours, France, we further test several soil moistures, i.e., very wet, moderately wet and dry, before simulating rainfall events. Finally, each experiment is repeated several times to assess the “memory” effect of topography on erosion. We quantify erosion by measuring sediment concentrations in run-off water collected at the outlet of the model and using topographic acquisitions performed using photogrammetry.

The experimental results are compared with estimations based on the Revised Universal Soil Loss Equation. Some propositions for upscaling, which could be used for assessing hypothetical future increase in soil loss in the CSM, are discussed.

How to cite: Portzer, G., Grimaud, J.-L., Marchiol, A., Stab, O., Fleurisson, J.-A., Abiven, S., Chollet, S., Maalouf, Y., Khoueiry, N., and Yadari, N.: Experimental simulation of soil erosion in the context of climate change in NW France., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11138, https://doi.org/10.5194/egusphere-egu24-11138, 2024.

EGU24-11387 | PICO | SSS2.2

Methodology for Spatially Distributed Rainfall Erosivity Calculations at the Conterminous United States to Support Soil Erosion Studies 

Henrique Momm, Robert Wells, Thomas Seever, Racha ElKadiri, and Ron Bingner

Research and action agencies in the US work collaboratively to develop and use soil erosion technology to support the development of field-specific conservation plans. These tools and accompanying databases are applied in all counties throughout the country covering a wide range of natural and anthropogenic physical conditions. Climate, particularly precipitation, constitutes one of the key drivers directly related to soil detachment and transport. Observations spanning over 30 years have demonstrated that estimated long-term average annual soil loss in agricultural fields is the result of the cumulative effect of many small and moderate-sized storms along with the impact of occasional severe ones. In the Revised Universal Soil Loss Equation version 2 (RUSLE2) technology, the effect of rainfall is represented by the rainfall runoff erosivity index R. This index is designed to serve as an estimation of the potential storm energy specific to each location. In this study, we propose and evaluate a methodology to generate continuous surfaces of monthly R for the continental US from discrete 15-min precipitation data. Over 2000 stations covering more than 50 years of 15-min precipitation data were used. Storm identification algorithms were implemented and evaluated through comparison with existing tools. Outlier events were identified and removed using a 50-year recurrent interval calculated for each station. Using 30-years of recorded data, a custom universal kriging algorithm was employed to generate a smooth continuous surface as a raster grid. This step included a boxcox transformation of the station data, directional variogram fitting, and the removing of external trends using elevation, long-term annual precipitation totals, and distance to the coast. Predicted surfaces were compared with existing RUSLE2 surfaces for the same time period with great level of agreement. The proposed methodology is intended to be comprehensive and reproductible such that it can serve as a template for future updates of erosivity maps for the entire continent at a county-scale. This methodology provides the means for future systematic updates to the RUSLE2 climate database to account for climatic changes and to support continued national efforts in reducing soil erosion and conserving natural resources. 

How to cite: Momm, H., Wells, R., Seever, T., ElKadiri, R., and Bingner, R.: Methodology for Spatially Distributed Rainfall Erosivity Calculations at the Conterminous United States to Support Soil Erosion Studies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11387, https://doi.org/10.5194/egusphere-egu24-11387, 2024.

EGU24-17727 | ECS | PICO | SSS2.2

QAnnAGNPS: a new plugin in QGIS to facilitate the use of AnnAGNPS 

Iñigo Barberena, Miguel A Campo-Bescós, and Javier Casalí

AnnAGNPS (ANNualized AGricultural NonPoint Source model) is a watershed-scale hydrologic model designed to analyze the impact of non-point pollutants in predominantly agricultural watersheds. It has capabilities that make it unique and indispensable on the world scene, such as an integrated simulation of all types of erosion and all major sources of non-point agricultural pollution. However, AnnAGNPS does not currently have a graphical user interface that allows the user to perform the simulation in a simple way. It is in this context that QAnnAGNPS has been created. QAnnAGNPS is a model developed in QGIS and written in Python 3 that fulfills two general functions. The first is to provide a simple to use graphical user interface to run AnnAGNPS. The second is to incorporate extra functionalities to the model, which are already included in similar hydrological models. The plugin has been used in the simulation of the Latxaga basin, a 207-hectare cereal basin located in Navarra (northern Spain). Its use has allowed to verify that QAnnAGNPS is able to perform the AnnAGNPS simulation and to visualize the results in a simpler way than the original one.

How to cite: Barberena, I., Campo-Bescós, M. A., and Casalí, J.: QAnnAGNPS: a new plugin in QGIS to facilitate the use of AnnAGNPS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17727, https://doi.org/10.5194/egusphere-egu24-17727, 2024.

Water erosion is a current issue, especially in hilly and areas, where driving force such as surface runoff and subsurface flow can mobilize large amounts of sediment to rivers. In fact, how and at which timescale, seasonality precipitation is turned into runoff or streamflow (Q) it is difficult to be predicted without calibrating site-specific models. The potential soil erosion can be assessed through the study of the relationships between sediment sources and sinks in a watershed (i.e., sediment connectivity assessment) and associated suspended sediment (SS) transport in rivers. On the other hand, sediment connectivity, defined as structural (from a geomorphological point of view) and functional connectivity (considering forcing processes), can be evaluated by the using of specific indexes (e.g., Index of connectivity – IC).  SS transport processes are intermittent processes fluctuating over a large range of temporal and spatial scales, making it challenging to develop predictive models applicable across timescales and rivers. While temporal variability in sediment transport is explained by the concept of “effective timescale of connectivity”; the mechanism behind this variability remains unknown. Here we used a data-driven approach considering two years of monitoring Q and SS to develop and demonstrate a proof of concept for automating the classification of event-based sediment dynamics by using a machine learning approach.  For each storm event we i) calculate the sediment connectivity (extreme rainfall events also are considered) and ii) define the link between sediment transport and deposition by considering SS transport as a fractal system (i.e. fractal storage time distributions in streams). Fractals are here used to describe and predict patterns over different temporal scales of dynamics in SS   The statistic and dynamics of Q, SSCs and associated grain size distribution, at event based, were considered by assessing their probability distribution function, Fourier power spectra, and the machine-learning classification of hysteresis index. Indeed, by approaching SS transport dynamics as a fractal system, it is assumed that patterns of variation in SS transport exist over different timescales, while linkages across those temporal scales are expressed as fractal power-laws. The study site, located near Florence in the Chianti area, is a 1 Km2 agricultural watershed with different types of land cover and characterize by a first-order mixed bedrock and alluvial stream channels. The area was mapped at high resolution with a Drone LIDAR scanner and equipped with a submersible laser diffraction particle size analyser (LISST) for long-term measuring suspended particle size and its volume concentration. Preliminary results showed a robust correlation between sediment connectivity, land cover, and sediment connectivity. Q-SS information flows exhibit seasonally varying behaviour consistent with dominant runoff generation mechanisms (catchment connectivity in wet to dry season). However, the timing and the magnitude of runoff also reflect considerable catchment heterogeneity, likely attributable to differences in baseflow contributions from different lithologies, and variation in of preferential flow paths (land use/land cover).  In conclusion, this study allowed to analyse a small catchment area in term of sediment connectivity and related sediment transport to identify potential areas of (dis)connectivity in the basin.

How to cite: Barbadori, F., Pelacani, S., and Raspini, F.: Investigating water erosion dynamics through connectivity based on fractal approaches: A case study in the Chianti area (Florence, Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18276, https://doi.org/10.5194/egusphere-egu24-18276, 2024.

EGU24-19497 | ECS | PICO | SSS2.2

SoilPulse – Towards FAIR soil process data! 

Jonas Lenz, Jan Devátý, and Conrad Jackisch

Soil processes are known to stretch over many scales – some processes, like erosion, are of particular interest due to their quick and complex characteristics with high impact. The analysis of soil erosion processes is challenging through heterogeneous field situations, involved spatio-temporal scales and by a reconfiguration of the system itself. Various experimental procedures and analytical methods were developed, which can analyze erosion processes. But because the procedures are driven by specific model assumptions which in effect also relate to a plethora of central state variables and parameters, the data of different groups are rarely compatible. Interoperability is hindered further through inhomogeneous data structures and a lack of metadata.

Within the NFDI4Earth pilot SoilPulse (soilpulse.github.io) we are developing an interactive metadata generator which shall assist researchers to make their soil process related data sets reusable by humans and machines. Instead of forcing the user to adhere to a defined metadata standard, the tool semi-automatically and interactively builds a translation procedure i) to map various existing data structures to a common scheme and ii) to feedback valuable but missing information to be provided by the researcher. While treating a dataset the researcher is aided by visualizations of the data in relation to other datasets which are already made machine readable through SoilPulse, allowing to easily discover non-plausible data and errors within the dataset. Once treated the dataset can be queried along with other datasets through a common interface and can be linked to erosion models through an API.

 

The PICO presentation demonstrates the functionality of the SoilPulse metadata generator prototype and invites attendees to apply it themselves on their data sets. As SoilPulse is in active development we highly appreciate comments, hints and impulses to further improve the tool!

How to cite: Lenz, J., Devátý, J., and Jackisch, C.: SoilPulse – Towards FAIR soil process data!, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19497, https://doi.org/10.5194/egusphere-egu24-19497, 2024.

EGU24-20845 | PICO | SSS2.2

An integrated GIS tool for gully erosion modelling  

Michael Maerker, Samuel Pelacani, Adel Omran, and Aleksey Sidorchuk

Gully erosion seriously affects the landscape and human life in different ways by destroying agricultural land and infrastructures, altering the hydraulic potential of soils, or affecting the water quality and quantity. Due to climate change, the negative effects of gully erosion are likely to increase in future, threatening especially low-income agricultural regions. In the past decades, quantitative methods have been proposed to simulate and predict gully erosion at different scales. However, gully erosion is still underrepresented in modern GIS-based modelling and simulation approaches. Therefore, we developed a tool to assess gully erosion dynamics. This tool comprises the data preparation, modelling and output analysis of the modelling phase as well as the visualization of the results. The modelling procedure is based on Sidorchuk’s gully simulation model. The tool was developed using phyton and the QGIS environment.

 

How to cite: Maerker, M., Pelacani, S., Omran, A., and Sidorchuk, A.: An integrated GIS tool for gully erosion modelling , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20845, https://doi.org/10.5194/egusphere-egu24-20845, 2024.

EGU24-21549 | PICO | SSS2.2

Comparing radar-raingauge precipitation-merging-methods for soil erosion modelling support 

Sandro Moretti, Rossano Ciampalini, Andrea Antonini, Alessandro Mazza, Samantha Melani, Alberto Ortolani, Ascanio Rosi, and Samuele Segoni

Radar-based rainfalls are currently used for process monitoring from remote in a large panel of domaines including hydrology and soil erosion modelling. Nevertheless, such data may include systemic and natural perturbations that need to be corrected before using these data. To encompass this problem, adjustments based on raingauge observations are frequently adopted. Here, we analysed the performance of different radar-raingauge merging procedures using a regional raingauge-radar network (Tuscany, Italy) focusing on a selected number of rainfalls events.

The computational methods adopted were: 1) Kriging with External Drift (KED) interpolation (Wackernagel 1998), 2) Probability-Matching-Method (PMM, Rosenfeld et al., 1994), and 3) an Adjusted kriging mixed method exploiting the conditional merging (ADj) process (Sinclair-Pegram, 2005). The latter made available by DPCN (Italian National Civil Protection Department), while methods 1) and 2) were applied on recorded raingauge rainfalls over the regional territory at 15’ time-step, and CAPPI (Constant Altitude Plan Position Indicator) reflectivity data from the Italian radar network at 2000/3000/5000 m at 5’ and 10’.

The comparisons between the three rainfall fields were based on the analyses of variance, Cumulative Distribution Function (CDF), and explicative coefficients such as BIAS, RMSE (Root Mean Square Error), MAD (Median Absolute Deviation). In average, rainfalls showed a moderate variability between the methods. Comparing CDFs, slight differences were detected between KED and ADj with bias mostly pronounced in lower quantiles, while more marked differences are observed in higher quantiles for the ADj-PMM methods. The analyses presented different spatial patterns depending on the applied procedure, closer to the radar data when using ADj, and more reflecting the gauge’s data structure when adopting KED. The probabilistic method (PMM) had the advantage to account for gauge data while preserving the spatial radar patterns, thus confirming interesting perspectives. Globally, the KED method provided more accurate coverage in the calculation by better compensating for local topographical shadows in the data, while ADJ confirmed the more detailed product in terms of time resolution (e.g. 5minute res.).

How to cite: Moretti, S., Ciampalini, R., Antonini, A., Mazza, A., Melani, S., Ortolani, A., Rosi, A., and Segoni, S.: Comparing radar-raingauge precipitation-merging-methods for soil erosion modelling support, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21549, https://doi.org/10.5194/egusphere-egu24-21549, 2024.

EGU24-3323 | ECS | Posters on site | SSS2.3

Innovations in Hydrological Modeling: A Standalone Approach to GAML Equation Enhancement for Runoff and Sediment Yield Estimation Using WEPP model 

Vijayalakshmi Suliammal Ponnambalam and Nagesh Kumar Dasika

Accurate estimation of infiltration rates is crucial for hydrological modeling, impacting predictions of runoff, sediment transport, and related phenomena. Various infiltration models, categorized as empirical, semi-empirical, and physically based, have been developed to compute cumulative infiltration and infiltration rates for these purposes. Because of its simplicity and accuracy, the Green–Ampt (GA) infiltration equation has been widely used for simulating 1-D (vertical) infiltration into the soil. The modification of GA equation by Mein and Larson for steady rainfall conditions (GAML,1973., etc.,) is widely employed in different hydrological modeling software such as ANSWERS (Areal Nonpoint Source Watershed Environment Response Simulation), CREAMS (Chemicals, Runoff, and Erosion from Agricultural Management Systems), and WEPP (Water Erosion Prediction Project), suggests the versatility of the model approach. However, its assumption of a sharp wetting front and uniform soil moisture content tends to overestimate low-flow runoff events. The present study proposes a simple, standalone methodology to refine the GAML equation employed for infiltration calculations in the WEPP model. The advantage of the WEPP model is that it can simulate runoff and soil loss events on an hourly, daily, monthly, annual, and event scale; Spatial and temporal distribution of soil loss and deposition can be estimated, and hillslope to watershed scale studies can be performed. Refinement entails estimating hydraulic conductivity (K) and soil moisture (ϴ) distribution in vertical and horizontal (2D) soil matrices before and after ponding scenarios as a linear equation of infiltration. A new algorithm was developed based on the refined GAML (R-GAML) parameters to estimate revised ponding time and infiltration rates based on experimental results, enhancing the accuracy of runoff predictions. Laboratory experiments on sand, clay, and sandy clay soils are utilized to estimate the soil infiltration parameters. The WEPP model was then employed to simulate runoff for a small agricultural watershed with the outlet at T. Narasipura station (of Cauvery River, India). The R-GAML and conventional GAML equations were used for runoff simulation and validated with the observed runoff data. The overestimation of low-flow runoff events using the conventional GAML was substantially reduced by the newly developed method, and the performance of R-GAML versus GAML was evaluated using correlation coefficient (0.937, 0.905), RMSE (16.471, 35.905), and NSE (0.968, 0.915) performance matrices for the Indian context.  Furthermore, this research aims to extend i) runoff and sediment yield (SY) simulation using the R-GAML equation from the field scale to the river basin scale (upscaling), ii) study the impact of Land Use and Land Cover (LULC) change on runoff and SY production by multi-site and multi-temporal calibration approach using the WEPP model. The findings offer valuable insights for urban planners in designing drainage networks, for agricultural water management in scheduling reservoir water release, and for deriving Best Management Practices (BMPs) in the Cauvery basin, which faces transboundary challenges due to rising water demand.

How to cite: Suliammal Ponnambalam, V. and Dasika, N. K.: Innovations in Hydrological Modeling: A Standalone Approach to GAML Equation Enhancement for Runoff and Sediment Yield Estimation Using WEPP model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3323, https://doi.org/10.5194/egusphere-egu24-3323, 2024.

EGU24-6562 | ECS | Posters virtual | SSS2.3

Development of observation model for predicting the phenomena of Rill and Gully erosion using Machine learning 

Harsha Vardhan Kaparthi and Alfonso Vitti

I am a doctoral candidate in University of Trento (first year) in Earth Observation at the Department of Civil, Environmental and Mechanical Engineering. My administrative University is Sapienza University of Rome and I am writing to express my interest in presenting my research in developing the strategies to predict Rill and Gully erosion in EGU general assembly 2024.

Soil moisture plays a major role in assisting crop productivity and weather forecasting to satisfy the ever-growing demands for land resources.

Soil erosion mechanics involve fluid (water/wind) detachment or entrainment followed by transport of soil particles and subsequent deposition as soil sediment. Soil movement by water often starts when a raindrop impacts the soil surface and initiates splash erosion, i.e., raindrops break aggregates into finer soil particles, displacing those particles and aggregates to create depressions in the soil surface. It depends on rainfall intensity, soil erodibility, and field slope among other factors. 

Various factors affecting soil erosion, including soil slope and length or supporting control practices like contour rows, strip cropping, and terrace systems, were recognized as independent factors influencing soil erosion by their inclusion in regional soil-loss equations. Water Erosion Prediction Project has been used to predict soil loss in a range of environments such as rangeland and forest for simulating runoff and sediment yield from the untreated watershed with good accuracy using continuity equation :

(dG/dx)  =  Dr + Di 

G = sediment load (kg·s-1· m-1)

x = distance down slope (m)

D= rill erosion rate (+for detachment, - for deposition)

D= interrill sediment delivery (kg·s−1·m−2).

Water Erosion Prediction Project relates sediment load in the runoff to the distance downslope as a function of the interrill and rill erosion rates calculated on a daily time step. Interrill erosion is the process of sediment delivery to more concentrated flow in rills, but rill erosion depends on the potential detachment capacity as limited by the sediment transport capacity of runoff in the rill. Soil loss through interrill and rill erosion is associated with the factor known as Revised Universal Soil Loss Equation (RUSLE), formulated as :

A  = R∗K∗Ls∗C∗P

A is the annual soil loss due to erosion [t/ha year];

R the rainfall erosivity factor;

K the soil erodibility factor;

LS the topographic factor derived from slope length and slope gradient;

C the cover and management factor; and

P the erosion control practice factor.

The limitations of RUSLE are that it only accounts for soil loss through sheet and rill erosion and ignores the effects of gully erosion. 

The objective is to generate gully erosion susceptibility maps (GESMs) by applying three machine learning algorithms to identify the area of the basin with respect to total area, which prones to have higher or lower susceptiblity to gully erosion.

These erosions require Persistent Monitoring with the combination of three main elements. High resolution, Revisit rate and global coverage. The models can be developed using GIS or R software and from SAR technologies.

Considering my academic performance so far, I hope to have this opportunity to present in EGU assembly, as I am confident that I will be able to meet your expectations.

Thanking you.

How to cite: Kaparthi, H. V. and Vitti, A.: Development of observation model for predicting the phenomena of Rill and Gully erosion using Machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6562, https://doi.org/10.5194/egusphere-egu24-6562, 2024.

EGU24-6677 | Posters on site | SSS2.3

Enhanced Ephemeral Gully Erosion Science within AnnAGNPS  

Ronald Bingner, Robert Wells, Henrique Momm, and Martin Locke

Concentrated runoff increases erosion and moves fine sediment and associated agrichemicals from upland areas to stream channels. Ephemeral gully erosion on croplands in the U.S. may contribute more of the sediment delivered to the edge of the field then from sheet and rill erosion. Typically, conservation practices developed for sheet and rill erosion are also expected to treat ephemeral gully erosion, but science and technology are needed to account for the separate benefits and effects of practices on each of the various sediment sources.

Watershed modeling technology has been widely developed to aid in evaluating conservation practices implemented as part of a management plan, but typically lacks the capability to identify how a source, such as sheet and rill erosion, ephemeral gully erosion, or channel erosion, is specifically controlled by a practice or integrated practices. The U.S. Department of Agriculture’s Annualized Agricultural Non-Point Source pollutant loading model, AnnAGNPS, has been developed to determine the effects of conservation management plans on erosion and provide sediment tracking from all sources within the watershed, including sheet and rill, ephemeral gully, and channel erosion. 

This study describes the ephemeral gully erosion capabilities within the AnnAGNPS model and discusses research needs to further improve these components for integrated conservation management planning.  Conservation management planning by agencies within the U.S. and by international organizations requires a systematic approach when determining the extent of ephemeral gully erosion impacts on a field, watershed, or national basis, and/or to predict recurring or new locations of ephemeral gullies prior to their development.  This technology provides the capability to separate the impact of ephemeral gullies on erosion from other sources and then evaluate the impact of targeted practices to control erosion at the source and subsequent downstream resources.

How to cite: Bingner, R., Wells, R., Momm, H., and Locke, M.: Enhanced Ephemeral Gully Erosion Science within AnnAGNPS , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6677, https://doi.org/10.5194/egusphere-egu24-6677, 2024.

EGU24-7471 | ECS | Posters virtual | SSS2.3

Comparing different approaches to measure erosion by concentrated flow in a rainfed agroecosystem in SE Spain: Field inventory vs RPAS 

Efraín Carrillo-López, Adolfo Calvo Cases, Pedro Pérez Cutillas, and Carolina Boix-Fayos

Concentrated-flow erosion and sheet erosion are main drivers of soil loss in Mediterranean agroecosystems with soft lithologies. Morphologies of concentrated-flow erosion were assessed in a terraced rainfed almond crop (Prunus dulcis Mill.) located on Tertiary marls in SE Spain, using two methodologies: i) field inventory and ii) photogrammetry through images taken with RPAS (Remotely Piloted Aircraft System). Both methods were applied to compare their results within one year after three major rainfall events. For the application of the field inventory, each morphology was divided longitudinally, measuring their dimensions (width, length and depth) to estimate the volume of mobilized material following the shape of each division. RPAS images were processed to obtain digital elevation models (DEMs) and orthophotos, which were subsequently used to identify erosional morphologies and calculate the volume of mobilized material through variation in height and resolution of the DEMs. Sampling for soil’s bulk density was carried out to convert volume into mass. Differences between second and first inventory or flight (period 1), and between third and second ones (period 2) were calculated to estimate sediment yield rates.

Erosional morphologies, identified with both methodologies, were: i) rills, mainly along terraces; ii) gullies, mainly on the edges of terraces; and iii) mass movements, only on the edges of the terraces. Moreover, a fourth form not described in previous studies was identified, called mixed erosion: a joint action of laminar and concentrated flow under extreme rainfall conditions. This form appeared at the base of gullies and, occasionally, connecting gullies.

In period 1, gullies showed higher median sediment yield than rills, both with field inventory (1,3 ± 1,7 y 0,22 ± 0,11 t ha-1 y-1, respectively), and photogrammetry (1,37 ± 1,01 y 0,24 ± 0,2 t ha-1 y-1, respectively). While, in period 2, mixed forms and gullies were more erosive than rills and mass movements, both with field inventory (8,8 ± 0,9, 2,4 ± 1,9, 0,54 ± 0,48 and 1,1 ± 0,8 t ha-1 y-1, respectively), and photogrammetry (1,7 ± 1,1, 1,2 ± 0,9, 0,23 ± 0,18 and 0,15 ± 0,11 t ha-1 y-1, respectively).

69, 16 and 50 % of the rills, gullies and mass movements, respectively, identified through inventory method were also identified with RPAS images. In contrast, all of the mixed erosional morphologies identified in the field survey were vissible in the RPAS images. The proportion of rills and gullies identified simultaneously with both methods increased in successive samplings, likely due to the increased intensity of the successive rainfall events, resulting in more easily identifiable features. Finally, for those morphologies identified with both methods, the RPAS sediment yield estimations were 40 – 50 % higher than those made by inventory method, probably due to the difference in resolution between methods.

The mixed form of erosion and the gullies showed a high erosive potential, involving a great environmental threat on this kind of agroecosystems. At a relatively low cost, RPAS, through its greater resolution, can help to get more reliable values of concentrated erosion rates in rainfed agroecosystems than field inventories.

How to cite: Carrillo-López, E., Calvo Cases, A., Pérez Cutillas, P., and Boix-Fayos, C.: Comparing different approaches to measure erosion by concentrated flow in a rainfed agroecosystem in SE Spain: Field inventory vs RPAS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7471, https://doi.org/10.5194/egusphere-egu24-7471, 2024.

EGU24-7648 | ECS | Posters on site | SSS2.3

Analysis of some gully control techniques for the conservation of olive cropped landscapes in Southern Spain 

Paula González Garrido, Adolfo Peña, Tom Vanwalleghem, and Juan Vicente Giráldez

The current evolution of climate in Southern Europe, apparently enhances the frequency and persistence of rainless spells, with interspersed short and intense rainfall events. Both circumstances exacerbate the soil erosion episodes, particularly in the olive cropped landscapes, with the consequent risk of soil productivity loss and the dispersion of pollutants. The most common erosion form, gully erosion, act as preferential ways for the removal and dispersal of runoff and sediments.

Although the near-future climate scenarios are uncertain, new and more effective integrated management systems need to adopted to preserve both the food generation potential, and the environment.

The purpose of this work is to analyze some techniques for the assessment of the gully erosion, from the photo-interpretation of the sequence of historical photograms, including Machine Learning methods to avoid the subjectivity of the observer, to the acquisition of new multi-spectral images with UAV. The nest step is the selection of the optimal location of the prevention, such as cover crops and vegetative barriers, and control, like check-dams for the interception of runoff and sediments.

The final outcome of the proposed techniques is the use of the fill-and spill concept to enhance an intermittent connectivity in the gully networks with the additional advantage of the increased biodiversity in the landscapes.

How to cite: González Garrido, P., Peña, A., Vanwalleghem, T., and Giráldez, J. V.: Analysis of some gully control techniques for the conservation of olive cropped landscapes in Southern Spain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7648, https://doi.org/10.5194/egusphere-egu24-7648, 2024.

EGU24-12354 | Posters on site | SSS2.3

Event Based Modeling of Ephemeral Gully Development in Agricultural Fields 

Dalmo Vieira, Robert Wells, Daniel Yoder, and Ronald Bingner

Ephemeral gullies (EGs) are channels that form in low parts of the field where runoff concentrates, and are often responsible for considerable soil loss from agriculture fields. Unfortunately, predicting the gradual development of gullies in response to storm events remains challenging. The United States Department of Agriculture has developed several modeling tools to predict the location and dimensions of ephemeral gullies and the resulting soil loss. The tool described herein combines precise geospatial determination of EG pathways with soil erosion and delivery calculations for both those pathways and the contributing hillslopes.

Considering the vital importance of determining runoff concentration for EG development, high-resolution (0.5 ~ 3 m) terrain elevation data are processed with specialized geospatial tools to determine topography-driven surface runoff patterns and define swales where concentrated flows occur.  This creates integrated surface drainage descriptions defining hillslope areas where sheet-and-rill erosion predominates, and swales where EG gullies may develop. This results in detailed flow maps covering entire fields, optionally considering oriented roughness created by crop rows on flow distribution.  These data, along with topography-derived parameters and spatial distributions of soil types and vegetation cover, form the digital landscape description for erosion modeling.

The magnitude, frequency, and seasonal distribution of storms are represented by a synthetic series of events derived from long-term climate databases created for the RUSLE2 (Revised Universal Soil Loss Equation, version 2) model.  Runoff for each storm event is estimated with RUSLER (RUSLE2-Raster), a two-dimensional (2D) raster implementation of RUSLE2 technology that calculates runoff and sheet-and-rill soil loss for all flow paths covering a field.  The RUSLER calculation provides the spatial and temporal distribution of incoming runoff and sediment loads necessary for the calculation of erosion and deposition in the EG channels.

The channel flow and sediment transport model EphGEE (Ephemeral Gully Erosion Estimator) employs an excess shear stress approach to determine where flow erosive forces cause soil detachment and transport, and where deposition occurs.  EphGEE also calculates the rates at which channels locally deepen and widen, thus predicting how channel geometry evolves during each storm, which depends strongly on knowledge of soil erodibility parameters. EphGEE attempts to estimate how erodibility parameters vary in time and with depth using management operations data available from RUSLE2 databases. In most cases, however, field data and parameter calibration are still necessary.

This modeling approach has been applied to monitored fields in the United States.  It was successful in determining runoff and concentrated flow paths, resulting in good predictions of locations where gullies form and how they connect to runoff-generating areas.  For tilled fields where a less erodible soil layer exists, the model provides good approximations of gully depths and widths. For no-till and pasture-to-crop transitions, where EG cross-sectional shapes may be dependent on how erodibility varies with soil depth, better data or prediction methods are needed to improve model performance.

How to cite: Vieira, D., Wells, R., Yoder, D., and Bingner, R.: Event Based Modeling of Ephemeral Gully Development in Agricultural Fields, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12354, https://doi.org/10.5194/egusphere-egu24-12354, 2024.

EGU24-12394 | Posters on site | SSS2.3 | Highlight

Automatic generation of topologically connected gully networks for integrated erosion control in sloping olive orchards 

Adolfo Peña, Paula González-Garrido, Ana María Laguna, and Antonio Miguel Gámiz

The severe erosion problems affecting large areas of olive groves on slopes in Andalusia (Spain), whose soil losses exceed 40 kg m-2an  in extreme rainfall events, require an integrated watershed management run by landowners and state or regional agencies.

The most common, and most severe erosion form is gully erosion. Gullies act as preferential ways through which soli particles with adsorbed nutrients and agrochemical substances spread downslope moved by surface runoff, what implies a great water loss.

During the last four years a cooperative innovation project between the University of Cordoba and two joint venture groups to (i) evaluate the extent of the soil loss in selected slopes, (ii) estimate the density and location of check-dams to intercept the water and sediment flows; (iii) design a novel type of modular dams; and (iv) complement th conservation works with new cover crops mixtures.

A by-product of this project is the development of an automatic model for the spatiotemporal evolution of gully networks based on the D8 flow direction algorithm, and a network branches detection scheme to accumulate flow identifying the final outlet.

This model has been successfully applied to two olive cropped slopes of Southern Spain.

The innovative proposal has allowed for: (a) Generation of the DEM (Digital Elevation Model) for hydrological modeling of watersheds and determination of gullies and areas vulnerable to erosion; (b) Development of algorithms for a topologically connected network of gullies to establish the areas of origin of soil loss and sediment deposition (c) Protection and correction of ephemeral and deep gullies in pilot plots by means of dikes of modular pieces, vegetation covers in crop roads, protection of roads and vulnerable areas through native plantations, and burying of pruning remains; (d) Monitoring and follow-up of measures from LiDAR sensors on board UAVs and soil analysis before and after extreme events.

These initiatives have already been successfully tested in several projects in which the University of Cordoba participates, such as the CPI INNOLIVAR project and the HIDROLIVAR Operational Group and will be implemented in new study basins where excellent results are expected due to the fragility of steep slope olive groves in very degraded soils.

How to cite: Peña, A., González-Garrido, P., Laguna, A. M., and Gámiz, A. M.: Automatic generation of topologically connected gully networks for integrated erosion control in sloping olive orchards, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12394, https://doi.org/10.5194/egusphere-egu24-12394, 2024.

EGU24-14301 | ECS | Posters on site | SSS2.3

Quantification Studies on Ephemeral Gully Erosion 

Ximeng Xu

Ephemeral gullies (EGs) are major contributors to sediment loss and land degradation on cultivated lands. EG is an important linear erosion feature, often occurring at mid-slope position, that can be greatly influenced by upslope and lateral inflow. This study quantified the ephemeral gully erosion influenced by the upslope and lateral inflow, and the results showed that upslope and lateral inflow both contributed to the runoff connectivity of the EG channel and lateral rills in the EG system. For these simulated conditions, upslope inflow contributions to total runoff and soil loss were 62–78% and 65–81%, respectively, while lateral inflow only contributed around 10%. The contribution differences could be attributed to flow hydrodynamic characteristics in that shear stress and stream power in the EG channel were 4.9–8.6 times greater than those on the lateral slopes. From sheet flow to rill flow and EG channel flow, the flow regime gradually shifted from laminar and subcritical flow to turbulent and supercritical flow. The flow force, power, and energy correspondingly increased as the flow regime changed toward turbulent and supercritical. Both field monitoring and indoor simulation displayed the additional sediment delivery caused by upslope sediment-laden flow, verifying the transport-dominated sediment regime in EG systems. In field observations, the sediment increment coefficient (SIC, ratio of net sediment delivery caused by upslope sediment-laden flow to the total sediment delivery) on an event scale varied from 4.6% to 88.6%. In indoor simulations, the SIC changed from 24.9% to 87.5%. The SIC linearly decreased as the sediment concentration of upslope inflow increased. Field monitoring showed complicated phenomena because of natural random variations. SIC also generally decreased as the sediment concentration of upslope inflow increased. Laboratory simulations verified the field monitoring results of extreme rainfall events with large rainfall amounts and intensities. In future studies, multiple morphological criteria defining EG under various environments are urgently needed. Similar to the continuous sediment transport equations for rill erosion, continuous sediment transport equations for EG erosion need to be developed.

How to cite: Xu, X.: Quantification Studies on Ephemeral Gully Erosion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14301, https://doi.org/10.5194/egusphere-egu24-14301, 2024.

EGU24-20 | ECS | Orals | HS9.2

Effect of Sampling Design on Characterizing Surface Soil Fingerprinting Properties. 

Maria Luna, Alexander Koiter, and David Lobb

Purpose: The characterization of soil properties is an important part of many different types of agri-environmental research including inventory, comparison, and manipulation studies. Sediment source fingerprinting (i.e., tracing) is a method that is increasingly being used to link sediment sources to downstream sediment. There is currently not a standard approach to characterizing sources and the different approaches to sampling have not been well assessed.

Methods: Grid, transect, and likely to erode sampling designs were used to characterize the geochemical, colour, grain size distribution, and soil organic matter content at two sites under contrasting land uses (agricultural and forested). The impact of the three sampling designs on fingerprint selection, source discrimination, and mixing apportionment results was evaluated using a virtual mixture.

Results: The sampling design had a significant impact on the characterization of the two sites investigated. While the number and composition of the fingerprints selected varied between sampling designs there was strong discrimination between sources regardless of the sampling approach. There were deviations in the expected apportionment results, but the overall patterns were similar across the three sampling designs.

Conclusions: Despite having an impact on the characterization of sources, the sampling design used ultimately had little impact on the conclusions drawn from the final apportionment results. Continued work at the watershed scale is needed to fully evaluate the importance of source sampling on the sediment source fingerprinting approach.

How to cite: Luna, M., Koiter, A., and Lobb, D.: Effect of Sampling Design on Characterizing Surface Soil Fingerprinting Properties., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20, https://doi.org/10.5194/egusphere-egu24-20, 2024.

EGU24-1585 | ECS | Orals | HS9.2

Understanding spatial and temporal functioning of temporary storage areas to improve their flood mitigation effectiveness 

Martyn T. Roberts, Josie Geris, Paul D. Hallett, and Mark E. Wilkinson

Temporary Storage Areas (TSAs), such as bunds, offline ponds and leaky barriers represent a nature-based solution that can offer additional storage during storm events. They are designed to intercept and attenuate surface runoff, thereby addressing various catchment challenges, including flooding, water scarcity, and soil erosion. Soil infiltration is a key TSA outflow, particularly for more common small to medium storm events, meaning TSA functioning may vary between sites with different soil properties and be time-variable due to the dynamic nature of soil structure. The lack of understanding of TSA functioning in space and time represents a major knowledge gap and acts as a limiting factor for the widespread implementation of TSAs. To address these challenges, there is a need for a TSA analysis approach that allows for the systematic evaluation of TSA functioning.  The overall aim of this study was to enhance understanding of TSA functioning and explore variability in functioning with space and time. Specifically, the objectives were to: (i) develop a systematic data-based method for characterising the functioning of various TSA types; and (ii) assess the effect of spatial and temporal soil variability on TSA functioning and flood mitigation effectiveness.

 

Here we present the TSA Drainage Rate Analysis tool (TSA-DRA tool), a new data-based mechanistic approach that utilises only rainfall and water level to characterise drainage of individual TSAs. Results from a multi-site TSA assessment in the UK revealed time-variable functioning, especially at lower levels when soil infiltration is the dominant outflow. We explored this further by assessing changes in soil physical properties (bulk density, macroporosity and saturated hydraulic conductivity) at two TSA sites. These sites shared the same TSA type (bund) and had similar volumes (~250 m3) and soils (Cambisols). However, they differed in land use (winter wheat vs spring barley and blackcurrants) and TSA surface area (800 m2 vs 2800 m2). Soil cores were taken across three spatial zones: (1) TSA active zone (<10% full) – inundated for the longest time; (2) full zone (>50% full) – active during large storms; and (3) Field zone – field control points outside the wetted footprint. This assessment was then repeated for significant temporal events e.g., post-harvest, growing season and post-flood. Results show significant soil structure variations over time and space, with degradation more pronounced in soils within the TSA wetted footprint due to inundation. While tillage effectively reset topsoil structure at one site, its impact was negligible at the other site due to variations in land management, coupled with high sedimentation post-flooding, altering near-surface soil texture. Results from a modelling exercise suggest that well-structured soils with higher infiltration rates can improve TSA effectiveness during a large storm event by reducing the volume and frequency of overflow compared to a degraded soil. Gaining insights into spatial and temporal variations in TSA functioning is crucial for optimising both current and future TSA designs and maintenance regimes.

How to cite: Roberts, M. T., Geris, J., Hallett, P. D., and Wilkinson, M. E.: Understanding spatial and temporal functioning of temporary storage areas to improve their flood mitigation effectiveness, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1585, https://doi.org/10.5194/egusphere-egu24-1585, 2024.

This study examined the sediment characteristics of areas where landslides occurred due to heavy rains between 2014 and 2019. A total of 5 types of geology in two geographic regions in Japan were examined using LiDAR LP topography data before and after the disasters occurred to estimate the changes in elevation. In addition, the volume of sediment runoff for each case was estimated for watershed areas ranging from 0.01 up to 0.1 km2. The influence of geological differences on the sediment runoff volume within the basin using indicators such as the density of landslide occurrence, landslide volume, and watershed erosion intensity was also assessed. The results showed that, for all geology types, as the watershed area increases, the relief ratio decreases and the sediment runoff volume increases; however, the magnitude of this increase in sediment runoff volume differs depending on the underlying geology. In addition, the density of landslide occurrence was high in plutonic and metamorphic rocks. The landslide volume and the total eroded sediment volume within a watershed can be regressed using the linear equation y=ax. Since the average total eroded sediment volume within a watershed is approximately twice that of the landslide volume, there is a proportional relationship of 1:2. The relationship between the relief ratio and watershed erosion intensity shows that the watershed erosion intensity increases gradually as the relief ratio increases, and the rate of increase is larger in plutonic rocks (granite and granodiorite) than in the other groups. Metamorphic rocks had a relatively low watershed erosion intensity; these geological differences are reflected in differences in the degree of erosion of stream beds and banks by flood flows.

How to cite: Akita, H.: Comparison and analysis of the influence of geological differences on sediment runoff volumes from watersheds -case study of plutonic and metamorphic rocks in two sediment disasters in Japan-, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1808, https://doi.org/10.5194/egusphere-egu24-1808, 2024.

EGU24-1817 | Posters on site | HS9.2

TRACING 2021-2024 – Feedback on international events to develop novel strategies of sediment tracing in catchments and river systems 

Olivier Evrard and the TRACING Event organisers and participants

Several innovative techniques have been developed recently opening up new avenues to establish the assessment of sediment flux in the critical zone. These innovative techniques include the tracing or “fingerprinting” methods to identify the sources and quantify the dynamics of sediment and particle-bound contaminants. However, the use of these techniques is often associated with several methodological and statistical limitations, that are often reported although rarely addressed in the framework of concerted actions taken at the level of the international scientific community.

This presentation will present the main outcomes of the Thematic School organised in 2024 and the Scientific Meeting Days organised in 2022 and 2023 as a follow-up of a first training week organised in 2021 to bring together international experts working on these topics together. Based on the publication of an opinion paper (https://link.springer.com/article/10.1007/s11368-022-03203-1), new strategies to publish and disseminate sediment tracing databases will be presented. An example of formatted dataset will be given, with the objective to test research hypotheses based on multiple datasets adopting the same format of data/meta-data. Other perspectives regarding improvements of the sediment fingerprinting method in terms of modelling, tracer options and selection will also be presented.

How to cite: Evrard, O. and the TRACING Event organisers and participants: TRACING 2021-2024 – Feedback on international events to develop novel strategies of sediment tracing in catchments and river systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1817, https://doi.org/10.5194/egusphere-egu24-1817, 2024.

EGU24-3919 | ECS | Orals | HS9.2

Exploring the sediment redistribution dynamics of a data-scarce catchment in southwestern Ethiopia using the USPED model and gully erosion threshold indices 

Haftu Yemane, Bart Vermeulen, Berhane Grum, Jantine Baartman, Ton Hoitink, and Martine van der Ploeg

Soil erosion has on– and off-site detrimental effects, including decreased soil quality and sediment buildup in reservoirs. Predicting and monitoring soil erosion is challenging due to the spatio-temporal variation of its triggering factors. Therefore, developing and successfully implementing appropriate intervention measures requires a thorough understanding of its redistribution at the catchment scale. However, many previous soil erosion prediction models have been calibrated/validated based on sediment yield at catchment outlets. This approach does not provide any insight into the sources and sinks of erosion and deposition within the catchments. Furthermore, this approach has limited applicability in regions with no (limited) measured data. Therefore, exploring spatial patterns of erosion and deposition using the recent advances in remote sensing and GIS technologies is advisable. This research integrates the semi-distributed Unit Stream Erosion Deposition (USPED) model, and gully erosion threshold indices, described by stream power index (SPI) and topographic wetness index (TWI), to evaluate the sediment redistribution dynamics of a sub-humid catchment located in Omo-basin in southwestern Ethiopia. The catchment (~77 km2) has a rugged topography with an average slope of 35.8 %. It consists of four primary types of land use and cover (LUC): rangelands (20%), forest areas (19%), built-up areas (7%) and cultivated lands (54%). The (preliminary) results revealed that the gentle and mild slopes contribute more (53%) to the overall annual catchment soil loss (42.5 t.ha-1) from the hillslope. This is because the sediment deposited in the downstream sinks remobilizes, shifting an erosion-limited to a transport-limited system. Moreover, the total contribution of rangelands and forest areas is comparable to that of cultivated lands. Therefore, by focusing our management efforts on these areas, instead of the steeper slopes, we can make a greater impact on the overall sustainability of the catchment.

How to cite: Yemane, H., Vermeulen, B., Grum, B., Baartman, J., Hoitink, T., and van der Ploeg, M.: Exploring the sediment redistribution dynamics of a data-scarce catchment in southwestern Ethiopia using the USPED model and gully erosion threshold indices, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3919, https://doi.org/10.5194/egusphere-egu24-3919, 2024.

EGU24-4719 | Posters on site | HS9.2

An approach for the reduction of the sediment volume transported by debris flow from the high-sloping reach of a debris-flow channel 

Carlo Gregoretti, Matteo Barbini, Martino Bernard, Mauro Boreggio, Sandival Lopez, and Massimiliano Schiavo

Usual works for the reduction of the sediment volume transported by debris flows are the retention basins. Retention basins are usually built on the intermediate and low-sloping reaches of the debris-flow channels or at their end, where the terrain slope is usually not high. When the space required for trapping all the sediment volume is not available or the upper part of the basin must be protected deposition areas can be used. The deposition area is a retention basin without the downstream berm, to be placed in the high-sloping reach of a debris-flow channel. Therefore, it is proposed an approach for the progressive reduction of the sediment volume transported by debris flow: an in-series combination of deposition areas in the high-sloping reaches of the channel, and retention basins in the intermediate low-sloping reaches of the flow path.

An application of such approach is shown for the design of the control works on Ru Secco Creek at the purpose of defending the resort area and the village of San Vito di Cadore (Northeast Italian Alps).

How to cite: Gregoretti, C., Barbini, M., Bernard, M., Boreggio, M., Lopez, S., and Schiavo, M.: An approach for the reduction of the sediment volume transported by debris flow from the high-sloping reach of a debris-flow channel, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4719, https://doi.org/10.5194/egusphere-egu24-4719, 2024.

EGU24-5507 | Posters on site | HS9.2

Impacts of rainfall variability on river discharges and suspended discharges : A Case Study in Chenyulan Watershed, Taiwan 

Wen-Shun Huang, Jinn-Chyi Chen, Kuo-Hua Chien, Yue-Ting Lia, and Fan Wu

In this study, the variations of rainfall, river discharges and suspended sediment discharges were analyzed in the Chenyulan watershed in Nantou County, central Taiwan. The hydrological data, such as rainfall, daily discharges and daily suspended sediment discharges, was collected based on Neimaopu hydrology station during the period from 1972 to 2020. The yearly costs of structure conservation to prevent sediment disasters and slope hazard events were implemented in the watershed between 1999 and 2020 as well. The Rating Curve Method with the formula Qs=aQb is adopted to estimate sediment discharges with the corresponding discharge events. The impact factors that caused the variation of discharges and suspended sediment discharges were also analyzed to provide the references for the influence of geological and hydrological changes on sediment yielded on slope and following suspended sediment discharges in the rivers in the watershed. The analyzed results show that the suspended sediment discharges in 1972-1989 are less than the average value in 1990-2009 at the same discharges. The suspended sediment discharges in 2010-2020 are gradually reverted to that in 1972-1989. The causes of decreasing the suspended sediment discharges in last decade are analyzed, including: 1. The variations of rainfall were gradually calmed in last decade; 2. the loose soil on slopes in the watershed caused by Chi-Chi earthquake became concreted with time; 3. the landslide and debris flow disasters obviously decreased in last decade and the soil yield from slopes has slowed down; 4. the local government involved a lot of money to build the conservation structures in upstream creeks to trap the loose soil and control the volume of sediments from flowing into rivers.

How to cite: Huang, W.-S., Chen, J.-C., Chien, K.-H., Lia, Y.-T., and Wu, F.: Impacts of rainfall variability on river discharges and suspended discharges : A Case Study in Chenyulan Watershed, Taiwan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5507, https://doi.org/10.5194/egusphere-egu24-5507, 2024.

EGU24-5559 | ECS | Posters on site | HS9.2

Impact of dam construction on suspended sediment load alteration 

Zahra Karimidastenaei, Hamid Darabi, and Ali Torabi Haghighi

Impact of dam construction on suspended sediment load alteration

Zahra Karimidastenaei a*, Hamid Darabi b, Ali Torabi Haghighi a

 

a Water, Energy and Environmental Engineering Research Unit, University of Oulu, P.O. Box 4300, FIN-90014 Oulu, Finland.

bDepartment of Geosciences and Geography, University of Helsinki, Helsinki, Finland

*Corresponding author: Email: zahra.karimidastenaei@gmail.com

 

Abstract

Climate change and human activities have always impacted the fluvial processes, encompassing floods, soil erosion, sedimentation, and sediment transport in rivers, resulting in huge environmental concerns. Dynamics analysis of suspended sediment concentration (SSC) is a determining factor in the sediment budgets, and it has an important role in water resources management. In the current research, the relationship of the suspended sediment (SS) with precipitation (R) and flow discharge (Q) has been analyzed to assess the impact of Saveh Dam on the SSC during 1971-1982 and 1983-1994 as pre and 1995-2006 and 2007-2018 as post-impact periods in the Ghareh-chay basin, Iran. To quantify the spatio-temporal variation of SSC (due to climate change and anthropogenic activities such as dam construction and land use changes), a new measure Δα-based approach was introduced. The newly developed approach, referred to as the Δα-based method, was formulated by calculating the angle between (or the change in the slope of) the optimal Precipitation-Sediment (P-S) and Flow-Sediment (F-S) fit lines. This calculation is conducted spatially, encompassing both upstream and downstream locations, and temporally, by comparing data from different periods. The findings showed that Δα for the Precipitation-Sediment (P-S) relationship between upstream and downstream increased significantly after the Saveh dam commissioning. Initially, Δα was measured at 2.69 degrees and 1.35 degrees for the two pre-impact periods upstream and downstream, respectively. However, these values rose to 5.65 degrees and 9.39 degrees in the corresponding post-impact periods. Based on these results, it is evident that the notable changes in Δα for the Precipitation-Sediment relationship between upstream and downstream indicate the dam's impact on the Suspended Sediment Concentration (SSC) patterns in the Ghareh-chay river. The relatively short distance between the upstream and downstream gauge stations further supports the conclusion that these observed changes in Δα are directly attributable to the dam's influence, significantly altering sediment dynamics in the river system.

Keywords: Saveh dam; dynamics analysis; pre- and post-impacted; quantitative approach, sediment rating curve

 

Fig. 1. Location of the study area

How to cite: Karimidastenaei, Z., Darabi, H., and Torabi Haghighi, A.: Impact of dam construction on suspended sediment load alteration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5559, https://doi.org/10.5194/egusphere-egu24-5559, 2024.

EGU24-5752 | ECS | Posters on site | HS9.2

Exploring Remote Sensing Methodologies for River Bed Grain Size: Insights from a Mountainous Watershed Study in Val Camonica, Italy 

Matteo Benetti, Payam Heidarian, Riccardo Bonomelli, and Marco Pilotti

The measurement of river bed grain size has become an integral aspect of fieldwork in river geomorphology and regional ecology. Over the past years, various authors have proposed remote sensing methodologies to assess grain size based on ground and aerial images. With the burgeoning applications of small unmanned aerial systems (SUAS) in geomorphology, there is a burgeoning interest in leveraging these remote sensing granulometry methods for SUAS imagery. However, a dearth of studies exists that systematically investigate spatially consecutive images yielding grading curves or specifications over extensive areas within mountainous watersheds.

This study focuses on the granulometry of the mountainous watershed in Val Camonica, located in northern Italy, employing a drone for initial photographic documentation. The study incorporates the BaseGrain software for importing drone spatially consecutive images and extracting granulation curves from the photographed areas. Additionally, the study encompasses the utilization of Structure-from-Motion (SfM) photogrammetry within a Ground Control Points (GCP) workflow to scale the drone-acquired photos. The precision of this scaling is systematically validated by comparing photos with scaling images including meter using BaseGrain software. The precision of AGISOFT software, employed in the SfM-photogrammetry process, is also critically evaluated by itself with different numbers of benchmarks.

Results indicate that, despite the non-professional nature of the instrumentation, the acquisition of high-resolution images is feasible. These images enable the generation of Digital Elevation Models (DEMs) with accuracies ranging between 2 and 3 cm, contingent upon the number of ground control points. The granulation curve, extracted through BaseGrain, exhibits acceptable accuracy within meter-scale resolution. This research contributes valuable insights into the potential of SUAS-based remote sensing granulometry for mountainous watersheds and underscores the importance of methodological precision for reliable results in river geomorphology studies.

How to cite: Benetti, M., Heidarian, P., Bonomelli, R., and Pilotti, M.: Exploring Remote Sensing Methodologies for River Bed Grain Size: Insights from a Mountainous Watershed Study in Val Camonica, Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5752, https://doi.org/10.5194/egusphere-egu24-5752, 2024.

EGU24-7560 | ECS | Posters on site | HS9.2

Impact Analysis of Series of Groundsills on the Fluvial Stability and Geomorpholog 

Pohsuan Lin, Tsungyu Hsieh, Kuowei Liao, Kailun Wei, and Guanyu Lin

To mitigate riverbed erosion both longitudinally and transversely, control water flow, and stabilize riverbanks, the use of groundsills has become a widely adopted engineering method. For large conservation areas, using a series of groundsills is standard practice. However, the sediment transport in rivers is a dynamic process, and the implementation of series groundsills can cause discontinuities in the longitudinal corridor of the river, leading to damage to the ecological environment and landscape. Although there is considerable consensus on various aspects of series of groundsills, current research primarily focuses on the influence of the configuration of groundsills (such as height and width) on sediment downstream. Therefore, this project aims to estimate the trends in sediment transport through scaled experiments and numerical simulations. Results shown that according to the analysis results, neither the Q5 nor Q95 criteria are met in the proposed plan for the complete removal of the groundsills. This project believes that the complete removal of the groundsills may have a drastic impact on the environment, potentially leading to unstable conditions, and thus requires careful evaluation. The design of openings in the groundsills is an effective ecological adjustment project. Regarding the design of the opening height, this project suggests considering two factors: one is to reduce the similar damming effect caused by lowering the elevation, and the other is the gathering of water flow. It is a trade-off between these two factors. Increasing the depth of the opening may benefit the ecology but could lead to unintended erosion due to concentrated water flow, and vice versa.According to the analysis results, neither the Q5 nor Q95 criteria are met in the proposed plan for the complete removal of the fixed-bed structure. This project believes that the complete removal of the fixed-bed structure may have a drastic impact on the environment, potentially leading to unstable conditions, and thus requires careful evaluation. The design of openings in the fixed-bed structure is an effective ecological adjustment project. Regarding the design of the opening height, this project suggests considering two factors: one is to reduce the similar damming effect caused by lowering the elevation, and the other is the gathering of water flow. It is a trade-off between these two factors. Increasing the depth of the opening may benefit the ecology but could lead to unintended erosion due to concentrated water flow, and vice versa. he proposed plans can optimize benefits for both upstream and downstream water conservation, and protect downstream objectives by managing sediment transport.

Keywords: series groundsill, ecology, sustainable management, sediment transport

How to cite: Lin, P., Hsieh, T., Liao, K., Wei, K., and Lin, G.: Impact Analysis of Series of Groundsills on the Fluvial Stability and Geomorpholog, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7560, https://doi.org/10.5194/egusphere-egu24-7560, 2024.

EGU24-7827 | Orals | HS9.2

Impacts of check dams: a monitoring experience along a mountain watercourse 

Alessio Cislaghi, Dario Bellingeri, Vito Sacchetti, Emanuele Morlotti, and Gian Battista Bischetti

Torrential dynamic is a complex combination of natural processes along a mountain watercourse, including sediment deposition and erosion that cause cross-section occlusions and streambank failure, respectively. Thus, monitoring and managing sediments are fundamental activities for the maintenance in mountain watersheds. To regulate the sediment transport, a common countermeasure is the check dam, designed to control the sediment movement along the watercourse (Piton et al., 2017). Building check dams is complex and expensive, especially in mountain watercourse. These structures largely modify the surrounding environment and landscape; however, if well designed, check dams are very effective solutions to mitigate the potential losses due to flood, debris flood, and debris flow.

This study presents the monitoring of a stretch of a mountain watercourse over several years in an Alpine environment. The observed dominant process was the sediment deposition that has been countered by the construction of a slot check dam. The torrential dynamic has been strongly influenced by this in-channel structure, exacerbating the change of cross-sectional and longitudinal profiles (width and depth of the cross-sections, longitudinal profile, and bed granulometry) not only in proximity of the structure, but also along the observed overall stretch (downstream and upstream). The monitoring consists in measuring the hydrological response during rainfall events and assessing the geomorphic change using digital elevation models differencing (2010, 2014, 2021, 2023). The last topographic surveys were conducted immediately after the construction of the slot check dam and immediately after the first severe debris flood occurred several months later.

The results of monitoring show a clear geomorphic evolution along the observed stretch, contrary to the previously detected tendency of sediment dynamics and, moreover, a different hydrological response at downstream of the structure. As expected, sediments were trapped upstream of the structure, whereas a severe erosion removed the armoring layer bringing to light several bed sills at downstream.

This study underlines how artificial works have a spatially distributed effects on geomorphological change, on hydraulic behaviour, and in some cases on the flood hazards (also far from the structure). Thus, the prediction of geomorphological change, even if qualitative, is extremely important to improve the effectiveness of the check dam in managing sediment dynamics. In addition, sharing this information is essential to support designers (showing practical examples) in planning works not only focusing on the structural and hydraulic perspectives, but also from a geomorphological point of view, which is often neglected.

Piton, G., Carladous, S., Recking, A., Tacnet, J.M., Liébault, F., Kuss, D., Quefféléan, Y., Marco, O., 2017. Why do we build check dams in Alpine streams? An historical perspective from the French experience: A Review of the Subtle Knowledge of 19th Century Torrent-Control-Engineers. Earth Surf. Process. Landforms 42, 91–108. https://doi.org/10.1002/esp.3967

How to cite: Cislaghi, A., Bellingeri, D., Sacchetti, V., Morlotti, E., and Bischetti, G. B.: Impacts of check dams: a monitoring experience along a mountain watercourse, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7827, https://doi.org/10.5194/egusphere-egu24-7827, 2024.

EGU24-8068 | ECS | Posters on site | HS9.2

The new Austrian standard ÖNORM B4800 for torrent control work 

Georg Nagl, Johannes Hübl, and Jürgen Suda

Austria has a wide variety of protection structures at different condition levels due to the long tradition of torrent control works in the Austrian Alps. This has resulted in a large stock of protection structures and load models. In order to standardise the design of technical structures based on the Eurocode, including torrential processes, snow avalanches and rock fall, an interdisciplinary working group (ON-K-256) was established. The standardisation for torrential processes covers the definition and classification, the impact on structures, the design of structures, and the operation, monitoring and maintenance. These parts are based on and interact with EN 1990 (the basis of structural design), EN 1992-1-1 (the design of concrete structures), EN 1997-7 (geotechnical design) and the related documents for the Austrian national specifications. For torrential mass wasting processes with high variability in the concentration of solids, modern protection concepts are scenario-oriented. To optimize the mitigation measures for a multi-stage system, a functional chain must be implemented. This chain should have different structures to perform various functions such as dosing, filtering, and energy dissipation. When designing these torrential mitigation structures, it is necessary to simplify the model parameters, stress model, and load distribution. For debris flows, a standardized stress model combines the static and dynamic loads of debris flow impact on structures. This model was calibrated using available impact measurements of real debris flows and is in good agreement with common engineering design methods in Austria for debris flow impact on torrential barriers. The proposed method enables practitioners to design debris flow countermeasures with limited data availability.

How to cite: Nagl, G., Hübl, J., and Suda, J.: The new Austrian standard ÖNORM B4800 for torrent control work, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8068, https://doi.org/10.5194/egusphere-egu24-8068, 2024.

EGU24-8164 | ECS | Posters on site | HS9.2 | Highlight

Reconstructing the Flood History of Nan Ancient City: Insights from Sedimentary Analysis 

Prapawadee Srisunthon, Alex Berger, Alex Fuelling, Mubarak Abdulkarim, Damien Ertlen, Daniela Mueller, Jakob Wilk, Meike Reubold, and Frank Preusser

Monsoon-induced floods have played a pivotal role in shaping the fortunes of Asian civilizations and communities over the millennia, and their far-reaching consequences persist to this day. This study delves into the floodplain east of Nan ancient city, a city during Lan Na period in northern Thailand dating back to the 13th century AD. Our primary objective was to unravel the source direction of a catastrophic flood event in 1818 AD, which ultimately led to the city's relocation. Our sedimentological analyses revealed a diverse range of deposition. An innovative provenance study using mid-infrared spectroscopy (MIRS), conducted for the first time in this region, indicated a significant contribution from eastern tributaries not from the Nan River. Only two of the nine sediment cores (WTR and HH2) presented evidence of Nan River sediment. Optically stimulated luminescence (OSL) dating revealed a striking pattern: modern floods dominated the shallow depths (ca. 0-1.10 m) of all cores, while deeper layers exhibited unexpectedly older ages, exceeding 11,000 years. This finding aligns with climate data from multiple proxies, suggesting that Nan ancient city, akin to neighboring e.g. Kingdom of Angkor, endured a dry period. Based on these comprehensive findings, we postulate that the 1818 AD flood catastrophe originated from the east. The deluge may have been triggered by rainfall during an extended dry spell, when the parched and compacted soil's permeability was severely diminished. This sudden surge of water swiftly transported the sediment, ultimately inundating and devastating the city. The insights gained from this study are a reminder of the profound impact of monsoon-related floods on human settlements in Asia. By understanding the conceptions between sedimentology, provenance, and climate, we can better comprehend the historical and ongoing challenges posed by these natural disasters and advance strategies for sustainable development in vulnerable regions.

Keywords: flood sediment, monsoon, Southeast Asia,  provenance analysis, OSL dating, Lan Na, Nan, Thailand

How to cite: Srisunthon, P., Berger, A., Fuelling, A., Abdulkarim, M., Ertlen, D., Mueller, D., Wilk, J., Reubold, M., and Preusser, F.: Reconstructing the Flood History of Nan Ancient City: Insights from Sedimentary Analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8164, https://doi.org/10.5194/egusphere-egu24-8164, 2024.

EGU24-8675 | ECS | Posters on site | HS9.2

Assessment of flash flood impacts in a mountain basin: an integrated approach for the management of channel control works 

Francesco Piccinin, Lorenzo Martini, Sara Cucchiaro, Giacomo Pellegrini, Eleonora Maset, Alberto Beinat, Tommaso Baggio, Federico Cazorzi, and Lorenzo Picco

In mountain basins, the predominant approach to control the supply and transport of large volumes of sediment involves the installation of hydraulic structures within the channel network. While torrent control works are fundamental in reducing flash flood impacts, their effectiveness during time need regular monitoring and maintenance. However, few studies have proposed a workflow based on simple factors and criteria collected in the field to prioritize management interventions of torrent control works in a mountain basin. In this work, the aims are to assess the effectiveness of the hydraulic structures and to quantify their impact on sediment continuity in the Vegliato mountain basin (Italy), affected by a flash flood event occurred on the 30th July 2021. First, rainfall data from 2019 to 2022 are analyzed to detect and characterize the event that caused the flash flood. The assessment of post-event status and functionality of the control works is done using a novel Maintenance Priority index (MPi), distinguishing the structures that no longer fulfil their role and providing an overview on the maintenance and re-planning of the management system. These results integrate the analysis of multi-temporal High Resolution Topography (HRT) data deriving from LiDAR surveys. DEMs of Difference (DoDs) are generated to map the geomorphic changes occurred during the event, quantifying the sediment fluxes impacting on the control works and viceversa. The role of torrent control works is also analyzed in terms of continuity of the sediment cascade applying a novel parameter, the Sediment (dis)Continuity Ratio (SCR), which assesses the capability of the torrent control works system in intercepting and storing a sediment mass fraction constituting the cascade (obtained by DoD) and identifies the hydraulic structures that contribute or limit the sediment (dis)continuity along the channel network.

The application of the MPi indicates that the 16% of the control works should be given the highest maintenance priority (MPi = 1). The 45% of the hydraulic structures exhibit 0.63 ≤ MPi ≤ 0.88 and are in need of intervention to ensure the durability of the structures themselves. On the other hand, 12% of the control works require re-planning operations (0.25 ≤ MPi ≤ 0.50) due to their good structural condition but low functionality. Eventually, the 25% of the structures show MPi = 0 and are in the lowest range of priority for the interventions. These results were also corroborated by the DoD results, which supported the MPi. The analysis of the SCR shows how several torrent control works, especially the ones located in the upper part of the catchment, promote continuity (SCR from -100 to -0.1). On the other hand, several structures in the middle part of the main channel show positive SCR values, therefore promoting discontinuity. The highest values of SCR are found in the downstream and wider part of the main channel.

Finally, the workflow composed of different methodologies adopted in this work provides a detailed overview of the interaction between sediment dynamics and torrent control works and represent a useful tool to develop effective management decisions and plans.

How to cite: Piccinin, F., Martini, L., Cucchiaro, S., Pellegrini, G., Maset, E., Beinat, A., Baggio, T., Cazorzi, F., and Picco, L.: Assessment of flash flood impacts in a mountain basin: an integrated approach for the management of channel control works, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8675, https://doi.org/10.5194/egusphere-egu24-8675, 2024.

EGU24-9330 | Orals | HS9.2

(Dis)connected mountain headwaters: advocating for a paradigm shift in sediment management strategies 

Tomáš Galia, Václav Škarpich, and Tereza Macurová

Beyond land-use alterations at the catchment scale, numerous mountain catchments across Europe have experienced significant morphological changes and shifts in sediment transport dynamics over the past two centuries, largely attributable to the implementation of torrent control structures. A notable example is the mountainous part of the Czech Carpathians, where a comprehensive sediment management regime was introduced at the turn of the 19th and 20th centuries. This approach, based on methodologies established in the Austrian Alps, encompassed the installation of check dams and artificial bank stabilizations. Such practices have remained predominant in these areas, with certain catchments smaller than 25 km² exhibiting substantial portions of their stream lengths stabilized through sequences of consolidation check dams, bed sills, and riprap bank stabilizations.

However, it is crucial to consider the distinct nature of external factors influencing rainfall-runoff processes and sediment supply in the 19th century. This period was marked by the end of the Little Ice Age and a higher prevalence of deforested areas, linked with active gully development. Given the contemporary context of extensive reforestation and subtly altered hydroclimatic conditions, the appropriateness of continuing such 'hard and intensive' management strategies for local streams warrants reassessment.

Consequently, a sediment deficit in both mountain channels and foothill gravel-bed rivers has been observed. It resulted in channel transformation with sediment coarsening, the loss of gravel bars (as vital habitats), and, in some instances, channel incision into the bedrock. This situation necessitates a reconsideration of sediment-control strategies within the frameworks of fluvial continuum and sediment (dis)connectivity, particularly since these headwaters function as primary sediment sources. Without modifying these management approaches, enhancing the hydromorphological state of streams and rivers in the Czech Carpathians remains a formidable challenge.

How to cite: Galia, T., Škarpich, V., and Macurová, T.: (Dis)connected mountain headwaters: advocating for a paradigm shift in sediment management strategies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9330, https://doi.org/10.5194/egusphere-egu24-9330, 2024.

EGU24-9807 | ECS | Posters on site | HS9.2

Quantifying Sediment Dynamics in an Alpine River Catchment using a 10Be Tracing Method  

Chantal Schmidt, David Mair, Fritz Schlunegger, Brian McArdell, Marcus Christl, and Naki Akçar

In this study, we quantify the spatial variation in sediment generation for the c. 12 km2 large Gürbe catchment situated at the northern margin of the Swiss Alps. We particularly trace the sediment transfer from the hillslope to the channel network in the headwaters, and finally to the depositional fan at the downstream end of the catchment. Mapping shows that sediment production in the Gürbe catchment occurs through three primary mechanisms: (1) overland flow erosion generating sand and silt, contributing to the generation of suspension loads; (2) shallow and deep-seated landslides linked to the main channel, both supplying a mixture of gravel, boulders, and silt/sand during floods, thus generating sediment for both the bedload and suspension load of the Gürbe River; and (3) incision of the river into glacial till in the upper headwaters and into landslides farther downstream. The bedrock of the Gürbe catchment comprises Molasse, Flysch, and Quaternary deposits, posing challenges in tracing the origin of the material and estimating the relative importance of the various processes for sediment generation.  However, previous research has shown that the cosmogenic 10Be concentration can differ for various sediment sources (Cruz Nunes et al. 2015; e.g.). Therefore, we measured 10Be concentrations in the sand fraction (0.25 – 2 mm) in the main channel and in the tributaries, aiming to capture suspension load signals generated through overland flow erosion and landslides. As a novel approach, we also determined the bulk 10Be concentration of gravels (2 – 10 cm) collected from the same sampling locations in the Gürbe channel, in the three tributaries as well as from the landslide tongues reaching into the Gürbe. The results point to three different conclusions: First, there exists a clear difference between the signals measured in the sand fraction and the gravel samples. In particular, the 10Be concentrations in the sand fraction are two to four times higher than those measured in the gravel at the same sites. This grain size dependence aligns with previous findings by Puchol et al. (2014). Second, the sand samples in the main channel show a downstream decrease in 10Be concentration, thereby reflecting the supply of material from the tributaries and particularly from the landslides with low 10Be concentrations. Third, bulk gravel samples reveal a larger variability in 10Be concentrations than the sand samples at the same locations. This suggests that the supply and downstream transport of the coarse-grained bedload material occurs more episodic than the generation and transfer of the suspension load. 

 

REFERENCES 

Cruz Nunes, F., Delunel, R., Schlunegger, F., Akçar, N., & Kubik, P. (2015): Bedrock bedding, landsliding and erosional budgets in the Central European Alps. Terra Nova, 27(5), 370-378.

Puchol, Nicolas; Lavé, Jérôme; Lupker, Maarten; Blard, Pierre-Henri; Gallo, Florian; France-Lanord, Christian (2014): Grain-size dependent concentration of cosmogenic 10Be and erosion dynamics in a landslide-dominated Himalayan watershed. In: Geomorphology 224, S. 55–68.

How to cite: Schmidt, C., Mair, D., Schlunegger, F., McArdell, B., Christl, M., and Akçar, N.: Quantifying Sediment Dynamics in an Alpine River Catchment using a 10Be Tracing Method , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9807, https://doi.org/10.5194/egusphere-egu24-9807, 2024.

Land-use specific sediment source apportionment using compound specific isotopic tracers occurs with challenges from both contributions from aquatic  and particulate organic matter sources. Additionally, compound specific tracers have often occurred with co-linearity. Challenging our current understanding of erosion processes, previous studies using compound-specific isotopic tracers regularly indicate forests as the dominant source of sediment. We hypothesized that this estimation may be attributed to misclassifying particulate organic matter as a sediment contribution from forests.

This study is based in Lake Baldegg (Lucerne, Switzerland) and utilizes the δ13C values of lignin-derived methoxy groups and alkane average chain length as an additional land-use-specific tracer to δ13C fatty acids. Three Suess corrections using different tracer residence times are applied to constrain the changing δ13C values of CO2 in the atmosphere over the last 130 years. To identify changes in sediment sources over the last 130 years, contributions of particulate organic matter are determined, and subsequently removed to apportion only the mineral associated soil fraction. To determine the confidence which can be applied to the model’s output, the model's performance is evaluated with 300 mathematical mixtures. The potential misclassification of forest contributions is investigated by merging particulate organic matter and forest sources to simulate tracers which are unable to discriminate between these two sources.

The incorporation of δ13C values of lignin methoxy groups and alkane average chain length as additional tracers successfully expands the problematic one-dimensional mixing line.  Mathematical mixtures demonstrate the improvement of the model’s performance when using both the average chain length and δ13C values of lignin-derived methoxy groups as an additional tracer. Furthermore, they also demonstrate an underestimation of arable contribution. Changes in dominant sediment sources (Forest: pre-1990, Pasture: 1910-1940, Arable: post-1940) highlight the influence of policy-induced land-use changes. Additionally, the study reveals a 37% overestimation of forest contributions to the sediment core due to the inability to discriminate between particulate organic matter and forest sources.

The use of δ13C values of lignin methoxy groups as an additional tracer enables the identification of critical points in the 130-year sediment history of Lake Baldegg. We emphasize the importance of incorporating multiple Suess corrections to constrain the effect of multiple turnover times of tracers. While merging forest and particulate organic matter sources did not alter the dominant source over the last 130 years, it highlighted the need of separating these sources for more accurate apportionment. The study contributes valuable insights to sediment dynamics and land-use impacts, offering guidance for environmental management strategies.

How to cite: Cox, T., Laceby, P., Greule, M., Keppler, F., and Alewell, C.: Using stable carbon isotopes of lignin derived methoxy groups to investigate the impact of historical land use change on sediment/particulate matter dynamics , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10471, https://doi.org/10.5194/egusphere-egu24-10471, 2024.

EGU24-16053 | ECS | Posters virtual | HS9.2

Hydrological and Sediment Transport Regime on Rivers in the Balkans: The Case of the Seman River in Albania 

Alban Doko, Axel Bronstert, and Till Francke

Hydrological and sediment transport regime are important in water resource management. Aim of this study is to identify the flow regime and the suspended sediment transport in a Mediterranean River Basin. Precipitation, temperature, soil, land use, discharges and suspended sediment concentration are used to quantify runoff and sediment yields at daily scales. WASA-SED (Water Availability in Semi-Arid environments – SEDiments) a spatially semi distributed model it is developed to simulate the flow and sediment transport in Seman Basin. Sediment deposits in Seman Basin contribute to a significant annual loss in the water storage capacity of the dams. Runoff and suspended sediments in Mediterranean hill slopes are closely related to rainfall intensities and land surface cover. This study gives a valuable approach in improving the prediction of flow and sediment transport in Mediterranean River Basin.

Keywords:
Flow, Sediment transport, WASA-SED, Mediterranean River Basin

How to cite: Doko, A., Bronstert, A., and Francke, T.: Hydrological and Sediment Transport Regime on Rivers in the Balkans: The Case of the Seman River in Albania, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16053, https://doi.org/10.5194/egusphere-egu24-16053, 2024.

EGU24-16690 | ECS | Orals | HS9.2

Sediment Source Identification in a Southern Brazilian Watershed: Utilizing Geochemical Properties and Spectral Signatures with Mixing Models 

Mélory Araujo, Gema Guzmán, José Alfonso Gómez, Alexander Koiter, Stefan Nachtigall, and Pablo Miguel

 

One of the main impacts of water erosion within a watershed is the downstream deposition of sediments in watercourses and decrease in water quality, esigning and implementing effective soil and water conservation practices to address these impacts requires a soil conservation practices. Increasingly, researchers are using sediment source fingerprinting methods which use physical, biological, and geochemical attributes of the soil and sediments as tracers (Tiecher et al., 2015). Identifying sediment sources enables targeted corrective measures, but tracer selection and fingerprinting feasibility are ongoing debates among experts (Lizaga et al., 2020; Owens et al., 2022).

This study focuses on identifying sediment sources to develop erosion mitigation plans in a 33.3 km² rural river basin, in southern Brazil, crucial for supplying the municipality of Pelotas. Three primary sediment sources were identified: annual crops, perennial forage (pastures), and gutters (river channels). Samples were collected from the surface horizon (0-20 cm) of agricultural land and perennial pastures. Gutter samples were collected from the underground horizon, where active erosion processes were taking place. In total, 116 source samples were obtained. Nine sediment samples were collected from six sites across the study area every two months during 2021-2022, forming three collections for each sub-area of the river basin (A1, A2, and A3). Traditional fingerprinting methods, utilizing geochemical tracers, total organic carbon, and color coefficient tracers in the visible spectrum, were employed to analyze the soil of the contributing area and the sediments. The FingerPro (v1.1; Lizaga, 2018) mixture model was applied to evaluate the contributions of sediment sources to the collected sediment.

This communication presents preliminary results of 37 tracers: 22 geochemical elements, 14 color coefficients, and total organic carbon. Data processing, using FingerPro, was conducted separately by sub-area and sediment collection. Tracer selection involved a-two sequential statistical tests: 1) Kruskal-Wallis (KW) selects tracers with significant differences between at least two sources and 2) Discriminant Function Analysis (DFA) selects optimal tracers that effectively discriminate between the three sediment sources.

The results obtained demonstrated that the selected tracers for each sub-area varied considerably. For example, the tracer selection procedure for sub-area A1 resulted only in total organic carbon as a viable tracer while the number tracers selected for the other two sub-areas were seven and five, for A2 and A3, respectively. Notably, the varying sets of tracers being selected for each sub-area indicate that the heterogeneity in soil properties is an important consideration in sediment source fingerprinting studies. Combining samples from the whole river basin may distort sediment dynamics. Tailored approaches are crucial for accurate understanding and management.

Acknowledgements

This study was made possible by the generous support of Brazil-CAPES through a doctoral scholarship (Finance Code 001).

References

Lizaga et al. 2020. Consensus ranking as a method to identify non-conservative and dissenting tracers in fingerprinting studies

Lizaga. 2018. fingerPro 1.1.

Owens, P. N. 2022. Sediment source fingerprinting: are we going in the right direction?.

Tiecher et al. 2015. Combining visible-based-color parameters and geochemical tracers to improve sediment source discrimination and apportionment 

How to cite: Araujo, M., Guzmán, G., Gómez, J. A., Koiter, A., Nachtigall, S., and Miguel, P.: Sediment Source Identification in a Southern Brazilian Watershed: Utilizing Geochemical Properties and Spectral Signatures with Mixing Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16690, https://doi.org/10.5194/egusphere-egu24-16690, 2024.

EGU24-16692 | Posters on site | HS9.2

Pre-event conditions and rainfall–runoff characteristics drive suspended sediment source variability 

Núria Martínez-Carreras, Jean François Iffly, and Laurent Pfister

Most of the total sediment load transported in river systems is carried in suspension. Therefore, if we are to reduce soil erosion and sediment export, it is essential to determine suspended sediment sources and the drivers of its mobilisation into the river network. In this study, we combined the monitoring of suspended sediment fluxes and the sediment fingerprinting approach to test if pre-event conditions and rainfall-runoff characteristics drive suspended sediment source variability in catchments under a semi-oceanic climate. The sedimentological response to storm runoff events was studied in seven nested sub-catchments of the Attert River basin (0.4 - 245 km2), which have contrasting geological bedrock (sandstone, marls and shale) and land uses (forest, cropland and grassland). We collected stream water samples during storm runoff events (~30 events per catchment) using automatic water samplers to measure suspended sediment fluxes. In parallel, time-integrated suspended sediment and sediment sources samples (i.e., from different land use types) were collected and analysed in the laboratory (geochemistry, colour and organic properties) to determine the sediment origin using the sediment fingerprinting approach. Each sampled event was parameterized to describe rainfall, runoff, sediment transport and the relative contribution of each land use type to the sampled suspended sediment. Next, we assessed the relationships between variables. We found higher significant correlations between suspended sediment loads and runoff parameters (i.e., peak discharge and event runoff) than between suspended sediment loads and rainfall parameters (i.e., event precipitation, antecedent rainfall, and maximum rainfall intensity). Peak discharge for single events was found to be the best predictor of sediment loads in the studied catchments. We show that most events exhibit clockwise hysteretic loops between discharge and suspended sediment concentration in all studied catchments. We attribute this finding to the erosion or remobilization of sediment previously deposited on the channel bed or an adjacent area. During most of these events with clockwise hysteretic loops, sediment source apportionment presented a consistent pattern.

How to cite: Martínez-Carreras, N., Iffly, J. F., and Pfister, L.: Pre-event conditions and rainfall–runoff characteristics drive suspended sediment source variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16692, https://doi.org/10.5194/egusphere-egu24-16692, 2024.

EGU24-17307 | ECS | Orals | HS9.2

Sediment contribution of shallow landslides and flux connectivity of transfer paths in mountainous areas under climate change projections. A case study for the Saldes River basin (Pyrenees, Spain) 

Stephania Rodriguez, Marcel Hürlimann, Vicente Medina, Ona Torra, Raül Oorthuis, and Càrol Puig Polo

In the context of soil erosion modeling, coarse-grained sediments present considerable challenges, particularly concerning sediment production and quantification. This study proposes a module-based quantification approach that integrates different coarse-grained production processes, where one of the main outputs is the source area delimitation and the quantification of mobilizable sediment.

The present study focuses on analyzing shallow landslides and various scenarios of sediment transport to the nearest fluvial system, by implementing the newly developed “Random Connect” code. This code calculates the accumulated volume that travels from the source areas into the fluvial system based on the connectivity index. The chosen case study is the Saldes River basin in the Pyrenees (Spain) The outlet point of this basin is La Baells water reservoir, presently facing siltation challenges arising from sediment transport across the entire drainage area. Reported by CEDEX (2002), the sediment yield delivered to a La Baells Reservoir from the entire drainage area was 4.54 Mg ha−1yr−1 in 2002. In this sense, this water reservoir is utilized for calibrating and validating our model. The quantification of sediment in water reservoirs does not allow to separate the contributions of the different erosive processes at the basin, thus highlighting the importance of the study of the river section to better understand the sediment production.

For model calibration, field surveys were conducted to ascertain the connectivity index to the main river, identify (dis)connectivity factors, and measure fluvial and sediment grain characteristics. Comparing model output with field data enables determination of sediment transport potential and the maximum sediment quantity that can reach the main river. Depending on the connectivity threshold, the results of sediment reaching the main river for a critical rainfall event can vary between 250000 to 10000 m3.

Assessing sediment at the river cross-section helps in defining the principal coarse-grained production phenomena, such as shallow landslides, rock falls and debris flows. Grain characterization of sediment is necessary to study sediment mobilization through a hydrological-driven module. The main objective is to track coarse-grained sediment until it reaches the water reservoir and identify the meteorological and physical factors that trigger the process.

A historical baseline of sediment production has been determined for the Saldes River basin, based on historical landslide inventories, previous triggering events, and meteorological scenarios for the current climate. The assessment considers the impact of climate change in Spain at different timelines based on return periods. The rate of sediment production is determined by analyzing critical climate change scenarios, resulting in values below and above the baseline. This analysis places special emphasis on extreme climate events and the projection of mean annual precipitation.

How to cite: Rodriguez, S., Hürlimann, M., Medina, V., Torra, O., Oorthuis, R., and Puig Polo, C.: Sediment contribution of shallow landslides and flux connectivity of transfer paths in mountainous areas under climate change projections. A case study for the Saldes River basin (Pyrenees, Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17307, https://doi.org/10.5194/egusphere-egu24-17307, 2024.

EGU24-20102 | ECS | Posters on site | HS9.2

Deglaciation and debris flow dynamics: how does the glacier retreat affect debris flow activity in High Mountain Asia?  

Varvara Bazilova, Leon Duurkoop, Jacob Hirschberg, Tjalling de Haas, and Walter Immerzeel

Debris flows are fast-moving masses of rock, soil, and water, which occur in mountain areas all over the world. Debris flows achieve maximum discharges that are many times greater than those associated with floods and are therefore often hazardous to people and infrastructure. Contrary to the general expectations that climate change will increase the magnitude and frequency of the debris flows, recent assessments have shown that under certain conditions future climate may increase the sediment transport capacity, but could also favor a reduction of the sediment supply and, therefore, reduce debris-flow activity.  The impact of glacier retreat together with future climate conditions on debris-flow catchments is not yet fully understood, but it is expected to increase due to uncovered glacial till, increased hillslope instabilities and an increase in peak rainfall intensities. We aim to quantify the effect of the changes in water availability (changes in precipitation regime, but also glacier meltwater) together with the subsequent landscape changes in climatically contrasting catchments in High Mountain Asia (HMA) on the frequency and magnitude of debris flows. We address it by further extending the sediment cascade model (SedCas), expanding the available hydrological response units to bedrock, vegetated and glaciated parts of the catchment. We further investigate (1) how sediment yield and debris flow magnitude-frequency change over time, and (2) how deglaciation and catchment greening (changes of land cover) affect debris flow activity for different climate regions across High Mountain Asia. We find that in the case study of sediment-unlimited catchments, from 1950 to 2022, glacier retreat increases the water supply. That, in combination with the warming temperatures (and therefore the change in the partitioning of the solid and liquid precipitation) and the decrease in number of extreme precipitation events, results in a decrease in the debris-flow activity. These preliminary results show that changes are not consistent across HMA and highly depend on the climatic regime and elevation. Our findings shed light on the debris flow and flood hazard in the data-scarce areas of HMA and highlight the importance of considering regional climate conditions for hazard assessment in addition to region-wide estimation of glacier retreat. The future development will investigate the sediment-limited conditions. 



How to cite: Bazilova, V., Duurkoop, L., Hirschberg, J., de Haas, T., and Immerzeel, W.: Deglaciation and debris flow dynamics: how does the glacier retreat affect debris flow activity in High Mountain Asia? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20102, https://doi.org/10.5194/egusphere-egu24-20102, 2024.

EGU24-20399 | Orals | HS9.2

Accumulation of water and sediments upstream of Tuscan check dams 

Federico Preti, Sara Pini, Giorgio Cassiani, Andrea Dani, Yamuna Giambastiani, Luca Peruzzo, and Luigi Piemontese

Faced with a decline in water resources due to precipitation reduction and variability, it is fundamental to identify potential natural "reservoirs" and quantify their water retention capacity. This study examined approaches to estimate the water content rapidly and systematically in the sediment upstream of check dams at different scales, even with limited input data.

The study was conducted in the northern part of Tuscany, with a specific focus on the Casentino Valley. After gathering the necessary databases and information, an estimation model was developed using QGIS Model Designer, and geophysical surveys were performed using Electrical Resistivity Tomography (ERT).

The QGIS-based model relies on limited input data, including the geographical positioning of weirs, the hydrographic network, and a Digital Terrain Model (DTM) of the study area. This method provides useful initial approximate estimates of the water resources in the study area. The ERT surveys revealed varying patterns depending on the lithology of different areas, but a clear discontinuity between the sediment wedge and the original riverbed was observed, confirming the effectiveness of this tool in analyzing each individual structure. With the data obtained through the databases, it was also possible to conduct an analysis on the relationship between the original slope and the compensation slope of sediment wedges, and the distance between check dams located on the same river reach.

In the perspective of utilizing these natural reservoirs, possible maintenance interventions are proposed, especially on the existing spillways, to make a portion of the available water usable, accompanied by an assessment of potential implications. In the future, implementing the outlined procedures and integrating them with other tools could provide support for evaluating and utilizing these "hidden water resources."

How to cite: Preti, F., Pini, S., Cassiani, G., Dani, A., Giambastiani, Y., Peruzzo, L., and Piemontese, L.: Accumulation of water and sediments upstream of Tuscan check dams, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20399, https://doi.org/10.5194/egusphere-egu24-20399, 2024.

EGU24-20482 | Posters on site | HS9.2

Advancing sediment fingerprinting techniques: The importance of considering sediment mixtures data in tracer selection 

Leticia Gaspar, Borja Latorre, Ivan Lizaga, and Ana Navas

Sediment fingerprinting has become a key tool to identify and quantify sediment sources within a catchment. The technique involves statistical testing of a range of properties of source materials to identify a set of tracers that can effectively discriminate between different potential sources before estimating the source contributions with unmixing models. However, despite its increasing popularity among researchers, there is a lack of standardized procedures for tracer selection, which is crucial to estimating a reliable contribution of sediment sources. The most widespread methodology consisted of an initial mass conservation test, usually termed range test (RT), followed by the use of Kruskal-Wallis (KW) and discriminant function analysis (DFA) tests. However, KW and DFA even though identifies the best combination of tracers that provide the maximum discrimination between sources, do not incorporate the information of the sediment mixtures in the analysis. Novel methods highlight the importance of selecting the right tracers for each individual mixture and avoid the inclusion of tracers out of consensus or with non-conservative behavior by using consensus ranking (CR) and consistent tracer selection (CTS) methods. This contribution addresses the role of selecting appropriate tracers, demonstrating their impact on the results of the unmixing model. The main objectives are to emphasize the importance of considering the information provided by the sediment mixture in the selection of tracers and to pay attention to the impact of having sediment mixtures with values below the detection limit of the tracer being selected for source discrimination. A set of experimental and real sediment mixtures were selected to explore the different tracer selection methods, comparing the tracers selected and the contribution of sources obtained using the FingerPro unmixing model. We present the results of rigorously testing methodologies with the aim of understanding and assessing the suitability of each tracer selection method to select a combination of statistical and process-based criteria to select appropriate sediment properties for the unmixing models. Our findings highlight the importance of considering the information on the sediment mixture information for the selection of potential tracers, an aspect often neglected by conventional methods. This oversight can result in biased findings due to the use of tracers that are either not coherent or not conservative.

How to cite: Gaspar, L., Latorre, B., Lizaga, I., and Navas, A.: Advancing sediment fingerprinting techniques: The importance of considering sediment mixtures data in tracer selection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20482, https://doi.org/10.5194/egusphere-egu24-20482, 2024.

EGU24-21734 | Orals | HS9.2

Measures to mitigate torrential hazards in a typical alpine catchment area in Slovenia 

Jost Sodnik, Matjaž Mikoš, and Nejc Bezak

Various sediment-related disasters such as flash floods, debris flows and landslides can occur in an alpine torrential catchment area. To protect infrastructure and human life, various structural and non-structural (grey, green and hybrid infrastructure) protection measures can be used to mitigate torrential risks. An overview is given of the protective measures constructed near the Krvavec ski resort in north-western Slovenia (Central Europe). In May 2018, an extreme debris flood occurred in this area, causing considerable economic damage. After the event in May 2018, various field investigations (e.g. geological and topographical surveys) and modeling applications (e.g. hydrological modeling, debris flow) were carried out to prepare the necessary input data for the design of protective measures against such disasters in the future — due to climate change, further disasters are expected in this torrential catchment area. Compensatory measures include the engineering works of local streams, the construction of a large silt check dam for sediment retention, the construction of several smaller retention dams and the construction of 16 flexible net barriers with an estimated retention volume of ~8000 m3 to control erosion. A comprehensive monitoring system was also set up in the study area to observe and monitor potential future extreme events. This monitoring system includes measurements of corrosion of flexible nets, estimation of concrete abrasion on retention dams, regular geodetic surveys with small drones (UAV) and hydro-meteorological measurements with rain gauges and water level sensors. The recent extreme floods of August 2023 also hit this part of Slovenia, and this combination of technical countermeasures withstood the event and prevented large amounts of coarse debris from being transported to the downstream section and destroying infrastructure, as was the case in a less extreme event in May 2018. Therefore, such mitigation measures can also be used in other torrential catchment areas in the alpine environment.

How to cite: Sodnik, J., Mikoš, M., and Bezak, N.: Measures to mitigate torrential hazards in a typical alpine catchment area in Slovenia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21734, https://doi.org/10.5194/egusphere-egu24-21734, 2024.

SSS3 – Soil as Records in Time and Space

EGU24-1649 | ECS | PICO | GM7.3

Dunes on the north-eastern Tibetan Plateau as influenced by climate change: a remote sensing study of the past 5 decades  

Lukas Dörwald, Frank Lehmkuhl, Janek Walk, Xiaoping Yang, Deguo Zhang, Andreas Baas, Lucie Delobel, Bruno Boemke, and Georg Stauch

Dunes react quickly to climatic changes, with the main drivers being the dominating wind regime (e.g. magnitude and direction), precipitation, and temperature. Further, human impact can alter dune movement by fixation of active dunes through greening projects, or reactivation of stationary ones through overgrazing by animals. The north-eastern Tibetan Plateau shows a high variability of climatic parameters like wind, temperature, and precipitation within a high elevation environment, situated between the mid-latitude westerlies and the East Asian Summer monsoon. The presented studies asses active barchan dunes in different climatic settings, from the arid southern margins of the Badain Jaran Desert, to the humid Zoige Basin.

Since climate stations on the Tibetan Plateau are rare and their measurements often cover only a short time span, climatic changes were studied from ERA-5 reanalysis data, dating back to the 1950s. These metrics were processed via cloud computing, using Google Earth Engine, and were then compared to dune migration rates, which were deduced from optical satellite imagery. Here, the CORONA KH-4B images from the late 1960s, the Landsat archives, and up-to-date high resolution data (GeoEye and WorldView) were used. The Normalized Difference Vegetation Index (NDVI) was implemented to observe changes in vegetation. As a newly tested metric, dune field density changes were calculated, in order to investigate dynamics of dense dune field setting.

Over 500 dunes were mapped and analyzed in total within four focus-areas for comparative purposes. The results highlight a wide range of different behavioral patterns of dunes within the environment of the north-eastern Tibetan Plateau. This showcases how dunes can be influenced by and linked to climatic changes.

How to cite: Dörwald, L., Lehmkuhl, F., Walk, J., Yang, X., Zhang, D., Baas, A., Delobel, L., Boemke, B., and Stauch, G.: Dunes on the north-eastern Tibetan Plateau as influenced by climate change: a remote sensing study of the past 5 decades , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1649, https://doi.org/10.5194/egusphere-egu24-1649, 2024.

EGU24-1752 | PICO | GM7.3

A conceptual model for alluvial fan formation and development  

Frank Lehmkuhl and Lewis A. Owen

The development of alluvial fans is sensitive to environmental change and, thus, alluvial fans provide essential archives for reconstructing Quaternary paleoenvironmental conditions, particular climate, hydrology, and tectonics. Although alluvial fans have been studied across the globe for over a century, there is no unifying scheme/framework or model to consider their complete variety and mode of formation. By reviewing the global spatial and temporal range of alluvial fan types and data from selected key dryland regions, we are able to develop a conceptual scheme/framework for their geomorphology and formation, and thus aid in their application for Quaternary climate and environmental change studies. This approach suggests that there are three main regimes for alluvial fan geomorphology and formation: Type I) microscale mountain alluvial fans, small in size and extent (radius < a few 100 m); Type II) mesoscale (radius

How to cite: Lehmkuhl, F. and Owen, L. A.: A conceptual model for alluvial fan formation and development , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1752, https://doi.org/10.5194/egusphere-egu24-1752, 2024.

EGU24-2355 | PICO | GM7.3

Monitoring and simulating dryland soil salinization and assessing the impact of climate change and global warming on soil salinity processes over the past three decades in the Bajestan playa (NE Iran) 

Azra Khosravichenar, Mehdi Aalijahan, Saeedreza Moazeni-Noghondar, Anthony R. Lupo, Alireza Karimi, Mathias Ulrich, Naser Parvian, Aboozar Sadeghi, and Hans von Suchodoletz

Dryland soil salinization strongly affects soil properties, with severe consequences for regional ecology, agriculture and the aeolian dust dynamics. Given its climate-sensitivity it forms a serious environmental hazard, and to cope with this challenge during current global warming it needs to be better understood.

The Bajestan Playa, located in the heavily salinization-affected drylands of Iran, is home to several protected areas and serves as a crucial source of regional dust emissions. Consequently, soil salinization in this region affects both local ecosystems and societies but was not systematically studied yet.

Using an unprecedented comprehensive approach, we systematically monitored regional soil salinity from 1992 to 2021 through a combination of remote sensing, on-site field measurements, and laboratory analyses. We linked these data with regional and global climatic information to achieve three main objectives: (i) understanding the spatio-temporal dynamics of soil salinity, (ii) assessing the impact of regional and global climate changes on salinization processes, and (iii) exploring the potential applications of our approach for future soil salinity studies.

Our high-resolution annual data over three decades have provided significantly deeper insights into soil salinization dynamics. Furthermore, this pioneering, multidisciplinary research showcases substantial potential for future applications in other salinity-affected drylands forming a foundational knowledge base to address the consequences of ongoing global climate change.

How to cite: Khosravichenar, A., Aalijahan, M., Moazeni-Noghondar, S., R. Lupo, A., Karimi, A., Ulrich, M., Parvian, N., Sadeghi, A., and von Suchodoletz, H.: Monitoring and simulating dryland soil salinization and assessing the impact of climate change and global warming on soil salinity processes over the past three decades in the Bajestan playa (NE Iran), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2355, https://doi.org/10.5194/egusphere-egu24-2355, 2024.

The lower fourth member of the Paleogene Shahejie Formation (Es4L) in Bonan sag, Bohai Bay Basin, East China was taken as an important target for oil and gas exploration in Shengli oilfield. Bonan sag is one of several sag in the Bohai Bay Basin, located in north-east China. Paleogene deposits are characterized by red rock layers, formed under a hot-warm and arid climate. Four depositional systems were developed in the Bonan sag. Among them, the fan delta developed in the central part of the study area, consisting of gray-white fine glutenite with poor sorting and rounding. The braided river delta is developed in the southern part with large lithofacies. The lithology shows some light gray conglomerate, pebbly sandstone, sandstone and small amount of mudstone. Floodplain facies is mainly developed in the inundated plain that in some weather conditions have the characteristics of shallow lake facies. However, a number of questions remain unanswered about the disparate presence of evaporites, the diverse colors of the mudstones and the varying levels of total organic carbon (TOC) in the area. These disparities can be seen in the many oscillations in TOC content, from the source of the sediments in the upper relief to the flood lacustrine plain. Consequently, given to this conditions, the depositional system which occurs in the area remains unclear from previous works. However, looking at the distribution of the sediments in an apparently short distance of less than 50km from the south to the North of sag, suggests that they are more likely to be terminal fan deposits. Terminal fans are an architectural system for draining and depositional process from high relief to flood plain, with gradual discharge of water through infiltration and evaporation. Although some researchers have conducted studies on terminal fans around the world, the concept remains unfamiliar and deserves to be more elucidated. This approach postulates to be useful to better understanding the sedimentary deposits in the Bonan sag and must be reviewed for similar hydrocarbon explorations elsewhere.

How to cite: Mioumnde, A. P., Zhang, L., and Yan, Y.: Paleoenvironment and Depositional Analysis of a Paleogene Formation: Terminal Fan Sedimentation Approach for Reservoir Quality Study in the Lower Shahejie Fourth Member, Bonan sag, China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2604, https://doi.org/10.5194/egusphere-egu24-2604, 2024.

 In view of the problem that the Cretaceous favorable sedimentary facies belt in Kedong structural belt in the southwest depression of the Tarim Basin is not clear, in order to reduce the uncertainty of the research on the spatial and temporal distribution of source sink sedimentary systems in low drilling density areas, the applicability of sedimentary forward modeling in the Tarim Basin is explored. Based on existing geochemical data, statistical analysis of trace elements and rare earth elements is conducted to explore the ancient sedimentary environment during the sedimentation process of the Cretaceous Kizilsu Group, which is a prerequisite for conducting sedimentary forward modeling. By comprehensively utilizing drilling, seismic and other data, combined with previous research results, DionisosFlow sedimentary forward simulation software is applied to clarify the development characteristics of sedimentary systems. The results show that based on different element abundances, ratios, and sedimentary markers, the study of ancient sedimentary environments shows that the ancient climate is mainly characterized by semi humid, semi dry, and dry hot climate conditions; During the sedimentation period of the Kizilsu Group, the overall water depth was relatively shallow, and the ancient redox environment was a shallow underwater oxidation environment. The favorable paleoenvironmental conditions and abundant material sources provide favorable conditions for the development of shallow water delta sedimentary systems. The Kizilsu Group mainly develops braided river delta sediments in the northern gentle slope zone, with front edge sediments as the main type. The southern steep slope zone develops alluvial fans and fan delta sedimentary systems, and the central part develops shoreline shallow lake facies sediments. The western Kunlun Mountains in the south are the main source of material supply, while the Maigaiti ancient uplift in the north is the secondary source of material supply. The ancient uplift during the sedimentation period of the Kizilsu Group has a blocking effect on the delta that flows into the lake, dividing the southern fan delta and lake sedimentary system from the northern braided river delta and lake sedimentary system.

How to cite: Zhang, Y. and Zhang, L.: Application of Sedimentary Forward Simulation in the Kezilesu Group of the Kedong Structural Belt, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2738, https://doi.org/10.5194/egusphere-egu24-2738, 2024.

EGU24-3400 | ECS | PICO | GM7.3

Small endorheic basin sediments along a climatic gradient as paleoenvironmental archives 

Itzhak Raish, Joel Roskin, Shlomy Vainer, and Revital Bookman

 

Understanding and quantifying the natural variability and evolution of past climate systems require the use of datasets that are considerably long, continuous, and of broad spatial coverage. However, common terrestrial proxies, specifically in low- and mid-latitude could be puzzling due to the diversity of climate systems that records a mixed and regionally wide signal that fails to detect the short-term and transitional climate variability. In Holocene records, which are often used to study human-environment interactions, these resolutions are critical.

Here we explore the potency of deposits that are filling endorheic (internally drained) basins of not more than several km2 in size to serve as paleoenvironmental archives. We focus on three sites spread along a steep, ~150 km long climatic gradient in Israel that are influenced by several atmospheric circulation patterns. Core-drilled sediments acquired from such basins have undergone sequential analyses to characterize their textural, geochemical, and luminescence properties. Optically stimulated luminescence (OSL) dating, applied to construct a chronological framework, is coupled with port/pulsed OSL (POSL) analyses, mainly to analyze sedimentation trends and target samples for OSL dating.

The geomorphic and sedimentological responses to environmental perturbations of the late Quaternary are reflected distinctly in each site. Changes in depositional environments that occur throughout all sites often point to similar regional climatic trends, and are partly synchronous with established climatic events.  The compiled interpretation from several sites along a given climatic transect is anticipated to form a robust regional paleoenvironmental framework that can serve a wide range of Quaternary studies.

How to cite: Raish, I., Roskin, J., Vainer, S., and Bookman, R.: Small endorheic basin sediments along a climatic gradient as paleoenvironmental archives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3400, https://doi.org/10.5194/egusphere-egu24-3400, 2024.

EGU24-5535 | ECS | PICO | GM7.3

The formation and development of nebkhas based on chronology and sedimentology in the Ordos Plateau, northern China 

Yue Du, Ruijie Lu, Luo Ma, Dongxue Chen, and Yingna Liu

The Ordos Plateau lies on the northwest margin of the East Asian monsoon region as well as the farming-pastoral ecotone in northern China, with a wide distribution of nebkhas. The formation and development of nebkhas in this region are closely related to natural envi ronmental conditions and human activities. However, the processes of nebkhas formation and development under natural and anthropogenic influence still remain unclear. In this study, four typical nebkhas in the Ordos Plateau were selected after detailed field investigations. Chronology and sedimentary features of the formation and development of nebkhas were studied based on optically stimulated luminescence (OSL) dating, lithology, grain size, etc. The results demonstrated that modern nebkhas had formed since at least ~0.59 ka in the southwest of the Ordos Plateau, followed by the middle region, at least ~0.34 ka, and later in the south and north regions, at least ~0.10 ka. There were thin layers of weakly-developed paleosols at ~0.32-0.25 ka, peaks in the silt and fine sand content and lower deposition rates, about 0.37-0.46 cm/a, indicating a relatively humid climate and weak aeolian activities. After ~0.10 ka, aeolian activities intensified and the nebkhas widely developed with a higher deposition rate, ~0.45-5.21 cm/a. Nebkhas in the study region developed primarily over paleo-channels or paleosol layers. Very fine sand and fine sand were dominant composition on grain size of nebkha sediments; saltation was a main means for the particle movements, indicating near-source accumulation for nebkha sediments. In recent decades, local farmers are used to adding nebkhas deposits to the soil of irrigation areas to improve the soil quality and alleviate soil salinization. Such agricultural activities, together with land reclamation, have accelerated the demise of the nebkhas in the Ordos Plateau.

How to cite: Du, Y., Lu, R., Ma, L., Chen, D., and Liu, Y.: The formation and development of nebkhas based on chronology and sedimentology in the Ordos Plateau, northern China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5535, https://doi.org/10.5194/egusphere-egu24-5535, 2024.

EGU24-5537 | ECS | PICO | GM7.3

Estimation of aeolian sediment volume in the middle reaches of the Yarlung Zangbo River based on GPR and LiDAR 

Jianyu Ling, Rongyi Qian, Xu Liu, Zhibo Huang, Ding Wang, Ketong Hu, and Jinhang Zhang

Sand control is one of the most important components of environmental protection. In the middle reaches of the Yarlung Zangbo River, the phenomenon of desertification is becoming serious, which has a great impact on the local ecological environment protection and economic development. The accurate estimation of the volume of aeolian sediment is of great significance to the formulation of the treatment plan. However, most of the existing studies are based on remote sensing interpretation to estimate the area of aeolian sediment, and the research on the volume of aeolian sediment is relatively weak. To make up for this research gap and provide reliable basic information for sand control in the middle reaches of the Yarlung Zangbo River, we carried out research on estimation of aeolian sediment volume based on GPR and LiDAR. The experimental area of this study is located in Zhanang County in the middle reaches of the Yarlung Zangbo River, with an area of approximately 1.8 km2. We set up six GPR survey lines in the experimental area and obtained the bottom interface and corresponding average elevation of aeolian sediment. Subsequently, high-precision surface elevation of the study area was obtained by LiDAR, and the average surface elevation was calculated. Then we obtained the average thickness of the aeolian sediment is 3.25 m by subtraction of the average surface elevation and the elevation of the aeolian sediment bottom interface. Finally, we determined that the volume of aeolian sediment in the experimental area was about 5,850,000 m3. Our study has realized the volume estimation of typical aeolian sediment area in the middle reaches of Yarlung Zangbo River, which has important guiding significance for sand control.

How to cite: Ling, J., Qian, R., Liu, X., Huang, Z., Wang, D., Hu, K., and Zhang, J.: Estimation of aeolian sediment volume in the middle reaches of the Yarlung Zangbo River based on GPR and LiDAR, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5537, https://doi.org/10.5194/egusphere-egu24-5537, 2024.

Climate change continues to impact diverse ecosystems. Drylands stand out as particularly vulnerable environments, as they are highly responsive to key indicators of change. The sensitivity and response time of these regions remain largely unknown, underscoring the need for a deeper understanding of their systems.

Arid regions are considered optimal for Earth Observation based research, primarily due to factors such as minimal anthropogenic disturbance, sparse vegetation cover, and low cloud coverage. These attributes make drylands advantageous for studying and monitoring the impact of climate change, providing valuable insights into these vulnerable ecosystems.

Southern Mongolia stands out as an especially well-suited study area to test novel approaches and to detect land surface changes over both space and time. The basin of Orog Nuur was selected in this study to observe long-term environmental changes, building on significant prior studies conducted around the drainage basin.

Our approach emphasizes the utilization of state-of-the-art earth observation technology to unveil the dynamics of desert ecosystems. This involves cloud-based processing, such as Google Earth Engine and the German High Performance Data Analytics (HPDA) platform “terrabyte”. Throughout the project, we will apply various multispectral and active SAR techniques spanning 50 years to monitor geomorphological processes, ecosystem changes and ongoing surface dynamics linked to climate change indicators. Some of important pillars of the long-term time series analysis can be listed as greening and precipitation events, lake level dynamics, dune movement rates, mapping of sedimentological, geomorphological provinces and aeolian coverage, in order to understand frequency-magnitude relationships.

The findings will be supported by a series of fieldworks covered by UAS campaigns and auxiliary ground-truth sensors, ensuring the accuracy of our estimations by in-situ measurements. Based on the derived surface characteristics, various ecosystems will be defined, and a high-level ecosystem integrity model will be developed. Ultimately, our model aims to represent the intactness, functioning and structure of the different ecosystems within arid regions. Additionally, due to our high temporal study concept, the model will serve as the base for quantifiable measurements of the responsiveness and adaptiveness of the ecosystems.

Having a model for ecosystem intactness not only help to preserve fragile ecosystems but also strengthens the resilience and adaptive capacity of communities. Furthermore, the transferability of our framework to other drylands may also lead to a comprehensive understanding of the arid characteristics.

Keywords: Earth Observation, arid regions, dryland, remote sensing, climate change, impact, geomorphological process, ecological modelling, land surface dynamics

How to cite: Arisoy, B., Ullmann, T., and Stauch, G.: Desert Sensing – Characterizing recent surface dynamics in arid regions through high-performance data analytics of multi-sensor Earth Observation archives and in situ records, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10337, https://doi.org/10.5194/egusphere-egu24-10337, 2024.

Mineral dust aerosol particles are tiny soil particles mobilized and entrained into the atmosphere by wind. Suspended in the atmosphere and transported away from source regions by prevailing wind systems, dust aerosol alters the Earth’s radiation budget, stimulates cloud and precipitation formation processes, and modulates the carbon cycle as it may enhance bio-productivity due to its mineralogical composition. In the light of the manifold dust feedbacks with relevance to the climate, knowledge on the atmospheric pathway of dust from source to sink is essential for accurate climate simulations. Thereby, the spatio-temporal variability of dust source activity, and consequent dust production and entrainment into the atmosphere is of particular interest as dust emission marks the beginning of the atmospheric dust cycle. Although crucial for the understanding of the climate system, detailed knowledge on the interannual variability of dust source characteristics (i.e., emissivity and their susceptibility to wind erosion) and activity (i.e., occurrence frequency of dust emission events and emission fluxes) is still somewhat limited. In particular the impact of changing environmental conditions on dust sources and their emission variability is not fully understood yet and requires further research. This is also of importance in order to assess the spatially and temporally changing contribution of dust sources to the local and regional atmospheric dust burden and related dust feedbacks.

This presentation will provide an overview of different dust source types, their key characteristics, and their response to environmental changes due to climate change with regard to emission flux and dust source activity. It will include examples from remote sensing approaches and dust modelling in order to examine the interannual variability in a changing climate.

How to cite: Schepanski, K.: Mineral dust in the climate system: Dust source types and their response to environmental changes in a changing climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11443, https://doi.org/10.5194/egusphere-egu24-11443, 2024.

Aeolian-Fluvial interactions range from aeolian- to fluvial-dominated processes, often resulting in unique morphologies and complex stratigraphies along dunefield margins. In the Northwestern Negev dunefield (Israel) desert, a key factor influencing transitions from aeolian- to fluvial-domination, is the basin size. While medium-sized (40-200 km2) and large (>200 km2) basins were breached before or during the early Holocene, small basins are still dammed by dunes. Often their surficial and buried palaeochannel is comprised of a sequence of remain of dune-dammed water bodies in the form of fossilized playas. Unlike medium and large basins, where incision exposes Aeolian-Fluvial deposits after the dune-dam breaching, small dune-dammed fluvial systems necessitate sampling techniques such as drilling into continuously aggrading Aeolian-Fluvial deposits to reconstruct the stratigraphy and interpret paleoclimate and palaeoenvironmental records. We demonstrate the potential of a SUERC Portable-OSL (port-OSL) for interpreting palaeo-records in small dune-dammed basins.

The Shivta-East basin (3.3 km2) was hand-augered along an ephemeral stream's propagation path into the dunefield, at three disconnected playa-like sediments of seasonal dune-dammed waterbodies. At each dune-dammed waterbody sediments, samples were taken at 15-25 cm intervals and analyzed using the port-OSL reader. Their estimated ages were interpolated according to a calculated regional linear regression based on the northwestern Negev dunefield luminescence age database. This regression, generated by training a data set of thirty-two aeolian sand samples, analyzed for both OSL dating and port-OSL Net counts, accounts for 72% of the age variability, with a standard error of 3.4 ka between the model and the data. Due to the absence of modern-day OSL dated samples, the regression line was reconstructed for the LGM until the early Holocene. The regression model enables dating of the Last Glacial Maximum, Heinrich-1, and Younger Dryas sand incursions, previously described as the main active periods of the aeolian system.

K-means cluster analysis based on the port-OSL signals, reveals three distinct clusters, which points to alternations of the sedimentary units, between sand and fluvial sourced fine-grained sediments. The three clusters are understood to reflect both the mineralogical composition and burial age of the deposits. The overlying cluster mainly consists of fine-grained sediments deposited in the dune-dammed waterbody, while the other two units are sandy deposits.

Interpolation of the sandy samples from all three playas along the palaeochannel in the linear regression demonstrates that during the Heinrich-1 and Younger Dryas events, an aeolian-dominated environment dune-dammed the fluvial system, enabling aeolian sand deposition. Later, coevally with the fluvial system's propagation into the second (middle) dune-dammed waterbody, aeolian domination persisted until the Early Holocene generating the third and upstream dune-dammed waterbody.

This study demonstrates the potential and limitations of the port-OSL reader combined with statistical methods for chrono-stratigraphic analysis of hand-augered samples collected from an altering depositional environment. The ability to rapidly estimated depositional ages and associated palaeoclimatic periods highlights the potential for further exploration of the port-OSL reader in different environmental settings.

How to cite: Greenbaum, N., Robins, L., and Joel, R.: Regional Depositional Age Assessment using Portable-OSL of Hand-Augered Aeolian-Fluvial Deposits along a chain of Small Dune-Dammed Basins in the Northwestern Negev Dunefield Margins, Israel , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12423, https://doi.org/10.5194/egusphere-egu24-12423, 2024.

The Great Central Desert of Iran, located at the center of the Iranian plateau, bears valuable but scattered geological and geomorphological archives. However, the scarcity of data on the paleoenvironment and paleolandscape of this area is attributed to challenging accessibility and harsh climatic conditions. The Khur area in the eastern edge of the Iranian Central desert was selected for this investigation due to its distinctive geomorphological features and improved accessibility.
This study aims to delineate Late Pleistocene-Holocene landscape evolution in central Iran by utilizing sedimentary and morphostratigraphical evidence of aeolian-fluvial sequences. In a first step, geomorphological features were mapped based on satellite imagery, digital elevation models, geological maps and field observations. Subsequently, localities for excavator sections were deduced from these findings, guaranteeing accessibility and further ensuring their incorporation of anticipated stratigraphic key features, including contact zones of distinct geomorphological environments. Stratigraphic description of the excavated profiles was recorded, and sedimentary logs were drawn.
The preliminary results reveal complex interactions of Aeolian, fluvial, and lacustrine morphodynamics during the Late Pleistocene and Holocene. Seven landform groups including aeolian dunes and interdune areas, sandy mud flat, alluvial fans and fluvial plains, dissected fan toe with backward erosional valleys were recognized. Within these, five interfingering sedimentary units were identified based on distinctive geometry and layering and their internal facies distribution: Fluvial flood deposits, well to poorly-sorted alluvial deposits, aeolian sand deposits, fluvially reworked marl (fine-grained mud), paleosol horizons.
In summary, repeatedly changed depositional environments and cyclical climatic changes, where dune development took place during phases of increasing aridity, whereas non-aeolian deposition and paleosol formation might have occurred during more humid conditions and more stable paleosurfaces.
Luminescence dating, sedimentological and geochemical analyses, will determine climatic cycles, sedimentary environments and landscape evolution history.

How to cite: Rashidi Koochi, Z., Büdel, C., Torabi, M., Baumhauer, R., and Fuchs, M.: Towards Late Pleistocen-Holocene stratigraphy and landscape evolution of Khur area, Central IranTowards Late Pleistocen-Holocene stratigraphy and landscape evolution of Khur area, Central Iran, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12653, https://doi.org/10.5194/egusphere-egu24-12653, 2024.

EGU24-13466 | ECS | PICO | GM7.3

Reconstructing timeframes, processes and environmental implications of Late Quaternary aeolian Parna deposition in south-eastern Australia 

Felix Lauer, Samuel Marx, Anthony Dare-Edwards, and Jan-Hendrik May

Sedimentary sequences with major aeolian dust contribution blanket the flat to hilly landscapes of eastern New South Wales. Originally identified by Butler in 1956 within the Riverine Plain and adjoining hills, these widespread clay-rich sediments were termed "Parna”. Parna – which has often been compared to loess – is thought to be fine-grained sediment generated through exogenic processes in arid environments and transported as stable aggregates by prevailing westerly winds during the Quaternary. The primary hypothesized source regions for Parna are arid and semi-arid river and lake systems situated in the western Murray-Darling Basin. Despite the prolonged critical discourse surrounding the concept and terminology of Parna, investigations addressing unresolved questions have been limited, with absolute dating of the aeolian sequences being restricted to only a few sites.

Given the complexity of the Parna sequences resulting from the interaction of aeolian, hillslope and pedological processes, we choose a multimethodological approach combining field observations, grain size analysis, geochronological and geochemical methods to investigate the processes and time frames of sedimentation and sediment provenance. Results of optically stimulated luminescence (OSL) dating for several Parna sites in the Wagga Wagga (Beattie 1972) and Yass region, show age estimates reaching back 150,000 years. Sedimentological parameters are used to distinguish between material derived from local hillslope and aeolian input. Geochemical characteristics will help to trace sources and pathways of the aeolian material. Advancing our understanding of the Parna concept, implying large-scale deposition but also deflation of aeolian material, is one component of reconstructing Quaternary landscape development and environmental conditions in south-eastern Australia.

Butler, B.E., 1956. Parna-an aeolian clay. Australian Journal of Science, 18(5), 145-151.

Beattie, J.A., 1972. Groundsurfaces of the Wagga Wagga Region, New South Wales. C.S.I.R.O Soil. Pub Australia. No. 28.

How to cite: Lauer, F., Marx, S., Dare-Edwards, A., and May, J.-H.: Reconstructing timeframes, processes and environmental implications of Late Quaternary aeolian Parna deposition in south-eastern Australia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13466, https://doi.org/10.5194/egusphere-egu24-13466, 2024.

EGU24-15208 | PICO | GM7.3

Optically stimulated luminescence dating of loess sequences in the Tibetan Plateau and their palaeoenvironmental implications 

Shengli Yang, Li Liu, Qiong Li, Pushuang Li, and Yuanlong Luo

The Tibetan Plateau (TP) is extremely sensitive to climate change. Widely loess deposits distributed in the Tibetan Plateau are important archives for studying the past environmental changes of the Tibetan Plateau. However, little information is understood due to the poorly age constrained of the TP loess. In this study, we use the single-aliquot regenerative dose optically stimulated luminescence (OSL) method, and the post-infrared infrared stimulated luminescence protocol (pIRIR) to date the well-preserved loess–paleosol sequences in the eastern TP and discuss the applicability and reliability of OSL dating of the TP loess for establishing a reliable numerical age framework. We found that quartz OSL signal of TP loess is dominated by fast component, and the equivalent dose can be measured by SAR method. The growth curve shapes and saturation dose shows that the quartz OSL signal in this region saturated at ~200~230 Gy. The prior-IR stimulation plateau test, dose recovery, recycling ratio and recuperation indicated that pIR200IR290 could be used for the equivalent dose estimation of potassium feldspar. Our results contribute to an improved understanding of the TP dust history and paleoenvironmental changes in the Last Glacial cycles.

How to cite: Yang, S., Liu, L., Li, Q., Li, P., and Luo, Y.: Optically stimulated luminescence dating of loess sequences in the Tibetan Plateau and their palaeoenvironmental implications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15208, https://doi.org/10.5194/egusphere-egu24-15208, 2024.

EGU24-21074 | PICO | GM7.3

Holocene linear dune accumulation in the western Thar desert, India.  

Shashank Nitundil, Abi Stone, Aayush Srivastava, and Komal Songara

The densely populated Thar Desert in the northwestern part of the Indian subcontinent contains a complex spatial pattern of now vegetated dune morphologies. There is a growing dataset of luminescence ages that demonstrates a dominance of Holocene dune dynamics in the preserved record (e.g., Srivastava et al, 2020; Parida et al., 2023; Nitundil et al., 2023). This region is undergoing rapid change in recent decades with widespread flattening of dunes for agricultural land, which is fed by the Indira Gandhi Canal that provides water for irrigation.

 

Our work has developed a training set of >40 samples with published luminescence ages to create a calibration approach for the signals measured using portable luminescence readers (POSL) (Nitundil et al., 2023). Other POSL signal characteristics, such as IRSL:BSL ratios are a good indicator that the Thar sands have a broadly common sedimentary provenance, as well as transport processes and post-depositional histories of mineral weathering. During this work, a rigorous exploration of sediment properties, including moisture content and presence of carbonate was undertaken, and from this, guiding principles for building a calibration curve were developed.

 

Vegetated linear dunes have been sampled in five regions along a ~75 km north-south transect in the western Thar. The POSL calibration has been applied to determine estimated ages for three dunes at the second most northerly site, to shallow depths (2 m) (Nitundil et al., 2023), and from multiple profiles within two dunes at each of three other sites along the transect (a further 19 shallow, 2 m profiles). Fieldwork in September 2023 focussed on obtaining close to full dune vertical profiles via auguring (~10 m depth) from three sites, as well as exploring dynamics across and along a dune using ~0.8 m hand dug pits. This presentation will highlight key findings from the calibration exercise, and present POSL-based ages estimates across the western Thar to explore what they reveal about Holocene dune accumulation in this region. 

 

References

Nitundil, S., et al. (2023) Applicability of using portable luminescence reader for rapid age-assessments of dune accumulation in the Thar desert, India. Quat. Geochron. 78, 101468.

Parida, S. et al. (2023) Luminescence Dating of Dunes in the Western Thar Desert:  New Data and Regional Synthesis. XXI INQUA Congress, 14-20th July 2023, Rome, Italy.

Srivastava, A., et al. (2020) Holocene palaeoenvironmental changes in the Thar Desert: An integrated assessment incorporating new insights from aeolian systems. Quat. Sci. Rev. 233, 106214.

 

How to cite: Nitundil, S., Stone, A., Srivastava, A., and Songara, K.: Holocene linear dune accumulation in the western Thar desert, India. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21074, https://doi.org/10.5194/egusphere-egu24-21074, 2024.

EGU24-21086 | PICO | GM7.3

S.A.N.D.S. - Surface Archaeology on the Namib Desert Surface.  

Abi Stone, Dominic Stratford, Ted Marks, Rachel Bynoe, Kaarina Efraim, Eugene Marais, Rachel Smedley, and George Leader

The hyper-arid Namib Sand Sea (NSS) represents a significant challenge to human occupation, yet, despite these challenges, Early Stone Age (ESA) and Middle Stone Age (MSA) tools are found across this landscape. Whilst surface scatters are hindered by a lack of clear stratigraphy, they provide a spatially integrated record of the structuring of landscape use through time and relationships to sources of raw material and water. Omitting such sites leads to bias in our interpretations of early hominin distribution. We are investigating how and why early hominins were moving into the northern NSS, starting with two interdune pan sites: Namib IV (Leader et al., 2023) and Narabeb. Here we set out the context of these archaeological sites, the stratigraphies observed and our emerging luminescence chronologies for the sedimentary sequences.

 

To establish the palaeoenvironmental context of the lithics (both ESA and MSA) and fossil fauna at Namib IV we dug a series of test pits to explore the sedimentological record. The Namib IV surface has a complex meso-topography with a spatially-patchy, resistant calcareous surface unit, and our test pits reveal a similarly complex sedimentary record across space. This includes the preserved remnant of an aeolian slip face, and elsewhere a number of horizontally bedded units beneath surface calcareous layers. 13 samples from Namib IV were selected for luminescence dating, using pIRIRSL feldspar methods, anticipating ages close to quartz saturation (e.g. Stone et al. (2010) in this region). Narabeb contains predominantly MSA lithics. North (~2 km) of the artifact collection area is a prominent ‘ledge’ of interbedded muds and sands, previously dated using quartz OSL (Stone et al., 2010). We dug two small geotrenches associated with surface calcareous exposures, taking samples for pIRIRSL dating along with two sampling points in the lower unconsolidated dune flank. We also date a sample from the Stone et al. (2010) sequence using pIRIRSL (K fieldspar) to revise the saturated quartz luminescence age estimate.

 

References

Leader, G.M., Bynoe, R., Marks, T., Stone, A., Efraim, K., Stratford, D., Marais, E. (2023) Revisiting the Acheulean at Namib IV in the Namib Desert, Namibia. Journal of Field Archaeology 48(5), 380-394.

Stone, A., Thomas, D.S.G., Viles, H.A. (2010) Late Quaternary palaeohydrological changes in the northern Namib Sand Sea: new chronologies using OSL dating of interdigitated aeolian and water-lain interdune deposits. Palaeogeography, Palaeoclimatology, Palaeoecology 288 (1-4), 35-53.

How to cite: Stone, A., Stratford, D., Marks, T., Bynoe, R., Efraim, K., Marais, E., Smedley, R., and Leader, G.: S.A.N.D.S. - Surface Archaeology on the Namib Desert Surface. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21086, https://doi.org/10.5194/egusphere-egu24-21086, 2024.

Suspended sediment load in rivers has a crucial impact on the river water quality, soil erosion, irrigation activities, and dam or reservoir operations. Dam construction in a river reduces the runoff, which increases the deposition of suspended sediment on the river course and ultimately leads to a change in the river channel morphology. Thus, suspended sediment load prediction is significant for planning and sustainable management of the riverine ecosystem. Researchers have used various physical models, such as sediment rating curves (SRC), SWAT, HEC-RAS, HEC-HMS, etc., for predicting suspended sediment load. Recently, researchers have used machine learning models to predict suspended sediment load in different hydroclimatic regions worldwide. In this study, we used five different machine learning models, such as ElasticNetCV, Multi‑Layer Perceptron (MLP) Regressor, Extreme Gradient Boosting (XGB) Regressor, Light Gradient-Boosting Machine (LGBM) Regressor and Linear Regression (LR), for predicting suspended sediment load in a downstream station of Godavari River Basin (GRB). The GRB is the largest Indian peninsular river basin, covering more than 0.3 million square kilometers of area. We used the 'Lazy Predict' Python library to achieve better results for machine-learning modeling. The data was collected for the period of 1970–2018 and divided into two parts, viz. pre-1990 and post-1990, to consider the dam effects on the downstream regions of the GRB. Performance evaluation revealed that the Multi‑Layer Perceptron (MLP) Regressor performed very significantly, with an r-square value of 0.71 and 0.74, respectively, for pre-1990 and post-1990. The developed models offer a valuable resource for decision-makers, environmental scientists, and water resource managers seeking to proactively manage sediment-related issues in river systems, ultimately fostering sustainable water quality and ecosystem health.

How to cite: Kundu, S., Swarnkar, S., and Agarwal, A.: Application of Machine-Learning Based Models for Prediction of Suspended Sediment Load in the Indian Peninsular River Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1117, https://doi.org/10.5194/egusphere-egu24-1117, 2024.

EGU24-1900 | Orals | GM5.3 | Highlight

Large Scale Modification of the Salton Sea Shoreline to Reduce the Potential for Dust Emissions 

John Gillies, Eden Furtak-Cole, and George Nikolich

The Salton Sea in California’s Imperial and Riverside counties is a large endorheic lake with significant areas of exposed shoreline.  The exposed shoreline and surrounding desert are potential sources of wind-blown dust that can contribute to degraded air quality as the emissions create high concentrations of particulate matter ≤10 µm in aerodynamic diameter (i.e., PM10), which is a federally regulated pollutant in the USA.  The Salton Sea’s water surface height is lowering at an accelerating rate.  The decreasing volume of water leads to increased shoreline exposure with the potential for high wind speed events to cause dust emissions. This increases the potential for degradation of air quality with respect to PM10 mass concentrations within the basin potentially elevating the health risk to the surrounding population.  The State of California has implemented the Salton Sea Management Plan that has several phases of development to protect air quality and ecosystem values at the Salton Sea.  California Department of Water Resources (DWR) began a series of projects at the Salton Sea designed to limit dust emissions from shoreline areas deemed vulnerable to wind erosion and dust emissions based on evaluation of soil textural properties and in situ measurements of PM10 emissivity.  To protect sandy surfaces vulnerable to wind erosion, surface roughening based on the super-positioning of non-erodible roughness elements onto the exposed sediments of the shoreline has been implemented.  The non-erodible elements are bales of straw sourced from agricultural producers in the vicinity.  They are rectangular prisms of dimensions 0.41 m high, 1.12 m long, and 0.55 m wide. 

To evaluate the effectiveness of the roughness arrays, designed initially to offer 95% reduction in sand transport and dust emissions compared to the unprotected surface, computational fluid dynamics modeling was carried out to quantify the reduction in surface shear stress and dust emission potential due to the presence of the roughness.  In addition, in situ measurements of sand flux and PM10 concentrations were collected to corroborate the simulation results.  Air flow across the roughness array for three freestream wind speeds and three wind direction angles was simulated using CFD in OpenFOAM.  The mean shear stress reduction compared to the surface without roughness for the three freestream wind speeds and wind directions was 62% (±1%), 66% (±0.2%), and 79% (±1%), for 225°, 270°, and 315° wind directions, respectively.  The greatest probability for high wind speed events is expected from the wind direction range 225° to 315°. The mean reduction in total PM10 emission for these three conditions were: 73% (±4%), 85% (±2%), and 80% (±2%).  In situ measurements suggest control effectiveness is even greater as saltation has not been recorded within the roughness for the range of observed wind speed, and there is no indication that PM10 has been emitted from the protected surfaces.  This suggests that large size superposed roughness has effectively modified the dust emission potential of these susceptible surfaces and provides the protection needed to ensure that the exposed shoreline does not contribute to the regional PM10 burden.

How to cite: Gillies, J., Furtak-Cole, E., and Nikolich, G.: Large Scale Modification of the Salton Sea Shoreline to Reduce the Potential for Dust Emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1900, https://doi.org/10.5194/egusphere-egu24-1900, 2024.

Sand mining has accelerated in recent years primarily due to population increase and rapid urbanization. To meet demand, the rate of sand extraction often exceeds the rate of natural replenishment with serious environmental consequences. In this review paper, the Vietnamese Mekong Delta (VMD), a global hotspot for sand mining with a prolonged history of intensive riverbed extraction, is used as a representative case study to highlight the extent and compounded impacts of this activity. Sand mining budgets from literature present significant discrepancies, with estimates for the entire delta varying from around 8.5 to 42.2 Mm3/yr. These variances can be attributed to the challenges in the actual measurement of mining rates and the deployment of disparate methods across studies. Moreover, the widespread practice of illegal sand mining in the region further exacerbates the mismatch in budget calculations. Consequences of such mining activities manifest as deeply-incised riverbeds leading to riverbank and coastal erosion. Moreover, the massive sediment removal has resulted in river water level reductions, disrupted hydrological connectivity, and diminished floodplain inundation. The augmented backwater effect, a result of riverbed lowering, amplifies saltwater intrusion in dry seasons. While the physical and hydrological impacts have received attention, studies on the ecological and societal ramifications remain sparse. These impacts, further magnified by factors like upstream dams, irrigation infrastructures, excessive groundwater extraction, and sea-level rise (SLR), present a multifaceted challenge. This paper concludes by advocating for the adoption of remote sensing-based approaches for effective mapping of sand mining activities, and implementation of sustainable sand harvesting practices to balance developmental needs with environmental conservation.

How to cite: Park, E.: Sand mining in the Mekong Delta: Extent and compounded impacts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2678, https://doi.org/10.5194/egusphere-egu24-2678, 2024.

EGU24-4096 | ECS | Orals | GM5.3

Assessing river corridor changes after anthropogenic vegetation removal: an object-based mapping approach 

Katarina Pavlek, Mateo Gašparović, and Ronald E. Poeppl

The development of remote sensing technologies and image classification methods has facilitated research on changes in river channels and floodplains by automating mapping of land cover and geomorphic units. In often highly heterogeneous river environments, object-based approaches proved sensible, since they are based on objects produced by image segmentation rather than on individual pixels.

This study uses object-based image analysis to investigate land cover and river channel dynamics in the managed corridor of the Orljava River in the Pannonian basin (Croatia). In the last decade, the river has been affected by anthropogenic removal of riparian vegetation to increase channel capacity, which was followed by a big flood event. Five river corridor classes (water, bare soil, sparse vegetation, dense vegetation, and shadows) were classified based on RGB and near-infrared (NIR) aerial images in the period 2011-2021. A digital surface model generated from the images was used to separate bare river channel units (“river sediments”) from bare soil in the floodplain and to define high vegetation, while agricultural land was classified manually. The accuracy of the produced maps was between 85 and 93%, except for the year 2014 which lacked the NIR band. Based on classified river corridor units, changes in channel morphology were further analysed in GIS. The two main phases of river corridor changes were caused by the occurrence of a big flood in 2014. In 2011-2014, immediately after the flood, a significant increase in the area of water and river sediments was recorded, mostly at the expense of bare riverbanks and adjacent agricultural land. Large in-channel bars have formed due to sediment accumulation, as well as significant channel migration has been recorded. Contrarily, in 2014-2021 lower discharges allowed gradual channel narrowing and stabilisation, characterised by the spread and growth of vegetation in the river corridor.

Observed changes in channel morphology and vegetation succession are natural processes related to actively meandering rivers. However, it has been shown that extensive bank erosion during the flood and subsequent land cover dynamics were primarily triggered by anthropogenic removal of riparian vegetation exemplifying how inadequate and isolated river management decisions may increase bank erosion and lead to a loss of agricultural land in floodplain areas.

How to cite: Pavlek, K., Gašparović, M., and Poeppl, R. E.: Assessing river corridor changes after anthropogenic vegetation removal: an object-based mapping approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4096, https://doi.org/10.5194/egusphere-egu24-4096, 2024.

EGU24-4572 | ECS | Posters on site | GM5.3

Human impact on grain size variations of river gravel bars in the western Himalaya: Insights from a UAV survey 

Narendra K. Patel, Fritz Schlunegger, David Mair, Pitambar Pati, and Ariel Henrique Do Prado

Downstream variation in bed material size was investigated over a stretch of the Yamuna River in the western Himalayan region in India. Data on grain size distribution along rivers are critical for understanding river systems and material transport. Flow regulation caused by dam construction can alter sediment transport mechanisms, generating morphological changes. Using an uncrewed aerial vehicle (UAV), we investigated precise grain size variation along the Yamuna River and its tributaries in the Siwalik region, from Lakhwar Dam to Hathni Kund Barrage. All photos were collected via UAV survey.

On these datasets, grain size variation was observed across dams. The upper Yamuna River's bed-load sediments are becoming finer-grained downstream. Since the dam barrier and low flow energy force large particles to remain above the dam, smaller particles are found downstream of the dam. During the survey, evidence of mining in several locations along the river suggests the influence of anthropogenic activity in the regions. Accordingly, this study sheds light on the potential consequences of dam construction on material transportation. We observed that dams work as a barrier for coarse grain particles, which may have an impact on the dam in the near future. Field evidence and preliminary processed data indicate that the size of the gravel bar along the river course has been modified by many human interventions (hydroelectric dams, barrages, mining).

How to cite: Patel, N. K., Schlunegger, F., Mair, D., Pati, P., and Prado, A. H. D.: Human impact on grain size variations of river gravel bars in the western Himalaya: Insights from a UAV survey, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4572, https://doi.org/10.5194/egusphere-egu24-4572, 2024.

Already at the end of the 19th century, initial approaches were carried out to estimate the extent of anthropogenic mass transfer by humans on a global scale. In the course of the proposal of a new geological epoch, the Anthropocene, which is controversially discussed since the 2000s, anthropogenic geomorphological changes have received new attention. According to this concept, humans are moving more rocks and sediments worldwide than natural processes, with a supposed exponential increase in the mid 20th century. Along with agriculture, mining activities are among the most important anthropogenic transformations of the earth's surface. Mining landscapes have become at many locations an integral part of landform development and a crucial element of the technosphere. In the framework of the Anthropogenetic Geomorphology, humans are considered as geomorphological agents, creating a variety of landforms, for which at the same time new classifications are needed.

In the present project an interdisciplinary environmental-historical approach is used to examine the question of when, how and to which extent humans have modified the relief landscape. As study area, the Harz Mountains in Northern Germany were selected, which represents one of the most important historical mining areas in Central Europe, especially for silver, lead and copper. They are a key region for the interconnectedness of human-nature interactions, which are reflected in a genetically complex landscape development. Humans have influenced the landscape of the Harz Mountains already since prehistorical times to varying extents. Distinct phases of landscape transformation will be distinguished in this study. However, one of the most significant landscape changes took place in the Early Modern Period, when the Harz became one of the largest industrial areas in Central Europe with some of the deepest shafts worldwide at that time and large-scale underground excavations. The main driver for the exploitation of ores was the interlinkage with the global metal trade and the arise of new economic and political systems during the Renaissance, whereas the mining operations mainly relied on the local availability of certain resources such as wood and water. The energetic base for the underground mining, reaching up to almost 1000 m below the earth surface, was the Upper Harz Water Management System, the largest historical energy supply system for mining, designated as UNESCO-World-Heritage site in the year 2010.

In a case study in the St. Andreasberg Mining District (West-Harz) as one of the centers of silver mining, the physical landscape changes are systematically examined in the context of litho-geomorphological, ecological and cultural-political aspects and in their spatio-temporal patterns. The focus of the study presented here lies on the type and dimension of subterranean relief changes in the lithosphere in connection with the correlating transformation of the reliefsphere and the hydrological system in the catchment area of the Oder-Sieber River system. The mining landscape is composed of anthropogenic landform assemblages, consisting of heterogeneous compositions of lithogenic, geomorphological, biogenic and aquatic elements, which are representative for the Upper Harz mining landscape.

 

How to cite: Iturrizaga, L. and Ließmann, W.: Anthropogenic landscape transformations and geomorphological landform assemblages in the context of historical mining in the Harz Mountains (Germany): Case study Sankt Andreasberg Mining District , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6818, https://doi.org/10.5194/egusphere-egu24-6818, 2024.

EGU24-9614 | ECS | Posters on site | GM5.3 | Highlight

The influence of anthropogenic topographic changes on geomorphological processes in the city of Rome (Italy) 

Michele Delchiaro, Francesca Vergari, Carlo Esposito, and Maurizio Del Monte

The urban landscape of the city of Rome exhibits a discernible urban-rural gradient, characterized by a diminishing anthropic impact from the central historic city to the outskirts and peri-urban zones, marked by increased open spaces and green areas. In the Aeterna Urbs, the Anthropocene epoch has seen significant urbanization and infrastructure development, frequently leading to profound alterations or complete obliteration of natural landscapes. The distinctive anthropogenic changes observed in Rome, characterized by their unique features, are not confined to the city; they are also evident in other contexts, underscoring commonalities and interconnections in how human activity shapes the landscape. In this regard, the city of Rome stands as an exemplar, offering a unique opportunity to delve into the human-induced changes and their impact on the natural geomorphological processes. However, despite their critical importance in understanding human-landscape interactions and the associated geomorphological risks, the role of human activity as a morphogenetic agent along the urban-rural gradient remains inadequately understood. This study addresses the tricky understanding of human-induced geomorphic changes, particularly on erosion, transport, and sedimentation processes, which pose threats to ecosystem functioning and impede efficient land use. The Malagrotta extraction area in Rome, Italy, characterized by a mining landscape of ridge removal, hillslope terracing and valley filling, offers a unique opportunity to assess the impact of topographical alterations on the geomorphic system. The investigation employs the widely accepted functional relationship between drainage area (A in m2) and slope (S in m/m) to delineate local process domains and facilitate the interpretation of process interactions. The slope-area function is applied to the same watershed across different periods using digital elevation models, offering insights into the evolving geomorphic dynamics influenced by human activities.

How to cite: Delchiaro, M., Vergari, F., Esposito, C., and Del Monte, M.: The influence of anthropogenic topographic changes on geomorphological processes in the city of Rome (Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9614, https://doi.org/10.5194/egusphere-egu24-9614, 2024.

The Bonneville Salt Flats, a landscape characterized by a perennial halite crust and seasonal flooding in western Utah, USA, provides a natural laboratory for advancing understanding of the processes that create and change dynamic saline environments. A decade of interdisciplinary research on the Bonneville Salt Flats has resulted in a new understanding of the salt's history, the functioning of the salt crust ecosystem, and the role that humans play in shaping this landscape. Sedimentological analyses of cores collected across the salt has changed our understanding of the history of the landscape, including evidence of extensive erosion after Pleistocene Lake Bonneville, the surprisingly young age of the oldest salt (~5.4 cal ka BP), and historical and ongoing crust halite dissolution. 16S rRNA gene and metagenomic analysis of the salt crust reveals a complex and robust microbial and archaeal ecosystem within the salt, hosting a wide range of metabolic pathways that actively cycle C, N, and S through the landscape. A long-term environmental observation station established at the center of the salt crust provides a robust new record of landscape processes, weather data, and eddy covariance flux measurements that have helped to constrain the energy and water budgets and highlight the sensitivity of ecosystem-scale surface conductance in the absence of vegetation to atmospheric drying. Arial and spaceborne remote sensing data show the impacts of over a century of human activities on landscape composition and texture, including groundwater extraction for potash mining, intensive surface modification, and land use associated with high-speed vehicle racing on the salt. Brine extraction and attempted mitigation have resulted in salinity and salt crust extent decreases over the last several decades, potentially limiting future landscape uses. The intricate interconnection of the human-natural system has enabled the exploration of variations in mental models influencing decision-making, attribution of blame, and the feasibility of adaptive management in dynamic landscapes serving diverse and conflicting needs. Integration of science with art has expanded the nature of the inquiry and led to new ways of thinking about human connections to a seemingly barren, but truly alive, place. All of these new insights into saline landscapes and the role that human land use and climate change play in altering processes are significant to understand as water delivered to closed basin saline lakes globally is in decline, potentially leading to an expansion of exposed salt-encrusted landscapes.

How to cite: Bowen, B.: A decade of interdisciplinary research on the dynamics of surface processes and landscape change at the Bonneville Salt Flats, Utah, USA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9915, https://doi.org/10.5194/egusphere-egu24-9915, 2024.

EGU24-11466 | Posters on site | GM5.3

The impact of anthropogenic activities on the geomorphological evolution of the Taro River over the last 70 years 

Vittoria Scorpio, Alessandra Cervizzi, and Sharon Pittau

Human pressures, in response to economic development and population growth, have been one of the main drivers of river systems changes especially since the second half of the last century. In the European context, anthropogenic impacts mainly concern with catchment land use changes, in-stream gravel mining, and in-channel works construction. The reconstruction of the past evolutionary trajectories and the temporal analysis of driving factors is considered fundamental to understand present river conditions, to support channel network management and to anticipate future changes.

The aim of this study is to investigate the anthropogenic factors that have impacted the geomorphological evolution of the Taro River (Northern Apennines, Italy) over the last 70 years.

Traditional methods based on multi-temporal orthophoto (1954, 1976, 1988, 1994 and 2020) analysis in GIS environment were used for studying historical channel changes along a channel segment 90 km long. Analyses of anthropogenic factors that may have influenced changes in the active channel included: (i) analysis of land use changes at the catchment scale, (ii) quantification of gravel mining activities, and (iii) analysis of in-channel work constructions.

Results showed that between 1954 and 1976 the Taro River channel width decreased by 39% on average, mainly in response to gravel mining activities, and subsequently to the increase of works into the channel. To the contrary, as a result of mining activities abandonment in the early 1980s, and of the occurrence of an extreme flood event in 1982, an increase of 18% in the active channel width was observed in 1988. The decreases in active channel width in the last 30 years (since the end of the 1980s) were correlated with the increase in forested areas in the catchment and with the increasing degree of stabilization of channel banks.

These studies are fundamental to identify management solutions in degraded rivers and to anticipate impacts in such rivers still featuring poorly impacted channel morphologies.

How to cite: Scorpio, V., Cervizzi, A., and Pittau, S.: The impact of anthropogenic activities on the geomorphological evolution of the Taro River over the last 70 years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11466, https://doi.org/10.5194/egusphere-egu24-11466, 2024.

This study contributes to the topic of land surface degradation due to touristic activity by documenting examples of trail impacts related to initial trail development and high-intensity visitor usage. Our observations are based on a case study from the tropical Andes - Peru’s Rainbow Mountain (also named Vinicunca or Montaña de Siete Colores), which became a world-renowned tourist destination in recent years (after 2015/2016). The topic is important, as such high-mountain settings are very fragile, and degradation can occur rapidly – with long-term repercussions, as these landscapes tend not to recover quickly.

The main objectives of the study were to: (1) characterise and map different types of impacts related to direct visitor pressure, (2) document and evaluate activities aimed at limiting degradation while enhancing visitors’ experience, and (3) propose a conceptual model of trail functioning in the tropical high-mountain environment. Data were collected using ground-based surveys, unmanned aerial vehicle (UAV) and high-resolution satellite images.

Eight processes were responsible for transformation of the land surface: (1) trampling, (2) abrasion/shearing by visitors and service animals, (3) transformation of water and sediment circulation, (4) water erosion, (5) freeze-thaw cycles, (6) dry-wet cycles, (7) aeolian activities, and (8) mass movements. The five main trail impacts clearly visible in the landscape just after 1–2 seasons of intensive recreational use were: trail widening, trail incision, formation of braided trail networks, development of muddy sections, and development of informal (visitor-created) trails.

The hiking path was characterised by a width below 2 m and a low incision (<0.1 m incision on 80% of its length). The equestrian path was much wider (up to 17 m) and slightly more incised (<0.3 m incision on 69% of its length). The width of the multi-use path was up to 24 m. We suggest that the location of the trail in relation to the main geomorphological elements of the landscape (valley bottom vs slopes) and trail alignment to the terrain gradient have an essential impact on trail functioning and degradation. Specifically, trail sections routed through flat terrain and without lateral restrictions tend to widen and develop muddy sections, while sections routed parallel to steep slopes were prone to incision. Trails transverse to the terrain gradient were better drained but often developed into several parallel paths.

Undertaken trail management aimed to reduce negative visitor impacts and improve their safety and satisfaction. Successful measures included hardening the trail tread and marking the trail edges, which limited visitor dispersion and stabilised trail conditions. Partially successful actions involved installing artificial drainage (only partly preventing muddy section development) and providing separate paths for pedestrians and equestrians. After this change, the pedestrian trail was narrow and stable, but the equestrian path continued to degrade. Attempts to change visitor traffic patterns by relocating parking and abandoning a section of the trail were unsuccessful, as the new road and parking, and a new additional trail segment further degraded the landscape. Moreover, geomorphological processes continued to transform the abandoned trail section.

This study was funded by National Science Centre, Poland, project 2021/43/B/ST10/00950

How to cite: Tomczyk, A. and Ewertowski, M.: Land surface changes in response to touristic activity in the fragile, high-mountain environment: a case study of Vinicunca (Rainbow Mountain) in Andes, Peru, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12407, https://doi.org/10.5194/egusphere-egu24-12407, 2024.

Palaeochannels offer a glimpse into the history of a landscape. In the context of shifting perspectives from traditional hard engineering to soft nature-based measures, modern flood risk management could benefit from an understanding of the natural processes and features preserved within palaeochannels, which have otherwise been hidden by a legacy of engineering and land management on the river and floodplain. This study uses geophysical surveying techniques to bridge the gap between surface topography LiDAR data and sediment core data, in order to investigate the evolution of past rivers and tidal inlets in the Somerset Levels coastal plain and inland wetlands in southwest England. Case studies from a range of palaeochannels across the Somerset Levels are presented to identify the advantages and limitations of applying the methodology to a coastal plain and wetland dominated by Holocene alluvium and increasing human influence over the past several centuries. Four river systems represent both tidally dominated and inland freshwater conditions: a large tidal creek system within predominantly clay sediment; an inland river system traversing a peat wetland which was the former course of a major drainage network before intentional diversion; and two systems at the transition between tidal and freshwater influence.

Two-dimensional subsurface profiles derived from electrical resistivity tomography (ERT), shallow seismic refraction traverses, and ground penetrating radar (GPR) are used to laterally connect one-dimensional vertical sediment core data, and then integrated with the surface topography LiDAR data to construct channel and floodplain cross-sectional models. Past geomorphological processes – such as lateral migration, channel adjustment, and avulsion – are revealed in the preserved channel sediments, indicating responses to the contemporary climatic and anthropogenic conditions. Geophysical survey designs for identifying fluvial-geomorphological processes and features within palaeochannels are discussed, along with the need to adapt survey design for best resolution and depth in different, peat-dominated or clay-dominated, sedimentary settings. ERT is shown to consistently provide excellent depth penetration and estimations of channel extent. High resolution GPR data at the near-surface can be used in tandem with available core data to delineate the channel fill and bank geometry and calibrate depth estimations.

Flow conditions are reconstructed quantitatively using palaeohydrological drainage equations based on cross-sectional area values derived from the geophysical profiles. This avoids reliance on oversimplified cross-section estimates based upon surface parameters such as width and meander length, and one-dimensional depth estimates from core profiles. Existing hydraulic and drainage regime equations are tested against flow gauge data and channel measurements from active rivers to obtain optimal parameters for palaeohydrological calculations. These parameter estimates also benefit from on-the-ground channel parameter measurements in tandem with topographic remote-sensing. Hence, this study proposes a novel methodology that integrates geophysical surveying within palaeohydrological estimation techniques to improve models over long timescales of past fluvial environments that have been modified by humans.

How to cite: Anthony, J.: A geophysical study of palaeochannels on the Somerset Levels coastal plain and wetland to explore river landscape evolution., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12508, https://doi.org/10.5194/egusphere-egu24-12508, 2024.

EGU24-13659 | ECS | Orals | GM5.3

Testing a low-complexity model to decompose the multitemporal dynamics of soil erosion and sediment delivery in agricultural catchments 

Francis Matthews, Panos Panagos, Arthur Fendrich, and Gert Verstraeten

Testing and improving the capacity of soil erosion and sediment delivery models to simulate the response of soil erosion to the intra-annual dynamics of climatic drivers and disturbances (e.g., vegetation clearcutting, tillage events, wildfires) is critical to understand intolerable soil loss and catchment sediment yields. Here, we approach the trade-off between the need for model simplicity and temporally dynamic predictions by testing the ability of a low-complexity, spatially distributed model (WaTEM/SEDEM), to decompose the 15-day dynamics of soil erosion and sediment yield. A standardised RUSLE parameterisation and model implementation routine was applied to four arable-dominated catchments in North-West Europe with open-access validation data. We firstly show that when applied to simulate the multitemporal dynamics of sediment delivery, a standard assumption of a temporally static transport capacity within the model structure mostly cannot adequately replicate the multitemporal variability of sediment delivery. Instead, optimising a 5-parameter splines curve to determine the temporal profile of the transport capacity coefficient (ktc) based on the monthly average sediment yield improved the model performance and revealed clear seasonality in the sediment transport efficacy. Despite simulating similar temporally aggregated sediment yields, the introduction of seasonal dynamics into the transport capacity further caused a net reduction in the magnitudes of the spatially distributed sediment fluxes, compared to a temporally lumped approach. Published catchment observations infer this seasonality in sediment transport efficiency to attribute abundant vegetative boundaries in summer and increased soil crusting and runoff promotion in winter. Models operating at temporally aggregated timescales should account for the possibility of decoupling in time and space between gross erosion and sediment delivery related to these alternations between transport- and detachment-limited sediment transport capacity states. Despite the complexities and uncertainties involved in the temporal downscaling of WaTEM/SEDEM, we show the utility of this approach to: 1) link optimised multitemporal parameters to key missing model information components which may reduce error in gross erosion predictions (e.g. more consideration of antecedent soil conditions), 2) form a basis for strategically adding physical process-representation, with a focus on maintaining low model complexity while improving predictive skill, and 3) better understand the interdependencies between spatial fluxes and multitemporal dynamics when undertaking model predictions at large spatial and temporal scales.

How to cite: Matthews, F., Panagos, P., Fendrich, A., and Verstraeten, G.: Testing a low-complexity model to decompose the multitemporal dynamics of soil erosion and sediment delivery in agricultural catchments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13659, https://doi.org/10.5194/egusphere-egu24-13659, 2024.

Tailings are a by-product of the processing of minerals. Tailings can be highly erodible and transportable via fluvial processes and are commonly stored in ‘tailings dams’ which are a feature of many mine sites. These dams and their impounded material will become permanent geomorphic features in the post-mining landscape. The question examined here is - can tailings dams ever be walk-away structures? Tailings dams can fail by both catastrophic and gradual failure. Catastrophic failure occurs when there is a large scale rapid structural failure of the dam wall. Gradual failure occurs over time by slow infilling of the dam and the erosion of the dam wall. This can lead to overtopping of the dam wall and gully incision and failure of the wall and release of sediment to the environment. To understand failure modes and risk profile, computer based Landscape Evolution Models (LEMs) can be used. LEMs have become common tools to quantify risk for mine waste rock dumps and waste repositories.  LEMs provide detailed information on erosion rates, type of erosion and where erosion is likely to occur. They inform long-term behaviour which allows designs to be tested and improved. Here they are used to assess tailings dams where the strengths and weaknesses of different tailings dams designs are examined across a range of climates and material settings. The results show that if well-designed and assuming a well understood climate, a dam can be sufficiently robust to last centuries. However, failure can occur under different climate settings. Modelling also demonstrates that upon failure water quality will be affected for many centuries post-breach if no remedial work is conducted. Longer term, the tailings can be contained if there is maintenance and or an increase in the dam wall height over time or a more robust dam wall constructed to manage extreme events.

How to cite: Hancock, G. and Coulthard, T.: Assessing tailings dam long-term failure risk using computer based Landform Evolution Models , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14575, https://doi.org/10.5194/egusphere-egu24-14575, 2024.

EGU24-15250 | ECS | Posters on site | GM5.3

Legacy effects of post-storm silvicultural treatments on plot-scale soil erosion in a subalpine headwater catchment of the Italian Alps 

Kenta Koyanagi, Giovanna Nordio, Andrea Andreoli, Enrico Tomelleri, Ronald Pöppl, and Francesco Comiti

Wind-disturbed mountain forests are often subject to artificial deadwood extraction and tree planting to accelerate the recovery of timber resources. However, little is known about to what degree and extent those post-storm silvicultural treatments modify the surface processes of wind-affected hillslopes. This study aims to understand how post-storm silvicultural treatments affect soil erosion from wind-disturbed mountain forests by coupling monitoring and modeling approaches. We continuously collected and measured soil losses from four 4.5-m-wide and 6.0-m-long bounded field plots located on wind-disturbed hillslopes with a slope angle of 45 % in a subalpine headwater of the Italian Alps during the vegetation periods from 2021 to 2023. The dominant ground cover of four plots resulting from altered post-storm interventions is characterized by residual deadwood, native herbs, 20-year-old plantation, and 5-year-old plantation, respectively. During 75 analyzed storm events, average soil loss from the native herbs-covered plot (2.4 t ha-1; SD: ±3.5 t ha-1) was the smallest, followed by plots covered with residual deadwood (mean±SD: 3.1±2.9 t ha-1), 20-year-old plantation (mean±SD: 3.5±5.2 t ha-1), and the 5-year-old plantation (mean±SD: 4.5±4.2 t ha-1). Moreover, linear regression models (p-value < 0.001) indicated that two plantation plots potentially yield 2-fold sediment of naturally regenerating deadwood and herbs-covered plots as storm rainfall depth increases. Our three-year field observations highlight the persistent impact of post-storm forest management activities in accelerating soil erosion potentially even 20 years after their implementation. In the next step, the Water Erosion Prediction Project (WEPP) model will be used to further investigate the effect of human treatments on hydrology and sediment transport in storm-affected mountain areas.

How to cite: Koyanagi, K., Nordio, G., Andreoli, A., Tomelleri, E., Pöppl, R., and Comiti, F.: Legacy effects of post-storm silvicultural treatments on plot-scale soil erosion in a subalpine headwater catchment of the Italian Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15250, https://doi.org/10.5194/egusphere-egu24-15250, 2024.

As the number and quality of satellite data detecting the Earth increases, a significant number of research fields are using these images, providing increasingly interesting results that were previously unimaginable. In this study, we extract the coastline from satellite images captured over a long period of time and analyze how the location of the coastline has changed in time and space.

Recently, many studies have attempted similar analyzes. However, the resolution of the image is low, so the results tend to be unreliable, as they often produce trend results of less than cm per year. Therefore, in this study, we first analyzed how reliable the trend results are depending on the amount of data, even if the resolution is low.

We also present a method to obtain the location of the coastline from reference points fixed behind the coast by linearly fitting nearby coastline points to reduce the error of coastline points extracted from satellite images. This method obtains the coastline position as the distance to the intersection of the base line and the fitting line and obtains the coastline gradient as the angle of the fitting line.

This method was applied to Wonpyeong-Chogok Beach located in the East Sea of the Korean Peninsula to analyze how the coastline has evolved over the past five years from 2019 to 2023, when coastal structures were built. On this beach, which has a total length of 2.9 km, three submerged detached breakwaters, two emerged detached breakwaters, and three groynes were built to reduce beach erosion. Reference points are located about 100 m behind the circular line that best fits the coastline, and the direction of base line is fixed to face the center of the fitting circle. Behind the emerged detached breakwater, the rate of change is up to 6.2m per year, and even in areas where structures have not yet been installed, there is a slight forward trend (0.4m/yr) due to the influence of beach nourishment. The standard deviation of the coastline position data for each base line ranges from 4.0m to 10.6m. Recently, Lim et al. (2022) presented the relationship between the standard deviation of the coastline data and sand grain size, and compared to the sand grain size results collected in the field, the grain size value was shown to be larger. The reason is that if the annual mean coastline is not maintained and continues to advance, the standard deviation increases. Considering this effect, the results are compared with observed sand gain size data. Therefore, it will be interesting to see how feasible it is to estimate the sand grain size from the analysis of long-term shoreline data obtained from satellite data, as in the results of this study.

 

 

Reference

Lim, C., Kim, T.-K., Kim, J.-B., and Lee, J.-L. (2022). A study on the influence of sand median grain size on the short-term recovery process of shorelines. Front. Mar. Sci. 9. doi: 10.3389/fmars.2022.906209

How to cite: Kim, E. H. and Lee, J. L.: Shoreline Change Analysis After Construction of Coastal Structures in Wonpyeong-Chogok Beach by Satellite Image Process, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16648, https://doi.org/10.5194/egusphere-egu24-16648, 2024.

EGU24-18146 | ECS | Orals | GM5.3

Natural dynamic vs anthropogenic transformations of the AlUla oasis, NW Arabia, during the Holocene: a combination  of geoarchaeology and geomatic approaches 

Amaury Fernandes, Laurent Lespez, Gourguen Davtian, Hatem Djerbi, Claude Rouvier, Sophie Costa, Eric Andrieux, and Louise Purdue

Oases are man-made environment in response to hydro-climatic constraints of dryland. They form landscapes of natural origin that have been modified and exploited by the agro-pastoral practices of human societies. The oasis of AlUla, in Northwestern Saudi Arabia, is settled at least since the beginning of the Bronze Age. This oasis is located at the foot of the Harrat al-Uwayrid formation which separates the sandy deserts of northern Arabia from the Red Sea. AlUla has a long history of occupation, notably through the development of major archaeological sites such as the Late Bronze Age site of Dadan, the Nabataean site of Hegra, and the old towns of AlUla and Al Mabyat from the Islamic period. Recent research has also revealed the development of agro-pastoral activities since the Neolithic and hydroagricultural development from the Late Bronze Age onwards.

The aim of this research is to reconstruct the landscape of the AlUla oasis and thus to find out in what environmental framework these agro-pastoral societies developed. It also aims to study the role of climatic changes in the natural dynamics that have formed the geomorphology of the oasis (aeolian, fluvial, slopes processes and formations) and to determine the impact of human development. These objectives are to provide answers about the understanding of the current organization of geomorphological objects and their evolution/transformation through the Holocene and thus the interactions between societies and their environment that have produced them. This work has also enabled us to produce quantitative data on the volumes of earth moved/excavated since the rampant urbanization of the oasis, and to identify the practices (quarrying vs. levelling) and geomorphological environment most affected by these earthworks.

To achieve these objectives, we have produced a diachronic geomorphological map covering the AlUla oasis and its margins, with the aim of tracing the natural history of the oasis from its current state back to the Neolithic/Early Holocene. This realization of this map is based on a combination of geomatics methods, using a DEM produced by LiDAR data (2018, 40 cm accuracy), orthophotographs (2018, 10 cm accuracy), remote sensing with satellite images (1965-2024 Google, Bing, Corona), geological data (1:500,000) and fieldwork in order to inventory landforms and determined their organization and their chronology (C14, OSL).

Our results show a long-term trend towards aridification since the second half of the Holocene and an increase in human pressure since the Bronze Age. This last observation result from the initiation and expansion of agricultural practices supported by earthworks which have led to the development of levees along wadis, agricultural terraces and anthroposols. These anthropogenic forms associated with numerous excavations have greatly modified the initial topography and therefore the geomorphology of the oasis, from the Bronze age but with an astonishing and constant acceleration over the last thirty years. This demonstrates that the natural dynamics which have prevailed during the Holocene are progressively replaced by the impact of human societies, acting as an agent of erosion in the oasis environment in NW Arabia during the Anthropocene.

How to cite: Fernandes, A., Lespez, L., Davtian, G., Djerbi, H., Rouvier, C., Costa, S., Andrieux, E., and Purdue, L.: Natural dynamic vs anthropogenic transformations of the AlUla oasis, NW Arabia, during the Holocene: a combination  of geoarchaeology and geomatic approaches, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18146, https://doi.org/10.5194/egusphere-egu24-18146, 2024.

EGU24-18350 | Orals | GM5.3

Quantifying human impact during industrialisation on the evolutionary trajectory of Vosgian streams (NE France): the value of documentary archives  

Timothée Jautzy, Nicolas Jacob-Rousseau, Salomé Berthier--Laumond, Margaux Claudepierre, Gilles Rixhon, and Laurent Schmitt

The anthropogenic pressure on European rivers has greatly intensified since the Industrial Revolution through channelisation, rectification, and building of dams and weirs. Against this background, focusing on the Vosges Mountains (NE France) is particularly relevant since it is the most densely populated mountain range in France. The Vosgian hydrographic network was accordingly impacted by widespread human modifications. No less than ~5000 hydraulic structures (HS) mostly involving weirs were built across the main streams draining the massif. Contrary to large rivers (e.g. the Rhine), the edification periods of these HS in smaller catchments remains largely unknown yet, thereby impeding a precise chronological reconstruction of the main phases of human pressure and environmental trajectories.

 

In this study, we aim to gain insight into the spatio-temporal anthropisation of three main streams draining the southern part of the Vosges, i.e. the Fecht, Vologne and Moselotte, and to evaluate their historical morphodynamic adjustments from the end of the 18th century onwards. We took advantage of the abundant paper archives, i.e. written reports, plans…, from the “Ponts et Chaussées” administration, which collected at the local scale every official request to build HS along and across streams from the 18th to the 20th century. Firstly, we characterised and mapped every weir and levee along the three studied streams to produce an updated database of the present distribution of HS. Secondly, we analysed the archives to date the construction (and in some cases deconstruction) of the HS. Finally, we reconstructed the diachronic evolution of the channel pattern, from an ancient topographical map (1866) and two orthophotos (1951, 2018). Our results allow a first quantification of human impacts: the year of construction (terminus ante-quem) could be assigned to 7%, 38% and 59% of the weirs currently present in the Fecht, Vologne and Moselotte, respectively. Most of them were probably built in the middle of the 19th century. Importantly, we also evidence a spatio-temporal correlation between the construction of HS and the simplification of the channel pattern. Although the use of historical documents has several limitations (e.g. loss, destruction, unavailability), we demonstrate that they are valuable archives that usefully complement field observations and investigations.

How to cite: Jautzy, T., Jacob-Rousseau, N., Berthier--Laumond, S., Claudepierre, M., Rixhon, G., and Schmitt, L.: Quantifying human impact during industrialisation on the evolutionary trajectory of Vosgian streams (NE France): the value of documentary archives , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18350, https://doi.org/10.5194/egusphere-egu24-18350, 2024.

EGU24-19923 | Posters on site | GM5.3 | Highlight

Reading the sedimentary archives in the Danube floodplain downstream of Vienna (Austria) 

Michael Weissl, Diana Hatzenbühler, Christian Baumgartner, and Michael Wagreich

Many human interventions in river systems, e.g., river channelization, hydropower dams, or restoration measures, affect geomorphological and sedimentological settings. Anthropogenic impact can lead to alterations in stream dynamics and sedimentary imbalances, as recorded in the sediments of large riverplains.

In the project “From Romans to the Anthropocene, from Carnuntum to Vienna: An Urban Anthropocene Field Lab” (WWTF ESR20-027) we explore long-term urban and geomorphological transformations within the Danube floodplain between Vienna (Austria) and Bratislava (Slovakia). Combining historical and sedimentological methods, our research focuses on the development of a very old settlement area within the transition zone between eastern and Central Europe.

Extensive river engineering, starting in the 19th century, was a precondition for Vienna’s development as a residence and metropolis. This includes extensive river training and the construction of flood control structures. After a long period of river engineering and the construction of many hydro-power dams along the upper Danube, around 2000 the local removal of river bank fortifications started and also the restoration of fluvial dynamics primarily within our study area downstream of Vienna, in the free-flowing river section of the Donau-Auen National Park.

Fine overbank deposits record river dynamics through climatic and anthropogenic drivers. Reading the sequence of alluvial deposits allows us to understand the human impact on floodplain morphology. The great advantage of analyzing sedimentary archives is the temporal depth they offer: we can evaluate the conditions prior to river training (~200 years ago), the effects of engineering measures (e.g. river channelization, construction of hydropower stations), and recent restoration measures as well.

The characterization of sediment archives, including sediment dating (radioactive isotopes, OSL, dendrochronology), provides information on major flooding events, changes in the flow regime, and the dynamics of sedimentation. For investigations into sedimentary processes and river morphology downstream of Vienna, it is also necessary to have a look not only at the present state of a trained river but also at the former, near-natural situation of the riverscape. Therefore, comparisons of changing river morphologies before, during, and after the erection of dams and weirs are a requirement.

 

How to cite: Weissl, M., Hatzenbühler, D., Baumgartner, C., and Wagreich, M.: Reading the sedimentary archives in the Danube floodplain downstream of Vienna (Austria), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19923, https://doi.org/10.5194/egusphere-egu24-19923, 2024.

The interdisciplinary project, titled 'Living together or apart? Unravelling the development, internal organization, and social structure of a complex Bronze Age tell settlement at Toboliu, western Romania,' seeks to analyse Bronze Age settlement activity in Toboliu, located in the easternmost Carpathian Basin. Key aspects of the study include associated land-use and landscape evolution, making the reconstruction of the tell's surroundings a focal point. The study area is dominated by loess and significantly influenced by both modern and prehistoric agricultural practices. Thus, it is a major challenge to differentiate between landscape features caused by natural soil-landscape formation processes and human activity especially for the investigated period. Within this context we focussed our research on closed depressions surrounding the tell and investigated two hypotheses regarding their formation: i) closed depressions result from human activities (such as daub extraction pits) and ii) formed through natural soil-geomorphological processes (like loess dolines or periglacial relicts). Based on core drillings, we made use of Optically Stimulated Luminescence (OSL), radiocarbon-supported, and palynological chronostratigraphical analyses. In addition, we took advantage of spatial analysis involving a high-resolution LIDAR elevation model, multispectral WorldView-3 imagery, and magnetographic data to thoroughly testing both hypotheses. Our results suggest that the examined closed depressions exhibit characteristics reminiscent of specific periglacial relict forms, more commonly known from northern European landscapes. Details will be discussed within the presentation.

How to cite: Zickel, M., Nett, J. J., Röpke, A., and Reimann, T.: Unraveling Geomorphological Processes and Anthropogenic Activity at the Eastern Border of the Carpathian Basin: Insights from the Bronze Age Tell site Toboliu, Romania, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1638, https://doi.org/10.5194/egusphere-egu24-1638, 2024.

In antiquity, the development of techniques to collect and store water was fundamental to sustain life in arid regions. One way to overcome the problem of water supply in the desert was to construct water reservoirs and cisterns which collect surface runoff during rare rain events. Indeed, open reservoirs and rock-cut cisterns are widely spread over the arid zone of the Negev Highlands / Israel. They were an important component of human activity in the area. Today, they can serve as sedimentary archives for archaeological and paleoenvironmental reconstruction. Here we provide the final assessment of a large-scale optically stimulated luminescence (OSL) dating project of water installations in the arid Negev Highlands. By sampling spoil piles, feeding channels, and accumulation of sediments within reservoirs and cisterns, the construction, the phases of maintenance and abandonment were dated. The significance of these results for reconstructing the history of human activity in the region is discussed.

How to cite: Fuchs, M., Junge, A., and Lomax, J.: Chronology of ancient water installations and the history of human activity in the Negev Highlands, Israel , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2124, https://doi.org/10.5194/egusphere-egu24-2124, 2024.

EGU24-4080 | PICO | GM5.4

Holocene overbank sedimentation in Central Europe between natural and human drivers – the Weiße Elster River (Central Germany) 

Hans von Suchodoletz, Azra Khosravichenar, Pierre Fütterer, Christoph Zielhofer, Birgit Schneider, Tobias Sprafke, Christian Tinapp, Alexander Fülling, Lukas Werther, Harald Stäuble, Michael Hein, Ulrich Veit, Peter Ettel, Ulrike Werban, and Jan Miera

Up to several meters thick fine-grained Holocene overbank deposits are ubiquitously found in most Western and Central European lowland floodplains. However, the interplay of different possible causes for their formation are not well understood yet. Most authors suggest human-induced deforestation as the main precondition for sediment mobilisation and transport from the slopes to the floodplain, generally regarding overbank sediments as human-derived ‘legacy sediments’. In contrast, others suggest a stronger influence of climatic factors. This current research gap is caused by often missing well-resolved fluvial chronostratigraphies and spatio-temporal information about former human activity within the studied catchments. To fill this gap we exemplarily studied Holocene overbank sedimentation and possible human or natural drivers in the meso-scale Weiße Elster catchment in Central Germany by using a comprehensive geoarchaeological approach: On the one hand, we applied numerical dating as well as sedimentological and micromorphological analyses to Holocene overbank sediments along three floodplain transects. On the other hand, we built up an unprecedented systematic spatio-temporal database of former human activity within the catchment from the Neolithic until the Early Modern Ages. Together with published paleoclimatic data, this database allowed an unprecedented, systematic comparison of Holocene overbank sedimentation phases with possible human and natural external controls. Our data show that some overbank sedimentation phases were directly linked with human activities in the affected site sub-catchments, whereas others were not. Instead, all phases were clearly linked with natural factors, i.e. hydroclimatic fluctuations. This difference with most former studies could possibly be explained by previously often limited numerical dating of the fluvial sediments and by largely missing spatio-temporally well-resolved regional settlement records, hindering a precise temporal link of fluvial sedimentation with former human settlement. Furthermore, this difference could possibly also be explained by a relatively high natural sensitivity of the landscape dynamics in the Central German lowlands, showing a subcontinental climate, towards external controls.

 

How to cite: von Suchodoletz, H., Khosravichenar, A., Fütterer, P., Zielhofer, C., Schneider, B., Sprafke, T., Tinapp, C., Fülling, A., Werther, L., Stäuble, H., Hein, M., Veit, U., Ettel, P., Werban, U., and Miera, J.: Holocene overbank sedimentation in Central Europe between natural and human drivers – the Weiße Elster River (Central Germany), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4080, https://doi.org/10.5194/egusphere-egu24-4080, 2024.

The Austronesian population, which consists of approximately 0.4 billion people, is widely spread across the Pacific and Indian Ocean islands. Extensive research over several decades has led to an academic consensus that the Austronesian population originated from Taiwan and the southeastern coast of mainland China. However, the exact manner in which the Austronesian ancestors arrived in Taiwan and subsequently dispersed to other oceanic regions remains a mystery. By analyzing the last deglacial sea-level rise, neotectonic activities, and resulting ancient environmental changes, as well as comparing the characteristics of middle Neolithic remains (dating back approximately 7.4-4ka) between the Taiwan Strait, we have proposed the existence of a “proto-Austronesian culture” in the early Holocene (around 11.7ka~7.4ka). This culture was centered around the nearshore area of the Taiwan Strait and Taiwan Shoal region. As sea levels gradually rose, the Austronesian ancestors’ habitat became increasingly submerged, compelling them to retreat to the inshore highlands on both sides of the Taiwan Strait. The Austronesian relics discovered on both sides of the Taiwan Strait, such as Dabenken, Keqiutou, and Fuguodun, among others, are actually branches of the Austronesian ancestors, inheriting their marine ecological characteristics. The scarcity of Neolithic artifacts older than 7.4ka on both sides of the Taiwan Strait can be attributed to a “survivor bias” phenomenon. It is plausible that numerous early Holocene relics of the “proto-Austronesian culture” remain submerged in the nearshore area of the Taiwan Strait and Taiwan Shoal, eagerly awaiting discovery through submarine archaeological exploration.

How to cite: Zhang, K. and Zhang, S.: Unraveling the Origins and Dispersal of Austronesian Culture by the last deglacial sea-level rises and paleoenvironmental changes: Insights from the Taiwan Strait, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4518, https://doi.org/10.5194/egusphere-egu24-4518, 2024.

EGU24-8532 | ECS | PICO | GM5.4

Application of shallow geophysical methods and machine learning for detecting remains of early medieval settlements in south-eastern Poland. 

Szymon Oryński, Artur Marciniak, Piotr Berezowski, Paweł Banasiak, and Justyna Cader

Poland's landscape is a testament to its deep-rooted agricultural history, characterized by ancient field systems echoing the spatial layouts in Celtic fields throughout Europe. These intricate and expansive layouts pose a significant challenge for archaeologists and researchers dedicated to uncovering the secrets of the past. The focus of this study is to meticulously explore and analyze these extensive field systems, which often cover large areas and require a detailed and systematic approach. To navigate this complex task, researchers employed cutting-edge deep learning neural networks (DLNN), particularly the U-Net model. This approach involved semantic segmentation of data derived from Airborne Laser Scanning (ALS) to automate the identification of these significant archaeological sites. The team successfully identified hundreds of ancient sites across Poland by harnessing the power of ALS data combined with thorough desk-based analysis.

The research concentrated on specific sites in southern Poland, namely in the areas around Trzebinia and Jaworzno. Various geophysical methods were utilised here, including Magnetometry and the Slingram Electromagnetic Induction Method. These techniques aimed to confirm the existence of preliminary archaeological features in the region. The researchers conducted Magnetic Gradiometry and Electromagnetic Measurements across different terrains, including cultivated fields and forests. They specifically targeted relict embankments that once delineated old fields. The findings from these investigations were striking. The geophysical profiles of the two studied areas revealed significant differences. In the first area in a current crop field, researchers observed point-like, strong anomalies in both vertical magnetic gradient and electrical conductivity. In contrast, the wooded study area exhibited weaker but continuous anomalies, suggesting the presence of buried burnt clay formations. A key aspect of this research was integrating Ground Conductivity assessments with vertical magnetic gradient evaluations. This approach was crucial in correlating data from both methods. At the first site, variations in conductivity at different depths hinted at geological transitions or man-made structures beneath the surface. Meanwhile, at the second site, resistivity patterns suggested an anthropogenic alteration of water conditions, possibly resembling an artificial fault.

Integrating a machine learning system into this research process marked a significant advancement. It facilitated the automated segmentation of ALS data, greatly enhancing the efficiency of detecting and mapping cultural resources over large areas. Combined with traditional geophysical methodologies, this innovative approach provided a non-invasive means of identifying potential archaeological objects. This was crucial for the effective management and preservation of heritage sites. In summary, this comprehensive interdisciplinary study represents a fusion of advanced technological solutions with traditional geophysical methods. It offers valuable new insights into detecting and interpreting archaeological features, potentially revolutionizing the field of archaeological exploration and heritage conservation. The research highlights the importance of integrating diverse methodologies to uncover the intricacies of our past, ultimately contributing to a deeper understanding of human history and its impact on the landscape.

How to cite: Oryński, S., Marciniak, A., Berezowski, P., Banasiak, P., and Cader, J.: Application of shallow geophysical methods and machine learning for detecting remains of early medieval settlements in south-eastern Poland., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8532, https://doi.org/10.5194/egusphere-egu24-8532, 2024.

EGU24-10076 | PICO | GM5.4

Palaeoenvironmental changes and human-environment interactions in the surroundings of La Silla del Papa, SW Spain 

Dominik Brill, Simon Matthias May, Maike Norpoth, Anna Pint, Lyudmila Shumilovskikh, Kira Raith, Gilles Rixhon, Pierre Moret, Helena Jiménez-Vialás, Ignasi Grau-Mira, Iván García-Jiménez, Dirce Marzoli, César León-Martín, Klaus Reicherter, and Helmut Brückner

The surroundings of the Strait of Gibraltar in southern Iberia are well known as a crossroads for population movements, cultural exchange and trade from Late Prehistory to Modern Times. However, questions remain about how this historical development has impacted the environment. The settlement of La Silla del Papa, an important hillfort located in the Sierra de la Plata in southern Andalusia (Cádiz), and its territory represent an ideal location for long-term studies of human-environment interactions. It was occupied throughout the entire Iron Age, replaced by the coastal town of Baelo Claudia during Roman times, and reoccupied in the early Middle Ages. Therefore, the geoarchaeological investigations in the surroundings of La Silla del Papa within the framework of the interdisciplinary project “Archeostraits” aimed at constraining the ecological conditions and human-environment interactions during the Mid- and Late Holocene and during the most important human occupation phases. Our investigations included sedimentological, geochemical, chronological (OSL, 14C-AMS, diagnostic pottery), microfaunal and palynological analyses of nine sediment profiles as well as nine vibracores from the catchment of the Río del Cachón, a small river originating in the Sierra de la Plata, just below La Silla del Papa. Our results document an early Mid-Holocene open marine embayment in what is now the lower floodplain, which rapidly transformed into a coastal lagoon and later into freshwater-dominated wetlands. After ~2100 BP, fluvial and alluvial deposition considerably increased, suggesting high anthropogenic impact on the local landscape during the Roman or post-Roman times. Palynological results reveal fluctuating agricultural and pastoral activities and suggest two distinct periods of landscape opening between 7000-6000 BP and during the Phoenician and Iron Age period.

How to cite: Brill, D., May, S. M., Norpoth, M., Pint, A., Shumilovskikh, L., Raith, K., Rixhon, G., Moret, P., Jiménez-Vialás, H., Grau-Mira, I., García-Jiménez, I., Marzoli, D., León-Martín, C., Reicherter, K., and Brückner, H.: Palaeoenvironmental changes and human-environment interactions in the surroundings of La Silla del Papa, SW Spain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10076, https://doi.org/10.5194/egusphere-egu24-10076, 2024.

EGU24-12670 | PICO | GM5.4

Prehispanic agricultural terrace-settlement systems: an integrative approach to study land use and settlement dynamics in the southern Peruvian Andes 

Julia Meister, Christoph Binder, Laura Dietrich, Philipp Godde, Fernando Leceta, Mike Lyons, Erik Marsh, Markus Reindel, and Christian Mader

An impressive relic of the scale of human-environment interaction and land modification in prehispanic South America are agricultural terraces, covering slopes across the Andes and of which only a fraction is still in use nowadays. Despite the ubiquity of agricultural terraces in the Andes, there is a lack of systematic studies that combine the investigation of farming terraces, land use history, and settlement patterns, preventing a comprehensive understanding of prehispanic socio-economic-ecological systems and human-environmental interactions. Our project develops and applies an integrative and interdisciplinary methodological approach to the study of prehispanic Andean terrace agricultural systems and associated settlements, providing reliable data on the dynamics of land use-settlement systems through time and space. Our methodological approach consists of the application of a variety of archaeological and geoscientific methods, including archaeological and geomorphological surveys, archaeological excavations, drone surveys, mapping using satellite imagery and high-resolution digital elevation models, geographic information system applications, soil testing, phytolith and starch analysis, numerical dating, and calculations of food supply capacity and labour requirements.

We apply these to the prehispanic site of Cutamalla (3,300 m asl) in the southern Peruvian Andes, which serves as an ideal and pioneering case study. Previous research has focused primarily on the settlement of Cutamalla, particularly through large-scale archaeological excavations, but less attention has been paid to the extensive farming terraces surrounding the settlement and the close relationship between agricultural and settlement activities. By analyzing both the terrace and settlement levels, we take a new perspective and introduce the term agricultural terrace-settlement system for such complexes. Our results show that the residential occupation of Cutamalla and the use of the surrounding farming terraces coincided: the agricultural terrace-settlement system was intensively used for a relatively short period of about 200 years (~250–40 BCE) during the Formative Late Paracas and transitional Initial Nasca periods. There is no evidence of reoccupation of the site and subsequent reuse of the agricultural system. Our data also document the large extent of agricultural terraces around Cutamalla (221 ha) and that maize was likely a major crop grown there. Finally, we place these findings in their broader socio-economic and ecological context. Cutamalla was an important regional center and economic hub during a very dynamic period characterized by significant population growth and increased violence. Not only a more humid climate, but probably also forced collective labor were cornerstones of substantial agricultural production in Cutamalla and the region.

How to cite: Meister, J., Binder, C., Dietrich, L., Godde, P., Leceta, F., Lyons, M., Marsh, E., Reindel, M., and Mader, C.: Prehispanic agricultural terrace-settlement systems: an integrative approach to study land use and settlement dynamics in the southern Peruvian Andes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12670, https://doi.org/10.5194/egusphere-egu24-12670, 2024.

EGU24-14063 | PICO | GM5.4

Deciphering Hidden Ancient Human Physical and Chemical Markers through pOSL and  pXRF Analysis: A Case Study at Tel Burna 

Oren Ackermann, Martin Janovský, Polina Nikolskaia, Jan Fišer, Yaakov Anker, Yamm Anker, Tziona Ben-Gedalya, Aharon Friedman, Michal Hejcman, and Itzhaq Shai

As archeological sites are not isolated islands, they exert horizontal and vertical influence on their surrounding area. Therefore understanding the impact of these sites on their periphery becomes crucial.  Soil and sediments, as reliable historical archives, provide a unique opportunity to investigate these processes. Recent research has demonstrated that not all markers of human activity are visible, and a combination of physical and chemical methods, including pOSL and pXRF analysis, can provide insights into hidden past human signatures.

Core drills conducted at the footslope of Tel Burna In Israel's archaeological site revealed an anthropogenic unit buried within the valley. This unit also contains a layer indicative of heightened anthropogenic activity, which could either signify the remnants of an ancient field's surface or the site's abandonment, followed by rapid site erosion. Given that these drills spanned from the slope of the Tell to the valley below, we were able to track the sediment's properties from the top of the site down to the valley. It was shown that the anthropogenic influence reduced with distance from the site, resulting in increasingly intricate patterns, suggesting multiple sources of sedimentation—both natural and anthropogenic. Furthermore, the study revealed a cycle of deposits that were transported to the site from the adjacent valley through human material transport activities to be subsequently eroded back into the valley due to natural processes. In summary, the ancient archeological site during its occupation and abandonment is still a physical feature that has been contributing to the landscape cycling processes.

How to cite: Ackermann, O., Janovský, M., Nikolskaia, P., Fišer, J., Anker, Y., Anker, Y., Ben-Gedalya, T., Friedman, A., Hejcman, M., and Shai, I.: Deciphering Hidden Ancient Human Physical and Chemical Markers through pOSL and  pXRF Analysis: A Case Study at Tel Burna, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14063, https://doi.org/10.5194/egusphere-egu24-14063, 2024.

EGU24-15442 | PICO | GM5.4

A submerged Late Pleistocene hunting structure in the Western Baltic Sea 

Jacob Geersen, Marcel Bradtmöller, Jens Schneider von Deimling, Peter Feldens, Jens Auer, Philipp Held, Arne Lohrberg, Ruth Supka, Jasper Hoffmann, Berit Valentin Eriksen, Wolfgang Rabbel, Hans-Jörg Karlsen, Sebastian Krastel, David Heuskin, David Brandt, and Harald Lübke

After the retreat of the Weichselian glaciers, Northern Europe was populated by highly mobile hunter-gatherer groups. Traces of these societies are difficult to find, hampering our understanding of their life. Some remote basins of the western Baltic Sea, however, only drowned in the Holocene, and it has recently been postulated, that they preserve architectures from the Stone Age, that did not survive on land. In 2021 we documented the Blinkerwall, a stonewall megastructure located in 21 m water depth in the Bay of Mecklenburg, Germany. Shipborne and autonomous underwater vehicle hydroacoustic data as well as optical images show that the wall is composed of about 1700 stones, predominantly less than 1 m in height, placed side by side over 971 m in a way that argues against a natural origin by glacial transport or ice push ridges. Combining this information with sedimentological samples, radiocarbon dates, and a geophysical reconstruction of the paleo-landscape, we suggest that the wall was likely used as a drive lane for hunting during the late Pleistocene or earliest Holocene. Ranging among the oldest hunting structures on Earth and the largest Stone Age structures in Europe, the Blinkerwall will become important for understanding subsistence strategies, mobility patterns, and inspire discussions concerning the territorial development in the Western Baltic Sea region.

How to cite: Geersen, J., Bradtmöller, M., Schneider von Deimling, J., Feldens, P., Auer, J., Held, P., Lohrberg, A., Supka, R., Hoffmann, J., Eriksen, B. V., Rabbel, W., Karlsen, H.-J., Krastel, S., Heuskin, D., Brandt, D., and Lübke, H.: A submerged Late Pleistocene hunting structure in the Western Baltic Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15442, https://doi.org/10.5194/egusphere-egu24-15442, 2024.

EGU24-16626 | PICO | GM5.4

Micromorphological insights within the Middle Pleistocene-Holocene cave sediment record of Grotta Romanelli, Italy. 

Guido Stefano Mariani, Pierluigi Pieruccini, Davide Susini, Luca Forti, Ilaria Mazzini, and Raffaele Sardella

Grotta Romanelli (Apulia, southern Italy) is a key-site in Mediterranean archaeology. In the long history of excavations since the early 20th century, its sedimentary archive has revealed important information about human frequentation, vertebrate faunas, and environmental changes, inside a time frame which includes the Middle Pleistocene (ca. 350 ka BP) and the Early Holocene (ca 11 ka BP). The peculiarity of the sedimentary succession, which consists of fine- to very fine-grained sediments with weakly-developed or massive sedimentary structures, determined a thorough micromorphological investigation. Indeed, these sedimentary structures are often associated with human-settled cave environments. Thus, the micromorphological analysis is of utmost importance for determining the sedimentary and geomorphological context of an archaeological site. In this respect, we present for the first time the results at a more detailed scale of the depositional environments of Grotta Romanelli, in order to understand the role of sedimentary, post-depositional and anthropogenic processes in the formation of the stratigraphy of the cave.

The micromorphological investigation highlights several microfacies associated with the finer-grained sediments. The sediments within the deposit is mainly allochthonous as evidenced by the abundance of aeolian quartz and remnants of leached soils, thus indicating erosion and transport into the cave. Moreover, the characterisation of the microfacies suggests runoff and standing water processes as main agents of the internal redistribution of material. This also includes, albeit to a lesser extent, phases of biological activity, as well as phases of relative surface stability and anthropogenic contributions. Anthropogenic inputs are mainly related to fire activity and food exploitation, such as charcoal, charred plant tissue, and burnt bones. Notwithstanding the extensive volume of sediments excavated during historical archaeological campaigns, especially in the mid-frontal sectors, results show that anthropogenic inputs are not restricted to specific areas within the cave, due to its dimensions, rather they are sporadically scattered across the microfacies.

How to cite: Mariani, G. S., Pieruccini, P., Susini, D., Forti, L., Mazzini, I., and Sardella, R.: Micromorphological insights within the Middle Pleistocene-Holocene cave sediment record of Grotta Romanelli, Italy., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16626, https://doi.org/10.5194/egusphere-egu24-16626, 2024.

EGU24-20000 | PICO | GM5.4

New stable isotope geochemical approach documents grain production and manuring in the High Middle Ages 

Martin Janovský, Laszlo Ferenczi, and Jakub Trubač

Isotope analysis, particularly for the determination of δ13C and δ15N in archaeobotanical remains, is a recognized method within the field of archaeology. Until now, the primary focus of these analyses has been on archaeobotanical remains directly related to dietary practices. The significant impact of the Cistercian Order on the European agricultural landscape, and its far-reaching ecological consequences, has been well documented. However, the use of isotopic analysis for determining land-use based on present-day soils remains unexplored. The study at hand focuses on a Cistercian court, utilized from the 13th to the 15th century. The lands of this court, along with its surrounding regions, have been extensively surveyed. The isotopic analysis of the anthropogenically influenced soils is compared to approximately 400 archaeobotanical, soil, and sediment samples collected globally. The comparative analysis reveals the potential to ascertain through the presence of the C3 cycle and evidence of medieval fertilization, that the area was used for cereal cultivation and fertilization. The results of our study indicate that the medieval Cistercians employed the landscape primarily for grain production rather than pastoralism.

How to cite: Janovský, M., Ferenczi, L., and Trubač, J.: New stable isotope geochemical approach documents grain production and manuring in the High Middle Ages, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20000, https://doi.org/10.5194/egusphere-egu24-20000, 2024.

EGU24-20312 | ECS | PICO | GM5.4

Plant-wax biomarkers and their isotopes reveal complex relationships between climate, vegetation and fire during collapse of Indus Valley Civilization 

Deepak Jha, James Blinkhorn, Valerie Schwab-Lavric, Verónica Zuccarelli Freire, Jana Ilgner, Hema Achyuthan, Nicole Boivin, Ravindra Devra, S. Yoshi Maezumi, Gerd Gleixner, Patrick Roberts, and Michael Petraglia

Climate variability, especially monsoonal rainfall, has significantly shaped habitable areas for human populations in South Asia in the past just as it does today. Instances of climate-driven social disruptions and population movements are evident worldwide, as evidenced for example in the Classic Maya and the Indus Valley Civilization (IVC). However, climate change can manifest in very different ways in terms of vegetation and fire regimes, with important implications for regional environmental histories as well as socio-political patterns. As such, it is essential to develop a comprehensive understanding of the intricate interplay between climate, vegetation, fire, and archaeological evidence relating to changes in settlement patterns and continuities. Insights derived from such studies offer a foundation to explore and comprehend present and future human-environment interactions.

Here we present multi-proxy time-series datasets derived from a 2.25-meter geological trench known as ‘Jankipura,’ located within the semi-arid Thar Desert. Jankipura, located near Didwana Lake, holds prehistoric importance, being surrounded by major archaeological sites in the Thar Desert. It is also a part of the Didwana Palaeolithic Complex, surrounded by the IVC, Jodhpura-Ganeshwar, and Ahar-Banas cultural regions. The chronology of the Jankipura trench is constructed based on four 14C AMS dates ranging from 183 to 4656 cal yr. BP, aligning with the Mature phase of the IVC – a period characterized by population migration and a severe reduction in settlement density. Our analysis encompasses measurements of sediment total organic and bulk carbon isotope (d13Cbulk) composition, alongside examinations of plant-wax molecular distributions (n-alkanes and fatty acids). Additionally, we analyzed the δ13C and δ2H values of long-chain n-alkanes (C27, C29, C31, and C33) and fatty acids (C26, C28, C30, and C32) extracted from the sediment samples.

Our study also involved the assessment of macro-charcoal concentrations (>125 µm, differentiating grass from wood) to reconstruct the climate-vegetation-fire relationships during and after a major period of disruption of the IVC. The findings highlight an dry phase between 4656 and 2932 cal yr. BP, characterized by a mixed C3-C4 vegetational landscape with limited fire episodes. A significant fire episode took place during the period from 2932 to 1960 cal yr. BP, suggesting dry conditions supported by abundant C4 vegetation. Between 1960 and 183 cal yr. BP, three minor fire events occurred amid fluctuating rainfall conditions and a landscape dominated by mixed C3-C4 vegetation. The identified macro-charcoal predominantly comprised woody fragments over grass fragments. Notably, an increasing trend in isotope values, reaching its peak in macro-charcoal, is observed between 183 cal yr. BP and the present, signifying increased aridity compared to the mature phase of the IVC.

Although the study is based on a single trench, our observation of a weak relationship between vegetation and fire suggests that the reconstructed fire events may have originated from anthropogenic activities. This sheds light on the significance of vegetation, especially the utilization of wood, during the Mature phase of the IVC. We recommend generating more records from this region to better comprehend the spatio-temporal interaction of the IVC population with the environment.

How to cite: Jha, D., Blinkhorn, J., Schwab-Lavric, V., Zuccarelli Freire, V., Ilgner, J., Achyuthan, H., Boivin, N., Devra, R., Maezumi, S. Y., Gleixner, G., Roberts, P., and Petraglia, M.: Plant-wax biomarkers and their isotopes reveal complex relationships between climate, vegetation and fire during collapse of Indus Valley Civilization, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20312, https://doi.org/10.5194/egusphere-egu24-20312, 2024.

EGU24-21345 | ECS | PICO | GM5.4

Holocene relative sea-level changes and coastal dynamics in Southern Latium, Italy: an interdisciplinary investigation  

Claudia Caporizzo, Giuseppe Aiello, Vincenzo Amato, Pietro P.C. Aucelli, Diana Barra, Andrea Gionta, Giuseppe Corrado, Gaia Mattei, Gerardo Pappone, Roberta Parisi, Paola Petrosino, Marcello Schiattarella, and Matteo Vacchi

Understanding the historical changes in Relative Sea Level (RSL) and coastal responses in stable regions is crucial for unraveling the intricate relationship between natural dynamics and human adaptation. This interdisciplinary study seeks to explore the Holocene sea-level fluctuations in the stable area of Southern Latium, shedding light on how past societies adapted to coastal changes.
The study area, located in the historical Sinus Formianus, between the Fondi and Garigliano coastal plains, played a key role in ancient times. Formia, a strategic monitoring point for the Tyrrhenian Sea, was a thriving commercial hub during Roman occupation. During this period, the coastal stretch 
from Formia to Gaeta witnessed substantial urbanization, leaving behind well-preserved remnants visible today in submerged or semi-submerged coastal structures along the present shoreline.

This study reconstructs the Holocene morpho-evolution and RSL changes in the study area by creating a geodatabase following international guidelines for sea-level markers (SLMs). A comprehensive dataset of 52 SLMs was compiled from direct geoarchaeological measurements, stratigraphic and palaeoecological interpretations of new borehole data, and reinterpreting bibliographic information. Archaeological site selection involved analyzing bibliographic, cartographic, and video materials for ruins' details and dating. Additionally, public institutions provided access to an unpublished stratigraphic dataset from five deep boreholes drilled between Fondi and Formia plains in 2023. 
Three samples were collected from the stratigraphic columns of the analyzed boreholes in Formia Plain and dated using the radiocarbon dating technique. One sample, derived from a lagoonal deposit, presented an age exceeding the dating technique's accuracy range and older than 54 ka BCE. Despite this, the dating provided valuable information on the initiation of backshore formation. The other two dated samples, derived from a second drilling and collected inside layers of peat deposits, were interpreted as Terrestrial Limiting Points (TLPs) defining an upper limit of -4.20 m MSL for the RSL position at about 7.5 ka BP.
Accordingly, based on the collected data, between 8.0 and 7.5 ka BP, the sea level in the study area rose from -23 to -5 m at a rate of 25 mm/yr. Subsequently, the rate slowed to less than 5 mm/yr, stabilizing at its current position. In particular, the results coming from the geoarchaeological surveys suggest that the local sea level during the Roman period (I century BCE) was no higher than - 0.55 ± 0.29 m MSL. 
Overall, the RSL data included in the geodatabase highlights the tectonic stability of this sector during the last 2.0 ka, testified by the position of the SLMs in accordance with the GIA models and supported by the determination of average vertical ground movements rates of -0.017 ± 0.23 mm/yr.

Finally, the interplay between new data from geoarchaeological surveys, bibliographic sources, and LiDAR-based geomorphological analysis allowed the creation of a paleogeographic scenario for the study area in the 1st century CE. This highlights the significant landscape modifications induced by anthropic activities during that period.

How to cite: Caporizzo, C., Aiello, G., Amato, V., Aucelli, P. P. C., Barra, D., Gionta, A., Corrado, G., Mattei, G., Pappone, G., Parisi, R., Petrosino, P., Schiattarella, M., and Vacchi, M.: Holocene relative sea-level changes and coastal dynamics in Southern Latium, Italy: an interdisciplinary investigation , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21345, https://doi.org/10.5194/egusphere-egu24-21345, 2024.

SSS4 – Soil Biology, Microbiology and Biodiversity

EGU24-105 | ECS | Orals | SSS4.1

Liming effects on microbial carbon use efficiency and its potential consequences for soil organic carbon stocks 

Julia Schroeder, Claudia Damatirca, Tobias Bölscher, Claire Chenu, Lars Elsgaard, Christoph C. Tebbe, Laura Skadell, and Christopher Poeplau

The allocation of metabolised carbon (C) between soil microbial growth and respiration, i.e. C use efficiency (CUE) is crucial for SOC dynamics. The pH was shown to be a major driver of microbial CUE in agricultural soils and therefore, management practices to control soil pH, such as liming, could serve as a tool to modify microbial physiology. We hypothesised that raising soil pH would alleviate CUE-limiting conditions and that liming could thus increase CUE, thereby supporting SOC accrual. This study investigated whether CUE can be manipulated by liming and how this might contribute to SOC stock changes. The effects of liming on CUE, microbial biomass C, abundance of microbial domains, SOC stocks and OC inputs were assessed for soils from three European long-term field experiments. Field control soils were additionally limed in the laboratory to assess immediate effects, accounting for lime-derived CO2 emissions (δ13C signature). The shift in soil pHH2O from 4.5 to 7.3 with long-term liming reduced CUE by 40%, whereas the shift from 5.5 to 8.6 and from 6.5 to 7.8 was associated with increases in CUE by 16% and 24%, respectively. The overall relationship between CUE and soil pH followed a U-shaped (i.e. quadratic) curve, implying that in agricultural soils CUE may be lowest at pHH2O = 6.4. The immediate CUE response to liming followed the same trends. Interestingly, liming increased microbial biomass C in all cases. Changes in CUE with long-term liming contributed to the net effect of liming on SOC stocks. Our study confirms the value of liming as a management practice for climate-smart agriculture, but demonstrates that it remains difficult to predict the impact on SOC stocks due its complex effects on the C cycle.

How to cite: Schroeder, J., Damatirca, C., Bölscher, T., Chenu, C., Elsgaard, L., Tebbe, C. C., Skadell, L., and Poeplau, C.: Liming effects on microbial carbon use efficiency and its potential consequences for soil organic carbon stocks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-105, https://doi.org/10.5194/egusphere-egu24-105, 2024.

EGU24-1301 | ECS | Posters on site | SSS4.1

Thermodynamic indicators decipher the molecular composition of organic matter in phase transition 

Philipp Maurischat, Michael Seidel, Oliver Donnerhack, Patrick Liebmann, and Georg Guggenberger

With promising methods such as ultrahigh-resolution mass spectrometry (FT ICR MS), soil scientists have more opportunity than ever to gain a comprehensive picture of the composition and transformation of soil organic matter (SOM).  With soils as central mediators for carbon capture and storage this understanding is key when it comes to tackling major challenges, such as climate change and soil health. However, as novel techniques are often imported from other scientific fields, the evaluation and interpretation of data with regard to the heterogeneous pedosphere often remains a major challenge. For FT ICR MS, several commonly used indices were developed from empirical observations of the deep ocean. While these indices seem statistically transferable from ocean DOM to the terrestrial realm, there is legitimate concern that no causality ultimately ensures this applicability. Indices are needed that allow interpretation of the data from a conceptual perspective. Viewing SOM as a thermodynamically driven mediator of energy fluxes in the soil food web provides an opportunity to put a foot on the ground of data analysis with more general applicability. We aim to show that bioenergetic and thermodynamic molecular indices allow a better understanding of soil organic matter transformation by comparing FT ICR MS samples from complex, mixed sources and single source endmembers.

We investigated the molecular composition of stream DOM and soil leachates along a biome gradient between alpine meadow and alpine steppe, including a chronosequence of degradation in the southern Tibetan Nam Co watershed. Our results suggest a certain match of commonly used DOM molecular indices, such as the ‘island of stability‘, the ‘degradation index‘ and the ‘terrestrial index‘, applied to marine settings for terrestrial DOM and SOM. However, when comparing SOM and DOM phase transitions within endmember sources, we noted inconsistencies. In contrast, indicators representing the bioenergetics of organic matter composition, such as the ‘nominal oxidation state of carbon’ and the ‘Gibbs free energy for carbon oxidation’, show good agreement for the key phase transition between SOM and DOM. These results provide reasonable evidence in line with conceptual understanding, such as more oxidised DOM and SOM in degraded areas and generally less oxidised molecular formulae in mainly allochthonous stream DOM compared to extracted SOM. Our data support the notion that bioenergetic and thermodynamic indicators may be a way forward to better understand the complex nature of organic matter transformation in soils with FT ICR MS. These indicators can serve as important building blocks for molecular fingerprinting.

How to cite: Maurischat, P., Seidel, M., Donnerhack, O., Liebmann, P., and Guggenberger, G.: Thermodynamic indicators decipher the molecular composition of organic matter in phase transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1301, https://doi.org/10.5194/egusphere-egu24-1301, 2024.

Chemical quality of plant residues, which are the source of dissolved organic C (DOC), determine the molecular structure, notably functional group polysaccharides in DOC, and the origins of DOC-polysaccharide, which transitioned from plant- to microbial-derived as decomposition progressed. The microbial-derived DOC-polysaccharides contribute to soil organic C (SOC) stabilization, but what factor associated with the residue chemical quality regulates the origin of the DOC-polysaccharides remains unknown. Balanced DOC and dissolved N (DN) (DOC-and-DN) stoichiometry of microbial substrates as indicated by DOC-to-DN ratio enhances microbial C use efficiency (CUE). The CUE indicates the production of microbial-derived DOC compounds. We hypothesized that DOC-and-DN stoichiometry in soils receiving plant residues was a key factor controlling the origin of DOC-polysaccharides. The objectives of this study were to determine 1) DOC-to-DN ratio during decomposition, 2) relationships of DOC-to-DN ratio and microbial metabolic quotient (qCO2 - inverse of CUE), and 3) relationships of qCO2 and DOC-to-DN ratio with DOC-polysaccharides. This study employed data from year 13 of a long-term field experiment on the effect of annual application of varying quality residues on decomposition processes in sandy soils. During the early stage of decomposition (week 0-2), DOC-to-DN ratio of N-rich groundnut stover (GN) residue decreased, in contrast to low-N rice straw (RS), and dipterocarp leaf litter (DP) and medium-N tamarind leaf+petiole litter (TM). During the intermediate stage (week 2-8), GN and RS had increasing ratios, as opposed to DP and TM. Groundnut-treated soil had lower average ratio (6.8±2.6) than TM, RS and DP (10.7±4.4, 12.1±5.4, 14.1±7.2, respectively). Positive influences of the ratio on qCO2 in the three medium-to-low-N soils (R2 = 0.60** - 0.74**) indicated that the ratio had significant control on the CUE. The qCO2, in turn, had significant influence (non-linear relationship) on DOC-polysaccharides (R2 = 0.30*).  In the early stage (high qCO2), it decreased (indicating the increase of CUE) corresponding to the decreases in DOC-polysaccharides indicating that these were plant-derived. The qCO2 decreased further beyond the threshold of 0.00026 mg CO2-C kg-1 microbial biomass C h-1 whichmarked the beginning of the intermediate stage (low qCO2), corresponding to an increase in microbial-derived DOC-polysaccharides.  This increase signified the change in their origin. Negative influence of DOC-to-DN ratio on DOC-polysaccharides (R2 = 0.36*) during the intermediate stage showed that the increased ratios caused the decreases in DOC-polysaccharides. Our results identified DOC-and-DN stoichiometry in residues-treated soils as a prominent factor controlling the origin of the DOC-polysaccharides. Imbalanced DOC-and-DN stoichiometry in low-N residues, i.e., higher DOC-to-DN ratios than microbial biomass C-to-N ratios, brought about the decrease in microbial-derived DOC-polysaccharides during the later stage. Soil management via organic inputs requires careful consideration of changes in DOC-and-DN stoichiometry which can affect SOC accumulation.

How to cite: Poosathit, R. and Vityakon, P.: Stoichiometry of dissolved organic matter controls the origin of polysaccharides in dissolved organic carbon in sandy soils receiving contrasting-quality plant residues, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2590, https://doi.org/10.5194/egusphere-egu24-2590, 2024.

Microbial carbon use efficiency (CUE) is a vital physiological parameter in assessing soil carbon turnover. Yet, how microbial communities with distinct trophic strategies regulate soil microbial CUE has remained elusive. Based on the oligotrophic: copiotrophic framework, we here explored the role of microbial taxa with different trophic strategies in mediating microbial CUE (determined by a 13C-labeling approach) along the vegetation primary succession in the Hailuogou glacier retreat area of the southeastern Tibetan Plateau. Soil microbial CUE ranged from 0.54 to 0.72 (averaging 0.62 ± 0.01 across all samples), increasing markedly along the vegetation succession. Microbial assemblies with distinct trophic strategies were crucial regulators of soil microbial CUE. Specifically, microbial CUE increased with microbial oligotroph: copiotroph ratios, with oligotroph-dominated stages having a higher microbial CUE than copiotroph-dominated ones. The prevalence of oligotrophic members would therefore be linked to the high soil microbial CUE at late successional stages. Given that oligotrophs predominate in soils with more recalcitrant carbon and because of their higher microbial CUE, we speculate that oligotrophs are likely to promote carbon sequestration in soils. In addition, the responses of soil microbial CUE to fungal oligotroph: copiotroph ratios were stronger than to bacterial ones. Fungal taxa may play a particularly pronounced role in shaping microbial CUE relative to bacterial members. Overall, our results highlighted close associations between microbial trophic strategies and CUE and provide direct evidence regarding how microbial trophic strategies regulate soil microbial CUE. This study is a significant step forward for elucidating the physiological mechanisms regulating microbial CUE and has significant implications for understanding microbial-mediated carbon cycling processes.

How to cite: Ma, S., Zhu, W., Wang, W., Li, X., Sheng, Z., and Wanek, W.: Microbial assemblies with distinct trophic strategies drive changes in soil microbial carbon use efficiency along vegetation primary succession in a glacier retreat area of the southeastern Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3903, https://doi.org/10.5194/egusphere-egu24-3903, 2024.

EGU24-5128 | ECS | Posters on site | SSS4.1

Identification of plant, bacterial and fungal necro mass markers in soil organic matter via ultrahigh resolution mass spectrometry 

Konstantin Stumpf, Carsten Simon, and Oliver Lechtenfeld

Soil organic matter (SOM) plays a central role in the global carbon cycle, influencing for example soil fertility, biodiversity, and erosion. Recent theories predict that SOM is a blend of plant metabolites and their breakdown products, perpetually undergoing recycling and transformation driven by soil organisms such as fungi and bacteria. However, our understanding of SOM remains incomplete due to its complex chemical composition. Particularly, we lack distinct metabolite information for the majority of these compounds or sources, hampering the analysis of SOM structure, it’s genesis, as well as mechanistic understanding of soil processes. Non-targeted analysis by ultrahigh resolution mass spectrometry, foremost Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), has substantially advanced our understanding of organic matter complexity in soils and allows to gain a representative picture through the use of liquid chromatography (LC). To address the above knowledge gaps, we employed LC-FT-ICR-MS for the investigation of three primary types of necromass (maize litter, bacterial and fungal necromass) extracts, as well as aqueous SOM extracts obtained from arable topsoils (2 – 20 cm depth). Water-soluble SOM fractions can be seen as a transition state between higher molecular weight structures in soils like bio- or necromass and its decomposition end products like carbon dioxide or methane.

We employed an LC methodology capable of separating dissolved organic matter (DOM) across a broad polarity spectrum, including highly polar compounds that are typically lost during commonly employed solid-phase extraction. Our results show significant differences between farmyard manure-amended (FYM) and unamended (UF) soil DOM according to its nominal carbon oxidation state (NOSC), saturation and molecular mass, that are most prominent for the highly polar fraction of SOM. We assigned intricate markers derived from bacterial, fungal or plant necromass that indicated higher potential necromass contribution to FYM than UF soil DOM, in line with higher microbial activity in these soils. We found that necromass markers contribute most to the CHNO formula class in soil DOM, thereby explaining structural differences between FYM and UF samples.

The outcomes of our research represent an initial stride towards the identification of novel molecular markers intrinsic to soil DOM, its thermodynamic properties and N content. In the long term, these techniques will enable not only the detection of shifts in the molecular composition of soil DOM during substrate decomposition but also the recognition of alterations in structural motifs that are associated with specific necromass types. This advancement holds promise for enhancing our understanding of soil DOM dynamics and therefore may hold important implications for soil and ecosystem management.

How to cite: Stumpf, K., Simon, C., and Lechtenfeld, O.: Identification of plant, bacterial and fungal necro mass markers in soil organic matter via ultrahigh resolution mass spectrometry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5128, https://doi.org/10.5194/egusphere-egu24-5128, 2024.

EGU24-5432 | ECS | Orals | SSS4.1

Quantifying amino acid and amino sugar biomarkers in a single approach to estimate necromass from soil archaea, bacteria, fungi, and plants 

Erika Salas, Markus Gorfer, Dragana Bandian, Stephanie A. Eichorst, Hannes Schmidt, Julia Horak, Simon K.-M. R. Rittmann, Christa Schleper, Barbara Reischl, Thomas Pribasnig, Jan Jansa, Christina Kaiser, and Wolfgang Wanek

Soil organic matter is the largest carbon (C) pool in terrestrial ecosystems, and it is largely composed of microbial necromass. Microbes contribute to the long-term C storage in soils by incorporating C from plants into their biomass and, consequently, microbial necromass becomes stabilized mostly in mineral associated organic matter. So far, most studies have focused on tracing microbial necromass using amino sugar biomarkers, while plant contributions to soil organic matter are predominantly traced using lignin or long-chain alkanes. Glucosamine and muramic acid are amino sugars commonly used as biomarkers of fungal and bacterial necromass, respectively. Amino acids, such as D-enantiomers and non-proteinogenic amino acids have also been used though rarely as microbial and/or plant necromass tracers. For instance, meso(D,L)-diaminopimelic acid can be found in the peptidoglycan peptide chain of gram-negative bacteria, while hydroxyproline is commonly found in glycoproteins of plant cell walls. Currently, only very few studies have measured amino sugars alongside primary and secondary amino acids as biomarkers of plant and microbial necromass. In this study, we propose a new method that allows the simultaneous exploration of microbial and plant residue biomarkers using a single run via 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatization, followed by ultra-high performance liquid chromatography (UHPLC) and Orbitrap high resolution mass spectrometry. For this, we analysed 121 species of archaea, bacteria, fungi and plants. We were able to quantify amino acids and amino sugar biomarkers in the biomass of all taxonomic groups, as well as compare how these biomarker contents varied between broad taxonomic groups. We confirmed the biomarker potential of non-proteinogenic amino acids and amino sugars using indicator species analysis as well as supervised multivariate approaches, such as random forest and partial least squares discriminant analysis (PLS-DA). Our results showed that hydroxyproline is a biomarker specific for plants, while L,L-diaminopimelic acid can be used alongside muramic acid as biomarkers specific for bacteria. Talosaminuronic acid represents a biomarker specific for archaea, while glucosamine was a biomarker indicative of archaea, bacteria and fungi, being absent in plants. Our results showcase an unparalleled approach to trace both plant and microbial contributions to soil organic matter which will help improve our understanding of how different organic matter sources contribute to soil carbon formation and stabilization. This approach also allows the quantitation of plant versus microbial contributions to the continuum from litter decomposition to soil organic matter formation though microbial processing, the contribution of plant, fungal and bacterial organic matter to mineral-associated organic matter (MaOM) versus particulate organic matter (POM), and to soil macro- and microaggregate formation.

How to cite: Salas, E., Gorfer, M., Bandian, D., Eichorst, S. A., Schmidt, H., Horak, J., Rittmann, S. K.-M. R., Schleper, C., Reischl, B., Pribasnig, T., Jansa, J., Kaiser, C., and Wanek, W.: Quantifying amino acid and amino sugar biomarkers in a single approach to estimate necromass from soil archaea, bacteria, fungi, and plants, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5432, https://doi.org/10.5194/egusphere-egu24-5432, 2024.

EGU24-5842 | Posters on site | SSS4.1

Microbial Mechanisms Governing the Reduction of CH4 Emission in Coastal Wetlands under Elevated CO2 Conditions 

Hojeong Kang, Yerang Yang, Genevieve Noyce, and Patrick Megonigal

Elevated levels of CO2 are known to enhance CH4 emissions from wetlands due to the combined effects of increased plant biomass and greater carbon availability for methanogens. However, recent findings have demonstrated a decrease in CH4 emissions under elevated CO2 conditions in coastal wetlands, primarily attributed to the oxygen priming effect. Despite this knowledge, direct evidence elucidating the microbial processes underlying this reduction remains elusive. In this study, we employed mRNA-based analysis to identify the active microorganisms responsible for CH4 dynamics.

Under elevated CO2 conditions, we observed lower methanogen abundances compared to ambient CO2 levels, suggesting that the oxygen priming effect inhibited the activity of methane-producing microbes. Intriguingly, no significant differences were found for methanotrophs, whose impact on wetland sediments may be minimal. Additionally, there was no notable change in the abundance of dsrA genes, indicating that the reduction in CH4 emission was not a result of carbon substrate competition with sulfate reducers. This research contributes valuable insights into the microbial mechanisms governing CH4 emissions in coastal wetlands under elevated CO2 conditions.

How to cite: Kang, H., Yang, Y., Noyce, G., and Megonigal, P.: Microbial Mechanisms Governing the Reduction of CH4 Emission in Coastal Wetlands under Elevated CO2 Conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5842, https://doi.org/10.5194/egusphere-egu24-5842, 2024.

EGU24-6079 | Posters on site | SSS4.1

Spatial modelling of microbial interactions and carbon dynamics in soils 

Xavier Raynaud and Naoise Nunan

Soil hosts a large diversity of microorganisms, that are responsible for the transformation, storage in the soil and release of carbon (C) to the atmosphere. These transformations of C are realized by individual cells that all belong to a metabolic interaction network, i.e. a network of interactions within which cells from different species compete for, transform and exchange resources. Soil C respiration, soil C storage and soil Carbon Use Efficiency are all outcomes of the functioning of this metabolic interaction network. Understand the functioning of metabolic interaction networks is thus essential to understand the cycling of C in soils.

We present a spatially explicit, individual based, model of microbial interactions in which cells are able to take up some resources, transform them into other products, which are released into the environment. Each cell is assumed to have a spatially limited impact on their environment. In this contribution, using different model parametrizations, we explore the interplay between spatial distribution of cells, resource diversity and microbial diversity, and show how the spatial distribution of cells can be a strong modulator of the functioning of metabolic networks in soils.

How to cite: Raynaud, X. and Nunan, N.: Spatial modelling of microbial interactions and carbon dynamics in soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6079, https://doi.org/10.5194/egusphere-egu24-6079, 2024.

EGU24-6520 | Orals | SSS4.1

Expanding Understanding: Investigating the Information Value of Calorespirometric Ratio in Dynamic Processes of Soil Microbial Growth Using Calorimetry 

Thomas Maskow, Shiyue Yang, Eliana Di Lodovico, Alina Rupp, Christian Fricke, Anja Miltner, and Matthias Kästner

The preservation of soil services and functions is sustained by the catalytic activity of microbial communities. These communities use energy and carbon – especially for microbial growth – from the transformation of organic matter (OM).  A fraction of this OM is assimilated as carbon source for growth (anabolism). Another fraction is oxidized and the resulting electrons are transferred to various terminal acceptors to derive the energy for growth (catabolism). The distribution of carbon and energy into anabolism and catabolism determines carbon use efficiency (CUE) and energy use efficiency (EUE). Accurate quantification of the relationships between carbon and energy fluxes relies on key parameters like the metabolic heat (Qm),  calorespirometric ratio (CR), carbon dioxide evolution rate (CER), the apparent specific growth rate (μapp), and the degree of anaerobicity (ηA).

However, determining these parameters faces challenges at technical (sample size and instrument sensitivity) and experimental (thermal disturbance, sample aeration) levels impacting the precise quantification of energy and carbon flux relationships. To address these challenges under controlled conditions, we examined microbial turnover processes in a model arable soil amended with a readily metabolizable substrate (glucose). We utilized three commercial isothermal microcalorimeters (IMC)  with volume-related thermal detection limits (LODV) ranging from 0.05 to 1 mW L-1.

Comparison between three IMCs were conducted to figure out the influence of LODV on measuring accuracy. Calorimetric experiments (half ampoules were closed and half were aerated for 5 minutes on selected days) were compared to explore the effect of oxygen limitation and thermal perturbation on the calorimetric signal. CER was monitored by measuring the additional heat resulting from CO2 absorption in NaOH solution used as CO2 trap. The range of errors associated with calorimetrically derived μapp, Qm, and CR was determined experimentally and compared with the requirements for quantifying CUE and ηA from a theoretical perspective.

Significant differences in Qm and µapp were observed between IMCs which have the lowest and highest LODV. IMC with the lowest LODv provided the most accurate results. Opening ampoules for gas exchange did not significantly impact Qm. However, regular ampoule opening during calorimetrically derived CER measurements led to notable measurement errors for CER due to strong thermal perturbation of the signal. If established models are used to calculate CUE and ηA from CR, unrealistically high values are obtained and the accuracy of CR do not fit to the requirements.

There are two ways to cope with this problem. On the one hand, new thermodynamic balance models need to be developed that dispense with the error-prone CR value. On the other hand, new calorespirometric methods must be developed to determine the CR value more reliably. Initial results for both approaches will be presented. 

How to cite: Maskow, T., Yang, S., Di Lodovico, E., Rupp, A., Fricke, C., Miltner, A., and Kästner, M.: Expanding Understanding: Investigating the Information Value of Calorespirometric Ratio in Dynamic Processes of Soil Microbial Growth Using Calorimetry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6520, https://doi.org/10.5194/egusphere-egu24-6520, 2024.

EGU24-7984 | ECS | Orals | SSS4.1

The potential and challenges of dynamic models for investigating microbial processes in soil using the Calorespirometric Ratio 

Martin-Georg Endress, Fatemeh Dehghani, Evgenia Blagodatskaya, and Sergey Blagodatsky

Soil microbes obtain carbon (C), energy and nutrients from their environment to grow and to sustain themselves. Some of the matter and energy entering microbial metabolism leaves the soil system, e.g., as CO2 and heat, while some is recycled via microbial death and turnover. All these matter and energy flows are intimately coupled according to stoichiometric relationships and the laws of thermodynamics, and unraveling the details of this coupling is essential for our understanding of soil functions mediated by microbes such as nutrient cycling and carbon storage.

The ratio of heat to CO2 release, the so-called Calorespirometric Ratio (CR), obtained from soil incubation experiments with substrate amendment has been shown to hold valuable information about the major active metabolic pathways of the microbial community and the C and energy use efficiency. However, due to the complex and obscure nature of the soil system, measured CR values always require mechanistic models of the underlying processes for proper interpretation.

Here, we illustrate both the potential and the limitations of simple dynamic bioenergetic models for explaining experimental CR data and formulating testable hypotheses. For example, we highlight how such models may reveal shifts in metabolic pathways during growth and give clues about the dominant microbial sources of CO2 and heat in the absence of easily degradable C substrates, e.g., during maintenance and turnover, based on observed temporal CR patterns.

At the same time, the CR framework and associated models face important challenges. First, the CR represents the black box sum of all heat and COproducing processes, and this complication can lead to different conclusions being drawn from the same data. Based on experiments with glucose amended soil, we explain how the CR pattern observed during the retardation phase after glucose depletion might be interpreted as resulting from either the decomposition of SOM or the formation of necromass or a combination of both. While this challenge prevents a definitive interpretation based on CO2 ­and heat data alone, it can nonetheless play a vital role in informing and designing future experiments.

Second, evaluating the temporal patterns of the CR relies on synchronous measurements of heat and CO2. In contrast, these two quantities are often measured separately in experiments, and their different diffusion rates may also cause a delay of CO2 relative to heat in the case of simultaneous measurement. We demonstrate that even small shifts in the relative timing can cause a characteristic artificial pattern in observed CR data, with initially high CR values followed by a pronounced drop. We finally indicate how this issue may be accounted for in the structure of the dynamic models.

In summary, we present two major challenges – the black box nature of CR and shifts in relative timing – that arise from the interpretation of experimental rates of heat and CO2 release using mechanistic dynamic models, and we show how these issues may be addressed, and even leveraged, to advance our understanding of microbial processes in soil.

How to cite: Endress, M.-G., Dehghani, F., Blagodatskaya, E., and Blagodatsky, S.: The potential and challenges of dynamic models for investigating microbial processes in soil using the Calorespirometric Ratio, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7984, https://doi.org/10.5194/egusphere-egu24-7984, 2024.

EGU24-8685 | ECS | Orals | SSS4.1

Insights into the role of the environmental setting versus microbial actors for soil carbon cycling 

Daniel Wasner, Joerg Schnecker, Xingguo Han, Aline Frossard, Erick Zagal Venegas, and Sebastian Doetterl

Soil microbes perform important functions in the soil organic carbon (SOC) cycle and soil microbial decomposition activity is a major determinant of the carbon budget of a soil. It is well-established that soil microbial physiology is directly affected by temperature and moisture. However, it is less clear to what extent the environmental setting (i.e. long-term climatic conditions, soil physicochemistry) vs. the microbial actors (i.e. soil bacterial and fungal community composition) control the cycling of SOC in the absence of strong direct physiological constraints such as temperature and moisture limitation.

To address this knowledge gap, we used 35 grassland topsoils (0 – 10 cm) from 10 WRB major soil groups along a north-south transect in Chile, which ranged from arid steppe to tundra. We compiled climatic data and relevant physicochemical soil properties, together with an in depth characterization of OM quality. We then incubated the soils for 1 week in conditions favorable for microbial activity (20 °C, 50 % of water holding capacity). After incubation, we quantified soil microbial carbon and nitrogen, enzyme kinetics of three groups of relevant extracellular enzymes, basal heterotrophic respiration as well as microbial growth rates and carbon use efficiencies by incorporation of 18O into DNA. In addition, we characterized the microbial actors by DNA extraction and Illumina barcoding of a region of the 16S rRNA gene (bacteria) and a section of the ITS region (fungi). Finally, to investigate how strongly the measured microbial SOC functions were linked with the environmental setting vs. the microbial actors, we applied three different cross-validated regression approaches.

The resulting data highlights the links between environment, microbial community composition and SOC cycle functions under conditions without direct temperature and moisture limitation. Our findings show that the environmental setting controlled the amount of microbial biomass, and in extension biomass dependent SOC cycle functions such as heterotrophic respiration. In  contrast, microbial community composition was a better predictor of SOC cycle functions that are independent of microbial biomass such as carbon use efficiency and relative microbial growth rates. These insights help to disentangle the roles of the environmental setting and the microbial actors in the context of microbial SOC cycle functions.

How to cite: Wasner, D., Schnecker, J., Han, X., Frossard, A., Zagal Venegas, E., and Doetterl, S.: Insights into the role of the environmental setting versus microbial actors for soil carbon cycling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8685, https://doi.org/10.5194/egusphere-egu24-8685, 2024.

EGU24-8948 | Orals | SSS4.1

Thermodynamic control of microbial turnover of organic substrates in soils 

Anja Miltner, Matthias Kästner, Thomas Maskow, Marcel Lorenz, and Sören Thiele-Bruhn

Microbial turnover of organic substrates is a key process in soil organic matter formation and turnover. As microorganisms require both carbon and energy for growth and maintenance, carbon and energy fluxes in soils are tightly coupled. On the level of cellular metabolism, the substrates have to be allocated to catabolism and anabolism according to the requirements of the cells. In the soil system, additional processes have to be considered such as multiple substrate use, recycling of biomass components, interaction between different organisms and abiotic processes. As most of the energy flux in catabolism is created by the reduction of the terminal electron acceptors, the availability of the electron acceptors strongly affects carbon use efficiency and energy use efficiency. Here, we present a thermodynamic concept that combines experimental approaches of calorimetry and turnover mass balances paving the way for a better understanding of microbially mediated organic matter turnover and stabilization in soil.

Mass balances in soil systems need to be set up for exemplary substrates using isotope labelled compounds. They should be combined with information on energy fluxes, which can be obtained using calorimetric methods for thermodynamic calculations. Recently, calorimetric methods have been introduced into soil studies, e.g. differential scanning calorimetry or isothermal reaction calorimetry. Alternatively, enthalpies of combustion or formation must be known or estimated, e.g. based on the nominal oxidation state of the substrates and reaction products. All of these methods have their strengths and weaknesses, which need to be considered when assessing and interpreting the results. From a thermodynamic perspective, it is crucial to define the system boundaries and to use thermodynamic state variables such as reaction enthalpy, entropy and Gibbs free energy. If applied properly, the predictive power of thermodynamics can be fully utilized for process evaluation. In particular, this approach will enable us to identify whether a particular process is thermodynamically feasible or not under the given conditions.

In summary, linking mass balances and thermodynamics will allow us to better understand and predict soil organic matter turnover and sequestration.

How to cite: Miltner, A., Kästner, M., Maskow, T., Lorenz, M., and Thiele-Bruhn, S.: Thermodynamic control of microbial turnover of organic substrates in soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8948, https://doi.org/10.5194/egusphere-egu24-8948, 2024.

EGU24-9988 | Orals | SSS4.1

It’s the little things that count – how microbial dynamics affect simulation results of the systemic soil model BODIUM 

Sara König, Ulrich Weller, Thomas Reitz, Julius Diel, Ute Wollschläger, and Hans-Jörg Vogel

Mechanistic simulation models are essential tools for predicting soil functions such as nutrient cycling, water filtering and storage, productivity, and carbon storage as well as the complex interactions between these functions. Most soil functions are driven or affected by soil microorganisms. Yet, biological processes are often neglected in soil function models or only implicitly considered in form of unspecific, effective rate parameters. This can be explained by the high complexity of the soil ecosystem with its dynamic and heterogeneous environment, and by the range of temporal and spatial scales at which these processes take place.

We integrated different microbial processes and feedbacks into our systemic soil model BODIUM (König et al., 2023) and tested the sensitivity of soil functions such as productivity and nutrient cycling to these microbial aspects at the scale of soil profiles. This includes flexible C:N ratios, carbon use efficiency, nitrogen fixation, feedback with root exudation, and the dynamics of different functional groups such as fungi and bacteria. We observed a high sensitivity of our simulation outcomes to microbial parameters related to the microbial component, such as the exudation rate or fungal/bacterial resistance to environmental conditions. This shows the high relevance of microbial processes for soil functions at the field scale, but also indicates that the process description should be further improved.  In process-based models, a high sensitivity of parameters is often a sign for an instable process description relying too much on site-specific calibration instead of mechanistic understanding.

We will discuss how to improve this, but also further extensions, including an approach that accounts for the spatial distribution of microorganisms within the pore space.

 

König, S., Weller, U., Betancur-Corredor, B., Lang, B., Reitz, T., Wiesmeier, M., Wollschläger, U., & Vogel, H.-J. (2023). BODIUM—A systemic approach to model the dynamics of soil functions. European Journal of Soil Science, 74(5), e13411. https://doi.org/10.1111/ejss.13411

How to cite: König, S., Weller, U., Reitz, T., Diel, J., Wollschläger, U., and Vogel, H.-J.: It’s the little things that count – how microbial dynamics affect simulation results of the systemic soil model BODIUM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9988, https://doi.org/10.5194/egusphere-egu24-9988, 2024.

EGU24-10414 | ECS | Posters on site | SSS4.1

Kill’em all? Interactions of predatory Myxobacteria with soil microbes – an in vitro and microcosm perspective on their role in the soil microbial food-web. 

Marc Piecha, Mandip Tamang, Michael Pester, Miriam van Bommel, Liliane Ruess, Morten Streblow, Jonas Woyde, Verena Groß, Mathilde Borg Dahl, Anne Reinhard, Haitao Wang, and Tim Urich

Soil is one of the most complex ecosystems, being an elementary source for food and resources needed by humankind. Despite its pivotal role in shaping and transforming this complex ecosystem, the soil microbial food-web is still poorly understood, which stands also true for matter and energy fluxes to higher trophic levels. A group of microbiome predators that has recently come more into focus are the Myxobacteria. They are famous for their predatory life style and might thus influence microbial death, growth and turnover in the soil environment via predation and an elaborate arsenal of secondary metabolites. To shed light on their role in the soil food-web, we investigated their predatory behavior and interactions with potential prey and predators using in vitro and in situ approaches. 

We tested the predation spectra in vitro with binary interaction assays of four different Myxobacteria (Haliangium ochraceum, Myxococcus virescens, Myxococcus fulvus, Corallococcus coralloides) with 16 different prey bacteria isolated from soils. The in vitro assay showed that each Myxobacterium had species-specific prey spectra. While Haliangium ochraceum and Myxococcus virescens showed the strongest predation effects on prey bacteria, the Corallococcus coralloides strain lysed the fewest prey bacteria. Taken together, not a single bacterium of the tested ones was resistant to lysis. Remarkably, also strains of the never before tested phyla Gemmatimonadota and Veruccomicrobiota can be lysed by Myxobacteria.

To shed light on (inter)actions of Myxobacteria with microbiome members in situ, a 32 day long microcosm study with an agricultural soil was performed, manipulating (a) the carbon source and (b) the grazing pressure of higher trophic levels, via the addition of fungivorous and bacterivorous nematodes, respectively. We applied quantitative PCR and quantitative metatranscriptomics microbiome profiling of 80 samples to shed light of the impact of aforementioned manipulations of C-source and grazers on the microbiome. Three-Domain SSU rRNA profiling showed that myxobacteria were highly abundant (up to 20%) in the used agricultural soil. In contrast, fungal abundance was much lower (1.5 %), while Protozoa, i.e. dominated by Amoebozoa and Cercozoa, were much more abundant than fungi (5 %). This suggests a microbial food-web dynamic in this agricultural soil that was heavily dominated by a bacterial, and not fungal channel. As expected, the abundance and composition of Myxobacteria were not affected by addition of fungivorous Nematodes, but it was surprising that this was also true for adding bacterivorous nematodes. We speculate that Myxobacteria reduce predation pressure of nematodes by utilizing secondary metabolites, while in turn killing enough prey bacteria for their own metabolism and growth. Consequently, the high abundance of Myxobacteria suggests a substantial contribution of their (predatory) activity on matter and energy fluxes in these microcosms. In a next step, we will integrate the metatranscriptomics results with organic matter and energy fluxes via flux-web modelling.

In conclusion, the in vitro assays showed that Myxobacteria killed all prey bacteria. This, together with their high abundance and resistance to predation from higher trophic levels in the in situ microcosm suggest Myxobacteria as important players in the agricultural soil food web.

How to cite: Piecha, M., Tamang, M., Pester, M., van Bommel, M., Ruess, L., Streblow, M., Woyde, J., Groß, V., Borg Dahl, M., Reinhard, A., Wang, H., and Urich, T.: Kill’em all? Interactions of predatory Myxobacteria with soil microbes – an in vitro and microcosm perspective on their role in the soil microbial food-web., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10414, https://doi.org/10.5194/egusphere-egu24-10414, 2024.

Electron transfer reactions are central to the transformation of energy in the environment and play an important role in biogeochemical element cycling. In soils, one of the main drivers of carbon cycling is the activity of organisms that utilize the energy stored in soil organic matter by extracting electrons from organic carbon and transferring them to various electron acceptors. Yet, our understanding of this process is incomplete and the response of the soil carbon pool to climate change remains one of the primary sources of uncertainty in projections of atmospheric carbon dioxide concentrations.

Here, I discuss how we can track electron transfer reactions in soil and relate them to bioenergetic descriptors to elucidate controls on soil heterotrophic respiration. I will use two examples from my research to illustrate this:  first, I show how to characterize the redox properties of solid phase electron acceptors on the basis of reaction thermodynamics. I focus on iron minerals which are abundant solid phase electron acceptors in many soils. Using mediated electrochemistry, I quantified differences in the reactivity and energetics of synthetic iron minerals and variations in mineral redox properties during microbial mineral reduction. Second, I demonstrate how we can assess effects of mineral redox reactivity on anaerobic microbial respiration in a redox-dynamic floodplain soil. To this end, I link the kinetics of electron transfer to electron acceptors to the rate of microbial carbon dioxide production in a series of soil incubations. These two examples provide inspiration on how to integrate the redox reactivities and energetics of electron acceptors into bioenergetic frameworks.

How to cite: Aeppli, M.: Electron transfer reactions and their role in soil carbon cycling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10556, https://doi.org/10.5194/egusphere-egu24-10556, 2024.

EGU24-11690 | Orals | SSS4.1

From energy to soil organic matter 

Yakov Kuzyakov, Chaoqun Wang, and Anna Gunina

We developed a new concept of soil organic matter (SOM) formation and microbial utilization of organic carbon (C) and energy: microorganisms use most of the organics entering the soil as energy rather than as a C source, while SOM accumulates as a residual by-product because the microbial energy investment in its decomposition exceeds the energy gain. So, the energy use efficiency (EUE) is at least as important as the carbon use efficiency (CUE). The microbial EUE depends on the nominal oxidation state of carbon (NOSC) of organic compounds, which is the exact proxy of energy content: The energy content per C atom (enthalpy of combustion) increases by 108 kJ mol−1 C per one NOSC unit. The NOSC in litter remaining by decomposition decreases, and the energy content increases. Consequently, the NOSC of the remaining compounds drops to −0.3 units, and the oxidation decreases due to the residual accumulation of aromatic and aliphatic compounds, and entombment of the necromass. Preferential recycling of energy-rich reduced (lipids, aromatics, certain amino acids, amino sugars) and the microbial degradation of oxidized compounds (carboxylic acids) enrich energy content in remaining SOM. This explains why SOM is not fully mineralized (thermodynamically unfavorable). Energy from litter activates decomposers to mine nutrients stored in SOM (the main function of priming effects) because the nutrient content in SOM is 2–5 times higher than that of litter. Thus, the energy captured by photosynthesis is the main reason why microorganisms utilize organic matter, whereby SOM is merely a residual by-product of nutrient storage and a mediator of energy fluxes. For the first time we assessed the NOSC of microbial biomass in soil (−0.52) and calculated the corresponding energy content of −510 kJ mol−1 C, whereas bacteria contain less energy per unit of C than fungi. We linked CUE and EUE considering the NOSC of microbial biomass and element compositions of substrates utilized by microorganisms. The microbial EUE is always lower than CUE. This is one of the reasons why microbial growth is more limited by energy than by C. Based on the comparison of processes of C and energy utilization for cell growth and maintenance, we concluded that the two main mechanisms behind lower EUE versus CUE are: (i) microbial recycling: C can be microbially recycled, whereas energy is always utilized only once, and (ii) chemical reduction of organic and inorganic compounds: Energy is used for reduction, which is ongoing without C utilization.

Gunina A, Kuzyakov Y 2022. From energy to (soil organic) matter. Global Change Biology 28 (7), 2169-2182
Wang C, Kuzyakov Y 2023. Energy use efficiency of soil microorganisms: Driven by carbon recycling and reduction. Global Change Biology 29, 6170-6187

How to cite: Kuzyakov, Y., Wang, C., and Gunina, A.: From energy to soil organic matter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11690, https://doi.org/10.5194/egusphere-egu24-11690, 2024.

EGU24-12150 | ECS | Posters on site | SSS4.1

Effect of passive warming (soil translocation) on 18O CUE and soil enzyme activity along a tropical forest elevational gradient 

Bin Song, Aiwei Huang, Kevin Z.Mganga, Juuso Tuure, Christopher Poeplau, Xuhui Luo, and Kristiina Karhu

The impact of global warming on soil processes is a critical area of concern. Limited studies have investigated soil organic carbon (SOC) dynamics' adaptation to warming. This poses a great challenge in assessing and understanding terrestrial C cycle response to climate change. Carbon Use Efficiency (CUE), indicating the proportion of metabolized organic C allocated to microbial biomass growth, is a pivotal regulator governing the fate of soil C. Moreover, our understanding of fundamental drivers of microbial CUE is largely elusive and inconclusive, especially in tropical ecosystems.

To address these knowledge gaps, we translocated top soil samples (10 cm deep soil cores) from two higher elevation sites (Vuria, 2000 m a.s.l, and Ngangao, 1800 m a.s.l) to a lower site (Macha, 1600 m a.s.l) along a moist montane rain forest gradient in Taita Hills, Kenya. Utilizing an 18O-water tracing approach, we examined the changes in microbial CUE in response to approximately three years of experimental warming. We also measured enzyme activities and conducted a 6-month laboratory incubation (15°C and 25°C) to study temperature sensitivity in native and translocated samples.

Our hypotheses were: (i) Both microbial CUE and C related enzyme activities would decrease, however, N- and P- cycle enzyme would increase along an altitudinal gradient toward the top of the Taita Hills, primarily governed by soil C and N availability; (ii) passive warming by soil translocation would result in higher CUE in translocated soils compared to native soils; (iii) At lower temperatures, soil microbial CUE is expected to decrease due to microbes allocating increased energy towards synthesis of enzymes involved in nutrient acquisition, while reducing C investment towards their growth.

Initial findings have revealed significant distinctions in enzyme activity profile due to elevation and temperature effects. Specifically, β-glucosidase and acid phosphatase activities increased and decreased along the elevation, respectively. Consistent with our hypothesis, enzyme activities and microbial CUE were higher in translocated soil than native soil. The six-month incubation had a similar effect on translocated soils and lower temperature increased the microbial CUE. In summary, our study indicates that passive warming alters microbial temperature adaption and underscores the influential role of soil enzyme activities in regulating microbial CUE. We suggest that soil microbiome at lower temperature indicates greater need for nutrients and energy. Our results highlight the need to investigate a wide variety of temperature influence on tropical soils in order to better understand and predict how the changing climate will affect C and nutrient cycling.

How to cite: Song, B., Huang, A., Z.Mganga, K., Tuure, J., Poeplau, C., Luo, X., and Karhu, K.: Effect of passive warming (soil translocation) on 18O CUE and soil enzyme activity along a tropical forest elevational gradient, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12150, https://doi.org/10.5194/egusphere-egu24-12150, 2024.

EGU24-13165 | ECS | Posters on site | SSS4.1

Both soil minerals and organic material contribute to the energy content of soil – Insights from an artificial soil experiment and calorimetric analyses 

Marcel Lorenz, Christian Fricke, Klaus Kaiser, Elvira Sieberger, Thomas Maskow, and Sören Thiele-Bruhn

The thermodynamic perspective on soil systems gets more and more in the research focus and has the potential to take us a substantial step toward a holistic understanding of soil organic matter (SOM) turnover and stabilization. An integral part of new bioenergetic concepts and models is the energy content of SOM, but its determination particularly in mineral soils is challenging. One of the most promising techniques in this respect is thermogravimetry combined with differential scanning calorimetry (TG-DSC), where the heat of combustion is related to the mass losses of soil material during a temperature ramp from 50 to 1000°C under an oxidative atmosphere. Heat and mass changes in the range from 180-600°C are usually interpreted as the result from the exothermic reaction of SOM and thus used to obtain the energy content (combustion enthalpy, ∆CH) of SOM. Overlapping exo- and endothermic reactions by other non-oxidizing processes (e.g. dehydroxylation/-carboxylation and desorption of soil minerals etc.) in that temperature range are often neglected because their distinction and quantification from the rather strong exothermic oxidation reactions from SOM is challenging.

To investigate this, we determined the ∆CH of an organic substrate (cellulose) and soil minerals (quartz sand, quartz silt, goethite, illite, montmorillonite) 1) individually, 2) intensively mixed in the dry state, and 3) intensively mixed after several wetting-drying cycles. Furthermore, the minerals were mixed to create a silt loam texture and combined with cellulose to mimic an artificial soil. Calorimetric analyses were conducted using a TG-DSC coupled with a mass spectrometer (MS) to analyze the evolved gases during combustion.

First results show that the ∆CH value obtained by TG-DSC is lower for the organic substrate compared to reference values obtained by combustion calorimetry as the standard method. Furthermore, ∆CHdiffers when mineral compounds are mixed with cellulose indicating that thermal reactions by mineral soil compounds affect the determination of the energy content by the TG-DSC standard procedure described above. This is supported by the analyses of the pure mineral compounds, which revealed that all investigated minerals show exothermic and/or endothermic side reactions in the range from 180-600°C affecting the TG-DSC signal. In dependence on the mineral composition of the soil, the energy content of SOM by the classical TG-DSC approach can be substantially over- or underestimated.

From this first data set, we identified options to improve both the measurement and the data evaluation procedures. Building on this, we aim to develop a procedure for the accurate measurement of the energy content of SOM in (mineral) soils by TG-DSC(-MS), taking into account the contribution of mineral oxidation and the effect of organo-mineral associations on the energetic signatures derived from the thermograms. This is crucial if energy flows and sinks in soil systems are to be quantified to better understand OM turnover and stabilization in soil.

How to cite: Lorenz, M., Fricke, C., Kaiser, K., Sieberger, E., Maskow, T., and Thiele-Bruhn, S.: Both soil minerals and organic material contribute to the energy content of soil – Insights from an artificial soil experiment and calorimetric analyses, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13165, https://doi.org/10.5194/egusphere-egu24-13165, 2024.

EGU24-14773 | ECS | Posters on site | SSS4.1

Investigation of thermal reactions and energy content of building blocks of soil organic matter using simultaneous thermal analyses 

Christian Fricke, Marcel Lorenz, Thomas Maskow, Sören Thiele-Bruhn, and Gabriele Schaumann

Soils are multi-component, open systems and play a decisive role in natural energy and matter fluxes, e.g. in the storage and bioenergetic control of carbon. A key component in this system is soil organic matter (SOM), as it determines the functionality of the soil. SOM is formed by building blocks from biomass, plant and animal detritus. Therefore, SOM itself is a complex, supramolecular mixture of different components. This property complicates the thermodynamic characterization of SOM and consequently the determination of the energy content. The latter is an important piece of the puzzle for a thermodynamic description of energy fluxes in soil systems, which is necessary for a holistic understanding of SOM turnover and stabilization.

In soil science, simultaneous thermal analysis (STA) is used to determine the energy content of SOM. The soil sample is heated in crucibles in a defined temperature program (e.g. 30-1000 °C, 10 °C/min) under an oxidative atmosphere. During heating, the mass loss (thermogravimetry, TG) and heat flux caused by SOM combustion (dynamic scanning calorimetry, DSC) are measured simultaneously. The STA data can be used to determine the energy content of the SOM during combustion and to identify SOM fractions of different thermal stability.

To develop a deeper understanding of the reactions taking place during STA of SOM, we investigated the combustion of building blocks of SOM and examined the influence of different crucible setups (Al2O3 with and without lid, Pt-Rh-Al2O3 with lid) on the measured energy content. The selection of building blocks included well-defined compounds like glucose, cellulose, chitin, etc. and complex compounds like maize straw, peptidoglycan, humic acid and lignin (organosolv). The STA was coupled with an evolved gas analyzer (mass spectrometer, MS) to draw also conclusions about the combustion reactions of the building blocks by monitoring H2O and CO2.

Our results show two main points: First, the crucible setup has a huge impact on the measured energy content. A better thermal conductivity (Pt-Rh > Al2O3) and the use of a lid lead to an increase in the measured energy content. Secondly, we observe two distinguishable thermal reactions for most of the building blocks, which were mainly revealed by the release of H2O and CO2. The first reaction is a decomposition at low temperatures (< 400 °C) with the formation of char, which was then further oxidized at higher temperatures (> 400 °C). The change in the ratio between the H2O- and CO2-MS signal allows a clear allocation of different thermal reactions.

In summary, the investigation of building blocks of SOM by STA coupled with MS provides a better understanding of the combustion of SOM in soil samples and thus allows a more reliable interpretation of the measured energy contents. Further STA studies should focus on the interaction between SOM building blocks and soil minerals to identify other possible thermal reactions that could affect the measured energy content.

How to cite: Fricke, C., Lorenz, M., Maskow, T., Thiele-Bruhn, S., and Schaumann, G.: Investigation of thermal reactions and energy content of building blocks of soil organic matter using simultaneous thermal analyses, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14773, https://doi.org/10.5194/egusphere-egu24-14773, 2024.

EGU24-15343 | ECS | Orals | SSS4.1

Labile substrate availability affects interactions and function in degrader communities: Insights from a combined experimental and modelling approach 

Moritz Mohrlok, Ksenia Guseva, Lauren Alteio, Julia Berger, Lilian Kaufmann, Julia Mor Galvez, Dave Sirbu, and Christina Kaiser

Bacterial communities that degrade chitin in soils often exhibit “social” behavior, where different strains fulfill different functional roles. “Degraders” produce extracellular enzymes that attack and cleave the complex biopolymer, releasing the monomer N-acetylglucosamine (NAG) as a public good. This compound can be readily taken up by both degraders and “exploiters”. The latter do not contribute directly to the degradation process but might in turn produce different substances that can be utilized by other members. “Scavengers” do not utilize NAG themselves but live mostly off metabolites secreted by the other strains. Our work aimed to investigate what effect the addition of a readily available C compound, like NAG, has on these interactions in such a system. Based on the results of a wet-lab experiment using a model bacterial consortium, we hypothesized that adding labile C leads to domination of the exploiter-strain though competitive exclusion. This in turn results in the breakdown of positive interactions, and a loss of diversity and functionality of the community. To further investigate this, we designed an ordinary differential equation (ODE) consumer-resource model, consisting of different linked pools representing the experiment. By parametrizing this model based on our respiration measurements and simulating the system over time, we were able to reproduce most of the observed experimental patterns in silico. When there was no NAG added to the system, the model matched the measured respiration when we included several positive interactions (such as crossfeeding or division of labor). This resulted in a more diverse community that degraded chitin more efficiently than the degrader-strain in monoculture. When NAG was added, the exploiter-strain outcompeted the other strains quickly, resulting in a loss of their potential function for the community. Through this combined experimental and modelling approach, our work shows that the addition of excess labile C to degrader communities in soil can alter interactions between bacteria, possibly leading to a loss of biodiversity and function.

How to cite: Mohrlok, M., Guseva, K., Alteio, L., Berger, J., Kaufmann, L., Mor Galvez, J., Sirbu, D., and Kaiser, C.: Labile substrate availability affects interactions and function in degrader communities: Insights from a combined experimental and modelling approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15343, https://doi.org/10.5194/egusphere-egu24-15343, 2024.

EGU24-15875 | ECS | Orals | SSS4.1

Changes in the microbial control of C and N cycling in future subarctic tundra soils 

Agnieszka Rzepczynska, Johannes Rousk, and Lettice Hicks

Arctic climate warming will affect microbially-controlled nutrient cycling through elevated nutrient availability and changes in vegetation productivity and composition. Plant-derived C inputs will serve as a microbial energy and C source, while the inorganic N released from soil organic matter (SOM) could . Albeit controlled by different mechanisms, increased C and N availability may each stimulate microbes to degrade more SOM, creating positive climate change feedbacks. Simultaneously, microbes provide the main pathway to sequester and stabilize C and N in SOM through growth and subsequent necromass formation, termed the “microbial pump”, generating a negative climate change feedback. Combining estimates of microbial growth, biomass, and biogeochemical rates allows for the calculation of Carbon Use Efficiency (CUE) and Nitrogen Use Efficiency (NUE). Analyzing NUE relative to CUE may elucidate microbial resource limitation. Resultantly, NUE exceeding CUE indicates microbial N-limitation, and suggests that microbes sequester N in SOM. Conversely, CUE exceeding NUE suggests microbial C-limitation and points towards microbial C sequestration in SOM. In addition, the strength of the microbial C and N pumps can be estimated by assessing microbial growth along with microbial C and N retention times, providing insights into how long resources will be retained in the microbial biomass. These tools contribute to a comprehensive understanding of whether resources will be liberated through decomposition or sequestered via the microbial pump.

Here, we investigated microbial responses to changes in resource availability associated with future climate change in a subarctic tundra heath. We used additions of mineral N and litter in the field to mimic the effects of elevated nutrient availability and shrubification on microbial growth rates (radio-isotope tracing), C and gross N mineralisation rates (gas chromatography and 15N pool dilution methods, respectively), and microbial community size was estimated with phospholipid fatty acids.

We found that field N-fertilization generally decreased microbial NUE, and that the resulting NUE/CUE ratio was close to 1, thereby pointing towards alleviated microbial N-limitation. Field N-fertilization also accelerated N-cycling but had no significant effects on C retention times. Conversely, litter addition in the field led to NUE exceeding CUE, implying the induction of microbial N-limitation, and it slowed C turnover times, but had no significant effect on N turnover times. When N and litter were applied together, similar CUE and NUE values, but accelerated C and N turnover times were observed. Overall, fungal contribution to resource cycling diminished across all field treatments, evident from a reduced fungal-to-bacterial growth ratio compared to the control treatment.

These findings highlight that changes in nutrient availability impact microbial C and N cycling independently and emphasize that the microbial resource limitation may be altered by the substrate stoichiometry. Additionally, our results suggest that while microbial N cycling is likely to accelerate, thus weakening the microbial N pump, microbial C cycling may be impeded and microbial C pump strengthened. Overall, these observations align with projections of more fertile and productive subarctic ecosystems in the future, and underscore the potential for microbial C sequestration even under altered resource availability. 

How to cite: Rzepczynska, A., Rousk, J., and Hicks, L.: Changes in the microbial control of C and N cycling in future subarctic tundra soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15875, https://doi.org/10.5194/egusphere-egu24-15875, 2024.

Microbial communities in soil play a pivotal role in nutrient cycling and organic matter decomposition, relying on carbon (C) and energy sources for growth. The allocation of these substrates, crucial for their metabolic activities, is influenced by environmental conditions. We hypothesize a close linkage between carbon and energy fluxes in soil, with environmental conditions shaping substrate requirements and activities, thereby influencing Carbon Use Efficiency (CUE) and Energy Use Efficiency (EUE).

To establish the link between matter and energy fluxes, we employed artificial soil consisting of a sand, clay, and silt mixture as a simplified system, with cellulose as the only added substrate. This model system allowed us to investigate the relationship between C and energy fluxes without a large background of soil organic matter background (SOM). Experimental conditions included three different water contents (10%, 14.4% and 19%), two ratios of added carbon (C) to nitrogen (N) (C/N = 18 and C/N = 9), and two temperature regimes (7  and 20 ). Mineralization (measured by GC-TCD) and residual cellulose (measured by phenol sulphuric acid assay) were quantified on sampling days, while continuous monitoring of heat production rate (P) was monitored using isothermal microcalorimeter (i.e. TAM Air).

Results revealed a clear correlation between environmental conditions and microbial activities. Higher moisture levels led to increased CO2 production, heat generation, and cellulose degradation. Similarly, lower N supply (higher C/N ratio) exhibited the same trend. Decreased temperatures resulted in minimal CO2 evolution and heat production rates and diminished cellulose degradation.

Analysis of CUE over time indicated a decline, possibly due to biomass recycling and additional respiration. Surprisingly, little apparent effect of water content or N supply on CUE was observed. CUE in the two temperature treatments show similar decreasing trends, but CUE is at an overall higher level at 7°C. EUE remained relatively stable over time but tended to decrease under conditions of environmental stress, such as extreme water content or N limitation. However, high variability is observed, and no statistical significance can be found.

An energy balance framework is being developed and will be used to calculate CUE from a theoretical perspective. Comparisons between experimentally derived CUE and theoretically calculated values will prompt a re-evaluation of the underlying assumptions and a call for refined theoretical protocols. In summary, our findings suggest that environmental conditions significantly influence cellulose degradation. However, a clear correlation between CUE and EUE requires further analyses and experimental improvements. This study contributes to our understanding of the intricate relationships between carbon and energy fluxes in soil microbial systems and emphasizes the need for nuanced analyses in future research.

How to cite: Yang, S., Rupp, A., Miltner, A., Maskow, T., and Kästner, M.: Linking mass balances and thermodynamic energy balances at different water contents, temperature and nutrient supply in simplified model systems with artificial soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16129, https://doi.org/10.5194/egusphere-egu24-16129, 2024.

EGU24-16811 | Orals | SSS4.1

Prospects and challenges of simulating organic matter turnover and stabilization in soil systems 

Holger Pagel, Thilo Streck, Ahmet Sircan, and Stefano Manzoni

Understanding the turnover and stabilization of soil organic matter (SOM) is the key to highly productive agriculture and to climate change mitigation. Understanding and predicting biogeochemical matter and energy flows in soil systems is challenging due to persisting knowledge gaps regarding biological and energetic controls of SOM turnover and limited knowledge integration of informative data with process-based models. We present modeling concepts of microbially explicit soil organic matter models and shed light on integrating trait-based ecological frameworks in process-based models and the use of advanced data-model fusion approaches. We highlight some insights from applying process-based models and challenges we need to address to acquire robust predictions.

How to cite: Pagel, H., Streck, T., Sircan, A., and Manzoni, S.: Prospects and challenges of simulating organic matter turnover and stabilization in soil systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16811, https://doi.org/10.5194/egusphere-egu24-16811, 2024.

EGU24-17226 | ECS | Orals | SSS4.1

Dynamics of soil microbial carbon storage compounds in low fertility landscapes 

Orpheus Butler, Stefano Manzoni, and Charles Warren

Intracellular storage of carbon (C) by soil micro-organisms is emerging as a key process that influences soil biogeochemical cycling and the broader function of terrestrial ecosystems. One likely role of intracellular C storage is to serve as a stoichiometric buffer against nutritional imbalances in the microbial substrate. Such a function would make storage compounds vital to the long-term function of ecosystems associated with strongly weathered, low fertility soils, yet there have been few studies of intracellular carbon storage in such ecosystems. We examined the dynamics of two putative storage compounds (triacylglycerol [TAG] and polyhydroxybutyrate [PHB]) across two natural soil fertility gradients in eastern Australia. Across all sites and samples, absolute quantities of storage compounds ranged from 0 to 173 µg C g soil-1 in the case of TAG and 0 to 56 µg C g soil-1 for PHB. When standardized to total soil organic C, quantities of storage compounds tended to be markedly higher than those observed in prior studies of temperate and/or agricultural soils. Allocation to storage compounds followed strong trends across natural gradients of soil fertility and tended to peak in phosphorus-deficient and/or retrogressive ecosystems. Across soils of differing parent material, allocation to C storage was highest in infertile soils derived from phosphorus-depleted sandstone and ironstone compared to soils derived from shale and basalt. Likewise, allocation to C storage increased throughout ~700k years of soil development across a strongly weathered podzolic dune chronosequence. Dynamics of community-level C storage allocation were evidently underpinned by a combination of assemblage-level processes, most notably changes in the relative abundance of TAG-rich, C-limited fungal taxa, and physiological plasticity on the level of individual P-limited bacterial cells. Our findings are largely consistent with the surplus/reserve storage framework and highlight the importance of storage compounds for the function of oligotrophic ecosystems and as a major pool of C in soil.

How to cite: Butler, O., Manzoni, S., and Warren, C.: Dynamics of soil microbial carbon storage compounds in low fertility landscapes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17226, https://doi.org/10.5194/egusphere-egu24-17226, 2024.

EGU24-18651 | Orals | SSS4.1

Using metabolic flux modeling to disentangle anabolic and catabolic contributions to soil heat dissipation 

Guodong Shao, Xin Xu, Callum C. Banfield, Lingling Shi, Kyle Mason-Jones, Weichao Wu, and Michaela A. Dippold

Metabolic flux analysis is an integrated experimental and computational approach for quantitative understanding of biochemical reaction networks with particular relevance in systems biology. Mass and energy flows through soil microbial metabolism are subject to the laws of thermodynamics. Carbon (C) allocation through central metabolic pathways (e.g. glycolysis, pentose phosphate, and Entner-Doudoroff) can be reconstructed by 13C-labelling coupled to metabolic flux analysis (13C-MFA) by tracing specific C atoms from within substrate molecules into metabolic products such as carbon dioxide (CO2) or fatty acids. However, mass flow calculated via 13C-MFA alone cannot fully characterise microbial carbon use. Here, we took the novel approach of coupling MFA with microcalorimetry, to also take bioenergetic constraints into account. We coupled energetics and mass flow on a metabolic level by selecting optimal sets of isotopomer tracers. Fifteen position-specific or uniformly 13C-labelled isotopomers - four alanine, seven glucose, and four glutamic acid ones – were added to a Luvisol (in total 4 folds of the microbial biomass C), and we analyzed substrate-derived 13CO2 fluxes as well as heat dissipation via isothermal microcalorimetry.

Our results demonstrate that the temporal dynamics of catabolic CO2 release resembles that of the heat dissipation, i.e. peak respiration and peak heat dissipation were reached approximately 18 h after substrate addition, irrespective of whether the substance entered the central metabolic pathway at the monosaccharide level (glucose), at the pyruvate level (alanine) or in the citric acid cycle (glutamic acid). This indicates that heat dissipation in the initial growth period was strongly dominated by catabolic processes. However, whereas 13CO2 release leveled off during the 36 hours of incubation, the heat dissipation remained above its original level, suggesting that anabolic processes increasingly contribute to the heat dissipation in the later phases of incubation. Glucose isotopomer utilization indicated dominance of the pentose phosphate and Entner Douderoff pathways over glycolysis, suggesting a high activity of fast-growing organisms with considerable C allocation to anabolism. The dominance of this anabolic C use in the later stage of the incubation was confirmed by the isotopomer utilization of alanine and glutamic acid. This study shows that the heat dissipation of growing microbial communities under high C supply is closely linked to their catabolic CO2 release, whereas slow, potentially recycling-based growth after resource depletion releases energy more via anabolic reactions. We furthermore demonstrated that coupled MFA and calorespirometry provides a powerful tool to differentiate among metabolic contributions to the energy use of soil microbial communities in different growth phases.

How to cite: Shao, G., Xu, X., Banfield, C. C., Shi, L., Mason-Jones, K., Wu, W., and Dippold, M. A.: Using metabolic flux modeling to disentangle anabolic and catabolic contributions to soil heat dissipation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18651, https://doi.org/10.5194/egusphere-egu24-18651, 2024.

EGU24-19075 | ECS | Orals | SSS4.1

Global distribution and drivers of microbial carbon use efficiency for projecting soil organic carbon fates under a changing climate: A meta-analysis 

Qing-Fang Bi, Bernhard Ahrens, Thomas Wutzler, Markus Reichstein, and Marion Schrumpf

Comprehending the factors influencing microbial carbon use efficiency (CUE), and where CUE is most optimal to soil organic carbon (SOC) storage, are crucial for managing microbial roles in SOC sequestration and model prediction. Yet, establishing a direct mathematical relationship between CUE and SOC might be challenging, with global distributions and controls remaining unresolved, particularly in response to various global changes. Here, we leverage a global synthesis of CUE measurements by 18O-microbial DNA growth, and observed an average CUE across all biomes at 0.3, with the highest in temperate grasslands and deeper soils, and the lowest in tropical forests. Random forest analysis identified climates (aridity index and mean annual temperature: MAT) and soil properties (pH, bulk density and soil C:N ratio) as primary drivers influencing CUE. However, microbial biomass size overall exhibited a smaller effects on CUE, despite its substantial impact in each land use type. We then review how these drivers affecting CUE values may be altered by warming, soil fertilization, altered precipitation and elevated carbon dioxide. Notably, nitrogen additions plays a big role in increasing CUE and promoting SOC contents, while warming effects depend on time-scale, with long-term warming potentially leading to SOC losses with a lower CUE and growth. Moreover, we found that the CUE–SOC relationship varies across different climates, greatly driven by MAT and soil properties. Higher CUE promots SOC per fine fraction (clay+silt) across the major data points, contrasting with a negative relationship in a subarctic study, where pH is the primary determinate. Consequently, there might be no simple linear relationship between CUE and C in microbial biomass and soil. We conclude by discussing the integration of CUE into SOC models and the necessity of incorporating interactions between CUE and individual drivers for predicting soil carbon-climate change scenarios. Our study underscores the importance of considering microbial CUE and other microbial processes for improving projections of SOC dynamics.

How to cite: Bi, Q.-F., Ahrens, B., Wutzler, T., Reichstein, M., and Schrumpf, M.: Global distribution and drivers of microbial carbon use efficiency for projecting soil organic carbon fates under a changing climate: A meta-analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19075, https://doi.org/10.5194/egusphere-egu24-19075, 2024.

EGU24-19954 | ECS | Orals | SSS4.1

Microbial phenology in high-alpine environments: the influence of plant dynamics and physiological stress in a changing climate.  

Adam T. Ruka, Johannes Schweichhart, Jiří Doležal, Kateřina Čapková, Travis B Meador, Roey Angel, Rosa Paulina Calvillo Medina, Zuzana Chlumská, Vojtěch Lanta, Nadine Praeg, Paul Illmer, and Klára Řeháková

Alpine biomes experience harsh environmental conditions and short growing seasons, which necessitate interspecific and intraspecific interactions among plants and soil microbes to ensure the stability of diversity and ecosystem multifunctionality. With strong seasonal dynamics in alpine regions, including snow cover, snowmelt, and drought, “hot moments” of biogeochemical activity occur when pulses of nutrients dictate microbial processes across the biome. However, within the rhizosphere, microbial processes are promoted or deterred during phases of plant growth, senescence, and nutrient allocation, leading to a more nuanced seasonal pattern of soil microbes. Indeed, these factors lead to a general microbial phenology of soil processes and community composition. Yet, shifted climatic regimes due to warming likely cause these relationships to be strained, potentially resulting in physiological stress among plants and microbes. Therefore, our research focuses on the coupling or decoupling of plant and microbial parameters across seasonal changes in the Austrian Alps by assessing stoichiometric ratios of shared nutrients such as carbon (C), nitrogen (N) and phosphorus (P), along with microbial diversity. 

Using elevation gradients, the corresponding influence of plants, soil chemistry, and environmental conditions upon microbial phenology can be assessed in two different biomes: undeveloped subnival zones and nutrient-rich alpine meadows.  Furthermore, by combining methods for assessing biological soil parameters, such as chloroform fumigation extraction, enzymatic assays, and respiration measurements, with amplicon DNA sequencing, we can observe broad microbial community responses such as increased biomass (Cmic) in different seasons related to plant-specific interactions while identifying microbial taxa (fungal and bacterial) that indicate nutrient limitations in conjunction with ratios of enzymatic activity. Additionally, by measuring plant nutrient concentrations in distinct plant organs, we can infer which physiological processes among plant species most closely correspond with changes in broad microbial parameters and rhizosphere diversity.

Therefore, we propose that certain aspects of microbial phenology are generalizable, such as increased N cycling during winter and spring months, while the temporal optima for C cycling is more plant-specific. Furthermore, we present results from the rarely studied snow-covered winter months, in which the mineralization of C, P, and chitin degradation are highest. In total, these studies demonstrate a thorough analysis of plant-microbial interactions in alpine ecosystems which are subject to significant change within the coming decades.

How to cite: Ruka, A. T., Schweichhart, J., Doležal, J., Čapková, K., Meador, T. B., Angel, R., Calvillo Medina, R. P., Chlumská, Z., Lanta, V., Praeg, N., Illmer, P., and Řeháková, K.: Microbial phenology in high-alpine environments: the influence of plant dynamics and physiological stress in a changing climate. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19954, https://doi.org/10.5194/egusphere-egu24-19954, 2024.

EGU24-21168 | Orals | SSS4.1

What taxon-specific growth measurements reveal about microbial growth strategies in natural soil communities 

Andreas Richter, Dennis Metze, Alberto Canarini, Lucia Fuchslueger, Hannes Schmidt, and Christina Kaiser

Heterotrophic microorganisms decompose soil organic matter to assimilate organic compounds that provide energy and carbon for growth and maintenance. The growth of microbial communities is thus at the heart of the carbon cycle, and understanding how microbial growth is controlled is arguably of paramount importance for understanding global carbon cycling in the present and future climate. 

Most information on microbial growth comes from work with pure cultures (population level) or from studies of microbial community growth, while understanding the growth of individual microbial taxa in natural communities is poorly studied and understood. However, with the advent of new stable isotope probing techniques based on 18O from labelled water, it is now possible to look beyond the community level to the growth of individual populations of microorganisms in complex soil communities. In addition, recent advances in labelling growing microbial taxa without the addition of liquid water, the so-called ‘vapor qSIP', allow us to analyze microbial growth in complex communities without changing environmental conditions, a prerequisite for studying the behavior of microbial communities in climate change experiments.

We report here on two climate change experiments in which we performed taxon-resolved growth measurements under different environmental conditions. Our results show the following:

(1) Contrary to our expectations, changing environmental conditions (e.g., soil warming and drought) led to a change in the number of actively growing bacterial taxa, but not in their growth rates. Among other things, this challenges the paradigm developed from a plethora of measurements of microbial community growth that microbial physiology is accelerated by higher temperatures.

(2) Many microbial taxa were only actively dividing in specific climate change treatments, i.e., under specific environmental conditions. We conclude that the realized ecological niche of bacteria appears to be much smaller than community growth measurements suggest. Testing, for example, the temperature niche of individual populations (with presumably different functional traits) may therefore lead to very different predictions of soil functions in a future climate.

(3) Compared to estimates of total soil microbial community composition (e.g., amplicon sequencing of the 16S rRNA gene), the actively growing community is more sensitive to changes in environmental conditions, allowing a more accurate prediction of community structure in a future climate and its functional roles in biogeochemistry.

Overall, measuring taxon-resolved population growth rates of complex communities provides a novel, more nuanced and sophisticated picture of soil ecosystems, which may help to develop better predictions of structural and functional changes in microbial ecosystems in a future climate.

How to cite: Richter, A., Metze, D., Canarini, A., Fuchslueger, L., Schmidt, H., and Kaiser, C.: What taxon-specific growth measurements reveal about microbial growth strategies in natural soil communities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21168, https://doi.org/10.5194/egusphere-egu24-21168, 2024.

EGU24-21170 | ECS | Posters on site | SSS4.1

Tracking 13C into soil organic matter through the mycorrhizal fungal pathway under nutrient addition 

Kaydee S. Barker, Matthew L. Meehan, David Johnson, Richard D. Bardgett, and Clare H. Robinson

Arbuscular mycorrhizal (AM) fungi are ubiquitous plant symbionts that mediate soil organic matter (SOM) formation through nutrient exchange and the accumulation of their own biomass and necromass. Recent studies suggest that microbial necromass, including fungal necromass, may account for upwards of half of SOM carbon, but the specific contribution of AM necromass remains unknown. Additionally, how land management impacts AM-mediated SOM is not well understood, especially in grasslands where AM fungi are prevalent and play a key role in regulating plant diversity and ecosystem function. We grew Lolium perenne with four treatments: (1) an inoculation of AM spore-rich sandy soil, (2) an application of nitrogen-phosphorus-potassium (NPK) fertilizer, (3) a combination of spore-rich soil and NPK, and (4) a control. We isotopically labelled plants with 13C-CO2 before incubating the roots and AM hyphae in place, and are measuring 13C in SOM, plant and microbial pools, and released CO2 at multiple timepoints over 6 months to track C through decomposition. Our preliminary results show that both 13C and 13C-CO2 respiration were lower for fertilizer treatments compared to control and inoculation-only treatments during the first month of incubation. This demonstrates that even a small one-time NPK application may influence subsequent decomposition of root and AM tissues at the end of the growing season. The lower amounts of 13C respiration may be due to differences in plant carbon to nitrogen ratios, leading to higher microbial carbon use efficiency, or NPK addition may have inhibited the growth of AM hyphae, leading to decreased available 13C in the soil. These hypotheses will be investigated further with additional measurements as outlined above. By using stable isotope tracing into biomarkers, SOM pools, and soil respiration, our study will shed light on the contribution of AM and associated root necromass to SOM carbon and provide needed insight for conscious grassland management.

How to cite: Barker, K. S., Meehan, M. L., Johnson, D., Bardgett, R. D., and Robinson, C. H.: Tracking 13C into soil organic matter through the mycorrhizal fungal pathway under nutrient addition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21170, https://doi.org/10.5194/egusphere-egu24-21170, 2024.

EGU24-588 | ECS | Orals | SSS4.2

Relating bush encroachment density of savanna soils in the Kalahari district in Botswana to soil organic matter stocks and quality. 

José María García de Castro Barragán, Nnyaladzi Batisani, Flora Pule-Meulenberg, Lawrence Akanyang, José María de la Rosa Arranz, M. Rocio Reinoso Limones, and Heike Knicker

Bush encroachment is a form of rangeland degradation. It is characterized by a shift from herbaceous to woody plant dominance, which has reduced indigenous plant and animal biodiversity and it’s a significant problem in southern African savannas, particularly in Botswana, Namibia and South Africa. Overgrazing by cattle on the one hand and the loss of a large part of large herbivores on the other hand, have been identified as main contributor to imbalance of this delicate ecosystem. The present study aimed to investigate bush encroachment effects on soil organic matter (SOM) in areas of low, medium, and high bush density in a farmed area of the Botswana’s savanna. Bush encroachment is expected to have significant effects on soil properties. It is assumed to decrease soil organic C concentration as well as contents of macro and micro nutrients. To investigate such possible impacts, a sampling was realized during the dry season in various plots with varying encroachment densities (Senegalia mellifera). The analysis included standard soil parameters, (pH, electrical conductivity, cation exchange capacity; elemental composition, and bulk density) the composition of the SOM was characterized by solid-state nuclear magnetic resonance spectroscopy. The preliminary results of these analysis revealed only small differences between sites with low, medium, and high levels of bush encroachment. This suggests that the impact of bush encroachment on savannah’s SOM is lower than expected and may not be directly related to bush density. Further research will compare the obtained data with data obtained during the wet season to obtain a better understanding of the SOM dynamics and the impact of encroachment on soil degradation.

Acknowledgement: The authors would like to express their gratitude to the European Commission for the financial support of this research within the European Framework Program for Research and Innovation Horizon 2020 (Grant No. 101036401).

How to cite: García de Castro Barragán, J. M., Batisani, N., Pule-Meulenberg, F., Akanyang, L., de la Rosa Arranz, J. M., Reinoso Limones, M. R., and Knicker, H.: Relating bush encroachment density of savanna soils in the Kalahari district in Botswana to soil organic matter stocks and quality., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-588, https://doi.org/10.5194/egusphere-egu24-588, 2024.

EGU24-1115 | Posters on site | SSS4.2

The impact of the Russian-Ukrainian war on the soil-surface water interactions 

Vita Strokal, Yevhenii Berezhniak, Olena Naumovska, and Svitlana Palamarchuk

This research aims to discuss and reflect on the main consequences of the Russian-Ukrainian war on the soil, and water resources of Ukraine. For the soil resources, the main outcomes are as follows: 1) approximately 35% of the Ukrainian territories have been experiencing soil destruction processes due to the war implications – 130 thousand km2 of the land is mined or damaged; part of the agricultural land for growing crops is not suitable, especially in regions (oblasts) such as Kharkiv, Mykolaiv, Kherson, Zaporizhzhia, Kyiv, and Chernihiv (according to the state report on May 2023); 2) as a result of the damaged Kakhovka Hydropower Dam, losses of crop yields on the part of the Kherson region consist of 100 thousand tons, 31 irrigation systems are left without access to water supply in the southern part of Ukraine. Degradation of soil has impacts on water pollution via polluted runoff and erosion.

For the water resources, the main outcomes are as follows: 1) 724 hydrotechnical systems (hydraulic structures), 160 of treatment and sewage systems (water treatment and sewage facilities), and 22 dams are destroyed leading to water pollution; 2) up to 90% of the irrigation system in the south of Ukraine is lost, and 67% less fishing due to damaged or destroyed hydraulic systems; 3) the disruption of the Kakhovka Hydropower Dam has resulted in the flooded areas: water from the dammed reservoir was flushed and flooded the surrounded areas with polluted soils and households, a lot of pollutants was released into the water from untreated human waste, products of animals, around 31 water supply and drainage facilities were affected, 13 villages left without centralized water supply, and 4 landfills of solid household waste became flooded.

In our research, we analyzed the implications of the Russian-Ukrainian war on the state of soil and water resources and explored their interactions. We identified the main consequences of the Russian aggression such as the loss of soil productivity, the reduction of food production potentials, and the reduction of water safety and availability. The cause-and-effect relationships of risks are discussed. These relationships can become a threat and lead to the deterioration of the population's supply of food and safe water, and the spread of infectious diseases.

Keywords: soil resources; water resources; the Russian-Ukrainian war; soil destruction, the deterioration of food and safe water.

 

How to cite: Strokal, V., Berezhniak, Y., Naumovska, O., and Palamarchuk, S.: The impact of the Russian-Ukrainian war on the soil-surface water interactions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1115, https://doi.org/10.5194/egusphere-egu24-1115, 2024.

EGU24-3156 | ECS | Orals | SSS4.2

Elucidation of the interplay between roots and microorganisms in the organic N transformation in the rhizosphere of maize 

Guoting Shen, Andrey Guber, Alexandra Kravchenko, and Evgenia Blagodatskaya

Mechanisms of nitrogen (N) acquisition in the rhizosphere often include microbial immobilization of mineral N and its further transformation into organic compounds. Therefore, visualization and quantification of organic N distribution and their correlation with N-related enzymatic hotspots helps to reveal the role of roots in plant-microbial interplay related to N cycling. In this study, time-lapse leucine aminopeptidase (LAP) zymography and amino-mapping were coupled to reveal amino-N distribution both in the soil and distinct root segments of Zea mays L. A strong overlap between amino-N content and LAP activity in seminal and lateral root tips, as well as seminal roots, highlighted the intricate interplay between plants and microorganisms in N acquisition. Remarkably, we also uncovered a significant decoupling of LAP activity from amino-N in lateral roots and bulk soil. The distinct patterns in different root parts provided a perspective on the major origins of enzyme production in the rhizosphere. Endogenous LAP production by roots and root-associated microbes in seminal roots and root tips contrasted with the reliance on exogenous rhizosphere microorganisms for enzyme activity in lateral roots. This finding not only advances our understanding of N acquisition but also opens up the new avenues for discussion on the ecological roles of different root segments in shaping the rhizosphere environment.

How to cite: Shen, G., Guber, A., Kravchenko, A., and Blagodatskaya, E.: Elucidation of the interplay between roots and microorganisms in the organic N transformation in the rhizosphere of maize, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3156, https://doi.org/10.5194/egusphere-egu24-3156, 2024.

Substantial progress has been made in estimating and mapping soil organic carbon stocks, but the quantification of carbon stock change rates still needs exploration in numerous soil and management combinations. In this research, the soil organic carbon (SOC) changes and soil organic matter (SOM) composition in the long-term experiment (established in 1989, Tartu, Estonia) with sandy loam soil were studied. The experiment involves three-field crop rotation (potato-spring wheat-spring barley) with two fertilization regimes: (1) mineral fertilisation (N rates 0, 40, 80, 120 and 160 kg ha-1) and (2) same mineral fertilisation treatments with farmyard manure amendment. During 1989–2017, every spring the soil samples were taken from the 0-20 cm soil layer, and SOC concentration was measured by dry combustion. In 2017, the size fractionation of soil samples was also performed. In 2022, the soil samples were also taken from the area surrounding the experimental site, which has not been cultivated since the experiment was established and has been as permanent grassland (GR). Soil mineral-associated organic matter (MAOM fraction;<63 µm) of permanent grasslands is considered to be saturated with C thus the GR was used to estimate the MAOM-C saturation potential in treatments.

The SOC stock increased (0.08–0.18 Mg ha-1 y-1 depending on N fertiliser rate) only in manure treatments. In GR treatment the SOC stock remained unchanged. Without manure, the SOC stock decreased in range from -0.15 to -0.26 Mg ha-1 y-1. N fertilization had a positive effect on SOC stock. Initially, 27% of total SOC stock is related to particulate organic matter (POM fraction, 63-2000 µm) and 73% to MAOM fraction. Without manure, the proportion of C related to POM fraction decreased during 28 years to 21%, while in treatments with manure, it remained stable (28%). POM fraction plays an important role in plant nutrient supply, thus a higher proportion of C related to POM fraction in treatments with manure indicates sustainable nutrition conditions for plants and all soil biota. The MAOM-C concentrations in treatments without manure varied from 17.8 to 19.4 mg g-1 and were lower compared to treatments with manure (21.0–21.8 mg g-1). The MAOM-C of GR was 20.7 mg g-1 indicating that the soil is nearly saturated in manure treatments.  However, treatments without manure are far from saturation and have considerable potential for additional MAOM-C sequestration, varying between 3.0-6.8 Mg ha-1 depending on N fertilization. Soil organic matter fractionation into POM and MAOM fractions allows us to assess the soil's properties for sustainable plant production, and actual C sequestration capabilities, and provide crucial recommendations for effective management strategies.

How to cite: Kauer, K. and Astover, A.: Soil organic carbon change after 28 years of fertilisation in temperate conditions of Estonia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3449, https://doi.org/10.5194/egusphere-egu24-3449, 2024.

EGU24-3910 | ECS | Posters on site | SSS4.2

Microrespiration: A field method for measuring microbial activity in arable soils 

Franziska Weinrich

Microrespiration: A field method for measuring microbial activity in arable soils

Franziska Weinrich1, Katharina Keiblinger1, Christoph Rosinger1,2 Gernot Bodner2

1Institute of Soil Research, Department of Forest- and Soil Sciences, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria (franziska.weinrich@students.boku.ac.at)

2Institute of Agronomy, Department of Crop Sciences, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria

The debate on soil health is more topical than ever. Large-scale soil monitoring is therefore an important tool for assessing the state of soil health. In this context, relatively simple yet reliable methods are needed to accompany lab-based analytics of different soil health indicators, such as microbial activity. Microbial activity is a useful parameter because most soil processes are mediated by soil microorganisms. The aim of this study is to develop a simple and affordable field test for broad applicability of measuring microbial activity in arable soils. The method was tested for sensitivity to different arable management systems and effects of land use as well as the influence of soil texture.

The principle of the field method is based on the colour change of a pH-indicator due to the acidic reaction with CO2 that is released during soil respiration. For this purpose, 13 agricultural sites with varying soil texture, three management systems as well as two types of land use (arable and natural vegetation) were examined. Pioneer management is characterized by management aiming for an increase of soil health by applying conservational or regenerative practices, Standard management involves state of common knowledge practices and the Reference, representing a different land use, is provided by a semi-natural vegetation strip.

The method was developed for different amounts of soil, moisture conditions, incubation periods and substrates (glucose powder, milled straw, milled alfalfa). For the validation of the field method, the colour change of the indicator (evaluated by means of RGB data) is compared to respiration measurements with gas chromatography in the laboratory. Additionally, microbial biomass carbon and ergosterol concentrations as well as their ratio were determined to evaluate changes in the abundance of the microbial community and bacteria vs. fungi composition.

The results show that the continuous colour change of the indicator is highly correlated with the CO2 concentrations measured in the laboratory (r2 = 0.62; p < 0.001). Furthermore, the metabolic quotient and the colour change correlate well with each other (r2 = 0.72; p < 0.001). The differentiation between agricultural management systems (Pioneer vs. Standard) is not so clear, land use however can clearly be distinguished with this method.  The influence of soil texture on the results of the field test is clearly visible. However, it is not possible to derive an indication on the microbial community composition with this method.

The performance of the field method leads to reasonable results and proves to be suitable for the simple determination of microbial activity in arable soils. After further improvement, this method provides a rather simple and affordable tool for soil health monitoring of arable soils.

How to cite: Weinrich, F.: Microrespiration: A field method for measuring microbial activity in arable soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3910, https://doi.org/10.5194/egusphere-egu24-3910, 2024.

The land use changes and environmental pollution brought by urbanization are important aspects of global change. Cities provide a unique "natural laboratory" for people to understand the impact of human-nature composite ecosystems on global change and their response processes. Unlike natural soils, human activities during urbanization directly or indirectly affect the formation and development of soils. Generally, urban soils have a higher organic carbon content compared to agricultural soils and some natural soils, making them an important carbon reservoir in urban ecosystem carbon cycles. The urban-rural gradient method based on urbanization intensity provides a possibility for studying the response of Soil Organic Carbon (SOC) storage to urbanization on a global scale. Here, we define Urban Intensity (UI) as the proportion of impervious surface area within each 1x1 square kilometer (ranging from 0 to 100%). We first analyzed the trends of SOC storage along the UI gradient globally and in different climate zones, distinguishing the contributions of natural and socio-economic factors through multiple linear regression and residual quantification. The study found that as UI increases, SOC storage undergoes phased changes, with natural and socio-economic factors contributing differently in each urbanization stage and climate zone. For example, globally, when UI is low (UI ≤ 0.25) and high (0.75 < UI ≤ 1), SOC storage tends to decrease with increasing UI, while at medium intensity (0.25 < UI ≤ 0.75), SOC storage shows an increasing trend. Globally, changes in socio-economic factors (population, GDP) are the main drivers of SOC storage changes during urbanization. Particularly at low and medium urbanization intensities, socio-economic contributions reach 98% and 89%, respectively. However, as urbanization intensity increases, the driving role of natural factors becomes more apparent, contributing over 40% in areas of high urbanization intensity.

How to cite: Xu, F. and Li, S.: Trends and drivers of the soil organic carbon stocks along the urban-rural gradients globally, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4361, https://doi.org/10.5194/egusphere-egu24-4361, 2024.

EGU24-4405 | Orals | SSS4.2

Quantifying Soil Quality in Dryland Regions as A Key Step in Phosphate Mining Restoration 

Tarin Paz-Kagan, Arnon Karnieli, and Yaron Ziv

Mining is crucial in driving economic development but entails extensive environmental damage, such as soil degradation and water and air pollution. Mining activity impacts the soil quality, often making it unable to support ecosystem function and structure and reducing its ecological resilience. Soil degradation reduces physical, chemical, and biological (PBC) soil properties. The current study aims to apply the soil quality index (SQI) to quantify soil restoration success in an open-pit phosphate mine in Israel’s hyper-arid environment. In this regard, we evaluated an ecological restoration practice that includes topsoil refilling compared to the adjacent undisturbed natural system. We used transformed and standardized scorings of 11 PBC soil properties that were further statistically integrated into overall SQI values. Our results revealed significant differences between the restoration practice areas and the nearby natural areas, with a higher soil quality value in the latter. It is proposed that the topsoil restoration method is mainly affected by soil biological indicators, such as soil organic matter, soil proteins, and polysaccharides related to biocrust development, and, to a lesser extent, by physical properties (primarily infiltration rate, followed by available water content). The former properties encourage the biocrust establishment, which is essential for soil surface stabilization. This, in turn, affects the water infiltration, nutrient availability, and erosion rates. The chemical indicators showed no significant differences between most sites for the overall soil quality. In conclusion, our results reflect a slow recovery of the SQI in the restored sites, demonstrating that achieving the quality of the natural areas requires a long-term recovery process. Moreover, the physio-biological indicators were more suitable for reliably estimating mining restoration practices in dryland areas. Our approach could have broader implications for evaluating the ecological restoration success in hyper-arid environments.

How to cite: Paz-Kagan, T., Karnieli, A., and Ziv, Y.: Quantifying Soil Quality in Dryland Regions as A Key Step in Phosphate Mining Restoration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4405, https://doi.org/10.5194/egusphere-egu24-4405, 2024.

EGU24-5424 | ECS | Orals | SSS4.2

Stoichiometry of soil organic matter and microbial functional traits altered after 5 years of maize monoculture 

María Martín Roldán, Doris Vetterlein, Mika Tarkka, and Evgenia Blagodatskaya

The long-term transformation of organic matter in agroecosystems is modulated by soil properties and functional traits of plants and microorganisms, and is an indicator of soil quality. We studied how contrasting soil texture (loamy vs sandy) and two plant genotypes (a wild type, WT and a mutant deficient in root hairs, rth3) altered organic matter through microbial functioning in a field experiment after 5 years of maize monoculture. Our hypotheses were that (1) loamy rather than sandy soil will promote a larger OM storage; and (2) root-hairs, entailing a higher root-soil interface and water retention in the rhizosphere, boosting microbial processes and OM fluxes, will increase OM content not only in the rhizosphere but in the long-term, also in the bulk soil. To address these hypotheses, plots were filled with homogenized soil, being sandy soil a mix of 16.7 % loam with quartz sand, and the two maize genotypes. After 5 years of monoculture, soil was collected at the early maize growth stage of BBCH19, in the first 20 cm and the 20 to 40 cm depths. We determined stoichiometric ratios of total (TOC/TN) and labile (DOC/DON) fractions of soil organic matter, and microbial eco-physiological indexes related to OM transformation and sustainability, i.e. respiration-to-biomass ratio, qCO2, and microbial-to-total organic C ratio, Cmic:Corg.  The 5- and 7-times larger C supply in loamy vs sandy soil, for WT and rth3, respectively was explained by 40% more efficient C metabolism, i.e. less C losses through respiration per biomass unit, by 90% lower specific labile C content (DOC:Cmic ratio) and by 60% faster microbial turnover (µmax-1) in the former. As the TN content was only 3.1 and 4.2 times larger in loamy than sandy soil for WT and rth3 respectively, the resulting C:N ratio was 1.7- times greater for loamy than sandy soil, indicating more unbalanced stoichiometry in the former for both genotypes. Remarkably, the C and N content increased 20 and 36 %, respectively, after 5 years of maize monoculture, in the plots under root hair-deficient mutant than under wild type maize resulting in significantly larger C storage at rth3-plots in loamy soil. This may be explained by the reported higher exudates production by rth3 under the field conditions. Soil depth up to 40 cm did not show big differences in the capacity for C storage, likely due to similar root density in both depths. Concluding, loamy soil showed a higher capacity of C storage through microbial turnover and sandy soil demonstrated larger C losses through DOC compounds and respiration after 5 years of maize monoculture. Finally, carbon availability was not the limiting factor in sandy soil for microbial growth, but rather other factors such as soil water holding capacity, or OM fluxes from rhizosphere to bulk soil.

How to cite: Martín Roldán, M., Vetterlein, D., Tarkka, M., and Blagodatskaya, E.: Stoichiometry of soil organic matter and microbial functional traits altered after 5 years of maize monoculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5424, https://doi.org/10.5194/egusphere-egu24-5424, 2024.

EGU24-5596 | ECS | Posters on site | SSS4.2

Assessing climatic, hydrogeological, and anthropogenic factors shaping sustainable soil management: A case study in northern Germany 

Vahid Sobhi Gollo, Amirhossein Hassani, Peter Fröhle, and Nima Shokri

Sustainable soil and land management which is vital for security of natural resources and food production is a complex task due to the wide range of parameters influencing soil quality and health (1,2). Various parameters, including climatic variables such as precipitation, evaporation, and, in coastal regions, sea level rise and saltwater intrusion (3), hydrogeological factors like groundwater table levels influencing evaporative fluxes (4), groundwater salinity, and soil properties as well as anthropogenic factors such as fertilization and land use, play important roles in sustainable soil management and health. In this study, we gathered diverse climatic, hydrogeological, and anthropogenic data within an intensive food production and natural preservation study area situated in North Sea adjacent northern Germany to explore the complex interplay of parameters affecting soil health and characterize the impact of these variables on sustainable soil management. The area is characterized by predominantly flat terrain with fertile soils utilized for agriculture and grazing. Additionally, it contains protected areas such as forests. Due to significant variations in land use and soil properties across the region, we categorized the area into subgroups for robust comparability. This involved dividing the region into agricultural, grassland, and forest areas, each identified by specific characteristics, such as crop production, meadow type, fertilization method, and soil nutrient holding capacity. Additional parameters including precipitation, evaporation, and leakage were factored into a groundwater recharge model for the area. Statistical analysis and machine learning algorithms were employed to assess the interrelations among these parameters affecting sustainable soil management. Recognizing these interrelations, we adapted our model to potential future scenarios and discussed how hypothetical alterations to parameters such as groundwater recharge and added fertilizer could impact land management in the study area. Our findings are applicable to areas employing similar land management practices, offering insights into the vulnerabilities and potentials of these regions in the face of a changing climate and are useful for implementing mitigation measures against land degradation and preventing the loss of fertile soil.

 

1. Hassani, A., Azapagic, A., Shokri, N. (2020). Predicting Long-term Dynamics of Soil Salinity and Sodicity on a Global Scale, Proc. Nat. Sci., 117(52), 33017-33027, https://doi.org/10.1073/pnas.2013771117

2. Hassani, A., Azapagic, A., Shokri, N. (2021). Global Predictions of Primary Soil Salinization Under Changing Climate in the 21st Century, Nat. , 12, 6663. https://doi.org/10.1038/s41467-021-26907-3

3. Nevermann, H., Gomez, J.N.B., Fröhle, P., Shokri, N. (2023), Land loss implications of sea level rise along the coastline of Colombia under different climate change scenarios, Clim. Risk Manag., 39, 100470, https://doi.org/10.1016/j.crm.2022.10047

4. Sadeghi, M., Shokri, N., Jones, S.B. (2012). A novel analytical solution to steady-state evaporation from porous media. Water Resour. Res., 48, W09516, https://doi.org/10.1029/2012WR012060

How to cite: Sobhi Gollo, V., Hassani, A., Fröhle, P., and Shokri, N.: Assessing climatic, hydrogeological, and anthropogenic factors shaping sustainable soil management: A case study in northern Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5596, https://doi.org/10.5194/egusphere-egu24-5596, 2024.

The conversion of open fields to greenhouse cultivation leads to an increase in the amount and frequency of fertilization, as well as an increase in tillage intensity, which significantly affects soil organic carbon turnover and sequestration. In this study, four types of soils were selected in the coastal area of southeast China based on a sequence of greenhouse cultivation years of 0, 8, 18, and 36. The study fractionated the soil into four organic fractions: free mineral-associated organic carbon (f-MAOC), occluded mineral-associated organic carbon (o-MAOC), free particulate organic carbon (f-POC), occluded particulate organic carbon (o-POC), using particle size and density separation. The organic carbon content and natural abundance of 13C were measured for each of these fractions, as well as for the bulk soil. Key findings include a significant increase in bulk soil organic carbon with extended greenhouse cultivation, although differences between 18 and 36 years were not significant (27.4 g kg-1 and 31.7 g kg-1 respectively). o-MAOC and o-POC contents increased initially, then declined after 18 years. Notably, f-POC content significantly rose after 36 years, reaching 9.91 g kg-1. The δ13C values for f-MAOC, o-MAOC, and f-POC showed similar increasing trends, peaking after 18 years. The carbon flow analysis revealed the main carbon turnover pathway from f-POC to o-MAOC, with reverse transfers occurring after 18 and 36 years. It highlighted a saturation limit in the sequestration capacity of occluded organic carbon and significant accumulation of labile organic carbon due to long-term greenhouse cultivation. These findings offer new insights into carbon management in agricultural soils.

How to cite: Tian, Y., Liu, J. J., and Lu, S.: The impact of converting open-field cultivation to greenhouse cultivation on the accumulation of organic carbon in coastal soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7247, https://doi.org/10.5194/egusphere-egu24-7247, 2024.

EGU24-7709 | Posters on site | SSS4.2

How biochar suspension influences soil microbial activity and phosphorus availability 

Iryna Loginova, Nataliya Bilyera, Callum Banfield, Denis Kutoley, Yakov Kuzyakov, and Michaela A. Dippold

Biochar (BC) application to soil is a method of long-term carbon (C) sequestration in croplands. Along with contribution to climate change mitigation, agronomic benefits of biochar are widely accepted. Amelioration and nutritive benefits of biochar are mainly attributed to high applications rates, which may not be viable for farmers. We suggest a new approach: band application, which implements biochar in modern intensive crop rotations and optimizes both C and nutrients cycles (i.e. phosphorus (P)).

As maize is globally one of the most widely planted crops, corncobs (CC) may be utilized for BC production. Corncob biochar (CC BC) may be implemented into the farming practice as suspension with liquid phosphorus solution jointly applied in band in the close proximity to seeds.

We conducted an incubation experiment to evaluate the short-term effects (within 32 days) of corncob biochar and inorganic P application on P availability and microbial activity in a loamy Luvisol.

Corncobs were pyrolyzed to biochar (350oC; 0.2-0.3oC s-1), grinded (<200 µm), suspended and mixed with phosphate solution (as monopotassium phosphate). We compared liquid phosphorus (P) and joint P and BC application (BC+P) to control (water). The application rates were: 30 kg ha-1 P (200 mg kg-1 P) and 300 kg ha-1 BC (0.2% w/w). Soil was sampled on day 7, 14, and 32 to measure pH, available P, enzyme kinetics, microbial biomass C, N, and P.

Despite the alkaline pH of BC (pH 8.7), application of BC+P and P decreased soil pH (5.6-5.7) compared to soil in control (5.8). Acidifying effect of suspensions was attributed to used phosphate source and may differ for others. BC+P did not alter soil P availability compared to solely P applied. Thus, dynamics of soil available P within 32 days was mainly attributed to soil processes but not the BC effect.

Higher basal respiration in amended soil compared to control within first 7 days indicates that physiological status of microorganisms was affected by P and BC+P application. But this was independent on changes in microbial biomass C and dissolved organic C. Microbial biomass-specific activity of beta-glucosidase and leucine aminopeptidase (but not acid phosphatase) in BC+P soil were lower compared to only P application, that may be caused by adsorbing properties of BC. The application BC+P increased the catalytic efficiency (Ka) of all enzymes compared to only P, which indicates the positive effect of biochar on enzymatic efficiency of soil.

Sole P application resulted in acceleration of P immobilization on day 32, as microbial molar C:N:P ratio for only P (18:2:1) differed from control and BC+P (35:3:1 and 36:4:1, accordingly). Principal Component Analysis revealed that BC+P treatment differed from the control and solely P applied at all time points.

To conclude, joint application of corncob biochar suspension and phosphorus solution may not only increase soil P availability, but prevent high P immobilization by microorganisms and facilitate higher enzyme efficiency to potentially increase nutrient availability for seedlings in the application bands.

How to cite: Loginova, I., Bilyera, N., Banfield, C., Kutoley, D., Kuzyakov, Y., and Dippold, M. A.: How biochar suspension influences soil microbial activity and phosphorus availability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7709, https://doi.org/10.5194/egusphere-egu24-7709, 2024.

EGU24-7713 | Posters on site | SSS4.2

Status of soil health after 18 years of systematic tillage 

Barbara Simon, Györgyi Gelybó, Igor Dekemati, Hanaa M.I. Tharwat, Maxwell Maimela Modiba, and Márta Birkás

Carbon sequestration in our soils in the form of stable, humus materials is one of the most important tasks of our time, which can be monitored by tests carried out in long-term cultivation experiments. In our research, our objective was to determine the soil physical (0-10, 10-20, 20-30 and 30-40 cm depth: bulk density, soil moisture content), chemical (0-20 cm: pH(H2O), pH(KCl), soil organic carbon) and biological properties (0-20 cm: abundance, biomass, species composition of earthworms, soil microbial respiration – SMR). Out of the six soil cultivation methods (no-till, loosening, shallow and deep cultivation, disking and ploughing), we selected three (no-till – NT; shallow cultivation – SC, and ploughing – P) for our experiment. Based on our results, we can say that there was significant difference among the treatments in bulk density in the top layer (0-10 cm) (NT > SC, P), and NT was significantly greater than P in the deeper layers (10–20, 20–30, 30–40 cm). Soil moisture content was only significantly different in the lowest examined layer (30-40 cm), ie. P > SC = NT. The soil organic carbon content (0-10cm) of the investigated treatments was the highest in NT (2.5%), followed by SC (2.4%) and P (2.0%). Soil microbial respiration was significantly greater in NT than in SC and P. The abundance and biomass of earthworms was the highest in the NT treatment (189 ind m-2, 41.26 g m-2), which was followed by SC (125 ind m-2, 36.9 g m-2) and then by P (48 ind m-2, 7.4 g m-2). Thus, NT offers beneficial habitat for earthworms and microorganisms, high SOC storage capacity, whereas the physical parameters tend to be less convenient due to soil compaction in our experiment. Therefore, SC can offer an alternative approach for sustainable soil tillage.

How to cite: Simon, B., Gelybó, G., Dekemati, I., M.I. Tharwat, H., Maimela Modiba, M., and Birkás, M.: Status of soil health after 18 years of systematic tillage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7713, https://doi.org/10.5194/egusphere-egu24-7713, 2024.

EGU24-7955 | ECS | Orals | SSS4.2 | Highlight

Soil health increases primary productivity across Europe 

Ferran Romero, Maëva Labouyrie, Alberto Orgiazzi, Cristiano Ballabio, Panos Panagos, Arwyn Jones, Leho Tedersoo, Mohammad Bahram, Carlos Guerra, Nico Eisenhauer, Dongxue Tao, Manuel Delgado-Baquerizo, Pablo García-Palacios, and Marcel van der Heijden

The role of soil health in regulating primary productivity at large scale across different land-use types remains poorly understood. This hinders our ability to predict the impact of soil degradation on essential ecosystem services such as food provision and climate regulation. To address this gap, we conducted a pan-European observational field study using data from 588 sites and 27 countries to investigate the link between soil health (a composite index based on soil properties, biodiversity, and plant disease control) and primary productivity across three major land-use types: woodlands, grasslands, and croplands. We found that soil health in woodlands was 31.4% higher than in grasslands, and 76.1% higher than in croplands. We further observed that soil health was positively linked to cropland and grassland productivity at the continental scale. Woodland productivity was linked to climate conditions rather than to soil health status. We observed that soil organic carbon and the richness of Acidobacteria, Firmicutes, and Proteobacteria had a positive effect on primary productivity. Among microbial functional groups, we found that nitrogen-fixing bacteria and mycorrhizal fungi positively related to primary productivity in croplands and grasslands, while plant pathogens showed a negative relationship. Together, our results point to the importance of soil biodiversity and soil health for maintaining primary productivity across contrasting land-use types.

How to cite: Romero, F., Labouyrie, M., Orgiazzi, A., Ballabio, C., Panagos, P., Jones, A., Tedersoo, L., Bahram, M., Guerra, C., Eisenhauer, N., Tao, D., Delgado-Baquerizo, M., García-Palacios, P., and van der Heijden, M.: Soil health increases primary productivity across Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7955, https://doi.org/10.5194/egusphere-egu24-7955, 2024.

EGU24-8176 | ECS | Posters on site | SSS4.2

AI-driven spatiotemporal quantification and prediction of soil salinity at European scale using the LUCAS database 

Mohammad Aziz Zarif, Amirhossein Hassani, Panos Panagos, Inma Lebron, David A. Robinson, and Nima Shokri

Soil salinization, referring to the excessive accumulation of soluble salt in soils, adversely influences nutrient cycling, microbial activity, biodiversity, plant growth and crop production thus affecting soil health and ecosystem functioning. Soil salinity quantification is a major step toward mitigation of its effects. Therefore, developing quantitative tools to predict soil salinity at regional and continental levels under different boundary conditions and scenarios is crucial for sustainable soil management and security of natural resources (1-3). This study proposes an AI-driven soil salinity quantification and projection approach focused on EU soils using a set of environmental covariates which consist of soil properties, terrain attributes, climate, and remotely sensed variables. The soil salinity point data which was used for model training and validation, expressed as electrical conductivity, was obtained from the LUCAS survey for the years 2015 and 2018. The novelty of this work lies in the careful integration of LUCAS data point with AI-driven models aiming to produce soil salinity maps for EU soils. Different AI algorithms including Random Forest, LightGBM, and XGBoost were used in this study enabling us to evaluate the performance of each algorithm in predicting soil salinity across EU with the XGBoost algorithm producing the most accurate results. Feature engineering technique was applied to reduce the models’ collinearity; thus 17 covariates were selected as the most important model variables influencing soil salinity from the initial 34 covariates investigated in our analysis. The output of the predictive model will be a gridded dataset illustrating the spatial and temporal (yearly) distribution of soil salinity across the EU, accompanied by the corresponding uncertainty maps with the spatial resolution of 1-km. This information is crucial for identifying regions with elevated salinity levels and formulating necessary action plans to mitigate the situation.

References

  • Hassani, A., Azapagic, A., Shokri, N. (2020). Predicting Long-term Dynamics of Soil Salinity and Sodicity on a Global Scale, Proc. Nat. Acad. Sci., 117(52), 33017-33027, https://doi.org/10.1073/pnas.2013771117
  • Hassani, A., Azapagic, A., Shokri, N. (2021). Global Predictions of Primary Soil Salinization Under Changing Climate in the 21st Century, Nat. Commun., 12, 6663. https://doi.org/10.1038/s41467-021-26907-3
  • Shokri-Kuehni, S.M.S., Raaijmakers, B., Kurz, T., Or, D., Helmig, R., Shokri, N. (2020). Water Table Depth and Soil Salinization: From Pore-Scale Processes to Field-Scale Responses. Water Resour. Res., 56, e2019WR026707, https://doi.org/10.1029/2019WR026707

How to cite: Zarif, M. A., Hassani, A., Panagos, P., Lebron, I., Robinson, D. A., and Shokri, N.: AI-driven spatiotemporal quantification and prediction of soil salinity at European scale using the LUCAS database, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8176, https://doi.org/10.5194/egusphere-egu24-8176, 2024.

EGU24-8568 | ECS | Posters virtual | SSS4.2

Prospects of returning radioactively contaminated lands in the northern part of Ukraine to economic use 

Volodymyr Illienko, Olga Kosarchuk, Alla Klepko, Dmytro Lazarev, and Mykola Lazarev

About tens thousands hectares of agricultural land in the norther part of Ukraine cannot be used for agricultural production under the Law 'On the Legal Regime of the Territory Affected by Radioactive Contamination as a Result of the Chornobyl Disaster' since 1986 only in Zhytomyr Oblast. Additionally, due to Russia's aggressive military actions, large areas of Ukraine (currently near 800 thousands ha) are unable to carry out agricultural work. It may take over minimum ten years to clear the territories of mines. In these circumstances, revision of the actual contamination levels of lands may help to increase the share of agricultural lands in Ukraine. But before the economic use of these lands, it is essential to conduct a survey to determine the level of soil contamination with radionuclides and assess the radiological situation. This data will form the basis to decide whether the previously contaminated lands can be returned to economic use.

We conducted the radiological surveys, where the radiation background indicators were measured in 2023 in Narodychi and Vyazivka using modern devices that allow automatic registration of routes with GPS reference and marking of gamma background parameters. We recorded from 200 to 600 points on each field to build maps of the spatial distribution of soil radioactive contamination. The Narodychi community in Zhytomyr Oblast provided 30 field plots marked as 'radioactive land' in the State Land Cadastre of Ukraine. These plots include 23 agricultural lands covering an area of over 1400 hectares and 7 floodplain meadows of the Uzh and Zherev rivers covering 1200 hectares. The levels of radioactive contamination in the soil were determine on the agricultural lands, specifically with regards to 137Cs, 90Sr, and partially 238-240Pu isotopes. The maps were constructed to determine the density of radioactive contamination of soil in each field based on the obtained results.

We concluded, that the density of 137Cs, 90Sr and 238-240Pu contamination in the agricultural lands around the settlements of Narodychi and Vyazivka did not exceed the lower limit of the criteria for their classification as an unconditional (mandatory) resettlement zone. Specifically, cesium, strontium and plutonium isotopes did not exceed 555 kBq/m2, 111 kBq/m2 and 3.7 kBq/m2, respectively. While the criteria for assignment to the guaranteed voluntary resettlement zone are limited to cesium isotopes from 185 to 555 kBq/m2, strontium from 5.55 to 111 kBq/m2, or plutonium from 0.37 to 3.7 kBq/m2 (according to Article 2 of the Law of Ukraine "On the Legal Regime of the Territory Affected by Radioactive Contamination as a Result of the Chornobyl Disaster"). Accordingly, all surveyed land should lose its status as 'radioactive land' and can be returned to economic use.

We acknowledge the National Research Foundation of Ukraine for the financial support of this research (Project number 2022.01/0188).

How to cite: Illienko, V., Kosarchuk, O., Klepko, A., Lazarev, D., and Lazarev, M.: Prospects of returning radioactively contaminated lands in the northern part of Ukraine to economic use, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8568, https://doi.org/10.5194/egusphere-egu24-8568, 2024.

EGU24-8602 | ECS | Orals | SSS4.2

Glucose Release Controlled by Sugar Transporters in Wheat Plant Modulates Microbial Growth and Enzyme Activity Around the Root 

Mehdi Rashtbari, Seyed Sajjad Hosseini, Ahmad Samir Azimi, Markus Schemmel, Zheng Zhou, Lingyue Han, Daguang Cai, and Bahar S. Razavi

Soil microbial communities are the main regulators of ecosystem services and are vital for carbon and nutrient cycling. Root exudates play a crucial role in shaping soil microbial assembly and hence, influencing biogeochemical processes that impact plant growth. Here, we hypothesized that continuous wheat cultivation would lead to lower glucose release, resulting in lower microbial growth, activity, and biomass. For the first time in situ glucose imaging was optimized for studying these interactions in the field - using installed root windows in the first (W1) and third (W3) wheat after break crop plots. Root and leaf samples were collected to determine the expression of sugar transporter genes using transcriptomics. Soil microbial respiration (characterized by Substrate Induced Growth Respiration (SIGR)) and enzyme kinetics (measured by fluorometric microplate assays of 4-methylumbelliferone (MUF) and 7-amino-4-methyl coumarin (AMC)) were measured in rhizosphere, root affected and bulk soil samples to assess C, N, and P acquisition.

W3 had the lowest proportion of hotspots for glucose release with 1.35 % of the total soil surface area, indicating a 17.7 % decline compared to W1. Also, we found that the expressions of functional orthologous genes of SWEET1a in wheat roots were significantly upregulated in W3 compared to W1. Furthermore, total microbial biomass dropped by 11.8 and 4.8 % in W3 in the rhizosphere and bulk soils compared to W1, respectively. The growing microbial biomass in the rhizosphere soil of W1 was about five times higher than W3. For β-glucosidase activity, soil samples from W1 had a higher maximum velocity of enzyme activity (Vmax) compared to W3 samples, in all studied compartments (rhizosphere, root affected and bulk soil samples). Lower glucose release in W3 highlights the importance of root exudates in shaping rhizosphere interactions and microbial community dynamics in response to continuous wheat cultivation. Also, differences in SWEET gene expression in wheat roots and leaves, indicates shifts in nutrient uptake and resource allocation strategies. This decline in glucose release observed under W3 compared to W1 underscores the significance of root exudates in shaping rhizosphere interactions.

Overall, the shift in glucose release is linked to altered root physiology and exudation processes, potentially reflecting the plant's strategy to create a less favorable environment for ambuscade and opportunistic pathogens. Hence, this study provides novel insights into the complex interactions between continuous wheat cultivation, root exudation, microbial dynamics, gene expression, and enzymatic activities.

How to cite: Rashtbari, M., Hosseini, S. S., Azimi, A. S., Schemmel, M., Zhou, Z., Han, L., Cai, D., and Razavi, B. S.: Glucose Release Controlled by Sugar Transporters in Wheat Plant Modulates Microbial Growth and Enzyme Activity Around the Root, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8602, https://doi.org/10.5194/egusphere-egu24-8602, 2024.

EGU24-8831 | ECS | Orals | SSS4.2

Evaluation of the relation between soil biomass of arbuscular mycorrhizal fungi and glomalin-related soil protein in conservation agriculture 

Stamatios Thomopoulos, Lars Elsgaard, Lars Juhl Munkholm, and Sabine Ravnskov

Arbuscular mycorrhizal fungi (AMF) are indicators of soil health and are associated with various soil benefits, primarily linked to glomalin accumulation from hyphal turnover. However, the direct connection between glomalin-related soil protein (GRSP) and AMF has been questioned. In addition, conservation agriculture (CA) stands out as a pivotal plant production system that promotes agricultural sustainability and enhances soil quality.  In particular, the combination of minimal soil disturbance with residue retention has been linked with alterations in microbial biomass. The study aimed to explore the correlation between various fractions of GRSP and fatty acid fractions in the soil, along with examining the long-term impact of conservation agriculture practices on AMF biomass and GRSP content. Findings revealed a positive correlation between easily extractable (EE) GRSP and phospholipid fatty acid (PLFA) 16:1ω5, while no significant correlations were found for difficultly extractable (DE) or total GRSP fractions. These results highlight the complexity of GRSP dynamics and the need for further research on different fractions and their relation to AMF biomass. Additionally, the study demonstrated that mechanical soil management had a more significant impact on AMF hyphal biomass and EE-GRSP compared to residue management. Direct seeding, a reduced tillage approach, led to higher hyphal biomass and EE-GRSP, indicating AMF sensitivity to tillage intensity. This suggests that tillage practices exert a more substantial influence on AMF abundance and GRSP content than residue management.

How to cite: Thomopoulos, S., Elsgaard, L., Juhl Munkholm, L., and Ravnskov, S.: Evaluation of the relation between soil biomass of arbuscular mycorrhizal fungi and glomalin-related soil protein in conservation agriculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8831, https://doi.org/10.5194/egusphere-egu24-8831, 2024.

EGU24-10503 | Orals | SSS4.2

Unraveling the relationship between rural farm household wealth, carbon storage, and soil quality in Namibia's Zambezi Region 

Alexandra Dr. Sandhage-Hofmann, Foerster Mira, Amatotsero Vanessa, Börner Jan, Gebrekidan Bisrat, and Amelung Wulf

A significant portion of smallholder farming systems in Sub-Saharan Africa are marked by significant heterogeneity in both biophysical and socio-economic conditions. Resource access and the patterns of resource allocation at household level are often co-determined by wealth. We hypothesized that wealth plays a pivotal role in the effect of future-oriented farm management on soil organic carbon storage (SOC) and soil quality. To test this hypothesis, we conducted a study involving 42 households categorized in three wealth classes (high, medium, low) based on farm-household survey data from the Namibian Zambezi region. Soil samples were collected up to a depth of 1 m with a focus on soil organic carbon and nitrogen throughout the soil profile. Topsoils were additionally analyzed for texture, cation exchange capacity (CEC), pH, and available phosphorus; field size was measured. A follow-up survey wave captured information on crop species, yield, and soil management practices.

Results of the survey showed, that farmers of our study area typically burn their field regularly before the cultivation period. With rare exceptions no farmer fertilized their fields, neither with mineral fertilizer nor with manure. Results indicated that relatively wealthier farmers had larger fields, yet intriguingly, their yields per hectare were not higher than for farmers in lower wealth terciles. Notably, the Arenosols, which are widespread in the Zambezi region, had lower sand and higher clay and silt contents among the relatively wealthier farmers. Moreover, high wealth class showed significantly higher soil organic carbon and nitrogen concentrations in the topsoils compared to medium and low wealth classes along with CEC values. Though, no such a trend was observed for available phosphorous and pH. The elevated levels of soil organic carbon and nitrogen of relatively wealthy farmers persisted consistently up to a depth of 1 meter. These results indicate that the soils of farmers in the high wealth class have inherently better soil conditions. Contrary to our hypothesis, the wealthier farmers did not seem to invest more in land management in order to improve soil conditions. Instead, historically they seem to have been more inclined to settle on the more fertile soils in the Zambezi region of Namibia and benefit from larger fields and thus higher quality natural resources.

How to cite: Dr. Sandhage-Hofmann, A., Mira, F., Vanessa, A., Jan, B., Bisrat, G., and Wulf, A.: Unraveling the relationship between rural farm household wealth, carbon storage, and soil quality in Namibia's Zambezi Region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10503, https://doi.org/10.5194/egusphere-egu24-10503, 2024.

EGU24-10649 | ECS | Posters on site | SSS4.2

Long-Term Effects of Chabazite-Zeolite Tuff Amendments on Soil Quality in Arable and Perennial Cropping Systems 

Giacomo Ferretti, Christoph Rosinger, Eugenio Diaz-Pines, Thomas Weninger, Orracha Sae-Tun, Barbara Faccini, Massimo Coltorti, and Katharina Keiblinger

The use of natural zeolites to enhance soil properties has gained popularity, but there are limited long-term data on its effects. This study evaluates the Soil Quality Index (SQI) in three agricultural soil systems, 6-10 years post-application of chabazite zeolite. These soils had different management practices: intensive arable (cereals), intensive perennial (pear), and organic perennial (olive).

In the arable system, chabazite was applied at rates of 5, 10, and 15 kg m-2, compared to unamended soil. Perennial systems were tested at 5 kg m-2. Analysis of 25 soil parameters related to soil health was conducted at each site, including soil physic-chemical properties (bulk density, pH, electrical conductivity, cation exchange capacity, C-N-P species), biological properties (microbial C-N-P, enzyme activity) and gaseous emissions (CO2, N2O and NH3 fluxes). Principal Component Analysis (PCA) was performed to determine the SQI using a linear scoring method.

In the arable-cereal field, chabazite increased the SQI significantly from ~0.3 to ~0.6, but no clear dose effect was evident. The SQI also rose significantly in perennial fields thanks to the use of chabazite zeolites. Different indicators have been selected by the PCA at each site, suggesting that chabazite addition impacted soil quality differently in each cropping system.

Overall, this research underscores chabazite zeolite potential to boost soil health, indicating a substantial enhancement in soil quality post-amendment.

How to cite: Ferretti, G., Rosinger, C., Diaz-Pines, E., Weninger, T., Sae-Tun, O., Faccini, B., Coltorti, M., and Keiblinger, K.: Long-Term Effects of Chabazite-Zeolite Tuff Amendments on Soil Quality in Arable and Perennial Cropping Systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10649, https://doi.org/10.5194/egusphere-egu24-10649, 2024.

EGU24-13121 | Orals | SSS4.2 | Highlight

Bridging the Soil Health Data Gap: informing prioritization of soil data collection efforts 

Ester Miglio, Fabrizio Albanito, Simone Sala, and Pete Smith

The sampling and analysis or visual examination of soil to assess its health status are widely practiced from plot to national scales. However, available data are often not made easily accessible and new data are not always shared with the wider public, creating a partial understanding of soil processes and health status across different geographies, as well as a misuse of resources.

To address these challenges, Varda has created an interactive digital soil platform, named SoilHive, which provides an overview of existing soil data across the globe, facilitates the identification of soil data gaps across regions, and supports soil data sharing and interoperability.

To facilitate the identification of functional soil data gaps, Varda created a visualization tool to enable users to identify the extent to which the data available in their selected regions of interest allow them to characterize key soil characteristics and functions, starting with soil health. To this end, Varda collaborated with a team at the Aberdeen University to define a minimum set of indicators and associated soil properties, covering diverse soil degradation processes and ecosystem services, to describe soil health at the local level with a focus on agricultural settings. SoilHive users will be able to select a region of interest and verify how many of those indicators are available to characterize soil health: the gap between the available data and the required data will be marked as the "Soil Health Data Gap" and described as the percentage of data over the total number of indicators.

This Soil Health Data Gap could facilitate the identification of those regions where data collection efforts should be intensified, informing the prioritization of actions aimed at bridging existing gaps while expanding the availability of soil data. Several proposed activities to address this gap include targeted soil mining activities to collect historical and non-digitized soil data, advocating for data-sharing collaborations among diverse stakeholders, and organizing brand-new soil sampling campaigns. Moreover, additional soil health definitions could be used to provide the user with different representations of soil health data gaps, in line with these definitions.

Closing the existing Soil Health Data Gaps bears significant importance, as it empowers us to deepen our comprehension of soil health dynamics. By expanding soil data transparency across all sectors and stakeholders, we would gain the ability to make well-informed decisions regarding optimal soil management practices, efficiently allocate resources, and strive to enhance soil health for the betterment of both present and future generations.

How to cite: Miglio, E., Albanito, F., Sala, S., and Smith, P.: Bridging the Soil Health Data Gap: informing prioritization of soil data collection efforts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13121, https://doi.org/10.5194/egusphere-egu24-13121, 2024.

EGU24-13198 | ECS | Orals | SSS4.2

Microbial resistance in rhizosphere hotspots under biodegradable and non-degradable microplastic amendment: Community and functional sensitivity 

Bahar S. Razavi, Bin Song, Siyi Shang, Feng M. Cai, Zihao Liu, Jie Fang, Na Li, and Jonathan M. Adams

The annual global production of plastics is currently nearly 400 million tons, leading to widespread concern regarding the quantity of degradation-resistant plastics entering terrestrial environments. Farmland soils are a major sink for microplastics (MPs, size <500 μm) owing to the wide use of plastic film mulching. Although the influence of MPs on soil parameters has been investigated, the response of microbiomes to soil microenvironments with contrasting limiting factors, particularly in flooded soil environments such as rice paddies, remains unknown. Using zymography and high-throughput sequencing, we conducted an experiment with polylactide (PLA) and polyvinyl chloride (PVC) MPs to compare the effects of biodegradable and conventional MPs on rice growth, exoenzyme kinetics, and microbial communities. Both conventional and biodegradable MPs significantly inhibited rice growth, possibly by affecting nutrition. Compared with the control soils, both PLA- and PVC-amended soils exhibited higher enzyme activity in the hotspots. The enzymatic resistance to MPs was higher in ‘coldpots’ with PVC addition compared to that in PLA and control treatments. 
Bacterial biomass increased but diversity declined in PLA-amended soils, possibly because PLA particles act as carbon input inhabited the population of bacteria. Our findings suggest that co-occurrence networks among bacteria were strengthened by the addition of both MPs, with an increase in microbial functionality resilience and enhanced competition with neighboring roots for nutrient mining. This competition for nutrients may 
adversely affect plant growth. 

How to cite: Razavi, B. S., Song, B., Shang, S., Cai, F. M., Liu, Z., Fang, J., Li, N., and Adams, J. M.: Microbial resistance in rhizosphere hotspots under biodegradable and non-degradable microplastic amendment: Community and functional sensitivity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13198, https://doi.org/10.5194/egusphere-egu24-13198, 2024.

EGU24-13244 | ECS | Posters virtual | SSS4.2

Promoting Carbon Storage and Health in Urban Soils through Sustainable Management Practices   

Atefeh Movassagh, Bibiana Betancur Corredor, and Martin Hamer

Sustainable urban soil management is becoming increasingly crucial due to its vital role in climate and water regulation and its significant potential for storing soil organic carbon (SOC). This significance is emphasized considering the ongoing urbanization and climate change issues. Although SOC is influenced by many factors, such as soil type and climate fluctuations (temperature, precipitation patterns), on a regional scale, land use and management practices (e.g., fertilization, irrigation) can have a more significant impact on SOC storage and the balance of soil-atmosphere carbon fluxes. However, there is still a limited understanding of the amount of humus content in urban soils and the effects of urban development and management practices on soil health and carbon storage. We investigated how management practices in urban green spaces influence soil carbon storage as the primary indicator of soil health.

The present study was carried out in the Bonn-Rhein-Sieg area, as the region is vital in terms of sustainable urban and regional development with a high population density (Rhein-Sieg district: 338.4, Bonn: 520.9 inhabitants/km2) in Germany. A survey was conducted with owners and managers of urban private (e.g., allotment and backyard garden) and public green spaces on the practices for the most common vegetation types (e.g., lawn, vegetable, ornamental). In the autumn and winter of 2022, 248 soil samples (0–20 cm depth) were collected from 95 private and public green spaces in the study area and analyzed for physiochemical and biological properties. Multivariate Analysis of Variance (MANOVA) was performed to assess the effects of different management practices on soil properties.

Our results indicate that the average SOC stock in public green areas (94.67 Mg ha-1) is substantially higher than in private ones (house garden 67.72 Mg ha-1, allotment garden 73.15 Mg ha-1). Moreover, urban green spaces with vegetables (91.66 Mg ha-1) and ornamentals (85.05 mg ha-1) show greater SOC stock levels when comparing vegetation types (lawn 62.48 Mg ha-1). Significant differences in SOC are also found for various management practices. Specifically, the monthly fertilization schedule resulted in higher SOC levels (127.37 Mg ha⁻¹) compared to the yearly fertilization schedule (76.88 Mg ha⁻¹). Additionally, the use of organic fertilizers contributed to increased SOC levels (84.40 Mg ha⁻¹) in contrast to mineral fertilizer applications (65.31 Mg ha⁻¹). The average SOC stock in all the studied urban green spaces (85 mg ha-1) was higher than the average SOC stock in arable soils in Germany (47.30 Mg ha-1). The higher SOC in the region could be due to vegetation types and fertilization frequencies, which show statistically significant effects (p-value <0.001). Other management practices (e.g., irrigation type and frequency) did not show a significant effect. Our findings highlight the significance of soil management practices, particularly in selecting vegetation types and determining fertilization frequency, as essential factors influencing urban SOC.

How to cite: Movassagh, A., Betancur Corredor, B., and Hamer, M.: Promoting Carbon Storage and Health in Urban Soils through Sustainable Management Practices  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13244, https://doi.org/10.5194/egusphere-egu24-13244, 2024.

EGU24-14456 | Orals | SSS4.2

Effect of Alternative Dryland Crops on Soil Microbial Communities 

Sadikshya Dangi, Brett Allen, Jay Jabro, Tatyana Rand, Joshua Campbell, and Rosalie Calderon

Soil microbial community composition associated with novel rotation crops could contribute to increased yield to subsequent crops and an important factor influencing the composition of the rhizosphere microbiome. However, the effect of alternative dryland crops on soil microbial community composition is not clear in the northern Great Plains (NGP). The objective of this study therefore was to evaluate the effects of oilseed crops Ethiopian mustard (Brassica carinata A.) or camelina (Camelina sativa L.) or a 10-species forage/cover crop (CC) mix and fallow on soil microorganisms. A field study was conducted from 2014 to 2020 in the northern Great Plains, USA and was designed as a randomized complete block with three replications in a no-tillage system. Results showed that total bacterial proportion was significantly higher in camelina and fallow compared to CC and carinata. Total fungal proportion was significantly higher under CC mix compared to camelina and fallow. Fungal to bacterial ratio was significantly higher in CC and carinata compared to fallow. Fungi are often considered a good indicator of soil health while bacteria are crucial in soil functions. The changes in specific microbial communities due to crop-related alterations might play a key role in the yield of subsequent crop. Mechanisms responsible for these differences will be discussed.

How to cite: Dangi, S., Allen, B., Jabro, J., Rand, T., Campbell, J., and Calderon, R.: Effect of Alternative Dryland Crops on Soil Microbial Communities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14456, https://doi.org/10.5194/egusphere-egu24-14456, 2024.

EGU24-15886 | Orals | SSS4.2

Understanding the Complexity: A Meta-Analysis of the Impact of Land Use Intensification on Soil Fauna in Global Agroecosystems 

Bibiana Betancur Corredor, Andrey Zaitsev, and David Russell

Increased land use intensity, especially the transition from extensive to intensively managed agroecosystems, is frequently referred to as one of the primary causes of the decline in global biodiversity and is thought to be the primary force influencing soil biodiversity. For appropriate land management in the face of future land use change, it is essential to comprehend how soil biodiversity responds to various land use regimes. Still, there is a great deal of uncertainty regarding the consistent responses of various taxonomic groups to intensification of land use.

We systematically assessed and quantified through meta-analysis the effects of various forms of land use intensification on soil organisms in global agroecosystems (192 studies included, 3190 pairwise observations comparing intensified land use to undisturbed ecosystems across 59 countries) and analyzed the dependence of these effects on abiotic factors such as soil properties (organic matter, pH, nutrient and water availability, texture) and climatic zone.

We observed a substantial decline in springtails abundance (-34%) and species richness (-16%), while earthworms experience a positive abundance trend (+217%) but a reduction in species richness (-12%). Enchytraeids exhibit a negative impact on abundance (-32%) with no effect on species richness. Mites show a positive increase in abundance (+129%), but a significant reduction in species richness (-50%). Nematodes, on the other hand, experience a negative impact on abundance (-7%) with no effect on species richness.

Focusing specifically on earthworms, we observed varying effects depending on the specific forms of intensification employed. Positive impacts on earthworm abundance are observed with agroforestry (+60%), cover crops, low input cropping (+113%), managed grasslands (+52%), vegetable gardens (+52%), and pastures (+218%). Conversely, negative effects are noted in arable cropland (-24%), orchards (-35%), specialty crops (-61%), crop livestock integration (-13%), and managed forests (-95%). Furthermore, the analysis reveals that the intensification effects on earthworm abundance vary across different climatic zones, with significant impacts observed in zones A and C. Higher intensification effects are noted in areas with greater mean annual precipitation, higher soil pH, finer soil textures (clayey, loamy, and silty), and increased organic matter content.

This comprehensive exploration sheds light on the intricate dynamics between land-use intensification and soil fauna, providing valuable insights for sustainable land management practices tailored to different ecological contexts.

How to cite: Betancur Corredor, B., Zaitsev, A., and Russell, D.: Understanding the Complexity: A Meta-Analysis of the Impact of Land Use Intensification on Soil Fauna in Global Agroecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15886, https://doi.org/10.5194/egusphere-egu24-15886, 2024.

EGU24-18198 | ECS | Posters on site | SSS4.2

Earthworm populations and their drivers in agroecosystems across Europe: land use, soil properties, climatic factors 

Marion Mittmannsgruber, Guénola Peres, Rajasekaran Murugan, and Johann Zaller

Earthworms are a crucial part of soil biodiversity and indicate soil health, as they constitute the majority of soil macrofauna affecting various soil functions and ecosystem services. Among the most important drivers of the size and diversity of earthworm populations is land use, especially agriculture. It is widely known that agricultural activities such as tillage, fertilization or the use of agrochemicals directly and indirectly affect earthworms. However, it is rarely investigated to what extent soil properties and climatic factors interact with the influence of agricultural activities. To study this, we analysed datasets of earthworm surveys across 35 European countries covering various agricultural sectors, various soil types and climatic regions including mediterranean, oceanic, and continental climates, across several altitudinal ranges. Investigations were performed within the project MINOTAUR within the European Joint Programme Soil. Data on earthworm abundance and biodiversity in agroecosystems was collated from public sources containing FAIR (findability, accessibility, interoperability, and reusability) data such as GBIF, Edaphobase, datadryad, or zenodo, including many historical and non-English studies to prevent a publication bias. Moreover, long-term ecological research sites were sampled for earthworms as part of the project. The greatest challenge in collating earthworm data was to find meta-data regarding agricultural activities, soil properties and climatic data of the study sites. Moreover, data quality varied considerably, often lacking standard vocabulary, consistent species nomenclature, and details on sampling designs. Thus, preliminary outcomes of our analysis are (i) the need for data harmonization in biodiversity monitoring, (ii) the inclusion of a minimal set of meta-data regarding soil properties, land use intensity, and sampling methodology in order to be able to examine the drivers of earthworm populations in agricultural systems. After a tedious data harmonization process we will analyse our data using structural equation models, to determine which factors had the biggest impacts on earthworm abundance and biodiversity. Using this information, we can better understand earthworm population developments, and promote strategies to foster soil protection and earthworm biodiversity on a European scale.

How to cite: Mittmannsgruber, M., Peres, G., Murugan, R., and Zaller, J.: Earthworm populations and their drivers in agroecosystems across Europe: land use, soil properties, climatic factors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18198, https://doi.org/10.5194/egusphere-egu24-18198, 2024.

EGU24-18278 | ECS | Orals | SSS4.2

Soil health and microbial diversity in fruit chestnut groves affected by ink disease  

William Trenti, Mauro De Feudis, Gloria Falsone, Livia Vittori Antisari, Federico Puliga, Giulia Tabanelli, Alessandra Zambonelli, and Fausto Gardini

Soil is one of the most diverse and complex natural systems at global scale and is involved in several reactions of formation, development, and breakdown of chemicals, many of these depending on soil microorganisms.

According to the combination of soil forming factors, soil properties show a large horizontal and vertical variability, which can have a huge impact on soil microbial communities. However, relatively few investigations have been carried out to associate the changes in soil microbial community with the variations of soil properties across the genetic horizons and along depth.

In Italy, chestnut groves used to be key sources of products in mountain regions. Recent socio-economic changes have led to the progressive abandonment of this land use, producing degradation of the landscape and increased hydrogeologic risk. Now, programs for the restoration of this activity collide with outbreaks of illnesses such as ink disease, which is caused by Oomycetes present in the soil. In this framework, the physicochemical and biological features of soils play a crucial role in the distribution and assessment of the risk and severity of this disease.

The objective of this study was to correlate the diversity and eco-functionality of the microbial communities with soil properties and health indicators along depth and across a transect including chestnut trees with and without symptoms of ink disease.

The study area was a fruit chestnut grove located in the Apennine mountains south of Bologna, Italy. Soil profiles were opened along a transect ranging from a chestnut tree showing ink disease symptoms (INK1) to two subsequent chestnut trees with no visible symptoms (INK2 and INK3). In each profile, the horizons were described and sampled; to assess spatial variability, three minipits were opened around each profile, and their horizons were also described and sampled. Each horizon was also sampled in sterility. The samples were then analyzed for physicochemical and biological parameters, and total DNA was extracted to perform a taxonomic analysis.

Results showed that some physicochemical parameters, while presenting a trend with depth, also presented a trend with distance from the diseased tree: pH and base saturation decreased near this tree, while C:N and C:P increased, as well as water-extractable organic carbon. The taxonomic analysis showed that, while no substantial variation was detected in the bacterial composition of INK2 and INK3, INK1 showed a higher prevalence of phyla involved in the organic matter cycle (Acidobacteriota and Proteobacteria). Regarding the fungal population, in INK2 and INK3 the main trophic group was soil saprotrophs, while in INK1 the most frequent were short- and medium-distance ectomycorrhizae, which often indicate plant stress. Shannon index showed that bacterial diversity increased with depth while fungal diversity decreased. In both cases the profile near the diseased tree presented the least diversity. No difference was detected between the profiles in soil health indicators, such as organic matter content and microbial biomass and its activity, and these were not correlated with microbial diversity. These results suggest that taxonomic analysis of soil microorganisms could integrate traditional indicators in assessing soil and ecosystem health.

 

How to cite: Trenti, W., De Feudis, M., Falsone, G., Vittori Antisari, L., Puliga, F., Tabanelli, G., Zambonelli, A., and Gardini, F.: Soil health and microbial diversity in fruit chestnut groves affected by ink disease , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18278, https://doi.org/10.5194/egusphere-egu24-18278, 2024.

EGU24-18424 | Posters on site | SSS4.2

Finding the optimum tillage and cover crop system for optimizing microbial soil health and nutrient cycling 

Martin Schneider, Sabine Huber, Niklas Bruhn, Markus Gorfer, Sophie Zechmeister-Boltenstern, Gernot Bodner, and Katharina Keiblinger

Soil ecosystem services and soil health criteria, such as nutrient cycling, carbon (C) sequestration and water regulation, needs to be maintained and improved to meet our environmental, social and economic demands for the future within the frameworks of global change, population growth and economic independency.

This study investigated variations of soil physical, nutritional and microbial properties due to differing cover cropping systems within the first year. The experiment was located on an ongoing long-term tillage field trial in Hollabrunn, Austria. For 18 years, soils were cultivated either conventional (plough), reduced (grubber), minimized (disk-harrow) or by direct-seeding. Beside the fallow treatment, two mixtures of cover crops were selected. The 23 kg ha-1 standard mixture contained 65 % buckwheat (Fagopyrum esculentum), 22 % scorpion-weed (Phacelia tanacetifolia) and 13 % mustard (Brassica juncea). The 35 kg ha-1 advanced mixture contained 14 different species with 19 % Fabaceae and 15 % Brassicaceae. Soils were sampled after sowing of the cover crop in september and in the following june after sowing soybean.

Intensive tillage systems increase mineralization, aeration, redox potential and rooting within the upper most ploughing (Ap) horizon, while decreasing water holding capacity and soil aggregation. However, the higher frequency of machinery passes favors soil compaction in the layer below and limits deep rooting. Reduced tillage systems might provide a less disturbed soil structure, supporting the soil microbiology. In contrast, the reduced aeration and minimized mechanical breakdown should increase water availability, which often is the most critical factor for soil life.

The current results indicated, that soil water contents and aggregate stability was enhanced in the two least intensive treatments. The microbial C and nitrogen (N), dissolved C and N, ergosterol, extracellular enzyme activities (EEA) and the organic C pool were significantly higher with minimized and no-till. This indicated a larger amount of substrates, generating a more active and larger microbial community in the latter.

The vegetative soil coverage between the main crops is another driving factor controlling water and nutrient availability by withdrawal, fixation, mobilization and by feeding the soil rhizosphere.

After one period, cover crop-related effects were found, as the standard mixture had higher EEA, indicating a lower nutrient availability. Larger organic, inorganic and total C pools were found in the advanced mixture. Only the microbial phosphorus (P) was higher in the advanced mixture and no effect was found for microbial C and N. Higher availability of N and P in the advanced mixture due to the higher proportion of Fabaceae and Brassicaceae and their strong mobilizing effect was indicated by the higher ratio of C- to N-allocating EEA and a lower ratio of N- to P-allocating EEA. The fallow treatment was in between both cover crops and seemed to provide considerable amounts of nutrients and water to the main crop, in the first spring.

A combination of minimized or no-tillage and a diverse cover crop seemed to by promising for improving soil health, but characterizing the microbial community by 16S rRNA and ITS is still in progress.

How to cite: Schneider, M., Huber, S., Bruhn, N., Gorfer, M., Zechmeister-Boltenstern, S., Bodner, G., and Keiblinger, K.: Finding the optimum tillage and cover crop system for optimizing microbial soil health and nutrient cycling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18424, https://doi.org/10.5194/egusphere-egu24-18424, 2024.

EGU24-19809 | Posters on site | SSS4.2

Implementation of a pioneer program for soil monitoring and assessment of factors influencing soil biodiversity in Austria 

Johann Zaller, Marion Mittmannsgruber, Edith Gruber, Elisabeth Wiedenegger, Dmytro Monoshyn, Yoko Muraoka, Kathrin Pascher, Stefan Schindler, and Rajasekaran Murugan

Systematic monitoring of soil biodiversity and soil health is still in its infancy in Europe. In Austria, there are several active biodiversity monitoring programs such as the BINATS Biodiversity-Nature-Safety or ÖBM-K Austrian Biodiversity Monitoring of the Cultural Landscape projects. However, these projects focus on habitat diversity, vascular plants, grasshoppers, butterflies and wild bees, but have not taken soil organisms into account. This is surprising, as soils are among the most species-rich habitats and intact soils are the basic prerequisite for the integrity of ecosystems. Healthy soils also play an important role in buffering extreme climate events such as heavy rainfall or drought, or sequester carbon. The aim of the BodenBiodiv project is to close this glaring data gap for Austria and to identify the causes of various indicators of soil biodiversity in the agricultural landscape. As part of objective 1, systematic monitoring of earthworms in the agricultural landscape will be established in 200 quadrants (625 x 625 m) throughout Austria, which are part of the BINATS and ÖBM-K monitoring programs. Lists of the earthworm species present, their abundance and biomass as well as a distribution map are being compiled. In addition, a manual for future surveys on national monitoring of soil biodiversity will be compiled using harmonized terminology as a supplement to the existing monitoring manuals in Austria. Objective 2 deals with the analysis of factors that determine the occurrence of earthworms. For this purpose, site characteristics (land use, altitude) and soil properties (pH value, nutrient concentrations, moisture content, carbon content, soil microorganisms) as well as and management practices are associated with the recorded earthworm parameters and the available biotope mapping of the plots. Objective 3 is to compile a first Red List of earthworms in Austria. BodenBiodiv focuses on indicators of the status of species and biotope types; genetic diversity is also to be determined later on the basis of backup samples. The comprehensive data set from different climatic regions in Austria, from lowlands to high alpine areas, BodenBiodiv also enables the assessment of the influence of climatic variables on soil biodiversity. By incorporating data from existing biodiversity monitoring programs, we can expand our understanding of the interactions between below-ground and above-ground biodiversity.

How to cite: Zaller, J., Mittmannsgruber, M., Gruber, E., Wiedenegger, E., Monoshyn, D., Muraoka, Y., Pascher, K., Schindler, S., and Murugan, R.: Implementation of a pioneer program for soil monitoring and assessment of factors influencing soil biodiversity in Austria, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19809, https://doi.org/10.5194/egusphere-egu24-19809, 2024.

EGU24-20583 | Orals | SSS4.2

Multi-year dynamics of soil structural stability under contrasting farming practices in a belgian organic field experiment 

Frédéric Vanwindekens, Brieuc Hardy, Morgan Abras, Simon Sail, and Bruno Huyghebaert

At the heart of agro-ecosystems lie soils, essential components profoundly affected by intensive farming practices and global changes across various regions in Europe. This impact manifests as a loss of biodiversity, a decline in organic matter content, and heightened susceptibility to erosion. Recognizing these challenges, certain farmers are embracing innovative approaches to enhance soil quality, such as conservation farming and organic farming. These two systems differ significantly in their weed management practices, with conservation farming relying on synthetic herbicides and reduced tillage, while organic farming predominantly employs tillage.

To assess soil structural stability, we developed a new measurement protocol, the QuantiSlakeTest. This low-tech method operates on the principle of continuous quantitative measurement, evaluating the disintegration of a soil sample submerged in water. The resulting curves are normalized, and synthetic indicators, including relative weights at stabilization, time to reach maximum relative weight post-immersion, diverse slopes, and area under the curve, facilitate the comparison of various treatments.

Building on previous research demonstrating the relevance of this approach and the influence of tillage on soil structural stability (Vanwindekens & Hardy, 2023), our study employed the QuantiSlakeTest to highlight the annual evolution of soil structure stability over three years following the implementation of an organic cropping system trial in Gembloux (Wallonia, Belgium). Initiated in 2019, the trial involved converting a conventional 6 ha field to a seven-year rotation of organic farming. The three compared cropping systems differed in weed control, fertilization, and tillage practices. Soil samples were collected in early spring of 2020, 2021, and 2022 from various crops in the trial, including winter cereals, spring cereals, legumes, and maize, with cover crops or even uncovered after a winter ploughing.

Our main findings reveal a gradual differentiation of soil structural stability indicators during the first three years of cultivation. Cropping systems based on reduced tillage practices demonstrated a positive impact on soil structural stability, particularly in the third studied year (2022), while reference systems exhibited lower rates. These results confirm previous studies. We also detect a slight positive impact of legumes, cover crops, and/or crop associations, even in the two cropping systems with ploughing (2022). Further analyses, to be conducted over the seven years rotation will shed additional light on the dynamics of soil structural stability.

Frédéric M. Vanwindekens and Brieuc F. Hardy (2023). The QuantiSlakeTest, measuring soil structural stability by dynamic weighing of undisturbed samples immersed in water, SOIL, 9, 573–591, https://doi.org/10.5194/soil-9-573-2023

How to cite: Vanwindekens, F., Hardy, B., Abras, M., Sail, S., and Huyghebaert, B.: Multi-year dynamics of soil structural stability under contrasting farming practices in a belgian organic field experiment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20583, https://doi.org/10.5194/egusphere-egu24-20583, 2024.

EGU24-21191 | Orals | SSS4.2

Novel Soil Decomposition Sensor: Field Studies and Design Improvements 

Madhur Atreya, Taylor Sharpe, Shangshi Liu, Rebecca Killick, Mengyi Gong, Kelly Verhaalen, Anupam Gopalakrishnan, Noah Smock, Isabella Sarralde, Mac Bean, Jessica Davies, John Quinton, Richard Bardgett, Jason Neff, Evan Thomas, and Greg Whiting

 

The sensing of soil microbial and enzymatic activity continues to be a challenge, as current techniques are typically limited to the laboratory, and are time and labor intensive. In addition, such offsite assessments are not necessarily reflective of in situ bio-chemical-physical processes. We previously presented a novel printed decomposition sensor comprising a poly(hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and carbon composite material, wherein the sensor response correlated with the microbial activity in incubated soils [1]. In field trials carried out in the Yorkshire Dales (UK) these devices showed a clear correlation with measured soil microbial biomass carbon. These sensors consisted of a single fuse-like resistive element and as such were subject to stochastic effects in soil, requiring large numbers of devices to be used in order to address variability in field measurements. Here, we present a novel hardware solution to mitigate these stochastic effects by parallelizing multiple printed sensing elements on custom printed circuit boards (PCBs). The first instantiation of this approach showed to be effective at smoothing out sensor response in potato farms in the Upper Midwest region of the United States. In order to further shape the signal response of these decomposition sensors, we explored different parallel topologies by varying the number of sensing elements, element width, and element length. We discuss the advantages and disadvantages of these different topologies.


[1] Atreya, M.; Desousa, S.; Kauzya, J.; Williams, E.; Hayes, A.; Dikshit, K.; Nielson, J.; Palmgren, A.; Khorchidian, S.; Liu, S.; Gopalakrishnan, A.; Bihar, E.; Bruns, C. J.; Bardgett, R.; Quinton, J. N.; Davies, J.; Neff, J. C.; Whiting, G. L. A Transient Printed Soil Decomposition Sensor Based on a Biopolymer Composite Conductor. Adv. Sci. 2022, 2205785, 1–10. https://doi.org/10.1002/advs.202205785.

How to cite: Atreya, M., Sharpe, T., Liu, S., Killick, R., Gong, M., Verhaalen, K., Gopalakrishnan, A., Smock, N., Sarralde, I., Bean, M., Davies, J., Quinton, J., Bardgett, R., Neff, J., Thomas, E., and Whiting, G.: Novel Soil Decomposition Sensor: Field Studies and Design Improvements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21191, https://doi.org/10.5194/egusphere-egu24-21191, 2024.

Soil health is pivotal for maintaining environmental sustainability and plays a vital role in supporting diverse ecosystems, agricultural productivity, and overall human well-being. The interplay of climate change and anthropogenic (human-induced) activities can exert substantial influence on soil health, giving rise to a spectrum of challenges. In recent years, a growing body of scientific evidence indicates that climate change will adversely affect soil health. This impact manifests through the decline in soil organic matter, the degradation of soil structure, and an increased vulnerability to erosion and other forms of deterioration. Human activities, particularly pollution and widespread habitat degradation, further exacerbate these effects. Additionally, ongoing misuse of soil contributes to its continued degradation, resulting in adverse consequences such as diminished biodiversity, decreased agronomic productivity, reduced input efficiency, and heightened rural poverty.

Consequently, a paradigm shift is imperative, with a focus on adopting sustainable agricultural systems. This involves a need to restore soil health instead of contributing to its decline, actively mitigating and adapting to climate change rather than exacerbating it, promoting negative emission farming instead of being a source of greenhouse gases and transforming land into a significant carbon sink rather than a source. To deal effectively with the challenge of soil health in the context of climate and human-induced change, it is essential to adopt a global approach. This means integrating sustainable land management practices, formulating effective policies and encouraging global cooperation. These measures are essential to ensure the long-term health and productivity of our soils.

How to cite: Chabbi, A.: Unlocking the crucial interplay between soil health, climate change and global stewardship, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21813, https://doi.org/10.5194/egusphere-egu24-21813, 2024.

EGU24-22474 | Orals | SSS4.2

Using Treated Wastewater Sludge to Improve Soil and Growth characteristics of Rain-fed Wheat under Semi-Arid Conditions 

Lena Abou Jaoude, Rabi H. Mohtar, Farah Kamaleddine, Razan Dbaibo, Rania Bou Said, Imad Keniar, and Sandra F. Yanni

Sludge is an increasingly growing concern in Lebanon given the absence of proper treatment and disposal methods. As a solution, this two-years study proposes the valorization of sludge as an organic amendment on soil cultivated with rainfed wheat (Triticum icaversea) and itsimpact on soil properties, microbial activity, wheat yield and grain quality. Baseline characterization of sewage sludge collected from secondary treatment plant (SS) and tertiary treatment plant (TS) in Bekaa, Lebanon, showed that both sludge types can be classified as suitable for restricted agricultural use (Class B), which cannot be used on soils to grow fruits or vegetables that are eaten raw as per the Lebanese guidelines for sludge use. Post-harvest analysis of the amended soils revealed a significant enhancement in organic matter (OM), organic carbon (OC), soil moisture, wheat yield and grain quality in both seasons SS and TS amended soils compared to the control. All the tested heavy metals were much lower than the allowable limits for agricultural soils, except for zinc (Zn).  Wheat biomass and grain quality assessment revealed a significant increase of 30% in grain yield in both treated soils (SS: 74 g/m2, TS: 81 g/m2) compared to the control (46 g/m2). Notably, TS treatment exhibited the highest protein content (14.5%) and ash (1.9%) in the first season, while both SS and TS treatments showed a significant increase in grain moisture in the second season. Soil microbial analysis were not consistent in the two seasons, but showed a potential risk of total coliforms contamination with SS application in the second season. This research provides valuable insights into the positive effects of sewage sludge application on soil fertility, microbial communities, and wheat grain quality. The findings emphasize the potential benefits of sewage sludge in sustainable agriculture, underscored by numerical improvements in various parameters. Although promising soil quality improvement and yield increase were observed in this study, further research is still needed to assess the potential soil microbial contamination and heavy metal accumulation over the long term.

How to cite: Abou Jaoude, L., H. Mohtar, R., Kamaleddine, F., Dbaibo, R., Bou Said, R., Keniar, I., and F. Yanni, S.: Using Treated Wastewater Sludge to Improve Soil and Growth characteristics of Rain-fed Wheat under Semi-Arid Conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22474, https://doi.org/10.5194/egusphere-egu24-22474, 2024.

EGU24-591 | ECS | Orals | SSS4.3

The application of hydrochar promotes soil microbial growth and enhances sunflower yield, altering the nutritional composition of the seeds 

Francisco Jesús Moreno Racero, Rocío Reinoso, Laura Gismero Rodríguez, Enrique Martínez Force, Miguel Ángel Rosales Villegas, and Heike Knicker

In recent decades, the potential use of chars, such as biochar or hydrochar, as soil amendments to enhance plant growth, has garnered significant interest. However, understanding potential toxic impact of these materials on soil and plants remains an area requiring further exploration. In this study, the effect of applying hydrochar (HC) derived from chicken manure on the yield and nutritional quality of sunflower (Helianthus annuus L.) seeds was assessed under both well-irrigated and water deficit (WD) conditions. To address it, the HC was applied to a Cambisol at rates of 3.25 and 6.5 t ha-1. Mineral fertilizer treatments with equivalent total nitrogen contributions as the amendment were included for comparison. Sunflower plants were cultivated in pots under two irrigations conditions (60 and 30% of the soil water holding capacity). After 77 days of cultivation, the plants were harvested, and the content of macro- and micronutrients, heavy metals in both seeds and leaves, as well as the seed fatty acid composition, were analyzed. Additionally, soil nutrient contents were assessed post-experiment

Initially, HC application did not cause a noticeable change in soil nutrient composition. However, both HC applications demonstrated high productivity under well-irrigated conditions. Likewise, under WD conditions, the best yields were achieved with a HC dose of 6.5 t ha-1. Conversely, the composition of the different fatty acids in the seed oil remained unaffected by the treatments and irrigation conditions. Nonetheless, seed nutrient content was notably affected, particularly in plants treated with 6.5 t ha-1. Under well-irrigated conditions, the seeds of these plants exhibited decreased K and P levels, along with higher levels of toxic elements and heavy metals such as Al, Ba, Cd, Pb, and Sr. Under WD conditions, the impact of the treatment on heavy metals contents was less pronounced, but there was a marked reduction of seed macronutrient content (Ca, K, Mg, P and S). Notably, plants treated with 6.5 t ha-1 of HC under well-irrigated conditions exhibited a preferential accumulation of Al and Sr in the seeds, leading to the lowest concentrations of these toxic elements in their leaves. The accumulation of these metals in the seeds was accompanied by a decline of both elements in the soil after 77 days of experiment under this irrigation condition, suggesting plant uptake. Given that the concentration of both elements did not increase after the application of HC at the beginning of the experiment, it is presumed that these changes are due to a potential role of HC involved in heavy metals mobilization. Following qPCR analysis this may be related to microbial activity since the soils treated with 6.5 t ha-1 of HC exhibited a higher abundance of 16S rRNA and ITS gene copies related to bacteria and fungi, respectively, along with an increased dehydrogenase activity. Our findings highlight that the impact of char amendment on soil systems should not be seen as a simple linear process but has to be evaluated considering the complex interactions between climatic conditions, application rate, plant physiology and microbial activity.

How to cite: Moreno Racero, F. J., Reinoso, R., Gismero Rodríguez, L., Martínez Force, E., Rosales Villegas, M. Á., and Knicker, H.: The application of hydrochar promotes soil microbial growth and enhances sunflower yield, altering the nutritional composition of the seeds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-591, https://doi.org/10.5194/egusphere-egu24-591, 2024.

EGU24-976 | ECS | Orals | SSS4.3

Rooted in the city: Unveiling the hidden world of Quercus cerris enzymatic activity in urban soils  

Anna Gillini, Nataliya Bilyera, Dalila Trupiano, Iryna Loginova, Michaela Dippold, and Gabriella Stefania Scippa

 

The intricate interaction between human activities and the repercussions of climate change has made urban ecosystem health and biodiversity—both vital to human survival and well-being—particularly vulnerable. Recent research has spotlighted the frequently underestimated but crucial role that interactions between plant roots and several biotic and abiotic components of soil play in affecting urban biodiversity and ecosystem dynamics.

We conducted a controlled experiment to investigate this relatively obscure aspect of the urban environment. The experiment has been done with young plantlets of Quercus cerris and three urban soils collected from distinct sites in the city of Campobasso (Italy). We selected three sites in the city to clearly show a specific gradient of urbanization and vegetation fragmentation. Q. cerris young plants were grown in the rhizoboxes packed with three urban soils for two weeks to evaluate the impact of soil-plant interactions on the possible enzymes’ release by the roots and root-harboring microorganisms. The spatial distribution of three enzymes, namely acid phosphatase (P-cycle), β-glucosidase (C-cycle), and leucine aminopeptidase (N-cycle), was mapped and detected in each soil region (i.e., bulk soil and rhizosphere longitudinal surface) using a 2-D soil zymography technique.

The zymogram analysis revealed that the enzyme activities in soils differed spatially along the urbanization gradient, with the more urbanized soil having the highest levels of enzymatic activity and hotspot presence.

The root activity toward the exudation correlated with the highest enzymatic activity, that futrther lead to more intensive turnover of soil organic matter in soil. This could be linked to the exudation of roots to regulate plant growth in unfavorable conditions or to the rhizodeposition of substrates to change soil composition. 

Further in-depth analyses of the physical and chemical properties of the soil, along with the profiling and characterization of the microbial community composition, are currently underway in order to obtain a better understanding of the role of root enzymatic activities and their consequences on the biogeochemical processes in urban soils.

How to cite: Gillini, A., Bilyera, N., Trupiano, D., Loginova, I., Dippold, M., and Scippa, G. S.: Rooted in the city: Unveiling the hidden world of Quercus cerris enzymatic activity in urban soils , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-976, https://doi.org/10.5194/egusphere-egu24-976, 2024.

Glucose is one of the major primary metabolites in the plant root exudates to mediate the cross-talk between plants and microbes, but their contribution to drought resistance of plants is largely unknown. To test this, we inoculated arbuscular mycorrhizal fungi (AMF) in soybean, quantified rhizospheric microbial hotspots, visualized glucose exudation pattern, and analyzed microbial activities, such as kinetic properties of β-glucosidase and acid phosphomonoesterase enzymes, and microbial biomass phosphorus.

Drought reduced glucose exudation, mainly allocated to root tips under optimum conditions, and narrowed the rhizosphere enzymatic hotspot by three times. However, AMF inoculation enhanced glucose exudation compared to non-mycorrhizal plants, and enlarged enzymatic hotspot area by 53% under drought condition. Despite the 50% reduction in β-glucosidase and acid phosphomonoesterase activities owing to water deficit, AMF symbiont triggered up to 36% enzyme activities in correlation with the non-mycorrhizal ones. Therefore, the drought resistance of these two enzymes was enhanced by up to 63% in mycorrhizal plants. The biomass of microbial phosphorus increased by 45% under drought conditions in plants inoculated with AMF.

Overall, the greater resistance of enzyme activities to drought in AMF-inoculated than in non-mycorrhizal suggest that microorganisms associated with mycorrhizal root have higher capability to react to altered abiotic environmental conditions than those associated with non-mycorrhizal roots. The mycorrhization induced an interactive regulation of soybean glucose exudation and rhizosphere expansion for enzyme activities. This contributed to the resistance of microbial functions (e.g., enzyme expression) to drought stress in AMF-inoculated than in non-mycorrhizal soybean. AMF-inoculation suppressed adverse drought effects on plant and microbial nutrient mining, which has substantial implications for controlling microbial roles in organic matter decomposition and P cycling.

Keywords: glucose imaging, arbuscular mycorrhiza fungi, soybean, hotspot, drought resistance

How to cite: Hoang Thi Thu, D.: Overlapping locality between rhizosphere and mycorrhizosphere regulates glucose exudation pattern in rhizosphere and enzyme distribution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1017, https://doi.org/10.5194/egusphere-egu24-1017, 2024.

EGU24-1765 | ECS | Orals | SSS4.3

Forest microbiomes and aboveground forest functioning  

Mark Alan Anthony and the ICP Forests Microbiome Collaboration

Forest soils and roots harbor hyper-diverse microbiomes which strongly shape the growth and development of plant communities. How the biodiversity and functional capacities of the microbiome influence emergent ecosystem functioning is an important next frontier in the biogeosciences with implications for conservation, ecosystem management, and microbiome engineering. Directly testing hypotheses between microbiome diversity and forest functioning has been obstructed by a lack of paired data on microbiomes and in situ observations of forest growth and health. Here, I will synthesize findings from two large-scale European forest soil and root sampling efforts where we identified features of the mycorrhizal fungal, soil fungal, and bacterial communities linked to variation in forest tree growth and nutrition. We sampled roots and/or soils across 285 forest monitoring plots spanning 18 European countries, sequenced full-length fungal ITS and prokaryotic 16S amplicons to relate microbiomes to high resolution observations of tree growth, foliar nitrogen and phosphorus content, and aboveground carbon stocks. We show that the composition, richness, and traits of both root and soil inhabiting symbiotrophic fungal guilds is tightly linked to variation in tree growth, nutrition, and aboveground biomass carbon stocks while the biodiversity of free-living microbiomes was not tightly coupled to these key metrics of aboveground forest functioning. We also produced a roster of fungal biodiversity and compositional traits which are strong positive and negative bioindicators of forest carbon storage and nutrition. These large-scale observations lay important groundwork for experimental studies and demonstrate that soil microbiomes capture unique variation in emergent forest functions that cannot be explained by other physical, chemical, and biological properties.

How to cite: Anthony, M. A. and the ICP Forests Microbiome Collaboration: Forest microbiomes and aboveground forest functioning , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1765, https://doi.org/10.5194/egusphere-egu24-1765, 2024.

EGU24-1800 | ECS | Posters on site | SSS4.3

Spatio-temporal distribution of enzyme activities with covered and mixed straw incorporation 

Shang Wang, Huadong Zang, Yadong Yang, Zhaohai Zeng, and Bahar Razavi

The rhizosphere and detritusphere are hotspots of soil enzyme-mediated microbial processes, but little is known about their spatiotemporal distribution and interaction, especially under various straw application strategies. Here, we used an in situ method (i.e. zymography) to investigate the distribution of enzyme activities in the maize rhizosphere and straw detritusphere after straw application (no straw, straw mulching and straw mixed). The surroding of straw was considered as detritusphere. Furthermore, the root and shoot performance of maize and soil chemical properity were also monitored in the study. The plant height, shoot weight, and root surface density of straw mulching were 60.4%, 159.6%, and 19.2% higher than that of straw mixed (p < 0.05), which indicate straw mixed returning lead to a stronger competition between plant root and soil microorganism for nutrients. SOC, TN, DOC and DON in the topsoil of straw mulching returning were 97.2%, 27.0%, 186.7% and 175.0% higher than that of straw mixed, respectively (p < 0.05). Moreover, both straw mulching and mixed returning has a positive effect on soil surface enzyme activities. Higher enzyme activities in detritusphere was observed with straw mulching than straw mixed returning (p < 0.05). The higher enzyme activities in the rhizosphere of straw mulching on day 15 can be defined by the increase of C release caused by root growth. This inturn can promote the process of microbial and nutrient cycling, and enhance rhizosphere enzyme activity. These results revealed that straw mulching decreases nutrients competition between root and microorganism and increases the C- and N-acquiring enzyme activities in detritusphere.

How to cite: Wang, S., Zang, H., Yang, Y., Zeng, Z., and Razavi, B.: Spatio-temporal distribution of enzyme activities with covered and mixed straw incorporation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1800, https://doi.org/10.5194/egusphere-egu24-1800, 2024.

The response of soil carbon release to global warming is largely determined by the temperature sensitivity of soil respiration, yet how this relationship will be affected by increasing atmospheric nitrogen deposition is unclear. Here, we present a global synthesis of 686 observations from 168 field studies to investigate the relationship between nitrogen enrichment and the temperature sensitivity of soil respiration. We find that the temperature sensitivity of total and heterotrophic soil respiration increased with latitude. In addition, for total and autotrophic respiration, the temperature sensitivity responded more strongly to nitrogen enrichment with increasing latitude. Temperature and precipitation during the Last Glacial Maximum were better predictors of how the temperature sensitivity of soil respiration responds to nitrogen enrichment than contemporary climate variables. The tentative legacy effects of paleoclimate variables regulate the response through shaping soil organic carbon and nitrogen content. We suggest that careful consideration of past climate conditions is necessary when projecting soil carbon dynamics under future global change.

How to cite: Tian, P.: Past climate conditions predict the influence ofnitrogen enrichment on the temperature sensitivityof soil respiration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1953, https://doi.org/10.5194/egusphere-egu24-1953, 2024.

EGU24-2546 | ECS | Orals | SSS4.3

Soil zymography: a decade in microbial hotspot imaging and future challenges 

Nataliya Bilyera and Yakov Kuzyakov

Soil zymography represents a non-invasive methodology facilitating the in situ visualization and localization of potential enzyme activities in soil. Due to universality and simplicity of zymography method, it has been widely used to visualize the hidden microbial and root life in soil, which is a very heterogeneous and “dark” environment.

Following the pioneering use of fluorogenic substrates for enzyme activity visualization in soil, a significant methodological advancement occurred within the subsequent decade. Our primary focus is to highlight the progress in the last 10 years, with respect to the spectrum of enzyme activity imaging, zymography resolution, standardization and hotspot identification. Specifically, we emphasize the integration of zymography with the visualization of soil acidification, root exudation, pore distribution, nutrient and water movements. Although the majority of applications so far have centered on enzyme activities in the rhizosphere to reveal plant-soil-microbial interactions, we present the case studies to identify soil heterogeneity and microbial activity also in biopores, detritusphere and other hotspots.

We present not only the advancements made but also the current possibilities, challenges, and the potential directions of soil zymography. This technique finds applications across natural and agricultural ecosystems, both in field settings and laboratory studies, capable of scaling from the entire root system (dm) down to microbial communities (μm).

In the decade ahead, the future of enzyme research, particularly zymography imaging, will continue to broaden the scope of microbial studies and hotspot localization. This expansion will involve integrating with disciplines such as (bio)chemical, physico-chemical, microbial cell imaging, and isotope applications, facilitating a deeper understanding of soil processes and microbial interactions.

How to cite: Bilyera, N. and Kuzyakov, Y.: Soil zymography: a decade in microbial hotspot imaging and future challenges, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2546, https://doi.org/10.5194/egusphere-egu24-2546, 2024.

EGU24-3022 | ECS | Posters on site | SSS4.3

Top-down effects of crust-eating macro-arthropods on biocrust microtopography and carbon cycling 

Nevo Sagi, Amir Sagy, Vincent Felde, and Dror Hawlena

Biological soil crusts (biocrusts) are key regulators of soil C and N cycling, soil erosion, and water (re)distribution in drylands. Nevertheless, huge knowledge gaps exist about one core aspect of biocrust ecology, namely how these processes are affected by biocrust-eating macro-arthropods. We addressed this knowledge gap by exposing biocrusts to varying levels of isopod crustivory (i.e. grazing intensity), and quantifying the consequences for CO2 efflux, C fixation and microtopography. Biocrust CO2 efflux decreased with increasing crustivory and recovered after several wetting events. Crustivory had a negative effect on biocrust C fixation, but only after the CO2 efflux recovered to pre-crustivory levels. Biocrust surface roughness increased with increasing crustivory to a peak and then began to decrease, implying that varying levels of crustivory may have opposing consequences for water infiltration and runoff generation. Our findings suggest that macro-crustivores may play a key role in regulating biocrust ecological functioning, introducing a whole new line of crustivory research that will be instrumental in conceptualizing various ecosystem dynamics in drylands.

How to cite: Sagi, N., Sagy, A., Felde, V., and Hawlena, D.: Top-down effects of crust-eating macro-arthropods on biocrust microtopography and carbon cycling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3022, https://doi.org/10.5194/egusphere-egu24-3022, 2024.

Tropical rainforests on low-phosphorus (P) soils are highly biodiverse and productive, playing a crucial role in climate change mitigation. However, the adaptation mechanisms of tropical rainforest dominated by trees associated with different mycorrhizal symbioses (arbuscular mycorrhizal (AM) and ectomycorrhizal fungi (ECM)) to P-deficient environments remain unclear. Through a 10-year field experiments with nitrogen (N) and P additions in AM- and ECM-dominated stands, we first investigated leaf nutrient content and resorption efficiencies of eight species in each stand. We further explored how litter, soil, and microbes maintain P supply to plants. We found that both AM- and ECM-dominated forests are P-limited. AM-dominated forest exhibited higher soil phoD gene abundance and fungal diversity, while ECM-dominated forest displayed higher soil phosphatase activity. Regression and random forest analyses revealed that AM-dominated forest employ diverse P-acquisition strategies, including increased foliar P resorption efficiency, soil phosphatase activity, and fungal diversity. In contrast, ECM-dominated forest preferred to enhance soil phosphatases activity and mineralize moderately liable P, thereby alleviating P limitation. These findings show joint influence of litter, soil, and microorganisms on plant P acquisition, and P-regulated processes vary by mycorrhizal types. Our study enhances understanding of the effects of global change on biogeochemical processes in tropical rainforests.

How to cite: Yu, Q.: Differential adaptative strategies to phosphorus limitation in tropical rainforests dominated by trees associated with arbuscular and ectomycorrhizal fungi, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3313, https://doi.org/10.5194/egusphere-egu24-3313, 2024.

EGU24-6598 | ECS | Orals | SSS4.3

Why, where, and when are there anoxic microsites in the rhizosphere – a microfluidic approach 

Emily Lacroix, Giulia Ceriotti, Daniel Garrido-Sanz, Sergey Borisov, Jasmine Berg, Christoph Keel, Pietro de Anna, and Marco Keiluweit

For decades, biogeochemists have speculated that roots are key drivers of anoxic microsites – anomalous volumes of oxygen depletion – in upland soils. Rhizosphere-associated anoxic microsites are hypothesized to regulate plant contaminant uptake, nutrient availability, and the fate of root-derived carbon. However, despite the potential importance of rhizosphere-associated anoxic microsites, it remains unclear why, when, and where anoxic microsites form in the rhizosphere. Here, we pair planar optical oxygen sensors with microfluidic devices mimicking a soil structure to map the distribution of oxygen in a young wheat rhizosphere. We filled microfluidic devices with i) sterile; ii) wheat symbiont-inoculated, and iii) whole-soil community-inoculated nutrient solutions. As a result, we were able to determine root oxygen consumption vs. microbial oxygen consumption over space (i.e., at different root physiological features) and time (i.e., day/night cycles). We will show that i) intense root respiration within the root tip may drive anoxic microsite formation, even in the absence of microbial respiration; ii) microbial colonization of lateral root emergence may drive localized oxygen depletion in older root sections, and iii) overall rhizosphere oxygen depletion has a predictable, diurnal cycle dictated by the plant’s photosynthetically active period. Our findings are the first to link root physiology to anoxic microsites, providing a strong basis for future studies of anoxic microsites in field soils. 

How to cite: Lacroix, E., Ceriotti, G., Garrido-Sanz, D., Borisov, S., Berg, J., Keel, C., de Anna, P., and Keiluweit, M.: Why, where, and when are there anoxic microsites in the rhizosphere – a microfluidic approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6598, https://doi.org/10.5194/egusphere-egu24-6598, 2024.

EGU24-7619 | ECS | Posters on site | SSS4.3

Coexistence patterns of biocrust-vascular plant in the Loess Plateau 

Yali Ma, Li Ma, Liping Yang, Siqing Wang, Hongyu Jiang, Yuhan Qi, Qianhai Ye, and Ning Chen

Biological soil crust (biocrust) widely distributes in the Loess Plateau, which is the most typical loess platform worldwide, and a cultural origin of China. Since 1999, the Loess Plateau experienced heavily restorations, costed hundreds of billions Chinese Yuan. Even so, we have no clear idea of how do major biological components – biocrust, grass, and shrub coexist together therein, which can greatly affect restoration practices. To that end, this study combined field survey, reference compiling and remote sensing data to identify coexistence patterns of biocrusts and vascular plants (grass and shrub) on the Loess Plateau. A total of 262 data points had been collected. We found that precipitation, surface temperature and solar radiation were the major drivers in the Loess Plateau, and there were three coexistence patterns, namely high biocrust-vascular mixed state under high annual rainfall and surface temperature of 10-12°C, biocrust-dominated state under low rainfall condition and low biocrust-vascular mixed state under low surface temperature situation. Furthermore, we found that high biocrust-vascular mixed and biocrust-dominated states appeared to be alternative states along annual rainfall gradient. This study discovered coexistence patterns of biocrust-vascular plant in the Loess Plateau for the first time, and can guide future restoration and conservation in the region. This is crucial for achieving sustainable development and ecological safety of north China.

How to cite: Ma, Y., Ma, L., Yang, L., Wang, S., Jiang, H., Qi, Y., Ye, Q., and Chen, N.: Coexistence patterns of biocrust-vascular plant in the Loess Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7619, https://doi.org/10.5194/egusphere-egu24-7619, 2024.

EGU24-9749 | ECS | Posters on site | SSS4.3

Spatial organization of a soil cyanobacterium and its cyanosphere through GABA/Glu signaling to optimize mutualistic nitrogen fixation 

Corey Nelson, Pavani Dadi, Dhara D. Shah, and Ferran Garcia-Pichel

Soil biocrusts are characterized by the spatial self-organization of resident microbial populations at small scales. The cyanobacterium Microcoleus vaginatus, a prominent primary producer and pioneer biocrust former, relies on a mutualistic carbon (C) for nitrogen (N) exchange with its heterotrophic cyanosphere microbiome, a mutualism that may be optimized through the ability of the cyanobacterium to aggregate into bundles of trichomes. Testing both environmental populations and representative isolates, we show that the proximity of mutualistic diazotroph populations results in M. vaginatus bundle formation orchestrated through chemophobic and chemokinetic responses to Gamma-aminobutyric acid (GABA) / Glutamate (Glu) signals. The signaling system is characterized by: 1) high GABA sensitivity (nM range) and low Glu sensitivity (µM - mM); 2) GABA and Glu are produced by the cyanobacterium as an autoinduction response to N deficiency; and 3) interspecific signaling by heterotrophs in response to C limitation. Further, it crucially switches from a positive to a negative feed-back loop with increasing GABA concentration, thus setting maximal bundle sizes. The unprecedented use of GABA/Glu as an intra- and interspecific signal in the spatial organization of microbiomes highlights the pair as truly universal infochemicals.

How to cite: Nelson, C., Dadi, P., Shah, D. D., and Garcia-Pichel, F.: Spatial organization of a soil cyanobacterium and its cyanosphere through GABA/Glu signaling to optimize mutualistic nitrogen fixation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9749, https://doi.org/10.5194/egusphere-egu24-9749, 2024.

EGU24-10710 | ECS | Posters virtual | SSS4.3

Biological soil crusts as hotspots of managed soils in mesic environments 

Corinna Gall, Julia Katharina Kurth, Karin Glaser, Ulf Karsten, Juliette Ohan, Michael Schloter, Thomas Scholten, Stefanie Schulz, and Steffen Seitz

Biological soil crusts, or “biocrusts”, are biogeochemical hotspots that significantly influence ecosystem processes in arid environments. Biocrusts play an important ecological role in the pedosphere and can improve nutrient availability and fertility, influence plant germination, increase biogeochemical cycling, keep and enhance water availability at the soil surface, increase soil aggregate stability, and protect the soil surface by counteracting soil erosion from water and wind. Although they cover large areas, particularly in managed sites with frequent anthropogenic disturbance, their importance in mesic environments is not in the focus of research so far. As in arid regions, biocrusts can significantly affect soil nutrients, soil degradation as well as the water balance here; however, their persistence may differ. The essential requirements for biocrust development include bare soil and a minimum amount of light. These conditions act as a starting point for biocrust establishment and succession in mesic environments and can either occur in special habitats such as sand dunes or mining heaps or be created by disturbing or removing layers of vegetation and litter. Recent studies have found mesic biocrusts mostly at managed, anthropogenically impacted sites such as monospecific forest plantations, broadleaf-mixed forests under heavy machining, and agricultural fields.

Based on their ecological functions, biocrusts bear the potential to act as novel tools for sustainable soil management. They have already been explored as possible means to restore degraded soils such as in the rehabilitation of salt heaps and burned forests. As a consequence of global climate change with a larger frequency of extreme weather events such as heavy rainfalls or extended droughts, soils will become more vulnerable and require new forms of management. Accordingly, biocrusts could make a significant contribution considering their partly high abundance in managed mesic environments. As the study of biocrusts in mesic environments is still in its infancy, further elaboration on their dynamics, distribution, and potential impacts on ecosystem services is needed. Therefore, we call for interdisciplinary physical, biological, microbiological, chemical, and applied soil science research with a special focus on biocrusts of managed soils from mesic environments, to better understand their impact on overall ecosystem health and resilience, particularly due to climate change.

How to cite: Gall, C., Kurth, J. K., Glaser, K., Karsten, U., Ohan, J., Schloter, M., Scholten, T., Schulz, S., and Seitz, S.: Biological soil crusts as hotspots of managed soils in mesic environments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10710, https://doi.org/10.5194/egusphere-egu24-10710, 2024.

EGU24-11067 | ECS | Posters on site | SSS4.3

Evaluation the efficiency of different application method of Fe aminochelates compared to FeSO4 on yield and quality traits of oleic Sunflower (Helianthus annuus L.) in a calcareous soil 

Mina Alipour Babadi, Mojtaba Norouzi Masir, Abdol Amir Moezzi, Mehdi Taghavi, Afrasyab Rahnama, and Bahar S. Razavi

In modern and sustainable approaches, it is necessary to address the nutrient deficiencies that limit agriculture productions.­ Routine inorganic fertilizers such as FeCl2 and FeSO4, are not effective in correcting iron (Fe) deficiency due to their chemical nature and rapid conversion of soluble Fe forms into unavailable Fe (III)-oxide or hydroxide forms, particularly under lime conditions. Recently, organic complexing agents such as amino acids have been considered important due to increasing nutrient bioavailability in the soils as well as improving plant stress tolerance for more yield. It is hypothesized that the use of ecofriendly Fe (II)-amino acid chelates can increase Fe uptake by plant as such products have the potential to form relatively stable complexes with minerals as "aminochelates". Aminochelate fertilizers are the latest novelties regarding plant nutrition in agricultural production systems. Amino chelates provide higher bioavailability and absorption of micronutrients due to effective ingredients with no environmental side effects. Here, we investigate the effects of Fe aminochelates as Fe sources on the yield of sunflower (Helianthus annuus L.) plants in field condition. We made use of synthesized Fe (glycine)2 [Fe (Gly)2] and Fe (methionine)2 [Fe (Met)2] amino chelates for seed priming, fertigation and foliar application on plant leaves. This experiment showed that all methods of Fe aminochelates application, especially foliar feeding, can increase shoot iron content and improve nutritional quality of sunflower in Fe-deficient soils. We observed the higher effectiveness of Fe aminochelates compared to FeSO4 on increasing plant growth parameters, grain and oil yield, biomass production and activity of antioxidant enzymes. Overall, our results suggested that application of Fe aminochelates can be considered as an effective approach to overcome the plant Fe deficiency and improve the yield of plant in calcareous soil. Future experiments will investigate the effects of aminochelates on soil biological parameters and soil enzymes activity in rhizospheres using imaging techniques.

Key words: Aminochelates; antioxidant enzymes; grain yield; iron deficiency; nutrient uptake

 

How to cite: Alipour Babadi, M., Norouzi Masir, M., Moezzi, A. A., Taghavi, M., Rahnama, A., and Razavi, B. S.: Evaluation the efficiency of different application method of Fe aminochelates compared to FeSO4 on yield and quality traits of oleic Sunflower (Helianthus annuus L.) in a calcareous soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11067, https://doi.org/10.5194/egusphere-egu24-11067, 2024.

EGU24-11099 | Posters on site | SSS4.3

Soil fertilization alters spatial and temporal distribution of amino-N in the rhizosphere of maize 

Evgenia Blagodatskaya, Guoting Shen, and Andrey Guber

Despite an importance and relatively high abundance of organic N in soil, it is uncertain how the distribution of organic N is affected by mineral N availability in the course of root development. We visualized amino-N content in seminal and lateral roots of maize (Zea mays L.) grown under reduced and full fertilization at the 4- and 6-leaves phases.  The intensity of amino-N hotspots was fertilization-, growth phase- and root-specific. Under reduced fertilization, amino-N content decreased in all root parts at the 6- versus the 4-leaves phase. Under full fertilization, the content of amino-N increased in seminal roots and lateral root tips but it decreased in seminal root tips with root growth. This suggests a potential functional differentiation of seminal and lateral root tips in the N-acquisition strategy in the course of plant growth. 

How to cite: Blagodatskaya, E., Shen, G., and Guber, A.: Soil fertilization alters spatial and temporal distribution of amino-N in the rhizosphere of maize, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11099, https://doi.org/10.5194/egusphere-egu24-11099, 2024.

EGU24-11732 | ECS | Posters on site | SSS4.3

High soil metal contents override climate impacts on biogeochemical dynamics in bulk and rhizosphere soils of a metal-hyperaccumulating plant 

Carolina Vergara Cid, Natalia Sanchez, Sören Drabesch, Ines Merbach, Evgenia Blagodatskaya, and E. Marie Muehe

Plant roots can modify soil organic matter decomposition, regulating carbon (C) and nitrogen (N) fluxes and storage. Several biotic (e.g., plant species, soil microbiome) and abiotic factors (e.g., nutrient availability, temperature, environmental stressors) can influence the extent of changes in nutrient cycling driven by roots. For instance, metal contamination and climate change can trigger changes in plant and microbial growth and activity, impacting soil biogeochemical processes. Given that future climatic conditions may boost metal mobility in soils and root exudation, the coupling of both disturbances may likely impact nutrient cycling more severely than either single factor. However, little is known about the impacts of coupled climate change and soil contamination on nutrient cycling facilitated by the rhizosphere of a metal hyperaccumulating plant, which is especially relevant in phytoremediation.

To investigate whether and to which extent climate induces modifications of nutrient and metal availability affecting microbiome dynamics and functioning in bulk and rhizosphere soils, we set up a greenhouse pot study with the model metal hyperaccumulating plant Arabidopsis halleri. Three agricultural soils with natural contents of the common non-metabolically useful heavy metal Cd (low 0.2 ppm Cd, medium 1 ppm Cd, and high 14 ppm Cd) were exposed to today’s and future climatic conditions (according to IPCC RCP 8.5: +4º C and +400 ppmv CO2). 

Future climatic conditions enhanced plant growth in all soils producing between 1.6 to 2.8 times more shoot, with plants growing overall less on the high-Cd soil. Future climatic conditions increased shoot Cd accumulation only in soil with medium-Cd content but not low and high-Cd. Increased organic matter decomposition indicated by higher hydrolytic enzyme activity and N mineralization was found in the low-Cd soil under future conditions. Nevertheless, root activity was the main driver in producing changes in soil nutrient fluxes and metal availability in metal contaminated soils. Overall, increasing metal concentration negatively affected soil carbon microbial biomass and the microbial metabolic quotient; however, the decline was significantly more pronounced in the rhizosphere of medium-Cd and high-Cd soils. In addition, hydrolytic enzyme activities involved in C and N cycling were higher in medium-Cd and high-Cd soils, as well as the plant metal content and metal availability in the rhizospheres. These findings indicate a higher maintenance cost for microorganisms in the rhizosphere of contaminated soils, which may respond to higher nutrient demand from plants and a higher portion of assimilated C allocated to alleviate heavy metal toxicity. As soil metal contamination increased, less microbial N biomass and higher N mineralization were found in the rhizosphere, suggesting an adjustment in microbial activity to plant needs and lower capacity for N immobilization in soils.

We conclude that although climate change can significantly affect overall plant responses and boost organic matter decomposition in soils with low metal content, climate impacts on soil microbial community dynamics and biogeochemical processes are overridden in soils with high metal contents, which trigger higher C and N demand by plant and stressed microorganisms and may imply a decrease in C and N soil storage.

How to cite: Vergara Cid, C., Sanchez, N., Drabesch, S., Merbach, I., Blagodatskaya, E., and Muehe, E. M.: High soil metal contents override climate impacts on biogeochemical dynamics in bulk and rhizosphere soils of a metal-hyperaccumulating plant, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11732, https://doi.org/10.5194/egusphere-egu24-11732, 2024.

EGU24-11977 | Posters on site | SSS4.3

Synergistic Effects of Raised Temperature and CO2 on Strategists of Soil Enzyme and Microbial Communities 

Bin Song, Zhenhua Yu, Yuchao Wang, Jonathan Adams, and Bahar Razavi

The effects of global warming and CO2 influence on soil processes and crop growth are a major area of concern. Rhizosphere soil enzymes, mostly produced by microbes, play a pivotal role in enhancing soil nutrient accessibility for plant assimilation. Knowledge about the responses and adaptations related to the nutrient acquisition in space of microbial communities to increased temperature and CO2 re remaining deficient. Here, we grew soybean in rhizobox mesocosms under raised temperature (+2 ℃, ET) and CO2 (+300 ppm, ECO2) and the combination (ECO2+ ET). ECO2 increased the enzymatic hotspot area from 1.8 to 3.3% of soil, while ET increased enzyme activities by 2.5%-8.7%. Notably, the combined influence of ECO2 and ET synergistically amplified both the scope (increasing by 5.3% to 10.1%) and intensity (escalating by 35.4% to 67.3%) of three concurrent enzymes. Compared to ambient, rhizosphere communities in ECO2 were dominated by the keystone taxa of r-strategists, Acidobacteria, Proteobacteria, and Ascomycota. Conversely, ET shifted the microbial community to K- selection by increasing the relative abundance of Basidiomycota and Actinobacteria. Meanwhile, ECO2+ ET promoted the relative abundance of bacterial keystone species (Acidobacteria, Proteobacteria, and Actinobacteria) and fungi (Ascomycota and Basidiomycota) of the total community. These observations emphasize the potentially key role of enzyme hotspot areas in mediating climate change responses. Changes in the activity and extent of enzymes observed under the experimental treatments suggest a shift in balance towards a mixed r and K strategy in the hotspot microbiota. The microbial communities showed clear shifts in composition of the structure in response to the treatments, with changes in taxonomic composition, network structuring, and the balance between r and K-designated species.

How to cite: Song, B., Yu, Z., Wang, Y., Adams, J., and Razavi, B.: Synergistic Effects of Raised Temperature and CO2 on Strategists of Soil Enzyme and Microbial Communities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11977, https://doi.org/10.5194/egusphere-egu24-11977, 2024.

EGU24-12561 | Posters on site | SSS4.3

Rhizosphere microbial activities in response to combined effects of drought and microplastic  

Ali Feizi, Duyen T.T. Hoang, Bahar S. Razavi, and Sandra Spielvogel

The human’s well-being is challenged by various global issues such as environmental pollution and climate change. While plastic waste, particularly microplastic, is an emerging environmental pollution, drought becomes a more frequent natural hazard to cropping system.

Two hypotheses were proposed in this research as (i) drought is more dominated as compared to microplastic existence regulating microbial activities; (ii) the effects of microplastic on enzyme activities and distribution are enzyme specific and depends on microplastic types. Zymography was acquired to demonstrate the distribution of β-glucosidase (GLU) and acid phosphatase (APT) within soybean rhizosphere amended with either biodegradable microplastics or nondegradable microplastics. In addition, enzyme activities of GLU, APT, leucine aminopeptidase (LEU), and microbial biomass phosphorus (MBP) were assayed to prove the hypotheses. Five-time lower hotspot percentage in dry soil than moist soil regardless of microplastic types implied an overwhelming impacts of water stress as compared to microplastics on the microbial degradation of soil organic matter in the plant-soil ecosystem. A shortened rhizosphere extent was found in microplastic treatments also demonstrated its negative influence on rooted microbial activities. In conclusion, the co-influence of two distinguished abiotic factors should increase the complexity of plant-microbe association and unpredicted regulation of nutrient and C flux in the crop land.

Keywords: rhizosphere, enzyme activities, microbial biomass, drought, zymography

How to cite: Feizi, A., Hoang, D. T. T., Razavi, B. S., and Spielvogel, S.: Rhizosphere microbial activities in response to combined effects of drought and microplastic , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12561, https://doi.org/10.5194/egusphere-egu24-12561, 2024.

EGU24-13285 | Orals | SSS4.3

Abiotic soil matrix, rather than microbial community composition, determines litter C cycling 

Kyle Mason-Jones, Kira Ingenhoven, S. Emilia Hannula, G. F. (Ciska) Veen, and Wim H. van der Putten

Microorganisms are the primary agents of litter decomposition in the detritusphere, and are considered potentially powerful levers for influencing soil biogeochemical transformation of plant C into soil organic matter (SOM). However, it remains unclear whether soil microbial activity is primarily constrained by the microbial community composition or by the abiotic soil habitat in which they live. We explored the relative importance of abiotic and biotic factors in litter carbon (C) cycling by reinoculating five sterilized agricultural soils from the Netherlands with six contrasting soil microbial communities from a gradient of land-use intensity. Admixing of subsurface horizons (representing older SOM) and the addition of synthetic ferrihydrite (as an iron oxide representative) were included as additional abiotic manipulations. 16S and ITS amplicon sequencing confirmed that the contrasting communities successfully colonized the sterilized soils and retained strong signatures of their source inoculum during a laboratory incubation of nine months. Nevertheless, basal respiration of SOM and the mineralization of isotopically (13C) labelled litter (Lolium perenne) was overwhelmingly determined by the abiotic soil matrix, most notably the source soil and mixing of subsurface horizons. Ferrihydrite, in contrast, had little effect. These observations were extended by quantification of mineral nitrogen as well as 13C incorporation into particulate and mineral-associated SOM fractions. The findings provide strong experimental support for the responsiveness of C cycling to soil abiotic habitat factors, irrespective of community structure.

How to cite: Mason-Jones, K., Ingenhoven, K., Hannula, S. E., Veen, G. F. (., and van der Putten, W. H.: Abiotic soil matrix, rather than microbial community composition, determines litter C cycling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13285, https://doi.org/10.5194/egusphere-egu24-13285, 2024.

EGU24-13344 | Orals | SSS4.3

Metabolic responses to hotspot-forming processes: growth modes and their ecological consequences 

Michaela A. Dippold, Callum C. Banfield, and Kyle Mason-Jones

Hotspots are characterized by an increased availability of nutritional elements compared to the surrounding bulk soil, which enhances microbial activity. However, the shifts in nutrient stoichiometry, when hotspot formation is initiated by a non-microbial organic matter source (rhizodeposits, litter, feces & mucus, percolating dissolved organic matter), are highly hotspot-specific. This results in contrasting microbial dynamics in the rhizo-hyphosphere, the detritusphere, the drilosphere and further biopores of soil animals, and in preferential flow pathways.

Experiments and models of microbial growth-death dynamics have recently improved our understanding of how element stoichiometry shapes element allocation in microbial metabolism. This holds specifically true for to the two contrasting pathways of microbial growth – intracellular element storage versus the investment of C, nutrients and energy in replicative microbial growth. Both growth modes involve synthesis of organic polymers – either storage or structural cellular polymers. However, the nature of these two types of polymers is highly contrasting with regards to their elemental but also their molecular diversity, such that the two growth modes generate distinct differences in the molecular compositon of the cellular biomass. We can therefore expect that the stoichiometric differences of nutrient hotspots will drive differences in the molecular diversity of the microbial biomass, and so ultimately the successively accumulating necromass.

Whereas controlled incubation experiments demonstrate how element allocation to storage and replicative growth depends on nutrient stoichiometry, we lack an understanding of how growth modes are distributed among hotspots in situ. Besides developing this conceptual understanding, we aim to shed light on the implications of differences in cell physiology among hotspots, which includes i) the turnover rate of microbial biomass due to contrasting resistance to stress (e.g. starvation), ii) the molecular composition of the microbial cells and iii) the resulting chemical properties and molecular diversity of necromass. These factors strongly influence the formation rates, qualities and persistence of necromass-derived soil organic matter arising in these hotspots. Furthermore, the accrual of organic matter shapes microbial resource availability, including element stoichiometry, in the hotspot, as well as the physico-chemical microbial habitat properties. In consequence, a feedback loop between microbial growth- and turnover-based organic matter formation and the initial processes, that trigger the hotspot formation elaborates. Thus, although hotspot formation is always initiated by non-microbial organic matter input, the characteristics of the established soil hotspots are ultimately linked to the microbial necromass’ molecular and elemental diversity, which is the direct product of the hotspots’ microbial metabolism and growth mode. This study aims to relate the nutrient enriching processes (rhizodeposits, litter, feces & mucus, percolating DOM) and soil-intrinsic feedbacks to the dominant microbial growth modes and resulting properties of the organic matter in soil hotspots. 

How to cite: Dippold, M. A., Banfield, C. C., and Mason-Jones, K.: Metabolic responses to hotspot-forming processes: growth modes and their ecological consequences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13344, https://doi.org/10.5194/egusphere-egu24-13344, 2024.

EGU24-13836 | ECS | Orals | SSS4.3

Consumption of methane by a landfill cover soil under variable moisture and temperature conditions 

Christina Lam, Stephanie Slowinski, Mehdi Ramezanzadeh, Laura Hug, Nathanael Willms, Philippe Van Cappellen, and Fereidoun Rezanezhad

Landfills are one of the largest anthropogenic sources of methane (CH4), and hot-spots of CH4 emissions in landfill cover soils can enrich microbes that oxidize CH4 to carbon dioxide (CO2). CH4 oxidation rates are modulated by multiple variables including soil moisture and temperature, although the interactive effects of these factors on CH4 oxidation rates have not been well-studied. Here, we conducted a closed-headspace batch experiment with cover soil from a former landfill in Ontario, Canada to measure CH4 consumption and CO2 efflux rates associated with variations in soil moisture and temperature simultaneously. Soil samples were incubated under a factorial design of 5 soil moisture contents ranging from 11 to 47% WFPS (water-filled pore space), and 6 temperatures ranging from 1 to 35°C. At each temperature and WFPS combination, CH4 (812 nmol) was spiked into the headspace, and headspace CH4 and CO2 concentrations were measured over 2 hours to calculate CO2 efflux and CH4 consumption rates. The maximum CO2 efflux rate was observed at the maximal WFPS and temperature conditions of this experiment (92 nmol h-1 g dry wt.-1 at 47% WFPS and 35°C), while the maximum CH4 consumption rate was observed at intermediate WFPS and temperature conditions (1.9 nmol h-1 g dry wt.-1 at 25% WFPS and 25°C). The CO2 efflux observed is primarily attributed to the oxidative degradation of soil organic matter. A diffusion-reaction model was fit to the observed data to represent the effects of temperature and soil WFPS on the CH4 consumption and CO2 efflux rates. The model predicted similar optimal conditions as those observed for both the CH4 consumption and the CO2 efflux rates. The modeling and experimental results show that the dominant controls on optimal soil moisture for CH4 consumption are moisture limitation of microbial activity and of gas (CH4 and oxygen) diffusion, versus the interactive effects of moisture limitation of gas (oxygen) diffusion and of solute mobility for CO2 effluxes. These results provide insight into how seasonal changes in soil moisture and temperature could impact CH4 oxidation rates, and therefore also net CH4 emissions, in landfill cover soils and other environments.

How to cite: Lam, C., Slowinski, S., Ramezanzadeh, M., Hug, L., Willms, N., Van Cappellen, P., and Rezanezhad, F.: Consumption of methane by a landfill cover soil under variable moisture and temperature conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13836, https://doi.org/10.5194/egusphere-egu24-13836, 2024.

EGU24-13923 | ECS | Posters on site | SSS4.3

A urea-based symbiotic transfer of nitrogen in biological soil crusts 

Ana Mercedes Heredia-Velasquez, Soumyadev Sarkar, Finlay Warsop Thomas, and Ferran Garcia-Pichel

Crucial to the establishment of biological soil crusts is a mutualistic exchange of C for N between pioneer filamentous non-heterocystous cyanobacteria of the Microcoleus type and a selected group of heterotrophic diazotrophs (for example, Massilia sp.) that come together in the so-called “cyanosphere”. In other such C for N mutualisms, N is transferred between species in the form of amino acids, and potential losses to adventitious bacteria are prevented by sequestering the diazotrophs into specialized structures. Yet, in the Microcoleus symbiosis no such structures exist, and only proximity achieved through chemotaxis is known to optimize the exchange. How is specificity then achieved?  We posited that the exchange might occur through urea, because it is the preferred N source for growth in Microcoleus. We show using cultures that members of the cyanosphere excrete urea when growing in symbiosis with Microcoleus at low concentration but sustained rates, but not when growing on their own diazotrophically. Consistently, Microcoleus can grow on urea down to the micromolar range, unlike other cyanobacteria that need much higher concentrations to grow. We also show that Massilia overexpresses the genes for the urea cycle (production of urea) when in symbioses, but not otherwise, and that Microcoleus overexpresses genes for urea uptake and utilization when in symbiosis. Microcoleus contains a rare set of enzymes for urea utilization (allophanase and urea carboxylase), that, unlike the widespread urease, allow it to process urea at very low concentrations. Hence, it seems that with the combination of these unique biochemical and regulatory capacities, low concentration urea can effectively transfer N in a partner-specific way, dodging potential losses of N to most other bacteria that can only use urease. We discuss the importance of these findings for the ecology and restoration of biological soil crusts.

 

How to cite: Heredia-Velasquez, A. M., Sarkar, S., Warsop Thomas, F., and Garcia-Pichel, F.: A urea-based symbiotic transfer of nitrogen in biological soil crusts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13923, https://doi.org/10.5194/egusphere-egu24-13923, 2024.

We are currently revisiting a study by Flechtner, Johansen, and Belnap (2008) on the algae of biological soil crusts on San Nicolas Island.  A total of 200+ strains have been newly isolated, of which 78 cyanobacterial strains have been sequenced, representing 26 different species.  Of these 26 species, 23 appear to be phylogenetically new to science.  Several isolates show distinctive biogeography, belonging to genera recently described from Brazil. We found evidence of three species of the heterocytous genus Atlanticothrix, two species of Pycnacronema, and one species of Konicacronema.  Our species are morphologically consistent with species of these genera, but molecularly are clearly separated, particularly on the basis of ribosomal gene trees and analysis of the 16S-23S internal transcribed spacer region. There are presently no known vectors for transmission of taxa from the Atlantic Forest in Brazil to San Nicolas Island, or vice versa.  Wind patterns from Africa are known to bring dust from that continent to both South America and North America, but winds in the western hemisphere blow out into the Pacific Ocean in a westerly direction and do not cross the equator.  This suggests that at some time in the distant past, these microbes may have been seeded from Africa to North America, but have been in place long enough to become independent distinctive lineages worthy of recognition as different species from their southern hemisphere congeners. As preliminary evidence supporting an African origin for soil crust taxa, other workers have reported cyanobacterial genera in Africa (Pseudoacaryochloris, Aliterella, and Atlanticothrix) that also occur on San Nicolas Island. Future work will explore the cyanobacterial flora of all the Channel Islands as well as coastal southern California which could serve as a colonization source for cyanobacteria on the islands.

How to cite: Johansen, J. and Jusko, B.: Discovery of new cyanobacterial species from crusted soils of San Nicolas Island, California, from genera previously restricted to Brazil and Africa., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14115, https://doi.org/10.5194/egusphere-egu24-14115, 2024.

EGU24-14182 | Orals | SSS4.3

Revealing cyanosphere microbial diversity of terrestrial cyanobacteria 

Nicole Pietrasiak, Brianne Palmer, Estelle Couradeau, and Jason Stajich

The cyanosphere contains heterotrophic microorganisms living within the exopolysaccharide sheath of cyanobacteria and serves as an interface between the cyanobacteria and their surrounding ecosystem. The symbiosis between the cyanobacterial host and its cyanosphere microbes spans the mutualistic-antagonistic spectrum. Understanding these relationships will predict the success of terrestrial cyanobacteria and the ecosystem services they provide including primary production in often oligotrophic environments. However, our understanding of the microbial diversity within the cyanosphere is limited. In this study, we used metagenomic sequencing to construct 528 metagenome-assembled genomes (MAGs) from the cyanosphere microbes associated with 50 unialgal terrestrial Cyanobacteria cultures, spanning 12 orders. We found that the composition of cyanosphere microbial communities was unique between Cyanobacteria hosts and was largely influenced by environmental (habitat, precipitation, and temperature) and phylogenetic variables (host order). Alphaproteobacteria was the most common cyanosphere microbial class and Bosea, Devosia, Hyphomicrobium, Mesorhizobium, and Sphingomonas were core genera found across all habitats. Interestingly, the nitrogen-fixing cyanobacterial order, Nostocales, contained the highest diversity of cyanosphere bacteria, many of which have the genomic potential also to fix atmospheric nitrogen. Given the observed variations in the cyanosphere microbial communities across different hosts, future considerations for ecological assessments and cyanobacterial restoration efforts must extend beyond the cyanobacteria to encompass their associated microbial communities.

How to cite: Pietrasiak, N., Palmer, B., Couradeau, E., and Stajich, J.: Revealing cyanosphere microbial diversity of terrestrial cyanobacteria, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14182, https://doi.org/10.5194/egusphere-egu24-14182, 2024.

EGU24-14268 | ECS | Posters on site | SSS4.3

Distribution of biological soil crusts in the Tibetan Plateau 

Zhixin Zhou, Ning Chen, Li Ma, Liping Yang, Hongyu Jiang, and Siqing Wang

Biological soil crust (biocrust) is regarded as a self-organizing principle, and widely distributes in the Tibetan Plateau, which is a crucial ecological security area of China and water towel of Asia. Unfolding biocrust distribution in the region is critical to maintain ecosystem functions and services therein. However, we know little about explicit distribution of biocrust in the Tibet Plateau. To that end, this study combined field survey, reference compiling and random forest algorithm to explore the spatial distribution of biocrusts on Tibetan Plateau and the associated driving factors. A total of 203 data points had been collected. We found that the biocrusts cover up to 20% of the soil surface in the Tibetan Plateau and mainly cover the Qaidam Basin and the northern Tibetan Plateau, but less in the Qiangtang Plateau and the southeastern Tibetan Plateau.The dominating factors affecting biocrust distribution are soil clay content, altitude, average temperature of the hottest season, pH, and soil organic carbon content. Specifically, biocrust acclimatization is positively affected by lower soil clay content and elevation, hotter quarter temperatures (especially greater than 8°C), and greater pH, while negatively affected by higher soil organic carbon content. Overall, this study sheds light on biocrust distribution in the Tibetan Plateau, and will significantly expand our understandings of biocrusts.

How to cite: Zhou, Z., Chen, N., Ma, L., Yang, L., Jiang, H., and Wang, S.: Distribution of biological soil crusts in the Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14268, https://doi.org/10.5194/egusphere-egu24-14268, 2024.

EGU24-14324 | ECS | Posters virtual | SSS4.3

Effects of Elevated Temperature on Microbial Growth and Enzyme Kinetic During Transition from Rhizosphere to Root-Detritusphere 

Seyed Sajjad Hosseini, Mehdi Rashtbari, Amir Lakzian, and Bahar S. Razavi

Microbial growth and enzyme activity depend on carbon availability, which strongly differs in rhizosphere and root-detritusphere. Elevated temperature is expected to intensify enzymatic processes in these spheres. However, the response of soil enzyme activity to elevated temperature may be influenced by microbial growth, driven by variations in carbon availability. Therefore, our study investigated the response of enzyme kinetic parameters to elevated temperature during transition from rhizosphere to root-detritusphere and potential linkage to microbial growth. For this purpose, we measured active microbial biomass (AMC) and growth rate (µ) through substrate-induced growth respiration, as well as kinetic parameters of ꞵ-glucosidase (GLU) in rhizosphere (six weeks after planting) and root-detritusphere (four weeks after shoot cutting) of wheat at two different temperatures, 20 ᵒC and 30 ᵒC.

At both temperatures, a higher µ was observed in the root-detritusphere compared to the rhizosphere. Elevated temperatures significantly enhanced µ by 2.13 and 2.23 times in the rhizosphere and root-detritusphere, respectively. Additionally, AMB in root-detritusphere was lower than in the rhizosphere at both temperatures. Notably, at 30 ᵒC, AMB in the rhizosphere and root-detritusphere was 4.7 and 2.9 times lower than that at 20 ᵒC, respectively. The lower AMB in root-detritusphere and higher temperature, results from microbial starvation caused by rapid substrate uptake and fast growth. At 20 ᵒC, Vmax of GLU in root-detritusphere was higher than in rhizosphere, whereas at 30 ᵒC, the trend was reversed. Elevating the temperature from 20 ᵒC to 30 ᵒC within the rhizosphere resulted in an increase of 98% in the Vmax of GLU. Conversely, in the root-detritusphere, this temperature shift led to a reduction of 29% in the Vmax of GLU. The findings indicate that a reduction in AMB within the root-detritusphere leads to a downregulation of enzyme production. However, enzyme production in the rhizosphere is intricately regulated by both living roots and soil microorganisms, rendering it unaffected by changes in AMB.

How to cite: Hosseini, S. S., Rashtbari, M., Lakzian, A., and Razavi, B. S.: Effects of Elevated Temperature on Microbial Growth and Enzyme Kinetic During Transition from Rhizosphere to Root-Detritusphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14324, https://doi.org/10.5194/egusphere-egu24-14324, 2024.

Arbuscular mycorrhizal fungi (AMF) affect both plant nutrition and soil physical properties, including soil water retention and hydraulic conductivity. However, much less is known about the preferences of AMF for proliferation into soils of different (physical) natures, i.e. soil textures. To investigate this, we designed a pot trial with tomato in which AMF had access to root-free soil patches of different textures. We hypothesized that AMF would prefer fine-textured soils over coarse-textured soils because a finer textured soil is comparatively moist (which most fungi prefer) and contains a greater share of low-weight particles (less growth resistance) than a coarse-textured soil.

We inoculated tomato plants with the fungus Rhizopagus irregularis grown in 4L pots filled with a quartz sand: loam mixture (1:1 w/w). The loam is a calcareous alluvial loam obtained from the C-horizon with a pH of 7.5, low in organic matter (0.05% Corg), 42.72% sand, 44.22% silt, 13.06% clay and is highly P-fixing. The self-propagated fungal inoculum used was based on this loamy soil and, therefore, inoculation did not compromise the soil texture of the potting mix. Each pot received three ingrowth cores covered in root-excluding nylon mesh (37 µm) containing either pure quartz sand (grain size 0.3 – 1.0 mm), pure loam soil or a 1:1 mixture of the two (as in the main pot). To cause variance in soil hyphae development, we applied two treatments. On the one hand, half of the pots contained the tomato cultivar 76R and the other half its related rmc mutant, which is known to show reduced mycorrhizal colonization. On the other hand, we subjected half of the pots to two weeks of terminal drought to slow down plant and fungal growth, while the other half of the pots were kept under ample moisture. After harvest, we measured root colonization and plant nutrient uptake to verify the viability of the mycorrhizal symbioses. From the ingrowth cores, we extracted AMF hyphae and determined their length. As traits known to be affected by functional hyphae and plant activity as well as soil desiccation, we also measured aggregate stability indices in soils from the ingrowth cores.

According to our expectations, we found that the 76R tomatoes, which were able to develop a viable symbiosis, had higher tissue P and N mass fractions in their dry matter than the rmc tomatoes.  Against our expectations, the 76R plants were more sensitive to drought when exposed to it and had significantly lower biomass than the rmc plants and the 76R plants maintained under ample moisture. Furthermore, we illustrate our findings on hyphal length density and aggregation and discuss them with regard to the preferences of AMF to populate the soils with different textures. We answer whether our hypothesis must be confirmed or denied and deduce some potential ecological consequences of our findings.

How to cite: Jacob, E., Camenzind, T., and Bitterlich, M.: The modulation of plant nutrition and soil properties by mycorrhizal fungi and their preferences for the soil texture they encounter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15871, https://doi.org/10.5194/egusphere-egu24-15871, 2024.

EGU24-16663 | Orals | SSS4.3

Nutrient and Water Availability Modulate the Destabilization of Mineral-Associated Organic Matter in the Rhizosphere 

Marco Keiluweit, Mariela Garcia Arredondo, Sherlynette Castro, Malak Tfaily, and Zoe Cardon

Soils are the largest and most dynamic carbon reservoir in terrestrial environments, with most carbon stored as mineral-associated organic matter (MAOM). It has recently been shown that MAOM is effectively destabilized by reactive compounds released by plant roots and associated microbes. It is well known that quantity and quality of rhizodeposits dramatically change in response to nutrient or water stress, with unclear consequences for rates of plant root-driven MAOM destabilization. Here we show that altered rhizodeposition in response to environmental stressors affects rates of root-driven MAOM destabilization. Well-controlled growth chamber experiments with Avena sativa (common oat) allowed us to test the individual and interactive effects of nitrogen, phosphorus, and water limitations on the fate of 13C-labeled MAOM over a 10-week period. At the end of the experiment, total MAOM mineralization was strongly correlated with root biomass, which generally declined with nutrient and water limitations. However, under P limitations, root-driven MAOM mineralization was greatest during the initial growth stages (vegetative), whereas N limitations resulted in greater rates of MAOM mineralization during later growth stages (flowering). Drought treatments, when compared to their corresponding optimal watering treatments, produced the least MAOM destabilization. To test whether temporal changes in MAOM destabilization rates can be explained by differences in rhizodeposition intensity and composition, we analyzed rhizodeposits collected throughout the experiment via high-resolution mass spectrometry. This study demonstrates that MAOM mineralization is regulated not just by the inherent stability of MAOM against microbial attack, but also depends on plant water and nutrient availability within the whole plant-soil system as well as plant physiological and phenological stages. Through such feedback, changes in soil nutrient and water status (e.g. via altered precipitation or fertilizer application) can be expected to cause plant-induced alterations to the size of the otherwise stable, mineral-associated soil carbon reservoir.

How to cite: Keiluweit, M., Garcia Arredondo, M., Castro, S., Tfaily, M., and Cardon, Z.: Nutrient and Water Availability Modulate the Destabilization of Mineral-Associated Organic Matter in the Rhizosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16663, https://doi.org/10.5194/egusphere-egu24-16663, 2024.

EGU24-16883 | ECS | Orals | SSS4.3

Temperature increases the versatility of belowground plant-microbiota interactions in cold climates 

Dina in 't Zandt, Anna Aldorfová, Mária Šurinová, Michiel H. in ‘t Zandt, Vigdis Vandvik, and Zuzana Münzbergová

The ongoing change in climate extensively alters belowground interactions between plants and microbiota. Alterations in plant-microbiota interactions have significant implications for the functioning of ecosystems. To predict ecosystem change and protect vulnerable systems, it is therefore crucial to understand how climate shapes belowground plant-microbiota interactions. We test how prokaryote and fungal rhizosphere and root-associated communities of the perennial grass Festuca rubra are affected by temperature and precipitation in cold climate settings. We found that microbial communities were strongly shaped by temperature and to a lesser extent by precipitation. Temperature decreased relative habitat specialisation of the rhizosphere community and the fungal root-associated community. These effects were mediated by an increase in forb cover and a decrease in soil pH with temperature. Our findings indicate that with a rise in temperature in cold environments, plant-microbiota interactions become more versatile and adapted to a broader range of environmental conditions.

How to cite: in 't Zandt, D., Aldorfová, A., Šurinová, M., in ‘t Zandt, M. H., Vandvik, V., and Münzbergová, Z.: Temperature increases the versatility of belowground plant-microbiota interactions in cold climates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16883, https://doi.org/10.5194/egusphere-egu24-16883, 2024.

EGU24-20430 | ECS | Posters on site | SSS4.3

Harnessing biocrust-isolated bacteria from semiarid soils to promote plant growth in ecological restoration 

Beatriz Roncero-Ramos, Carlotta Pagli, Lisa Maggioli, Eloisa Pajuelo, Yolanda Canton, and Miriam Muñoz-Rojas

Restoration of drylands is crucial to reverse global land degradation because these areas cover around 40% of the Earth surface and host one third of the world population. Restoration efforts are often unsuccessful in drylands and alternative approaches need to be developed, i.e., biocrust-based restoration, to promote plant growth and increase soil fertility and stability. In this research, we cultured several biocrust-forming organisms to inoculate them on degraded soils. We designed a more effective inoculum based on biocrust-forming heterotrophic bacteria with plant growth promotion properties (PGP) and key enzymatic activities. We hypothesised that inoculation of native seeds with a consortium of selected heterotrophic bacteria would enhance seed germination and establishment. We sampled incipient and developed biocrusts from three study sites located in semi-arid areas from SE Spain, and isolated 48 bacterial strains. We performed a screening within the bacterial collection to find those strains with key PGP properties and enzymatic activities. Specifically, we analysed their capacity to fix N2, solubilize P and K, produce biofilms, auxins and siderophores, and the extracellular activity of DNAse, amylase, protease, catalase, and lipase. Then, we assessed the best performing bacterial strains for co-culturing to avoid possible antagonistic effects and identified them by sequencing the 16S rRNA gene. The next step of this project will focus on assessing the effects of seed pelleting with the best-performing consortium on germination and establishment of native plants.

How to cite: Roncero-Ramos, B., Pagli, C., Maggioli, L., Pajuelo, E., Canton, Y., and Muñoz-Rojas, M.: Harnessing biocrust-isolated bacteria from semiarid soils to promote plant growth in ecological restoration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20430, https://doi.org/10.5194/egusphere-egu24-20430, 2024.

EGU24-20825 | ECS | Orals | SSS4.3

Effect of ZnO nanoparticles on the bacterial community and other soil health parameters 

Zoya Javed, Gyan Datta Tripathi, and Kavya Dashora

The rapid growth of metallic nanoparticles (such as ZnO) in the present time increases the risk of the contamination of soil because it is the sink for all the nanoparticles, intentionally or unintentionally, and affects the microorganism productivity and damages the soil health. Zinc oxide nanoparticles are widely used in agriculture and other industries at the current time. Our study aimed to evaluate the toxicological effects of zinc oxide nanoparticles on the bacterial diversity of soil. A microcosm experiment was conducted by mixing the 1000 µg/gm of ZnO nanoparticles in the soil. After 60 days, the effect of zinc oxide nanoparticles on bacterial diversity was determined using Illumina MiSeq sequencing of 16S rRNA genes. The soil's physiochemical characteristics, such as C, H, and N content, were analyzed and compared with non-treated samples. Dehydrogenases (DH) and fluorescein diacetate (FDA) were assayed as the soil health indicator.  Results have shown that the relative abundances of the dominant and agriculturally significant phyla, namely, Proteobacteria and Actinobacteria, were altered in the presence of Zinc Oxide nanoparticles. However, it was also observed that Zinc oxide nanoparticles showed negligible effects at the phylum level. The dissolution of ZnO nanoparticles was also estimated with the help of ICP-MS, which was 870 µg/gm after 60 days. DH activity was higher and FDA activities were lowered compared to the non-treated soil.

How to cite: Javed, Z., Tripathi, G. D., and Dashora, K.: Effect of ZnO nanoparticles on the bacterial community and other soil health parameters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20825, https://doi.org/10.5194/egusphere-egu24-20825, 2024.

EGU24-20849 | Orals | SSS4.3

Impact of Copper oxide nanoparticles on soil isolated Bacillus megaterium   

Gyan Datta Tripathi, Zoya Javed, and Kavya Dashora

Bacillus megaterium is a plant growth-promoting bacteria that performs various activities like producing hydrolytic enzymes in the soil such as protease and xylanase, releasing various growth hormones and other bioactive compounds that inhibit the plant pathogenic microbes in the soil. These microorganisms are not only part of the rhizosphere but instrumental in activities such as soil conditioning and nutrient cycling. But as the modernization of agriculture practices comes up with new age agrochemicals, called nano-agrochemicals, the concerns of toxicity also increased. These nano agrochemicals (such as CuO nanoparticles) have several advantages over the traditional chemicals, however, several properties like small size, lower dissolution, and potential to alter soil properties such as pH, raise serious threats to the soil beneficial microbes. It is also estimated that the accumulation of nanoparticles in the soil may become available for microbial ecosystems and cause toxicity with unique mechanisms, eg contact mode toxicity. Copper oxide nanoparticles are integral to new-era agrochemicals like nano-pesticides, nano-fertilizers, etc. There are mixed reviews on the toxicity of CuO nanoparticles on soil owing to diverse microbiota. Our in vitro studies were focused on the analysis of the size and dose-dependent impact of nanoparticles on the plant growth-promoting species  Bacillus megaterium at cellular, morphological as well as Indole acetic acid (IAA) production potential. Our study reveals that the small dose (0.05mg/ml) of copper oxide is not harmful to the microbes because copper is one of the essential elements However at upper concentration around 0.5mg to 1 mg/ml was significantly toxic for the Bacillus megaterium. The size-dependent toxicity on IAA production was also tested with the two different sizes of the CuO nanoparticles and the results were not significantly different.  

 

How to cite: Tripathi, G. D., Javed, Z., and Dashora, K.: Impact of Copper oxide nanoparticles on soil isolated Bacillus megaterium  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20849, https://doi.org/10.5194/egusphere-egu24-20849, 2024.

EGU24-21104 | ECS | Posters virtual | SSS4.3

Biological soil crusts stabilize degraded soils of the Brazilian Pampa affected by sandization 

carla webber, Ulisses F. Bremer, Ruhollah Tagizadeh-Mehrjardi, Bettina Weber, Aline Rosa, Thomas Scholten, and Steffen Seitz

Biological soil crusts (biocrusts) are a main factor in the protection of arid and semiarid ecosystems. They are key contributors to soil stabilization and erosion control through the aggregation of particles and the provision of a continuous surface cover. In the Brazilian Pampa, vegetation disturbance and soil degradation led to an expansion of sandization areas. These areas are quickly covered by biocrusts, which show the same soil-stabilizing effects as in other geographic regions but have not been investigated in this biome before.

The present study aims to expand our knowledge on the occurrence of biocrusts in sandization areas of the Brazilian Pampa and to analyse their distribution patterns related to the local topography. We focused on two research sites, where the presence of biocrusts seemed essential for soil protection. At these sites, first, the different biocrust types were assessed and a taxonomic survey was conducted. Second, UAV-based imagery was created to classify the communities. A random forest approach was applied to understand the relation between biocrust abundance and topography.

We observed that biocrusts are widespread in areas prone to sandization, with a coverage of approximately 25% of the surface area. They are mostly dominated by cyanobacteria, but also bryophytes play a key role. In this study, the cyanobacterial genus Stigonema was predominant at both study sites, while Campylopus pilifer was the dominating moss species. The mapping confirmed all major biocrust types including rolling, pinnacled, rugose, and smooth crusts. The biocrust distribution was influenced by local topography, but also the establishment of vascular plants. Slope and aspect had a strong influence on biocrust development, but the presence of protective topographic positions against atmospheric influences most prominently facilitated their occurrence.

This pilot study proved that biocrusts can play a key role as ecosystem engineers in the Brazilian Pampa with a positive effect on general vegetation growth and soil stabilization. Despite their significant impact in sandization areas, biocrusts are not in the focus of research, yet, and should be further studied to constrain future soil degradation.

How to cite: webber, C., Bremer, U. F., Tagizadeh-Mehrjardi, R., Weber, B., Rosa, A., Scholten, T., and Seitz, S.: Biological soil crusts stabilize degraded soils of the Brazilian Pampa affected by sandization, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21104, https://doi.org/10.5194/egusphere-egu24-21104, 2024.

Plant derived organic matter (OM), entering soils either as aboveground plant litter or via belowground rhizodeposition or dead roots, undergoes microbial mineralization and transformation and finally ends up in various soil OM (SOM) pools. With two major solid SOM pools besides dissolved OM, namely particulate OM (POM) and mineral-associated OM (MAOM), the initially plant dominated OM is progressively transformed into microbial OM during decomposition. However, as mineral soils comprise highly heterogeneous systems over a wide range of spatial and temporal scales, the microbial transformation of plant OM and the formation of SOM is highly variable in time and space as well. Processes controlling the persistence of SOM are especially determined at nm to µm scales at biological highly active biogeochemical interfaces. Thus, plant litter and roots form distinct soil hot spots for interactions between microbiota, OM and mineral particles that are thought to control the long-term fate of soil carbon. The detritusphere and rhizosphere thus represent soil volumes that host the complex interplay of biological, chemical and physical soil processes that determine the fate of SOM. We will highlight the intricate connection between the transformation of plant derived OM via microbial processing and soil structure formation that lead to the build-up of persistent SOM.   

How to cite: Mueller, C. W.: Plants, microorganisms and soil minerals, how the persistence of soil organic carbon is regulated at microscale interfaces, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21758, https://doi.org/10.5194/egusphere-egu24-21758, 2024.

EGU24-21779 | ECS | Orals | SSS4.3

Biocrusts, ecological indicators in the Australian rangelands 

Wendy Williams, Than Myint Swe, Maria Vega, Colin Driscoll, Robyn Cowley, Peter O’Reagain, Andries Potgieter, Yan Zhao, Paul Dennis, and Susanne Schmidt

The Australian rangelands that cover around 70% of the country (~6 million km2) are inhabited by some of the most extensive and diverse biocrusts globally. These regions are predominately managed as natural grazing lands. Across northern Australia where the climate is influenced by the monsoon (wet season) biocrusts dominated by cyanobacteria and liverworts occupy the interspaces between grass plants as a coherent layer that binds the upper millimetres of soil and forms a living cover of photoautotrophic (cyanobacteria, algae, lichens and bryophytes), and heterotrophic (bacteria, fungi and archaea) organisms. During the dry season biocrusts are inactive, then recover at the onset of the wet season, actively participating in nitrogen and carbon fixation and accumulation. To identify the role of biocrusts as ecological indicators, we modelled their distribution, diversity and function across microhabitats. We also determined how biocrust community dynamics had been influenced by long-term fire and grazing management regimes.

At Victoria River Research Station (Kidman Springs, NT), after 30 years of fire research we compared managed burning practices at 2, 4 or 6-yearly intervals on two soil types (calcarosol, vertosol). Biocrusts were resilient and recovered rapidly from fire, where diversity and genetic function altered seasonally, between soil types, and fire regimes. Post-fire, after a wet season (cattle excluded), biocrusts recovered with significantly more carbon and nitrogen in the surface soils of cooler fire treatments every four years.  

At Wambiana Cattle Station (QLD), grazing trials have been established for 25 years. When paddocks were rested from cattle grazing every second year, biocrusts in duplex soils recovered to levels comparable to ungrazed natural sites. In red-yellow earths, there were biocrust hotspots that provided protection to the soil surfaces when there was a loss of grass cover during drought. Biocrust diversity and function differed between soil type and management (moderate and heavy stocking).

This research demonstrates that the top centimetre of biocrust-rich soil is central to ground cover integrity and is essential to soil nutrient cycling and fertility. Biocrusts are an important indicator for overall vegetative recovery post fire, grazing and drought disturbances. The principles of land cover condition based on landscape function should include biocrust presence as a metric that describes landscape resilience, as opposed to bare unprotected ground. Importantly, land managers can apply this research to grazing practices that show that giving the land rest periods timed to coincide with the wet season allows time for biocrust organisms to recover from disturbance.

How to cite: Williams, W., Myint Swe, T., Vega, M., Driscoll, C., Cowley, R., O’Reagain, P., Potgieter, A., Zhao, Y., Dennis, P., and Schmidt, S.: Biocrusts, ecological indicators in the Australian rangelands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21779, https://doi.org/10.5194/egusphere-egu24-21779, 2024.

The presence of multiple layers of red paleosol in loess strata poses challenges due to its high hardness, which hinders easy collapse when encountering water. This characteristic significantly affects the measurement results of the collapsible amount of loess strata. However, there is currently a lack of reports on the control effect of paleosol on collapsibility, resulting in a deficiency in the theoretical basis for the scientific selection of collapsibility in these strata. This paper aims to address this gap by analyzing the differences in self-weight collapsibility between indoor and outdoor conditions under various paleosol layers in different areas and strata. The analysis is based on statistical results from immersion tests conducted in the Loess Plateau. Furthermore, the research focuses on two test sites in Xi'an and conducts large-scale immersion tests, considering measurements such as water diffusion, changes in water content, soil pressure, and cumulative collapsibility under different test conditions. The study investigates the influence of paleosol layers on water infiltration and their role in controlling total weight collapse.The final results indicate that the presence of a paleosol layer prevents collapsibility from transferring to the lower layer and inhibits water infiltration, thereby reducing total collapsibility. Discrepancies between measured and calculated collapsibility values are positively correlated with the number of ancient soil layers. This research provides valuable insights into the collapsibility mechanism of paleosol-loess strata.

How to cite: Lin, L.:  Effects of paleosol on collapsibility of loess sites under immersion test conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-209, https://doi.org/10.5194/egusphere-egu24-209, 2024.

EGU24-1343 | Posters on site | SSS4.4

Soil Structural Stability Influenced by Land Management 

Maysoon Mikha, Timothy Green, Tyler Untiedt, and Gary Hergret

Soil structure is an important factor in regulating soil ecological functions and soil chemical, physical, and biological properties. This study evaluated soil structural stability from three locations within the central Great Plains (USA) under different management practices.  The study sites consisted of Alternative Crop Rotation (ACR) and Long-Term Tillage (LTT) near Akron, Colorado, and Knorr-Holden (KH) near Mitchell, Nebraska.  Tillage treatments consisted of no-tillage (NT), reduced tillage (RT), conventional tillage (CT), and moldboard plow (MP). Commercial mineral fertilizer (F) was used as a nitrogen source in ACR and LTT sites while manure (M) plus F treatments were used in KH.  Soil structural stability was evaluated using four indices, aggregate stability index (ASI), mean weight diameter (MWD), geometric mean diameter (GMD), and fractal dimension (FD).  At 0-15 cm depth, intensive tillage (CT and MP) in ACR and LTT, reduced (P < 0.05) ASI by 46.7%, MWD by 21.0% and GMD by 8.4% and increased FD by 0.77% compared with NT and RT treatments.  The addition of manure increased (P < 0.05) ASI by 72.2%, MWD by 65.6%, GMD by 32.8%, and reduced FD by 5.5% compared with tillage treatments in ACR and LTT.  Although FD was negatively correlated with MWD and GWD; it provides information not captured by ASI and complements MWD and GWD.  The indices presented in this study, including FD, are effective in measuring soil structural stability and should be considered further in management decisions to sustain soil resources and enhance economic returns.

How to cite: Mikha, M., Green, T., Untiedt, T., and Hergret, G.: Soil Structural Stability Influenced by Land Management, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1343, https://doi.org/10.5194/egusphere-egu24-1343, 2024.

The demand for ground improvement of marine sediments has been risen in construction of offshore infrastructures, including wharves, embankments and breakwaters. In recent years, microbially induced carbonate precipitation (MICP) has developed rapidly and become an alternative technology for increasing soil strength and limiting soil erosion. Silty sand is widely distributed in offshore areas throughout the world. The high salinity of seawater may have an impact on the bacterial activity, while the fine particles in silty sand would affect the transportation of cementation solution and the formation of carbonate precipitation. In this study, attentions are paid to the application of MICP on improvement of marine silty sand properties, as well as the factors influencing the hydraulic conductivity and strength of the bio-cemented soil. Multi-gradient domestication tests on Sporosacina pasteurii were carried out to ensure the bacterial and urease activities in seawater environment. It was found that the bacterial concentration and urease activity after five-gradient domestication in seawater reached 98.5% and 92.8% of those in the deionized water environment, respectively. The permeability, unconfined compressive strength (UCS) and content of carbonate precipitation of bio-cemented specimens were measured. The MICP treatment on silty sand with seawater resulted in an increase of UCS to 700 kPa and a reduction of permeability by an order of magnitude, corresponding to a carbonate content of 8%. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed to investigate the types and distributions of carbonate crystals. The results indicated the formation of calcium carbonate and magnesium carbonate crystals due to the interaction between carbonate ions and calcium and magnesium ions in seawater. The precipitations were distributed on the surfaces of soil particles and near particle contact points, affecting the soil microstructure and thus the strength and permeability. The influences of concentration and injection rate of cementation solution on the efficiency of MICP were demonstrated and the recommended values were given. This study may provide a possible solution for improvement of engineering properties of marine silty sand foundations.

How to cite: Tang, Y. and Cai, S.: Study on methodology and efficiency of microbially induced carbonate precipitation on improvement of marine silty sand, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2980, https://doi.org/10.5194/egusphere-egu24-2980, 2024.

EGU24-6823 | ECS | Orals | SSS4.4

The role of root mucilage and Extracellular Polymeric Substances in shaping soil structure and maintaining plant-soil contact 

Sara Di Bert, Konstantina Papadopoulou, Patrick Duddek, Andrea Carminati, and Pascal Benard

The hydraulic properties of the rhizosphere are essential for understanding root-soil interactions. Diverging from common assumptions in soil modelling, which often equate rhizosphere properties with those of bulk soil, research shows that the rhizosphere is distinct in its physical, biological, and chemical attributes.

There is a broad agreement on the role of mucilage and extracellular polymeric substances (EPS) in modifying soil water dynamics in the rhizosphere. However, the mechanisms of how these substances interact with the soil matrix and impact its hydraulic properties remain unclear. In this study, we assessed the forces exerted by Xanthan gum, used as a stand-in for EPS, maize root mucilage, and water - formed liquid bridges on particle pairs.

Forces were quantified for 1 microL liquid bridge between a pair of glass beads — one standing on a precision balance and the other fixed to a static stand. While the water bridges broke upon drying due to capillary forces, mucilage and Xanthan gum formed resilient filaments that maintain connectivity and tensile forces between the glass beads. The continuous recordings of weight changes by the balance provided crucial data for quantifying the force exerted on the beads during drying.

Our results show that both Xanthan gum and maize mucilage liquid bridges exert tensile strengths that are substantially greater than those of water bridges. The polymer solutions initially behave similarly to water, but the forces exerted on particle pairs deviate as the solutions dry, becoming progressively stronger. The tensile strength of water reaches around 10-1 mN, while maize and Xanthan gum are respectively 1 and 2 order of magnitudes bigger. This increase is caused by the stretching of the polymer network and the development of elastic forces.

The significant aggregating force observed in our study suggests that EPS and mucilage play a crucial role on the mechanics of the root-soil interface. They contribute to soil structure formation in the rhizoshere and to maintain root and soil contact as roots shrink in drying soils.

 

How to cite: Di Bert, S., Papadopoulou, K., Duddek, P., Carminati, A., and Benard, P.: The role of root mucilage and Extracellular Polymeric Substances in shaping soil structure and maintaining plant-soil contact, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6823, https://doi.org/10.5194/egusphere-egu24-6823, 2024.

EGU24-8747 | ECS | Posters on site | SSS4.4

Correlations between microbial activity and soil texture in Hungarian soils 

Orsolya Szécsy, Márk Rékási, Anita Szabó, and Nóra Szűcs-Vásárhelyi

As part of a national survey, 129 soil samples were taken countrywide across Hungary, in order to be representative of both soil types and intensity of cultivation of the country. The bulk samples were taken from 20 points of the diagonals of each sampling parcel, from the 0-30 cm surface layer. Among other soil physical parameters, samples were classified into soil textures based on the Arany yarn number. Microbial measurements were selected so that they could give an overall look at the actual biological soil state.

 

Our goal was to find out, whether we could detect correlations between soil texture, and clay content in particular with the measured microbial parameters regarding such a heterogeneous and large group of natural soil samples.

 

Biological activity of the soil samples were evaluated applying three tests: fluorescein-diacetate (FDA) and sucrose (invertase) enzyme activity tests as well as substrate induced respiration (SIR) measurement. The FDA test is suitable for estimating the soil’s microbial activity. The hydrolysis of FDA is based on the process of several soil enzymes hydrolysing colourless fluorescein-diacetate added to the soil. Released coloured fluorescein can be measured by spectrophotometry. Determination of sucrose (invertase) enzyme activity is founded on quantitative measurement of reducer monosaccharides emerging from the hydrolysis of sucrose. This test provides information on the carbohydrate metabolism processes in the soil. The most important indicator of soil biological activity is the degree of soil respiration that can be measured through the quantitative analysis of the CO2 produced by the decomposition of organic matter. Substrate induced respiration (SIR) method is based on a so-called respiration answer given by the microbial biomass in the presence of an easily utilisable substrate (glucose) being in saturated concentration. Statistical analysis of the data was performed with the programme StatSoft Statistica (Version 12 and 13).

 

The results showed that according to the Kruskal-Wallis tests, correlations could be detected between soil texture and all three microbial parameters. Microbial activity raised in accordance with increasing clay content. It could therefore be verified that although microbiological state and activity of the soil is affected by several environmental factors, FDA and sucrose activity as well as SIR in our samples all depend on the content of clay minerals of the soil, as these can produce favourable conditions for the accumulation of enzymes. This research was funded by TDR project (KEOP-6.3.0/2F/09-2009-0006).

How to cite: Szécsy, O., Rékási, M., Szabó, A., and Szűcs-Vásárhelyi, N.: Correlations between microbial activity and soil texture in Hungarian soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8747, https://doi.org/10.5194/egusphere-egu24-8747, 2024.

Freeze-thaw cycling can influence microbial physiological states including microbial dormancy and resuscitation, and enzyme activities. These factors are essential to the mechanisms that control soil carbon and nutrition dynamics mediated by microbes. Warming-induced thawing may also cause changes in microbial functional diversity and stability. However, it remains a significant challenge to integrate these responses within microbial ecological models, which impedes the precision of carbon-nutrient-climate feedback projections. Here, we depict the dynamics of freezing and thawing soil, as well as the microbial and enzymatic functions in response to freeze-thaw processes within the Microbial-ENzyme Decomposition (MEND) model. The simulation was conducted in the Qingzang alpine grassland with field observations and comprehensive parameterization. Our findings suggest that microbial data potentially enhance confidence in model simulations. We also demonstrate that the relative substrate availability affects the trade-off between enzyme synthesis and metabolic flux. The results can deepen our understanding of microbial acclimation to freeze-thaw cycling and how they respond to soil organic carbon decomposition in permafrost ecosystems. 

How to cite: Qi, S. and Wang, G.: Freeze-thaw processes regulate microbial controls on soil organic carbon decomposition in Qingzang alpine grasslands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9003, https://doi.org/10.5194/egusphere-egu24-9003, 2024.

EGU24-10743 | Orals | SSS4.4

How is microbial metabolic power distributed throughout the soil pore network? 

Naoise Nunan, Maëlle Maestrali, Haotian Wu, Steffen Schwitzer, and Xavier Raynaud

Soil microbial communities live within a complex three dimensional pore network, the properties of which constrains microbial life and activity. The physical structure of soil, and the associated pore network, limit microbial access to resources. It also determines micro-environmental conditions (e.g. redox conditions) that can affect microbial use of the available resources and the rates at which they use energy. Whilst the distributions of different types of activities (CO2 production, enzyme activities) in the pore network have received some attention, the rate at which microbial communities use the energy available to them, i.e. metabolic power, has received little. Energy is required for most aspects of microbial functioning and the rate at which this energy is used determines the extent to microbial functioning proceeds.

Linking the energy available to the rate at which it is processed at the pore scale may help us to better understand how microbial growth and C dynamics are constrained by the physical environment in soil. In order to do so, we collected data from papers in which isotopically-labelled organic substrate was added to pores with different neck diameters and calculated the microbial community catabolic rates, the Gibbs energies of the reactions in oxic and anoxic conditions. This allowed us to estimate the distribution of microbial metabolic power in the pore network and of carbon use efficiency using the approach in LaRowe and Amend (American Journal of Science, Vol. 315, March, 2015,P.167–203, DOI 10.2475/03.2015.01). We then compare the calculations with laboratory measurements of the distribution of carbon use efficiency at the pore scale.

 

How to cite: Nunan, N., Maestrali, M., Wu, H., Schwitzer, S., and Raynaud, X.: How is microbial metabolic power distributed throughout the soil pore network?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10743, https://doi.org/10.5194/egusphere-egu24-10743, 2024.

EGU24-11174 | ECS | Orals | SSS4.4

Linking progressive SOC depletion to degradation of soil structure: Where does it fail first? 

Franziska B. Bucka, Julien Guigue, Christopher Just, Saniv Gupta, Vincent J.M.N.L. Felde, Stephan Peth, and Ingrid Kögel-Knabner

Soil organic carbon (SOC) depletion is often a result of human land use, which is intensified by climate change. As SOC is closely linked to the stabilization of soil structure, the loss of SOC in a soil may induce soil structure breakdown and turnover processes that are not yet well understood.

In order to study soil structure turnover with respect to OC loss, we designed an incubation experiment with soil microcosms that allowed OC loss by leaching and microbial respiration, while avoiding any mechanical disturbance.

We incubated intact soil cores of an arable Luvisol from Loess deposits in southeastern Germany for 300 days at constant water tension and 25 °C to promote microbial activity. During incubation, CO2 release from the microcosms was monitored. A subset of the microcosms was sampled monthly to assess the effect of progressive OC depletion on the stability and architectural features of the soil structure.

The incubation resulted in a reduction of the initial OC (11.2 mg g-1) by approx. 20% and a narrower C:N ratio, corresponding to a reduced OC coverage of the mineral surfaces (1.7 m² g-1 to 0.9 m² g-1, as determined by N2-BET). Despite the OC reduction, the aggregate size distribution (as determined by both wet and dry sieving) did not change significantly, although there was a trend toward a reduction in the mean weight diameter of the aggregates. The mechanical stability of isolated soil aggregates (as determined by dry crushing) even increased slightly with lower OC content in the bulk soil. Microscopic analysis of resin-embedded soil aggregates revealed a lower bulk density in the center, suggesting a progressive carbon depletion from the outside to the inside of the soil aggregates.

These observations highlight that early stage OC depletion along with reduction of OC-covered mineral surface area, without additional mechanical influence, does not immediately lead to the degradation of soil structure. This suggests the existence of OC storage sites that are not susceptible to OC loss by leaching or microbial degradation. In contrast, the sites of initial OC loss may not contribute to the structural stability of a soil.

How to cite: Bucka, F. B., Guigue, J., Just, C., Gupta, S., Felde, V. J. M. N. L., Peth, S., and Kögel-Knabner, I.: Linking progressive SOC depletion to degradation of soil structure: Where does it fail first?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11174, https://doi.org/10.5194/egusphere-egu24-11174, 2024.

EGU24-12707 | Posters on site | SSS4.4

Fire effects on soil structure and hydraulic conductivity 

Markus Berli, Rose M. Shillito, Dani Or, Jeremy J. Giovando, Jay Pak, Nawa Pradhan, René A. Vermeeren, Ian E. Floyd, and Sean McKenna

Fire-induced changes in soil structure and hydraulic conductivity reduce infiltration and increase the likelihood for post-fire flooding and debris flows. Current post-fire hydrology models, however, cannot take fire-induced soil structure changes into account. The goal of this study was to review current understanding of fire-induced changes in soil structure and their post-fire persistence. Specifically, we seek to quantify how fire-induced soil structure changes affect soil hydraulic conductivity.

Changes in soil structure vary widely with the definition of structure. We focused on literature describing fire-induced changes to soil aggregate stability and onset of loss of aggregation followed by formation of surface crust. Generally, aggregate stability tends to increase with increasing soil temperature up to approximately 200°C. Beyond 200˚C, aggregate stability decreases due to changes or loss of soil organic matter (the main binding agent). Evidence suggests that aggregate stability may decrease for soil temperatures as low as 100˚C due to rupture doe to rapid water evaporation within the aggregates. The loss of soil aggregation can promote erosion or formation of surface crust from fine soil particles. Often, fire-induced soil crusts are related to high soil surface temperatures. Literature data show that fire-induced changes in soil structure may persist for a decade after the burn. We developed a conceptual model to describe soil surface structure life cycle in fire-prone ecosystems.

The effects of aggregate deterioration (and recovery) on saturated hydraulic conductivity (Ks) of the soil can be captured by the model of Bonetti et al. (2021). Calculations show that aggregate deterioration leads to a decrease in Ks by a few orders of magnitude (depending on soil texture). Additionally, post-fire soil crusting effects on infiltration were captured by calculating an effective hydraulic conductivity (Rawls et al.,1990) showing a decrease in hydraulic conductivity by one to two orders of magnitude. Moreover, results suggest that fire-induced aggregate deterioration combined with crust formation can reduce the hydraulic conductivity of a soil surface by three to four orders of magnitude. Even without explicit consideration of documented effects of wildfire on soil hydrophobicity, we illustrate the important impact of fire-induced changes in soil structure on infiltration, flooding and debris flow.

How to cite: Berli, M., Shillito, R. M., Or, D., Giovando, J. J., Pak, J., Pradhan, N., Vermeeren, R. A., Floyd, I. E., and McKenna, S.: Fire effects on soil structure and hydraulic conductivity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12707, https://doi.org/10.5194/egusphere-egu24-12707, 2024.

EGU24-14526 | Posters on site | SSS4.4

Effects of Plant Growth-Promoting Rhizobacteria (PGPR) on Saltwater Evaporation: A Case Study Using Bacillus Subtilis 

Yan Jin, Jing Yan, Bridget Knight, and Wenjuan Zheng

Plant growth-promoting rhizobacteria (PGPR) are known for their ability to enhance plant tolerance to abiotic and biotic stresses, including drought and salinity. Additionally, PGPR have been shown to mediate changes in physical properties and hydrological functions of soil. In previous studies, we demonstrated that Bacillus subtilis FB17 (trade name UD1022, a PGPR), could increase soil water retention, preserve continuity of the liquid phase in drying soils, and decrease evaporation. These effects are attributed to production of extracellular polymeric substances (EPS), which are capable of mediating local/micro scale changes in water retention and flow dynamics in soil. We have since extended our study to investigate the potential influence of UD1022 on saltwater evaporation from sand. Specifically, we are comparing evaporation of saltwater, at concentrations 0 (pure water), 10 and 20 ppt, from UD1022-treated sand columns and controls (without treatment). Measurements include temporal changes in cumulative evaporation and evaporation rate, as well as recording surface salt precipitation patterns. Preliminary results from experiments with pure water and 20 ppt saltwater show significant differences in evaporation of pure water between the treated and control columns, however, treatment effects on the evaporation of 20-ppt saltwater were much less pronounced. A preliminary experiment evaluating effects of salt concentration on pellicle formation showed that biofilm formation was suppressed with increasing salinity, presumably, leading to the insignificant effect in reducing evaporation. Nevertheless, images from light and scanning electron microscopes show an earlier onset of salt precipitation on the surface of UD1022-treated sand than control sand, hinting on the potentially very complex interactions between UD1022 and salt precipitation and their effects on evaporation. Additional on-going experiments at lower salt concentrations will allow better mechanistic understanding on how PGPR may mediate changes in salt precipitation and saltwater evaporation in porous media.

How to cite: Jin, Y., Yan, J., Knight, B., and Zheng, W.: Effects of Plant Growth-Promoting Rhizobacteria (PGPR) on Saltwater Evaporation: A Case Study Using Bacillus Subtilis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14526, https://doi.org/10.5194/egusphere-egu24-14526, 2024.

EGU24-15099 | ECS | Orals | SSS4.4

Biological soil crusts regulate evaporation dynamics and energy partitioning over terrestrial surfaces 

Minsu Kim, Milad Aminzadeh, Samuel Bickel, Nima Shokri, and Bettina Weber

Biological soil crusts (hereafter, biocrusts) occurring in drylands modify near-surface soil properties which influences land-atmosphere interactions and exchanges of energy and matter. Yet, the impact of biocrusts on soil evaporation lacks a mechanistic understanding of the biological processes that modify the crusts’ physical properties. We used controlled laboratory experiments, field observations, and mechanistic modelling to determine the impact of biocrusts on evaporation dynamics and subsurface thermal regimes. Our experiments were conducted with bare soil and different types of biocrusts along the ecological succession of the Succulent Karoo desert, South Africa. The preliminary results highlight how different thermal and radiative properties of the crusts affect evaporation rates and heat transfer into the soil layers beneath. Furthermore, active water uptake and storage by biocrust organisms result in water redistribution, which shapes energy balance during diurnal cycles. We conclude from the mechanistic model that biocrusts can accelerate the vertical transport of substrates at the cost of evaporative water loss. Thus, biocrusts may have evolved to modify soil physical properties for balancing nutrient turnover and water usage in global drylands highlighting their crucial roles in regulating mass and energy exchanges over terrestrial surfaces.

How to cite: Kim, M., Aminzadeh, M., Bickel, S., Shokri, N., and Weber, B.: Biological soil crusts regulate evaporation dynamics and energy partitioning over terrestrial surfaces, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15099, https://doi.org/10.5194/egusphere-egu24-15099, 2024.

As an opaque medium, soil conceals processes beneath its surface, posing a challenge for direct observation. To overcome this limitation, scientists employ imaging techniques based on radiation types capable of penetrating the soil, offering insights into its internal structures. While X-ray imaging is the most commonly used method due to its widespread availability, our focus lies on neutron imaging, an alternative and complementary modality.

The distinctive advantage of neutron imaging lies in its heightened sensitivity to light elements, particularly hydrogen, and its greater penetration depth in many metals compared to X-rays. Hydrogen's significance emerges in studying the distribution of water and organic matter within soils. While the spatial and temporal resolution of neutron imaging falls slightly short of laboratory-based X-ray imaging, it operates within the same order of magnitude. Neutron imaging, often flux-limited, has prompted methodological advancements to enable time-series experiments in two and three dimensions on a scale pertinent to soil studies.

Our efforts have concentrated on refining methods for conducting time-sensitive experiments, and we have pioneered the concurrent use of neutron and X-ray imaging. This dual modality approach enhances the reliability of quantitative analysis by leveraging the advantages of images from the two modalities. Quantitative analysis has been a primary focus, leading to the development of correction methods that substantially enhance the accuracy of gravimetric water content quantification based on gray levels in acquired images. The exceptional sensitivity to hydrogen enables the quantification of water content even in unresolved pores, showcasing the primary advantage of neutron imaging. Incorporating advanced denoising techniques further diminishes uncertainties in the results.

Beyond imaging-related innovations, our current endeavors extend to the provision of dedicated sample environments for porous media experiments. This new equipment encompasses balances, pumps, and signal-logging devices integrated into the instrument control system. This integration improves experiment control and facilitates the logging of metadata associated with each image.

In this presentation, we offer a comprehensive overview of applications benefiting from these developments, showcasing the state-of-the-art performance of neutron imaging techniques in porous media research. Our commitment to refining methodologies, advancing quantitative analysis, and providing specialized sample environments underscores our dedication to pushing the boundaries of neutron imaging for a deeper understanding of soil processes.

How to cite: Kaestner, A.: Unveiling Subsurface Secrets: Advances in Neutron Imaging for Soil Research, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15669, https://doi.org/10.5194/egusphere-egu24-15669, 2024.

EGU24-16045 | ECS | Orals | SSS4.4

Effects of mucilage on soil gas diffusion 

Adrian Haupenthal, Patrick Duddek, Mathilde Knott, Andrea Carminati, Hermann Jungkunst, Eva Kroener, and Nicolas Brüggemann

Gas exchange in the soil is determined by the size and connectivity of air-filled pores. Root mucilage can partially reduce air-filled pore connectivity and thus reduce gas diffusivity. However, it remains unclear to what extent mucilage affects soil pore connectivity and tortuosity. The aim of this study was to gain a better understanding of gas diffusion processes in the rhizosphere by explaining the geometric alterations of the soil pore space induced by mucilage.

We quantified the effect of a root mucilage analogue collected from chia seeds without intrinsic respiratory activity on oxygen diffusion at different water contents during wetting-drying cycles in a diffusion chamber experiment. In addition, we used X-ray computed tomography (CT) imaging to visualize the distribution of air and water in the pore space, and quantified the connectivity of the gas phase. Furthermore, we used environmental scanning electron microscopy (ESEM) to visualize mucilage bridges in the dry soil samples.

Quantification of oxygen diffusion showed that mucilage decreased the gas diffusion coefficient in dry soil without affecting air-filled porosity. Without mucilage, a hysteresis in gas diffusion coefficient during a drying-rewetting cycle could be observed for fine sandy soil as well as silt and clay soils. The effect diminished with increasing mucilage content. CT imaging indicated a hysteresis in the connectivity of the gas phase during a drying-rewetting cycle for samples without mucilage. This effect was attenuated with increasing mucilage content. Electron microscopy showed that mucilage forms membrane-like liquid bridges during drying. With increasing mucilage content cylindrical structured are created and at high content interconnected structures are observed throughout the pore space, thereby progressively reducing the connectivity of the gas phase.

Our results suggest that the release of mucilage into the soil may be a plant adaptation strategy to balance soil oxygen availability and water content.

How to cite: Haupenthal, A., Duddek, P., Knott, M., Carminati, A., Jungkunst, H., Kroener, E., and Brüggemann, N.: Effects of mucilage on soil gas diffusion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16045, https://doi.org/10.5194/egusphere-egu24-16045, 2024.

EGU24-16463 | ECS | Orals | SSS4.4

Soil bioturbation – how habitat climatic constraints shape biophysical processes 

Siul Ruiz, Paul Hallett, and Dani Or

Soil bioturbation is the physical movement and alteration of soil by fauna and plants. It plays a central role in soil formation at long time scales and shapes soil structure at hydrologic time scales that affects many soil physical processes and ecosystem services. Varying biomes act as hosts to a variety of ‘ecosystem engineers’ that have developed unique strategies for generating habitats and appreciable soil biopores. For example, earthworms and plant roots generate biopores in moist soil via penetration-expansion (and some ingestion) processes. Other organisms such as ants or termites excavate soil by displacing soil particles with their limbs. We present an overview of biophysical processes associated with soil bioturbation driven by various biological agents and biomechanical  strategies (e.g. penetrators vs excavators). The study highlights the critical role of soil moisture and texture in modulating and shaping the various biomechanical strategies and activity time windows. We explore the implications that regional environmental factors play in locally favoring particular bioturbation processes, which can be used to identify the likelihood of a specific bioturbation agents occurrence in a given region. The overview highlights the relative impact of soil bioturbation on soil structure formation by comparison with conventional tillage processes (restricted to arable lands). Ultimately, this work endeavors to open discussions that can aid in reducing intensive mechanized tillage and help guide sustainable land use initiatives by capitalizing on the biological agents present in the environment.   

How to cite: Ruiz, S., Hallett, P., and Or, D.: Soil bioturbation – how habitat climatic constraints shape biophysical processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16463, https://doi.org/10.5194/egusphere-egu24-16463, 2024.

EGU24-17397 | ECS | Posters on site | SSS4.4

Root hairs facilitate root water uptake across soil textures – a numerical study 

Patrick Duddek, Mutez Ali Ahmed, Mathieu Javaux, Jan Vanderborght, Goran Lovric, Andrew King, and Andrea Carminati

By substantially increasing the surface area of roots available for soil resource capture, root hairs have been hypothesised to facilitate root water uptake, particularly in dry soil conditions. However, existing experimental and computational studies have shown that the effect of root hairs on water uptake cannot be generalised across soils and plant species.

The objective of our study is to investigate to what extent and under which soil conditions root hairs facilitate root water uptake. Ultimately we aim to gain a mechanistic understanding of the effect of root hairs on root water uptake across soil textures.

We scanned maize (Zea Mays L.) roots grown in two soil types (loamy and sandy soil) using synchrotron-based X-ray CT. We utilized an image‐based modelling approach to simulate water flow through the soil-root continuum by solving the flow equations numerically. This approach allowed us to incorporate rhizosphere properties (e.g. root-soil contact) and root hair shrinkage into the image-based model.

Experimental and numerical results show that under dry soil conditions (-1 to -0.1 MPa) root hairs attenuate the gradient in soil matric potential across the rhizosphere. This results in a more effective water extraction compared to a hairless root. Our model revealed that the effect of hairs is determined by soil properties (e.g. soil porosity), root hair traits (e.g. length and density) and the capacity of hairs to remain turgid under drought stress. Compared to densely packed fine textured soils, the effect of hairs is more pronounced in coarse textured soils and loosely packed fine textured soil. This is explained by the steeper hydraulic conductivity curves of these soils.

In conclusion, our results show that the effect of root hairs is determined by root-soil contact, which depends on soil properties, and root hair shrinkage.

How to cite: Duddek, P., Ahmed, M. A., Javaux, M., Vanderborght, J., Lovric, G., King, A., and Carminati, A.: Root hairs facilitate root water uptake across soil textures – a numerical study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17397, https://doi.org/10.5194/egusphere-egu24-17397, 2024.

EGU24-17648 | ECS | Posters on site | SSS4.4

Exploring the interplay of shoot to root hydraulic conductance in varying soil water contents 

Samantha Spinoso Sosa, Benjamin Hafner, Ruth Adamczewski, and Mohsen Zare

Understanding how plants regulate their hydraulic systems in response to varying soil conditions is crucial for comprehending water fluxes in the soil-plant-atmosphere continuum. This study examines hydraulic conductance in maize plants grown in loamy soil under different soil water contents. We hypothesize that plants actively adjust both aboveground and belowground hydraulic conductance in response to soil texture and moisture to balance their water loss with water uptake.

Maize plants were grown in loamy soil with varying moisture levels, simulating optimal and water-stressed conditions. Pre-germinated seeds were planted in PVC pots (10 cm diameter, 24 cm height). At different growth stages (2, 3, 4 and 6 weeks), shoots were delicately separated from the roots. We assessed both total aboveground (Kab) and belowground hydraulic conductance (Kbe). The Kbe was determined by subjecting soil and roots to incremental pressure increases in a pressure pot, collecting the sap to derive water flow at a given pressure. To calculate the total aboveground hydraulic conductance (Kab,tot), effective internal aboveground xylem hydraulic conductance (Kab,xyl), and stomatal conductance (Kab,sto), we measured transpiration, leaf water potential, temperature, and vapor pressure.

In optimal conditions (OC), our initial findings show a linear increase during the initial growth stage in both above- and belowground conductance, followed by deceleration at the late developmental stage. Significantly,  Kbe surpassed  Kab,tot by over two orders of magnitude. It's worth noting that although Kab,xyl displayed a higher magnitude in our measurements, exceeding Kbe , the Kab,sto took precedence as the primary controlling factor when considering the overall soil-plant hydraulics. Under water-stressed conditions, plants exhibited an overall increase in hydraulic conductance with growth, where Kbe once again surpassed Kab,tot by over two orders of magnitude. However,  Kab,tot values were approximately half of those obtained in OC. Notably,  Kab,xyl decreased with plant age but remained greater than  Kbe. These results provide valuable insights into the intricate interplay between root and shoot hydraulic conductance. This research contributes to our understanding of how plants dynamically regulate their hydraulic systems under varying soil conditions, contributing to the broader knowledge of the soil-plant-atmosphere continuum.

How to cite: Spinoso Sosa, S., Hafner, B., Adamczewski, R., and Zare, M.: Exploring the interplay of shoot to root hydraulic conductance in varying soil water contents, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17648, https://doi.org/10.5194/egusphere-egu24-17648, 2024.

EGU24-20510 | Posters on site | SSS4.4

Influence of cropping and fertilization on soil macropore characteristics in a long-term field study 

John Koestel, Jumpei Fukumasu, and David Nimblad-Svensson

It is known that soil organic carbon (SOC) is positively correlated with soil aggregation and total porosity. Similarly simple relationships between SOC content and abundance of pores in specific diameter ranges seem however elusive. In this study, we used X-ray tomography to investigate if this may be explained by treatment-specific differences in biopore forming agents, in other words soil faunal communities and root growth. We therefore compared the pore and biopore network characteristics in the topsoil of an ongoing long-term field experiment in Ultuna, Sweden, which was started in 1956. We selected three contrasting treatments that had led to significantly different SOC contents, ranging from 0.9 to 2.1% in weight, namely: a bare fallow and two cropped plots with two different fertilization treatments, mineral N-fertilizing with Ca(NO3)2 and farm yard manure (FYM). Sixteen undisturbed soil cores were sampled in eight small (ø 22.5 mm; height 65.5 mm) and eight large (ø 65.5 mm; height 74.8 mm) columns from each treatment, respectively (48 samples in total). The results of our study are in line with empirical knowledge that soil treatments associated with increased carbon contents exhibit larger porosities. However, we observed that the abundance and size distribution of biopores at different scales exhibited treatment-specific differences that cannot be explained with SOC content differences alone. Instead, they must have been caused by distinct root morphologies (or complete absence of roots) and/or by differences in soil faunal communities. Our study demonstrates that simple relationships between soil organic matter content and soil macropore network properties must not be taken for granted.

How to cite: Koestel, J., Fukumasu, J., and Nimblad-Svensson, D.: Influence of cropping and fertilization on soil macropore characteristics in a long-term field study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20510, https://doi.org/10.5194/egusphere-egu24-20510, 2024.

EGU24-21045 | ECS | Posters on site | SSS4.4

Meta-analysis of soil pore size distribution and its relationship with various soil properties and land management 

Haotian Wu, Maelle Maestrali, Maik Lucas, Xavier Raynaud, Naoise Nunan, and Steffen Schweizer

The size distribution of soil pores is an important key characteristic of soil systems influencing soil functions such as the cycling of water as well as organic matter storage and dynamics. There is a lack of information about the pore size distribution considering a wide variety of soils and whether various soil characteristics pre-dominantly influence specific pore size ranges. Especially, pores with a diameter < 100 µm serve as a key driver of soil water holding capacity and as a habitat for soil microorganisms involved in the decomposition of organic matter. Here, we aim to contribute to the identification of size patterns in the soil pore size distribution and its relationships with soil biogeochemical matter cycles. In our contribution, we will present insights into our literature-based meta-analysis approach enabling relative comparisons by the integration of pore size distributions across different soils using a water retention curve model. To disentangle the effects of soil texture, soil type, organic matter content, and land management on soil pore size distribution, we used multivariate regression, path analysis, and random forest feature importance. By building a quantitative framework of interrelated controls on soil pore size distribution, we aim to discuss the current understanding of the soil pore network and its ecological functions.

How to cite: Wu, H., Maestrali, M., Lucas, M., Raynaud, X., Nunan, N., and Schweizer, S.: Meta-analysis of soil pore size distribution and its relationship with various soil properties and land management, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21045, https://doi.org/10.5194/egusphere-egu24-21045, 2024.

EGU24-21211 | Orals | SSS4.4

Characterization of soil aggregates in green bioswales in relation to carbon sequestration, aggregate stability, and microbial activity 

Maha Deeb, Peter M. Groffman, Matthew Amato, Zhongqi Cheng, and Daniel Giménez

Green Infrastructure (GI) plays a crucial role in reducing stormwater runoff and providing ecological benefits in urban areas. Aggregation is a key process in many soil functions as it influences carbon storage, greenhouse gas emissions, nutrient cycling, hydraulic properties, and biotic activity. In this study, we investigated soil aggregation processes and stability in GI.

Soil samples were collected from six bioswale sites in New York City that had two different designs - streetside infiltration swales and enhanced tree pits. The soil samples were taken from the inlet, center, and outlet positions (relative to stormwater input) of each site. These samples were then tested for 1) macro and micro aggregate sizes; 2) distribution of soil organic carbon (SOC) and nitrogen; 3) aggregate stability; and 4) microbial biomass and activity relevant to carbon and nitrogen cycles in macroaggregates.

Our results showed that 60% g/g of the soil aggregates at these GI sites were smaller than 2 mm and had high structural stability. Microaggregates between 1-2 mm had the highest SOC and accounted for 60% g/g of all microaggregate size classes. GI aggregates are formed from the breakdown of macroaggregates into intermediate microaggregates. The newly formed microaggregates contained more stable SOC than macroaggregates and bonds within microaggregates were stronger than bonds grouping microaggregates, which is not consistent with a classical model of aggregate formation in natural soils. Microbial biomass and activity were correlated with the carbon and nitrogen content of aggregates and with GI type, allowing for the identification of microbial hot spots. These results suggest that aggregation processes in human-engineered soils included in GI play an important role in sustaining carbon and nitrogen cycles.

How to cite: Deeb, M., Groffman, P. M., Amato, M., Cheng, Z., and Giménez, D.: Characterization of soil aggregates in green bioswales in relation to carbon sequestration, aggregate stability, and microbial activity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21211, https://doi.org/10.5194/egusphere-egu24-21211, 2024.

EGU24-1653 | Orals | SSS4.5

Short-term impact of irrigation on soil microbiome in a Mediterranean maize cropping system 

Carla S. S. Ferreira, Pedro R. Soares, André Pereira, Pedro Mendes-Moreira, and Lyudmyla Symochko

Soil is a complex environment, where microorganisms play a crucial role in the maintenance of soil structure, nutrient cycling and thus soil quality, relevant for croplands productivity. Soil microbial activity, however, is largely determined by water availability, and both are affected by agricultural management. This study aims to investigate the impact of irrigation, i.e. different amount of water and application scheduling, on soil microbial biomass and functional structure of soil microbiome (number of microorganisms in various ecological-trophic groups) in a Mediterranean maize farm. In 2023, six irrigation treatments were applied in a maize farm located in the Mondego Agricultural Valey, centre region of mainland Portugal. The irrigation treatments included three different amounts of water per week applied with drip irrigation: i) 100 mm, the average optimal amount over the last 30 years, based on APSIM crop model), ii) 55 mm, selected to simulate water scarcity conditions, and iii) the amount recommended by the local farmers’ association, based on weekly weather forecast and water balance modelling (ranged between 24 mm and 66 mm over the study period). The water was applied once or split in two applications during the week in different treatments. Each treatment was applied in triplicated plots, each plot covering five maize rows and extending over 10 m length. Nine composite soil samples (0-15 cm depth) per treatment were collected immediately before and after the irrigation period (~ 6 to 17 weeks after sowing). The soil samples were analyzed in sterile conditions using solid growth media: Nutrient Agar, Agar-Agar, Jensens Medium, Soil Agar, and Czapek-Dox Medium. The serial dilutions of the samples were provided until the suspension contained a microorganism titer within the range of 10−3–10−5 CFU/mL. The content of general microbial biomass (Сmic) in the soil was determined using the rehydration method. The results show that after the irrigation period, Cmic increased between 14% to 48%. The number of different nitrogen fixing bacteria and ammonifiers (nitrogen-mineralizing bacteria) increased, whereas the number of micromycetes, spore forming bacteria, oligotrophic, and pedotrophic bacteria groups decreased in all the treatments, which are good indicators about soil quality. Generally, these changes are slightly higher in the treatments where irrigation was applied twice instead of once a week (e.g. 28-31% vs 20-34% increase in nitrogen fixing bacteria, and 33-50% vs 12-36% decrease in oligotrophic bacteria - often associated to nutrient-poor soils). This highlights the relevance of providing a more uniform soil moisture content over the crop season (through smaller amounts of water, applied more often) to support soil microbial communities. Microbial biomass was lowest in plots receiving the less water (55 mm per week), but it was similar between plots receiving 100 mm of water per week and adjusting the amount of water to the recommendations of local farmers’ association. Long term average data would be useful to support decision on the amount of water to apply in areas where technical recommendations are not available. Adequate irrigation management in croplands can support soil biodiversity.

How to cite: Ferreira, C. S. S., Soares, P. R., Pereira, A., Mendes-Moreira, P., and Symochko, L.: Short-term impact of irrigation on soil microbiome in a Mediterranean maize cropping system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1653, https://doi.org/10.5194/egusphere-egu24-1653, 2024.

EGU24-3298 | ECS | Posters on site | SSS4.5

Metagenomic insights into microbial structure and metabolism in alpine permafrost on the Tibetan Plateau 

Luyao Kang, Yutong Song, Rachel Mackelprang, Linwei Wu, and Yuanhe Yang

Permafrost, characterized by its frozen soil, serves as a unique and ecologically significant habitat for diverse microorganisms. Understanding the intricacies of their community structure and functional attributes is crucial for predicting the response of permafrost ecosystems to climate change. However, large-scale evidence regarding microbial profiles and their differences across soil strata remains limited. Here we analyze microbial structure and metabolic potential in permafrost deposits based on 16S rRNA and metagenomic data obtained from a ∼1,000 km permafrost transect on the Tibetan Plateau. We find that microbial communities exhibit apparent discrepancy in structure among soil depth, with a decline in alpha diversity and an increase in spatial variation along soil profile. Microbial assemblages are primarily governed by dispersal limitation and drift, with dispersal limitation being more pronounced in permafrost layer. We also observe that functional genes related to reduction reactions, including nitrate reduction, denitrification, polysulfide reduction, sulfide reduction, tetrathionate reduction, Fe reduction, and methanogenesis, are enriched in the permafrost layer. Taxa involving in redox reactions are more diverse in the permafrost layer and contribute highly to community-level metabolic profiles, reflecting higher redox potential and more complicated trophic strategies for microorganisms in permafrost deposits. These findings provide new insights into the large-scale stratigraphic profiles of microbial community structure and biogeochemical processes and laying the groundwork for future endeavors that elucidate microbial responses to environmental change in permafrost regions.

How to cite: Kang, L., Song, Y., Mackelprang, R., Wu, L., and Yang, Y.: Metagenomic insights into microbial structure and metabolism in alpine permafrost on the Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3298, https://doi.org/10.5194/egusphere-egu24-3298, 2024.

The transition from dry-to-wet soils is often characterized by an acceleration of the nitrogen (N) cycle, representing a period of interest to biogeochemists studying future N cycling responses to global changes. In particular, wetting dry soils can produce large emission pulses of nitric oxide (NO; an air pollutant at high concentrations) and nitrous oxide (N2O; a powerful greenhouse gas), but the mechanisms governing the N losses remain unresolved. The asynchronous timing of when N becomes bioavailable and when ecosystem N sinks activate (e.g., plant N uptake) post wetting has often been used to explain why N is lost when dry soils wet up. However, other factors directly affecting nitrifying communities may also contribute to the emissions. For instance, ammonia oxidizing bacteria (AOB) may be favored over ammonia oxidizing archaea (AOA) in NH4+-rich environments that are typically observed in dry soils. Because AOB may process N less efficiently than AOA, shifts in nitrifier activity may help promote gaseous N losses.

 

To better understand mechanisms for gaseous N loss, we studied drylands in southern California that can experience >6 months without rain, as well as other drylands where we added or excluded precipitation during the dry summer or wet winter seasons. We also selectively inhibited AOA and AOB communities to measure their contributions to soil N emissions. Excluding precipitation during the winter prior to collecting soils did not affect NO emissions, but either adding or excluding precipitation during the summer did; NO emissions after adding extra rainfall (95 ± 6 µg NO g soil-1; p = 0.01) or excluding rainfall (105 ± 22 µg NO g soil-1; p = 0.006) were significantly higher than the control (41 ± 6 µg NO g soil-1), with over 50% of the emissions controlled by AOB. While most of the effects of manipulating precipitation were observed on NO emissions, N2O increased only when we excluded precipitation in the winter wet season, averaging 0.58 ± 0.40 µg N-N2O g soil-1. Using isotopologues of N2O coupled with chloroform fumigations to slow microbial activity, we found that N retention and loss trade off as dry conditions intensify. Altogether, our measurements suggest that that shifts in precipitation patterns can favor AOB-derived NO emissions when dry soils are wetted at the end of the dry season, suggesting that shifts in nitrifier activity from the legacies of past precipitation can also help explain why N is lost when dry soils are wetted.

How to cite: Homyak, P.: Soil nitrogen cycling in dry lands: Precipitation legacy effects on microbial N loss pathways, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4788, https://doi.org/10.5194/egusphere-egu24-4788, 2024.

EGU24-5211 | ECS | Posters on site | SSS4.5

Temperature regulates microbial carbon use efficiency effects on soil organic carbon storage 

Zhaoyang Luo, Jianning Ren, and Simone Fatichi

Microbial carbon use efficiency (CUE), describing the partitioning of microbe assimilated carbon into microbial growth and respiration, is commonly used in soil carbon models to link microbial activities with the consumption of soil organic carbon (SOC). However, the role of CUE in regulating SOC storage remains debated. Previous studies have reported that a higher CUE could not only favour SOC formation through microbial necromass accumulation, but also trigger SOC losses because an enhancement in enzyme production facilitates SOC decomposition. The former leads to a positive relationship between CUE and SOC, while the latter leads to a negative one. Temperature dependencies introduce additional uncertainties while exploring the SOC-CUE relationship since temperature affects both SOC decomposition and CUE. Based on the meta-analysis and numerical simulations with a mechanistic model (T&C), we examined the relationship between CUE, SOC storage and temperature. Numerical results recover the expected SOC storage decrease with increasing temperature when temperature effects are isolated; however, an increase of SOC storage with decreasing CUE is found once temperature effects are discounted, indicating that SOC storage increase with increasing CUE is likely a by-product of temperature dependencies. In addition, we show that CUE variability plays a more important role in affecting SOC storage at lower temperature. Our study helps refine the understanding of SOC responses in a warming climate.

How to cite: Luo, Z., Ren, J., and Fatichi, S.: Temperature regulates microbial carbon use efficiency effects on soil organic carbon storage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5211, https://doi.org/10.5194/egusphere-egu24-5211, 2024.

EGU24-5313 | ECS | Orals | SSS4.5

Context-dependent benefits of ectomycorrhiza on Aleppo pine seedling performance under ecologically relevant settings  

Stav Livne- Luzon, Lior Herol, Tamir Klein, and Hagai Shemesh

Droughts significantly impact forests, with long-term forest existence largely depending on seedling recruitment. However, seedling establishment under natural conditions is often limited by numerous interacting factors such as water availability, competition with herbaceous vegetation, and interaction with ectomycorrhizal fungi (EMF). We performed two greenhouse experiments to examine these factors and their interacting effects on the establishment of Aleppo pine seedlings. In both experiments, Geopora, a genus known to colonize seedlings in dry habitats, predominantly colonized the seedlings' roots, regardless of the EMF inoculum's origin. EMF inoculation enhanced seedling height, biomass, and branch number. However, under combined drought and competition, EMF had no growth impact. When facing competition or consistent water scarcity, EMF's positive effects decreased. Interestingly, during intermittent drought periods (resource pulses), EMF benefits persisted even in severe drought. This discrepancy in pine performance across treatments highlights the complexity of benefits provided to seedlings by EMF under ecologically relevant settings.

 

How to cite: Livne- Luzon, S., Herol, L., Klein, T., and Shemesh, H.: Context-dependent benefits of ectomycorrhiza on Aleppo pine seedling performance under ecologically relevant settings , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5313, https://doi.org/10.5194/egusphere-egu24-5313, 2024.

EGU24-6731 | Orals | SSS4.5 | Highlight

Comprehensive geospatial assessment of the soil microbiome’s response to temperature and moisture in interior Alaska, USA 

Robyn Barbato, Stacey Doherty, Theodore Letcher, Dragos Vas, and Julie Parno

As global temperatures rise, soil fractions of organic matter are being subjected to microbial degradation, particularly in high latitude regions.  Concurrently, permafrost perched below active layer soils is thawing at unprecedented rates, significantly altering landscapes and ecosystem trajectories by changing subsurface conditions and vegetation characteristics. Our aim was to investigate an Alaskan soil microbiome’s response to changes in temperature and water potential because they are well established factors that influence microbial activity and could be predicted using remote sensing data and weather forecasts.  The extent of microbial change in the seasonally thawed active layer remains poorly understood.  To address this, we studied the physical and microbiological properties of two permafrost-affected surface soils in interior Alaska primarily composed of deciduous forests, coniferous forests, and woody wetlands.  We collected soils for laboratory incubation studies where we measured respiration and microbial taxonomy from replicate microcosms experiencing four temperatures and five matric potentials.  Soil respiration rates from the soils varied according to temperature and moisture, with soils exposed to warmer, wetter conditions exhibiting the highest respiration rates (e.g. 0.23 or 0.70 µg C-CO2 g-1 dry soil h-1) and soils exposed to colder, drier conditions exhibiting lower respiration rates (e.g. 0.03 or 0.1 µg C-CO2 g-1 dry soil h-1).   In the field, we measured soil temperature, moisture, and respiration at the sites where the soils were initially collected.  Surface soil temperatures measured at the sites ranged from -25°C in the winter months to +25°C in the summer months.  These values were compared to geospatial estimates of temperature and soil moisture that were used to calculate soil respiration rates.  The estimated respiration values will be compared to field measurements to determine the efficacy of the model.  Additionally, respiration estimates will be calculated under a future climate scenario.  These findings have important implications for developing accurate forecasts of microbial community assemblages during thaw in that location should be considered as a strong influencing factor. 

How to cite: Barbato, R., Doherty, S., Letcher, T., Vas, D., and Parno, J.: Comprehensive geospatial assessment of the soil microbiome’s response to temperature and moisture in interior Alaska, USA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6731, https://doi.org/10.5194/egusphere-egu24-6731, 2024.

Increasing industrial activity has led to a growing risk of cadmium (Cd) accumulations and biomagnifications in plants and humans. Arbuscular mycorrhizal fungi (AMF) have been extensively studied as a soil amendment technique due to their capability to reduce the accumulation of Cd in plant tissues. However, a quantitative and data-based consensus has yet to be reached on the effect of AMF on host plant growth, Cd uptake, and tolerance. Here, a meta-analysis was conducted to quantitatively evaluate the impact of AMF using 2079 individual observations from 157 articles. The research showed that adding AMF to the plants stopped the accumulation of Cd in the shoots and roots and increased biomass, phosphorus (P), and catalase (CAT) in the leaves compared to the control. Yet these effects varied with different mycorrhizal colonization rates, AMF species, plant families and functional types, and soil Cd contents. Mycorrhizal colonization rates positively correlate with changes in biomass and P content in shoots and roots, and CAT and proline in leaves, while showing no significant correlation with Cd concentration in plant tissues. Plants inoculated with Funneliformis caledonium exhibited greater biomass accumulation, while those inoculated with Rhizophagus irregularis showed higher P uptake. Mycorrhizal Legumes demonstrated the most significant reduction in Cd concentration among the plant families, whereas Compositae exhibited the highest increase in biomass, P content, and CAT. In addition, soils with intermediate and high Cd levels were more favorable for AMF to promote plant biomass accumulation. This study shows that AMF can help plants become more resistant to environments with excessive Cd. It also talks about how to manage and use them as bio-inoculants for farming and environmental restoration.

 

 

Acknowledgments

This research received funding from the National Key Research and Development Program of China (No. 2022YFC3701303) and the National Natural Science Foundation of China (Grant Nos. U2344228).

 

How to cite: Tan, Q., Wei, R., Hu, H., and Guo, Q.: Role of arbuscular mycorrhizal fungi behind the plant ameliorated tolerance against cadmium stress: A global meta-analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6946, https://doi.org/10.5194/egusphere-egu24-6946, 2024.

Drought resulting from extended periods of limited precipitation have a substantial impact on soil pH, microbial biomass, and soil derived nutrients for plant growth. A long-term integrated crop, beef, and soil health research project at the Dickinson Research Extension Center is designed around a no-till diverse multi-crop rotation (spring wheat, cover crop, corn, pea-barley, sunflower). In this crop and animal production system, beef cattle graze the pea-barley, corn, and 13-specie cover crop to document microbial, fungal, and nutrient change over time and space. Precipitation during the first five-year crop rotation was normal to slightly above normal. However, the second five-year rotation was drier than normal resulting in nutrient concentration, reduced microbial biomass, and pH decline. Potential nitrogen mineralization of soil organic matter (SOM) in the crop rotation suggests that 8.4 mg N/kg of soil are mineralized for each 1.0% increase in SOM. The mean SOM content of soils in the study is 3.97%. For rain-fed crops, periods of reduced precipitation inhibit soil nutrient solubilization and translocation that negatively impacts a complex system of soil microbial respiration, fungal activity, plant nutrient supply, crop yield, and animal grazing days. The extent of soil drying in 2017 compared to moist soil in 2019 and somewhat drier soil in the 2020 cropping season will be presented. With drying, soil pH declined as soluble salt became more concentrated resulting in a more acidic condition. Naturally, reduced precipitation contributes to minimized plant and root growth, which contributed to reduced SOM content and nitrogen mineralization. For most of the crops in the diverse crop rotation, the percent of microbial active carbon, organic C : N ratio, and organic N : inorganic N ratio declined. Ward Lab Haney Test results for 24-hour microbial respiration provide measurements of microbial community and organismal diversity. Mean microbial biomass under drought conditions (2017), in the crop rotation, was 1,637 ng/g of soil. With the return to normal precipitation (2019) soil microbial biomass was 4,804 ng/g of soil; a 193.5% increase. While total microbial biomass increased with return to normal precipitation in 2019, arbuscular mycorrhizal fungi (AMF) did not reestablish in sunflower, cover crop, corn, and spring wheat-control, and only slight levels of AMF were measured in the pea-barley and spring wheat-rotation crops. Declining soil pH effects mineral nutrient availability among copper, manganese, zinc, and aluminum. At pH levels less than 5 (strongly acidic), aluminum availability becomes toxic to plants. Drought effected soil pH in this integrated systems research declined 9.5% to a mean crop pH value of 5.95, which at this pH level aluminum is sufficiently hydrated to be non-toxic. Return to normal precipitation (2019) increased the crop rotation pH mean to 6.58.

How to cite: Landblom, D., Senturklu, S., and Cihacek, L.: Effect of Drought and Subsequent Precipitation (2016-2020) on Soil pH, Microbial Biomass, and Plant Nutrient Change in the Semi-Arid Region of Western North Dakota, USA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7094, https://doi.org/10.5194/egusphere-egu24-7094, 2024.

A large amount of research has demonstrated that global warming leads to changes in the structure and function of soil microbial communities. Despite the large number of studies which have identified soil microbes as key drivers of biogeochemical processes, little is known about the trade-offs between soil microbial activities under environmental change and how this will affect soil biogeochemistry.

To this end, we currently develop high throughput methodology to measure growth, respiration, extracellular polymeric substance (EPS), extracellular enzyme activity (EEA) and carbon use efficiency (CUE) in pure cultures of a wide range of bacterial isolates. In response to resource quality (concentration, lability, stoichiometry), temperature and oxygen stress, we will assess trade-offs between key microbial catabolic and anabolic processes. The methodology will finally be applied to soils collected from the Achenkirch forest warming experiment in Austria to examine how complex communities and isolates from long-term warming and control soils express trait trade-offs. Isolates will be selected and checked to cover the most actively growing microbes in control and warmed soils using the qSIP method. The purpose of this study is to gain a deeper understanding of the anabolic and catabolic transitions of soil microbes under the influence of warming and, consequently, to predict the potential biogeochemical impacts of long-term warming on forest soils.

How to cite: Li, Y., Li, T., A. Eichorst, S., A. Anthony, M., and Wanek, W.: Trade-offs between growth, carbon use efficiency, and the production of extracellular polymeric substance and soil enzymes of soil microbes under long-term warming with different resource complexities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7945, https://doi.org/10.5194/egusphere-egu24-7945, 2024.

EGU24-8012 | ECS | Posters on site | SSS4.5

Continental-scale β diversity of bacteria and fungi vary differentially with soil pH in forests 

Changjiang Huang and Xuhui Zhou

Abstract:  The soil microbiota is crucial for regulating biogeochemical cycles, including soil carbon (C) dynamics and nutrient cycling. However, how climate, plants, and soil properties influence the microbiome in forests at a continental scale remains unclear, hampering us from better understanding forest C-climate change feedback. Here, we investigated the spatial patterns of microbial diversity across China’s forests and explored the factors controlling microbial β diversity and network complexity. Our results showed that bacterial and fungal β diversity were strongly influenced by soil pH and climate. To further investigate the environmental preference of the microbial networks, we classified the zero-radius operational taxonomic units (zOTUs) into five groups ranging from acidic to alkaline soils. Co-occurrence network analysis revealed that the topological structure of the bacterial network (e.g., edge and degree) increased with pH and had a negative relationship with β diversity but not with fungal diversity. Soil fungi exhibit greater β diversity with network complexity (i.e., degree and betweenness) than bacteria at pH < 5.1 and vice versa in neutral and alkaline soils (pH > 5.5). Within the pH range of 5.1-5.5, the bacteria-fungi network exhibited the most increased network complexity but the lowest fungal β diversity, with significant positive correlations found between fungal β diversity and soil properties. Furthermore, 46 bacterial core species were identified and shown to be significantly correlated with soil pH. These findings highlight the critical role of soil pH in driving soil microbial β diversity across China’s forests and reveal the effects of pH thresholds on changes in the soil microbial network and core species.

Keywords: Bacterial diversity, fungal diversity, network analysis, forest 

How to cite: Huang, C. and Zhou, X.: Continental-scale β diversity of bacteria and fungi vary differentially with soil pH in forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8012, https://doi.org/10.5194/egusphere-egu24-8012, 2024.

EGU24-15868 | ECS | Orals | SSS4.5 | Highlight

Drought intensity shapes legacy effects on grassland plant and soil microbial communities and their response to a subsequent drought 

Natalie J. Oram, Nadine Praeg, Richard D. Bardgett, Fiona Brennan, Tancredi Caruso, Paul Illmer, Johannes Ingrisch, and Michael Bahn

Drought has long-lasting legacy effects on grassland ecosystem functioning, which can manifest as shifts in soil microbial community structure and function and plant productivity that persist long after a drought passes. Increasing drought intensity causes abrupt shifts in plant productivity, plant-soil carbon and nitrogen dynamics, and soil microbial communities. However, very little is known about the role that drought intensity plays in the formation of drought legacies, and in plant and microbial responses to a subsequent drought. In a two-year experiment, we studied soil legacies associated with drought intensity in two model grassland plant communities with contrasting resource acquisition strategies (i.e., a fast- and a slow-strategy community). In the first year of the experiment, communities experienced a gradient of increasing drought intensity from well-watered to severely drought-stressed. In the second year, we determined soil microbial community composition and function, and plant community above-ground biomass in response to a subsequent drought. We found that the drought in the first year affected soil prokaryote and fungal community composition, microbial network structure, and soil function in the following growing season, and these effects were dependent on the past drought’s intensity. Soil drought legacy effects significantly altered plant community resilience to the subsequent drought: increasing intensity of the initial drought reduced plant community productivity resistance in slow-strategy plant communities, and decreased productivity overshoot seven weeks after re-wetting in fast-strategy plant communities. Our study shows that drought intensity causes distinct legacies in soil microbial community composition and function and alters the resilience of plant productivity to subsequent drought.

How to cite: Oram, N. J., Praeg, N., Bardgett, R. D., Brennan, F., Caruso, T., Illmer, P., Ingrisch, J., and Bahn, M.: Drought intensity shapes legacy effects on grassland plant and soil microbial communities and their response to a subsequent drought, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15868, https://doi.org/10.5194/egusphere-egu24-15868, 2024.

EGU24-16307 | Orals | SSS4.5 | Highlight

Land use intensity has a stronger effect on the temperature sensitivity of soil microbial carbon cycling processes than long-term climate change. 

Luiz Domeignoz-Horta, Matthew McLaughlin, Marcelo Soares Fontes, David Sebag, Marie-Liesse Aubertin, Eric Verrecchia, Ansgar Kahmen, Daniel Nelson, Anna-Liisa Laine, Pascal Niklaus, Klaus Butterbach-Bahl, and Ralf Kiese

Microbes are responsible for the cycling of carbon (C) in soils, and predicted changes in soil C stocks under climate change are highly sensitive to shifts in the mechanisms thought to control microbial physiological response to warming. Two mechanisms have been proposed to explain the long-term effects of warming on microbial physiology: microbial thermal acclimation and changes in the quantity and quality of substrates available for microbial metabolism. However, studies disentangling these two mechanisms and assessing how land use affects them are lacking. To disentangle the drivers of changes in microbial physiology in response to long-term climate change, we sampled soils from a 10-year old global change and land use intensity experiment at the Pre-Alpine Terrestrial Environmental Observatories (TERENO project). The global change treatment includes a warming of 2oC and a reduction in precipitation of about 450 mm. We took soil samples at different time-points during the spring season and depths. We performed short-term laboratory incubations over a range of temperatures to measure the relationships between temperature sensitivity of physiology (growth, respiration, carbon use efficiency with the 18O-H2O method) and we characterized the quantity and quality of soil organic matter with the ramped thermal rock-eval pyrolysis at different depths. In this ongoing project, we did not observe thermal acclimation of microbial respiration, growth or CUE to climate change. However, fertilization had the strongest effect on the temperature sensitivity of microbial respiration. In the next steps of this project, we will determine whether climate change and/or land use intensity has an effect on soil organic carbon fractions with different residence times. Our preliminary results show that land use intensity has an overriding effect on the temperature sensitivity of microbial processes compared to long-term climate change.

How to cite: Domeignoz-Horta, L., McLaughlin, M., Soares Fontes, M., Sebag, D., Aubertin, M.-L., Verrecchia, E., Kahmen, A., Nelson, D., Laine, A.-L., Niklaus, P., Butterbach-Bahl, K., and Kiese, R.: Land use intensity has a stronger effect on the temperature sensitivity of soil microbial carbon cycling processes than long-term climate change., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16307, https://doi.org/10.5194/egusphere-egu24-16307, 2024.

EGU24-18381 | ECS | Orals | SSS4.5

Cropping system modulates the effect of drought on ammonia-oxidizing communities 

Ari Fina Bintarti, Elena Kost, Dominika Kundel, Rafaela Feola Conz, Paul Mäder, Hans-Martin Krause, Jochen Mayer, Martin Hartmann, and Laurent Philippot

The severity of drought is predicted to increase across Europe due to climate change. Droughts can substantially impact terrestrial nitrogen (N) cycling and the corresponding microbial communities. Here, we investigated how ammonia-oxidizing bacteria (AOB), archaea (AOA), and comammox (complete ammonia oxidizers) respond to simulated drought in a rain-out shelter experiment in the DOK long-term field trial comparing different organic and conventional agricultural practices since 1978. This study is part of the MICROSERVICES (BiodivERsA) project aiming to understand and predict the effects of climate change on crop-associated microbiomes and their ecosystem functions. We monitored the diversity, the composition, and the abundance of ammonia-oxidizers for five months by Illumina-based amplicon sequencing and quantitative real-time PCR using the amoA gene as molecular marker.

We found that the effect of drought varied depending on the ammonia-oxidizing community and also on the agricultural practices. The community structures of AOA and comammox were more strongly affected by drought than the AOB community structure. Drought also had a stronger impact on the community structure in the biodynamic (organic) cropping system than in both the mixed and mineral-fertilized conventional systems. The abundance of ammonia oxidizers was also influenced by drought, with comammox clade B exhibiting the strongest sensitivity to drought. The drought effect on the community abundance was more prominent in the biodynamic and mixed-conventional systems than in the mineral-fertilized conventional system. We further found a significant interaction between drought and agricultural practices on the abundance of all groups of ammonia-oxidizers except AOB. Overall, our study showed that the impact of drought on ammonia oxidizers was modulated by agricultural practices and varied with time as well as among members of ammonia-oxidizers. These results underscore the significance of agricultural management practices in influencing the response of nitrogen cycling and the corresponding communities to drought.

How to cite: Bintarti, A. F., Kost, E., Kundel, D., Conz, R. F., Mäder, P., Krause, H.-M., Mayer, J., Hartmann, M., and Philippot, L.: Cropping system modulates the effect of drought on ammonia-oxidizing communities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18381, https://doi.org/10.5194/egusphere-egu24-18381, 2024.

EGU24-19061 | ECS | Posters on site | SSS4.5

Effects of elevated CO2 on soil microbial communities in a tropical understory forest in the Central Amazon 

Crisvaldo Souza, Lucia Fuchslueger, Nathielly Pires Martins, Iokanam Sales Pereira, Alacimar Viana Guedes, Bruno Takeshi Tanaka Portela, Maria Pires Martins, Juliane G. Menezes, Joana Séneca, Sabrina Garcia, Amanda Rayane Macambira Damasceno, Alberto Vicentini, David M. Lapola, and Carlos Alberto Quesada

Soil microbial communities are central to understanding interactions between soil and climate change by controlling  major carbon and nutrient fluxes, such as organic matter formation and decomposition. In addition, soil microbial communities respond sensitively to climate change and  can control the magnitude and direction of potential soil feedback to climate.

Tropical forests have a crucial role as carbon sink to reduce elevated atmospheric CO2 (eCO2), but they rely on soil microbial communities to access nutrients from organic matter. However, especially in tropical areas, the effects of increasing atmospheric CO2 on soil microbial community composition are still not fully understood. Studies, primarily conducted in temperate regions, demonstrate that eCO2 concentrations can cause changes in the structure and activity of soil microbial communities responsible for decomposing organic matter. Additionally, the richness of some microorganism species is relatively sensitive and decrease under eCO2, potentially leading to changes in the abundance of specific microbial taxa. Consequently, this could change nutrient mineralization rates, affecting primary production rates, and subsequently plant organic matter quality and inputs to soil.

Here we used an Open-Top Chamber (OTC) experiment to expose the understory vegetation in a tropical lowland forest to eCO2 (+200 ppm above ambient), and tested the impacts of eCO2 on soil microbial (fungal, bacterial, and archaeal) community structure using 16SrRNA amplicon sequencing. Two soil collections were conducted in eight OTCs (four eCO2 and four ambient control OTCs), in September 2019 before the CO2 increase and in September 2021 after two years of CO2 increment. Our results showed a significant decrease in microbial biomass carbon and phosphorus pools in response to eCO2 and a strong tendency of decreased DNA concentrations corroborating a potential decrease in soil microbial biomass. In addition, our data will provide insights in the diversity of microorganisms in Amazonian soil, and allow to better understand soil microbial community responses and feedbacks of tropical forests to eCO2 and consequences for soil carbon and nutrient cycling.

How to cite: Souza, C., Fuchslueger, L., Pires Martins, N., Sales Pereira, I., Viana Guedes, A., Tanaka Portela, B. T., Pires Martins, M., Menezes, J. G., Séneca, J., Garcia, S., Macambira Damasceno, A. R., Vicentini, A., Lapola, D. M., and Quesada, C. A.: Effects of elevated CO2 on soil microbial communities in a tropical understory forest in the Central Amazon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19061, https://doi.org/10.5194/egusphere-egu24-19061, 2024.

EGU24-19132 | ECS | Orals | SSS4.5

Microbial growth in a warming Arctic: Exploring controls and temperature responses in permafrost soils 

Cornelia Rottensteiner, Victoria Martin, Alberto Canarini, Hannes Schmidt, Leila Jensen, Julia Horak, Moritz Mohrlok, Carolina Urbina Malo, Willeke A'Campo, Luca Durstewitz, Julia Wagner, Rachele Lodi, Niek Speetjens, George Tanski, Michael Fritz, Hugues Lantuit, Gustaf Hugelius, and Andreas Richter

Permafrost soils are particularly vulnerable to climate warming. With ~1,500 Gt Carbon (C), they store a significant proportion of global soil C. Organic matter that was frozen and thus unavailable for microbial decomposition for millennia, is now thawing. How much of this permafrost C is decomposed will be determined by microbial activities and the partitioning of assimilated C to microbial growth (potential C stabilization) or microbial respiration (C loss). Our current knowledge on the controls of microbial growth and respiration in permafrost soils is, however, limited.

The objective of this study was to analyze microbial growth and respiration in permafrost soils and to explore soil organic matter composition, microbial community composition and various soil parameters as potential drivers. We collected 81 soil samples from four soil layers (organic, mineral, cryoturbated, permafrost) and three lowland tundra polygon types (low-center, flat-center, high-center) in Arctic Canada. We used pyrolysis-GC-MS fingerprinting to characterize soil organic matter composition and amplicon sequencing (16S, ITS1) to identify archaeal, bacterial, and fungal community composition. Temperature responses (Q10) were analyzed in an 8-week laboratory incubation experiment, subjecting soil aliquots to 4 °C and 14 °C. Microbial growth was determined by 18O-H2O-incorporation into DNA and microbial respiration by gas analysis.

Soil organic matter composition differed between soil layers along a gradient of degradation and C content. Organic matter complexity and diversity decreased with the level of decomposition. We found distinct soil organic matter composition for each polygon type, including all soil layers, suggesting different decomposition pathways, induced by differences in vegetation and soil water regime. Anoxic conditions in low-center polygons resulted in more archaea and distinct fungal communities. Microbial community composition differed among all soil layers, with particularly more fungi in organic soils. Microbial mass-specific growth and respiration differed among polygons and soil layers, and both increased with warming. Overall, temperature responses (Q10) were higher for respiration than for growth, implying that microbes are less efficient in using C for growth. Linear mixed effect models revealed that soil organic matter composition and microbial community composition were good predictors for mass-specific growth at field and warmed conditions. Mass-specific respiration was best explained by microbial community composition. Our predictors, however, did not explain the temperature responses.

Our results indicate that under warming, microbes allocated more C to respiration, leading to increased greenhouse gas emissions per unit of carbon taken up. We found these results while including all soil layers and polygon types, suggesting these responses to be representative for lowland Arctic ecosystems. Moreover, we could show that organic matter composition and microbial community composition are good predictors for microbial growth and respiration, thus deserving more attention in future studies.

This study is part of the EU H2020 project “Nunataryuk”.

How to cite: Rottensteiner, C., Martin, V., Canarini, A., Schmidt, H., Jensen, L., Horak, J., Mohrlok, M., Urbina Malo, C., A'Campo, W., Durstewitz, L., Wagner, J., Lodi, R., Speetjens, N., Tanski, G., Fritz, M., Lantuit, H., Hugelius, G., and Richter, A.: Microbial growth in a warming Arctic: Exploring controls and temperature responses in permafrost soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19132, https://doi.org/10.5194/egusphere-egu24-19132, 2024.

EGU24-19328 | ECS | Posters on site | SSS4.5

Disentangling the impacts of soil management practices on nitrogen mineralization and inorganic nitrogen accumulation during soil drying events 

Eduardo Vázquez, Nikola Teutscherová, and Marta Benito

The biogeochemical cycling of nitrogen (N) in drylands ecosystems depends strongly on the alternance dry-wet cycles caused by seasonal nature of rainfall pulses. While during the dry periods the soil organic matter (SOM) mineralization is limited and inorganic N (Ninorg) is accumulated in soil because the low diffusion of ions and low N uptake by plant and microbes, the rewetting enhances the diffusion of ions and causes a pulse of N transformations and N2O emissions. Therefore, the understanding of the processes involved in the accumulation of Ninorg is crucial. In this study we combined a field and a laboratory study to disentangle the role of soil management practices on N mineralization and Ninorg accumulation in soils under drought conditions in Spain. First, we evaluated the N mineralization and Ninorg accumulation during summer fallow in a full-factorial field experiment comparing the effect of tillage (no-tillage (NT) vs traditional tillage (TT)) and liming. Second, we performed a soil drying experiment under controlled conditions using soil from the same field experiment to distinguish the impacts of management practices via changes in soil biogeochemical properties (mainly soil organic matter (SOM) and pH) and via soil microenvironmental conditions (soil water availability and temperature).

In the field experiment, Ninorg was accumulated in soils along the summer fallow (from May to July) while the evaluated enzymatic activities (β-glucosaminidase, Leucine aminopeptidase, BAA protease, Casein protease, L-glutaminase and Urease) and the abundance of chiA, pepA and apr genes were significantly reduced during the summer fallow. We observed a significant and positive interaction between NT and liming in the accumulation of Ninorg which may suggest higher risk of N losses upon rewetting. The higher Ninorg accumulation is linked to a similar synergistic effect of both practices on the activity of L-Asparaginase, L-glutaminase and Urease. The higher SOM, pH and less extreme microenvironmental conditions observed in soils managed by NT and liming can explain this synergistic effect. No effect of the treatments in the abundance of the evaluated genes was observed. In the soil drying experiment under controlled conditions where the differences caused by the microenvironmental conditions were excluded, we observed a positive effect of NT and liming on Ninorg accumulation along the drying experiment (29 days of drying). However, no interaction between NT and liming on the Ninorg accumulation was observed. This suggest that the synergistic effect observed in the field experiment was caused by the microenvironmental conditions rather than by changes in biogeochemical properties. Similar circumstance was observed in the analyzed enzymatic activities and chiA abundance (positive effect of NT and liming but without synergistic response) confirming the previous observation. In summary, our results suggest that the combination of NT and liming increases synergistically the accumulation of Ninorg in soil during summer fallow because of their positive effect on soil microenvironmental conditions rather than on soil biogeochemical properties

How to cite: Vázquez, E., Teutscherová, N., and Benito, M.: Disentangling the impacts of soil management practices on nitrogen mineralization and inorganic nitrogen accumulation during soil drying events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19328, https://doi.org/10.5194/egusphere-egu24-19328, 2024.

EGU24-20534 | Posters on site | SSS4.5

Cover crop diversification alters microbial life-death cycle and enhances carbon sequestration in agricultural soil 

Alexander König, Christoph Rosinger, Katharina Keiblinger, Sophie Zechmeister-Boltenstern, Anke Herrmann, and Erich Inselsbacher

Sequestering atmospheric CO2 within soil organic matter via shifts in agricultural practices represents a compelling strategy for enhancing soil ecosystem services and mitigating global change. Traditionally, the perception of soil carbon (C) stability is focused on intrinsic characteristics of organic matter inputs, such as lignin content. However, recent studies challenge this perspective, proposing a more effective approach centered on managing how the soil microbiome processes C inputs (Sokol et al., 2019; Poeplau et al., 2019).

This shift prompts an exploration into the intricate connection between aboveground plant communities and belowground diversity of the microbiome, as well as the associated metabolic processes governing C sequestration. Building on this, Lehmann et al. (2020) presented a theoretical framework that interprets the persistence of C in soil as a consequence of interactions between the molecular variability of organic matter input and the spatio-temporal microbial heterogeneities within the soil system. This perspective underscores the need for a comprehensive understanding of the dynamic interplay shaping C sequestration, moving beyond static views of organic matter stability.

Therefore, within the EnergyLink framework various microbial markers were investigated to shed light on potential physiological changes at a microbial level across several European agricultural field sites with different cover crop management types. Specifically, to discern shifts in microbial necromass composition and quantity, we focused on amino sugars (galactosamin, gluctosamine, mannosamine and muramic acid). To evaluate effects on potential growth rates, we quantified 14C incorporation into ergosterol for fungi and 14C-leucine incorporation for bacteria. Comprehending changes in uptake strategies, we examined extracellular enzyme activities for different nutrient classes. Additionally, we determined C:N:P ratio for bulk soil and microbial biomass. Here we present first results and discuss implications of diversified cover crops on soil carbon properties.

How to cite: König, A., Rosinger, C., Keiblinger, K., Zechmeister-Boltenstern, S., Herrmann, A., and Inselsbacher, E.: Cover crop diversification alters microbial life-death cycle and enhances carbon sequestration in agricultural soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20534, https://doi.org/10.5194/egusphere-egu24-20534, 2024.

EGU24-197 | ECS | Orals | BG3.23

Non-living respiration: another breath in the soil 

Clémentin Bouquet, Benoit Keraval, Gaël Alvarez, Mounir Traïkia, Fanny Perrière, Sandrine Revaillot, Anne-Hélène Le Jeune, Hermine Billard, Sébastien Fontaine, and Anne-Catherine Lehours

Containing about three times more carbon (C) than the atmosphere (600-800 PgC) or the Earth’s vegetation, soils are crucial C pools for climate change mitigation. The CO2 flux (~110 PgC yr1) from soils is the largest terrestrial C source to the atmosphere and is about ten times the annual emissions from burning fossil fuels (IPCC 2021). A small change in soil CO2 flux can significantly alter the atmospheric CO2 concentrationand potentially amplify global warming.A complete and reliable identification of soil processes likely to affect soil C balance and CO2 flux is essential to predict future atmospheric CO2 concentrations.

The current scientific consensus is that the dominant component of the soil CO2 flux is heterotrophic microbial respiration. However, this paradigm is challenged by recurrent observations of substantial and persistent CO2 emissions in soil microcosms where sterilization treatments (e.g. γ-irradiations) reduced microbial activities to an undetectable level. To address this shortcoming, we postulated that non-cellular respiratory pathways in soils are capable of performing the complete oxidation of organic matter to CO2. This hypothesis was enhanced (i) by the detection of an isotopic signature of soil CO2 flux (δ13C-CO2 up to −75.4 ± 2.8 ‰) incompatible with a cell-derived respiration and (ii) by the release of 13C-CO2 in sterilized soils supplied with 13C-glucose (Maire et al. 2013; Kéraval et al. 2016; 2018).

Overall our work highlights that non-cellular respiration accounts for 16 to 48 % of CO2 fluxes from sterilized soils worldwide with contrasted physical and chemical properties. We have also demonstrated that sterilized soils have a high and persistent potential for electron transfer and form self-sustaining systems that can maintain CO2 emissions for more than 6 years without external input. Furthermore, untargeted metabolite profiling carried out using proton nuclear magnetic resonance (1H NMR) spectroscopy revealed that non-living soils have an orderly exometabolome dynamics supporting the idea that non-stochastic scenarios mimicking biochemical transformations (i.e. Krebs cycle, fermentation) occurred in sterilized soils (Bouquet, Keraval et al. in prep).

  • Maire, V. et al, 2013. An unknown oxidative metabolism substantially contributes to soil CO2emissions, Biogeosciences, 10, 1155–1167, https://doi.org/10.5194/bg-10-1155-2013,
  • Kéraval, B., et al, 2016. Soil carbon dioxide emissions controlled by an extracellular oxidative metabolism identifiable by its isotope signature, Biogeosciences, 13, 6353–6362, https://doi.org/10.5194/bg-13-6353-2016, 2016
  • Kéraval, B. et al, 2018. Cellular and non-cellular mineralization of organic carbon in soils with contrasted physicochemical properties. Soil Biol. Biochem. 125, 286–289. doi:10.1016/j. soilbio.2018.07.02
  • Bouquet, C., et al. in prep. Non-living respiration : another breath in the soil

How to cite: Bouquet, C., Keraval, B., Alvarez, G., Traïkia, M., Perrière, F., Revaillot, S., Le Jeune, A.-H., Billard, H., Fontaine, S., and Lehours, A.-C.: Non-living respiration: another breath in the soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-197, https://doi.org/10.5194/egusphere-egu24-197, 2024.

EGU24-2201 | ECS | Orals | BG3.23

An innovative soil mesocosm system for studying the effect of soil moisture and background NO contribution on soil surface trace gas fluxes  

Logapragasan Subramaniam, Florian Engelsberger, Benjamin Wolf, Michael Dannenmann, and Klaus Butterbach-bahl

This research investigates the complex dynamics of how soil NO concentrations and soil moisture affect the exchange of greenhouse gases between soils and the atmosphere. To this end, we have developed and tested an automated soil mesocosm system (AU-MES), which allows for dynamically change of headspace and soil NO concentrations, measures trace and greenhouse gas fluxes based on a dynamic chamber approach, and observes and manipulates key soil and environmental metrics such as temperature, light conditions, or moisture.

Initial a brief phase of soil-only incubation experiments demonstrated the influence of soil moisture and soil and headspace NO concentrations of 400 ppbv on gas emissions. We observed that under low soil moisture conditions (30% water-filled pore space), nitrification was favored, as indicated by increased emissions of NO (at zero NO concentration 0.191 kg N ha-1 and at high NO concentration 0.180 kg N ha-1) and NO2 (at zero NO concentration 0.002 kg N ha-1 and at high NO concentration 0.001 kg N ha-1). In contrast, under higher soil moisture conditions (50% water-filled pore space), we observed increased N2O (at zero NO concentration 0.149 kg N ha-1and at high NO concentration 0.147 kg N ha-1) and CO2 (at zero NO concentration 0.122 t C ha-1 and at high NO concentration 0.110 t C ha-1)fluxes, suggesting that denitrification may become more important. These results, particularly under soil rewetting and fertilizer application, illustrate the complex interplay between soil nitric oxide concentrations, moisture levels, microbial activities, and gas emissions.

In summary, the AU-MES system is a valuable tool for investigating soil-atmosphere gas interactions and the effects of various environmental elements on these processes. Our research provides important insights into how nitric oxide may affect soil processes and trace gas exchange at the soil-atmosphere interface.

Keywords
Automated soil mesocosm system, nitric oxide, gas concentrations, headspace purging, soil purging

How to cite: Subramaniam, L., Engelsberger, F., Wolf, B., Dannenmann, M., and Butterbach-bahl, K.: An innovative soil mesocosm system for studying the effect of soil moisture and background NO contribution on soil surface trace gas fluxes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2201, https://doi.org/10.5194/egusphere-egu24-2201, 2024.

EGU24-2971 | ECS | Posters on site | BG3.23

Viral lifestyles modulate prokaryotic community structure and function in thermokarst lakes 

Yutong Song and Yuanhe Yang

Microbes determine the fate of carbon (C) and nitrogen (N) released by rapidly thawing permafrost, with viruses that infect them mediating this process via lysis and metabolic reprogramming. However, little is known about whether and how viruses with different lifestyles modulate microbial community and ecological functions, particularly in thermokarst lakes where studies for viruses were pretty scarce. Here, we conducted metagenome deep sequencing on sediment samples obtained from 60 thermokarst lakes along a 1,100 km permafrost transect, and recovered 4,161 viral and 2,805 microbial genomes from above 3 Tb data, as well as predicted their interactions and functions. We found that viral lifestyles were coupled with microbial life-history strategies along nutrient gradients. Virus-host interactions were more specialized in temperate viruses dominant samples than those in virulent viruses prevailing samples. Further functional predictions revealed that virus-encoded auxiliary metabolic genes (AMGs) exhibited more diverse and higher abundance in virulent viruses dominant community than those in temperate viruses predominant community. What count was that viruses could reduce methane (CH4) emissions from thermokarst lakes via virus-encoded mmoB genes. Overall, these findings highlight the crucial impact of viral life-history strategies on microbial community and key ecosystem function in climate-sensitive thermokarst habitats.

How to cite: Song, Y. and Yang, Y.: Viral lifestyles modulate prokaryotic community structure and function in thermokarst lakes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2971, https://doi.org/10.5194/egusphere-egu24-2971, 2024.

EGU24-4353 | Orals | BG3.23

Soil microsites controls N2O production and emission in undisturbed soils 

Zhifeng Yan and Baoxuan Chang

Soil structures regulate the production and emission of N2O from soils mainly through influencing substrate availability and gas diffusion. However, the respective impacts of substrate availability and gas diffusion and their response to moisture changes remain elusive. This study conducted laboratory incubation experiments with disturbed (sieved) and undisturbed (intact) soil cores under different soil moisture levels (i.e., 40, 60, 80 and 100% water filled pore space (WPFS)). Soil N2O fluxes were continuously monitored over a 21-day incubation period, during which O2 concentration profile was occasionally measured and relative soil gas diffusivity was measured at the end of experiments. The results show that the N2O fluxes from the disturbed soil cores were 2~25 times higher, respectively, than those from undisturbed cores, which are similar to field observations. Nevertheless, the difference in the relative soil gas diffusivity between them was not obvious, especially under high moisture conditions. Therefore, the overestimated soil N2O emission from sieved soil experiments was attributed to increased C availability caused by disturbance rather than changes in gas diffusivity. Additional incubation experiments with 15N tracing further demonstrated the key impacts of soil microsites on N2O production and emission. Overall, this study highlighted the physical protection of soil microsites on carbon sequestration and N2O mitigation.

How to cite: Yan, Z. and Chang, B.: Soil microsites controls N2O production and emission in undisturbed soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4353, https://doi.org/10.5194/egusphere-egu24-4353, 2024.

Global warming can significantly impact soil CH4 uptake in subtropical forests due to changes in soil moisture, temperature sensitivity of methane-oxidizing bacteria (MOB), and shifts in microbial communities. However, the specific effects of climate warming and the underlying mechanisms on soil CH4 uptake at different soil depths remain poorly understood. To address this knowledge gap, we conducted a soil warming experiment (+4°C) in a natural forest. From August 2020 to October 2021, we measured soil temperature, soil moisture, and CH4 uptake rates at four different soil depths: 0-10 cm, 10-20 cm, 20-40 cm, and 40-60 cm. Additionally, we assessed the soil MOB community structure and pmoA gene (with qPCR) at the 0-20 cm depth. Our findings revealed that warming significantly enhanced soil net CH4 uptake rate by 12.28%, 29.51%, and 61.05% in the 0-10, 20-40, and 40-60 cm soil layers, respectively. The warming also led to reduced soil moisture levels, with more pronounced reductions observed at the 20-40 cm depth compared to the 0-20 cm depth. At the 0-10 cm depth, warming increased the relative abundance of upland soil cluster α and decreased the relative abundance of Methylocystis, but it did not significantly increase the pmoA gene copies. Our structural equation model indicated that warming directly regulated soil CH4 uptake rate through the decrease in soil moisture, rather than through changes in the pmoA gene and MOB community structure at the 0-20 cm depth. In summary, our results demonstrate that warming enhances soil CH4 uptake at different depths, with soil moisture playing a crucial role in this process. Under warming conditions, the drier soil pores allow for better O2 and CH4 penetration, thereby promoting more efficient activity of MOB. This increased CH4 uptake in subtropical forests has the potential to mitigate the effects of global warming.

How to cite: Zhang, L., Lin, W., and Guo, J.: Exploring the impact of soil warming on methane uptake at different soil depths in a subtropical forest: unraveling the role of decreased water content, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4918, https://doi.org/10.5194/egusphere-egu24-4918, 2024.

EGU24-5323 | ECS | Orals | BG3.23

The influence of glyphosate on soil CO2 respiration and microbial communities structure in histosol and fluvisol 

Adam Furtak, Anna Szafranek-Nakonieczna, Andrzej Górski, and Anna Pytlak

Carbon dioxide is the most important among all greenhouse gases and microbial respiration is one of the fundamental soil processes, that contribute to atmospheric CO2 pool. Many factors influence the respiration of soil microbiota. With regard to agricultural soils, the most discussed are the type of cultivation and fertilisation. Much less attention is paid to herbicides, which are widely used and comprise a frequent contaminant of the soil environment. The most commonly used herbicide worldwide is glyphosate (GFP). In 2018, annual  GFP consumption exceeded 8.25 x 108 kg and is still increasing. GFP is a foliar herbicide that is used in agriculture in the form of commercial formulations (GFC). Due to imprecise dosing, leaf washoff or with plant necromass, GFC reaches the soil environment where can potentially modulate activity and abundance of soil microorganisms. Possible modes of action include toxicity (e.g. due to inhibition of the shikimate pathway) or stimulation due to the fact that GFP is biodegradable and can potentially be a source of all major biogenic elements C, N and P. Due to the widespread use of GFC in agriculture, it may be an important driver of soil-related CO2 emissions, but knowledge in this area is still fragmentary.  

In the current study, a wide range of GFP and GFC (0 – 10 000µg g-1) doses were used to determine its effect on microbial respiration in two agriculturally used soils (histosol and fluvisol). In parallel, the qualitative and quantitative composition of the soil microbial community was studied. Pure glyphosate (GFP) and a commercial formulation (GFC) containing adjuvants in addition to glyphosate were tested.

For both soils, the exposure to GFP and GFC resulted in an increase in microbial respiration. However, this effect was greater for GFC, indicating the important role of adjuvants in shaping the environmental effect of the herbicides used. In accordance with the respiration results, a significant increase in the total bacteria count was found in both studied soils. Qualitatively, communities' structures were not significantly transformed, even under the influence of high doses of the tested preparations.

How to cite: Furtak, A., Szafranek-Nakonieczna, A., Górski, A., and Pytlak, A.: The influence of glyphosate on soil CO2 respiration and microbial communities structure in histosol and fluvisol, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5323, https://doi.org/10.5194/egusphere-egu24-5323, 2024.

EGU24-5799 | Orals | BG3.23

Stable-isotope probing identifies microorganisms actively degrading DMSP in anaerobic saltmarsh sediments 

Özge Eyice, Susan Hawthorne, Stephania Tsola, Ornella Carrión, and Jonathan Todd

Billions of tons of dimethylsulfoniopropionate (DMSP) are produced every year in marine and coastal ecosystems such as saltmarshes and estuaries. DMSP has far-reaching roles in global carbon and sulfur cycling, also as an osmotolerant and signalling molecule. Furthermore, the microbial degradation of DMSP contributes significantly to the formation of dimethylsulfide (DMS) and methanethiol (MT), other abundant organosulfur compounds with ecological significance. Particularly, in anaerobic sediments, microbial DMS and MT degradation leads to the formation of methane, a powerful greenhouse gas. However, research to date has predominantly focused on aerobic settings, revealing diverse groups of microbes and enzymes mediating DMSP degradation. DMSP concentrations in anaerobic ecosystems and microbial populations underlying DMSP breakdown have never been studied, prohibiting improvements in our understanding of global carbon and sulfur cycles. To address this key knowledge gap, we applied stable-isotope probing combined with 16S rRNA sequencing to identify the active DMSP-degraders in anaerobic saltmarsh sediments.

We collected sediments from a 5-10 cm depth of Medway Saltmarshes (UK) using 3.5cm Perspex corers. We transferred the samples to the laboratory and measured in situ DMSP concentrations of 7.7 (±0.5) μmol g−1 wet sediment. In line with the in situ concentrations, we set up replicated incubations anaerobically with 8 μmol g−113C- and 12C-labelled DMSP, and applied stable-isotope probing combined with 16S rRNA sequencing.

We observed immediate degradation of DMSP in the sediment incubations and DMS production, suggesting the existence of a resident microbial community actively carrying out this process. A total of 48 μmol/g 13C- or 12C-DMSP was amended and a total of 34 (±3.2) μmol/g DMS was produced in the incubations over 12 days.  DNA was extracted and ultracentrifugation was applied to separate heavy and light DNA fractions for downstream analysis. 16S rRNA sequencing of the fractions from 13C and 12C-labelled DNA demonstrated significant enrichment of the family Nitrincolaceae within the order Oceanospirillales in 13C-heavy fractions compared to 13C- light and 12C-heavy fractions (P<0.05). Their relative abundance increased from 2% (±1.3) to 27.2% (±9.1). This demonstrates that they are the active DMSP degraders in anaerobic saltmarsh sediments.

This is the first study quantifying significant concentrations of DMSP in anaerobic saltmarsh sediments and demonstrating Nitrincolaceae to be the active DMSP-degraders. Our findings not only broaden our understanding of microbial carbon and sulfur cycling but also highlight a previously overlooked route to methane formation in anaerobic saltmarsh sediments.  Our study underscores the need to identify microbial communities and pathways of DMSP breakdown across diverse anaerobic settings.

How to cite: Eyice, Ö., Hawthorne, S., Tsola, S., Carrión, O., and Todd, J.: Stable-isotope probing identifies microorganisms actively degrading DMSP in anaerobic saltmarsh sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5799, https://doi.org/10.5194/egusphere-egu24-5799, 2024.

EGU24-6777 | Posters on site | BG3.23

Development of an online O2-CO2 soil profile probe for flux estimations 

Martin Maier, Laurin Osterholt, and Elad Levintal

Reliable and accurate measurements of gas fluxes between soil and atmosphere are fundamental to calculate global greenhouse gas budgets. Chamber methods and the eddy covariance method are the most often used methods to measure soil-atmosphere gas fluxes. The gradient method can provide additional information about the localization of gas production within the soil profile. Using this approach gas fluxes in the soil profile are calculated by multiplication of the vertical concentration gradient of a gas in the soil by the effective gas diffusion coefficient of the soil. Technical progress in the field of small gas sensors has made it possible to integrate online CO2 sensors into soil gas profile monitoring systems, which greatly facilitates soil CO2 monitoring. While soil CO2 fluxes have been widely studied during the last decade, the “forgotten half” of this respiratory flux, the counter wise flux of atmospheric oxygen (O2) into the soil is rarely investigated, although it is known that O2 availability is the key for many soil processes.

Our objective was to develop and test a soil gas profile probe for online CO2 and O2 measurements with high temporal resolution that allows (1) soil–atmosphere flux estimation and (2) estimation of soil respiration profiles for both CO2 and O2 including (3) the apparent respiratory coefficient (CO2 efflux divided by O2 influx).

We developed a multilevel O2-CO2 profile probe with small build-in online sensors in multiple depths. The design was based on a modified version of a recently developed CO2 profile probe (Osterholt and Maier, 2020, Osterholt et al 2023). The probe consists of one 3D print segment per depth each containing one small NDIR CO2 and one O2 sensor. Extensive laboratory tests with different O2 sensors were necessary to exclude, or identify and quantify, possible biases in the O2 measurements due to expected environmental changes during field measurements (such as barometric pressure, soil temperature and relative humidity). The segments can be combined to probes of different length. For the installation of the sampler a hole has to be drilled, into which the sampler is inserted. We present first results from laboratory experiments and a field experiment, focusing on methodological issues and the technical performance of the measuring system.

Acknowledgements: This research was supported by the German Research Foundation (DFG, MA 5826/4‑1 project number: 535470615)

Osterholt, L. and Maier, M.: Development of an in-situ CO­2 gradient sampler, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7272, https://doi.org/10.5194/egusphere-egu2020-7272,  2020.

Osterholt, L.; Kolbe, S.; Maier, M. (2022): A differential CO2 profile probe approach for field measurements of soil gas transport and soil respiration #. In J. Plant Nutr. Soil Sci. 185 (2), pp. 282–296. DOI: 10.1002/jpln.202100155.

How to cite: Maier, M., Osterholt, L., and Levintal, E.: Development of an online O2-CO2 soil profile probe for flux estimations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6777, https://doi.org/10.5194/egusphere-egu24-6777, 2024.

EGU24-7425 | ECS | Orals | BG3.23

Hysteretic response of N2O reductase activity to soil pH variations after application of lime to an acidic agricultural soil 

Camille Rousset, Iheb Ouerghi, Florian Bizouard, Henri Brefort, Marjorie Ubertosi, Mustapha Arkoun, and Catherine Hénault

Nitrous oxide (N2O) contributes to increasing the greenhouse effect and is also involved in stratospheric ozone depletion. In soil and water, N2O reductase catalyses the reduction of N2O into the inert form N2 and is then considered as a key environmental enzyme. N2O reductase activity is known to be affected by acidic conditions (Samad et al. 2016) and the application of liming materials to acidic soils is now proposed as a solution for mitigating soil N2O emissions (Barton et al. 2013).

During a one-year laboratory experiment, we studied the functioning of N2O reductase after the application of calcium carbonates to an acidic soil with initially a very low capacity to reduce N2O. The functioning of N2O reductase was characterised through anaerobic incubations using the acetylene inhibition technique combined with a logistic model to determine the main enzyme functioning characteristics (latency, maximal rate).

Both changes in soil pH and soil capacity to reduce N2O were rapidly observed after the application of lime materials. The activity of N2O reductase was observed to be efficient throughout the experiment even when the soil had returned to initial acidic conditions, revealing a hysteretic response of N2O reductase to pH variations. Nevertheless, some signs of lower N2O reductase activity over time were observed mainly after 200 days of applying lime materials. Altogether, these results suggest that, in this soil condition, the beneficial impact of the application of liming materials on N2O emissions could last longer than this on soil pH.

Keywords: Climate change mitigation · N2O reductase · Soil · pH · Lime application · Logistic modelling

 

References:

Barton, L. et al. (2013) Is liming soil a strategy for mitigating nitrous oxide emissions from semi-arid soils? Soil Biology and Biochemistry 62, doi: 10.1016/j.soilbio.2013.02.014

Samad, M. S. et al. (2016) High-resolution denitrification kinetics in pasture soils link N2O emissions to pH, and denitrification to C mineralization. Plos One 11, doi: 10.1371/journal.pone.0151713  

 

Acknowledgements: The authors gratefully acknowledge funding for the NatAdGES project from the “Investissement d’Avenir” program, ISITE-BFC project (contract ANR-15-IDEX-0003), the European Regional Development Fund (FEDER), the public investment bank (BPI France) and the CMI-Roullier.

How to cite: Rousset, C., Ouerghi, I., Bizouard, F., Brefort, H., Ubertosi, M., Arkoun, M., and Hénault, C.: Hysteretic response of N2O reductase activity to soil pH variations after application of lime to an acidic agricultural soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7425, https://doi.org/10.5194/egusphere-egu24-7425, 2024.

EGU24-8889 | ECS | Orals | BG3.23

Using 15N isotope and microbiome analysis to understand N2O production and consumption processes. 

Mohit Masta, Mikk Espenberg, Jaan Pärn, and Ülo Mander

Nitrous oxide is a potent greenhouse gas which is involved in stratospheric ozone depletion. Even though nitrogen cycle has been studied for a long time, it is still challenging to understand specific N2O production and consumption processes. This is due to the complexity and heterogeneity of soil, wherein multiple processes can take place simultaneously. Isotopic composition of N2O can help us solve this and provide useful information on evaluating N2O sources and calculate global budgets. N2O is a linear molecule and its understanding at molecular scale can provide major insights into partition of its source processes. The N2O site preference (SP), which is the difference in δ15N between N2O molecules substituted with 15N at the central and the peripheral position, has proved to be a major tool to tackle this problem. The objective of this study is to use isotopic and microbial research for N2O sources and process partitioning. We will bring some examples from our recent studies in the lab and in a drained peatland forest.

 

During our lab study based on peat soil from a floodplain fen, we observed bacterial denitrification was a major source of N2O emissions under flooded conditions. We observed this using 15N isotopic mapping technique, which helped separate multiple active processes. We applied a similar method in-situ on a drained peatland in southeastern Estonia and described hybrid N2O formation, where one N atom of the N2O molecule was taken from NH4 and the other N molecule from another source such as organic N, was the dominant source of N2O emissions. The isotopic mapping and molecular enrichment of 15N during our experiment showed that. The isotopic mapping initially suggested nitrification as a major source, but on further investigation of 15N enrichment, we found the presence of hybrid processes (15N nitrogen from two pools or processes). Furthermore, we studied the genetic potential for major N2O processes (denitrification, nitrification, dissimilatory nitrate reduction to ammonium (DNRA)) and combined these with the isotope results, and this integrated approach is an important tool to partition N2O processes. When using 15N tracers, the isotopic technique can partition the sources (nitrate or ammonia) of N2O. Hence, using the isotopic mapping of natural abundances and 15N tracers to partition the source, we can get initial insights into N2O sources and processes together. Isotopic mapping is still under development and further research is required as it also has a problem of overlapping of processes.

How to cite: Masta, M., Espenberg, M., Pärn, J., and Mander, Ü.: Using 15N isotope and microbiome analysis to understand N2O production and consumption processes., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8889, https://doi.org/10.5194/egusphere-egu24-8889, 2024.

The dynamics of soil carbon (C) emissions along with their biogeochemical and environmental control have garnered increasing attention. However, the role of methane (CH4) in soil organic carbon (SOC) modelling has been relatively underexplored compared to carbon dioxide (CO2), and the omission of microbial processes may prevent us from accurately modelling CH4 dynamics under environmental changes. Here, we incorporated an explicit microbial CH4 module into the Microbial-ENzyme Decomposition (MEND) model and evaluated it against a sub-version with the first-order kinetics (First-order) and the previous MEND (MEND_old) model. We conducted a rigorous calibration and validation of MEND with high-resolution CO2 and CH4 efflux observations across two soil types and five different oxygen (O2) fluctuation conditions. Beyond precisely capturing soil CO2 and CH4 effluxes, the model could also effectively simulate the relative contents of microbial biomass and enzymes. The multi-model comparison further revealed that the inclusion of new processes did not necessarily enhance model performance if microbes were not perceived as explicit state variables. Our results demonstrated that adopting microbial functional groups as drivers of soil CH4 cycle could provide a basis for testing hypotheses on microbially mediated CH4 processes and their responses to environmental changes. With the availability of diverse data and the development of genetic technologies, our modelling framework present here will empower ecologists and governments to perceive and intervene in global warming from underlying biogeochemical mechanisms rather than predictions.

How to cite: Wang, G. and Zhou, S.: Representing explicit microbial processes enhances methane modeling under oxygen fluctuation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9741, https://doi.org/10.5194/egusphere-egu24-9741, 2024.

Drylands, constituting approximately 56% of the Earth's terrestrial surface, stand as the largest biome. Despite their vast expanse, our understanding of soil trace gas emissions from these regions remains limited. This knowledge gap arises from an uneven distribution of soil trace gas flux measurements across continents. While North American and East Asian drylands have been extensively studied, reports from other drylands are scarce. This lack of information hinders our ability to effectively constrain the atmospheric budget of reactive carbon and nitrogen gases and to develop predictive models for changes in soil trace gas emissions amid ongoing global environmental changes.

To address this gap, we conducted a comprehensive study in the Negev Desert, Israel, utilizing an array of seven automatic soil static chambers coupled to two infrared gas analyzers. This allowed us to measure soil emissions of methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) near-continuously every 15 minutes over three rainless months, measuring ~5000 individual soil fluxes. Our focus was on bare soils with varying organic carbon content (0.2%, 0.5%, and 0.6%) and nitrogen content of ~0.1%.

Our findings reveal significant diurnal variations in both CO2 and N2O emissions. CO2 emissions peaked at noon (1318.2±440.4 µg C m-2min-1) and reached their lowest point at midnight (373.4±228.8 µg C m-2min-1). In contrast, soil N2O flux was highest at 9:00 (0.07±0.02 µg N m-2min-1) and lowest at 21:00 (0.03±0.01 µg N m-2min-1). Soil CH4 flux exhibited minimal variation, with maximum and minimum emissions of 0.43±0.24 and 0.16±0.09 µg C m-2min-1, respectively.

Notably, the distinct peak emission times for CO2 and N2O suggest different underlying mechanisms for the production of these gases in the soil. Furthermore, we observed a strong correlation between soil CO2 emissions and soil water fluxes, while all gaseous fluxes correlated with the organic carbon content of soils. This emphasizes the role of water and soil organic carbon as primary driving factors for trace gas production in desert soils during rainless periods. Specific mechanisms of soil trace gases production in dry desert soils, however, will require further research.

How to cite: Gelfand, I. and Grabovsky, V. I.: During the rainless season, arid soils exhibited large diurnal fluctuations in carbon and nitrous oxides emissions, while displaying a uniform pattern of methane emissions throughout the day. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10301, https://doi.org/10.5194/egusphere-egu24-10301, 2024.

EGU24-11695 | ECS | Posters on site | BG3.23

Microbial nitrogen cycle in sub-tropical peatland cloud forest and wetland ecosystems of Réunion Island 

Fahad Kazmi, Ülo Mander, Reti Ranniku, Maarja Öpik, Kaido Soosaar, Kuno Kasak, Claudine Ah-Peng, and Mikk Espenberg

Peatlands play an essential role in the regulation of carbon and nitrogen cycles. Nitrogen-rich peatlands under warm and dry conditions can be a source of N2O, a potent greenhouse gas. Research on microbial activity, particularly in relation to N2O emissions in sub-tropical peatlands and wetlands, is very limited. In the current study, we investigated two peatland cloud forest sites in Reunion Island, namely Plaine des Cafres (characterized by dominant species Erica reunionensis and Alsophila glaucifolia) and Forêt de Bébour (featuring Erica reunionensis exclusively), alongside one RAMSAR wetland site located in Saint Paul. Both cloud forest sites were located at an altitude of 1500-1600 m, while the wetland was at an altitude of 4 m. to clarify the microbial dynamics of the nitrogen cycle in sub-tropical peatland cloud forests and wetlands.

DNA extraction was performed on these samples, followed by quantification of genes associated with the nitrogen cycle using quantitative polymerase chain reaction (qPCR). Analyses are ongoing for plant samples. In addition, soil samples underwent analyses to assess levels of ammonium (NH4+-N) and nitrate (NO3-N). Soil N2O fluxes were determined by collecting gas samples from the chamber headspace of static soil chamber systems at 20-minute intervals during one-hour sessions. The concentration of N2O was determined from gas samples using a gas chromatographer (Shimadzu, 2014).

All sites emitted negligible soil N2O fluxes (mean: 0.9 µg N m−2 h−1). However, a substantial amount of soil NH4+-N was found across all sites (mean: 77.2 mg/kg). The forests dominated by Erica reunionensis showed the highest values (mean: 106 mg/kg). Soil NH4+-N significantly correlated with the abundance of the nifH gene (R2 = 0.7, p<0.05). This indicates a high potential for microbial nitrogen fixation in all sites. Soil NO3-N varied significantly among different ecosystems. The cloud forests dominated by Erica reunionensis showed the highest values (mean: 139 mg/kg) as compared to the mixed forest (mean: 53.7 mg/kg) and the wetland site (mean: 2.53 mg/kg). Archaeal amoA gene abundance and proportion in soil were higher (p<0.05) in cloud forest sites than in wetland sites, positively correlating with NO3-N (R2 = 0.7, p<0.05). This reveals an archaeal nitrification potential in cloud forests. The nir:amoA ratio, as well as the nirS gene proportion, was significantly higher in the wetland (p<0.05), indicating the anaerobic denitrification potential, which explains the low NO3-N values there. Meanwhile, low soil N2O fluxes in the cloud forest soils can be attributed to the high abundance and proportions of nosZI-type denitrifiers.

The canopy soil from Erica reunionensis had a higher abundance of nirK and nosZI genes than Alsophila glaucifolia's canopy soil (P<0.05). However, it was the opposite in the case of fungal nirK abundance. The presence of denitrification genes in the canopy indicates an aboveground potential denitrification pathway in the cloud forests of the Réunion island. 

How to cite: Kazmi, F., Mander, Ü., Ranniku, R., Öpik, M., Soosaar, K., Kasak, K., Ah-Peng, C., and Espenberg, M.: Microbial nitrogen cycle in sub-tropical peatland cloud forest and wetland ecosystems of Réunion Island, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11695, https://doi.org/10.5194/egusphere-egu24-11695, 2024.

EGU24-12260 | Posters on site | BG3.23

The influence of herbicides on greenhouse gases emissions from soil: a bibliometric analysis 

Anna Pytlak, Adam Furtak, and Anna Szafranek-Nakonieczna

Agriculture is an important factor shaping gas exchange in the soil-atmosphere system. An important mechanism of agricultural impact is through the modulation of the living conditions of soil microorganisms responsible for the biological formation and utilisation of greenhouse gases. In this respect, agrochemicals play an important role. Fertilisers in particular have received much attention to date. The effects of soil supplementation, particularly with mineral nitrogen-containing fertilisers or organic fertilisers, on the microbial communities responsible for GHG transformation are well documented. Far less attention has been paid to other categories of agrochemicals, including herbicides. Meanwhile, the intensification of agriculture and the introduction of herbicide-resistant, transgenic crops involves the introduction of huge quantities of these chemicals (in the thousands of tonnes per year) into the environment. As a result of inaccurate dosing and with dead plant biomass, these compounds end up in the soil environment. The current paper presents a synthesis of information on the current state of knowledge regarding the effects of 4 commonly used herbicides worldwide (glyphosate, glufosinate, atrazine and 2,4-D) on the cycles of the most important greenhouse gases. VOS wiever software, equipped with text mining functionality was used to construct and visualise co-occurrence networks of important terms extracted from a body of scientific literature. An analysis of bibliographic databases for co-occurrence of key words such as "methane", "nitrous oxide", "carbon dioxide" and "greenhouse gas" - separately for each of the studied herbicides revealed that knowledge in this area is scarce and fragmentary. In the context of effects on greenhouse gas balance, only a few papers were recorded for glyphosate and atrazine and none for glufosinate or 2,4-D. In view of increasing global warming and the intensification of agricultural activity, it is important to complete the knowledge in this area.

Acknowledgements

This work was supported by the Project “Effect of glyphosate on the biological methane oxidation in agricultural soils”, no. 2021/41/B/NZ9/03130 which was financed by National Science Centre Poland.

How to cite: Pytlak, A., Furtak, A., and Szafranek-Nakonieczna, A.: The influence of herbicides on greenhouse gases emissions from soil: a bibliometric analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12260, https://doi.org/10.5194/egusphere-egu24-12260, 2024.

EGU24-12641 | Posters on site | BG3.23

Groundwater changes affect soil CO2 dynamics 

Stefan Seeger, Faisal Hayat, Talat Saeidi, and Martin Maier

Soils play a central role in the global carbon (C) cycle and can be a major source or sink of greenhouse gases. The highest concentrations and turnover of soil C is typically found in the top soil (0-0.5m depth). Yet, the total amount stored of soil organic carbon (SOC) in the subsoil (e.g. 0.5-3m) can be large and could be mobilized when soil environmental conditions change. These could be slow changes due to global climate change e.g. in subsoil moisture or temperature affecting subsoil respiration, but also more abrupt changes e.g. subsoil SOC mineralization after a decline in the groundwater level when prior submerged SOC gets exposed to higher O2 levels.

Our objective was (1) to study the effect of a changing groundwater level on soil CO2 concentration dynamics and (2) to test if the gradient method is a suitable tool to identify subsoil respiration effects.

For this pilot study we used a multilevel soil CO2 profile probe that allowed simultaneous online monitoring of soil CO2 concentration at different depth (Osterholt et al 2022), and calculation of the depth distribution of the soil respiration profile based on the gradient method (Maier & Schack-Kirchner, 2014). The CO2 probe and additional sensors were installed in a large (3 m diameter) lysimeter field station with sandy soil where the groundwater table was kept constant for >10 years at 0.8m depth. During the study period the ground water table was changed several times between 0.3-1.0m depth directly inducing effects on the CO2 concentration itself (piston flow) and also on the soil respiration profile (enhanced mineralization after groundwater level drops), which would not have been observed by pure chamber measurements at the surface.

 

Osterholt, L.; Kolbe, S.; Maier, M. (2022): A differential CO2 profile probe approach for field measurements of soil gas transport and soil respiration #. In J. Plant Nutr. Soil Sci. 185 (2), pp. 282–296. DOI: 10.1002/jpln.202100155.

Maier, M., & Schack-Kirchner, H. (2014). Using the gradient method to determine soil gas flux: A review. Agricultural and Forest Meteorology, 192–193, 78–95. https://doi.org/10.1016/j.agrformet.2014.03.006

How to cite: Seeger, S., Hayat, F., Saeidi, T., and Maier, M.: Groundwater changes affect soil CO2 dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12641, https://doi.org/10.5194/egusphere-egu24-12641, 2024.

EGU24-12997 | ECS | Posters on site | BG3.23

Two decades of micrometeorological measurements show dynamic drivers of springtime N2O emissions 

Leah Brown, Ian B. Strachan, David Pelster, Stuart Admiral, Luc Pelletier, Brian Grant, Ward Smith, and Elizabeth Pattey

Nitrous oxide (N2O) is a potent greenhouse gas with a global warming potential 265 times that of carbon dioxide and the ability to destroy stratospheric ozone. Agricultural soils contribute over two-thirds of anthropogenic N2O emissions. Field observations in temperate climates have commonly shown N2O emission peaks occurring in the spring during a period of snow melt and soil thaw. This freeze-thaw period typically accounts for approximately 35% of annual N2O emissions, however, current understanding of its drivers is based off of relatively short observation periods. The analysis of such data over decadal time spans is therefore needed to improve our understanding of key drivers. Here, we report on 21 years (2002-2022) of micrometeorological N2O flux data from a field site in Ottawa, Ontario. Correlation analyses were conducted between the N2O flux during the spring thaw period and variables that are commonly considered drivers. Little to no correlation was seen from linear or multilinear regressions across a range of meteorological, management, and soil variables. The non-linear response of non-growing season cumulative N2O emissions to cumulative freezing degree-days was consistent with previous studies (Wagner-Riddle et al., 2017). However, in isolating freezing degree-days we may be neglecting other possible controls. These results show that the relationship of N2O flux with environmental variables may be related to complex, potentially non-linear, interactions between agricultural practices, weather, soil quality, and other variables. We will further examine the data using other multivariate statistical methods to further investigate potential drivers of these non-growing season emissions with a focus on those emissions occurring specifically during the spring thaw. As these relationships are used in nitrification/denitrification models, improved understanding is still needed to accurately simulate these processes, which is imperative to improving nitrogen budgets and ultimately achieving climate goals.

How to cite: Brown, L., Strachan, I. B., Pelster, D., Admiral, S., Pelletier, L., Grant, B., Smith, W., and Pattey, E.: Two decades of micrometeorological measurements show dynamic drivers of springtime N2O emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12997, https://doi.org/10.5194/egusphere-egu24-12997, 2024.

EGU24-13087 | ECS | Orals | BG3.23

Belowground methane cycling along a stream-to-edge transect in the Lompolojänkkä fen 

Lukas Kohl, Salla A. M. Tenhovirta, Iikka Haikarainen, Mari Pihlatie, Markus Greule, Frank Keppler, and Annalea Lohila

Lompolojänkkä is a nutrient-rich fen located in western Lapland. The site has been the focus of detailed methane flux measurements, which revealed high spatial variability along a transect from the central stream to the edge of the peatland. Surprisingly, the highest fluxes did not occur in the center of the peatlands, but rather at the halfway point between the center and the edge of the peatland, likely due greater oxygen transport by turbulent water flow at the center of the peatland. In this study, we aim to quantify the contribution of hydrogenotrophic and acetoclastic methanogenesis, the fraction of methane oxidized prior to emission to the atmosphere, and the location (depth) of these processes in the peat profile. We further investigate if these processes differ in space along a the stream-to-edge transect and time with the progress of the growth season. To quantify these processes, we collected pore water samples from 15 depth profiles at 20 to 100 cm depth. In these samples we quantified concentrations of dissolved methane, its carbon and hydrogen isotope values, and a suite of geochemical measures. We find that locations close to the central stream are characterized by high methane concentrations at depth, which decrease steeply towards the surface, indicating that high rate of methane are produced at depth but oxidized prior to reaching the surface. Sites located at the edge of the peatland, in contrast, show low methane concentrations throughout the peat profiles, indicating that small amounts of methane are produced relatively close to the surface. Stable carbon and hydrogen isotope values add additional complexity to our understanding of the methane dynamics. Methane oxidation is associated with strong increases in both δ13C and δ2H values in the residual methane and would therefore be indicated by an increase in both isotope values from deep to shallow peat layers. Such a pattern, however, was only detected close to the central stream, where approximately 50% of methane was oxidized prior to reaching the surface. In most other transect points, we found that δ13C increased from deep to shallow layers, whereas δ2H showed the opposite trend, indicating the mixing of hydrogenotrophic methane produced in deep peat layers with acetoclastic methane produced in the rooting zone. An isotope mixing model indicated that that the fraction of hydrogenotrophic methane increased from center to edge of the site (from 45 to 30% at 100 cm depth in June) and with the advancing growth season (32 to 0% in September). In contrast, we typically find less than 15% hydrogenotrophic methane in shallow layers. We note that these numbers are associated with significant external uncertainty stemming from poor certainty about mixing model parameters. Overall, our data demonstrates high and temporal spatial heterogeneity of methane production and oxidation within a single site. We demonstrate the additional information gained methane dual isotope analysis, and reveals how δ13C profiles alone can be ambiguous and misleading.

How to cite: Kohl, L., Tenhovirta, S. A. M., Haikarainen, I., Pihlatie, M., Greule, M., Keppler, F., and Lohila, A.: Belowground methane cycling along a stream-to-edge transect in the Lompolojänkkä fen, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13087, https://doi.org/10.5194/egusphere-egu24-13087, 2024.

EGU24-13690 | ECS | Orals | BG3.23

17-Years of Soil Gas Sampling for Assurance Monitoring at an Onshore CCS Demonstration Site in Victoria, Australia 

Kexin Zhang, Svetlana Stevanovic, Zibo Zhou, and Wendy Timms

Carbon capture and storage (CCS) projects aim to capture carbon dioxide (CO2) from hard-to-abate industries and the existing energy industry, for permanent storage in suitable geological formations. CCS technologies offer promising solutions to achieve net-zero emissions and ease the transition towards clean energy. Environmental monitoring is employed to demonstrate minimal influences on the near-surface environment by the CCS operation and provides assurance to the regulators and local communities. Soil gas monitoring is one of the techniques available for monitoring onshore sequestration sites.

The Otway International Test Centre (OITC), Australia’s first demonstration site for deep-well CO2 injection, has demonstrated over 95,000 tonnes of CO2 sequestration into a depleted gas reservoir and a deep saline aquifer. Due to the unique regulatory framework under which the site is permitted, a requirement of the site’s EPA license for the injection of CO2 into the subsurface is soil gas monitoring, which commenced prior to the first injection in 2008. At the OITC, soil gas samples were collected at more than 100 sites across a study area of 3.8 km2 from a 1-meter depth, with soil gas baseline values established in 2007 and 2008. The samples were analysed for major gas concentrations (i.e., oxygen (O2), nitrogen (N2), CO2 and methane (CH4)), 13C analysis on CO2, and selected samples were tested for tracer, including sulphur hexafluoride (SF6), Krypton (Kr) and Xeon (Xe). Based on available data, the injection operations at the OITC have no undesirable impacts on the near-surface environment and, when managed appropriately, CCS operations can be conducted with a high level of confidence.

The 17-year soil gas data from the OITC shows high year-to-year variabilities in soil gas CO2 concentrations, posing a major challenge to ensure robust soil gas baseline monitoring. For this reason, the use of soil gas monitoring for regulatory processes is not supported, however, as a general site check and as a means to garner community confidence, it has proven to be useful. To address the challenge of this naturally occurring variability, a multi-step verification process has been implemented to enhance confidence in identifying or ruling out anomalies. This process incorporates tracer analysis, baseline analysis, and adapted analysis methodologies demonstrated in research papers, such as the process-based analysis. Furthermore, research was conducted to review the evolution of soil gas science in the CCS industry and to optimise the monitoring strategies with data collected from the OITC as a case study.  Valuable lessons highlighted the efficacy of risk-based monitoring adjacent to identified storage formations. For example, monitoring near relatively high-risk legacy wells with compromised well integrity or for highly faulted regions with great geological uncertainty. Risk-based monitoring that includes several locations with higher temporal resolution is supported for future large-scale CCS sites.

How to cite: Zhang, K., Stevanovic, S., Zhou, Z., and Timms, W.: 17-Years of Soil Gas Sampling for Assurance Monitoring at an Onshore CCS Demonstration Site in Victoria, Australia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13690, https://doi.org/10.5194/egusphere-egu24-13690, 2024.

EGU24-14300 | ECS | Posters on site | BG3.23

Hot spots and hot moments of N2O fluxes explained by monthly dynamics of soil microbiome in drained peatland forest 

Mikk Espenberg, Zane Ferch, Fahad Ali Kazmi, Jordi Escuer-Gatius, Sharvari Sunil Gadegaonkar, Reti Ranniku, Martin Maddison, Kaido Soosaar, Jaan Pärn, and Ülo Mander

The nitrogen (N) cycle involves intricate interactions affected by the spatial and temporal variability. Hot moments, occurring short-lived across seasons, significantly contribute to temporal nitrous (N2O) emission fluctuations. Likewise, N2O emissions exhibit localized spatial variability as hot spots. Year long monthly based studies of soil N cycle microbiome dynamics in peatland forests are unknown. This study investigates the relationship between soil microbial communities and N2O gaseous fluxes within a drained peatland forest throughout a year. Key research questions are: how are the genes responsible for N cycling in the peatland spatially and temporally distributed?; what patterns are there between soil characteristics (e.g., soil water content, soil temperature and pH) and N cycling gene abundances?

Soil samples from 12 sites within a drained peatland forest in south-eastern Estonia were collected over a year and analysed for their physical and chemical properties and the abundance of genes associated with N cycling. Quantitative polymerase chain reaction was used to evaluate the bacterial and archaeal community abundances by quantifying the abundances of specific 16S rRNA genes and to evaluating the abundances of 10 genes associated with N cycling: denitrification (nirS, nirK, nosZ clade I, nosZ clade II, and fungal nirK), nitrification (bacterial, archaeal, and comammox amoA), DNRA (nrfA), and N fixation (nifH). This data was paired with N2O flux data collected in automatic dynamic gas chambers throughout the study period.

Spatial variations apparent in the soil's chemical and physical composition reveal distinct vegetation and microbial communities across the area. Archaeal 16S rRNA, along with genes associated with N cycling (fungal nirK, nosZI, bacterial and comammox amoA), exhibited correlations with N2O emissions. Archaeal 16S rRNA, bacterial amoA, fungal nirK, and nosZI were positively correlated with N2O emissions. Throughout the year, water table levels and volumetric water content significantly influenced both N2O emissions and the abundance of N cycling genes. The site encompasses specific areas with consistently higher N2O emissions (hot spots) and periodic peaks in emissions (hot moments) due to the combined interplay of physical, chemical, and genetic attributes within the peatland soil.

How to cite: Espenberg, M., Ferch, Z., Kazmi, F. A., Escuer-Gatius, J., Gadegaonkar, S. S., Ranniku, R., Maddison, M., Soosaar, K., Pärn, J., and Mander, Ü.: Hot spots and hot moments of N2O fluxes explained by monthly dynamics of soil microbiome in drained peatland forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14300, https://doi.org/10.5194/egusphere-egu24-14300, 2024.

EGU24-14918 | Posters on site | BG3.23

Simultaneous Quantification of Soil Water States, Water Fluxes, Greenhouse Gases and BVOC Exchange between soil and atmosphere during transient conditions 

Efstathios Diamantopoulos, Hai Anh Nguyen, Frederic Leuther, and Anke Nölscher

Biogenic volatile organic compounds (BVOCs) are a diverse group of chemicals emitted from living organisms. These compounds are involved in a variety of ecological processes, as well as the formation of aerosols and ozone, which can impact air quality and climate. Recent studies suggest that BVOCs can be released and taken up by soil through biotic and abiotic pathways in high amounts. In this work, we simultaneously quantified the BVOCs exchange between , soil water evaporation fluxes, and matric potential under transient conditions (drying-rewetting experiments). The experiment was conducted with 250 cm³ soil cores (n=4) packed with sieved soil (loamy sand, bulk density: 1.6g/cm³) taken from agricultural topsoil. Aluminum chambers (1L in volume) were attached to the top of the soil cylinders and gas with different BVOCs concentrations was applied at the inlet. At the outlet, the analysis of BVOCs mixing ratios and BVOCs emission was done with a Proton Transfer Reaction – Time of Flight – Mass Spectrometry (PTR-ToF-MS). In addition, a Greenhouse Gas Analyzer (GGA) was used for monitoring the fluxes of methane, carbon dioxide, and water vapor. The analysis of soil water retention curves was done with a Hydraulic Property Analyzer (HYPROP). The results showed a strong negative correlation between ambient mixing ratios and soil emission rates of water-soluble BVOCs when the soil was wet. As the soil moisture fell below a threshold of 0.18 m3m-3 volumetric water content, BVOCs emission negatively correlated to soil water content. The more frequently the soil was rewetted, the more BVOCs could be taken up by wet soil. In conclusion, the study suggests that the BVOCs mixing ratio in the ambient air was the dominant driving factor of the BVOCs emission rate in disturbed soil samples from agricultural land use. Lastly, soil water content affected BVOCs emission mainly when the soil was dry.

How to cite: Diamantopoulos, E., Nguyen, H. A., Leuther, F., and Nölscher, A.: Simultaneous Quantification of Soil Water States, Water Fluxes, Greenhouse Gases and BVOC Exchange between soil and atmosphere during transient conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14918, https://doi.org/10.5194/egusphere-egu24-14918, 2024.

EGU24-15503 | ECS | Posters on site | BG3.23

Differences of nitrogen cycle microbes and nitrous oxide emissions from natural and degraded tropical peatland sites in Malaysia 

Laura Kuusemets, Ülo Mander, Maarja Öpik, Lulie Melling, Kaido Soosaar, Kuno Kasak, and Mikk Espenberg

Tropical peatlands in Southeast Asia are severe threats due to rapid changes in land-cover. Estimates suggest that approximately 25% of natural peatlands in Malaysia have been converted for large-scale agro-industrial development in the last two decades, primarily driven by the rapid expansion of oil palm cultivation. These intense and rapid land-use changes contribute to adverse ecological impacts, including increased greenhouse gas (GHG) emissions, soil degradation, deforestation and the loss of biodiversity. The aim of the study was to assess the genetic potential of nitrogen (N) transformation processes by quantifying functional marker genes of N cycle and measuring nitrous oxide (N2O) emissions from natural tropical peatland and oil palm plantation. This was conducted to understand the effect of land-cover changes on microbial N transformation processes and gaseous N emissions, using the closed chamber method and quantitative polymerase chain reaction (qPCR) analysis. N2O emissions were measured in the natural tropical peatland forest in Maludam (Sarawak, Malaysia) and in the oil palm plantation on peat soil in Betong (Sarawak, Malaysia) in September 2022. qPCR was used to measure the abundance of bacterial and archaeal specific 16S rRNA, nitrification (AOB, AOA and COMAMMOX amoA genes), denitrification (nirK, nirS, nosZ clade I and nosZ clade II genes) and dissimilatory nitrate reduction to ammonium (DNRA; nrfA gene) marker genes in the collected soil, litter and leaf samples.

The average soil N2O emissions were relatively higher from the oil palm plantation, ranging from 2.04 to 131.9 µg N m-2 h-1. Soil N2O emissions from the natural peatland forest were negligible. Quantification of N cycle genes revealed variations in the microbiome between natural peatland and deep-drained oil palm plantation. The microbial analysis showed that the archaeal abundance in leaves did not vary significantly between the two sites, but the abundance of bacteria in leaves was higher in the oil palm plantation. The abundance of denitrifying microorganisms was significantly higher in the natural peatland soil compared to the peat soil in the oil palm plantation. However, the abundances of bacterial amoA and archaeal amoA were found to be lower in the soil of natural site compared to the soil in oil palm plantation, suggesting a higher genetic potential of nitrification in the oil palm plantation. In addition, microbes possessing the archaeal amoA gene seemed to be the primary nitrifiers in the soil of oil palm plantation. The study’s findings indicate that hydrological interventions cause significant changes in the microbial N cycle and N2O emissions of tropical peatlands.

How to cite: Kuusemets, L., Mander, Ü., Öpik, M., Melling, L., Soosaar, K., Kasak, K., and Espenberg, M.: Differences of nitrogen cycle microbes and nitrous oxide emissions from natural and degraded tropical peatland sites in Malaysia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15503, https://doi.org/10.5194/egusphere-egu24-15503, 2024.

Wetting of dry soil after prolonged drought triggers emissions of N-oxides (nitric oxide; NO and nitrous oxide; N2O) and this post-wetting burst may contribute disproportionately to annual soil N-oxides emissions in drylands. During the wetting, nitrification and denitrification were shown to be the major sources of soil N-oxides emissions. Several abiotic reactions involving the nitrification intermediates- e.g. nitrite (NO2-), however, may also contribute to the production of N-oxides in soils. The contribution of these abiotic reaction to N-oxides emissions, despite potential importance is not well quantified. To quantify and partition the contribution of abiotic and biotic processes to post-wetting N-oxides emissions in drylands, we measured soil NO and N2O production in a laboratory incubation with live and gamma-irradiated soils. Samples were collected under canopies of dominant local (Acacia tortilis) and invasive (Prosopis juliflora) trees, as well as from bare soils outside the canopy cover.

We found that that while the overall dynamics of soil NO and N2O emissions were similar in gamma irradiated and live soils under both P. juliflora and A. tortilis trees, as well as in bare soils, the magnitudes and rates of emissions exhibited significant disparities. In particular, gamma irradiated soils under A. tortilis canopies after eight hours’ incubation, emitted ~10 times less NO (~5 ng N g-1) and ~4 times less N2O (~10 µg N g-1) compared to the live soils. While gamma irradiated soils under P. juliflora canopies emitted ~2 times less NO (~7 ng N g-1) and similar N2O (~7 µg N g-1) compared to the live soils, and in the bare soils, ~9 times less NO (~5 ng N g-1) and similar N2O (~10 µg N g-1). Our findings suggest that both biotic and abiotic pathways contribute to N-oxides production following dry soil wetting, however, the relative contribution is dependent on the landscape position and affected by plant presence and species. Specifically, abiotic processes contributed 10% to soil NO and 25% to N2O production in soils beneath A. tortilis canopies and between 10% and 75% in the bare soils. In soil under P. juliflora canopies abiotic processes contributed five times more to the NO production (50%) while N2O production was solely from abiotic activity.

How to cite: Yagle, I. and Gelfand, I.: Quantification and partitioning the contributions of abiotic and biotic processes to soil N-oxides emissions in the Dead Sea valley, Israel., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16201, https://doi.org/10.5194/egusphere-egu24-16201, 2024.

EGU24-17269 | ECS | Orals | BG3.23

Genome-resolved metagenomics of tropical peatland ammonia-oxidising archaea 

Frazer Midot, Kian Mau Goh, Kok Jun Liew, Sharon Yu Ling Lau, and Lulie Melling

Nitrogen cycling, a critical biogeochemical process in ecosystems, involves a complex microorganism network. In nitrification, ammonia oxidation is mainly governed by ammonia-oxidizing archaea (AOA) in acidic soil. Limited information exists about these taxa in tropical peatlands. This genome-centric metagenomic study aimed to identify key taxa and their functional potential driving nitrification in tropical peatlands. After cleaning Illumina reads, draft bins were created, refined, reassembled, and decontaminated through various strategies, involving both semi-supervised and unsupervised binners, including deep-learning-based approaches. This process resulted in 271 medium to high-quality archaeal metagenome-assembled genomes (MAGs). Five near-complete high-quality AOA MAGs were constructed. Phylogenomic analyses placed the AOA MAGs in the Nitrosotalea genus within the Nitrosopumilaceae family. Comparisons to reference genomes using average amino acid identity (AAI) and average nucleotide identity (ANI) suggested these MAGs might represent separate Nitrosotalea species. Besides core ammonia monooxygenase (amoCAB), these Nitrosotalea MAGs also encoded for nitrite reductase (nirK), ferredoxin-nitrite reductase (nirA) and nitric oxide reductase (norQ) that could also lead to the production of nitrous oxide (N2O), a potent greenhouse gas. These tropical peatland autotrophic Nitrosotalea MAGs fixed carbon with the hydroxypropionate/hydroxybutyrate pathway and survive in low pH environments through flagellar motility, various transport proteins, substrate acquisition and pH regulation systems for oxidising ammonia. Genomic analyses of candidate taxa can provide a thorough understanding of important biogeochemical functions as critical baseline information to assess microorganism resilience and response to anthropogenic-induced land use change.

How to cite: Midot, F., Goh, K. M., Liew, K. J., Lau, S. Y. L., and Melling, L.: Genome-resolved metagenomics of tropical peatland ammonia-oxidising archaea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17269, https://doi.org/10.5194/egusphere-egu24-17269, 2024.

EGU24-17493 | ECS | Orals | BG3.23

Differences in the uptake of biogenic volatile organic compounds (BVOCs) between habitat types and peat layers in boreal peatlands 

Aino Korrensalo, Cleo Davie-Martin, Elisa Männistö, James Blande, and Riikka Rinnan

Biogenic volatile organic compounds (BVOCs) released by boreal vegetation have a net cooling impact on climate, both in the boreal and Arctic regions. While boreal forests play a major role in this process, the release and uptake of BVOCs in peatlands is poorly understood, even though they cover up to 28% of the boreal region. Furthermore, soil BVOC sinks and sources are an understudied component of the boreal BVOC budget. Recently, microbial uptake of BVOCs has been found to regulate BVOC release from the soil into the atmosphere. In peatlands, methane emissions from the peat are known to be controlled by microbial oxidation within the living mosses, but it is unknown whether similar uptake occurs with BVOCs.

Our aim was to quantify the release and uptake of BVOCs across different boreal peatland habitats. We collected peat samples, including the living moss layer, from four peatland habitats varying in fertility, wetness, and vegetation composition (bog hollow, bog hummock, fen, bog peat). The samples were split into the living moss layer, as well as the oxic and anoxic peat layers, above and below the water table, respectively. First, we investigated the potential uptake of peat-derived BVOCs in the living moss layer by incubating the peat and moss layers in glass jars both separately and together with other layers from the same habitat. Next, we quantified the uptake of four specific compounds by introducing 13C-labeled BVOCs into jars containing peat or moss layers. The magnitude and compound composition of BVOCs was measured with proton transfer reaction–time of flight–mass spectrometry (PTR-TOF-MS).

Contrary to our expectations, BVOC uptake of peat-derived compounds was observed in the living moss layer, as well as in the oxic and anoxic peat layers. The most important layer for BVOC release and uptake varied between the peatland habitats. For example, the number of released compounds and the total BVOC emissions were largest for anoxic peat in the fen, while it was the living mosses in the bog hollow. Anoxic bog peat had the largest BVOC uptake of all of the habitats and layers. BVOC uptake varied between the studied compounds; while ethanol was taken up by all layers in every habitat, we observed no uptake of acetic acid. Acetone was mostly consumed in the peat layers, while acetaldehyde uptake occurred in bog hummock and fen habitats, regardless of the layer. According to our results, BVOC emissions from boreal peatland soil into the atmosphere are a net outcome of production and consumption both in the peat and moss layers. As these patterns vary even within habitats of the same site, changes in vegetation have the potential to modify BVOC fluxes in boreal peatlands.

How to cite: Korrensalo, A., Davie-Martin, C., Männistö, E., Blande, J., and Rinnan, R.: Differences in the uptake of biogenic volatile organic compounds (BVOCs) between habitat types and peat layers in boreal peatlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17493, https://doi.org/10.5194/egusphere-egu24-17493, 2024.

EGU24-18734 | ECS | Orals | BG3.23

Numerical investigation of methanotrophs in a biofilter for methane emission mitigation 

Morgane Bellec, Cristian Picioreanu, Muhammad Ali, and Laurence Gill

Methane is the second highest contributor to human greenhouse gas emissions. In Ireland, it represented 29% of the total CO2 equivalent emissions in 2022. A drastic reduction methane emissions is thus crucial to meet the Paris Agreement commitment of 30% reduction of emissions between 2005 and 2030. It is, however, challenging as more than half of anthropogenic methane emissions are produced at concentrations below 5%. At such low concentrations, methane cannot be efficiently recovered or even flared as it is lower than its flammability level in air. In Ireland, this concerns mainly the agriculture and the waste sector. In terms of wastewater treatment, on-site domestic wastewater treatment systems serve approximately one third of the households in Ireland and so represent a significant source of methane coming from the anaerobic processes (mainly septic tanks).

A promising alternative way to treat methane is microbial oxidation by methanotrophs grown on a suitable porous media. Such a passive biofilter could be easily placed on top of septic tank gas vents, capturing the emitted methane before it is released into the atmosphere. The methane-oxidizing bacteria will then convert it into carbon dioxide, which is approximately thirty times less potent greenhouse gas in terms of global warming potential.

 

Multiple questions must be addressed to confirm the practical feasibility of this methane biofilter concept. The environmental conditions in the filter must allow the methanotrophs to thrive and outcompete other bacteria, thus ensuring an efficient methane oxidation, without obstructing the airflow. In addition to methane, an adequate supply of oxygen is necessary. This requires complex simulations of both the fluid dynamics involved as well as microbial growth and other kinetic dynamics. To investigate these different physical and biological aspects, a numerical study has been conducted combining computational fluid dynamics (CFD) modelling and multispecies biofilm modelling.

The CFD approach is carried on at the system level, producing velocity fields in the septic tank and the different pipes and vents. Knowledge of the gas flow in the full wastewater treatment system is essential to estimate the inlet flow conditions the biofilter will be subjected to depending on the wind weather. The information obtained on the gas phase, especially oxygen and methane levels, is then fed into a multispecies biofilm model. At this local level, we model the methanotrophs as well as the other bacteria expected to grow, compete for space and oxygen, and decay in the biofilter environment: heterotrophs, nitrifiers and Sulphate Reducing Bacteria. The results show that the methanotrophs should not be outcompeted. Moreover, the model enables the height of the filter to be estimated such that it should reach the target of 90% of methane consumption. Finally, transient simulations give insight into the expected time of usage of the filter before it needs to be regenerated.  

How to cite: Bellec, M., Picioreanu, C., Ali, M., and Gill, L.: Numerical investigation of methanotrophs in a biofilter for methane emission mitigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18734, https://doi.org/10.5194/egusphere-egu24-18734, 2024.

EGU24-19680 | Orals | BG3.23

Bioelectrochemical biosensors for in-situ monitoring microbial activity in outdoor soil mesocosms from postharvest rice field 

Marc Viñas, Maite Martínez-Eixarch, Abraham Esteve-Núñez, Antonio Berna, Belén Fernández, Yolanda Lucas, Cristy Medina-Armijo, Miriam Guivernau, Lluis Jornet, Joan Noguerol, and Carles Alcaraz

The decomposition of buried straw in rice fields during post-harvest generates volatile fatty acids (VFA), thus activating methanogenesis (1). In this study, bioelectrochemical biosensors were used to measure the in-situ electrical current produced by electroactive microorganisms, related to the biodegradation of buired straw,  in outdoor mesocosms containing rice paddy soil from the Ebro Delta (Spain) .

Three  biosensors (BS1-BS3), based on bioelectrochemical cells buried in the water saturated soil (at a -10 cm), were used in 3 rice paddy soil mesocosms, with a poised working electrode (graphite) potential at +0.2V vs Ag/AgCl, by using a potentiostat. During 5 months (November 2022-March 2023), the production of electrical current (I) in the soil mesocosms was monitored using chronoamperometry. The presence of electroactive microbial biofilms on the electrodes was assessed by cyclic voltammetry (CV). Simultaneously, soil chemical parameters were monitored (total and soluble COD, VFA and CH4 emission), and microbial diversity (bacteria and archaea) in  the soil and the electrodes biofilms was assessed by 16S rRNA-metabarcoding.

Chronoamperometry data in BS1-BS3 showed a marked current production curve from the day 3 to 5 after straw addition, with an I max of 110-180µA (4.26-6.91 µA cm-2) at day 10, remaining higher than the baseline for 30-45 days, and concomitant with VFA accumulation  (69-28 mg-eq Acetic kg-1 soil , 7-40 days) and a high emission rate of CH4 (198.1±101.0 mg C-CH4· m-2 soil · h-1 7 days after straw addition. The CV revealed electroactive profiles in the 3 biosensors, similar in BS1-BS2 (oxidation peak -0.16/-0.22 V vs Ag/AgCl, similar to Geobacter), and different in BS3 (oxidation peak +0.26 V vs Ag/AgCl), revealing different electroactive microbial communities. 16S-based metataxonomy revealed an enrichment of well known electroactive bacteria on the three anode biofilm but with different relative predominances, encompassing mainly Desulfobulbus in BS1-BS3,  Geobacter mainly in BS1, but in less predominance in BS2 and BS3, Proteiniclasticum solely in BS3, and Clostridium in BS2 and BS3.  Methanogenic archaea such as Methanosarcina and Methanobacterium were also depicted on the anode, but at lower relative abundance than observed in the soil, where ammonium oxidizing archaea (Nitrososphaera and candidatus Nitrosocaldus) were also predominant.

The results showed the capacity of the bioelectrochemical-based biosensors for real time detection of microbial in-situ degradation processes of buried edible organic carbon (straw) in the soil of rice  paddy fields, also linked to methane emissions.

Aknowledgements
This research was funded by Agencia Estatal de Investigación (PID2019-111572RB-I00/AEI/10.13039/501100011033 ) from Spain.

References
1. Martínez-Eixarch, M., Alcaraz, C., Viñas, M., Noguerol, J., Aranda, X., Prenafeta-Boldú, F. X., Saldaña-De la Vega, J.A., Català, M.M. & Ibáñez, C. (2018). Neglecting the fallow season can significantly underestimate annual methane emissions in Mediterranean rice fields. PLoS One, 13(5), e0198081. DOI: 10.1371/journal.pone.0202159

How to cite: Viñas, M., Martínez-Eixarch, M., Esteve-Núñez, A., Berna, A., Fernández, B., Lucas, Y., Medina-Armijo, C., Guivernau, M., Jornet, L., Noguerol, J., and Alcaraz, C.: Bioelectrochemical biosensors for in-situ monitoring microbial activity in outdoor soil mesocosms from postharvest rice field, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19680, https://doi.org/10.5194/egusphere-egu24-19680, 2024.

EGU24-20187 | Orals | BG3.23

Soil microbial functional diversity changes under contrasting N2O emission events 

Stefania Mattana, Cinta Sabaté, Tiphaine Tallec, Francois Boland, Tanguy Manise, Bernard Heinesch, Iris Feigenwinter, Fabio Turco, Helena Rautakoski, Annalea Lohila, Rossella Guerrieri, Ivan Janssens, Marilyn Roland, Sílvia Poblador, Enzo Magliulo, Luca Vitale, Liyou Wu, Jizhong Zhou, Josep Peñuelas, and Angela Ribas

Denitrification, the reduction of nitrogen oxides (NO3-and NO2-) to NO, N2O and, ultimately, to N2 gas in soils, is classified as a microbiologically ‘broad process’ which can be conducted by a wide array of microbes belonging to remote phylogenetic groups. Further, understanding how environmental and management factors drive denitrification is challenging because they are scale-dependent, with large scale drivers affecting denitrification fluxes both directly and through drivers working at detailed small scales. 

Despite of this, we hypothesized that denitrification processes, although highly complexes due to the multiple processes and environmental conditions involved, they could present a functional convergence at the microbial community level explained by a short list of microbial groups or functions.  

On the other hand, different methodological approaches to assess soil microbial diversity are currently used; among them are multiple substrate-induced respiration by MicroResp™, enzymes activities and functional genes abundance and structure by GeoChip 5S microarray. We applied all those methods to study functional diversity in 5 different soils from 5 countries: Finland, Belgium; France, Switzerland and Italy. Studied soils have a wide range of soil pH, organic Carbon and Nitrogen content, and texture. Soils were sampled at Hot Moment and Low flux emission of N2O.   

The main objective of this study was to explore possible convergences in terms of functional microbial diversity in contrasting N2O emission events (low emission versus hot moments).  

Result showed that MicroResp™ , enzyme activities and GeoChip 5S microarray were reliable ecological indicator to evaluate soil microbial functionality diversity. Results stressed the importance to study soil microbiome at different magnitude of N2O emission with the aim to gain a deeper knowledge of nitrifiers community. Reciprocal relationship of those methodologies, soil proprieties and magnitude of flux emission of N2O are discussed.   

How to cite: Mattana, S., Sabaté, C., Tallec, T., Boland, F., Manise, T., Heinesch, B., Feigenwinter, I., Turco, F., Rautakoski, H., Lohila, A., Guerrieri, R., Janssens, I., Roland, M., Poblador, S., Magliulo, E., Vitale, L., Wu, L., Zhou, J., Peñuelas, J., and Ribas, A.: Soil microbial functional diversity changes under contrasting N2O emission events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20187, https://doi.org/10.5194/egusphere-egu24-20187, 2024.

EGU24-20747 | ECS | Orals | BG3.23

Dynamics of soil N2O fluxes and hot-moments typification: How are they related to environmental characteristics? 

Maria Cinta Sabaté Gil, Josep Peñuelas, Marcos Fernandez-Martinez, Stephania Mattana, Tiphaine Tallec, François Boland, Bernard Heinesch, Iris Freigenwinter, Helena Rautakoski, Annaela Lohila, Enzo Magliulo, Ivan Jansens, Marilyn Roland, Sílvia Poblador, and Àngela Ribas

To date, extensive field measurements of nitrogen oxide (N2O) exchanges in soils across diverse terrestrial ecosystems, complemented by controlled laboratory incubation studies, have unveiled considerable variability in N2O soil fluxes. This variability arises from the intricate interplay of various factors. Notably, soil N2O emissions display significant spatiotemporal fluctuations, including extreme events. The primary objective of this study is to enhance our understanding of the environmental factors influencing soil N2O fluxes and to characterize instances of pronounced N2O emissions, hereafter termed "hot-moments."

Our investigation encompassed six distinct sites of the Integrated Carbon Observation System (ICOS) network including agricultural systems, sylvicultural systems, and unmanaged forests spanning the northern hemisphere. To identify and categorize hot-moments events, we standardized N2O values and considered events greater than or equal to 4, or -4-fold standard deviations from the mean of each site.

We then conducted wavelet coherence analyses to delve into the patterns of N2O fluxes. In the biwavelet plots, our variable of interest was juxtaposed with each soil environmental variable, illustrating the distribution of correlations in the time-frequency domain of our signals. Employing this advanced approach, we explored N2O patterns and their variability in relation to specific environmental characteristics (soil water content, soil temperature, and CO2 flux) within the six temporal series (different soil types).

Our analyses revealed a recurring pattern across all time series, with a frequency of approximately 24 hours for the N2O vs. CO2 plots, indicating a daily correlation between the emissions of both gases. This correlation may be linked to seasonality in certain sites. Soil temperature emerged as a leading factor in shaping the daily patterns of N2O fluxes in most sites, exhibiting also a 24-hour pattern. Although the periodicities related to soil water content were less clear, a discernible pattern persisted with variations within sites. However, we will deepen into the discussion of these results and their implications in our EGU presentation.

 

Key words: N2O fluxes, hot-moments, soil environmental variables, temporal series, wavelet coherence analysis

How to cite: Sabaté Gil, M. C., Peñuelas, J., Fernandez-Martinez, M., Mattana, S., Tallec, T., Boland, F., Heinesch, B., Freigenwinter, I., Rautakoski, H., Lohila, A., Magliulo, E., Jansens, I., Roland, M., Poblador, S., and Ribas, À.: Dynamics of soil N2O fluxes and hot-moments typification: How are they related to environmental characteristics?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20747, https://doi.org/10.5194/egusphere-egu24-20747, 2024.

EGU24-20969 | ECS | Posters on site | BG3.23

Methanotrophy Potential in Tropical Peatland under Different Land Use in Sarawak, Malaysia 

Claudia Jenai Yeong, Herman Umbau Lindang, Adrian Ho, Sharon Yu Ling Lau, Samuel Lihan, Marcus Andreas Horn, and Lulie Melling

Tropical peatlands hold immense global significance, serving as critical ecosystems that provide a wide range of services including carbon storage. The conversion of a large fraction of tropical peatlands into primarily agricultural lands in Malaysia has raised concern over the dynamics of carbon cycle including methane (CH4) in tropical peat soil. As CH4 is a potent greenhouse gas mainly produced under anoxic conditions, it is widely assumed that the waterlogged nature of peatlands emit a significant amount of CH4, though CH4 emission in tropical peatlands are comparatively lower than boreal peatlands. Methane oxidation (methanotrophy) by methanotrophic bacteria is the only known biological oxidation of CH4. However, there is a limited understanding of the methanotrophy in tropical peat soil of different land use. This study aims to study the methanotrophy potential in both tropical peat swamp forest and oil palm plantations. Soil sampling was carried out in July 2023 (dry season) from peat swamp forest of Maludam National Park and an oil palm plantation (OPP), encompassing both matured and young OPP. All sites are historically from Mixed Peat Swamp (MPS) forest type. Peat sample was collected from the topsoil (0-10 cm depth). Methanotrophy potential was assessed by incubation in 100 mL vial bottle supplemented with 2-3% v/v CH4. Soil pH, moisture content, total C and N, and electrical conductivity were determined. The total N differs significantly (p<0.05) with 1.93%, 1.72%, and 1.53% in the peat swamp forest, matured OPP, and young OPP, respectively. Total N has been associated with methanotroph community composition and its oxidation activity. Soil methanotrophy ranged from 0.35 to 0.60 µmol g dw soil-1 day-1 during the microcosm study. Results from this incubation demonstrated methanotrophy potential rate across three sites showed no significant difference, suggesting methanotrophy of topsoil may not be affected by different land use. In addition, the methanotrophy rate showed no correlation with the total N in this study. Nevertheless, validation of pmoA gene abundance across different land uses using quantitative polymerase chain reaction analysis will be conducted to further confirm if methanotrophy is affected by different land use on tropical peat soil.

How to cite: Yeong, C. J., Lindang, H. U., Ho, A., Lau, S. Y. L., Lihan, S., Horn, M. A., and Melling, L.: Methanotrophy Potential in Tropical Peatland under Different Land Use in Sarawak, Malaysia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20969, https://doi.org/10.5194/egusphere-egu24-20969, 2024.

EGU24-21985 | Posters on site | BG3.23

Dynamics of Microbial Communities and Greenhouse Gas Flux Responses to Short-Term Flooding in Riparian Forest Soil 

Kristel Reiss, Ülo Mander, Maarja Öpik, Kärt Kanger, Thomas Schindler, Kaido Soosaar, and Mikk Espenberg

The growing interest in the impact of short-term floods on various ecosystems is driven by climate change and the increasing occurrence of extreme rainfall events. The control of nutrient quantity and distribution relies on complicated biogeochemical processes. Yet, our understanding of the microbial processes governing carbon and nitrogen cycling needs improvement, hindering our ability to estimate the effects of climate change on forests.

This study aimed to evaluate the influence of short-term flooding on bacterial, archaeal, and fungal communities and microbial processes with greenhouse gas (GHG) emissions in riparian alder forests. Topsoil peat samples were collected from riparian alder forests and analyzed with quantitative polymerase chain reaction (qPCR), and sequencing techniques were employed to assess processes and communities, while physicochemical parameters and in-situ GHG emissions were concurrently measured.

Floods exert a substantial influence on the intricate biogeochemical cycles within soil ecosystems. The flooding event led to a change in bacterial 16S rRNA abundances and a noticeable expansion in the size of Bryobacter and Candidatus Solibacter communities associated with the breakdown of organic carbon. Several aerobic genera like Arthrobacter, Ferruginibacter, Lacunisphaera, and Novosphingobium, which were identifiable before short-term flooding, became undetectable. Many of these organisms were known for their role in breaking down carbon compounds, highlighting the transformative impact of short-term flooding on the composition and functions of soil microbial communities and GHG emissions.

In the examined sites, a diverse array of arbuscular mycorrhizal (AM) fungal genera were identified, including Acaulospora, Archaeospora, Claroideoglomus, Diversispora, and Paraglomus. One pivotal aspect of these fungal communities is their role in establishing arbuscular mycorrhiza, a beneficial symbiotic association between plant roots and fungi. AM fungi contribute significantly to enhancing plant nutrition, stress resistance, and shaping soil structure and fertility.

Nitrifiers, particularly those associated with archaeal amoA, experienced notable shifts. Denitrifiers, identified through the nosZII gene, were also significantly impacted. Moreover, microorganisms engaged in the n-damo process displayed alterations. The flooding event was observed to augment the community size of denitrifying and nitrogen-fixing genera such as Rhodanobacter, Pseudolabrys, and RB41. In contrast, a decrease was noted in the abundance of nitrifiers, exemplified by the decline of Nitrospira. Furthermore, several associations were observed between marker genes of the nitrogen cycle and N2O emissions.

How to cite: Reiss, K., Mander, Ü., Öpik, M., Kanger, K., Schindler, T., Soosaar, K., and Espenberg, M.: Dynamics of Microbial Communities and Greenhouse Gas Flux Responses to Short-Term Flooding in Riparian Forest Soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21985, https://doi.org/10.5194/egusphere-egu24-21985, 2024.

SSS5 – Soil Chemistry and Organic Matter Dynamics

EGU24-221 | ECS | Orals | SSS5.2

Effects of Contrasting Organic Amendments on Carbon Stability and Soil Carbon Dynamics in Acidic and Alkaline Soils  

Sara M. Pérez-Dalí, Águeda Sánchez-Martín, Jorge Márquez-Moreno, Jose A. González-Pérez, Layla M. San-Emeterio, and José María de la Rosa

The application of organic amendments, both traditionally utilized (e.g., compost) and more recent innovations (e.g., biochar), to degraded agricultural soils is being driven by international initiatives in the current context of global change, such as the "4 per mil initiative". The main goal is to achieve sustainable soil quality restoration, contributing to carbon (C) sequestration, while also providing a practical use and value addition to agro waste products. Despite the generally recognized benefits of such applications on soil productivity and physical properties [1,2], their effects on soil C cycling and sequestration are not as comprehensively understood. Results exhibit considerable variability depending on the type of amendment and the specific soil, emphasizing the need for a more in-depth investigation in this area [3]. Therefore, the aim of this study was to analyze the effects of contrasting organic amendments on soil carbon stability.

To accomplish this, two soils commonly employed in humid grasslands of the northern region and rainfed agriculture in the southern region of the Iberian Peninsula, respectively, were amended in triplicate at 10% (w/w) with wastewater sludge biochar, olive pomace biochar , white poplar wood biochar, rice husk biochar, cow manure digestate, a mixture of cattle manure and straw digestate (CM&SD), green compost (GC), and a mix of GC and OPB. A control was also established for each type of soil. After inoculating all the vessels with 1 mL of a standard microbial solution, respiration rates (CO2 emissions) were measured every 6 h over 100 days using an automated respirometer (Nordgren Innovations, Sweden) under controlled conditions (25°C; 60% water holding capacity). The data obtained were plotted against the incubation time by an exponential curve to discern the C stability through fast and slow C pools.

Our findings revealed significantly enhanced stability of recalcitrant carbon (slow C pool) in both soils treated with biochars, particularly in the case of RHB and WB. These amendments substantially extended the mean residence time of the slow C pool (MRT2) by a factor of six to nine. The overall trend observed for the studied amendments was as follows: biochar >> green compost >> digestates > native soil carbon. In contrast, the alkaline rainfed soil exhibited a faster carbon turnover rate compared to the grassland soil, resulting in a lower C MRT2.

Acknowledgements:  The Spanish Ministry of Science and Innovation (MCIN) and AEI are thanked for funding the project RES2SOIL (PID2021-126349OB-C22). The European Joint programme EJP SOIL from the EU Horizon 2020 R&I programme is thanked for funding the subproject EOM4SOIL (Grant agreement Nº 862695).

References:
[1] De la Rosa, J.M., Pérez-Dalí, S.M., Campos, P., Sánchez-Martín, Á., González-Pérez, J.A., Miller, A.Z., 2023. Agronomy, 13, 1097.
[2] Doblas-Rodrigo, A., Gallejones, P, Artetxe, A., Merino, P., 2023. Sci. Total Environ., 901, 165931.
[3] De la Rosa, J.M., Rosado, M., Paneque, M., Miller, A.Z., Knicker, H., 2018. Sci. Total Environ., 613-614, 969-976.

How to cite: Pérez-Dalí, S. M., Sánchez-Martín, Á., Márquez-Moreno, J., González-Pérez, J. A., San-Emeterio, L. M., and de la Rosa, J. M.: Effects of Contrasting Organic Amendments on Carbon Stability and Soil Carbon Dynamics in Acidic and Alkaline Soils , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-221, https://doi.org/10.5194/egusphere-egu24-221, 2024.

ABSTRACT

Nowadays, due to high population pressure more fragile lands are put into farming which then leads to low crop yield, loss of biodiversity and above all contributing to increased greenhouse gas emissions. This two year study (2020-2021) evaluated the potential of legume green manure (GM) species in improving soil fertility and barley yield, and their ability to effectively sequester soil organic carbon (SOC) towards reducing greenhouse gas emissions. The GM crops; lupine and vetch were planted during the main rainy season on the land that previous barley crop was harvested and left bare and fallow. The green manures crops were chopped and ploughed under at their 50% flowering stage and the main test crop, barley was introduced during the next cropping season. The treatments included (i) vetch GM, (ii) vetch GM + 23N + 20P, (iii) lupine GM, (iv) lupine GM + 23N + 20P, (v) fallow, (vi) fallow + 46N + 20P laid down in RCBD design with three replications. The N rate used was half when integrated with the GM species but full dose with the fallow system, whereas P was full dose. Results showed that barley grain & biomass yields were increased by 3.7 to 39.8% and 10.66 to 38.58%, respectively due to the application of the GM crops. The highest grain yield (4.1 t ha-1) and biomass yield (10.1 t ha-1) were recorded from vetch + NP application while the least grain yield (2.94 t ha-1) & biomass yield (7.24 t ha-1) were registered from the traditional fallow system. Green manure addition has brought 25 to 95.41% SOC relative change in the top 0-20cm soil depth compared with the traditional fallow system. Since both GM species are legumes, they added more N to the soil alongside with storing more C in the soil so that C: N ratio was also not affected. The highest carbon sequestered was from sole application of vetch GM (26.18 t C ha-1 yr-1) followed by vetch + NP applications (22.82 t C ha-1 yr-1). Lupine GM alone sequestered 9.24 t C ha-1 yr-1 and lupine + NP sequestered 6.86 t C ha-1 yr-1. The carbon balance in the fallow and fallow + NP combinations were negative (-0.98 and -1.40 t C ha-1 yr-1, respectively) indicating that there was C loss to the atmosphere. Therefore, application of vetch and lupine GMs with and/or without inorganic fertilizer integration had positively contributed towards improving the yield of barley and sequestering more C as compared to the local fallow practice.

How to cite: Debele, G. G., Kassie, K., and Getachew, T.: Improving Carbon Sequestration and Yield of Barley (Hordeum vulgare) through Combined Application of Green Manure and Mineral Fertilizers under Cambisols in Ethiopian Highlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-802, https://doi.org/10.5194/egusphere-egu24-802, 2024.

EGU24-1004 | Posters on site | SSS5.2

Comparative effect of incorporated and surface spread crop residues, poultry manure and their biochars on soil health indicators along a soil profile  

Tanvir Shahzad, Rummana Basit Mir, Umme Aiman Fiaz, Huma Shahid, Fiza Arshad, and Muhammad Sanaullah

Biochar is being touted as a wonderful amendment for improving soil health. However, its effectiveness for alkaline soils that are poor in organic matter has rarely been evaluated, particularly in long term field experiments. We laid down a field experiment based on wheat-maize crop rotation where we either incorporate or spread on surface the residues of the previous crop (wheat or maize), poultry manure or biochar(s) derived from these organic amendments. They are applied at the rate of 2 tons ha-1 before sowing each crop. It was hypothesized that the organic amendments applied in their feedstock or biochar form will considerably differ in space and time vis-à-vis soil health indicators. Moreover, tillage (incorporation i.e., conventional tillage vs surface spreading i.e., no tillage) would significantly alter the effect of these organic amendments. Over two years and four cropping seasons, the CO2-C emissions from the field were significantly higher (12-17%) when residues or biochar were incorporated. However, the feedstocks (residues/manure) induced significantly higher CO2-C emissions than their respective biochars across the tillage treatments (13-23%). Furthermore, the ammonia emissions were significantly reduced when biochars were added (5-11%) where surface spreading, or incorporation didn’t induce any difference. First soil sampling was done till 75 cm in depth increments of 15 cm, after two years of the experiment (Nb: the experiment is running). Microbial biomass (MBC) was significantly higher in upper layers (0-15 cm, 15-30 cm) in the plots incorporated with residues while all other amendments or tillage treatments showed similar MBC. No change in MBC was observed below 30 cm in any treatment. The soil organic carbon content (& stocks) were slightly but significantly higher (by 5-14%) in upper layers where biochars were incorporated, whereas incorporating residues increased soil organic carbon compared to biochar surface spreading. The extracellular enzymatic activity particularly of β-glucosidase, was significantly altered to 60 cm in some treatments with residue addition (incorporation or spreading) inducing higher activity. The leucine aminopeptidase activity remained unchanged throughout the soil profile in most of the treatments. However, chitinase activity was significantly higher in some biochar amended soils. These preliminary results indicate that residues/manure as well as their biochar significantly improve soil health indicators and that their method of application (incorporation vs spreading) significantly alter their effects. However, it must be noted that both types of amendments have improved different soil health indicators at this stage of the experiment.  

How to cite: Shahzad, T., Mir, R. B., Fiaz, U. A., Shahid, H., Arshad, F., and Sanaullah, M.: Comparative effect of incorporated and surface spread crop residues, poultry manure and their biochars on soil health indicators along a soil profile , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1004, https://doi.org/10.5194/egusphere-egu24-1004, 2024.

EGU24-1152 | ECS | Orals | SSS5.2

Soil moisture determines dead wood effects on soil organic matter in temperate beech forests 

Robin Schäfferling, Lilli Zeh, Patrick Wordell-Dietrich, Alina Azekenova, Alexandra Koller, Kenton Stutz, Karl-Heinz Feger, Stefan Julich, Goddert von Oheimb, and Karsten Kalbitz

Dead wood has important functions in forest ecosystems. It is a biodiversity hot spot, serves as a storage of water and stores 8% (73 +- 6 Pg) of the world’s forest carbon (Pan et al., 2011). The fate of this carbon (C) is still highly debated particularly concerning its influence on soil organic matter (SOM) and its contribution to the forest soil’s C sink. The aim of this research is to investigate how downed beech dead wood affects the stable soil C pool of temperate beech forests, and how this depends on soil moisture.

The research was conducted in a near natural beech forest near Leipzig, Germany (Dübener Heide) and is part of the BENEATH-Project. We sampled three sites representing a soil moisture gradient, i.e. dry, intermediate (i.e. moist) and wet conditions. Undisturbed soil cores were taken from these sites in three depth (0-10 cm, 10-20 cm and 20-30 cm) beneath dead wood at an advanced stage of decay. Reference soils were sampled at a distance of about 2 m. Soil moisture and soil temperature are constantly monitored. We applied a physical fractionation scheme to identify the effects of dead wood on differently stable SOM fractions. The samples were separated in the free light fraction (F-LF), the occluded light fraction (O-LF) and the heavy fraction (HF) via density fractionation using sodium polytungstate solution (ρ =1,6 g cm-³). For each fraction, the organic C and N contents were determined.

Our results indicate a positive influence of dead wood on SOC stocks in the dry and wet regions of our soil moisture gradient. In the intermediate region of the soil moisture gradient, dead wood has no or even a negative effect on SOC stocks. Changes in the SOC content under dead wood compared to the reference soil occurred manly in the F-LF and HF fraction at 0 cm and 10 cm depth. The observed pattern of dead woods effect on SOC along the moisture gradient is suggested to be a result of the relationship between soil moisture and microbial activity. According to the literature, we assume that the microbial activity should be highest in the intermediate moist soil and to some extent inhibited under either wet or dry conditions. In this case, it is not the input but the rate of decomposition that changes with soil moisture, resulting in a different net increase in SOC. To test our hypothesis, we attempt to estimate the theoretical time of effective microbial decomposition per year based on soil moisture and soil temperature data for our three sites. Correlation analysis will be used to test this indicator of microbial activity for the effect of dead wood on SOC.

Our results should sharpen the picture of the dead wood’s role for long-term C stabilization in forest soils and how this process is affected by differences in the soil moisture status. They will give implications for climate mitigating forest management.

How to cite: Schäfferling, R., Zeh, L., Wordell-Dietrich, P., Azekenova, A., Koller, A., Stutz, K., Feger, K.-H., Julich, S., von Oheimb, G., and Kalbitz, K.: Soil moisture determines dead wood effects on soil organic matter in temperate beech forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1152, https://doi.org/10.5194/egusphere-egu24-1152, 2024.

EGU24-1321 | ECS | Posters on site | SSS5.2

A demonstration of the compositional stability of saline-hosted sedimentary carbon in a coastal wetland 

Mollie Lowrie, Mark Schuerch, Jack Lacey, and Daniel Magnone

Tidal wetlands sequester around ~4.8-87.2 Tg of carbon per year1 and represent approximately 25% of the global carbon sink, as a result of high inputs of organic matter and slow below-ground decomposition. The rate of carbon storage is hypothesised to be linked to the composition, particularly the relative oxidation, of soil organic carbon and the relationship with the sediment mineral matrix. The complex and dynamic biogeochemical processes governing tidal wetland carbon are not yet fully understood and therefore, the aim of this research was to understand how the composition of organic material varies across a tidal wetland and how this in turn is related to source, mineralogy and salinity.

Topsoil (0-20cm) and subsoil (20-40 cm) samples were collected from three marshes along a transect representing a salinity, inundation and elevation gradient and were analysed to assess the variations of SOC source, prevalence and composition, as well as the influence of salinity and sediment mineral composition on SOC stabilization.

SOC in the saline environments was highly oxidised with a low oxidation potential and thus had a particularly stable composition. In contrast, the carbon in the freshwater marsh was significantly less oxidised and thus demonstrated a greater potential for CH4 and CO2 emission. Carbon isotope (δ13C) and C:N analysis revealed that the SOC in all sites was produced in-situ by C3 plants, but highlighted differences between the photosynthetic pathway of the vegetation in each marsh. The freshwater marsh carbon was also more δ13C depleted, indicative of methane-consuming organisms and we hypothesise this variation in production pathway links to oxidation state.  

The compositional stability of SOC affected overall concentrations with the highest concentration of SOC in the first 20 cm of sediment in the high saltmarsh (between 0.35% and 5.34% w/w) and the lowest concentration of SOC in the lower 20-40 cm of sediment of the freshwater marsh (0.4% - 2.7% w/w). SOC prevalence is also positively associated with Fe-Al clay minerals, which was the dominant sediment type in the saltmarshes, whereas the freshwater marsh was predominantly siliceous sediment.

We conclude that the relative stability and concentration of SOC is greatest in the saltmarshes compared to the freshwater marsh. This aligns with emerging theory that mineral association is an important pathway of SOC stabilisation, and that salinity may exhibit a positive effect on cation bridging between organic material and mineral surfaces.

Acknowledgements: This project received funding from the National Environmental Isotope Facility (# 2656.0424).

References: Mcleod, E., Chmura, G. L., Bouillon, S., Salm, R., Björk, M., Duarte, C. M., Lovelock, C. E., Schlesinger, W. H., and Silliman, B. R.: A blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in sequestering CO2, Frontiers in Ecology and the Environment, 9, 552–560, https://doi.org/10.1890/110004, 2011. 

How to cite: Lowrie, M., Schuerch, M., Lacey, J., and Magnone, D.: A demonstration of the compositional stability of saline-hosted sedimentary carbon in a coastal wetland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1321, https://doi.org/10.5194/egusphere-egu24-1321, 2024.

EGU24-1635 | ECS | Posters on site | SSS5.2

The impact of land use change on soil organic carbon pools: A multi-method assessment 

Marcus Schiedung, Pierre Barré, and Christopher Poeplau

Soil organic carbon (SOC) is significantly affected by land use change (LUC), which can lead to either SOC losses or gains. In consequence, LUC is a major controlling factor of total SOC contents and its dynamics. In general, LUC from forest or grassland to permanent cropland results in losses of SOC, while the reverse can result in long-term gains. Several methods have been developed to assess distinct SOC pools. This includes particle size separation, thermal analysis and soil reflectance spectroscopy. The responses of such defined SOC pools to LUC have rarely been studied comprehensively, while doing so is a straightforward way to reveal their biogeochemical relevance. Here we used 23 sites covering six different LUC (i.e. forest-cropland, grassland-cropland, grassland-forest, cropland-grassland, cropland-forest and cropland-perennial Miscanthus) to assess SOC pool changes. We used particle size fractionation to obtain coarse (>50µm) and fine (<50µm) fractions and Rock-Eval 6 analysis to estimate active and stable SOC pools. Additionally, we used mid-infrared spectroscopy (Diffusive Reflectance Infrared Fourier Transformed Spectroscopy (DRIFT)) on bulk soils and particle size fractions to determine the relative SOC composition.

All methods identified kinetically different SOC pools across all LUC. The fine particle size fraction, representing a stabilized and slow cycling SOC pool, was more responsive to LUC compared to the stable pool estimated using Rock-Eval. Assessing the relative changes of total SOC and organic carbon contents of the fractions across all LUC, showed that the fine particle fraction follows closely the total SOC changes (R2=0.91 with slope of 0.77). In comparison, the stable pool extracted by Rock-Eval was less dynamic (R2=0.72 with a slope of 0.43). Absolute changes in bulk SOC were well described by the absolute organic carbon change of extracted Rock-Eval pools (active: R2=0.99 and stable: R2=0.91), while organic carbon changes of the particle size fractions were less sufficient to describe bulk SOC changes (coarse: R2=0.77 and fine: R2=0.33). The SOC composition, determined by DRIFT, revealed that changes in the relative composition of fast cycling aliphatic to slow cycling aromatic compounds can well explain relative total SOC changes (R2=0.81). This shows that three conceptually different methods (physical, thermal and spectroscopic) are suitable to determine SOC pool changes for a large diversity of LUC, but the sensitivity of the individual pools can differ strongly, depending on the method.

How to cite: Schiedung, M., Barré, P., and Poeplau, C.: The impact of land use change on soil organic carbon pools: A multi-method assessment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1635, https://doi.org/10.5194/egusphere-egu24-1635, 2024.

Given that microbial mediated input of crop residues and their humification products may be more conducive to the transformation and sequestration of soil organic matter. The study aims to use 13C15N double labeling tracing technology in incubation experiments to quantify the differences in the fate and distribution contribution of the C and N of crop residues and their decomposition products under the mediation of different exogenous microorganisms with different life strategies in soil organic matter (SOM) and dissolved organic matter (DOM). The study utilized exogenous microorganisms, such as Trichoderma reesei, Trichoderma harzianum, and Phanerochaete chrysosporium (K-strategists), as well as Bacillus subtilis (r-strategist). Additionally, a combination microbial treatment comprised of Trichoderma harzianum, Phanerochaete chrysosporium, and Bacillus subtilis was also employed. The study also aims to reveal the variation patterns of soil active organic carbon and humic carbon components in response to different exogenous microorganisms. The main conclusions of the study are as follows:

  • The addition of exogenous k-strategy microorganisms was more favorable than r-strategy microorganisms in mediating the increase in soil SOM contribution of crop residues derived C and N.Trichoderma treatments were more adept at mediating crop residues derived dissolvd organic carbon, and k-strategy microorganisms were more likely to stimulate soil production of dissolved nitrogen. Although the combination microbial treatment was the most effective at translational immobilization of crop residues in SOM, the Trichoderma reesei treatment had the best ability to increase soil organic carbon content by mediating crop residues translational immobilization with the lowest depletion of SOM. In addition, the addition of K-strategy microorganisms was more effective than r-strategy microorganisms in increasing the content of labile organic carbon and humic carbon fractions in the soil.
  • Fungimediated humification products was significantly better than bacterial and no microbe mediated for translational immobilization in soil, and the fungal treatments contributed more to DOM and stimulated soil deriving dissolved nitrogen. The Trichoderma reesei treatment was the most effective in immobilizing the carbon and nitrogen dereived from humification products. Fungi mediated humification products was superior to bacteria in boosting labile organic carbon and humic acid fractions. The Trichoderma reesei treatment was the most effective in boosting contents of easily oxidizable organic carbon, microbial biomass carbon and humic acid carbon, whereas the combination microbial treatments significantly increased fvlic acid carbon and substantially reduced PQ values in the early part of the experiment, and the three fungal treatments were effective in increasing fvlic acid carbon in the later part of the experiment.

In summary, these conclusions provide a theoretical basis for seeking suitable microbial regulation of farmland management measures to improve SOM transformation and humification effects and provide practical reference for scientifically guiding agricultural production and soil carbon sequestration and fertilization.

How to cite: Zhang, Y.: The impact of microbial-mediated crop residues and their humification products on transformation of soil organic matter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2329, https://doi.org/10.5194/egusphere-egu24-2329, 2024.

Soil contains three times more carbon (C) than the atmosphere and biosphere combined. It therefore represents an important tool for removal of carbon dioxide (CO2) from the atmosphere and its long term sequestration. However, in the current climate crisis, C that is already stored in soil reservoir represents a potential threat because different fractions of C in soil have different stability against the rising global temperatures. C is stored in soil in the form of soil organic matter (SOM) which is a mixture of many different organic components. Based on different properties we can divide SOM into two pools. The first pool is represented by small fragments of dead biomass referred to as free particulate organic matter (FPOM). The other pool is comprised of organic matter, usually chemically transformed or converted to microbial necromass, which is in various ways associated with soil mineral matrix. This pool is referred to as mineral associated organic matter (MAOM). It is assumed that MAOM becomes C saturated during soil development because it is limited by the amount of available mineral surfaces. FPOM, on the other hand, does not saturate and can therefore play an important role in later stages of soil development. Beside this some OM is stored in organic horizons in forest floor (Oe layer), which we expect will have similar pattern as FPOM. However, there is scarcity of studies that examine this assumption. In this work we studied the hypothesis that soils in different stages of development will differ in the amount of C stored in FPOM and MAOM fractions. On top of that, we assumed that this difference will be affected by the dominant tree species growing on the soil and the effect of tree species and soil age will not always be additive. We tested this hypothesis by analyzing C storage in soil and amount of C in FPOM and MAOM using two types of soils - recultivated spoil heap (immature soil) and forest soil in the surrounding area (mature soil). Plots with only one type of tree species (spruce or alder) in 3 replications were present on each of these soil types. Our results show that different tree species have different effects on the amount of C stored in mineral soil and Oe layer in immature and mature soils. In mineral soil more, C was sequestered under alder on recultivated heap, while in the surrounding area no difference between tree species was found. In Oe layer more C was sequestered under spruce in both types of soils. Soils did not differ in the amounts of FPOM and MAOM present in soil, but they did differ in the amount of C stored in these fractions. In young soil, MAOM fraction stored more C under alder than spruce. For mature soil the opposite was true. For FPOM fraction no significant effect of tree species or soil age was found but in young soil higher C storage in FPOM was found under alder compared to spruce.

How to cite: Hüblová, L. and Frouz, J.: Sequestration of soil organic matter in broadleaf and coniferous forests in soil at various stages of pedogenesis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2696, https://doi.org/10.5194/egusphere-egu24-2696, 2024.

EGU24-3039 | Posters on site | SSS5.2

Effect of topsoil dilution on stabilization of plant derived carbon 

Maire Holz, Bryan Salzmann, Rainer Remus, Valerie Pusch, Eva Mundschenk, Mathias Hoffmann, and Jürgen Augustin

Soil tillage often results in tillage erosion in hilly croplands, i.e. to subsoil incorporation into topsoil. However, up to now effect of tillage erosion on the turnover and stabilization of freshly added plant material remains poorly understood. We therefore conducted an incubation experiment comparing topsoil, diluted topsoil and subsoil from an erosion effected field site in north-east Germany. (14)CO2 respiration was traced over a period of 33 days after addition of 14C labelled plant residues and (14)C incorporation into several C fractions was studied. The topsoil showed increased C turnover compared to subsoil, however, topsoil dilution resulted in slightly higher C fluxes than in the topsoil, indicative of a more diverse microbial community. The addition of plant residues induced increased decomposition of native soil organic matter, resulting in a priming effect of similar magnitudes in all treatments ranging around 20%. This indicated that C might not be preferentially stabilized in the studied diluted topsoils or in the subsoil. In terms of carbon fractionation, topsoil dilution primarily affected the POM and MAOM (< 20 µm) fractions, with a decline in the order of topsoil > diluted > subsoil. Freshly assimilated carbon was preferentially stabilized in the MAOM fraction (<20µm), especially in subsoils, indicating potential for carbon stabilization in these soils. Overall we observed small effects of topsoil dilution on soil C storage, however, it's important to note that this study used shoot material, which is less intensively retained in soil compared to root material. Topsoil dilution seems to be a promising way to enhance C sequestration but further research is needed to assess its effectiveness for long-term soil carbon sequestration and to evaluate the role of root-derived carbon in these processes.

How to cite: Holz, M., Salzmann, B., Remus, R., Pusch, V., Mundschenk, E., Hoffmann, M., and Augustin, J.: Effect of topsoil dilution on stabilization of plant derived carbon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3039, https://doi.org/10.5194/egusphere-egu24-3039, 2024.

EGU24-3492 | Orals | SSS5.2

Microbial and mineral interactions decouple litter quality from soil organic matter formation  

Jeanette Whitaker, Kelly Mason, Ashley Taylor, Pengzhi Zhao, Tim Goodall, Rob Griffiths, Niall McNamara, and Dafydd Elias

Mineral-associated organic matter (MAOM) forms from plant or microbial-derived compounds and comprises the largest reservoir of soil organic carbon (SOC) globally.  Most SOC is associated with soil minerals and mineralogy is considered a primary control on SOC persistence due to variations in mineral reactivity. However, most mineral-associated SOC is microbial in origin thus microbial residue formation, through the processing of plant inputs, may also control SOC dynamics. Current understanding suggests that litter quality controls the formation of MAOM with high-quality litter producing more microbial residues which are then stabilised on mineral surfaces. We hypothesized that inputs of high-quality litter would lead to a net increase in MAOM stocks, relative to low-quality litter, through more efficient formation of MAOM and less priming of existing SOC.  We also hypothesised that soil mineralogy would act as the primary control on the formation of MAOM relative to litter quality. To test our hypotheses, we amended an agricultural soil with common soil minerals (Kaolinite, Montmorillonite and unamended control) and incubated these amended soils in the laboratory with two surface-applied 13C labelled litters of contrasting qualities (high quality - White Clover and low quality - Winter Wheat). During the incubation, litter decomposition and priming were quantified by δ13CO2 analysis. After 4 months, mineral stabilisation of litter-C, the amounts of particulate organic matter (POM) remaining and litter-C assimilated into microbial biomass were all quantified, along with characterisation of the soil microbial communities. Soil mineralogy strongly influenced the efficiency of MAOM formation, with Montmorillonite-amended soils respiring less litter-C and stabilising more as MAOM. High quality litter led to less (not more) efficient production of MAOM due to soil microbial community shifts associated with lower carbon-use efficiency. Low-quality litter enhanced priming of pre-existing SOC, counterbalancing the effect of litter quality on MAOM stocks.  Taken together, our findings demonstrate that soil mineralogy was the primary control on MAOM formation and that litter-microbial interactions determine the effect of litter quality on MAOM.  These findings refute the hypothesis that high-quality plant litters form MAOM most efficiently and demonstrate that mineral and microbial interactions regulate the formation of stable SOC.

How to cite: Whitaker, J., Mason, K., Taylor, A., Zhao, P., Goodall, T., Griffiths, R., McNamara, N., and Elias, D.: Microbial and mineral interactions decouple litter quality from soil organic matter formation , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3492, https://doi.org/10.5194/egusphere-egu24-3492, 2024.

Most of the organic carbon (C) in soil is linked to various degrees with the mineral matrix, which includes the formation of aggregates and the association of organic C with clay minerals and Fe and Al hydro(oxides). Both mechanisms ensure the physical stabilization of organics against microbial decomposition and the stability of the soil system. The present work analyzed the processes of C stabilization, and C flows between the aggregate size classes of macro- and macroaggregates and density fractions (free and occluded light (FL, OL), occluded dense (OD) and mineral (MF)) based on the 13C natural abundance approach using 73 published works and looked at the two groups of factors: i) internal (edaphic soil properties) and ii) external (type of land use and climate).

The global pattern showed the relative enrichment of 13C in silt + clay fraction for 0.4‰ and MF for 0.25-0.6‰ compared to bulk soil. In contrast, organics in micro- and macroaggregates and FL and OL fractions were 13C depleted, reflecting the fast decomposition of these pools and input of fresh plant-derived organics. The difference in 13C enrichment between the OL and MF fractions was 1.3‰, whereas between macroaggregates and silt+clay fraction 0.6‰, showing that density fractionation could more accurately reflect the intensity of organic C processing by microorganisms and fractions are more homogeneous in composition than aggregates.

The 13C enrichment in silt + clay and MF increased with the clay content; the difference between the 13C enrichment for OL and both dense fractions and macroaggregates and silt + clay fractions rose. Forests, grasslands, and croplands showed the same trend of increasing 13C enrichment with decreasing aggregate size classes; grasslands and croplands showed higher enrichment of silt+clay associated C (~0.3‰ relative to bulk soil) than forests. Under grasslands and forests, 13C enrichment in OD and MF was higher than in agriculture, showing deep microbial processing of organic matter without structure disturbance. The differences in 13C enrichment of organic matter between the aggregate size classes (0.6-0.9‰) and density fractions (2.5-3‰) were higher under subtropical and tropical climates, compared to temperate and Mediterranean, reflecting more intensive recycling of organic matter by microorganisms.

C flows between the aggregates followed the trend from macroaggregates to silt+clay fraction and from large macro- to microaggregates, reflecting the well-known sequential formation of soil structure and macro aggregates' role in stabilizing plant residues. More intensive C flows were found from FL to MF, compared to the C flow from OD to MF, pointing to the importance of plant-derived organics and microbial metabolites for the formation of MF. Thus, the global pattern of organic C transformation identified that the 13C natural abundance approach could be used for a broad range of automorphic soil types and can open a new perspective for the estimation of processes of C recycling and reveal the intensity of microbial processes depending on the land use, soil edaphic factors and climate.

How to cite: Gunina, A., Wang, Y., and Kuzyakov, Y.: 13C natural abundance approach for analysis of steps of organic carbon transformation in soil: application for various ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4695, https://doi.org/10.5194/egusphere-egu24-4695, 2024.

EGU24-5359 | ECS | Orals | SSS5.2

Cover Crops Affect Pool Specific Soil Organic Carbon in Cropland – a Meta-analysis 

Julia Fohrafellner, Katharina Keiblinger, Sophie Zechmeister-Boltenstern, Rajasekaran Murugan, Heide Spiegel, and Elena Valkama

Cover crops (CC) offer numerous benefits to agroecosystems, particularly in the realm of soil organic carbon (SOC) accrual and loss mitigation. However, uncertainties persist regarding the extent to which CCs, in co-occurrence with environmental factors, influence SOC responses and associated C pools. We therefore performed a weighted meta-analysis on the effects of CCs on the mineral associated organic carbon (MAOC), the particulate organic carbon (POC) and the microbial biomass carbon (MBC) pool in arable cropland. Our study summarized global research of comparable management, with a focus on climatic zones representative of Europe, such as arid, temperate and boreal climates. 
    In this meta-analysis, we included 71 independent studies from 61 articles published between 1990 and June 2023 in several scientific and grey literature databases. Sensitivity analysis was conducted and did not identify any significant publication bias. The results revealed that CCs had an overall statistically significant positive effect on SOC pools, increasing MAOC by 4.8% (CI: 0.6% - 9.4%, n = 16), POC by 23.2% (CI: 13.9% - 34.4%, n = 39) and MBC by 20.2% (CI: 11.7% - 30.7%, n = 30) in the top soil, compared to no CC cultivation. Thereby, CCs feed into the stable as well as the more labile C pools. The effect of CCs on MAOC was dependent on soil clay content and initial SOC concentration, whereas POC was influenced by moderators such as CC peak biomass and experiment duration. For MBC, e.g., clay content, crop rotation duration and tillage depth were identified as important drivers. 
    Based on our results on the effects of CCs on SOC pools and significant moderators, we identified several research needs. A pressing need for additional experiments exploring the effects on CCs on SOC pools was found, with a particular focus on MAOC and POC. Further, we emphasize the necessity for conducting European studies spanning the north-south gradient. 
    In conclusion, our results show that CC cultivation is a key strategy to promote C accrual in different SOC pools. Additionally, this meta-analysis provides new insights on the state of knowledge regarding SOC pool changes influenced by CCs, offering quantitative summary results and shedding light on the sources of heterogeneity affecting these findings.

How to cite: Fohrafellner, J., Keiblinger, K., Zechmeister-Boltenstern, S., Murugan, R., Spiegel, H., and Valkama, E.: Cover Crops Affect Pool Specific Soil Organic Carbon in Cropland – a Meta-analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5359, https://doi.org/10.5194/egusphere-egu24-5359, 2024.

EGU24-6188 | ECS | Posters on site | SSS5.2 | Highlight

Transformation and backfilling of peatland soils and effect on CO2 emissions 

Ciriaco McMackin, Luisa Minich, Wiesenberg Guido, Burgos Stéphane, and Egli Markus

Peatlands are the Earth's largest natural terrestrial carbon reservoir, storing more than 40% of all soil organic carbon. Despite their significance, damaged peatlands emerge as a major source of greenhouse gas emissions, contributing to nearly 5% of global anthropogenic CO2 emissions.

Peatlands have been drained in the Three Lakes region (Switzerland). These drainage efforts were initiated to develop agricultural land use and enhance the overall quality of life in the region. While the drainage improved living conditions, it also accelerated peat decomposition. This accelerated decomposition gave rise to a loss of soil, reaching up to 4 meters at specific locations, and drastically increased CO2 emissions.

Various strategies have been developed to reduce CO2 emissions from degraded peatland. Backfilling—the deposition of a mineral layer on the soil— is one promising method to mitigate CO2 emissions. Backfilling disconnects the peat from the surface soil by a mineral layer. CO2 emissions from the peat are diminished, while the surface soil can still be used for agricultural purposes.

Peatlands contain very old carbon preserved by water-logged conditions that limited carbon decomposition. We measured rates and radiocarbon (C14) signals of the CO2 emissions at three locations in the Three Lakes Region to compare the amount and age of carbon emitted from drained and drained-backfilled peatland soils. First results show that the backfilled peatland soils emit less and younger CO2 than peatland soils having no backfilling. The covered peatland still continues to degrade, however at a slower pace. The overed peat contributes to about 50% of the measured CO2 emissions from the transformed sites. Further investigation will be needed to identify the spatio-temporal variability and the influence of other factors such as the groundwater table level.

How to cite: McMackin, C., Minich, L., Guido, W., Stéphane, B., and Markus, E.: Transformation and backfilling of peatland soils and effect on CO2 emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6188, https://doi.org/10.5194/egusphere-egu24-6188, 2024.

EGU24-7874 | ECS | Posters on site | SSS5.2

Rapid analysis using Diffuse Reflectance Spectroscopy can enhance Soil Carbon Monitoring 

Sean Adam and Conrad Jackisch

To gain a better understanding of changes in soil carbon stocks and composition it is essential to have data on relevant soil properties with high temporal and spatial resolution. However, traditional laboratory analysis can be both time-consuming and expensive, ultimately limiting data availability. Mid-DRIFTS (Diffuse Reflectance Infrared Fourier Transformed Spectroscopy in the mid-IR range) is a cost-effective alternative to conventional analytical methods. It enables the simultaneous inference of multiple soil properties, such as soil organic carbon, nitrogen and phosphorus content, soil texture, and cation exchange capacity, from measured spectra. This makes it a valuable analytical tool for soil monitoring.

To successfully integrate mid-DRIFTS into a soil monitoring concept, a spectral library representative of the target is required as the basis for multivariate or machine-learning-based calibration models. Here, we want to present the initial results obtained using the BDF-SSL, a soil spectral library we created as the foundation for integrating mid-DRIFTS in agricultural soil monitoring in Saxony, Germany. The library's core consists of nearly 300 spectra obtained from retention samples from agricultural soil monitoring sites in Saxony, which were collected over the past 20 years.
We focused on the inference of soil carbon content, including three thermally derived carbon fractions (TOC400, ROC, TIC900) we measured according to DIN19539 by combustion. Additionally, we calibrated models for a wide range of other soil properties, such as soil texture, nitrogen and phosphorus content, elemental concentrations and cation exchange capacity. We used both Partial Least Squares Regression (PLSR), Cubist, and the Memory Based Learner (MBL) to calibrate the models.

Both Cubist and MBL consistently outperformed PLSR. Our models show high predictive accuracy for the carbon fractions, total nitrogen and phosphorous contents, cation exchange capacity and texture. In addition, we are also able to predict several elemental concentrations, such as Fe, Al, or Ni contents with high accuracy. Our results show that mid-DRIFT can be used to enhance spatial and temporal coverage of soil monitoring, allowing not only for more accurate estimations of soil carbon stocks and sequestration rates, but also for the rapid estimation of several other soil properties.

How to cite: Adam, S. and Jackisch, C.: Rapid analysis using Diffuse Reflectance Spectroscopy can enhance Soil Carbon Monitoring, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7874, https://doi.org/10.5194/egusphere-egu24-7874, 2024.

EGU24-8770 | ECS | Orals | SSS5.2

Influence of initial soil carbon content on the stabilization of new carbon: a 2-year lab incubation study 

Neha Begill, Axel Don, and Christopher Poeplau

The hotly debated concept of carbon (C) saturation in mineral soils not only affects our understanding of soil organic matter (SOC) dynamics but also holds critical implications for negative emissions strategies. Many recent studies have indicated that soil’s capacity to store and stabilize C in mineral form depends on the initial SOC content, i.e., the soil C saturation deficit. According to these studies, low-C soils are suggested to have a higher potential for SOC storage compared to high-C soils. In light of these considerations, our hypothesis presents a different viewpoint, suggesting that initial C content in soils mainly affects the absolute loss of old carbon (following first-order kinetics), while it will not significantly impact the soil’s ability to stabilize new C. To investigate this experimentally, we selected soils from the first German Agricultural Soil Inventory with varying C contents (0.7–14.5%) and three different soil textures (light to heavy). These soils were then incubated in air-tight glass jars, where the same amount of 13C labeled litter was added, along with an unamended control of each sample. After two years, soils were dried and physically fractionated into mineral-associated organic carbon (MAOC) and particulate organic carbon (POC) using a size-cutoff of 20µm to find and δ13C as well as total SOC was measured. Here, we will present the first results from this lab incubation experiment, providing further systematic insights into whether the amount of initial carbon content or the ‘saturation C’ deficit truly affects the SOC dynamics with varying amounts of C contents in it.

How to cite: Begill, N., Don, A., and Poeplau, C.: Influence of initial soil carbon content on the stabilization of new carbon: a 2-year lab incubation study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8770, https://doi.org/10.5194/egusphere-egu24-8770, 2024.

EGU24-8970 | Orals | SSS5.2

Coupling scales in process-based soil organic carbon modeling including dynamic aggregation 

Alexander Prechtel, Simon Zech, and Nadja Ray

Background: Carbon storage and turnover in soils depend on the interplay of soil architecture, microbial activities and soil organic matter dynamics. For a fundamental understanding of the mechanisms that drive these processes, not only the exploitation of advanced experimental techniques down to the nanoscale is necessary, but also spatially explicit and dynamic image-based modeling at the pore scale.
We present a modeling approach which is capable of transferring microscale information into macroscale simulations at the profile scale. This enables the prediction of future developments of carbon fluxes and the impact of changes in the environmental conditions linking scales.
We consider a mathematical model for CO2 transport across soil profiles (macroscale) which is informed by a pore-scale (microscale) model for C turnover. It allows for the dynamic, self-organized re-arrangement of solid building units, aggregates and particulate organic matter (POM) based on surface interactions, realized by a cellular automaton method, and explicitly takes spatial effects on POM turnover such as occlusion into account. We further include the macroscopic environmental conditions water saturation, POM content, and oxygen concentration.

The coupled simulations of macroscopic transport and pore scale carbon and aggregate turnover reveal the complex, nonlinear interplay of the underlying processes. Limitations by diffusive transport, oxygen availability, texture dependent occlusion and turnover of OM drive CO2 production and carbon storage.

Zech, Prechtel, Ray (2024): Coupling scales in process-based soil organic carbon modeling including dynamic aggregation. J. Plant Nutr. Soil Sci.

How to cite: Prechtel, A., Zech, S., and Ray, N.: Coupling scales in process-based soil organic carbon modeling including dynamic aggregation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8970, https://doi.org/10.5194/egusphere-egu24-8970, 2024.

EGU24-9176 | Posters on site | SSS5.2

Carbon Sequestration and Mitigation of Agricultural Greenhouse Gas Emissions through management: Insight from an incubation experiment 

Sobia Bibi, Hassan Ahmad, Wolfgang Wanek, Mohammad Zaman, Magdeline Vlasimsky, Maria Heiling, Reinhard Pucher, and Gerd Dercon

Climate change poses a significant threat to soil quality and global food security, with projections indicating potential crop yield declines of 17% by 2050. Simultaneously, agriculture contributes to an estimated 24% of all greenhouse gas (GHG) emissions. The dynamics of carbon (C) and nitrogen (N) play a pivotal role in GHG emissions and soil C sequestration, yet further research is needed on how management practices influence these dynamics.

 

To address these challenges and provide data can facilitate efficient resource utilization in agricultural production, an incubation experiment was conducted to provide data on the impact of management options on C sequestration and GHG emissions from agricultural soils. The experiment took place in 850 mL glass jars under controlled conditions at 60% water-filled pore space and a temperature of 25°C. Composite soil samples, derived from a moderately fertile soil (2-3% SOC) from Grabenegg, Austria, at a depth of 0-15 cm, were subjected to five treatments: 1) control, 2) labeled urea, 3) inhibitor and labeled urea, 4) biochar + 15N labeled urea, and 5) inhibitor and biochar and labeled urea.

 

The 15N-labeled urea (5% atom excess) was applied at a rate of 150 kg N ha-1, while biochar was applied at 2% of the soil by dry mass basis. A neon inhibitor which includes NBPT to limit nitrogen loss into the atmosphere as ammonia and DCD to reduce leaching, were applied at a rate of 4 mL per 100g urea as instructed by the manufacturer. All treatments were replicated four times. Soil and gas samples were collected on days 1, 3, 8, 15, 24, 31, 38, 45, 52, and 59 after treatment application. Gas samples were collected over a two hour period each day. Soil samples were analyzed for pH, soluble organic C, and mineral-N (NH4+, NO3-), while gas samples were analyzed using a gas chromatograph (GC) for NO2, CO2, and CH4.

 

Preliminary results indicate that the addition of biochar increased soil C content, aligning with expectations from prior studies and that the addition of the inhibitor had a discernible impact on the pathways of nitrogen in the study samples. The use of isotopic methods and GHG measurements can furnish critical data supporting the most efficient use of resources for both climate mitigation and adaptation.

 

How to cite: Bibi, S., Ahmad, H., Wanek, W., Zaman, M., Vlasimsky, M., Heiling, M., Pucher, R., and Dercon, G.: Carbon Sequestration and Mitigation of Agricultural Greenhouse Gas Emissions through management: Insight from an incubation experiment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9176, https://doi.org/10.5194/egusphere-egu24-9176, 2024.

EGU24-9202 | ECS | Posters on site | SSS5.2

Assessing inert pool models for estimating long-term biochar stability in soil 

Haichao Li, Elias S. Azzi, Cecilia Sundberg, Erik Karltun, and Harald Cederlund

Estimating the long-term stability of biochar in soil often relies on extrapolating mineralization data from short-term laboratory incubations. Various models such as single first-order (SFO), double first-order (DFO), triple first-order (TFO) and the power model have been employed for this purpose, all of which have an inherent assumption that biochar is completely biodegradable. However, recent insights challenge this assumption by highlighting that biochar consist largely of highly condensed aromatic structures, which have been proposed to be essentially inert. If biochar were resistant to microbial degradation it would make sense if this was reflected in the choice of model used. Therefore, our aim was to assess whether the proposed inert pool models (SFO+I and DFO+I) fit the data better compared to existing models (SFO, DFO, TFO and power model) using a recently compiled extensive dataset. We hypothesized that models incorporating an inert pool would fit better (or at least comparably well) to incubation data compared to the existing models and give more reliable long-term predictions. As a way of assessing the model’s predictive ability, we fitted them to progressively shortened incubation times derived from the longest biochar incubation data sets available, and then evaluated how well they extrapolated to the full measured range. Our results indicated that the proposed DFO+I model did indeed fit better than the both DFO and TFO models. Moreover, predictions of BC100 (% of carbon remaining after 100 years) by the inert pool models and by the power model displayed stronger correlations with the biochar stability indicator (H/C ratio) than both SFO and DFO models, which aligns with our initial hypothesis. However, the power model in general outperformed all other models, including the inert pool models, with the highest number of best fits. From our extrapolation exercise, it is clear the DFO model, which has been most widely used to date, substantially underestimated biochar stability in the longer term while the inert pool models tended to overestimate it. This uncertainty appears to be quite severe when fitting inert pool models to incubation data from non-pyrolysed materials. By comparison, the power model appeared to be more robust when estimating biochar persistence in soils. From these results we cannot conclusively confirm nor reject the idea of inert pool models. It is possible that an inert-pool model is the more suitable choice for extrapolating biochar decomposition data. However, it is clear from their tendency to overestimate stability of biodegradable materials. Our current understanding is hampered by the fact that the incubation data set available contains a high proportion of biochars produced at relatively modest temperatures and by a lack of chemical/structural characterization of the incubated biochars. Future research could remedy this by providing better information on the degree of aromatic condensation/proportion of inertinite in incubated biochars samples. For now, we recommend the power model as the most robust option.

How to cite: Li, H., Azzi, E. S., Sundberg, C., Karltun, E., and Cederlund, H.: Assessing inert pool models for estimating long-term biochar stability in soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9202, https://doi.org/10.5194/egusphere-egu24-9202, 2024.

EGU24-9216 | Orals | SSS5.2 | Highlight

Net primary production rather than saturation of mineral surfaces limits soil carbon sequestration  

Christopher Poeplau, Rene Dechow, Neha Begill, and Axel Don

Accrual of soil organic carbon (SOC), and especially the formation of mineral associated organic carbon (MAOC), has a large theoretical potential to act as sink for atmospheric CO2. For reliable estimates of this potential and efficient policy advice, the major limiting factors need to be understood. The positive correlation between the content of fine mineral particles (silt + clay) and the content of MAOC is widely used to estimate a general maximum MAOC storage capacity of soils, based on the notion that mineral surfaces get C saturated. However, recent literature raised doubts about the concept of C saturation and it remains unclear, if and to what extent the mineral capacity of soils to stabilise C limits SOC accrual. Here, using large scale soil datasets and the model RothC, we provide two independent lines of evidence, that the upper boundary line of the correlation between MAOC and silt and clay does not resemble a maximum mineralogical SOC stabilisation capacity. 1. In coarse-textured soils, the C loading of the silt and clay fraction was found to strongly overshoot the mentioned upper boundary line and thus exceed previous C saturation estimates. 2. A global modelling exercise revealed that only for 28.8 % of all soils, local net primary production (NPP) would be sufficient to reach a C loading of 80 g C kg-1 silt and clay, which is currently assumed to be the maximum capacity of soils to stabilise C. This proportion decreased strongly with increasing silt and clay content, which revealed that high C loadings can hardly be reached in more fine-textured soils. We conclude that SOC accrual is mainly limited by C inputs and strongly modulated by texture, mineralogy and climatic conditions. Taken together, those factors could be used to be formulate an ecosystem capacity to stabilise SOC. However, a potential C saturation point of MAOC appears still unknown and of no relevance for strategies of climate mitigation via SOC sequestration.

How to cite: Poeplau, C., Dechow, R., Begill, N., and Don, A.: Net primary production rather than saturation of mineral surfaces limits soil carbon sequestration , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9216, https://doi.org/10.5194/egusphere-egu24-9216, 2024.

EGU24-9335 | ECS | Posters on site | SSS5.2

Andosol genesis: Transition from silandic to aluandic properties and the related changes in organic carbon storage 

Antonia Zieger, Klaus Kaiser, and Martin Kaupenjohann

Andosols are commonly subdivided according to silandic and aluandic features. Both subgroups are considered to be end members of the Andosol genesis. Silandic Andosols are characterized by organic matter (OM) strongly bound to imogolite-type material (ITM), while Aluandic Andosols mainly consist of aluminium-OM complexes (Al-OM complexes). According to current theory, silandic and aluandic properties are direct results of primary weathering, assuming two separate lines of genesis.

Our previous results, however, suggest that silandic horizons can transform into aluandic over time, resulting in additional carbon accumulation. This is likely caused by dissolved organic matter (DOM) entering the subsoil with the percolating soil solution, masking dissolved aluminium as soluble Al-OM complexes. This promotes the dissolution of ITM, releasing aluminium. The latter reacts with DOM, inducing the formation of insoluble, Al-OM complexes, which then precipitate.

To test this hypothesis, we conducted a long-term percolation experiment with material of an Ecuadorian Andosol formed in a homogeneously tephra deposit. This soil exhibits aluandic properties in the topsoil and silandic properties in the subsoil. Ions, pH, and DOC in the feed and eluate solution were monitored over a period of 18 months. The convection-dispersion-equation as implemented in HYDRUS-1D was used to model the percolation experiment as a one-dimensional standard reactive solute transport.

Our results revealed a strong carbon accumulation of 14 g·kg-1 in the silandic material after 18 months, with the vertical transport of Al-OM complexes only explaining up to 33 % of the carbon accumulation. The HYDRUS-1D model revealed that sorption of DOM dominates at the beginning of the experiment and explains up to 40 % of carbon accumulation (including vertically transported Al-OM complexes). For the silandic material, the results indicate that up to 91% of the carbon accumulation are due to ITM dissolution and subsequent formation of insoluble Al-OM complexes.

In summary, our findings support the hypothesis, that ITM dissolution and the subsequent formation of Al-OM precipitates significantly contribute to the increase in carbon concentration in the silandic material, while the above aluandic material did not change.

How to cite: Zieger, A., Kaiser, K., and Kaupenjohann, M.: Andosol genesis: Transition from silandic to aluandic properties and the related changes in organic carbon storage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9335, https://doi.org/10.5194/egusphere-egu24-9335, 2024.

EGU24-9389 | ECS | Orals | SSS5.2 | Highlight

Cover crop´s carbon inputs to soils via aboveground and root biomass as affected by species, mixtures and sowing date 

Laura Reinelt, Nicole Christin Maack, Henrike Heinemann, and Axel Don

An increased use and optimised management of cover crops is a promising way to promote soil organic carbon accrual in agricultural soils. However, data is lacking on aboveground and especially root biomass of important cover crop species depending on the length of their cultivation window and on climatic conditions. We sampled aboveground and root biomass in a German field trial covering twelve common cover crop species and eight commercially available seed mixtures in 2021, a year with a rather wet summer, and 2022, a year with a rather dry summer. Each species and mixture were sown at three different dates and were sampled in early November, after having grown for 8 to 14 weeks.

Root and shoot biomass differed significantly between species, years and sowing dates. Oil radish, Phacelia, Bristle oat and Italian rye-grass had the highest root biomass. Cover crop mixtures did not have significantly higher aboveground or root biomass than single species. Aboveground biomass was 60% lower in 2022 compared to 2021 and root biomass on average 52% lower. Biomass generally decreased substantially with later sowing dates, by up to 80%. In 2021, the root to shoot ratio decreased by on average 41% from the earliest to the latest sowing date.

Based on the results of our study, management recommendations can be given regarding the selection and management of cover crop species for soil carbon accrual. Our data is also useful for more accurate mechanistic modelling of the soil carbon dynamics under different agricultural management scenarios. We conclude that there is a large optimisation potential for cover crop cultivation in Europa that could reveal a significant soil carbon sequestration potential.

How to cite: Reinelt, L., Maack, N. C., Heinemann, H., and Don, A.: Cover crop´s carbon inputs to soils via aboveground and root biomass as affected by species, mixtures and sowing date, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9389, https://doi.org/10.5194/egusphere-egu24-9389, 2024.

EGU24-10155 | ECS | Posters on site | SSS5.2

Impact of cover crops and conventional and reduced tillage on plant productivity in a bicultural maize-oat cropping system 

Giulia De Luca, Eszter Sugar, Nándor Fodor, Tamás Árendás, Péter Bónis, and Renáta Sándor

Agricultural crop production plays a key role in satisfying the increasing food demand of our ever-growing population. However, continuous production and certain land use practices often result in the depletion of soil quality. This revelation developed a need to improve soil fertility by enhancing carbon sequestration and storage in our cultivated fields using different methods.

Even though the application of green manure crops can significantly increase the amount of carbon stored in the soil while improving its water storage capacity and protecting the surface from erosion, it is still not a widespread method in Hungary due to usual water shortage during their sowing and germination periods. Furthermore, different soil management techniques can also alter the quality and carbon sequestration potential of our soils. The objective of our study is to determine how soil management and the usage of catch crop cover may affect crop productivity.

A maize-oat bicultural field trial with two different soil management techniques (conventional ploughing and reduced tillage) combined with four types of cover crops (fallow, trefoils-buckwheat mixture, phacelia and oilseed radish) was established in 2020. Changes in soil water content and temperature were continuously monitored at three depths (5, 25 and 45 cm), while leaf area index (LAI) and chlorophyll content (SPAD) were measured periodically. At the end of the vegetation periods measurements regarding crop quality and quantity were executed as well. Furthermore, soil respiration and additional (soil penetration resistance, SWC, VIgreen index) measurements were carried out during the study period, these results will be presented in a separate poster (Effect of cover cropping and soil tillage on soil CO2 emissions).

Our results showed that differences between treatments regarding management techniques and cover crops are more characterized in maize than in oat.

How to cite: De Luca, G., Sugar, E., Fodor, N., Árendás, T., Bónis, P., and Sándor, R.: Impact of cover crops and conventional and reduced tillage on plant productivity in a bicultural maize-oat cropping system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10155, https://doi.org/10.5194/egusphere-egu24-10155, 2024.

EGU24-10379 | Orals | SSS5.2

Climate conditions control the SOC sequestration potential of agricultural terraces 

Pengzhi Zhao, Daniel Fallu, Sara Cucchiaro, Ben Pears, Andreas Lang, Paolo Tarolli, Sebastian Doetterl, Jeanette Whitaker, Tony Brown, and Kristof Van Oost

Agricultural terraces, being among the volumetrically largest and most common man-made landforms, have been widely implemented to support essential soil ecosystem services, e.g., erosion control, soil nutrient, and water retention, and have had an essential impact on soil organic carbon (SOC) stock and its exchange with the atmospheric C. However, the direction and magnitude of this impact remain highly uncertain. By integrating the broad-scale field observations of 14 terrace sites across the EU with a global data synthesis, we demonstrate that the effectiveness of terracing-driven SOC sequestration potential is intricately controlled by climate conditions that govern in-return soil properties.

Our findings reveal that the terracing practices represent a promising land management strategy for enhancing SOC sequestration, but also that risks of SOC loss exist when building terraces under arid climate, where they could be potentially very beneficial to crop productivity and SOC storage. We recommend that future terrace construction should integrate water and nutrient recycling techniques to ensure soil moisture and nutrient availability, enhancing land productivity and maximizing SOC sequestration potential. Our data suggest that promoting the recovery of the lost topsoil C during terrace construction through increasing C inputs and C use efficiency, i.e., straw return and nutrient amendment is an efficient way to counteract initial SOC losses.

How to cite: Zhao, P., Fallu, D., Cucchiaro, S., Pears, B., Lang, A., Tarolli, P., Doetterl, S., Whitaker, J., Brown, T., and Van Oost, K.: Climate conditions control the SOC sequestration potential of agricultural terraces, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10379, https://doi.org/10.5194/egusphere-egu24-10379, 2024.

EGU24-10695 | Posters on site | SSS5.2

Effect of cover cropping and soil tillage on soil CO2 emissions 

Györgyi Gelybó, Giulia De Luca, János Balogh, Nándor Fodor, Szilvia Fóti, Eszter Sugár, and Renáta Sándor

It has long been in the focus of research interest how cover cropping affect water regime of the soil. However, its simultaneous effect on CO2 emission, i.e. soil respiration is not so widely reported. We examined an agricultural experiment set up as a maize-oat rotation under conventional and reduced tillage tillage and four different cover-cropping treatments (fallow, oilseed radish, mixture, phacelia) in Martonvásár (Hungary). Soil respiration measurements were carried out using infrared gas analyzer in 5 replicates per treatment plot (tillage-main-crop-cover crop combinations). Measurements covered two years in the different main crops and also in cover crops. A total of 10 measurement campaigns were organized in 2021 and 2022, which covered both main crops and cover crops. Meteorological parameters were measured in a nearby automatic meteorological station.

Besides soil respiration measurements ancillary measurements have been carried out to better characterize soil status. Using a penetrologger soil penetration resistance, using handheld sensors, soil water content measurements and soil temperature was recorded. Also, point scale continuous soil water content profile measurements were carried out. At each plot, vegetation was characterized using the VI green index derived from RGB imagery and periodically chlorophyll content (SPAD) and leaf area index was recorded. Here we analyze soil respiration, VI green soil temperature and soil water content measurements. The results showed differences between tillage treatments and between main crops. For further results please see abstract “Impact of cover crops and conventional and reduced tillage on plant productivity in a bicultural maize-oat cropping system”.

How to cite: Gelybó, G., De Luca, G., Balogh, J., Fodor, N., Fóti, S., Sugár, E., and Sándor, R.: Effect of cover cropping and soil tillage on soil CO2 emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10695, https://doi.org/10.5194/egusphere-egu24-10695, 2024.

EGU24-11164 | ECS | Orals | SSS5.2 | Highlight

Areas available for potential carbon sequestration in European agricultural soils 

Florian Schneider, Daria Seitz, Felix Seidel, and Axel Don

In order to estimate a feasible carbon (C) sequestration potential in European agricultural soils, we need to know the area where additional measures that increase soil organic carbon (SOC) can be implemented and the corresponding SOC accrual rates. In this study, we focus on the former and identify areas where promising SOC increasing practices can be implemented on European agricultural soils.

The practices considered include a higher share of agroforestry, cover crops replacing bare winter fallows, reduced tillage instead of ploughing and the integration of perennial legumes and leys into crop rotations. Open-access data of European Farm Structure Surveys as provided by EUROSTAT at NUTS2 level serve as a reference for the intensities at which the measures are already implemented in Europe. It was assumed that only the further spread of these measures could potentially sequester additional C in soils.

We argue that the adoption of reduced tillage is the practice that covers by far the largest area relevant for potential C sequestration in soils under current food, feed, and fibre demands. The replacement of bare winter fallow with cover crops is restricted to regions with sufficient growing degree days to allow a second crop after harvest. The introduction of more woody features like hedgerows and alley cropping to agro-ecosystems, as well as the integration of more perennial legumes or leys in present crop rotations creates the need for land reallocation and likely compromises agricultural productivity.

Overall, we conclude that reduced tillage may emerge as the most promising practice for atmospheric C sequestration in European agriculture despite its reported relatively low SOC accrual rate per hectare. Trade-offs between C sequestration in soils, agricultural production and agricultural demand warrant further inter-disciplinary attention.

How to cite: Schneider, F., Seitz, D., Seidel, F., and Don, A.: Areas available for potential carbon sequestration in European agricultural soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11164, https://doi.org/10.5194/egusphere-egu24-11164, 2024.

EGU24-11742 | ECS | Orals | SSS5.2 | Arne Richter Awards for Outstanding ECS Lecture

Digging into the Future: The transition between bedrock and soil as an underexplored frontier zone in geoscience 

Daniel Evans

Terrestrial environments and their ecosystems demand healthy, sustainable, and resilient soils. Over the past couple of decades, significant efforts have been made to safeguard global soils, yet the materials and resources responsible for soil formation have been widely overlooked.  The transition from bedrock to soil – a zone often described as ‘soil parent material’ – holds an exciting yet untapped potential for helping us address some of the largest environmental challenges, including climate change and the biodiversity crisis. In this award lecture, I will present a strand of my research programme ‘Building Tomorrow’s Soils’ which seeks to establish how soil parent materials enhance the sustainability, health, and resilience of soil systems. First, with a focus on carbon sequestration, I will highlight how the bedrock–soil transition zone has the potential to be a long-term store of organic carbon. I will then present research which shows that some soil parent materials release petrogenic (i.e. rock-derived) organic carbon into soils. These understudied inputs of organic carbon to soils are currently absent from most, if not all, soil carbon models, which threatens our ability to optimize soil carbon management in the long-term. Finally, I will argue that developing a mechanistic understanding about this transition zone – this underexplored material which is neither rock nor soil in structure and function, but a blend of both – requires a similarly cross-disciplinary approach.

How to cite: Evans, D.: Digging into the Future: The transition between bedrock and soil as an underexplored frontier zone in geoscience, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11742, https://doi.org/10.5194/egusphere-egu24-11742, 2024.

EGU24-12025 | ECS | Posters on site | SSS5.2 | Highlight

Enhancing soil carbon sequestration in the parks of the city of Barcelona  

Sílvia Poblador, Lucía Álvarez, Bárbara Díaz, Marc Felip, Francesc Sabater, Arthur Vienne, and Sara Vicca

Climate change is progressing at an alarming pace. In order to limit global warming to the agreed-upon 2°C in the United Nations Paris Agreement, we require both rapid decarbonization and the implementation of negative emissions technologies (NETs), that actively remove carbon dioxide (CO2) from the atmosphere and ensure stable long-term carbon storage. In this context, enhanced silicate weathering (ESW) has been proposed as a NET based on a nature solution. ESW aims to accelerate the natural uptake of atmospheric CO2 during the weathering of silicate rocks by grinding them, increasing their reactive surface and speeding up the process. This NET is particularly interesting as it does not compete for space with other economical activities. For instance, in agroecosystems, ESW is already considered a promising NET, offering multiple co-benefits for crop production when spreading silicate minerals on arable soils (i.e. increase in crop yields, restoration of soil base cations and micro- and macronutrient stocks). Besides agricultural land, urban soils can also be suitable for ESW. The application of ESW in city parcs and gardens presents an opportunity to increase the capture of atmospheric CO2, while also favoring vegetation growth (lawn, shrubs and flowers) and potentially enhancing resistance to drought and pests.

EMBARCARB is a pilot project that aims to increase soil carbon sequestration and improve the vegetation status in two parcs of the city of Barcelona (SE Iberian Peninsula), during an extremely dry year. Moreover, the project also aims to compare the carbon sequestration capacity of soils with weathering of silicate rocks and concrete demolition fines, thus reusing construction debris and strengthening the circular economy of the region. Here, we explore the preliminary results of the project and give a first estimation of the weathering rates and the capacity of such NETs to enhance soil carbon sequestration in the green areas of the cities.

How to cite: Poblador, S., Álvarez, L., Díaz, B., Felip, M., Sabater, F., Vienne, A., and Vicca, S.: Enhancing soil carbon sequestration in the parks of the city of Barcelona , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12025, https://doi.org/10.5194/egusphere-egu24-12025, 2024.

EGU24-12698 | ECS | Orals | SSS5.2 | Highlight

The centennial legacy of land-use change on organic carbon stocks of temperate agricultural soils 

David Emde, Christopher Poeplau, Axel Don, Stefan Heilek, and Florian Schneider

Land-use change (LUC) in agricultural settings is common both historically and under more recent climate-smart agriculture guidelines aimed at reducing the impact of agriculture on the climate. Recognising that conversion of perennial grasslands to annual cropland results in a large, but potentially reversible, loss of soil organic carbon (SOC) such guidelines often call for increasing the overall area under grassland. To date, the magnitude and direction of SOC change following LUC has been fairly well accounted for, but the time it takes to reach a new SOC equilibrium is not well understood. While broad scale emission reporting best practices (e.g. IPCC) suggest that SOC equilibrium is reached approximately 20 years after LUC, there is a growing body of knowledge that supports a centennial timescale in temperate or boreal climates. With data from the first German Agricultural Soil Inventory alongside extensive per-site land-use histories, we established SOC change timelines that show that not only does SOC take much longer than 20 years to reach equilibrium but it reaches equilibrium at vastly different rates depending on the direction of LUC. Sites converted from cropland to grassland took 83 years (95 % CI: 79 to 90 years) to reach SOC equilibrium whereas sites converted from grassland to cropland took 180 years (95 % CI: 151 to 223 years). In order to map the effects of historic LUC on SOC stocks in temperate agroecosystems with similar grassland and cropland SOC stocks to Germany, we applied these timeline models to comparable sites from the HILDA+ global LUC database (Winkler et al., 2020); a global reconstruction of annual land use and land cover at a 1 km spatial resolution from 1899 to 2019. Compiled from a range of open data sources (remote sensing, reconstructions, and census data) the HILDA+ dataset offers insights into relatively fine scale LUC dynamics that follow known socioeconomic drivers over the past 120 years. Using this dataset, we determined that 112 Million ha, or 3.5 % of the total agricultural area worldwide, was comparable to German agriculture in terms of SOC and growing conditions, and 11 % of that land (12.6 Million ha) had undergone LUC from cropland to grassland or vice versa since 1899. After accounting for duration on a per-cell basis, areas having undergone LUC from cropland to grassland (7.5 million ha) accounted for a 86.2 million Mg C increase over the past 120 years. Conversely, areas having undergone LUC from grassland to cropland (5.1 million ha) accounted for a -55.0 million Mg C decrease in SOC. The overall net increase of 31.2 million Mg C corresponds to about 5‰ of total SOC stocks across all agricultural land with pronounced regional differences. We conclude that land-use change histories of at least one century should be considered when interpreting present-day, and predicting future, SOC dynamics.


Winkler, K., Fuchs, R., Rounsevell, M. D. A., & Herold, M. (2020). HILDA+ Global Land Use Change between 1960 and 2019 [dataset]. PANGAEA. https://doi.org/10.1594/PANGAEA.921846

How to cite: Emde, D., Poeplau, C., Don, A., Heilek, S., and Schneider, F.: The centennial legacy of land-use change on organic carbon stocks of temperate agricultural soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12698, https://doi.org/10.5194/egusphere-egu24-12698, 2024.

EGU24-13751 | ECS | Posters on site | SSS5.2

Assessing the environmental benefits of biochar application in agriculture: Insights from lifecycle assessment 

Sirjana Adhikari, M A Parvez Mahmud, Ellen Moon, and Wendy Timms

Organic waste-derived biochar has been proven to have a significant potential for soil improvement, with recent results from this group showing evidence for improved water holding capacity, carbon stability and exchangeable cations. However, to contextualise these benefits it is important to consider environmental impacts during each stage of life cycle for the product.

In this study, a cradle-to-gate life cycle assessment (LCA) was performed, comparing a common use for garden organics (composting) to two alternative scenarios. One involved converting over-sized compost screenings (otherwise considered waste) to biochar as a supplementary product from the process, and the other involved converting garden organics directly to biochar as an alternative product.

LCA was conducted using ReCiPe2016 impact assessment method in OpenLCA software. Data for assessment were collected from the participating industries and Ecoinvent database. Sensitivity analysis considering different transport distances was carried out and finally an optimum transport distance with the lowest environmental impacts was recommended. Additionally, physico-chemical characterisation and carbon stability assessment were conducted to provide a comprehensive idea about the overall benefits of organic waste-derived biochar for soil and climate.

Our results revealed that global warming was increased from 675 kgCO2eq during composting of garden waste to 1017 kgCO2eq where over-sized screenings of compost is converted to biochar as a value-added product. Direct conversion of organic waste to biochar showed reduced global warming impact of 428 kgCO2eq compared to the previous two scenarios. Among 16 environmental impact indicators studied, the magnitude of 10 impact indicators increased with transport distance, while the remaining six indicators were not influenced by transport distance.

Soil application of biochar from organic waste has multiple co-benefits, that can be short and/or long term. Nevertheless, this study emphasises that research focused on agricultural application of biochar needs to be coupled with LCA or other holistic assessments for a comprehensive evaluation of net environmental impacts and benefits that consider the processes involved in sourcing of feedstock, biochar production, transport, and application.

How to cite: Adhikari, S., Mahmud, M. A. P., Moon, E., and Timms, W.: Assessing the environmental benefits of biochar application in agriculture: Insights from lifecycle assessment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13751, https://doi.org/10.5194/egusphere-egu24-13751, 2024.

The process of organic horizon formation is reflected in the quantity and quality of the mineral materials contained. In the highland of mountains in northern Japan, thick organic horizons develop due to heavy snowfall. The organic horizons are rich in 2:1 clay minerals from Asian dust originating from the Eurasian Continent and active Al and Fe derived from volcanic ash. Organic matter in the organic horizons is present in separation or associations with these clay minerals or active Al and Fe. These organo-mineral associations make different biogeochemical properties between relatively free and mineral-associated organic matter in its dynamics, even in the organic horizons, because minerals can protect organic matter from microbial decomposition. Evaluating the biogeochemical arrangements of organic matter and minerals is valuable to understanding organic matter dynamics in the organic horizons containing rich minerals. The objective of this research is to evaluate the organo-mineral associations in the organic horizons in the snowy mountains of northern Japan using density fractionation.

The organic horizon samples were collected from three mountains. Two selected mountains (Mt. Chokai and Mt. Kurikoma) are volcanoes, and the other is a non-volcanic mountain (Mt. Makihata). Samples in Mt. Chokai were taken from each soil horizon from two soil profiles of snow meadow soils and one of dwarf bamboo and dwarf pine soil. In Mt. Kurikoma, one soil profile of a snow meadow was selected. One soil profile and two surface soils (5-15 cm) of snow meadow were collected in Mt. Makihata. Freeze-dried organic horizon samples were shaken with 1.6 g cm-3 SPT and grass beads at 16 h and 120 rpm. Recovered floating materials were sieved at 0.5 mm to remove coarse, fresh plant roots. The fraction larger than 0.5 mm was termed course light fraction (cLF), and the smaller fraction was termed small light fraction (sLF). The residue heavier than 1.6 g cm-3 was  heavy fraction (HF). Isolated fractions were freeze-dried and observed by SEM. Organic carbon and total nitrogen of isolated fractions were measured by an elemental analyzer.

The mass recovery ranged from 91.5 to 97.0%. A lower recovery rate was observed in the upper horizons, presumably due to losses attributable to higher dissolved organic carbon contents. Each isolated fraction separated by density and size showed different physicochemical properties. cLF mainly consisted of fresh roots. Decomposed plant residue was found in sLF. In HF, structures of highly decomposed plant residues combined with minerals were observed. Lower C/N of HF compared to cLF and sLF in Mt. Chokai indicated more decomposed organic matter associated with minerals. These results showed that even in organic horizons, organic matter had different physicochemical properties depending on their associations with minerals. This study highlights the importance of focusing on minerals in evaluating organic matter dynamics in organic horizons affected by aeolian dust. The stability of organic matter bound to minerals in organic horizons needs further evaluation.

How to cite: Kobayashi, K., Asano, M., and Tamura, K.: Organic matter characteristics in density fractionation of organic horizons with Asian dust and volcanic ash in snowy mountains of northern Japan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13777, https://doi.org/10.5194/egusphere-egu24-13777, 2024.

EGU24-14590 | ECS | Posters on site | SSS5.2

Improving Biochar Suitability for Arid-Land Use: Impact of Elemental Sulfur and Compost on Acidification and Biological Activation 

Ahmed Al Rabaiai, Daniel Menezes-Blackburna, Said Al-Ismailya, Rhonda Janke, Ahmed Al-Alawi, Mohamed Al-Kindi, and Roland Bol

This study aimed to enhance the quality of biochar for applications in arid lands by employing elemental sulfur (S, 0.013%) as an acidifying agent and compost (10%) as a biological activator. The addition of elemental sulfur significantly reduced the biochar pH, with the most substantial decrease from 8.1 to 7.2 observed when co-amended with vermicompost was used. Elemental sulfur markedly increased the water-soluble concentrations of calcium (Ca) by 147% and 105%, as well as magnesium (Mg) by 929% and 447% in compost and vermicompost, respectively. This suggests a decline in biochar basicity due to acid mineral dissolution and desorption. Sulfate (SO42-) levels showed the greatest increase when compost was co-applied with sulfur, indicating more efficient oxidation in this treatment. FT-IR analysis revealed increased carbonyl groups (C=O) and decreased alkyne (C≡C) groups in compost and vermicompost-treated samples, while sulfur treatment resulted in the decrease of hydroxyl groups, but only in the presence of vermicompost. SEM-EDX analysis demonstrated changes in the elemental composition and microscale pore structure of biochar samples after incubation with sulfur. Sulfur amendments stimulated substrate-induced respiration, particularly in biochar amended with sulfur (BS, 0.011 ug CO2- C/g/h) and biochar with vermicompost (BV, 0.18 ug CO2- C/g/h) treatments. Microbial diversity (Shannon H) significantly increased in compost treatments with sulfur amendment from 3.08 to 4.52, while it decreased in vermicompost from 4.25 to 4.02. Vermicompost treatments (BV, BVS) exhibited higher microbial evenness (0.27 and 0.28) and equitability (0.67) diversity indices. The bacterial community structure was significantly influenced by all treatments, with sulfur reducing the abundance of Proteobacteria by 30% in the presence of compost and 8% with vermicompost, while increasing the abundance of Actinobacteria by 18% and 4% for compost and vermicompost treatments, respectively.Multivariate principal component analysis (PCA) indicated that soluble sulfate was associated with specific sulfur-oxidizing bacterial clusters, which were differentially expressed under different compost treatments. Integrating biochar with sulfur and compost emerges as a promising sustainable technology for managing alkalinity, enhancing soil fertility, and improving agricultural productivity in arid regions.

 

How to cite: Al Rabaiai, A., Menezes-Blackburna, D., Al-Ismailya, S., Janke, R., Al-Alawi, A., Al-Kindi, M., and Bol, R.: Improving Biochar Suitability for Arid-Land Use: Impact of Elemental Sulfur and Compost on Acidification and Biological Activation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14590, https://doi.org/10.5194/egusphere-egu24-14590, 2024.

Crop residues play a key role in supplying renewable carbon for the envisioned future greenhouse gas-neutral economy. However, their harvest is often limited below their technical potential to avoid soil organic carbon (SOC) stock losses. Nevertheless, the use of crop residues in the bioeconomy often involves the generation of a coproduct rich in recalcitrant carbon that can be reintegrated into soils to maintain SOC stocks. Yet, the environmental implications of such a strategy beyond those on climate change remain uncertain and contingent on specific contexts. Here, we present a novel framework that integrates a recalcitrance-adapted SOC model with a consequential life cycle assessment (LCA) to comprehensively evaluate the spatially explicit long-term SOC evolution and environmental impacts associated with returning various bioeconomy coproducts to croplands. The study spans diverse contexts, including temperate (France) and tropical (Ecuador) regions and five environmental impact categories, assessing the conversion of crop residues into maritime fuels, here hydrodeoxigenated pyrolysis oil (HPO) and cryogenic liquefied biomethane (bio-LNG), generating biochar and digestate as coproducts, respectively. The simulations were performed for >60,000 and >15,000 simulation units in France and Ecuador, employing adapted versions of AMG and RothC, respectively, under the RCP4.5 climate pathway in both regions. Results revealed that after 100 years, compared to a reference scenario where crop residues are directly incorporated into soils, biochar allows harvesting 100% of crop residues without any SOC losses in both French and Ecuadorian contexts. In contrast, digestate demonstrates a more limited potential, reaching 50% in France and 0% in Ecuador. This is referred to as the C-neutral harvest rate, which allows a surplus potential of 71-125 PJ in France and 113 PJ in Ecuador. The LCA revealed environmental benefits for all five impact categories for HPO and three categories for bio-LNG, per tonne of crop residues. Despite bio-LNG representing higher net avoided emissions (946 MgCO2e) than HPO (563 MgCO2e) per tonne of crop residues, the scaled results for the national C-neutral harvest rate showed the opposite trend with net avoided emissions of 11,912 MgCO2e for HPO and 10,707 MgCO2e for bio-LNG. Further, the scaled results revealed increased eutrophication impacts in marine water in the bio-LNG case, reflecting the nitrogen emissions associated with digestate, which is responsible for N2O, NH3, and nitrate losses to water. Yet, these can be mitigated with simple solutions such as treating digestate with nitrification inhibitors, microbial enrichment, or acidification at spreading. Moreover, biochar could be applied in tandem with digestate to create synergies from the nutrient-fertilizer effect of digestate and reduced C and N mineralization properties of biochar. In conclusion, defining a C-neutral harvest rate emerges as a pivotal strategy, ensuring a harmonious balance between SOC maintenance and net environmental impacts across diverse scenarios, emphasizing the potential of integrating bioeconomy practices with soil carbon management.

 

How to cite: Andrade Diaz, C. and Hamelin, L.: Tradeoffs between long-term SOC storage and overall environmental impacts of supplying crop residues to the bioeconomy: where, when, how and what does it depend on? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17426, https://doi.org/10.5194/egusphere-egu24-17426, 2024.

Examining soil carbon losses across various time scales is essential for understanding the potential of soil carbon stabilization. It allows for considering these losses in estimating the net changes in carbon stocks. The soil's intrinsic physical and chemical properties, particularly those associated with the mineral phase, have been suggested to regulate soil organic carbon (SOC) losses. However, the relationship between these properties and SOC losses remains to be determined in long-term experiments. A 600-day incubation experiment was conducted on sieved soil samples (<2 mm) and intact cores (volume=~200 cm3) collected from an arable field in Bjertorp in southwest Sweden with large variations in soil texture and SOC to determine the respiration rate through chamber alkali trap respirometry using a Portable conductivity meter. After the incubation experiment, soil properties (carbon, nitrogen, and pH) were also measured. In addition, previously determined soil texture, oxalate extractable aluminum (Alox), and iron measurements were used to explain the results of the incubation experiment. The ratios between Alox and SOC and Alox and clay content were used as proxies for the protection of SOC. Preliminary results from the sieved soil samples indicate that the respiration rate (µg C-CO2 g-1 SOC h-1) was positively correlated to the Alox:SOC  and clay:SOC ratio. These findings can be interpreted as the absence of SOC protection by Alox and/or clay complexes or interactions. The conclusions drawn from this study suggest the need for additional exploration into the intricate dynamics that influence the fate of soil organic carbon (SOC) associated with mineral phases when assessing carbon stocks.

How to cite: Chilipamushi, M., von Brömssen, C., Colombi, T., Kätterer, T., and Larsbo, M.: The role of oxalate-extractable aluminum in regulating soil organic carbon decomposition in agricultural topsoil in humid continental climates: Insights from a long-term incubation field-scale study., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17497, https://doi.org/10.5194/egusphere-egu24-17497, 2024.

EGU24-17654 | ECS | Orals | SSS5.2

Distribution of soil organic carbon across contrasting fractionation techniques - results from a long-term field trial with increasing shares of leguminous cover crops 

Ferdinando Binacchi, Murilo Veloso, Cimélio Bayer, Christopher Poeplau, Carsten Mueller, Franz Buegger, and Andreas Gattinger

Diversification of no-till cropping systems through the inclusion of leguminous crops can be a sustainable means for enhancing both the bioavailability as well as the persistence of soil organic carbon (SOC). Therefore a comprehensive assessment of long-term soil organic matter (SOM) dynamics is crucial to realize the potential of sequestering atmospheric carbon dioxide, while concomitantly restoring the productivity and functionality of degraded soils. In the current study, soil samples were taken from a 39 years old subtropical trial at seven soil increments until one meter depth. Treatments included five maize-based cropping systems, with increasing shares of leguminous cover crops, with or without nitrogen (N) fertilizer applications to the maize plants. Varying degrees of labile and recalcitrant SOC were distinguished by means of thermal analysis as well as through physio-chemical fractionation, yielding contrasting results in shares of carbon accumulation across conceptual pools. While thermally recalcitrant SOC (combusted at temperatures between 400˚C and 800 ˚C) represented a small percentage of total C accrual, chemically recalcitrant SOC (silt and clay fraction resisting sodium hypochlorite oxidation) reported both a large share of total C content, as well as a high C accumulation. Although limited overlap among C pools from the two fractionations was found, irrespective of C detection method, systems with higher shares of leguminous cover crops reported highest SOC stocks. Interestingly, including additional leguminous cover crops contributed in storing as much SOC as systems with N fertilization, but the depth at which SOC sequestration occurred varied between fertilized and non-fertilized systems. While SOC stocks in the 0-30 cm depth correlated positively to total C inputs from crop residues in both fertilized and unfertilized systems, SOC stocks in the subsoil (30-100 cm depth) only correlated (p<0.05) to inputs from leguminous cover crops in non-fertilized systems.

Moreover, shifts in δ¹³C signatures across the five physically separated C fractions (silt+clay, recalcitrant SOC , stable aggregates + sand, dissolved organic carbon and particulate organic matter), were used to calculate contributions of C₃ leguminous C inputs in mixed C₃/C₄ cropping systems and study pathways of SOC dynamics.  

Overall, the study reports high potential of leguminous cover crops to contribute to SOC build-up in subtropical Oxisols, especially through the association of labile organic matter to soil minerals.

How to cite: Binacchi, F., Veloso, M., Bayer, C., Poeplau, C., Mueller, C., Buegger, F., and Gattinger, A.: Distribution of soil organic carbon across contrasting fractionation techniques - results from a long-term field trial with increasing shares of leguminous cover crops, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17654, https://doi.org/10.5194/egusphere-egu24-17654, 2024.

EGU24-18070 | ECS | Posters virtual | SSS5.2

Stability of microbial necromass in soil is controlled by necromass chemical composition 

Sam Walrond, Jeanette Whitaker, Caroline Peacock, and Nick Ostle

Reversing the trend of decreasing soil carbon stocks is important to help mitigate current environmental challenges. Improving knowledge on the mechanisms that control the stabilisation and persistence of soil organic carbon will provide a foundation to tackle the issue. This includes the mechanisms controlling the stability of organomineral associations, considered to be the most persistent pool of soil carbon. Uncertainties remain in how the composition of carbon involved in mineral associations can control the persistence of this soil organic carbon (SOC) pool.

With the mineral associated pool being dominated by soil carbon derived from microbial necromass, composition of microbes and their cell components will have a significant impact on organomineral stability. This study aims to investigate whether differences in cell wall composition between fungi, gram-positive and gram-negative bacteria, contribute to contrasting stability of the organominerals synthesised using necromass of these microbial groups.

Organominerals composed of ferrihydrite and montmorillonite minerals and three types of necromass were synthesised and tested for their stability. This was done using chemical washes that bring about desorption (NaOH) and oxidation (NaOCl) of the necromass C. Solid fraction C and N were measured before and after chemical wash treatments to determine the extent of organic carbon (OC) destabilisation, and Fourier transform infrared (FTIR) spectroscopy was used to semi-quantitatively assess changes in OC functional groups before and after destabilisation.

Results indicate that organominerals containing fungal necromass have greater stability compared to organominerals containing gram-positive and gram-negative bacterial necromass. The most stable fraction within organominerals was C rich and did not comprise N-containing necromass components. The results imply that necromass derived from soil fungi could enhance the persistence of the mineral-associated pool of SOC.

How to cite: Walrond, S., Whitaker, J., Peacock, C., and Ostle, N.: Stability of microbial necromass in soil is controlled by necromass chemical composition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18070, https://doi.org/10.5194/egusphere-egu24-18070, 2024.

EGU24-18494 | ECS | Posters on site | SSS5.2

Modelling priming effect to explain the effect of DOC input quality on soil C turnover 

Olga Vindušková, Gaby Deckmyn, Kateřina Jandová, and Veronika Jílková

Even though priming effects (PE) could reduce soil organic C gains from enhanced ecosystem productivity under global change, the PE has been introduced to few models only recently. Both particulate organic matter (POM) and mineral-associated organic matter (MAOM) decomposition may be increased by DOC (dissolved organic carbon) inputs via the priming effect (PE) which is stronger in less-protected fractions (i.e., POM) and is also influenced by the DOC input quality. In our previous study, we showed that spruce litter leachates induced a higher PE than root exudates and could track their utilization by fungi and bacteria using isotope labelling, 13C-PLFA and 13C in respired CO2 and soil C fractions (Jílková et al. 2022)

Here we use components from the KEYLINK model to develop a model that can be optimized using data from the experiment of Jílková et al. (2022) and used to predict outcomes of ongoing follow up incubation experiments using 13C-labelled spruce and beech litter leachates and root exudates on soils and fractions alone. We use this approach to test our understanding of the mechanisms of the microbially-driven soil C turnover under contrasting quality of DOM inputs.

How to cite: Vindušková, O., Deckmyn, G., Jandová, K., and Jílková, V.: Modelling priming effect to explain the effect of DOC input quality on soil C turnover, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18494, https://doi.org/10.5194/egusphere-egu24-18494, 2024.

EGU24-18626 | ECS | Posters on site | SSS5.2 | Highlight

Combining remote sensing products with crop and soil models to estimate changes in soil organic carbon on cropland 

Gaétan Pique, Basile Goussard, and Andréa Géraud

Agricultural land is a major contributor to human greenhouse gas emissions, but it is also affected by climate change. At the same time, the recent 4p1000 initiative has identified cropland as having important the potential to sequester atmospheric carbon in the soil.
However, there is currently a lack of robust and accurate tools to assess the carbon budget of cropland at plot level and over large areas. This lack is due to the heterogeneity of the landscape, characterised by a wide range of soil and climatic conditions and many agricultural practices. However, these tools are needed to better understand the contribution of cropland to greenhouse gas emissions and to properly identify the most efficient levers for sequestrating carbon in the soil.
In this study we propose a modelling framework to estimate carbon budgets at plot scale and over large areas. This approach assimilates optical remote sensing products with high spatial and temporal resolution into a crop model (SAFYE-CO2). This model allows the estimation of CO2 fluxes as well as crop productions (biomass and yield) of the main crops and the cover crops. This information is then used as input to a soil model (RothC) to estimate the carbon storage following the introduction of the cover crops into the soil.
This framework is validated using CO2 flux measurements from the ICOS network and cover crop in situ biomass data.
This approach is in line with the search for the 'monitoring, reporting and verification' tools that is needed today to drive the agricultural transition, to enable sustainable agriculture that provides sufficient production in a changing climate, while identifying the best practices to use agricultural land as a way of achieving net zero carbon targets.

How to cite: Pique, G., Goussard, B., and Géraud, A.: Combining remote sensing products with crop and soil models to estimate changes in soil organic carbon on cropland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18626, https://doi.org/10.5194/egusphere-egu24-18626, 2024.

EGU24-19022 | Orals | SSS5.2

Enhanced rock weathering application on sub-tropical agroecosystems for carbon sequestration and sustainable crop production 

Shinya Iwasaki, Kosuke Hamada, Kazutoshi Kinjo, Yudai Yamaura, Yoshifumi Terajima, and Toshihiko Anzai

Achieving increased or sustained crop yields while minimizing environmental impact is a pressing challenge in agricultural science. Enhanced Rock Weathering (ERW) has emerged as a novel negative emission technology that accelerates natural geological processes of carbon (C) sequestration by applying crushed silicate rocks, specifically basalt, to croplands. However, field-scale evaluations to demonstrate carbon sequestration potential and agricultural co-benefits have been limited. This study quantitatively assessed the carbon and nitrogen (N) flow resulting from basaltic rock application in sugarcane and upland rice cultivation in a sub-tropical agroecosystem.

Two types of experiments were conducted on Ishigaki Island, located in the subtropical zone of Japan, where the annual rainfall and annual temperature were 2,500 mm and 24.0 ℃, respectively. Firstly, an outdoor field experiment on sugarcane cultivation was conducted. The following six treatments were applied with four replicates using a completely randomized block design: bare soil (no sugarcane), control without any amendment, lime application, manure application (10 Mg C ha−1), basaltic rock application (10% by weight), and a combination of manure and basaltic rock. Soil water at the 0.6 m depth, which we defined as leaching water, was collected from all plots using the porous cup method and subjected to dissolved C and N analysis. Secondly, an indoor lysimeter experiment was conducted on upland rice cultivation to understand the comprehensive flow of C and N, including greenhouse gas emissions. The following four treatments were assigned with three replicates to 12 concrete lysimeters with 2 m2 and 1 m depth: control without any amendment, torrefied plant residue (1% by weight), basaltic rock application (10% by weight), and a combination of torrefied plant residue and basaltic rock.

In the outdoor field experiment, continuous monitoring of soil volumetric water content and electric conductivity showed that the weathering of basaltic rock was enhanced by solid-liquid contact. Soil pH increased by the basaltic rock application the same as lime application. Similarly, the acidification of leaching water was buffered in the basaltic rock application treatments. Consequently, the inorganic carbon concentration in leaching water was higher in the basaltic rock application treatments than in the control and lime application treatments. Although there were no significant differences in the plant height of sugarcane, the number of leaves and Single Photon Avalanche Diode (SPAD) increased by basaltic rock application. Similarly, the indoor lysimeter experiment observed higher pH and dissolved inorganic C concentrations in leaching water. Although carbon dioxide flux increased by basaltic rock application in the first month, it was decreased in the crop growing period. These results indicated that the ERW application has a C sequestration potential and co-benefit on crop production. The annual C and N budget and further discussion will be presented in the session.

How to cite: Iwasaki, S., Hamada, K., Kinjo, K., Yamaura, Y., Terajima, Y., and Anzai, T.: Enhanced rock weathering application on sub-tropical agroecosystems for carbon sequestration and sustainable crop production, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19022, https://doi.org/10.5194/egusphere-egu24-19022, 2024.

EGU24-19605 | ECS | Posters virtual | SSS5.2

Soil carbon storage and greenhouse gas fluxes in forested and grassland ecosystems of Gujarat undergoing anthropogenic and climatic disturbances 

Niharika Sharma, Mohammad Atif Khan, Priyamvada Dubey, Chhavi Nath Pandey, Sanjeev Kumar, and Vikrant Jain

Carbon storage in soils is a significant nature-based solution for adaptation and mitigation of climate change. However, soil carbon storage varies with the change in land cover and the association of organic matter with differently sized soil aggregates. To compare the effects of these parameters on the carbon cycling of soils, we have analyzed the soil carbon content and greenhouse gas emissions from soils under different land cover in Gujarat, India. We sampled forest soils from regions covered with dry deciduous trees, moist trees, forest fires, and forest conversion to agriculture. We further sampled grassland soils in the areas showing matured grasses, harvested grasses, salinity-affected grasses, grazing-affected grasses, and the grassland region impacted by the invasion by Prosopis juliflora species. We classified some of these land features as a result of climatic disturbances (increase in salinity, invasion by Prosopis, forest fire) and others as anthropogenic disturbances (cattle grazing, harvesting, agriculture). Physico-chemical properties and greenhouse gases emitted from soils were measured using handheld probes and chamber methods, respectively. Laboratory analysis of soil carbon and its isotopes was performed for bulk soils and the soil density-size fractions (particulate fractions, sand-sized fractions, clay and silt size fractions, and recalcitrant organic matter fractions). Our analysis reveals the change in carbon emissions and carbon storage in soils of arid-moist stretch in Gujarat is caused by different land cover and management practices. The presence of aboveground biomass has a significant control on the carbon storage capacity of soils highlighting the importance of afforestation and ecosystem restoration in building up the soil carbon stock. Carbon emissions were also higher in soils with large aboveground vegetation; however, this mainly represents soil microbial respiration and thus indicates healthy soil and rich pedo-biodiversity. Most of the carbon in grassland soils was associated with silt and clay-sized particles whereas the carbon content in forested soils is higher within sand-sized particles. Soils from both grasslands and forests acted as a sink for atmospheric methane except for soils from grazed grasslands, indicating the importance of grazing management in grassland ecosystems. Climatic stressors like an increase in salinity and Prosopis invasion showed no significant impact on soil carbon stock and greenhouse gas emissions and behaved similarly to harvested grasslands or dry-deciduous forests. Forest fire, on the other hand, can change the texture and carbon and nitrogen association in the soils. Conversion of forests to croplands has the most detrimental impact on soil carbon storage and can lead to loss of stored carbon in the form of high greenhouse gas emissions. Forest land conversions should, therefore, also consider this aspect of forest conversion in its management plan.

How to cite: Sharma, N., Khan, M. A., Dubey, P., Pandey, C. N., Kumar, S., and Jain, V.: Soil carbon storage and greenhouse gas fluxes in forested and grassland ecosystems of Gujarat undergoing anthropogenic and climatic disturbances, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19605, https://doi.org/10.5194/egusphere-egu24-19605, 2024.

Improving carbon storage in soils and the biosphere is a promising nature-based solution to combat climate change and is receiving more and more attention with little understanding how this can be achieved globally and in a sustainable way.

Many of our expectations in finding nature-based solutions rely on vast, less developed–but nevertheless populated and rapidly changing– regions of the Global South. At the same time, concepts and assumptions about which solutions work for increasing long-term carbon capture in soil systems are based on knowledge gathered largely from the Global North in often fundamentally different environmental settings and development history. 

In my talk I will illustrate with examples from the socio-ecological context of the African Tropics how these knowledge gaps and our lack of understanding of tropical carbon cycling mislead us into thinking that we can find easy solutions in the Tropics to mitigate climate change. I will highlight how the interactions of weathering and erosional disturbance can influence and dominate biogeochemical cycles in soils and discuss some directions where geochemical proxies that are available at the global scale can be useful for improving the spatial and temporal representation of tropical carbon storage and turnover.

How to cite: Doetterl, S.: Soil carbon sequestration in sub-Saharan Africa – Great expectations, limited potentials?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22139, https://doi.org/10.5194/egusphere-egu24-22139, 2024.

EGU24-3409 | ECS | Orals | SSS5.3

Microbial iron(III) reduction of iron-organic carbon phases across a permafrost thaw gradient and its impact on methane emissions 

Eva Voggenreiter, Daniel Straub, Laurel Thomas Arrigo, Andreas Kappler, and Prachi Joshi

Wetlands account for roughly 20-30% of global methane (CH4) emissions, in part due to (permanently) anoxic conditions that promote methanogenesis. Low-lying permafrost peatlands are expected to be an increasing source of CH4 due to permafrost thaw in the future, due to waterlogging, anoxia and organic carbon (OC) mobilization. These processes can force an increase of the extent of wetlands and higher total CH4 emissions. Net release of CH4 depends on the availability of more energetically favorable electron acceptors in soil, such as ferric iron (Fe(III)). Fe(III) may be present as Fe(III) oxyhydroxides or Fe(III)-OC phases in peatlands. Since Fe(III)-reducing microbes and methanogens compete for the same substrates (e.g., small organic molecules such as acetate), CH4 production is often suppressed as long as there is bioavailable Fe(III) present. However, the dissolution of Fe(III)-OC phases during Fe(III) reduction would release the previously bound OC and make it more bioavailable to fermenting microorganisms. This would produce more substrates for methanogens and could therefore increase CH4 production. It is currently unknown to what extent microbial reduction of Fe(III)-OC phases and the coupled OC release effects CH4 emissions across permafrost thaw.

In this study, we therefore aim to elucidate the extent of reduction of Fe(III)-OC phases upon permafrost thaw and the corresponding effect on CH4 emissions across three distinct thaw stages: (i) recently collapsed palsa hills, (ii) partly thawed bog and (iii) fully thawed fen habitats. We simulated permafrost thaw by a series of incubation experiments with soils from each thaw stage from a permafrost peatland (Stordalen Mire, Abisko, Sweden). Soils were incubated under anoxic, flooded conditions for 30 days, after which synthesized 57Fe-labelled Fe(III)-OC coprecipitates were added as representative Fe-OC phases. Over the course of the incubations (42 days), we followed Fe speciation and 57Fe fractions in the dissolved and solid phases using geochemical and synchrotron-based spectroscopy techniques in addition to quantification of greenhouse gas production. Results show that added coprecipitates were completely reduced (within 1 day) in palsa and bog soils, leading to increases in dissolved Fe2+, OC concentrations and CO2 emissions. CH4 production was not detected in palsa soils over the course of the incubation and CH4 suppression in bog soils due to Fe(III) reduction was only short-term. In contrast, added coprecipitates in fen soils were only reduced by 10% after 42 days, likely due to low dissolved OC concentrations. However, this led to a significantly higher inhibition of methanogenesis than in the palsa and bog soils. We also studied the microbial community by 16S rRNA amplicon (gene) sequencing and quantified mcrA gene copy numbers to assess the potential activity of methanogens. Overall, these results help to understand the influence of Fe-OC coprecipitates on methane emissions in thawing permafrost peatlands.

How to cite: Voggenreiter, E., Straub, D., Thomas Arrigo, L., Kappler, A., and Joshi, P.: Microbial iron(III) reduction of iron-organic carbon phases across a permafrost thaw gradient and its impact on methane emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3409, https://doi.org/10.5194/egusphere-egu24-3409, 2024.

Diffusion is acknowledged as the principal mechanism for the soil solution transport of limiting nutrients in terrestrial ecosystems. This process is influenced by the interplay among the chemical, biological, and physical properties of soil, where alterations in these properties can variably impact other factors, thereby influencing diffusive fluxes. This study, based on theoretical analysis and the review of existing literature, explores how soil biological properties such as microbial activity and soil enzyme activity, as well as abiotic soil properties like soil pH, soil texture, soil cation and anion exchange capacity, and moisture, influence the diffusion and availability of nutrients in soils. We first formalize the drivers of diffusive solute fluxes into three contributors according to Fick’s first law of diffusion (the diffusion coefficient controlled by soil physicochemistry, the path length by pore size distribution and soil water content and the concentration gradient related to source-sink relationships) and then discuss and study the effects of soil biological and abiotic properties on these three principal drivers and on nutrient diffusion. Microbial activity plays a crucial intermediary role in the diffusion of nutrients in soils, significantly influencing their availability and distribution. Soil microorganisms, by decomposing soil organic matter, alter the form and availability of soil nutrients, thereby impacting the concentration gradient for nutrient diffusion. Additionally, the competitive relationship between plants and soil microorganisms affects the forms and quantities of available nutrients. Abiotic soil factors also significantly influence the migration and diffusion of nutrients. Soil chemical properties, such as soil pH and surface charge which vary among different forms of nitrogen, including inorganic forms such as nitrate and ammonium as well as organic forms such as amino acids. These forms exhibit considerable differences in net charge, hydrophobicity, and molecular weight, affecting their interaction with the soil matrix. Through processes like ion exchange, adsorption, and hydrophobic interactions, these interactions consequently alter their individual diffusion coefficients based on soil properties. Additionally, the physical structure of soil, such as the porosity, pore size distribution and aggregate structure, determines the mobility of water and nutrients within the soil through affecting the diffusive path length, together with soil water content, thereby affecting nutrient diffusion. In conclusion, this study underscores the importance of understanding and evaluating the interplay between soil biotic and abiotic properties when conducting nutrient diffusion research using soil microdialysis techniques. This comprehensive analytical approach is crucial for enhancing the effectiveness of soil nutrient management, as well as for its long-term implications on agricultural production and environmental conservation. The conceptual/analytical approach will be applied to a wide range of soils differing in texture, mineralogy, pH, chemistry, management and microbial activity, and diffusive fluxes of multiple elements and solute forms determined simultaneously at similar soil moisture and temperature, and then be linked - using machine learning approaches - to those key soil properties potentially controlling nutrient diffusive fluxes to develop a generalized model of controls of soil diffusive fluxes of elements.

How to cite: Wen, M. and Wanek, W.: Biotic and Abiotic Controls on Soil Nutrient Diffusion Fluxes Based on Microdialysis Measurerments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5844, https://doi.org/10.5194/egusphere-egu24-5844, 2024.

EGU24-5967 | ECS | Posters on site | SSS5.3

Gross Nitrogen Transformation: Insights from 15N Tracing in a Gas Sampling Incubation Experiment 

Barira Shoukat Hafiza, Wolfgang Wanek, Magdeline Vlasimsky, Mohammad Zaman, Gerd Dercon, Maria Heiling, and Christian Resch

Nitrous oxide (N2O) stands out among greenhouse gases due to its global warming potential, surpassing carbon dioxide by 310 times and methane by 16 times over a 100-year period. Its primary source lies in the application of fertilizers to agricultural soil. Despite its significance, traditional methods for understanding the intricate relationships within gross nitrogen (N) transformation processes are limited in their analytical depth.

Current research increasingly centers on the N2O/(N2O+N2) product ratio, offering valuable insights into the efficiency of nitrogen transformations and the potential for N2O emissions. Quantifying both gases, however, poses challenges that demand specialized techniques. Leveraging isotopic methods, such as the introduction of enriched NO3− and monitoring 15N labelled denitrification products, proves instrumental in unravelling N2O sources and facilitating emission mitigation strategies.

This study aims to contribute to this knowledge by measuring N2O and N2 and identifying their sources using a 15N tracer. Soil samples were collected from a 0-15cm depth at Grabenegg, an agricultural site in Austria. Two treatments were applied, with 15NH414NO3  for treatment one and 14NH415NO3 for treatment two, both at a rate of 100 kg N/ha (equivalent to 150 kg N/ha when expressed as 100 mg N/kg soil). The incubation experiment spanned 10 days in 850ml glass jars at 60% WFPS, involving seven sampling days. Soil analyses included ammonium and nitrate content through colorimetric methods, pH determination, and 15N analysis using an Isotope Ratio Mass Spectrometer (IRMS) following an adjusted Brooks microdiffusion.

Gas samples extracted from the jars over a two-hour period underwent analysis for CO2, CH4, and N2O content using a Picarro G5102-i isotopic and gas concentration analyzer. Integration with N tracing models yielded crucial insights into the connections between substrates and N transformation products, shedding light on the impacts of synthetic fertilizer and enabling the quantification of transformation rates.

How to cite: Hafiza, B. S., Wanek, W., Vlasimsky, M., Zaman, M., Dercon, G., Heiling, M., and Resch, C.: Gross Nitrogen Transformation: Insights from 15N Tracing in a Gas Sampling Incubation Experiment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5967, https://doi.org/10.5194/egusphere-egu24-5967, 2024.

EGU24-6628 | ECS | Orals | SSS5.3

Time to Anoxia: Oxygen Consumption in Soils Varies Across a Coastal Gradient 

Kaizad Patel, Kenton Rod, Jianqiu Zheng, Peter Regier, Fausto Machado-Silva, Matthew Kaufman, Kenneth Kemner, J. Patrick Megonigal, Nicholas Ward, Michael Weintraub, and Vanessa Bailey and the COMPASS-FME Team

The coastal terrestrial-aquatic interface (TAI) is a highly dynamic system characterized by strong physical, chemical, and biological gradients. In particular, shifting soil redox conditions, due in part to dynamic water conditions, is a strong driver of carbon availability and transformations across TAIs. However, one of the important unknowns across TAIs is how soils with different characteristics and inundation regimes respond quantitatively to water saturation and resulting shifts between oxic and anoxic subsurface conditions. We used field measurements, laboratory incubations, and model simulations to investigate oxygen consumption and redox transformations following short-lived oxygenation events under different environmental conditions. Soils were collected along a coastal gradient (upland to wetland) from the Western Lake Erie region (freshwater TAI) and the Chesapeake Bay (estuarine TAI) and incubated in microcosms for two weeks. When inundated in MilliQ water, the upland A horizon soils went anoxic in 24 hours, whereas the wetland and transitional soils went anoxic in 0.5 - 10 hours. In contrast, the upland B horizon soils did not go anoxic during the 2-week incubation. Model simulations suggested stronger abiotic controls of oxygen consumption in the wetlands vs. biotic controls in the upland soils. These simulations also suggested nutrient limitation in the subsurface soils. Subsequent incubations with glucose and acetate additions showed increased rates of oxygen consumption in the B horizon soils, suggesting that these soils were indeed carbon limited. These experiments provide insight on shifting redox conditions during flooding events, especially relevant in coastal systems that experience rapidly shifting hydrological conditions and are becoming increasingly vulnerable to sea level rise and episodic disturbances (e.g., storm surges, king tides).

How to cite: Patel, K., Rod, K., Zheng, J., Regier, P., Machado-Silva, F., Kaufman, M., Kemner, K., Megonigal, J. P., Ward, N., Weintraub, M., and Bailey, V. and the COMPASS-FME Team: Time to Anoxia: Oxygen Consumption in Soils Varies Across a Coastal Gradient, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6628, https://doi.org/10.5194/egusphere-egu24-6628, 2024.

 The repetitive wetting and drying cycles, driven by intense rainfall and drought, intricately alter subsurface conditions, affecting redox states and pH levels. Consequently, these alterations may prompt the dissolution or transformation of ferrihydrite (Fh), an amorphous iron oxide used as a stabilizing agent in soil, thereby influencing the leaching behavior of heavy metals. This study investigates the impact of wetting and drying cycles on Fh crystallinity, and the leaching behavior of immobilized heavy metals, specifically focusing on cadmium (Cd) and zinc (Zn) at Fe/heavy metals molar ratios of 1 and 10. Fh synthesis was induced by neutralizing pH to 7.0 with 1 M NaOH, simultaneously fostering the coprecipitation of Fh-heavy metals. The experimental design entailed 12 cycles, each involving 8 hours of wetting at room temperature, followed by 16 hours of drying at 40 °C. The Synthesis Precipitation Leaching Procedure (SPLP) was then used to confirm the variations in leaching quantities observed throughout the cycles, following the guidelines of EPA METHOD 1312. Analyses using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) revealed distinct variations in morphology and crystallinity based on the type and ratio of heavy metals. Pure ferrihydrite remained stable after 12 cycles; however, heightened crystallinity emerged after 3 cycles in high heavy metal concentrations, forming otavite (CdCO3) in Cd samples and petalline-shaped ferrihydrite in Zn samples. In contrast, low heavy metal concentrations displayed no such changes, indicating variable effects of wetting-drying cycles depending on the iron-to-heavy-metals ratio. The supernatant concentration decreased by 11-37% during wetting in all samples, yet SPLP leaching tests exhibited consistent heavy metal concentrations between wetting and drying, suggesting a minimal impact on heavy metal stability. These findings underscore the environmental factors influencing the stability of iron oxide-based immobilized heavy metals and raise the need for long-term stability assessments to consider variables that can cause more complex changes in the field. 

How to cite: Kim, C. and Nam, K.: Effect of Wetting and Drying Cycles on the Stability of Cadmium and Zinc Immobilized with Ferrihydrite , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7067, https://doi.org/10.5194/egusphere-egu24-7067, 2024.

EGU24-7518 | ECS | Posters on site | SSS5.3

Faster P cycling upon permafrost collapse 

Ziliang Li and Yuanhe Yang

Permafrost collapse is expected to accelerate carbon (C) release and induce a positive C-climate feedback. As the frequently limiting key element in permafrost ecosystems, phosphorus (P) could mediate ecosystem C balance by modulating microbial decomposition and primary production. However, little is known about the changes in P cycling upon permafrost collapse. By combining sequential extraction, 31P NMR spectroscopy and metagenomic sequencing, we explored whether and how different soil P pools and microbial P transformation genes responded to permafrost thaw based on six thermokarst (abrupt collapse of ice-rich permafrost)-influenced sites on the Tibetan Plateau. We observed a significant decrease in soil labile P, NaOH-Po and residual P after permafrost collapse. The negative relationship between aboveground biomass P content and the soil labile P as well as NaOH-Po indicated that the reduction in these P pools were associated with the plant P uptake. Moreover, the increased relative abundance of the genes involved in inorganic P-solubilization and organic P-mineralization upon permafrost collapse reflected the potential increase in microbial P mobilization. These findings highlight a faster P cycling through plant P uptake and microbial P mobilization after permafrost collapse, which could impact the ecosystem C cycle and its feedback to climate warming.

 

How to cite: Li, Z. and Yang, Y.: Faster P cycling upon permafrost collapse, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7518, https://doi.org/10.5194/egusphere-egu24-7518, 2024.

EGU24-9618 | Posters on site | SSS5.3

Exchangeable soil and sediment fractions compared 

Manfred Sager

Soil to plant transfer depends on availability, plant needs and plant excretion. Readily soluble and exchangeable ions represent the minimum available fraction. Traditionally, different extracts have been standardized to monitor just one or two nutrients resp. trace elements. Whereas customers expect a “true value”, leachings with neutral salts lead to slightly different results. Some of the uncertainties are due to the low concentration levels, others due to resorption of reagent blanks at the solid matrix. Thus, the interpretation is of relevance, and not the numeric level.

From the point of view of blanks and ICP-compatibility, ammonium salts or weak organic acids should be preferable extractants.

Data from a ring test of 5 soils and 12 participants show widely overlapping data ranges of extracts obtained with ammonium acetate and ammonium nitrate, but a trend to lower release of Cd, Cu, Pb and Zn into nitrate versus acetate, contrary to Cr and Ni. This is expectable due to complexation capabilities of acetate.

Also from sediments of the River Danube, 1M ammonium acetate released much more Pb, Zn, P, Ca, and Mn than 1M ammonium chloride at the same pH = 7. For Cr, Al, and As, however, this effect was rather reverse. The proportion of acetate versus chloride release did not significantly correlate with loss of ignition, nor with pedogenic of these samples. (The pedogenic oxides were calculated as the sum of Al+Fe+Mn released into oxalate buffer pH 3, and turned into their oxides).

Is it possible, to substitute the fraction exchangeable with LiCl by much cleaner dilute acetic acid? The released amount into LiCl is quite low, and in non-contaminated samples, As, Be, Cd, Cr, Mn, Mo, Pb and V were below detection limits. There is resorption of Cr, Ni, Pb, Zn reagent blanks at the solid, and Li blanks at the ICP for subsequent determinations get reduced. In case of K, Mn, Ba, and B, a good correlation and for S and P a moderate one, had been achieved between concentrations extracted into LiCl and dilute acetic acid, but not for others.

In order to optimum use of ICP-OES as a multi-element instrument, and to cope with decreasing manpower in the labs, the number of extractions should be minimized. Thus, it was tried to simulate the concentration of K and P by CAL extract, B by Baron-extract, and Mg by CaCl2-extract, by a simple (BCR-like) sequence of 0,16M acetic acid, with subsequent 0,1M oxalate buffer pH 3. This would widen the scope for acid exchangeable trace elements and S also. K, P and B could be very well simulated, and fitted to equal numeric values by partial correlation analysis with other parameters obtained, but for Ca-exchangeable Mg, this was difficult.

How to cite: Sager, M.: Exchangeable soil and sediment fractions compared, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9618, https://doi.org/10.5194/egusphere-egu24-9618, 2024.

EGU24-11857 | Orals | SSS5.3

Soil organic matter turnover: global implications from δ13C and δ15N signatures 

Yakov Kuzyakov and Evgeniya Soldatova

The residence time of carbon (C) and nitrogen (N) in soil is a fundamental parameter reflecting the rates of soil organic matter (SOM) transformation and the contribution of soils to greenhouse gases fluxes. Based on the global database of the stable isotope composition of C (δ13C) and N (δ15N) depending on soil depth (171 profiles), we assessed С and N turnover and related them to climate, biome types and soil properties. The 13C and 15N discrimination between the litter horizon and mineral soil was evaluated to explain the key litter transformation processes. The 13C and 15N discrimination by microbial utilization of litter and SOM, as well as the continuous increase of δ13C and δ15N with depth, enabled to assess C and N turnover within SOM. N turnover was two times faster than that of C, which reflects i) repeated N recycling by microorganisms accelerating the N turnover, ii) C loss as CO2 and input of new C atoms to cycling, which reduces the C turnover, and iii) generally slower turnover of N free persistent organic compounds (e.g. lignin, suberin, cellulose) compared to the N containing compounds (e.g. amino acids, ribonucleic acids). An increase in temperature and precipitation accelerated C and N turnover because: i) higher microbial activity and SOM decomposition rate, ii) larger soil moisture and fast diffusion of dissolved organics towards exoenzymes, iii) downward transport of 13C-enriched organic matter (e.g. sugars, amino acids), and iii) leaching of 15N-depleted nitrates from the topsoil and losses from the whole soil profile. Temperature accelerates SOM turnover stronger than precipitation. The temperature increase by 10 °C accelerates the C and N turnover for 40%. SOM turnover is boosted by decreasing C/N ratio because: i) SOM with a high C/N ratio originated from litter is converted to microbially-derived SOM in mineral soil characterized by a low C/N ratio; ii) litter with a low C/N ratio is decomposed faster than litter with a high C/N; iii) microbial carbon-use efficiency increases with N availability. The biome type affects SOM decomposition by i) climate: slower turnover under wetter and colder conditions, and ii) by litter quality: faster utilization of leaves than needles. Thus, the fastest C turnover is common under evergreen forests and the lowest under mixed and coniferous ones, whereas temperature and C/N ratio are the main factors controlling SOM turnover. Concluding, the assessment of SOM turnover by δ13C and δ15N approach showed two times faster N turnover compared to C, and specifics of SOM turnover depending on the biomes as well as climate conditions.

Soldatova E, Krasilnikov S, Kuzyakov Y 2024. Soil organic matter turnover: global implications from δ13C and δ15N signatures. Science of the Total Environment 912, 169423. https://doi.org/10.1016/j.scitotenv.2023.169423

How to cite: Kuzyakov, Y. and Soldatova, E.: Soil organic matter turnover: global implications from δ13C and δ15N signatures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11857, https://doi.org/10.5194/egusphere-egu24-11857, 2024.

EGU24-12106 | Orals | SSS5.3

Divergent patterns of Carbon, Nitrogen and Sulfur storage in grassland soils 

Sara L. Bauke, Jospehine Iser, Heike Schimmel, Dymphie Burger, and Wulf Amelung

Sulfur (S) in soils mainly occurs in organic forms, and its cycling should be primarily controlled by the same factors as those for carbon (C) and nitrogen (N), two other main constituents of soil organic matter. Here, we aim to test this assumption based on a global meta-analysis of soil organic C, N and S contents in grassland soils. We reviewed existing literature with a focus on grassland soils as one of the major global ecosystems, including both native grasslands and managed grasslands with additional fertilization. Element concentrations and supplementary parameters (mean annual temperature and precipitation, texture, pH, soil group, management) were retrieved from the studies, while C:S and N:S element ratios were either directly obtained from the studies or calculated. Additionally, we analyze isotope ratios of the respective elements (δ13C, δ15N and δ34S) in soil samples collected from native and managed grassland sites along climatic transects across Europe and North America.

In literature data concentrations of OC and N, but not S, were significantly higher in pastures compared to native grassland. As a consequence, C:S and N:S ratios were significantly lower in cultivated grassland than in native sites. Further, climatic conditions and soil group significantly affected C:S and N:S ratios, with significantly lower ratios in arid climate and in soil groups typically occurring there (e.g. Kastanozems) compared to more humid conditions and respective soil groups (e.g. Luvisols). However, the variation of C:S and N:S ratios was considerably higher than for C:N ratios. This was also evident in the isotope data obtained from the soil samples along the continental transects. Here, compared to δ13C and δ15N, δ34S values showed strong variation that was only partially explained by climate and land use, and was additionally affected by the specific parent material at each site. We therefore suggest that the availability and turnover of S in organic matter of grassland soils is not strictly analogous to C and N cycling. 

How to cite: Bauke, S. L., Iser, J., Schimmel, H., Burger, D., and Amelung, W.: Divergent patterns of Carbon, Nitrogen and Sulfur storage in grassland soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12106, https://doi.org/10.5194/egusphere-egu24-12106, 2024.

EGU24-13254 | ECS | Posters on site | SSS5.3

P dynamics in rainfed forage maize crop soils under different maize-grassland rotation cycles 

Begoña Maroñas, Ángeles Prieto-Fernández, Beatriz Rodriguez-Garrido, Serafín González-Prieto, M. Carmen Monterroso-Martínez, and Carmen Trasar-Cepeda

In a context of environmental sustainability, fertiliser application to agricultural soils must be optimised through sustainable cultivation practices. Over-fertilisation, the use of soluble mineral forms and/or their application at inappropriate stages of crop growth, has generated serious problems associated with the alteration of biogeochemical cycles (mainly C, N and P), eutrophication of waters, emission of greenhouse gases and depletion of natural resources. For this reason, our research team is conducting a project aimed at developing and evaluating sustainable agricultural soil management practices that reduce dependence on inorganic fertilisers and pesticides, prevent SOM loss and erosion, and contribute to the restoration of soil biodiversity. As part of this project, this study focuses on assessing P dynamics in rainfed forage maize crop soils subjected to different management practices, aiming to evaluate the influence of these practices on the bioavailability of P and its potential leaching into drainage waters.

We selected several maize plots subjected to two distinct management types, each under conventional inorganic/organic fertilisation regime. The first management type follows a typical rotation for maize crops in the area - after maize harvest (September-October) the plot is maintained as grassland for 2-3 years before being cultivated with maize again (3-year rotation). The second management type focuses on analising P dynamics in soils during the early stages of conversion to cultivation. In this case, we choose a site where soil that had been under grassland for at least 100 years was converted to maize; however, in this case the maize-grassland rotation is annual, with the two crops alternating each year (1-year rotation).

Over three consecutive years, samples were taken from the top 10 cm of the soil under the triennial grassland-maize rotation, while for the annual rotation, samples were taken from the top two soil layers (0-10 and 10-20 cm). Soil sampling occurred at various times when the soil was under maize and grassland. P forms were analysed following the sequential fractionation of Hedley et al. (1982). Residual inorganic and total P were analysed through extraction with 0.5 N sulfuric acid before and after calcination (550 ºC, 2 h) of the fractionation residue, estimating the residual organic phosphorus by difference between both. The pseudo-total P content of the soils was determined by ICP-OES after acid digestion with HNO3 +HCl in a microwave oven (MILESTONE, Italy).

The results were analysed in relation to the type of rotation and the time elapsed since the transformation from grassland to maize cropland. The P content, especially inorganic P, in the soil subjected to the 3-year rotation was significantly higher compared to the soil under the 1-year rotation. This discrepancy reflects the historical overfertilization experienced by the former over an extended period. Moreover, the transition from grassland to maize cultivation resulted in the loss of the typical stratification observed in grassland soils. This was evidenced through the homogenization of P contents across all organic and inorganic forms in the two soil layers investigated.

Hedley M.J., J. Stewart J.W.B., Chauhan B.S. 1982. Soil Sci. Soc. Am. J. 46, 970-976.

How to cite: Maroñas, B., Prieto-Fernández, Á., Rodriguez-Garrido, B., González-Prieto, S., Monterroso-Martínez, M. C., and Trasar-Cepeda, C.: P dynamics in rainfed forage maize crop soils under different maize-grassland rotation cycles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13254, https://doi.org/10.5194/egusphere-egu24-13254, 2024.

EGU24-13568 | ECS | Orals | SSS5.3

Effect of biochar application depths on leaching of nitrate and crop growth 

Kosuke Hamada and Satoshi Nakamura

Abundant use of chemical fertilizer causes reactive nitrogen load to the environment. Leaching of reactive nitrogen occurs mainly in nitrate (NO3−N) form, which moves into groundwater and other water bodies causing human health hazard and harming ecosystems, especially in tropical islands. Biochar application, which is known as a measure of carbon sequestration, can mitigate the leaching of NO3−N. We have accumulated knowledge regarding the effective application rate of biochar. However, the information on the effect of biochar application depth remains unclear, although it would affect the leaching of NO3−N and crop growth. The objective of this study was to evaluate the effect of biochar application depth on the leaching of NO3−N and crop growth. Using biochar made from bagasse, which is a major organic waste in tropical islands, we conducted a pipe experiment with upland rice (NERICA). We set four treatments: control (no biochar application); surface application (0−5 cm); plow layer application (0−30 cm); subsurface application (25−30 cm). Regarding leaching of NO3−N, the result under surface application showed a 12% decrease, while that under plow layer application showed an 11% increase against that under the control. Whereas the leaching of NO3−N was the same under subsurface application as that under the control. Total nitrogen uptake by crop was the highest under surface application, whereas those under plow layer and subsurface applications were smaller than those under the control. By comparing the leaching of NO3−N with the total nitrogen in the root, we obtained a clear relationship that the higher the total nitrogen in the root was, the lesser the leaching became. The result of the matric potential head in each pipe revealed that soil water condition was stressless for crops under the surface application. On the other hand, dry stress occurred more frequently under plow layer and subsurface applications. These results indicated that, depending on biochar application depth, soil water stress conditions differed and affected root growth positively/negatively. Consequently, crop growth and the leaching of NO3−N were changed. The surface application can be considered as an effective application, which mitigates the leaching and promotes crop growth simultaneously. We believe the finding of this study encourages the establishment of sustainable agriculture.

How to cite: Hamada, K. and Nakamura, S.: Effect of biochar application depths on leaching of nitrate and crop growth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13568, https://doi.org/10.5194/egusphere-egu24-13568, 2024.

EGU24-15009 | ECS | Orals | SSS5.3

Trace metal transport during managed aquifer recharge with monovalent-partial desalinated water: The role of divalent ions and organic matter 

Laura Braeunig, Jack Longman, Frederik Gäng, and Gudrun Massmann

Global fresh groundwater resources are threatened due to increasing withdrawal and salinization. Managed Aquifer Recharge (MAR) is an effective approach to augment overexploited aquifers and can also be applied to improve the groundwater quality by infiltration of desalinated water. But MAR can also bear risks when the soil passage or aquifer contains trace metals (e.g. As, V, Co, Cd) with their mobilization and subsequent human uptake. Understanding of metal mobilization (especially As) due to mineral dissolution at MAR sites with desalinated water was subject of investigation in many studies. Ionic strength and divalent ions concentration of the infiltrating water are known to influence the transport behaviour of trace metals by controlling dissolution and stabilization. As a new approach for water desalination, the aim of the cooperative project “innovatION” is the development of a monovalent-selective membrane capacitive deionization method to remove monovalent ions from brackish water. Other than fully desalinated water, the product water is still enriched in divalent ions. Here, we present first insights on how trace metal transport during MAR depends on the chemistry of the infiltrating water. Trace elements, as for example As, were found in sands of the East Frisian Island Langeoog, Northern Germany, and could be mobilized during potential MAR. We conducted column experiments with infiltration of a fresh groundwater (fGW), monovalent partial desalinated water (mPDW) and pure water (PW) into grey dune sand from Langeoog.

Our results show As mobilization due to shifting redox conditions and iron mineral dissolution up to a maximum of 16 µg/l in the outflow. Notably, the infiltration of mPDW, with a higher ionic strength than fGW and PW, lead to a temporary retention of As with a concentration decline to 2 µg/l and subsequently a slow increase. Whereas As is further mobilized with a very slow decrease with infiltration of fGW and PW. Arsenic concentrations were positively connected to dissolved organic carbon concentrations of the outflow, an indication that organic complexation of As takes place after dissolution of Fe-minerals. Clearly, the infiltration of mPDW can mitigate potentially harmful colloidal trace element transport. These results help to understand the mechanisms of sorption, desorption and transport of trace metals in environments with changing pore water chemistry during MAR. Our research also aids to better assess the functionality of this novel desalination technique that has high potential to improve groundwater quality.

How to cite: Braeunig, L., Longman, J., Gäng, F., and Massmann, G.: Trace metal transport during managed aquifer recharge with monovalent-partial desalinated water: The role of divalent ions and organic matter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15009, https://doi.org/10.5194/egusphere-egu24-15009, 2024.

EGU24-15729 | ECS | Posters on site | SSS5.3

The influence of liming with oil-shale ash on the soluble P fraction in soil 

Tonu Tonutare, Raimo Kõlli, Tõnis Tõnutare, and Kadri Krebstein

The acidification of agriculturally used soils is a widely known phenomenon. Acidification may be caused by various factors. One part of the acidification results from natural processes, including acid plant root exudates and the oxidation of flora and fauna residues in the soil. Another contributing factor is acidic rain, which may have a natural origin or be caused by human activities such as burning coal, sulfur-containing materials, and emissions from metallurgy and chemical factories.

For sustainable agriculture, it is essential to maintain the optimum soil pH to ensure high yields. Typically, liming is employed to establish the suitable pH for plant growth, using carbonaceous materials. Commonly used materials include milled limestone or dolomite, and sometimes ashes from biomaterial. In Estonia, for over 60 years, fly ash from the burning of oil shale in power plants has been used for liming agriculturally used fields. However, the bottom ash from power plants remains unused and is stored in ash hills, accumulating to more than 600 million tons. This ash is an alkaline material with a high content of calcium, potassium, and magnesium. In 2025, the company RagnSells plans to start an experimental factory producing high-quality CaCO3 from this ash. The residue of this process will be a white solid alkaline material with an increased content of magnesium, making it suitable for liming agriculturally used fields. As liming can lock some phosphorus in the soil into an insoluble phase, there may be a decrease in soluble (plant-available) phosphorus. Therefore, we conducted an incubation experiment with this experimental liming agent on three different soils and used two fertilizer norms.  Our research aimed to monitor changes in water-extractable and plant-available P (by the AL method) content in different soils during a 24-week incubation period.

How to cite: Tonutare, T., Kõlli, R., Tõnutare, T., and Krebstein, K.: The influence of liming with oil-shale ash on the soluble P fraction in soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15729, https://doi.org/10.5194/egusphere-egu24-15729, 2024.

Planting trees on non-forested land has the potential to sequester atmospheric CO2 in biomass and soil. While afforestation on former agricultural land often results in an increased soil organic carbon sequestration, the outcomes of afforestation on pastures vary from carbon sink to source. Alpine soils are characterized by a higher proportion of labile carbon compounds compared to soils in temperate ecosystems, which makes alpine ecosystems more sensitive to environmental changes. The conversion of subalpine pasture to forests thereby might have a substantial effect on the SOC dynamics and  on soil organic matter (SOM) stabilization. In addition, the alteration in the proportion of aboveground biomass- and root-derived organic matter and the associated alterations in the soil microbial community following afforestation on subalpine pastures are not yet fully understood.

In this study, the alteration in SOC stocks as well as in the SOM composition following  afforestation (0 to 130 years) with Norway spruce (Picea abies) on a subalpine pasture is investigated in the Swiss Alps. To determine the alteration of potential sources and decomposition of SOM, a multi-proxy molecular marker approach was applied. Specifically, the combination of n-fatty acids, n-alkanes, and n-alcohols was applied to identify possible sources of plant-derived SOM. For the identification of microorganism-derived SOM, a combination of phospholipid fatty acids and glycerol dialkyl glycerol tetraethers was used.

Afforestation with Norway spruce on a subalpine pasture did not result in any significant change in SOC stocks (Pasture: 11.5 ± 0.5 kg m-2; 130-year-old forest 11.0 ± 0.3 kg m-2) after 130-years. The organic matter input, however, changed from grass leaves to spruce needles with increasing forest stand age. Surprisingly, root-derived organic matter seems to play a minor role in the pasture soil as well as in forest soils of all stand ages as one of the predominant sources of SOM. With increasing forest age an increased abundance of Gram+ bacteria as well as arbuscular mycorrhizal fungi was observed. In the pasture soil, a clearly higher abundance of archaea was observed compared with the forest. This shift in the soil microbial community shows its adaptation to the changes in the vegetation cover.  Furthermore, the difference in the soil microbial community structure implies a use of different carbon substrates of the microorganisms between the pasture and forests, which can have substantial effects on soil organic matter stabilization. Conclusively SOC stocks did not change after 130 years of afforestation on a subalpine pasture, but the SOM dynamics has changed due to the changes in the vegetation cover. For a better understanding of the connection between organic matter input and its decomposition, the analysis of plant polymers such as cutin and suberin polymers can help to unravel the difference in shoot- vs. root-derived organic matter and their contribution to the stable SOM pool in subalpine ecosystems.

How to cite: Speckert, T. C. and Wiesenberg, G. L. B.: Afforestation on a subalpine pasture does not result in an increase in carbon sequestration but in a change in the soil organic matter (de)composition  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18440, https://doi.org/10.5194/egusphere-egu24-18440, 2024.

EGU24-18712 | ECS | Orals | SSS5.3

Drought induces changes to redox chemistry and C exports from boreal riparian soils 

Martin Škerlep, Melissa Reidy, Hjalmar Laudon, and Ryan Sponseller

Extreme summer droughts can drastically lower water tables and lead to oxygenation of normally anoxic soils in boreal ecosystems. In organic rich riparian soils, this creates a dynamic redox environment, driving changes in soil organic matter stability and the export of redox sensitive elements (e.g., C, N, S, Fe, etc.) to surface waters.  We hypothesized that the destabilization of redox cycles and the activation of oxidative soil enzymes during drought periods can lead to prolonged periods of altered soil biogeochemical processes that drive element export from terrestrial to surface water systems upon rewetting. Here we simulated a soil core drying-rewetting event, to ask how riparian soil solution biogeochemistry changes during two months post drought. To three drought treatments (dry, semi-dry, wet), we also added a root exudate treatment (exudates or no exudates) to simulate the effects of riparian vegetation on microbial organic matter decomposition. We found that following drought, dissolved organic carbon (DOC) concentrations initially decreased, due to the increased acidity caused by the oxidation of reduced S to SO42-. As other preferred electron acceptors (O2, NO32-, Fe3+) were gradually reduced, reduction of SO42- lead to increases in DOC concentrations, which after 2 weeks surpassed concentrations in the control (wet) treatment, and continued increasing until the end of the experiment. Once SO42- was depleted and CO2 became the preferred electron acceptor, methane (CH4) in solution also increased to concentrations higher than those in control treatments. Peroxidase activity was increased post drought and remained elevated throughout the experiment, suggesting that microbial organic matter breakdown was enhanced, and could explain why DOC concentrations in drying treatments eventually surpassed those in wet controls. While the root exudate treatments produced mixed results, an increase of labile C supply appeared to increase extracellular enzymatic activity and serve as an alternative electron acceptor, thereby suppressing methanogenesis. Our results show that drought drastically changes the biogeochemistry of boreal riparian soils and that upon rewetting this can eventually lead to increased lateral exports of both organic and inorganic C. Changes in C biogeochemistry are seemingly caused by shifts in redox chemistry and by changes in microbial decomposition of soil organic matter induced by the oxygenation of riparian soils. Since this has implications for surface water chemistry, further study is needed on the length of drought effects to establish the duration of this influence of stream and riparian biogeochemistry.

How to cite: Škerlep, M., Reidy, M., Laudon, H., and Sponseller, R.: Drought induces changes to redox chemistry and C exports from boreal riparian soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18712, https://doi.org/10.5194/egusphere-egu24-18712, 2024.

EGU24-18833 | ECS | Posters on site | SSS5.3

Changes in soil organic matter forms after the conversion of a meadow into a rainfed forage maize-ley grassland rotation cropland 

Ana María Martínez-Solino, Carmen Trasar-Cepeda, Carmela Monterroso, Beatriz Rodríguez-Garrido, Serafín González-Prieto, and Ángeles Prieto-Fernández

Agricultural management deeply affects soil properties, with soil organic matter (SOM) being among those most impacted. Nowadays, the importance of adopting agricultural management systems and practices that enhance the storage and stabilization of organic matter in the soil is widely accepted. In this context, the analysis of different SOM fractions is essential for evaluating its stability and obtaining valuable information about its potential long-term persistence.

In the present study 0-10 cm and 10-20 cm soil samples were collected 2 months and 2 years after the conversion of an old meadow into a rainfed forage maize-ley grassland rotation system. Similar reference soil samples were taken from an undisturbed area of the meadow. The SOM in samples collected was analysed using different chemical extractants and particulate organic matter (POM) and mineral associated organic matter (MAOM) were studied using a physical fractionation method (Lopez-Sangil and Rovira, 2013 with unpublished modifications suggested by P. Rovira).

The conversion of the meadow into the rotation cropland induced a reduction of soil organic C content and modifications of SOM fractions. Generally, the changes were detected in the first sampling and persisted two years after the implementation of the rotation system. The modification induced by the agricultural management were more pronounced in the 0-10 cm layer than in the 10-20 cm layer.

Lopez-Sangil L., Rovira P. 2013. Soil Biol. Biochem. 62, 57–67

How to cite: Martínez-Solino, A. M., Trasar-Cepeda, C., Monterroso, C., Rodríguez-Garrido, B., González-Prieto, S., and Prieto-Fernández, Á.: Changes in soil organic matter forms after the conversion of a meadow into a rainfed forage maize-ley grassland rotation cropland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18833, https://doi.org/10.5194/egusphere-egu24-18833, 2024.

EGU24-20796 | Orals | SSS5.3 | Highlight

Predicting Soil Nitrogen Mineralization Potential using Pyrolysis-coupled FTIR 

Sevendeep Kaur and Adam Gillespie

Soil nitrogen (N) is a key component of plant nutrition but our ability to predict organic N mineralization potential remains incomplete.  Several methods are commonly used to characterize and measure mineralizable N; however, they are generally lacking because of required lab resources and poor predictive power. Pyrolysis is an emerging technology used to characterize soil organic matter and the thermal stability of soils. However, the idea of using Pyrolysis technology to characterize soil N and measure soil N release is novel. We adopted a novel online pyrolysis coupled with FTIR (Fourier-transform infrared spectroscopy) technology to investigate soil N. The soil samples used were collected from a long-term field trial involving different crop rotations and fertilization to include a wide array of samples. Samples were pyrolyzed from 25 to 850 °C with a heating rate of 10 K min-1. The temperature at which 50% of the material underwent pyrolysis, referred to as T50, was determined to quantify the thermal stability. The focus was to look at mass loss characteristics, identify volatile matter released, T50, and the correlation of TG-FTIR data with a 12-week lab mineralization study. We found a negative correlation (R2= -0.67) between the T50 and mineralized N at week 12. In conclusion, this study elucidates the intricate interplay between temperature kinetics and nitrogen mineralization. The negative correlation between T50 and mineralizable N underscores the potential of the material to release N over time. This research offers a valuable foundation for optimizing Pyrolysis application in the context of soil nitrogen. 

How to cite: Kaur, S. and Gillespie, A.: Predicting Soil Nitrogen Mineralization Potential using Pyrolysis-coupled FTIR, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20796, https://doi.org/10.5194/egusphere-egu24-20796, 2024.

EGU24-416 | ECS | Posters on site | BG1.10

The dissolution pattern of the flattened otolith of Pacific cod using the stepwise acid dissolution method 

Keito Aonuma, Yusuke Yokoyama, Yosuke Miyairi, Masayuki Chimura, Tomonori Hamatsu, Osamu Sakai, and Guido Plaza

The inner ear of fish contains calcium carbonate (CaCO3)-based crystals called otoliths, which play an essential role in hearing and balance. During otolith formation, new calcium carbonate is deposited in layers on the surface of the existing part and the part is no longer affected by metabolism. This feature means that each layer of the otolith retains the trace element ratios and isotope ratios it had at the time of formation. By analysing this preserved information, it is possible to make estimates about the environment and habitat at that time.

The stepwise acid dissolution method has been used in several studies as a technique for analysing the radiocarbon isotope ratios preserved in otoliths. In this method, phosphoric acid is used to dissolves the otolith from the outermost to the innermost layers. It has the advantage that a large amount of carbon can be collected from a single otolith, compared to the mechanical methods for the calcium carbonate sampling from each layer of the otolith.

However, this method involves dissolving the otolith in acid and the pattern of dissolution cannot be controlled minutely by the experimenter. Pacific cod (Gadus macrocephalus) otolith used by us is flattened and the dissolution pattern of such otoliths is not yet known. Furthermore, no direct observation of the otolith dissolution process has been made in relation to previous studies.

In this study, we dissolved three Pacific cod otoliths in phosphoric acid to directly confirm the process of otolith dissolution in the stepwise acid dissolution method. We removed each otolith from the acid one or more times during the dissolution process, weighed it and observed the change in the shape of the otolith and the layer structure exposed on the otolith surface. As the dissolution progressed and the otoliths became smaller, we polished them to check that the internal layered structure had not been destroyed by acid penetration.

As a result, we found that the serrated structures present on the outer edges of the otoliths are maintained when they are dissolved from the outside by acid. We also confirmed that acid dissolution from the outside does not destroy the inner layer structure, even microstructures such as daily rings. The validity of the stepwise acid dissolution method would be strengthened by these results. On the other hand, the otoliths were thinner as a result of acid dissolution, exposing the more inner layers on the flat surface. This is due to the thin vertical thickness of the flattened otoliths. This observation suggests that the collected carbon may be mixed with the carbon collected from more inner layer. This carbon mixing is able to be taken into account with future work. In addition, care should be taken when using this method near the nucleus, as the final stage of dissolution results in multiple holes in the otolith.

How to cite: Aonuma, K., Yokoyama, Y., Miyairi, Y., Chimura, M., Hamatsu, T., Sakai, O., and Plaza, G.: The dissolution pattern of the flattened otolith of Pacific cod using the stepwise acid dissolution method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-416, https://doi.org/10.5194/egusphere-egu24-416, 2024.

EGU24-815 | ECS | Orals | BG1.10

From sediments to the atmosphere: a mass spectrometry approach revealing structural dissimilarities of common NOM components 

Alexander Zherebker, Oliver Babcock, Roman Vasilevich, and Chiara Giorio

Natural organic matter (NOM) is a complex mixture of thousands of organic molecules that reflects environmental conditions and chemical transformations occurring nowadays or in the past. Fourier transform mass spectrometry (FTMS) resolves isobaric constituents and it is widely applied to obtain aquatic, terrigenous and aerosol NOM fingerprints. Traditionally, comparison of mass peak intensities is used to make a distinctive conclusion about samples behavior, but it has the limitation of omitting structural information on the corresponding ions. Due to the stochastic character of NOM synthesis, drastically different samples may appear as resembling, which hampers mechanistic study of NOM dynamics and its attribution to the source. Here we present how implementation of chemical and isotopic tagging in combination with FTMS helps to overcome this issue. The developed approach provides an upper boundary for the presence of specific structural features, e.g. functional groups, in individual NOM components. This facilitates a clear distinction between different NOM samples, which would share isobaric ions, and provides insights on isomeric complexity of these ions. The advantages of the method were demonstrated on two sets of samples. Firstly, we collected permafrost peat cores from different depths in the European Arctic region, which varied in corresponding botanical conditions, peat degradation and oxidation states. Selective deuteromethylation and bromination coupled to FTMS enabled to capture structural differences between shared ions, which differed in carboxylic functionality and aromaticity. Surprisingly, structural differences were found for ions, which abundance positively correlated with peat characteristics and geo-temporal conditions. The second set included aerosol particles collected in marine, rural and urban areas. Application of in-source H/D exchange for FTMS analysis of extracted NOM enabled to enumerate functional groups in shared ions and point molecular constituents with similar and distinct structural features. The observed trends serve to better understand aerosol formation processes and accompanied conventional formula-based statistical analysis including better understanding of Kendrick mass defect series.

How to cite: Zherebker, A., Babcock, O., Vasilevich, R., and Giorio, C.: From sediments to the atmosphere: a mass spectrometry approach revealing structural dissimilarities of common NOM components, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-815, https://doi.org/10.5194/egusphere-egu24-815, 2024.

EGU24-1109 | ECS | Orals | BG1.10

Post fire Black Carbon alteration: Rapid changes in a supposedly inert pool 

Oliver Donnerhack, Patrick Liebmann, Philipp Maurischat, and Georg Guggenberger

Forest fires are among the most influential disturbances in ecosystems and have varying effects on the soil depending on fire intensity and biomass consumption. The significant decline in biodiversity in European forests due to centuries of non-sustainable forest management, combined with worsening drought from climate change, has greatly increased vulnerability to wildfires. Incomplete combustion during fires leads to the formation of black carbon (BC), a group of substances known for their persistence in soil. However, studies suggest that medium-condensed BC species may have lower chemical and spatial stability and are therefore potentially more mobile and consequently only serve as temporary carbon sinks.

In order to assess the mobilization of BC, we investigate short-term changes in BC under field conditions, particularly of the low-condensed BC, and call into question the established concept of the general stability of BC pools. We investigated the dynamics of BC alterations during the post-fire period within one winter, following a late summer forest fire. We selected two comparable sites featuring spruce-dominated forest stands with different geologic parent material and weather conditions, particularly with respect to the amount of precipitation during the observation period. We sampled soil profiles down to 40 cm depth shortly after the fire event in late summer and after a 6-month period in late spring. After performing density fractionation to separate the mineral associated organic matter (MAOM) from particulate organic matter (POM), we analysed the BC content in the MAOM fraction using benzene polycarboxylic acids (BPCA) analysis.

The results show a high content of low to medium condensed BPCAs directly after fire, which decreased, especially the medium condensed BPCA marker, during the observation period. Taking into account the fast change in medium BPCA values in the MAOM fraction, we conclude that the general assumption that BC is in principle a stable, long-term carbon sink needs to be addressed more carefully.

How to cite: Donnerhack, O., Liebmann, P., Maurischat, P., and Guggenberger, G.: Post fire Black Carbon alteration: Rapid changes in a supposedly inert pool, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1109, https://doi.org/10.5194/egusphere-egu24-1109, 2024.

EGU24-1180 | ECS | Orals | BG1.10

Net CO2 release during chemical weathering in the north-western Himalaya: A dominant role of pyrite oxidation 

Rakesh Kumar Rout, Gyana Ranjan Tripathy, Satyabrata Das, and Santosh K. Rai

Oxidation of pyrites plays a key role in global chemical and climatic cycles. In particular, interaction of sulfuric acid produced through this process with carbonates releases CO2 to the atmosphere. This CO2 source counterbalances the CO2 consumed during silicate weathering in river basins, and hence, may influence earlier-suggested linkage between silicate weathering and global cooling events. In this study, we have investigated the dissolved major ions and sulfur isotopes of Indus headwaters to quantify the net effect of sulfide oxidation on the CO2 budget. This research is an attempt to evaluate the coupling between global Cenozoic cooling event and Himalaya weathering - ­a hypothesis which overlooked the CO2 supply via sulfide and organic oxidation. Towards this, we have employed sulfur isotopes (δ34S) as a proxy for riverine sulfate sources, mainly due to its distinct composition for the two major end-members [pyrite (~ -12 ‰) and gypsum (~ 17 ‰); [1]]. The average sulfate concentrations for the Indus headwaters are found to be higher than the regional rainfall, global average for rivers, and other major Himalayan rivers (e.g., Ganga and the Brahmaputra). Consistently, the mean δ34S for the Indus headwaters is also depleted with respect to that reported for the Ganga (~ 2 ‰) and Brahmaputra (~ 4 ‰) outflows [1-5]. Also, the sulfur isotopic values for the Indus headwaters are systematically depleted by 3 to 4 ‰ than that reported earlier for Indus mainstream [3]. These lighter δ34S values for the headwaters hint at relatively higher sulfide oxidation in the northwestern (NW) Himalaya compared to central and eastern Himalayas. Also, these processes are found to be more intense in the mountainous regions than in the floodplains. These observations are consistent with the basin lithology dominated by Paleozoic carbonates and organic-rich shales, and higher glacial coverage. Estimation of sulfide-derived cations from carbonate weathering and silicate-derived cations indicate that the chemical weathering in the Indus headwaters serve as a net source of CO2 to the atmosphere. This finding is in contrast with previous suggestion of significant CO2 removal during the Himalaya weathering and hence, challenges the role of land surface processes in the NW Himalaya in regulating the Cenozoic cooling event.

 

 

References

[1] Burke et al., (2018), Earth Planet. Sci. Lett., 496, 168-177.

[2] Chakrapani et al., (2009), J. Asian Earth Sci., 34, 347-362.

[3] Karim and Veizer, (2000), Chem. Geol., 170, 153-177.

[4] Kemeny et al., (2021), Geochim. Cosmochim. Acta, 294, 43-69.

[5] Turchyn et al., (2013), Earth Planet. Sci. Lett., 374, 36-46.

How to cite: Rout, R. K., Tripathy, G. R., Das, S., and Rai, S. K.: Net CO2 release during chemical weathering in the north-western Himalaya: A dominant role of pyrite oxidation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1180, https://doi.org/10.5194/egusphere-egu24-1180, 2024.

EGU24-1546 | Posters on site | BG1.10

Soil chemistry and hydrophobicity caused by four 2021-22 western U.S. megafires. 

Vera Samburova, Eric Schneider, Christopher Rüger, Brad Sion, Lukas Friederici, Yasaman Raeofy, Markus Berli, Palina Bahdanovich, Hans Moosmüller, and Ralf Zimmermann

In the past decade, the size, frequency, and severity of wildfires have increased around the world, especially in forests of the western United States, where ecosystems are dominated by dry conifer forests. It is known that fires can greatly affect not only air quality, climate, forest, and fauna, but also soil. The heat from fires can alter soil chemistry and change soil water repellency (SWR). SWR can reduce soil infiltration, which can increase surface runoff, erosion, and the potential for flooding and mud and debris slides. The increased frequency and intensity of western U.S. wildfires due to the rapidly changing climate poses an important question: What are the short- and long-term effects of wildfires on soil’s hydrologic responses, including SWR, and what is the role of fire-induced chemistry in SWR?

In the summer and fall of 2021 and 2022, there were four mega-wildfires (Caldor, Dixie, Beckwourth Complex, and Mosquito) in the Eastern Sierra Nevada mountains (California, USA). These wildfires provided us an opportunity to collect post-fire soil and ash samples and study the effects of fires on the physical and chemical properties of soils. We collected over 80 samples and performed multiple water-droplet penetration time (WDPT) tests in the field and, in the laboratory, apparent contact angle (ACA) measurements with the goniometer technique. For all four fires, a significant increase in SWR was observed between unburned and burned soils, with WDPT increasing from <1 s to 600 s (maximum measured value) and ACA values increasing between 1.1 and 9 times (p-value < 0.001). Our WDPT and ACA measurements of the samples collected 6 months and 1 year after the 2021 megafires (Dixie, Caldor, and Beckwourth Complex megafires) showed no significant changes in SWR for unburned and burned soils. The chemical analysis of organic constituents of unburned and burned soils with ultra-high-resolution mass spectrometry (thermogravimetry atmospheric pressure photoionization in combination with Fourier transform ion cyclotron resonance mass spectrometry or TG APPI FT-ICR MS) suggests that burned soils became water-repellent due to the formation and/or deposition of aromatic organic species (e.g., polycyclic aromatic hydrocarbons or PAHs) on the soil surface during fires. We found a positive correlation (R2 = 0.813) between the ACA values of analyzed fire-affected samples and aromaticity derived from the TG APPI FT-ICR MS spectra.

These results of our research highlight the importance of future research on the chemical composition of post-fire soils and the need to study the long-term effects of fires on soil properties.

How to cite: Samburova, V., Schneider, E., Rüger, C., Sion, B., Friederici, L., Raeofy, Y., Berli, M., Bahdanovich, P., Moosmüller, H., and Zimmermann, R.: Soil chemistry and hydrophobicity caused by four 2021-22 western U.S. megafires., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1546, https://doi.org/10.5194/egusphere-egu24-1546, 2024.

EGU24-1595 | ECS | Posters virtual | BG1.10

Hyperspectral Reflectance of Pre- and Post-Fire Soils: Toward Remote Sensing of Fire-Induced Soil Hydrophobicity 

Yasaman Raeofy, Vera Samburova, Markus Berli, Brad Sion, and Hans Moosmüller

Recently, wildfire activity and intensity in the western U.S. have greatly increased, mainly due to a warming climate, population growth, land use changes, and fuel accumulation. Disastrous effects during fires include loss of human lives and infrastructure, ecosystem disturbances, and emissions of carbon dioxide and air pollutants. In addition, wildfires modify physical and chemical soil properties and can cause Fire-Induced Soil Hydrophobicity (FISH), which reduces water infiltration into the soil and accelerates runoff during precipitation events. This may induce cascading disasters including flooding, landslides, and deterioration of water quality. To predict and mitigate such disasters, FISH is generally quantified at a few fire-affected locations using a manual infiltration test. However, this limited spatial coverage poorly represents FISH on a watershed scale as needed for prediction and mitigation purposes.

Watershed-wide, high-resolution monitoring of FISH is only practical using airborne or satellite-based remote sensing, for example utilizing solar reflectance spectra to characterize and monitor physical and chemical properties of fire-affected soils. Such spectra depend on light scattering and absorption at the soil surface. For this study, we have sampled ash, burned, and unburned soils, fresh (0 month), 1 year, and 2 years after three recent California (US) megafires: the Dixie (2021, 3,890 km2), Caldor (2021, 897 km2), and Beckwourth Complex (2021, 428 km2) fires. We studied the optical, chemical, and physical properties of all our samples. Optical hyperspectral reflectance spectra (350–2,500 nm) were obtained using natural solar (blue sky) illumination and a spectroradiometer (ASD FieldSpec3), operated in reflectance mode.  For all three fires, the results show that 700 nm wavelength reflectance of ash samples collected 1 and 1.5 years after the fire decreased between 36% and 76% compared to that of samples collected right after the fires. Additionally, significantly higher visible reflectance has been found for unburned compared to burned soil samples in each fire region that was studied. Fourier-transform infrared (FTIR) measurements were used to characterize the carbonate content of soil and ash samples demonstrating a positive relationship between carbonate content and visible reflectance, indicating a possible contribution of carbonate to the reflectance of soil/ash samples.

How to cite: Raeofy, Y., Samburova, V., Berli, M., Sion, B., and Moosmüller, H.: Hyperspectral Reflectance of Pre- and Post-Fire Soils: Toward Remote Sensing of Fire-Induced Soil Hydrophobicity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1595, https://doi.org/10.5194/egusphere-egu24-1595, 2024.

EGU24-1957 | ECS | Orals | BG1.10

Bacterial decomposition of dissolved organic matter: including the colloidal perspective 

Erika Andersson, Lars Tranvik, Marloes Groeneveld, Anders Tunlid, Per Persson, and Ulf Olsson

Dissolved organic matter (DOM) is a major carbon pool and considered the most bioavailable and most mobile fraction of organic matter. DOM is generally defined as the organic matter passing a filter pore size of 0.2 or 0.45 µm, and this size cut off means that DOM not only contains dissolved molecules but also colloidal objects and aggregates up to a few hundred nanometres. The properties of this colloidal DOM fraction, such as for example size, shape, and surface charge, will affect its actual bioavailability and mobility in the environment. Although previously not well studied, there has recently been a growing interest in this colloidal fraction of DOM.

We have studied DOM extracted by water from a boreal spruce forest soil, filtered through a 0.2 µm pore size. By using a combination of spectroscopy techniques, such as NMR, and light (SLS, DLS), X-ray (SAXS) and neutron (SANS) scattering techniques, we can access chemical and physical information on both the molecular and colloidal fractions of DOM.

Our results show that the colloidal DOM has a homogenous chemical composition, and that carbohydrates is the dominating chemical component in both the colloidal and molecular DOM. The colloids have a mass fractal structure which does not change upon dilution and they are electrostatically stabilised against aggregation. In a lab scale study, we investigated the bacterial decomposition of this DOM during a two-month incubation. The molecular fraction of DOM was quickly decomposed. However, no change was observed for the colloidal DOM, constituting ca. 50% of the carbon, indicating that it persisted bacterial decomposition.

Our results suggest that colloidal properties could be an important but hitherto overlooked aspect to the central question of what dictates organic matter reactivity and persistency in different environments and across different time scales. Our current work extends from soil solution to aquatic ecosystems, to assess the ubiquity of the colloidal fraction of DOM.

How to cite: Andersson, E., Tranvik, L., Groeneveld, M., Tunlid, A., Persson, P., and Olsson, U.: Bacterial decomposition of dissolved organic matter: including the colloidal perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1957, https://doi.org/10.5194/egusphere-egu24-1957, 2024.

EGU24-2117 | Orals | BG1.10

Biochar enhanced microbial carbon use efficiency, while reducing mineralization of added and native soil organic carbon 

Kristiina Karhu, Subin Kalu, Aino Seppänen, Kevin Mganga, Outi-Maaria Sietiö, and Bruno Glaser

Biochar can increase long-term soil organic carbon (SOC) storage due to its polyaromatic structure. In addition to the recalcitrant carbon (C) contained in the biochar itself, biochar can also increase SOC storage by adsorption or organic matter on its surfaces, and reduced decomposition rate of native SOC (negative priming). Limited number of studies have looked at how biochar affects decomposition and stabilization of fresh C inputs, and native SOC decomposition. To fill this knowledge gap, we conducted a laboratory incubation study, where we followed the fate of added 13C-labeled glucose in a fine-textured agriculturally used soil (Stagnosol) amended with two different biochar levels corresponding to 15 and 30 Mg ha-1 in field conditions. Biochar addition reduced mineralization of SOC and added 13C glucose, while increasing microbial biomass and microbial carbon use efficiency (CUE). Most of the added biochar, as well as remaining 13C were found in the free particulate organic matter (POM) fraction after 6 months, indicating that added 13C glucose was preserved within the biochar particles. Our closer study of 13C amino sugar fraction extracted from the biochar particles revealed that the microbes that had efficiently grown on the added 13C glucose in the presence of biochar, were retained as dead microbial residues inside the biochar pores. This microbial route could provide a way for additional formation of rather recalcitrant C in the form of microbial residues in the presence of biochar, which could with time contribute to building SOC stock in biochar amended soils beyond the C present in biochar itself. We found that biochar also increased the portion of occluded POM in the treatments without 13C glucose addition, demonstrating that increased soil occlusion following biochar addition reduced SOC mineralization. The effects were found to be dose-dependent, i.e. higher biochar application rate resulted in lower mineralization rate of native SOC and of added 13C-glucose.

How to cite: Karhu, K., Kalu, S., Seppänen, A., Mganga, K., Sietiö, O.-M., and Glaser, B.: Biochar enhanced microbial carbon use efficiency, while reducing mineralization of added and native soil organic carbon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2117, https://doi.org/10.5194/egusphere-egu24-2117, 2024.

Elevated concentration levels of geogenic ammonium in groundwater arise from the mineralization of nitrogen-containing natural organic matter in various geological settings worldwide, especially in alluvial-lacustrine and coastal environments. However, the difference in enrichment mechanisms of geogenic ammonium between these two types of aquifers remains poorly understood. To address this knowledge gap, we investigated two representative aquifer systems in central Yangtze (Dongting Lake Plain, DTP) and southern China (Pearl River Delta, PRD) with contrasting geogenic ammonium contents. The use of optical and molecular characterization of DOM combined with hydrochemistry and stable carbon isotopes has revealed differences in DOM between the two types of aquifer systems and revealed contrasting controls of DOM on ammonium enrichment. The results indicated higher humification and degradation of DOM in DTP groundwater, characterized by abundant highly unsaturated compounds. The degradation of DOM and nitrogen-containing DOM was dominated by highly unsaturated compounds and CHO+N molecular formulas in highly unsaturated compounds, respectively. In contrast, the DOM in PRD groundwater was more biogenic, less degraded, and contained more aliphatic compounds in addition to highly unsaturated compounds. The degradation of DOM and nitrogen-containing DOM was dominated by aliphatic compounds and polyphenols and CHO+N molecular formulas in highly unsaturated compounds and polyphenols, respectively. As DOM degraded, the ammonium production efficiency of DOM decreased, contributing to lower ammonium concentrations in DTP groundwater. In addition, the CHO+N(SP) molecular formulas were mainly of microbial-derived and gradually accumulated with DOM degradation. In this study, we conducted the first comprehensive investigation into the patterns of groundwater ammonium enrichment based on DOM differences in various geological settings.

How to cite: Xiong, Y.: Characteristics of Dissolved Organic Matter Contribute to Geogenic Ammonium Enrichment in Coastal versus Alluvial-lacustrine Aquifers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3292, https://doi.org/10.5194/egusphere-egu24-3292, 2024.

EGU24-3355 | Posters on site | BG1.10

NOM quality differences in sediments of land based aquacultures – insights by liquid chromatography-high resolution mass spectrometry 

Peter Herzsprung, Carolin Waldemer, Matthias Koschorreck, and Oliver Lechtenfeld

Natural organic matter (NOM) was widely investigated in natural waters, sea water, river water, lake water, groundwater. The highest molecular resolution of NOM can be achieved by Fourier-transform ion cyclotron resonance mass spectroscopy (FT-ICR-MS). This analytical tool generates molecular formulas (MF) for thousands of NOM components. By coupling liquid chromatography to FT-ICR-MS insights into the polarity (hydrophilic versus hydrophobic) of NOM compounds can be achieved.

Anthropogenic inputs have an imprint on NOM and it changes its overall composition. Aquaculture is one of the fastest growing sectors of food production by covering over 8 Mio ha. The consequences of fish farming for the organic matter quality in fish pond waters and sediments are poorly understood. Here we investigated the stages of pollution by comparison the water extractable organic matter (WEOM) in the sediment at the main site of fish feed application and open water sediments at different distances (transect) to the feeding site.

Full profile HPLC-FTICR-MS chromatograms were segmented into approx. one-minute wide segments between 10 and 15 Min (five segments), the main eluting region of WEOM. MF were calculated for the mass range 150 - 1000 Da with an error threshold of 1 ppm using in-house software considering the following carbon (C), hydrogen (H), oxygen (O), nitrogen (N) and sulphur (S) elements: 12C0–60, 13C0–1, 1H0–122, 16O0–40, 14N0–8, 32S0–3, and 34S0–1.

For all retention times, N3, N4, N5, N6, N7 (CHNO) MF with 0.2 < O/C < 0.5 and 1.5 < H/C < 2.0 showed relative higher intensities in the feeding center compared to the distant sites. For some MF like C20H37N5O7, C22H39N5O7, C24H42N6O10 the intensity was more than five times higher in the center compared to open water site. Such components can be suggested to be oligopeptides (Leu-Asn-Thr-Ile, Glu-Pro-Lys-Ile, Leu-Leu-Asp-Ser-Gln as possible isomeric solutions). The sediment in the feeding center exhibited a prevalence of CHNOS and CHOS2 MF, whereas N1, N2, CHOS1, and CHO displayed relatively uniform intensities along the transect, with some instances of slightly higher intensities observed away from the feeding site. The number and abundance of CHNOS MF decreased with increasing retention time (decreasing polarity). Notably, these compounds appear to be inherently hydrophilic, characterized by predominantly low molecular weights (< 400 Da).

The results obtained suggest the following biogeochemical processes: Initially, the protein-rich fish feed undergoes hydrolysis, leading to the formation of oligopeptides. Subsequent partial desamination of these molecules facilitates their interaction with inorganic sulphides, resulting in the formation of CHNOS MF. Notably, the component C8H13N1O3S1, exhibiting a five-fold intensity at the feeding site, appears to correspond to one of the possible metabolites (Sulfanylpropanoyl-proline).

The results indicate a potential overfertilization with easily biodegradable protein-rich substances. The WEOM quality seems highly affected by additional input of CHNO, CHNOS and CHOS.

How to cite: Herzsprung, P., Waldemer, C., Koschorreck, M., and Lechtenfeld, O.: NOM quality differences in sediments of land based aquacultures – insights by liquid chromatography-high resolution mass spectrometry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3355, https://doi.org/10.5194/egusphere-egu24-3355, 2024.

EGU24-3667 | ECS | Orals | BG1.10

Rapid lateral transport of fresh dissolved organic matter to the deep ocean in the NE Atlantic 

Bingbing Wei, Michael Seidel, Gesine Mollenhauer, Hendrik Grotheer, Jenny Wendt, Thorsten Dittmar, and Moritz Holtappels

Deepwater formation in the North Atlantic Ocean is a major gateway for dissolved organic matter (DOM) transport into the deep ocean. Despite focusing on vertical mixing, lateral transport of DOM from productive shelf regions is underexplored. Previous research suggested substantial offshore DOM transport on the Irish and Hebrides Margin via the bottom Ekman Drain. Our in-depth bottom water DOM analyses of carbon isotopes in combination with ultrahigh-resolution mass spectrometry (FT-ICR-MS) indicated that downwelling in this region leads to higher DOM concentrations (by 7–11 μM) and younger radiocarbon ages (by 190–330 yrs) compared to DOM of the central Northeast Atlantic at similar depths. During downslope transport, conservative mixing shapes the molecular composition of recalcitrant DOM, while minor particulate organic matter degradation contributes to producing less-refractory DOM with terrigenous signals. Consequently, the bottom Ekman transport emerges as a rapid and efficient channel for transporting fresh DOM into the deep North Atlantic Ocean, acting as a crucial carbon sink for atmospheric CO2.

How to cite: Wei, B., Seidel, M., Mollenhauer, G., Grotheer, H., Wendt, J., Dittmar, T., and Holtappels, M.: Rapid lateral transport of fresh dissolved organic matter to the deep ocean in the NE Atlantic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3667, https://doi.org/10.5194/egusphere-egu24-3667, 2024.

EGU24-3890 | ECS | Posters on site | BG1.10

Carbon cycling in coexisting marine ecosystems: Cold seeps and coral reefs in Northern Norway 

Muhammed Fatih Sert, Knut Ola Dølven, Sebastian Petters, Timo Kekäläinen, Janne Jänis, Jorge Corrales-Guerrero, and Bénédicte Ferré

Cold seeps and cold water corals (CWCs) coexist on Northern Norway's continental shelf at the Hola trough between Lofoten and Vesterålen. Here, cold seeps release methane from the seabed, yet only a limited amount reaches the atmosphere. The remaining methane dissolves and disperses in nearby seeps. Methane is unreactive for most microorganisms in the water column, yet it is a unique energy and carbon source for methane-oxidizing bacteria (MOB). MOBs metabolize methane and release carbon dioxide as the end product of oxidation. Increasing carbon dioxide may constrain pH-sensitive CWCs in the region. We investigated the biogeochemistry of carbon, carbon isotopes, nutrients, dissolved organic matter (DOM) compositions and microbial diversity through water column profiles and water samples collected in June 2022. Preliminary results indicated that elevated methane increases dissolved inorganic carbon concentrations and modifies carbon isotopic compositions. Additionally, DOM compositions implied a positive correlation between prokaryotic diversity and protein-like DOM components at cold seeps and the entire water column near CWCs, suggesting analogous microbial modifications. Our preliminary conclusion suggests cold seeps and CWCs symbiotically coexist in Northern Norway continental shelves; however, enhanced water temperatures and consequent increase in methane release at cold seeps may mitigate the functioning of CWCs in future.

This study is supported by the Research Council of Norway, project number 320100, through the project EMAN7 (Environmental impact of Methane seepage and sub-seabed characterization at LoVe-Node 7).

How to cite: Sert, M. F., Dølven, K. O., Petters, S., Kekäläinen, T., Jänis, J., Corrales-Guerrero, J., and Ferré, B.: Carbon cycling in coexisting marine ecosystems: Cold seeps and coral reefs in Northern Norway, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3890, https://doi.org/10.5194/egusphere-egu24-3890, 2024.

EGU24-5444 | ECS | Orals | BG1.10

Efficiency of Biological Carbon Pump: Insights from Compound-Specific Amino Acid δ15N 

Chen Li, Zhimin Jian, and Haowen Dang

As a vital component of the global carbon cycle, the ocean’s biological carbon pump determines the amount of carbon fixed by primary production in the surface waters. The efficiency of this biological pump is closely interconnected with the nitrogen cycle, which regulates nutrient inventory and primary productivity rates. Additionally, the structure of the upper ocean ecosystem influences the efficiency of the biological pump by determining how much fixed carbon is exported to the deep ocean. Compound-specific nitrogen isotope (δ15NAA) is a novel proxy that could provide valuable insights into both aspects of these questions. The δ15NAA could unravel isotopic information of source nitrogen and show δ15N changes associated with trophic processes. This study generates sedimentary δ15NAA, as well as bulk sediment δ15N and organic δ15N records from a western equatorial Pacific site (MD10-3340) covering the last 140 kyr. Our results demonstrate an overall agreement among three proxies, all indicating distinct precessional variations in source nitrate δ15N and potential changes in nutrient inventory. More importantly, the δ15NAA signatures suggest an inverse relationship between animal trophic activity in the surface water and the degradation of organic matter precipitating through the water column. Higher ecosystem trophic position is found during glacial periods, accompanied by inactive organic matter recycling, which implies a greater potential for carbon burial in deep reservoirs. Together, we suggest that the δ15NAAsignatures can provide a detailed picture of carbon cycle coupled with nitrogen cycle.

How to cite: Li, C., Jian, Z., and Dang, H.: Efficiency of Biological Carbon Pump: Insights from Compound-Specific Amino Acid δ15N, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5444, https://doi.org/10.5194/egusphere-egu24-5444, 2024.

EGU24-5586 | Orals | BG1.10

Temporal and spatial changes in DOM revealed by FT-ICR MS 

Catherine Moody, Nicholle Bell, Logan Mackay, and Ezra Kitson

DOM from peatlands is a collection of complex molecules, but also a significant source of carbon to aquatic pathways. It has a wide impact on aquatic ecosystems, providing an energy source for microbes and buffering capacity for water chemistry changes. The composition of DOM in drinking water reservoirs also impacts on chemical and energy demands of treatment processes, and is an area of growing concern for UK drinking water providers.

DOM was extracted from water collected from peatland headwater streams and reservoirs in the UK. The DOM was analysed with elemental analysis and FT-ICR MS to determine how the composition changes as water moves through the catchment. A combination of spatial and temporal sampling strategies allowed seasonal and catchment characteristics to be investigated (from 2018-2021, and 53-61°N).

There were significant trends in DOM composition metrics across a north/south gradient, with higher lipid content, and lower carbohydrate and peptide content in northern sites than southern sites. Samples collected in 2021 had several significant composition differences to other years. Monthly sampling showed the largest changes in DOM composition coincided with the end of the growing season (September in the UK).

These results show variable DOM in headwaters can be, and how reservoirs act to buffer the most extreme changes, resulting in more stable DOM compositions in reservoirs. Understanding how DOM composition is impacted by season, climate and catchment characteristics will have important ramifications for drinking water providers, and will help catchment managers plan land use changes and timing of water draw-off from peatland reservoirs.

How to cite: Moody, C., Bell, N., Mackay, L., and Kitson, E.: Temporal and spatial changes in DOM revealed by FT-ICR MS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5586, https://doi.org/10.5194/egusphere-egu24-5586, 2024.

EGU24-6501 | Orals | BG1.10

Variations in binding properties of dissolved organic matter along river-ocean continuum 

Pablo Lodeiro, Joao C. A. Macedo, Calin David, Carlos Rey-Castro, Jaume Puy, María Martínez-Cabanas, Roberto Herrero, Manuel E. Sastre de Vicente, and José L. Barriada

The binding properties of dissolved organic matter (DOM) play a crucial role in the biogeochemical cycles of trace metals and carbon. The composition of DOM is anticipated to exert influence over the magnitude and distribution of the intrinsic ion binding affinities that occur over a continuum of values, referred to as the affinity spectra. These spectra encompass many different organic acid groups that contribute to the nuanced binding characteristics of DOM. The total proton binding capacity represents the maximum sites available for other chemical species that may compete with protons for the same DOM binding sites, particularly in the case of metals. Consequently, the study of proton binding by DOM becomes the initial step to investigate deeper into metal binding mechanisms. Here, we research the variability in proton binding exhibited by DOM extracted from the Ebro and Mero Rivers (NNE and NW of Spain), and at the Atlantic Ocean and Mediterranean Sea. Our approach combines the non-ideal competitive adsorption (NICA) isotherm, offering insights into chemical binding on heterogeneous ligands, with the Donnan electrostatic model, which accounts for polyelectrolytic effects, i.e., the non-specific binding. This methodology enables us to pinpoint potential shifts in DOM binding affinities and derive a comprehensive set of intrinsic binding parameters for DOM. Importantly, these parameters are thermodynamically consistent and remain independent of the specific conditions of the samples, enhancing the extrapolation to future environmental changes.

 

Acknowledgements: Authors thank Agencia Española de Investigación for the financial support through the research projects PID2020-117910GB-C21 and -C22/AEI/10.13039/501100011033. P.L. acknowledges current support from the Ministerio de Ciencia, Innovación y Universidades of Spain and University of Lleida (Beatriz Galindo Senior award number BG20/00104)

References:

[1] Lodeiro, P., Rey-Castro, C., David, C., Humphreys, M. H., Gledhill, M., 2023. Proton Binding Characteristics of Dissolved Organic Matter Extracted from the North Atlantic. Environmental Science & Technology 57, 21136–21144.

[2] Waska, H., Brumsack, H.-J., Massmann, G., Koschinsky, A., Schnetger, B., Simon, H., Dittmar, T., 2019. Inorganic and organic iron and copper species of the subterranean estuary: Origins and fate. Geochimica et Cosmochimica Acta 259, 211–232.

[3] Heerah, K. M.,  Reade, H. E., 2023. Towards the identification of humic ligands associated with iron transport through a salinity gradient. Scientific Reports 12:15545.

How to cite: Lodeiro, P., Macedo, J. C. A., David, C., Rey-Castro, C., Puy, J., Martínez-Cabanas, M., Herrero, R., Sastre de Vicente, M. E., and Barriada, J. L.: Variations in binding properties of dissolved organic matter along river-ocean continuum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6501, https://doi.org/10.5194/egusphere-egu24-6501, 2024.

EGU24-6516 | ECS | Posters on site | BG1.10

Spatio-temporal dimensions of organic carbon-mineral interactions in a source-to-sink system 

Nora Gallarotti, Bernhard Peucker-Ehrenbrink, Sophia Johannessen, Lisa Bröder, Reto Wijker, Britta Voss, Negar Haghipour, and Timothy Eglinton

Rivers play a key role in the global carbon cycle by transferring organic carbon (OC) from the terrestrial biosphere to marine sediments, which act as an important long-term carbon sink. Associations between biospheric OC and mineral phases can alter OC stability and hydrodynamic properties, thereby influencing its transport and storage patterns within a river basin and dictating the fate of terrestrial biospheric OC discharged to the ocean. While research has mainly investigated the formation of these associations within soils, open questions remain on how these interactions evolve over space and time.

The Fraser River Basin in British Columbia, Canada drains regions with distinctive lithological and climatic gradients allowing the simultaneous study of leaf-wax-specific isotopic compositions (δ2H, δ13C) and inorganic geochemical signatures (εNd) of sediments as tracers of the provenance of biospheric OC and detrital mineral phases, respectively. In addition, bulk radiocarbon (D14C) serves as a tool to constrain biospheric OC residence times. Here, to investigate seasonal variations in the geochemical signatures of OC and its mineral host in sediments exported by the Fraser River to the Strait of Georgia using samples from a time-series sediment trap deployed cover the course of a year adjacent to the river mouth.

Both εNd and D14C follow a seasonal pattern by which aged OC (-176 to -140‰) is mostly transported during high discharge events such as the freshet in June and heavy rainstorms occurring in the upper basin in fall. During the former event, the geochemical signature (εNd: -9.2 to -7.2) points towards the Coastal Range affecting the detrital mineral composition more strongly, which shifts towards a greater proportion of Rocky Mountains-sourced sediment (εNd: -11.7 to -9.1) during the second high discharge event. Biomarker specific δ2H will further elucidate the extent to which the provenance of biospheric OC coincides with the mineral detrital load. Further, comparison with geochemical signatures of fluvial sediments within the Fraser basin, together with corresponding signatures in river-proximal sediments deposited in the Strait of Georgia allow for OC-mineral interactions to be assessed from a source-to-sink perspective.

This coupled investigation of organic and inorganic tracers provides new insights into terrestrial organic carbon export and the role of organo-mineral interactions on riverine organic carbon dynamics. These findings also have important ramifications for the interpretation of sedimentary archives.

How to cite: Gallarotti, N., Peucker-Ehrenbrink, B., Johannessen, S., Bröder, L., Wijker, R., Voss, B., Haghipour, N., and Eglinton, T.: Spatio-temporal dimensions of organic carbon-mineral interactions in a source-to-sink system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6516, https://doi.org/10.5194/egusphere-egu24-6516, 2024.

EGU24-6629 | ECS | Orals | BG1.10

Different dissolved organic matter (DOM) sources sustain microbial life in beach subterranean estuary 

Grace Abarike, Simone Brick, Bert Engelen, and Jutta Niggemann

Dissolved organic matter (DOM) is diverse in composition and serves as substrate for microbial metabolism. Within subterranean estuaries (STEs), DOM is introduced from different sources along the groundwater flow paths. These different DOM sources make it challenging to disentangle degradation pathways, especially in high-energy beaches with dynamic porewater advection and changing redox conditions. We performed sediment incubations in flow-through reactors (FTRs) to investigate how DOM from different sources is transformed by STE microbial communities. We used sediment and groundwater from the STE of a high-energy beach on Spiekeroog Island (Germany). Intertidal beach sediments were incubated for 13 days in FTRs with groundwater of low (~1.6) and high salinity (~29.1) as marine and terrestrial endmember, respectively, in triplicate setups, and additional control FTRs with artificial seawater of respective salinities. The FTRs ran under oxic conditions with recirculating advective flow. Porewater samples were taken daily for quantification of dissolved organic carbon (DOC) and nutrient concentrations, and samples from the start and the end of the incubation were taken for the analysis of microbial community composition, microbial cell numbers, and DOM composition. DOM samples were isolated through solid phase extraction and molecularly characterized via ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry. Over the course of the incubation, DOC concentrations increased, presumably from sediment leaching and potentially also by primary production in light-exposed parts of the setup, as oxygen concentrations also increased. The DOM composition of the porewater samples at start and end of the incubation was highly diverse, with a total of up to 2900 different molecular formulae detected in each sample. As expected, the low salinity porewater had a more terrestrial DOM signature with a higher proportion of aromatic compounds compared to the DOM in the high salinity porewater. In all setups, the DOM composition changed significantly from start to end. We observed an increase in DOM lability in both endmember setups indicating the mobilization of fresh DOM from sediments and/or microbial activity, including primary production. Interestingly, the changes observed were similar for both DOM endmembers. Our results indicate that the microbial communities of the high-energy beach STE thrive on a similar fraction of DOM, independent of its source.

How to cite: Abarike, G., Brick, S., Engelen, B., and Niggemann, J.: Different dissolved organic matter (DOM) sources sustain microbial life in beach subterranean estuary, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6629, https://doi.org/10.5194/egusphere-egu24-6629, 2024.

EGU24-7088 | ECS | Posters on site | BG1.10

Using a novel N-15 natural abundance approach to quantify soil nitrogen transformations in biochar-treated vineyard soils. 

Kate Kingston, Zhihong Xu, Chris Pratt, Brendan Mackey, Paul Petrie, and Yihan Li

The increased frequency and intensity of climate extremes challenges vineyards to adapt and mitigate to ensure the survival of grape vines (Vitis vinifera) to meet the growing demand for quality wine.  Regenerative Viticulture (RV) is a novel approach with a strong focus on increasing soil carbon (C) stocks to regenerate vineyard soil that is largely degraded and in poor health.  When soil health and fertility is low, this impacts vine health and reduces its ability to fight disease and pests and withstand extreme climatic events. We hypothesised that biochar would increase nitrogen (N) cycling and retention and that these would differ in relation to the distinct physiochemical properties of the two vineyard soils.   Conscious of contributing to a sustainable circular economy, we utilised viticulture industry waste to produce biochar’s to compare with standard pine biochar.  Biochar was produced with three feedstocks at different pyrolysis temperatures, grape marc (475°C), vine pruning (450°C) and pine (600°C).  Soil (0 - 10 cm depth) was collected from under vines from vineyards at the South Burnett (heavy texture) and Granite Belt (sandy texture) regions in Queensland, Australia. We used a novel 15N natural abundance approach in a laboratory incubation experiment to investigate the potential of using biochar, a C-dense material produced by high temperature pyrolysis of organic materials in limited oxygen conditions as a suitable climate smart RV method for vineyard soils.  A short three-day laboratory incubation followed by microdiffusion was conducted to quantify the impacts of the three biochars on N transformations in the two soils.  Soil moisture was controlled at 60% and 90% water holding capacity (WHC) and biochar applied at 0% and 10% (w/w), with samples harvested on incubation days 0 and 3. Preliminary results indicate that in the short term for both experimental soils, biochar stimulated microbial activity, increased N availability and water use efficiency and reduced N loss through denitrification.  The results indicate that fungicides use in vineyards impacted the underlying soil health and microbial communities and influencing N cycling.  For the long term impact, the potential to use biochar for increase biodiversity and ecosystem recovery as a climate smart RV method in vineyards needs to be trialled in the field.  This is to establish the long-term effects of C accumulation and improved N cycling on soil health, biodiversity, vine resilience under extreme natural weather events, and on wine grape quality and quantity.

How to cite: Kingston, K., Xu, Z., Pratt, C., Mackey, B., Petrie, P., and Li, Y.: Using a novel N-15 natural abundance approach to quantify soil nitrogen transformations in biochar-treated vineyard soils., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7088, https://doi.org/10.5194/egusphere-egu24-7088, 2024.

EGU24-7317 | ECS | Orals | BG1.10

Reactivity of hydrogen sulfide toward organic compounds with sulfur-sulfur bonds 

Irina Zweig and Alexey Kamyshny

The presence of organic molecules containing sulfur-sulfur bonds was identified in both water columns and sediments of natural aquatic systems. While processes leading to formation of these compounds were intensively studied during recent decades, the kinetics and mechanisms of reactions responsible for their decomposition remain poorly understood. This study focuses on the kinetics and products of the reactions of dimethyl disulfide, dimethyl trisulfide, and cyclic polysulfide lenthionine (1,2,3,5,6-pentathiepane) with hydrogen sulfide at the pH and temperature ranges typical of environmental conditions. The findings reveal that under environmental conditions (pH≥5), the overall reaction rates are primarily controlled by the reaction of bisulfide anion (HS-) rather than hydrogen sulfide. The activation energy and the order of the reaction with respect to bisulfide anion is dimethyl disulfide < dimethyl trisulfide < lenthionine, while the order of the reaction with respect to organosulfur compounds is lenthionine < dimethyl trisulfide < dimethyl disulfide. The rates of the reactions between linear dimethyl polysulfides with bisulfide anion were found to be higher than the rates of their reactions with cyanide and hydroxyl anions, but lower than the rates of their photodecomposition. These results suggest that rapid decomposition of organosulfur compounds in sulfidic aphotic natural aquatic systems should be controlled by HS- decomposition pathway. Products of the decomposition of dimethyl disulfide and dimethyl trisulfide include methanethiol, higher dimethyl polysulfides, and inorganic polysulfides. The cyclic polysulfides were shown to be more stable than their linear analogs, resulting in their preferential preservation during the maturation process.

How to cite: Zweig, I. and Kamyshny, A.: Reactivity of hydrogen sulfide toward organic compounds with sulfur-sulfur bonds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7317, https://doi.org/10.5194/egusphere-egu24-7317, 2024.

EGU24-7593 | Posters on site | BG1.10

Towards an online ramped oxidation approach for thermal dissection and serial radiocarbon measurement of complex organic matter 

Marco A. Bolandini, Daniele De Maria, Negar Haghipour, Lukas Wacker, Jordon D. Hemingway, Timothy I. Eglinton, and Lisa Bröder

Radiocarbon (14C) measurements provide a powerful tool to deconvolute sources and dynamics of organic matter in the environment. However, interpretation of conventional bulk-level 14C data is challenging due to the myriad components comprising organic matter in soils and sediments. Thermally ramped oxidation provides one approach for overcoming this limitation, and involves subjecting a sample to gradually increasing temperatures, serially oxidizing the OC to CO2. Collected over prescribed temperature ranges ('thermal fractions'), this CO2 is then analyzed for 14C content using accelerator mass spectrometry (AMS). While effective, current ramped oxidation methods are mostly 'offline', involving manual collection and subsequent AMS analysis of evolved CO2, hindering sample throughput and reproducibility.

Here, we introduce a compact, online ramped oxidation (ORO) setup in which CO2 from discrete thermal fractions is directly collected and measured for 14C by AMS equipped with a gas ion source. The setup comprises two modules: (i) an ORO unit with two sequential furnaces - the first, ramped from room temperature to 900 °C, holds the sample; the second, maintained at 900 °C, includes a catalyst ensuring complete oxidation to CO2; and (ii) a dual-trap interface (DTI) collection unit with two parallel molecular sieve traps alternately collecting and releasing CO2 from a given fraction for direct injection into the AMS.

Preliminary results indicate reproducible data, evident in both thermograms and F14C results. Analysis of natural reference samples reveals that measured 14C values and their associated uncertainties align with those reported in the literature using conventional “off-line” ramped oxidation methods, affirming the utility of the new ORO-DTI-AMS setup.

Our goal is to apply this new method for comprehensive investigation of a range of natural samples, with a particular focus on the improved understanding of the fate of OC held in permafrost soils in the context of on-going climate and carbon cycle change in high latitude ecosystems.

How to cite: Bolandini, M. A., De Maria, D., Haghipour, N., Wacker, L., Hemingway, J. D., Eglinton, T. I., and Bröder, L.: Towards an online ramped oxidation approach for thermal dissection and serial radiocarbon measurement of complex organic matter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7593, https://doi.org/10.5194/egusphere-egu24-7593, 2024.

Subterranean estuaries underlying high-energy beaches are efficient turnover sites for dissolved organic matter (DOM) and nutrients from marine and terrestrial waters. In addition, leaching of beach wrack during tidal inundation and precipitation can contribute to DOM and nutrient loads. However, the combined impact of diverse environmental settings on the release of DOM and nutrients from beach wrack has so far not been studied, although e.g., salinity oscillations and temporary exposure to sunlight are common in high-energy beach subterranean estuaries. Here, we present the results of an extensive beach wrack leaching experiment taking beach wrack type, age, sunlight exposure, and leaching matrix into consideration. A combination of UVA irradiation, advanced wrack age, and leaching by low-salinity artificial rainwater resulted in high dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) releases of mmoles- to moles per kg dry weight in the macroalga Fucus sp. Furthermore, jellyfish wrack released millimoles of TDN in artificial seawater incubations. Ultra-high-resolution analyses of DOM revealed a prevalence of molecular formulae resembling biochemical building blocks such as sugars, amino acids, and vitamins, indicating that the released DOM could be of substantial nutritional value for the heterotrophic microbial communities on and near beach wrack. An interesting finding was the high abundance of aromatic and humic-like DOM released from macroalgal beach wrack, which may impact typically used marine and terrestrial source- and sink proxies. As such, beach wrack DOM and nutrients could further complicate biogeochemical distribution patterns in the subterranean estuary.

How to cite: Waska, H. and Banko-Kubis, H.: Experimental comparison of dissolved organic matter and nutrients leached from beach wrack by sea- and rainwater: A nutritional boost for the sandy beach subterranean estuary, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8750, https://doi.org/10.5194/egusphere-egu24-8750, 2024.

EGU24-10047 | Orals | BG1.10

Carbonate-associated organic matter: A form of “dissolvable” organic matter? 

Mary Zeller, Bryce Van Dam, Amy McKenna, Christian Lopes, Christopher Osburn, James Fourqurean, Kominoski John, and Michael Böttcher

Carbonate-associated organic matter (CAOM) is the organic matter associated with carbonate minerals, and a survey of carbonate-rich surface sediments suggests that it is incorporated at a consistent amount scaling with the internal surface area of the carbonate grains. As the carbonate sediment is sensitive to changes in saturation state due to benthic biogeochemical processing, we predicted that CAOM could exhibit interesting biogeochemical cycling, based on its potential to bridge particulate and dissolved pools of organic matter. Here, we report on a study in a seagrass meadow in central Florida Bay, USA. We utilize a combination of inorganic stable isotope (C, S, O) and high resolution mass spectrometry (21T FT ICR-MS) techniques to explore the carbon and sulfur cycles here, with a particular emphasis on dissolved organic matter (DOM) characterization. CAOM is examined similar to standard solid phase extraction (SPE-DOM) methods, after first washing carbonate sediment and dissolving it incompletely under a mild hydrochloric acid treatment. The δ34S and δ18O of sulfate, as well as the δ13C of dissolved inorganic carbon (DIC), suggest that the promotion of sulfide oxidation in the seagrass rhizosphere drives rapid carbonate dissolution and re-precipitation cycles. Sulfide oxidation, as well as elevated sulfide concentration, promotes sulfurization of CAOM, which is more sulfurized than porewater and surface water, as 42% of CAOM formulas vs 28% of surface water are sulfurized. Furthermore, a substantial quantity of molecular formulas present in the overlaying surface waters (90% of formulas, 97% by relative abundance) are also present in CAOM. Despite the CAOM sample containing nearly twice the number of formulas compared to surface water, due in part to its higher dissolved organic carbon concentration, these shared formulas make up 75% of the abundance of CAOM formulas. We argue that repeated coupled sulfur and inorganic carbon cycles, intensified by seagrasses, leads to increased sulfurization and release of CAOM, affecting DOM quality in the broader aquatic system. We estimate that approximately 9% of the particulate organic carbon (POC) stored in the sediments of this site are CAOM. Our results suggest that CAOM here is a form of “dissolvable” organic carbon which cycles much more rapidly than POC more broadly.

How to cite: Zeller, M., Van Dam, B., McKenna, A., Lopes, C., Osburn, C., Fourqurean, J., John, K., and Böttcher, M.: Carbonate-associated organic matter: A form of “dissolvable” organic matter?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10047, https://doi.org/10.5194/egusphere-egu24-10047, 2024.

EGU24-10209 | ECS | Posters on site | BG1.10

Apparent Aging and Rejuvenation of Terrestrial Organic Carbon Along the River-Estuary-Coastal Ocean Continuum 

Meng Yu, Timothy Eglinton, Pengfei Hou, Negar Haghipour, Hailong Zhang, Zicheng Wang, and Meixun Zhao

The balance between remineralization and sedimentary burial of terrestrial organic carbon (OCterr) in large river-dominated marginal seas influences atmospheric CO2 inventory on a range of timescales. Here we systematically investigate the evolution of OCterr along the river-estuary-coastal ocean continuum for three fluvial systems discharging to the Chinese marginal seas. The 14C-depleted characteristics of bulk OC and molecular components of riverine suspended sediments and marine sediments suggest that the Chinese marginal seas are a significant sink of pre-aged OCterr. Lower plant-wax fatty acid 14C contents suggest selective degradation of labile OC within estuaries, resulting in apparent aging of OCterr, followed by an apparent rejuvenation in OCterr in shelf sediments, the latter likely reflecting inputs from proximal sources that contribute younger OCterr. This selective degradation, aging and rejuvenation of OCterr along the continuum confounds the use of plant wax lipid 14C to constrain lateral transport times, and sheds light on more complex OCterr dynamics in marginal seas.

How to cite: Yu, M., Eglinton, T., Hou, P., Haghipour, N., Zhang, H., Wang, Z., and Zhao, M.: Apparent Aging and Rejuvenation of Terrestrial Organic Carbon Along the River-Estuary-Coastal Ocean Continuum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10209, https://doi.org/10.5194/egusphere-egu24-10209, 2024.

EGU24-11112 | ECS | Orals | BG1.10

Exploring CO2 Cycling in Karst Critical Zones: Lessons from Milandre Cave 

Sarah Rowan, Marc Leutscher, Sönke Szidat, and Franziska Lechleitner

We know that the concentrations of CO2 and DIC in the subsurface are often magnitudes higher than in the soil zone, and therefore we need to understand this reservoir and its vulnerability to change. Understanding the critical zone in the context of CO2 input, cycling dynamics, and export is essential as this carbon is particularly vulnerable to changes in water table rise which may result in rapid release of CO2 into the atmosphere. Cave environments provide an accessible natural window into the critical zone as they connect meteoric water, soils, the unsaturated vadose zone, and saturated zone. We conducted a two year monitoring campaign at Milandre cave in northern Switzerland, analyzing pCO2, d13CO2, and 14CO2 at various environmental interfaces, including the soil zone, within the epikarst, and in the cave itself. Forest soils maintained stable, modern 14C signatures and low d13C indicating year-round contribution of CO2 from C3 tree and plant root respiration. Conversely, meadow soils exhibited notable seasonality in F14C, suggesting a dominance of respiration from older soil pools in the winter months. Distinct variations in CO2 concentrations were observed within the cave, influenced by temperature driven ventilation dynamics. Keeling plot analysis revealed a consistent contributing endmember of C3 vegetation. However, similarities between the F14C of the meadow soils and cave CO2 suggests a significant contribution of meadow soil CO2 into the cave. These findings offer vital insights into the nuanced dynamics of CO2 sources and cycling processes within the critical zone of Milandre Cave, shedding light on the influences of seasonal variation and ecological influences of critical zone carbon and the export of carbon from terrestrial ecosystems.

How to cite: Rowan, S., Leutscher, M., Szidat, S., and Lechleitner, F.: Exploring CO2 Cycling in Karst Critical Zones: Lessons from Milandre Cave, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11112, https://doi.org/10.5194/egusphere-egu24-11112, 2024.

EGU24-11285 | Orals | BG1.10

Global expression of bomb radiocarbon in Earth's surface carbon reservoirs 

Timothy Eglinton and the Bomb-spike team

The Earth’s carbon cycle encompasses myriad processes that connect different reservoirs containing diverse forms of carbon that turnover and exchange on a wide range of spatial and temporal scales. Increased atmospheric CO2 from anthropogenic perturbation of the carbon cycle associated with fossil fuel combustion and land-use change reflects the release of carbon from stable, slow-cycling reservoirs.  Much current research seeks to quantify carbon transfer from slow to fast cycling reservoirs, as well as the ability of different carbon reservoirs, particularly the terrestrial biosphere and the oceans, to compensate for these increased CO2 emissions through carbon uptake and storage. Determination of the turnover time and rate of transfer of carbon between reservoirs is crucial in this regard. Radiocarbon, 14C, represents a powerful tool to address this question by virtue of its ~ 5700-year half-life that allows processes occurring on centennial to millennial timescales to be resolved. Superimposed on natural abundance 14C variations, above-ground nuclear weapons testing during the mid-20th Century created an abrupt spike in atmospheric radiocarbon (“bomb spike”) that has subsequently permeated into and moved through various Earth surface carbon reservoirs, serving as a useful tracer of carbon cycle processes occurring on annual to decadal timescales. Numerous studies have exploited this signal for assessment of turnover or transit times within and through carbon pools, atmospheric and oceanic circulation, ecosystem functioning and source attribution. However, much 14C data currently tends to be compartmentalized, with a focus on specific reservoirs or geographic locations.

In this study, we evaluate the global expression of the radiocarbon bomb spike across the different Earth surface active carbon reservoirs (terrestrial biosphere, soils, freshwater aquatic systems, and marine carbon reservoirs). We compile 14C data from existing and nascent databases as well as new measurements, including direct observations and records from natural archives spanning the pre-bomb period to the present, to develop an overview of the general features of 14C (timing, amplitude and character of the bomb peak) within each reservoir over this time interval.  In addition to using this information to refine our understanding of the interactions between different reservoirs, this study seeks to (i) identify gaps and biases in data with a view to motivating further 14C studies, (ii) underline the value of systematic data reporting, as well as careful archiving of samples for future 14C analysis, (iii) inform isotope-enabled carbon cycle and earth system models, and (iv) serve as benchmark against which to gauge future carbon cycle changes.

How to cite: Eglinton, T. and the Bomb-spike team: Global expression of bomb radiocarbon in Earth's surface carbon reservoirs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11285, https://doi.org/10.5194/egusphere-egu24-11285, 2024.

EGU24-11446 | ECS | Orals | BG1.10

Pyrogenic Carbon production in eucalypt forests: implications for the carbon cycle in fire-prone ecosystems 

Minerva García-Carmona, Cristina Santín, and Stefan Doerr

Wildfires play an important role in the carbon cycle, influencing both atmospheric carbon concentrations and terrestrial carbon storage. Pyrogenic carbon (PyC) derived from incomplete biomass combustion during wildfires is currently considered a relevant carbon sink at the global level. In order to assess the quantitative importance of PyC production, accurate data on PyC generation in different ecosystems and under a range of fire conditions are needed. In this study, we focus on the fire-prone continent of Australia, specifically on eucalypt forests, which are the most common type of native forests. Eucalypt forests, subjected frequently to both wildfires and human-prescribed fires, provide an important context for understanding PyC dynamics.
We conducted comprehensive pre-fire and postfire fuel inventories and quantified all pyrogenic materials generated in three representative eucalypt forests in Sydney, Melbourne, and Perth. Experimental fires, simulating low to medium-severity wildfires, were used to quantify PyC conversion rates in the main fuel components: forest floor, understory, down wood, and overstory (comprising only tree bark as these fires did not affect the crowns).
Our results show an average pyrogenic carbon conversion rate of 24% for eucalypt forests. This translates to 9 t C ha-1 of the carbon affected by the fire being emitted to the atmosphere, while 3 t C ha-1 is transformed into PyC, underscoring the relevance of PyC in carbon budgets from eucalypt forest fires. The conversion rates varied substantially among fuel components, with the bark component exhibiting the highest conversion rate, at approximately 40%, and the down wood component displaying the lowest rate at around 15%. Intermediate conversion values were reported for forest floor and understory components. 
Given the recurrent nature of fires in eucalypt forests in Australia, both naturally and under human-prescribed conditions, our findings suggest that PyC production plays a significant role in the carbon cycle, of sufficient magnitude to be considered in global carbon budget estimations.

How to cite: García-Carmona, M., Santín, C., and Doerr, S.: Pyrogenic Carbon production in eucalypt forests: implications for the carbon cycle in fire-prone ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11446, https://doi.org/10.5194/egusphere-egu24-11446, 2024.

EGU24-11885 | Orals | BG1.10

Radiocarbon measurements of archived fish scales reconstruct past carbon cycle changes in a peri-alpine lake 

Margot White, Benedict Mittelbach, Timo Rhyner, Negar Haghipour, Thomas Blattmann, Martin Wessels, Nathalie Dubois, and Timothy Eglinton

Climate change and other anthropogenic impacts such as nutrient pollution result in perturbations to freshwater systems that alter aquatic carbon cycling. In the alpine Rhine basin, for example, long-term monitoring over the past four decades has documented increasing water temperatures that cause a decrease in the solubility of CO2. However, this same dataset records a small increase in the concentration of dissolved inorganic carbon (DIC) over the same period. This requires increasing inputs of DIC to aquatic systems and an acceleration of the carbon cycle, but the source of this additional carbon is not clear. Possible explanations include increased weathering of bedrock or increased soil organic matter respiration, with sharply contrasting implications for carbon storage and turnover. Radiocarbon (14C) is an ideal tool to distinguish between these different scenarios, as bedrock weathering will contribute 14C-depleted (fossil) DIC whereas increased soil respiration will contribute DIC that is more 14C-enriched (younger). Furthermore, large changes in the atmospheric radiocarbon content over the past century resulting from the testing of nuclear weapons provide a strong signal with which to track the exchange between aquatic and atmospheric carbon pools by examining how lake water DI14C changes through time. Here we focus on Lake Constance, a large peri-alpine lake fed mostly by the alpine Rhine River. We measured natural abundance radiocarbon in archived fish scales collected from Lake Constance over the past 100 years to reconstruct changes in lake water DI14C. These fish scales come from young fish caught in the lake who feed primarily on phytoplankton and thus reflect the 14C of the lake DIC pool. Preliminary measurements of fish scales from the pre-bomb period were 0.78 to 0.79 Fm, reflecting the addition of 14C dead rock-derived carbon from the dissolution of carbonate rocks within the catchment. These values are 14C-depleted compared to present day water column DIC values of 0.82 to 0.84 Fm, where the bomb spike signal persists. Results from fish scales will ultimately be compared with other archives of water column DI14C currently in development, including 14C of chlorophyll degradation products and zooplankton exoskeletons isolated from varved lake sediments. These records permit us to investigate how carbon cycling in the lake and its catchment has responded to anthropogenic perturbations such as warming and nutrient pollution over the past century, with the eventual goal of calibrating isotope enabled carbon cycle models.

How to cite: White, M., Mittelbach, B., Rhyner, T., Haghipour, N., Blattmann, T., Wessels, M., Dubois, N., and Eglinton, T.: Radiocarbon measurements of archived fish scales reconstruct past carbon cycle changes in a peri-alpine lake, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11885, https://doi.org/10.5194/egusphere-egu24-11885, 2024.

EGU24-11886 | Posters on site | BG1.10

Direct radiocarbon measurements of dissolved inorganic carbon from environmental water using a gas ion source  

Negar Haghipour, Charlotte Schnepper, Thomas Blattmann, Kayley Kundig, Maxi Castrillejo, Nuria Casacuberta, Timothy I. Eglinton, and Margot E. White

An increasing demand for radiocarbon analysis of small samples has led to the development of various methods to further improve and simplify the CO2 extraction needed for accelerator mass spectrometer (AMS) measurements. Here, the performance of a direct feeding system of CO2 from dissolved inorganic carbon (DIC) from small water samples (<6 ml) and direct AMS measurement via a gas ion source coupled to a gas interface system (GIS) is presented and compared to the conventional preparation by graphitization that demands significantly larger samples (> 60 ml).

Seawater samples collected from Sargasso Sea, southeast of and lake water samples collected from Lake Constance have been prepared by both methods. The extraction of CO2 gas from samples for GIS measurement is performed using a carbonate handling system (CHS-Ionplus AG) through purging the headspace, acidifying the water, and sparging out the CO2. The preparation time is greatly reduced compared to conventional analysis that requires the labor-intensive graphitization step. The yielded 14C results from the direct CO2 measurements are in good agreement with values obtained from graphite measurements. The observed deviation between the two methods is below the uncertainty of radiocarbon gas measurement (~7‰).

This new approach will facilitate understanding of carbon cycle dynamics in many different environments and applications where a high throughput (up to 80 sample/day) is required. The new method is suitable for groundwater, pore water, seawater, freshwaters from lakes, rivers and glacial settings. Furthermore, it enables the analysis of small milliliter-scale samples and those containing low DIC concentrations.

How to cite: Haghipour, N., Schnepper, C., Blattmann, T., Kundig, K., Castrillejo, M., Casacuberta, N., Eglinton, T. I., and White, M. E.: Direct radiocarbon measurements of dissolved inorganic carbon from environmental water using a gas ion source , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11886, https://doi.org/10.5194/egusphere-egu24-11886, 2024.

EGU24-12192 | Posters on site | BG1.10

There to remain? Pyrogenic carbon production of savanna fires 

Cristina Santin, Carmen Sánchez-García, Minerva García-Carmona, Tercia Strydom, Philippa Ascough, and Stefan H. Doerr

Southern African savanna fires account for ~30% of the annual global carbon (C) emissions from vegetation fires, but their impact on the global C cycle extends beyond direct emissions During fire, part of the C burnt is converted to pyrogenic carbon (PyC), which is more resistant to degradation than original biomass and acts as a buffer to global fire C emissions when stored in soils or sediments. Despite its recognized importance for the C cycle, how much PyC is produced and how much of it stays in savanna ecosystems is still not well known, with no information yet for Southern African savannas. To address this research gap, we quantified how much PyC was produced during four fires in Kruger National Park (South Africa) and how much PyC was stored in surface soils. We also characterized the chemical and thermal recalcitrance of this PyC. Our results will be discussed in the broader context of C emissions from savanna fires as well as the role PyC plays as a C sequestration mechanism through its accumulation in soils, redistribution and ex-situ transport.

How to cite: Santin, C., Sánchez-García, C., García-Carmona, M., Strydom, T., Ascough, P., and Doerr, S. H.: There to remain? Pyrogenic carbon production of savanna fires, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12192, https://doi.org/10.5194/egusphere-egu24-12192, 2024.

EGU24-12381 | ECS | Posters on site | BG1.10

Assessing the biodegradability of dissolved organic carbon in freshwater systems: A method evaluation study 

Danielle Green, Fereidoun Rezanezhad, Scott Smith, Stephanie Slowinski, and Philippe Van Cappellen

Dissolved organic carbon (DOC) is an important contributor to both carbon cycling and other biogeochemical processes in aquatic ecosystems. The biodegradable fraction of DOC can be microbially degraded over time, producing carbon dioxide (CO2), a greenhouse gas. In addition, microbial degradation-resistant DOC can accumulate in water bodies, causing chemical and physical changes to aquatic systems. Although biodegradable DOC (BDOC) is widely studied, there is no agreed-upon standard method for assessing its biodegradability. Here, we aimed to develop and evaluate a new method for determining BDOC in freshwater samples. Our method includes filtering water samples to below 0.22 µm, to remove existing microbial cells, prior to inoculating the samples with a concentrated microbial inoculum produced by stepwise isolation of microbial cells from a peat sample. In addition, we added solutions containing nitrogen and phosphorus (in the forms of NH4NO3 and K2HPO4, respectively) to ensure that the microbes were not nutrient-limited. The samples were then capped with foam stoppers and incubated in the dark at 25⁰C on a shaker for 28 days to allow constant aeration during BDOC degradation. When applied to five freshwater samples collected from rivers, stormwater ponds, and a lake, and a glucose control, we observed that the amount of BDOC in the natural samples ranged from 15% to 53% and was 90% in the glucose control. Rates of BDOC degradation were calculated from DOC measurements at six sampling time points between days 0 and 28. We found that the DOC trends with time were best explained by two successive phases for BDOC degradation in all of the samples: an initial, fast, phase of BDOC degradation followed by a second, slower, phase of BDOC degradation where the rate constant for the second phase was between 5.57 and 565 times slower than for the initial phase. Changes in chemical characteristics of DOC measured using absorbance and fluorescence parameters including specific ultraviolet absorbance at 254 nm (SUVA254), humification index (HIX), and parallel factor analysis (PARAFAC) at each sampling time revealed that the initial, fast, phase of BDOC degradation often represents the utilization of small, non-aromatic compounds while the later, slower, phase of BDOC degradation often represents the utilization of more complex, aromatic compounds. The presented method provides a new approach to measure and characterize BDOC degradability and degradation kinetics that can be applied to future studies on biogeochemical processes in aquatic ecosystems.

How to cite: Green, D., Rezanezhad, F., Smith, S., Slowinski, S., and Van Cappellen, P.: Assessing the biodegradability of dissolved organic carbon in freshwater systems: A method evaluation study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12381, https://doi.org/10.5194/egusphere-egu24-12381, 2024.

EGU24-12504 | ECS | Posters on site | BG1.10

Burning poop: carbon dynamics in herbivore dung during southern-African savanna fires 

Carmen Sánchez-García, Cristina Santín, Tercia Strydom, and Stefan Doerr

Herbivores play a vital role in the functioning of savanna ecosystems. They ingest plants, modifying the vegetation cover, and disperse nutrients across the landscape in the form of dung. Fire in savanna is also a key nutrient recycling pathway, making elements readily available through the resultant ash and smoke. Wildfire ash, known for its susceptibility to be transported by wind and water, plays a key role in redistributing pyrogenic organic matter and nutrients across the landscape. However, our level of understanding of ash characteristics from burnt dung is very low. In addition, and due to its high carbon content, dung also adds to the wildland fuels for fires, alongside vegetation. Given that savannas are the dominant source of global Cemissions from fires, assessing the role of burnt dung in C dynamics is, therefore, also crucial for more accurate estimations of the overall C released during savanna fires.

We quantified C losses from dung combustion during fire in four savanna sites burnt by experimental fires in Kruger National Park (South Africa). We also analysed chemical properties, including major nutrients and metals, of dung and dung-derived ash. The studied dung came from large herbivores (zebra, elephant, giraffe, buffalo and wildebeest). The concentration of carbon and nitrogen in burnt dung was significantly lower than unburnt dung (carbon: 41 and 4.1%, nitrogen: 1.1 and 0.3% in unburnt and burnt dung, respectively). The carbon released from dung burning accounted for up to 6% of the carbon released from vegetation burning, emphasizing the substantial role of dung in carbon emissions during savanna fires. Our results also highlight burnt dung as a hotspot for minerals and nutrients with chemical characteristics different to those found in vegetation ash (e.g., phosphorus: 9,195 and 6,158 mg kg-1, copper: 55.8 and 28.1 mg kg-1 in dung-derived and vegetation ash respectively). This is likely to affect local soil physical and chemical properties and hence enhance ecosystem diversity.

How to cite: Sánchez-García, C., Santín, C., Strydom, T., and Doerr, S.: Burning poop: carbon dynamics in herbivore dung during southern-African savanna fires, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12504, https://doi.org/10.5194/egusphere-egu24-12504, 2024.

EGU24-13692 | ECS | Posters on site | BG1.10

Unveiling the role of soil water: Identifying primary sources of dissolved organic matter in surface waters 

Livia Vieira Carlini Charamba, Tobias Houska, Klaus Kaiser, Klaus-Holger Knorr, Stephan Krüger, Tobias Krause, Huan Chen, Pavel Krám, Jakub Hruška, and Karsten Kalbitz

Dissolved organic matter (DOM) is crucial for various ecological processes, playing essential roles in carbon and nutrient cycling. In forested catchments, litter input contributes to soil organic matter, influencing DOM composition in surface waters. The transition of DOM from soil organic matter to the dissolved state significantly impacts ecological balance and highlights the role of specific soil horizons in the catchment for stream water. DOM fingerprints, reflecting variations and similarities, act as valuable indicators for identifying primary DOM sources. The increasing trend in dissolved organic carbon (DOC) concentrations in surface waters underscores the urgency to understand contributing sources comprehensively. This study aims to characterize DOM along the terrestrial-aquatic continuum, identifying sources in stream water.

Soil, soil water, and stream water samples were collected biweekly for approximately two years at various depths in the Sosa drinking water reservoir catchment (Ore Mountains, Saxony, Germany). Two sub-catchments (one with a significant peatland component and one with predominantly mineral soils) were considered, each with two streams. The soil and soil water samples included four different soil types that characterize the entire catchment, i.e., intact and degraded peatland, cambisol, podzol. Pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) was employed to characterize DOM in both solid and aqueous samples. Rstudio was used as a semiautomatic data processing aiming to achieve consistent compound identification. A principal component analysis (PCA) and cluster analysis were used to identify DOM sources in stream water.

PCA results showed a clear distinction between solid and aqueous samples. Overlaps were observed among soil water and stream water samples, revealing shared organic compound sources and potential transfer pathways. Fluctuations and degradation patterns were noted across seasons, especially for soil water samples. Cluster analysis revealed that soil water DOM from peat horizons predominantly influenced upstream stream water DOM in peatland-dominated areas. Downstream, the DOM composition changed and was influenced by soil water from the cambisol and the podzol (mineral soils). Concerning the sub-catchment composed mainly of mineral soils, stream water reflected DOM of deep mineral horizons of cambisols and podzols. Forest floor soil water from cambisol had no to very little effect in both sub-catchments, however, soil water of the podzol forest floor slightly contributed to the streams located in the mineral soil-dominated sub-catchment. Thus, the results show that the primary source of DOM in the Sosa catchment came from soil water of deep mineral soil horizons and that stream proximity was a primary factor influencing the influx of allochthonous DOM into stream water.

The research emphasized that DOM composition in the four streams closely resembled soil water DOM and analyzing the composition of the solid organic soil horizons did not help to identify the potential DOM source of the streams. Therefore, although recognizing intrinsic stream processes is important, successful source identification requires analysis of DOM in soil water from major catchment soil types. Proximity to stream water played a critical role as the predominant factor contributing to the introduction of allochthonous DOM into stream water.

How to cite: Vieira Carlini Charamba, L., Houska, T., Kaiser, K., Knorr, K.-H., Krüger, S., Krause, T., Chen, H., Krám, P., Hruška, J., and Kalbitz, K.: Unveiling the role of soil water: Identifying primary sources of dissolved organic matter in surface waters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13692, https://doi.org/10.5194/egusphere-egu24-13692, 2024.

EGU24-14728 | Orals | BG1.10

Transformations of soil organic matter induced by volatile organic compounds 

Laura Meredith, Juliana Gil Loaiza, Adrian Castro, Antonette DiGuiseppe, Gemma Purser, Zhaoxin Zhang, Qunli Shen, Kolby Jardine, Romy Chakraborty, Eoin Brodie, and Malak Tfaily

Volatile organic compounds (VOCs) are diverse and prevalent metabolites exchanged in microbial systems but are often overlooked as vectors of soil organic matter (SOM) transformations. Roots, litter, aboveground vegetation, and microbial metabolism are all sources of VOCs to soil; however, little is known about how they can contribute to soil carbon (C) cycling. VOCs have been shown to contribute to key soil C pools including microbial biomass, dissolved organic matter, particulate organic matter, and mineral-associated organic matter (MAOM), suggesting that they can participate in critical soil C stabilization pathways such as the microbial necromass conduits to MAOM. Yet, we still lack an understanding of the specific VOC-induced transformations in SOC, hindering the characterization of this process across soil and volatile compounds.

 

To address this research gap, we conducted a soil incubation study to evaluate the contributions of VOCs to SOM composition. We hypothesized that VOCs would impact SOM composition and soil carbon pool magnitudes. We evaluated whether the diversity and quality of soil metabolites change in response to weekly additions of five individual VOCs over a 3-month period: methanol, acetone, acetaldehyde, isoprene, and alpha-pinene. In our study, we utilized soil matrices from a semi-arid agroecosystem, alongside sterile (irradiated) soil controls and silica controls, enabling us to distinguish between biotic and abiotic interactions. We monitored CO2 concentrations regularly as a proxy for microbial activity. Destructive triplicate samples were harvested each month for metabolite extraction and high-resolution SOM analysis by Fourier-transform ion cyclotron resonance mass spectrometry (FTICRMS). We found that VOCs stimulated SOM transformations and generally increased the number of lipids and amino sugars—markers of microbial biomass. VOCs a-pinene, acetaldehyde, and methanol had the most unique compounds, suggesting that these VOCs may support biomass production and its transformation, while isoprene and acetone had no unique compounds and may have predominantly been used for catabolic, CO2-producing processes. With this study, we aim to grow understanding of the role of VOCs in soil C cycling and their contribution to soil ecological and metabolic interactions related to carbon stabilization.

How to cite: Meredith, L., Gil Loaiza, J., Castro, A., DiGuiseppe, A., Purser, G., Zhang, Z., Shen, Q., Jardine, K., Chakraborty, R., Brodie, E., and Tfaily, M.: Transformations of soil organic matter induced by volatile organic compounds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14728, https://doi.org/10.5194/egusphere-egu24-14728, 2024.

EGU24-15386 | ECS | Posters on site | BG1.10

Dissolved Organic Matter from Coastal Vegetated Ecosystems Through the Lens of Carbon Sequestration 

Dariya Baiko, Thorsten Dittmar, Philipp Böning, and Michael Seidel

Coastal vegetated ecosystems (CVEs) are highly productive habitats whose role in coastal biogeochemical cycles cannot be understated. The high productivity of salt marshes, seagrass meadows, and mangrove forests is channeled into the sediments and into the sea in form of particulate and dissolved organic matter (DOM). While labile DOM is degraded within a short time frame, recalcitrant DOM compounds can remain in the oceanic water column for hundreds to thousands of years. However, so far, DOM has received little consideration in carbon sequestration approaches. In sulfidic porewater of CVEs, DOM can undergo abiotic sulfurization, producing dissolved organic sulfur (DOS), which may render it resistant to biodegradation. Thus, the formation of DOS in CVEs can act as a link between labile and recalcitrant pools of DOM and provide the means of carbon transport across and beyond ecosystem boundaries. We analyzed DOM as well as inorganic nutrients in samples from temperate (German) and tropical (Malaysian) mesotidal CVEs. Unprecedentedly high porewater DOC concentrations were found in both temperate salt marshes as well as in tropical mangroves. High proportions of DOS in the DOM pool demonstrated accumulation of sulfurized compounds in the porewater. Molecular DOM patterns deduced from ultrahigh-resolution mass spectrometry (FT-ICR-MS) analysis indicated that up to 50% of the several thousand molecular formulas identified were characteristic of the analyzed CVEs. Adjacent habitats shared a substantial proportion of DOM molecular formulas indicating lateral transfer of organic material. This emphasizes that the potential for carbon dioxide removal of CVEs extends beyond the areas with above-ground biomass.

How to cite: Baiko, D., Dittmar, T., Böning, P., and Seidel, M.: Dissolved Organic Matter from Coastal Vegetated Ecosystems Through the Lens of Carbon Sequestration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15386, https://doi.org/10.5194/egusphere-egu24-15386, 2024.

EGU24-15535 | ECS | Orals | BG1.10

The climate control of soil organic carbon dynamics inferred from speleothem radiocarbon ages 

Gang Xue, Yanjun Cai, Peng Cheng, Franziska Lechleitner, Haiwei Zhang, Yanhong Zheng, Yingying Wei, Shouyi Huang, Ling Yang, Xing Cheng, Yanbin Lu, Jie Zhou, Le Ma, Hai Cheng, and Lawrence Edwards

The complexity of processes affecting soil organic carbon (SOC) turnover on spatio-temporal scales often hinders the extrapolation of results from specific sites to larger scales. This study presents Holocene speleothem U-Th ages paired with 14C ages of carbonate and dissolved organic carbon (DOC) through three caves located on a north-south transect through China. The deviations of speleothem 14CDOCages from the U-Th ages show clearly spatial variability, and they are positively correlated with mean ages of modern SOC and soil turnover time, suggesting that deviations can be used to infer the SOC turnover. We further demonstrate that slow SOC turnover (large deviation) was associated with weak monsoon (low temperature/less precipitation) on temporal scales. Our findings reveal that climate dominates the speleothem 14CDOCages and SOC turnover. As global warming likely will intensify, the accelerated turnover of SOC, particularly at higher latitude areas, may partially offset the existing soil carbon stock. 

How to cite: Xue, G., Cai, Y., Cheng, P., Lechleitner, F., Zhang, H., Zheng, Y., Wei, Y., Huang, S., Yang, L., Cheng, X., Lu, Y., Zhou, J., Ma, L., Cheng, H., and Edwards, L.: The climate control of soil organic carbon dynamics inferred from speleothem radiocarbon ages, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15535, https://doi.org/10.5194/egusphere-egu24-15535, 2024.

EGU24-15782 | ECS | Posters on site | BG1.10

Lambda-Miner: Enhancing Reproducible Natural Organic Matter Data Processing with a Semi-Automatic Web Application  

Johann Wurz, Anika Groß, Kai Franze, and Oliver Lechtenfeld

As the volume and complexity of data in environmental sciences continue to grow, the need for data management and reproducible processing methods becomes increasingly crucial. In the specific research domain of natural organic matter (NOM), there is currently no standardized tool for data processing, particularly for the management of data and its respective metadata. We developed and present the Lambda-Miner - a semi-automatic web application for data processing of ultrahigh-resolution mass spectrometry data of NOM. The platform provides an end-to-end data processing pipeline and supersedes manual steps via standardized data and metadata management. It empowers users to execute interactive workflows for mass spectra calibration, assignment of molecular formulas by specific rules to peak masses, and validation of these formulas according to specific sets of rules. Peak data as well as sample and measurement metadata are stored in a relational database management system (RDBMS). The Lambda-Miner thus facilitates reproducible, standardized data processing which builds a common repository for mass data, metadata (such as sample type and geolocation), intermediate, and final results in a format suitable for subsequent analyses. The combination of this information in one place enables meta-analyses such as long-term quality control studies and software optimization assays. The Lambda-Miner supports domain-specific requirements for research data management and contributes to achieving FAIR data principles in the domain of NOM analytics. The Lambda-Miner allows researchers to process their ultrahigh-resolution mass spectrometry data of NOM within minutes and linking it to features such as extraction efficiency, accumulation time, and relation of total assigned current to total ion current. Processed data can be downloaded in an interoperable format, facilitating individual data processing or visualization. The current implementation of the Lambda-Miner is designed for studying NOM with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) allowing formula assignments with widely used elemental compositions of NOM in the mass range from 0 to 1000 Da. But its modular structure makes it easy to adjust and extend the implementation for other kind of analyses or instrumentations. With its adaptability and focus on reproducibility, the Lambda-Miner introduces a valuable tool for advancing standardized data storage, processing, and analysis in the study of Natural Organic Matter.

How to cite: Wurz, J., Groß, A., Franze, K., and Lechtenfeld, O.: Lambda-Miner: Enhancing Reproducible Natural Organic Matter Data Processing with a Semi-Automatic Web Application , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15782, https://doi.org/10.5194/egusphere-egu24-15782, 2024.

EGU24-16215 | ECS | Orals | BG1.10

Detection and exclusion of false molecular formula assignments via mass error distributions in ultrahigh resolution mass spectra from natural organic matter. 

Shuxian Gao, Elaine Jennings, Limei Han, Boris Koch, Peter Herzsprung, and Oliver Lechtenfeld

Ultrahigh resolution mass spectrometry (UHRMS) routinely detects and identifies thousands of molecular formulas (MFs) in natural organic matter (NOM). However, multiple assignments (MultiAs) occur when the several chemically plausible MFs are assigned to one single mass peak. MultiAs for a mass peak consist of one common core MF but different “formula residuals”, or replacement pairs, and increase as more heteroatoms and isotopes are being considered during the assignment process. This poses a major problem for the reliable interpretation of NOM composition in a biogeochemical context. A number of approaches have been proposed to rule out false assignments based on structural constraints or isotopologue detection and intensity ratios. But this becomes increasingly challenging for low abundance mass peaks or when stable isotope labeling (e.g. with 15N, 2H) is employed. Here, we present a new approach based on mass error distributions for the identification of true and false-assignments among MultiAs. An automatic workflow was developed for the detection and exclusion of false assignments in MultiAs based on their recurring replacement pairs and Kendrick mass defect values. The workflow can validate MFs for mass peaks that are close to detection limit or where naturally occurring isotopes are rare (e.g. 15N) or absent (e.g. P, F), substantially increasing the reliability of MFs assignments and broadening the applicability of UHRMS in characterization of NOM, e.g. for organic nitrogen and organic phosphorus in different environmental compartments, which are key components for global elemental cycles.  

How to cite: Gao, S., Jennings, E., Han, L., Koch, B., Herzsprung, P., and Lechtenfeld, O.: Detection and exclusion of false molecular formula assignments via mass error distributions in ultrahigh resolution mass spectra from natural organic matter., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16215, https://doi.org/10.5194/egusphere-egu24-16215, 2024.

EGU24-16483 | ECS | Orals | BG1.10

Radiocarbon signatures of dissolved black carbon in early winter water masses from the Beaufort Sea 

Linn Speidel, Negar Haghipour, Thomas Blattmann, Lisa Bröder, Julie Lattaud, Alysha I. Coppola, and Timothy I. Eglinton

Black carbon (BC) is a fraction of organic carbon resulting from the incomplete combustion of biomass and fossil fuels. The production and fate of BC is a topic of great interest in the context of ongoing climate change, as the intensity and severity of fires is increasing. The recalcitrant nature enables BC to buffer these changes by removing biomass-derived carbon into longer cycling pools. BC is mainly produced on land and a portion is transported in both particulate and dissolved form by the rivers to the oceans. Dissolved BC (DBC) cycles on millennial timescales, thereby storing BC as fraction of Dissolved Organic Carbon (DOC) in the marine DOC pool before deposition to sediments or complete degradation. However, there is currently limited information on the cycling, transport and evolution of modern riverine DBC, and how it contributes to the deep ocean DOC pool.
The arctic and boreal regions are well recognized as a nexus for climate change, given amplified rates of change in average temperatures and summer precipitation, which exacerbate carbon cycle feedbacks, including enhanced BC production by intensified wildfire seasons. The Beaufort Sea in the Arctic Ocean is composed of different water masses, with Pacific water masses entering from the Chukchi Sea, and arctic rivers - in particular the Mackenzie River - being the major source of freshwater that delivers both terrestrial DOC and DBC. Presently, information on the sources and fate of BC in the Arctic Ocean remains sparse.
Here, we report DBC concentrations and Δ14C values in the Beaufort Sea during early winter conditions. Distinct water masses were sampled, including the outflow of the Mackenzie River and the Pacific water jet on the shelf break, during two cruises in 2021 and 2022 that spanned the coast of north Alaska to the Amundsen Gulf. Preliminary radiocarbon results show that DBC on the shelf break is up to five millennia old. We discuss our findings in the context of regional hydrography and carbon cycle processes.

How to cite: Speidel, L., Haghipour, N., Blattmann, T., Bröder, L., Lattaud, J., Coppola, A. I., and Eglinton, T. I.: Radiocarbon signatures of dissolved black carbon in early winter water masses from the Beaufort Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16483, https://doi.org/10.5194/egusphere-egu24-16483, 2024.

EGU24-16551 | ECS | Orals | BG1.10

Prediction of soil pyrogenic carbon contents from Rock-Eval® thermal analysis: a machine-learning based model 

Johanne Lebrun Thauront, Severin Luca Bellè, Marcus Schiedung, Amicie Delahaie, Marija Stojanova, François Baudin, Pierre Barré, and Samuel Abiven

Pyrogenic carbon (PyC) is a continuum of aromatic and condensed organic molecules. It represents about 15 % of organic carbon in soils and sediments1. However, there is a discrepancy in the literature regarding quantification of PyC: different methods that are currently considered as reference differ largely in their results1,2. Indeed, most methods used to quantify PyC are based on different operational principles (e.g. chemical, thermal or physical stability of PyC, molecular markers) and consequently, they do not cover the same range of the PyC continuum2. In addition, most of them are expensive and/or time consuming. Here, we propose a new PyC quantification method based on Rock-Eval® thermal analysis, thought to be rapid, inexpensive and comparable to the previous methods toolbox. Rock-Eval® thermal analysis has been successfully introduced to the field of soil carbon analysis in the last two decades and allowed to distinguish between various pools of soil carbon (inorganic carbon, stable and active organic carbon) using a single analysis of combined pyrolysis and thermal oxidation3,4. In this study, we formulate the hypothesis that Rock-Eval® thermal analysis in combination with predictive modelling is suitable to quantify PyC in soil matrices.

To build and validate such a model, we chose soil samples originating from contrasting climate zones and parent material and with varying properties including clay content and mineralogy, iron oxide speciation and content, pH, cation-exchange capacity and organic carbon content. We measured PyC using a set of established methods (i.e. CTO-375, BPCA and HyPy) and acquired Rock-Eval® thermograms. Then, we identified the relevant features for PyC quantification in the thermograms by applying several machine-learning approaches. This work adds a new soil carbon pool to the ones already accessible from Rock-Eval® thermal analysis and allows an efficient and rapid quantification of PyC in soils, which is needed for large-scale studies of soil carbon pools.

(1) Reisser, M.; Purves, R. S.; Schmidt, M. W. I.; Abiven, S. Pyrogenic Carbon in Soils: A Literature-Based Inventory and a Global Estimation of Its Content in Soil Organic Carbon and Stocks. Front. Earth Sci. 2016, 4 (August), 1–14. https://doi.org/10.3389/feart.2016.00080.

(2) Hammes, K.; Smernik, R. J.; Skjemstad, J. O.; Schmidt, M. W. I. Characterisation and Evaluation of Reference Materials for Black Carbon Analysis Using Elemental Composition, Colour, BET Surface Area and 13C NMR Spectroscopy. Appl. Geochemistry 2008, 23 (8), 2113–2122. https://doi.org/10.1016/j.apgeochem.2008.04.023.

(3) Disnar, J. R.; Guillet, B.; Keravis, D.; Di-Giovanni, C.; Sebag, D. Soil Organic Matter (SOM) Characterization by Rock-Eval Pyrolysis: Scope and Limitations. Org. Geochem. 2003, 34 (3), 327–343. https://doi.org/10.1016/S0146-6380(02)00239-5.

(4) Cécillon, L.; Baudin, F.; Chenu, C.; Houot, S.; Jolivet, R.; Kätterer, T.; Lutfalla, S.; Macdonald, A.; Van Oort, F.; Plante, A. F.; Savignac, F.; Soucémarianadin, L. N.; Barré, P. A Model Based on Rock-Eval Thermal Analysis to Quantify the Size of the Centennially Persistent Organic Carbon Pool in Temperate Soils. Biogeosciences 2018, 15 (9), 2835–2849. https://doi.org/10.5194/bg-15-2835-2018.

How to cite: Lebrun Thauront, J., Luca Bellè, S., Schiedung, M., Delahaie, A., Stojanova, M., Baudin, F., Barré, P., and Abiven, S.: Prediction of soil pyrogenic carbon contents from Rock-Eval® thermal analysis: a machine-learning based model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16551, https://doi.org/10.5194/egusphere-egu24-16551, 2024.

EGU24-16627 | Posters on site | BG1.10

Direct analysis of marine dissolved organic matter using LC-FT-ICR MS 

Oliver Lechtenfeld, Jan Kaesler, Elaine Jennings, and Boris Koch

Marine dissolved organic matter (DOM) is an important component of the global carbon cycle, yet its intricate composition and the sea salt matrix pose major challenges for chemical analysis. The current view on marine DOM as assessed with ultrahigh resolution mass spectrometry (UHR-MS) is largely based on SPE-extracts known for its consistent underestimation of e.g. the mean nominal oxidation state of carbon (NOSC) and molecular weight as compared to bulk measurements. We introduce a direct injection, reversed-phase liquid chromatography Fourier-transform ion cyclotron resonance (FT-ICR) MS approach to analyze marine DOM without the need for solid-phase extraction. Effective separation of salt and DOM is achieved with a large chromatographic column and an extended isocratic aqueous step. Post-column dilution of the sample flow with buffer-free solvents and implementing a counter gradient reduced salt buildup in the ion source and resulted in excellent repeatability. With this method over 5,500 unique molecular formulas were detected from just 5.5 nmol of carbon in 100 µL filtered Arctic Ocean seawater. We observed highly linear detector response for variable sample carbon concentrations and a high robustness against the salt matrix. We could demonstrate the bias of SPE in marine DOM on a molecular level leading to a predominant detection of less polar DOM, while neglecting a large fraction of polar, heteroatom-rich DOM. In addition, a substantial fraction of terrestrial-derived DOM was previously overlooked in solid-phase extracted marine DOM. Overall, the direct analysis of seawater offers fast and simple sample preparation and avoids fractionation introduced by extraction. The method facilitates studies in environments, where only minimal sample volume is available e.g. in marine sediment pore water, ice cores, or permafrost soil solution. The small volume requirement also supports higher spatial (e.g. in soils) or temporal sample resolution (e.g. in culture experiments). Chromatographic separation adds further chemical information to molecular formulas, enhancing our understanding of marine biogeochemistry, chemodiversity, and ecological processes.

How to cite: Lechtenfeld, O., Kaesler, J., Jennings, E., and Koch, B.: Direct analysis of marine dissolved organic matter using LC-FT-ICR MS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16627, https://doi.org/10.5194/egusphere-egu24-16627, 2024.

EGU24-17503 | ECS | Orals | BG1.10

Sediment source and transport along the Iberian Margin 

Sara Campderrós, Leopoldo D. Pena, Jaime Frigola, Ester Garcia-Solsona, Eduardo Paredes, Negar Haghipour, Heather M. Stoll, and Isabel Cacho

The Iberian Margin is a dynamic margin, affected by complex sedimentary and oceanographic processes. The Mediterranean Outflow Water (MOW) is a prominent water mass that flows along the Iberian margin and interacts with the sediment on the slope. However, more information about how MOW interacts with sediment delivery, distribution, deposition along the margin is needed. In this study we combine Nd, Sr and Pb isotopes on fine-grained detrital sediments (< 63 μm) and 14C measurements in planktonic foraminifera (G. bulloides) in 25 coretop sediment samples collected along the entire Iberian Margin (from the Gulf of Cadiz to the “Cachucho” mount in the Cantabrian Sea). Nd, Sr and Pb isotopes were used to (i) identify the main source areas of terrigenous sediments coming from the Iberian Peninsula and (ii) trace the distribution of these sediments along the Iberian Margin. Additionally, 14C data in planktonic foraminifera were used to obtain radiocarbon ages, that allowed us to date the coretop sediments. Results from Nd, Sr and Pb isotopes allow us to identify three main terrigenous sediment source provinces in the Iberian margin, depicting a prominent south to north gradient. Moreover, large age discrepancies in coretop sediments are strongly associated with the main pathway of MOW, thus suggesting erosion and lateral transport of sediments along the main path of the MOW.

How to cite: Campderrós, S., Pena, L. D., Frigola, J., Garcia-Solsona, E., Paredes, E., Haghipour, N., Stoll, H. M., and Cacho, I.: Sediment source and transport along the Iberian Margin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17503, https://doi.org/10.5194/egusphere-egu24-17503, 2024.

EGU24-17520 | ECS | Posters on site | BG1.10

A multi-method approach to characterise and quantify pyrogenic carbon in tropical urban agroecosystems.  

Stephen Boahen Asabere, Ankit Ankit, Tino Peplau, Simon Drollinger, Christopher Poeplau, Daniela Sauer, and Axel Don

Pyrogenic carbon (PyC) is produced by the incomplete combustion of biomass. It is chemically inert and nutrient-deficient, making it relatively stable in soils. PyC can thus form an important pool of total soil organic carbon (TOC) for C preservation in soils. Despite its significance, data on the nature, level, and relative contribution of PyC to TOC in tropical urban agroecosystems is largely non-existent. In this study, we aim to determine the content and chemical composition of PyC in urban arable soils of Kumasi, a rapidly expanding city in Ghana, West Africa. PyC is likely enriched in these soils, mainly due to soot deposition from traffic, combined with widespread burning of household waste and use of charcoal for cooking.

We sampled topsoils (0–10 cm) from arable fields under four levels of urbanisation intensity (UI), from low to high UI. We employed a range of analytical techniques including visual, chemothermal, thermogravimetric, and biomarker analysis, as well as fourier transformed infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. Visual assessment indicated that ≥80% of all bulk soil samples contained charred macro particles, pointing to PyC enrichment in the urban arable soils. Separating TOC into particulate organic C (POC, ≥63 µm particle size) and mineral-associated organic C (MAOC, <63 µm), chemothermal assessment revealed that PyC contributed less than 0.1% to each fraction under all urban intensity conditions. These PyC levels increased notably along with increasing UI in both TOC fractions. Thereby, median PyC levels in the MAOC fraction (7.8–20.4 mg kg-1) were markedly higher compared to those of the POC fraction (0.1–0.3 mg kg-1). This finding highlight a noticeable PyC contribution to TOC preservations in Kumasi’s tropical urban arable soils, although overall contribution is low. Ongoing thermogravimetric, FTIR spectroscopy, NMR spectroscopy, and biomarker analysis will further detail the amount and chemical composition of PyC in these soils. For instance, we will integrate diagnostic ratios of polycyclic aromatic hydrocarbons with masoccharide anhydrides in order to decouple the relative amount of PyC from biomass and that of fossil fuel.

By characterising the chemical nature of PyC with this wide range of analytical techniques, insights into the source and transformation of PyC in a tropical urban agricultural context can be provided. This will lead to better understanding of the role of PyC in the urban soil carbon cycle and its implications for urban sustainability and global C sequestration efforts.

How to cite: Asabere, S. B., Ankit, A., Peplau, T., Drollinger, S., Poeplau, C., Sauer, D., and Don, A.: A multi-method approach to characterise and quantify pyrogenic carbon in tropical urban agroecosystems. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17520, https://doi.org/10.5194/egusphere-egu24-17520, 2024.

EGU24-18669 | Orals | BG1.10

Pyrogenic carbon: Is it a sink in the global carbon cycle? And why we can’t be sure. 

Matthew Jones, Alysha Coppola, and Cristina Santín

Fires play a critical role in modulating the quantity and quality of carbon (C) stored in the terrestrial biosphere, including in aboveground vegetation and soils. Via riverine transport routes, fires also affect the quantity and quality of C delivered to the global oceans.

The mission of this talk is to set the scene on the multifaceted ways in which fire impacts the global C cycle, with a special focus on the widely-overlooked role of pyrogenic C.

We will begin by summarising how fires impact on terrestrial stores of C, starting with natural cycles of disturbance and recovery that influence total stocks of C on the terrestrial landscape. We will then demonstrate how shifting fire regimes, related to climate change and changes in land use, are perturbing the cycle of C and influencing the quantity of C stored on the landscape. Increased fire frequency and intensity generally promotes a loss of C from landscapes, especially in cases where vegetation cannot recover completely in the shortening time available between disturbance events.

Set within the broader cycle of biogenic C is a sub-cycle of highly recalcitrant ‘pyrogenic’ C – a by-product of incomplete combustion during fires. We will highlight how the special properties of this pyrogenic C promote its longevity in terrestrial stores in a manner that can offset (or ‘buffer’) losses of total C. The process of pyrogenic C storage has been widely overlooked in models of the global C cycle leading to C accounting errors, however we will highlight some recent examples of its implementation in land surface models and the lessons learned from doing so.

Due to its exceptional longevity in terrestrial pools, pyrogenic C has enhanced odds of reaching the global oceans via rivers. We will discuss the disproportionate export of pyrogenic C to the global oceans (relative to biogenic C) and how this leads to an unusual potential for long-term C sequestration.

Finally, we will provide an overview of the current understanding of the global budget of pyrogenic C, integrating best estimates for the fluxes of C to and from terrestrial stores and to and from marine stores. We will also highlight how uncertainties in the magnitude of fluxes in the C cycle lead to poor understanding of whether pyrogenic C currently acts as a sink or source of C to the atmosphere. We will underscore the particular need to constrain the decomposition rates and residence times of pyrogenic C in soils and marine stores if we are to build a complete picture of its role in the global C cycle.

How to cite: Jones, M., Coppola, A., and Santín, C.: Pyrogenic carbon: Is it a sink in the global carbon cycle? And why we can’t be sure., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18669, https://doi.org/10.5194/egusphere-egu24-18669, 2024.

EGU24-19168 | Orals | BG1.10

Molecules and microbes: monitoring peatland health below the surface 

Nicholle Bell, Ezra Kitson, Gianluca Trifiro, and Richard York

Peatlands are organic matter rich (with over 60% organic matter) ecosystems that act as ‘carbon sinks’, storing many times the carbon stored by Earth’s forests. Peatlands act as sponges storing excess water from rain events and releasing it slowly, a mechanism that not only mitigates floods but also filters drinking waters. However, peatlands can only conduct these vital services when healthy and functioning, with a near surface water table and anoxic acidic conditions below the surface. Unfortunately, 80% of UK peatlands have been assessed as damaged mainly via drainage for repurposing the land for other uses. Rewetting peatlands by installing dams is one of the most common methods to restore these damaged bogs. While there is a large amount of evidence that rewetting restores the water table, questions remain whether rewetting successfully restores peatlands to their full health. To answer this question, we need to know what is happening below the surface and examine the roles of key players in peat formation and carbon cycling, namely the microbes and the carbon-containing molecules. It is not clear which of these players is more important, or how they depend on each other. To address this question, we are using the latest technologies (DNA/RNA sequencing, NMR spectroscopy and FT-ICR mass spectrometry) to uncover who they are, how they interact and how they are impacted by drainage and rewetting. The task is not easy as peat is an uncharacterised complex mixture on a molecular and microbial level and the key players could be found in different phases (solid or liquid). In this presentation, I will provide a brief overview of what insights the technologies we are using provide for below the surface characterisation of UK peatlands.

How to cite: Bell, N., Kitson, E., Trifiro, G., and York, R.: Molecules and microbes: monitoring peatland health below the surface, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19168, https://doi.org/10.5194/egusphere-egu24-19168, 2024.

EGU24-19501 | ECS | Posters on site | BG1.10

Inorganic biogenic carbon redistribution and transport in marine sediments 

Prabodha Lakrani Hewage, Luz María Mejía, Negar Haghipour, Mariem Saavedra-Pellitero, Ben Trundley, Timothy Eglinton, David Hodell, and Blanca Ausín

Coccolithophores are calcifying marine phytoplankton whose blooms can be seen from space and play an important, yet complex, role in the global carbon cycle. On one hand, coccolithophores sequester atmospheric CO2 to the deep ocean via photosynthesis contributing to the biological pump. On the other hand, coccolithophores increase aqueous CO2 via precipitation of tiny calcite scales named coccoliths (i.e., carbonate counter pump), which are a major component of marine sediments. Coccoliths are generally in the 2-20 µm size range, and thus they can be winnowed by strong currents and transported to distal locations. Here, we show the first coccoliths radiocarbon (14C) ages and explore the influence of size-dependent coccolith sorting and transport, redistribution, and fate in marine sediments. Because the coccolith depends on the species, we have separated and 14C dated four coccolith size fractions: 8-11 µm, 5-8 µm, 3-5 µm, and 2-3 µm, in  five depth intervals on a sediment core recovered from SHAK06-5K site, off the Iberian Margin. Coccolith separation was achieved by a combination of dry sieving, microfiltration, centrifugation, and settling experiments. Energy Dispersive Spectroscopy (EDS) images of selected size fractions were used to estimate the relative contribution of coccolith and non-coccolith carbonate. A relationship between coccolith 14C age and grain size is apparent in all samples, with the smallest size class recording the youngest ages and the largest coccoliths being the oldest. The latter suggests that hydrodynamic sorting largely influences coccolith redistribution in marine sediments, where larger coccoliths result in increased mobility, as they are prone to resuspension than coccoliths in 2-3 µm size fraction that tend to show cohesive behaviour. The 14C ages of coccoliths are older than those of co-deposited planktic foraminifera, bulk organic carbon (OC), long-chain fatty acids (LCFA), and alkenones. Coccoliths within the 2-3 µm size class show 14C ages comparable to those of OC in all samples. Such a pattern indicates similar transport mechanisms for both the smallest coccoliths and OC, and that the majority of carbonate in the 2-3 µm size fraction, including the non-coccolith particles, is predominantly derived from marine primary production and thus, of biogenic origin. Our study has implications for palaeoceanographic studies using coccoliths as paleo-productivity and geochemical proxies.

How to cite: Hewage, P. L., Mejía, L. M., Haghipour, N., Saavedra-Pellitero, M., Trundley, B., Eglinton, T., Hodell, D., and Ausín, B.: Inorganic biogenic carbon redistribution and transport in marine sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19501, https://doi.org/10.5194/egusphere-egu24-19501, 2024.

EGU24-19642 | Orals | BG1.10

Insight in high alpine soil carbon dynamics from compound-specific and soil fraction radiocarbon analysis on a glacier forefield chronosequence  

Rienk Smittenberg, Valerie Schwab, Hans Sanden, Iso Christl, Frank Hagedorn, Irka Hajdas, Lukas Wacker, Negar Haghipour, Susan Trumbore, Xiaomei Xu, and Stefano Bernasconi

The ecosystem carbon balance of high latitude and high altitude ecosystems is particularly sensitive to climate change, where increasing temperatures generally lead to a rise of the ecosystem carbon storage, but also increasing carbon turnover times. In this study, we investigated the carbon dynamics of the 150-year long Damma Glacier forefield chronosequence, Switzerland. Specifically, we performed radiocarbon analysis of a range of organic matter fractions, sampled in 2007, 2017 and 2022 from soils developing on areas having been exposed for 20-150 years due to the retreat of the glacier. To characterize the age spectrum of material making up the bulk soil carbon, we isolated a range of different fractions, from supposedly 'stable' carbon pools (fine mineral-bound, and peroxide-resistant carbon), microbially ‘labile’ respired CO2, dissolved soil organic carbon (DOC), hydrophobic leaf wax-derived alkanes, and microbial-derived fatty acids. Comparison of our results with the penetration of the radiocarbon bomb spike and the increase of soil and ecosystem carbon over the both the chronosequence (space-for-time) and over the sampling period (time-for-time) allowed us to make the following inferences: (i) A small but persistent contribution of ancient carbon is present in the forefield area exposed by the glacier, which is particularly visible in the hydrophobic leaf wax 14C data. From this we conclude that this old carbon pool is at least in part a remnant of ancient soil carbon from a previous warm and glacier-free period, potentially adding to contributions of fossil-fuel derived black carbon deposition. (ii) There is a significant portion of soil carbon with a decadal-scale carbon turnover rate, and (iii) mineral-bound carbon clearly has a slower turnover time. (iv) Microbial lipids, soil CO2 and DOC 14C content reflect different carbon sources: in younger soils, relatively low 14C contents indicate a higher relative contribution of ancient carbon decomposition, while in older soils this signal is swamped by decomposition of freshly photosynthesized organic matter.

How to cite: Smittenberg, R., Schwab, V., Sanden, H., Christl, I., Hagedorn, F., Hajdas, I., Wacker, L., Haghipour, N., Trumbore, S., Xu, X., and Bernasconi, S.: Insight in high alpine soil carbon dynamics from compound-specific and soil fraction radiocarbon analysis on a glacier forefield chronosequence , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19642, https://doi.org/10.5194/egusphere-egu24-19642, 2024.

EGU24-21439 | ECS | Orals | BG1.10

Modeling microbial functional trait-environment interactions at the continental scale 

Katherine Shek, James Stegen, Alan Roebuck, Amy Goldman, Mikayla Borton, Kelly Wrighton, and Adam Wymore

Inferring linkages between microbial metabolism and dissolved organic matter (DOM) across environmental gradients is a promising avenue to improve biogeochemical predictions at large spatial scales. Despite decades of metagenomic studies identifying microbial functional trait-environment patterns at small spatial scales, general patterns at continental or global scales that may improve large-scale models remain unresolved. Recent influx of multi-omics datasets that represent diverse environmental conditions has enabled scalable analyses linking microbial metabolic niche breadths with key environmental processes, such as carbon and nutrient transformations.

Here, we leveraged publicly available microbial metagenome assembled genomes (MAGs) derived from the Worldwide Hydrobiogeochemistry Observation Network for Dynamic River Systems (WHONDRS) data paired with metabolomic (FTICR-MS) and sediment chemistry data to link microbial metabolic potential with organic chemistry. We annotated 1,384 MAGs representing 65 sites using the R tool microTrait, which categorizes functional traits under the YAS (growth yield-resource acquisition-stress tolerance) framework. Following Hutchinsonian niche theory, we modeled microbial trait combinations as n-dimensional hypervolumes and observed trait-DOM patterns at the continental scale, showing microbial functional tradeoffs along gradients of organic carbon. We expect that at the continental scale, microbial trait profiles will be distinct across climatic regions, and that niche breadth (i.e. the size of individual hypervolumes in trait space) will correlate with DOM/metabolite diversity. The results of this work will distill generalizable patterns of microbe-DOM availability and diversity at large spatial scales, thus identifying information to improve current biogeochemical models.

How to cite: Shek, K., Stegen, J., Roebuck, A., Goldman, A., Borton, M., Wrighton, K., and Wymore, A.: Modeling microbial functional trait-environment interactions at the continental scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21439, https://doi.org/10.5194/egusphere-egu24-21439, 2024.

Soil pore structure, dictated by factors such as porosity, size distribution, and geometry, is crucial for various soil processes and is significantly influenced by soil organic carbon (SOC). As the primary architect of pore geometry within soil aggregates, SOC plays a vital role in determining soil functionality and ecosystem services, yet traditional in-situ analysis methods have fallen short in accurately depicting its intricate distribution. The study employed a two-fold approach to analyze soil structure: a hydrogen peroxide fogging system was used to selectively remove organic carbon from soil aggregates, followed by synchrotron radiation micro-computed tomography (SR-μCT) for in-depth three-dimensional imaging. The results revealed that hydrogen peroxide treatment variably reduced organic carbon in soil aggregates, with Cambisol showing a higher removal efficiency (68-79%) compared to Ultisol (42-47%). The data highlighted the transformation of smaller pores and an increase in larger pore spaces following organic carbon removal, with Cambisol aggregates experiencing the most substantial alterations in pore structures. The impact of organic carbon on the shaping of pore structure within soil aggregates was profound and varied distinctly between the two studied soils—Ultisol and Cambisol. In Ultisol, the organic carbon, initially minimal, played a subtle role in pore structure formation, leading to limited changes post-removal, which suggested a structural resilience possibly due to its inherent mineralogy and physicochemical characteristics. In contrast, Cambisol, with higher initial organic carbon content, showed dramatic alterations in pore structure upon organic carbon removal. This indicated a more critical role of organic carbon in maintaining pore space configurations, with significant increases in larger pore spaces and a decrease in smaller, disconnected pores. These changes highlighted the organic carbon’s crucial function in not only sustaining pore integrity but also in facilitating the complex soil functions such as water retention and root penetration.

How to cite: Liu, J., Tian, Y., and Lu, S.: Investigating the influence of soil organic carbon on pore structure within aggregates a comparative study of Ultisols and Cambisols in China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-139, https://doi.org/10.5194/egusphere-egu24-139, 2024.

EGU24-627 | ECS | Posters on site | SSS5.5

The effect of slope on soil organic matter and on microbial communities under different soil management practices. 

Laura Gismero Rodríguez, Inés Aguilar-Romero, José Alfonso Gómez, Ángel Valverde, and Heike Knicker

In Mediterranean regions, olive plantations are commonly located on steep 
slopes, leading to significant erosion. To mitigate soil loss, sustainable management 
practices often involve allowing natural vegetation cover to grow in the inter-tree 
spaces. 

To provide insights into the impact of different management forms on soil quality, we 
collected topsoil samples (0-15 cm) from an olive orchard with an 11% slope located in 
Southern Spain (Benacazón, Seville). Samples were taken along the slope of plots
managed with conventional tillage (CT) and with natural cover (NC). Additionally, soils
from the tree line, treated with herbicide (TL-Herb.), were included. To account for 
seasonality effects, sampling campaigns were conducted in autumn 2022 (following the 
dry season) and spring 2023 (after the rainy season). 

Soil organic matter content will be correlated with the management practices, slope 
location and microorganism abundance, determined through phospholipid fatty acid 
analysis (PLFA). Microbial respiration analysis will be also performed, using MicroResp
to assess microbial activity. The main hypothesis is that plots with vegetation cover will 
have higher SOM and total microbial biomass contents. We also expect an impact of 
slope location not only on the size of the microbial pool but also on the microbial 
biodiversity.

How to cite: Gismero Rodríguez, L., Aguilar-Romero, I., Gómez, J. A., Valverde, Á., and Knicker, H.: The effect of slope on soil organic matter and on microbial communities under different soil management practices., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-627, https://doi.org/10.5194/egusphere-egu24-627, 2024.

Landsliding creates new substrates upon which ecosystems develop. From a recovery perspective, these substrates may limit plant growth due their harsh conditions. Yet, from a soil formation perspective, these substrates may enhance weathering rates due to a combination of abiotic and biotic factors. Central to both is the role that mycorrhiza may play in ecosystem development, including biogeochemical cycles. Given that at mountainscape scales landslide populations are diverse due to variation in underlying climatic and edaphic conditions, we hypothesize that plant-mycorrhizal associations and their functions will mirror this diversity. To test this hypothesis, we focus on the Sierra de Las Minas in Guatemala (SLM), a mountain range that offers contrasting climatic characteristics associated with aspect (south aspect is dry to mesic and north aspect wet) and steep elevation gradients (400 – 2600 m a.s.l.). Leveraging plant and soil inventories conducted in forest and landslide habitats in the SLM we ask 1) How do plant-mycorrhizal associations vary with aspect, elevation, and habitat? 2) What is the contribution of soil chemistry to the observed variation in plant-mycorrhizal associations? And 3) How do plant-mycorrhizal associations and environmental conditions explain variation in weathering rates? To answer these questions, we integrated our plant inventories with a global database on plant-mycorrhizal associations. The former contains species composition and soil elemental analyses that we used to estimate a variety of weathering indices. The latter was used to assign plants from our field inventories to one or more mycorrhizal type.

Plant-mycorrhizal associations were diverse and greatly contributed to the separation of plant communities in multivariate space. Aspect followed by habitat explained a large fraction of the observed variability. Subsets of soil variables correlated with different dimensions derived from principal component analyses suggesting that plant-mycorrhizal associations contribute diverse functions. In general, weathering indexes differed with aspect and habitat. For example, Vogt Residual Index and Chemical Index of Alteration, were higher in landslide than forest and this difference was more pronounced in the wet than dry to mesic aspects. Further analyses will allow us to examine the contribution of plant-mycorrhizal associations to ecosystem development and soil formation in tropical mountainscapes influenced by landslide activity.

How to cite: Restrepo, C. and Ortiz, Y.: Plant-mycorrhizal associations vary with climate and soil in tropical mountainscapes influenced by landslides: Implications for ecosystem development and soil formation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4322, https://doi.org/10.5194/egusphere-egu24-4322, 2024.

EGU24-4570 | ECS | Posters on site | SSS5.5

Seasonal floodplain dynamics control Fe-rich colloid characteristics 

Maya Engel, Vincent Noel, Samuel Pierce, Tristan Babey, Libor Kovarik, Ravi Kukkadapu, Qian Zhao, Rosalie Chu, Kristin Boye, and John Bargar

High concentrations of Fe-rich colloids have been detected in the anoxic zones of our Slate River floodplain field site (CO, USA) since 2018. We speculated that the composition and abundance of the colloids is controlled by the seasonal dynamics and spatial heterogeneities of the subsurface. Therefore, our goals were to 1) decipher the structure and chemical composition of Fe-rich colloids, 2) identify mechanisms of colloid transformation and 3) understand their biogeochemical function.

TEM analysis revealed nano-spheres and nano-assemblages that consist mainly of Fe, O, Si, and C, with lower contributions from Al, S and Ca. Based on this elemental distribution, we hypothesized that the colloids are composed of Fe minerals that are associated with organic matter and Si. This was further confirmed through Mössbauer spectroscopy and Fe-EXAFS that indicated the colloids consist ferrihydrite associated with organic matter and Si. NanoSIMS imaging detected co-localities of Fe, S, Si, and O, as well as C and N, which demonstrate once more that these are ferrihydrite-based colloids that are embedded in an organic matter-Si matrix.

 These findings are intriguing as they demonstrate high abundance of ferrihydrite-based colloids in anoxic depths of our field site. The stability of the colloids is likely attributed to the coating of organic matter and Si that serves as a protective layer against the reducing conditions. Nevertheless, our data also showed that colloids collected during snowmelt (Spring 2021) contained a higher proportion of Fe(II) than colloids collected during baseflow conditions (Summer 2021). XPS analysis measured higher atomic percentages of C and Si compared to Fe and O in baseflow versus snowmelt colloids, indicating a decrease in the organic-Si protective layer under baseflow conditions, allowing for Fe(II) oxidation and an increase in Fe(III)/ferrihydrite content. The fact that there is an occurrence of S species only in the more reduced snowmelt colloids illustrates the dynamic and delicate composition of these environmental colloids during seasonal changes in hydrology and porewater chemistry.

We are also in the process of interpreting our seasonal data that will shed light on the controls over the seasonal dynamics of the colloids. We have already linked Fe(II) colloid abundance to lower vertical porewater velocities and higher organic matter levels, and are working on additional analyses including data acquired from FT-ICR-MS analysis of the organic composition of the colloids.

How to cite: Engel, M., Noel, V., Pierce, S., Babey, T., Kovarik, L., Kukkadapu, R., Zhao, Q., Chu, R., Boye, K., and Bargar, J.: Seasonal floodplain dynamics control Fe-rich colloid characteristics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4570, https://doi.org/10.5194/egusphere-egu24-4570, 2024.

Soil particle size distribution determines the soil water and nutrient availability, but the spatial variance of the soil texture is often unknown in agricultural fields. This knowledge gap limits demand-oriented and ecological nutrient and water management of crops. It also hampers our understanding of the crop resource use in the field as mediated by soil microbes such as the arbuscular mycorrhizal symbioses. To better understand to which soil conditions maize-mycorrhiza associations respond, we used proximal sensing of soil texture to map within-field variation soil particle size in high spatial resolution and related soil texture to the mycorrhization of organic maize.

To obtain the soil texture maps, we used the mobile sensor platform Geophilus electricus [1]. This proximal soil sensing system deploys a multi-sensor approach to discriminate soil properties by simultaneously measuring the electrical resistivity (up to 1.5m depth) via rolling electrodes and the natural gamma activity, whilst a DGPS guarantees the required precision in geo-referencing during mapping [2]. After calibration of the sensor data with soil samples of the selected fields, the final output is a high-resolution map of the mean soil particle diameter (MPD), which was then used as the independent variable in correlations with the mycorrhization of maize.

The soil texture mapping took place for three investigated fields in 2020 at an organic farm in Lower Saxony, Germany, which is dominated by sandy soils and on which a crop rotation with maize was deployed. The plant and soil sampling took place in 2017, 2020 and 2021 at the respective sites with maize. For each field, the sampling of soils and plants occurred equidistantly in 12 parallel transects along the moving lane direction. We analyzed plant and soil C/N, P, K, Mg, soil pH and organic matter and root colonization by native mycorrhizal fungi during the maize culture.

According to our expectations, we found that the MPD and the clay fraction are accurate describers of the soil P, N, Mg and Corg concentrations for the three years and fields in the crop rotation, while soil K was not responding to the soil texture. Interestingly, we also found a conserved correlation between root colonization by arbuscular mycorrhizal fungi and the MPD of the soil surrounding the roots of the sampled plants. Lower MPD (i.e. higher clay contents) gave rise to stronger maize-mycorrhiza root associations. This response pattern was conserved in years markedly different in mean annual temperature and precipitation. However, the lowest rates of root colonization by mycorrhizas were observed in the dry year of 2020.

We discuss that precision farming technologies may have the potential to guide the management of crops for improved and microbe-assisted resource use. 

 

 

[1] Lück, E., & Rühlmann, J. (2013). Resistivity mapping with GEOPHILUS ELECTRICUS—information about lateral and vertical soil heterogeneity. Geoderma, 199, 2–11. [2] Meyer, S. et al. (2019). Creating soil texture maps for precision liming using electrical resistivity and gamma ray mapping. In Stafford, J. V. (Ed.) Precision Agriculture’19 Proceedings of the 12th European Conference on Precision Agriculture Wageningen (pp. 92). Wageningen, The Netherlands: Wageningen Academic Publishers.

How to cite: Bitterlich, M., bönecke, E., and Rühlmann, J.: Mycorrhiza likes clay - High resolution soil texture maps reveal a conserved correlation of maize mycorrhization to soil particle size across years and fields, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4761, https://doi.org/10.5194/egusphere-egu24-4761, 2024.

EGU24-5851 | Posters on site | SSS5.5

Synergistic relationships between the age of soil organic matter, Fe speciation, and aggregate stability 

Nina Siebers, Eva Voggenreiter, Prachi Joshi, Janet Rethemeyer, and Liming Wang

Understanding the formation and stability of soil aggregates is crucial for sustaining soil functions. This study investigates the impact of organic matter (OM), pedogenic Fe (oxyhydr)oxides, and aggregate size on aggregate stability in an arable soil. Samples were collected from the Ap and Bt horizons of a Luvisol after 14 years of bare fallow, and results were compared with a control field under permanent cropping. In the Ap horizon, bare fallow led to a 26% reduction in the median diameter of the 53-250 µm size fraction, indicating decreased stability of larger microaggregates. Simultaneously, the mass of the 20-53 µm size fraction increased by 65%, suggesting reduced stability, particularly of larger soil microaggregates, due to the absence of fresh OM input. The 14carbon (14C) fraction of modern C (F14C) under bare fallow ranged from 0.50 to 0.90, lower than the cropped site (F14C between 0.75 and 1.01). This difference was most pronounced in the smallest size fraction, indicating the presence of older C. Higher stability and reduced C turnover in <20 µm aggregates were attributed to their elevated content of poorly crystalline Fe (oxy)hydroxides, acting as cementing agents. Colloid transport from the Ap to the Bt horizon was observed under bare fallow treatment, highlighting the release of mobile colloids. This transport may initiate elemental fluxes with potential unknown environmental consequences. In conclusion, the absence of OM input decreased microaggregate stability, releasing mobile colloids and initiating colloid transport.

How to cite: Siebers, N., Voggenreiter, E., Joshi, P., Rethemeyer, J., and Wang, L.: Synergistic relationships between the age of soil organic matter, Fe speciation, and aggregate stability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5851, https://doi.org/10.5194/egusphere-egu24-5851, 2024.

EGU24-6272 | Posters on site | SSS5.5

Long-Term Effects of Silphium perfoliatum on Soil Pore Dynamics and Organic Carbon Accumulation 

Maik Lucas, Lina Rohlmann, and Kathrin Deiglmayr

Perennial bioenergy crops like Silphium perfoliatum (cup plant) are a promising alternative to currently used energy crops such as maize because of their positive feedbacks on various soil properties including carbon sequestration, edaphon activity and erosion control. This study investigates the long-term impact (over 10 years) of the cup plant on soil organic carbon and soil structural parameters in comparisons to a to a nearby ploughed reference site.

We employed tension infiltrometers to measure water infiltration rates at two soil depths (5 and 45 cm). Following this, 100 cm³ aluminum soil cores were extracted for X-ray computed tomography at a resolution of 35 µm. The image analysis, enhanced by machine learning, classified structures including roots, particulate organic matter (POM), biopores, and two types of soil matrix: dense and loose, the latter indicating higher carbon content or more pores slightly below image resolution. The dataset was complimented by the determination of total carbon content and the root length distribution with RhizoVisionExplorer.

The results indicate significant differences in pore structure, primarily in the topsoil, where the cup plant site showed a greater volume of biopores than the reference site. In contrast, the subsoil differences were less marked. Organic carbon content analysis demonstrated a notable increase in the upper soil layer (10-15 cm) at the cup plant site, contributing to a higher soil organic carbon stock than the reference site. However, this effect diminished with depth, becoming negligible at 50-55 cm. In the topsoil, extensive bioturbation/biomixing was observed, as indicated by the darker, more loosely structured soil matrix, which often had the shape of biopores. This bioturbation, which mixed particulate organic matter (POM) into the soil, significantly enhanced soil organic carbon, as evidenced by linear regression analysis.

These findings underscore the substantial impact of the perennial cup plant in enhancing soil structure and carbon content, particularly in the topsoil.

How to cite: Lucas, M., Rohlmann, L., and Deiglmayr, K.: Long-Term Effects of Silphium perfoliatum on Soil Pore Dynamics and Organic Carbon Accumulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6272, https://doi.org/10.5194/egusphere-egu24-6272, 2024.

EGU24-7710 | Orals | SSS5.5

Probing microbe-mineral-organic matter interactions in soils with photothermal infrared spectromicroscopy 

Floriane Jamoteau, Mustafa Kansiz, and Marco Keiluweit

Interactions among microbes, minerals, and organic matter are key controls on carbon, nutrient, and contaminant dynamics in soil and sediments. However, probing these interactions at relevant scales and through time remains an analytical challenge due to both their complex nature and the lack of tools permitting non-destructive time-step analysis. The recent development of optical photothermal infrared (O-PTIR) microscopy has opened the way for non-invasive analysis of these interactions at submicron resolution through time. Here we demonstrate the ability of O-PTIR microscopy to analyze mineral-organic microstructures down to 400 nm, without contact, allowing the time-resolved, non-destructive characterization of both mineral and organic components. Results showed that, while all these mineral-organic microstructures can be analyzed without measurable beam damage using the appropriate laser power, poorly crystalline minerals, and high-molecular-weight compounds are more sensitive to damage than crystalline minerals and low-molecular-weight compounds, respectively. Despite these differences in beam damage sensitivity, we found analytical conditions under which all materials were analyzed without damage and could therefore be analyzed repeatedly over time. With synthetic mineral-organic microstructures, we localized mineral-bound and unbound organic compounds, down to the sub-micron scale. Our results highlight the potential of and provides analytical recommendation for the application of O-PTIR microscopy to resolve microbe-mineral-organic matter interactions in soil and sediments.

How to cite: Jamoteau, F., Kansiz, M., and Keiluweit, M.: Probing microbe-mineral-organic matter interactions in soils with photothermal infrared spectromicroscopy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7710, https://doi.org/10.5194/egusphere-egu24-7710, 2024.

EGU24-8956 | ECS | Posters on site | SSS5.5

Seasonal greenhouse gas flux and microbial community dynamics along a landslide soil chronosequence at the west side of New Zealand's Southern Alps 

Olivia Rasigraf, Anne Riedel, Alexander Bartholomäus, Timothy Clough, Thomas Friedl, and Dirk Wagner

Landslides are an important erosion mechanism in mountainous terrain. They strip large quantities of organic material from ecosystems and expose bedrock to weathering. At the west side of New Zealand’s Southern Alps, super-humid climate and slope instabilities create ideal conditions for frequent landslides, allowing studies of soil formation processes in short-term chronosequences. Here, we investigated soils from three landslides that occurred in 2019 (“young”), 1997 (“intermediate”), and 1965±5y (“old”), respectively. Additionally, reference forest soils located outside of landslide areas were sampled at each location. Closed PVC chambers were installed at different positions on landslide surfaces and reference soils, and gas samples were collected for flux analysis. Soil samples were collected at the same positions from the surface and 20 cm depth and investigated for physico-chemical parameters and microbial community composition.

Net CO2 emissions reached 830 mg h-1m-2 at the “old” site in summer and remained below 356 mg h-1m-2 in winter. Net N2O emissions showed a patchy spatial pattern, reaching rates of 0.2 mg h-1m-2 at the “old” site in summer. At most locations, N2O flux was below the detection limit during winter.

Soils were dominated by bacterial phyla Acidobacteria, Bacteroidota, Chloroflexi, Gemmatimonadota, Planctomycetota, Proteobacteria and Verrucomicrobiota. Dominant archaeal phyla comprised Thermoplasmatota and Crenarchaeota. Beta diversity analysis revealed distinct community composition patterns with the “young” site forming a separate cluster from the older landslides and reference soils. Surface- and depth-associated microbial communities showed high similarity at the “young” site, but they became increasingly distinct at the “intermediate”, “old” and reference soil sites. Community composition at the “old” site showed the least difference to reference sites, indicating that ecosystem development rapidly reached a state similar to older mature forests.

In general, the three landslide sites showed a gradient in the development of soil chemical parameters, microbial community composition and soil respiration rates, with the “old” site being closest to reference sites. Soil respiration rates showed strong seasonal dependence and soil temperature sensitivity.

Our results indicate that respiration rates and microbial community composition of landslide soils reach those of older mature forest soils within a few decades after mass wasting events, if no reactivation occurs and soil development can proceed without disturbance.

How to cite: Rasigraf, O., Riedel, A., Bartholomäus, A., Clough, T., Friedl, T., and Wagner, D.: Seasonal greenhouse gas flux and microbial community dynamics along a landslide soil chronosequence at the west side of New Zealand's Southern Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8956, https://doi.org/10.5194/egusphere-egu24-8956, 2024.

EGU24-9465 | Posters on site | SSS5.5

Mapping redox conditions in a tar-oil contaminated technosol by S K-edge XANES at the micrometer scale 

Karin Eusterhues, Jürgen Thieme, Thomas Ritschel, Pavel Ivanov, and Kai Uwe Totsche

At numerous open pits worldwide, carcinogenic and geno‐toxic tar oil is still exposed to the environment. To understand ongoing tar degradation under different environmental conditions we studied soil structure, water retention, tar composition, and microbial biomass of a technosol under a small tar-oil spill at a former brown coal processing site. We observed that microbial biomass increased with pore volume on our study site: Generally, contaminated layers of the technosol were more porous than uncontaminated control soils and accommodated more microbes. However, the relationship was not linear. We therefore wondered whether the redox regimes within the aggregates of the different layers provide comparable conditions for microbial degradation.

We used the chemical state of S as a proxy for the prevailing redox-conditions and µXANES on thin sections (5 µm spatial resolution) to analyze the S speciation in relation to soil structure. First results show that the tar is not homogeneously composed and that the proportion of reduced S compounds increases with soil depth: Particularly S-rich domains within the tar are often roundish, up to 200 µm in size and composed of varying proportions of inorganic sulfide-S, organic monosulfide-S or thiol-S, sulfoxide-S, and sulfonate-S. The topmost layer (0-5 cm) of the technosol is very porous. Here, the tar matrix is dominated by sulfonate-S. At more than 5 cm depth, the soil also has a high porosity due to large pores > 50 µm but at the same time includes mm-sized, compact aggregates with only few small pores (1-10 µm and 10-50 µm). The tar matrix within these aggregates contains sulfidic S in addition to the sulfonate-rich component. However, adjacent to pore surfaces we observe 5-15 µm thick (oxidized) rims with only sulfonate-S.

Our data show that the tar is not only chemically complex, but also heterogeneous in composition at the µm scale. Below a soil depth of 5 cm, we can assume that microbial tar degradation is slowed down because of the anoxic conditions within the aggregates, although pores > 50 µm are abundant and bacterial cell counts are high.

How to cite: Eusterhues, K., Thieme, J., Ritschel, T., Ivanov, P., and Totsche, K. U.: Mapping redox conditions in a tar-oil contaminated technosol by S K-edge XANES at the micrometer scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9465, https://doi.org/10.5194/egusphere-egu24-9465, 2024.

EGU24-11128 | Orals | SSS5.5

The influence of structural complexity of microbial habitats on soil organic matter decomposition: a theoretical analysis 

Ksenia Guseva, Carlos Arellano, Magdalena Rath, Paul Prinz, Moritz Mohrlok, and Christina Kaiser

The soil pore space constitutes a highly heterogeneous habitat that harbors a rich microbial diversity. Microbial processes within soils are intricately linked to the physical and chemical characteristics of micro-environments of pores where they reside. The dynamics of decomposition of organic matter therefore is shaped by the dispersion dynamics or spatial constraints imposed on microorganisms and their enzymes. Therefore, incorporating the complex soil architecture into computational models at the microscale is a crucial step to improve our predictions of the dynamics of soil organic matter (SOM) turnover.

In this work, we employ theoretical models to elucidate the impact of soil structural complexity and heterogeneity on organic matter decomposition dynamics, and characterize mechanisms that enhance or constrain it. In the first part, we show the impact of compartmentalization of the substrate on enzyme activity, considering a scenario where microbes have no direct physical access to the substrate and only smaller freely diffusing enzymes can reach it. Our findings reveal that, in this context, enzyme lifetime imposes limitations on the turnover rate of the reaction, subsequently affecting the uptake and growth rates of microorganisms. In the second part, we examine the effect of soil architecture on microbial decomposition dynamics. Our results highlight two contrasting aspects necessary for rapid decomposition: on one hand there is a need for refuges/shelters where microbial activity is boosted trough accumulation of enzymes, and on the other there is a need for high connectivity (accessibility) of the pore space for the microbial population to spread. Through our examination, we unveil the intricate interplay between these apparently conflicting conditions and their profound effects on population growth and substrate decomposition rates.

How to cite: Guseva, K., Arellano, C., Rath, M., Prinz, P., Mohrlok, M., and Kaiser, C.: The influence of structural complexity of microbial habitats on soil organic matter decomposition: a theoretical analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11128, https://doi.org/10.5194/egusphere-egu24-11128, 2024.

EGU24-11265 | ECS | Posters on site | SSS5.5

Aged carbon mineralisation from headwater peatland floodplains in the Peak District, UK 

Danielle Alderson, Martin Evans, Mark Garnett, and Fred Worrall

Floodplains are dynamic ecosystems that cycle carbon, which is both delivered from upstream catchment sources and produced in-situ by pedogenesis. These landforms are being progressively acknowledged as important environments of carbon processing, with the capacity for both substantial carbon sequestration in addition to acting as hotspots of carbon mineralisation. The balance between storage and release is dependent on a number of controls including landscape position, environmental conditions and soil characteristics. This study focuses on three headwater floodplains in a single catchment (approximately 10km in length), downstream of a highly eroded blanket bog peatland in the Peak District, UK. Aged organic carbon of peatland origin has been found in floodplains in this area based on prior research, and therefore we aimed to understand whether the allochthonous carbon was being mineralised in this context. We examined sediment cores and analysed the radiocarbon (14C) content of CO2 respired from the floodplain soils using a partitioning approach to scrutinise the depth and age relations of respiration in the individual floodplains and patterns of age distributions downstream. As such, we examined whether soil heterogeneity as a function of distance downstream and within individual floodplain profiles had an impact on age of respired CO2.

Aged organic carbon was released from the upper and mid floodplain sites (14C ages of 682 and 232 years BP, respectively), whereas only modern dates were recorded at the lower site. The sedimentology was in accordance with the radiocarbon dates, suggesting primarily allochthonous deposition at the upper sites, but a dominance of in-situ soil development at the lower site. There was no age-depth relationship within individual floodplains, suggesting that the floodplain sediments were well-mixed and that aged organic matter was being processed both at the surface and at depth in the uppermost sites. An isotope mass balance mixing model indicated the control of two sources of CO2; recently fixed C3 organic matter and CO2 produced by methanogenesis. The results indicate that floodplains in a relatively narrow halo around eroding headwater peatlands could be important sites of aged carbon turnover originally derived from upstream sources, with those further downstream playing a different role. Reworked carbon does not transfer passively through the system and experiences periods of deposition where it can be subject to microbial action. In areas where organic carbon has previously been ‘locked up’ (e.g., permafrost regions) but is now under the threat of release due to climate change, this is an important consideration.

How to cite: Alderson, D., Evans, M., Garnett, M., and Worrall, F.: Aged carbon mineralisation from headwater peatland floodplains in the Peak District, UK, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11265, https://doi.org/10.5194/egusphere-egu24-11265, 2024.

EGU24-11474 | ECS | Posters on site | SSS5.5

Spatiotemporal variations of manganese-mediated litter decompositions across oxic-anoxic transitions in deciduous forest soils 

Nathan Chin, Egon Van Der Loo, Kristen DeAngelis, and Marco Keiluweit

Manganese (Mn) has been demonstrated to be a significant driver of litter decomposition in forest soils, regulating nutrient cycling, CO2 production, and ultimately soil carbon storage across forest systems globally. Recent evidence suggests that Mn-driven litter decomposition is dependent on ubiquitous oxic-anoxic interfaces in soils, which act as potential hotspots for the formation of reactive Mn(III) oxidants. Here we will show how oxic-anoxic interfaces in forest soils, arising from spatiotemporal variations in moisture, affect Mn(III)-driven litter decomposition. To do this, we tested the effect of in-field Mn additions on litter decomposition along a deciduous forest upland-to-wetland transect exhibiting dynamics in oxic-anoxic transitions. Within Mn-amended litterbags incubated across the transect, we monitored spatiotemporal variations in Mn(III) formation and litter decomposition. Over the course of the experiment, increased Mn amendments in litter correlated with both enhanced CO2 production as greater mass loss compared to untreated litter, particularly during periods of greater Mn(II) oxidation. Wet-chemical extractions revealed increasing Mn(II) oxidation over the growing season in elevated Mn treatments, resulting in enhanced Mn(III) formation. Additionally, the greater abundance of Mn(III) phases in Mn treated litter compared to untreated litter was significantly correlated to a greater degree of oxidation in the litter and greater water extractability of litter carbon, demonstrating enhanced litter decomposition in Mn amended litter. Across the forest transect, Mn oxidation and Mn(III) formation were greatest at sites with greater presence of oxic-anoxic transitions, which coincided with the sites exhibiting higher litter decomposition. Therefore, our results show that Mn(III)-mediated litter decomposition occur in hotspots present at oxic-anoxic interfaces across spatiotemporal gradients in forest soils. These findings provide first insights into the spatiotemporal links between Mn and carbon coupled redox cycling in forest ecosystems.

How to cite: Chin, N., Van Der Loo, E., DeAngelis, K., and Keiluweit, M.: Spatiotemporal variations of manganese-mediated litter decompositions across oxic-anoxic transitions in deciduous forest soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11474, https://doi.org/10.5194/egusphere-egu24-11474, 2024.

EGU24-13293 | Orals | SSS5.5

Laboratory for Observing Anoxic Microsites in Soils (LOAMS) 

Vincent Noël, Samuel Webb, and Kristin Boye

Redox reactions essentially underlie several biogeochemical processes and are typically spatiotemporally heterogeneous in soils and sediments. However, redox heterogeneity has yet to be incorporated into mainstream conceptualizations and modeling of soil biogeochemistry. Anoxic microsites, a defining feature of soil redox heterogeneity, are non-majority oxygen depleted zones in otherwise oxic environments. Neglecting to account for anoxic microsites can generate major uncertainties in quantitative assessments of greenhouse gas emissions, C sequestration, as well as nutrient and contaminant cycling at the ecosystem to global scales. However, only a few studies have observed/characterized anoxic microsites in undisturbed soils, primarily, because soil is opaque and microsites require µm-cm scale resolution over cm-m scales. Consequently, our current understanding of microsite characteristics does not support model parameterization.

To resolve this knowledge gap, we simultaneously (i) study impact from anoxic microsites on biogeochemical cycles at the soil scale and (ii) detect, quantify, and characterize anoxic microsites directly from natural cores.

We have examined the influence of anoxic microsites on biogeochemical cycles of nutrients (C, S, and Fe) and contaminants (Zn, Ni, As, U), combining results from experimental columns and natural cm-scale anoxic microsites of floodplain sediments at the upper Colorado River Basin scale. In parallel, we have demonstrated through a proof-of-concept study that X-ray fluorescence (XRF) 2D mapping can reliably detect, quantify, and provide basic redox characterization of anoxic microsites using solid phase “forensic” evidence. Rapid screening of large cores at high spatial and energy resolution, i.e. 1-100 µm resolution over cm-m areas, followed by systematic algorithm-driven data processing, allows for relatively quick identification, quantification, and characterization of actual anoxic microsites. To date, these investigations have revealed direct evidence of anoxic microsites in predominantly oxic soils such as from an oak savanna and toeslope soil of a mountainous watershed, where anaerobicity would typically not be expected. We also revealed preferential spatial distribution of redox microsites inside aggregates from oak savanna soils. We anticipate that this approach will advance our understanding of soil biogeochemistry and help resolve “anomalous” occurrences of reduced products in nominally oxic soils.

How to cite: Noël, V., Webb, S., and Boye, K.: Laboratory for Observing Anoxic Microsites in Soils (LOAMS), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13293, https://doi.org/10.5194/egusphere-egu24-13293, 2024.

EGU24-13732 | Orals | SSS5.5

Exploring subsurface heterogeneity of nitrogen and carbon cycling under a southeastern U.S. cattle grazing pasture  

Joseph Roscioli, Joanne Shorter, Elizabeth Lunny, Scott Herndon, Nuria Gomez-Casanovas, and Peter Byck

Subsurface cycling of nitrogen and carbon is central to our understanding of biosphere-atmosphere exchange and can strongly impact the ability of soil to be a greenhouse gas source or sink.  The underlying processes exhibit strong environmental dependence that can lead to substantial spatiotemporal heterogeneity across scales.  Here we present a study that explores how that variability manifests in subsurface greenhouse gases and their isotopes under a cattle grazing pasture in the southeastern U.S.  We used an automated array of 24 diffusive soil gas probes connected to a tunable infrared laser direct absorption spectrometer (TILDAS) to produce real-time maps of nitrous oxide isotopes, carbon dioxide, and oxygen with high spatial (meters) and temporal (hours) resolution.  We discuss ways to visualize and process the heterogeneity data, including using Lorenz plots and two-dimensional correlation, to reveal the magnitude and persistence of spatial heterogeneity of these gases.  CO2 is found to be much more spatially homogeneous than N2O, indicating a stronger dependence of N processing upon the local environment.  Analysis of N2O isotopic signatures shows that the last step in subsurface N-cycling, N2O reduction, is spatially heterogeneous and related to the magnitude of “hot spots” of N2O production.   

How to cite: Roscioli, J., Shorter, J., Lunny, E., Herndon, S., Gomez-Casanovas, N., and Byck, P.: Exploring subsurface heterogeneity of nitrogen and carbon cycling under a southeastern U.S. cattle grazing pasture , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13732, https://doi.org/10.5194/egusphere-egu24-13732, 2024.

EGU24-14399 | Orals | SSS5.5

The interplay of soil spatial heterogeneity and water in stabilizing and destabilizing soil organic matter 

Claire Chenu, Charlotte Védère, Israel Kpemoua, Naoise Nunan, Valérie Pot, Patricia Garnier, Clémentine Chirol, and Laure Vieublé-Gonod

Soil moisture is a main driver of soil organic matter dynamics of soil organic matter and is an important environmental variable in all models predicting changes in soil carbon stocks from site to global scales. Despite this, the mechanisms determining the response of heterotrophic soil respiration to soil moisture remain poorly quantified, being represented in most current carbon cycle models as simple empirical functions. Soils are extremely complex and heterogeneous environments and many properties observed at the profile or at the plot the scale are, in fact, determined by microscale conditions and processes.

The spatial heterogeneity of soil constituents and assemblages defines a myriad of contrasted micro-habitats, hosting diverse microorganisms, with contrasted moisture related characteristics and presumably contrasted levels of microbial activity. In addition, the respective spatial distributions of organic resources and microbial decomposers and the transfer rates between them, that depend on soil moisture, explain that similar organic compounds may have contrasted residence times in soil, being stabilized or not.

We consider how do soil moisture and soil spatial heterogeneity may explain the stabilisation of organic matter. Different pore size classes exhibit different rates of microbial decomposition, when considering different soils, across published studies and in a single laboratory experiment. Soil moisture affects the dynamics of biogeochemical hotspots, such as the detritusphere.

Regarding destabilization of soil organic matter, priming effect was revealed to be soil moisture dependent, that can be explained by varying access of newly produced enzymes to native soil organic matter. The Birch effect, a well-described flush of mineralization observed after rewetting dry soils, may also be partly explained at the microscale by changes in the local architecture of soils.

Overall, considering the interplay between soil spatial heterogeneity, soil moisture and the activity of microbial decomposers offers insights in understanding the stabilisation and de-stabilisation of soil organic matter. Incorporating this process level understanding into soil organic matter dynamics models is a challenge, as it requires the identification of relevant soil structure descriptors of these processes, at different time scales.

How to cite: Chenu, C., Védère, C., Kpemoua, I., Nunan, N., Pot, V., Garnier, P., Chirol, C., and Vieublé-Gonod, L.: The interplay of soil spatial heterogeneity and water in stabilizing and destabilizing soil organic matter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14399, https://doi.org/10.5194/egusphere-egu24-14399, 2024.

EGU24-14407 | ECS | Posters on site | SSS5.5

The effect of habitat complexity on bacterial competition 

Carlos Arellano-Caicedo, Ara Fadhel, Pelle Ohlsson, and Edith C. Hammer

The way microbes interact in nature can vary widely depending on the spatial characteristics they are located in. This aspect of the microbial environment can determine whether processes such as organic matter turnover, community dynamics, or microbial speciation, among others, occur and their impact on soil functions. Investigating how the geometry of microhabitats influences microbes has been traditionally challenging due to methodological limitations. A major challenge in soil microbial ecology is to reveal the mechanisms that allow a wide diversity of microorganisms to co-exist. This study is directed towards answering the question of how spatial complexity affects bacterial competition, and how this can lead to organic matter turnover.

Using microfluidic chips that mimic the inner soil pore physical geometry, and fluorescence microscopy, we followed the effect of an increasing complexity in the growth and substrate degradation of two soil bacterial strains. The parameters used to define complexity were two: the turning angle and order of pore channels, and the fractal order of pore mazes. When we tested the effect of an increasing in turning angle sharpness on microbial growth, we found that in sharper angles, both species coexisted, but only until certain sharpness where both populations decreased. We also found that substrate degradation was highest in the same sharp angles that permitted the coexistence of both strains. Our next series of experiments, testing the effect of maze fractal complexity showed that both strains could coexist and degrade the most substrate in complex mazes that had dead ends as opposed to mazes that were highly connected. Our results demonstrate the relevance of microhabitat complexity in bacterial competition and substrate degradation, showing that complex habitats allow bacterial strains to coexist and perform functions with higher efficiency than in less complex ones.

How to cite: Arellano-Caicedo, C., Fadhel, A., Ohlsson, P., and Hammer, E. C.: The effect of habitat complexity on bacterial competition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14407, https://doi.org/10.5194/egusphere-egu24-14407, 2024.

EGU24-15015 | ECS | Orals | SSS5.5 | Highlight

On the Microgeography of Soil Bacterial Communities 

Samuel Bickel and Dani Or

The highly fragmented soil physical environment and the dynamic aqueous phase jointly constrain bacterial life by limiting cell dispersion and modulating diffusion and access to patchy nutrients. A modeling framework that integrates soil hydration conditions with soil organic carbon inputs provides systematic estimates of size distributions and interaction distances among soil bacterial populations. The patterns of bacterial community microgeography provide an important building block for interpreting soil ecological functioning. Experiments and mechanistic modelling show that soil bacterial cluster sizes (measured by counting cell numbers within a community) follow an exponentially truncated power law with parameters (e.g., largest community size) that vary with mean soil water content and carbon inputs across biomes. Theory predicts that similar to human settlement size distributions, tree sizes and other systems in which growth rates are defined by the environment independent of the object size, the resulting bacterial community size distributions is likely to obey the so-called Gibrat’s law. Our results support a potential for generalization using positively skewed distributions of soil bacterial community sizes (e.g., log normal and Gamma). We show that soil bacteria reside in many small communities (with over 90% of soil bacterial communities having less than 100 cells), supported by theoretical predictions of log-normal distribution for non-interacting soil bacterial community sizes with scaling parameters that vary with biome characteristics. We will use estimates of the fraction of the largest bacterial communities where anoxic conditions may develop under prevailing conditions to constrain the number of anoxic hotspots per soil volume.

How to cite: Bickel, S. and Or, D.: On the Microgeography of Soil Bacterial Communities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15015, https://doi.org/10.5194/egusphere-egu24-15015, 2024.

A large fraction of organic matter in soils is associated with mineral phases. This association is mediated by manifold processes (reactive transport, drying-rewetting cycles, biofilm formation, digestion of mineral particles, etc.) and ultimately leads to a stabilization of organic matter in soil [1]. Adsorption describes the mechanism for this association at the molecular level. Ultrahigh resolution mass spectrometry like FT-ICR-MS has gained interest in the study of adsorption processes because of its high sensitivity, resolving power and mass accuracy which allow to study the complex organic mixtures present in soils, and therefore provides molecular insight [2]. For that, supernatant composition can be compared before and after adsorption, but this indirect approach is often not sensitive enough to detect the sorption of small amounts of organic matter, i.e., during initial adsorption to pristine mineral surfaces. An alternative approach is to use laser desorption ionization (LDI) to directly analyze the adsorbed molecules on the mineral surfaces. The method theoretically allows laser spot size of ~ 20-50 µm and even allows imaging of thin sections; methodological advances could therefore improve our understanding of soil organic matter and its spatial heterogeneity [3].

We applied LDI-FT-ICR-MS to study the ionization of individual molecules with and without the presence of DOM (SRFA and pine/ beech litter extracts), and measured adsorption isotherms of individual molecular formulas in dissolved organic matter on quartz, illite and goethite after 24h of contact. Analog to organic matrices used in matrix-assisted LDI, detectability of model compounds improved by factor 2.5 – 40 when spiked into a DOM matrix. In case of sinapic acid, presence of DOM shifted the ionization towards the monomer ion [M-H]- as compared to a mixture of mono-, di- [2M-H]- and trimer [3M-H]- species when analyzed in pure form. These results suggest that soil organic matter and its soluble analogs act as suitable matrices in LDI experiments that ensure proper ionization of the mixture as a whole. In a next step, ion abundance data from sorption experiments was used to model the adsorption process of individual molecular formulas by a Langmuir isotherm approach. We derived estimates of sorption capacity and sorption affinity for each molecular formula, and identified the molecular properties explaining differences in both estimates, as well as their differences between mineral phases. Our data highlight the benefits of LDI-FT-ICR-MS for the study of sorption phenomena in soils, and opens perspectives for resolution of spatial heterogeneity in soils.

References

[1] Kleber, M., Bourg, I. C., ... & Nunan, N. (2021): Dynamic interactions at the mineral–organic matter interface. Nature Reviews Earth & Environment 2: 402-421.

[2] Bahureksa, W., Tfaily, M. M., ... & Borch, T. (2021): Soil organic matter characterization by Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS): A critical review of sample preparation, analysis, and data interpretation. Environmental Science & Technology 55: 9637-9656.

[3] Lohse, M., Haag, R., ... & Lechtenfeld, O. J. (2021). Direct imaging of plant metabolites in the rhizosphere using laser desorption ionization ultra-high resolution mass spectrometry. Frontiers in Plant Science 12: 753812.

How to cite: Simon, C. and Lechtenfeld, O.: Adsorption of dissolved organic matter to mineral phases studied by laser desorption ionization mass spectrometry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15127, https://doi.org/10.5194/egusphere-egu24-15127, 2024.

EGU24-15762 | ECS | Orals | SSS5.5

Continuum and particle scale analysis of nutrient gradients in the rhizosphere  

Eva Lippold, Magdalena Landl, Eric Braatz, Steffen Schlüter, Rüdiger Kilian, Carmen Höschen, Gertraud Harrington, Carsten W. Mueller, Andrea Schnepf, Robert Mikutta, Martina I. Gocke, Eva Lehndorff, and Doris Vetterlein

Plant roots create chemical gradients within the soil rhizosphere but little information exists on the effect of root types and ages on the distribution of chemical gradients. Research aim was to develop an imaging workflow and to analyze and model the effects of radial root geometry, root hairs, and ages on nutrient gradients around roots.

The presented correlative imaging workflow is suitable for targeted sampling of roots in their 3D context and assessing the imprint of roots on chemical properties of the root-soil contact zone at µm to mm scale. Maize (Zea mays) was grown in 15N-labelled soil columns and pulse-labelled with 13CO2 to visualize the spatial distribution of carbon inputs and nitrogen uptake together with the redistribution of other elements. Soil columns were scanned by X-ray computed tomography (X-ray CT) at low resolution (45 µm) to enable image-guided subsampling of specific root segments. Resin embedded subsamples were then analysed by X-ray CT at high resolution (10 µm) for their 3D structure and chemical gradients around roots using micro X-ray fluorescence spectroscopy (µXRF), nanoscale secondary ion mass spectrometry (NanoSIMS), and laser-ablation isotope ratio mass spectrometry (LA-IRMS). NanoSIMS and LA-IRMS detected the release of 13C into soil up to a distance of 100 µm from the root surface, whereas 15N accumulated preferentially in the root cells.

Concentration gradients with different spatial extents could be identified by µXRF. The observed concentration gradients were compared to simulated gradients generated by a process-based, radially symmetric 1D rhizosphere model. An accumulation of calcium and sulfur was observed, particularly around old root segments. Our model simulations indicated that this phenomenon originates from the radial structure of the root, leading to enhanced nutrient transport towards the root surface. Gradients of calcium and sulfur could be accurately predicted by the model around a single growing root, when they were mainly caused by sorption.

However, at the pore-scale, phenomena like local precipitation, which could be visualized using our methodology, were inadequately accounted for by the classic model approach. Nonetheless, the observed extension of the gradients was well described by the model. The presented approach combining targeted sampling of the soil-root system and correlative microscopy opens new avenues for unravelling rhizosphere processes in situ.  

 

 

How to cite: Lippold, E., Landl, M., Braatz, E., Schlüter, S., Kilian, R., Höschen, C., Harrington, G., Mueller, C. W., Schnepf, A., Mikutta, R., Gocke, M. I., Lehndorff, E., and Vetterlein, D.: Continuum and particle scale analysis of nutrient gradients in the rhizosphere , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15762, https://doi.org/10.5194/egusphere-egu24-15762, 2024.

EGU24-16443 | Orals | SSS5.5

Embracing the structural framework of soil in microbiological and ecological research 

Hannes Schmidt, Naoise Nunan, Xavier Raynaud, Steffen Schlueter, Vincent Felde, Berit Zeller-Plumhoff, Gaëlle Marmasse, Alberto Canarini, Lucia Fuchslueger, and Andreas Richter

Soil is a complex system with a high degree of physical, chemical, and biological heterogeneity. Soil structure is organized into entangled pore networks that provide an immense surface area and are partially filled with gases and aqueous solutions. This heterogeneous landscape houses a multitude of active and inactive organisms of which soil bacteria and fungi are considered the driving forces of nutrient cycling and biogeochemical processes. Standard analyses such as soil respiration are meaningful measures to estimate processes on a meso- and macroscale while the biological agents whose actions we measure are mainly to be found on the microscale. Yet, our understanding of microbial living conditions in soil and their consequences for activity, growth, and turnover is severely limited. In this presentation I will focus on a microbial perspective and present data from various experiments where soil microbial identity and/or activity were investigated while acknowledging spatial aspects of their microenvironments. I will provide an updated view on spatial distribution of microbial communities within soils, including evidence that suggests that the density of bacteria in soils has likely been underestimated by orders of magnitudes for decades. Microbial density arguably is a major determinant of cell-to-cell interactions, and thus many processes involved in microbial nutrient cycling that we measure on a larger scale. I will further argue to embrace soil heterogeneity rather than minimizing it, for example by using intact soil cores instead of sieved soils for stable isotope labelling experiments. I will present data on in situ bacterial and fungal growth which suggests that preserving soil physical architecture while investigating microbial parameters could bring experimental measurements significantly closer to field conditions, while also opening new avenues to improve our understanding of spatial aspects of soil microbiology.

How to cite: Schmidt, H., Nunan, N., Raynaud, X., Schlueter, S., Felde, V., Zeller-Plumhoff, B., Marmasse, G., Canarini, A., Fuchslueger, L., and Richter, A.: Embracing the structural framework of soil in microbiological and ecological research, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16443, https://doi.org/10.5194/egusphere-egu24-16443, 2024.

EGU24-16904 | ECS | Posters on site | SSS5.5

Two-step unsupervised clustering method on soil nanoscale secondary ion mass spectrometry (NanoSIMS) images to determine the spatial arrangement of minerals and organic matter 

Yahan Hu, Johann Zollner, Martin Werner, Steffen Schweizer, and Carmen Höschen

In the soil, mineral particles, organic matter, and soil organisms are arranged in a complex architecture which can influence organic matter dynamics. Nanoscale secondary ion mass spectrometry (NanoSIMS) provides insights into the microscale arrangement of soil minerals and organic compounds at a resolution of approximately 50 nm. However, current NanoSIMS image processing lacks methods to analyze large datasets automatically and requires manual intervention. We developed a two-step unsupervised clustering method for batch analyses of NanoSIMS images. Our two-step method consists of K-Means clustering as the first step generating around 100 clusters, followed by hierarchical agglomerative clustering (HAC) re-grouping the K clusters into less than 10 cluster groups. The elbow method, HAC linkage method and gap statistics are used to automatically select the optimal clustering numbers. Subsequently, soil minerals and organic matter can be spatially segmented and identified as different species. Further, this method could apply to the spatial arrangement of mineral-dominated and organic matter-dominated parts or different mineral types. Moreover, this method enables the analyses of larger datasets with >100 NanoSIMS images providing insights of organo-mineral interactive hotspots or even micro function domains involved in soil organic matter dynamics.

How to cite: Hu, Y., Zollner, J., Werner, M., Schweizer, S., and Höschen, C.: Two-step unsupervised clustering method on soil nanoscale secondary ion mass spectrometry (NanoSIMS) images to determine the spatial arrangement of minerals and organic matter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16904, https://doi.org/10.5194/egusphere-egu24-16904, 2024.

EGU24-17573 | ECS | Posters on site | SSS5.5

Plant-derived organic exudates in soil: Mobility and aggregation 

Tom Guhra, Jona Schönherr, and Kai Uwe Totsche

Plant derived photosynthates are a component of the biotic organic matter involved in carbon cycling and storage due their mobility and formation of organo-mineral associations and (micro-)aggregates. Such photosynthates are typically found as components of mucilage or generate during the germination of seeds in the soil environments. While the effect of, e.g., mucilage, on soil physical properties has been intensively investigated, their role for carbon transport, adsorption, and aggregation process is rather unclear. Most of the knowledge available originates from studies that used single compounds, e.g., oxalic acid, glucose, polygalacturonic acid or mixtures of those in aqueous solutions. In our study, we utilized hydrogel-freed plant exuded photosynthates (PDE) extracted from four different seed types (Linum usitatissimum, Plantago ovata, Ocimum basilicum and Salvia hispanica) to investigate their interactions with minerals typically for temperate soil. In batch experiments, PDE adsorbed to both illite and goethite minerals with a preference of polysaccharide-rich PDE to goethite. During the adsorption, organo-mineral associations were formed leaving behind a less mineral-affine fraction of PDE prone to transport or degradation. Hence, PDE transport was also studied in column experiments using quartz functionalized with reactive minerals where we measured the breakthrough of PDE exploiting their distinct fluorescence. Furthermore, we followed the gravity-constrained aggregation dynamics of PDE-mineral associations using tensiometric measurements. We showed that low PDE concentrations facilitate aggregation via polymer bridges leading to a rapid sedimentation of aggregates while PDE available in excess prevents aggregation via steric repulsion and thus decelerates sedimentation. These results showed that PDE extracted from seeds might serve as better surrogates of natural plant exudates to study their role for the formation and transport of organo-mineral associations and aggregates in soils.

How to cite: Guhra, T., Schönherr, J., and Totsche, K. U.: Plant-derived organic exudates in soil: Mobility and aggregation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17573, https://doi.org/10.5194/egusphere-egu24-17573, 2024.

EGU24-18568 | Posters on site | SSS5.5

Intrinsic potential and activity of nitrate turnover examined for different hydrogeological aquifer settings 

John Lester Pide, Johann Holdt, Vitor Patricio Cantarella, Adrian Mellage, Olaf Cirpka, Carsten Leven-Pfister, Jan-Peter Duda, Daniel Buchner, and Christian Griebler

Nitrate (NO3-) is one of the most serious contaminants in groundwater, frequently deteriorating water quality and groundwater use as drinking water. Nitrate can, at specific environmental conditions, be removed within the subsurface environment via natural biogeochemical processes, such as denitrification and dissimilatory nitrate reduction to ammonium (DNRA). Traditionally, research has concentrated on the NO3- attenuation potential and microbial activity in groundwater, largely overlooking an aquifers’ sediment matrix as a reaction contributor. We hypothesize that the sedimentary deposits host the major potential for NO3- reduction, carrying the majority of microorganisms as well as different sources of electron donors. Moreover, diverse hydrogeological settings harbor different sources and varying amounts of electron donors such as reduced iron minerals and organic matter. Therefore, subsurface physicochemical heterogeneity, determined by sedimentology, controls the potential of an aquifer to reduce nitrate. We hypothesize that locations where physicochemical conditions favor NO3- reduction, we may expect microbes involved in these processes to be more abundant and highly active, leading to a fast NO3- removal from groundwater.

Here, we present results from temperature-controlled (12°C) batch incubations and flow-through experiments conducted over several months using fresh sediments from an alluvial, tufaceous unconfined aquifer, with embedded peat layers, in an agricultural landscape in southwest Germany. Batch experiments received an addition of NO3- of 50 mg L–1. Sediment columns were supplied with nitrate-spiked groundwater collected from the site at a maximum inlet concentration of 150 mg L and run in continuous injection mode. Batch experiments showed a gradual decrease in the initially high hydrogen sulfide (H2S) concentration, becoming undetectable after Day 7, compared to an untreated control, which revealed a slow conversion of HS-. These preliminary findings indicate a strong autotrophic denitrification with NO3- reduction coupled to aqueous HS- oxidation. In contrast to nitrate, NH4+ concentrations remained stable in all experiments. In the column experiments, the sediment exhibited a substantial NO3- reduction capacity in the early phase but rapidly declined with time. We hypothesize that a dual contribution to denitrification via easily bioavailable electron donors in the groundwater followed by slower denitrification coupled to organic matter in the sediment matrix is responsible for the observed dynamics. Our ongoing experiments, including groundwater and sediments from other, hydrogeologically different aquifers, will dissect the individual redox processes and key microorganisms involved in turnover of prominent nitrate and carbon species in the context of different hydrogeological settings. 

How to cite: Pide, J. L., Holdt, J., Cantarella, V. P., Mellage, A., Cirpka, O., Leven-Pfister, C., Duda, J.-P., Buchner, D., and Griebler, C.: Intrinsic potential and activity of nitrate turnover examined for different hydrogeological aquifer settings, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18568, https://doi.org/10.5194/egusphere-egu24-18568, 2024.

EGU24-18644 | ECS | Posters on site | SSS5.5

Investigating the distribution and residence time of carbon in the rhizosphere by image-based modelling at the pore-scale 

Maximilian Rötzer, Alexander Prechtel, Eva Lehndorff, and Nadja Ray

Mathematical models serve as valuable tools for unraveling the spatial heterogeneity and evolution of soil particles and carbon, particularly on the pore scale, that might be challenging to measure directly. The model we provide facilitates the exploration of interactions in the rhizosphere by the manipulation of different drivers and their parametrization. 

The focus of our study is on the residence time and spatial distribution of carbon originating from particulate organic matter and rhizodeposits. This process of turnover and distribution is influenced by a number of drivers. We provide insights into the role of some of these drivers across different stages of root growth, including carbon occlusion due to aggregation, chemical composition of rhizodeposits, and root morphology. We employ a spatially and temporally explicit mathematical model in which different components such as soil particles, carbon and a dynamic root interact. It is realized within a cellular automaton framework combined with an organic matter turnover model. Through numerical simulations, we track the temporal evolution of mineral soil particles bound by gluing agents. Spatially resolved datasets of soil texture and organic matter distribution are used to implement different soil types comparable with field experiments. Realistic parametrizations are derived from a laboratory experiment conducted in a rhizobox, measuring the carbon-to-nitrogen ratio at distinct temporal states of root growth and varying spatial distances from the biopore.

We compare and quantify the individual impact that soil, root and rhizodeposit characteristics have on the residence time and dispersal of carbon. Using an image-based modeling approach, we gain insight into spatiotemporal patterns and analyze the properties of regions with low turnover, so-called cold spots. 

How to cite: Rötzer, M., Prechtel, A., Lehndorff, E., and Ray, N.: Investigating the distribution and residence time of carbon in the rhizosphere by image-based modelling at the pore-scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18644, https://doi.org/10.5194/egusphere-egu24-18644, 2024.

EGU24-54 | ECS | Orals | SSS5.6

Effects of conservation tillage on soil organic carbon storage, fractions and stability in Black soil 

Yan Zhang, Aizhen Liang, Xiaoping Zhang, Xiujun Li, Edward Gregorich, and Neil McLaughlin

In Northeast China, conventional tillage practices involve removal of crop residue after harvest and prior to moldboard plowing; this has been shown to cause a decline of soil organic carbon (SOC) and degradation of Black soils (Mollisols). Conservation tillage, particularly no tillage (NT), has been suggested to be an effective practice to control soil erosion and increase the SOC content. Hence, we established an experiment (since 2001) to evaluate how a combination of different tillage and cropping systems could improve SOC in black soils. The total SOC storage, SOC fractions (physical and chemical), SOC stability were assessed to evaluate the effects of tillage and cropping system. Our results shows that: 1) different tillage and cropping system combinations had different effects on SOC storage; NT combined with continuous maize had the highest SOC storage among all treatments; 2) The effects of tillage on aggregate size and OC concentration mainly occurred in the surface layer (0–5 cm) while the effect of cropping system on aggregate size and OC concentration mainly occurred at deeper depths; 3) NT increased the recalcitrant carbon pool in surface layer showing the critical need for returning crop residues to maintain long-term SOC storage; 4) SOC mineralization (biological stability) appears to be related to the SOC proportion in the light fraction; 5) More than half of the increase in SOC storage due to NT existed as microbial necromass carbon storage under continuous maize which was higher than maize-soybean rotation. Our study shows that in black soils (Northeast China), NT and appropriate cropping systems can not only halt soil degradation caused by poor management but can induce substantial increases in SOC which is beneficial for SOC long-term sequestration.

How to cite: Zhang, Y., Liang, A., Zhang, X., Li, X., Gregorich, E., and McLaughlin, N.: Effects of conservation tillage on soil organic carbon storage, fractions and stability in Black soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-54, https://doi.org/10.5194/egusphere-egu24-54, 2024.

EGU24-1063 | ECS | Orals | SSS5.6

Investigating the complementarity of thermal and physical soil organic carbon fractions 

Amicie Delahaie and the Freacs team

Evaluating SOC biogeochemical stability is key to better predict the impact of SOC on both climate mitigation and soil health. This evaluation can be conducted using SOC partition schemes that allow us to quantify SOC fractions with different biogeochemical stability. However, most of these schemes are costly or time consuming and cannot be implemented on large sample sets. Two exceptions are  the widely used physical fractionation protocol allowing to separate particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) and the emerging thermal fractionation protocol distinguishing active SOC (Ca; MRT ~30 years) from stable SOC (Cs; stable at a centennial timescale).

Here, we use analyzes conducted on samples from the French soil monitoring network (RMQS) to compare the results of thermal fractionations (Ca/Cs) performed on ca. 2000 samples, and physical fractionations (POC/MAOC) performed on ca. 1000 samples. Our results show that MAOC and Cs from one side and POC and Ca from the other side have different sizes. The most biogeochemically stable fractions (Cs and MAOC) are mostly influenced by soil characteristics whereas land cover and climate influence more substantially POC and Ca. However, the more stable fractions provided by both fractionation schemes (respectively the more labile fractions) do not have the exact same environmental drivers. Our results therefore suggest that both fractionation scheme gives complementary results. The relative contribution of these fractionation schemes to the evaluation of soil functions and OC stock evolution remains to be evaluated on soil monitoring networks and constitutes a promising research avenue.

How to cite: Delahaie, A. and the Freacs team: Investigating the complementarity of thermal and physical soil organic carbon fractions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1063, https://doi.org/10.5194/egusphere-egu24-1063, 2024.

EGU24-1422 | ECS | Orals | SSS5.6 | Highlight

Long-Term Phosphorus Fertilisation: Effects on Nitrogen and Carbon Cycle Dynamics and Greenhouse Gas Fluxes in European Agricultural Soils  

Lea Dannenberg, Christian Eckhardt, Christoph Müller, and Kristina Kleineidam

Phosphorus (P) is a crucial nutrient for plant growth, its limitation reduces plant and microbial biomass, affecting soil organic carbon (SOC) sequestration. Changes in soil P content may influence microbial composition, shaping pathways in the carbon (C) and nitrogen (N) cycles and impacting greenhouse gas emissions. In this lab incubation experiment we investigate the impact of different P fertilisation levels in three European long-term experiments (LTE) on N and C transformation processes and greenhouse gas fluxes in agricultural soils using stable isotope techniques (15N and 13C). The study is part of the EJP SOIL project “ICONICA” (Impact of long-term P additions on C sequestration and N cycling in agricultural soils).

The soil samples derived from Johnstown Castle, JC (grassland soil, Ireland), Lanna Skara, LS (arable soil, Sweden) and Jyndevad, JY (arable soil, Denmark). Two P levels were examined from each LTE: low P (0 kg P/ha and year) and high P additions (different P application rates among LTEs). The soils were mixed with 13C- and 13C15N- labelled maize biomass, respectively, and received ammonium nitrate (NH4NO3) in the 13C treatment as 15NH4NO3 and NH415NO3, respectively, and unlabelled NH4NO3 in the 13C15N treatment. Soil and gas samples were taken 0, 1, 3, 7 and 10 days after addition of NH4NO3 and were analysed for (15)NH4+-N, (15)NO3--N, organic (15)N, organic (13)C contents as well as for nitrous oxide ((15)N2O), carbon dioxide ((13)CO2), and methane (CH4) fluxes.

Preliminary findings display clear differences among the three LTEs as well as the two P levels. Regarding the impact of P fertilisation history: JC soil exhibited elevated CO2 emissions at high P compared to low P level. Significantly, high P levels showed higher CH4 uptake rates in JC and JY soils compared to the respective low P levels. JY had the highest N2O emissions, while JC had the lowest. JC had higher NH4-N values than LS. The highest NO3-N values were measured in JC, and the lowest in JY. In JC, higher NO3-N values were measured in high P compared to low P.

The results so far underscore the complex interactions within the carbon-nitrogen-phosphorus cycles under varying P inputs. Further analyses and interpretations are in progress.

How to cite: Dannenberg, L., Eckhardt, C., Müller, C., and Kleineidam, K.: Long-Term Phosphorus Fertilisation: Effects on Nitrogen and Carbon Cycle Dynamics and Greenhouse Gas Fluxes in European Agricultural Soils , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1422, https://doi.org/10.5194/egusphere-egu24-1422, 2024.

EGU24-1464 | ECS | Posters on site | SSS5.6

Less than 4% of dryland areas will desertify due to climate change.   

Xinyue zhang, Jason Evans, and Arden Burrell

Drylands with low biological productivity are more fragile compared with non-drylands, making many human activities within them sensitive to long-term trends. Any negative trend in dryland condition is considered desertification. The Aridity Index, widely used to define drylands, indicates increasing aridity in the drylands over several decades, which has been linked to increasing occurrence of desertification. Future projections show continued increases in aridity due to climate change, suggesting that drylands will expand. However, satellite observations show a general greening of the drylands. Given the past inconsistency between the Aridity Index changes and observed vegetation changes, future evolution of vegetation productivity within the drylands remains an open question. Here we use a data driven approach to estimate the state of vegetation in the drylands and project their future changes. Results shows most of the global drylands are projected to see an increase in vegetation productivity due to climate change through 2050. The general increases are in-part due to CO2 fertilization effects and are in-line with recent trends and continue the past inconsistency with changes in the Aridity Index. Climate change negates the changes in at most 4% of global drylands to produce desertification. These regions include parts of north-east Brazil, Namibia, western Sahel, Horn of Africa and central Asia.

How to cite: zhang, X., Evans, J., and Burrell, A.: Less than 4% of dryland areas will desertify due to climate change.  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1464, https://doi.org/10.5194/egusphere-egu24-1464, 2024.

EGU24-2093 | ECS | Orals | SSS5.6

Development CNtrace tool 

Anne Jansen-Willems, Kristina Kleineidam, Tim Clough, Lea Dannenberg, and Christoph Müller

The Ntrace tool was developed as a flexible 15N analysis tool to determine gross nitrogen (N) transformations. Since the development of the tool, it has been applied to many ecosystems world-wide as documented in more than 190 peer-reviewed publications. Over time, the tool has evolved to become much more flexible including different pools and determining more transformation rates. Up until now, the focus has been on the N cycle. However, the N and carbon (C) cycle are closely connected. Considering both cycles concomitantly provides a more comprehensive understanding of how elements move through the system. Thus, the next step in the development of the Ntrace tool includes connecting the N and C pools (CNtrace) in order to simultaneously quantify gross N and C transformations based on the observed 15N and 13C dynamics. Data from specifically designed experiments, using either labelled organic matter or C4 plants in a C3 soil, with the addition of differentially 15N labelled mineral fertilizer will be used for the development of the CNtrace tool. The theoretical background and the various development steps will be presented.

How to cite: Jansen-Willems, A., Kleineidam, K., Clough, T., Dannenberg, L., and Müller, C.: Development CNtrace tool, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2093, https://doi.org/10.5194/egusphere-egu24-2093, 2024.

EGU24-2759 | ECS | Orals | SSS5.6

Effects of aridification on soil total carbon pools in China's drylands 

Zhuobing Ren, Changjia Li, Bojie Fu, Shuai Wang, and Lindsay C. Stringer

Drylands are important carbon pools and are highly vulnerable to climate change, particularly in the context of increasing aridity. However, there has been limited research on the effects of aridification on soil total carbon including soil organic carbon and soil inorganic carbon, which hinders comprehensive understanding and projection of soil carbon dynamics in drylands. To determine the response of soil total carbon to aridification, and to understand how aridification drives soil total carbon variation along the aridity gradient through different ecosystem attributes, we measured soil organic carbon, inorganic carbon and total carbon across a ~4000 km aridity gradient in the drylands of northern China. Distribution patterns of organic carbon, inorganic carbon, and total carbon at different sites along the aridity gradient were analyzed. Results showed that soil organic carbon and inorganic carbon had a complementary relationship, that is, an increase in soil inorganic carbon positively compensated for the decrease in organic carbon in semiarid to hyperarid regions. Soil total carbon exhibited a nonlinear change with increasing aridity, and the effect of aridity on total carbon shifted from negative to positive at an aridity level of 0.71. In less arid regions, aridification leads to a decrease in total carbon, mainly through a decrease in organic carbon, whereas in more arid regions, aridification promotes an increase in inorganic carbon and thus an increase in total carbon. Our study highlights the importance of soil inorganic carbon to total carbon and the different effects of aridity on soil carbon pools in drylands. Soil total carbon needs to be considered when developing measures to conserve the terrestrial carbon sink.

How to cite: Ren, Z., Li, C., Fu, B., Wang, S., and Stringer, L. C.: Effects of aridification on soil total carbon pools in China's drylands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2759, https://doi.org/10.5194/egusphere-egu24-2759, 2024.

EGU24-2926 | ECS | Orals | SSS5.6

Inorganic carbon: an overlooked pool in global soil carbon research   

Sajjad Raza, Annie Irshad, Andrew Margenot, Kazem Zamanian, Sami Ullah, Irina Kurganova, Xiaoning Zhao, and Yakov Kuzyakov

Soils are one of the major players in the global carbon (C) cycle and climate change by functioning as a sink or a source of atmospheric carbon dioxide (CO2). The largest terrestrial C reservoir in soils comprises two main pools: organic (SOC) and inorganic C (SIC), each having distinct fates and functions but with a large disparity in global research attention. This study quantified global soil C research trends and the proportional focus on SOC and SIC pools based on a bibliometric analysis. Research on soil C pools started in 1905 and has produced over 42,000 publications (> 1.6 million citations). Although the global C stocks down to 2 m depth are nearly the same for SOC and SIC, the research has dominantly examined SOC (> 96% of publications and citations) with a minimal share on SIC (< 4%). Approximately 39% of the soil C research was focused on climate change. Despite poor coverage and publications, the climate change-related research impact (citations per document) of SIC studies was higher than that of SOC. Machine learning, biochar, soil properties, and climate change were the recent top trend topics for SOC research (2018-2022), whereas soil acidification, organic C, climate change, and Holocene were recent trends for SIC. SOC research was contributed by 150 countries compared to 85 for SIC. As assessed by publications, soil C research was mainly concentrated in a few countries, with only 10 countries accounting for 75% of the research. China and the USA were the major producers (44%), collaborators (36%), and funders of soil C research. SIC is a long-lived soil C pool with a turnover rate of more than 1000 years in natural ecosystems but intensive agricultural practices have accelerated SIC losses, making SIC an important player in global C cycle and climate change. The lack of attention and investment towards SIC research could jeopardize the ongoing efforts to mitigate climate change impacts to meet the 1.5-2.0 oC targets under the Paris Climate Agreement of 2015. This study calls for expanding the research focus on SIC and including SIC fluxes in C budgets and models, without which the representation of the global C cycle is incomplete.

How to cite: Raza, S., Irshad, A., Margenot, A., Zamanian, K., Ullah, S., Kurganova, I., Zhao, X., and Kuzyakov, Y.: Inorganic carbon: an overlooked pool in global soil carbon research  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2926, https://doi.org/10.5194/egusphere-egu24-2926, 2024.

Post mining ecosystems are severally degraded.  This is particularly true for soils which are either excavated or buried and replace by overburden which differ remarkably, from normal soils. Despite these severe degradation, post mining soils of numerals opportunities: they are valuable secondary habitat for rare and endangered species, and soils developing in these areas are able to sequester carbon in much higher rate than soils in surrounding landscape.. Here we compare effect of reclaimed and unreclaimed sites on provisioning ecosystem services in Sokolov (Czech Republic) and on climatic gradient across USA. In suitable substrates, the succession is driven mainly by site topography. In sites which were leveled grassy vegetation develops. In sites where original wave like topography was preserved the ecosystem develops towards shrubs and forest. Reclaimed and unrecaimed forest sites have similar development of canopy cover,   stems number gradually decreased with age in reclaimed sites and increased in succession, in 20 year both reaching the same density.  Tree biomass was higher in young reclaimed sites, in sites 30 years old or older tree biomass in succession sites was comparable or higher than in reclaimed sites.  Initial rate of soil carbon storage in reclaimed sites namely those planted by alder was faster than in succession sites but it decrease with plot age.  In unclaimed sites, the rate of C storage increase and peaked in site 20-30 years old. Amount of C stored in unreclaimed sites c 50 years old is comparable to alder plantations of the same age.  Alder plantation of intermediate age store more water than unreclaimed sites but water budget is similar due to higher water demand of alder.  In leveled sites where grassland establish, reclaimed sites are slightly higher in all studied parameters. In conclusion, development of key ecosystem process is fasted in reclaimed sites but latter on difference disappear. The reasons are, soil   leveling, promote soil compaction, which slows root growth. Focus on achieving a close cannopy often lead to dense three stand which limit a light availability for trees. This is even supported by leveling and homogenous pattern of planting which lead to one layer cannopy, compare to multi-layer cannopy in unreclaimed sites. Also planting N fixers, my contribute, to this slow down, as nitrogen fixing plant often fixed nitrogen even in conditions when nitrogen is already plentiful in soil. This cause additional energy expense for the trees.

Comparison of benefits of reclamation and spontaneous ecosystem development vary depending on climatic conditions and target ecosystem. For example, in dry cold conditions when target is grassy vegetation such as short grass prairie in Wyoming (USA), to reclamation practices show often much better results than unassisted ecosystem development. In contrary in wet warm climate, when broadleaf forest is a target (e.g. in Eastern USA), unassisted ecosystem development often shows better results in many parameters namely in long run.  These results show that we should try to better understood naturel processes of ecosystem development so we can implement them in improvement of reclamation technologies.

 

 

How to cite: Bartuška, M. and Frouz, J.: Natural regeneration as restoration strategy to restore functional soils and ecosystems in post mining sites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3229, https://doi.org/10.5194/egusphere-egu24-3229, 2024.

Simple conceptual overview how peculiarities of food production and food supply chain affect land degradation.

Most of the land suitable for agriculture is located in the temperate zone, while the yields of comparable crops in tropical countries (countries of the global south) are almost half compared to developed countries in the temperate zone. In addition to greater soil fertility, the more advanced technological base of economically developed countries. Developed counties the increase their production mainly through its intensification, i.e. greater production on the same area and greater meat, milk or egg production per one livestock specimen. This leads to the concentration of production in suitable conditions, the homogenization of the landscape, reduction of grazing and other extensive form of land use and other negative effects of agricultural intensification on ecosystems. On the other hand, in the countries of the global south, agricultural production is increasing mainly through increasing the production areas, which results in endangering the remnants of the original ecosystems. Number of farmers is decreasing yet they feed larger amount of food consumers. This increasing the efficiency of human work is connected with the transfer of part of the work to the work of animals and later machines which allow one farmer to cultivate larger area of land, and further to the intensification of agricultural production, the use of fertilizers, pesticides, and other substances, so-called additional energy is needed to obtain them. As the intensity of agriculture and the ability of one farmer to feed more people increases, the total amount of energy required to achieve production also increases, not only because total output increases, but also because the amount of additional energy required per unit of output increases. As the amount of additional energy increase recycling of biomass (and energy) inside agriculture system decrease. Along with this, the negative impacts of agricultural production on ecosystems are increasing. These negative impacts are usually greater in the less fertile soils of the global south than in the more fertile soils of developed countries.  Pressure of consumers increase not only due to population increase, but also due to detachment of people from food production, which cause that consumers perceive food mainly by its cost. Food supply chain become driven by retailers, which increase pressure on price, and thus pressure on farmers to optimize production cost often on expense of more intensive soil and land use which may lead to land degradation. Many retailers now use environmental standards which are well suited to control for extensification (such as zero deforestation) but tackling of agriculture intensification is rare.

How to cite: Frouzova, J. and Frouz, J.: Simple conceptual overview how peculiarities of food production and food supply chain affect land degradation., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3233, https://doi.org/10.5194/egusphere-egu24-3233, 2024.

Improved tillage practice plays a positive role in restoring degraded cropland, maintaining crop productivity, and mitigating climate change, which has been proposed as a sustainable agricultural technology. Based on a long-term experiment in black soil area of Northeast China, effects of different tillage practices on soil organic carbon (SOC) and nutrient content were explored, and ecological and economic benefits were also evaluated. Three tillage practices were included: conventional tillage with complete removal of residue (CT), moldboard plowing with residue return (MP) and no-tillage with residue return (NT). As the trial period increased, the SOC content of the CK decreased in the 0-20 cm soil layer, while the total nitrogen (TN) content remained. Residue return treatments (MP and NT) increased SOC and TN content. The SOC and TN were uniformly distributed in the 0-20 cm soil layer of MP, whereas the SOC and TN increased significantly in the 0-5 cm soil layer of NT, especially during the 5-8 years of the experiment. The total phosphorus (TP) and total potassium (TK) contents of all treatments slowly increased over time, and there was no significant difference among treatments. Compared with CT, NT could reduce N2O emissions and absorb more CH4, whereas MP significantly increased CO2 emissions from soil. Moreover, NT led to both the lowest GHG emissions from soil (GWPGHG) and agricultural inputs (AIGHG), thus reduced approximately 40% carbon footprint (CF) compared to CT. However, no significant difference in maize yield and net ecosystem ecological benefit (NEEB) were observed among three tillage practices, although MP and NT showed lower investments during maize production than CK. In conclusion, NT could not only enhance the SOC and nutrient content but also minimize CF while ensuring economic benefit from a long-term perspective. Long-term NT can be implemented in Northeast China and similar agro-eco-regions around the world.

How to cite: Zhang, Y. and Liang, A.: Effects of long-term residue return on nutrient content, ecological and economic benefits of black soil in Northeast China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6534, https://doi.org/10.5194/egusphere-egu24-6534, 2024.

EGU24-6933 | Posters on site | SSS5.6

Application of the Ntrace tool to investigate long-term P fertilizer effects on gross N transformations in a pasture soil 

Tim Clough, Anne Jansen-Willems, Kristina Kleineidam, Lea Dannenberg, and Christoph Müller

The Ntrace tool uses soil 15N analysis of soil N pool dynamics to establish soil gross nitrogen (N) transformations. An understanding of what initiates and controls soil N transformation dynamics is critical when considering the environmental impacts (e.g. nitrate leaching and nitrous oxide emissions) and fate of N in pasture soils. Phosphorus (P) is an essential nutrient required by soil microbes that facilitate both soil N and soil organic matter transformations. A laboratory mesocosm study was performed to examine the effect of long-term superphosphate use on soil gross N and soil organic matter transformations. Sheep grazed pasture soils, undisturbed for 71 years, receiving either nil fertilizer (control) or 188 kg ha-1 year-1 of single superphosphate (17 kg P ha-1 yr-1) were collected at a depth of 0 – 7.5 cm. Soils were sieved (4 mm) and placed in kilner jars, whereupon they received treatments that consisted of: 15NH414NO3 + natural abundance 13C perennial ryegrass (Lolium perenne) root material; 14NH415NO3 + natural abundance 13C perennial ryegrass root material; or 14NH414NO3 + 13C enriched ground perennial ryegrass root material. Over 7 days measurements included soil inorganic-N concentration and 15N enrichments, nitrous oxide emissions, microbial biomass, and soil organic C concentrations. Data and initial conclusions from this experiment will be presented with respect to the long-term P fertilizer effects on soil gross N and soil organic matter transformations.

How to cite: Clough, T., Jansen-Willems, A., Kleineidam, K., Dannenberg, L., and Müller, C.: Application of the Ntrace tool to investigate long-term P fertilizer effects on gross N transformations in a pasture soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6933, https://doi.org/10.5194/egusphere-egu24-6933, 2024.

EGU24-7661 | ECS | Orals | SSS5.6

Soil organic carbon dynamics after land-use change – combining process-based modelling with machine learning 

Daria Seitz, Rene Dechow, David Emde, Florian Schneider, and Axel Don

Land-use changes affect soil organic carbon (SOC) stocks over decades. However, IPCC default for greenhouse gas emissions reporting suggests a simple linear SOC stock change over 20 years only. Using process-based modelling approaches such as RothC to describe SOC dynamics after land-use change requires model validation. However, there are only few long-term field experiments where SOC stocks have been observed long enough to get sufficient data for such a model validation. This lack of data makes validating models for large-scale use challenging.

Based on empirical data from over 3000 sites from the German Agricultural Soil Inventory we selected 204 sites with land-use change history within the last 60 years and created an artificial data-set using a reciprocal modeling approach. This approach utilizes machine learning models trained on sites under permanent land use to predict SOC stocks for similar sites where the land use had been changed. In addition, we extracted further empirical data from over 30 sites with land-use change in the temperate zone from a comprehensive meta-analysis.

These two datasets were used to test the ability of the well-known SOC model RothC to simulate land-use change effects on SOC stocks. In these tests, we use the observed or predicted SOC stocks assumed at equilibrium to model the carbon input under permanent land use and corresponding SOC dynamics after land-use change. These modelled SOC dynamics are then compared with observed SOC stocks after land-use change.

We will discuss opportunities and challenges of using process-based models to describe SOC dynamics after land-use change on regional to national scale.

 

How to cite: Seitz, D., Dechow, R., Emde, D., Schneider, F., and Don, A.: Soil organic carbon dynamics after land-use change – combining process-based modelling with machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7661, https://doi.org/10.5194/egusphere-egu24-7661, 2024.

EGU24-7763 | Orals | SSS5.6

Possible interactions of hazardous elements with pharmaceuticals in soils of a Mediterranean wetland (L’Albufera, Valencia, Spain) 

Vicente Andreu, Eugenia Gimeno-Garcia, Danielle Sadutto, and Yolanda Picó

There is scarce information about toxic effects, environmental dynamics and even toxic levels or regulations, mainly in soils, of several elements widely used in agriculture and industry. These so called elements “of emerging concern” have not been studied, mainly regarding their environmental effects or relationships. By the other hand, tons of pharmaceuticals are liberated by effluents of the wastewater treatment plants to the environment and agricultural fields daily. As study case, we have selected an important area in Spain that is affected by high anthropogenic pressures.

The target area of study the alluvial plain between the rivers Turia and Jucar (Valencia, SPAIN), with an extension of 486 km2, which is characterized by its dense network of channels and ravines for irrigation one of the most productive agricultural areas of Spain. This area includes a wide zone of rice farming and a Natural Park (L’Albufera). In this study area, 33 sampling zones were selected covering the different water sources and agricultural types, to monitor the distribution of the levels of 15 hazardous metals.

Total concentrations of the selected metals (Al, As, B, Be, Bi, Co, Fe, Li, Mo, Se, Rb, Sr, Ti, Tl and V) were determined. Standard analytical methods were used to measure soil physical and chemical properties. Total content of the twelve heavy metals, in soil samples, were extracted by microwave acid digestion and determined by ICP-OES. In the same zones, 32 pharmaceuticals were also studied. soil samples were extracted by pressurized liquid extraction (SPE). and determined by liquid-chromatography tandem mass spectrometry (LC-MS/MS).

Maximum average values were determined for Ti, Sr and Rb with 466.36, 263.16 and 63.62 mg/kg, respectively. Highest values for B, Li and Tl were 76.05, 70.91 and 56.37 mg/kg, respectively. The Northern part of the Albufera lake, devoted to rice farming, concentrated the highest values of almost all the selected elements. From the 32 studied pharmaceuticals, 29 were detected being the most frequents Bisphenol A, Caffeine and Tramadol. Maximum values were observed for Alprazolam (67.28 ng/g), Ibuprofen (76.11 ng/g) and Lorazepam (62.02 ng/g).

The interactions between metals and pharmaceuticals, and from both with soil characteristics and the influence of environmental factors were also studied.

More research is needed to stablish their toxic levels and effects, or even their average concentrations in soils of these elements, very scarcely studied in the majority of them.

Acknowledgements

This work has been supported by the Generalitat Valenciana (Regional Autonomous Government) through the project CIPROM/2021/032.

How to cite: Andreu, V., Gimeno-Garcia, E., Sadutto, D., and Picó, Y.: Possible interactions of hazardous elements with pharmaceuticals in soils of a Mediterranean wetland (L’Albufera, Valencia, Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7763, https://doi.org/10.5194/egusphere-egu24-7763, 2024.

EGU24-7793 | Orals | SSS5.6

Nutrients and carbon losses due to wind erosion in Sahelian Senegal 

Caroline Pierre, Jean Louis Rajot, Pierre-Marie Bonneval, Paul-Alain Raynal, Abdourahmane Tall, Issa Faye, Dioumacor Fall, and Alfred Tine

Land degradation appears today as a major issue for feeding humans, whose population on Earth is still increasing. Such issues are particularly acute in semi-arid regions like the Sahel, where, in addition, soils are already poor in nutrients and carbon. Wind erosion is one of the processes likely to cause soil depletion of nutrients and carbon in this region, thus potentially leading to land degradation. However, there is little scientific literature providing quantitative estimates of soil losses of nutrients and carbon through the windblown sediments, particularly for the Sahel.

We monitored the horizontal flux of windblown sediments (collected every 2 weeks in MWAC sand-traps) for the main land use types of Western Sahel in the Peanut Basin of Senegal: a field (bare, then cropped with groundnut) (2020-2021), 4 fallows (2022/2023), and 4 millet fields (2023/2024) to characterize differences in windblown sediment fluxes due to land management (e.g. management of crop residues, grazing pressure, …). Each plot was about 1 ha, and had 5 masts of 5 MWAC each, from 5 cm to 80 cm above ground level. During these experiments, we also monitored vegetation characteristics (every week) and meteorological variables (at 5-minutes resolution).

We then carried out analyses on the windblown sediments collected in the sand traps for the bare/groundnut field (the amounts of sediments collected in the fallows were too low to perform such analyses, and the erosive period, which extends from January to April in Western Senegal, just started in early 2024 for the millet fields experiment).

Our first results show that the horizontal flux of windblown sediments is much larger for a bare/groundnut field (around 40 t/ha/year) than for fallows (0.03 to 0.80 t/ha/year). The results also suggest that differences in land management among fallows (e.g. age, woody cover) may have an impact on this horizontal flux.

Additionally, the orders of magnitude of the organic C, total N and available (Olsen) P concentrations of the horizontal (saltation) flux from the bare/groundnut field are respectively approximately 0.22%, 0.02%, and 8 ppm, thus larger than the concentrations of the topsoil, that are respectively 0.15 %, 0.01 % and 7 ppm. These values compare well with those existing in the literature (e.g. for Niger), and confirm an enrichment of the horizontal flux (by a factor of 1.1 to 1.8) in soil carbon and nutrients compared to the topsoil. A rough estimate of organic C losses from the monitored field of 1 ha would be about 80 kg/year, and 8 kg/ha and 0.32 kg/ha for N and available P, respectively.

To better characterize the composition of windblown sediments, we also plan to carry out microbiological analyzes to determine the composition of the microbial communities (bacteria and fungi) they contain. Indeed, these microbial communities play a role in the biogeochemical cycle of nutrients and in the storage of carbon in the soil, thus potentially impacting their fertility.

We thank the IMAGO/LAMA analytical laboratory of Dakar for the analyses of the composition of the sediment samples.

How to cite: Pierre, C., Rajot, J. L., Bonneval, P.-M., Raynal, P.-A., Tall, A., Faye, I., Fall, D., and Tine, A.: Nutrients and carbon losses due to wind erosion in Sahelian Senegal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7793, https://doi.org/10.5194/egusphere-egu24-7793, 2024.

We studied the effect of grazing on carbon sequestration in semi-natural grasslands.  The study was conducted on three farms with known history of land use in W Iceland. On each farm, we located an intensively (IG) and an extensively (EG) grazed site, which both had been constantly grazed for centuries, and a parallel site were grazing had been excluded (NG) for over 50 years. We measured net ecosystem exchange (NEE), ecosystem respiration and normalized difference vegetation index (NDVI) on a regular basis over the growing season. Samples were taken from 60 cm deep soil profiles for analysis of soil organic carbon (SOC). The grazed sites showed significantly more negative NEE than the NG sites, indicating more carbon dioxide uptake on the grazed sites compared to the NG sites. NDVI was also significantly higher on the grazed sites. On all farms, the total SOC content was higher in the grazed sites than in the parallel NG sites. The study indicates that cessation of grazing decreases productivity and carbon dioxide uptake in a semi-natural grassland in Iceland, as well as SOC content in the soil. Historically, all the NG sites in the study had the same grazing history as the continuously grazed sites until grazing exclusion. The measured lower SOC on the NG sites seems to indicate that, without grazing, SOC is lost with time and/or grazing is needed to maintain SOC in these grasslands.

How to cite: Thorhallsdottir, A. G. and Gudmundsson, J.: Carbon dioxide fluxes and soil carbon storage in relation to long-term grazing and grazing exclusion in Icelandic semi-natural grasslands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8473, https://doi.org/10.5194/egusphere-egu24-8473, 2024.

EGU24-9123 | Posters on site | SSS5.6

The role of (in)organic carbon removal as a pretreatment in the 13C isotope composition of various soils 

Gergely Jakab, Tibor Filep, Tiphaine Chevallier, Zoltán Szalai, and Dóra Zachary

Soil carbon content is a crucial property in fertility and soil health. Carbon occurs in the soil in organic and inorganic forms. Soil organic carbon enters the soil mainly as plant residues and root extracts from the biosphere, whereas the primary source of inorganic carbon is the parent material. Both organic and inorganic carbon forms are affected by the current environmental and artificial conditions and, consequently, change in space and time. In this dynamic system, biogen or pedogen effects can reform carbonates and change organic matter composition. Both carbon forms are the focus of research in the soil however, the interaction between them is less understood. Inorganic carbon forms play an essential role in soil organic matter stabilization and, therefore, in maintaining soil functions. The present study aimed to investigate the organic-inorganic carbon interaction processes in various soil horizons. As a proxy, the stable isotope δ13C values were measured separately in the organic and inorganic pools and the bulk soil. Altogether, 55 soil samples were taken from top and subsoils under various land uses and texture classes. Beyond the measurement of the bulk soils, one aliquot was heated to 550°C for six hours to eliminate the organic carbon content, whereas another one was treated with HCl to remove the carbonates. All samples were measured using a Thermo Scientific FLASH 2000 HT elemental analyzer mass spectrometer, identifying δ13C composition. The sum of organic and inorganic carbon was higher than the total carbon content (R2=0.94), suggesting that at least one carbon removal pretreatment was incomplete. Some low inorganic carbon content (<0.5%) revealed a deficient δ13C value (-15 – -30 ‰), indicating organic carbon residue presence. However, other slightly carbonated samples parallel with higher inorganic carbon content ones are in the range of pedogenic carbonates (0 – -10 ‰). The reason for the incomplete organic carbon removal is probably related to the organic-mineral complexes; however, further investigations are needed for a more convincing result. This work was supported by the National Research, Development and Innovation Fund of Hungary [project no. 2019-2.14-ERA-NET-2022-00037 and FK 142936]. Project no. 2019-2.14-ERA-NET-2022-00037 has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the ERA-NET COFUND/EJP COFUND funding scheme with co-funding from the European Union Horizon 2020 research and innovation programme.

How to cite: Jakab, G., Filep, T., Chevallier, T., Szalai, Z., and Zachary, D.: The role of (in)organic carbon removal as a pretreatment in the 13C isotope composition of various soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9123, https://doi.org/10.5194/egusphere-egu24-9123, 2024.

EGU24-11107 | ECS | Posters on site | SSS5.6

A new machine-learning model to partition soil organic carbon into its centennially stable and active fractions based on Rock-Eval(r) thermal analysis 

Marija Stojanova, Pierre Barré, Hugues Clivot, Lauric Cécillon, François Baudin, Thomas Kätterer, Bent T. Christensen, Claire Chenu, Ines Merbach, Adrián Andriulo, Sabine Houot, and Fabien Ferchaud

The quantification of soil organic carbon (SOC) biogeochemical stability is important for assessing soil health and its capacity to store carbon. Models simulating SOC stock evolution divide SOC into different kinetic pools with contrasting residence times. The initialization of compartment sizes is a major source of uncertainty for SOC simulations. In a previous study, Cécillon et al. (2021) developed a machine-learning model (PARTYsoc v2) that uses Rock-Eval(r) thermal analysis results as input variables to quantify the proportion of centennially stable and active SOC fractions using samples from long term bare fallow sites. The outputs of PARTYsoc v2 have been shown to be particularly effective for initializing the AMG model, enabling very accurate simulations of SOC stock evolutions for a dozen French sites (Kanari et al., 2022). The objective of the present work is to build a new version of PARTYsoc, validated on a larger sample set, and extend the usefulness of the AMG model initialized with PARTYsoc to different parts of the world.

To do so, we have first identified sites with known crop yields and SOC stock evolutions and archived samples available for Rock-Eval(r) characterization. We then determined, for each site, the stable SOC stock value leading to the best simulation accuracy of SOC stock evolution with the AMG model. This optimal stable SOC stock allowed us to quantify the stable SOC proportion for all samples from the selected sites. Finally, we developed PARTYsoc v3 using Rock-Eval(r) measurements as input variables to predict stable SOC proportions sensu AMG model.

PARTYsoc v3 is significantly different from PARTYsoc v2. In the v3, the target variable, i.e., the centennially stable SOC proportion, is determined to be optimal for the AMG model whereas in the v2 it was calculated from SOC declines at bare fallow sites. Moreover, the current v3 model uses Support Vector Machine (SVM) regression coupled with a Beta Regression instead of Random Forest. This combination of machine-learning models allows for a non-linear relationship between the target and the features, and predictions are always bounded in the [0, 1] interval. The data set has also been extended to use a larger number of sites (6 sites in the v2, and 12 sites in the v3), including both bare fallows and other types of long-term experiments.

The features (Rock-Eval(r) features) are selected by first removing highly-correlated features (Spearman correlation > 0.9) and then ranking them based on their predictive importance when randomly permuted. This procedure allows us to decrease the effects of overfitting the training data. The final model uses 7 Rock-Eval(r) features (18 for the v2). We obtain satisfactory performance in both internal validation (R2=0.82, RMSE=0.07), as well as Leave-One-Site-Out (LOSO) validation (R2=0.76, RMSE=0.09).

The proposed model builds upon and significantly improves the work laid out by PARTYsoc v2. Currently, we are working on further extending the data set as well as stabilizing the processes of feature selection and model parameters.

How to cite: Stojanova, M., Barré, P., Clivot, H., Cécillon, L., Baudin, F., Kätterer, T., T. Christensen, B., Chenu, C., Merbach, I., Andriulo, A., Houot, S., and Ferchaud, F.: A new machine-learning model to partition soil organic carbon into its centennially stable and active fractions based on Rock-Eval(r) thermal analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11107, https://doi.org/10.5194/egusphere-egu24-11107, 2024.

EGU24-12395 | Posters on site | SSS5.6 | Highlight

Long-term P fertilizer effects on pasture soil nitrous oxide and carbon dioxide emissions 

Tim Clough, Naomi Wells, Parag Bhople, Karl Richards, and Giulia Bondi

Grazed pasture ecosystems are key contributors to anthropogenic nitrous oxide (N2O) emissions. Within the grazed pasture, it is the deposition of ruminant urine, from the grazing animal, that creates the hot-spot for N2O emissions. Grazed pastures also receive phosphorus (P) fertilizer to sustain plant nutrient needs. This in turn increases the soil microbial biomass pool and promotes dry matter production: this affects soil moisture dynamics and plant N uptake. How long-term P fertilizer affects N2O emissions from pasture soils in situ is poorly understood. To address this an in situ study was performed on the Winchmore long-term fertilizer trial, in New Zealand. This has run for 71 years and the pasture has not been disturbed over this time. The trial consists of replicated (n = 4) field plots (0.09 ha) receiving either 0, 17, 23, or 34 kg P ha-1 yr-1 as single superphosphate. These field plots are rotationally grazed by sheep, with stocking rate adjusted according to feed on offer. Headspace chamber bases were installed in each field plot and synthetic ruminant urine or distilled water (control) were applied. Static chambers were placed on the chamber bases during gas flux measurement. Gas measurements were taken over a 76-day period to determine N2O and CO2 fluxes. Soil inorganic-N concentrations (0 – 7.5 cm) were also followed over time, along with soil sampling for determining soil chemical characteristics. Data from this study and their interpretation will be presented to assess the effect of long-term P fertilizer on grazed pasture N2O and CO2 fluxes.

How to cite: Clough, T., Wells, N., Bhople, P., Richards, K., and Bondi, G.: Long-term P fertilizer effects on pasture soil nitrous oxide and carbon dioxide emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12395, https://doi.org/10.5194/egusphere-egu24-12395, 2024.

EGU24-13467 | Posters on site | SSS5.6

Organic Vineyard Fertilization: Soil Carbon and Nitrogen in Southern Brazil 

Tadeu L. Tiecher, Allan Augusto Kokkonen, Daniéle Gonçalves Papalia, Luana Paula Garlet, Vanessa Ferraz Costa, Samuel Bolívar de Mello Schemer, Arthur Gonçalves Gulartt, Barbara Clasen, and Gustavo Brunetto

In recent years, vineyard areas in organic production system have been increasing significatively, in both develop and developing nations. This trend aligns with the growing concerns of people and governments. They are increasingly worried about health issues and the environmental impact of conventional agriculture and horticulture. In contrast, agroecology and organic fertilization have the potential to offer safe products and promote carbon (C) sequestration in the soil. The latter benefit is also a crucial strategy to mitigate the climate effects of greenhouse gas emissions. This aligns with the UN's guidelines for carbon-neutral production systems However, in vineyard agroecosystems, there is limited technical information about the impact of organic fertilizers and plant CO2 fixation on carbon levels. This is especially true in subtropical climates. Therefore, this research aimed to evaluate how different fertilization systems affect soil organic carbon (SOC) and soil organic nitrogen (SON). An experiment was set up in a commercial organic vineyard with two different cultivars: ‘Isabella’ (Vitis labrusca x V. vinifera) and ‘Chardonnay’ (V. vinifera), in Veranópolis (Cfa climate), in Southern Brazil. The soil in the experiment was classified as Cambisol (WRB). Since 2020, the following fertilization systems have been applied yearly: no fertilization (T), grape pomace vermicompost (GPV), grape pomace compost (GPC), GPV plus mineral fertilizers (GPV+MF), GPC plus mineral fertilizers (GPC+MF), and mineral fertilizers only (MF). The organic fertilizers were applied in the dose of 40 kg of N ha-1, on the surface beneath grapevine canopies. The mineral fertilizers consisted of natural phosphate and potassium sulphate, in the doses of 160 and 100 kg ha-1 of P2O5 and K2O, respectively. In 2023, soil samples were collected from 0 to 5, 5 to 10, 10 to 20 and 20 to 40 cm layers, at bud burst (August), and analyzed for SOC and SON, via combustion followed by gas chromatography. No fertilization system increased SOC or SON in layers up until 20 cm deep after three years of treatment. In 20 to 40 cm layer, there was variability among treatments; however, that is probably main to natural variation. Mean C:N ratio of soil organic matter was 12,0. In light of this, we suggest the evaluation of SOC and SON after a longer period of treatment application, since their low increase in humid subtropical regions, which presents hot and wet summers.

How to cite: Tiecher, T. L., Kokkonen, A. A., Papalia, D. G., Garlet, L. P., Ferraz Costa, V., Bolívar de Mello Schemer, S., Gonçalves Gulartt, A., Clasen, B., and Brunetto, G.: Organic Vineyard Fertilization: Soil Carbon and Nitrogen in Southern Brazil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13467, https://doi.org/10.5194/egusphere-egu24-13467, 2024.

EGU24-15383 | ECS | Orals | SSS5.6

On-farm soil management distinctly influences the stabilization of dissolved organic carbon within soil aggregates 

Orracha Sae-Tun, Christoph Rosinger, Gernot Bodner, Axel Mentler, Herwig Mayer, Sabine Huber, and Katharina Keiblinger

Dissolved organic carbon (DOC) is a highly active carbon pool which can easily be utilized by soil microbes and is thereby a crucial fraction of the soil carbon cycle. Occlusion within soil aggregates is one important stabilization mechanism of DOC in the soil and is affected by various factors including soil management and site-specific conditions. However, details about this mechanism and its regulating factors are still largely unclear. Thus, this study aims to investigate the stabilization mechanism of DOC in soil aggregates under different soil managements across varying soil textures (fine, medium, and coarse). In the study, the soil managements were categorized into three different systems depending on the degree of conservation measures implemented on the farms: state-of-the-art system (standard), conservation systems (pioneer) which were primarily characterized by intensive use of cover cropping together with crop diversification and rotation, and semi-natural grassland (reference). We employed a combination of ultrasonication and online UV-visible spectroscopy to examine the concentration of DOC released from soil aggregates decayed. The experimental setup followed the theory that the duration of low-amplitude ultrasonication energy correlates with higher aggregate stability (resistant to decay), which in return affects the stability of DOC. Influential factors were assessed from relationships with soil physico-chemical and biological characteristics. Based on the observed release pattern, the study deduced that DOC was stabilized within soil aggregates across three different stability levels: low, moderate, and high. 

The results revealed that soil management systems exerted a significant effect on DOC in moderately and highly stable aggregates. Standard systems exhibited the lowest DOC concentration, while reference systems demonstrated the highest concentration. A significant effect of soil texture was found only at the moderate aggregate stability level where coarse soil displayed the lowest DOC concentration. Contrastingly, neither soil management systems nor soil texture had a significant effect on DOC concentration at the low aggregate stability level. The stabilized DOC within moderately stable aggregates, as evidenced by DOC concentration at the moderate level of aggregate stability, exhibited more pronounced correlations with soil microbial variables (i.e., microbial biomass C and ergosterol) than with soil texture as identified through particle size distribution. Therefore, our results suggest that changes induced by soil management, particularly in microbiological attributes, have a more crucial role on the stabilization of DOC in highly stable aggregates than site-specific conditions such as soil texture. Furthermore, the application of low-energy ultrasonication in this study enables the differentiation of soil managements, even within arable systems, in an on-farm setting.

How to cite: Sae-Tun, O., Rosinger, C., Bodner, G., Mentler, A., Mayer, H., Huber, S., and Keiblinger, K.: On-farm soil management distinctly influences the stabilization of dissolved organic carbon within soil aggregates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15383, https://doi.org/10.5194/egusphere-egu24-15383, 2024.

EGU24-17574 | ECS | Posters on site | SSS5.6

Determining factors of soil organic carbon in the sclerophyll ecosystem of central Chile 

Nancy Daniela Mallitasig, Marcelo Miranda, and Eduardo Arellano

The sclerophyllous forest of Central Chile, a Mediterranean-type ecosystem, is facing increasing vulnerability, exacerbated by anthropogenic pressures and drought conditions that have intensified over the past decade.

The objective of this study was to determine, at both regional and local scales, the factors influencing soil organic carbon (SOC), considering the integrated soil-vegetation system. Biophysical conditions such as primary productivity (PP), soil properties (SP), terrain physiography, and climate were considered.

At the regional scale, predictive variables for PP were selected using remote sensing techniques, including the Enhanced Vegetation Index (EVI) and the Normalized Difference Water Index (NDWI) in the spring period. Additionally, climatic variables (maximum, mean, and minimum temperature in spring and annual precipitation between 2001 and 2021) and physiographic variables such as exposure, slope, elevation, and topographic position index (TPI) were included. Statistical analysis was analyzed using a Random Forest model.

At the local scale, a forest inventory has been made, and soil samples were taken at a depth of 20 cm in 45 field plots of 400 m2, located in multi-species shrub vegetation (>4m in height). Concentrations and stocks of SOC were quantified, along with physical properties (texture, field capacity, and macroaggregates), chemical properties (pH, organic matter content, total nitrogen, and C/N ratio), and microbial activity estimated through basal respiration. Biomass, nitrogen content, and C/N ratio of leaf litter also measured. Statistical analysis was performed using a stepwise regression.

Preliminary results indicate that the most significant variables in predicting SOC were EVI, slope, elevation, total nitrogen, DA, LAI, coverage of the tree stratum, and vegetation height at the corresponding spatial scale.

How to cite: Mallitasig, N. D., Miranda, M., and Arellano, E.: Determining factors of soil organic carbon in the sclerophyll ecosystem of central Chile, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17574, https://doi.org/10.5194/egusphere-egu24-17574, 2024.

EGU24-17771 | Posters on site | SSS5.6 | Highlight

Modelling of C stock development for assessing the feasibility and implications of humus build-up in humus-oriented farming  

Susanne Stadler, Lisa Bahlmann, Ursula Noell, Florian Stange, Silke Mollenhauer, Alice Woelk, Andrea Rode, and Christina Aue

Soil and groundwater resources in the North Sea region are under increasing pressure due to climate change and human activities, calling for the need of sound strategies for their sustainable protection. The EU Interreg North Sea Project "Blue Transition" targets at a systemic change that balances activities in urban, agricultural or natural areas. It considers a transition in land-use and fosters political structures and governance, investigating 16 pilot sites in Denmark, The Netherlands, Sweden, Belgium, France and Germany to exchange and develop transnational solutions for water boards, farmers, authorities and society.

Within the project, we conduct scenario-based simulations (some based on strip experiments) regarding humus build-up under climate-induced rising temperatures and leaching from humus decomposition in arable soils in Lower Saxony, comparing conventional and organic farming. The aim of our study is an improvement of soil management in conventional and organic farming – especially regarding humus build-up and N loss reduction from soil. The results will serve as a base for elaborating best practices in management strategies for humus-oriented farming, and for investigating implications on soil water. We show first approaches of the numerical simulations.

How to cite: Stadler, S., Bahlmann, L., Noell, U., Stange, F., Mollenhauer, S., Woelk, A., Rode, A., and Aue, C.: Modelling of C stock development for assessing the feasibility and implications of humus build-up in humus-oriented farming , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17771, https://doi.org/10.5194/egusphere-egu24-17771, 2024.

EGU24-18519 | ECS | Posters on site | SSS5.6

Impacts of long term P availability on Soil Organic Carbon stocks and cycling – insights from the EJP ICONICA project 

Parag Bhople, David Wall, Karl Richards, Fiona Brennan, Gary Lanigan, and Giulia Bondi

The management of agro-ecosystems enhancing soil and subsoil organic carbon (SOC) sequestration could be a potential strategy to mitigate climate change. However, soil quality and organic matter (SOM) transformation is highly regulated by the cycle and interactions with other nutrients such as carbon (C), nitrogen (N) and phosphorus (P). In agricultural management, the addition of P fertilizers and its effect on C and N cycling (CNP stoichiometry) is still largely unknown. Therefore, the ICONICA project intends to provide context-based information on soil nutrients (C & N) and their stocks and cycling in P fertilizer scenarios. To determine the influence that P fertilization has on SOC stabilizations and greenhouse gas (GHG) emissions in agricultural systems, ICONICA employed a unique set of long-term P fertilizer experiments (LTEs) across Europe, including a range of P treatments to establish relationship between long-term P availability and interaction with C and N. In this project soils up to 50 cm depth were collected from six LTEs distributed across Europe. The LTEs feature different soil type/textural classes and land uses. The objective was to quantify C stocks and provide initial reference value of soil C storage for soil depths and link that to the soil stoichiometric ratios (C:N:P) in different management systems. Overall, in grassland sites the average SOC stocks ranged from 54.76±6.65 (tC/ha) in The Netherlands, followed by 43.07±5.71 (tC/ha) in Ireland. The average SOC stocks in arable sites in Sweden were 21.22±1.19 (tC/ha) and the least SOC stocks (18.60±2.35 (tC/ha) occurred in arable site in Denmark. Grassland sites showed a higher SOC stock within the topsoil (0-10 cm) while arable sites contributes most of the C in the subsoil especially at 10-30 cm. The mean soil C/N ratio was higher in the topsoil (0-10 cm) in the arable with respect to the grasslands and ranged from 13.74 to 10.28 with similar trend at soil depth gradients. The variations in C flow and in stocks through the sampled profile of different land uses such as grassland to arable is highly complex and driven by multiple factors indicating the need for further assessment. Nevertheless, the observations indicated the indispensable nature of long-term field experiments to quantify the optimum C:N:P stoichiometry that may enable efficient SOC sequestration as opposed to production in the managed agricultural systems.

How to cite: Bhople, P., Wall, D., Richards, K., Brennan, F., Lanigan, G., and Bondi, G.: Impacts of long term P availability on Soil Organic Carbon stocks and cycling – insights from the EJP ICONICA project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18519, https://doi.org/10.5194/egusphere-egu24-18519, 2024.

EGU24-18694 | ECS | Orals | SSS5.6

Greenhouse gas emissions and nitrate leaching as a result of grassland renovation practices 

Mart Ros, Jordy van 't Hull, and Gerard Velthof

Grasslands are a major sink of organic carbon and for that reason are interesting as a means to achieve national and international climate goals. Grassland renovation (reseeding or conversion to arable land) is a common measure to counteract yield declines in intensively managed agricultural grasslands. The destruction of the sod that accompanies this practice induces a strong increase in mineralization of soil organic carbon and can therefore be a major source of nitrate (NO3) leaching and emissions of carbon dioxide (CO2) and nitrous oxide (N2O).

 

Most farmers prefer reseeding in autumn instead of spring because of better establishment of the sward and low weed infestation. However, limited crop nitrogen (N) demand during autumn increases the risk of NO3 leaching and N2O emissions. Potentially, such N losses could be mitigated by measures such as reducing tillage intensity, reducing fertilizer N application, or applying nitrification inhibitors. In 7 different experiments, we studied the effect of various grassland renovation practices on soil N cycling, greenhouse gas emissions, and nitrate leaching. We hypothesized (i) that conversion to arable land leads to greater CO2 and N2O losses than the reseeding of grassland; (ii) that reseeding in autumn causes enhanced risk of NO3 leaching during winter; and (iii) that these losses can be mitigated by reducing tillage and/or N application rates.

 

Results show that NO3 concentrations in groundwater after harvest were higher for observed after autumn reseeding combined with mitigation strategies than for reseeding in spring. This implies that confining the renewal of grassland to spring season could be a viable strategy to mitigate NO3 leaching. Emissions of N2O varied between experiments and could generally be linked to precipitation events and agricultural management (fertilization and renovation). Grassland renovation led to higher N2O (and CO2) emissions, but the effects of mitigation practices were inconsistent. The results from these experiments will be discussed in more detail. Mitigation strategies for N2O are less straightforward than those for nitrate leaching.

How to cite: Ros, M., van 't Hull, J., and Velthof, G.: Greenhouse gas emissions and nitrate leaching as a result of grassland renovation practices, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18694, https://doi.org/10.5194/egusphere-egu24-18694, 2024.

EGU24-19029 | ECS | Posters on site | SSS5.6 | Highlight

Phosphorus modelling on agricultural fields – trade-offs between applicability and complexity 

Julius Diel, Sara König, Ulrich Weller, and Hans-Jörg Vogel

Besides nitrogen, phosphorus is the second most important nutrient for plants, but has only little natural inputs. If it is not added regularly by fertilizers, be it mineral or organic, the soil gets depleted after a few years. As a consequence, crop growth is impeded as well as the microbial turnover of soil organic matter.  However, many crop growth models do not account for phosphorus dynamics, although it might be a limiting factor.

In a mechanistic soil process model such as BODIUM, crops are growing dynamically adapting to their boundary conditions and affect many other soil functions due to water and nutrient uptake, root exudation and biomass input to the soil. Moreover, microbial metabolism depends on the stoichiometry of soil organic matter and available nutrients, i.e. C/N/P ratios. A phosphorus component shall therefore enhance the nutrient cycle and improve the crop growth prediction, both in regard to yields as well as to feedbacks with other soil processes.

Here, we want to present an extended BODIUM version including the representation of the P cycle and present first simulations with data from the Static Fertilization Experiment in Bad Lauchstädt. Beside stoichiometric considerations for all organic pools, the mineral dynamics are represented with only ‘total’ and ‘available’ P. These can easily be measured by standard procedures and are now mandatory in some countries, although with varying protocols. This is especially relevant for farmers, who are a declared target group of the model.

How to cite: Diel, J., König, S., Weller, U., and Vogel, H.-J.: Phosphorus modelling on agricultural fields – trade-offs between applicability and complexity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19029, https://doi.org/10.5194/egusphere-egu24-19029, 2024.

EGU24-19722 | ECS | Posters on site | SSS5.6 | Highlight

Quantifying baseline soil organic carbon (SOC) stocks to allow establishment of robust carbon accounting framework for sustainable agriculture in Ireland  

Alex Martin Castellon Meyrat, Lilian O'Sullivan, David Wall, Paul Holloway, and Giulia Bondi

The soil organic carbon (SOC) and stocks mediate pivotal ecosystem services such as carbon sequestration, climate regulation by mitigating greenhouse gas emissions, nutrient cycling, provisioning habitats for organisms, water supply, and production of food, fiber and fuel. In agricultural systems, multiple factors including climate, soil types, vegetation, and land management affect the SOC dynamics. However, the coupled impacts among these factors on SOC stocks at farm and regional scale are still unknown. Therefore, it is crucial to expand our understanding of carbon cycle under different scenarios to develop more sustainable agro-ecosystems at national level. To achieve this, Teagasc is leading the Signpost Program a multiannual sampling campaign aiming to build an accurate baseline of SOC stocks across different soil types, land uses and management regimes in Ireland. This will help to understand the carbon dynamics in Irish agricultural soils, revealing the composition and stability of SOC in depth. To build the baseline for longtime soil carbon observatory, SOC data and soil health indicators for 148 soil profiles have been collected to date within 37 farms across the country. The method for site selection was based on combination of geographic information system (GIS) techniques and the catena approach, covering different climatic regions, soil types, and farming systems along the dominant hillslope within each farm. The soil samples were taken at each 15 cm increment up to 60 cm soil depth. The baseline data includes estimation of chemical properties such as potassium (K) and phosphorus (P) obtained by Morgan’s extraction; pH, total nitrogen (N), total carbon (C), and organic carbon (SOC); aluminum (Al), calcium (Ca), Magnesium (Mg), and phosphorus (P). It also includes physical properties such as bulk density based on three replicates per each range of sampling depth and finally clay, silt, and sand content to be assessed by spectroscopy measurements. Finally, SOC stocks across P scenarios, C/N ratio, and C:N:P ratios are estimated to understand the capacity of soils to sequester carbon and the nutrients dynamics under different management regimes and soil types. The Signpost initiative emphasizes soil management practices with long-term benefits for the environment and expand knowledge to contribute to sequestering carbon, improving overall soil health to support progression of sustainable agricultural systems.

How to cite: Castellon Meyrat, A. M., O'Sullivan, L., Wall, D., Holloway, P., and Bondi, G.: Quantifying baseline soil organic carbon (SOC) stocks to allow establishment of robust carbon accounting framework for sustainable agriculture in Ireland , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19722, https://doi.org/10.5194/egusphere-egu24-19722, 2024.

EGU24-20186 | Posters on site | SSS5.6

Trace metals in the soils of the Sanjiang Plain in the Northeast Asia: Land use influence 

Jing Wang, Hongguang Cheng, Kai Yang, and Chunye Lin

The Sanjiang Plain is located in the Northeast Asia, where the large areas of farmland and wetland are distributed. The soil cores of 40 to 100 cm depth were collected at 48 sites in the Sanjiang Plain and sectioned into 3-, 5- or 10-cm slices. In total, 451 soil samples were got and were analyzed for trace, minor, and major elements. The concentration ranges of trace and minor metals (mg kg-1) in the soil were 1.08-65.7 for As, 0.03-0.36 for Cd, 5.26-103.8 for Co, 42.6-102.9 for Cr, 12.4-64.4 for Cu, 0.01 to 0.14 for Hg, 139.3-4184.5 for Mn, 13.4 to 58.2 for Ni, 15.3-106.2 for Pb, 0.25-1.67 for Sb, 7.87-23.6 for Sc, 2525-6265 for Ti, 51.7-283.4 for V, and 42.8-184.6 for Zn. The average contents of Al2O3, Fe2O3, MgO, CaO, Na2O, and K2O in the soil were 9.72%, 5.34%, 1.00%, 0.98%, 1.63, and 2.28%, respectively. The soil pH ranged from 5.03 to 6.97, with an average of 5.84. Land uses had important effects on trace metal concentrations in the soil. The average concentrations of As, Co, Mn, and Pb the soil decreased from forest land, to dry farmland, to paddy field, and to wetland. On the other hand, the average concentrations of Cr, Cu, Ni, Sc, and Ti in the soil of wetland and paddy field were higher than those of dry farmland and forest land. However, the average concentrations of Hg and V in the soil of wetland and forest land were higher than those of paddy field and dry farmland. The difference in the concentrations of trace and minor elements among the four types of land use originate from anthropogenic activity, hydrologic conditions, and pristine soil properties. Atmospheric deposition of V and Hg led to higher Hg and V concentrations in the soil of natural wetland and forest land than in the agricultural land (paddy field and dry farmland). Higher leaching of redox sensitive elements such as As, Co, Mn, and Pb led to lower concentrations of As, Co, Mn, and Pb in wetland and paddy field than in forest land and dry farmland. The difference in the concentrations of Cr, Cu, Ni, Sc, and Ti in the soil among the four kinds of land use should be ascribed to the difference in the pristine soil properties.  

This study was funded by the National Natural Science Foundation of China (42276233). 

How to cite: Wang, J., Cheng, H., Yang, K., and Lin, C.: Trace metals in the soils of the Sanjiang Plain in the Northeast Asia: Land use influence, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20186, https://doi.org/10.5194/egusphere-egu24-20186, 2024.

It has been advocated that nitrogen (N) availability plays an essential role in mediating plant and microbial growth in cold environment, and could thus regulate the direction and magnitude of permafrost carbon (C)-climate feedback. However, compared to widely concerned N, little is known about soil phosphorous (P) availability and its biological acquisition strategies in permafrost environment. Here we explored soil microbial P acquisition strategies using shotgun metagenomics across the Tibetan permafrost area, encompassing a large scale survey spanning 1,000 km. In contrast to the traditional opinion that microorganisms in cold area usually obtain P mainly through mineralization process, our results revealed that the P cycling genes responsible for solubilization, mineralization and transportation were widespread, illustrating multiple microbial strategies for acquiring P in permafrost regions. Moreover, the higher gene abundance related to solubilization and mineralization as well as an increased ration of MAGs carrying these genes were detected in the active layer, while the greater abundance of low affinity transporter gene (pit) and proportions of MAGs harbouring pit gene were observed in permafrost deposits, reflecting a stronger potential for P activation in active layer but an enhanced P transportation potential in permafrost deposits. Taken together, these results highlight that besides microbial P mineralization, multiple P-related acquisition strategies and their differences among various soil layers should be considered simultaneously to improve model prediction for the responses of biogeochemical cycles in permafrost ecosystems to climate change.

How to cite: Wang, L. and Yang, Y.: Divergent microbial phosphorous acquisition strategies between active layer and permafrost deposits, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2973, https://doi.org/10.5194/egusphere-egu24-2973, 2024.

EGU24-3208 | ECS | Orals | BG1.4 | Highlight

Seagrasses' role as a reverse sedimentary phosphate pump 

Neta Soto, Gilad Antler, and Avner Gross

Seagrasses are marine-flowing plants that form an important coastal ecosystem. Although occupying less than 0.2% of the ocean’s surface, seagrasses store over 15% of the accumulated global carbon storage in the ocean’s sediments. Thus, Seagrass meadows play a pivotal role in mitigating climate change by carbon sequestration. Seagrasses are widely distributed in oligotrophic tropical waters despite the low nutrient levels in the water column due to their ability to absorb nutrients from the sediment porewater. Moreover, seagrasses can actively mobilize unavailable nutrients e.g., iron and phosphorus in the rhizosphere via multiple biogeochemical interactions. This provides them with an important advantage over pelagic photoautotrophs, which are limited by the availability of nutrients in the water column. Despite their ability to transport nutrients from sinks e.g., sediments to the water column where they can be recycled trough grazing or decomposition, the potential role of seagrass as a revers sedimentary phosphate pump remains unclear. The aim of this study is to examine the effect of seagrass disappearance on phosphate flux in marine coastal environments. In a series of incubation experiments, the change in the phosphate release was examined in different tissues of seagrass Halophila stipulacea. The results showed that the while the highest decomposition rate of the rhizomes was the fastest, the highest phosphate release rate was measured in the leaves, despite having similar phosphate content. Since the leaves mostly decompose in the water column, the released phosphate is made available to planktonic photoautotrophs and further enhances more carbon fixation. Overall, we suggest that in oligotrophic environments seagrasses act as a reverse phosphate pump by accessing phosphate in the sediment and later translocating it to the aboveground parts and releasing in the water column, thus fertilizing planktonic photoautotrophs and enhancing further carbon sequestration.

How to cite: Soto, N., Antler, G., and Gross, A.: Seagrasses' role as a reverse sedimentary phosphate pump, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3208, https://doi.org/10.5194/egusphere-egu24-3208, 2024.

EGU24-3472 | Orals | BG1.4

Elevated atmospheric CO2 increased soil plant available and soil organic phosphorus in a mature temperate oak (Quercus robur L.) forest 

Amin Soltangheisi, Adam Pinder, Keegan Blazey, Robert T. Grzesik, Miles Marshall, Angeliki Kourmouli, Carolina Mayoral, Kris M. Hart, Sami Ullah, Iain P. Hartley, A. Robert MacKenzie, and Andy R. Smith

Enhanced productivity of forest ecosystems in response to rising levels of anthropogenically generated atmospheric carbon dioxide (CO2) has the potential to mitigate against climate change by sequestering carbon in woody biomass and soils. However, the physiological response of trees to elevated atmospheric CO2 may be constrained by the availability of soil nutrients, predominantly nitrogen and phosphorus (P). Here, we assess the impact of elevated atmospheric CO2 on P cycling in a temperate 180-year-old oak (Quercus robur L.) forest exposed to free-air CO2 enrichment (ambient + 150 ppm) for six years. Soil cores were collected to a depth of 1 m in July 2023 and separated into three horizons and three layers (O, A, B, 30-50, 50-70, 70-100 cm) before analysis using the Hedley1 sequential P fractionation and the DeLuca2biological based P extraction techniques. Plant available P in soil pore water and total organic P from the O horizon increased by 84 and 128%, respectively, whilst organic P extracted with phosphatase increased by 62% under elevated CO2. Total organic P in soil horizons beyond the B horizon (> 15 cm) decreased under elevated CO2 in comparison with ambient CO2. As soil organic P is derived from the turnover of both vegetation and microbial biomass, increased soil organic P in the O horizon may be due to the faster turnover of organic matter or an increase in the net primary productivity of the forest. Soil P cycling in this forest ecosystem appears to be predominantly influenced by biological rather than chemical processes, since elevated CO2 only affected the organic P and not inorganic P fractions. Forest productivity may be constrained by P limitation in future elevated CO2 environments, if there is faster organic matter turnover which is probably the case in our study.

1Hedley, M. J., Stewart, J. W. B., & Chauhan, B. (1982). Changes in inorganic and organic soil phosphorus fractions induced by cultivation practices and by laboratory incubations. Soil Science Society of America Journal, 46(5), 970-976.

2DeLuca, T. H., Glanville, H. C., Harris, M., Emmett, B. A., Pingree, M. R., de Sosa, L. L., Cerdá-Moreno, C. & Jones, D. L. (2015). A novel biologically-based approach to evaluating soil phosphorus availability across complex landscapes. Soil Biology and Biochemistry, 88, 110-119.

How to cite: Soltangheisi, A., Pinder, A., Blazey, K., Grzesik, R. T., Marshall, M., Kourmouli, A., Mayoral, C., Hart, K. M., Ullah, S., Hartley, I. P., MacKenzie, A. R., and Smith, A. R.: Elevated atmospheric CO2 increased soil plant available and soil organic phosphorus in a mature temperate oak (Quercus robur L.) forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3472, https://doi.org/10.5194/egusphere-egu24-3472, 2024.

EGU24-4491 | Posters on site | BG1.4

Silicone availability and NaCl water type enhances the phosphorus release from sediments in coastal forest catchments in Akita, Japan 

Atsushi Hayakawa, Yuka Kuroe, Ayumi Kawata, Kazuya Nishina, Yuichi Ishikawa, and Tadashi Takahashi

[Background] Phosphorus (P) availability in soils and sediments is a critical parameter influencing primary production in terrestrial and aquatic ecosystems, controlled by both P chemical fractions in solid phase and solution composition. A recent study using Arctic soils reported that the addition of Si to the soil released P bound to Fe(II) compounds, but reports on other soils and sediments are limited. In our previous study, we detected higher P concentrations in stream water and iron-bound P content in river sediments in the marine sedimentary rock catchments of the Akita coastal area compared to catchments in the adjacent igneous rock area. Furthermore, high-P stream waters were NaCl water type with relatively lower Ca2+ and higher SiO2 concentrations. In this study, we evaluated the effects of different solution compositions and amorphous Si addition on P solubilization in sediments using river sediments from marine sedimentary and igneous rock regions. [Method] We tested each five river sediments (<2 mm) in the headwaters of western Akita Prefecture, Japan, where the surface geology is composed of marine sedimentary rocks and igneous rocks. Available Si (easily water-soluble Si) was measured by a long-term flooded incubation in distilled water at 30°C for 30 days. In the P dissolution incubation, four types of treatment solutions (distilled water, 1 mM NaCl and NaHCO3 solutions, and 0.5 mM CaCl2 solution) were added to 0.5 g sediment and in the Si addition treatment, amorphous Si (hydrophilic fumed silica, AEROSIL300) was also added. SRP, DOC and pH in the solution were measured after shaking for 48 hours. A statistical analysis was performed using a linear mixed model (LMM) with SRP, DOC and pH in the liquid phase as objective variables. The surface geology, four types of solutions, and the Si addition as explanatory variables. Additionally, each five sediment was treated as a random effect. [Results and discussion] Easily water-soluble Si content in sediments was significantly higher in marine sedimentary rock areas (p < 0.001), indicating that the easily soluble Si causes higher SiO2 concentration in stream water. The incubation results showed Si addition significantly increased P concentration in the liquid phase (p < 0.001), and combined Si addition with NaHCO3 treatment further increased P concentration. Conversely, CaCl2 treatment significantly decreased the liquid-phase P concentration. The influence of surface geology on extracted P concentration was not significant. Si addition did not affect pH (p = 0.58) and DOC (p = 0.90), while the effects of solution composition on pH and DOC were also significant; NaHCO3 solution increased pH and DOC while CaCl2 solution decreased pH and DOC. In conclusion, in marine sedimentary rock areas in coastal Akita with NaCl water type where Ca2+ concentration is relatively low and sediments have higher easily soluble Si, P release from sediments easily occurs and a high P concentration keeps in the liquid phase.

How to cite: Hayakawa, A., Kuroe, Y., Kawata, A., Nishina, K., Ishikawa, Y., and Takahashi, T.: Silicone availability and NaCl water type enhances the phosphorus release from sediments in coastal forest catchments in Akita, Japan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4491, https://doi.org/10.5194/egusphere-egu24-4491, 2024.

EGU24-6352 | ECS | Posters on site | BG1.4

Phosphorous in the seabed sediments of the Gulf of Riga, Baltic Sea: Fe-Mn concretions as main carriers of mobile phosphorous  

Markus Ausmeel, Martin Liira, Päärn Paiste, Aivo Lepland, and Sten Suuroja

Baltic Sea is a geologically young semi-enclosed brakish-water body which water exchange with the ocean has been gradually declining. Approximately 85 million people live in the Baltic Sea's catchment area, resulting in significant human impact on the basin's ecosystem. Eutrophication due to anthropogenic discharge of nutrients is considered to be the most serious environmental problem which leads to a greater growth of phytoplankton and algae, deterioration of water quality, and lack of oxygen in near-bottom water masses. As a result of recent large-scale input of nutrients, phosphorus has accumulated in the seabed sediments from where it can be remobilized and released into the water column under favorable conditions (hypoxic or anoxic). Marine sediments contain phosphorus in various components i.e. fractions, but not all of them are affected by remobilization. Therefore, knowing how phosphorus fractions are distributed in seabed sediments is important.

One part of the Baltic Sea that has received little attention, but will significantly affect the entire Baltic Sea in the future, is the Gulf of Riga. The Gulf of Riga accounts for less than 5% of the total area of the Baltic Sea and less than 2% of the total water volume. Due to its shallowness and limited connection with the open Baltic Sea, the Gulf of Riga is strongly influenced by riverine input. Intense agriculture, rapid development of industry, and urbanization have resulted in high loads of nutrients into the Gulf of Riga already since the 1960s.

Phosphorus fractions and their vertical distribution were studied from the sea-bottom sediments from the Gulf of Riga and other coastal areas of western Estonia. The amount of potentially mobile phosphorus stored in the surface sediments of the Gulf of Riga is several times higher than in other accumulation areas of the Baltic Sea, with concentrations as high as 980 mg/kg(dw). A strong correlation between Mn and mobile phosphorus concentration suggests that Fe-Mn concretions control the amount of phosphorus in the sediments of the Gulf of Riga. Although the bottom waters of the Gulf of Riga are currently predominantly oxic, a decreasing trend of deep-layer oxygen concentrations and more frequent hypoxia in the Gulf of Riga during previous decades have been documented. Considering the large amount of potentially mobile phosphorus in the sediments of the Gulf of Riga, surpassing the annual total phosphorus input to the Baltic Sea, a substantial release of phosphorus could be inevitable, possibly impacting the entire Baltic Sea ecosystem.

How to cite: Ausmeel, M., Liira, M., Paiste, P., Lepland, A., and Suuroja, S.: Phosphorous in the seabed sediments of the Gulf of Riga, Baltic Sea: Fe-Mn concretions as main carriers of mobile phosphorous , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6352, https://doi.org/10.5194/egusphere-egu24-6352, 2024.

EGU24-7212 | ECS | Orals | BG1.4

Vivianite verified in early Cambrian strata in northwestern China: Implications for phosphorus recycling in ancient anoxic oceans 

Xuyang Cao, Pengcheng Ju, Yigui Han, Lihui Lu, and Dong Shao

In modern low sulfate and anoxic (euxinic) waters, the precipitation of mineral vivianite (an easily oxidized hydrated ferrous-iron phosphate) has played a crucial role in restraining the limiting nutrient element phosphorus (P) recycling back to the water column and consequently decreasing primary productivity. Although such low sulfate and anoxic conditions were widespread in ancient coastal oceans, vivianite has not been directly discovered in the paleo-sediments, which hampers the understanding of P cycling in ancient anoxic environments. Here, we combined techniques of scanning electron microscopy-energy dispersive X-ray spectroscopy, focused ion beam-transmission electron microscopy and P K-edge X-ray absorption near edge structure spectroscopy to analyze samples of P-bearing siliceous rocks and shales from the early Cambrian Yurtus Formation in the Tarim Craton, northwest China. Our results have demonstrated that micron- to nano-scale vivianite crystals are well preserved in the rocks and the vivianite dominates the P phase in some samples. The cherty matrix of the rocks most likely increased the chances of preservation of the oxidation-sensitive vivianite. In light of recent advances, we suggest that vivianite was a crucial P phase in ancient continental margin sediments, spanning most time from the Neoarchean to the early Cambrian. During this interval, the precipitation of vivianite was likely aided by the prevalent dynamic ocean euxinic conditions linked with the seawater sulfate reservoir and the flux of organic matter settling. We propose a negative feedback mechanism in which vivianite precipitation from ancient euxinic waters restricted P availability for biota, reduced marine primary productivity, and possibly abated the rate of Earth's oxygenation and associated evolution of life. This work was financially supported by NSFC projects (grants 42072264, 41730213) and Hong Kong RGC GRF (17307918).

How to cite: Cao, X., Ju, P., Han, Y., Lu, L., and Shao, D.: Vivianite verified in early Cambrian strata in northwestern China: Implications for phosphorus recycling in ancient anoxic oceans, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7212, https://doi.org/10.5194/egusphere-egu24-7212, 2024.

EGU24-9578 | ECS | Posters on site | BG1.4

Lithology-constrained phosphorus (P) releasement 

Shenghui Ouyang

Phosphorus (P), as an indispensable nutrient element in Earth’s biological system, exerts a pivotal role on the burial of organic carbon over million-year time scales. By producing oxygen and consuming carbon dioxide, organic carbon burial may have paved the path for multicellular organisms by reforming the anoxic atmosphere to an oxic one. Organic carbon burial, on long time scales, is ultimately limited by continental P influx released by chemical weathering of P-bearing minerals. As crystalline rocks characterized by prominent discrepancy in P-bearing mineral composition undergoing various dominant weathering forces on surficial environment, P availability for organic carbon burial could be controlled by lithology. To decipher the conundrum of P releasement, a catchment scale case study was conducted, encompassing a series of lithologies following the crystalline rock order. Preliminary data suggests that the P release efficiency is lithology-constrained, indicating an enhanced P releasement in felsic catchment. The result gives us a hint that felsic crust would export more P to the ocean and promote the organic carbon burial, the lithology-constrained P releasement also enlightens us a new perspective to understand the coevolution among crust, atmosphere and life.

How to cite: Ouyang, S.: Lithology-constrained phosphorus (P) releasement, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9578, https://doi.org/10.5194/egusphere-egu24-9578, 2024.

EGU24-9674 | ECS | Orals | BG1.4

Linking phosphorus research to impact: advances and challenges in mapping soil phosphorus pools 

Julian Helfenstein, Bruno Ringeval, Federica Tamburini, Daniel S. Goll, Xianjin He, Vera Mulder, Yingping Wang, Edwin Alblas, and Emmanuel Frossard

Improved management of phosphorus (P) is essential for achieving a range of Sustainable Development Goals (SDGs), including maintaining food security, preserving water quality, and mitigating climate change. This requires an integration of comprehensive mechanistic understanding with accurate spatial data. In this interdisciplinary review, we combine insights from empirical P research, digital soil mapping, biogeochemical modeling, and environmental law to critically examine the current state, pinpoint challenges and propose novel pathways for desperately needed P maps. We first elucidate the relevance of spatial data on P for different SDGs. Subsequently, we summarize the current efforts in mapping P pools at regional to global scales, and discuss the challenges of mapping “available P” due to substantial local scale variability and poor correlation with predictors relative to other soil properties. The practical applicability of these recently published maps is tested by evaluating them with independent measurement data. Finally, we outline ways forward to enhance the accuracy and reliability of P maps, as a basis for science-informed management of P resources.

How to cite: Helfenstein, J., Ringeval, B., Tamburini, F., Goll, D. S., He, X., Mulder, V., Wang, Y., Alblas, E., and Frossard, E.: Linking phosphorus research to impact: advances and challenges in mapping soil phosphorus pools, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9674, https://doi.org/10.5194/egusphere-egu24-9674, 2024.

EGU24-14368 | Orals | BG1.4

Phosphorus Cycling and Transport in Phosphorus Saturated Soils of the Chesapeake Bay Watershed, USA 

Gurpal Toor, Jesse Radolinski, Emileigh Lucas, Charles Burgis, Bradley Kennedy, Fajun Sun, and Patricia Steinhilber

Long-term application of organic products (manure, biosolids, other wastes) and inorganic phosphatic fertilizers have created hot spots of phosphorus (P) saturated soils in intensive animal production regions worldwide. In such regions, P losses from P-saturated (i.e., legacy P) soils continue to plague efforts to improve water quality. Understanding the P cycling and fluxes from these P-saturated soils is critical to advancing our knowledge and developing strategies to manage P in soils and curb P losses. This presentation will discuss P cycling and transport in agricultural catchments (with Maize-Soybean rotation) from the lenses of P chemistry in soils and hydrologic responses from soils to further advancements in managing the P cycle in the soil-plant-water continuum for agricultural sustainability and environmental protection.

How to cite: Toor, G., Radolinski, J., Lucas, E., Burgis, C., Kennedy, B., Sun, F., and Steinhilber, P.: Phosphorus Cycling and Transport in Phosphorus Saturated Soils of the Chesapeake Bay Watershed, USA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14368, https://doi.org/10.5194/egusphere-egu24-14368, 2024.

EGU24-14436 | ECS | Orals | BG1.4

Balancing crop production, water quality and the use of finite P reserves by using the soil P sorption capacity in revised fertilizer recommendations 

Maarten van Doorn, Debby van Rotterdam-Los, Gerard H. Ros, and Wim de Vries

Phosphorus (P) is an essential nutrient for plant growth and is applied to agricultural soils in the form of organic manure or inorganic fertilizer. To guide farmers in achieving optimal crop yields, P fertilizer recommendations are in place with the rationale to bring soils to a “target soil P status” following the classic build-up and maintenance approach. The target soil P status where crop yield is not limited by P deficiencies is generally operationalized as the soil P status at which 90-99% of the potential crop yield is found in long-term fertilization field experiments. Though these fertilizer recommendations allow for an economic optimization of crop yield versus P inputs, environmental objectives are barely considered. In our research, we revised the classic build-up and maintenance approach to balance crop production, water quality and the use of finite P reserves. This revision requires insights into the P sorption capacity of soils (PSC) and its saturation with P. We identify the oxalate extraction method as a key component of this approach since it quantifies the PSC from the combined measurement of amorphous iron- and aluminium-(hydr)oxides and the total pool of reversibly bound P. For the Netherlands, we show the implications of the approach for P fertilizer use. We quantified soil amorphous iron- and aluminium(hydr)oxides contents at a 25m resolution across the soil depth profile using a Digital Soil Mapping approach and used these predictions to translate agronomic soil P data to new insights to optimize P fertilizer use. We finally argue that agronomic P target levels should be lowered in soils with a low PSC to decrease the risk of P leaching and in soils with a high PSC to ensure judicious use of finite P reserves.

How to cite: van Doorn, M., van Rotterdam-Los, D., Ros, G. H., and de Vries, W.: Balancing crop production, water quality and the use of finite P reserves by using the soil P sorption capacity in revised fertilizer recommendations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14436, https://doi.org/10.5194/egusphere-egu24-14436, 2024.

EGU24-16417 | ECS | Orals | BG1.4

31P NMR Reveals Predominance of Small Molecules in Organic Phosphorus within NaOH-EDTA Soil Extracts 

Lenny Haddad, Andrea Vincent, Reiner Giesler, and Jürgen Schleucher

Organic phosphorus (P) plays a crucial role in maintaining the health and productivity of soils. Understanding the composition of organic phosphorus in soils is thus relevant to a range of disciplines, spanning from agricultural sciences to ecology. Over the past few decades, efforts have been directed towards characterizing and quantifying various soil organic P compounds and determining their turnover rates. Despite these efforts, the precise nature of soil organic P remains unclear, particularly that of orthophosphate monoesters, which dominate 31P NMR spectra of NaOH-EDTA extracts globally.

Typically, the monoester region of 1D 31P NMR spectra appears as a series of sharp signals "sitting" on a broad background where the broad background can account for a substantial part of the monoester region. This is prompting questions about how to integrate and identify these signals and to what extent this fraction may be ecologically important. To investigate this monoester background, we employed 1D 31P NMR and 2D 1H-31P NMR1, along with 31P transverse relaxation (T2)2 measurements to calculate intrinsic linewidths. We related this linewidth to molecular weight to unveil the nature of the observed background. Analysing seven soils from different ecosystems, we observed linewidths ranging from 0.5 to 3 Hz for both resolved monoester signals and the background. This suggests that the background comprises numerous, possibly exceeding 100, sharp signals associated with small (<1.5 kDa) organic P molecules.

Organic P in the form of nucleic acids, phospholipids, P-containing metabolites, and phosphorylated proteins dominate the P content of live leaves, leaf litter and microbial tissues. Furthermore, P-containing metabolites are exuded by roots and are present in a vast array of organisms. Evidence that the background potentially can contain a large number of small metabolites is thus not surprising and may account for an important part of the organic P pool given that the background accounts for about 55% of the monoester region. Our findings warrant further research specifically addressing to what extent this pool may play for plant and microbial P nutrition.

We provide recommendations for treating 31P NMR spectra to accurately quantify phosphomonoester species, representing a crucial step in linking observed P speciation to its bioavailability. Our findings align with previous 31P NMR studies detecting background signals in soil-free samples and new evidence suggesting that alkali-soluble soil organic matter consists of self-assemblies of small organic compounds mimicking large molecules.

1Vestergren, J.; Vincent, A. G.; Jansson, M.; Persson, P.; Ilstedt, U.; Gröbner, G.; Giesler, R.; Schleucher, J. High-Resolution Characterization of Organic Phosphorus in Soil Extracts Using 2D 1H–31P NMR Correlation Spectroscopy. Environmental Science & Technology 2012, 46 (7), 3950–3956. https://doi.org/10.1021/es204016h.

2Vincent, A. G.; Schleucher, J.; Gröbner, G.; Vestergren, J.; Persson, P.; Jansson, M.; Giesler, R. Changes in Organic Phosphorus Composition in Boreal Forest Humus Soils: The Role of Iron and Aluminium. Biogeochemistry 2012, 108 (1), 485–499. https://doi.org/10.1007/s10533-011-9612-0.

How to cite: Haddad, L., Vincent, A., Giesler, R., and Schleucher, J.: 31P NMR Reveals Predominance of Small Molecules in Organic Phosphorus within NaOH-EDTA Soil Extracts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16417, https://doi.org/10.5194/egusphere-egu24-16417, 2024.

EGU24-16549 | ECS | Posters on site | BG1.4

A meta-analysis of global soybean plant growth and yield improvement in response to phosphorus addition 

Hannah Walling, Mariana Rufino, Jose Rotundo, Lucas Borras, Shane Rothwell, John Quinton, and Phil Haygarth

Application of phosphorus (P) fertiliser to soybean accounts for a large proportion of the global consumption of P as an agricultural fertiliser. Despite this key a knowledge gap exists surrounding the mechanisms of P fertiliser uptake and how it interacts with nitrogen fixation processes and yield improvements.

This paper aims to improve the understanding of P cycling in global cropping systems and will present a global meta-analysis of published data quantifying the effect of P fertiliser application on soybean above- and below-ground plant response variables. 790 paired observations (P fertiliser treatment and control treatment) were synthesised from 81 peer-reviewed articles that reported soybean response, including seed yield and nodulation, to P addition under a range of different environmental conditions.

We tested the hypothesise that:

  • soybean productivity will increase following P addition, with this response being driven by below-ground processes;
  • environmental conditions, particularly soil chemical properties would explain the variance in the observed response.

Analysis of these observations showed an overarching increase in soybean plant response following P addition. We found that several environmental and experimental conditions, particularly soil phosphorus status and phosphorus fertiliser rate influence the response of soybean to phosphorus addition, highlighting the complexities of sustaining P use across such a globally cultivated crop.

We recommend further experimental work needs to be conducted, which controls for such factors and allows for the improved mechanistic understanding of below-ground processes, to inform better use of finite P resources.

How to cite: Walling, H., Rufino, M., Rotundo, J., Borras, L., Rothwell, S., Quinton, J., and Haygarth, P.: A meta-analysis of global soybean plant growth and yield improvement in response to phosphorus addition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16549, https://doi.org/10.5194/egusphere-egu24-16549, 2024.

EGU24-17700 | ECS | Posters on site | BG1.4

Vivianite as a phosphorus sink in estuarine systems: The case study of the Brillantes mudflat, Loire, France 

Mohammed Barhdadi, Aurélia Mouret, Christine Barras, Guillaume Morin, Grégoire Maillet, Matthieu Durand, Meryem Mojtahid, Eric Bénéteau, Nicolas Dubosq, and Edouard Metzger

Phosphorus (P) is a key nutrient controlling primary production in aquatic systems. In coastal systems, the P cycle involves dynamic interactions between terrestrial, aquatic and sedimentary compartments. Over the last century, human activities such as deforestation, intensive agricultural practices and the disposal of municipal and industrial wastes have increased P inputs to coastal ecosystems. As a result, this increase in P inputs has led to an increase in the occurrence of algal blooms and higher oxygen demand in estuaries. In the Loire estuary, dissolved oxygen deficits have been a recurrent and worrying issue for several decades despite the improvement of water quality over the last 30 years due to reduced wastewater discharge and better effluent treatment. In this context, the burial of bioavailable P may influence the recovery of waters from eutrophication. The major P burial phases are apatite, organic P and iron-bound P. The results of sequential chemical extraction and pore water analysis carried out over a 5m-long sediment core from the intertidal Brillantes mudflat in the Loire estuary indicated a greater abundance of the iron-bound P compared to other phases. Iron-bound P occurs in two different forms: phosphorus bound to iron oxides and in the iron phosphate mineral known as vivianite. Vivianite is a ferrous iron phosphate mineral formed under reducing and low sulphate conditions in sediments where organic matter serve as electron donor for ferric iron reduction. Results of sequential chemical extraction of freeze-dried sediment samples combined with pore water data and scanning electron microscope–energy dispersive x-ray spectroscopy (SEM-EDXS) on resin-embedded sediment samples indicated that vivianite-type minerals may act as an important sink for P at the studied site. Authigenic vivianite crystals were found below the shallow sulphate/methane transition zone (SMTZ) at 94 cm depth and contain significant amounts of manganese, as observed in freshwater sediments. We therefore hypothesise that anthropogenic over-fertilization of coastal regions in the last century may have increased the importance of vivianite authigenesis in surface sediments. Consequently, vivianite is likely to be an important sink for P in estuarine systems worldwide.

This study is part of a PhD financed by the European Project Life REVERS’EAU.

How to cite: Barhdadi, M., Mouret, A., Barras, C., Morin, G., Maillet, G., Durand, M., Mojtahid, M., Bénéteau, E., Dubosq, N., and Metzger, E.: Vivianite as a phosphorus sink in estuarine systems: The case study of the Brillantes mudflat, Loire, France, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17700, https://doi.org/10.5194/egusphere-egu24-17700, 2024.

EGU24-19011 | Orals | BG1.4

Microbial phosphorus limitiation with soil age along a chronosequence on the Galapagos Islands 

Katharina Maria Keiblinger, Sebastian Socianu, Maria Rechberger, Martin Gerzabek, and Franz Zehetner

The Galápagos archipelago, a volcanic island chain, is comprised of a series of progressively older islands with increasingly weathered soils away from the volcanic hotspot. Volcanic soils are known for their high phosphate sorption capacity. In this study, we explore differences in soil microbial abundance and activity across a soil age gradient (1.5 to 1070 ka) to understand how soil microorganisms are affected by soil development, shifting soil characteristics and P sorption over extensive periods.

Basal respiration, substrate-induced respiration and microbial biomass P decreased with soil development, suggesting increasing nutrient limitation for soil microbes. Also, soil enzymatic stoichiometry revealed a limitation driven mainly by P and not by N or C. C- and N-acquiring exoenzyme activities peaked at 26 ka with lower activities in younger and older soils. Phosphatase activity increased with soil age, indicating microbial P limitation in the older soils. This is only partly in line with  P sorption-desorption characteristics along the studied weathering sequence. Phosphate sorption capacity was high in the 4.3 ka soils likely due to amorphous soil constituents. A change towards 2:1-type crystalline clays after 26 ka of soil weathering led to weaker P sorption and stronger desorption, and acidification and increased P occlusion in Al and Fe (hydr)oxides became an important factor for microbial P limitation in the older soils.

Our results reveal striking differences in soil properties on the Galápagos Islands, suggesting relatively little nutrient constraints for soil microbes, despite strong P sorption, in the younger volcanic soils but growing P limitation in the older, highly weathered soils. These observations have important bearings on nutrient cycling and may therefore also affect the evolution of plant and animal species on this unique archipelago.

How to cite: Keiblinger, K. M., Socianu, S., Rechberger, M., Gerzabek, M., and Zehetner, F.: Microbial phosphorus limitiation with soil age along a chronosequence on the Galapagos Islands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19011, https://doi.org/10.5194/egusphere-egu24-19011, 2024.

EGU24-20517 | Posters on site | BG1.4

A spatial perspective on internal phosphorus cycling in morphologically complex eutrophic lakes: the importance of stratification 

Tom Jilbert, Siqi Zhao, Jussi Vesterinen, and Juha Niemistö

Many eutrophic lakes suffer from long term accumulation of legacy phosphorus (P) in sediments. Repeated cycling of P between sediments and water column leads to delayed recovery from eutrophication even after abatement of external loading. Moreover, in complex multi-basin lake systems, legacy P can be internally redistributed over time, leading to spatial heterogeneity in regeneration and burial of P and consequent impacts on water quality. Few studies have attempted to map such internal variability in individual lakes in the context of understanding long term recovery from eutrophication. Here we use a combination of sediment trap deployments through one full stratification cycle (May-October 2021), sediment core biogeochemical analyses, and mass balance calculations, to quantify P cycling in Lake Hiidenvesi, a dimictic lake with 5 sub-basins in southern Finland. We show that exchange of P between sediments and water column is more intense in shallow (approximately 0-10 m depth) non-stratified sub-basins, due to both sediment resuspension and diffusive fluxes across the sediment-water interface. In contrast, deeper stratified sub-basins serve as P sinks by promoting sedimentation in relatively quiescent conditions. Due to lateral exchange of water and suspended materials between sub-basins, P is shuttled towards long term burial in deeper, downstream sub-basins. Budget calculations show that net sediment P burial exceeds external loading on the whole-lake scale, indicating a long-term trend towards recovery from eutrophication. However, temporary retention and repeated recycling of legacy P in the shallower upstream sub-basins continues to impact negatively on water quality, despite external loading reductions. The results have implications for understanding the timescales of recovery and for targeting restoration actions aimed at modifying internal P cycling to improve water quality.

How to cite: Jilbert, T., Zhao, S., Vesterinen, J., and Niemistö, J.: A spatial perspective on internal phosphorus cycling in morphologically complex eutrophic lakes: the importance of stratification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20517, https://doi.org/10.5194/egusphere-egu24-20517, 2024.

EGU24-20917 | Posters on site | BG1.4

Controls on global patterns of dissolved organic phosphorus utilisation in the surface ocean 

Bei Su, Xianrui Song, Solange Duhamel, Claire Mahaffey, Clare Davis, Ingrid Ivančić, Shuo Zhou, and Jihua Liu

          Utilisation of dissolved organic phosphorus (DOP) by marine microbes as an alternative phosphorus (P) source when phosphate is scarce can help sustain non-Redfieldian carbon:nitrogen:phosphorus ratios and efficient ocean carbon export. Alkaline phosphatase (AP) is an important enzyme group that facilitates the remineralisation of DOP to phosphate and thus its activity is a promising proxy for DOP-utilisation, particularly in P-stressed regions. In order tounderstand the global spatial patterns and rates of microbial DOP utilization and their environmental controls, we compiled a Global Alkaline Phosphatase Activity Dataset (GAPAD) with 4083 measurements collected from 79 published manuscripts and one database and further investigated the possible mechanisms controlling global ocean APA. We find that DOP concentration, salinity, excess phosphate (P*), and chlorophyll a concentrations are critical factors in predicting global patterns of APA, which together explain as much as 39% of the variance in the observed APA dataset. Among all environmental factors, DOP concentration explains the most variance in the observed APA data and is negatively correlated with APA. P* is negatively correlated with APAwhile chlorophyll a concentration is positively correlated.  Moreover, wind speed, dust iron deposition rate, and zinc concentration are also possible important environmental factors controlling APA. Using structural equation modeling, DOP and P* concentrations have a total negative effect on APA of -0.36. and -0.2 respectively, while chlorophyll a concentration and salinity have a total positive effect of 0.16 and 0.24. Via a set of numerical competition experiments between an AP-producing phytoplankton and a non AP-producing competitor, AP-producing phytoplankton are found to have an advantage in regions with low P*, but only alongside sufficiently high DOP and DIN concentrations. This trend arises due to the trade-off between P acquisition and N allocation to AP synthesis and is not affected by varying the model assumptions regarding nutrient supplies, N-demand, and key physiological traits.  Extending our results to the global ocean using DIN, DIP, and DOP datasets enables us to pinpoint key regions where optimal conditions for DOP-utilisation are prevalent. These findings align closely with the patterns illuminated by our APA dataset. Our results show that on a global scale, when phosphate limitation is severe, plankton utilize DOP through producing AP, and this will help understand the biogeographical shift of different microbial groups in response to future climate change. Further work is needed to include the parallel role of the trace metal co-factors iron and zinc in driving AP synthesis and its spatial distribution in our modelling experiments.

How to cite: Su, B., Song, X., Duhamel, S., Mahaffey, C., Davis, C., Ivančić, I., Zhou, S., and Liu, J.: Controls on global patterns of dissolved organic phosphorus utilisation in the surface ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20917, https://doi.org/10.5194/egusphere-egu24-20917, 2024.

EGU24-21673 | Posters on site | BG1.4

Beyond “Redfield ratio”: Oxygen exchange between water and phosphate can provide insights into carbon dynamics in soils 

Federica Tamburini, Maja Siegenthaler, and Chiara Pistocchi

Phosphorus (P) is essential for cellular metabolism. Many metabolic pathways and processes depend on it, including energy production through ATP, DNA and RNA synthesis, and protein phosphorylation during post-translational signaling adaptation.

In marine sediments and oceanic water, the stoichiometric ratio between carbon and phosphorus has been found to vary with latitude, but in algae and phytoplankton, which are responsible for primary production and CO2 uptake from the atmosphere, this ratio is relatively constant. This constant ratio is known as the Redfield ratio and  it is often used as a constraint in modeling.

In soils, where microorganisms control nutrient cycling and consequent carbon sequestration, the C:P is more variable both in soil and microbial biomass. First, microorganisms exhibit a wide range of metabolic adaptations to environmental pressure, and the physical and mineralogical properties of the soil play a significant role in nutrient control, e.g. through sorption/desorption reactions. Due to these complexities, using nutrient ratios for modeling soil organic carbon dynamics and predicting the impact of anthropogenic influences on global changes is challenging. Is it possible to find a connection between carbon and phosphate that encompasses the "Redfield" ratio and reflects their tight link in cellular metabolism?

By examining the oxygen isotope composition in inorganic phosphate (δ18O-Pi), we can determine the extent of oxygen exchange between water and phosphate, which is controlled by biological processes. Intracellularly, this exchange occurs through phosphoryl transfer, a fundamental process in cellular phosphate cycling. 

During the last 10 years, we conducted a series of incubation experiments where we measured CO2 respiration and δ18O in resin and microbial cytosolic phosphate in soils from different environments. These incubations were performed with waters of varying 18O isotopic composition. By analyzing δ18O in microbial cytosolic phosphate at the beginning and end of the incubation, we could measure the level of oxygen exchange between water and phosphate.

Comparing the results from these incubations, we observed a significant correlation between the percentage of oxygen exchange and the cumulative CO2 respired during the incubation. This correlation was consistent  through different soil ages, mineralogy, phosphate levels, and incubation length. When normalizing the percentage of oxygen exchange to moles of oxygen exchanged per moles of carbon respired, it appears that for every mole of oxygen exchanged due to phosphoryl transfer, there is a nearly fixed amount of carbon respired. This suggests that the moles of oxygen exchanged through phosphoryl transfer recorded in soil microbial phosphate can provide information about metabolic carbon expenditure.

This finding would provide new insights on the link between P and C in soil microbial biomass. The controlled nature of the incubation experiments may not fully reflect the biological activity in soil environments, so it would be necessary to perform field-based incubation experiments to confirm the link between carbon respiration and phosphorus microbial cycle. This information could potentially improve our understanding of carbon dynamics and be used for further modeling purposes.

How to cite: Tamburini, F., Siegenthaler, M., and Pistocchi, C.: Beyond “Redfield ratio”: Oxygen exchange between water and phosphate can provide insights into carbon dynamics in soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21673, https://doi.org/10.5194/egusphere-egu24-21673, 2024.

EGU24-21972 | Posters on site | BG1.4

Exploring spatial distribution and characterization of inorganic and organic phosphorus in temperate soils using NanoSIMS  

Kaiyu Lei, Franziska Barbara Bucka, Carmen Höschen, Yahan Hu, and Ingrid Kögel-Knabner

For a comprehensive understanding of the phosphorus (P) storage and cycling in temperate soils, it is necessary to explore further the bonding pathways of organic P (Po) and inorganic P (Pi) to mineral surfaces and soil organic matter (SOM), and their interconnections with organic carbon (OC) at a micro-scale other than conventional bulk analysis. In the past decade, nanoscale secondary ion mass spectrometry (NanoSIMS) has been increasingly recognized as a promising imaging technique to understand soil biogeochemical processes, particularly in exploring organo-mineral associations in soils at the microscale (Mueller et al., 2023). However, its application in studying P, and the identification and distinction of Po and Pi remains challenging, hindering a comprehensive understanding of the P cycling in soils.

In our study, four temperate soil types, including Cambisol, Luvisol, Phaeozem and Fluvisol, were taken from Bavarian Forest in South-East Germany. The pH of these soils ranges from 5.4 to 6.3, with poor to medium P stocks but distinct Po stocks in fine fractions (<20 μm). Previous bulk studies have hinted at different pathways in P bonding to mineral surfaces and SOM. NanoSIMS was employed to further explore and visualize these bonding pathways. Recent advancements in NanoSIMS technology, particularly improved O- sources for cation detection and the capability for 31P- and 31P16O2- detection enable us to identify and distinguish Po and Pi at a microscale by 31P16O2-/31P- ratio, in which a lower ratio in specific areas corresponds to a more dominant presence of Po, and vice versa.

From NanoSIMS images, preliminary results reveal that a proportion of Po associates with either clay minerals or Fe (hydr)oxdies without assimilating into SOM. This Po fraction is suspected to originate from highly decomposed SOM, where N has either been assimilated by microorganisms or leached away, and Po is stabilized to mineral surfaces due to strong bonding strength. In contrast, the Po assimilated into SOM is associated with various cations, including Ca, Al and Fe, which may suggest the origin from particulate organic matter. Interestingly, the fine plant residue is depleted in Po in the fine fraction.

In conclusion, our study provides valuable insights into distinguishing different bonding pathways of these P forms within clay minerals, Fe (hydro)oxides, and SOM by using advanced NanoSIMS data, and emphasizes the interconnection with OC and Po and Pi in the fine fraction.

Reference: Mueller, C. W., Hoeschen, C., Koegel-Knabner, I., 2023. Understanding of soil processes at the microscale—Use of NanoSIMS in soil science. Encyclopedia of Soils in the Environment (Second Edition). Elsevier. 10.1016/B978-0-12-822974-3.00045-8

How to cite: Lei, K., Bucka, F. B., Höschen, C., Hu, Y., and Kögel-Knabner, I.: Exploring spatial distribution and characterization of inorganic and organic phosphorus in temperate soils using NanoSIMS , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21972, https://doi.org/10.5194/egusphere-egu24-21972, 2024.

EGU24-22214 | Orals | BG1.4

Heterogeneous Dissolved Organic Phosphorus Composition and Bioavailability in Marine Systems 

Sonya Dyhrman, Kathleen Ruttenberg, Danielle Hull, and Sherril Leon Soon

The critical role of Dissolved Organic Phosphorus (DOP) in supporting primary production has spurred efforts to characterize DOP composition so that insight may be gained into its bioavailability and cycling in aquatic systems. The degree to which DOP is bioavailable to primary producers will determine, in part, the extent of carbon uptake and sequestration.  Ascertaining DOP composition has proven to be an analytically challenging endeavor.  As a consequence, the DOP pool remains poorly characterized, and our predictive power relative to DOP-bioavailability, and coupled carbon cycling, remains limited. Analytical impediments to characterizing DOP composition in natural waters include its low concentration, requiring pre-concentration before compositional features can be probed via spectroscopy, and the fact that organic phosphorus compounds are not easily amenable to standard organic geochemical approaches, such as chromatographic or mass spectrophotometric methods, particularly in salt water. While 31-Phosphorus Nuclear Magnetic Resonance (31P-NMR) spectroscopy has provided intriguing information on the distribution of the 2 major DOP compound types (phosphoesters, phosphonates), the crucial question of DOP bioavailability cannot be addressed by this method. We present novel DOP molecular weight distribution and bioavailability data, generated using a coupled sequential ultrafiltration-bioavailability approach from a marine water column depth profile and locations across a gradient in phosphate concentration in the Atlantic and Pacific Oceans.  There is substantial compositional variability in the marine DOP pool, both in the pattern of DOP molecular weight distribution at different sites, as well as the distribution of bioavailable mono- and diesters of phosphate across molecular weight fractions.  In some cases, a substantial fraction of DOP in different molecular weight size classes is non-reactive to the two enzymes used to assay potential bioavailability, raising the interesting possibility of non-bioavailable DOP. The significance of recognizing that the oceanic DOP pool is compositionally heterogeneous, and variably bioavailable, lies in that fact that such information is a prerequisite to building ecosystem models that capture the influence of P biogeochemistry on primary production and carbon cycling in aquatic systems.

How to cite: Dyhrman, S., Ruttenberg, K., Hull, D., and Leon Soon, S.: Heterogeneous Dissolved Organic Phosphorus Composition and Bioavailability in Marine Systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22214, https://doi.org/10.5194/egusphere-egu24-22214, 2024.

EGU24-276 | Orals | BG3.10 | Highlight

Controls of atmospheric carbon transfer to soil by root exudates 

Melanie Brunn

The interaction between plants and soil plays a decisive role in controlling the formation of soil organic matter (SOM) - a critical factor for the functioning of ecosystems and the mitigation of climate change. Carbon compounds that plants release into the soil as root exudates have important impacts on the stability of SOM and can shift with climate change. Yet, a generalizable understanding of the biotic and abiotic controls on the relationships between plant-soil carbon exchanges and large-scale carbon fluxes and SOM formation is still lacking.

Here, I compile data from different forest ecosystems to illustrate: 1) the response of root exudates in distinct ecozones to species mixing, 2) the impact of drought and recovery on plant-soil interactions, and 3) the quantitative correlation between rhizodeposition and ecosystem carbon uptake, as well as its association with SOM formation.

Observations point to a connection between carbon exudation and root growth, with greater root growth leading to reduced exudation rates and vice versa. However, exudation rates across diverse ecozones were highly responsive to even minor alterations in the sampling method, suggesting careful considerations when comparing datasets from different studies. The rhizosphere showed increased levels of stabilized SOM that endured after drought, suggesting the potential for rhizodeposition to enhance the preservation of soil carbon.

Current data indicates that a substantial fraction of carbon in the atmosphere is allocated towards root exudates, likely serving as a crucial element in the ability of ecosystems to respond to climate change. Understanding plant-soil interactions in a global context requires aligning sampling methods within an ecozonal context.

How to cite: Brunn, M.: Controls of atmospheric carbon transfer to soil by root exudates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-276, https://doi.org/10.5194/egusphere-egu24-276, 2024.

EGU24-2866 | Posters on site | BG3.10

Soil warming influences organic carbon composition at the microscale in Blodgett Forest 

Mike Rowley, Jasquelin Pena, Matthew Marcus, Rachel Porras, Elaine Pegoraro, Margaret Torn, and Peter Nico

The impact of warming on the soil organic carbon (SOC) cycle and its potential positive feedback with increasing atmospheric CO2 concentrations is of global concern. Earth System Models currently predict that warming will increase soil CO2 efflux faster than net primary productivity (Crowther et al., 2016); yet there are still large uncertainties associated with these modelled estimates, which can be reduced by process-based observations from whole-soil warming experiments. To identify the influence of 7.5 years of +4°C whole-soil warming on SOC and its elemental associations at the microscale, we used scanning transmission X-ray spectromicroscopy at the carbon K-edge (STXM C NEXAFS). We focused our analyses on soils collected from three depth intervals (10-20, 40-50, 60-70 cm) at the control and warmed plots from the whole-soil warming project at Blodgett Experimental Forest (granitic Alfisols). Relative to control plots, samples from the warmed plots had elevated aromatic and phenolic C content, and this observation was most pronounced in the 40-50 cm depth samples. This result differed from previous observations at the bulk-soil level (Ofiti et al., 2021), which demonstrated a decrease in the relative abundance of these compound classes with warming, particularly at depth. These contrasting results may be explained by a difference in SOC dynamics at the bulk scale relative to the microscale, with STXM investigating SOC bound in organo-mineral assemblages at the microscale, while bulk soil measurements include larger partulate organic matter. It could also be indicative of the changes in root dynamics with warming that were also recorded in Ofiti et al. (2021). The STXM data also showed that organic carbon was strongly associated with calcium in these acidic soils, which had a more plant-like nature than C associated with iron. This supports similar observations, which were recently made in soils from an acidic grassland soil series at Point Reyes, California that had developed in a different parent material (sandstone; Rowley et al., 2023). This study highlights the importance of investigating how organo-mineral or -metal associations will respond to changing environmental conditions at various analytical scales. 

References

Crowther et al., 2016. Quantifying global soil carbon losses in response to warming. Nature 540(7631), 104-108.
Ofiti, et al., 2021. Warming promotes loss of subsoil carbon through accelerated degradation of plant-derived organic matter. Soil Biology and Biochemistry 156, 108185.
Rowley et al., 2023. Association between soil organic carbon and calcium in acidic grassland soils from Point Reyes National Seashore, CA. Biogeochemistry 165, 91-111.

How to cite: Rowley, M., Pena, J., Marcus, M., Porras, R., Pegoraro, E., Torn, M., and Nico, P.: Soil warming influences organic carbon composition at the microscale in Blodgett Forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2866, https://doi.org/10.5194/egusphere-egu24-2866, 2024.

EGU24-3377 | Posters on site | BG3.10 | Highlight

Long-term soil warming decreases soil microbial necromass carbon by adversely affecting its production and decomposition  

Xiaofei Liu, Ye Tian, Jakob Heinzle, Erika Salas, Steve Kwatcho-Kengdo, Werner Borken, Andreas Schindlbacher, and Wolfgang Wanek

Microbial necromass carbon (MNC) accounts for a large fraction of soil organic carbon (SOC) in terrestrial ecosystems. Yet our understanding of the fate of this large carbon pool under long-term warming is uncertain. Here we show that 14 years of soil warming (+4 °C) in a temperate forest resulted in a reduction of MNC by 11% (0-10 cm) and 33% (10-20 cm). Warming caused a decrease in the production of MNC due to a decline in microbial biomass carbon and reduced microbial carbon use efficiency. This reduction was primarily caused by warming-induced limitations in available soil phosphorus, which, in turn, constrained the production of microbial biomass. Conversely, warming increased the activity of soil extracellular enzymes, specifically N-acetylglucosaminidase and leucine-aminopeptidase, which accelerated the decomposition of MNC. These findings collectively demonstrate that decoupling of MNC formation and decomposition underlie the observed MNC loss under climate warming, which could affect SOC content in temperate forest ecosystems more widespread.

How to cite: Liu, X., Tian, Y., Heinzle, J., Salas, E., Kwatcho-Kengdo, S., Borken, W., Schindlbacher, A., and Wanek, W.: Long-term soil warming decreases soil microbial necromass carbon by adversely affecting its production and decomposition , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3377, https://doi.org/10.5194/egusphere-egu24-3377, 2024.

The impact of warming on the carbon cycling of terrestrial ecosystems determines the carbon cycle-climate change feedback and the future climate. Specifically, how warming affects the carbon cycling in deep soils (>20 cm) remains uncertain, because most of existing manipulation experiments only warm surface soils (<20 cm). In 2018, we started a Total-soil-warming Experiment in an Alpine Meadow (TEAM). We have maintained year-round warming (+4 oC) of the whole soil profile (0-100 cm) in an alpine meadow on the Tibetan Plateau. We anticipate running the experiment for >10 years. I will present an overview and some of the results of TEAM during the first 5 years (2018-2023), including treatment effects on plant communities, soil and microbial properties, and ecosystem processes.

First, warming did not significantly affect plant richness and diversity, and above- and belowground biomass and productivity, but changed the relative proportion of plant functional groups in aboveground biomass (decrease in legumes and increase in forbs). Second, soil physico-chemical properties (including organic carbon and total nitrogen concentrations) and microbial community characteristics (such as carbon use efficiency, community diversity and composition) throughout the profile were mostly unresponsive to warming, although they changed dramatically (e.g. declined) with depth. Third, warming significantly stimulated soil respiration (and microbial respiration) and soil N2O emission, but did not significantly change root respiration and soil CH4 uptake. Lastly, warming promoted plant growth, soil microbial respiration, and soil fauna feeding by 8%, 57%, and 20%, respectively, but caused dissimilar changes in their phenology during the growing season. Overall, although ecosystem carbon stocks were not significantly affected by the whole-soil-warming, some processes and variables of the alpine grassland ecosystem showed significant responses. We will continue to monitor these processes and variables to gain a long-term mechanistic understanding of the response of ecosystem carbon cycling to whole-soil-warming in the alpine grassland.

How to cite: Zhu, B.: Whole-soil warming effects on carbon cycling of an alpine grassland ecosystem on the Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4917, https://doi.org/10.5194/egusphere-egu24-4917, 2024.

Climate warming has caused widespread global concern. However, how warming affects soil microbial diversity, richness, community structure and biomass is still poorly understood. Therefore, this study conducted a meta-analysis of 1044 observations from 144 publications by collecting relevant data on a global scale. The results showed that warming significantly altered soil temperature, soil water content, community structure of soil bacteria and fungi, and beta diversity of fungi. Warming decreased soil microbial diversity, richness and biomass, but the overall effect was not significant, while warming increased soil physicochemical and plant biomass indicators. Soil bacteria and fungi showed opposite trends in response to warming (e.g., the weighted mean effect values of the bacterial Shannon index, OTU Richness, and PLFA were all negative, whereas those for fungi were all positive), with fungi being more sensitive to warming than bacteria. Model selection analysis indicated that the RR (response ratio) of pH, ecosystem type and warming magnitude are important factors influencing the RR of soil bacterial diversity and richness. In addition, warming significantly decreased the OTU richness of forest soil bacteria and significantly increased the OTU richness of cropland soil fungi. The RR of bacterial richness (Chao1, OTU Richness) was significantly different among ecosystems, whereas that of fungal richness was not. The RR of diversity and richness of soil bacteria showed significant correlations with the RR of pH and warming magnitude. Overall, these findings improve our understanding of soil microbial responses under global warming.

 

How to cite: Wang, X. and Zhu, B.: Warming has differential effects on the diversity, richness and biomass of soil bacteria and fungi, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4980, https://doi.org/10.5194/egusphere-egu24-4980, 2024.

EGU24-5007 | ECS | Posters on site | BG3.10

Bacterial necromass is more responsive to global change than fungal necromass 

Wenao Wu and Biao Zhu

As an important component of soil organic matter (SOM), soil microbial necromass largely determines the dynamics of SOM under global change. However, the response of soil microbial necromass to global change is not well understood. Hence, this study conducted a meta-analysis to assess the global response of soil microbial necromass to warming, altered precipitation, nutrient addition, and elevated CO2. Results showed that global change had no significant effects on total necromass carbon (TNC) and fungal necromass carbon (FNC). However, we found that bacterial necromass carbon (BNC) was significantly responsive to warming (+9.70%), increased precipitation (+10.15%), and nitrogen (N) addition (+8.62%). Furthermore, the response of BNC could be regulated by ecosystem types, climate factors, soil properties, and experimental conditions, but the influencing factors under different global change factors could be different. Correlation analysis suggested that the response of BNC was associated with the change of soil pH under warming, while it had a positive correlation with the response of soil microbial biomass carbon under N addition. Overall, this study contributes to the understanding of how soil microbial necromass responds to global change on a global scale, and emphasizes the important role of BNC in SOC dynamics under global change.

How to cite: Wu, W. and Zhu, B.: Bacterial necromass is more responsive to global change than fungal necromass, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5007, https://doi.org/10.5194/egusphere-egu24-5007, 2024.

EGU24-5029 | Orals | BG3.10

Climate change will increase Cd accumulation in spinach leaves 

Marie Muehe, Aleksandra Pienkowska, Alexandra Glöckle, Natalia Sánchez, Shitalben Khadela, Paul-Georg Richter, Ines Merbach, Martin Herzberg, and Thomas Reitz

Metal contamination in agricultural soils poses a notable environmental and health concern. When available in soils, metals can be assimilated and accumulated by crops, emphasizing the potential for human exposure to elevated metal levels through the consumption of contaminated agricultural produce. Our recent research shows that future climate change conditions of +4°C, doubled atmospheric CO2, and reduced soil moisture [1] increases the mobility of the heavy metal Cd in agricultural soils [2]. It remains uncertain whether this climate-augmented Cd bioavailability in agricultural soils transfers into the food chain.

To address this gap in knowledge, we cultivated four varieties of spinach (Spinacia oleracaea) in four soils with diverse geochemistry and heavy metal contents. Spinach, chosen as a model for leafy crops prone to heavy metal accumulation in edible parts, boasts a global production volume of 63 billion kg in 2021 [3]. Under anticipated climatic conditions with +3°C, +300 ppmv CO2 and 10% less water [1], three out of four spinach varieties yielded more edible biomass compared to today’s climate typical for spring spinach with 20°C daytime temperature and 50% water holding capacity. The non-essential heavy metal Cd and the micronutrient Zn proved most responsive to the imposed future climatic conditions, exhibiting increased accumulation in the edible part. Factors such as soil-root transfer and root to shoot translocation will be discussed to elucidate the climate-induced rise in Cd and Zn contents in spinach leaves beyond soil Cd mobility.

Our findings offer significant insights into forecasting future spinach production and quality, applicable to other leafy vegetables, and underscore the importance of addressing combined climate and heavy metal contamination issues to sustain food quality.

 

[1] IPCC, 2021. Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.

[2] Drabesch et al., submitted, Climate induced microbiome alterations increase Cd bioavailability in agricultural soils.

[3] UN Food and Agriculture Organization, 2023. Spinach production in 2021; Crops/Regions/ World/Production Quantity/Year from pick lists.

How to cite: Muehe, M., Pienkowska, A., Glöckle, A., Sánchez, N., Khadela, S., Richter, P.-G., Merbach, I., Herzberg, M., and Reitz, T.: Climate change will increase Cd accumulation in spinach leaves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5029, https://doi.org/10.5194/egusphere-egu24-5029, 2024.

EGU24-6341 | Orals | BG3.10

Drivers of soil carbon emission in warmed tropical soil 

Andrew Nottingham, Erland Bååth, Kirk Broders, Patrick Meir, Maria Montero-Sanchez, Kristin Saltonstall, Alicia Sanjur, Jarrod Scott, and Esther Velasquez

Soil microbes form some of the most diverse biological communities on Earth and are fundamental in regulating the terrestrial carbon cycle. Their response to climate warming could therefore have major consequences for future climate, particularly in tropical forests where high biological diversity coincides with a vast store of soil carbon. We used an in-situ soil warming experiment to test the response of tropical forest soil microbial communities, growth, enzyme activities and respiration to three years of soil warming. We first determined the response to warming of the microbial community composition and asked whether community change was related to a change in the intrinsic sensitivity of microbial growth. Second, we asked whether the response to warming of microbial growth sensitivity could explain the response of heterotrophic soil CO2 emission under in situ warming. The experiment, SWELTR (Soil Warming Experiment in Lowland TRopical forest) consists of five pairs of circular control and warmed plots (whole-profile warming, using buried resistance cables) distributed evenly within approximately 1 ha of semi-deciduous moist lowland tropical forest on Barro Colorado Island, Panama. Each warmed plot is heated across the full soil profile, resulting in a total of 120 m3 of warmed soil for the experiment. For this study we established two subplots per treatment plot that differed with distance to the heating source, thus providing two treatments of, on average, 3ºC and 8ºC warming of surface soils and performed field campaigns during the wet season (when soil moisture was not limiting to microbial activity). Microbial diversity declined markedly, especially of bacteria. As the microbial community composition shifted under warming, many taxa were no longer detected and others, including taxa associated with thermophilic traits, were enriched. The activity of 7 out of 10 measured soil enzyme activities increased with warming. The community shift resulted in an adaptation of growth to warmer temperatures, which we used to specify a microbial model to predict changes in soil CO2 emissions. However, the observed in situ soil CO2 emissions increase exceeded the rates predicted by our model three-fold. Our results show that the soil microbial community and growth response to warming was decoupled from large increases in CO2 emission, which was potentially boosted by an abiotic effect of warming on soil enzyme activity. Our results suggest that warming of tropical forests will have rapid, detrimental consequences both for soil microbial biodiversity and future climate.

How to cite: Nottingham, A., Bååth, E., Broders, K., Meir, P., Montero-Sanchez, M., Saltonstall, K., Sanjur, A., Scott, J., and Velasquez, E.: Drivers of soil carbon emission in warmed tropical soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6341, https://doi.org/10.5194/egusphere-egu24-6341, 2024.

EGU24-6587 | ECS | Orals | BG3.10 | Highlight

Hydrological controls on soil carbon dynamics: from pores to cores 

Kaizad Patel, Vanessa Bailey, Ben Bond-Lamberty, Sarah Fansler, Allison Myers-Pigg, and A. Peyton Smith

Core-scale soil carbon fluxes are ultimately regulated by pore-scale dynamics of substrate availability and microbial access, which are strongly influenced by soil water. The global water cycle is intensifying, and moisture extremes like drought and flood are increasing in frequency and intensity. It is therefore important to understand how these changing moisture regimes will affect carbon availability and fluxes in soils. We conducted two laboratory incubation experiments to investigate how drought and flood altered soil carbon availability and mineralization. Antecedent moisture conditions were found to be an important control on soil carbon availability, as soil respiration and carbon availability showed distinct hysteresis during drying and rewetting. Additionally, when comparing impacts of drought and flood across different soils, the soil carbon response was not consistent across sites, and was influenced by site-level pedological and environmental factors such as soil texture and historic stress conditions. These studies highlight the importance of pore-scale physicochemical and biochemical properties when studying soil biogeochemical transformations at the core scale.

How to cite: Patel, K., Bailey, V., Bond-Lamberty, B., Fansler, S., Myers-Pigg, A., and Smith, A. P.: Hydrological controls on soil carbon dynamics: from pores to cores, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6587, https://doi.org/10.5194/egusphere-egu24-6587, 2024.

EGU24-6894 | ECS | Orals | BG3.10

Increased snow depth and vascular plant species promote Arctic soil methane emissions 

Jung In Kim, Jeongeun Yun, Ji Young Jung, Sung Jin Nam, Jaehyun Lee, and Hojeong Kang

Atmospheric temperatures are steadily rising on a global scale, with the Arctic region experiencing an alarming rate of increase, double that of the global average. This temperature surge not only signifies anticipated changes but also forecasts a consequential rise in winter precipitation. Within the context of climate change, this leads to a significant upturn in net methane (CH4) emissions. During winter, augmented snow depth enhances thermal insulation of the underlying soil, subsequently increasing soil moisture upon melting. This results in warmer and wetter soil conditions, fostering an anoxic environment that stimulates methanogenic activity. Furthermore, methane emissions are accelerated through plant-mediated CH4 transport. Studies propose a potential shift in vegetation communities, favoring vascular species with extensive aerenchyma under warming conditions.

While projections suggest an increase in CH4 flux with greater winter precipitation, the combined effects of heightened snow cover and the presence of vascular plant species on CH4 production remain largely unexplored. This study, conducted using snow fences installed since 2017 in Council, Alaska, aims to unravel the legacy effect of deepened snow during winter and plant-mediated transport on soil CH4 emissions during the growing season (Jul–Aug, 2023). Our investigation involves the analysis of soil CH4 flux, soil chemical properties, and microbial abundance and communities in both control and high snow depth (HS) conditions, comparing bare soil and Eriophorum angustifolium dominant soil.

Results indicate that deeper snow significantly increased the average CH4 emission rate from 2.65 to 16.6 mg m-2 day-1. The presence of E. angustifolium amplified CH4 emission strength in both control and HS conditions (63.4 and 116 mg m-2 day-1, respectively). Increased CH4 emissions in HS conditions were primarily driven by enhanced carbon source availability and higher ammonium concentrations. Deeper thaw depth in HS conditions increased carbon source availability, particularly in vegetated soils, promoting methanogenic activity. Higher ammonium concentrations in HS conditions contributed to inhibiting methanotrophs from oxidizing CH4.

Consistent variations in soil characteristics were observed at a microbial scale, confirming increased methanogenic activity and decreased methanotrophic activity in HS conditions, for both bare and vegetated soil. These findings underscore the synergistic legacy effect of increased CH4 flux resulting from the complex interaction between deepened snow depth and the presence of vascular species, creating conditions conducive to elevated CH4 production during the growing season.

How to cite: Kim, J. I., Yun, J., Jung, J. Y., Nam, S. J., Lee, J., and Kang, H.: Increased snow depth and vascular plant species promote Arctic soil methane emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6894, https://doi.org/10.5194/egusphere-egu24-6894, 2024.

EGU24-7338 | ECS | Posters on site | BG3.10

Increased decomposition of root-derived biomass by warming in a temperate forest soil is depth-dependent 

Binyan Sun, Cyrill Zosso, Guido Wiesenberg, Elaine Pegoraro, Margaret Torn, and Michael Schmidtt

Increased decomposition of root-derived biomass by warming in a temperate forest soil is depth-dependent

 

Sun B, Zosso, C.U., Wiesenberg GLB, Pegoraro E., Torn MS, Schmidt MWI

 

The IPCC climate scenario RCP 8.5 suggests temperate regions will warm 4°C by 2100, which could accelerate soil carbon loss, greenhouse gas release, and further promote global warming. Despite low carbon concentrations, subsoils (> 30 cm) store more than half of the total global soil organic carbon stocks. However, it remains largely unknown how this deep soil carbon will respond to warming and how root-derived carbon, a potentially slower cycling part of soil carbon, could contribute to long-term carbon sequestration in soil.

After three years of in-situ root-litter incubation, we i) quantified decomposition of root-litter at different depths in a +4°C warming field experiment, ii) assessed whether root-derived polymers degraded differently in warmed and ambient temperature conditions, and iii) identified decomposition products of plant biomass remaining.

In a field warming experiment in a temperate forest (Blodgett Forest, Sierra Nevada, CA, USA), 13C-labelled root-litter was incubated at three soil depths (10-14, 45-49, 85-89 cm) in soil cores for one and three years at ambient temperature and +4°C. For bulk soil, we measured carbon and nitrogen concentrations, and δ13C isotope composition. We further quantified and determined the δ13C isotope composition of microbial (PLFA) and root-derived (suberin) molecular marker.

The results showed that:

1) In bulk soil, on average there was higher 13C-excess in the control compared to heated plots in topsoil (10-14 cm), meaning more decomposition and loss in the heated plots, but there was no difference in subsoils (45-49, and 85-89 cm).

2) The root-specific molecular marker suberin indicated that warming accelerated the loss of root biomass in topsoil. However, this trend was not found in subsoils and this could be due to scattered hotspots of microbes in subsoil. Nevertheless, 13C-excess of suberin biomarkers was higher than that of bulk soil carbon, which indicates a slower turnover of hydrolysable lipids in root litter compared to bulk root carbon.

3) With warming, the concentrations of hydrolysable lipids (normalized to carbon content) increased at all three depths. This indicates a potential preferential preservation of hydrolysable lipids. But this could also be attributed to faster litter decomposition and incorporation in mineral soil due to warming, especially in the topsoil.

In conclusion, warming increased decomposition of root-derived carbon and hydrolysable lipids in topsoil but not in subsoil. On the other hand, warming also increased plant-derived input into topsoil which accelerated the turnover of carbon at this shallower depth. Root-derived hydrolysable lipids in roots are relatively less decomposable than bulk tissues and could be preferentially preserved with warming. Therefore, warming could accelerate the turnover of root-derived carbon, but this is strongly dependent on depth and whether the tissues are available to microorganisms.

How to cite: Sun, B., Zosso, C., Wiesenberg, G., Pegoraro, E., Torn, M., and Schmidtt, M.: Increased decomposition of root-derived biomass by warming in a temperate forest soil is depth-dependent, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7338, https://doi.org/10.5194/egusphere-egu24-7338, 2024.

EGU24-7359 | Orals | BG3.10

Exploring the interaction between global changes, soil properties and vegetation patterns on soil phosphorus transformation in alpine grasslands of the Tibetan Plateau 

Zuonan Cao, Qingzhu Gao, Thomas Scholten, Peter Kühn, Jin-sheng He, Zhen-Huan Guan, Hasbagan Ganjurjav, Guozheng Hu, and Shanting Hu

The grassland ecosystems of the Tibetan Plateau have witnessed substantial transformations in recent decades, driven by various global factors, including alterations in temperature and precipitation, nitrogen (N) deposition, and regional effects. Despite documented shifts in species richness and distribution towards higher elevations, there is a scarcity of comprehensive plant and soil data along elevation gradients in alpine grasslands. The intricate interplay of soil properties and nutrient supply on vegetation patterns at high altitudes, particularly the response of the "grass-line" to global warming, remains unexplored. To bridge these knowledge gaps, our research investigated the impacts of global changes, specifically warming and N deposition, and soil properties on soil phosphorus (P) transformation and plant P uptake. Leveraging insights from long-term nutrient addition experiments, random sampling, and open-top chamber experiments along elevation gradients in an alpine grassland on the northeastern Tibetan Plateau, the study delved into soil properties such as texture, bulk density, soil organic carbon (SOC), and soil P fractions. Furthermore, it explores plant and microbial P pools, P acquisition strategies, and biomass. Results revealed that N input had a discernible effect on plant P requirements, particularly under conditions of deficient soil available P. Changes in P acquisition strategies wielded a more substantial influence on community structure and composition than alterations in root traits. The addition of P significantly impacted plant growth, signifying a shift from nitrogen to P limitation with increased N input. Soil properties exhibited variations among sites, while pH remained stable in the 0–10 cm soil depth due to the adequate levels of calcium and magnesium in the soil, which could buffer the impact of N deposition on soil acidification in the grassland ecosystem. Strong positive correlations observed between organic P pools, SOC, and total N underscored the pivotal role of soil organic matter in sustaining soil P reserves. More importantly, P limitation did not emerge as the primary factor propelling grasses to higher elevations; instead, other soil properties and nutrients might play a key role. These findings underscore the importance of specific combinations of soil properties in constraining plant growth on the northeastern plateau, thereby influencing biodiversity and biomass production. This research highlights the factors influencing effective soil nutrients and provides valuable insights for predicting the impact of global changes on the stability and productivity of alpine grassland ecosystems.

How to cite: Cao, Z., Gao, Q., Scholten, T., Kühn, P., He, J., Guan, Z.-H., Ganjurjav, H., Hu, G., and Hu, S.: Exploring the interaction between global changes, soil properties and vegetation patterns on soil phosphorus transformation in alpine grasslands of the Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7359, https://doi.org/10.5194/egusphere-egu24-7359, 2024.

EGU24-9591 | ECS | Orals | BG3.10

The age and sources of respired CO2 from soils of dominant land use types across Switzerland   

Luisa Minich, Margaux Moreno Duborgel, Dylan Geissbühler, Annegret Udke, Ciriaco McMackin, Lukas Wacker, Philip Gautschi, Markus Egli, and Frank Hagedorn

Soil CO2 efflux is one of the largest C fluxes between terrestrial ecosystems and the atmosphere and originates from different sources such as rhizosphere respiration and the mineralization of various soil organic matter components. Alterations of soil respiration induced by environmental changes, such as climate and land use change, can thus affect atmospheric CO2 levels. Land use regulates soil CO2 fluxes and their source contributions through various factors such as vegetation type, root density, nutrient input, and management. Soil CO2 fluxes from different land use types are likely to vary in their susceptibility to climate change induced perturbations. However, a systematic comparison of the age and sources of the soil CO2 efflux between different land use types remains elusive. Isotopic techniques using radiocarbon (14C) and stable carbon (13C) represent a powerful approach to identify the sources of soil CO2 fluxes. In this study, we investigated how land use affects the age and sources of soil-respired CO2 across Switzerland and in different seasons by using radiocarbon and stable isotopic approaches.

We measured in situ rates and isotopic signatures (14C, 13C) of soil-respired CO2 in summer and winter from 18 sites of six dominant land use types in Switzerland: forests, croplands, managed peatlands (original and covered with mineral soil), and grasslands (lowland and alpine). The sites vary in their physico-chemical soil properties and span a climatic as well as elevational gradient from 400 to 3000 m a.s.l. across Switzerland. We further disentangled source contribution (autotrophic vs. heterotrophic respiration) to total soil respiration for each site by separating 14C, and 13C signatures of CO2 derived from root and soil incubations.

In summer, the age of in situ soil-respired CO2 increased from lowland grasslands towards alpine grasslands, forests, croplands, and peatlands. We attribute this pattern to an increase of the mean age of soil organic matter along this trajectory. Additionally, we assume a decreasing contribution of rhizosphere respiration from grasslands to forests and arable land. We found managed peatlands to be hotspots of old carbon release, with the respired CO2 being around 500 to 1500 years old. Grasslands released the most modern CO2, in the range of contemporary atmospheric 14CO2 levels. Within grassland sites, we observed an increased age of soil-respired CO2 with increasing elevation (lowland towards alpine) which we attribute to slower C turnover in alpine areas due to cooler climatic conditions. CO2 respired from forest soils originates from bomb-derived decadial old carbon, indicating a reduced turnover as compared to grasslands. Isotopic data of CO2 derived from soil and root incubations will provide insights into source contribution.

How to cite: Minich, L., Moreno Duborgel, M., Geissbühler, D., Udke, A., McMackin, C., Wacker, L., Gautschi, P., Egli, M., and Hagedorn, F.: The age and sources of respired CO2 from soils of dominant land use types across Switzerland  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9591, https://doi.org/10.5194/egusphere-egu24-9591, 2024.

Due to persistent low temperatures, permafrost ecosystems experience constraints in nitrogen (N) turnover, resulting in long-term ecosystem nitrogen limitation. Climate warming would induce the release of N trapped in permafrost, making it available for plant growth and thereby enhancing ecosystem carbon sequestration. Additionally, increased soil N availability would alleviate nutrient limitations for soil microorganisms, promoting greenhouse gas emissions through enhanced soil organic matter decomposition. Against this background, it is crucial to resolve the response of N cycling in permafrost ecosystems to warming, to accurately understand the feedbacks between permafrost carbon-nitrogen dynamics and climate warming. Given the low N deposition in permafrost zones, biological nitrogen fixation (BNF) serves as the primary N input for ecosystems (~50-80% of the annuals). Nitrogen-fixing microbes in moss and soil play crucial roles in BNF in permafrost ecosystems, through symbiotic and autotrophic pathways. Warming may induce alteration in moss and soil characteristics (e.g. moss and soil drying), which would subsequent affect BNF in moss and soil. However, it remains unclear whether microbial BNF in moss and soil would exhibit contrasting responses to warming, and how active nitrogen-fixing microbes modulates such responses. To address these questions, we performed an interactive experiment involving warming and moss removal (warming vs. ambient × moss removal vs. retention) in response to whole-ecosystem warming at the Simulate Warming at Mountain Permafrost (SWAMP). In the in situ labeling procedure, we took two soil columns (10 cm in diameter and in depth) in the surface of each plot, separated them in the middle, and placed them in two incubation container with a dividers, designing one side for moss removal and the other side for moss retention. The two containers were filled separately with 10% 14N2 and 15N2, incubated in situ for 7 days to determine the BNF rate. In the in-house experiment, we employed the 15N-DNA Stable-Isotope Probing to elucidate changes in active microbial groups engaged in BNF, allowing us to uncover their impacts on regulating BNF to warming. Warming resulted in a significant reduction of moss cover by 37.8%. Concurrently, BNF rate significantly increased under warming conditions, especially in the moss-retention treatment. Conversely, warming did not alter BNF rate in the moss-removal treatment. Such finding suggested that warming enhance BNF rate primarily by stimulating a higher microbial BNF rate in moss rather than in soil. The results of microbial functional genes showed that, for moss, although warming didn’t affect the richness of nifH genes, but significantly reduced the Shannon-Wiener index and evenness, leading to an altered functional structure; for soils, warming didn’t change functional structure or any microbial α-diversity indices of nifH genes. These results suggest that the potential for BNF by moss would be further stimulated under warming, resulting in a higher N fixation efficiency. These gains may compensate for the decline in ecosystem-level BNF triggered by the reduction in moss cover. In other words, N supply from BNF in permafrost ecosystems will not decrease due to the trade-off between decreased cover and enhanced BNF ability for moss in a warmer scenario.

How to cite: Bai, Y., Zhou, W., and Yang, Y.: Contrasting responses of biological nitrogen fixation in soil and moss to ecosystem warming in an alpine permafrost ecosystem, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9859, https://doi.org/10.5194/egusphere-egu24-9859, 2024.

Atmospheric nitrogen deposition was artificially increased for 27 years (1995-2022) by sprinkling rain water enriched with NH4NO3 (+22 kg ha-1 y-1 N) to a small headwater catchment in a spruce (Picea abies) forest growing on gley soils at Alptal (central Switzerland). This treatment was compared to a control in a paired catchment design. Nitrate leaching increased already during the first rain events after starting the treatment and continued to increase within the first 5 years. Later, it increased again markedly after part of trees had been girdled then felled in 2010. As shown by 15N labelling, most of the added N remained in the soil. In plots receiving the same treatment, this lowered the C/N ratio, changed the composition of the fungal community and tended to reduce the total microbial biomass, the abundance of Collembola and soil respiration. Soil acidification was observed in those plots located on small mounds but was effectively buffered in topographical depressions. Denitrification was clearly increased, but other processes like mineralisation were not significantly affected. Over time, trees took up about 1/10 of the added N and used it mainly to build larger needles. Their growth was slightly improved, presumably by a better use of the light in their relatively open canopy. Both the soil microbiote and the trees showed signs of limitation by other nutrients like P and Mg, but the poor aeration remained the major limiting factor of the gley soils on this site.

How to cite: Schleppi, P.: Fate and effects of nitrogen added in a long-term experiment to a sub-alpine forest in Switzerland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10159, https://doi.org/10.5194/egusphere-egu24-10159, 2024.

EGU24-10828 | ECS | Orals | BG3.10

Temperature-dependent Degradation of Soil Organic Matter in an Incubation Experiment 

Dario Püntener, Tatjana C. Speckert, Carrie L. Thomas, and Guido L. B. Wiesenberg

Climate change induced warming of soils will have a strong impact on the carbon cycle, especially the decomposition of soil organic matter (SOM) is likely to increase with rising temperature. Alpine regions are especially prone to those changes with earlier and higher expected temperature increase compared to the global average. Carbon cycling in these regions has been also increasingly influenced by land-use changes, such as afforestation, the abandonment of alpine pastures and the resulting bush encroachment, as well as an increasing elevation of the tree line. However, it is still largely unknown how these changes affect the degradation of different compound classes of soil organic matter. A one-year laboratory incubation experiment was carried out to investigate the degradation of SOM at a molecular level.

Two soils with different land-use histories including a soil from an afforested subalpine forest site and a nearby pasture soil from the same site located near Jaun (Canton Fribourg, Switzerland) were incubated under controlled conditions. The incubation was carried out under three different temperatures, the current average growing season temperature (12.5 °C) as a control, as well as two increased temperature treatments of +4 °C (16.5 °C) and +8 °C (20.5 °C) that represent the range of temperature increase expected for Alpine regions under a high emission scenario. To trace the decomposition of organic matter input, 13C-labelled plant litter was added to a subset of the incubated samples. The incubation ran for a period of one year with six different sampling times (14, 28, 56, 168, 360 days).

In samples without labelled litter, the bulk carbon (C) concentration decreased for pasture and forest soils from initial C concentrations of 45.5 and 43.3 mg/g, respectively, by 3.3 % and 5.6 % on average. This is also reflected in lignin concentrations, with a decrease of 13.8 % for pasture and 20.2 % for forest soils.

With litter addition, the degradation was higher than for samples without labelled litter for bulk C, lignin as well as for free extractable lipid fractions. The strongest degradation was observed already during the initial phase of the incubation experiment. E.g., a decrease of more than 50% of the 13C signal of individual lignin phenols could be observed already during the first 14 days, which indicates a fast degradation mainly of the added litter.

In general, the degradation of individual compounds increased with increasing temperature with the highest degradation being observed for the highest temperature treatment.

Higher temperatures have led to increased degradation of SOM during the laboratory incubation experiment, even in seemingly more recalcitrant compounds as lignin. In alpine regions, an expected rise in temperature can therefore lead to increased decomposition of recalcitrant components of SOM. In addition, increased degradation in forest compared to pasture soils indicates a higher vulnerability of forest than pasture soils in alpine regions, which points to complex responses of SOM cycling following land-use changes such as afforestation.

How to cite: Püntener, D., Speckert, T. C., Thomas, C. L., and Wiesenberg, G. L. B.: Temperature-dependent Degradation of Soil Organic Matter in an Incubation Experiment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10828, https://doi.org/10.5194/egusphere-egu24-10828, 2024.

EGU24-11139 | ECS | Orals | BG3.10

Do we obtain valid data from climate change incubations using soils of today? 

Aleksandra Pienkowska, Paula Kosel, Sören Drabesch, Oliver Lechtenfeld, Carsten Simon, Scott Fendorf, Thomas Reitz, and E. Marie Muehe

Assessing climate change effects on soils usually involves conducting comparisons of biogeochemical processes under projected future conditions against ambient ones. This is typically achieved through incubation experiments utilizing today’s soils. However, a significant limitation of relying on present-day soils is the oversight of the ongoing evolution of soils in terms of geochemistry and microbiology over several years in response to future climatic conditions.

This study challenges the traditional approach by asking: Can climate change experiments accurately replicate future biogeochemical processes and their outcomes using soils with today's geochemistry and microbiome? To address this question, we collected oxic and anoxic soils from experimental climate studies, exposed to both present-day and concurrently predicted future climate conditions. We reintroduced these soils with varying climate histories to both sets of climatic conditions (ambient/future), employing a crossover design. This unique experimental setup enables us to discern which biogeochemical processes are influenced by the soil’s historical context and which are contingent on the specific incubation conditions imposed.

For the oxic soil, with an eight-year night temperature increase of up to 2°C coupled with altered precipitation patterns (a 10% increase in spring and autumn, a 20% decrease in summer), our findings indicate a notable influence of soil history on soil respiration, surpassing impacts of the incubation climate. This implies that the historical context of the soil wielded a stronger influence than the specific incubation conditions in shaping organic matter pools and turnover within oxic soils. Conversely, iron(III) reduction, as a pivotal indicator of geochemical evolution, was primarily regulated by incubation conditions related to soil moisture rather than being dictated by the soil’s historical background.

In the anoxic soil, with a one-year treatment of temperature increases of 4°C and doubled atmospheric CO2, a more pronounced reductive iron(III) dissolution occurred in the soil with the future climate history compared to soils with today’s history. This observation suggests that, over the course of soil history, a larger pool of reducible iron became available to microorganisms in soil with a future climate history than in those with today's soil history. Interestingly, the release of arsenic from these ageing iron minerals was higher in soils with a future climate history compared to today’s soils. This indicates that studies investigating arsenic mobility and its impact on crop performances using present-day soils may underestimate the potential environmental consequences of arsenic. Additionally, the history of future soil conditions favoured greater microbial growth than the incubation conditions. However, soil respiration deviated from this pattern, with a predominant increase attributed to the future incubation climate and, to a lesser extent, influenced by soil history.

Complementary data on compositional variations in soil organic matter (LDI-FT-ICR MS) and microbial community (16S rRNA amplicon sequencing) assessing differences based on soil history and short-term experimental conditions will also be presented for both soils.

Our findings indicate that soil history plays a differential role for biogeochemical processes and outcomes of the future with biogeochemical outcomes and temporal trajectories possibly being over- or underinterpreted when studies on climate change utilize present-day soils.

How to cite: Pienkowska, A., Kosel, P., Drabesch, S., Lechtenfeld, O., Simon, C., Fendorf, S., Reitz, T., and Muehe, E. M.: Do we obtain valid data from climate change incubations using soils of today?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11139, https://doi.org/10.5194/egusphere-egu24-11139, 2024.

EGU24-11870 | Orals | BG3.10

Soil carbon-concentration and carbon-climate feedbacks in CMIP6 Earth system models 

Rebecca Varney, Peter Cox, Pierre Friedlingstein, Sarah Chadburn, and Eleanor Burke

Achieving climate targets requires mitigation against climate change, but also understanding of the response of land and ocean carbon systems. In this context, global soil carbon stocks and its response to environmental changes is key. In this presentation, the global soil carbon feedbacks to both changes in atmospheric CO2 and associated climate changes for Earth system models (ESMs) in CMIP6 are quantified. A standard approach is used to calculate the carbon cycle feedbacks, which are defined as soil specific carbon-concentration (βs) and carbon-climate (γs) feedback parameters. Amongst CMIP6 ESMs, it is shown that the sensitivity to CO2 is found to dominate global soil carbon changes at least up to a doubling of atmospheric CO2. However, the sensitivity of soil carbon to climate change is found to become an increasingly important source of uncertainty under higher atmospheric CO2 concentrations.

How to cite: Varney, R., Cox, P., Friedlingstein, P., Chadburn, S., and Burke, E.: Soil carbon-concentration and carbon-climate feedbacks in CMIP6 Earth system models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11870, https://doi.org/10.5194/egusphere-egu24-11870, 2024.

EGU24-12234 | ECS | Orals | BG3.10

Water fluxes under threat by changes in land cover and climate in the Brazilian Cerrado biome 

Dimaghi Schwamback, Edson Wendland, Ronny Berndtsson, and Magnus Persson

In developing countries, the economy is commonly based on agriculture, and combined with the demand for the expansion of urban centers, large natural territories have been converted into agricultural and urban areas. In Brazil, the productive engine for agricultural activities is mainly situated in the wooded Cerrado biome, which has undergone agricultural expansion that led to almost 50% of the native forest vegetation. Besides being well know the role land cover plays on water fluxes, there is still requirement to further coupling with climate change component. The predicted alteration of climate patterns under future climate change scenarios can potentially alter infiltration/runoff rates, aquifer recharge, and soil-water availability for plants, impacting plant growth and development. In this research, we evaluated changes in water fluxes (surface flux, evaporation, soil-water storage, infiltration, bottom flux, and root uptake) at intermediate (2040-2070) and distant future (2071-2100) due to climate change occurring in the Brazilian Cerrado Biome. The two specific objectives included the calibration and validation of the Hydrus model through an eight-year soil moisture monitoring on experimental plots in Cerrado, pasture, and sugarcane areas (i), as well as the incorporation of outcomes from climate change models (10 CMIP6 models under SSP2-4.5 and SSP5-8.5 scenarios) into the validated Hydrus models (ii). The predicted water fluxes were made by Hydrus, a computational that uses the finite element method to achieve the numerical solution of the Richards Equation to describe saturated/unsaturated flows. The study is composed of experimental plots (100 m² and 9% slope) with weather variables and soil moisture fluctuations from 2011 to 2018. We tested different parameter combinations during calibration and found that for sugarcane and pasture simulations plots, saturated soil water content, parameter N in the soil retention function, and saturated hydraulic conductivity were the most sensitive ones and led to better calibration statistics. The first observation is that we cannot point out that climate change is affecting preferentially superficial fluxes rather than sub-superficial ones since each variable has a singular behavior under climate scenarios. Nonetheless, climate change poses a higher threat to certain water fluxes than others, being at a hierarchical (bottom-top) sequence: soil-water storage, bottom flux, infiltration, surface flux, evaporation, and root uptake. The same sequence is applied to all land cover, differing in magnitudes. Comparing the actual water fluxes due changes in to land cover with those due to climate, we concluded that the intensification of land cover change poses a higher risk of water fluxes than those predicted due to climate change. The intricate relationship between land cover and climate necessitates a nuanced understanding to anticipate and mitigate the consequences on water fluxes.

How to cite: Schwamback, D., Wendland, E., Berndtsson, R., and Persson, M.: Water fluxes under threat by changes in land cover and climate in the Brazilian Cerrado biome, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12234, https://doi.org/10.5194/egusphere-egu24-12234, 2024.

EGU24-12840 | ECS | Orals | BG3.10 | Highlight

Soil microbes increase investment into storage compounds during drought conditions. 

Alberto Canarini, Mona Lauritz, Katharina Sodnikar, Thilo Hofmann, Lucia Fuchslueger, Margarete Watzka, Erich M. Pötsch, Andreas Schaumberger, Michael Bahn, and Andreas Richter

The rise of atmospheric CO2 concentrations, with subsequent increase in global warming and the frequency and duration of severe droughts, is altering the terrestrial carbon (C) cycling, with potential feedback to climate change.  Microbial growth, turnover and carbon use efficiency, are major controls of soil carbon fluxes to the atmosphere. Given the prominent role of soil microbial physiology for C cycling, quantifying microbial physiological responses to climate change is essential. Advances in the field now permit the quantification of community-level microbial growth and carbon use efficiency in dry conditions, by introducing stable isotopes in soil water via a water vapor equilibration technique. This has recently allowed, for the first time, to evaluate microbial physiology under drought conditions.

We here used the water vapor equilibration technique to measure deuterium (2H) incorporation into phospholipid and neutral fatty acids (PLFA and NLFA) and polyhydroxybutyrate (PHB). We applied this approach to soil samples collected from a long-term climate change experiment (ClimGrass) where warming, elevated atmospheric CO2 (eCO2) and drought are manipulated in a full factorial combination. Samples were taken in the field at four time points: before drought, one month and two months into drought, and few days after rewetting. We used a high-throughput method to extract PLFAs and NLFAs from soil, as well as a newly developed method to extract PHB, and measured 2H enrichment in these compounds via GC-IRMS.

We showed that during drought, bacterial growth rates are reduced, except for Actinobacteria, which maintain similar mass specific growth rates as compared to control conditions. Similarly, fungi growth rates are not affected by drought. Production of NLFAs (belonging to fungi and gram-negative bacteria) increased up to 4 to 6 folds when compared to production of membrane lipids. PHB production rates did not change compared to control conditions, revealing a higher production per unit of active bacteria. Our study demonstrates that climate change can have strong effects on microbial physiology. Investment into storage compounds is a major strategy present across different soil microbial groups in response to drought. Soil fungi and actinobacteria are key taxa in the microbial response to drought, maintaining most of the growth rates of the soil microbial community.

 

How to cite: Canarini, A., Lauritz, M., Sodnikar, K., Hofmann, T., Fuchslueger, L., Watzka, M., Pötsch, E. M., Schaumberger, A., Bahn, M., and Richter, A.: Soil microbes increase investment into storage compounds during drought conditions., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12840, https://doi.org/10.5194/egusphere-egu24-12840, 2024.

EGU24-13803 | ECS | Posters on site | BG3.10

Microbial diversity controls soil multifunctionality across the European continent 

Xingguo Han, Anna Doménech-Pascual, Joan Pere Casas-Ruiz, Jonathan Donhauser, Karen Jordaan, Jean-Baptiste Ramond, Anders Priemé, Anna Romaní, and Aline Frossard

Soil microorganisms, crucial players of soil organic matter degradation, contribute substantially to global carbon and nitrogen biogeochemical cycles. Although microbial community structure and diversity have been extensively studied at different latitudes worldwide, the relationship between microbial communities, environmental drivers, and ecosystem functions across latitudes has yet to be explored. Here we investigate soil bacterial and fungal community structure and diversity, and ecosystem multifunctionality across different biomes of the European continent from southern Spain (37°N) to Sweden (60°N). Bacterial alpha-diversity increased with increasing the latitude, while fungal alpha-diversity showed an opposite pattern. Fungal communities were more geographically dispersed than bacterial communities. Microbial communities were structured by soil temperature, water content, and resources (TOC, C/N ratio and phosphate). While multifunctionality index related to N cycling functions decreased linearly and significantly with increasing bacterial diversity, it increased significantly with the increases in fungal diversity indices. Our study sheds light on the soil microbial complexity, microbial diversity and function relationship across latitudes and biomes, and highlights the importance of microbial diversity and community structure in driving soil multifunctionality.

How to cite: Han, X., Doménech-Pascual, A., Casas-Ruiz, J. P., Donhauser, J., Jordaan, K., Ramond, J.-B., Priemé, A., Romaní, A., and Frossard, A.: Microbial diversity controls soil multifunctionality across the European continent, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13803, https://doi.org/10.5194/egusphere-egu24-13803, 2024.

How climate and soil properties limit mineral-associated organic carbon (MAOC) accrual under afforestation. Findings from a climate gradient study in warm drylands.

David Yalin, William Mlelwa, Eyal Rotenberg, Dan Yakir and José M. Grünzweig

The efficiency of afforestation in climate mitigation has been a matter of debate in recent years. Specifically, there have been doubts about whether afforestation in drylands can be climate-positive. If afforestation can contribute to accumulation of soil organic carbon (SOC) and to the buildup of the mineral-associated organic C (MAOC) pools this may be a significant contribution to long-term C capturing in dry environments. However, there are still gaps in our understanding of how the interactions between vegetation type and climate affect MAOC storage. Furthermore, studies of MAOC dynamics have often disregarded the finite capacity of soils to store MAOC. In this work, we aimed at bridging these gaps by examining SOC and its partitioning between different soil size fractions in sites planted with Aleppo pine over 50 years ago (PF) as compared to neighboring fallow sites which were not actively forested (NF). This was performed at 16 sites along a climate gradient in Israel (ranging from 250-800 mm in annual precipitation) and differing in soil properties. MAOC in the 0-10 cm and 10-20 cm showed a general trend of increase with precipitation (more statistically significant in PF sites). Calcareous sites (>10% CaCO3 equivalent) showed lower MAOC concentrations, which may arise from smaller fine-grain soil fraction but also from reduced input from vegetation due to poor nutrient availability. MAOC composed between 37-83% of total SOC with a weak decreasing trend with increasing SOC (regardless of afforestation). The decrease in MAOC/SOC points to possible MAOC saturation at~40 g C kg-1 soil, a value previously suggested for saturation in European soils. To investigate whether saturation could be limiting MAOC accrual, we examined the saturation limit using topsoil samples (collected at the 0-2 cm depth) selected for high total SOC. In the topsoil fine fraction SOC reached 95 g C kg-1 soil-fine-fraction, slightly above global reports for soils with high activity clays. Based on these topsoil measurements, MAOC even in the high SOC soils (at 0-10 cm depth), reached less than 70% of its capacity, suggesting that saturation was not a limiting factor. However, density fractionation of the topsoil samples raised questions about whether they truly represent soil capacity to associate organic carbon. In the presentation we will discuss the concept of MAOC capacity in light of these findings and its implications for afforestation in dry climates.

 

How to cite: Yalin, D., Mlelwa, W., Rotenberg, E., Yakir, D., and Grünzweig, J. M.: How climate and soil properties limit mineral-associated organic carbon (MAOC) accrual under afforestation. Findings from a climate gradient study in warm drylands., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14798, https://doi.org/10.5194/egusphere-egu24-14798, 2024.

EGU24-16246 | ECS | Posters on site | BG3.10

Climatic conditions impact As and Cd mobility differently in flooded paddy soils 

Tianyu Wang, Britta Planer-Friedrich, Steffen Kümmel, and E. Marie Muehe

Arsenic (As) and cadmium (Cd) contamination in rice paddy soil are prevailing due to human activities including the application of agrochemicals and wastewater irrigation. Due to their inherently different geochemistry, As transitions to the porewater becoming more mobile under flooded water management while Cd binds to sulfidic minerals becoming more immobile. We currently have little understanding to which extent future climatic conditions imprint on native and elevated Cd and As mobilities in paddies, and whether they influence each other when being present in elevated concentrations together.

In order to close this gap in knowledge, we performed an incubation experiment with flooded paddy soils exposed to two different climatic conditions. The soil either contained the native metal(loid) content or elevated As and Cd realistic for contamination scenarios (+15 mg/kg As, +0.7 mg/kg Cd, or combined with +15 mg/kg As and +0.7 mg/kg Cd). Future climatic conditions were set relative to today’s climatic conditions (ambient CO2 and room temperature) with 850 ppm atmospheric CO2 and +4°C air temperature.

Adsorbed As approximated with 0.01 M CaCl2 extraction and outer-mineral associated As approximated with 0.1 M HCl extraction increased under flooded soil conditions over the incubation period, whereas 0.01 M CaCl2-extractable Cd decreased and 0.1 M HCl-extractable Cd remained stable, supporting prior knowledge on the contrasting geochemical behaviour of these two contaminants under flooded conditions. Future climatic conditions enhanced the increase of CaCl2 –extractable As but not 0.1 M HCl-extractable As when present as a single contaminant, indicating that climatic conditions influenced As dynamics on the surface of minerals but were not able to exert deeper into mineral phases. CaCl2- and HCl-extractable Cd were not affected by climatic conditions when present as a single contaminant, indicating resilience to climatic change. In the presence of combined As and Cd, the enhancement of the increase of CaCl2-extractable As by future climatic conditions was eliminated suggesting a toxicity of Cd to As-cycling related microbes which offset the stimulation by future climatic conditions.

Respirational output and other microbial dynamics data will be discussed relative to climatic impacts on either of these two contaminants and their combination.

Our findings show a link between climatic conditions and metal(loid) contaminant mobility under flooding conditions. The results of combined elevated As and Cd indicate a more realistic situation which is potentially overlooked in previous studies.

How to cite: Wang, T., Planer-Friedrich, B., Kümmel, S., and Muehe, E. M.: Climatic conditions impact As and Cd mobility differently in flooded paddy soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16246, https://doi.org/10.5194/egusphere-egu24-16246, 2024.

EGU24-16689 | ECS | Orals | BG3.10

Flux of CO2, CH4 and N2O from temperate woodland soil under elevated CO2 

Alex Armstrong, Sami Ullah, Liz Hamilton, Elena Vanguelova, Mike Morecroft, Nathan Basiliko, Rob MacKenzie, Niall McNamara, and Nine Douwes Dekker

Atmospheric fluxes of greenhouse gases (GHG’s) in the form of CO2, CH4 and N2O from temperate forest soils are an important aspect of the net global warming potential and climate change mitigation function of forests. However, it remains unclear how the magnitude of these atmospheric fluxes of GHG’s will respond to rising atmospheric CO2 concentrations in mature temperate forests. An increase in carbon capture by temperate forests under elevated atmospheric CO2 concentration (eCO2) and its subsequent storage in biomass and soils can have direct impact on the activities of soil microbes. In addition to indirect effects through shifting soil moisture regimes, potentially altering GHG production and consumption processes and hence net emissions from temperate forests. The Birmingham Institute of Forest research established a Free Air Carbon Enrichment Facility (BIFoR-FACE) whereby a mature temperate forest in the UK is exposed to +150 ppm CO2 above the ambient (aCO2), mimicking future CO2 conditions. Understanding GHG exchange from soils under elevated atmospheric CO2 levels is critical for addressing this component of the systems response to eCO2. Fumigation started in 2017 and continues to date, where the ecological and biogeochemical responses of the forest is being studied. In this abstract, the focus is placed on quantifying ~5-years (2019 – 2024) of GHG flux response to eCO2 to elucidate shifts in fluxes as influenced by eCO2 and local microclimatic conditions.

The flux of CO2 from the soil has been continuously measured within fumigated treatment (eCO2) and ambient control (aCO2) arrays since 2017 via LI-COR 8100A long-term measurement systems. With capabilities to additionally measure CH4 and N2O being added in 2020 through a coupled Picarro-G2508 analyser. Initial trends from 2017 - 2020 indicated that eCO2 arrays had a higher efflux of CO2 relative to paired aCO2 arrays by +20%. However, from 2020 – 2022 a significant decline of -46.6% in the efflux of CO2 was detected, in addition to a -76.6% reduction in N2O effluxes and a -44.3% decline in the CH4 uptake by the soil component. This period corresponds to a significant decline in soil moisture across the soil profile from the surface (0.05m) to a depth of 0.4m, equivalent to a -36% decline in volumetric water content under eCO2 relative to aCO2. Which when coupled with the prevalence of drought periods during the growing seasons of 2021 and 2022 suggest an enhanced drying of soil under eCO2, which is in turn exacerbated by drought events. During 2023 and the wettest July on record for the UK, the moisture deficit between eCO2 and aCO2 shrunk, reducing the variance in the efflux of CO2 to just ~4.5%. Therefore, it is possible that a functional change in the heterotrophic and autotrophic mediated flux dynamic could be occurring, driven by significant soil drying under eCO2, an affect which is exacerbated during drought events. Inter and intra-seasonal patterns of GHG fluxes will be examined in further detail, whilst also partitioning between autotrophic and heterotrophic contributions.

How to cite: Armstrong, A., Ullah, S., Hamilton, L., Vanguelova, E., Morecroft, M., Basiliko, N., MacKenzie, R., McNamara, N., and Douwes Dekker, N.: Flux of CO2, CH4 and N2O from temperate woodland soil under elevated CO2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16689, https://doi.org/10.5194/egusphere-egu24-16689, 2024.

EGU24-16701 | Orals | BG3.10 | Highlight

Seasonal changes of microbial functions along high-Arctic tundra soil toposequences 

Aline Frossard and the Climarctic team (Biodiversa ERANET project)

High-arctic tundra-soil ecosystems are particularly sensible to global changes due to their proximity to freezing, snow cover, light availability and scarcity of vegetation. Seasonal dynamic are large in these biomes with a very short vegetation growing season. Hydrological fluctuations in these soils are also important, directly impacting the soil biological activity. Yet, little is known on the seasonal dyanmic in the regulation of microbial functions in high-arctic soils and their impact on greenhouses gas exchanges with the atmosphere. Fluxes of greenhouse gases (CO2, CH4 and N2O) and microbial functions linked to C and N cylcing were assessed at each season along a slope toposequence in high-arctic tundra soils near Ny-Ålesund (Svalbard) and compared with prokaryotic and fungal community structures. Microbial functional diversity exhibited strong seasonal patterns, with most microbial functions acquiring C, N and P enhanced in summer, at the peak of the plant growing season. Seasonal dynamics was also evident for greenhouse gas fluxes but were not consistent across seasons. While CO2 fluxes were clearly increased in summer, CH4 fluxes were slightly higher in Autumn, especially in the upslope soils, alike methanogenesis gene abundance mcrA which distinctly increased in both biocrust and soil layer of the upslope site in Autumn. N2O gas fluxes were clearly higher in both shoulder seasons (i.e. Spring and Autumn), when freeze-thaw cycle are frequents. Seasonal microbial functional changes however did not mirror the prokaryotic and fungal community structure, which were more influenced by the microtopography and the soil depth layers (biocrust vs underneath mineral soil). These findings highlight the intricate relationships between microbial functions, diversity, and environmental factors in high-Arctic soils and underscore the importance of considering both seasonal and microtopography factors in understanding soil microbial dynamics in Arctic ecosystems.

How to cite: Frossard, A. and the Climarctic team (Biodiversa ERANET project): Seasonal changes of microbial functions along high-Arctic tundra soil toposequences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16701, https://doi.org/10.5194/egusphere-egu24-16701, 2024.

EGU24-17254 | Posters virtual | BG3.10

Impact of urease inhibitor and biofertilizer application on N2O emissions derived from fertilizer using 15N-labelled urea 

Maria Heiling, Rayehe Mirkhani, Christian Resch, Rebecca Hood-Nowotny, and Gerd Gerd Dercon

The introduction of nitrogen (N) fertilizers into agricultural soils represents the predominant anthropogenic contributor to the emission of the greenhouse gas N2O. The impact of N management choices on nitrous oxide (N2O) fluxes is contingent upon interactions with both soil biotic and abiotic factors. This study, conducted by the Joint FAO/IAEA Centre in the spring of 2022 at the experimental station of the University of Natural Resources and Life Sciences (BOKU) near Vienna, Austria, aims to explore the influence of a urease inhibitor (UI) and biofertilizer (BI) on N2O emissions arising from fertilizer use in wheat cropping systems. Employing a randomized complete block design with five treatments and four replicates, including a control treatment (T1), urea-only application (T2), urea with UI (T3), urea with BI (T4), and urea with both UI and BI (T5). For this study, the application rate was 50 kg N ha-1 at the tillering stage (GS 31), except for T1. N-(n-butyl) thiophosphoric triamide (nBTPT) was used as the UI, and Azotobacter chroococcum as the BI. N2O gas fluxes were measured using the static chamber method eight times between 3 to 84 days post-fertilizer application, and gas samples were analysed via off-axis integrated cavity output spectroscopy (ICOS, Los Gatos). The highest cumulative N2O and 15N2O emissions occurred in the T3 treatment, where urea was combined with UI. The emission factors for N2O in T2, T3, T4, and T5 were 0.63%, 0.85%, 0.52%, and 0.68%, respectively. Results from 15N2O emissions and the fraction of N2O from 15N-urea confirmed that UI increased N2O release from the added fertilizer source. The fraction of N2O from 15N-urea reached 26% in the Urea+UI (T3) treatment, decreasing to 12% in the Urea+BI (T4) treatment.

 

 

How to cite: Heiling, M., Mirkhani, R., Resch, C., Hood-Nowotny, R., and Gerd Dercon, G.: Impact of urease inhibitor and biofertilizer application on N2O emissions derived from fertilizer using 15N-labelled urea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17254, https://doi.org/10.5194/egusphere-egu24-17254, 2024.

EGU24-17930 | ECS | Posters on site | BG3.10

DeepSoil2100 and SWÆDIE (the Soil WArming Experiment Data Integration Effort) 

Jeffrey Beem Miller, Margaret Torn, Peter Reich, William Riley, and Michael Schmidt

How do soils respond to warming temperatures? The importance of soils in the global carbon cycle and as hotspots of biogeochemical processes in terrestrial ecosystems underscores the imperative of understanding this response. Soil warming experiments have proved to be a key tool for probing the mechanisms underlying warming responses. However, climate, mineralogy, flora, fauna, and methodology specific to each experimental site hamper efforts to generalize and upscale these findings. The DeepSoil 2100 project was initiated to synthesize data from soil warming experiments worldwide through the creation of a harmonized database (SWÆDIE, the Soil WArming Experiment Data Integration Effort). SWÆDIE emphasizes experiments in which soils have been warmed ≥ 1 m, and will enable us to explore depth-dependence and coupling between above and belowground processes, assess feedbacks and interactions between C stocks, nutrients, and soil moisture, compare short versus long-term warming responses, and identify global patterns.

Collaborative projects such as SWÆDIE require establishing clear guideline for data sharing and attribution of credit, for which we are building on the models provided by Ameriflux and NutNet. We have also drawn from other soil carbon-focused synthesis efforts such as ISRaD, SoDaH, and ISCN to construct a transparent and flexible data model with a user-friendly data access interface. Data are organized hierarchically, with a static site-level table and dynamic subordinate data tables, e.g., time series of fluxes, moisture, and temperature, resolved by depth. We maintain raw data files that are harmonized in a scripted data entry pipeline with the aid of separate metadata files describing variable names and units. Such an approach facilitates new data ingestion while also ensuring reproducibility and transparency.

We will present the results from the initial site characterization, including quantification of heating efficacy and the relationship to changes in soil moisture with depth and across sites. This initial site characterization will also allow us to compare data coverage and define the scope of soil, climatic, and vegetation gradients across the database. On the basis of this comparison, we will present plans for coordinated future sampling. Finally, we will present initial work on establishing improved metrics for model benchmarking, i.e., which modellable response variables are both sensitive and robust when measured across sites?

How to cite: Beem Miller, J., Torn, M., Reich, P., Riley, W., and Schmidt, M.: DeepSoil2100 and SWÆDIE (the Soil WArming Experiment Data Integration Effort), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17930, https://doi.org/10.5194/egusphere-egu24-17930, 2024.

EGU24-18305 | Posters on site | BG3.10

Nitrogen deposition effects on forest ecosystems: Linking N leaching patterns to long-term dynamics of soil C/N ratios in Swiss ICP Forests Level II Plots 

Peter Waldner, Alessandra Musso, Margaux Moreno Duborgel, Luisa Isabell Minich, Anne Thimonier, Maria Schmitt, Andreas Rigling, Alexander S. Brunmayr, and Katrin Meusburger

Forests play a major role in wood production and other ecosystem services, such as carbon (C) sequestration and filling reservoirs in drinking water quality. However, it is still under discussion to what extent environmental changes, such as elevated nitrogen (N) deposition and related eutrophication, may affect such services.

Our study aimed to assess long-term changes in N and C storage in Swiss forest soils along a gradient in N deposition (about 10 to 30 kg N/ha/y). At five long-term forest ecosystem research plots in Switzerland, which are part of the ICP Forests Level II network, nutrient fluxes (atmospheric deposition, litterfall, soil solution) have continuously been measured since the 1990s. Soil samples were taken from fixed depth layers in the course of soil inventories in the 1990s and 2022.

The observed flux patterns indicated that the forests had reached nitrogen saturation on some sites, resulting in nitrogen leaching. At sites with a higher carbon-to-nitrogen ratio (C/N), we found comparatively lower levels of N leaching. The comparison of the two soil inventories showed that the N concentration in soils has actually increased (and the C/N ratio decreased) on the sites with high C/N ratio and high N deposition. We will discuss the observed accumulation and transformations of organic C and N in these soils and the potential impacts on selected ecosystem services. 

How to cite: Waldner, P., Musso, A., Moreno Duborgel, M., Minich, L. I., Thimonier, A., Schmitt, M., Rigling, A., Brunmayr, A. S., and Meusburger, K.: Nitrogen deposition effects on forest ecosystems: Linking N leaching patterns to long-term dynamics of soil C/N ratios in Swiss ICP Forests Level II Plots, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18305, https://doi.org/10.5194/egusphere-egu24-18305, 2024.

Numerous studies have shown that nitrification inhibitors (NIs) are an effective tool to reduce direct N2O emissions. However, some studies have showed the positive effect of NIs on ammonia volatilization and increase the indirect N2O emission from AV. This study aimed to investigate the effect of nitrapyrin (NP) as a NI and gibberellic acid (GA3) as a plant growth regulator (PGR) on direct and indirect N2O emissions. A randomized complete block design including three treatments and five replicates was used in this study. The treatments were: T1 (control treatment-without N fertilizer), T2 (Urea only), and T3 (Urea+NI+GA3). Urea was applied in three split applications. GA3 was foliar sprayed only at stem elongation stage. NP and GA3 were applied at a rate of 0.51% and 0.03% of the applied N (weight/weight), respectively. Ammonia volatilization was measured with semi-static chambers and direct N2O emission was measured with static chambers. Cumulative N2O was 1.45 ± 0.13 and 1.11 ± 0.10 (kg N2O-N ha-1) in urea alone and urea in combination of NP+GA3. The estimated values of indirect N2O-N produced from AV in urea and urea+NP + GA3  were 0.38 and 0.45 kg N ha− 1, respectively. The results showed that the indirect N2O emission from the ammonia path in this type of soil which has high pH cannot be ignored and should be included in the net emission. Also, the results showed that the increase in the indirect emission of N2O from ammonia path induced by NP is negligible.

 

How to cite: Mirkhani, R., Shorafa, M., and Dercon, G.: Direct and indirect nitrous oxide emissions with application of nitrification inhibitor and plant growth regulator in a calcareous soil , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19196, https://doi.org/10.5194/egusphere-egu24-19196, 2024.

EGU24-19400 | ECS | Orals | BG3.10 | Highlight

Soil carbon storage in response to forest disturbance  

Mathias Mayer, Florian Hechenblaikner, Andri Baltensweiler, Jason James, Silvan Rusch, Markus Didion, Lorenz Walthert, Stephan Zimmermann, Andreas Rigling, and Frank Hagedorn

Forest soils have significant potential to mitigate climate change through their ability to store large amounts of organic carbon. However, forests are increasingly subject to natural disturbances such as windthrow, wildfire or disease outbreaks, which threaten the permanence of this large carbon stock. In response to increasing disturbances and ongoing climate change, forests are expected to lose their ability to return to pre-disturbance conditions involving a reorganization of tree species composition and stand structure. If tipping points are crossed, even a complete vegetation shift and conversion to non-forest ecosystems is possible. Here we aimed to assess the sensitivity of forest soil carbon to disturbance and its recovery with contrasting successional trajectories by combining two field studies on soil carbon stocks in windthrown forest stands and a global meta-analysis on the effects of different disturbance agents. Our results along an altitudinal gradient in Switzerland show that mountain forests with high carbon stocks in thick organic layers were particularly sensitive to disturbance by windthrow, losing up to 90% of their carbon stored belowground. In contrast, low-elevation forest soils with thin organic layers and smaller carbon stocks were barely affected. These results are consistent with our meta-analysis, which shows that disturbance-induced carbon losses increase with the size of initial carbon stocks. Boreal and high-elevation forests with large soil carbon stocks are highly sensitive to severe and long-lasting carbon losses due to damage from storms, wildfire, insects, and harvesting, while in most temperate and tropical forests soil carbon stocks recover more rapidly and losses are smaller. Results from a disturbance chronosequence in Austria also suggest that vegetation shifts following forest damage can strongly influence the recovery of soil carbon stocks after disturbance. Disturbed sites that remained in a non-forest, grass-dominated state for three decades accumulated about a third more soil carbon than sites that regenerated with trees. In addition to high litter inputs from herbaceous fine roots at grass-dominated sites, we relate this difference to changes in microbial community structure and function. In conclusion, our results underline that the magnitude and duration of soil carbon losses after disturbance depend on the forest type and site specific soil properties. Moreover, vegetation shifts during succession significantly modify the re-accumulation of soil carbon after disturbance.

How to cite: Mayer, M., Hechenblaikner, F., Baltensweiler, A., James, J., Rusch, S., Didion, M., Walthert, L., Zimmermann, S., Rigling, A., and Hagedorn, F.: Soil carbon storage in response to forest disturbance , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19400, https://doi.org/10.5194/egusphere-egu24-19400, 2024.

EGU24-19770 | Posters on site | BG3.10

The influence of penguin activity on the Nitrogen-Phosphorus cycle in the Ross Sea region 

Zhangqin Zheng, Xueying Wang, Jihua Hao, and Xiaodong Liu

As the limiting nutrient elements, nitrogen (N) and phosphorus (P) play important roles in forming biological organisms, promoting primary productivity, and changing ecological community structures. Until now, the research on the N and P cycle and the mechanisms in eutrophic lakes under human influence have been in-depth. However, in Antarctica, the research is still scarce. Adélie penguin, as the most important advanced predator in Antarctica, feeds mainly on krill in the ocean, while rearing and colonizing on land, which has important impacts on the N and P cycle in the fragile Antarctic terrestrial ecosystem.

In this study, soils and lacustrine sediments in the Ross Sea, Antarctica, which were heavily influenced or uninfluenced by penguin activities, were analyzed for N and P forms, N isotopes of NH4+ and NO3-, and O isotope of NO3-. Combined with the basic physicochemical properties, elements, and mineralogical analysis results of XRD, SEM/EDS, the mineralogical and morphological characteristics in sediments were discussed for the influence of penguin activities. The results show that penguin bio-transport inputs a large amount of N and P into soils and lacustrine sediments, Especially Ca-P, Mg-P, and NH4+. Mineralogical results such as XRD and SEM/EDS showed that the surface morphology of mineral particles heavily influenced by penguin activities was different from that in the natural environment. Phosphorus input from penguin guano forms a large amount of struvite (MgNH4PO4 6H2O) and other relatively stable minerals in aquatic environments. The results of TN and NH4+-N isotopes showed that the sediments influenced by penguin activities were more positive (about +30~40‰) than uninfluenced soils and sediments, which would be affected by the form of struvite. The N and O isotopes of NO3- were more complicated in the sediments, which may be related to the nitrification and denitrification processes in soils and sediments. The results of this study provide an important scientific basis for further understanding of the N and P cycle in the Antarctic affected by penguin activities under climate change.

How to cite: Zheng, Z., Wang, X., Hao, J., and Liu, X.: The influence of penguin activity on the Nitrogen-Phosphorus cycle in the Ross Sea region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19770, https://doi.org/10.5194/egusphere-egu24-19770, 2024.

Biogenic volatile organic compounds (BVOCs) are carbon compounds released by plants through secondary metabolism. In the global background of nitrogen (N) deposition, plants respond to environmental changes by altering BVOCs and photosynthetic strategies. However, there is very little research on the release and photosynthetic characteristics of BVOCs in bamboo in response to N deposition. Therefore, we took Pleioblast amarus as a research object and conducted pot experiments to set up four different nitrogen deposition levels (referred to as "N deposition") (0 kg N hm-2-a-1(N0), 30 kg N hm-2 a-1(N1), 60 kg N hm-2 a-1(N2), and 90 kg N hm-2 a-1(N3)) to explore the effects of different N deposition levels on the release and photosynthetic characteristics of BVOCs in leaves, and analyzed the correlation between the indicators. The results showed that: (1) the percentage of isoprene emission from Pleioblast amarus bamboo leaves increased with the increase of N deposition level (significantly positively correlated), but the N deposition level did not significantly affect the total number of BVOCs; (2) the increase of N deposition level significantly increased the net photosynthetic rate and isoprene (ISO) emission rate of leaves, with the highest ISO emission rate under N3 treatment, which was 80. 39%, 75.07%, and 50.84% higher than N0, N1, and N2, respectively; (3) ISO emission rate and total BVOCs emission of Sanming bitter bamboo were significantly positively correlated with net photosynthetic rate and photosynthetic effective radiation of leaves, but ISO emission rate and total BVOCs emission were significantly negatively correlated with chlorophyll b and total chlorophyll content (P≤0.05). In conclusion, the increase in nitrogen deposition led to a remarkable increase in isoprene emissions from Sanming bitter bamboo leaves. 

How to cite: Li, L. and Liu, X.: Effects of nitrogen deposition on volatile organic compounds composition, isoprene emissions and photosynthetic characteristics of Pleioblast amarus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2236, https://doi.org/10.5194/egusphere-egu24-2236, 2024.

EGU24-2534 | Posters on site | BG1.6

Rice cultivation under continuous flooding vs alternate wetting and drying: implications for biomass, nitrogen cycling and greenhouse gas flux 

Sami Ullah, Megha Kaviraj, Yafei Guo, Gianni Micucci, and Fotis Sgouridis

Rice uses 34-43% of the global irrigation water and is responsible for the usage of 24-30% of the world's total freshwater. More than 75% of rice produced in India is cultivated using the traditional continuous flooding (CF) irrigation method, which is a labour-intensive, time, water and energy-consuming process and a key source of global methane emissions. Alternate Wetting and Drying (AWD) is a popular water-saving approach trailed in Asia including India to reduce water use and methane emissions, whilst sustaining rice production. AWD is a method of periodic soil saturation followed by drying compared to CF. The objective of this research was to evaluate greenhouse gas (GHG) fluxes and internal and external nitrogen cycling processes as influenced by AWD and CF management regimes. A mesocosm experiment was set up in the laboratory using imported Indian paddy soil where Jasmine rice (var KDML 105) was grown. Our results depicted that plant biomass (52.57%), root biomass (28.57%), height (24.77%), effective tiller number (45.15%), stem sheath diameter (53.38%) and stomatal conductance (66.49%) were significantly (p<0.05) higher in CF compared to AWD treatment. A similar trend was observed in rice leaf chlorophyll (Chl a, b and total chl) contents. Interestingly, the chlorophyll a and b ratio observed was higher (1.63) in AWD compared to CF (1.03) conditions. This was likely during the process of chlorophyll b degradation and conversion to Chl a, thus resulting in the increase of a to b ratio to cope with the stress by maintaining the leaf photosynthetic efficacy. Soil enzyme activity revealed that β-glucosidase (BG), β-N-acetyl-glucosaminidase (NAG), and acid phosphatase (AP) were higher in AWD, whereas leucine aminopeptidase (LAP) activity was significantly higher in CF. Higher LAP activity might be a response to limited nutrient availability, as LAP helps to release amino acids that serves as a source for N mineralization and N supply. The 15N isotope tracing study revealed that denitrified N2O flux was significantly (p<0.05) higher in CF compared to AWD where source partitioning (% N2O denitrified) was 99.32% in CF and 27.01% in AWD. Higher gross mineralization was observed under AWD (3.92 ± 0.31µg-1 g-1 d-1) due to the promotion of aerobic microbial activity compared to CF (1.31 ± 0.31µg-1 g-1 d-1). A similar trend was observed for the consumption and immobilization of NH4+ and gross nitrification rates. GHG emissions rate viz., CH4-C, CO2-C, and N2O-N emissions were significantly higher under CF by 61, 3 and 72.%, respectively. Moreover, the global warming potential projected was higher under CF averaging at 10.92 mg kg-1 soil compared to 2.19 mg COkg-1 soil under AWD. Reduced GHG emissions under AWD provides for a significant negative feedback to global warming potential and future initiatives should keep emphasizing the optimization of this practice for its significant contribution to both climate change mitigation and sustainable agriculture.

How to cite: Ullah, S., Kaviraj, M., Guo, Y., Micucci, G., and Sgouridis, F.: Rice cultivation under continuous flooding vs alternate wetting and drying: implications for biomass, nitrogen cycling and greenhouse gas flux, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2534, https://doi.org/10.5194/egusphere-egu24-2534, 2024.

EGU24-2749 | ECS | Posters on site | BG1.6

Molecular transformation of organic nitrogen in Antarctic penguin guano-affected soil 

Libin Wu, Ming Sheng, Xiaodong Liu, and Pingqing Fu

Organic nitrogen (ON) is an important participant in the Earth’s N cycle. Previous studies have shown that penguin feces add an abundance of nutrients including N to the soil, significantly changing the eco-environment in ice-free areas in Antarctica. To explore the molecular transformation of ON in penguin guano-affected soil, we collected guano-free weathered soil, modern guano-affected soil from penguin colonies, ancient guano-affected soil from abandoned penguin colonies, and penguin feces from the Ross Sea region, Antarctica, and Fourier transform ion cyclotron mass spectrometry (FT-ICR MS) was used to investigate the chemical composition of water-extractable ON. By comparing the molecular compositions of ON among different samples, we found that the number of ON compounds (>4,000) in weathered soil is minimal, while carboxylic-rich alicyclic-like molecules (CRAM-like) are dominant. Penguin feces adds ON into the soil with > 10,000 CHON, CHONS and CHN compounds, including CRAM-like, lipid-like, aliphatic/ peptide-like molecules and amines in the guano-affected soil. After the input of penguin feces, macromolecules continue to degrade, and other ON compounds tend to be oxidized into relatively stable CRAM-like molecules, this is an important transformation process of ON in guano-affected soils. We conclude the roles of various forms of ON in the N cycle are complex and diverse. Combined with previous studies, ON eventually turns into inorganic N and is lost from the soil. The lost N ultimately returns to the ocean and the food web, thus completing the N cycle. Our study preliminarily reveals the molecular transformation of ON in penguin guano-affected soil and is important for understanding the N cycle in Antarctica.

How to cite: Wu, L., Sheng, M., Liu, X., and Fu, P.: Molecular transformation of organic nitrogen in Antarctic penguin guano-affected soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2749, https://doi.org/10.5194/egusphere-egu24-2749, 2024.

EGU24-3699 | Posters on site | BG1.6 | Highlight

Nitrite stimulates HONO and NOx but not N2O emissions in Chinese agricultural soils during nitrification 

Dianming Wu, Yaqi Song, Yuanchun Yu, and Peter Dörsch

The long-lived greenhouse gas nitrous oxide (N2O) and short-lived reactive nitrogen (Nr) gases such as ammonia (NH3), nitrous acid (HONO), and nitrogen oxides (NOx) are produced and emitted from fertilized soils and play a critical role for climate warming and air quality. However, only few studies have quantified the production and emission potentials for long- and short-lived gaseous nitrogen (N) species simultaneously in agricultural soils. To link the gaseous N species to intermediate N compounds [ammonium (NH4+), hydroxylamine (NH2OH), and nitrite (NO2)] and estimate their temperature change potential, ex-situ dry-out experiments were conducted with three Chinese agricultural soils. We found that HONO and NOx (NO + NO2) emissions mainly depend on NO2, while NH3 and N2O emissions are stimulated by NH4+ and NH2OH, respectively. Addition of 3,4-dimethylpyrazole phosphate (DMPP) and acetylene significantly reduced HONO and NOx emissions, while NH3 emissions were significantly enhanced in an alkaline Fluvo-aquic soil. These results suggest that ammonia-oxidizing bacteria (AOB) and complete ammonia-oxidizing bacteria (comammox Nitrospira) dominate HONO and NOx emissions in the alkaline Fluvo-aquic soil, while ammonia-oxidizing archaea (AOA) are the main source in the acidic Mollisol. DMPP effectively mitigated the warming effect in the Fluvo-aquic soil and the Ultisol. In conclusion, our findings highlight the important role of NO2 in stimulating HONO and NOx emissions from dryland agricultural soils. In addition, subtle differences of soil NH3, N2O, HONO, and NOx emissions indicated different N turnover processes, and should be considered in biogeochemical and atmospheric chemistry models.

How to cite: Wu, D., Song, Y., Yu, Y., and Dörsch, P.: Nitrite stimulates HONO and NOx but not N2O emissions in Chinese agricultural soils during nitrification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3699, https://doi.org/10.5194/egusphere-egu24-3699, 2024.

EGU24-4369 | ECS | Orals | BG1.6

Constraining the denitrification process in conventional and regenerative agriculture 

Gianni Micucci, Fotis Sgouridis, Stefan Krause, Iseult Lynch, Niall P. McNamara, Felicity Roos, Leake Jonathan, and Sami Ullah

In this study, we aimed to constrain and characterize the dynamics of denitrification in three different fields: one conventional arable and two types of pasture (“leys”). During a one-year field campaign, denitrification was measured using our newly developed method combining the application of 15N tracer and artificial atmosphere for the incubation of soil cores under field conditions (Micucci, 2022), while total N2O emissions were measured using static flux chambers during parallel incubations. Our objectives were to determine the best way to upscale soil core denitrification measurements and trace the fate of applied synthetic nitrogen fertilizer via denitrification in conventional agriculture in comparison to pastures under regenerative agriculture practices.

We determined that the best way to derive field-scale fluxes of denitrification was to use the core method to calculate the source partitioning coefficient (SPC) and product ratio (PR) and use these metrics in combination with static chamber data. The SPC is defined as the proportion of total N2O emissions that originates from denitrification while the product ratio measures the proportion of denitrification product emitted as N2O rather than N2.

During the field campaign, we estimated that 22 kgN ha-1 were lost via denitrification in the arable field, amongst which 15.17 were attributed to fertilizer application, representing around 8% of the 200 kgN ha-1 applied. Furthermore, 9 % of the denitrified fertilizer was emitted as N2O rather than N2. On the other hand, the unfertilized ley emitted only 2.6 kgN ha-1 via denitrification annually. Overall, the total N2O emissions in the fertilizer arable field were responsible for around 2 t eqCO2 ha-1 year-1 compared to 0.15 in the unfertilized ley, highlighting the importance of land management in strategies of greenhouse gas emission reduction.

How to cite: Micucci, G., Sgouridis, F., Krause, S., Lynch, I., McNamara, N. P., Roos, F., Jonathan, L., and Ullah, S.: Constraining the denitrification process in conventional and regenerative agriculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4369, https://doi.org/10.5194/egusphere-egu24-4369, 2024.

EGU24-4706 | ECS | Orals | BG1.6

How does nitrogen control soil organic matter composition? – A theory and model 

Chun Chung Yeung, Harald Bugmann, Frank Hagedorn, and Olalla Díaz-Yáñez

Current soil biogeochemical models have difficulties matching the observed composition of soil organic matter (i.e., the relative proportions of deadwood, raw litter, organic horizon, particulate organic carbon, and mineral-associated organic carbon). In reality, nitrogen (N) controls microbial decomposition and physiological processes, whereas in most models it is merely considered a plant nutrient. In addition, many N fertilization studies have shown that N exerts different effects on different C pools via changing exoenzyme activities, microbial growth, and necromass production via microbial turnover. These divergent effects control SOM composition and have C-cycle consequences.

We expanded the CENTURY model by incorporating multiple hypothesized microbial responses to nitrogen availability, including 1) decomposition reduction of recalcitrant substrates when N is in excess; 2) decomposition stimulation of high C:N substrates when N limitation is alleviated; 3) microbial adaptation of turnover rate; 4) microbial adaptation of CUE; and 5) secondary feedback to decomposition via changes in microbial biomass in response to N. We systematically tested multiple model variants using two sets of simulations, one along a natural N gradient in Swiss forests, and another one with artificially increased N input (i.e., simulating an N-fertilization experiment). We evaluated the simulated outputs using data on soil organic matter fraction stocks, their relative proportions, and temporal responses under N addition.

From the simulation results, we identified the necessary processes to explain the temporal response pattern of different C pools to N addition, in accordance with findings from meta-analyses. In addition, we identified patterns of SOM composition over a natural gradient of N supply (no artificial N addition), which can again be explained by the N-driven processes we implemented. We conclude that considering the direct effects of nitrogen as a key additional constraint on microbial processes is essential to improve the realism and accuracy of soil biogeochemistry models.

How to cite: Yeung, C. C., Bugmann, H., Hagedorn, F., and Díaz-Yáñez, O.: How does nitrogen control soil organic matter composition? – A theory and model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4706, https://doi.org/10.5194/egusphere-egu24-4706, 2024.

EGU24-5161 | ECS | Orals | BG1.6

On the Contribution of Atmospheric Nitrogen Deposition to Nitrogen Burden in an Eutrophic Lake in Eastern China 

Weikun Li, Xia Wang, Zhongyi Zhang, Xiaodong Liu, and Lei Geng

Atmospheric deposition of natural and anthropogenic sourced reactive nitrogen (Nr, mainly including NH3, NH4+, NOx, NO3- and etc.) has substantial influence on terrestrial and aquatic ecosystems, driving global nutrient imbalances and increasing risks to human health. Although it has been demonstrated that atmospheric Nr deposition has a substantial impact on nitrogen pools in remote and/or sensitive lakes, there is a scarcity of systematic evaluations regarding atmospheric Nr deposition's impact on the nitrogen burden in eutrophic lakes with riverine input as the primary source. Utilizing a regional chemical transport model, combined with observations of riverine nitrogen input, we investigate the contribution of atmospheric Nr deposition to a eutrophic Lake Chaohu in eastern China. The results indicate that riverine total nitrogen (TN) input to the lake was 11553.3 t N yr-1 and atmospheric TN deposition was 2326.0 t N yr-1 in the year of 2022. For Nr species which are directly available for the biosphere supporting algae and plant growth, riverine NH4+ input was 1856.1 t N yr-1 and atmospheric NHx (NH3 and NH4+) deposition was 824.5 t N yr-1. The latter accounts for ~ 1/3 of total NHx input to the lake. For NOy (HNO3 and NO3-) species, atmospheric deposition was estimated to also contributes a similar amount to the NHx species. The results suggest that even in regions with dense human activities with primary riverine N input, atmospheric deposition of Nr could also contribute significantly to the bio-available nitrogen in lake systems, and addressing eutrophication in Lake Chaohu and other eutrophic lakes will also need to consider the reduction of NH3 and NOx (i.e., NO + NO2, the precursor of NOy) emissions, in addition to the mitigation of riverine N input.

How to cite: Li, W., Wang, X., Zhang, Z., Liu, X., and Geng, L.: On the Contribution of Atmospheric Nitrogen Deposition to Nitrogen Burden in an Eutrophic Lake in Eastern China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5161, https://doi.org/10.5194/egusphere-egu24-5161, 2024.

EGU24-5244 | ECS | Posters on site | BG1.6

Surges in global N2O fluxes from saltmarshes are driven by increasing porewater nitrate and ammonium concentrations 

Devon Collier-Woods, Sami Ullah, and Sophie Comer-Warner

Saltmarshes have the potential to sequester large amounts of carbon, however, the value of stored carbon may be partially offset by emissions of the potent greenhouse gas nitrous oxide (N2O). Increased nutrients [NO3- and NH4+] have been shown to increase N2O emissions from saltmarshes, however, a global-scale analysis of this relationship has not been performed. Here, we present a global meta-analysis to investigate the relationship between N2O fluxes and porewater nitrogen and determine the relative importance of porewater NO3- and NH4+ as key drivers of enhanced saltmarsh N2O fluxes. Both porewater NO3- and NH4+ were significantly, positively correlated with N2O fluxes (p < 0.01), explaining 25 and 18% of the variation in fluxes, respectively. We estimate a global saltmarsh N2O flux of 0.012 Tg N2O yr-1, which is six times higher than the current estimate (0.0021 Tg N2O yr-1), representing an offset of 19% of the estimated global saltmarsh carbon burial. Using predicted future increases in riverine DIN export, our meta-analysis suggests that 17-31% of the estimated global saltmarsh carbon burial could be offset by a surge in N2O emissions under chronic mineral N pollution. This meta-analysis indicates the importance of reducing nutrient inputs into saltmarshes to reduce N2O fluxes and maximise their negative radiative forcing.

How to cite: Collier-Woods, D., Ullah, S., and Comer-Warner, S.: Surges in global N2O fluxes from saltmarshes are driven by increasing porewater nitrate and ammonium concentrations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5244, https://doi.org/10.5194/egusphere-egu24-5244, 2024.

EGU24-5701 | ECS | Orals | BG1.6

Regionalized nitrogen balances of Switzerland 

Anina Gilgen, Simon Baumgartner, Ernst Spiess, and Frank Liebisch

For the agri-environmental monitoring of Switzerland, nitrogen balances on farm level for all Swiss farms were calculated and aggregated in order to obtain regionalized nitrogen balances. This monitoring attempts to incorporate as much existing data as possible to minimize multiple data collections from farmers. Data from the agricultural policy information system of Switzerland was used as basis for the calculation. This database contains information on livestock numbers, the crops grown, and the direct payments received for each farm. This information was supported with different data sources from federal offices, cantons, agricultural associations, and research institutions. Balances were calculated as a soil-surface balance according to the OECD method, which includes N input via organic and mineral fertilizers, biological N-fixation, atmospheric N-deposition, and seedlings as well as N outputs via plant yields.

The regional balances showed a high variability, resulting in an average N surplus of around 105 kg N per hectare of utilized agricultural area in cantons with highly intensive livestock farming and around 16 kg N in cantons with more extensive farming practices, i.e. in mountain regions. On national scale, highest N input occurred via organic fertilizers, whereas mineral fertilizers and biological N-fixation account for around 15% of the total input each.

Our approach of calculating N balances on farm level for the whole Swiss farming system has some limitations, which are mainly due to missing or incomplete data sources.  As an example, the use of mineral fertilizers had to be estimated by application data of a rather small sample of farms (~300 farms). Nevertheless, the obtained results show that this methodology is a promising tool to gain a regional overview of the environmental status of Swiss farms. Over the years, this approach will be refined and new data (e.g. additional administrative data, satellite data) can be incorporated in order to better estimate the N balances of Swiss farms.

How to cite: Gilgen, A., Baumgartner, S., Spiess, E., and Liebisch, F.: Regionalized nitrogen balances of Switzerland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5701, https://doi.org/10.5194/egusphere-egu24-5701, 2024.

EGU24-5728 | ECS | Orals | BG1.6

Advances in measuring low N2O fluxes by a portable gas analyser and manual chambers 

Nathalie Ylenia Triches, Maija Marushchak, Anna Virkkala, Timo Vesala, Martin Heimann, and Mathias Göckede

Nitrous oxide (N2O) is one of the most important greenhouse gases with a global warming potential of about 298 times stronger than carbon dioxide (CO2) over a period of 100 years. From 1800 to 2023, the atmospheric concentration of N2O has increased from 273 to 336 ppbv, whereby more than half of this rise is due to the addition of fertilisers and manure on agricultural soils. Whilst these managed, nutrient-rich soils have been relatively well studied, little is known about N2O fluxes in nutrient-poor ecosystems (e.g., the Arctic).

Since many Arctic soils contain very low amounts of available nitrogen, in the past it has been generally assumed that Arctic soils are not a significant source of N2O. Only recently, several studies have reported significant N2O emissions from organic-rich Arctic soils; however, due to methodological challenges, extensive investigations on N2O fluxes in Arctic soils have been limited. As a result, the importance of N2O fluxes from this region to the global budget remains highly uncertain. 

With the recent advances in portable GHG analyser technology, extensive manual chamber measurements based on in-situ N2O concentration measurements can provide novel information to close this knowledge gap. However, guidelines on measuring techniques (e.g., chamber closure time) and data quality (e.g., no flux vs. low flux) are still lacking. In this study, we provide new insights on N2O fluxes in a nutrient-poor ecosystem and give general practical guidelines for measuring low N2O fluxes with a portable gas analyser and manual chambers. In May, July, and September 2023, we used a portable N2O/CO2 analyser to measure N2O fluxes in a thawing sub-Arctic permafrost peatland in northern Sweden. Recommendations on practical use in the field are given to support future N2O research with portable gas analysers. 

How to cite: Triches, N. Y., Marushchak, M., Virkkala, A., Vesala, T., Heimann, M., and Göckede, M.: Advances in measuring low N2O fluxes by a portable gas analyser and manual chambers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5728, https://doi.org/10.5194/egusphere-egu24-5728, 2024.

EGU24-5816 | ECS | Orals | BG1.6

2152 

Meng Yao and Ronghua Kang

It has been recognized recently that trees can assimilate NO2 directly through leaf stomata. Both laboratory and field studies have measured the foliar NO2 deposition velocity, which could be determined by some environmental factors, e.g. light irradiation intensity, ambient NO2 concentration, and leaf characteristics. However, the NO2 uptake capacity and allocation of foliar uptake NO2 under these environmental factors remain unclear. To clearly understand the foliar NO2 uptake process and refine the forest NO2 uptake models, we conducted a dynamic 15NO2 fumigation experiment.

We selected Fraxinus mandshurica (F. mandshurica), Pinus koraiensis (P. konraiensis), Quercus mongolica (Q. mongolica), and Larix gmenilii (L. gmenilii) saplings, four dominant tree species in temperate forests of northeastern China, as our experimental materials. Meanwhile, we chose a pair of broad-leaved and coniferous tree species (F. mandshurica and P. konraiensis) to perform fumigation experiment under dark/light irradiation and another pair (Q. mongolica and L. gmenilii) to perform fumigation experiment with soil N addition. All saplings were dynamically fumigated with 50 ppb 15NO2 for 8 h and destructively sampled immediately after fumigation. We rinsed the samples surface with purified water, dried and grinded all samples, then measured the 15N abundance in leaves, twigs, stems and roots with EA-IRMS.

The results showed that tree saplings can absorb NO2 under both dark and light irradiation treatments. The total 15N recovery ranged between 30 to 80% under the light condition in all species. Under the dark condition, the total 15N recovery were (29.8±9.16) % and (1.1±0.47) % for F. mandshurica and P. konraiensis, which were significantly lower than under the light condition, (59.6±5.2) % and (8.8±2.5) %, respectively. With the soil N addition, the total 15N recovery in Q. mongolica ((56.2±8.8) %) were significantly larger than non-N addition ((27.6± 4.8) %), while L. gmenilii showed the opposite result that the total 15N recovery ((31.7±7.8) %) significantly decreased, compared to that without N addition ((73.6±4.3) %). These results are likely attributed to different amount of N demand for different tree species, more N needed for Q. mongolica than L. gmenilii. Moreover, coniferous species could assimilate more N through foliar uptake than broad-leaved species, probably due to bigger leaf surface areas of coniferous trees. After 8 h fumigation, the largest proportion of 15NO2 was recovered in leaves in all species and treatments, accounting for 60-97%, which indicates that NO2 stays in leaves in a short-term period after foliar assimilation. However, further studies are needed to explore the transformation of foliar incorporated NO2 to other organs in a long-term scale.

This study quantified the foliar NO2 uptake capacity of different tree species and figured out the effects of light irradiation and soil nitrogen availability on foliar NO2 uptake. Our results would provide references for the model estimation of canopy NO2 uptake magnitude at a regional scale.

How to cite: Yao, M. and Kang, R.: 2152, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5816, https://doi.org/10.5194/egusphere-egu24-5816, 2024.

EGU24-6942 | ECS | Orals | BG1.6

Improving Agricultural Nitrogen Use Efficiency to Reduce Air Pollution in China 

Biao Luo and Amos P. K. Tai

Chinese agriculture has long been characterized by low nitrogen use efficiency (NUE) associated with substantial ammonia (NH3) loss, which contributes significantly to fine particulate matter (PM2.5) pollution. However, the knowledge gaps in the spatiotemporal patterns of NH3 emissions and the states of nitrogen management of agricultural systems render it challenging to evaluate the effectiveness of different mitigation strategies and policies. Here we explored the NH3 mitigation potential of various strategies and its subsequent effects on PM2.5 pollution, and their effectiveness in improving NUE of Chinese agricultural systems. We developed and used a nitrogen flow model for evaluating NUE of different crop and livestock types at a provincial scale in China. We then used the bottom-up NH3 estimates to drive an air quality model (GEOS-Chem High Performance, GCHP) to provide an integrated assessment of four improved nitrogen management scenarios: improving NUE of crop systems (NUE-C), increasing organic fertilizer use (OUR), improving NUE of livestock systems (NUE-L) and combined measures (COMB). The total agricultural NH3 emission of China was estimated to be 11.2 Tg NH3 in 2017, of which 46.24% and 53.76% are attributable to fertilizer use and livestock animal waste, respectively, and emission hotspots can be identified in the North China Plain. Our results show that grain crops have higher NUE than fruits and vegetables, while high livestock NUE can be found in pork and poultry, and NUE for the entire crop and livestock systems are both better in Northeast China than the rest of China. We also found that agricultural NH3 emissions can be reduced from 11.2 Tg to 9.1 Tg, 9.3 Tg, 9.9 Tg and 6.8 Tg, and consequently annual population-weighted PM2.5 reductions are estimated to be 1.8 µg m–3, 1.6 µg m–3, 1.3 µg m–3 and 4.1 µg m–3 under NUE-C, OUR, NUE-L and COMB scenarios, respectively. Our results are expected to provide decision support policy making concerning agricultural NH3 emissions.

How to cite: Luo, B. and Tai, A. P. K.: Improving Agricultural Nitrogen Use Efficiency to Reduce Air Pollution in China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6942, https://doi.org/10.5194/egusphere-egu24-6942, 2024.

EGU24-9564 | ECS | Posters on site | BG1.6

Progressive decline in topsoil nitrogen pool upon decadal warming in a permafrost ecosystem 

Bin Wei and Yuanhe Yang

Nitrogen (N) plays an important role in mediating many aspects of permafrost carbon cycle, such as plant productivity, soil organic matter decomposition and the production of greenhouse gases. In contrast to the well-recognized effects of climate warming on soil organic carbon stocks and vulnerability, the fates and pools of soil N has received little attention in permafrost ecosystems.

Here, based on a decadal warming experiment in a permafrost ecosystem on the Tibetan Plateau, we assessed changes in soil N stocks over a 10-year time-scale, and in situ measured the majority of N-cycling processes involving biological N fixation and soil N transformation, and the preferential plant uptake of different N forms, and above- and belowground litter decomposition and N release, and N leaching losses as well as high-resolution nitrous oxide (N2O) flux during the growing season.

Our results showed that experimental warming progressively reduced topsoil N stocks but had no effect in the deeper soils on a 10-year time-scale. The observed decline in topsoil N pools could be due to the fact that decadal warming enhanced plant N uptake and intensified N leaching and gaseous losses. Specifically, warming treatment had a negligible effect on ecosystem biological N fixation rate, but increased the above- and belowground plant N pools. Meanwhile, simulated warming accelerated belowground litter N release and soil N transformation rate, and enhanced plant uptake of organic N. However, warming intensified the topsoil inorganic N leaching losses and N2O flux during the growing season.

These findings highlight that progressive N limitation could occur in permafrost ecosystems under continuous climate warming due to the re-allocation of N pool from soils to plants and the losses of N through leaching and gases flux, which would make the future trajectory of permafrost carbon cycle and its feedback to climate warming more complex than previously thought.

How to cite: Wei, B. and Yang, Y.: Progressive decline in topsoil nitrogen pool upon decadal warming in a permafrost ecosystem, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9564, https://doi.org/10.5194/egusphere-egu24-9564, 2024.

EGU24-10360 | ECS | Posters on site | BG1.6

Mitigation measures of crop cultivation to reduce climate-impacting emissions from denitrification 

Jaqueline Stenfert Kroese, Caroline Buchen-Tschiskale, Johannes Cordes, Rene Dechow, Klaus Dittert, Bryan Dix, Kathrin Fuchs, Andreas Gattinger, Jörg-Michael Greef, Balazs Grosz, Michael Hauschild, Jarrah Mahboube, Johannes Kühne, Henrike Mielenz, Thade Potthoff, Clemens Scheer, Franz Schulz, Conor Simpson, Benjamin Wolf, and Reinhard Well

The joint project 'Measures to reduce direct and indirect climate-impacting emissions caused by denitrification in agricultural soils - MinDen' addresses the topics of reducing nitrous oxide emissions and improving nitrogen efficiency through modeling, the evaluation of possible mitigation measures and the evaluation of denitrification on spatial scale. Gaseous emissions from denitrification cause N losses relevant to crop cultivation and cause direct N2O emissions from crop cultivation. Climate protection measures in crop production in the areas of fertilization, soil cultivation and crop rotation have hardly been researched with regard to the role of denitrification. Crop management that optimizes N efficiency and minimizes N emissions at the same time has therefore not yet been reliably defined. The overall objective of the present project is to identify practicable crop management measures to minimize N2 and N2O emissions from denitrification for arable cropping systems in Germany by improving the knowledge on denitrification-related N losses through field and laboratory studies and using it for parameterization, validation and application of simulation models. Our objectives are as follows:

  • Regionalization of N losses due to denitrification in Germany based on existing models
  • Determination of the effect of crop protection measures on N2 and N2O losses on field scale
  • Testing of mitigation options on the model, laboratory and field scale, taking into account the topsoil and subsoil for different soils
  • Further development of denitrification models to improve the mapping of mitigation measures using existing and new field data
  • Testing of mitigation options for Germany using the improved models, taking into account yield, economic efficiency, technology requirements, N2O emissions, N efficiency, fertilizer requirements, NH3 emissions and nitrate leaching.

We provide an overview of the approach and the current status of the joint project, which started at the beginning of 2023.

How to cite: Stenfert Kroese, J., Buchen-Tschiskale, C., Cordes, J., Dechow, R., Dittert, K., Dix, B., Fuchs, K., Gattinger, A., Greef, J.-M., Grosz, B., Hauschild, M., Mahboube, J., Kühne, J., Mielenz, H., Potthoff, T., Scheer, C., Schulz, F., Simpson, C., Wolf, B., and Well, R.: Mitigation measures of crop cultivation to reduce climate-impacting emissions from denitrification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10360, https://doi.org/10.5194/egusphere-egu24-10360, 2024.

Title: Drought and eCO2 Effects on Oak Seedlings Growth, Soil Fertility, and Greenhouse Gases Fluxes

 

Authors: Rehab Al Mutairi, Nicholas Kettridge and Sami Ullah

 

Objective/Purpose:

This study explores the impact of water stress legacy and elevated CO2 on oak seedlings' growth, stomatal conductance, soil nutrient availability, and greenhouse gas (GHGs) fluxes. The research aims to unravel the intricate interplay of these factors under controlled glasshouse conditions.

 

Methods/Approach:

The experiment, conducted from mid-May to August 2023 at the University of Birmingham campus, involved oak seedlings grown under ambient CO2 and elevated CO2 chambers, subjected to two soil volumetric moisture levels (10% for drought, 30% for non-drought). Various parameters, including oak growth, stomatal conductance, soil nutrient availability, and GHGs flux, were measured and recorded throughout the three-month period. Additional analyses, including biomass, soil extracellular enzyme activities, microbial biomass of N and C, and net N mineralization, were conducted at the experiment's conclusion.

 

Key Findings/Results:

The study revealed compelling insights into the response of oak seedlings to drought stress and elevated CO2 conditions. Under drought scenarios, both under ambient and elevated CO2  environments, oak biomass and growth were notably diminished. Particularly, the roots exhibited a substantial increase in biomass, suggesting a coping strategy in search of water and nutrient resources of the seedlings. Stomatal conductance exhibited a decline under elevated carbon dioxide (eCO2), indicating a water-saving mechanism employed by plants. Additionally, extracellular enzyme activities were impacted by environmental conditions: a reduction was observed under drought stress. This reduction in enzyme functions aligns with a concurrent decrease in nutrient availability, highlighting a correlation between nutrient levels and enzyme activity reduction during drought conditions.

 

Conclusion/Implications:

The findings underscore the vulnerability of oak seedlings to drought stress, highlighting the importance of soil moisture management for their optimal growth. Additionally, the differential response between ambient and elevated CO2  levels emphasizes the need for nuanced considerations in future climate change scenarios. These insights contribute to our understanding of ecosystem responses to concurrent drought and elevated CO2 conditions.

 

Keywords:

Oak seedlings, Drought stress, Elevated CO2, Soil fertility, Greenhouse gas fluxes, Stomatal conductance, Biomass, Microbial biomass, Net N mineralization.

 

 

 

 

 

How to cite: Almutairi, R.: Drought and eCO2 Effects on Oak Seedlings Growth, Soil Fertility, and Greenhouse Gases Fluxes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11614, https://doi.org/10.5194/egusphere-egu24-11614, 2024.

EGU24-12116 | Orals | BG1.6

Examining the natural nitrogen biogeochemical cycling and impacts across South African ecosystems 

Rebecca M. Garland, Mogesh Naidoo, Katye Altieri, Phesheya Dlamini, Gregor Feig, Kerneels Jaars, Lerato Sekhohola, Pieter van Zyl, Nomsa Muthelo, Jabulile Leroko, Pelenomi Sakwe, Tamryn Hamilton, Tiaan van Niekerk, Pedro Bixirao Neto Marinho, and Kathleen Smart

The biogeochemical nitrogen (N) cycle in South Africa is influenced by, and in turn influences a number of crucially important global change processes. However, the natural N cycling in South Africa is not well-understood. The “Emissions, deposition, impacts - Interdisciplinary study of N biogeochemical cycling (EDI-SA)” project is working to improve our baseline understanding of the natural biogeochemical cycling of N in non-industrialized ecosystems across South Africa. This includes quantifying N fluxes from emissions through to deposition, identifying linkages between N cycling and related species such as sulphur (S) and ozone, and evaluating ecosystem impacts. Previous work has focused on the impact of atmospheric deposition of N and S species on ecosystems at sites almost exclusively on the industrialized Highveld. This has left large gaps of knowledge in the biogeochemical cycling and ecosystem impacts, particularly within the diverse natural ecosystems found across South Africa. In order to address this gap, EDI-SA is applying a more holistic approach using measurements (from two South African Research Infrastructures; EFTEON and BIOGRIP) and modelling to investigate multiple linkages within the biogeochemical cycling of N with a focus on improving the understanding of the natural cycling. The project is applying a variable resolution sampling approach to investigate processes which occur at multiple spatial scales, and applying multiple measurement techniques including atmospheric measurements, stable isotope analysis of aerosol particles, rainwater and soil, and analysis of soil chemistry and biology. This contribution will detail the approach of this interdisciplinary project, highlight results from the first soil and air sampling campaigns, as well as the atmospheric composition modelling that assesses the relative importance and impacts of N emissions from soil across South Africa. This baseline understanding will allow future research to assess the potential changes to N biogeochemical cycling into the future in a changing climate.  

How to cite: Garland, R. M., Naidoo, M., Altieri, K., Dlamini, P., Feig, G., Jaars, K., Sekhohola, L., van Zyl, P., Muthelo, N., Leroko, J., Sakwe, P., Hamilton, T., van Niekerk, T., Bixirao Neto Marinho, P., and Smart, K.: Examining the natural nitrogen biogeochemical cycling and impacts across South African ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12116, https://doi.org/10.5194/egusphere-egu24-12116, 2024.

Nitrogen is a fundamental plant nutrient and the most important fertilizer in modern agriculture. At the same time nitrate based nitrogen loss from agroecosystems becomes an increasing environmental problem in ground- and surface waters. The lysimeter station Brandis in Saxony, Germany, provides detailed observations of water and solute fluxes under representative agricultural landuse since 1981. Despite substantial efforts and success in regulation and assessment of fertilizer needs and the reduction of fertilization excess, the seepage water analysis reveals increasing or stagnating levels of nitrate concentration in groundwater recharge in a broad range of soil types. This apparent decoupling between input and output is evident in all soil types under investigation and raises some important questions concerning the nitrate loss in agricultural soils:

  • Which part of the soil N-cycle contributes to the seepage water nitrate export?
  • What are the main drivers of nitrate loss in agricultural soils?
  • Can residence times of mineral fertilizer nitrogen be estimated?
  • Will reduced fertilization excess lead to timely reductions in nitrate loss to the groundwater?

We investigated these questions with long-term solute balances and state-of-the-art isotope methods. Analysis of source δ 15N ratios in soil, atmospheric deposition and fertilizer in combination with a 5-year campaign of δ15N and δ18O analysis of seepage water nitrate allows a source identification with dual-isotope plots and mixing models. The results clearly show that the main source of nitrate loss with the seepage water is the soil organic matter pool in all investigated soils. Analysis of the long-term nitrogen balances and the soil samples show furthermore a substantial accumulation of fertilization excess within the upper meter of agricultural soils and indicate that the residence time of nitrogen in the lysimeters might be substantially longer than water residence times. Isotope analysis in combination with mixing model analysis suggest that the nitrate loss is mainly driven by nitrification of this nitrogen legacy in the post-harvest period. Thus, the results hold an explanation why the current regulation efforts have not yet led to the desired reductions in nitrogen loadings of seepage water fluxes. Furthermore, the apparent decoupling between nitrogen input in agricultural soils and the seepage water output makes a timely reduction of nitrate concentrations, by reductions in fertilization excess alone, in groundwater recharge unlikely.

How to cite: Werisch, S., Alexandra, T., and Diana, B.: Insights into nitrogen dynamics and nitrate loss from agricultural soils based on long-term lysimeter observations and a 5-year isotope measurement campaign, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12647, https://doi.org/10.5194/egusphere-egu24-12647, 2024.

EGU24-13239 | ECS | Orals | BG1.6

Resolving nitrogen gaseous pathways in the atmosphere-plant-microbial-soil continuum in the NOAA/GFDL Earth System Modeling Framework 

Maureen Beaudor, Elena Shevliakova, Sergey Malyshev, and Minjin Lee

Representing plant-microbe-soil organic matter interactions and their coupling with land surface processes are critical to understanding of ecosystem responses to climate change. More specifically, microbes play an important role in the nitrogen (N) cycle by providing acquisition pathways for plants and overcoming N limitation through mycorrhizal symbiosis and bacterial fixation. Even though biological nitrogen fixation acts as a primary N source for the organisms, ecosystem N availability is still strongly affected by N losses, including atmospheric volatilization.

One of the major challenges to accurately representing N availability in Earth System Models (ESM) is the representation of the atmospheric losses that are not necessarily controlled by the organisms. For instance, the conversion of soil ammonium into gaseous ammonia (i.e., volatilization) is driven by ambient environmental conditions and not directly controlled by the biological demand of plants and soil microbes. Thus, rapid losses of N via volatilization (e.g., after precipitation events) could induce feedback on soil microbial activity and plant growth by impeding biological assimilation.

Even though the representation of ammonia emissions is progressively integrated into ESMs, the focus has been mainly on parameterizing losses from agricultural or managed ecosystems. However, ammonia volatilization from natural soils occurs worldwide and can reach 9 TgN/yr, a non-negligible source, especially in alkaline drylands. Up to now, no proper representation of emissions of ammonia, applicable to unmanaged lands, has been included in ESMs and challenged by observations. In the future, these emissions are likely to follow the rising trends of nitrogen deposition and increasing precipitation due to climate change.

Here we describe a mechanistic parameterization of ammonia emissions in natural ecosystems with explicit treatment of microbes and vegetation dynamics in the fully integrated terrestrial component of the GFDL ESM, LM4.2-GIMICS-N. We apply observational constraints, including measurements of soil 15N isotope and estimates of nitrogen fluxes (BNF, nitrification, mineralization, and ammonia exchange) at different sites to reduce uncertainty in the model simulations. Finally, we examine the main drivers of ammonia volatilization across various ecosystems by considering aridity, soil pH, and nitrogen deposition as well as the key environmental conditions such as precipitation, temperature, and soil moisture.

How to cite: Beaudor, M., Shevliakova, E., Malyshev, S., and Lee, M.: Resolving nitrogen gaseous pathways in the atmosphere-plant-microbial-soil continuum in the NOAA/GFDL Earth System Modeling Framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13239, https://doi.org/10.5194/egusphere-egu24-13239, 2024.

EGU24-15243 | Posters on site | BG1.6

A Sphagnum incubation study using 15N-labelled atmospheric N2 reveals contrasting potential for biological N2 fixation at three medium-polluted Central European peat bogs 

Marketa Stepanova, Martin Novak, Bohuslava Cejkova, Frantisek Buzek, Ivana Jackova, Eva Prechova, Frantisek Veselovsky, and Jan Curik

Microbial N2-fixation helps to sustain carbon accumulation in pristine peatlands and to remove CO2 from the atmosphere. Recent work has provided evidence that this energetically costly process is not completely downregulated at sites with higher availability of reactive nitrogen (Nr). We studied nitrogen (N) cycling at three high-elevation, mainly rain-fed, Sphagnum-dominated peat bogs in the northern Czech Republic receiving medium to high amounts of reactive nitrogen (Nr) via atmospheric deposition. 15N/14N isotope ratios were determined in Nr deposition, along vertical peat profiles, and in a laboratory incubation study using fresh Sphagnum and 15N-enriched atmospheric N2. Our objective was to assess the potential for biological N2-fixation at the selected study sites in light of various biogeochemical parameters. Historically, all the peat bogs experienced similar changes in atmospheric Nr (mainly NO3--N and NH4-N) inputs. Nr depositions at all three sites peaked between 1980 and 1990. During that time period, the highest annual depositions were close to 10 kg ha-1 yr-1 at the slightly more polluted site Uhlirska (UHL) than at Male mechove jezirko (MMJ) and Brumiste (BRU). Since ca. 1990, atmospheric deposition of Nr has been steadily decreasing. Living Sphagnum had variable N concentrations with similar means for all three sites (1.1, 1.0 and 0.9 wt. % at MMJ, BRU and UHL, respectively). Downcore, peat density remained nearly constant at MMJ but increased at BRU and UHL. Ash contents were below 10 wt. % at least to the depth of 20 cm. With an increasing peat depth, both N concentration and δ15N values generally increased, while C/N ratios tended to decrease. At depths > 10 cm, N/P ratio was lower at UHL than at the other two sites and remained nearly constant downcore. N/P ratio at MMJ increased from ~10 to ~20 with an increasing depth, whereas the N/P ratio exhibited a zigzag vertical pattern at BRU, reaching a value of 40 in deeper segments. The potential for biological N2-fixation was investigated using a replicated laboratory incubation of fresh Sphagnum in a closed system following an application of 98 % enriched atmospheric N2. The experiment lasted for 7 days. The control Sphagnum samples had δ15N values of -4.0 ‰ (BRU and UHL) and -3.7 ‰ (MMJ). At the end of the incubation, the δ15N significantly increased only in MMJ moss reaching + 70 ‰, while it remained unchanged in BRU and UHL moss. Biological N2 fixation was thus recorded at only at MMJ, a site with the lowest N/P ratio in the topmost 2-cm thick sections. Potential N2 fixation rates at MMJ were similar to values previously reported for Finland (Leppänen et al. 2015) but ~7 times lower than at sites located in Patagonia, Chile (Knorr et al. 2016).

References

Leppänen et al., 2015. Plant and Soil, 389, 185-196.

Knorr et al., 2016, Global Change Biology 21, 2357–2365.

How to cite: Stepanova, M., Novak, M., Cejkova, B., Buzek, F., Jackova, I., Prechova, E., Veselovsky, F., and Curik, J.: A Sphagnum incubation study using 15N-labelled atmospheric N2 reveals contrasting potential for biological N2 fixation at three medium-polluted Central European peat bogs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15243, https://doi.org/10.5194/egusphere-egu24-15243, 2024.

EGU24-15470 | Orals | BG1.6

Long-term soil warming causes acceleration of soil nitrogen losses in a temperate forest studied by 15N isotope fractionation 

Wolfgang Wanek, Michaela Bachmann, Ye Tian, Steve Kwatcho Kengdo, Jakob Heinzle, Erich Inselsbacher, Werner Borken, and Andreas Schindlbacher

Climate warming was shown to strongly affect the biogeochemical cycles in global forests, reducing soil carbon storage and accelerating soil nitrogen (N) and phosphorus cycling. In a long-term soil warming experiment in a temperate old-growth forest in Achenkirch, Austria, we recently showed faster root turnover and growth, decreases in microbial biomass, carbon use efficiency and soil carbon storage, increases in ecosystem phosphorus limitation, and varied responses of the soil N cycle in warmed plots (+4 ° C above ambient for 14 years). In this study we therefore employed natural stable isotope techniques to better understand ecosystem-level responses of the N cycle in Achenkirch, studying the abundance of 15N and 14N (expressed as δ15N values) in a wide range of soil nitrogen pools (bulk soil N, root N, microbial biomass N, extractable organic N, ammonium, nitrate) and employed isotope fractionation models to explain the patterns found dependent on soil warming. Specific N cycle processes such as mineralization, nitrification and denitrification cause substantial isotope fractionation (against the heavy stable isotope 15N), leading to 15N enrichment of the residual substrates and 15N depletion of the cumulative products, depending on the fraction on substrates consumed and the isotope fractionation factor of that process. Other processes such as diffusion, (de)sorption and depolymerization exert negligible isotope fractionation. We found a significant warming effect on the isotopic signatures of root N and the soil ammoniumpool, i.e. a 15N enrichment in these pools. 15N enrichment of tree fine roots, considered to be isotopic integrators of the plant available N pool, suggest increased soil N cycling and greater soil N losses in warmed plots causing a 15N enrichment of the soil inorganic N pool (ammonium and nitrate). The increased 15N enrichment in ammonium of warmed soils highlights an increased activity of nitrifiers, with greater fractions of ammonium oxidized to nitrate causing the observed 15N enrichment of ammonium. However, soil nitrate did not show the expected 15N depletion imparted by nitrifiers but matched or even exceeded δ15N values of soil ammonium. Isotope fractionation calculations indicated that >50% of the soil nitrate produced was lost, particularly through denitrification promoting gaseous N losses in the form of NO, N2O and/or N2 and less through nitrate leaching. Natural 15N abundance studies thereby hold great potential for evaluating the status quo of the complex N cycle in terrestrial ecosystems and to monitor in situ responses to climate change with minimal invasion and improved time integration.

How to cite: Wanek, W., Bachmann, M., Tian, Y., Kwatcho Kengdo, S., Heinzle, J., Inselsbacher, E., Borken, W., and Schindlbacher, A.: Long-term soil warming causes acceleration of soil nitrogen losses in a temperate forest studied by 15N isotope fractionation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15470, https://doi.org/10.5194/egusphere-egu24-15470, 2024.

EGU24-15569 | Posters on site | BG1.6 | Highlight

The anaerobic soil volume as a controlling factor of denitrification  

Steffen Schlüter, Maik Lucas, Balazs Grosz, Olaf Ippisch, Jan Zawallich, Hongxing He, Rene Dechow, David Kraus, Sergey Blagodatsky, Mehmet Senbeyram, Alexandra Kravchenko, Hans-Jörg Vogel, and Reinhard Well

Denitrification is a major component of the nitrogen cycle in soil that returns reactive nitrogen to the atmosphere. Denitrification activity is often concentrated spatially in anoxic microsites and temporally in ephemeral events, which presents a challenge for modelling. The anaerobic fraction of soil volume can be a useful predictor of denitrification in soils. Here, we provide a review of this soil characteristic, its controlling factors and its estimation from basic soil properties.

The concept of the anaerobic soil volume and its link to denitrification activity has undergone several paradigm shifts that came along with the advent of new oxygen and microstructure mapping techniques. The current understanding is that hotspots of denitrification activity are partially decoupled from air distances in the wet soil matrix and are mainly associated with particulate organic matter (POM) in the form of fresh plant residues or manure. POM fragments harbor large amounts of labile carbon that fuels local oxygen consumption and, as a result, these microsites differ in their aeration status from the surrounding soil matrix.

Current denitrification models link the anaerobic soil volume fraction to bulk oxygen concentration in different ways but take almost no account of microstructure information, such as the distance between POM and air-filled pores. Based on meta-analyses, we derive new empirical relationships to estimate conditions for the formation of anoxia at the microscale from basic soil properties and we outline how these empirical relationships could be used in the future to improve prediction accuracy of denitrification models at the soil profile scale.

How to cite: Schlüter, S., Lucas, M., Grosz, B., Ippisch, O., Zawallich, J., He, H., Dechow, R., Kraus, D., Blagodatsky, S., Senbeyram, M., Kravchenko, A., Vogel, H.-J., and Well, R.: The anaerobic soil volume as a controlling factor of denitrification , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15569, https://doi.org/10.5194/egusphere-egu24-15569, 2024.

Direct emission of the greenhouse gases methane and nitrous oxide (N2O) constitute a significant fraction of the overall carbon footprint of wastewater treatment. Measurement methods to identify emission sources and to quantify emissions are key in mitigating these direct emissions. Nitrous oxide is formed in biological nitrogen removal process units, which are the main source of N2O emission from wastewater treatment.

Liquid phase sensors (LPS) have recently been developed and installed at various Danish wastewater treatment plants to measure N2O concentrations in the liquid phase of biological nitrogen removal tanks. These sensors can be used to implement adjustments on the operation of the plant (for example duration of aeration), which affects N2O emission. In addition, LPS can be utilized to calculate N2O emission through mass transfer modelling. However, there is a need for validation of liquid-based modelled emission rates against measurement methods, which measure direct N2O emission rates. In this study, emission rates determined by two remote sensing methods, the tracer gas dispersion method (TDM) and Eddy covariance method (EC) were compared to LPS derived N2O emission rates.

TDM relies on continuous, controlled release of a gaseous tracer at the source combined with downwind measurements of concentration of target gas (N2O here) and tracer gas (often acetylene - C2H2).  This method is well-established, validated, and has been used to quantify fugitive emissions from various sources such as landfills, composting plants, biogas plants, etc. EC is a stationary method, which relies on high-frequency measurements of N2O concentration and wind vector on a tower near the source. EC can be set up for continuous monitoring, while TDM as applied here is a discrete measurement method.

In the study, N2O emission rates were measured over a period of 1.5 years at a relatively large wastewater treatment plant in the greater Copenhagen area. TDM measurements were conducted on 15 measurement days covering both periods of relatively high and low N2O emission rates. TDM measurements were compared to LPS derived emission rates, where N2O emission was measured using sensors in four of eight process units for biological nitrogen removal. Overall, daily average emission rates between approximately 0.38 and 13.4 kg N2O h-1 were measured. High emission rates of 120 kg N2O h-1 were observed on a day, where plant maintenance is believed to be the cause of unusual high emission. Emission rates from simultaneous TDM measurements and LPS derived values (n=43) showed good correlation (R2=0.70). On average, emission rates from TDM were 35% higher than LPS rates. The model implementation to derive LPS determined emission rates was further developed during the study, and the listed results were the final values after some correction. Several factors can explain the difference – including liquid sensor drift, which for the specific sensors tends towards lower N2O concentration readings than actual concentrations. Continuous EC measurements showed the same emission dynamics as measured by the liquid sensors located inside the footprint of the station.

How to cite: Fredenslund, A., Kissas, K., and Scheutz, C.: Comparison of liquid phase and remote sensing measurements of nitrous oxide emission from biological nitrogen removal at a wastewater treatment facility, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16147, https://doi.org/10.5194/egusphere-egu24-16147, 2024.

EGU24-16927 | ECS | Posters on site | BG1.6

In-situ treatment of nitrate polluted groundwater by chemoautotrophic denitrification: flow-through tank experiments 

Adrian Simon Seeholzer, Anja Wunderlich, Ruben Steib, and Florian Einsiedl

Nitrate in groundwater can be converted microbially into N2. However, the lack of anoxic conditions (oxygen concentrations < 50 μmol/L) in the aquifer linked with the limitation of microbial available organic and inorganic electron donors may lead to insufficient denitrification in aquifers and nitrate concentration above the drinking water limit of 50 mg/L can be observed. In view of the increasing drinking-water scarcity associated with climate change and the continuing increase in nitrate concentrations in near-surface aquifers, it is urgently necessary and prudent to develop practicable and cost-effective methods to reduce nitrate to harmless N2.
Faced with the increasing nitrate pollution in groundwater, we want to develop a new cost-effective in-situ remediation technology by hydrogen/methane coupled denitrification. We hypothesize that the simultaneous injection of the two water soluble electron donors H2 and CH4 into groundwater may significantly enhance the rate of nitrate consumption by activation of denitrifying chemolithoautotrophic microorganisms that are already present in the groundwater.
Here we show the experimental set-up of the 2D-model aquifer (6 m x 1,8 m), the sampling strategy and show first results of the methane injection experiment. Measurements are performed along the flow direction and at several depths. Concentration profiles and stable isotope composition of methane (δ13C) and nitrate (δ15N) linked with oxygen concentrations shed light on the hydrogen-methane coupled denitrification potential in the model aquifer.

How to cite: Seeholzer, A. S., Wunderlich, A., Steib, R., and Einsiedl, F.: In-situ treatment of nitrate polluted groundwater by chemoautotrophic denitrification: flow-through tank experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16927, https://doi.org/10.5194/egusphere-egu24-16927, 2024.

EGU24-17028 | Orals | BG1.6

Quantifying tree canopy nitrification across European forests 

Rossella Guerrieri, Joan Joan, Stefania Mattana, Emilio Casamayor, Josep Peñuelas, and Maurizio Mencuccini and the Collaborators at the ICP Forests sites

Fluxes and chemical composition of precipitation is substantially changed after passing through tree canopies, particularly in the case of atmospheric nitrogen compounds, with important implications on forest nitrogen cycling. The causes of these changes, however, have mostly focused on the passive role of foliar surfaces to scavenge pollutants from the atmosphere and to ion exchange processes, while biological processes involving microbes hidden in the phyllosphere have been less investigated. We combined triple oxygen isotopes approach and molecular analyses with the aim of quantifying canopy nitrification and identify microbes responsible for it, respectively. Ten sites included in the European ICP Forests monitoring network, chosen along climate and nitrogen deposition gradients, were selected to include the two most dominant tree species in Europe (Fagus sylvatica L. and Pinus sylvestris L.). Specifically, in this study we: 1) estimated the relative contribution of nitrate derived from biological canopy nitrification vs. atmospheric deposition by using δ18O and Δ17O of nitrate collected in water samples, i.e., in the open field (bulk deposition) and underneath tree canopies (throughfall); 2) quantified the functional genes related to nitrification for the two dominant tree species in European forests by using next-generation sequence analyses. Based on the isotope approach, we found that up to 80% of the nitrate reaching the soil via throughfall derived from biological transformations in the phyllosphere, equivalent to a flux of gross canopy nitrification of up to 5.76 kg N ha-1 y-1. The fraction of microbiologically derived nitrate increased with raising nitrogen deposition, thus suggesting that the process can be substrate limited. Molecular analyses confirmed the presence on foliar surfaces of bacterial and archaeal autotrophic ammonia oxidisers and bacterial autotrophic nitrite oxidisers across the investigate European forests. Our study demonstrates the potential of integrating stable isotopes with molecular analyses to advance our understanding on key processes underpinning forest nitrogen cycling, which should no longer exclude microbial processes occurring in the phyllosphere.

How to cite: Guerrieri, R., Joan, J., Mattana, S., Casamayor, E., Peñuelas, J., and Mencuccini, M. and the Collaborators at the ICP Forests sites: Quantifying tree canopy nitrification across European forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17028, https://doi.org/10.5194/egusphere-egu24-17028, 2024.

EGU24-17096 | ECS | Orals | BG1.6

Co-application of organic amendments and urea-N in a loamy soil reduced the N2O emission factor but substantial amounts of organic C were lost as CO2. 

Georgios Giannopoulos, Elpida Pasvadoglou, Georgios Kourtidis, Lars Elsgaard, George Zanakis, and Ioannis Anastopoulos

Under the framework of Circular Economy, EU Green Deal, and UN Sustainable Development Goals the addition of organic amendments to agricultural soils is highly promoted as a cost-efficient solution to improve soil quality and agrosystem sustainability. Nonetheless, their agronomic use comes with an uncertainty of their potential to release ample plant-available N, and to emit soil greenhouse gases.

This mesocosm study investigated short-term (90 d) soil N dynamics of a loamy soil receiving four organic amendments (50 t ha-1) (i) cow manure compost (CMC), (ii) food waste compost (FWC), (iii) used digestate substrate (UDS) and (iv) municipal sewage sludge (MSS), without and with N fertilization (160 kg N ha-1; urea). An unamended soil mesocosm was included as a control (C). During the incubation soil NO2-, NO3-, NH4+, N2O and CO2 were regularly monitored.

During the incubation, org. amendments did not affect NH4+ availability (AUC) compared to unamended soil, except MSS treatment which had 5.7x more NH4+ than C. The co-application of urea increased available NH4+ by 2.9x, 4.1x, 4.4x, 4.6x, and 5.9x for MSS, UDS, CMC, FWC, and C, respectively. There was no difference in available NO2- among org. amendment treatments and the C, except MSS (2.4x). There was a substantial and temporal accumulation of NO2- (2.4x to 3.6x) when urea was co-applied with org. amendments. Co-application of urea with org. amendments increased AUC NO3- in all treatments ranging to 2.7x from 13.6x, except MSS. Considering cum. CO2 we did not observe any differences between org. amended treatments without and with urea. However, org. amendments increased cum. N2O emission by 1.4x, 1.6x, and 3x, for UDS, FWC, and MSS, and reduced by 0.6x for CMC relative to C, respectively. The co-application of urea increased cum. N2O emissions for MSS, UDS, and CMC by 6%, 65%, and 90%, respectively, and reduced by 58% for FWC, compared to the corresponding org. treatment without urea.

Interestingly, co-application of urea with org. amendments reduced N2O emission factor (EF) by 4x, 6x, 6x, and 9x, relative to org. amendments without urea, for CMC, MSS, UDS and FWC, respectively. However, the EF N2O exceeded 1% in most cases. Treatments with urea lost substantial amounts of org. C as CO2-equivalent emissions, for instance, UDS+U and MSS+U lost 22% and 68%, respectively.  

In conclusion, our preliminary results indicate that the co-application of org. amendments with urea-N could potentially fuel soil N2O emissions, thus offsetting any favorable aspects of the aforementioned policies. Org. amendment, urea-N, and their interaction were significant factors (p≤0.05) driving CO2 and N2O emissions. The quality and composition of the amendments may stimulate soil microbial N transformations, and further investigation will elucidate the intrinsic role of soil microbes and their dynamics in regulating CO2 and N2O emissions from soils.

The research project was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “2nd Call for H.F.R.I. Research Projects to support Post-Doctoral Researchers”; Project #01053 awarded to P.I. Dr Georgios Giannopoulos. This project was co-implemented with industrial partner Corteva Agriscience Hellas SA.     

How to cite: Giannopoulos, G., Pasvadoglou, E., Kourtidis, G., Elsgaard, L., Zanakis, G., and Anastopoulos, I.: Co-application of organic amendments and urea-N in a loamy soil reduced the N2O emission factor but substantial amounts of organic C were lost as CO2., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17096, https://doi.org/10.5194/egusphere-egu24-17096, 2024.

EGU24-17469 | Orals | BG1.6

Evaluating temporal patterns in wood δ15N in Swedish forests as an indicator of changing N limitation 

Michael Gundale, Kelley Bassett, Lars Östlund, Jonas Fridman, Steven Perakis, and Sandra Jämtgård

Boreal forests play an important role in the global carbon (C) cycle, and their productivity is strongly limited by nitrogen availability.  Thus, understanding whether nitrogen availability in boreal forests is changing has important implications for understanding past, present, and future trends of forest growth. We utilized a unique archive of tree cores collected by the Swedish National Forest Inventory, to evaluate temporal patterns (1950-2017) of wood δ15N, which is commonly used as an indicator of N limitation. First, we focused on an area of ca. 55,000 sq. km in central Sweden to evaluate how sensitive the wood δ15N approach is to tree age and two alternative sampling methodologies: a) analysis of single trees sampled in the present, versus b) tree chronologies constructed from multiple trees of the same age sampled during different decades.  By analysing 1038 woods samples, and covering two key boreal tree species (Picea abies and Pinus sylvestris), we found strong trends of declining δ15N through time, suggestive of progressive N limitation.  We further found that temporal patterns were highly sensitive to method choice, where the multiple tree approach supported by the tree core archive showed much stronger temporal patterns than reliance on more conventional contemporary sampling approaches, where N mobility appeared to obscure temporal patterns.  We further found that temporal trends were relatively insensitive to tree age class. Using the more powerful Multiple Tree Approach, we further evaluated δ15N values from an additional 1000 P. abies and P. sylvestris wood samples covering the entire forested area of Sweden and spanning the same time period, to investigate how temporal patterns in wood δ15N varied in areas with historically high N deposition (Southern Sweden) versus low N deposition (Northern Sweden).  These data help address current debates regarding whether temporal patterns in δ15N are indicative of oligitrophication (i.e. progressive N limitation), or are instead the result of changing δ15N signatures from nitrogen deposition inputs.  

How to cite: Gundale, M., Bassett, K., Östlund, L., Fridman, J., Perakis, S., and Jämtgård, S.: Evaluating temporal patterns in wood δ15N in Swedish forests as an indicator of changing N limitation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17469, https://doi.org/10.5194/egusphere-egu24-17469, 2024.

EGU24-17865 | ECS | Posters on site | BG1.6

The effect of nano fertilizers on wheat vegetative characters 

Thanawan Buacharoen, Yafei Guo, Eugenia Valsami - Jones, and Sami Ullah

The effect of nano fertilizers on Wheat vegetative characters

Thanawan Buacharoen1, Yafei Guo1, Eugenia Valsami-Jones1*, and Sami Ullah1

*Authors to whom correspondence should be addressed.

1School of Geography, Earth and Environmental Science, College of Life and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK

Wheat is the primary staple cereal in the world. It was the highest cultivation in 2018. According to the British Survey of Fertilizer Practice, total nitrogen use in Great Britain was reduced between 2021 and 2022. At the same time, the total phosphate did not change. Meanwhile, the usage of the total potash has increased compared to last year.  
Conventional fertilizer, which consists of nitrogen, phosphorous, and potassium nutrients, will release Greenhouse gas emissions. The other option to solve this problem is the nano fertilizer. Plants can easily absorb a tiny particle of nano fertilizer, reducing greenhouse gas emissions into the air. Therefore, this study focused on nano fertilizers' effect on plant growth. 

The first set of 30-day-old wheat plants was treated with amorphous calcium phosphate (nano - ACP), a potassium-bearing variant of the ACP (nano ACP - NPK) and a urea and potassium-bearing variant of the ACP (nano - UNPK). Moreover, three conventional fertilizers, which have the same nutrient quantity as same as nano fertilizers, were applied to the second set of plants to be a positive control. On the other hand, blank treatment was used to be a negative control. After harvesting the wheat plants, the shoot length and fresh weight were measured. Also, the ammonium concentration in the soil was examined with the colorimetric method. Maximum root weight was found in the wheat treated with nano–ACP (Average± SD. = 0.39±0.20). The nano ACP - NPK gave the highest value of shoot weight (Average ± SD. = 0.9 ± 0.10), number of seeds (84 seeds) and shoot length (Average ±SD.= 63.33 ± 4.29). However, the maximum ammonium concentration was found in the soil treated with nano ACP. All treatments' seed weight and shoot length differ at the P – value of less than 0.5. Our finding suggests that the nano fertilizers had enhanced vegetative characteristics compared with the conventional fertilizers.

Key word; amorphous calcium phosphate (nano - ACP), potassium-bearing variant of the ACP (nano ACP - NPK) and urea and potassium-bearing variant of the ACP (nano - UNPK)        

How to cite: Buacharoen, T., Guo, Y., Valsami - Jones, E., and Ullah, S.: The effect of nano fertilizers on wheat vegetative characters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17865, https://doi.org/10.5194/egusphere-egu24-17865, 2024.

EGU24-19499 | ECS | Orals | BG1.6

Increased irrigation frequency reduces N2O, but not overall denitrification losses (N2O+N2) from an intensively managed pasture following ruminant urine deposition and nitrogen fertilisation. 

Johannes Friedl, Daniele De Rosa, Clemens Scheer, Michael Fitzgerald, Peter R. Grace, and David W. Rowlings

Intensively managed pasture systems receive large inputs of nitrogen (N) in the form of fertiliser and through the  deposition of ruminant urine, creating hot-spots for denitrification which results in variable amounts of nitrous oxide (N2O) and dinitrogen (N2) emitted. Here we investigated the potential of increased  irrigation frequency to reduce N2O and N2 emissions from an intensively managed pasture in the subtropics after ruminant urine deposition. Irrigation volumes were estimated to replace evapotranspiration and were applied either once (Low-Frequency) or split into four applications (High-Frequency). This irrigation schedule was applied 3 times over the 60 day monitoring period, and fluxes of N2O and N2 were  measured using the 15N gas flux method. In line with farming practice, simulated urine patches (equivalent of 80 g N m-2 applied) were also fertilised three times with 2 g urea N m-2 to show the combined effects of urinary and fertiliser N on N2O and N2 emissions. Highest N2O emissions of up to 60 mg N2O-N m-2 day-1 were observed briefly after urine deposition, decreasing thereafter, resulting in cumulative N2O losses of 169.9 mg N2O-N m-2 from the Low-Frequency treatment. Denitrification was dominated by N2, accounting for more than 89% of  N2O+N2 emitted. Irrigation treatments had no effect on cumulative N2 losses of more than 2700 mg N2-N m-2. However, High frequency irrigation reduced cumulative N2O losses by 35%. Our findings suggest that under conditions of high N availability, increased irrigation frequency can reduce the environmental impact (N2O) of denitrification, but not overall N losses via this pathway. The response of N2O emissions may further indicate that less frequent, but more intense rainfall events will shift the product ratio of denitrification towards N2O, increasing environmentally harmful N losses from intensively managed pasture systems.

How to cite: Friedl, J., De Rosa, D., Scheer, C., Fitzgerald, M., Grace, P. R., and Rowlings, D. W.: Increased irrigation frequency reduces N2O, but not overall denitrification losses (N2O+N2) from an intensively managed pasture following ruminant urine deposition and nitrogen fertilisation., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19499, https://doi.org/10.5194/egusphere-egu24-19499, 2024.

EGU24-20301 | ECS | Orals | BG1.6

Browning and mining increase the nitrous oxide production in sediments of large boreal lakes during winter 

Carlos Palacin-Lizarbe, Stefan Bertilsson, Henri J. Siljanen, Moritz Buck, Lukas Kolh, Dhiraj Paul, Marion Maréchal, Hannu Nykänen, Tong Liu, Mikko Kiljunen, Sanni L. Aalto, Antti J. Rissanen, Christina Biasi, Anssi Vainikka, and Jukka Pumpanen

There is limited knowledge on the N (nitrogen) cycling in winter, on the role of organic matter quality on N cycling, and on the microbes involved.

We studied Lake Viinijärvi and Lake Höytiäinen, large boreal lakes in Finland, each lake with clear-water and brown-water sides. Viinijärvi has an additional side affected by mining activities in the catchment showing higher nitrate and sulphate levels. During winter of 2021 we sampled 5 sites at the beginning and at the end of the ice-covered period. Using the Isotope Pairing Technique we incubated sediment cores with 15NO3- and quantified the products of 1) complete denitrification (N2), 2) truncated denitrification (nitrous oxide, N2O), and 3) dissimilatory nitrate reduction to ammonium (DNRA, NH4+) to infer the process rates. We characterized the DOM using FT-ICR MS. We explore the genetic potential (DNA) of the sediment microbiome by using several sequencing techniques.

During winter the sediment-water interface is an active compartment. The top sediment microbiome has heterotrophic bacteria with flexible metabolism, breaking-down OM during winter despite most of the DOM is recalcitrant. Impacts of browning and mining with major differences between sites. The genetic potential of the sediment microbiome indicates more DNRA and N2O consumption in clear-waters, while in the mining-impacted site and brown-water sites the dominant pathway depends on the sediment layer with truncated denitrification in top layer, and methanogenesis and N-fixation in sub-top layer. The N2O production (d14), that fits the genetic potential, is highest in the mining-impacted site (35-43 µmol N/m2/d), followed by the brown-water sediments (6-11 µmol N/m2/d), with the lowest rates in the clear-water sediments (0-1 µmol N/m2/d).

How to cite: Palacin-Lizarbe, C., Bertilsson, S., Siljanen, H. J., Buck, M., Kolh, L., Paul, D., Maréchal, M., Nykänen, H., Liu, T., Kiljunen, M., Aalto, S. L., Rissanen, A. J., Biasi, C., Vainikka, A., and Pumpanen, J.: Browning and mining increase the nitrous oxide production in sediments of large boreal lakes during winter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20301, https://doi.org/10.5194/egusphere-egu24-20301, 2024.

One of the most pressing issues in intensive agriculture is how we can reduce post-harvest losses of nitrogen (N) on agricultural land. In terms of N use efficiency, the focus so far has been on optimizing the amount and timing of N fertilization, including spatially targeted application (precision agriculture). However, we must be aware that this will not be sufficient to solve the problem of N surplus. The mineralization of crop residues and soil organic matter, especially after harvest, can lead to very high mineral N concentrations in the soil, which ultimately result in high N losses, mainly in the form of nitrate leaching, but also as nitrous oxide (N2O) if the excess N is not immobilized before winter. In crop rotations that do not allow the cultivation of a catch crop, e.g. before winter cereals, the N immobilization potential is by far not high enough to immobilize the available mineral N. In this case, a different approach than plant N immobilization is required to immobilize the excess N before winter.

Here, we present results from laboratory incubations and field trials with different soils under a wide range of conditions based on the stimulation of microbial biomass growth by readily available organic soil amendments. They show that effective immobilization of mineral N in large quantities (almost 100 % reduction of nitrate concentration in the soil) is possible for several months, even under winter conditions. A consistent picture emerges from the results, suggesting that the optimal and longest-lasting effect of N immobilization can be achieved with nitrogen-free organic compounds that are moderately available to microorganisms (i.e., within several weeks rather than a few days). If the microorganisms are offered compounds that are too readily available (extreme case: glucose), a rapid stimulating effect can be triggered, which, however, does not last long enough to immobilize N for several months due to too early remineralization. If too recalcitrant organic compounds are introduced into the soil, the utilization of the additional carbon source takes too long to lead to effective N immobilization. We can therefore say that we have taken a significant step forward in understanding the mechanisms and timing of microbial N immobilization and remobilization, which may prove key to solving the N surplus problem in agriculture. However, the extent to which such management measures can be implemented in agricultural practice also depends on the political framework conditions that make them economically feasible.

How to cite: Brüggemann, N., Zhao, K., and Reichel, R.: How can we reduce post-harvest nitrogen losses on agricultural land? Evaluating the potential of easily degradable, nitrogen-free organic soil additives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20772, https://doi.org/10.5194/egusphere-egu24-20772, 2024.

EGU24-21470 | Orals | BG1.6

Off-target effects of biological nitrification inhibitors on soil microbial substrate use and enzyme activity in an agricultural soil  

Iris Karbon, Konstanze Madani, Judith Prommer, Paula Rojas, Andrew Giguere, Christopher Sedlacek, Taru Sandén, Heide Spiegel, Petra Pjevac, and Lucia Fuchslueger

High nitrification rates and substantial nitrogen (N) losses through nitrate leaching and N2O emissions make current agricultural practices unsustainable, contributing to greenhouse gas emissions and environmental pollution. Synthetic nitrification inhibitors (SNIs) can be amended with N-fertilizers to reduce the conversion of ammonia to nitrate by soil nitrifiers. SNIs aim to increase agricultural nitrogen use efficiency (NUE), but they have several disadvantages (e.g., costs, ineffectiveness in the field, possible accumulation in the food chain). The use of biological nitrification inhibitors (BNIs), naturally occurring in plant root exudates, could become an alternative to SNIs. Potential BNIs should be highly specifically targeting nitrification, but for most known BNIs it is unclear if and how they affect other soil microorganisms and biogeochemical processes.

This study aimed to investigate possible off-target effects of BNIs in agricultural soils. We tested the effect of two candidate BNIs (Methyl 3-(4-hydroxyphenyl)propionate and DL-limonene) in slurry assays on soil microbial communities from a typical Austrian agricultural field (Linz, pH 6.89±0.12, fertilized with 120 kg N ha-1 yr-1), and compared them to a known SNI (nitrapyrin), and two further nitrification inhibitors (phenylacetylene and octyne). The slurries were incubated for eight days and CO2 production, pH, as well as nitrate- and N2O accumulation were measured. At the end of the incubation, we analyzed fluorescence-based enzyme activity, as well as microbial substrate use efficiency using ‘Biolog©’ assays to test the influence on general microbial activity, selected microbial soil processes, and the effectiveness of nitrification inhibition, respectively.

Our results showed that both tested BNIs significantly reduced net nitrification rates, but also affected other biogeochemical processes, even though limonene lost some effectiveness during the incubation. MHPP was heavily respired by heterotrophic microorganisms, leading to a drop in pH and heterotrophic competition for the remaining ammonium, therefore likely acting as an indirect nitrification inhibitor. Extracellular enzymes were also affected: MHPP led to increased potential β-glucosidase activity, while nitrapyrin led to a decrease in potential phosphatase activity. General soil microbial substrate use diversity seemed to be unaffected by the input of either BNIs or SNIs. Whether or not the observed off-target effects are positive and what they mean for the large-scale application of BNIs in the agricultural industry remains to be further investigated.

How to cite: Karbon, I., Madani, K., Prommer, J., Rojas, P., Giguere, A., Sedlacek, C., Sandén, T., Spiegel, H., Pjevac, P., and Fuchslueger, L.: Off-target effects of biological nitrification inhibitors on soil microbial substrate use and enzyme activity in an agricultural soil , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21470, https://doi.org/10.5194/egusphere-egu24-21470, 2024.

EGU24-419 | ECS | Posters on site | HS2.1.12

Exploring the landscape heterogeneity and the hydrological diversity in three contrasted observatories of the French critical zone research infrastructure OZCAR 

Julien Ackerer, Sylvain Kuppel, Isabelle Braud, Sylvain Pasquet, Ophélie Fovet, Anne Probst, Marie Claire Pierret, Laurent Ruiz, Tiphaine Tallec, Nolwen Lesparre, Sylvain Weill, Christophe Flechard, Jean Luc Probst, Jean Marçais, Agnes Riviere, Florence Habets, Sandrine Anquetin, and Jerome Gaillardet

The French OZCAR critical zone network offers the opportunity to conduct multi-site studies and to explore the critical zone functioning under contrasted climate, geology, vegetation and land use. In this study, an integrated modeling of the water cycle is performed with the ecohydrological model EcH2O-iso in three long-term observatories: (1) the Naizin watershed characterized by an oceanic climate, a metamorphic bedrock and an intensive agriculture (north-west of France, AgrHyS observatory); (2) the Aurade watershed, a watershed with a warmer semi-continental oceanic climate, a sedimentary geological substratum and a crop cover with a wheat-sunflower rotation (south-west of France, Aurade observatory) and; (3) the Strengbach watershed characterized by a mountain climate, a granitic bedrock, and a beech-spruce forest cover (north-east of France, OHGE observatory).

Modeling robustness is evaluated by taking advantage of the large database for critical zone sciences including stream flow, water level in piezometers, and evapotranspiration fluxes measured from climatological stations and flux-towers located in the watersheds. Our comparative study brings these general outcomes: (1) the long term CZ evolution controlling the regolith thickness strongly impacts the total water storage in watersheds; (2) the Quaternary geomorphological evolution influences the current hydrological partitioning and the separation of hydrologically active and inactive water storage; (3) Both internal watershed characteristics and external forcings, such as current atmospheric forcing and recent land use need to be considered to infer stream persistence and to understand hydrological diversity; and (4) the observed hydrological diversity cannot be fully understood without considering a continuum of time scales in CZ evolution.

 

Overall, this work illustrates the strength of critical zone networks, allowing a new level of multi-site and comparative studies that are crossing several observatories and encompassing a wide diversity of geology and climate.

 

How to cite: Ackerer, J., Kuppel, S., Braud, I., Pasquet, S., Fovet, O., Probst, A., Pierret, M. C., Ruiz, L., Tallec, T., Lesparre, N., Weill, S., Flechard, C., Probst, J. L., Marçais, J., Riviere, A., Habets, F., Anquetin, S., and Gaillardet, J.: Exploring the landscape heterogeneity and the hydrological diversity in three contrasted observatories of the French critical zone research infrastructure OZCAR, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-419, https://doi.org/10.5194/egusphere-egu24-419, 2024.

EGU24-2143 | Posters on site | HS2.1.12

Time matters: photosynthetic vs. weathering-induced C drawdown and the role of dust inputs along a one-million-year soil weathering gradient on the Galápagos Islands 

Franz Zehetner, Martin H. Gerzabek, J. Gregory Shellnutt, Pei-Hao Chen, I Nyoman Candra, Kuo-Fang Huang, and Der-Chuen Lee

The Galápagos archipelago, a chain of islands formed by hotspot volcanism on the Nazca tectonic plate, exhibits a pronounced rock age gradient with distance from the volcanic hotspot from west to east. Here, we investigate chemical weathering along a soil chronosequence (1.5 to 1070 ka) under humid conditions. Our results show considerable loss of base cations already in the early to intermediate phases of weathering (e.g. 95% of Na and 78% of Mg lost from the topsoil after 26 ka) and almost complete loss from the entire profile in soils older than 800 ka. Depletion of Si was less pronounced, with topsoil losses of 24% and 63-68% after 26 ka and >800 ka, respectively. Total weathering flux and associated CO2 consumption rates estimated from profile-scale element losses in this study exceeded catchment-scale estimates reported for other volcanic islands or global averages during the early weathering phase, but were much lower in the intermediate and late phases. Nevertheless, total C drawdown was dominated by soil organic C sequestration (70-90% share) rather than inorganic, weathering-induced CO2 consumption during early pedogenesis (≤4.3 ka), and the relative importance switched in the intermediate and late phases (90-95% share of weathering-induced C drawdown at ≥166 ka). Dust deposition derived from a nearby ocean sediment core was <20% of total basalt mass loss at the young and intermediate-aged sites, but reached 40-60% at the older sites (>800 ka). Our results suggest that (1) young volcanic surfaces are very efficient (inorganic and organic) C sinks, (2) the development of thick soil covers at advanced pedogenic stages effectively shields the underlying rocks from further weathering, and (3) dust inputs become an increasingly important biogeochemical factor in such highly weathered environments.

How to cite: Zehetner, F., Gerzabek, M. H., Shellnutt, J. G., Chen, P.-H., Candra, I. N., Huang, K.-F., and Lee, D.-C.: Time matters: photosynthetic vs. weathering-induced C drawdown and the role of dust inputs along a one-million-year soil weathering gradient on the Galápagos Islands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2143, https://doi.org/10.5194/egusphere-egu24-2143, 2024.

EGU24-4999 | Posters on site | HS2.1.12 | Highlight

Lessons learned from 15 years of TERENO: the integrated TERrestrial ENvironmental Observatories in Germany 

Steffen Zacharias, Theresa Blume, Heye Bogena, Ralf Kiese, Erik Borg, Peter Dietrich, Susanne Liebner, Hans Peter Schmid, Martin Schrön, and Harry Vereecken

The need to develop and provide integrated observation systems to better understand and manage global and regional environmental change is one of the major challenges facing Earth system science today. In 2008, the German Helmholtz Association took up this challenge and launched the German research infrastructure TERrestrial ENvironmental Observatories (TERENO). The aim of TERENO is to establish and to maintain a network of observatories as a basis for an interdisciplinary and long-term research programme to investigate the effects of global environmental change on terrestrial ecosystems and their socio-economic consequences. State-of-the-art methods from the field of environmental monitoring, geophysics, and remote sensing are used to record and analyze states and fluxes in different environmental compartments from groundwater through the vadose zone, surface water, and biosphere, up to the lower atmosphere. To date, four observatories are part of the network, and over the past 15 years we have gained collective experience in running a long-term observing network, thereby overcoming unexpected operational and institutional challenges, exceeding expectations and facilitating new research. Today, the TERENO network is a key pillar for environmental modelling and prediction in Germany, an information hub for regional stakeholders, a nucleus for international collaboration, an important anchor for large-scale experiments, and a trigger for methodological innovation and technological progress. We will present the main lessons learned from this 15-year endeavour, and illustrate the need to continue long-term integrated environmental monitoring programmes in the future.

How to cite: Zacharias, S., Blume, T., Bogena, H., Kiese, R., Borg, E., Dietrich, P., Liebner, S., Schmid, H. P., Schrön, M., and Vereecken, H.: Lessons learned from 15 years of TERENO: the integrated TERrestrial ENvironmental Observatories in Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4999, https://doi.org/10.5194/egusphere-egu24-4999, 2024.

EGU24-7396 | Posters on site | HS2.1.12

Developing a coupled hydrological model for UK chalk catchments 

Mostaquimur Rahman, Ross Woods, Francesca Pianosi, Fai Fung, and Rafael Rosolem

Chalk forms one of the most important aquifers in the UK. Extending over large parts in the south-west, chalk aquifers account for more than half of the groundwater used for drinking in England and Wales. Groundwater held in these aquifers supports flows in chalk rivers. Hence, chalk aquifers play an important role in sustaining the riverine ecosystem. It is, therefore, important to assess and manage freshwater resources in these catchments. Here we develop and evaluate a distributed numerical model for simulating coupled subsurface and land surface hydrological processes including soil moisture variability, flow, and groundwater dynamics in chalk catchments. The parsimony and computational efficiency of this model make it possible to perform numerous simulations within a reasonable time. This allows for sensitivity analysis, calibration, and multiple scenario analysis that are useful in management decision making.

How to cite: Rahman, M., Woods, R., Pianosi, F., Fung, F., and Rosolem, R.: Developing a coupled hydrological model for UK chalk catchments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7396, https://doi.org/10.5194/egusphere-egu24-7396, 2024.

EGU24-9338 | ECS | Posters on site | HS2.1.12

The importance of in-situ soil moisture observations to evaluate the main drivers of event runoff characteristics in a small-scale catchment 

Adriane Hövel, Christine Stumpp, Heye Bogena, Andreas Lücke, and Michael Stockinger

A catchment’s runoff response to precipitation largely depends on the antecedent soil moisture in the catchment, but also on hydro-meteorological conditions in terms of, e.g., evapotranspiration. Studies investigating the effects of hydro-meteorological conditions on runoff event characteristics at the small catchment scale with daily temporal resolution mostly used surrogate measures for soil moisture, e.g., derived from hydrological models or using the antecedent precipitation index (API). Here, we applied a time-series based pattern search to 11 years of daily in-situ measured soil moisture in three depths (5, 20, 50 cm) at 33 locations in the Rollesbroich catchment (40 ha) in Germany to identify key variables influencing runoff event characteristics under similar wetness patterns. After identifying wetness patterns, we split the corresponding runoff responses into similar and dissimilar ones by means of goodness-of-fit criteria and analyzed their respective hydro-meteorological variables and event runoff coefficients (ERC), i.e., the proportion of rainfall that transforms into runoff during an event. Results showed that for similar soil moisture patterns, mean potential evapotranspiration, and antecedent soil moisture in all three depths had a smaller standard deviation for similar runoff responses than for dissimilar. This indicates a larger influence on the runoff response compared to rainfall-derived variables such as total event rainfall, maximum event rainfall intensity, or API. Furthermore, during runoff events under similar wetness conditions, the Spearman rank correlation coefficient (ρ) indicated a low average correlation between ERC and API (ρ=0.17). In terms of antecedent soil moisture conditions, the highest correlation between ERC and antecedent soil moisture was observed in the topsoil at 5 cm depth (ρ=0.43), while at 20 cm (ρ=0.16) and 50 cm (ρ=0.30) depths, the correlations were comparatively lower. Our study indicates that using the API as a substitute for antecedent wetness conditions may not be able to comprehensively reflect the relation between the runoff response and antecedent soil moisture conditions in the topsoil in the given catchment. Consequently, the results show that topsoil moisture measurements are more suitable than the surrogate API for assessing the impact of hydro-meteorological variables on daily runoff characteristics.

How to cite: Hövel, A., Stumpp, C., Bogena, H., Lücke, A., and Stockinger, M.: The importance of in-situ soil moisture observations to evaluate the main drivers of event runoff characteristics in a small-scale catchment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9338, https://doi.org/10.5194/egusphere-egu24-9338, 2024.

EGU24-9375 | ECS | Posters on site | HS2.1.12

Link between groundwater storage and landscape changes in mountainous areas: the Kahule Khola watershed (Nepal) 

Kapiolani Teagai, John Armitage, Léo Agélas, Christoff Andermann, and Niels Hovius

In many watersheds of various sizes, the role played by groundwater to sustain river flow is still misunderstood. This is the case in mountainous areas where geological features as fractures, altered or unaltered bedrocks and steep slopes notably play an important role for storing groundwater into the subsurface. The groundwater support to low flows was considered for a long time as a minor contribution, due to the steep slopes in those areas. But in Nepal, it is estimated that 2/3 of the volume of rivers comes from the exfiltration of groundwater through resurgences. Though several attempts were made with numerical modelling based on data monitoring and field surveys to quantify river-groundwater exchanged fluxes, some ambiguities remain. Especially regarding the impact of landscape change in a mountainous topography. The aim of this work is to characterize the subsurface infiltration, recharge, and storage mechanisms of a mountainous hydrogeological system in the Himalayas using field investigations and numerical modelling. In the Kahule Khola watershed (Nepal), a steep catchment of 33 km² whose altitudes range between 1000 and 3500 masl, various field experiments were made to identify groundwater pathways into the altered subsurface and to catch the river/groundwater interactions: seismic and electric surveys (ERT), infiltration tests, physical and isotopic measurements of springs/streams and the water tracking on the surface with loggers installed along gullies in the overall watershed. The region is submitted to intense rainfall as monsoon, intercalated by dry periods in which the river flow is still sustained. Moreover, by closing ancient fractures and opening new ones, earthquakes can deviate springs and change the surface water/groundwater pathways. This contributes to reshaping the landscape. However, the spatial and temporal contribution of groundwater to maintain a baseflow in the river is not quantified yet, in space and time. The ERT data from a time-lapse realized before and after monsoon show a deep alteration zone with a shallow humid layer of 10 m thick at least all year long under the slopes. Areas of low resistivity reveal infiltration zones and preferential flow paths. These areas are recharged in the wet season and drained in the dry season. At the surface, we estimate an average hydraulic conductivity at saturation of 3,5.10-5 m.s-1 in 150 cm depth which suggest an infiltration rate higher than the average rainfall rate (~3000 mm.year-1). In order to quantify the groundwater storage into the subsurface, a numerical groundwater model in 2D has been developed (Python) and is able to simulate and quantify the water storage dynamics of a spatial and temporal pre-defined domain. The data measured on the field will be used to define the initial conditions of future scenarios.

How to cite: Teagai, K., Armitage, J., Agélas, L., Andermann, C., and Hovius, N.: Link between groundwater storage and landscape changes in mountainous areas: the Kahule Khola watershed (Nepal), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9375, https://doi.org/10.5194/egusphere-egu24-9375, 2024.

EGU24-13095 | Posters on site | HS2.1.12

Hydrological, biogeochemical, and ecological linkages at the land-sea margin: Insights from a coastal critical zone network 

Holly Michael, Dannielle Pratt, Yu-Ping Chin, Sergio Fagherazzi, Keryn Gedan, Matthew Kirwan, Angelia Seyfferth, Lee Slater, Stephanie Stotts, and Katherine Tully

Ghost forests and abandoned farms are stark indicators of ecological change along world coastlines, caused by sea level rise (SLR). These changes adversely affect terrestrial ecosystems and economies, but expanding coastal marshes resulting from SLR also provide crucial ecosystem services such as carbon sequestration and mediate material fluxes to the ocean. A US-NSF Critical Zone Network project was designed to understand the hydrological, ecological, geomorphological, and biogeochemical processes that are altering the functioning of the marsh-upland transition in the coastal critical zone. We have instrumented six sites in the mid-Atlantic region of the US, along the coastlines of the Atlantic Ocean, Delaware Bay, and Chesapeake Bay where marshes are rapidly encroaching into forests and farmland. Field observations, laboratory experiments, and modeling are revealing the drivers and impacts of coastal change, as well as feedbacks among competing processes that accelerate or reduce rates and magnitude of change. We discuss examples of processes and feedbacks and highlight the importance of interdisciplinary exploration and synthesis in advancing process understanding at the land-sea transition.

How to cite: Michael, H., Pratt, D., Chin, Y.-P., Fagherazzi, S., Gedan, K., Kirwan, M., Seyfferth, A., Slater, L., Stotts, S., and Tully, K.: Hydrological, biogeochemical, and ecological linkages at the land-sea margin: Insights from a coastal critical zone network, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13095, https://doi.org/10.5194/egusphere-egu24-13095, 2024.

EGU24-13395 | Posters on site | HS2.1.12

Exploring Earth's Critical Zone Through the U.S. Critical Zone Collaborative Network 

Elizabeth W. Boyer, Bhavna Arora, Emma Aronson, Holly Barnard, Steven Holbrook, Jeffery S. Horsburgh, Lixin Jin, Praveen Kumar, Holly Michael, Jeff Munroe, Julia Perdrial, Claire Welty, and Jordan Read

The Critical Zone Collaborative Network (CZ Net) is a national research initiative in the United States supporting investigations of the Earth's critical zone (CZ) -- the vital near-surface environment extending from the top of the vegetation canopy to the weathered bedrock beneath. CZ Net fosters collaboration, data sharing, and interdisciplinary research to understand complex landscapes. The network comprises nine thematic clusters covering diverse geological, climatic, and land use settings. The thematic clusters explore many areas, including bedrock geology's effects on landscapes and ecosystems, ecosystem responses to climate and land-use disturbances, processes occurring between land and sea affected by sea-level rise, land-water interactions in agricultural regions, water and carbon cycles in arid regions, the impact of mineral dust transported in the atmosphere on ecosystems, water storage's influence on landscape and ecosystem processes, relationships between landscapes and microbial communities, and ecosystem processes in cities. A coordinating hub provides cross-cluster support. In the presentation, we introduce CZ Net and the focal research areas of each thematic cluster. We consider synthesis work addressing environmental challenges faced by the CZ, which is under increasing pressure to meet societal needs while safeguarding the environment for future generations. Further, we discuss opportunities for engagement with the network, reflecting CZ Net's dedication to advancing knowledge and addressing critical environmental issues through collaborative efforts. International coordination through developing a network of networks can foster collaborative research that transcends national boundaries, allowing scientists to combine expertise, data, and resources for a deeper understanding of CZ processes. Such collaboration is imperative for addressing pressing global environmental challenges.

How to cite: Boyer, E. W., Arora, B., Aronson, E., Barnard, H., Holbrook, S., Horsburgh, J. S., Jin, L., Kumar, P., Michael, H., Munroe, J., Perdrial, J., Welty, C., and Read, J.: Exploring Earth's Critical Zone Through the U.S. Critical Zone Collaborative Network, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13395, https://doi.org/10.5194/egusphere-egu24-13395, 2024.

EGU24-15452 | ECS | Posters on site | HS2.1.12

Exploring fluvial morphodynamics through scales  

Boris Gailleton, Philippe Steer, Philippe Davy, and Wolfgang Schwanghart

Surface processes control mass transfer efficiency on Earth, responding to tectonic and climatic forcings. These forcings impact landscape dynamics across a wide range of temporal scales, from individual events (e.g., storms) to geological time spans (e.g., Cenozoic climate cooling). Bridging these temporal scales poses a significant challenge for Landscape Evolution Models (LEMs). While LEMs are conventionally employed to study the effects of climate or tectonics on landscape dynamics over geological time, numerical methods simulating short-term processes such as landslides, floods, erosion, and sediment transport struggle to be projected beyond a few hundred years. 

In this contribution, we address this challenge by leveraging a recent model development—graphflood—that enables the computation of hydro-stationary water surfaces and discharge using a simplified shallow water approximation. This new model shows an order-of-magnitude improvement in speed over its predecessors, achieved through the efficiency of algorithms applied to directed acyclic graphs. Through testing induced subgraph dynamic traversals for initial calculations of a stationary state and employing GPU techniques to maintain the state to slower erosion and deposition processes, we demonstrate the potential for an additional order-of-magnitude reduction in computation time for fluvial dynamics. We also investigate how the computation of landslide runout using a shallow water approximation with a friction coefficient modified to account for velocity-weakening can be introduced within the same numerical framework. 

First, we explore various sets of fluvial erosion and deposition laws (e.g., stream power, Meyer Peter Muller) to determine the minimal representation needed for fluvial morphodynamics and projecting them across scales at the lowest computational cost. We then perturb the system with landslides processes and observe the controls on its resilience to external forcings. Lateral dynamics (e.g., lateral erosion, deposition, interaction with valley walls) and the model's ability to capture different river states (e.g., high flow vs low flow, flood) emerge as crucial elements in understanding the complexity of river responses to climato-tectonic perturbations. 

How to cite: Gailleton, B., Steer, P., Davy, P., and Schwanghart, W.: Exploring fluvial morphodynamics through scales , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15452, https://doi.org/10.5194/egusphere-egu24-15452, 2024.

EGU24-15453 | Posters on site | HS2.1.12

High Mountain Plateau Margin Critical Zone Observatory, Kaligandaki River Nepal 

Christoff Andermann, Kristen Cook, Basanta Raj Adhikari, Niels Hovius, and Rajaram Prajapati

Mountains are hotspots for earth surface processes, with very fast erosion rates, mass movements, catastrophic flooding and enhanced geochemical weathering rates. These landscapes respond quickly to external forcing by tectonics and/or climate. As a consequence, the hazard potential in mountains is very high, and mountains produce a wide range of large catastrophes which often have wide-reaching impacts on infrastructure and human lives. Furthermore, mountains can be considered as the water towers of the world, as they are very effective at harvesting water from the atmosphere, storing it, and redistributing it to the adjacent lowlands. The key role of mountain regions can be extended endlessly to other disciplines such as ecology, climatology, social sciences and so forth. Yet, despite their importance, high mountains remain inaccessible and notoriously understudied. High elevation terrains are only lightly covered by monitoring systems, with elevations >2500 m asl. widely underrepresented in global monitoring networks (Shahgedanova et al., 2021). The Himalayan mountains are particularly poorly covered by coordinated monitoring observatories.

In this contribution we present the set up and overview results of the ~last 10 years of integrated critical zone monitoring in the Kaligandaki Catchment in the central Himalayas in Nepal.

Motivated by fundamental research questions on coupled surface process and the high mountain water cycle in the Himalayan mountain range, we began observation in the Kaligandaki Catchment with two major stations for climatological and hydrological monitoring that have operated continuously over the past 10 years. At each location trained personal conducted manual river water sampling for river water geochemistry and suspended sediment monitoring as well as water discharge and bulk meteorological parameters. These observations were complemented by targeted short-term deployments and field sampling campaigns to cover the full spatial extent as well as the seasonal variability. Research question range from organic carbon export, climate and erosion feedback as well as water pathways in high mountains to large mass-movements and intramountain sediment storage and feedbacks with landscape evolution.

Our findings from the past 10 years of monitoring motivate the development of a more substantial observatory in the Kaligandaki catchment, which is particularly suited as a critical zone observatory in the Himalayas. The Kaligandaki is a trans-Himalayan river that connects the Tibetan Plateau through the Himalaya to the low elevation foreland. The river crosses distinct climatological, ecological, tectonic, and geomorphic zones, including the arid high elevation plateau, the rapidly uplifting high Himalaya and monsoon precipitation maxima, and the middle hills. The river corridor is highly prone to flood and landslide hazards, and is experience increasing development and human impact, particularly road construction and hydropower. In addition, the river basin is highly sensitive to changing precipitation patterns, which have brought anomalous rainfall and flooding in recent years, and to changing melting patterns, which affect water resources. Together with local partners and the international research community we are proposing this unique catchment as potential integrated mountain critical zone observatory in order to close the monitoring gap in the highest mountain range on Earth.

Literature:

Shahgedanova, M., et al. 2021, https://doi.org/10.1659/MRD-JOURNAL-D-20-00054.1

How to cite: Andermann, C., Cook, K., Adhikari, B. R., Hovius, N., and Prajapati, R.: High Mountain Plateau Margin Critical Zone Observatory, Kaligandaki River Nepal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15453, https://doi.org/10.5194/egusphere-egu24-15453, 2024.

EGU24-15523 | Posters on site | HS2.1.12

The impact of groundwater dynamics on landsliding and hillslope morphology: insights from typhoon Morakot and landscape evolution modelling 

Philippe Steer, Lucas Pelascini, Laurent Longuevergne, and Min-Hui Lo

Landslides represent a pervasive natural hazard, exerting a significant influence on hillslope morphology in steep regions. Intense rainfall events are well-established as primary triggers for landslides, particularly those characterized by high rainfall intensity, intermediate to long durations, and substantial cumulative precipitation during and before the event. While the evolving roles of soil saturation and mechanical properties are well-identified in shallow landslide occurrences, the influence of groundwater dynamics on the triggering of deep-seated or bedrock landslides remains less understood. Despite this knowledge gap, deep-seated landslides play a dominant role in the volume budget of landslide catalogs and serve as the primary geomorphological process shaping hillslope evolution in steep regions. In this study, we explore the impact of groundwater dynamics on landslide triggering. Our investigation focuses initially on landslides triggered during Typhoon Morakot, examining their relationship with water table fluctuations derived from the HydroModPy 3D hydrogeological model, forced by water recharge data obtained from the Community Land Model CLM 4.0. Analyzing several contrasting catchments, we demonstrate a strong correlation between the locations and depth of deep-seated landslides and the instability predicted by a simple landslide model that integrates pore pressure and water table depth. Notably, these predictions are valid within specific ranges of hydrogeological (i.e., aquifer thickness, porosity, and conductivity) and mechanical (i.e., cohesion and friction angle) parameters, providing valuable insights into the hydrogeological and mechanical properties of the studied catchments. In an exploratory study, we then shift our focus to the longer-term geomorphological impact of rainfall-triggered landslides on hillslope evolution and morphology. Using a coupled 2D model of water table evolution and landsliding, we investigate topographic changes at the hillslope scale, under different scenarios. Our investigation considers the influence of seasonal recharge, intense rainfall events, and hillslope hydrological convergence or divergence perpendicular to the hillslope orientation on resulting hillslope morphology and dynamics. Overall, our results particularly highlight the role of groundwater dynamics on hillslope finite shape.

How to cite: Steer, P., Pelascini, L., Longuevergne, L., and Lo, M.-H.: The impact of groundwater dynamics on landsliding and hillslope morphology: insights from typhoon Morakot and landscape evolution modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15523, https://doi.org/10.5194/egusphere-egu24-15523, 2024.

EGU24-17282 | ECS | Posters on site | HS2.1.12

Assessing the impact of stress–dependent hydraulic properties on hillslope-scale groundwater flow and transport 

Ronny Figueroa, Clément Roques, Ronan Abherve, Landon Halloran, and Benoit Valley

The occurrence of springs and their connectivity within stream networks is typically associated with three key controlling factors: climate, topography and the distribution of hydraulic properties. In crystalline media, this distribution is often related to lithology and the presence of fractures. In addition, tectonic and topographic stresses can modify properties through compressive and extensional forces acting on the rock mass and fractures. However, these controls are rarely considered for hillslope scale applications. The aim of this research is to investigate the effects of stress on bedrock hydraulic properties and their implications for groundwater flow and transport at the hillslope scale. A numerical experiment has been designed that combines linear poroelasticity to simulate the distribution of permeability and porosity, together with groundwater flow and transport simulations. Different slope and stress conditions are examined, providing a comprehensive sensitivity analysis framework.

Our results show that vertical stress leads to a decrease in permeability and porosity at depth, following an exponential-like trend. Increasing the proportion of lateral stresses relative to the total vertical stresses reduces the mean permeability and porosity and increases the variance in the distribution along the hillslope. For high values of lateral stress, a low permeability domain develops downslope at the valley bottom due to the accumulation of compressive stresses, while the extensive regime at the crest provides higher permeabilities. As expected, groundwater flow simulations revealed that the partitioning of flow paths is strongly influenced by such heterogeneous stress-induced permeability and porosity fields. As stress increases, groundwater flow becomes more channelized in the near subsurface, strongly deviating from the classical Dupuit model. We also found that the distribution of normalized groundwater discharge rates shows higher values in the upper part of the seepage zone than in the lower part. By analyzing the results of particle tracking simulations, we found that mean residence times increase with higher external stress due to a decrease in mean permeability. In addition, the shape of the residence time distribution is strongly modified by the channeling of groundwater flow with increasing lateral stress, with the probability of shorter residence times increasing as stress increases. We discuss the implications of these fundamental results for our understanding of the role of stress in groundwater-dependent systems, with important insights into the recharge, storage and discharge mechanisms that may control the resilience of landscapes to the effects of climate change.

How to cite: Figueroa, R., Roques, C., Abherve, R., Halloran, L., and Valley, B.: Assessing the impact of stress–dependent hydraulic properties on hillslope-scale groundwater flow and transport, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17282, https://doi.org/10.5194/egusphere-egu24-17282, 2024.

EGU24-17490 | Posters on site | HS2.1.12 | Highlight

Hydroclimatic versus geochemical controls on silicate weathering rates 

Sylvain Kuppel, Yves Goddéris, Jean Riotte, and Laurent Ruiz

Water is the first order controlling factor of the weathering reactions. In the recent years, efforts have been made towards the building of model cascades able to simulate the water fluxes and the residence time of the water in the various compartments of the critical zone. Those hydrological constrains are then injected into numerical models simulating the water-rock interactions from the surface down to the impervious bedrock. In this contribution, we describe such a model cascade, where the water-rock interaction model WITCH is fed by the process-based ecohydrological model EcH2O-iso. This model cascade, WITCH2O, is designed for the modeling of water fluxes & stores, as well as the weathering reactions and transport of weathering products (including atmospheric CO2 consumption), from the vertical profile to the catchment scale, and from the submonthly to decadal time scales. We deployed WITCH2O along a gneiss-saprolite-ferralsol profile in a small tropical forested catchment in peninsular India. Long-term observations of water and geochemical fluxes are available, allowing for a 2-step model calibration and evaluation (hydrological and geochemical) across the different processes simulated. Using various temporal averages of simulated water fluxes and stores, preliminary results highlight that seasonal hydrological variability (driven by monsoon dynamics and deep root water uptake) is key for capturing groundwater nutrient concentrations, despite highly-buffered water table variations. We also explore how this non-linear dependence of weathering fluxes upon hydrological states is modulated by the propagation of uncertainties regarding i) modeled hydrology and ii) uncertainties in geohydrochemical properties (e.g. reactive surface and mineral abundance).

How to cite: Kuppel, S., Goddéris, Y., Riotte, J., and Ruiz, L.: Hydroclimatic versus geochemical controls on silicate weathering rates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17490, https://doi.org/10.5194/egusphere-egu24-17490, 2024.

EGU24-20178 | Posters on site | HS2.1.12

Coevolution in the critical zone: the key role of fast hydrologic processes 

Patricia Saco, Juan Quijano Baron, Jose Rodriguez, Mariano Moreno de las Heras, and Samira Azadi

Feedback effects between hydrology, vegetation and erosion processes are pervasive across landscapes. These tight interactions lead to the coevolution of landscape patterns that modulate landform shape and regulate many other critical zone processes. We study these feedbacks and interactions using simulations from landform evolution models that account for the effect (and feedbacks) of spatially and temporally varying hydrologic pathways and vegetation over landscapes displaying a variety of vegetation patterns. 

We first present results from a landscape evolution modelling framework, that accounts for a comprehensive representation of hydrology and vegetation, including the effect of various vegetation pools on erosion processes. The model includes interacting modules for hydrology, dynamic vegetation, biomass pools partition, and landform evolution. Our simulations indicate that each of the biomass pools provides a specific erosion protection mechanism at a different time of the year. As rainfall events and the resulting vegetation growth and protection are asynchronous, the maximum values of erosion are associated with runoff at the beginning of the rainy season when vegetation protection is not as its maximum. These results show how rapid hydrological processes affecting vegetation have long term implications for landform development. Results for a Eucalyptus savanna landscape study site in the Northern Territory (Australia) showed that models that do not account for the vegetation dynamics can result in prediction errors of up to 80%.  

We also present simulations of the coevolution of landforms and vegetation patterns in selected sites with patchy Acacia Aneura (Mulga) vegetation.  These sites display a sparse vegetation cover and strong patterns of surface water redistribution, with runoff sources located in the bare areas and sinks in the vegetation patches. This effect triggers high spatial variability of erosion/deposition rates that affects the evolving topography and induces feedbacks that shape the dynamic vegetation patterns. We run simulations using rainfall, vegetation and erosion data, and vegetation parameters previously calibrated for Mulga sites in the Northern territory. We further investigate the effect of alterations in hydrologic connectivity induced by climate change and/or anthropogenic activities, which affect water and sediment redistribution and can be linked to loss of resources leading to degradation. We find that an increase in hydrologic connectivity can trigger changes in vegetation patterns inducing feedbacks with landforms leading to degraded states. These transitions display non-linear behaviour and, in some cases, can lead to thresholds with an abrupt reduction in productivity. Critical implications for management and restoration are discussed.  

How to cite: Saco, P., Quijano Baron, J., Rodriguez, J., Moreno de las Heras, M., and Azadi, S.: Coevolution in the critical zone: the key role of fast hydrologic processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20178, https://doi.org/10.5194/egusphere-egu24-20178, 2024.

EGU24-2217 | ECS | Orals | HS8.1.2

What controls the development of heterogenous dissolution patterns in carbonate rocks? 

Atefeh Vafaie, Josep M. Soler, Jordi Cama, Iman R. Kivi, Samuel Krevor, and Victor Vilarrasa

Porosity and permeability changes are anticipated when carbonate rocks are percolated with and dissolved by acidic fluids. The ability to predict the location, extent, and impact of these changes could benefit acid-relevant operations in carbonate rocks, specifically CO2 storage by improving our estimates of CO2 flow and storage performance in the subsurface. In this work, we combine percolation experiments and numerical simulations to capture the chemical effects of CO2-saturated water (weak acid) and HCl solution (strong acid) on cm-scale limestone cores. Numerical simulations are parameterized and validated against experimental data, including effluent solution chemistry, porosity distribution, and observed dissolution features in CT images of the reacted specimens. CT imaging data of intact cores are employed to construct porosity and permeability distribution maps over the core domain serving as input for reactive transport models of the experiments. The results indicate that the pore space heterogeneity controls the mineral dissolution from the onset of the acidic fluid injections, while the acid type becomes progressively important as the dissolution front further penetrates the rock. The compact dissolution pattern formed in the HCl-treated cores due to the complete dissociation of the strong acid could be numerically simulated using a generalized power-law porosity-permeability relationship with a power value of 3, applied at the numerical grid scale. However, the formation of the lengthwise wormhole in CO2-treated cores due to partial dissociation of the weak acid and its buffering capacity could be only simulated using a large power value of 15 at the grid scale in the porosity-permeability relationship. This exponent increases to 27.6 for the bulk flow behavior of the limestone core containing the wormhole, illustrating large-scale dependence of acid-induced permeability evolutions in carbonate rocks. These findings highlight the need for developing robust upscaling approaches to account for the hydraulic behavior of reactive, intrinsically heterogeneous carbonate rocks in large-scale simulations.

How to cite: Vafaie, A., Soler, J. M., Cama, J., Kivi, I. R., Krevor, S., and Vilarrasa, V.: What controls the development of heterogenous dissolution patterns in carbonate rocks?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2217, https://doi.org/10.5194/egusphere-egu24-2217, 2024.

EGU24-2723 | ECS | Posters on site | HS8.1.2

Effect of Hydrophobicity on the Transport of Carbon Nanoparticles in Saturated and Unsaturated Porous Media 

Bahareh Hassanpour, Daniel May, Laura SinClair, Tammo Steenhuis, and Lawrence Cathles

Carbon-based nanoparticles (CNPs) are increasingly used for environmental and industrial applications such as in pharmaceuticals, energy production, and water and wastewater treatment. Thus, it is crucial to understand their interactions and transport in porous media. Here, we examine the impact of CNP hydrophobicity and porous medium surface area on their transport. We use CNPs that are synthesized from citric acid and ethanolamine and are fluorescent. They exhibit synthesis-temperature-dependent hydrophobicity and were synthesized at four temperatures: 190 °C, 210 °C, 230 °C, and 250 °C. The experiments were conducted by flowing these CNPs in sand-packed columns under saturated and unsaturated conditions. To examine the impact of the surface area of sand on CNP transport, the sands packed in the columns had three surface areas. In addition, a particle transport model in HYDRUS 1D was used to model the transport.

Together, our experimental and modeling noted four important observations. The first observation indicated the importance of hydrophobicity on CNP transport. There was a 55% difference between the recovery of CNPs synthesized at 190 °C compared to those synthesized at 250 °C. Second, a five-fold increase in surface area yielded a 17% decrease in the recovery of CNPs, suggesting the role of sand surface area on CNP recovery. Third, due to the small size of CNPs relative to the water film on the sand surface, there were no significant differences in the mass recovery of CNPs under unsaturated and saturated conditions. Fourth, the particle transport model with a Langmuirian site blocking term successfully simulated the transport of CNPs. There was approximately a 10-fold increase in the adsorption coefficients for hydrophobic CNPs compared to hydrophilic ones. In sum, our observations and modeling demonstrated that hydrophobicity was a major factor that impacted the transport of CNPs.

 

 

How to cite: Hassanpour, B., May, D., SinClair, L., Steenhuis, T., and Cathles, L.: Effect of Hydrophobicity on the Transport of Carbon Nanoparticles in Saturated and Unsaturated Porous Media, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2723, https://doi.org/10.5194/egusphere-egu24-2723, 2024.

EGU24-3082 | ECS | Orals | HS8.1.2

Investigation of mineral dissolution kinetics through Atomic Force Microscopy 

Chiara Recalcati, Martina Siena, Monica Riva, Monica Bollani, and Alberto Guadagnini

We illustrate an experimental platform grounded on Atomic Force Microscopy (AFM) imaging enabling one to evaluate nanometer-scale absolute material fluxes across a mineral surface subject to precipitation/dissolution reaction under continuous flow. Reactive phenomena of this kind taking place at the solid-fluid interface have a pivotal role in driving alterations of the fundamental properties of natural geologic systems (including, e.g., porosity, permeability, and storage capacity). High resolution experimental observations document that several kinetic processes contribute to the overall reaction. These, in turn, yield a markedly heterogeneous distribution of reaction rates. The latter cannot be characterized through average rate values. Current challenges limiting our ability to characterize such heterogeneity include the establishment of a reliable integrated experimental platform that allows employing AFM imaging to evaluate real-time and in situ absolute material fluxes across the mineral surface. These can then be employed to enrich and expand typical analyses of the evolution of surface morphology. We overcome these barriers and provide spatial distributions of rates observed at the nanoscale across the surface of a calcite crystal subject to dissolution. We then interpret experimental observations through a stochastic approach. The latter is designed to embed the action of diverse kinetic modes corresponding to different mechanistic processes taking place across the surface and driving the spatial heterogeneity of the reaction.

How to cite: Recalcati, C., Siena, M., Riva, M., Bollani, M., and Guadagnini, A.: Investigation of mineral dissolution kinetics through Atomic Force Microscopy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3082, https://doi.org/10.5194/egusphere-egu24-3082, 2024.

EGU24-3554 | ECS | Orals | HS8.1.2

Experimental and numerical study of CO2 sequestration in a heterogeneous porous medium 

Rima Benhammadi, Patrice Meunier, Marco Dentz, and Juan J. Hidalgo

We investigate both experimentally and numerically the gravitational instability due to the dissolution of carbon dioxide into brine in heterogeneous porous media. To do so, we consider a two dimensional Hele-Shaw cell of 0.073 m x 0.49 m, in which a log-normally distributed permeability field has been engraved. Permeability fields with a mean gap of 370 µm and 500 µm, a correlation length  λx = 0.032 m, λz = 0.016 m and a variance of 0.137 are considered in order to see the effect of heterogeneity on the convective instability. Experiments in cells with a constant gap are also performed. The CO2 partial pressure is varied between 12% and 85%. The convective patterns are visualized using a pH sensitive dye (Bromocresol green).

Experimental results show that fingers tend to merge faster in the heterogeneous cases than in the homogeneous ones and tend to look more distorted. The number of fingers at late times is smaller in the heterogeneous cases than in the homogeneous ones. The gap thickness has little effect in the heterogenous cells but a small increase of fingers with the gap width is observed in the absence of heterogeneity. Moreover, the amplitude of the instability is higher in the case of the heterogeneous experiments whereas the growth rate at early times is a bit smaller compared to the homogeneous ones. The amplitude of the instability at late times is higher for the cases with bigger gap thickness for homogeneous and heterogeneous cases. Increasing the partial pressure of CO2 intensifies the amplitude of the instability as well as the number of fingers at a given time. As for the Numerical simulations, they reproduce well the evolution of the number of fingers and the amplitude of the instability. However, the numerical time for the onset of convection is longer.

Key words: CO2 sequestration, Rayleigh-Taylor instability, heterogeneity, fingering patterns, amplitude, growth rate.

How to cite: Benhammadi, R., Meunier, P., Dentz, M., and Hidalgo, J. J.: Experimental and numerical study of CO2 sequestration in a heterogeneous porous medium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3554, https://doi.org/10.5194/egusphere-egu24-3554, 2024.

EGU24-4016 | ECS | Orals | HS8.1.2

Experiment and simulation of quasistatic capillary rise in an ink-bottle setup resultingin pressure-saturation (p-s) hysteresis 

Animesh Nepal, Juan J. Hidalgo, Jordi Ortin, Ivan Lunati, and Marco Dentz

During imbibition, fluid-fluid interface at the inlet of a constriction experiences an increase in capillary force that results in rapid fluid invasion known as Haines jump. During drainage, the interface gets pinned at the end of the constriction, which causes pressure-saturation (p-s) trajectories to follow different paths during imbibition and drainage resulting in p-s hysteresis. In this work, we performed quasistatic two-phase flow experiments and simulations of cyclic imbibition and drainage in a capillary tube with a constriction (ink-bottle) to have a quantitative understanding of p-s hysteresis. In the setup, drainage and imbibition were driven by quasitatically changing the pressure gradient between the inlet and the outlet of the tube. The experimental results were compared with the results from a numerical model in OpenFOAM, which solves the Navier-Stokes equations employing Volume of Fluid method to calculate the position of the interface. We observed that multiphase flow through a single constriction revealed distinct p-s hysteresis, a common trait in porous media. The steeper the constriction, the more pronounced the p-s hysteresis and vice versa. We derived an analytical solution to obtain the p-s curve and compared the results obtained from experiments and simulations. This comparative study will allow us to quantitatively link the pore-scale capillary physics to large-scale p-s hysteresis.

How to cite: Nepal, A., Hidalgo, J. J., Ortin, J., Lunati, I., and Dentz, M.: Experiment and simulation of quasistatic capillary rise in an ink-bottle setup resultingin pressure-saturation (p-s) hysteresis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4016, https://doi.org/10.5194/egusphere-egu24-4016, 2024.

The deep geological disposal method is a prominent approach for the management of high-level radioactive waste, and understanding the behavior of uranium under various geochemical conditions is essential for this purpose. To predict the behavior of uranium in the field, it is necessary to evaluate not only the transport of uranium but also the reactions between host rock and groundwater at the field site. In this regard, we evaluated the behavior of uranium in the underground environment by analyzing the temporal and spatial changes in uranium geochemistry in response to water-rock reactions. This was achieved through column experiments using rocks containing uranium ore bodies and groundwater from a natural analogue study site in Korea. Two columns (NA-PJ1 and NA-PJ2) were prepared by collecting coaly slate materials containing uranium minerals sourced from the Okcheon Metamorphic Belt in Korea. NA-PJ1 was filled with coaly slate (0.025 ~ 2 mm grain size) collected from the study area, while NA-PJ2 included a mixture of coaly slate and limestone (10 wt%) to provide pH buffering. The input solutions to the columns were artificial groundwater manufactured with a chemistry similar to that of the groundwater at the study site. The artificial groundwater was purged with Ar gas before the experiment to minimize the ingress of dissolved oxygen (DO) from the atmosphere. To observe spatial and temporal changes in geochemistry resulting from the interactions between the artificial groundwater and the reactive materials inside the columns, water samplings were performed at 0, 5, 10, 15, 20, 25, 30, 35, and 40 cm from the column influent. The results consistently showed low and stable DO concentrations in both columns. The pH in NA-PJ1 initially exhibited the highest value at 0 cm but gradually decreased to below 4.5. This was attributed to the insufficient carbonate buffering capacity to neutralize hydrogen ions generated by the oxidation of iron sulfide in coaly slate. In NA-PJ2, in contrast, the pH remained around 8. Uranium concentration in NA-PJ1 increased gradually with distance. It was determined that uranium was released through the dissolution of uranium minerals (i.e., uraninite and ekanite). Subsequently, the released uranium formed uranium aqueous complexes with dissolved F or SO4 induced by iron sulfide oxidation. Furthermore, it was shown that uranium in NA-PJ1 formed UO2CO3(aq) complexes closer to the column influent, while it formed more UO2SO4(aq) complexes with increasing distance. This study contributes to understanding the transport and reaction characteristics of uranium in groundwater, ultimately aiding in the management of high-level radioactive waste in a deep geological disposal site.

How to cite: Lim, S., Cho, H., Noh, S., and Jeen, S.-W.: Evaluating the Behavior of Uranium Through Column Experiments Using Artificial Groundwater and Coaly Slate from a Natural Analogue Study Site in Korea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5012, https://doi.org/10.5194/egusphere-egu24-5012, 2024.

Random walk particle tracking (RWPT) methods employ a Lagrangian discretization of solute plumes into point particles to numerically solve the advection-dispersion equation. Their recognized advantages over more traditional grid-based Eulerian methods regarding numerical stability and numerical dispersion make them ideal candidates to simulate complex reactive fronts in heterogeneous media. However, handling nontrivial boundary conditions remains a challenge, restricting the range of interface processes that can be simulated. We derive and validate a new collision-based approach to implement a broad class of generalized Robin-type boundary conditions, representing the balance between diffusive fluxes and an arbitrary nonlinear function of the transported and surface reactant concentrations. This formulation allows for modeling arbitrary coupled sets of nonlinear surface reactions within the classical RWPT framework, thus opening new opportunities for simulating pore-scale reactive transport in the subsurface. The collision-based nature of the proposed technique allows for estimating surface reaction rates based on single-particle collisions with the reactive interface. Thus, it does not require concentration field reconstructions or multi-particle searches. We verify the method for a coupled set of nonlinear mass-action reactions under pure diffusion and for nonlinear kinetics representing calcite dissolution in a model porous medium.

How to cite: Aquino, T.: Simulating pore-scale nonlinear reactions at the fluid-solid interface using random walk particle tracking, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5519, https://doi.org/10.5194/egusphere-egu24-5519, 2024.

The combined action of stretching and diffusion within solute plumes controls mixing in flows through soils and fractured rocks, ultimately affecting the rates of subsurface reactions. Stretching enhances mixing by increasing the area available for diffusion to act and steepening concentration gradients. Ultimately, the resulting solute filaments coalesce which drives the transition of concentration profiles toward uniformity. While the role of stretching is well described by current models, the effect of coalescence on mixing has been more challenging to understand, partly because the spatial extent and distribution of coalesced regions depends on the geometric structure of the medium. Here we present a new set of experiments designed to isolate the role of coalescence on mixing in porous media. Using stereolithography 3D printing, we have fabricated transparent porous models with different geometric structures. By imaging pulses of fluorescent dye as they mix in flows through these models, we have resolved the dependence of mixing rates on both Peclet number and the medium geometry. We observe that converging streamlines downstream of stagnation points establish local zones in the flow where coalescence is enhanced. From these observations, we describe the statistics of coalescence and its impact on mixing and reaction rates. These findings support the ongoing effort to improve our predictions of mixing and reactive transport in the subsurface.

How to cite: Pierce, K., Le Borgne, T., and Linga, G.: Experimental imaging of pore scale stretching and coalescence as drivers for solute mixing in porous media, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5575, https://doi.org/10.5194/egusphere-egu24-5575, 2024.

EGU24-5680 | ECS | Orals | HS8.1.2

Vapor condensation in fractured porous media revealed by in-situ rapid neutron tomography and numerical modeling 

Arash Nemati, Bratislav Lukić, Alessandro Tengattini, Matthieu Briffaut, and Philippe Sechet

The study of phase change in processes involving two-phase flow in porous media remains relatively under-explored due to the intricate nature arising from the strong coupling between heat and mass transfer and the heterogeneity of the medium. However, condensation in porous media plays a crucial role in various applications, including steam-based gas recovery, underground contamination removal, the integrity of geothermal, CO2 storage reservoirs, durability of concrete structure, and porous fabric and insulation condensation. The objective of this study is to provide a deeper understanding of the subject by conducting rapid neutron tomographies during vapor injection experiments and introducing a novel numerical approach to model the process.

The identification and quantification of water is revealed using 3D rapid in-situ neutron imaging, acquired at 30-second intervals per tomography. Such temporal resolution is possible thanks to the high neutron flux of the Institute Laue Langevin Grenoble (ILL) using the imaging instrument NeXT (Neutron and X-ray Tomograph [1]). The experiments were preceded by a calibration and correction campaign where the quantification of water content was fitted to empirical correlation and the spurious deviations arising from the scattering of neutrons were accounted for using the black body (BB) grid method [2]. The in-situ experiment consists of the injection of a predefined mixture of air and water vapor at a constant flow rate into cylindrical samples of Fontainebleau sandstone with a splitting crack along their height. Successive rapid neutron tomographies are acquired during the injection of vapor to investigate the evolution of water content and condensation process inside the sample. Furthermore, X-ray tomography is performed prior to the vapor injection, and part of the sample is scanned by synchrotron microtomography with 6.5 micrometers pixel size. This allows for extracting the microstructure and morphology of the crack and porous matrix, and its impact on the spatio-temporal accumulation of liquid water, and understanding its migration within the crack and matrix. The results [3,4] show that water initially emerges near the inlet and spreads toward distant areas. Condensed water generally has the tendency to occupy tighter spaces within the sample. The condensed water diffuses into the porous matrix due to capillary effects and pressure buildup in the crack.

Preliminary results of a numerical model developed in OpenFoam are also discussed. The model solves heat transfer and two-phase flow equations with phase change mass transfer terms. It is capable of modeling water condensation and temperature fields within a domain of heterogeneous porous media contributing additional insights to the phenomena.

References:

1) Tengattini, A., et al., Nucl. Instrum. Methods Phys. Res., 968, 163939 (2020)

2) Boillat, P., et al., Optics Express, 26(12), 15769-15784 (2018)

3) Gupta, R. et al., Cem. Concr. Res., 162, p. 106987. (2022)

4) Nemati, A., et al., Transp. Porous Media, 150(2), 327-357 (2023)

How to cite: Nemati, A., Lukić, B., Tengattini, A., Briffaut, M., and Sechet, P.: Vapor condensation in fractured porous media revealed by in-situ rapid neutron tomography and numerical modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5680, https://doi.org/10.5194/egusphere-egu24-5680, 2024.

EGU24-5705 | ECS | Posters on site | HS8.1.2

Unraveling biogeochemical transformation of organic carbon and nitrogen compounds in groundwater along a hill slope transect 

Thanh Quynh Duong, Anke Hildebrandt, and Martin Thullner

The origin and the fate of organic carbon and nitrogen compounds in groundwater play an important role in the global biogeochemical cycling of carbon and nutrients and have implications for drinking water production. While the input of these compounds into the subsurface is strongly driven by land use, their fate in subsurface environments such as fractured aquifers is controlled by a complex interplay between hydrological and biogeochemical processes at different temporal and spatial scales and is poorly understood yet. Determining the fate of these organic compounds in fractured aquifers is additionally challenging due to spatial heterogeneities at various scales down to centimeter scales, leading to a multitude of flow paths of different lengths and residence times.  This causes an overlap of solute residence times for compounds moving from the surface through the subsurface to surface waters or groundwater observation wells, stretching from days to many years, thus affecting the dynamics of the biogeochemical processes and the quantitative assessment of compound fluxes. To address this issue, a travel time-based modeling approach is employed to simulate the fate of carbon and nitrogen compounds in groundwater along a hill slope transect of the Hainich Critical Zone Exploratory (CZE), located northwest of Thuringia (central Germany). This transect is set up under the Collaborative Research Center AQUADIVA. It is subject to an intensive surface and subsurface monitoring program providing groundwater quality and quantity data. Travel time distributions obtained from a numerical groundwater flow model of the transect and its vicinity are combined with a set of numerical 1D simulations describing the biogeochemical transformations of carbon and nitrogen. The simulated complex reaction network describes the transformation of carbon and nitrogen along individual groundwater flow paths, which considers varying microbial functional groups such as aerobes and anaerobes, as well as key microbial life processes under different redox conditions, including aerobic, nitrate-reducing, ammonia-oxidizing, and sulfate-reducing conditions.  The model-predicted concentrations of reactive species at various observation wells are compared to measured concentrations to validate the approach. The results show that processes on the surface strongly shape the dynamics of resulting recharge zones represented by different land use areas, which have an impact on observed concentrations at wells. Travel time distributions combined with simulations of the biogeochemical transformation along a flow path can provide a model-based interpretation of measured observations and the factors controlling them. This allows predicting fluxes of chemical species through the entire sub-catchment and their dependency on the dynamics of surface conditions.

How to cite: Duong, T. Q., Hildebrandt, A., and Thullner, M.: Unraveling biogeochemical transformation of organic carbon and nitrogen compounds in groundwater along a hill slope transect, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5705, https://doi.org/10.5194/egusphere-egu24-5705, 2024.

EGU24-6219 | ECS | Orals | HS8.1.2

Biofilm Growth in Porous Media well approximated by Fractal Multirate Mass Transfer with Advective-Diffusive Solute Exchange 

Jingjing Wang, Jesús Carrera, Maarten W. Saaltink, Jordi Petchamé-Guerrero, Graciela S. Herrera, and Cristina Valhondo

Biofilm growth in porous media changes the hydrodynamic properties of the medium: porosity and permeability decrease, and dispersivity increases. However, the first arrival of breakthrough curves (BTCs) is more reduced than derived from the reduction in porosity, and the BTC tail becomes heavier. These observations suggest the need for multicontinuum models (Multi-Rate Mass Transfer, MRMT) which describe reactive transport in heterogeneous porous media and facilitate the simulation of localized reactions often observed within biofilms. Here, we present a conceptual model of biochemical reactive transport with dynamic biofilm growth based on MRMT formulations. The model incorporates microbial growth by updating the porosity, dispersivity, and local mass exchange between mobile water and the immobile biofilm according to the stoichiometry and kinetic rate laws of biochemical reactions. This model has been successfully tested using two sets of laboratory data. We found that (1) the basic model based on the growth of uniformly sized biofilm aggregates (memory function with 1/2 slope), fails to reproduce laboratory tracer tests and rate of biofilm growth, while the fractal growth model, which we obtain by integrating the memory functions of biofilm aggregates with a power law distribution, does; (2) The biofilm memory function evolves as the biofilm grows in response to the varying aggregate size distribution; and (3) the early time portion of eluted volume BTCs are independent of flow rate, whereas the tail becomes heavier when the flow rate is decreased, that both advection controlled and diffusion controlled mass exchange coexist in biofilms.

How to cite: Wang, J., Carrera, J., Saaltink, M. W., Petchamé-Guerrero, J., Herrera, G. S., and Valhondo, C.: Biofilm Growth in Porous Media well approximated by Fractal Multirate Mass Transfer with Advective-Diffusive Solute Exchange, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6219, https://doi.org/10.5194/egusphere-egu24-6219, 2024.

EGU24-6871 | ECS | Posters on site | HS8.1.2

The advantages and considerations of applying dual tracers in SWPP tests  

Nam-Ryeong Lee, Ji-Young Baek, and Kang-Kun Lee

The Single-Well Push-Pull (SWPP) test is a cost-effective tracer test that has been widely used for aquifer characterization. There is an advantage in concurrently utilizing heat and solute tracers for a comprehensive understanding of the hydraulic and thermal characteristics of the aquifer. However, the application of both tracers in SWPP tests has yet to be commonly used due to their particularity in setting experimental conditions such as drift time and the use of chaser. In this research, dual-tracer SWPP tests were conducted in a laboratory scale using sand (d50 = 0.84 mm, U = 2.06) under six different seepage velocities (vs = 17.5 ― 59.7 m/d), with relative drift time as the variable. As tracers, a sodium chloride solution with a concentration of 1000 ppm and a temperature difference of approximately 6℃ from the background water temperature was employed. Obtained EC and temperature time series data were analyzed by several analytical models. The estimates from analytical models (seepage velocity, porosity, volumetric heat capacity) were compared to those from measurements to evaluate the applicability of a single analytical model on dual-tracer SWPP test. Preliminary experimental results showed that slower velocities and shorter drift times resulted in higher recovery rates but also led to larger error rates in estimates for the solute tracer. Building upon a solute tracer, more accurate analytical models suitable for the current experimental setup were identified, and subsequently extended to the heat tracer for further analysis. Based on the interpretation of both tracers, appropriate test conditions for dual-tracer SWPP tests will be proposed. We anticipate to offer a deeper understanding of the benefits and considerations associated with the combined use of heat and solute tracers for the thorough evaluation of aquifer characteristics during push-pull tests.

Keywords: Single-well push-pull test, Laboratory experiments, Heat tracer, Solute tracer

Acknowledgements : This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2022R1A2C1006696). This work was also supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government(MSIT) (No. 2022R1A5A1085103). This work was also supported by the Nuclear Research and Development Program of the National Research Foundation of Korea (NRF-2021M2E1A1085200).

How to cite: Lee, N.-R., Baek, J.-Y., and Lee, K.-K.: The advantages and considerations of applying dual tracers in SWPP tests , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6871, https://doi.org/10.5194/egusphere-egu24-6871, 2024.

The effects of global warming have already been recorded in many decorated caves located in karst systems, and some prehistoric paintings are already deteriorating. Modeling the microclimate of caves under various climate change scenarios will enable to adapt the conservation strategy for rock art heritage.

The first step in this modeling approach is to simulate heat transfer from the surface to the cave through the soil/epikarst/karst system. The rock characteristics in the model are calibrated using sensor data taken at various depths in the soil and in the karst over a few years, and in the cave thanks to long-term monitoring. To provide long-term climate forcing, a transfer function is established between meteorological data measured at a height of 2 meters by Météo France and the temperature measured at the ground surface.

Then, this heat transfer model is fed with projections from regional climate downscaling models. This modeling approach, which integrates both current data and climate projections, will be a significant step towards the effective management and conservation of decorated caves, which are not only geological wonders but also hold critical historical and archaeological significance.

How to cite: Artigue, C. and Mugler, C.:  Heat transfer modeling in karst environments to study the impact of climate change on the future of decorated caves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9577, https://doi.org/10.5194/egusphere-egu24-9577, 2024.

Immiscible fluid displacement in rough geological fractures plays a crucial role in various subsurface processes, such as enhanced oil recovery and geological carbon sequestration. In horizontal settings, this displacement is governed by capillary and viscous forces, resulting in the emergence of various displacement patterns as a less viscous fluid displaces a more viscous one (drainage). The macroscopic variables quantifying the flow process differ substantially between the two limit unstable regimes, namely capillary and viscous fingering, for very low and very large capillary numbers, respectively. While there has been extensive investigation of such phenomena in the context of porous media, studies on rough fractures are relatively scarce. In this study, we perform Direct Numerical Simulation (DNS) to analyze the process of drainage by solving the Navier–Stokes equations within the fracture pore space, employing the Volume of Fluid (VOF) method to track the evolution of the fluid-fluid interface. We consider a wide range of Capillary numbers (10-5 – 10-2) encompassing both the viscous and capillary dominated regimes, as well as three distinct viscosity ratios (0.8, 0.05 and 0.01), and address realistic synthetic fracture geometries characterized by their Hurst exponent, the ratio of the roughness amplitude to the mean aperture (denoted as the fracture closure), and the correlation scale Lc (i.e., the scale above which the two fracture walls are identical) of the investigated fracture domain. The fracture closure is varied between 0.1 and 1, and Lc between L/32 (aperture field with spatial correlations only at small scales) and L (self-affine aperture field), where L denotes the length of the domain. Starting from the invasion morphologies of the fluid-fluid interface, we examine various pore-scale and macroscopic flow observables, allowing us to systematically characterize the displacement processes of the two-phase system at the hydrodynamic scale. Additionally, flow observables, such as the residual saturation of the displaced fluid and the interfacial area, can be utilized to define the parameter functions of a continuum scale two-phase flow model towards upscaling.

How to cite: Neuweiler, I., Krishna, R., Yang, Z., and Yves, M.: Direct Numerical Simulation of Immiscible Two-phase Flow in Rough Fractures from Viscous to Capillary Fingering – Impact of Flow regime and Structure of the Aperture Field , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9743, https://doi.org/10.5194/egusphere-egu24-9743, 2024.

Coupled dissolution/precipitation reactive processes in transport in porous media are ubiquitous in a multitude of contexts within the field of Earth sciences, such as geological CO2 and H2 storage, contaminant remediation and acid injection in petroleum reservoirs. In particular, the dynamic interaction between the reaction and solute transport, capable of giving rise to the phenomenon of preferential flow paths, is of a critical importance, as these paths play a dominant role in determining the transport properties of the porous medium; still, the approaches to its characterization remain disputed. The emergence of preferential flow paths in porous media can be considered a manifestation of transport self-organization, as they introduce concentration gradients that distance the system from the state of perfect mixing.

To investigate the dynamic reactive-transport interaction and its influence on transport self-organization within the porous media, we consider a 2D Darcy-scale reactive transport simulation, where dissolution and precipitation of the calcite porous matrix are driven by the injection of a low-pH water. The reactive process alters the transport properties of the porous medium, thus creating the reaction-transport interaction. The coupled reactive-transport process is simulated in a series of computational analyses employing the Lagrangian particle tracking approach, capable of capturing the subtleties of the multiscale heterogeneity phenomena. We employ the thermodynamic framework to investigate the emergence of preferential flow paths as the manifestation of transport self-organization; in particular, we are interested in the relationship between the reaction enthalpy that leads to alteration of the medium's transport properties and the resulting change in the transport self-organization.

For initially homogeneous media, our findings show an increase in transport self-organization with time, along with the emergence of the medium heterogeneity due to interaction between the transport and reactive processes. By studying the influence of the Peclet number on the coupled reactive-transport process, we observe that self-organization is more pronounced in diffusion-dominated flows, characterized by low Peclet values. The hydraulic power, dissipated by the fluid, is shown to increase with the increasing medium heterogeneity, as well as with the mean hydraulic conductivity value. This increase in power, supplied to the fluid, results in an intensification of transport self-organization.

For heterogeneous media, we find again that transport self-organization increases with the evolution of the reactive process, along with an increase in the heterogeneity of the medium; their rates of change depend on the initial heterogeneity of the porous medium. These parameters correlate well with the "useful" reactive enthalpy invested in the reactive process, suggesting the existence of a relation between the energy spent and the transport self-organization gained. The self-organization of the breakthrough times exhibits the opposite tendencies, that can be explained by means of a thermodynamic analogy.

Employing thermodynamic framework to investigate the dynamic reaction-transport interaction in porous media may prove beneficial whenever the need exists to estimate the alteration of the overall transport properties of the medium due to emergence of preferential flow paths due to reactive-transport interaction.

How to cite: Shavelzon, E. and Edery, Y.: Applying Thermodynamic Framework to Analyze Transport Self-Organization Due to Dissolution/Precipitation Reaction in Porous Medium: Entropy, Enthalpy, Heterogeneity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10003, https://doi.org/10.5194/egusphere-egu24-10003, 2024.

EGU24-10397 | ECS | Posters on site | HS8.1.2

Impact of Sharp Interfaces on Biofilm Growth: Insights from Mixing Processes in a Flow-Through Column Experiment. 

Michela Trabucchi, Paula Rodriguez Escales, Xavier Sanchez Vila, Jesus Carrera, and Daniel Fernandez Garcia

Biofilms in porous media host microbial communities that play a central role in the degradation of nutrients and Contaminants of Emerging Concern. Their importance for promoting contaminants removal in the context of Natural Based Solutions is acknowledged, but we still lack a complete understanding and quantification of biofilm growth dynamics in porous media, and their impact on flow and transport behavior.

In this context, we aim to investigate the effects of sharp interfaces on the spatial and temporal distribution of biofilms growth and their subsequent role in the evolution of flow and transport properties. For this purpose, we conduct flow-through experiments in sand-packed columns characterized by two homogeneous porous media separated by a sharp interface. We inject electron acceptor and electron donor solutions sequentially and multiple times. This creates multiple reactive mixing zones that flow and evolve through the system, depending on the porous medium. The high-resolution monitoring system enables the quantification of biofilm activity, as well as changes in hydraulic conductivity over time and at different sections of the column. Additionally, image analysis allows for the evaluation of the spatial distribution of biofilm growth over time, while breakthrough curve concentrations derived from several tracer tests provide further insights into overall transport parameter changes.

How to cite: Trabucchi, M., Rodriguez Escales, P., Sanchez Vila, X., Carrera, J., and Fernandez Garcia, D.: Impact of Sharp Interfaces on Biofilm Growth: Insights from Mixing Processes in a Flow-Through Column Experiment., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10397, https://doi.org/10.5194/egusphere-egu24-10397, 2024.

EGU24-10971 | Orals | HS8.1.2

Dispersion in heterogeneous networks under linear and non-linear flow conditions 

Marco Dentz, Jannes Kordilla, and Juan Hidalgo

The understanding and prediction of dispersion phenomena in natural and engineered media are key issues in different fields of science and engineering, with applications ranging from groundwater management to geological energy storage. Spatial variability in the physical medium properties and flow conditions leads to scale effects in the flow and dispersion processes. Here we study the mechanisms of dispersion in two- and three-dimensional heterogeneous networks under linear and non-linear flow conditions, that is, for flows in which the flow rate is a non-linear function of the pressure gradient. Such non-linear relationships have been found for the flow of non-Newtonian fluids, for multiphase flow and inertial flows in porous, fractured and karstic media. We study transport under steady flow using a Lagrangian approach. The flow fields are characterized statistically in terms of the distribution of Eulerian and Lagrangian flow velocities and their correlation properties. Longitudinal dispersion is measured in terms of particle breakthrough curves. We observe broad distributions of particle arrival times, which are manifestations of memory processes that occur due to broadly distributed flow velocities and mass transfer rates. These behaviors are analyzed in terms of the Eulerian and Lagrangian flow statistics, medium structure and flow conditions. Based on this analysis, we propose a stochastic time domain random walk approach to quantify the impact of the network heterogeneity and flow conditions on large-scale dispersion.     

How to cite: Dentz, M., Kordilla, J., and Hidalgo, J.: Dispersion in heterogeneous networks under linear and non-linear flow conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10971, https://doi.org/10.5194/egusphere-egu24-10971, 2024.

EGU24-12432 | Posters on site | HS8.1.2

Intrinsic permeability of porous systems: models and microfludiic experiments for heterogeneous structures 

Wenqiao Jiao, David Scheidweiler, Nolwenn Delouche, Alberto Guadagnini, and Pietro de Anna

Understanding the relationship between flow (Q) and pressure drop (ΔP) for porous media is a long-standing challenge affecting a wide variety of environmental, societal and industrial issues, from soil remediation to enhanced oil recovery. While for homogeneous media such dependence is well represented by the Kozeny-Carman formula,  the fundamental nature of such a relationship (Q vs ΔP) within heterogeneous systems, characterized by a broad range of pore sizes, is still not understood. We design a set of controlled and complex porous structures that we use to conduct microfluidics experiments to measure their intrinsic permeability. We synthesize the results upon deriving an analytical formulation relating the overall intrinsic permeability and key features of the porous structure. We propose to embed the spatial variability of pore sizes into the medium permeability by upscaling the flow through each pore, via the Hagen Poiseuille Law. Our prediction fits well the collected data, highlighting the role played by the micro-structure on the overall medium permeability. Furthermore, beside the theoretical understanding of this important relationship, we also extend our set-up to novel experiments focusing on the paradigmatic case study of biofilm growth that affects the system permeability by obstructing the pore spaces.

How to cite: Jiao, W., Scheidweiler, D., Delouche, N., Guadagnini, A., and de Anna, P.: Intrinsic permeability of porous systems: models and microfludiic experiments for heterogeneous structures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12432, https://doi.org/10.5194/egusphere-egu24-12432, 2024.

In this study, a study on groundwater flow analysis was conducted using hydrochemical and thermal data to find out the flow of groundwater and pollutant behavior in the karst area and to secure countermeasures for problems related to water quality and water resource stability. The flow characteristics were identified using the study area's overall topographic slope and groundwater map. It is more vulnerable to groundwater pollution because it belongs to the discharge stand where groundwater from the west is discharged into the sea. The vertical hydraulic gradient was measured to confirm the direction of recharge and discharge of groundwater and surface water, and it can be seen that the inflow and outflow of groundwater-surface water is active. In both Gyogokcheon (Gyogok-ri) and Sohancheon (Hamaengbang-ri), the recharge of groundwater tends to be more dominant, and in the case of Sohancheon located in Hamangbang-ri, the recharge of groundwater in summer and winter was more active than in spring and fall. In addition, the residence time of groundwater and the recharge and mixing of surface water according to the flow of groundwater and the behavior of pollutants were analyzed using hydrochemical data. There was a distinct difference in radon concentration values between Gyogokcheon (gneiss-based rock) and Sohancheon (limestone-based rock). In the case of Hamaengbang-ri, radon concentration values were not significantly divided according to surface water, groundwater-surface water mixing section (hyporheic zone), and cave water. In the case of Gyogok-ri, radon concentration was used as one of the indicators to estimate the mixing ratio of groundwater and surface water in the hyporheic zone. This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (grant numbers 2019R1I1A2A01057002 and 2019R1A6A1A03033167). This subject is supported by Korea Ministry of Environment as "The SS(Surface Soil conservation and management) projects; 2019002820004.

How to cite: Ryu, H.-S. and Kim, H.: A Study on the analysis of groundwater flow using thermal and hydrochemical data of groundwater and surface water in the karst area of Samcheok, Korea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14397, https://doi.org/10.5194/egusphere-egu24-14397, 2024.

EGU24-14733 | ECS | Posters on site | HS8.1.2

Tracing colloidal co-transport in porous media with tailor-made polymers 

Nimo Kwarkye, Thomas Ritschel, and Kai Totsche

The soil aqueous phase contains a multitude of dissolved as well as colloidal substances, e.g., organic colloids and clay minerals. Due to their ability to facilitate co-transport, colloids significantly contribute to the fluxes of carbon, nutrients, and contaminants, which renders a thorough consideration of colloids and their mobility a prerequisite for an understanding of soil matter exchange. However, a comprehensive assessment of colloidal transport is often hampered by the heterogeneity of reactions at soil mineral interfaces and the compositional and functional diversity of organic matter in natural soil suspensions. We addressed this challenge by using tailored organic polymers based on poly(ethylene glycol) (PEG) with high reactivity towards clay minerals. Hence, the polymers may be immobilized when clays are exposed on pore walls or mobilized when clay minerals form a colloidal suspension that permits a co-transport of clays and polymers. To unravel the competition between these mechanisms, we investigated the separate and combined transport of PEG and bentonite in column experiments using natural limestone as substrate. Here, PEG was strongly retarded due to adsorption on clay mineral surfaces that were exposed following limestone weathering. In contrast, PEG was highly mobile when transported simultaneously with bentonite and the observed PEG breakthrough resembled that of bentonite, indicating PEG was co-transported. This demonstrates that the application of PEG is promising in the disentanglement of complex transport phenomena in natural porous media, particularly if competition between adsorption sites is decisive for the fate of organic matter.

How to cite: Kwarkye, N., Ritschel, T., and Totsche, K.: Tracing colloidal co-transport in porous media with tailor-made polymers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14733, https://doi.org/10.5194/egusphere-egu24-14733, 2024.

EGU24-14769 | ECS | Posters on site | HS8.1.2

Prediction of As behavior in a vadose zone using an empirical relationship between As retardation factor and the soil properties 

Sang Hyun Kim, Tho Huynh Huu Tran, Jaeshik Chung, and Seunghak Lee

Arsenic (As) pollution in soil from various anthropogenic sources potentially threatens groundwater by migrating downward through a vadose zone. As goes through complex biogeochemical reactions such as sorption, desorption, and/or redox transformation, which affects its retention in this zone. A retardation factor is a critical solute-transport parameter to quantitatively assess the retention of As in this zone, and eventually to predict the potential risk of groundwater contamination. Despite its importance, however, there is still limited information to quantify the retardation factor in a vadose zone, compared to in the saturated condition. This study aimed to assess the retardation factor of As using twenty-two unsaturated soil columns coupled with the non-equilibrium solute-transport modeling. We employed a multiple linear regression approach to develop a prediction model for the retardation factor based on the soil properties. Soil columns with 3-cm inner diameter and 45-cm height were packed with six different field soils at various bulk densities. Distilled water was infiltrated into each column at a constant flowrate, until a steady-state unsaturated condition was achieved. The distilled water was replaced with a solution containing As and a conservative tracer (chloride, Cl), to obtain their breakthrough curves. The retardation factor of As was determined by inversely fitting the breakthrough data of As and Cl with Mobile-Immobile model integrated in HYDRUS 1-D software. The derived retardation factors of As in the mobile and immobile zones ranged 1.58–6.93 and 1.44–25.48, respectively. These showed high degree of dependence on soil properties. In the mobile water zone, iron content and organic matter content emerged as the two most influential properties affecting As transport, impeding As mobility. Conversely, in the immobile water zone, coefficient of uniformity and bulk density were identified as the most influential factors, enhancing As retention. Based on the results, empirical equations were derived to predict the retardation factors of As in a vadose zone based on the aforementioned soil properties.

How to cite: Kim, S. H., Tran, T. H. H., Chung, J., and Lee, S.: Prediction of As behavior in a vadose zone using an empirical relationship between As retardation factor and the soil properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14769, https://doi.org/10.5194/egusphere-egu24-14769, 2024.

EGU24-17262 | ECS | Posters on site | HS8.1.2

Effect of velocity fluctuations on pore scale stretching kinematics in 3D porous media 

Manuel Maeritz, Joris Heyman, Tanguy Le Borgne, and Marco Dentz

Fluid stretching plays an important role in controlling mixing dynamics in porous media. Recent advances have shown that stretching at pore scale in 3D porous media is chaotic, leading to exponential elongation of mixing interfaces [e.g. 1,2]. Yet, it is not known how the associated stretching rate depend on the pore scale velocity heterogeneity. In this study, we perform particle tracking simulations in a periodic flow fields to investigate how flow heterogeneity control the transient evolution of the stretching rate as well as the asymptotic stretching rate (Lyapunov exponent). Our results reveal that rare low velocity events have a significant impact on the Lyapunov exponent, while these regions are numerically more difficult to treat and thus sometimes excluded from statistics [1]. Moreover, we discuss conceptual difficulties associated to velocity pdf with heavy tails towards low velocities: Ensemble averages of the deformation gradient tensor do not converge under these conditions when taken them at equal advective distances, as opposed to at equal times. As a consequence, the meaning of the steady state stretching rate must be discussed in the context of long memories. Using Continuous Time Random Walks (CTRW) we derive analytical expressions for the averages and discuss low velocity cutoffs to guarantee convergence. We further discuss the nature of the pre-asymptotic stretching kinematics, which can have a dominant effect on mixing processes. We show that the strength of the transient is controlled by the typical shear rate while the duration is determined by the Lyapunov exponent. Weaker chaotic stretching are associated to a longer lasting transient regime.

[1]: Turuban et al. (2019) In: JFM 
[2]: Heyman et al. (2020) In: PNAS

How to cite: Maeritz, M., Heyman, J., Le Borgne, T., and Dentz, M.: Effect of velocity fluctuations on pore scale stretching kinematics in 3D porous media, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17262, https://doi.org/10.5194/egusphere-egu24-17262, 2024.

EGU24-18015 | ECS | Orals | HS8.1.2

Linking biogeochemical potential to depositional processes 

Vitor Cantarella, Adrian Mellage, and Olaf Cirpka

Biogeochemical reactions are microbially mediated chemical reactions that occur naturally in the subsurface, involving naturally occurring and anthropogenically enriched reactants as well as microbes. These reactions play a crucial role in determining the fate of reactive solutes in groundwater. In Quaternary aquifers, the depositional (sedimentological) processes modulate the composition of the sedimentary matrix, leading to strong spatial variability in both hydraulic and reactive properties. For example, the presence or absence of reduced minerals or organic matter in the sediment matrix determines its “reactivity” with respect to oxidized reactants, auch as dissolved oxygen and nitrate. Additionally, the depositional processes determine properties relevant to groundwater flow, notably the hydraulic conductivity. In this work, we attempt to link depositional processes and the physico-chemical makeup of sediment matrices with the ability of an aquifer to naturally attenuate electron acceptors. We focus on nitrate and denitrification as dissolved electron acceptor and associated biodegradation pathway, respectively. Traditional numerical modeling approaches that account for physical heterogeneity in reactive transport rely on geostatistical methods using, e.g., multi-Gaussian random fields, and often fall short in capturing the link to the geological generating processes. We propose the use of object-based modeling to realistically represent the subsurface's physical characteristics and bridge the gap between geology and biogeochemical potential. Object-based models depict various sedimentary features as 3-D geometries (geo-bodies) within a hierarchical framework. On the largest spatial scale, the model represents strata, corresponding to the sedimentary deposition setting. Within each stratum, facies elements (with internal structure such as crossbedding or layering) representing architectural elements, such as channels or scour-pool fills, are assigned. We illustrate the construction of an object-based aquifer scale groundwater flow model informed via sedimentological descriptions (core logs), integrating field and lab-derived information. Furthermore, we apply a travel-time based reactive transport modelling approach to quantify the effect of the realistic distribution of reactive sedimentary faces on the extent of denitrification. We expect our ongoing analysis to shed light on the quantitative link between the sedimentological architecture of an aquifer and its denitrification potential.

How to cite: Cantarella, V., Mellage, A., and Cirpka, O.: Linking biogeochemical potential to depositional processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18015, https://doi.org/10.5194/egusphere-egu24-18015, 2024.

SSS6 – Soil Physics

EGU24-833 | ECS | Posters on site | HS8.3.2

Quantification of Temporal Variability of Soil Hydraulic Properties in an Agricultural Plot  

Saurabh Kumar, Ajit Kumar Srivastava, and Richa Ojha

An improved understanding of temporal variability of soil hydraulic properties (SHPs) can lead to better prediction of soil water dynamics in agricultural fields. This study aims to quantify the temporal variations and trends in SHPs of an experimental agricultural plot in IIT Kanpur during rice and wheat crop seasons. Statistical analysis is performed to investigate the effects of crop-cover, sampling time and depth on temporal variability of SHPs. The soil samples were collected in 6 plots at depths of 10 cm, 25 cm, and 50 cm for the period 2022-23. The samples were analysed for variations in organic carbon content, bulk density (ρb), saturated hydraulic conductivity (Ksat) , saturated moisture content (θs), and soil water characteristic curve. The results show significant temporal variations in ρb and θs. The lowest temporal variation in observed in organic carbon content. The temporal trends in SHPs for both rice and wheat crops offer valuable insights into the dynamic nature of soil behaviour during crop cultivation. The findings of this study will contribute to better understanding of soil-water relationships, aiding farmers in optimizing irrigation practices and promoting sustainable agricultural management for improved crop productivity.

How to cite: Kumar, S., Srivastava, A. K., and Ojha, R.: Quantification of Temporal Variability of Soil Hydraulic Properties in an Agricultural Plot , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-833, https://doi.org/10.5194/egusphere-egu24-833, 2024.

EGU24-1708 | ECS | Orals | HS8.3.2

A Wetting-Front Model for Vadose Zone Infiltration via Drywells 

Ziv Moreno, Amir Paster, and Tamir Kamai

Drywell infiltration is a common approach to recharge groundwater and reduce load from drainage systems. Due to rapid acceleration in urban developments, as well as climate change that predicts an increase in frequencies and magnitude of extreme precipitation events in the Mediterranean area, it is critical to predict the drywell infiltration capacity, i.e., its response to anticipated precipitation events. The infiltration capacity of a drywell is mainly determined by the geometrical parameters, i.e., diameter and depth, and the soil hydraulic parameters, i.e., hydraulic conductivity, porosity, and water retention. Predictions of drywell infiltration capacity are commonly conducted using models that solve the unsaturated flow in the subsurface using complex and costly numerical schemes. This work proposes a different approach based on a semi-analytical model that relies on a sharp interface wetting front assumption. The proposed model can predict the water levels in the well and the subsurface wetting front location during and after an infiltration event. The semi-analytical model was tested and compared with numerical simulations of Richards' equation and with data from a field experiment and proved to be sufficiently accurate. The typical run times of the semi-analytical model are smaller than 1 second and about three orders of magnitude shorter than the numerical model of Richards' equation. The field data was further utilized to calibrate the soil hydraulic properties by matching the semi-analytical model's outcomes to the measured water levels in the well. A sensitivity analysis of the drywell response to variable hydraulic properties, climatic scenarios, and well configurations (depth and diameter) was conducted, demonstrating some practical applications for analysis, which may be used for adequately determining site-specific drywell design.

How to cite: Moreno, Z., Paster, A., and Kamai, T.: A Wetting-Front Model for Vadose Zone Infiltration via Drywells, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1708, https://doi.org/10.5194/egusphere-egu24-1708, 2024.

Deep-rooted vegetation transpires a considerable amount of deep soil water with different ages in the unsaturated zone. However, the tradeoffs between new water of transpiration (temporally originating from post-planting precipitation) and old water of transpiration (temporally originating from pre-planting precipitation) across the vegetation lifespan are poorly understood. In this study, we collected soil samples from beyond 28 m soil depth on the Loess Plateau of China to investigate the influence of deep-rooted vegetation on the age of soil water and analyze the proportion of new and old water of transpiration in the unsaturated zone under grassland, 22-year-old apple orchard, and 17-year-old peach orchard. Water isotopes (2H, 18O, and 3H), solutes (chloride, nitrate, sulfate), and soil water content were used to identify the critical water ages in the unsaturated zone (one-year water age, water age corresponding to stand age, and the maximum water age of transpiration), and to determine soil water deficit, soil evaporation loss fraction, and potential groundwater recharge. The results showed that soil water mainly moved as piston flow in these soil profiles, and deep soil water largely came from heavy precipitation. Deep-rooted vegetation restrained new pore water velocity and potential groundwater recharge. New pore water velocity declined from 0.40 m yr-1 to 0.14 m yr-1 and 0.34 m yr-1 for apple and peach, respectively. Deep-rooted vegetation decreased groundwater recharge by 9.46 % for apple and 7.04 % for peach, compared to grassland. Over the vegetation lifespan, annual average transpiration was 500.56 mm yr-1 and 468.89 mm yr-1 with maximum water age of 63 years and 45 years for apple and peach, respectively. The transpiration of deep-rooted vegetation mainly used new water (94.97 % for apple and 97.47 % for peach). The total old water of transpiration was 553 mm for apple and 209 mm for peach. Our results identify the temporal sources of vegetation water use, offering new insights into the transpiration process of deep-rooted vegetation.

How to cite: Li, M. and Chen, G.: Quantitative partitioning of temporal origin of transpiration into pre- and post-plantation under deep-rooted vegetation on the Loess Plateau of China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2584, https://doi.org/10.5194/egusphere-egu24-2584, 2024.

EGU24-2639 | Posters on site | HS8.3.2

Water vapor adsorption and flow dynamics in dry desert soils 

Dilia Kool and Nurit Agam

Water vapor adsorption is the least studied form of non-rainfall water inputs but is likely the most common one in arid and hyper-arid areas. It is determined by the magnitude of the downward gradient in water vapor pressure between the atmosphere and the soil; the surface area of the adsorbing soil; and the penetration depth of water vapor adsorption. Water vapor adsorption was measured using micro-lysimeters and profiles of relative humidity (RH) sensors in both loess and sand in the Negev desert, Israel, over the summers of 2021 and 2022. The RH sensor array allowed measurement of detailed changes in water content in the soil profile and provided an unprecedented insight into processes governing water vapor adsorption dynamics under arid conditions in-situ. The RH sensors significantly underestimated total water vapor adsorption, indicating that a finer array is needed to capture the full process. However, even with the current array, extremely small changes in water content were captured. With these measurements we explored the three main factors contributing to water vapor adsorption. The onset of a downward vapor pressure gradient coincided with the arrival of the sea breeze, indicating that the sea breeze is the primary source for water vapor adsorption in the uppermost soil layer. Water vapor adsorption was higher in loess than in sand, due to its finer texture and larger surface area. The most important finding of this research is that the dominant mechanism for water vapor flow under natural arid conditions (relative humidity in the soil (RHs) <100%) is different than under the generally assumed RHs = 100% conditions. Under natural arid conditions, temperature affects water vapor flow through advection rather than through diffusion. This means water vapor moves from lower to higher, rather than from higher to lower, temperatures. The fact that advection is a much faster process compared to diffusion potentially explains the rather deep penetration of water vapor adsorption observed in deserts.

How to cite: Kool, D. and Agam, N.: Water vapor adsorption and flow dynamics in dry desert soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2639, https://doi.org/10.5194/egusphere-egu24-2639, 2024.

Recent models of the unsaturated hydraulic conductivity curve (UHCC) are the sum of separate UHCCs for domains of capillary water, film water, and water vapor. A new theoretical framework for aggregating domain conductivities to a bulk soil UHCC reveals that this requires parallel domains. The same theory also generates arithmetic, harmonic, and geometric averages of the liquid-water conductivities, which can be arithmetically averaged with the vapor conductivity. However, current models for capillary and film conductivities are intrinsic, i.e., valid within their respective domain. The vapor conductivity is a bulk conductivity, i.e., it gives the conductivity of the gaseous domain as it manifests itself in the soil. Conversion relationships use the domain volume fractions as approximations of the as-yet unknown weighting factors to convert between intrinsic and bulk conductivities. This facilitates consistent averaging of domain conductivities. The fitted curves for the capillary and film water depend on the averaging (or adding) method. Hence, they are not strictly characteristic of their respective domains. Truly intrinsic domain conductivity functions may not exist, or are perhaps merely tools to arrive at a good fit of the UHCC of the bulk soil. Given these complications, a simpler junction model that joins a capillary and a film limb at a junction point offers an attractive alternative. 

How to cite: de Rooij, G. H.: The unsaturated soil hydraulic conductivity as a sum, an average, or a junction of domain conductivities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2947, https://doi.org/10.5194/egusphere-egu24-2947, 2024.

EGU24-3493 | ECS | Orals | HS8.3.2

Investigating the feasibility of Bioengineering and Hydropedological techniques in controlling shallow water table problem in urban areas 

Shahad Al-Yaqoubi, Ali Al-Maktoumi, Anvar Kacimov, Osman Abdalla, and Said Al-Ismaily

The continuous and frequent occurrence of the Shallow Water Table (SWT) in urban regions aggravates the severity of geotechnical and environmental problems. Exploring possible measures that effectively reduce the negative impact of SWT in urban aquifers is of extreme importance. This research investigated the effectiveness of bioengineering techniques in lowering SWT in the framework of hydropedological factors (soil structure in the vadose zone, where most pore water fluxes take place). The methodology includes physical models (sand tank experiments) and field-scale studies. A total of nine sand tanks were utilized, segmented into three distinct groups, to investigate the reduction of the water table through different mechanisms: (1) evapotranspiration drawdown by soil water uptake by the roots of vegetation (specifically Reeds), (2) evaporation by bare homogeneous topsoil, and (3) evaporative “soil siphoning” in tanks that were made as “smart composites” with a fine-textured vertical “moisture chimney”. The dynamics of SWT were monitored over 6 months (March–September 2023). Each tank measures 100 cm in length, 70 cm in height, and 15 cm in width. All tanks were packed with two horizontal soil layers (sand and clay) to simulate a perched aquifer, common prototypes of which were explored in Muscat, Oman. In the siphoning experiment, a small trench was made and packed with silt loam soil. This trench extended the entire thickness of the aquifer to enhance capillarity and, hence, evaporation. Analysis of the results showed that the drawdown of the water table ranged from 75% to 300% (winter to summer seasons) in the tanks containing plants (Reeds) compared with the control tanks. In addition, the SWT in the tanks with “soil siphons” was reduced in the range of 22%-46% compared with the control tanks. Another experiment with Reeds was conducted on a larger field scale using Concrete Agricultural Basins (CABs) with dimensions of 1000 cm length, 200 cm width, and 60 cm depth. The experiment spanned three months (June-September 2023) and aimed to investigate the impact of Reeds on SWT levels in larger-scale 3D pore water dynamics (in sand tank experiments flows were 2D). Overall, the large-scale experiment showed that over the three months, the evapotranspiration from Reeds reduced the water level by 16.7%, 66.7%, and 116.7% more than evaporation from bare soil during the first, second, and third months, respectively.

This investigation highlights the significant influence of bioengineering through phreatophytic Reeds, seasonal variations of weather conditions, and the hydropedology of the root zone on checking the SWT levels. The influence of fine-textured soil lenses, strata, and engineered soil siphons in controlling water levels was studied. While the presence of Reeds plays a crucial role in influencing water levels, seasonal fluctuations, usually modeled by ET0-ETc, also contribute, with drastic differences between summer and winter. The investigated drainage techniques are ecologically and environmentally benign: no electricity or fuel is used for the reduction of waterlogging because only soil capillarity and solar energy maintain the processes of evaporation and transpiration; the Reeds’ biomass, accumulated during the ecoengineering process, additionally intercepts and sequesters CO2.

How to cite: Al-Yaqoubi, S., Al-Maktoumi, A., Kacimov, A., Abdalla, O., and Al-Ismaily, S.: Investigating the feasibility of Bioengineering and Hydropedological techniques in controlling shallow water table problem in urban areas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3493, https://doi.org/10.5194/egusphere-egu24-3493, 2024.

The SWAP model employs a finite difference numerical solution of the Richards equation, including root water uptake, to simulate the movement and predict the state of soil water and associated quantities in the vadose zone. The relation between hydraulic conductivity K, pressure head h, and water content θ can be described by parameters of the Van Genuchten-Mualem (VGM) relations, where the quality of these parameters determines the quality of the model output. We developed a stochastic procedure to evaluate the outputs of the SWAP model according to the uncertainty and correlations in the VGM parameters. Specific software was developed to (1) fit VGM parameters to observed retention and conductivity data to obtain values, standard errors, and correlations of transformed parameters (software HPFit); (2) generate p stochastic realizations of the VGM parameters using Cholesky decomposition (software StochHyProp), and (3) run the SWAP model with each of the p parameter realizations for specific scenarios, extracting simulation results (software RunSWAP), e.g., the simulated water balance components evaporation, transpiration, bottom flux, and runoff. The results from the last step yield the respective frequency distributions of the output values. Examples will show that the most commonly performed prediction using the average VGM parameter values does not always agree with the median of the stochastic realizations. The developed procedure allows the quantitative analysis of the uncertainty of SWAP model output, adding to the interpretation of the predictive power of hydrological models like SWAP.

How to cite: de Jong van Lier, Q.: Using the SWAP model for the stochastic analysis of hydraulic parameter uncertainty propagation in soil water balance components, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3939, https://doi.org/10.5194/egusphere-egu24-3939, 2024.

Films, rivulets, snapping rivulets, sliding drops, slugs—many flow modes besides filled-tube, Poiseuille-type flow occur in macropores. Some of these fit reasonably into Darcian formulations and the analog of laminar viscous flow in water-filled tubes. But others do not. These exceptions may be the main reason for failures to predict the speed and travel distance of preferential flow.

A useful first step for an improved model of macropore flow is the classification of diverse flow modes into categories based on their intrapore boundary conditions. Within a flowing macropore, the gas-liquid and liquid-solid interfaces, with the effects of interfacial constraints such as surface tension and contact angles, determine the geometry of the flowing liquid phase and its controlling frictional influences. A classification scheme with four categories can account for the various flow modes that have been observed in lab and field experiments. This categorization helps to distinguish which flow modes are amenable to Darcian or Poiseuille-type representation and which are not. Some of the exceptions are approachable with wave or film-flow concepts as in several recently-developed models. Yet there are other flow modes that do not fit well in any of these models, and in some cases these may be the most important means of rapid and long-distance transport. Other sorts of physical processes may provide suitable analogs for these, for example free-fall concepts like initial acceleration, speed-dependent frictional forces, and terminal velocity. In any case, the diversity of macropore flow modes needs to be considered in the development of markedly improved models of preferential flow.

How to cite: Nimmo, J. R.: Diverse modes of macropore flow—How to include them in predictive models?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4130, https://doi.org/10.5194/egusphere-egu24-4130, 2024.

Understanding the change of soil hydraulic conductivity with temperature is a key to predicting the groundwater flow and solute transport in permafrost and seasonally frozen area. The most commonly used models for hydraulic conductivity during freeze-thaw cycles only consider the flow of capillary water in the soil and neglect water flowing along thin films around the particle surface. This paper proposed a new hydraulic conductivity model of frozen soil via Clausius-Clapeyron equation based on an unsaturated soil hydraulic conductivity model over the entire moisture range using analogy between freeze-thaw and dry-wet process in soils. The new model used a simple single equation to describe the conductivity behaviors resulting from both capillary and adsorption forces, thus accounting for effect of both capillary water and thin liquid film around soil. By comparing with other existing models, the results demonstrated that the new model is applicable to various types of soils and the predicted hydraulic conductivity is in the highest agreement with the observed data. Finally, our new model was validated with a thermal-hydrological benchmark problem and a laboratory experiment result, and the benchmark results indicated that the advective heat transfer was more significant and the phase change completed earlier when considering both capillary and adsorption forces than that only considering capillary forces. Further, the coupled flow-heat model with the FXW-frozen-M2 replicate well the results from a laboratory column experiment.

How to cite: Qiao, S.: A New Model for Predicting Hydraulic Conductivity of Soil during Freeze-thaw Processes that Accounts for Both Capillary and Adsorption Forces, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4578, https://doi.org/10.5194/egusphere-egu24-4578, 2024.

EGU24-5914 | ECS | Posters on site | HS8.3.2

A Stochastic Approach to Quantifying Uncertainty in Soil Organic Carbon 

Leonardo Inforsato, Pablo Rosso, Ahsan Raza, Magdalena Main-Knorn, and Claas Nendel

Soil organic carbon (SOC) is a key driver of soil hydraulic properties like, field capacity and wilting point, necessary for in-field scale yield prediction using tipping bucket models. However, the labor-intensive nature of obtaining spatially distributed SOC often leads to its extrapolation using satellite imagery, resulting in significant inaccuracies in SOC prediction. In this study, we propose a Monte Carlo-based (MC) procedure to quantify the propagation of SOC error to simulated yield estimates. This procedure stochastically generates data, considering both uncorrelated and correlated data. For uncorrelated data, each SOC value is generated following an independent normal distribution. For correlated data, covariances are considered, accounting for the spatial correlation of in-field SOC variability. The autocorrelation between each pair of pixels is calculated, building a correlation matrix, which is submitted to the Cholesky decomposition, resulting in a lower triangular matrix. This matrix is then used to generate correlated SOC values for each pixel, maintaining the shape of the SOC clusters while varying the SOC value in each pixel according to its error. We validated our methodology using synthetic data, then used the methodology to assist error propagation of SOC with true data in a field located in Booßen, Germany. We generated 5000 SOC images, each with approximately 6000 pixels, and simulated the yield for each pixel. The results were analyzed by the field as a whole and each pixel across different images, by generating probability distributions for both. Another comparison was made by direct measurement between measured and simulated yields. Our results confirm the consistency of our method. In the specific scenario analyzed, preliminary results show that the SOC uncertainty was sufficient to explain the entire difference between the true and estimated crop yield, highlighting the importance of accurately assessing SOC uncertainty in yield prediction models.

How to cite: Inforsato, L., Rosso, P., Raza, A., Main-Knorn, M., and Nendel, C.: A Stochastic Approach to Quantifying Uncertainty in Soil Organic Carbon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5914, https://doi.org/10.5194/egusphere-egu24-5914, 2024.

EGU24-6420 | ECS | Posters virtual | HS8.3.2

Direct measurement and indirect estimation of unsaturated soil hydraulic properties in Tunisian soils. 

Asma Hmaied and Claude Hammecker

Abstract

The hydrological cycle is strongly affected by climate changes causing extreme weather events with long drought periods and intense rainfall events. To predict the hydrological functioning of Tunisians catchments, modelling is an essential tool to estimate the consequences on water resources and to test the sustainability of the different land uses. Soil physical properties describing water flow, are therefore essential to feed the models and need to be determined all over the watershed.

In order to complete this task, lightweight, cost effective but robust methods are needed. In the present study, both physically based and empirical models or pedo-transfer functions (PTF) have been used to estimate unsaturated soil hydraulic properties based on particles size distribution (PSD), and straightforward in-situ infiltration experiments.

The specific Pedo-Transfer Functions (PTFs) embedded within the Rosetta model, the physically grounded Arya-Paris model, and the Beerkan Estimation of Soil Transfer parameters (BEST) have been specifically developed to gauge soil hydraulic parameters based on soil texture, bulk density, and, eventually, outcomes from single-ring infiltration experiments. These models were applied to a diverse array of soil types from both Northern and Central Tunisia, with a subsequent comparative analysis aimed at evaluating their potential applicability and individual performances.

Consequently, the estimated parameters derived from these models were incorporated into Hydrus to compute water flow in the vadose zone under the actual weather conditions prevailing in Tunisia. The resultant effects on the calculated water balance, encompassing infiltration, drainage, and runoff, were systematically compared for a comprehensive understanding of their implications.

Results show that soil hydraulic parameters determined with different techniques are significantly different. The results for simulated water balance over 3 years, show also differences especially for intense rainfall events. It seems that the BEST method is a valuable technique for estimating soil hydraulic parameters, offering a cost-effective and practical alternative to traditional methods, especially as it leverages on experimental infiltration data.

 

How to cite: Hmaied, A. and Hammecker, C.: Direct measurement and indirect estimation of unsaturated soil hydraulic properties in Tunisian soils., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6420, https://doi.org/10.5194/egusphere-egu24-6420, 2024.

EGU24-6425 | ECS | Orals | HS8.3.2

Does model complexity of a pedotransfer function for soil hydraulic properties hamper its transferability? 

Julian Schoch, Madlene Nussbaum, Lorenz Walthert, Andrea Carminati, and Peter Lehmann

Land surface models need information on soil hydraulic properties (SHP) that are often estimated using pedotransfer functions (PTFs). Due to a lack of calibration data, PTFs must be applied that were trained for regions and land use types outside the region of interest. In this study, we quantify the transferability of PTFs to new regions as function of mathematical complexity and number of covariates. For that purpose, we trained new PTFs for forest soils based on a dataset of 25 soil profiles from climatically moderate regions of Switzerland. In a second step, we tested the new and some existing PTFs in a drier and hotter Swiss region (Valais). Tests of transferability showed that increasing the mathematical complexity (from a linear model to a highly non-linear random forest model) was always beneficial for the predictive power in new regions. Increasing the number of covariates revealed a trade-off between improving the accuracy of the predicted soil water retention curve and reducing accuracy of the soil hydraulic conductivity. Interestingly, the use of environmental predictors (climate data) hampers transferability the most due to large climatic contrasts between the calibration and validation regions. These results suggest that transferability works better for PTFs using fewer predictors. We recommend the use of non-linear PTFs based on soil texture, soil density, and organic carbon content for optimal prediction accuracy in regions without training data. This work highlights that the models with the highest number of predictors are not optimal for achieving transferability and that reducing the number of predictors can be beneficial.

How to cite: Schoch, J., Nussbaum, M., Walthert, L., Carminati, A., and Lehmann, P.: Does model complexity of a pedotransfer function for soil hydraulic properties hamper its transferability?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6425, https://doi.org/10.5194/egusphere-egu24-6425, 2024.

EGU24-6734 | Posters on site | HS8.3.2

Soil structure determined from interrelationships in hydraulic, thermal and electrical properties 

Josh Heitman, Yongwei Fu, and Robert Horton

The presentation will focus on the interrelationships of soil hydraulic, thermal and electrical transport properties. We will highlight how some more easily measured transport properties can be used as surrogates for others, which cannot be readily measured. We will specifically illustrate how the thermo-TDR sensing platform can be used to collect detailed in situ thermal and electrical property measurements at millimeter to profile scale. We will utilize the interrelationships between hydraulic, thermal and electrical properties together with thermo-TDR measurements in order to demonstrate how soil density and structure can be determined in situ. We will also highlight opportunities for extending such approaches to other sensing platforms at other scales.

How to cite: Heitman, J., Fu, Y., and Horton, R.: Soil structure determined from interrelationships in hydraulic, thermal and electrical properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6734, https://doi.org/10.5194/egusphere-egu24-6734, 2024.

EGU24-7481 | ECS | Posters on site | HS8.3.2

Concept to quantify the effects of SOM on water retention hysteresis and hydrophobicity in sandy soils and their implication for soil water modeling 

Daniel Schwarze, Johanna Metzger, Mathias Spieckermann, Joscha Becker, Yva Herion, Marc-Oliver Göbel, Jörg Bachmann, and Annette Eschenbach

Global warming is promoting extreme weather conditions like more frequent heavy rainfall events and longer periods of drought in central Europe. This can lead to an increase in hydrophobicity and hysteretic behavior of soils, potentially reducing its water retention capabilities and changing the soil water balance. These soil characteristics are also highly dependent on the amount and properties of soil organic matter (SOM). Climate change effects are expected to be particularly pronounced in sandy soils, which have comparatively low water retention capacities.

In this study, we will quantify the effects of SOM on soil hydraulic properties and analyze their impact on the soil water balance in hydrological models in comparison to data acquired by pedotransfer functions.

To cover a wide range of SOM content and properties, we sampled sandy soils (> 80% sand) from five different land use categories (arable land, heathland, grassland, deciduous and coniferous forest). The samples were taken in the Southwest of the Metropolitan region of Hamburg, near Lüchow-Dannenberg. The samples were analyzed for their total soil organic carbon and nitrogen content, and will further be analyzed for their fractions of particulate organic matter (POM) and mineral associated organic matter (MAOM). Hydrophobicity was determined using the water-drop-penetration-time test and contact angle measurements with the sessile drop method. Furthermore, the Integrative Repellency Dynamic Index (IRDI) will be determined for all topsoils to quantify the average hydrophobicity of the sample. Soil water retention is acquired using the porous plate method as well as the evaporation method (HYPROP), including wetting and drying curves. This data will serve as a starting point for simulations under different climate scenarios using HYDRUS.

The aim of this study is to improve our understanding on how hydrophobicity and water retention (wetting and drying) in sandy soils are influenced by the content and properties of SOM, and how this affects the results of hydrological models under different climate scenarios. This will contribute to improve the ability to assess future soil water dynamics, which is vital for sustainable land use and climate change adaptation.

 

The study is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany‘s Excellence Strategy – EXC 2037 'CLICCS - Climate, Climatic Change, and Society' – Project Number: 390683824, contribution to the Center for Earth System Research and Sustainability (CEN) of Universität Hamburg".

How to cite: Schwarze, D., Metzger, J., Spieckermann, M., Becker, J., Herion, Y., Göbel, M.-O., Bachmann, J., and Eschenbach, A.: Concept to quantify the effects of SOM on water retention hysteresis and hydrophobicity in sandy soils and their implication for soil water modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7481, https://doi.org/10.5194/egusphere-egu24-7481, 2024.

EGU24-7858 | Orals | HS8.3.2

Water flow across the skin of the Earth – how badly are we doing? 

Peter Lehmann, Patrick Duddek, and Andrea Carminati

Despite its limited vertical extent, the thin soil layer provides essential functions for climate and ecosystems globally. For accurate large scale process description, land use models compute the water distribution in soils based on spatial domains with a width-to-thickness ratio of about 1000:1: a geometry as thin as a sheet of paper. Most models simulate the water flow in these ‘soil sheets’ by solving the Richardson-Richards equation in 1D, neglecting smaller scale structures and lateral flow, and implicitly making strong assumptions on the relations between water content, matric potential, hydraulic conductivity, and water flux. To quantify the accuracy of this conceptualization, we compare drainage simulations of wet soils for the 1D column simplification with the full 2D-and 3D geometry using the correct sheet-like size ratio. The role of different climates, soil types, and heterogeneities at smaller scale is analyzed. These simulations based on the full geometry provide guidelines for (i) the applicability of Richardson-Richards equation in land surface models and (ii) the development of appropriate averaging schemes of soil hydraulic properties in the 1D scenario.

How to cite: Lehmann, P., Duddek, P., and Carminati, A.: Water flow across the skin of the Earth – how badly are we doing?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7858, https://doi.org/10.5194/egusphere-egu24-7858, 2024.

EGU24-7923 | ECS | Orals | HS8.3.2

Advancing estimates of groundwater recharge by integrating multi-sensor observations across the vadose zone in a drying climate 

Simone Gelsinari, Sarah Bourke, James McCallum, and Sally Thompson

Understanding the impact of climate change on groundwater recharge is crucial for the sustainable management of groundwater systems, especially when regulatory agencies are managing aquifers already fully allocated. Recharge emerges as the outcome of Critical Zone (CZ) processes such as interception, runoff, or plant water uptake that use or store water from rainfall as it traverses the soil-plant-atmosphere continuum. Consequently, recharge is best understood and observed through multiple observations that can characterise storage, potentials and transport of water both in the soil and in the groundwater. Understanding how these CZ processes respond to a variable climate is essential for informing groundwater allocation management and decision-making.

We present the results of field observations and a meta-analysis of recharge studies spanning the last 50 years in the Mediterranean climate area around Perth (Australia). This period coincides with a 15% reduction in winter rainfall, with the impacts on recharge partly revealed by the meta-analysis, but confounded by varying observation methods and sites. Seven field observation sites with consistent, multi-sensor instrumentation were therefore established to reveal recharge dynamics and estimate recharge fluxes. Electromagnetic soil moisture sensors provide vertical information across the soil profile (up to 10 meters below ground), complemented with soil water potential sensing at the surface and capillary fringe. ERT observations and manual soil moisture measurements in ancillary access tubes extend this information laterally (i.e. from 1D to 2D).  Groundwater depth, meteorological and remotely sensed information enables contextualisation of the observations. 

Historical data analysis shows that rainfall reductions lead to nonlinear (3 to 4 times higher), decreases in recharge. The installed monitoring stations reveal how the dynamics of wetting fronts are influenced not only by the climatic variables but also by the types of vegetation and their response to a drying climate. This suggests the presence of distinct local recharge mechanisms operating within the transient systems of the area. The insights obtained from these monitoring sites can be benchmarked against broader observations, such as data provided by remote sensing or borewell measurements, to generate databases of recharge estimates useful for models.

How to cite: Gelsinari, S., Bourke, S., McCallum, J., and Thompson, S.: Advancing estimates of groundwater recharge by integrating multi-sensor observations across the vadose zone in a drying climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7923, https://doi.org/10.5194/egusphere-egu24-7923, 2024.

EGU24-7939 | ECS | Orals | HS8.3.2

Neutron imaging unveils heterogeneous flow patterns in homogeneous porous media and limitations of Darcy-Richards models 

Alexander Sternagel, Ashish Dinesh Rajyaguru, Luca Trevisan, Ralf Loritz, Brian Berkowitz, and Erwin Zehe

We applied neutron imaging techniques to unveil pore scale flow processes occurring during desaturation of a homogeneous, saturated sand pack. For this purpose, we used a small glass flow cell (2 cm x 2 cm x 0.1 cm) filled with pure, artificial S250 quartz sand. The pore space of the sand was initially fully saturated with double distilled water (DDW). The saturated flow cell was subjected to a series of suction phases with increasing suction tensions to extract water via a bottom outlet, controlled by a vacuum pump. In the first phase, a tension of 0.016 MPa (low suction) was applied for 248 min, followed by 1.14 MPa (mid suction) for 227 min, and finally, 10 MPa (high suction) for 397 min. Throughout the entire duration of the experiment, the flow cell was continuously exposed to neutrons. A back-end detector collected the neutron beams passing through the different matters (sand, water, air) contained in the flow cell and generated snapshot images of the internal pore structure and the water distribution with a pixel resolution of 5 µm at one-minute intervals.

The resulting images revealed that water did not redistribute homogeneously during the desaturation of the flow cell, over dimensions of a few millimeters. Despite using “perfectly homogeneous” sand under initially fully water-saturated, controlled conditions, heterogeneous patterns of stable water pockets were observed inside the pore space of the sand, where water became immobilized.

These experiments demonstrate that truly homogeneous flow does not occur even under controlled laboratory conditions in a “perfectly homogeneous” porous medium.

Subsequent simulations of the experiments with common Darcy-Richards models showed that the macroscopic 1D desaturation time series of the flow cell could be realistically depicted. However, even after parameter calibration and the manual addition of heterogeneity, the microscopic, heterogeneous 2D distribution of water observed inside the flow cell could not be reproduced.

This highlights limitations on the applicability of Darcy-Richards models, which may be effective at a macroscopic level but simultaneously fail to represent accurately the internal dynamics of the system. This insight is crucial for the application of Darcy-Richards models and the interpretation of their results.

How to cite: Sternagel, A., Rajyaguru, A. D., Trevisan, L., Loritz, R., Berkowitz, B., and Zehe, E.: Neutron imaging unveils heterogeneous flow patterns in homogeneous porous media and limitations of Darcy-Richards models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7939, https://doi.org/10.5194/egusphere-egu24-7939, 2024.

EGU24-8608 | ECS | Posters on site | HS8.3.2

“rswap” – an R package for automated and command-based interaction with the SWAP4.2 model. 

Moritz Shore and Csilla Farkas

“rswap” is an R package under development for SWAP 4.2 with the goal of simplifying, automating, and improving user interaction with the model. The package functions by detecting and translating SWAP input files into R-compatible dataframes, allowing for easy and automated modifications to parameters. Modified model inputs can then be re-written to files and run in SWAP from the R console using "rswap". SWAP model output can be automatically imported into the R environment and visualized using a variety of (interactive) graphing functions. If observational data is provided by the user, then the package can adjust output settings to match (variables and depth).  Modelled and observed data can then be graphically compared in-line and “goodness-of-fit” statistics can be generated and plotted. Additionally, model runs can be saved and interactively compared with each other, functions are thoroughly documented with runnable examples, and a baseline runnable model setup can be automatically initialized. Further planned developments to the package include support for parallel running of model runs, enabling rapid automated sensitivity analysis, scenario analysis, as well as automated “hard calibration” routines and parameter estimation. Through this functionality, “rswap” can connect the SWAP model to an integrated development environment (IDE), such as “RStudio”, allowing users to efficiently perform all their work (setup, calibration, execution, analysis) in a single environment. Importantly, the packages allows for direct use of  SWAP with the vast array of research software on the R platform. “rswap” is an open-source project originally developed for use in OPTAIN (optain.eu) and has been applied in multiple case studies and thesis projects.

How to cite: Shore, M. and Farkas, C.: “rswap” – an R package for automated and command-based interaction with the SWAP4.2 model., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8608, https://doi.org/10.5194/egusphere-egu24-8608, 2024.

The variability of soil hydraulic properties across different spatial and temporal scales leads to heterogeneous sub-surface water flows, affecting the accuracy of predicting soil water distribution and solute transport. Since soils such as Andosols can describe extreme physical behaviours and water rarely is in hydraulic equilibrium in the porous media, it is still challenging to derive hydraulic functions that realistically represent the influence of soil structure dynamics under different land uses, as well as to predict the occurrence of non-uniform flows at field conditions. This work aimed to describe the spatiotemporal variability of unimodal and dual-porosity (bi-modal) soil water retention (SWR) functions using high-resolution field observations in structured soil affected by compaction. We focused on the influence of water-filled pores volumes at wet and dry conditions, wetting/drying cycles, and soil structure dynamics using three depths (10, 20, and 60 cm). The land use was a diverse grassland sown in September 2019, including three compaction levels (0.65, 0.75, and 0.85 g cm-3, named Control, T1, and T2, respectively) in an Andosol of Southern Chile. A two-year 10-min-resolution dataset (June 2020 to June 2022) of soil moisture content (48 sensors) and matric potential (18 sensors) collected by 6 monitoring stations was analysed by i) separating wet and dry periods dynamics based on soil moisture states, ii) determining wetting and drying cycles using time derivatives of soil moisture content, and iii) fitting and comparing the parameters of unimodal and dual-porosity formulations of the Mualen-van Genuchten numerical solution. Separating soil moisture observations in wet and dry conditions, as well as in wetting and drying cycles, resulted in different SWR curves starting from contrasting water-filled pores volumes. This dynamic-based hydrological parameterisation resulted in a range of high goodness of fit (mean R2 of 0.89 ± 0.07 and 0.94 ± 0.06 for unimodal and dual-porosity van Genuchten models) while deriving SWR functions. However, the dual-porosity formulation better represented complex curvatures in SWR curves towards the soil surface in wet conditions, which would increase our capacity to describe near-saturation macropore dynamics at high resolution. Thus field observations allowed the representation of expected spatial variability between soil depths due to different physical properties and compaction influence. While at the same time, high-resolution time series were used to describe significant different SWR curves for wet and dry conditions when soil structure is affected by compaction, mainly influencing α and n parameters in unimodal formulations, and n1, α2, and n2 in dual-porosity formulations.

How to cite: Bravo-Peña, S., van Schaik, L., and van Dam, J.: Soil water retention function variability based on soil structure and moisture dynamics at field conditions affected by compaction in an Andosol, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9410, https://doi.org/10.5194/egusphere-egu24-9410, 2024.

EGU24-10348 | ECS | Posters on site | HS8.3.2

Connecting soil structure and hydraulic properties under different land use on a European climate gradient 

Dymphie Burger, Wulf Amelung, Heike Schimmel, Lutz Weihermüller, Harry Vereecken, and Sara Bauke

The infiltration of water into the soil, especially during extreme rainfall events, is controlled by soil hydraulic properties such as saturated hydraulic conductivity. Usually, the saturated hydraulic conductivity of the soil at larger scales is estimated by pedotransfer functions that use easily available soil properties such as soil texture, bulk density, and soil carbon content. Unfortunately, it has been already shown that those predictors do not contain the information for precise prediction of the saturated hydraulic conductivity. Moreover, it is widely accepted that the soil structure caused by aggregation, which defines the soil pore network, are important characteristics towards correctly estimating the saturated hydraulic conductivity.

To analyze and quantify the impact of aggregation on the saturated hydraulic conductivity we combined analyses of soil structure based on drop-shatter tests and aggregate size fractionation, with analyses of infiltration pathways via dye tracer application and in-field infiltration measurements. As soil structure is strongly influenced by soil management and climate, we sampled croplands, grasslands, and forests along a European climate gradient.

Our results indicate that both soil structure parameters and the classical predictors used in pedotransfer functions (soil texture, bulk density, and soil carbon content) had a significant influence on the saturated hydraulic conductivity. Regression models using soil structure parameters had a very similar Aikaike Information Criterion (AIC) as regression models without taking soil aggregation into account. This was different for the near-saturated hydraulic conductivity (K-2 cm), where the regression models based on soil texture, bulk density and soil organic carbon content  performed better than the model using soil structure parameters. Additionally, it was found that landuse and plant type had a large influence on soil structural parameters. We found less stained areas (0- 30 cm depth) in forests than in croplands and grasslands, which indicates more occurrences of preferential flow, and this was also  negatively correlated with the initial soil moisture at the time of measurement. In addition, higher levels of aggregation, indicated by a higher mean weight diameter of the soil aggregates, was associated with higher preferential flow as indicated by the dye tracer Both, stained area and peds and clods were influenced by the plant type as well, since the sites with vegetation having predominantly fibrous root systems responded differently than the sites with tap-rooted plants, trees, or heathland vegetation. The enhanced information on soil structure can therefore help us better understand landuse and land cover effects on saturated hydraulic conductivity and soil water infiltration.

How to cite: Burger, D., Amelung, W., Schimmel, H., Weihermüller, L., Vereecken, H., and Bauke, S.: Connecting soil structure and hydraulic properties under different land use on a European climate gradient, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10348, https://doi.org/10.5194/egusphere-egu24-10348, 2024.

EGU24-10493 | ECS | Posters on site | HS8.3.2

Groundwater influence on the frequency of heatwaves: A global perspective 

Anastasia Vogelbacher, Milad Aminzadeh, Mehdi H. Afshar, and Nima Shokri

Groundwater plays a crucial role in land-atmosphere interactions through its effect on soil moisture, evaporation and thus surface heat fluxes (1). Variation of rainfall patterns in a changing climate and the increase in water demands are expected to influence groundwater dynamics that affect soil moisture-air temperature feedback processes and subsequently the occurrence of heatwaves. The decline in groundwater levels with intensified abstraction could hinder its buffer capacities to impede soil desiccation and onset of heatwaves. The current understanding of the relationship between shallow groundwater tables and heatwave events is often limited to regional studies or specific land covers, with a very few endeavors seeking to characterize global-scale trends and responses. We thus aim to globally investigate the relation between groundwater levels and heatwave events considering different land cover types and environmental variables by conducting a wide-ranging statistical analysis. Our approach involved leveraging a comprehensive dataset, allowing us to distinguish potential links between groundwater tables and the frequency of heatwaves over a range of geographical and climatological parameters. The findings from our investigation provide valuable insights into the relationship between groundwater dynamics and heatwave frequency within the broader context of the interactions between soil moisture and air temperature. This information will aid in devising effective action plan to mitigate the adverse effects of climate change.

 

 

Reference:

(1) Maxwell, R., Kollet, S. Interdependence of groundwater dynamics and land-energy feedbacks under climate change. Nature Geosci1, 665–669 (2008). https://doi.org/10.1038/ngeo315

 

How to cite: Vogelbacher, A., Aminzadeh, M., Afshar, M. H., and Shokri, N.: Groundwater influence on the frequency of heatwaves: A global perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10493, https://doi.org/10.5194/egusphere-egu24-10493, 2024.

EGU24-10596 | ECS | Orals | HS8.3.2

Comparing the accuracy of soil moisture estimation derived from environmental and spectroscopic gamma radiation measurements  

Sonia Akter, Johan Alexander Huisman, and Heye Reemt Bogena

Continuous monitoring of root-zone soil moisture status is important to ensure the effective management of water resources for agricultural production, and to improve our understanding of land-atmosphere interactions in a changing climate. Utilizing gamma radiation to monitor soil moisture at the field scale is an emerging non-invasive technique that can also bridge the gap between point and remote sensing measurements. The measurement principle relies on the increased attenuation of gamma radiation emitted from soil with increasing soil moisture content. In a previous study, we successfully obtained soil moisture estimates from low-cost environmental gamma radiation (EGR) detectors. However, since EGR detectors provide the bulk response to gamma radiation over a wide energy range (0 to 3000 keV), EGR signals are influenced by several confounding factors, e.g., skyshine radiation, atmospheric and soil radon variability. To what extent these confounding factors deteriorate the accuracy of soil moisture estimates obtained with EGR is still not fully understood. Therefore, the aim of this study is to compare EGR measurements with K-40 gamma radiation (at 1460 keV) measurements that are much less influenced by these confounding factors. For this, two different kinds of gamma radiation detectors were installed close to each other at an agricultural field in Selhausen, Germany: an EGR detector based on a G-M counter tube (MIRA, ENVINET GmbH) and a spectroscopic scintillation-based detector (SARA, ENVINET GmbH). The field was also equipped with in-situ soil moisture sensors to measure reference soil moisture and a climate station to measure meteorological parameters. The EGR measurements were corrected for atmospheric radon-washout during precipitation events and the contributions of meteorologically influenced secondary cosmic radiation were also eliminated. In case of the spectroscopic measurements, no further corrections were applied as the analysis was only focused on the K-40 energy window. Both sets of gamma radiation measurements were related to reference soil moisture using a functional relationship derived from theory. We found that daily soil moisture can be predicted more accurately from K-40 gamma radiation (RMSE 4 vol.%) than from EGR (RMSE 6 vol.%). Regardless of the higher prediction uncertainty obtained due to the influence of the confounding factors at low energy, the long-term availability of ERG data, e.g., in Europe via EURDEP, makes it interesting for continental scale analysis of soil moisture. 

How to cite: Akter, S., Huisman, J. A., and Bogena, H. R.: Comparing the accuracy of soil moisture estimation derived from environmental and spectroscopic gamma radiation measurements , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10596, https://doi.org/10.5194/egusphere-egu24-10596, 2024.

EGU24-10970 | Posters on site | HS8.3.2

Assessing heterogeneity of preferential soil water fluxes in situ with zero-tension microlysimeters in a temperate forest 

Johanna Clara Metzger, Volker Kleinschmidt, Truxton Oldridge, Matthias Beyer, and Annette Eschenbach

Macropore flow in structured soils constitutes an important component of soil water fluxes. This is especially true for unmanaged ecosystems. Preferential flow substantially affects ecohydrological separation, the partitioning of precipitation water into green (soil matrix, vegetation) and blue (recharge) water. Event characteristics, which are affected by changing climate, impact preferential flow; this, in turn, has an impact on ecohydrological separation and water resource availability. Though its importance is widely acknowledged since decades, it remains a challenge to measure preferential flow in soils. Additionally, small-scale heterogeneity of soil and environmental properties triggers spatial heterogeneity of preferential flow. In this study, we test the potential of zero-tension microlysimeters to measure preferential flow in a high spatial resolution. Zero-tension lysimeters have been used to sample soil water solution for chemical analysis. Methodical studies have shown that soil matric fluxes flow around zero-tension lysimeters and only gravity-driven water fluxes are captured. Using this to our advantage, we aim to develop a low-cost and simple method to sample preferential (gravity-driven) soil water fluxes in point measurements. This enables the implementation of a statistical design due to a high possible number of repetitions and the comparison with standard soil water status sensors due to similar scales. We are testing our lysimeters in a temperate mixed deciduous forest at Apelern, Lower Saxony, Central Germany. The soils are shallow and consist of weathered limestone intermingled with loess. By implementing transects starting from tree stems, we aim to cover a range of input fluxes and soil properties. We are combining lysimeters with measurements of soil water content, stand precipitation and soil properties. With our setup, we will be able to gain insight into the heterogeneity of preferential fluxes in situ and compare soil, stand and event impact factors to get a better understanding of the role of macropore flow in ecohydrological separation.

How to cite: Metzger, J. C., Kleinschmidt, V., Oldridge, T., Beyer, M., and Eschenbach, A.: Assessing heterogeneity of preferential soil water fluxes in situ with zero-tension microlysimeters in a temperate forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10970, https://doi.org/10.5194/egusphere-egu24-10970, 2024.

EGU24-11862 | Posters on site | HS8.3.2

Experimental evidence of non-equilibrium water flow during bare-soil evaporation 

Sascha Iden, Efstathios Diamantopoulos, Magdalena Sut-Lohmann, and Wolfgang Durner

The Richards equation is de facto the standard model for simulating variably-saturated water flow in soils. It is based on the assumption that water content and matric potential are in instantaneous equilibrium. Their relationship is the water retention curve which is widely used to evaluate soil quality, to determine the effective pore-size distribution, and to derive the soil hydraulic conductivity curve. Experimental data collected over the last 6 decades show that the water retention curve depends not only on the history of wetting / drying, but also on the dynamics of water flow (transient vs equilibrium conditions). Many studies present experimental evidence on the hypothesis that the faster the water flow in soils, the more pronounced is the deviation of the dynamic retention curve from the equilibrium one. In this contribution, we present experimental data which show that these effects also occur during experiments in which water flow can be characterized as relatively slow. We conducted evaporation experiments on two soils, a sand and a silt loam, and varied the evaporation rate. Evaporation rates were controlled by wind speed, and flow interruptions were induced by temporarily covering the samples. We measured soil temperature and matric potential at different depths. The results show a relaxation of the matric potential with changes in wind speed, in particular during the flow interruptions. A complete analysis of the data requires a distinction between the vertical redistribution of moisture caused by changes in the evaporation rate, the effect of temperature on matric potential, and the “true” nonequilibrium between matric potential and water content. Contrary to the general assumption that bare-soil evaporation is a slow process during which equilibrium between water content and matric potential is ensured, our results show that dynamic nonequilibrium occurs even in the case of relatively slow, upward water flow. This results in a shift in the dynamic water retention curve estimated from evaporation experiments, indicating that more water is retained in the soil when water is flowing, as compared to static experiments.

How to cite: Iden, S., Diamantopoulos, E., Sut-Lohmann, M., and Durner, W.: Experimental evidence of non-equilibrium water flow during bare-soil evaporation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11862, https://doi.org/10.5194/egusphere-egu24-11862, 2024.

EGU24-11928 | ECS | Orals | HS8.3.2

The dynamics of field soil water retention curves predicted by autoencoder neural network 

Nedal Aqel, Andrea Carminati, and Peter Lehmann

The matric potential plays a pivotal role in understanding of water movement, plant water availability, and mechanical stability. In lack of direct measurements, the matric potential dynamics must be deduced from soil water content values, using the soil water retention curve. This approach is of particular importance at larger scales where only the water content (but not the potential) can be deduced from satellite data. However, because the relationship between water content and matric potential in natural field soils is highly ambiguous, not unique and dynamic, the prediction of matric potential from water content data is a big challenge. This ambiguity is related to different structures controlling drainage and wetting, dynamic effects, and seasonal changes of structures controlling the water distribution. In this study we present an autoencoder neural network as a new approach to analyze the soil moisture dynamics and to predict matric potential from water content data. The autoencoder compresses the water content time series into a site-specific feature (denoted as autoencoder value, AUV) that is representative of the underlying soil moisture dynamics. The AUV can then be used as predictor of the matric potential and the highly hysteretic soil water retention curve. The approach was tested successfully for nine soil profiles in the region of Solothurn (Switzerland). Three sites were chosen to establish the connection between AUV and the ambiguous soil water retention curve using a deep neural network, that was then applied to predict the matric potential dynamics of the other six sites. This method offers the potential to (i) deduce matric potential dynamics by relying solely on soil water content measurements (including satellite data), even when strong seasonal effects challenge standard methods, and (ii) serves as a warning system for changes in soil properties and in the intricate relationship between soil water content and matric potential dynamics.

How to cite: Aqel, N., Carminati, A., and Lehmann, P.: The dynamics of field soil water retention curves predicted by autoencoder neural network, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11928, https://doi.org/10.5194/egusphere-egu24-11928, 2024.

EGU24-11976 | Posters on site | HS8.3.2

Manual versus Automated Beerkan run for characterizing the hydraulic properties of sandy soil in Senegal's Sahel 

Laurent Lassabatere, Deniz Yilmaz, Faye Waly, Didier Orange, Hanane Aroui, Djim ML Diongue, Saint-Martin Saint-Louis, Thierry Winiarski, Brice Mourier, Rafael Angulo-Jaramillo, Simone Di Prima, Olivier Roupsard, and Frederic C. Do

The comprehension of hydrological processes inherent in the water cycle and its constituents is of paramount significance when formulating adaptation strategies to address climate and global changes. The Sahel region serves a crucial role as a buffer zone between the arid desert and the more verdant and precipitation-laden areas of Senegal. The savanna region comprises a dynamic amalgamation of woody perennials intermixed with agricultural crops and pastures. The sustained vitality of this ecosystem hinges upon sustainable agriculture, mandating the judicious utilization of water resources. The formulation of strategies geared towards optimizing water resource management necessitates a comprehensive understanding of hydrological processes. This includes the investigation of water infiltration at the soil surface, the dynamics of water redistribution within the soil profile, and the mechanisms governing groundwater recharge. These scientific insights will help to develop effective strategies for the sustainable utilization of water resources within the Sahel region.  The intended investigation seeks to characterize the hydraulic properties of sandy soils that extensively prevail within the savanna ecosystem.

The utilization of water infiltration experiments coupled with corresponding modeling presents a robust framework for non-intrusive on-site hydraulic soil characterization. These methodologies have been widely employed across diverse contexts (Angulo-Jaramillo et al., 2019, for a review). To achieve this objective, the Beerkan method, initially proposed by Braud et al. (2005), involving the controlled infiltration of known water volumes into a designated ring, has been identified as a pertinent approach. Recently, Di Prima et al. (2016) have introduced an automated infiltrometer as a substitute for the manual Beerkan method, thereby streamlining and enhancing the procedural aspects of hydraulic soil characterization.

The study pursues a dual objective: (i) to characterize the hydraulic properties of sandy soil and delineate their spatial variability, both horizontally and vertically across the soil profile; and (ii) to assess the influence of the chosen water infiltration setup (Manual versus Automated Beerkan) on the obtained results. The investigation involved the excavation of three pits arranged as steps, providing access to five distinct horizons that spanned from the soil surface to a perched aquifer positioned at 2.5/3 m depth. Both Manual and Automated Beerkan experiments were conducted at the soil surface and for each horizon. Cumulative infiltrations were subjected to analysis using the BEST methods for precise determination of hydraulic parameters. Furthermore, bulk density and particle size distributions were determined for each Beerkan run by coring the soil at the conclusion of the experiment.

The examination of infiltration rates and hydraulic parameter profiles across the soil profiles, along with the comparative analysis of values derived from manual versus automated Beerkan runs, furnished pertinent insights to address the study's dual objectives.

References

Angulo-Jaramillo, R., et al., 2019. Journal of Hydrology. 576, 239–261. https://doi.org/10.1016/j.jhydrol.2019.06.007

Braud, I., et al., 2005. European Journal of Soil Science 56, 361–374. https://doi.org/10.1111/j.1365-2389.2004.00660.x

Di Prima, S., et al.,2016. Geoderma 262, 20–34. https://doi.org/10.1016/j.geoderma.2015.08.006

How to cite: Lassabatere, L., Yilmaz, D., Waly, F., Orange, D., Aroui, H., Diongue, D. M., Saint-Louis, S.-M., Winiarski, T., Mourier, B., Angulo-Jaramillo, R., Di Prima, S., Roupsard, O., and Do, F. C.: Manual versus Automated Beerkan run for characterizing the hydraulic properties of sandy soil in Senegal's Sahel, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11976, https://doi.org/10.5194/egusphere-egu24-11976, 2024.

EGU24-12002 | Posters on site | HS8.3.2

Ground-penetrating radar can ascertain the influence of biochar on soil wetting 

Lakshman Galagedara, Sashini Pathirana, and Manokararajah Krishnapillai

Incorporating biochar (BC) as a soil amendment has become a prominent agricultural management practice since it has many advantages. Most soils amended with BC have shown improvements in soil physical and hydraulic properties, including bulk density, soil porosity, water retention, field capacity, and permanent wilting point. Ground-penetrating radar (GPR) is a non-destructive geophysical technique that is used to study soil properties and state variables. Yet, there is a lack of research studying the influence of amendments on soil hydrology using GPR.  Therefore, this study was aimed at evaluating the ability of GPR in assessing the effect of BC on soil hydrology. The experiment was conducted under laboratory conditions using plastic containers measuring 28.6 cm in length, 20 cm in width and 16.4 cm in height. These plastic containers were filled up to 14 cm height with three different treatments (T); T1 (100% Sand+0% BC), T2 (99.5% Sand+0.5% BC), and T3 (98% Sand+2% BC) on a mass basis. Soil moisture sensors were placed horizontally at 2, 7, and 12 cm depths while packing the containers. The GPR data were collected using 1000 MHz center frequency transducers by keeping transmitter and receiver on opposite sides of the container (zero-offset profiling survey) at 20 cm antenna offset. Data were collected before, during, and after the wetting process over a one-hour timeframe. A 204 mL of water was applied every 4 min (13 times) to increase the soil water content at each time by 2% from initial water content. The GPR data were processed, and radargrams were prepared to observe the wetting front movement. Soil water contents were estimated utilizing the travel time of the GPR direct wave through the treatment media. GPR travel time and moisture sensor data were compared in each treatment. The GPR estimated soil water contents correlated well with moisture sensor data (correlation coefficient (r)>0.93) in all three treatments. Results have shown that the travel time of GPR direct wave responded differently for three treatments. The rate of change in GPR estimated soil water content over time exhibits an increase with the percentage of BC (T1<T2<T3). This suggests that the amendments with BC influence the soil water dynamics as expected, and the GPR effectively captures these rapid water content changes indicating its ability to monitor soil water dynamics non-destructively. Furthermore, the identification of the wetting pattern by GPR was noticeably distinct as compared to that observed with soil moisture probes in the BC amended treatments (T2 and T3), as compared to 100% sand (T1). Accordingly, our study demonstrates the capability of GPR in non-destructively capturing and distinguishing soil water dynamics influenced by BC amendments, emphasizing its potential for evaluating the impact of BC on soil hydrology.

How to cite: Galagedara, L., Pathirana, S., and Krishnapillai, M.: Ground-penetrating radar can ascertain the influence of biochar on soil wetting, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12002, https://doi.org/10.5194/egusphere-egu24-12002, 2024.

EGU24-12041 | Orals | HS8.3.2

Overview of water retention and suction stress properties of layered pyroclastic ashes in landslide prone areas of Campania, southern Italy 

Daniel Camilo Roman Quintero, Emilia Damiano, Lucio Olivares, and Roberto Greco

The loose, stratified composition of pyroclastic soil covers typically consists of layers of air-fall ashes and pumices. When these deposits are resting on steep slopes, they pose a significant geohazard due to slope instabilities. This scenario is evident in the carbonate massifs covered by pyroclastic soils in Campania (southern Italy), an extensive area of about 400 km2 prone to landslides. In these porous deposits, the soil suction in unsaturated conditions plays a crucial role in enhancing the slope stability by providing additional shear strength.

This study aims to present a comprehensive overview of the hydraulic and shear strength characteristics observed in different layers of pyroclastic ashes across various sites in the Campania study area. By gathering datasets from previous studies and introducing new experimental data, the relationship between soil index, hydraulic properties and the shear strength in unsaturated conditions is examined.

The findings highlight notable differences in hydraulic properties of soils originating from the same location but belonging to different layers: ashes from intermediate layers within the soil profile, where failure surface usually occurs; weathered ashes in direct contact with the carbonate bedrock, responsible of water exchange with deeper systems. The water retention curves of intermediate ashes exhibit air entry values at approximately 4 kPa, while those in contact with the bedrock show values around 25 kPa. Conversely, soils from the same layer but from different sites exhibit relatively similar hydraulic characteristics. For example, intermediate ashes from the same layer typically display air entry values varying between 0.5 kPa and 4 kPa. The same behavior also appears regarding the influence of soil suction on the shear strength of the investigated materials, which can be estimated directly from the water retention curves.

How to cite: Roman Quintero, D. C., Damiano, E., Olivares, L., and Greco, R.: Overview of water retention and suction stress properties of layered pyroclastic ashes in landslide prone areas of Campania, southern Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12041, https://doi.org/10.5194/egusphere-egu24-12041, 2024.

EGU24-12145 | ECS | Posters virtual | HS8.3.2

Comparing manual versus automated Beerkan runs for the estimation of water infiltration and soil hydraulic parameters for an urban soil 

Saint Martin Saint Louis, Fasnet Boncourage, Simone Di Prima, Dieuseul Prédélus, Rafael Angulo-Jaramillo, and Laurent Lassabatere

Adapting cities to climate and global changes requires tremendous progress in managing the water cycle in cities. So far, the water pathways are disconnected from the natural water cycle in urban areas. Runoff water is collected and routed to sewer systems. Best management practices were then developed to restore the natural water cycle by promoting water infiltration into specific urban drainage systems. These are often called “SUDS” for Sustainable Urban Drainage Systems and infiltrate the runoff water collected over urban catchments. However, SUDS may lose their capability to infiltrate water as the soil clogs and becomes less permeable. For these devices, soil hydraulic conductivity must be monitored over time.

Water infiltration techniques have been developed to characterize the soil hydraulic properties. The Beerkan method was pioneered by Braud et al. in 2005 and then used by many soil scientists (Angulo-Jaramillo et al., 2016). Several algorithms were developed to treat the data and estimate the soil hydraulic properties. In 2006, Lassabatere et al. (2006) initiated the BEST method to identify the saturated hydraulic conductivity and the whole set of unsaturated hydraulic parameters from Beerkan runs combined with field data (bulk density and particle size distribution). Since then, the method has been improved and adapted to many types of soils and configurations (see Angulo-Jaramillo et al., 2019, for a review).

The Beerkan run is easy to perform. It requires one operator to prepare known volumes of water, infiltrate them into a ring inserted in the soil, and score the infiltration times. The cumulative infiltration, which assigns the cumulative infiltrated volume to the infiltration time, is the raw data that is used in most hydraulic characterization algorithms. However, its ease of use requires human resources (one operator) and may be time-consuming, particularly for fine soils that infiltrate very slowly. Di Prima et al. (2016) recently designed an automated infiltrometer that replaces the operator. The device automatically supplies the water before desaturation of the soil surface and records the infiltrated volume as a function of time. This device has been deployed for several studies, allowing the hydraulic characterization of several types of soils under several field conditions.

However, so far, no studies have focused on comparing the automated infiltration, referred to as “Automated Beerkan,” and the manual version of the Beerkan runs. In this study, we performed the two types of runs at the same places in order to avoid uncontrolled variations due to spatial variability in urban soils. We present the cumulative infiltrations obtained at the same point with the automated Beerkan and the original Beerkan (manual version). The cumulative infiltrations were inverted using the BEST methods, and the obtained hydraulic parameters were compared.

Di Prima, S., et al.,2016. Geoderma 262, 20–34. https://doi.org/10.1016/j.geoderma.2015.08.006

Angulo-Jaramillo, R., et al., 2016. Springer, Switzerland. https://doi.org/10.1007/978-3-319-31788-5

Angulo-Jaramillo, R., et al., 2019. Journal of Hydrology 576, 239–261. https://doi.org/10.1016/j.jhydrol.2019.06.007

Braud, I., et al. 2005. European Journal of Soil Science 56, 361–374. https://doi.org/10.1111/j.1365-2389.2004.00660.x

Lassabatere, L., et al., 2006. Soil Science Society of America Journal 70, 521–532. https://doi.org/10.2136/sssaj2005.0026

How to cite: Saint Louis, S. M., Boncourage, F., Di Prima, S., Prédélus, D., Angulo-Jaramillo, R., and Lassabatere, L.: Comparing manual versus automated Beerkan runs for the estimation of water infiltration and soil hydraulic parameters for an urban soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12145, https://doi.org/10.5194/egusphere-egu24-12145, 2024.

EGU24-12183 | ECS | Posters on site | HS8.3.2

Extending the measurement range for determining soil hydraulic properties with the simplified evaporation method using relative humidity sensors 

Jannis Bosse, Sascha C. Iden, Wolfgang Durner, Magdalena Sut-Lohmann, and Andre Peters

A precise knowledge of soil hydraulic properties is crucial for many applications, with the unsaturated hydraulic conductivity being most challenging to measure accurately. Direct measurement under dry conditions presents difficulties, lacking simple and precise methods. While the simplified evaporation method (SEM) has become the standard for determining the water retention curve (WRC) and hydraulic conductivity curve (HCC), its classic implementation only provides conductivity values within a relatively narrow suction range measurable by tensiometers, typically between 60 and 1000 cm.

In this study, we extended the experimental setup of the SEM by incorporating small sensors to measure temperature and relative humidity alongside the tensiometers. Applying the Kelvin equation, this addition allows for suction measurements between the wilting point and air-dry conditions. Using this setup, we conducted evaporation experiments on soils spanning various textures, from silt loam to pure sand. Analyzing the data through (i) inverse modeling using the Richards equation and (ii) the SEM revealed that combining tensiometers and relative humidity sensors facilitates the determination of HCC over a broad moisture range. This includes the suction range covered between the measurement ranges of the sensors, given proper interpolation between the two sensor types.

Crucially, successful inverse modeling relies on a suitable parametric representation of the soil hydraulic properties, considering water adsorption, film, and vapor flow. Our findings indicate that the classic SEM evaluation tends to overestimate HCC in the tensiometer's measuring range and underestimate it in the hygroscopic range, especially in coarse-textured soils with a narrow pore size distribution. Despite this limitation, the proposed test setup, when coupled with the SEM, offers practical advantages due to its relative simplicity and ease of data evaluation.

How to cite: Bosse, J., Iden, S. C., Durner, W., Sut-Lohmann, M., and Peters, A.: Extending the measurement range for determining soil hydraulic properties with the simplified evaporation method using relative humidity sensors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12183, https://doi.org/10.5194/egusphere-egu24-12183, 2024.

EGU24-12291 | ECS | Orals | HS8.3.2

Evaluation of Soil Mapping Methods for SWAT Hydrological Modeling through Multi-Objective Calibration 

Fernando Gimeno, Mauricio Zambrano-Bigiarini, Mauricio Galleguillos, and Rodrigo Marinao

Soil data is a crucial component for hydrological models operating at the catchment scale, such as the Soil and Water Assessment Tool (SWAT). Nevertheless, the reliability of these models is heavily contingent upon the quality and spatial resolution of the soil information employed. This study addresses the pressing need for robust soil data in SWAT modeling by evaluating various soil mapping techniques.

The first objective was to prove different mapping techniques, such as textural class combination and clustering approach using soil grid data to have different soil maps. The performance of those maps, together with WRB, WSR, Zobler, HWSD v2.0 and DSOLMAPS, was evaluated to improve the accuracy and reliability of the SWAT hydrological model. To achieve this, we conduct a comprehensive investigation involving multi-objective calibration, utilizing both flow data and soil moisture data to calibrate the model. Finally we incorporate a  pedotransfer function to include the landcover effect on Saturated Hydraulic Conductivity to improve the reliability of soil hydrological processes in the SWAT model.

The study area, situated within the Cauquenes River Catchment, presents a complex hydrological system characterized by substantial spatial heterogeneity in soil properties. The soil mapping techniques under evaluation encompass traditional soil survey data integrated with remotely sensed soil information and machine learning-based soil mapping methodologies. These methods are compared in their ability to enhance the SWAT model's representation of the catchment's hydrological dynamics.

In the case of the kmeans clustering approach the results of soil clusters are equivalent to soil units. A number of clusters from 3 to 100 were evaluated with the lowest DB index. Clusters from 3 to 16 presented an optimal range. The SWAT model calibration was performed under multi-objective evaluation, with kmeans soil cluster and DSoilMaps with better result for daily simulations.

The work to correct the application of soil data, including in situ observation, satellite data and machine learning approach, provides a valuable approach to improve the calibration and validation processes of hydrological models in semi-arid regions, important for cacthment management and decision making processes, and to correctly assess the impacts of land use changes, climate variability and extreme events on water resources. 

How to cite: Gimeno, F., Zambrano-Bigiarini, M., Galleguillos, M., and Marinao, R.: Evaluation of Soil Mapping Methods for SWAT Hydrological Modeling through Multi-Objective Calibration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12291, https://doi.org/10.5194/egusphere-egu24-12291, 2024.

EGU24-12832 | ECS | Orals | HS8.3.2

Tree influence on water dynamics in sloped forest soils: insights from stemflow and throughflow experiments and time-lapse ground-penetrating radar monitoring 

Gersende Fernandes, Maria Burguet Marimon, Maria Paz Salazar, Elisa Marras, Ilenia Murgia, Konstantinos Kaffas, Filippo Giadrossich, Ryan D. Stewart, Majdi R. Abou Najm, Alessandro Comegna, Laurent Lassabatère, Daniele Penna, Christian Massari, and Simone Di Prima

Incident gross precipitation is divided by tree canopies into three main parts: i) intercepted rainfall, which evaporates directly from the canopies, ii) throughfall, which reaches the soil surface after passing through the canopies, and iii) stemflow, which is concentrated from the canopies to the stems. Stemflow tends to infiltrate preferentially around the base of the stem, and once belowground, is channeled by tree roots.

The objective of this research was to investigate the contribution of stemflow and throughflow to subsurface water dynamics in a hillslope forested with beech trees. The experimental activities were carried out in a 10 x 10 m plot located in the Lecciona catchment of the Appennine Mountains, Central Italy.  Stemflow was collected from seven beech trees located within the plot. Stemflow and throughfall were sequentially and then simultaneously induced using controlled water applications. Time-lapse ground-penetrating radar (GPR) surveys were conducted under each line of trees. Overland flow and subsurface runoff were collected with V-shaped gutters positioned at the bottom of the trees and at the downhill plot edge.

Stemflow infiltration rates were calculated by a mass balance, i.e., subtracting the collected overland flow from the injected volume and then dividing by the stem basal area and the time of steady infiltration. Mean values for each tree and for the entire plot, the latter considering the throughfall experiments, were approximately 1000 mm/h. The GPR data enabled the detection of active preferential flow paths, assessment of hillslope connectivity, and estimation of flow velocities. GPR gave relevant information in the flow pathways in the soils, the effects of root systems and its combination with matrix flow.

This experiment represents a straightforward, replicable, and non-invasive method for characterizing the role of trees in water runoff and infiltration at the hillslope spatial scale, and more broadly, in understanding how forested hillslope respond to rainstorms.

How to cite: Fernandes, G., Burguet Marimon, M., Paz Salazar, M., Marras, E., Murgia, I., Kaffas, K., Giadrossich, F., D. Stewart, R., R. Abou Najm, M., Comegna, A., Lassabatère, L., Penna, D., Massari, C., and Di Prima, S.: Tree influence on water dynamics in sloped forest soils: insights from stemflow and throughflow experiments and time-lapse ground-penetrating radar monitoring, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12832, https://doi.org/10.5194/egusphere-egu24-12832, 2024.

EGU24-13115 | ECS | Posters on site | HS8.3.2

Advancing hydrological monitoring: Terrestrial gravimetry surveys in the Selke Catchment, Germany 

Sara Sayyadi, Daniel Rasche, Marvin Reich, Theresa Blume, and Andreas Güntner

In this study, spatial and temporal variations of soil moisture and water storage were monitored with two complementary methods: terrestrial gravimetry and cosmic ray neutron sensing (CRNS). CRNS monitors near-surface soil moisture by measuring low-energy neutron abundance in the near-surface atmosphere, which inversely correlates with soil moisture in the top decimeters of the soil. Terrestrial gravimetry monitors water storage variations in an integrative way over the entire unsaturated zone and the groundwater. Both methods allow for non-invasive spatially integrated field-scale monitoring around the instruments.

The study area is the Selke catchment in Central Germany with an area of 456 km². It has notable variations in topography, land use, and meteorology from the lowlands to the low mountain ranges. A combined approach was applied for terrestrial gravimetry: continuous stationary and time-lapse network surveys. We deployed a gPhone in a container-based housing (SolarCube) which serves as a base station for the relative gravity campaigns. Using two CG-6 gravimeters, the campaigns were conducted at six sites within the catchment area with co-located CRNS installations. In total five relative gravity surveys were carried out from July to October 2023. Each of them consisted of a two-day campaign where each survey point was visited three times by the two gravimeters. In order to ensure a high quality of the gravity data, capable of resolving a signal in the magnitude typical for hydrological processes in the area, a network adjustment of the repeated survey data was carried out. This included device-specific drift estimations. The results are combined with the continuous time series of the gPhone and analyzed jointly in a spatio-temporal approach with CRNS and in-situ soil moisture observations. Temporal dynamics of storage dynamics are assessed and spatial differences between the upland and the lowland areas are analyzed.

How to cite: Sayyadi, S., Rasche, D., Reich, M., Blume, T., and Güntner, A.: Advancing hydrological monitoring: Terrestrial gravimetry surveys in the Selke Catchment, Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13115, https://doi.org/10.5194/egusphere-egu24-13115, 2024.

EGU24-13600 | Orals | HS8.3.2

A hydrothermal model for unsaturated frozen rocks based on lattice Boltzmann method 

Zheng Wang, Chi Zhang, Yaning Zhang, and Bingxi Li

Frost weathering is considered the primary cause of erosion in periglacial environments. This process is initiated by the freezing of water within rock pores and its subsequent expansion, which generates substantial forces leading to the physical fragmentation and disintegration of the rock structure. To detail the mechanism and predict the patterns of rock fracturing, this study has developed a specialized numerical model. In previous study, researchers typically studied the mechanical failure of rocks via macroscopic numerical methods. However, these methods often face limitations in depicting mesoscale forces, particularly in the context of multiphase flow processes of water migration. Moreover, the influences of various hydrothermal conditions on the mechanical behavior of rocks are frequently overlooked. In this study, a coupled lattice Boltzmann model (LBM) was developed to simulate the freezing process in rocks. The porous structure with complexity and disorder was generated by using a stochastic growth method, and then the Shan-Chen multi-phase model and enthalpy-based phase change model were coupled by introducing a freezing interface force to describe the variation of phase interface. By utilizing the developed model, the ice growth process in rock pores can be well depicted under porous conditions characterized by varying contact angles, porosities, and specific surface areas. Building on this foundation, our work advances the understanding of the complex interaction between thermal dynamics and mechanical processes in periglacial environments, shedding light on the mechanisms of frost weathering and the predictive modeling of rock fracture patterns under varying hydrothermal conditions.

How to cite: Wang, Z., Zhang, C., Zhang, Y., and Li, B.: A hydrothermal model for unsaturated frozen rocks based on lattice Boltzmann method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13600, https://doi.org/10.5194/egusphere-egu24-13600, 2024.

The location of dry layer interface (LDI), which varies during soi drying process, is a key parameter for characterizing soil water evaporation process. Recently the heat pulse (HP) technique has been applied to estimate the LDI indirectly. However, errors may occur with the HP method when analytical solutions are used because of soil heterogeneity across the measurement plane, especially when a heterogeneous interface lies between the two probes. In this study, we propose a numerical inversion-based heat pulse method for estimating the LDI under five configurations. The inputs are thermal properties of dry and wet soils, and the temperature rise-by-time curves at two locations from the heat source. The heat source was positioned at different distances from the LDI. The inversion method was evaluated with temperature rise-by-time curves from 17 scenarios obtained from numerical simulation and 14 scenarios obtained from laboratory measurements. Results demonstrated that the new approach produced reasonable LDI estimates within the range of 0.1 to 5 cm to the soil surface, with relative errors (REs) less than 0.30, except for the situation that the LDI was close to the heat source. The proposed method has significant implications in groundwater management and modeling hydrological processes in unsaturated soils.

How to cite: Liu, L., Xie, X., Lu, Y., and Ren, T.: Locating the dry layer interface during soil water evaporation by using numerical inversion-based heat pulse method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13980, https://doi.org/10.5194/egusphere-egu24-13980, 2024.

Extensive cropland-to-orchard transition alters water flow and nitrate transport in the vadose zone (VZ) of the Earth’s Critical Zone (CZ), which may impact groundwater recharge and threaten future water quality from intensive nitrogen fertilizer application. Understanding the regional unsaturated water and nitrate fluxes and travel times in the deep VZ is crucial for the sustainable management of the groundwater system. Here, a regional-scale model was developed to estimate the recharge and nitrate transport in the cultivated loess CZ of China’s Guanzhong Plain (CGP), where cropland-to-orchard transition has been extensively promoted in the past few decades. Besides, uncertainties and sensitivities in estimated fluxes of water and nitrate induced by variations in soil hydraulic parameters (SHPs) were evaluated. A comparison between model simulations and observations at 12 sites exhibits good simulation performance. Comparing the measured SHPs, SHPs from Rosetta and Global SHPs products introduced 86.28% and 48.94% uncertainties in the simulation of nitrate leaching fluxes from cropland and orchard, respectively, as well as 44.76% uncertainties in the simulation of groundwater recharge fluxes from the orchard. Application over the CGP based on measured SHPs indicates that the central and eastern CGP were the hotspots for groundwater nitrate contamination. By comparing traditional cropland and orchard scenarios, simulations reveal that cropland-to-orchard transition results in a 39.3-fold increase in nitrate leaching fluxes and a 9.8% decrease in groundwater recharge fluxes. Modeled nitrate travel times through the deep VZ range between decades and centuries under both land use scenarios; however, the cropland-to-orchard transition would extend the time (~22.4 years) it takes for nitrate to reach the aquifer. Although cropland-to-orchard transition delays nitrate transport to the aquifer, the increased nitrate leaching flux will increase the risk of nitrate groundwater pollution, especially in areas with shallow VZs and coarse soil texture. This study provides valuable information for assessing the future vulnerability of groundwater resources under agricultural land use and management changes in the cultivated loess CZ.

How to cite: Niu, L. and Jia, X.: Future Orchard Expansion May Decrease Groundwater Recharge and Increase Nitrate Contamination in An Intensively Cultivated Loess Critical Zone, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14516, https://doi.org/10.5194/egusphere-egu24-14516, 2024.

EGU24-14811 | ECS | Posters on site | HS8.3.2

Predicting phosphorus loss from structured soils through macropores 

Ping Xin, Charles Pesch, Trine Norgaard, Lis Wollesen Wollesen de Jonge, Maarit Mäenpää, Goswin Heckrath, and Bo Vangsø Iversen

Macropore transport is an important process of phosphorus (P) loss from tile-drained agricultural land to surface waters where P inputs may cause accelerated eutrophication. Many laboratory experiments or plot studies have shown that P loss by macropore transport increases with increasing concentrations of mobilizable P in the topsoil. However, operational models that quantify the risk of P losses by macropore transport based on typically available information on soil properties, including P status and soil hydrological properties, are currently lacking.

This study has collated and analyzed comprehensive existing data from standardized column-leaching experiments with 193 topsoils from different locations in Denmark. In addition to general physical and chemical soil properties including soil P pools, water, and P transport were measured on the large undisturbed soil columns. This data has been used to investigate relationships between P loss and soil properties under varying degrees of macropore transport. Specifically, we have used two statistical methods to analyze relationships between variables and to explore predictive models – multiple linear mixed models (MLMM) and structural equation modeling (SEM). The latter technique allows for testing complex causal relationships among observed and latent variables.

Our SEM approach has so far yielded rather poor model fits, and the model structures for estimating the loss of dissolved and particulate P from the columns were characterized by low significance. This was partly due to missing data. In contrast, different MLMM fitted the measured dissolved and particulate P losses satisfactorily. Water-extractable P and saturated hydraulic conductivity were the most important variables for estimating dissolved P losses, while colloid mobilization in soils and tritium leaching breakthrough time explained particulate P losses to a large degree.

Our initial statistical analyses show that P loss in dissolved and particulate form from large columns under macropore runoff scenarios can be reasonably explained by soil properties that are typically mapped in Denmark. This approach could bridge empirical and mechanistic modeling and facilitate mapping the risk of P loss by macropore transport.

How to cite: Xin, P., Pesch, C., Norgaard, T., Wollesen de Jonge, L. W., Mäenpää, M., Heckrath, G., and Vangsø Iversen, B.: Predicting phosphorus loss from structured soils through macropores, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14811, https://doi.org/10.5194/egusphere-egu24-14811, 2024.

EGU24-15146 | ECS | Orals | HS8.3.2

Extraction of recharge in variably saturated subsurface flow models 

Chengcheng Gong, Peter Cook, René Therrien, and Philip Brunner

Variably saturated subsurface flow models have been widely used in the context of water resources management as they conceptualize and simulate water flow in the unsaturated and saturated zone. By solving the Richards equation and using infiltration flux as an input, these models do not require groundwater recharge. As the models simulate the infiltration dynamics through the unsaturated zone, recharge is expected to be reliably extracted from such kinds of models. In this study, we explore to what extent variably saturated subsurface flow models can actually be used to extract groundwater recharge. In this context, we implement numerous definitions of groundwater recharge in a simple, variably saturated 1D model, extract groundwater recharge for a wide range of infiltration and groundwater dynamics imposed through boundary conditions, and assess the reliability of the extracted values. The results show that the value of recharge cannot be uniquely obtained from such kinds of models. The problem is attributed to the storage dynamics in the capillary fringe above the water table. However, it is important to keep in mind that if a variably saturated subsurface flow model of a project area is available, extracting recharge is superfluous as the model is capable of representing all the relevant flux and dynamics.  

Keywords: Variably saturated subsurface flow models; Groundwater recharge; unsaturated zone; Water resources management.

Reference: Gong, Chengcheng, Peter G. Cook, René Therrien, Wenke Wang, and Philip Brunner. "On groundwater recharge in variably saturated subsurface flow models." Water Resources Research 59, no. 9 (2023): e2023WR034920.

How to cite: Gong, C., Cook, P., Therrien, R., and Brunner, P.: Extraction of recharge in variably saturated subsurface flow models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15146, https://doi.org/10.5194/egusphere-egu24-15146, 2024.

EGU24-16238 | Orals | HS8.3.2

Saturated hydraulic conductivity spatialization strategy to model recharge and hydrogeological transfers on an industrial site in France 

Salohy Nantenaina Andriatahiana, Idrissou Sinabarigui, Nathalie Courtois, Jean-Pierre Vandervaere, and Jean-Martial Cohard

Pollutant transfers in the critical zone is an issue for decades both because of complex physico-chemical interactions in the porous media and because of the emergence of new materials/molecules rejected in the environment for which rules are not ready. The study presented here is part of a research project which aimed to predict transfers and residence time of pollutants in the critical zone including the Unsaturated Zone (UZ), and in aquifers on the CEA Cadarache site (France). This site benefits from a large instrumentation for decades to survey both the water dynamic and quality in the aquifers below the industrial facilities. One of the remaining challenges is to study the distributed recharge in the UZ. In situ measurements of saturated hydraulic conductivity Ks are often time-consuming, but also costly to implement at a catchment scale. To overcome this difficulty, an approach using Pedotransfer Functions (PTFs) is possible in order to spatialize this parameter of the UZ (Nasta et al., 2021; Weihermüller et al., 2021). The main objective of the study is to evaluate a spatialization strategy of Ks values using PTFs calibrated from an intensive in situ measurement campaign.

A total of 48 measurement points were selected on the study site, covering an area of around 900 hectares. The points were chosen to represent the different types of geological formations at the outcrop as well as the different types of land cover on the site. For all those locations, in situ hydraulic conductivity measurements were carried out with a disc infiltrometer, using the multi-potential method (Vandervaere, 1995), together with physico-chemical analyses of the surface soils. The results obtained show that for most of the measurement points, a fairly clear break in the slope of the exponential function K(h) appears for potentials h around -30 / -20 mm. The estimate of the value of Ks is chosen as being the value of K(h) obtained for the last value of potential h = - 5 mm, considering that saturation has been reached. On site, Ks varies from 20 to 410 mm/h.

Several PTFs for estimating Ks were selected (Rawls & Brakensiek, 1985, Wösten et al., 1999, Weynants et al., 2009, Szabó et al., 2021, Rosetta (Schaap et al., 2001; Zhang & Schaap, 2017)). The study will help us to identify some geological or land cover drivers for Ks ranges and to select which PTFs are able to represent such a variability.

How to cite: Andriatahiana, S. N., Sinabarigui, I., Courtois, N., Vandervaere, J.-P., and Cohard, J.-M.: Saturated hydraulic conductivity spatialization strategy to model recharge and hydrogeological transfers on an industrial site in France, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16238, https://doi.org/10.5194/egusphere-egu24-16238, 2024.

The modeling of the coupled thermo-hydro-mechanical processes within a soil undergoing freeze-thaw cycles is an increasingly relevant problem in the era of accelerating climate change. One can hope to alleviate and prepare for infrastructure damages due to e.g., frost heave and frost quakes by modeling the interplay of hydrology and soil mechanics and identifying at-risk structures and environmental profiles (i.e. temperature gradient, snow cover, soil water/ice saturation) that make those structures susceptible to said damages.

Our work is focused on developing a linked computational framework for thermo-hydro-mechanical modeling of soils. We achieve this currently by linking the state-of-the-art thermo-hydrological modeling of Amanzi-ATS with the thermo-mechanical modeling capabilities of OpenGeoSys, allowing us to have an accurate understanding of both the intricate hydrology of freezing soils as well as being able to determine the stress and pressure fields within the system. This framework is then to be applied to understand the mechanics and triggering circumstances at the frost quake site at Talvikangas in Oulu, Finland as well as developing a risk-assessment tool for damages to infrastructure and built environment.

How to cite: Remes, J. and Okkonen, J.: Modeling mechanical stress in freezing soils: sub-Arctic infrastructure, built environment and frost quakes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16485, https://doi.org/10.5194/egusphere-egu24-16485, 2024.

EGU24-17257 | ECS | Posters on site | HS8.3.2

Groundwater recharge estimates in agriculturally managed site in Northeast Germany: combining Cosmic ray neutron sensing and soil hydrological modelling 

Lena M. Scheiffele, Katya Dimitrova Petrova, Maik Heistermann, and Sascha E. Oswald

Brandenburg is among the driest regions in Germany, and heavily relies on groundwater resources for both agricultural and drinking water supply. Already suffering from declining groundwater tables, climate change is expected to exacerbate the situation. For a sustainable management of groundwater resources, the rate of groundwater recharge (GWR) is a key variable. Yet, its quantification remains a challenge, as it cannot be measured directly at the field scale

One way to estimate GWR is using vadose zone models to simulate the local water balance and the vertical percolation of water towards the groundwater. Observations of soil moisture (SM) in the root zone can provide a means to calibrate such models so that they can adequately represent the local water balance. However, conventional point-scale SM observations notoriously suffer from a lack of horizontal and vertical representativeness, compromising the validity of the calibration.

In this study, we explore the potential of cosmic-ray neutron sensors (CRNS) to address this issue. CRNS allow for non-invasive SM monitoring of the shallow root zone at the hectare-scale. We use daily CRNS-based soil moisture estimates to calibrate the vadose zone model HYDRUS-1D, and hence to derive daily estimates of the downward water fluxes below the root-zone, as an approximation of GWR.

For this purpose, we explore a unique dataset that was obtained in a research site near Potsdam, Brandenburg, over a period of more than three years. The site features a diversity of agricultural plots, and sits on a gentle hillslope over a glacial till aquifer, with the groundwater table at depths between 1 to 10 m. In an area of around 10 ha, we operated eight CRNS sensors and 27 SM profile probes, complemented by measurements of soil texture and soil hydraulic properties, among others.

In various simulation experiments, we evaluate the added value of using CRNS-based soil moisture estimates for model calibration, as a replacement or as a supplement of conventional profile probes. Based on a calibrated model, we also assess long-term (centennial) changes of GWR.

How to cite: Scheiffele, L. M., Dimitrova Petrova, K., Heistermann, M., and Oswald, S. E.: Groundwater recharge estimates in agriculturally managed site in Northeast Germany: combining Cosmic ray neutron sensing and soil hydrological modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17257, https://doi.org/10.5194/egusphere-egu24-17257, 2024.

EGU24-18554 | ECS | Orals | HS8.3.2

Can 3-D X-Ray tomography imaging improve the estimation of saturated hydraulic conductivity of soils? 

Einar Emil Låker, Attila Nemes, and Daniel Hirmas

Saturated hydraulic conductivity (Ksat) is one of the most fundamental parameters in soil hydrology. It governs the rate of saturated flow through porous media and functions as a scaling factor for unsaturated flow. Knowledge of Ksat is key to understanding the movement of water in soils, transport and recharge of groundwater, suspended and dissolved transport in soils, and soil-air water exchange. In hydrology and climate modeling Ksat is often estimated through pedotransfer functions. A large effort has been committed to the development of these models, using an array of differing algorithms and methods. However, estimating Ksat has been somewhat troublesome, since the commonly measured soil properties, such as soil texture, bulk density and organic matter content, used as predictor variables in PTFs do not explain Ksat variation well. Instead, Ksat is largely controlled by pore-network characteristics especially in highly-structured soils. Using an extended, methodologically homogeneous dataset of commonly measured soil physical properties, 3-D X-ray computed tomography imaged pore-network parameters, and quasi-continuous particle-size measurements using the Integral Suspension Pressure method, we assess the benefits of using combined soil textural and structural information on the estimation of Ksat. Using this dataset, we have built models that estimate Ksat using a boosted random forest algorithm (XGboost) and used explanatory model analysis to tune and evaluate the models. Three input data scenarios included (i) basic soil inputs only (ii) imaged pore metrics only, and (iii) their combination. Using or adding imaged pore metrics as inputs greatly improved the Ksat estimations that were reflected, for example, by the respective coefficients of determination, evaluated using a cross-validation scheme (R2 = -0.05/0.60/0.58 for the three input scenarios respectively). 3-D imaging of soil and the subsequent characterization of its pore-space may serve multiple research purposes, but such data are still not routinely collected due to cost of measurement and general lack of access to equipment. Our study confirms, however, that when collecting such metrics will become economically feasible through e.g. better automation of image processing using tools like SoilJ, having those metrics will show great potential towards improving the estimation of the soil’s water transport properties. 

How to cite: Låker, E. E., Nemes, A., and Hirmas, D.: Can 3-D X-Ray tomography imaging improve the estimation of saturated hydraulic conductivity of soils?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18554, https://doi.org/10.5194/egusphere-egu24-18554, 2024.

Soil moisture is an important state variable with high spatiotemporal variability depending on land and climate variables. The importance of various physical controls on soil moisture varies depending on the scale and extent of the study. At a fine scale, soil properties are proven to be critical in defining spatiotemporal variability of soil moisture. In the context of agricultural applications in India, soil moisture estimates at the farm scale (finer spatial resolution) over various root depths are essential.  Traditional Land Surface Models (LSMs) are limited to large spatial scales (in the order of tens of kilometers). They have been designed for synergistic coupling with Earth system models. Besides, they do not account for the vertical heterogeneity of soil. LSMs, including Noah-MP, use a lookup table to obtain soil properties corresponding to soil texture while assuming vertically homogeneous soil texture. Recent studies proved that accounting for vertical heterogeneity in the soil using state-of-art soil maps and pedotransfer functions in LSM can significantly improve the surface soil moisture estimations. However, the effects of incorporating vertical heterogeneity in soil properties on deeper layer soil moisture simulations are yet to be explored. Considering the importance of farm scale root water uptake processes, understanding soil moisture heterogeneity at deeper layers is essential. In this context, the present study hypothesizes that a hyperresolution LSM, which accounts for subgrid spatial heterogeneity while maintaining soil heterogeneity between layers, can improve the characterization of rootzone soil moisture. 

In this work, we used HydroBlocks, a semi-distributed hyper-resolution LSM, which uses Noah-MP at its core, and the concept of Hydrologic Response Units (HRU) to simulate the land surface variables. The analysis is carried out for the first time in India over the Upper Bhima Basin, for the year 2020. Initially, we investigated the benefit of vertical heterogeneity in soil properties to simulate soil moisture at five different layers till one meter deep using HydroBlocks. We used SoilGrids data for different layers to calculate soil hydraulic properties using PTFs and feed them as inputs in the HydroBlocks model. We compare HydroBlocks surface and rootzone soil moisture to existing reanalysis and satellite products, including GLEAM, ERA5-Land, SMAP-L3, and SMAP L4 statistically in terms of bias, ubRMSE and R2. Further, an intercomparison of surface and rootzone soil moisture simulations is made between the two cases of Hydroblocks model, first with vertically homogeneous soil properties, and second, with vertically heterogeneous soil properties. The objective of this step is to emphasize the role of vertically heterogeneous soil layers in a hyper-resolution LSM towards addressing the spatiotemporal variability of soil moisture. Finally, a soil parameter sensitivity analysis (using Sobol technique) is carried out using HydroBlocks for five soil layers (up to 1 meter depth), for the first time, to assess the influence of eight soil textural parameters such as wilting point, porosity, pose size distribution, and likewise, on soil moisture simulations. In this process, we also assessed the seasonal variability of parameter sensitivity.

How to cite: U Krishnan, V., Vergopolan, N., Jayaluxmi, I., and Lanka, K.: Examining the benefits and sensitivity of vertically heterogeneous hyper resolution land surface model towards simulating a farm scale soil moisture profile in Upper Bhima Basin, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18945, https://doi.org/10.5194/egusphere-egu24-18945, 2024.

EGU24-19388 | ECS | Posters on site | HS8.3.2

Modeling the impact of stone content on the shape of water retention curve 

Anne Doat, Caroline Vincke, and Mathieu Javaux

Heterogeneous soils with stone fractions are very common in non-agricultural areas. The characterization of their hydraulic properties is important but face technical challenges. Therefore, the retention of the stony fraction (larger than 2 mm) is often considered as null. However, when soil stone content is large (>15%), even a slight change of water with suction in the stone fraction will affect the shape of the bulk soil retention curve.

In this study, we analyzed the retention data, between pF 0 and pF 4.2, of more than 2400 aggregates extracted from 48 soil horizons in forests down to 2-m depth. For each horizon, at each suction level, we characterized water content and stone content of at least 8 replicates of aggregates. We propose a novel methodology to extract and separate the hydraulic properties of the stony and of the fine fractions from these data. It proved to be efficient beyond 15% of stone content.

In general, the change of volumetric water content between pF 2 and pF 4.2 was below 5% for stones but for some of them, it could reach up to 15%.  In addition, we could propose a general expression of the bulk retention curve that explicitly contains the fraction of stones. It is observed that the shape of the bulk retention curve (mono or bimodal) evolves with stone content for a given horizon.

How to cite: Doat, A., Vincke, C., and Javaux, M.: Modeling the impact of stone content on the shape of water retention curve, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19388, https://doi.org/10.5194/egusphere-egu24-19388, 2024.

EGU24-19703 | Orals | HS8.3.2

Infiltration as dynamic non-uniform stochastic flow field – repeatable, high-resolution 4D GPR measurements at the plot scale 

Conrad Jackisch, Sophie Marie Stephan, Jens Tronicke, and Niklas Allroggen

Infiltration is a central concern in soil physics. The advective and diffusive redistribution of event water depends on various factors such as initial wetting, the establishment of film connectivity, and capillary gradients and hydraulic conductivity. Non-uniform infiltration patterns are prevalent. However, direct infiltration measurements do not account for this reality and tracer experiments require a destruction of the experimental plot. We developed a data acquisition strategy based on time-lapse 3D ground-penetrating radar (GPR) to monitor fast and small-scale subsurface flow processes during irrigation in a non-invasive manner.

The technique combines an irrigation pad (1 m2 drip irrigation to simulate moderate, non-erosive rain events) with a GPR measurement platform (manually driven two-channel GPR antenna array with positioning guides). We will present a systematic field experiment consisting of two recurrent irrigations (40 mm/2 h, 1 irrigation per day) and a respective replicate. For evaluation, the GPR measurements were sidelined with soil moisture measurements (TDR profile) and tracer applications (dye and salt). Our data show that the achieved high resolution of less than 5 cm in space and 10 minutes in time makes it possible to monitor and quantify infiltration processes in their spatial and temporal non-uniformity.

The experiment supports the hypothesis from earlier experiments at various sites: Non-uniform infiltration patterns and dynamically connected flow-fields are highly heterogeneous but share stochastic features, such as distribution, randomness, and skewness. Our approach opens new options for repeated, spatially resolved infiltration measurements and theory development for soil hydrology and land surface models.

How to cite: Jackisch, C., Stephan, S. M., Tronicke, J., and Allroggen, N.: Infiltration as dynamic non-uniform stochastic flow field – repeatable, high-resolution 4D GPR measurements at the plot scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19703, https://doi.org/10.5194/egusphere-egu24-19703, 2024.

EGU24-19745 | ECS | Posters on site | HS8.3.2

pySWAP: Python wrapper for SWAP hydrological model 

Mateusz Zawadzki

The Soil-Water-Atmosphere-Plant (SWAP) model has been continuously developed since 1974 and has gained a community of users. The need for clearer and more reproducible model development and interpretation drove the development of wrapper packages in R, such as SWAPTools and RSWAP. Due to the steady increase in the community of Python users, it became important to provide similar interface tools written in Python. This work introduces the pySWAP Python package, developed as a wrapper for the SWAP model.

A key feature of pySWAP is its user-friendly, object-oriented design. Users provide the essential model setup, for example, in the form of a Jupyter notebook, and the package creates the input files while preemptively checking for errors. This ensures a smooth setup and execution process, significantly reducing common user errors and streamlining the model setup. This is especially beneficial for those new to SWAP, who can easily access documentation through their Integrated Development Environments (IDEs). The package also runs the model, captures the results, and provides tools for simple data visualization.

pySWAP also aims to optimize work with multiple scenarios and the parameter estimation process. This is achieved through the integration of a SQLite database, which stores data from intermediate simulations. This method not only reduces file storage requirements but also enhances the efficiency of data retrieval and manipulation during and after simulation runs. The use of open-source SQLite is also beneficial for sharing models between users, as it can efficiently store input and output data of multiple models in a single file, accessible on all operating systems. Furthermore, we are in the process of developing a Dockerized version of PySWAP, which may further improve collaboration on models and allow users to effortlessly deploy and execute simulations developed on local machines on supercomputers.

As a proof-of-concept, we use pySWAP in the Grow project to develop a SWAP model for a pilot site in Kinrooi, East Belgium, where treated wastewater is reused through a subirrigation system.

How to cite: Zawadzki, M.: pySWAP: Python wrapper for SWAP hydrological model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19745, https://doi.org/10.5194/egusphere-egu24-19745, 2024.

Hydraulic Conductivity and Water Retention Functions of Porous Rock and Glacial Till Soil: Quasi-Steady Centrifuge versus Evaporation Methods

Maria Clementina Caputo1, Lorenzo De Carlo1, Antonietta Celeste Turturro1, Horst Herbert Gerke2

1CNR National Research Council, IRSA Water Research Institute, via Francesco De Blasio 5, 70132 Bari, Italy

2Research Area 1 “Landscape Functioning”, Leibniz-Centre for Agricultural Landscape Research (ZALF), Eberswalder Straße 84, D-15374 Müncheberg, Germany

 

 

Experimental laboratory measurements of the hydraulic conductivity and the water retention functions have a crucial role in describing the solid matrix-water dynamics. However, the direct determination of the hydraulic conductivity, K, as a function of the pressure head, h, is still difficult.  It is often estimated indirectly from the water retention curve, which relates the water content, θ, to h, or obtained by using pedotransfer functions or by field data of  pumping tests.

In this study the unsaturated hydraulic conductivity values of carbonate porous rocks and soil clods were measured by means of evaporation, Quasi-Steady Centrifuge (QSC) and double-membrane steady-through flow methods. Water retention curves were obtained by using the evaporation, QSC, suction table, Mercury Intrusion Porosimetry (MIP) and pressure chambers methods. Samples belonging to two rock lithotypes collected in southern Italy and to two soil clods coming from northeastern Germany were tested. The data were fitted to the unimodal and bimodal functions of van Genuchten and the Peters-Durner-Iden models by using the LABROS SoilView Analysis software. The bimodal functions better described the experimental data of both the studied rocks and soils.

The soil compaction during the centrifuge runs performed by applying the QSC method, corroborated by changed values of bulk density, porosity, tortuosity, and pore connectivity after the runs, confirms that this method is not suitable to non-rigid media.

The results confirm that the QSC method allows measuring the unsaturated hydraulic conductivity values for rock samples. The larger range of experimental hydraulic conductivity values helps to improve the fitting and obtain the more accurate of the hydraulic conductivity function to better describe the unsaturated rock-soil-water dynamics.

How to cite: Caputo, M. C.: Hydraulic Conductivity and Water Retention Functions of Porous Rock and Glacial Till Soil: Quasi-Steady Centrifuge versus Evaporation Methods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20473, https://doi.org/10.5194/egusphere-egu24-20473, 2024.

EGU24-20755 | Posters on site | HS8.3.2

An Integrated Approach for Estimation and Uncertainty Analysis of Soil Pore Electrical Conductivity 

Jose A Sanchez-Espigares, Basem Aljoumani, and Birgit Kleinschmit

This study proposes an integrated methodology to advance the estimation and uncertainty analysis of soil pore electrical conductivity. Drawing on previous work from Aljoumani et al. (2015), where modifications were made to the Hilhorst model, and subsequent enhancements in Aljoumani et al. (2018), this research unfolds in a systematic manner.

Commencing with a comprehensive examination of critical data from the Aljoumani el al.(2015) study, including bulk electrical conductivity, soil permittivity, and pore water permittivity, we transition into the construction of an improved Hilhorst model. This advanced model convert the deterministic Hilhorst model to stochastic model incorporates linear dynamic modeling and the Kalman filter, enabling precise estimation of soil salinity (pore electrical conductivity) and determination of corresponding offsets.

To address uncertainty comprehensively, we employ a multifaceted strategy. Beginning with the modeling of relationships using the Long Short-Term Memory (LSTM) algorithm, an artificial recurrent neural network, we intricately examine the interplay between the original time series of soil permittivity, pore water permittivity, and bulk electrical conductivity.

Subsequently, we utilize bootstrapping to generate 1000 series for soil permittivity and pore water permittivity. The LSTM model then produces 1000 series of bulk electrical conductivity, using the generated soil and pore water permittivity series as input.

Applying the modified Hilhorst model to the 1000 series obtained from bootstrapping and the LSTM model, we obtain 1000 models, each providing 1000 offsets and predicted pore water electrical conductivity series. Returning to the original data, the modified model is applied to construct predicted series of pore electrical conductivity. Upper and lower bounds are established using the calculated 5th and 95th percentiles of the 1000 offset values from the generated data.

In summary, this integrated methodology not only ensures accurate estimations of soil pore electrical conductivity but also provides a robust framework for quantifying uncertainty comprehensively.

How to cite: Sanchez-Espigares, J. A., Aljoumani, B., and Kleinschmit, B.: An Integrated Approach for Estimation and Uncertainty Analysis of Soil Pore Electrical Conductivity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20755, https://doi.org/10.5194/egusphere-egu24-20755, 2024.

EGU24-21584 | ECS | Orals | HS8.3.2

Design of a spatially differentiated water balance modelling tool 

Frederik Graaf, Michael Bock, Olaf Conrad, and Robin Sur

Existing water balance assessments may lack precision due to overlooking the spatial variations in factors such as soil and topography while transferring the results from point modelling to a wider area. In cooperation with Bayer AG Crop Science Division and Hamburg University, within the DREAM (Digital Run-off Exposure Assessment and Management) project, a model is being developed which is temporally dynamic as well as spatially differentiated to provide a more nuanced and location-specific understanding of quantitative water dynamics. It is based on high resolution grid data and features a multi-layered soil water model, the goal of which is to depict volumes of water in different soil layers. It is to be employed in an agricultural context and serve as a toolbox of possible runoff reduction measures for plant protection products.

Since risk management is a highly localized undertaking, the model operates at a field- or sub-field-level with a spatial resolution of up to one meter. The temporal resolution of simulation steps is variable; from one hour to a day. The necessary input data – that being a digital terrain model, information about the vegetation as well as soil and weather data – create conditions specific to the site.

It is embedded in the open source geoinformation system (GIS) SAGA. The modular approach allows for flexible development and changes on short notice. The model includes an algorithm that determines soil water movement, incorporating the groundwater layer as the model’s lower boundary. To achieve this, an expanded bucket model for soil water movement, based on the works of Glugla, is used. Should the infiltration capacity of the soil - calculated via the Green-Ampt-Method - be surpassed, runoff occurs. In this case, the model possesses the ability to depict runoff and its flow paths through the terrain, along with the respective volumes and flow velocity based on Gauckler-Manning-Strickler.

While the current focus lies on the movement of water, the model is designed for gradual expansion and improvement, allowing for future considerations such as the tracking of solutes moving into larger depths or even into groundwater.

How to cite: Graaf, F., Bock, M., Conrad, O., and Sur, R.: Design of a spatially differentiated water balance modelling tool, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21584, https://doi.org/10.5194/egusphere-egu24-21584, 2024.

EGU24-22326 | Orals | HS8.3.2

Soil management using lignite to improve soil cracking properties and performance 

Nima Baghbani, Franziska Bucka, and Thomas Baumgartl

Incorporating Victorian brown coal (VBC) into the soil as a reliable amendment can markedly alter the hydraulic properties of the soil. A pivotal phenomenon influencing soil hydraulic parameters, particularly the soil permeability coefficient, is the extent of cracking and shrinkage observed during the drying process and consequent moisture loss. This study investigates the impact of incorporating VBC into clay and its influence on the two-dimensional cracking and shrinkage characteristics of the mixture. Various mixtures of brown coal from Latrobe valley in Victoria, Australia and clay, ranging from 2% to 20% brown coal content, were prepared and subjected to liquid limit and plastic limit tests. The samples were then readied for cracking and shrinkage assessments under liquid limit moisture conditions as an initial moisture content, featuring a sample diameter of 150 mm and a thickness of 10 mm. Results from the liquid limit tests demonstrated a decreasing trend in the liquid limit of the mixture with increasing brown coal content, registering values of 38.3%, 37.4%, 36.5%, 34.9%, and 32.9% for 0%, 2%, 5%, 10%, and 20% brown coal mixtures, respectively. Plastic limit tests indicated a 1.7% reduction, decreasing from 20.6% to 18%.9, with the addition of 20% brown coal. Furthermore, cracking and shrinkage tests revealed a substantial reduction in the cracking index (cracking intensity factor, CIF) of the mixture upon the addition of brown coal, reaching zero for mixtures containing 5%, 10%, and 20% brown coal after exposure to a 45℃ temperature for 30 hours. Additionally, the shrinkage index (shrinkage intensity factor, SIF) decreased from 15.4% for the clay soil sample to 14.9%, 14.6%, 13.9%, and 13.1% for the 2%, 5%, 10%, and 20% brown coal mixtures, respectively. This underscores the positive influence of brown coal on mitigating soil cracking and shrinkage, emphasizing its significance in soil science research.

How to cite: Baghbani, N., Bucka, F., and Baumgartl, T.: Soil management using lignite to improve soil cracking properties and performance, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22326, https://doi.org/10.5194/egusphere-egu24-22326, 2024.

EGU24-692 | ECS | Orals | HS8.3.7

Field quantification of the water productivity of a peach orchard within an arid climate zone. 

Ines Toumi, Mohamed Ghrab, Olfa Zarrouk, and Kamel Nagaz

Irrigation management is the key to improving water productivity in fruit orchards growing under marginal conditions in dry areas where the water for irrigation is significantly decreasing. The aim of this work was to determine the yield response to variable water supply of an early maturing peach orchard and to assess the water productivity in an environment where the water is extremely scarce. Field experiments were carried out on peach trees for a private farm in south of Tunisia for two relevant period (2010/2011 and 2013/2015), in an area with sandy soil, hot summer and mild winter conditions.  Old trees were irrigated with different irrigation strategies 100%, 60%, 50%, 40% and 20% of the estimated ETc. In the first experimental period, Flordasar peach trees were subjected to DI40, DI60 and DI20 and gave a variable yields ranged between 23-30 Kg tree-1. The highest WP values were obtained for DI60 et DI40, respectively 4.26 and 3.63 kg m-3. However, experimental work in peach trees under DI50 with two irrigation strategies, average water productivity varied between 2.21-2.24 and 2.81-3.14 kg m-3 respectively when yields was increased from 25.5 to 34.1 Kg tree-1. The yield reductions under low to severe water defcits accompanied by gains in WP may be justifable in the light of anticipated water restriction.

How to cite: Toumi, I., Ghrab, M., Zarrouk, O., and Nagaz, K.: Field quantification of the water productivity of a peach orchard within an arid climate zone., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-692, https://doi.org/10.5194/egusphere-egu24-692, 2024.

EGU24-1726 | ECS | Orals | HS8.3.7

Benefits of increasing soil organic carbon to reduce drought stress in maize under climate change 

Maria Eliza Turek, Annelie Holzkämper, and Attila Nemes

Increasing frequencies and intensities of drought periods are likely to aggravate conflicts between agricultural demands and other human and ecological demands for water resources. Improving the natural soil water retention capacity can help to defuse these conflicts and at the same time strengthen climate mitigation, biodiversity, and food security. Increasing soil organic carbon content (SOC) is seen as a promising negative emission technology for the agricultural sector, with the co-benefit of potentially increasing the soil water retention capacity. We tested how different levels of SOC at varying soil depths influence in the transpiration reduction caused by drought stress (Treddry) in maize under current and future climatic conditions. We used the SWAP (Soil Water Atmosphere Plant) model validated utilizing information from a long-term lysimeter for a typical Swiss soil and applied it at three distinct climatic regions. A pedotransfer function (PTF) was used to indirectly assess the effects of SOC on soil hydraulic properties that affected the drought stress. Study findings revealed that increasing SOC down to 65 cm depth is beneficial to reduce drought limitations in maize. These benefits are minimal if SOC is only increased in the top 25 cm but become considerable if SOC is increased down to 65 or 135 cm depth. With a 2% addition of SOC down to 65 cm depth, a considerable average transpiration gain of 40 mm can be reached. It appears that a greater or deeper SOC addition would not return substantial extra benefits in terms of offsetting more crop drought stress rooting in the changing climate.

How to cite: Turek, M. E., Holzkämper, A., and Nemes, A.: Benefits of increasing soil organic carbon to reduce drought stress in maize under climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1726, https://doi.org/10.5194/egusphere-egu24-1726, 2024.

EGU24-2081 | ECS | Orals | HS8.3.7 | Highlight

Exploring the possibilities to reduce irrigation demands through adaptations in soil and crop management 

Malve Heinz, Maria Eliza Turek, Annelie Holzkämper, Bettina Schaefli, and Christoph Raible

In Central Europe, increasing temperatures and declining summer precipitation intensify the water and heat stress on crops and reduce water availability for irrigation from rivers and groundwater. Thus, approaches that reduce the need for irrigation are required. In this study, we quantify the potential of soil and crop management adaptations to reduce irrigation deficits for a mid-sized rainfed catchment in Switzerland. The Broye catchment, comprising 68 % agricultural land with a notable portion dedicated to irrigated agriculture, faces frequent summer irrigation bans. We employ the field-scale agro-hydrological model (SWAP) aiming to 1) quantify irrigation demand at the catchment scale, 2) assess the impacts of temporary irrigation bans on irrigation deficits, and 3) explore the potential of soil and crop management adaptations to reduce these irrigation deficits. SWAP simulates horizontal solute, heat and water flow in the vadose zone and crop growth at a daily timestep. The model calibration process involves a comprehensive global sensitivity analysis and parameter optimization. The optimization aims to maximize the model's fit to reference data on crop yield and seasonal irrigation amounts from the study region. Spatial climate, land use, and soil input data enable the quantification of irrigation water demand on the catchment scale. We simulated the exceptionally hot and dry summer of 2022, revealing a 57 % deficit in water supply and again emphasizing the importance of reducing reliance on irrigation. We further evaluate the effectiveness of measures such as increased soil organic carbon content and planting earlier maturing crop varieties in reducing irrigation demand. Our findings provide valuable insights for sustainable water management in midsized rainfed catchments, particularly in the face of climate change and evolving water use conflicts. As a next step, we plan to couple the field-scale model with a catchment-scale rainfall-runoff model to evaluate the effects of implementing such measures on the catchment's water balance.

How to cite: Heinz, M., Turek, M. E., Holzkämper, A., Schaefli, B., and Raible, C.: Exploring the possibilities to reduce irrigation demands through adaptations in soil and crop management, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2081, https://doi.org/10.5194/egusphere-egu24-2081, 2024.

EGU24-2190 | ECS | Orals | HS8.3.7

Field and numerical experiments of subsurface drainage systems in saline and clay interlayered fields in arid regions 

Chenyao Guo, Chenzhi Yao, Jingwei Wu, Shuai Qin, and Haoyu Yang

A reasonable layout of subsurface drainage systems is considered essential for maximizing its drainage and salt control effectiveness. In the saline-alkali farmland of arid regions in Northwest China, clay interlayers are common; however, the influence of clay interlayers on the layout of the subsurface drainage has not been extensively considered in the literature. This study investigated the process of subsurface drainage and salt discharge in salt-affected fields with clay layers using field experiments and numerical simulations. Four field experiments were conducted, considering three different relative positions between the drainage pipes and clay interlayers. The results showed that the clay interlayers hindered water infiltration; however, the distribution of soil salinity in the soil profile varied with the buried depth of drainage pipes at different positions relative to the clay layer. When the buried depth of drainage pipes increased, the amount of water and salt discharged from drainage pipes increased, and the increase rate in salt discharge was greater than water drainage. A numerical model was calibrated and validated using the field experiment data, and 25 orthogonal numerical experiments were conducted to investigate the soil desalination effects of buried depth of drainage pipes, spacing between the pipes, permeability of the interlayer, and position of the clay interlayer. The results showed that the drainage pipe buried depth, spacing, and permeability of the clay layer had significant effects on the desalination rate (P < 0.01), while the position of the clay interlayer had no significant effect (P > 0.05). Therefore, subsurface drainage pipes should be placed below the clay interlayer. The desalination rate linearly increased with the buried depth of drainage pipe and permeability of the interlayer, and it increased exponentially with decreased spacing. An empirical formula for soil desalination rate considering interlayer and subsurface drainage pipe layout parameters was fabricated and used to determine the appropriate layout parameters.

How to cite: Guo, C., Yao, C., Wu, J., Qin, S., and Yang, H.: Field and numerical experiments of subsurface drainage systems in saline and clay interlayered fields in arid regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2190, https://doi.org/10.5194/egusphere-egu24-2190, 2024.

EGU24-3837 | ECS | Posters on site | HS8.3.7 | Highlight

Exploring climate-adaptive drainage in water management: Enhancing soil moisture, crop resilience and groundwater recharge. 

Erika Lucía Rodríguez Lache, Guillaume Blanchy, Ali Mehmandoostkotlar, and Sarah Garré

Drainage systems are essential for cultivated fields, ensuring optimal growth conditions for crops by preventing root zone wet stress. However, these conventional drainage systems also lead to a significant loss of water, a valuable resource that could be used to sustain crops during dry (summer) months. To address this, climate adaptive drainage or controlled drainage is employed, raising the water table “when possible given the ongoing agricultural activities”. This approach enhances aquifer recharge and stores excess water for use during the summer. Nevertheless, it remains unclear for farmers and water managers whether climate-adaptive drainage will improve agricultural performance and, if so, how to precisely manage water levels throughout the growing season to optimize performance. 

In this study, we conduct a synthetic experiment using the SWAP model to investigate the complex interaction between drainage types under different meteorological conditions, soil characteristics, and crop types. Our research aims to provide insights into the effect of climate-adaptive drainage for both farmers and water managers.

Our findings highlight that controlled drainage significantly enhances soil water content in sandy and loamy soils, contributing to climate resilience. However, its effectiveness in clay soils is small. It is important to note that climate-adaptive drainage has the potential to raise groundwater levels across all soil types, posing a potential risk of oxygen stress on crops. Regardless of soil type, the implementation of controlled drainage results in increased surface runoff and groundwater recharge, associated with a reduction in drainage flux. While the augmented surface runoff  poses potential issues such as soil erosion and water pollution, the positive aspect lies in the enhanced groundwater recharge, crucial for maintaining water availability and supporting ecological systems.

How to cite: Rodríguez Lache, E. L., Blanchy, G., Mehmandoostkotlar, A., and Garré, S.: Exploring climate-adaptive drainage in water management: Enhancing soil moisture, crop resilience and groundwater recharge., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3837, https://doi.org/10.5194/egusphere-egu24-3837, 2024.

EGU24-6546 | ECS | Posters on site | HS8.3.7

The effect of land use types and climate change on soil moisture profile dynamics 

Mengqi Wu, Tobias Klauder, Mika Tarkka, Doris Vetterlein, and Steffen Schlüter

Soil moisture, as a key indicator of soil functionality, is significantly influenced by the evolution of soil-plant systems and the hydrologic cycle. Little long-term data is available about how land use and climate change affect the spatial and temporal distribution of soil water. In particular the variations in deeper subsoil layers are poorly documented. Here, the effects of five land use types, including two croplands with conventional and organic farming (CF and OF) and three grasslands with intensive and extensive meadow (IM and EM), as well as extensive pasture (EP) on soil moisture profiles were investigated at the Global Change Experimental Facility (GCEF), at Bad Lauchstädt in the German dryland belt. The facility harbors two climate treatments. The ambient climate and a future climate with increased temperature by ~0.55 C across seasons, and the altered precipitation patterns by ~9 % additional irrigation in spring and autumn, and ~21 % reduction in summer. The soil moisture profiles were bi-weekly monitored with a portable probe (TRIME Pico IPH) down to 110 cm for two continuous years.

Soil moisture content in topsoil and subsoil reflected the presence and size of transpiring plants, i.e. from October to next April, the soil water content was lower in grasslands than in croplands, which planted winter crops. During summer, there was a marked decrease in soil water content in the deeper soil layers of grasslands, while the crop on the cropland was already harvested. As a result, the recovery of soil water storage was faster during winter in croplands than in grasslands. Within croplands, OF had higher moisture than CF below 30 cm during the whole growing season and beyond due to less vigorous growth imposed by nutrient deficits. Within grasslands, differences in soil moisture only emerged in deeper soil (> 70 cm). In general, soil moisture in the shallow soil layers (0 - 20 cm) was very similar across land uses and climate scenarios and these clear differences only emerged in deeper soil. In the deeper soil (< 50 cm), croplands and extensively used grasslands showed an obvious increase of soil moisture in future treatment, especially during wet spring and summer.

Our results clearly indicate long-term differences in soil moisture between the land uses. Climate manipulation at the GCEF only manifests itself in the subsoil (> 50 cm), by contrast, topsoil (< 30 cm) was more controlled by short-term dynamics induced by evaporation and precipitation. These findings stress the importance of deep soil moisture monitoring for a more comprehensive assessment of the water budget. 

How to cite: Wu, M., Klauder, T., Tarkka, M., Vetterlein, D., and Schlüter, S.: The effect of land use types and climate change on soil moisture profile dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6546, https://doi.org/10.5194/egusphere-egu24-6546, 2024.

EGU24-6804 | ECS | Posters on site | HS8.3.7 | Highlight

Groundwater Recharge in Pecan Orchards Under Different Irrigation Systems to Reduce the Impacts of Climate Change in the Southwest USA 

Jorge Preciado, Alexander Fernald, and Richard Heerema

Water balance is important to provide information and to conserve water. The flow of water in the system can be used to help and manage water supply, changes in management can increase water productivity in arid regions. For this study, soil water content was measured from one soil column within the orchards using time-domain reflectometry probes installed at different depths in the root zone of pecan fields. This data was analyzed to compare the irrigation systems. Water that passes the root zone was considered deep percolation. This research compared the amount of water stored on each field and water consumed by the trees for the last four irrigation seasons 2020 - 2023. Quantifying water from irrigation was essential to know how much water would recharge the Mesilla basin. Percolation was higher in the flood section, with 52 % of the total water applied, while in the drip, percolation was less than 5% of the total water applied moving down in the field for the 2021 growing season. In addition, there were differences in crop yield between the irrigation systems. This study estimated recharge and modeled water flow through the soil in drip and flood-irrigated pecan orchards to understand better surface water and groundwater interactions for improved river basin water management strategies and quantifies water stored in the ground lost through evapotranspiration. In addition, this project evaluates which irrigation scenario could best grow sustainable pecans in arid regions, reducing water use while maintaining crop production. It presents a balance of the two irrigation systems to understand the implications of climate change on the water cycle and achieve sustainability in the crops grown in the area.

How to cite: Preciado, J., Fernald, A., and Heerema, R.: Groundwater Recharge in Pecan Orchards Under Different Irrigation Systems to Reduce the Impacts of Climate Change in the Southwest USA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6804, https://doi.org/10.5194/egusphere-egu24-6804, 2024.

EGU24-6964 | ECS | Orals | HS8.3.7

Surface Fertigation Practices for Smallholder Farmers in the North China Plain 

Xiulu Sun, Henk Ritzema, Jos van Dam, and Petra Hellegers

The North China Plain (NCP) stands as a densely populated region vital for agriculture, sustaining a large population through intensive farming practices. However, the reliance on irrigation and fertilization in the region has led to inefficiencies in water and nutrient use, compromising the sustainability of agriculture and contributing to environmental degradation. To address these challenges, the focus of this study is on optimizing water and fertilizer management, particularly through surface fertigation. This method involves applying fertilizers dissolved in irrigation water to enhance water use efficiency (WUE) and nitrogen use efficiency (NUE). Each section explores different facets of surface fertigation, aiming to improve the uniformity of fertilizer distribution in irrigation water, subsequently enhancing crop yields while reducing water and fertilizer leaching.

A participatory study in the People's Victory Canal Irrigation District revealed farmers' satisfaction with current practices but identified obstacles to adopting more efficient technologies. Challenges included a lack of knowledge about advanced fertigation systems, constraints of small-scale farming, and high implementation costs. Tailored guidelines grounded in empirical evidence and considering socio-economic factors are crucial for overcoming these challenges. An experimental approach in subsequent sections evaluated surface fertigation practices tailored to NCP farmers' fields. Traditional methods showed low field application efficiency and uneven distribution of water and fertilizers. The WinSRFR model aided in understanding these practices, leading to proposed methods for enhancing application efficiency and distribution uniformity. Optimal irrigation depths for wheat and maize were identified to be 95 mm and 80 mm, respectively. Continuing with field experiments and modeling, the study analyzed the impact of irrigation and fertigation practices on crop yield, WUE, NUE, and nitrogen loss. The findings emphasized the need for integrating optimized irrigation and fertigation strategies for sustainable crop production and minimized nitrogen loss. The viability of transitioning smallholder farmers in the NCP to organic fertilizer application through surface fertigation was explored. A 50% organic fertilizer ratio was found to balance maintaining crop yield and minimizing nitrogen leaching. The study advocated for compensation to offset additional costs for farmers adopting organic fertilizers.

In conclusion, the study highlights inefficiencies in current irrigation and fertilization practices in the NCP and suggests surface fertigation as a promising solution. Refining practices, such as adjusting irrigation depth and fertigation scheduling, can significantly enhance WUE, NUE, and mitigate environmental impacts. The research underscores the importance of tailoring solutions to local conditions and farmer preferences, emphasizing the need for government support and incentives to facilitate the adoption of sustainable practices. The research methodology reflects a commitment to evidence-based approaches, utilizing participatory tools, field experiments, and simulation models to assess and refine fertigation strategies. Looking ahead, successful implementation of improved practices relies on understanding and engaging with the local farming community, addressing their concerns, enhancing their knowledge, and providing cost-effective solutions. The research suggests a pathway towards sustainable agriculture in the NCP, emphasizing the need for a comprehensive approach considering both environmental and socio-economic factors.

How to cite: Sun, X., Ritzema, H., van Dam, J., and Hellegers, P.: Surface Fertigation Practices for Smallholder Farmers in the North China Plain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6964, https://doi.org/10.5194/egusphere-egu24-6964, 2024.

Abstract: The Hetao Irrigation District (HID) is located in the arid region along the upper reach of the Yellow River and is an important grain production area in northwest China. Water diverted from the Yellow River is an indispensable water supply of the crop production in this region. Unfortunately, traditional irrigation, drainage and fertilization practices have resulted in severe soil salinization and inefficient of water use, which poses a great challenge to food security and water resources. Therefore, it is important to search a new practice that can achieve water saving, salinity control, and yield increase simultaneously. To this end, this study applied a framework that combined the SWAP model and a multi-criteria decision-making method.

First, we used a total of 21 station-years of experimental data from 12 spring wheat and spring maize sites for parameter calibration by the PEST package. The sensitive parameters of spring wheat and spring maize were obtained, and the evaluation showed that the SWAP model is capable of simulating seasonal variations of leaf area index, evapotranspiration, soil moisture and soil salt content. Specially, we showed that the parameters SALTMAX (threshold salt concentration in soil water) and TSUMEA (temperature sum from emergence to anthesis) were obviously different from the default values of wheat and maize in the SWAP.

Second, we designed simulation scenarios based on the combinations of irrigation, drainage and fertilization practices, constrained by the local customs and water supply from the Yellow River. The simulated crop yield, water use efficiency (i.e., the crop production per irrigation water amount), and soil salt content change were obtained by the SWAP model.

Finally, based on the SWAP-simulated results, optimal practices were obtained with the help of the VIKOR method, a multi-criteria decision-making method which has the advantage of objectively determining the weights of water use efficiency, crop yield, and soil salt content change. Compared with the traditional practices by farmers, the optimal practice can not only increase crop yield by 20 per cent and improve water use efficiency by more than 10 per cent, but also ensure the soil salt content does not increase.

 

Keywords: Irrigation; Drainage; Fertilization; SWAP model; VIKOR method

How to cite: Duan, S. and Lei, H.: Searching for optimal practices for water saving, salinity control and yield increase in an arid and salinity irrigated area of China using the SWAP-based method., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7726, https://doi.org/10.5194/egusphere-egu24-7726, 2024.

EGU24-8199 | Posters on site | HS8.3.7

Comparing Hydrus-2D/3D and Philip (1984)’s model to assess wetting bulb expansion from buried and surface point sources 

Dario Autovino, Massimo Iovino, and Giorgio Baiamonte

In surface and subsurface drip irrigation systems, predicting the size expansion of the wetting bulb and the irrigation time are mandatory for water saving, and help drive their design and scheduling. At this aim, different hydrological models have been suggested to predict the wetting bulb expansion from buried and surface point sources. In this work, we compare the results obtained by the application of Hydrus-2D/3D and Philip (1984) model.

The Philip (1984) model accounts for the Gardner conductivity function, which is not implemented in Hydrus 2D/3D. Moreover, in the Philip (1984) model, a certain approximation in the choice of the water contents to be used for calculating the average volumetric water content behind the wetting front, θav, is necessary, also considering that definitions do not seem univocal. For example, the water content at the wetting front was assumed as the θav, value when soil hydraulic conductivity, K, was equal to 1 mm/day by Cook et al. (2003) and 1 mm/h by Thorburn et al. (2003).

For the purpose of the comparison, an extended analysis aiming at detecting the parameter ranges of the van Genuchten-Mualem model (van Genuchten 1980), which provide hydraulic conductivity functions matching those of Gardner, was preliminary conducted. Then, for van Genuchten-Mualem parameters falling in such parameters’ ranges, the average volumetric water content that is required in the Philip (1984) model was calculated in Hydrus-2D/3D.

For sandy-loam soil, results showed a quite good agreement between the simplified Philip (1984) model and the more accurate but numerically demanding Hydrus 2D/3D, suggesting that Philip (1984)’s model can be successfully applied to predict the wetting bulb expansion from buried and surface point sources, provided the average volumetric water content in the soil behind the wetting front and the saturated hydraulic conductivity are appropriately considered.

Keywords: wetting bulb, buried sources, surface sources, Philip (1984)’s model, Hydrus 2D/3D.

Acknowledgement: This study was carried out within the RETURN Extended Partnership and received funding from the European Union Next-GenerationEU (National Recovery and Resilience Plan – NRRP, Mission 4, Component 2, Investment 1.3 – D.D. 1243 2/8/2022, PE0000005).

References:

Cook, F.J., P.J., Thorburn, K.L., Bristow, and C.M., Cote, “Infiltration from surface and buried point sources: The Average wetting water content”, Water Resour. Res., 2003, 39(12): 1364, doi:10.1029/2003WR002554.

Philip, J.R., “Travel times from buried and surface infiltration point sources”, Water Resour. Res., 1984, 20(7), 990–994, https://doi.org/10.1029/WR020i007p00990.

Thorburn, P.J., F.J., Cook, and K.L., Bristow, “Soil-dependent wetting from trickle emitters: Implications for system design and management”, Irrig. Sci., 2003, 22: 121–127, doi 10.1007/s00271-003-0077-3.

van Genuchten, M. Th., “A closed form equation for predicting the hydraulic conductivity of unsaturated soils”, Soil Sci. Soc. Am. J., 1980, 44: 892-898.

How to cite: Autovino, D., Iovino, M., and Baiamonte, G.: Comparing Hydrus-2D/3D and Philip (1984)’s model to assess wetting bulb expansion from buried and surface point sources, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8199, https://doi.org/10.5194/egusphere-egu24-8199, 2024.

EGU24-9057 | ECS | Orals | HS8.3.7

Temporal impact of treated wastewater irrigation on field hydraulic conductivity 

Lin Wang, Tim De Cuypere, Sabien Pollet, Sarah Garré, and Wim Corneils

Hydraulic properties of agricultural soils exhibit dynamic temporal variations influenced by field management practices, such as tillage and irrigation, as well as climatic factors, particularly changes in precipitation and temperature. With the emergence of using treated wastewater (TWW) in irrigation as a solution to alleviate increased pressure on available water resources, but characterized by elevated salt and solute concentrations, understanding its potential impact on soil hydraulic properties is crucial. In this study, we aimed to discern the influences of field management practices and irrigation water sources on the temporal variability of soil hydraulic conductivity.

Mini disk infiltrometers were employed to assess near-saturated hydraulic conductivity Kh and associated soil indicators (including soil’s electrical conductivity ECe, sodium adsorption ratio SAR, water repellency WR, bulk density BD, aggregate stability AS, and air permeability Ka) in the top 20 cm of a Retisol soil in Beitem (50°91′N, 3°12′E), Belgium. A comparative analysis was conducted to evaluate the effects of irrigation using treated wastewater (from households, from vegetable industry and from potato industry) and rainwater, relative to those under rainwater irrigation conditions. All treatments significantly affected ECe and SAR. Across four replicated plots per treatment, Kh was measured at distinct matric potentials on various dates, spanning a wet (2021) and a dry (2022) year, during a crop rotation of cauliflower (Brassica oleracea L.) and spinach (Spinacia oleracea L.). The plots were tilled with a rotary harrow till 30 cm depth to prepare the seedbeds.

Our findings highlighted tillage as the predominant factor influencing Kh . Irrespective of the irrigation type, Kh increased post-tillage and subsequently decreased throughout the growing season. Yearly weather differences also played a significant role, with the dry, warm year resulting in a higher average Kh at each matric potential. Surprisingly, there were no significant differences in Khbetween irrigation treatments over two crop cycles

Despite the elevation of soil salinity (ECe) and sodicity (SAR) with TWW irrigation, it did not detrimentally impact or other soil attributes (WR, BD, AS, and Ka) in this study. Our results underscore the importance of considering the interplay of tillage, weather conditions, the timing/frequency of irrigation/rain events, and matric potential when evaluating the effects of different irrigation sources on soil hydraulic properties.

How to cite: Wang, L., Cuypere, T. D., Pollet, S., Garré, S., and Corneils, W.: Temporal impact of treated wastewater irrigation on field hydraulic conductivity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9057, https://doi.org/10.5194/egusphere-egu24-9057, 2024.

EGU24-9563 | ECS | Orals | HS8.3.7

A model for predicting permeability of geotextile envelope after combined clogging in arid areas 

Shuai Qin, Chenyao Guo, and Jingwei Wu

The clogging problem of geotextile envelopes in subsurface drainage pipes in arid areas can lead to a reduction of the drainage capacity in the drainage system. The current research on combined clogging is mostly in the stage of phenomenological observations or indoor experiments, and quantitative methods are lacking. In this study, a model for predicting permeability of geotextile envelope was developed using pore distribution theory of geotextile envelope. Then, a stepwise coupled combined clogging model was proposed based on the evolution characteristics of physical and chemical clogging. The coupled model was verified by field sampling, and the measured results of the three sites were within the range of the predicted values. Then, the main factors affecting the combined clogging model of the geotextile envelope were analyzed, and the clogging evolution was predicted. The results showed that the combined clogging model was sensitive to the physical clogging coefficient β1 during the first 30 days and more sensitive to the calcium carbonate saturation index (SI) after 30 days of drainage. When β1 was equal to 0.3, a saturation index greater than 1.0, which corresponds to drainage mineralization exceeding 3.0 g/L, indicated a high risk of clogging in Xinjiang.

How to cite: Qin, S., Guo, C., and Wu, J.: A model for predicting permeability of geotextile envelope after combined clogging in arid areas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9563, https://doi.org/10.5194/egusphere-egu24-9563, 2024.

EGU24-11295 | ECS | Orals | HS8.3.7

Development of a new modeling framework for estimating water needs in lowland agricultural areas: linking GIS database and SWAP simulation 

Giulio Gilardi, Darya Tkachenko, Michele Rienzner, and Arianna Facchi

The implementation of adaptation strategies is becoming increasingly important to mitigate climate-related risks and water resource overuse in agriculture. When considering large spatial domains, the assessment of alternative irrigation techniques can be carried out using a modelling approach, useful to take into consideration all the relevant processes in complex agro-ecosystems.

In ‘fully distributed’ models, the domain of interest is divided into simulation units, each characterized by a unique set of parameters and inputs, by using a regular grid. In ‘semi-distributed’ models, simulation units correspond with spatial units of different size and shape but homogeneous in terms of parameters and inputs. Moreover, if the description of processes is based on simplified schematization of the physical system and equations, models are referred as ‘conceptual’, whereas if an accurate physical-mathematical description is adopted, they are considered as ‘physically based’. Because of their complexity and computational requirements, ‘physically based’ models are often applied in a ‘semi-distributed’ manner when describing large territories.

A framework is currently under development to directly link a file-based vector database (GeoPackage), describing the main features of an agricultural area, and ‘physically based’ simulations carried out by the SWAP model (https://www.swap.alterra.nl/). The framework, written in Python, runs within the QGIS environment. It requires the user to define seven basic themes: I) a district domain, II) soil types, III) land uses, IV) irrigation water distribution areas, V) homogeneous groundwater depth polygons or groundwater level measuring stations, VI) homogeneous agro-meteorological polygons or agro-meteorological stations, and VII) a DTM raster layer. From the intersection of the layers considered, a number of polygons are generated. Next, the polygons are post-processed based on of the following options: a) aggregate all polygons characterized by the same value of the input themes, b) maintain all the polygons obtained through the intersection operation, or c) aggregate polygons based on a critical distance (meters). This last option is useful to limit the number of polygons and reduce the computational effort. In the case of multiple groundwater level or agro-meteorological measuring stations, the framework calculates the values of the variables to be assigned to each polygon through the ‘Inverse Distance Weighting’ (IDW) algorithm. Finally, the framework links each unit to its parameter set, transferring the information stored in the database into the SWAP input files. Simulation results are saved in a tabular format that allows them to be analyzed according to different aggregations (by land use, soil type, etc.) and to produce time series graphs or vector maps.

The application of the tool for the estimation of the irrigation requirements and the percolation fluxes of the Lomellina region (northern Italy) under the current and alternative irrigation strategies will be presented and discussed. The study area, located on the left bank of the Po River, covers more than 125,000 hectares mainly cropped with rice. In more recent years, this area is experiencing water shortages and a reduction in aquifer levels.

How to cite: Gilardi, G., Tkachenko, D., Rienzner, M., and Facchi, A.: Development of a new modeling framework for estimating water needs in lowland agricultural areas: linking GIS database and SWAP simulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11295, https://doi.org/10.5194/egusphere-egu24-11295, 2024.

Agricultural activities account for a significant portion of global water consumption, emphasizing the need to improve water productivity in this sector. This can be achieved through the implementation of effective agricultural management practices, such as optimizing crop patterns, adjusting irrigation methods, and improving fertilization practices. The Water Footprint (WF) concept offers a comprehensive approach to assessing water consumption in agriculture, considering different types of water use. By integrating the WF methodology with hydrological modeling programs, a more detailed analysis of water consumption patterns can be achieved, overcoming previous limitations in understanding agricultural water use. This study aims to assess the water consumption patterns of maize under different spatio-temporal dynamics. The WF of maize, including blue, green, and grey components, was calculated using the Soil and Water Assessment Tool (SWAT) model in the Ceyhan Basin (Turkey) between 2011-2020. The study outputs indicated considerable spatial and temporal variations, with a total WF ranging from 350 to 1320 m3/t. Green WF (61-385 m3/t) is found to be less dominant in maize production across the basin, while blue water emerges as the primary component (25 to 870 m3/t). In this study, the utilization of the SWAT model provided detailed spatio-temporal results, allowing for adjustments in agricultural patterns. We obtained that, optimizing the cultivation regions of maize within the Ceyhan Basin has the potential to reduce the total WF by approximately 26% and the blue WF by 47%. This optimization could result in an annual saving of around 135 million m3 of irrigation water. Furthermore, the study also analyzed temporal water consumption patterns. The findings highlight the significant potential for water conservation in agricultural activities through the spatio-temporal optimization of blue and green water, taking into account hydrological characteristics.

How to cite: Muratoglu, A. and Demir, M. S.: Understanding spatio-temporal variations in crop water consumption: Applying the WF Methodology Integrated with the SWAT Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12151, https://doi.org/10.5194/egusphere-egu24-12151, 2024.

EGU24-12460 | ECS | Posters on site | HS8.3.7

Water vapor movement and utilization with condensation in the upper layers of a sandy soil column 

Simran Sekhri, Volker Kleinschmidt, Annette Eschenbach, and Joscha N Becker

In semi-arid and arid regions, prolonged dry spells lead to a significant reduction in topsoil moisture, forming a dry soil layer, where water can only move as vapor. Such conditions hinder young crops with weakly developed root systems to directly reach deep water reservoir. Since there is no indication of gaseous water uptake from soil pores, plants might be able to acquire water from these deep sources when water vapor condensates at night or at a vapor barrier (mulch). To trace potential water vapor uptake by plants, we developed a sand column experiment using deuterium labeled water. The water source column was separated by a glass bead layer and a root barrier (50µm mesh) from the soil to ensure that there was no capillary rise or root uptake of liquid water. Four treatments with three replicates, including planted (Pl), unplanted (Un), mulch variation (Pl+M; Un+M) and an additional unlabeled control column, were installed in a climatic chamber. Vigna radiata a moderately drought resistant plant species was selected for this experiment. Constant day-night cycle with stable temperature and light conditions were maintained for a period of seven days without irrigation. Afterwards, soil samples were collected at 0-5, 5-10 and 10-15 cm depths. Vigna radiata saplings and condensed water samples were collected separately. Cryo-extraction of water from the samples and liquid isotopic water analysis revealed substantial results for the uptake of water vapor by young saplings. Evaporation from the water source into the column was recorded to be 0.7-2.1 ml. The δD/H ratios were analysed using Triple Isotope Water Analyser (Los Gatos Research). The relative potential uptake of water vapor by young saplings was recorded to be as high as 0.56ml for the 'Pl' and 0.35ml for the 'Pl+M' treatment. The utilization of water vapor by young plants in the upper soil layer could prolong plant life during dry spells. Although, it remains uncertain to what extent the prolongation could be maintained.

Keywords: Deuterium Labeled Water, Plant Vitality, Water Conductivity

How to cite: Sekhri, S., Kleinschmidt, V., Eschenbach, A., and Becker, J. N.: Water vapor movement and utilization with condensation in the upper layers of a sandy soil column, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12460, https://doi.org/10.5194/egusphere-egu24-12460, 2024.

EGU24-18026 | Posters on site | HS8.3.7

Wappfruit, a project for the optimization of the irrigation in agriculture: final results 

Davide Canone, Davide Gisolo, Luca Nari, Francesca Pettiti, Alessio Gentile, Stefano Ferraris, Mattia Barezzi, Umberto Garlando, and Danilo Demarchi

The Wappfruit project objective is to optimize the irrigation techniques for water and energy saving in fruit orchards in the Piemonte Region, Northwest Italy. The stakeholders of the project are Politecnico and the University of Torino, Piemonte Region, Agrion Foundation for Research in Agriculture, Astel S.r.l. (for the industrialisation of the experimental hardware developed by Politecnico di Torino), and three farms (“La Marchisa” and “Lorenzo Sacchetto” – apple orchards and “Paolo Vassallo” – actinidia orchard).  In each farm, two areas were identified, an “experimental area” where the new set-up was tested and a control area where the farmers continued the irrigation as usual.

In the year 2023, the Wappfruit project has shown the potentiality of a smart irrigation solution composed of two kinds of IoT (Internet of Things) nodes employing LoRa technology and governed by a 24/7 server script, written in Python, that acquires soil matric potential and decides the opening and closure of the irrigation pumps in real-time. The soil matric potential thresholds, identified in 2022 and early 2023, (-60 kPa and -25 kPa at 20 cm of depth for the activation of the irrigation, respectively in the apple and Actinidia orchards; -50 kPa at 40 and 20 cm of depth and -18 kPa at 20 cm of depth, for the deactivation of the irrigation, again respectively for apple and Actinidia orchards) were verified again after a campaign in which soil parameters (saturated soil water content, infiltration velocity at saturation) were measured. These values were used for new model simulations that included irrigation. The thresholds for the apple orchards were confirmed, whereas new thresholds were identified for the Actinidia: -12 kPa (activation) and -5 kPa (deactivation). Results highlight that these thresholds can activate and deactivate the irrigation appropriately. The 2022 simulations show a matric potential in agreement with the measures collected (R between 0.51 and 0.88). Moreover, the 2023 simulations with modelled irrigation show a good agreement with the measures in the experimental area. Both the simulations and the real optimized irrigation generally show lower values if compared with the irrigation of the farmers (range: 13 – 217.5 mm/ha), with an exception in one apple orchard, where the model suggests more irrigation than expected, likely because of an overestimation of the water infiltration velocity. The hardware/software design and implementation have shown that low-cost low-power electronic devices and artificial intelligence can be reliable and very inexpensive for water and energy savings. The remote control of the system is another important achievement. Moreover, optimized irrigation does not affect the vegetation productivity and increases the fruit quality.

How to cite: Canone, D., Gisolo, D., Nari, L., Pettiti, F., Gentile, A., Ferraris, S., Barezzi, M., Garlando, U., and Demarchi, D.: Wappfruit, a project for the optimization of the irrigation in agriculture: final results, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18026, https://doi.org/10.5194/egusphere-egu24-18026, 2024.

EGU24-18956 | Posters virtual | HS8.3.7

Innovative irrigation strategies for rice in the Mediterranean areas 

Olfa Gharsallah, Arianna Facchi, Gerard Arbat, Sílvia Cufí, Francisco Ramírez de Cartagena, Marco Romani, Michele Rienzner, Darya Tkachenko, Concepcion Mira, Isabel Pedrosa de Lima, José Manuel Gonçalves, Abdrabbo Shehata Aboukheira, Saad Shebl, and Melih Enginsu

Rice is the world's most important food crop, as it is a staple food for more than half of the world's population, and the global demand for rice is expected to increase. More than 1,000,000 hectares in the Mediterranean basin are devoted to rice cultivation. The most important producing countries are Italy (IT) and Spain (SP) in Europe (over 310,000 ha), and Egypt (EG) and Turkey (TR) among non-EU countries (over 600,000 ha). In the Mediterranean region, rice production is of great socio-economic and environmental importance, as rice is often a crucial product for internal consumption and export, especially in Egypt, where it is considered strategic for food security. Despite of this, the peculiar flooding conditions in which rice is traditionally grown lead to the use of huge water volumes, as well as to the potential release of greenhouse gases and pesticides into the environment. For this reason, the introduction of water-saving irrigation strategies could reduce water consumption and decrease the harmful environmental impacts associated with rice flooding, while maintaining yield and rice grain quality.

In the context of the MEDWATERICE project (https://www.medwaterice.org/; PRIMA-2018), alternative irrigation methods to WFL were tested in case studies implemented in five Mediterranean countries (Italy, Spain, Portugal, Turkey, Egypt). Irrigation strategies for each CS were selected with the support of local Stake-Holder groups and applied in experimental fields measuring/estimating all the water balance terms on a daily basis. Wet seeding and alternate wetting and drying (AWD), dry seeding and delayed flooding (DFL), reduction of inlet/outlet discharges (WIR), a better control of ponding water level through automated gates (DFL-aut), hybrid irrigation (HYBRID), sprinkler irrigation (SPRINKLER), surface drip (DRIP) and subsurface drip irrigation (SDI) were implemented for at least two years in the period 2019-2021 alongside the traditional WFL, to investigate their environmental and economic sustainability and social acceptability.

How to cite: Gharsallah, O., Facchi, A., Arbat, G., Cufí, S., Ramírez de Cartagena, F., Romani, M., Rienzner, M., Tkachenko, D., Mira, C., de Lima, I. P., Gonçalves, J. M., Aboukheira, A. S., Shebl, S., and Enginsu, M.: Innovative irrigation strategies for rice in the Mediterranean areas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18956, https://doi.org/10.5194/egusphere-egu24-18956, 2024.

EGU24-19384 | ECS | Posters on site | HS8.3.7

Effective radius of corrugated drainage pipes wrapped with a thin geotextile envelope 

Haoyu Yang, Chenyao Guo, and Jingwei Wu

Subsurface drainage is widely used in farmland. Entrance resistance occurs when water flows into a perforated drain pipe, reducing the drainage efficiency and resulting in a high water table. Using the real radius will overestimate the drainage discharge. Accurately calculating effective radius is essential for subsurface drainage calculation and simulation. New effective radius formulas for corrugated drains wrapped with a thin geotextile were proposed by dividing the entrance resistance into corrugation and perforation resistance. The accuracy of the formulas was verified by sand tank experiments. Sensitivity analysis was conducted to determine the factors that affected effective radius, indicating that corrugation was the main factor. When the radius and structure of the drain wall were determined, the opening area exhibited high sensitivity with interactivity between it and drainage discharge. The effect of the opening area and position of the perforations on the effective radius was evaluated for different drainage discharges. Putting the perforations on the bottom was better for drainage efficiency. For small drainage discharge of less than 0.1 cm3 s-1 cm-1, the opening area was not significant, and an opening area of 15 cm2 m-1 was sufficient. However, for greater drainage discharge, an opening area of 60 cm2 m-1 with three or more row perforations would be required.

How to cite: Yang, H., Guo, C., and Wu, J.: Effective radius of corrugated drainage pipes wrapped with a thin geotextile envelope, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19384, https://doi.org/10.5194/egusphere-egu24-19384, 2024.

EGU24-20020 | Posters on site | HS8.3.7 | Highlight

Enhancing Vegetation Cover in Fujairah through Sustainable Honey Tree Plantations and Water Harvesting Technique: A Multi-Criteria Suitability Mapping 

Youssouf Belaid, Abeyou Worqlul, Mira Haddad, Aseela Al Moalla, and Fouad Lamghari Ridouane

The emirate of Fujairah, spanning approximately 1,450 km², is characterised by a landscape dominated by rugged mountains, encompassing 77% of its total surface area. Despite its average precipitation of less than 150 mm, Fujairah hosts a thriving ecosystem supported by national tree plantations, including Acacia nilotica, Acacia tortilis, Prosopis cineraria, and Zizyphus spina-christi. These plantations are crucial in providing ecosystem services, notably contributing to honey bee production.

This study attempts to support the increase of vegetation cover in Fujairah through sustainable land management practices of using water harvesting and planting native trees by employing cutting-edge technology. Through the integration of Remote Sensing and Geographic Information System (GIS)-driven Multi-Criteria Evaluation (MCE), the research identifies optimal areas for planting native honey trees. Emphasising sustainability, the methodology incorporates water harvesting techniques that eliminate reliance on traditional irrigation methods for plantation.

Local and international datasets encompassing biophysical parameters such as land use, digital elevation models, slope, topographic wetness index, soil texture, and climate data are combined. Additionally, the study considers optimal ecological conditions for native trees, including temperature and soil pH. The resulting suitability maps, treated as future land cover maps, are employed alongside soil sample data to estimate carbon storage and sequestration potential.

Furthermore, the research investigates indigenous water harvesting knowledge in Fujairah through a comprehensive survey. This survey explores community awareness, historical context, current applications, technical specifics of water harvesting and native tree plantation practices, environmental considerations, and potential obstacles and solutions.

The findings aim to inform a holistic approach to sustainably enhancing Fujairah's vegetation cover, providing valuable insights for environmental conservation and community engagement.

Keywords: Suitability mapping, water harvesting techniques, Sustainable land management, and Ecosystem Services

How to cite: Belaid, Y., Worqlul, A., Haddad, M., Al Moalla, A., and Lamghari Ridouane, F.: Enhancing Vegetation Cover in Fujairah through Sustainable Honey Tree Plantations and Water Harvesting Technique: A Multi-Criteria Suitability Mapping, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20020, https://doi.org/10.5194/egusphere-egu24-20020, 2024.

EGU24-20913 | Posters on site | HS8.3.7

Effectiveness of natural soil water retention measures at field scale under current and future climate – case studies in three European biogeographical regions 

Csilla Farkas, Moritz Shore, Ágota Horel, Gökhan Cüceloglu, Levente Czelnai, Dorota Mirosław-Świątek, Maria Eliza Turek, Natalja Cerkasova, Brigitta Szabó, Antonín Zajiček, Attila Nemes, Sinja Weiland, Petr Fucik, Annelie Holzkaemper, Rasa Idzelyté, and Stepan Marval

Within the EU Horizon project OPTAIN (OPtimal strategies to reTAIN and re-use water and nutrients in small agricultural catchments across different soil-climatic regions in Europe, optain.eu) project, the effects of Natural/Small Water Retention Measures (NSWRMs) on water regime, soil erosion and nutrient transport are evaluated at both, catchment- and field-scales for present and future climate conditions. Our goal is to perform an integrated, model-based assessment of the effectiveness of NSWRMs at field scale and cross-validated these results from those obtained from the catchment-scale modelling. The field-scale assessment is based on the adaptation of the SWAP mathematical model to seven pilot sites across three European biogeographical regions and on combined NSWRM – projected climate scenario analyses. The scenarios are designed to evaluate the efficiency and potential of different natural/small water retention measures in improving soil water retention and reducing flash floods and the loss of soil and nutrients under changing climate conditions. We present the harmonized SWAP modelling workflow and the combined scenario analyses, including the implementation of various in-field measures in the SWAP model. Examples of model calibration, validation and scenario results for selected pilot sites will be given.

How to cite: Farkas, C., Shore, M., Horel, Á., Cüceloglu, G., Czelnai, L., Mirosław-Świątek, D., Turek, M. E., Cerkasova, N., Szabó, B., Zajiček, A., Nemes, A., Weiland, S., Fucik, P., Holzkaemper, A., Idzelyté, R., and Marval, S.: Effectiveness of natural soil water retention measures at field scale under current and future climate – case studies in three European biogeographical regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20913, https://doi.org/10.5194/egusphere-egu24-20913, 2024.

EGU24-20983 | Posters on site | HS8.3.7

A framework based on Melisenda’s aridity index and on Budyko’s curve to assess the crop proneness to the hydrological sustainability 

Stefano Barontini, Martina Greta Caffi, Muhammad Faisal Hanif, Elpida Kolokytha, Dimitrios Malamataris, and Marco Peli

Many agroecosystems are experiencing an increase of agricultural water demand which risks depleting the natural reservoirs, viz lakes and aquifers. The increasing temperature reduces glacier extent and snow accumulation, thus reducing the dry—season water availability, and challenging the agricultural systems and the food security, particularly in arid and semiarid regions.

Aiming at contributing to defining effective strategies that are able to provide robust and parametric parsimonious estimates of the irrigation water demand of the agroecosystems at the planning level, we propose a framework based on the joint use of Melisenda’s aridity index, Benfratello’s water balance and Budyko’s curve to define the crop proneness to the hydrological sustainability.

The strategy is based on Benfratello’s (1961) explicit and conservative method to assess the soil water balance and the irrigation deficit in semiarid Mediterranean climates. The method is parametrized by means of an aridity index (Melisenda, 1964) to assess the soil proneness to water surplus formation, and the results are compared with the natural ecosystem deficit as provided by Budyko’s (1974) curve. Coupling these climatic water balances with a crop based estimate of the maximum required evapotranspiration, as given by the FAO procedure, it is possible to assess the expected crop irrigation deficit.

Our strategy is two—step. The first step is mapping Melisenda’s index, to identify the climatically—wet areas and the potentially climatically—dry areas. In potentially dry areas field capacity may not be refilled during the dry season, if it is greater than a critical value. It is worth noting that the greater is the field capacity, the smaller is the surplus water, and the greater is the crop water availability during the dry season. These maps may be produced both for the actual cultivations, and for some reference crops, viz millet, barley, rice and wheat, which are important for food security, to depict the local hydrological attitude to them.

The second step is the calculation of the monthly and annual irrigation deficit by means of Benfratello’s water balance. The irrigation deficit does not depend only on the annual precipitation and on the annual crop water demand, but also on their annual regime. Benfratello’s irrigation deficit is then compared with the ecosystemic water deficit, provided by Budyko’s curve. The closer is the crop behaviour to Budyko’s curve, the closer is its water demand to the ecosystemic one, considered as a reference natural water demand.

In order to test the sensitivity of the procedure at characterising the water balance also in presence of small climatic differences, we applied it with promising results to two important and comparable Mediterranean agricultural districts, the Bonifica della Capitanata (Southern Italy, 4,410 km2, mainly cultivated with herbaceous crops, olives, fruit and grapevine trees) and the Mygdonia water basin (Northern Greece, 2,100 km2, 1,030 of which are cultivated mainly with cereals). The Köppen—Geiger climate type is mainly Cfa for both areas. De Martonne aridity index depicts a semi—dry to Mediterranean condition for the Capitanata and a mainly Mediterranean condition for the Mygdonia.

How to cite: Barontini, S., Caffi, M. G., Hanif, M. F., Kolokytha, E., Malamataris, D., and Peli, M.: A framework based on Melisenda’s aridity index and on Budyko’s curve to assess the crop proneness to the hydrological sustainability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20983, https://doi.org/10.5194/egusphere-egu24-20983, 2024.

The global issue of saltwater intrusion (SWI) is impacting coastal aquifers more prominently due to climate changes and the escalating demand of freshwater for various anthropogenic activities. Consequently, there has been a heightened focus on research in this area to improve predictions regarding the effect of geological media on the advancement of salt water into fresh aquifers. The current study simulated saltwater flow into a freshwater zone for a coastal environment, considering density-dependent effects. Two specific scenarios were considered: one involving homogeneous media and the other involving heterogeneous media. In prior studies, researchers commonly employed homogeneous media exclusively for simulating SWI experiments. However, for the present work, we also incorporated heterogeneous media with a geophysical Direct Current (DC) sounding approach to determine the interface between fresh and saltwater. The experimental responses were numerically modelled to know the behaviour of geological constraints during the flow of saline water. For validation, a field example of the DC resistivity survey was incorporated for a better correlation. The experimental findings suggest that the interface between freshwater and saltwater was influenced when the advancing saltwater wedge encountered the clay layer. For a coastal environment, a clay layer (which is porous but not permeable) is crucial in influencing saltwater intrusion dynamics. The agreement between experimental data, numerical simulations, and DC-sounding outcomes indicates that the proposed integrated approach can be a valuable benchmark for future studies on seawater intrusion, even in environments with more complex geological conditions.

 

Keywords: Aquifers, Saltwater Intrusion (SWI), DC Sounding, Numerical modeling.

How to cite: Tiwari, P. and Sharma, S. P.: Investigating the influence of geological heterogeneity in the advancement of the saltwater wedge: A novel perspective study employing Experimental, DC Sounding and Numerical modeling approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-314, https://doi.org/10.5194/egusphere-egu24-314, 2024.

EGU24-654 | ECS | Orals | HS8.2.13

Geoelectrical and electromagnetic imaging methods applied to groundwater systems: recent advances and future potentials 

Paula Rulff, Octavio Castillo-Reyes, Philipp Koyan, Tina Martin, Wouter Deleersnyder, and Maria Carrizo Mascarell

The impacts of climate change, combined with population growth, necessitate practical and effective solutions for locating groundwater resources and ensuring drinking water quality. Our contribution explores recent advances in geoelectrical and electromagnetic imaging methods applied to investigate groundwater systems. Geoelectrical and electromagnetic imaging techniques are popular methods for characterising subsurface properties, such as electrical resistivity or dielectric permittivity. These electrical properties are strongly related to the hydrogeological characteristics of the subsurface. Therefore, geoelectrical and electromagnetic investigations can provide valuable insights into finding groundwater resources, assessing the water quality in terms of contaminations and conducting effective groundwater management.

Our study examines state-of-the-art approaches in modelling and instrumentation of induced polarisation and electrical resistivity tomography, as well as time- and frequency-domain electromagnetics and ground-penetrating radar methods. We review recent impactful and innovative groundwater case studies where the above-mentioned methods were applied and further developed. Emphasising the combination of geoelectrical and electromagnetic methods, the studies provide insights into the variation of electrical subsurface properties at different scales, contributing to an improved understanding of the hydrological dynamics in the studied areas. Furthermore, we provide an outlook on the potential for applying geoelectrical and electromagnetic imaging techniques for large-scale groundwater investigations in the exascale computing area.

How to cite: Rulff, P., Castillo-Reyes, O., Koyan, P., Martin, T., Deleersnyder, W., and Carrizo Mascarell, M.: Geoelectrical and electromagnetic imaging methods applied to groundwater systems: recent advances and future potentials, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-654, https://doi.org/10.5194/egusphere-egu24-654, 2024.

EGU24-2176 | ECS | Posters virtual | HS8.2.13

Predicting Soil Bulk Density in Boreal Podzolic Soil using Ground-Penetrating Radar and Electromagnetic Induction 

Sashini Pathirana, Lakshman Galagedara, Sébastien Lambot, Manokararajah Krishnapillai, Christina Smeaton, and Mumtaz Cheema

Soil compaction is one of the major challenges in sustainable agriculture, primarily due to the use of heavy farming machinery. Tillage and soil compaction influence soil properties, state variables, and processes, ultimately affecting soil health, crop growth, and yield. Traditional methods to estimate soil compaction level, like bulk density (BD) and penetration resistance, are laborious, destructive, time-consuming and provide point-scale measurements only. Near-surface geophysical techniques like Ground-Penetrating Radar (GPR) and Electromagnetic Induction (EMI) are being increasingly utilized to estimate soil properties and state variables in the agricultural landscape since GPR and EMI can address some of drawbacks of traditional methods. However, there is a lack of studies with GPR and EMI examining the BD change associated with tillage and soil compaction. We hypothesize that proxies from GPR and/or EMI can be used to predict BD as an indicator of soil compaction. The objectives were to: 1) evaluate the impact of BD change on dielectric constant (Kr) and direct ground wave amplitude (A) measured from GPR, and apparent electrical conductivity (ECa) measured by EMI; and 2) assess the predictive capability of GPR and EMI for BD determination. The experiment was conducted on a loamy sand textured soil at a boreal podzolic site in Newfoundland, Canada. Proxy data (i.e., Kr, A and ECa) were collected using a 500 MHz center frequency GPR system and an EMI sensor representing three compaction treatments (i.e., after tillage, after 4- and 10-time roller passes). Treatment effects and relationships between proxies and the average BD of 0-30 cm soil depth were tested using analysis of variance (ANOVA) and correlation analysis. A Random Forest (RF) regression approach was employed to identify the most significant variables for predicting BD. Subsequently, simple, and multiple linear regression models (LRM) were developed. The accuracy of these LRMs was assessed by comparing predicted and measured BD values. ANOVA results reveal that the measured BD and proxies are significantly different at all three compaction levels. The average BD strongly correlated with soil proxies; Kr(r=0.72), A (r=0.71), and ECa(r=0.89). Based on RF, ECa and Kr are the most important variables to predict BD for the studied data set. Therefore, ECaand Kr were used to develop simple and multiple LRMs. The simple LRM developed with ECa showed a higher coefficient of determination, R2=0.80, compared to Kr (R2=0.63), while the multiple LRM showed the highest R2 (R2=0.83). The model predicted BDs did not deviate from 1:1 line with a root mean square error of <0.14 g/cm3. This study highlights the potential of using GPR and EMI to predict BD non-destructively while covering a larger sample volume. Further research must be conducted to assess the applicability and limitations of this approach under different water contents, electrical conductivities, and soil types.

How to cite: Pathirana, S., Galagedara, L., Lambot, S., Krishnapillai, M., Smeaton, C., and Cheema, M.: Predicting Soil Bulk Density in Boreal Podzolic Soil using Ground-Penetrating Radar and Electromagnetic Induction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2176, https://doi.org/10.5194/egusphere-egu24-2176, 2024.

EGU24-2394 | Orals | HS8.2.13

Unveiling the characteristics of ZVI-AC-sand mixtures in remediating contaminated groundwater using spectral induced polarization 

Deqiang Mao, Xinmin Ma, Alex Furman, Nimrod Schwartz, Chen Chao, Teng Xia, Kai Yang, and Xiaolei Guan

The long-term performance of the permeable reactive barriers in remediating contaminated groundwater may diminish as a result of oxidation, precipitation on the particle surfaces, and pore space clogging. Evaluating its performance through monitoring could address this dilemma. We investigate the spectral induced polarization (SIP) response of zero valent iron (ZVI)-activated carbon (AC)-sand mixtures.The chargeablity exhibits a perfect linear relation to the volumetric concentration of ZVI (2.5-50%) and AC (2.5%-75%) with r = 0.99. However, the low-frequency electrical conductivity shows low sensitivity to the volumetric content of ZVI and AC. The relaxation time increases with the particle sizes. When these two particles are mixed, chargeablity is approximated as a superposition of their individual values. In terms of phase values and frequencies of the phase peaks, it also exhibits this superposition effect. Furthermore, we conducted 720-hour SIP measurements on ZVI-AC-sand columns flushed with NaCl or NaNO3 solutions. It suggests that precipitation of 0.06 mm thick sedimentation onto the ZVI surface induced by changes in redox chemistry observed in micromorphology images, resulting an increase in the normalized chargeability by 44.05%, the scaled relaxation time and Cole–Cole model exponent by 1098.99% and 23.11%. Compared to flow-through by NaCl solution, changes in these parameters are more pronounced for columns saturated with NaNO3 solution, indicating the corrosion of ZVI. Our findings illustrate that induced polarization parameters vary in response to the chemical alteration of ZVI-AC-sand mixed media, showing the potential for noninvasive long-term monitoring of the reactive barriers.

How to cite: Mao, D., Ma, X., Furman, A., Schwartz, N., Chao, C., Xia, T., Yang, K., and Guan, X.: Unveiling the characteristics of ZVI-AC-sand mixtures in remediating contaminated groundwater using spectral induced polarization, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2394, https://doi.org/10.5194/egusphere-egu24-2394, 2024.

Groundwater level, permeability and chemical components can be affected by earthquakes, however there are few comprehensive investigations on the combination of long-term continuous monitoring data and multiple strong earthquakes. In this study, continuous two-year dataset of groundwater levels and chemical compositions of groundwater (Ca2+, Mg2+ and HCO3-) in well #32 were collected to analyze the groundwater dynamic changes induced by earthquakes in the aquifer-aquitard system. The groundwater level appeared co-seismic rise change induced by Yangbi MW 6.1 earthquake and Luding MW 6.6 earthquake. The vertical permeability, estimated by the tidal response model, exhibited decrease changes during the period of Yangbi MW 6.1 earthquake and Luding MW 6.6 earthquake. Meanwhile, the continuous two-year chemical compositions showed that Ca2+ and HCO3- concentrations decreased, and Mg2+ concentrations increased during the two earthquakes period. The correlation between the vertical permeability and chemical compositions showed that there was a significant negative correlation between the vertical permeability and Mg2+, and a significant positive between the vertical permeability and Ca2+, HCO3-. A possible mechanism for observed fluctuations in some chemical compositions during earthquakes periods was that the reduction of mixing effect of different groundwater caused by permeability decreased. The flow of groundwater richened in Ca2+ and HCO3- from the overlying aquifer to the observation aquifer has been reduced. Meanwhile, due to the weakening of dilution effect, the Mg2+ concentration of the observation aquifer increased. This study can enhance understanding of the groundwater dynamic changes induced by earthquakes.

How to cite: Feng, X., Zhou, Z., and Zhong, J.: Groundwater dynamic changes induced by earthquakes in an aquifer-aquitard system from well monitoring in Southwest China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2961, https://doi.org/10.5194/egusphere-egu24-2961, 2024.

EGU24-3994 | Posters on site | HS8.2.13

Coupled multiphysics approach to characterize groundwater flow system around a near-surface fault zone 

Marceau Gresse, Akinobu Miyakoshi, Shogo Komori, Hinako Hosono, Yuki Tosaki, Tsutomu Sato, Daisuke Asahina, Hitoshi Tsukamoto, Makoto Otsubo, and Mikio Takeda

Fault zones intensively disturb local hydrogeologic structures, and, consequently, can play a critical role in governing small to large-scale groundwater flow. Extensive studies have focused on the permeability variation along faults in the light of the conduit or barrier function for the deep groundwater flow. However, little attempt has been made to characterize the hydrological functions of near-surface fault zone.

Exposed to atmospheric conditions, fault zones are further disturbed by stress relief and chemical weathering, modifying their structure and generally increasing their permeability. Consequently, the fault zone, which functions as a recharge or discharge zone at the near surface, exerts a non-negligible influence on groundwater flow. However, identifying the hydrological function of near-surface fault zone remains challenging when relying solely on conventional, often non-integrated, geophysical or hydrological investigation approaches.

This study proposes a multiphysics coupled strategy to understand the groundwater flow regime around near-surface fault zone. The proposed approach is applied to an active reverse fault zone in Kamikita Plain, NE Japan, which extends for 30 km within the recharge zone of the catchment.

The proposed multiphysics approach consists of 5 successive steps:

  • 2-D Electrical Resistivity Tomography (ERT) Survey: A 2.3 km-long profile crossing the fault zone, consisting of 7 roll-along surveys with a 6-m electrode spacing.
  • Self-Potential Survey: Conducted along the 2.3 km ERT profile.
  • Rock Property Characterization: A 80 m deep borehole was drilled in the fault zone and physical properties were measured.
  • 3-D Groundwater Flow Simulation of the Fault Zone: Utilizing areal hydrogeological data, measured rock properties, and geophysical imaging.
  • Model Validation Process: Using the results from the groundwater flow simulation, electrical conductivity and self-potential responses were calculated, and compared with observed field data.

Preliminary results successfully reproduce the overall resistivity signature and the self-potential anomaly (+35 mV) in the fault zone, attributed to local groundwater upwelling. This newly proposed multiphysics approach could be an essential tool to evaluate the groundwater flow in a region including large-size fault zone, which is important for radioactive waste disposal. Furthermore, this approach could also be effective in capturing the local fluid flow circulation for a variety of applications.

Acknowledgements: Main part of this research project has been conducted as the regulatory supporting research funded by the Secretariat of the Nuclear Regulation Authority, Japan.

How to cite: Gresse, M., Miyakoshi, A., Komori, S., Hosono, H., Tosaki, Y., Sato, T., Asahina, D., Tsukamoto, H., Otsubo, M., and Takeda, M.: Coupled multiphysics approach to characterize groundwater flow system around a near-surface fault zone, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3994, https://doi.org/10.5194/egusphere-egu24-3994, 2024.

EGU24-4487 | ECS | Orals | HS8.2.13

Water transport in agricultural soils estimated by time-lapse electrical resistivity tomography technique 

Jia-Wei Liu, Young-fo Chang, and Tsang-Sen Liu

It is well-recognized that soil moisture plays an important role in the management of water resources, as well as soil and crop production. This research proposed the use of time-lapse Electrical Resistivity Tomography (ERT) to overcome the limitations of point-based soil moisture measurement, which often fails to capture detailed spatiotemporal data. ERT is a widely used geophysical technique for the non-destructive exploration of subsurface media’s resistivity. Since the electrical resistivity is sensitive to the water content in soil, the variation of the soil’s resistivity in time and space can be obtained by using this technique that can be correlated to water transport in soil. Thus, using time-lapse ERT for the exploration of water transport in the soil was launched in this study.

This research conducted a time-lapse ERT survey executed in a farm during a sprinkling rainfall. A 50 meters time-lapse ERT survey was employed for 29 days with a hybrid-array configuration at a fallow land. The electrode spacing was 1 meter and measurement were conducted every 2 hours, thus a resistivity section of the land with 50 meters in length and 4 meters in depth was estimated with a period of 2 hours. In addition, five moisture meters were set up in the middle of the ERT survey line and at depths of 10, 20, 30, 50, and 100 cm, respectively. Then, the variation of the resistivity was compared with the precipitation data and the soil moisture readings from the meters. The results showed that the decrease of soil resistivity was consistent with the increase of the precipitation and soil moisture. The water transport rates in soils estimated by this technique and moisture meters were similar, they were 20 mm/hour and 16 mm/hour, respectively.

This study demonstrates that time-lapse ERT is an effective tool for dynamically monitoring water transport in soils. By employing this technique, near real-time 2D soil moisture monitoring becomes feasible, which could significantly enhance the optimization of water resources and crop production, when integrated with an automatic irrigation system.

How to cite: Liu, J.-W., Chang, Y., and Liu, T.-S.: Water transport in agricultural soils estimated by time-lapse electrical resistivity tomography technique, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4487, https://doi.org/10.5194/egusphere-egu24-4487, 2024.

Accurately determining soil hydraulic properties is a complex task due to significant variations in spatial information, posing ongoing challenges in managing subsurface and agricultural practices effectively. Geophysical methods, alongside traditional techniques, play a crucial role in monitoring subsurface state variables and inferring soil properties. Electrical Resistivity Tomography (ERT) is an appealing geophysical method due to its non-invasive, easy-to-apply and cost-effective nature. In ERT, electrical resistivity tomograms, obtained with surface measurements, are used to monitor the hydraulic state of the subsurface by translating the electrical tomograms to water content or pore-water salinity maps using calibrated petrophysical relations. However, obtaining 2D (or 3D) electrical tomograms from raw measurements requires the inversion of an ill-posed problem, which causes smoothing of the actual structure. Furthermore, the spatial resolution of the electrical tomograms is determined from the distances in the electrode placement, thus inherently upscaling the obtained structure. In this study, we explored the applicability of Physics-Informed Neural Networks (PINNs) for simultaneously upscaling soil properties, specifically the permeability and the petrophysical relations, and monitoring water dynamics at heterogeneous soils, using time-lapse geoelectrical measurements as the training data. High-resolution numerical simulations mimicking water infiltration to the subsurface were used as benchmarks to test the provided approach. Synthetic time-lapse ERT surveys with electrode spacing ten times larger than the numerical model resolution were conducted to provide upscaled 2D electrical resistivity tomograms. The electrical tomograms were fed to a PINNs system to obtain the permeability, petrophysical relations, and water content spatiotemporal maps simultaneously. To examine the system sensitivity to the measured data, an additional PINNs system that also incorporates water content measurements at 20 random locations was trained separately. Results have shown that the PINNs system could produce reliable results regarding the upscaled (heterogeneous) permeability and petrophysical relations fields. Water dynamics at the subsurface was accurately predicted by the PINNs system with an average error of ∼3% in the upscaled water saturation maps. The two separately trained PINNs systems have provided similar results in the obtained fields, indicating that the PINNs system can produce unique solutions for highly ill-posed problems. The addition of water content measurements at 20 random locations to the PINNs system training slightly improved the system outcomes, where a reduction of ∼0.25% in the upscaled water saturation average misfit was observed. Improvements were primarily located at the ERT low sensitivity zones, i.e., at the array's outskirts and large depths, thus implying the cost over benefits for obtaining additional hard data for training the system.

How to cite: Sakar, C., Schwartz, N., and Moreno, Z.: Upscaling Permeability, Petrophysical Relations and Water Saturation Maps of Heterogeneous Soils Using Physics-Informed Neural Networks Trained with Time-lapse Geo-electrical Tomograms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6719, https://doi.org/10.5194/egusphere-egu24-6719, 2024.

EGU24-8903 | ECS | Posters on site | HS8.2.13

Pore Structure Affecting the NMR Relaxation in Unsaturated porous media  

Junwen Zhou and Chi Zhang

Nuclear magnetic resonance (NMR) uniquely reveals pore water properties due to the magnetization and relaxation dynamics of water molecule hydrogen atoms. Importantly, the correlation between NMR signals (amplitude and relaxation times) and water content and distribution aids in discerning water retention patterns in porous media. While this relationship is well understood in saturated media, comprehending water dynamics under unsaturated conditions using NMR datasets is a considerable challenge, owing to the complexities of the pore environment (e.g. pore structure and interactions between different phases and components). In many previous studies, an increased amplitude of shorter relaxation T2 time distribution components has often been associated with enhanced water bound in micropores in unsaturated versus saturated media. The interpretation is counterintuitive as smaller pores cannot exceed their saturation water capacity, implying a potential misinterpretation of water distribution dynamics and pore structure within unsaturated media. To address this misinterpretation, our study develops a model to simulate the T2 peak shift from unsaturated to saturated pore states. The simulations successfully reconcile these anomalies, indicating that unsaturated macropores can display short relaxation times akin to saturated micropores and demystifying the decrease in shorter relaxation time components in T2 distributions of non-expansive, multi-pore-sized media from saturated to unsaturated states. By establishing different models to idealize pore structure characteristics (e.g. size and shape), the simulated NMR relaxation can clarify how pore structure affects the NMR relaxation, and how information about water distribution and pore structure are interpreted from NMR outcomes in unsaturated porous media.

Keywords: Nuclear magnetic resonance; porous media; water distribution; pore structure

How to cite: Zhou, J. and Zhang, C.: Pore Structure Affecting the NMR Relaxation in Unsaturated porous media , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8903, https://doi.org/10.5194/egusphere-egu24-8903, 2024.

EGU24-9432 | ECS | Orals | HS8.2.13

Electrical conductivity estimation from a new fractal model for porous media under reactive processes 

Mariangeles Soldi, Flore Rembert, Luis Guarracino, and Damien Jougnot

Near-surface geo-electrical methods monitoring the electrical conductivity have gained particular interest for environmental studies. Their sensitivity to key properties of storage and transport in porous media and their non-destructive nature make these methods a significant asset for studying the subsurface. Nevertheless, their quantitative interpretation depends on the efficiency of the used petrophysical relationship to link the physical properties, obtained from the electrical measurements, with the hydrological properties and state variables of interest. Therefore, the electrical conductivity of a porous medium is related to several geological parameters such as mineral matrix, porosity, permeability, and degree of water saturation. All of these parameters are controlled by the pore structure which plays a key role in the distribution of the conductive fluid. During reactive processes, the pore structure is significantly affected which translates into surface and volume variations. This evolution of the pore space leads to changes in the macroscopic hydraulic properties and, therefore, the electrical conductivity. In this study, we present an analytical fractal model to describe the electrical conductivity evolution during reactive processes. Under the assumption that the pore system is represented by a bundle of tortuous capillaries with constrictivity, we account for the reactive processes in the model by considering the geometrical variations in the pore structure (i.e., the increase and decrease of the pores aperture). The derivation of the electrical conductivity is based on upscaling procedures and a fractal law which describes the size distribution of pores. Considering the electrical charges dragged by the water in one capillary, we upscale the electrical property and obtain closed-mathematical expressions to calculate the electrical conductivity of the medium. This can be achieved thanks to the independence from scales of fractal media. For partially saturated conditions of the medium, the model’s expressions can estimate the electrical conductivity as a function of hydraulic properties. The performance of the model has been tested with published data from different soil and rock textures, under reactive fluid flow or partial saturation conditions. The comparison shows that the model can satisfactorily reproduce the behavior of the data. The fractal distribution is consistent with mico-CT results and the dissolution rate is within the same order of magnitude of the value obtained from experimental results. From a geometrical approach and within a fractal framework, we included the effect of reactive processes in the estimates of the medium electrical conductivity which opens up new possibilities to characterize media from geoelectrical techniques.

How to cite: Soldi, M., Rembert, F., Guarracino, L., and Jougnot, D.: Electrical conductivity estimation from a new fractal model for porous media under reactive processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9432, https://doi.org/10.5194/egusphere-egu24-9432, 2024.

We pioneer microscale geoelectrical acquisition with advanced microfabrication technologies to investigate hydrogeological processes using microfluidics that couples direct visualization of the pore scale dynamics with the geoelectrical response. Geoelectrical monitoring gives information at various scales (µm to m) about dynamic and reactive processes involving multiphase flow, solute transport, and mineral dissolution/precipitation, which rely on microscopic interactions. Yet, the field scale geophysical survey interpretation is challenging due to the superposition of the couplings and the heterogeneity of the natural environment. We focus on developing electrical conductivity monitoring with the spectral induced polarization (SIP) method. The interpretation of the SIP signal is based on developing petrophysical models that relate the complex electrical conductivity to structural, hydrodynamical, and geochemical properties. State-of-the-art petrophysical models, however, suffer from a limited range of validity and presume many microscopic mechanisms to define macroscale parameters. Thus, direct observations of the underlying processes coupled with geoelectrical monitoring are keys to deconvolute the signature of the bio-chemo-physical mechanisms at play and for using reliable models. Microfluidic experiments enable direct visualization of flows, reactions, and transport at the pore scale thanks to transparent micromodels coupled with high-resolution imaging techniques. Micromodels are a two-dimensional representation of the porous medium, ranging in complexity from single channels to replicas of natural rocks. Cutting-edge micromodels use reactive minerals to investigate the water-mineral interactions. Here, we investigate calcite dissolution, a key multiphase process involved, e.g., in karstification. Our micromodel is a channel containing a calcite grain in the middle. Thin gold electrodes are deposited on the bottom surface of the channel for SIP monitoring. We highlight the strong correlation between SIP response and dissolution through electrical signal examination and image analysis. In particular, degassed CO2 bubbles generated by dissolution play a critical role in the acid trajectory, the evolving calcite shape, and the decreasing real part of the complex conductivity. Then, we perform image processing to retrieve petrophysical parameters such as porosity and water saturation. These parameters are used as inputs to model the complex electrical conductivity with petrophysical modeling based on the concept of equivalent circuits representing bulk and surface conductivities. We show that the petrophysical model can be applied to pore scale geoelectrical monitoring and is consistent with optical observations. We show that the time variations are linked to partially saturated conditions, pore water composition, and evolving mineral surface state. These results demonstrate that the proposed technological advancement provides a breakthrough in understanding the subsurface processes through SIP monitoring.

How to cite: Rembert, F., Leroy, P., and Roman, S.: Microfluidic investigation of calcite dissolution with spectral induced polarization. Direct observation and petrophysical modeling., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11251, https://doi.org/10.5194/egusphere-egu24-11251, 2024.

EGU24-12001 | ECS | Orals | HS8.2.13

Bayesian sensitivity analysis of seismic data to van Genuchten parameters in unsaturated and unconsolidated soils 

Ramon Sanchez Gonzalez, Ludovic Bodet, Alexandrine Gesret, and Agnès Rivière

Increasing anthropogenic and climate pressures on water resources and thermal energy call for a better understanding of the transient water storage and the water fluxes within the Critical Zone (CZ). Recharge, as the main water inflow feeding groundwater (GW), is critical for the proper management of GW systems. GW recharge is defined as the water percolating from the last unsaturated horizon down to the water table and is therefore broadly inaccessible to direct observations. Recharge is spatially heterogeneous and controlled by multiple factors such as porous media properties and hydrogeological conditions. Hydrogeophysics provide valuable approaches to determining hydraulic parameters in unconsolidated and unsaturated soils. In this domain, electromagnetic and electrical methods predominate due to their obvious dependence on water content. While crucial for water-related assessments, the transition to mechanical properties emphasizes the complementary role of seismic techniques. Specifically, seismic refraction tomography and surface-wave dispersion analysis stand out in delimiting boundaries between saturated and unsaturated zones. Recent studies underscore the synergy of employing both 2D electrical and seismic methods, showcasing their collective efficacy in identifying hydrofacieses and delineating the water table. However, these techniques fall short of providing a detailed saturation profile in the unsaturated zone. Recent studies suggest to employ the Van Genuchten model, coupled with a rock physics model that incorporates capillary suction effects, to determine the mechanical properties of the soil, accounting for both depth and saturation dependencies. This method enables the analytical 1D modeling of both P- and S-wave velocities in various hydrofacieses with various water table depths (in static conditions). Then by utilizing these velocity models, it is possible to calculate synthetic P-wave travel times (P-TT) and surface-wave dispersion (SWD) from an artificial seismic setup. This constitute a forward problem from saturation versus depth models towards seismic data. In this study, we propose to do the inverse problem, e.g. estimating the VG parameters (VG) from P-TT and SWD. We use the database provided by Carsell and Parrish to compute synthetic observations in wide a priori ranges. We propose the employment of a straightforward grid search and formulate the results in a Bayesian framework. Our results indicate that both SWD and P-TT are responsive to changes in water saturation, allowing for the retrieval of the VG parameters from observed data. Moreover, our study highlights that the sensitivity of geophysical data varies with soil composition, particularly underscoring the complexities of estimating VG parameters in soils with a high sand content.

How to cite: Sanchez Gonzalez, R., Bodet, L., Gesret, A., and Rivière, A.: Bayesian sensitivity analysis of seismic data to van Genuchten parameters in unsaturated and unconsolidated soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12001, https://doi.org/10.5194/egusphere-egu24-12001, 2024.

EGU24-12830 | ECS | Posters on site | HS8.2.13

Designing and optimizing an Electrical Resistivity Tomography (ERT) time lapse acquisition for mapping hedgerow impacts on water transfers 

Hanifa Bader, Jean Marçais, Nadia Carluer, Laurent Lassabatere, Fanny Courapied, Arnold Imig, and Rémi Clément

Hedgerows have an a priori beneficial influence on hillslope hydrology in the context of climate change. Thanks to their root network, they enhance the infiltration of rainwater or upcoming runoff (Wallace et al., 2021). However, the fate of the water that infiltrates under the hedgerows has not been quantified: evapotranspiration, runoff, groundwater recharge, subsurface runoff to the watercourse. This is a crucial question to better understand the role of hedgerows in hillslope hydrology and the fate of associated contaminants. In this context, we plan to deploy a hydrogeophysical study based on Electrical Resistivity Tomography (ERT) time lapse to investigate the infiltration processes beneath a hedgerow located on a long-term observatory catchment near Lyon, France (Lagouy et al., 2015). Time-lapse ERT has significantly developed in recent years to provide quantitative measurements of subsurface properties and relevant information on hydrological processes, particularly water infiltration into soils (Brunet et al., 2011). Yet geophysical experimental setups are often designed heuristically and seldom optimized a priori (i.e. without specific optimization procedure beforehand). In our case, considering that the development of Open Source resistivity meter such as Ohmpi (Clement et al., 2020) will make it possible to monitor hydrological processes intensively, the aim is to optimize our acquisition strategy to obtain a compromise between the best image and a minimal acquisition time.

In order to ensure that our experimental hydrogeophysical setup is « data worth » and optimized for our field applications, we adapted a classical numerical approach to generate data (referred to as numerical experiments) to size and design our experimental parametrization of an ERT acquisition. Therefore, we investigate the unit of electrode spacing in order to (i) achieve the desired optimal resolution beneath the hedgerow (to enhance the monitoring of hydrological flows), (ii) maintain a sufficient depth of investigation (to visualize water table fluctuations and to study the soil and root properties of the hedgerows), and (iii) select the most appropriate electrode configuration (Wenner, Dipole-dipole, Schlumberger) for the specific studied site. To validate this approach, we simulated resistivity anomalies similar to those expected in the field (as the result of soil heterogeneity or soil wetting due to rainfall events and preferential flows). These simulations were rendered by ERT after the inversion step and compared to the prescribed field of electrical resistivity. The objective was to determine if we could detect these types of resistivity heterogeneities and which resistivity gaps were detectable. Besides these considerations, several key questions arise regarding the time of experimental design. Specifically, we tested different sequencing strategies to optimize measurements and minimize acquisition time. Finally, field tests will be conducted to validate this « data worth » experiment and validate the gain in acquisition time while minimizing the loss in ERT image rendering.

References

Brunet et al., 2010, Journal of Hydrology, 10.1016/j.jhydrol.2009.10.032.

Clément et al. 2020, HardwareX, 10.1016/j.ohx.2020.e00122.

Lagouy et al., 2015, 10.17180/OBS.YZERON.

Wallace et al., 2021, Hydrological Processes, 10.1002/hyp.14098.

 

How to cite: Bader, H., Marçais, J., Carluer, N., Lassabatere, L., Courapied, F., Imig, A., and Clément, R.: Designing and optimizing an Electrical Resistivity Tomography (ERT) time lapse acquisition for mapping hedgerow impacts on water transfers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12830, https://doi.org/10.5194/egusphere-egu24-12830, 2024.

EGU24-16241 | ECS | Posters on site | HS8.2.13

Data fusion and classification of electromagnetic induction and remote sensing data for management zone delineation in sustainable agriculture  

Salar Saeed Dogar, Cosimo Brogi, Marco Donat, Harry Vereecken, and Johan Alexander Huisman

A precise and reliable characterization of intra-field heterogeneity of soil properties and water content is vital in precision agriculture as these significantly impact crop growth and yield. Non-invasive hydrogeophysical methods such as electromagnetic induction (EMI) can be used to delineate intra-field agricultural management zones that represent areas where field characteristics tend to be homogeneous and have similar impact on crops. The combination with additional data sources, for example, remote sensing or yield maps, has the potential to improve the quality of the management zones. However, extracting subsurface information from multiple datasets and for large agricultural fields poses several challenges in data harmonization and analysis. The selection of optimal dataset combinations and the influence of different data products on the creation of management zones have also not been sufficiently investigated. In this study, we present an approach to produce intra-field management zones that combines a) electromagnetic induction (EMI) measurements performed with a CMD Mini-Explorer and a CMD Mini-Explorer Special-Edition (with 3 and 6 coil separation, respectively) and b) normalized difference vegetation index (NDVI) from PlanetScope satellite imagery. The method was tested on a 70-ha field of the PatchCrop experiment in Tempelberg, Brandenburg (Germany). This field is challenging to investigate as it contains 30 small patches of 0.5 ha (72 x 72m) that are managed separately. EMI measurements were collected in three different campaigns in 2022 and 2023 depending on the availability of these small patches. The EMI data were automatically filtered, temperature corrected, and interpolated onto a 1x1 meter resolution grid. Furthermore, EMI measurements were normalized by testing different methodologies (min-max, log, and z-transformation) to reduce the influence of measuring in different periods. Satellite NDVI maps with 3 m resolution for selected years within the period 2019-2023 were obtained from PlanetScope and provided information on crop development over the growing season. For validation, yield maps with 10 m resolution for the period 2011-2019 were available. Both the EMI and the NDVI maps revealed the presence of sub-surface heterogeneities that clearly impact plant productivity, but their patterns did not fully match. To delineate agricultural management zones, ISODATA and K-means clustering algorithms were employed by using a) EMI data, b) NDVI maps, and c) a combination of these datasets. Silhouette and elbow methods were used to identify the optimal number of clusters. The adequacy of the resulting management zones was assessed by comparing them to the available yield maps. The results revealed that a combination of EMI and NDVI datasets could often improve the spatial representation of yield patterns, which confirms the relevance of this method for precision agriculture. Nonetheless, further research is needed to assess the relevance of each dataset and to evaluate the applicability in different regions and contexts.

How to cite: Dogar, S. S., Brogi, C., Donat, M., Vereecken, H., and Huisman, J. A.: Data fusion and classification of electromagnetic induction and remote sensing data for management zone delineation in sustainable agriculture , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16241, https://doi.org/10.5194/egusphere-egu24-16241, 2024.

EGU24-17325 | ECS | Orals | HS8.2.13

Tracking shallow groundwater response to a pumping test using a dense passive seismic array  

Cécile Baudement, Antoine Guillemot, Eric Larose, Stéphane Garambois, Alexandra Royer, Etienne Rey, and Vincent Cappoen

Facing the societal issues related to water resources management, the development of ambient noise-based seismology for monitoring fluids in the subsurface is promising but still challenging (1). In this study, we propose a seismological monitoring of shallow groundwater with high spatial resolution, by applying ambient noise interferometry techniques. On a glacio-alluvial plain containing a shallow aquifer near Grenoble (France), we installed a dense array of 50 seismic nodes settled during five days. A pumping test was performed in a borehole during the experiment, inducing a fast and heterogeneous response of the aquifer. We estimated relative changes in surface wave velocity (dV/V) from autocorrelations of ambient noise recorded by the 50 sensors. During the pumping phase, dV/V increases by more than 10% near the borehole, indicating a significant decrease in pore pressure. Mapping the seismological response to pumping suggests a high channelization of the hydrogeological paths. Poroelastic modeling combined with active seismic campaigns improves the interpretation of observations (2), paving the way to a high-resolution time-lapse 3D mapping of the water dome and potential fluxes.

References

1 - Gaubert‐Bastide, T., Garambois, S., Bordes, C., Voisin, C., Oxarango, L., Brito, D., & Roux, P. (2022). High‐resolution monitoring of controlled water table variations from dense seismic‐noise acquisitions. Water Resources Research58(8), e2021WR030680.

2 - Voisin, C., Garambois, S., Massey, C., & Brossier, R. (2016). Seismic noise monitoring of the water table in a deep-seated, slow-moving landslide. Interpretation4(3), SJ67-SJ76.

How to cite: Baudement, C., Guillemot, A., Larose, E., Garambois, S., Royer, A., Rey, E., and Cappoen, V.: Tracking shallow groundwater response to a pumping test using a dense passive seismic array , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17325, https://doi.org/10.5194/egusphere-egu24-17325, 2024.

EGU24-17523 | Posters on site | HS8.2.13

Electrical resistance measurement strategies and their implementation in OhmPi 

Olivier Kaufmann, Arnaud Watlet, Guillaume Blanchy, Yannick Fargier, Hélène Guyard, and Rémi Clément

Various strategies can be envisaged to optimise the performance of an automatic resistivity meter when measuring electric resistances on a quadrupole. The objectives may be, for example, to maximise the signal-to-noise ratio of each measurement, to minimise the power delivered while ensuring that the voltage measured at the receiver reaches a fixed threshold, or to try to inject a given current independently of variations in the contact resistances. We describe how the variables controlled at the transmitter affect the signals received at the receiver as a function of the uncontrolled quantities during a soil resistivity measurement. We then propose some strategies for acquiring soil resistivity measurements based on these relationships, taking into account the physical characteristics and limitations of the transmitter and receiver. These strategies have been implemented in the software redesign included in version 2024 of OhmPi, an open-source resistivity meter.

How to cite: Kaufmann, O., Watlet, A., Blanchy, G., Fargier, Y., Guyard, H., and Clément, R.: Electrical resistance measurement strategies and their implementation in OhmPi, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17523, https://doi.org/10.5194/egusphere-egu24-17523, 2024.

EGU24-19108 | ECS | Orals | HS8.2.13

Monitoring 3D soil moisture dynamics at a karst forest site with OhmPi, an open source resistivity meter 

Arnaud Watlet, Olivier Kaufmann, Anthony Mahieu, Arnold-Fred Imig, Hélène Guyard, Pascal Goderniaux, Nicolas Forquet, Yannick Fargier, Vivien Dubois, Guillaume Blanchy, and Rémi Clément

Karst aquifers are particularly vulnerable to changes in environmental factors such as climate change or pollutants. In the critical zone, the role of the superficial layer, the soil and the so-called epikarst, is crucial as it can delay water infiltration and host temporary perched water reservoirs, due to high contrasts in hydraulic conductivity with deeper layers. In an effort to better characterise the effect of the plant activity on the water content in the shallow subsurface, we have designed a time-lapse ERT experiment at the Rochefort Cave Observatory (Belgium). We present results from (at least) 6 months of daily 3D ERT measurements on 64 electrodes installed in a 40x60 cm grid covering a 6.0 x 1.8 m surface area centred on a young beech tree. The ERT dataset is supported by data from a vertical profile of soil moisture probes and in-cave water percolation gauges. Our study also includes an artificial drying and sprinkling experiment which main purposes are to replicate extreme weather events and investigate their effect on the soil moisture condition.

This experiment also serves as a testbed for using OhmPi as a monitoring tool in the field. OhmPi is an open-source, open-hardware resistivity meter, which runs on a Raspberry Pi. It is designed for enabling flexible data acquisition, and is primarily dedicated to the research community. Relying on low-cost components and devices, and using a low-power injection module (0-50V), OhmPi is particularly suited for small-scale field and laboratory experiments.

How to cite: Watlet, A., Kaufmann, O., Mahieu, A., Imig, A.-F., Guyard, H., Goderniaux, P., Forquet, N., Fargier, Y., Dubois, V., Blanchy, G., and Clément, R.: Monitoring 3D soil moisture dynamics at a karst forest site with OhmPi, an open source resistivity meter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19108, https://doi.org/10.5194/egusphere-egu24-19108, 2024.

Lake Sibaya is the largest groundwater-fed freshwater lake in South Africa. In the past several decades the lake levels have declined substantially, largely due to drought, human water demands, and the expansion of eucalyptus plantations. These falling lake levels have resulted in the formation of isolated basins, most notably a northern main basin and a southern secondary basin, where water levels behave independently. The southern basin plays an important water resource and ecological role in the area, consequently, there is a need to better understand the groundwater-surface water connectivity and hydrogeological structure.

The area is characterized by a complex depositional system comprising dune and fluvial-deltaic sediments which makes understanding the groundwater and surface water connectivity non-trivial. To better understand the subsurface structure land and waterborne transient electromagnetic (TEM) surveys were conducted using a towed TEM system. The TEM method utilizes a transmitter and a receiver coil to estimate the subsurface resistivity distribution to depths of 50 – 70 m. Firstly, a primary electromagnetic field is generated by passing an electric current around the transmitter coil. The primary electromagnetic field induces currents in the subsurface which then generate a secondary electromagnetic field. The receiver coil then detects the secondary electromagnetic field. The rate of decay of this secondary electromagnetic field can be used to model the subsurface resistivity distribution. The resistivity models can be used with local borehole data to constrain geological boundaries in the survey area.

The resistivity models derived from the surveys, combined with borehole data, revealed distinct geological layers comprising organic sediments, sands, silts, and calcareous sandstones. Furthermore, whereas the northern basin is connected to the deeper aquifer, the southern basin is not. This work highlights the ability of high-productivity TEM methods to gain a better understanding of complex hydrogeological systems and provide context for their management.

How to cite: McLachlan, P.: Assessing groundwater-surface water connectivity using land and waterborne transient electromagnetic surveys, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20461, https://doi.org/10.5194/egusphere-egu24-20461, 2024.

EGU24-2753 | Orals | HS8.1.1

Release and Transport Characteristics of Heavy Metal Pollutants in Tailings Pond 

Jiaxu Jin, Pengfei Wu, Hongzhi Cui, and Xinlei Zhang

The lead-zinc tailings pond contains a significant concentration of heavy metal pollutants, such as lead, zinc, copper, chromium, cadmium, mercury, and arsenic. These pollutants exist in the form of ions within the tailings. External environmental factors can facilitate the release and transportation of these heavy metal elements from the tailings, resulting in pollution. The factors influencing pollutant release and variations in heavy metal tailings transport across different media were investigated by employing statistical analysis, leaching tests, and heavy metal soil column experiments based on the results of a case study on the Qingshan lead-zinc mining area. The multi-component solute release transport model for tailings to examine the interplay between concentration and seepage fields was constructed by considering hydrodynamics, mass transfer, and chemical reactions. The COMSOL software was performed to develop a customized model for the transport of heavy metal pollutants, wherein specific boundary conditions were set to enable quantitative analysis and interpretation of the release and migration of heavy metal solutes in tailings. The present study establishes a foundation for comprehending the migration patterns, pollution pathways, and mechanisms of heavy metal pollutants in tailings ponds. Furthermore, it provides indispensable technical support for addressing heavy metal contamination in lead-zinc mining regions and developing impermeable systems for tailings ponds.

How to cite: Jin, J., Wu, P., Cui, H., and Zhang, X.: Release and Transport Characteristics of Heavy Metal Pollutants in Tailings Pond, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2753, https://doi.org/10.5194/egusphere-egu24-2753, 2024.

Simulations of two-phase flow in heterogeneous porous media are crucial for several applications, such as CO2 sequestration, efficient oil and gas recovery, and groundwater pollution remediation. Modeling of two-phase flow systems becomes very challenging when capillary heterogeneity and hydraulic discontinuities are considered. Traditional models use numerical techniques such as finite difference, finite element, and finite volume for solving the partial differential equations of the system. Although numerical methods have been shown to produce reliable solutions for complex flow problems, they can become computationally expensive. This emphasizes the high computational demand for solving the inverse problem. The use of DNNs (deep neural networks) has become more common in predicting subsurface flow behavior. DNNs is a data-driven approach that enables the learning of a system by linking input and output parameters and provides fast predictions of dynamic, complex systems. Nevertheless, when data is extremely scarce, particularly in subsurface systems, standard DNNs are unable to yield robust results. Recent advancements enable the integration of physical constraints as partial differential equations (PDEs) into the DNNs scheme. Such a class of deep learning techniques is generally referred to as physics-informed neural networks (PINNs). PINNs are also capable to provide forward solutions for PDEs.  In this work, we examined PINNs' capabilities to provide forward solutions of a 1D steady-state two-phase flow with capillary heterogeneity at the sub-core scale. Here, we trained a PINNs system that incorporates high variability in the hydraulic properties and boundary conditions implemented as input parameters. We compared the PINNs results with numerical solutions to test the efficiency of the developed PINNs system. Results have shown that the trained PINNs system could reproduce both capillary pressure and phase saturation profiles for altering fractional flows, injection rates, hydraulic properties, and domain lengths with high accuracy and within a single training. Training the extended PINNs system was obtained in a few hours, and the post-trained system provided unlimited solutions for variable structures and boundary conditions within a few seconds. 

How to cite: Chakraborty, A. and Moreno, Z.: Simulating two-phase flow using Physics-informed neural networks with capillary heterogeneity and hydraulic discontinuities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3458, https://doi.org/10.5194/egusphere-egu24-3458, 2024.

The power mean is the generalization of the common averaging methods, such as harmonic, geometric and arithmetic mean, but also minimum and maximum. However, it also allows an infinite number of other means between these common means and can therefore be adapted very flexibly to the specific task of upscaling. This will be demonstrated in the contribution by calculating the effective thermal conductivity as the mean of the partial conductivities of soil components (typically of the solid, liquid, and gaseous phase). Soil thermal conductivity is a key factor for the soil heat balance and is widely used in many fields of science. However, it is elaborate to measure thermal conductivity of soils that have different porosities and degrees of saturation. Effective thermal conductivity of soil strongly depends on the arrangement of particles (soil structure) and on the interaction of added water to the solid phase (e.g., menisci).  To improve the prediction of soil thermal conductivity, specific information of soil structure needs to be taken into account. The relationship between the power mean exponents p and the degree of saturation is an indicator of the existing soil structure.

How to cite: Stange, C. F.: On the possibilities of the power mean as an upscaling method using the example of thermal conductivity in soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3853, https://doi.org/10.5194/egusphere-egu24-3853, 2024.

EGU24-4162 | Orals | HS8.1.1

Impact of an immobile, mobile and permeable phase on mixing-driven reactions in porous media 

Joaquin Jimenez-Martinez, Xueyi Zhang, Ishaan Markale, Dorothee Kurz, Zhi Dou, Maxence Carrel, Veronica Morales, and Markus Holzner

Understanding chemicals mixing and reactions in porous media is critical for many environmental and industrial applications. In the presence of a non-wetting immiscible phase (e.g., gas) within the pore space, it can remain immobile, giving rise to the so-called unsaturated flow, or it can move, resulting in a multiphase flow. In other cases, the immiscible phase can be permeable, as it occurs with biofilms growing within the pore space. We combine experiments and numerical modeling to assess the impact of saturation (fraction of the pore volume occupied by the wetting phase), multiphase flow (stationary two-phase flow), and the presence of permeable biofilm within the pore space on mixing-driven reactions. The product formation is larger for a given flow rate as saturation decreases, while for a given Peclet, it is the opposite. In multiphase flow conditions, for a given flow rate of the wetting phase, the product formation depends on the flow rate of the non-wetting phase. In the presence of biofilms, the product formation is enhanced compared to their absence and is further enhanced with a heterogeneous permeability within the biofilm.

How to cite: Jimenez-Martinez, J., Zhang, X., Markale, I., Kurz, D., Dou, Z., Carrel, M., Morales, V., and Holzner, M.: Impact of an immobile, mobile and permeable phase on mixing-driven reactions in porous media, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4162, https://doi.org/10.5194/egusphere-egu24-4162, 2024.

Plutonium (Pu) in the subsurface environment can transport in different oxidation states as an aqueous solute or as colloidal particles. The transport behavior of Pu is affected by the relative abundances of these species and can be difficult to predict when they simultaneously exist. This study investigates the concurrent transport of Pu intrinsic colloids, Pu(IV)(aq) and Pu(V-VI)(aq) through a combination of controlled experiments and semi-analytical dual-porosity transport modeling. Pu transport experiments were conducted in a fractured granite to elucidate sorption processes and their scaling behavior. In the experiments, Pu(IV)(aq) was the least mobile of the Pu species, Pu(V-VI)(aq) had intermediate mobility, and the colloidal Pu, which consisted mainly of precipitated and/or hydrolyzed Pu(IV), was the most mobile. The semi-analytical modeling revealed that the sorption of each Pu species was rate-limited, as the sorption could not be described by assuming local equilibrium in the experiments. The model was able to describe the sorption of the different Pu species that occurring either on fracture surfaces, in the pores of the rock matrix, or simultaneously in both locations. While equally good fits to the data could be achieved using any of these assumptions, a fracture-dominated process was considered to be the most plausible because it provided the most reasonable estimates of sorption rate constants. Importantly, a key result of this work is that the sorption rate constant of all Pu species tends to decrease with increasing time scales, which implies that Pu will tend to be more mobile at longer time scales than observations at shorter time scales suggest. 

How to cite: Zhang, X.: Plutonium reactive transport in fractured granite: Multi-species experiments and simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4230, https://doi.org/10.5194/egusphere-egu24-4230, 2024.

Contamination with mono-aromatic hydrocarbons, specifically benzene, toluene, and xylenes (BTX), is one of the major concern to groundwater aquifers. BTX have high environmental stability and are harmful to human health and aquifer ecosystem. Thorough assessment and monitoring of the risk posed by BTX in aquifers are essential for the sustainable use of groundwater resources. The biodegradation of BTX in aquifer rely primarily on anaerobic processes. Nitrate-sulfate-reducing assemblages is considered for BTX bioremediation in such anoxic condition. These assemblages act as a terminal electron acceptor for bacterial respiration. The degree of the interaction between combinations of nitrate-sulfate reduction and BTX elimination determines the efficacy of BTX biological degradation. The interactions, however, received limited attention in the existing literature. Hence, the current analysis focuses co-existence of nitrate-sulfate assemblages affecting BTX bioremediation. A multi-component numerical simulation is performed to investigate the potential of nitrate-sulfate-assemblages for bioremediation of BTX in anoxic conditions. A fully implicit finite-difference novel approach is adopted here to solve the proposed numerical model, which is capable of obtaining spatial variation in BTX concentrations. The results suggest that bioremediation is efficient in removing toxic BTX from aquifers under the coexistence of nitrate-sulfate assemblages. This approach, in addition, can be used in deciding the optimum rate of electron acceptor injection and the time required to bring BTX to standard limits. Furthermore, it can help us to plan sustainable bioremediation strategies for mono-aromatic hydrocarbon contaminated aquifers where such reduction assemblages co-exist. This hydrogeobiochemical modelling study also emphasizes the importance of multidisciplinary methods in dealing with challenging environmental issues in the contaminated aquifers.

Keywords: Hydrogeobiochemical modelling; Bioremediation; BTX; Nitrate-sulfate assemblages; Aquifers.

How to cite: Srivastava, A., Valsala, R., and Jagadevan, S.: Hydrogeobiochemical Modelling for Bioremediation of Mono-Aromatic Hydrocarbons Using Nitrate-Sulfate-Reducing Assemblages in Aquifers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4243, https://doi.org/10.5194/egusphere-egu24-4243, 2024.

EGU24-4880 | ECS | Orals | HS8.1.1

Experimental Investigation on Dispersion Within Porous Media Influenced by Particle sizes and Pore-Scale Heterogeneity 

Jiyoung Baek, Byeong-Hak Park, Gabriel Rau, and Kang-Kun Lee

As heat tracing gains versatility in hydrogeological applications, precise thermal dispersion modeling becomes essential. However, limited experimental data for thermal dispersion, influenced by several factors such as particle size or shape, poses a challenge to the understanding of the relationship between flow velocity and thermal dispersion coefficient. To fill these gaps, the solute and heat tracer experiments were conducted using two different sizes of sand. Thermal and solute dispersion were analyzed by applying analytical models. We also systematically collected and revisited literature data to comprehensively interpret the influences of particle size, shape, and pore-scale heterogeneity on dispersion. The results exhibited that the solute and thermal dispersivity were comparable when the dispersion linearly increased to the velocity. However, within the transition regime (Pe < 5), a departure from linearity was observed (R2 < 0.9). The deviation was more pronounced in smaller particle size due to pore-scale heterogeneity arising from the complexity of pore network. Consequently, our findings emphasize the potential necessity for caution when modeling thermal dispersion based on solute dispersion within natural porous materials.

Keywords: Particle size; Thermal dispersion; Pore-scale heterogeneity; Transition regime; Sandbox experiment

 

Acknowledgements

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2022R1A2C1006696). This work was also supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government(MSIT) (No. 2022R1A5A1085103). This work was also supported by the Nuclear Research and Development Program of the National Research Foundation of Korea (NRF-2021M2E1A1085200).

 

How to cite: Baek, J., Park, B.-H., Rau, G., and Lee, K.-K.: Experimental Investigation on Dispersion Within Porous Media Influenced by Particle sizes and Pore-Scale Heterogeneity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4880, https://doi.org/10.5194/egusphere-egu24-4880, 2024.

This study experimentally demonstrates the impact of water and solute influx magnitude, and its resulting local distribution, on transport at timescales longer than the influx duration, through a disparate velocity field of a partially saturated domain. In a sand-filled cell, steady-state flow is maintained with a constant horizontal hydraulic head, while the upper part of the cell is partially saturated. The horizontal velocity varies by orders of magnitude from the surface to the saturated zone. An influx of water with a dissolved tracer is applied at the middle of the upper boundary surface, over several minutes, forming a plume that reaches a depth of a few centimeters. This influx disturbs the flow field locally, but after it is terminated, the return to steady-state flow is of the order of magnitude of the influx timescale. Eventually, the solute flows to the saturated zone and out of the cell through a path on the scale of decimeters, over a time scale of days. Employing ICP-MS as a sensitive measurement tool to detect highly diluted concentrations of solute enables tracking of a small influx volume that does not significantly perturb the flow field. This maintains a separation between the distinct spatial-temporal scales of the short-term local infiltration and the long-term system-scale transport. Applying varying influx magnitudes sets the solute plume across different velocity profiles and thus dictates the downstream plume distribution. A low influx relative to the hydraulic conductivity of the partially saturated sand allows solutes to infiltrate farther down compared to a higher influx, so that the plume reaches higher flow velocities but also spans a wider velocity variability. A higher influx relative to the hydraulic conductivity leads to a local increase in saturation, but a shallower depth of infiltration compared to the lower influx, and the system accordingly exhibits a more uniform plume located at a lower velocity region. In downstream solute concentration measurements, these influx variations result in a faster but more smeared breakthrough for the lower influx compared to a slower and more uniform breakthrough for the higher influx, corresponding to their initial distribution after infiltration.

How to cite: Kalisman, D., Dror, I., and Berkowitz, B.: From infiltration to steady-state flow in partially saturated media – bridging solute transport between millimeter-decimeter and minute-day scales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5615, https://doi.org/10.5194/egusphere-egu24-5615, 2024.

EGU24-5866 | ECS | Posters on site | HS8.1.1

The Effect of Time-Varying Soil Properties Caused by Ploughing and Consolidation on Pesticide Fate in Soil and Groundwater 

Pavan Cornelissen, Louise Wipfler, Maarten Braakhekke, and Marius Heinen

Soil properties such as the dry bulk density and soil hydraulic parameters can significantly affect the environmental fate of pesticides. These properties are often assumed to remain constant in time in numerical models. In reality, however, these properties change over time due ploughing and consolidation. In this study, we modeled the time-varying soil properties induced by ploughing and consolidation and assessed its effect on pesticide accumulation in the topsoil and leaching to the groundwater. For this purpose, time-dependent soil properties have been implemented in the hydrological model SWAP and the pesticide fate model PEARL. Ploughing instantaneously decreases the bulk density, after which it gradually increases again to its original value due to consolidation caused by rainfall. The time-dependent soil properties are modelled based on empirical relationships between the dry bulk density and the Mualem-Van Genuchten parameters found in the literature.

Ploughing leads to a short-term deviation of the soil water content and concentration compared to the reference case (i.e., the case with constant soil properties). We included mixing of pesticide over the ploughing layer due to ploughing in both cases. However, under Central European climate conditions, the effect of ploughing vanishes within several months in the entire soil profile. For assessing the impact on the leaching of pesticide to groundwater, we evaluated the pesticide concentration in pore water at 1 meter depth. The effect of time-varying soil properties due to ploughing and consolidation on the leaching concentration was found to be small for both a tracer and an adsorbing solute. Even for an extreme case with three ploughing events per year, the effect on the 90th-percentile of daily leaching concentration was smaller than 0.3%. For assessing the impact on the exposure of soil organisms to pesticides, we considered the pesticide concentration in pore water averaged over the upper 20 centimeters of the soil. For the tracer, ploughing resulted in a 1.2% decrease of the 90th-percentile of daily topsoil concentration data for the extreme case of three ploughing events per year. Interpretation of the results for adsorbing solutes in the topsoil is hampered by the fact that soil mass is not conserved in the current approach. More advanced models must be developed that allow for conservation of soil mass for assessing the impact of time-dependent soil properties on concentrations in the topsoil.

How to cite: Cornelissen, P., Wipfler, L., Braakhekke, M., and Heinen, M.: The Effect of Time-Varying Soil Properties Caused by Ploughing and Consolidation on Pesticide Fate in Soil and Groundwater, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5866, https://doi.org/10.5194/egusphere-egu24-5866, 2024.

EGU24-7503 | Orals | HS8.1.1

Dynamics of aeration zone mobile inventory preshape groundwater quality evolution - results from multi-year sampling of regolith seepage  

Katharina Lehmann, Dinusha Eshvara Arachchige, Robert Lehmann, and Kai Uwe Totsche

The aeration zone (AZ) below the soils sensu stricto is still neglected compartment regarding its structure, diversity of life and habitats, and role for the provision of ecosystem services. Especially in thick AZ of topographic recharge areas, fluid flow dynamics and the exchange of the total mobile inventory (Lehmann et al. 2021) and their roles for the quality-evolution of groundwater are largely unknown. In the low-mountain topographic recharge area of the Hainich Critical Zone Exploratory (central Germany), we study spatiotemporal dynamics of the fluid fluxes and mobile inventory within the shallow (upper) AZ (regolith) and compare their signature with soil seepage and perched groundwater (deeper AZ). Percolates from 20 drainage collectors (DC) covering a diversity of Triassic mixed carbonate-siliciclastic (sedimentary) bedrock, soil types, and installation depths were sampled for more than 3 years on regular (monthly) and event-based basis and analyzed by various physico-/hydrochemical and spectro-microscopic techniques.

On average, the DC captured ~13% of the percolate from the forest topsoil seepage and 2.4% of precipitation. Seepage volume was mainly influenced by the factors soil thickness and sampling month, followed by scarp slope gradient and seasonal differences. In the upper AZ, the mobile inventory exhibited strong seasonality (e.g. EC, pH, nitrate, sulphate, K, Si, Mn, Al, Fe, particle concentration) and were more dependend on seasonal weather conditions and single (extreme) events (e.g., snow melt, rain events) than on lithology, followed by site-specific structural factors (location, slope), or pedological settings (e.g. overburden soil type, soil thickness). Generally, our results show fluid-rock interactions within the upper AZ with a more similar hydrochemical water signature to perched groundwater. Contrastingly, particulate mobile inventory showed a strong connection to soil seepage signature, comprising a diverse spectrum of mineral particles (mainly clay minerals) and mineral- and mineral-organic associations up to 160 µm, including aggregates and microorganisms. The different flow regimes that prevail during different seasons and weather conditions mainly influenced the amount and spectrum of percolate mobile inventory. During summer, dry periods in conjunction with extreme precipitation events favored translocation of small-sized particles. In winter, fast-flow regimes during normal precipitation as well as during snowmelts contributed strongly to the translocation of organic/inorganic carbon and mineral particle through the AZ and to groundwater. We conclude that the AZ is a complex biogeochemical reactor, that severely alters the percolate composition and properties, already preshaping the biogeochemical groundwater quality as well as due to its functions and services (e.g. water-purification and storage). As such, the aeration zone hast to be considered as a crucial compartment for groundwater quality evolution, especially in topographic recharge areas.

 

Lehmann, K., Lehmann, R., Totsche, K. U. (2021) Event-driven dynamics of the total mobile inventory in undisturbed soil account for significant fluxes of particulate organic carbon. Sci. Total Environ. 756, 143774, doi: https://doi.org/10.1016/j.scitotenv.2020.143774

How to cite: Lehmann, K., Eshvara Arachchige, D., Lehmann, R., and Totsche, K. U.: Dynamics of aeration zone mobile inventory preshape groundwater quality evolution - results from multi-year sampling of regolith seepage , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7503, https://doi.org/10.5194/egusphere-egu24-7503, 2024.

Two-phase flow in geological fractures holds significant relevance in various applications, including subsurface fluid storage and oil and gas exploitation. The pore-scale modelling of such flows is a challenging task influenced by many factors, such as the complex interplay between the viscous, capillary, gravitational and inertial forces, intricate geometries, as well as molecular scale phenomena such as moving contact lines and thin wetting films. Although various modelling approaches have been used to tackle these challenges, the high computational demands required to accurately capture the three-dimensional fluid-fluid interfacial dynamics often render these models impractical for real-world applications. Consequently, from a practical point of view, the simplification of these 3D models may become imperative to facilitate efficient and reasonably accurate predictions of flow quantities.

Depth-integrated two-dimensional modelling is one such approach which enables saving computational time and effort at the expense of not resolving the third dimension. Here, the governing equations are solved in two dimensions, the influence of the third dimension being incorporated through appropriate additional terms. While such models have been used previously, they have so far been restricted to either permanent single-phase flow in rough fractures or two-phase flow in 2D porous media of homogeneous depth. In a rough fracture, the fluid-fluid interface possesses not only an in-plane curvature but also an out-of-plane curvature, which must be accommodated in the 2D depth-integrated model. Therefore, to address the immiscible flows in rough fractures it is essential to reformulate the 2-D depth-integrated approach from the first principles.

To perform the depth integration, we proceed from the traditional direct numerical simulation (DNS) approach, where the Navier-Stokes equations, coupled with an interface capturing technique, which in our case is the Volume of Fluid (VOF), are solved numerically. We integrate the governing flow equations in the vertical direction while expressing the flow fields in terms of 2D depth-averaged flow quantities. To account for the out-of-plane curvature and the wall shear stress arising from the no-slip conditions on the fracture walls, we assume locally a plane Poiseuille configuration (Hele-Shaw). 

The derived 2D depth-integrated model is implemented in the open-source CFD code OpenFOAM. We validate our model using the Saffman-Taylor instability case, comparing predictions with experiments and full 3D model results. We then extend our study to two numerically generated rough fractures with (a) smoothly and periodically varying aperture and (b) a more realistic aperture field with a larger roughness. We investigate drainage (i.e., the displacement of the wetting fluid by the non-wetting fluid) over a range of Capillary numbers spanning more than three orders of magnitude. We compare our 2D model predictions of both, pore-scale and macroscopic flow variables, with those obtained using 3D simulations. Our 2D model accurately estimates key statistical indicators with a tenfold reduction in computation time, offering an excellent compromise between solution accuracy and computational efficiency. We also discuss the limitations of the depth-averaged model depending on flow ranges.

How to cite: Krishna, R., Meheust, Y., and Neuweiler, I.: Depth-integrated Two-dimensional Model for Immiscible Two-phase Flow in Open Rough-walled Fractures with Smoothly Varying Aperture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7889, https://doi.org/10.5194/egusphere-egu24-7889, 2024.

Evaporation of soil water depends not only on climatic conditions, soil texture, and soil hydraulic properties but also on the soils’ macro-structure. Often, evaporation is characterised by water losses over time for a defined soil volume where soils are assumed to be homogeneous in texture and structure. In this study, we investigated the potential and limitations of 3D modelling of evaporation processes on soil cores with structural features ≥ 480 µm determined by X-ray computed tomography (X-ray µCT). The method was tested for two contrasting soil structures (ploughed vs. non-ploughed grassland) which experienced structural changes due 19 cycles of freezing and thawing. For all real soil samples, we simulated three different conditions of atmospheric demand with Hydrus 3D. It was hypothesised that the different distribution of air-filled macro-pores, the macro-connectivity of soil matrix and the surface area will affect bare soil evaporation and more specific the transition from stage 1 to stage 2 evaporation. To evaluate the effect of soil macro-structure on the column scale, we investigated the spatial distribution of water content and water fluxes. The combination of X-ray µCT and HYDRUS 3D was able to capture the effect of ploughing and freezing-thawing on soil macro-structure and to quantify the effect on the water dynamics inside the samples for various atmospheric demands and thus the feedback with evaporation.

How to cite: Leuther, F. and Diamantopoulos, E.: The effect of soil macro-structure on bare soil evaporation – using HYDRUS 3D simulation on X-ray µCT determined soil structures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8091, https://doi.org/10.5194/egusphere-egu24-8091, 2024.

EGU24-8793 | Posters on site | HS8.1.1

Advancing Irrigation Strategies: Synergistic Modeling of Soil Moisture Using Cosmic-Ray Neutron Sensing, Hydrus-1D, and Machine Learning 

Salvatore Straface, Guglielmo Federico Antonio Brunetti, and Andrea Scozzari

Innovative monitoring techniques today facilitate advanced and reliable measurements in the vadose zone. This, coupled with the predictive capabilities of machine learning, has an ever-growing impact on the management of agricultural and irrigation practices. The vadose zone, particularly the root zone, plays a pivotal role in hydrological processes by regulating water and energy fluxes across the soil surface. Additionally, it influences nutrient transport, groundwater recharge, groundwater pollution, microbial activity, and plant physiology, as it links the atmosphere, soil, and groundwater. Among various monitoring techniques, Cosmic-Ray Neutron Sensing (CRNS) stands out as a ground-based remote sensing technique capable of measuring soil moisture within the root zone at relevant scales (up to 240 m) with a high level of reliability. It is based on nuclear interactions between incoming cosmic rays and elements in the Earth’s atmosphere, such as hydrogen. By employing the Hydrus-1D Cosmic module, effective soil moisture values can be derived based on the neutron intensity detected by Cosmic-Ray Neutron Probes (CRNPs). On the other hand, machine learning methods and neural networks (NN) hold enormous potential despite inherent limitations, notably the requirement for extensive datasets and their lack of a physical foundation in reproducing soil processes. In this study, we propose a synergistic approach to overcome these limitations. The physically-based Hydrus-1D model was utilized to train a single-layer NN for the direct prediction of soil moisture and irrigation water demand, relying exclusively on atmospheric forcings (temperature and precipitation) as input. In a proof-of-concept aimed at assessing the validity and robustness of our approach, a time series of synthetic data replicating soil characteristics, atmospheric forcings, and field measurements conducted through CRNPs was generated. These data were employed in the Hydrus-1D Cosmic module to calibrate a physically-based model, facilitating the generation of a continuous and extensive spatiotemporal soil moisture output dataset for the simulated synthetic field. The single-layer NN, trained with this synthetic soil moisture and atmospheric forcing data, demonstrated the potential to accurately predict soil moisture and irrigation needs of the terrain straightforwardly, using only atmospheric variables as input. The proposed synergistic approach has exhibited significant potential, and future developments in this research will involve the incorporation of real data.

How to cite: Straface, S., Brunetti, G. F. A., and Scozzari, A.: Advancing Irrigation Strategies: Synergistic Modeling of Soil Moisture Using Cosmic-Ray Neutron Sensing, Hydrus-1D, and Machine Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8793, https://doi.org/10.5194/egusphere-egu24-8793, 2024.

EGU24-9159 | ECS | Orals | HS8.1.1

Assessing glyphosate movement through different agricultural systems with a shallow water table: insights from an inverse dual permeability model 

Giovanna Piazzon, Matteo Longo, Sebastiano Rocco, Francesco Morari, and Nicola Dal Ferro

The movement dynamics of glyphosate (GLY) in soil can be highly complex and challenging to predict, because its high water solubility and strong propensity to soil particle adsorption can interact with agricultural management practices, e.g. tillage operations and water table management. This can make GLY i) sensitive to nonuniform leaching via preferential flow paths into the groundwater before it can degrade, ii) difficult to model according to uniform flows. The aim of this study was to understand GLY dynamics in different agricultural systems of the low-lying Venetian plain, by calibrating a dual permeability model embedded in HYDRUS-1D using a series of GLY experimental data that were collected in the field, and compare it with a dual porosity mobile-immobile approach. Experimental data came from eight drainable lysimeters, where two shallow water table depths (60 cm and 120 cm deep) were compared in conventional (CV) and conservation agriculture (CA) systems as representative of the low-lying Venetian plain conditions (NE Italy). On May 2019, GLY and a tracer (KBr) were applied on bare soil (in CV) and rye that was used as a cover crop, in CA. After the distribution, soil (0-5, 5-15 cm deep) and soil-pore water (15, 30, 60 cm deep) samples were collected for 48 days to follow solutes dynamics. At the same depths, soil moisture and matric potential were monitored using TDR probes and electronic tensiometers. An automated system modulated the suction through matric potential readings combined with an electronic vacuum regulator. The HYDRUS 1-D software package was employed for inverse modelling of soil properties, first through parameterization and matric potential results, while solute movement parameters were calibrated based on GLY and KBr results from soil and water samples. Experimental results showed that GLY was found at different depths, especially soon after its distribution as dependent on intense rainfall events. The MIM model failed to predict any GLY movement, due to its high adsorption coefficient that hindered any GLY exchange between the immobile and mobile phases. In fact, experimental observations revealed that a preferential flow occurred down to the deepest layers (60 cm deep), even in the presence of poorly structured soil and irrespective of both the groundwater level and the cultivation system. In contrast, the dual permeability model provided a more accurate description of GLY dynamics in soil, successfully predicting the observed bypass flow timing experiment. Therefore, dual permeability model seems crucial for describing GLY dynamics in agroecosystems, enabling more accurate predictions of its potential pathways. 

How to cite: Piazzon, G., Longo, M., Rocco, S., Morari, F., and Dal Ferro, N.: Assessing glyphosate movement through different agricultural systems with a shallow water table: insights from an inverse dual permeability model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9159, https://doi.org/10.5194/egusphere-egu24-9159, 2024.

EGU24-9503 | ECS | Orals | HS8.1.1

Reservoir characterization by push-pull tests employing Kinetic Interface Sensitive tracers 

Huhao Gao, Alexandru Tatomir, Hiwa Abdullah, and Martin Sauter

The kinetic interface-sensitive (KIS) tracer test is a newly developed tracer approach to measure the fluid-fluid interfacial area (IFA) during dynamic two-phase flow in porous media. This new tracer approach can be applied for multiple geological applications, where dynamic two-phase flow is involved, e.g. monitoring the plume during geological storage of carbon dioxide. The obtained concentration breakthrough curves by measuring reacted tracer concentration in water samples are interpreted with a specialized Darcy-scale numerical model to determine the IFA. The previous design of the drainage experiments has one major limitation that the volume of the usable water sample after breakthrough for the measurement is often insufficient. An alternative is to employ KIS tracers in a “push-pull” experimental set-up, i.e. primary drainage is followed by a consequent main imbibition process, with the flow direction being reversed. This study applies both the pore-scale numerical simulation and the core-scale column experiments to study the KIS tracer reactive transport during push-pull processes. The pore-scale numerical simulation is done with a phase-field method-based continuous species transport model. The reactive transport of the tracer and the characteristics of the concentration breakthrough curves are analyzed. The Darcy-scale reactive transport model is validated by comparing it to the pore-scale results. Finally, the new method is applied in the column experiment, where the determined specific interfacial area is found to be close to the literature data.

How to cite: Gao, H., Tatomir, A., Abdullah, H., and Sauter, M.: Reservoir characterization by push-pull tests employing Kinetic Interface Sensitive tracers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9503, https://doi.org/10.5194/egusphere-egu24-9503, 2024.

Soils are complex systems where different physical, chemical and biological processes occurring simultaneously and interact in a non-linear way. This includes the diffusion process, which is known to be affected by the tortuosity, and therefore the water content. Additionally, the high degree of soil heterogeneity poses significant challenges in studying soil reactivity due to its high impact on mixing. In this study we evaluate the effect of a series of what we could be key controlling factors of effective reaction rates in soils at the plot scale: the degree of heterogeneity, the hydraulic structure, the reaction rate, the initial distribution of reactants, and the heterogeneity in the diffusion coefficient.

We tackle this by explicitly simulating hypothetical biomolecular soil reaction (A+B C) for different degrees of heterogeneity, different hydraulic structures, different reaction rates, different initial distribution of the reactants and different representation of diffusion. Results are evaluated in terms of effective reaction rates at the plot scale.

The simulation results reveal that mixing conditions control reactions in unsaturated soils. Non-ideal reactivity due to mixing-limited conditions is not only a consequence of the simple presence of heterogeneity or even of its intensity. Instead, it results from (at least): the characteristics of heterogeneity, the Pe number, the Da number, the spatial distribution of the reactants. Interestingly, the spatial variability of the (tortuosity-dependent) diffusion coefficient appears to also have a significant effect on mixing conditions.  

By these results, we illustrate the high complexity of reactive systems in unsaturated soils, which makes the use of average macroscopic reaction rates (as in most agriculture, environmental and geoengineering models) at least questionable.

How to cite: Henri, C. and Diamantopoulos, E.: What control reactions in unsaturated soils? On the dynamic effect of small-scale heterogeneity and (spatially variable) diffusion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9957, https://doi.org/10.5194/egusphere-egu24-9957, 2024.

EGU24-10423 | ECS | Posters on site | HS8.1.1

Disentangling nitrogen turnover in Nature Based Solutions: hydrodynamic properties and reactive behavior  

Ludovica Presta, Giuseppe Brunetti, Christine Stumpp, Michele Turco, and Patrizia Piro

Nature Based Solutions (NBS) are known to play a key role in urban water management by increasing the infiltration, retention, and evapotranspiration capacity of urban areas. However, their potential use for contaminant removal has only been partially investigated. To address this issue, this study presents an experimental analysis of the nitrogen turnover in selected typical NBS substrates. Soil column experiments were combined with laboratory methods to characterize the hydrodynamic properties of porous media and elucidate the nitrification process in NBSs. In a first experimental campaign, saturated soil columns were injected with a natural tracer (deuterium) to characterize non-reactive solute transport in different substrates. Breakthrough curves exhibit significant tailing, thus suggesting the existence of a complex interplay between a mobile and an immobile domain. A second experimental campaign was carried out in larger unsaturated soil columns periodically injected with wastewater. Nitrogen species were measured in the effluent to describe the nitrogen turnover in soils. Results are characterized by two distinct phases, in which nitrate is initially not detectable in the outflow but later becomes the dominant species. This behavior indicates the existence of an initial microbial adaptation phase, followed by an efficient nitrification process supported by the oxic conditions in the substrate. Altogether, observations highlight the complex hydraulic and reactive behavior of NBSs substrates, which should be properly combined with modeling to better understand and design NBS systems for pollutant treatment.

How to cite: Presta, L., Brunetti, G., Stumpp, C., Turco, M., and Piro, P.: Disentangling nitrogen turnover in Nature Based Solutions: hydrodynamic properties and reactive behavior , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10423, https://doi.org/10.5194/egusphere-egu24-10423, 2024.

EGU24-12231 | ECS | Posters on site | HS8.1.1

An Experimental Technique for Measuring Spatiotemporal pH and Carbon Concentration During Density-Driven Convection of CO2 in Water 

Yao Xu, Marcel Moura, Hilmar Yngvi Birgisson, and Knut Jørgen Måløy

Density-driven convection of CO2 in water will trigger the spatiotemporal evolution of pH and carbon concentration, impacting the understanding of CO2 dissolution and implementations of geological carbon sequestration. Building upon the conventional methodology which applies a single pH indicator and Schlieren imaging analysis, the enhanced experimental technique, offering a holistic view of CO2 convection within water, resulted in an accurate and visual representation of the CO2 plume propagation and a wider range of pH alteration and carbon concentration during CO2-water interactions. In response to the broad pH variations with continuous CO2 dissolution, this study utilized three pH indicators combined with the novel image analysis method to correlate the solutions’ colors to their pH. Afterwards, the carbon concentration is derived from the pH values by employing the pseudo-equilibrium theories. Leveraging an experimental technique and analytical tools to measure the spatiotemporal pH and carbon concentration, the research aims to deepen the understanding of CO2 convection behaviors, paving the way for enhanced insights into carbon sequestration and related environmental processes.

Keywords: Carbon sequestration, CO2 convection, density-driven, pH, carbon concentration

How to cite: Xu, Y., Moura, M., Birgisson, H. Y., and Måløy, K. J.: An Experimental Technique for Measuring Spatiotemporal pH and Carbon Concentration During Density-Driven Convection of CO2 in Water, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12231, https://doi.org/10.5194/egusphere-egu24-12231, 2024.

Water flow in the vadose zone is strongly non-linear due to the feedback of water flow, saturation, and the associated hydraulic conductivity. Therefore, the simulation of unsaturated flow at the continuum scale is notoriously complicated. Yet, not only the solution of the non-linear partial differential equation itself is difficult, also the appropriate parameterization of the unsaturated hydraulic conductivity function poses a challenge. Frequently, hydraulic conductivity is estimated from the water retention curve using capillary bundle models such as the well-established Mualem model or from pedotransfer functions that hardly include information on the actual pore space morphology. Here, a novel approach is presented to estimate the full unsaturated hydraulic conductivity function from a morphological analysis of Xray-CT images in the following way. First, the local pore space morphology is evaluated to obtain pore radius, Euclidean distances to the pore wall, and connectivity measures. Then, a local hydraulic conductivity and capillary forces are calculated for individual voxels of the images. This already permits to estimate the water retention curve and the water distribution inside the pore space at different levels of saturation. These configurations are then used to calculate an associated continuum scale hydraulic conductivity from dry to fully saturated conditions. This approach can be implemented in image analysis software, e.g. ImageJ, in a straight-forward way and may provide much better and specific estimates of the unsaturated hydraulic conductivity that sensitively affects the simulation of fluid flow in soils and the vadose zone provided satisfactory pore space acquisition with Xray-CT is possible.

How to cite: Ritschel, T.: Estimation of unsaturated hydraulic conductivity from morphological analysis of Xray-CT images, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14615, https://doi.org/10.5194/egusphere-egu24-14615, 2024.

EGU24-14907 | ECS | Orals | HS8.1.1

Mixing-induced reactive transport experiments in heterogeneous and variably saturated porous media 

Oshri Borgman, Francesco Gomez, Tanguy Le Borgne, and Yves Méheust

Mixing-induced reactions are an essential feature of environmental flow and transport processes. They control many reactive transport processes, including mineral precipitation rates and contaminant remediation processes. Natural porous media are characterized by a strong structural heterogeneity, which impacts solute mixing and, therefore, the resulting chemical reaction rates. Establishing a quantitative link between pore-scale heterogeneity and mixing/reaction rates in saturated and unsaturated conditions remains an open question. Here, we study pore-scale solute mixing using high-resolution experimental measurements to quantify the overall reaction rates and product concentrations. Our goals are to study the impact of structural heterogeneity on 1) reaction rates and products during saturated flow and 2) the spatial arrangement of fluid phases during unsaturated flow and its impact on reaction rates and products.

We use two-dimensional porous media consisting of circular posts in a Hele-Shaw-type flow cell. We control heterogeneity by varying the posts’ diameters disorder and correlation length; increasing this length introduces more structure in the porous medium. We utilize an irreversible oxidation reaction to produce fluorescein from its non-fluorescent form. The Damköhler number is sufficiently larger than unity, so the reaction rate is mixing-controlled. We inject a non-fluorescent tracer pulse into the porous medium sample filled with the oxidating reactant under saturated and unsaturated flow conditions. We analyze periodic fluorescence intensity images to track the evolving solute concentration field. The reaction rates and the total reaction product mass are calculated directly from the concentration images.

Solute concentration images show that increasing the spatial correlation length under saturated flow conditions leads to enhanced reaction front stretching and elongation as the solute travels along preferential pathways. Due to this overall stretching, the reaction front is locally more compressed perpendicular to the elongation direction. In a non-correlated, randomly disordered porous medium, overall stretching is reduced, and the front is less compressed locally. Under unsaturated flow conditions, a main preferential flow path characterizes the correlated porous medium. In contrast, the non-correlated medium is characterized by a higher degree of branching and splitting in the velocity field. Solute pulse focusing in the correlated porous medium sample reduces reaction front stretching compared to the non-correlated porous medium, under unsaturated conditions. Under these conditions, the reaction rate increases more than the saturated case due to the unsaturated flow pattern's enhanced reaction front stretching. This effect is more pronounced for the non-correlated sample, where flow path splitting and reaction front stretching are more significant. This work shows that structural heterogeneity has a considerable effect on reactive solute transport and that this effect depends on the system’s saturation.

How to cite: Borgman, O., Gomez, F., Le Borgne, T., and Méheust, Y.: Mixing-induced reactive transport experiments in heterogeneous and variably saturated porous media, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14907, https://doi.org/10.5194/egusphere-egu24-14907, 2024.

EGU24-15195 | ECS | Posters on site | HS8.1.1

Effect of water content on transport of water tracer and strontium in compacted clay-rich soil column 

Jean Maillet, Emilie Thory, Christelle Latrille, and Sébastien Savoye

Mechanisms involved in the radionuclide mobility in water-saturated environments have been extensively studied in order to predict their migration. However, in natural environments, a partially water-saturated zone occurs between the soil surface and the water table. It is well known that a decrease in water content reduces the porosity available for flow. Various studies have reported a increase or reduction of the contaminants residence time in porous media, explained by the flow paths complexity increase, a preferential path by the macroporosity and a reduced accessibility to reactive sites [1]. This study aims to understand the influence of water content on transport parameters such as dispersivity, porosity and chemical reactivity. This study investigates the effect of water content by comparing column transport experiments performed with inert (enriched-HDO water) and reactive (strontium) tracers on water-saturated and partially saturated soil.

Transport experiments were carried out on columns filled with the 300-400 µm fraction extracted by dry sieving from a sedimentary alluvium. This material was then compacted inside a glass column to reach the same density as that measured in the field (1.47 g.cm-3). Transport experiments were performed under water saturated and partially saturated conditions corresponding to 0.43 to 0.19 water content, with a CaCl2 solution equilibrated with calcite at pCO2 atm. At steady flow, tracers were introduced into the system by an injecting loop, passed through the material and was collected in sequenced fractions. Sensors placed at both inlet and outlet of the column [2] allowed pH and electrical conductivity to be continuously controlled. HDO and Sr were measured with a deuterium analyser and an ICP MS respectively. HDO and Sr breakthrough curves were interpreted with HYDRUS-1D coupled with PhreeqC softwares. A multi-site ion exchange model was implemented in PhreeqC [2]. Flowrate and porosity were experimentally measured while dispersivity was determined by inverse modelling. To compare the different experiments, results were expressed in dimensionless units: relative concentration (C/C0) and pore volume passed through the column normalized to the column pore volume (V/Vpore).

Based on experiments carried out in water-saturated media with HDO, the dispersivity in the material was estimated at 0.1 cm-1. The Sr residence time was tenfold more than HDO (from 2.5 to 30 V/Vpore), which confirms that chemical retention drives the cation migration into porous media. Three HDO experiments carried out at various water contents (0.24 to 0.19 cm.cm-1) revealed a regular dispersivity increase with decreasing water content from 0.1 to 0.2 cm-1. For Sr experiments, decreasing water content led to the increase of the breakthrough curve intensities and a tailing effect, meaning that Sr would be less retained and more spread with reduced water content.

These results show that reducing the water content in porous media leads to reduce the porosity accessibility to flow and to increase the dispersivity. This suggests that the water content decrease constrains the water flow path, this is intensified with the desaturation. The Sr transport behaviour change with desaturation may be explained by the reduction in the accessibility to the sorption sites.

 

How to cite: Maillet, J., Thory, E., Latrille, C., and Savoye, S.: Effect of water content on transport of water tracer and strontium in compacted clay-rich soil column, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15195, https://doi.org/10.5194/egusphere-egu24-15195, 2024.

EGU24-18085 | ECS | Orals | HS8.1.1

Impact of helicity on mixing in heterogeneous porous media 

Konstantinos Feroukas, Marco Dentz, Juan Hidalgo, and Daniel Lester

Mixing is the process that homogenizes initially segregated miscible constituents, increases the volume occupied by a solute, and decreases concentration peaks. It is important for the assessment of contamination levels and biogeochemical reactions in groundwater and soils. Mixing processes are governed by the interplay of fluid advection, molecular diffusion and local-scale dispersion at Darcy scale. Here we study the mechanisms of mixing in three-dimensional Darcy scale porous media with different heterogeneity structure. We analyze the role of medium and flow topology on the mixing and dispersion behavior. To this end, we perform Darcy-scale numerical simulations of incompressible flow and transport in heterogeneous three-dimensional porous media. Hydraulic conductivity is represented as a multi-Gaussian random field with lognormal marginal distribution. We consider isotropic and anisotropic correlation structures and scalar and tensorial conductivity. Flow is solved using a finite volume two-point method and transport using a Lagrangian approach. The flow topology is quantified by the helicity of the velocity field. We consider a planar injection of particles. Dispersion is quantified by the longitudinal and transverse dispersion coefficient, which are determined by the evolution along time of the position’s variance in the respective direction divide by two. It is also quantified by the breakthrough curves, which measure the distribution of arrival times at a given position from the initial one. Mixing is quantified by the ability of the flow to stretch and elongate a fluid strip which enhances diffusion through the creation and sustaining of concentration gradients. Results show that for a helical flow, a finite transverse dispersion coefficient is observed at long times and that the elongation of elemental strips follow an exponential stretching  (for large logK variances). On the contrary, on non-helical flows, transverse dispersion tends asymptotically to zero and the stretching rate is algebraic. The longitudinal dispersion coefficient seems unaffected by the helicity of the flow. These results shed light on the relation between medium structure and flow topology on mixing, making an important step towards the control, upscaling and large scale representation of mixing in porous media

.

 

How to cite: Feroukas, K., Dentz, M., Hidalgo, J., and Lester, D.: Impact of helicity on mixing in heterogeneous porous media, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18085, https://doi.org/10.5194/egusphere-egu24-18085, 2024.

EGU24-18902 | Posters on site | HS8.1.1

Development of a new computer tool for coupling HYDRUS-1D and MODFLOW 

Bartosz Balis, Mateusz Pawlowicz, Adam Szymkiewicz, Jirka Simunek, Anna Gumula-Kawecka, and Beata Jaworska-Szulc

Groundwater management relies increasingly on numerical models to assess past, present, and future conditions, optimize strategies, and protect resources from climate and land use changes. Groundwater systems encompass the unsaturated (vadose) and saturated (groundwater) zones, with vadose zone modeling presenting computational challenges due to nonlinear equations and complex parameters. One possible solution to include the vadose zone processes in groundwater models in a flexible manner is to couple computer programs modeling 3D flow in the saturated zone with programs modeling 1D flow in the vadose zone. 

 

In this study, we introduce the HYDRUS-MODFLOW Synergy Engine (HMSE), a novel coupling approach for HYDRUS-1D and MODFLOW-2005, aimed at enhancing groundwater modeling. HMSE employs external coupling via a versatile interface, offering three deployment options: a desktop application, a Docker container, and a Kubernetes cluster. Users interact through a web interface, enabling project setup, model uploads, configuration adjustments, simulations, and result retrieval.

 

The MODFLOW's area is divided into recharge zones, each assigned a HYDRUS-1D model representing soil profiles, land cover, groundwater depth, and weather conditions. HMSE offers two coupling modes. In the simple mode, groundwater table positions are assumed constant, HYDRUS-1D simulations are performed for the entire period, and average recharge rates are calculated for MODFLOW. In the second coupling mode, MODFLOW and HYDRUS-1D interact iteratively to update the water table position in HYDRUS-1D profiles after each stress period in the MODFLOW simulation. This involves splitting the MODFLOW model into segments corresponding to different stress periods, performing HYDRUS-1D simulations, passing recharge data to the RCH file, running a MODFLOW simulation for each stress period, and using MODFLOW results to calculate the average water table depth for each recharge zone, thus updating the corresponding HYDRUS profiles while avoiding oscillations in recharge flux. 

 

HMSE combines the strengths of mature and validated HYDRUS-1D and MODFLOW-2005 programs, offering a more comprehensive understanding of groundwater systems. Our study presents a preliminary validation of HMSE for a shallow aquifer in northern Poland. We also evaluated HMSE performance in the three deployments (desktop, Docker and Kubernetes). 

How to cite: Balis, B., Pawlowicz, M., Szymkiewicz, A., Simunek, J., Gumula-Kawecka, A., and Jaworska-Szulc, B.: Development of a new computer tool for coupling HYDRUS-1D and MODFLOW, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18902, https://doi.org/10.5194/egusphere-egu24-18902, 2024.

EGU24-19360 | Posters virtual | HS8.1.1

Effect of supercritical CO2/water interactions on geomechanical behavior of quartz-rich sandstone for CO2 geological storage 

Takashi Fujii, Masashige Shiga, Yasuki Oikawa, and Xinglin Lei

In the course of CO2 injection into a storage reservoir, understanding of a volumetric change (e.g., swelling), induced by interacting among CO2, water and rock into pores of rocks should be a critical step for modeling of hydro-mechanical response relevant to CO2 capture and storage (CCS) technology. For the majority of ongoing and planning CCS sites in the globe, hard sedimentary rocks, which is main component of quartz and feldspars with less clay minerals (e.g., smectite, illite), is a representative reservoir rock. It is well-known that caprocks (i.e., mudstone and shale) occur the swelling behavior of a rock matrix in the presence of water and/or CO2 due to intercalation and exchange reactions between layers of clay minerals. However, such volumetric change effect for quartz-rich rocks is not yet being investigated enough. In this study, we investigate geomechanical behavior of quartz-rich sandstone (Berea sandstone) in supercritical CO2 (scCO2)-water system under effective pressure of 10 MPa for up to approximately 1 week, the condition of which assumes that CO2 is injected into a storage reservoir at 1 km depth. Our results demonstrated that quartz-rich sandstone had a significant potential for changes in geomechanical properties (i.e., axial stress, displacement, volumetric strain) in scCO2-water system, like that do clay-rich caprocks, although little the change being observed for only water-saturation under the same effective stresses, and its maximum value was approximately 0.3 % for scCO2/water system. Also, increasing axial stress induced by the change in volumetric strain of the rock sample tested were more than 1 MPa for all experimental runs. A comparison results suggested that the obtained volumetric strains for this system could not be explained fully by change in bulk modulus before and after introducing scCO2 into the rock sample. The findings of our study might provide a significant contribution for the coupled hydro-mechanical behavior in storing CO2 into hard sedimentary rocks.

How to cite: Fujii, T., Shiga, M., Oikawa, Y., and Lei, X.: Effect of supercritical CO2/water interactions on geomechanical behavior of quartz-rich sandstone for CO2 geological storage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19360, https://doi.org/10.5194/egusphere-egu24-19360, 2024.

EGU24-19678 | Orals | HS8.1.1

A Spatially Distributed Leaching Model to assess pesticide leaching for exposure assessment at the European level 

Maarten Braakhekke, Pavan Cornelissen, Louise Wipfler, Aaldrik Tiktak, Anton Poot, Bernhard Jene, Gerco Hoogeweg, Abdul Ghafoor, Judith Klein, Michael Stemmer, Amy Ritter, Robin Sur, Gregor Spickermann, Gerard Heuvelink, Gregory Hughes, Stephan Marahrens, Stefan Reichenberger, Nicoleta Suciu, and Michelle Morris

Assessment of the leaching potential of pesticides and their metabolites is an important part of the authorization procedure for pesticides in Europe. To protect groundwater quality, it must be demonstrated that concentrations of active substances in the upper groundwater do not exceed 0.1 μg/L before a pesticide can be approved for use. For the purpose of exposure assessment, this concentration limit is imposed on the water leaching downward at 1 m depth in the soil profile. For a given substance and application pattern, this leaching concentration can vary in space by several orders of magnitude, due to variation in site conditions, most importantly soil properties and climate. Spatially distributed leaching modelling (SDLM) is a methodology for exposure assessment over large spatial extents, dealing with this spatial variability in a comprehensive way. It involves performing simulations for many parametrizations representative for a spatial region and can be used to generate maps or calculate spatio-temporal percentiles of leaching concentrations. While such tools are already used in exposure assessment at national level in several EU member states, no generally accepted SDLM tool is available at the European level. In 2020, a working group of Society of Environmental Toxicology and Chemistry (SETAC) was formed with the purpose to develop a harmonized framework for SDLM across Europe (EU27 + UK).

A first version of an SDLM—referred to as GeoPEARL-EU—was built around the pesticide leaching model PEARL, a field-scale model of pesticide fate in the soil-plant system. PEARL mechanistically simulates pesticide behaviour in a 1D soil column based on explicit descriptions of transport in the liquid and gas phases, sorption to the solid phase, degradation, volatilisation, and plant-uptake. Soil moisture content and fluxes are provided by the SWAP hydrological model. PEARL is used in regulatory exposure assessment for groundwater and soil. Furthermore, a spatially distributed tool based on PEARL (GeoPEARL) is used for exposure assessment in the Netherlands.

To apply PEARL to Europe, pan-European gridded datasets were collected for several variables, including soil texture, pH, soil organic carbon, weather, irrigation patterns and crop area. These datasets were used to develop a set of parametrizations covering the variability of climate and soil conditions in Europe. To this end, all 1x1 km grid cells for the EU27 + UK were partitioned into approximately 10,000 clusters using k-means clustering, based on several soil- and climate-related variables relevant for leaching vulnerability. Subsequently, a representative grid cell was selected for each cluster, which was used to obtain the data required to parameterize PEARL from the spatial data sets. Pedotransfer functions were used to derive soil hydraulic parameters.

We will present results from GeoPEARL-EU for several test cases with specific attention to the effect of the spatial aggregation approach on the model predictions. Moreover, we discuss how the tool could be used in the tiered approach of the regulatory exposure assessment for groundwater in the EU.

How to cite: Braakhekke, M., Cornelissen, P., Wipfler, L., Tiktak, A., Poot, A., Jene, B., Hoogeweg, G., Ghafoor, A., Klein, J., Stemmer, M., Ritter, A., Sur, R., Spickermann, G., Heuvelink, G., Hughes, G., Marahrens, S., Reichenberger, S., Suciu, N., and Morris, M.: A Spatially Distributed Leaching Model to assess pesticide leaching for exposure assessment at the European level, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19678, https://doi.org/10.5194/egusphere-egu24-19678, 2024.

EGU24-20806 | Orals | HS8.1.1

Pore-scale investigations of interactions between microorganisms and ionic strength: Implications for salt crystallization damage in porous media 

Jafar Qajar, Alejandra Reyes Amezaga, Selen Ezgi Celik Selen Ezgi Celik, Sebastiaan Godts, Laurenz Schröer, Amir Raoof Amir Raoof, and Veerle Cnudde

Drying of building materials filled with salt-containing moisture is a common example of salt weathering [1]. Fluid flow, such as capillary uptake of water, and local climate changes stand out as key factors in salt weathering, substantially impacting the Earth's landscape and building infrastructure [2]. While microbial organisms are known to alter rock surfaces, some exhibit physiological capabilities that beneficially impact rock properties by producing biofilms, biocement and biogas [3]. Environmental factors such as temperature, relative humidity, and ionic strength of the medium influence microbial-induced products [4]. The impact of salt type, concentration, and ionic strength on microbially mediated reactions inside porous media is a largely unexplored phenomenon at the pore scale. Effective addressing of the respective challenges requires understanding the synergistic and counter effects of bacterial interactions and salt crystallization within the internal pore structure of rocks, influencing related pore-scale processes. In this study, we explored the response to the drying process in a range of porous materials, from PDMS transparent micromodels to sedimentary porous rocks containing brine solutions of various compositions in the presence and without bacterial solutions. We used Paracoccus denitrificans bacteria in our experiments. We specifically consider the case where air with different levels of humidity and at a constant temperature is exposed to one side of the porous media, forming a drying front—a defined interface separating liquid-saturated and partially gas-filled domains. High-resolution optical and confocal microscopy, Raman spectroscopy, and X-ray micro-computed tomography (µ-CT) were used to visualize and characterize bacteria-salt aggregates interactions in the porous media. Systematic investigations were carried out to understand how the interactions between salt crystallization and bacterial reactions depend on pore space morphology, type, and ionic strength of salt solutions. The findings highlight the potential of advanced 2D and 3D imaging techniques for enhanced understanding of the transport-crystallization coupling with bacterial activity through in-situ experiments and, hence, for constructing more accurate prediction models and conservation strategies.

Keywords: Salt weathering; Bacteria; Ionic strength; Relative humidity; Evaporation; Imaging techniques.

Acknowledgement: This project has received funding from the Dutch Research Council (NWO) through the BugControl project (project number VI.C.202.074) of the NWO Talent program and from the EU INFRAIA project (H2020) the EXCITE Network.

References

[1]       Sghaier, N., S. Geoffroy, M. Prat, H. Eloukabi, and S. Ben Nasrallah, Evaporation-driven growth of large crystallized salt structures in a porous medium. Physical Review E, 2014. 90(4): p. 042402.

[2]       Grossi, C.M., P. Brimblecombe, B. Menéndez, D. Benavente, I. Harris, and M. Déqué, Climatology of salt transitions and implications for stone weathering. Science of The Total Environment, 2011. 409(13): p. 2577-2585.

[3]       Llop, E., I. Alvaro, A. Gómez-Bolea, M. Hernández Mariné, and S. Sammut, Biological crusts contribute to the protection of NeolithicHeritage in the Mediterranean region, in Science and Technology for the Conservation of Cultural Heritage. 2013. p. 33-36.

[4]       Ferrer, M.R., J. Quevedo-Sarmiento, M.A. Rivadeneyra, V. Bejar, R. Delgado, and A. Ramos-Cormenzana, Calcium carbonate precipitation by two groups of moderately halophilic microorganisms at different temperatures and salt concentrations. Current Microbiology, 1988. 17(4): p. 221-227.

How to cite: Qajar, J., Reyes Amezaga, A., Selen Ezgi Celik, S. E. C., Godts, S., Schröer, L., Amir Raoof, A. R., and Cnudde, V.: Pore-scale investigations of interactions between microorganisms and ionic strength: Implications for salt crystallization damage in porous media, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20806, https://doi.org/10.5194/egusphere-egu24-20806, 2024.

EGU24-20962 | ECS | Posters on site | HS8.1.1

Preventing Salt Precipitation in Soils through Density-Driven Salt Instabilities 

Stefanie Kiemle, Theresa Schollenberger, Katharina Heck, Rainer Helmig, Carina Bringedal, and Hans van Duijn

Soil salinization causes severe problems in agriculture, especially in arid and semi-arid regions, as it leads to soil degradation and reduces plant growth. During evaporation from a saline-water-saturated soil, salt accumulates near the top of the soil. Depending on the conditions, the increasing salt concentration will either lead to precipitation once the solubility limit is reached or due to the increase in the liquid density a gravitationally unstable situation is given, where instabilities in the form of fingers will develop. Hence, salt can be transported downwards. The development of these instabilities and the potential salt precipitation have been analyzed using numerical simulations on the REV-scale. The simulations were performed by using the numerical simulator DuMuX.  

We analyzed the relevant processes to identify the influence of different parameters like soil-hydraulic properties, evaporation rate, or salt properties on precipitation. In Bringedal et. al., 2022, the appearance of instabilities during evaporation from a one-phase system was investigated using a linear stability analysis and numerical simulations on the REV-scale. The linear stability set criteria for the onset of instabilities for a large range of parameters, whereas the numerical simulations provide information about the development of the instabilities after onset. By combining both methods, we can predict the occurrence of instabilities and their effect on the salt concentration near the top boundary. This analysis has been extended to two-phase systems to analyze the impact of phase saturation on the development of salt instabilities. 

In future work,  we plan to improve the REV-scale models with the help of the pore-network model. This will be done by identifying relevant parameters for salinization processes on the pore scale and using suitable upscaling methods for the use on the REV-scale.

How to cite: Kiemle, S., Schollenberger, T., Heck, K., Helmig, R., Bringedal, C., and van Duijn, H.: Preventing Salt Precipitation in Soils through Density-Driven Salt Instabilities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20962, https://doi.org/10.5194/egusphere-egu24-20962, 2024.

EGU24-21133 | Posters on site | HS8.1.1

Implementation of the Brunswick model system into the Hydrus software suite 

Jiri Simunek, Efstathios Diamantopoulos, and Tobias K. D. Weber

The modular framework for modelling unsaturated soil hydraulic properties over the full moisture range of Weber et al. (2019) and Streck and Weber (2020) was implemented in the Hydrus Suite. Users can now additionally choose between four different variants of the Brunswick model: i) van Genuchten-Mualem (van Genuchten, 1980; Mualem, 1976), ii) Brooks-Corey (Brooks and Corey, 1964), iii) Kosugi (Kosugi, 1996), and iv) modified van Genuchten (Vogel and Cislerova, 1988). For demonstration purposes, simulation results of bare soil evaporation and root water uptake with Hydrus are presented, along with a comparison of the original van Genuchten-Mualem model and its Brunswick variant. Results show that the original van Genuchten-Mualem model underestimates the simulated cumulative evaporation and cumulative transpiration due to the inconsistent representation of the soil hydraulic properties in the dry moisture range. We also implemented a two-step hydro-ptf into the Hydrus Suite that converts the parameters of the original van Genuchten-Mualem model to the Brunswick variant (Weber et al., 2020). In that way, physically comprehensive simulations are ensured in case no data on soil hydraulic properties are directly available, but information on physical soil properties (e.q., texture, bulk density) exists.

How to cite: Simunek, J., Diamantopoulos, E., and K. D. Weber, T.: Implementation of the Brunswick model system into the Hydrus software suite, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21133, https://doi.org/10.5194/egusphere-egu24-21133, 2024.

EGU24-21207 | Posters on site | HS8.1.1

 Dissecting the spatio-temporal variability of soil hydraulic properties in an agricultural eroded area 

Giuseppe Brunetti, Radka Kodešová, Miroslav Fér, Antonín Nikodem, Aleš Klement, and Jiří Šimůnek

The combined effect of anthropogenic and climatic stressors deeply influences the hydrological behavior of agricultural areas, especially on hillslopes. Tillage induces an abrupt change in the soil's hydraulic functioning, which can be dynamically recovered in time due to natural consolidation, alternation of wetting and drying cycles, and other biophysical factors. Heavy rainfall can accelerate the recovery process, but also induce erosion events in tilled soils, further exacerbating the spatial variability of the topsoil hydraulic properties. To better understand the mechanisms driving the spatio-temporal variability of soil hydraulic properties in agricultural areas, we combine the modified hydrological model HYDRUS with transient soil moisture observations from two hillslopes in the Czech Republic exposed to tillage and erosion. In particular, the Bayesian inference is used to calibrate two alternative HYDRUS implementations at five different locations along the hillslopes. The first model assumes static soil hydraulic properties, while the second simulates their dynamic change induced by tillage and natural consolidation (due to rainfall). The Watanabe-Akaike Information Criterion (WAIC) is used to compare the two models by considering not only the fitting accuracy, but also the predictive uncertainty. The results show that both models can reproduce soil moisture observations satisfactorily at different depths and locations. While the dynamic model exhibits slightly better fitting, this is compensated by larger predictive uncertainty compared to the static model. This is confirmed by the WAIC values, which are similar for the two models. An in-depth analysis indicates that the dynamic recovery of soil hydraulic properties happens during the first few rainfall events (confirming what was observed in other studies) and suggests that higher resolution measurements are needed to better estimate recovery factors. Finally, the spatial variability of the estimated soil hydraulic parameters hints at a possible role of overland flow fluxes along the hillslope as a heterogeneity-generating factor. 

How to cite: Brunetti, G., Kodešová, R., Fér, M., Nikodem, A., Klement, A., and Šimůnek, J.:  Dissecting the spatio-temporal variability of soil hydraulic properties in an agricultural eroded area, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21207, https://doi.org/10.5194/egusphere-egu24-21207, 2024.

SSS7 – Soil Pollution and Reclamation

EGU24-594 | Posters on site | SSS7.1

Coupling Leaching-Bioremediation for Petroleum-Contaminated Soils 

Bing Qin and Liming Ren

Petroleum-contaminated soils are difficult to remediate due to a wide range of point/nonpoint sources of pollution and complex components. Here, a new leaching agent system was developed and synthesized, including oligomers, to construct the leaching process and optimize the soil leaching process parameters. The new agent has improved skeleton structure, green bio-based surfactant molecules, and synergists. Based on the characteristics of the leaching soil and its flora structure, more than 60 strains of petroleum degradation bacteria were isolated and screened. Furthermore, suitable bacteria for degradation were cultivated, the nutritional formula and process flow were optimized, and the microbial agent formula for heavy oil, polycyclic aromatic hydrocarbons and other pollutants were established. According to the physical characteristics of different types of oily sludge and soil, an economical and efficient remediation technology system and supporting implementation process were established, and finally, a "leaching-bioremediation" coupling treatment process was formed. The PHs content of the actual contaminated soil after the treatment was lower than 0.45%, and 12,000 t of PHs contaminated soil was remediated. Through the study of the elution-bioremediation process, the establishment of economical and environmentally friendly remediation technology and the process will improve our knowledge to solve the sudden oil pollution in contaminated areas and the environmental protection solution of historical problems.

How to cite: Qin, B. and Ren, L.: Coupling Leaching-Bioremediation for Petroleum-Contaminated Soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-594, https://doi.org/10.5194/egusphere-egu24-594, 2024.

EGU24-1286 | ECS | Orals | SSS7.1

Spatial modelling of Soil Organic Carbon fractions in a degraded coal-mining area through UAV and Sentinel-2 

Lorena Salgado, Rubén Forján, Carlos A. López-Sánchez, María G. Álvarez, Ana M. Díaz, Arturo Colina, and Jose R. Gallego

Traditional methods to acquire (geo)chemical data of Soil Organic Carbon (SOC) in soil rely on manual sampling, time-consuming and laborious chemical analyses, and subsequent mapping by geostatistical interpolation methods. In this study, we propose the use of UAV-RS and Sentinel-2 images, still partially supported by field sampling, for assessing and mapping different fractions of SOC using a regression study through Machine Learning (ML) techniques. This approach is exemplified in the postmining degraded soils of a vast former coal-mining area affected mainly by high degradation of Organic Matter (O.M).

Geochemical analyses by means of a TOC analyzer were conducted to monitor SOC fractions. Soil samples were dried and sieved through a 2-mm mesh to eliminate large particles. Two labile fractions of carbon (CLAB) were obtained through cold-water extraction (CCWE) and hot-water extraction (CHWE); also, two removable carbon fractions (CREM), humic and fulvic acids (CHA and CFA), were extracted; finally, the remaining recalcitrant organic carbon (CREC) was measured in the residue of the previous extractions. TOC was estimated as the sum of CLAB, CREM and CREC.

Spectral data were systematically recorded across a surface area covering 64 hectares within former open pits, involving natural, restored, and degraded zones. A UAV-RS P4-Multispectral platform, equipped with a camera featuring six individual sensors (RGB, blue, green, red, red-edge, and near-infrared), was used; five distinct bands between the visible and near-infrared spectra were obtained. Simultaneously, Sentinel-2 data were employed to acquire spectral information from satellite-borne sensors, thereby obtaining 12 single bands (aerosol, blue, green, red, 3 red edge, 2 NIR, water vapor, cirrus, and 2 SWIR). Given the limitations of information derived from individual bands, spectral indices—combinations of multiple bands through algebraic operations—were employed. Subsequently, two ML algorithms, specifically Random Forest (RF) and Partial Least Square (PLS), were applied to identify the most fitted model for each SOC fraction.

Results revealed that the utilization of non-parametric algorithms, specifically RF, yields a superior goodness of fit compared to parametric algorithms like PLS. The most favourable statistical outcomes were observed for fractions of non-labile organic carbon, with the optimal statistics achieved for CREC, attaining an R2 value of 0.70 and an RPD value of 1.83. When comparing data from UAV and Sentinel-2 sources, better results were found for UAV, this strongly suggesting that, in this study, spatial resolution holds greater relevance than spectral resolution.

This research was funded by the projects NATURESOIL (AEI/Spain, TED2021-130375B-I00) and Atlantic Risk Management Plan in Water and Soil (RiskAquaSoil 272-2016, Interreg Atlantic Area, EU).

How to cite: Salgado, L., Forján, R., López-Sánchez, C. A., Álvarez, M. G., Díaz, A. M., Colina, A., and Gallego, J. R.: Spatial modelling of Soil Organic Carbon fractions in a degraded coal-mining area through UAV and Sentinel-2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1286, https://doi.org/10.5194/egusphere-egu24-1286, 2024.

Oxytetracycline (OTC) is one of the popular antibiotics accumulated in soils and groundwater, posing harmful effects on ecological systems and human health. The objective of this work is to examine the feasibility of OTC degradation using a new catalyst, oxygen-doped graphitic carbon nitride (O-gC3N) for in-situ oxidation remediation. In-situ oxidation system was simulated with column experiments to investigate the performance of PMS activation and OCT removal in saturated porous media. Numerical modeling as HYDRUS 1D was used to analyze OTC's transport behaviors in saturated porous media. The results show that OTC transport in saturated porous media is non-equilibrium. O-gC3N can efficiently activate PMS to degrade OTC and the increase of PMS and O-gC3N can enhance OTC removal. A wide pH range is beneficial for OTC degradation in saturated porous media. EBCT significantly affects OTC degradation and the optimal velocity was 0.4 cm/min. The findings of this work suggest that O-gC3N catalyst can effectively be utilized for the in-situ oxidation of organic pollutants in contaminated sites.

How to cite: Ko, S., Nguyen, T. T., and Kim, D.: Degradation of oxytetracycline in saturated porous media by in-situ chemical oxidation using oxygen-doped graphitic carbon nitride and peroxymonosulfate (PMS), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1305, https://doi.org/10.5194/egusphere-egu24-1305, 2024.

EGU24-1966 | ECS | Orals | SSS7.1

Functional diagnosis of industrial soils: from a cognitive model to in situ implementation 

Caroline Dalquier, Geoffroy Séré, Jennifer Hellal, Nicolas Legay, Laure Santoni, and Pascaline Herbelin

Industrial activities, such as thermal power plants, induce soil degradation on large areas (e.g. soil sealing, contamination related to fuel, coal and ash deposits, soil compaction). After the cessation of activities, landowners of such sites have a huge land heritage that could be considered to promote rehabilitation projects for new land-uses in the frame of the No Net Land Take by 2050. Therefore, there is a need to develop a robust and easy-to-use approach for landowners that could be implemented by soil techniciens/pratitioners to assess soil functions to measure their potential for future uses.

First a cognitive model linking soil functions to a minimum dataset of indicators was established based on chemical, physical and biological properties of soil as well as vegetation cover. This cognitive model includes 6 soil functions (e.g. plant biomass production) and 17 sub-functions (e.g. phytoavailability of nutrients, nutrients storage) and a minimum set of indicators selected among a large list from research studies and attributed to each sub-function and function.

Then two thermal power plants under closure were selected and a documentary survey was carried out for each site to identify contrasted zones in terms of soil cover, mostly based on the nature of the past activities (e.g. coal, slag or ash deposit, building foundations, fuel storage). Twelve zones considered as homogeneous in terms of vegetation and soil type and distinct from each other were selected on these two sites. In total, 12 soil profiles and 164 soil samples were analysed for various biological (plants, nematodes, microbial communities), chemical and physical parameters.

Our results show contrasting situations. Despite the high vegetation cover of the three different ash deposit zones, their plant diversity indices ranged from very low to medium. The same goes for the area where building foundations were located, but they had very little vegetation cover. Also, the enrichment index (EI) and structure index (SI) of the nematode community showed that ash deposits are degraded, nutrient-poor soils and have a high C/N (>12) while the building foundation areas have a "mature and fertile" soil with optimal C/N.  

Whereas some soils could be considered as natural references as they were not affected by industrial activities, others were Technosols made of 100% artefacts. However, the gradient of anthropisation was surprisingly not correlated to the level of functions that were assessed. As an example, technogenic soils developed from fly ash exhibit high soil functions ratings (e.g. carbon storage).

These initial results suggest that the functioning of these soils must be evaluated according to different scales (e.g. plot scale, surface soils), points of view (biological, chemical and physical) and soil functions (e.g. storage and sequestration of GHG, biodiversity reservoir), to establish their functional profiles and suggest possible future uses.

How to cite: Dalquier, C., Séré, G., Hellal, J., Legay, N., Santoni, L., and Herbelin, P.: Functional diagnosis of industrial soils: from a cognitive model to in situ implementation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1966, https://doi.org/10.5194/egusphere-egu24-1966, 2024.

EGU24-2726 | ECS | Orals | SSS7.1

GIS-based approach to generate the bioaccessibility of soil heavy metals for human risk assessments: case study in Changhua farmlands, Taiwan 

Yen-Tzu Fan, Ying-Lin Wang, Ming-Chien Tsou, Zeng-Yei Hseu, Hsing-Cheng Hsi, and Ling-Chu Chien

Considering the bioaccessibility of soil heavy metals for human health assessment can prevent overestimation for policymakers. However, the complexity of soil properties and heavy metal concentrations makes it challenging to establish a general dataset for bioaccessibility in assessments. Soil heavy metals commonly occur in agricultural regions due to both agricultural and industrial activities, posing high health risks for residents through soil exposure. In the past 10 years, the government in Taiwan has actively promoted soil remediation for agricultural heavy metal-polluted soils, completing remediation for more than 99% of polluted sites. However, conducting health risk assessments for remediated soils remains difficulty due to a lack of a general dataset for the bioaccessibility of common soil heavy metals. In this study, we conducted soil sampling from 98 sites located in agricultural regions with various soil properties. We first established regression relationships for the bioaccessibility of six common heavy metals: cadmium (Cd), lead (Pb), chromium (Cr), nickel (Ni), copper (Cu), and zinc (Zn), based on measured soil properties and heavy metal concentrations. Second, we performed GIS analysis to generate the bioaccessibility of heavy metals from a previous soil survey across all agricultural regions in Taiwan, using our established equations. Then, we conducted health risk assessments for residents at different stages of life (infants, children, teenagers, adults, and seniors) living in agricultural regions (i.e., Changhua farmlands) after soil remediation. Our results revealed high non-carcinogenic risks (hazard index > 1) for infants and children but high carcinogenic risks (total cancer risk index > 1e-4) for seniors. Our study established a GIS-based approach for estimating the bioaccessibility of soil heavy metals based on actual measurements, providing an easier way for health risk assessments of soil heavy metal pollution.

 

Keywords: SBET, human health, farmland, heavy metal pollution, GIS

How to cite: Fan, Y.-T., Wang, Y.-L., Tsou, M.-C., Hseu, Z.-Y., Hsi, H.-C., and Chien, L.-C.: GIS-based approach to generate the bioaccessibility of soil heavy metals for human risk assessments: case study in Changhua farmlands, Taiwan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2726, https://doi.org/10.5194/egusphere-egu24-2726, 2024.

EGU24-6389 | ECS | Orals | SSS7.1

Plant biomass for energy and phytoremediation purposes: three-year analysis of Phalaris arundinacea production on contaminated lands in central Italy 

Riccardo Alemanno, Leonardo Bianchini, Richard Lord, Benjamin Nunn, and Andrea Colantoni

Energy production is one of the main challenges that continues to unsettle nations. The cultivation of plant species as biomass for energy purposes is an option but raises the issue of taking land away from food production. A solution to this controversy has been identified by exploiting those soils that cannot be used for food production, namely contaminated soils. The present study focuses on the evaluation of the biomass productivity of Phalaris arundinacea (Reed Canary Grass) in three different fields in Central Italy, which present potentially toxic element (PTE) contamination. The experiment was conducted over three consecutive years. This study is part of the CERESiS (ContaminatEd land Remediation through Energy crops for Soil improvement to liquid biofuels Strategies) Project which has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 101006717, which started in November 2020 and is set to end in 2024. P. arundinacea is a species that lends itself to biomass production and to the phytoremediation and phytostabilisation of contaminated soils. The three cultivated areas with different textures (EA: sandy loam, B1: clay loam and B2: clay) were prepared with a minimum tillage system in late winter 2021 and sown in spring 2021. Annually, the crop received urea-based nitrogen fertilisation (100 kg ha-1) in late spring and sprinkler irrigation in dry periods. In the “EA” area, additional tests were conducted with different amounts of nitrogen fertiliser (0 - 50 - 100 kg ha-1) and seed treatment with biostimulant based on Trichoderma spp.  Production was estimated by sampling the biomass at different annual times. In areas B1 and B2 through two annual mowings (August and November). In EA, on the other hand, the sampling method allowed for the estimation of a single and/or double mowing at different times (August, mid-September and November). This experimental design allowed assessment of biomass growth, regrowth, and bioaccumulation capacity. At harvest time, a chemical-physical characterisation of the biomass was carried out.

The sandy loam texture did not favour the development of P. arundinacea. Dry biomass production over the three years averaged between 4.0 t ha-1 and 5.1 t ha-1. Generally, the second mowing did not provide enough yield to justify harvesting. P. arundinacea showed limited phyto-extraction of heavy metals. This is compensated by the positive result of the low concentration of PTE in the plant with abundant biomass production. As a fuel, the biomass showed good qualities, with average HHV and LHV values of over 18.8 and 16.1 MJ kg-1 respectively. One aspect that could have a negative impact is the exceptionally high ash content, which over the years has averaged around 14.5 %.

This experiment highlights the manifold benefits of using this plant species. The simultaneous capacity for phytoremediation and energy use of the derived biomass are environmental, economic, and social winning points.

How to cite: Alemanno, R., Bianchini, L., Lord, R., Nunn, B., and Colantoni, A.: Plant biomass for energy and phytoremediation purposes: three-year analysis of Phalaris arundinacea production on contaminated lands in central Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6389, https://doi.org/10.5194/egusphere-egu24-6389, 2024.

EGU24-6709 | Posters on site | SSS7.1

The comprehensive concept for the management of post-industrial sites based on natural processes 

Gabriela Wozniak, Agnieszka Kompała-Bąba, Agnieszka Hutniczak, Wojciech Bierza, and Agnieszka Błońska

There are many theories and concepts concerning ecosystem development in natural and semi-natural habitat conditions. The study of spontaneous processes on human-disturbed habitats such as post-excavation mineral habitats provided data revealing that the impact of the specific abiotic factors on any aspect of biotic elements of the developing ecosystems does not follow most of the mechanisms known from the natural and semi-natural habitat conditions. The feedback relations become more complex when the spontaneous vegetation patches and the developing ecosystem start to cover mineral oligotrophic habitats, particular in respect to the biomass soil organic matter and soil substratum parameters. The fundamental process of the biomass and further soil organic matter in mineral soil substratum is based on the non-analogous species composition of the developing vegetation assemblages.

The de novo formed unusual mineral habitats are colonized by not-known plant species vegetation communities. The relationships between the plant species, particularly the dominant plant species, and the abiotic substrate parameters are frequently different than expected. The differences in ecosystem functioning observed in the disturbed habitats led the researcher to use a separate term novel ecosystem.

The crucial observed process is the colonization of the best-adapted plant species individuals. The individuals of the commonly represented species are adapted to extreme drought, salinity,  texture, and pH. The same is true regarding the microorganisms of the colonizing plant's root system. These natural processes provide an opportunity to investigate the relationships between the plant species, particularly the dominant plant species, and the associated organisms and the abiotic substrate parameters. Differences in the chemical and physical properties of the disturbed post-mineral excavation substrates have resulted in unknown, non-analogous species compositions of the vegetation and animal organisms. These differences are reflected in the soil substratum enzymatic activity, the bacteria functional diversity, and soil substratum respiration rates.

The vegetation, biomass, the matter flow beginning, growing on the mineral material of the post-coal mine heaps consists of a mosaic of patches dominated by various species assembled in a variety of microhabitats. This mosaic reflects the diversity of abiotic habitat conditions. The taxonomic species diversity is followed by the functional vegetation diversity and the variety of plant individual's responses to environmental stressors.

Post-mineral excavation sites deliver an example of newly established habitats that differ from the natural ecosystems current in the surrounding landscape. These findings brought us to present a comprehensive concept for the management of post-industrial sites based on natural processes, that is necessary to be applied to recover the ecosystems after disturbance. This concept enables the application of the natural processes, in a site-specific approach in the disturbed or de novo established sites. The return to previous ecosystems should not be considered. The enhancement of the novel ecosystem development in urban and industrialized landscapes is the prerequisite of the modern economy.

How to cite: Wozniak, G., Kompała-Bąba, A., Hutniczak, A., Bierza, W., and Błońska, A.: The comprehensive concept for the management of post-industrial sites based on natural processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6709, https://doi.org/10.5194/egusphere-egu24-6709, 2024.

EGU24-7200 | Posters on site | SSS7.1

Immobilization mechanisms of Hexavalent Chromium When Reduced by Fe2+-Bearing Clay Minerals Depending on solution pH 

Changyu Moon, Hee-sun Moon, and Kyoungphile Nam

 Structural iron (Fe3+)-bearing clay minerals, when they are reduced, can mediate electron transfer through the Fe3+/Fe2+ coupling reaction and transform hexavalent chromium (Cr6+) into less toxic Cr3+, which in turn can be removed from the solution by the clay minerals. Two types of clay minerals with different structural iron (Fe3+) contents, montmorillonite (2.3 wt%) and nontronite (22.3 wt%), were subjected to reaction with 50 mM dithionite at pH 9 for 48 hours, resulting in Fe2+ bearing clay minerals, with measured Fe2+ ratios of 0.68 and 0.49, respectively. Subsequently, the Fe2+ bearing clay minerals were reacted with Cr6+ solution with varying pH ranging from 2.5 to 11 in an anaerobic chamber. Results show that the reduction of Cr6+ was observed at all pH conditions, consistent with the stoichiometric ratios with structural iron (Cr6+:Fe2+/1:3). At pH 7 and below, over 99% of the structural iron (Fe2+) participated in the reduction reaction. At pH 9 and 11, however, the reaction exhibited a shortfall, with approximately 7-27% and 20-32% of unutilized structural iron remaining in montmorillonite and nontronite, respectively. According to the Visual MINTEQ model and DTPA extraction experiments conducted on solids obtained, Cr3+ is immobilized through sorption onto the clay mineral surface at pH 4.5 and below, and through precipitation and deposition on the clay mineral at pH 7 and above. SEM-EDS analysis, the presence of precipitated Cr at pH 7 and above was identified, and XPS analysis confirmed its precipitation in the form of Cr(OH)3

How to cite: Moon, C., Moon, H., and Nam, K.: Immobilization mechanisms of Hexavalent Chromium When Reduced by Fe2+-Bearing Clay Minerals Depending on solution pH, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7200, https://doi.org/10.5194/egusphere-egu24-7200, 2024.

EGU24-7435 | ECS | Posters on site | SSS7.1

Growing perennial rhizomatous grasses on contaminated land: a strategy for combining phyto-management with sustainable biomass production? 

Benjamin Nunn, Keith Torrance, Ben Wright, Andrea Colantoni, Leonardo Bianchini, Riccardo Alemanno, Oleksandra Tryboi, Maico Severino, Wilson Leandro, and Richard Lord

To investigate this strategy, 15 field scale trials were implemented in five countries [1].  These have evaluated the performance of Phalaris, Miscanthus, 2 x Saccharum and 2 x Pennisetum species for combined energy crop production, phyto-remediation and or phyto-management of contaminated land in Brazil and Europe.  Reed canarygrass (Phalaris arundinacea) is a native perennial rhizomatous C3 species suitable for non-agricultural or marginal lands and climatic zones such as Scotland (where C4 Miscanthus x giganteous cannot be grown effectively).  Our phytoremediation trials using Phalaris in Italy and Ukraine are the first we are aware of.

Given the wide variety of non-agricultural marginal lands [2], species selection must combine significant biomass production on marginal land with acceptable levels of biomass contamination for subsequent use or energy conversion.  Whereas specialist hyperaccumulator plants may achieve higher absolute concentrations of contaminants and exhibit greater bioconcentration and translocation factors, their inherently lower biomass productivity means that both biomass, energy yield and total mass of contaminants removed per unit area will be relatively small.  In contrast, high yielding, low contaminant uptake characteristics, such as for conventional energy crop species, would result in greater energy production, economic viability and greater potential for biomass utilisation.

In the UK the CERESiS project has utilised long-term field trials originally established during the BioReGen (Biomass, Remediation, re-Generation: Reusing Brownfield Sites for renewable energy crops) EU Life demonstration Project (LIFE05 ENV/UK/000128) in 2007.  These allowed direct comparison of the actual contaminant removal rates of three crop species:  Although the biomass of Miscanthus and short-rotation coppice Salix contained higher concentrations of certain elements, Phalaris far out-performed these in terms of biomass, ease and economy of production [3].  Surprisingly, despite lower contaminant concentrations in Phalaris, such was the increased biomass yield that the total mass removed was still greater than for Miscanthus or Salix.  Likewise Pennisetum (Napier and Capiaçu grasses) shows similar promise in Brazil as the most productive, resulting in the highest offtake of Cr from soils contaminated with this element.  This suggests that low-uptake phyto-excluding plants which can tolerate contaminated soils and grow productively might still represent the best and most economically viable option for clean-up of contaminated sites. Meanwhile this nature-based solution can simultaneously deliver a variety of wider societal and environmental benefits, such as greening-up derelict land or the enhanced storage of carbon in soil [4].

This paper will investigate this strategy by comparing biomass yield, biomass contamination and the calculated offtake of contaminants for a wide range of generic contaminants across all of the CERESiS trial sites.  This will be used to evaluate the potential trade-offs between biomass suitability for use and phyto-management of contaminated land.

 

 [1] This study is part of the CERESiS (ContaminatEd land Remediation through Energy crops for Soil improvement to liquid biofuels Strategies) Project which has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 101006717, www.ceresis.eu

 [2] Mellor et al 2020, RaSER 135, 110220

 [3] Lord, 2015, BioBE 78, 110-125

 [4] Lord & Sakrabani, 2019, STotEn 686, 1057-68

 

How to cite: Nunn, B., Torrance, K., Wright, B., Colantoni, A., Bianchini, L., Alemanno, R., Tryboi, O., Severino, M., Leandro, W., and Lord, R.: Growing perennial rhizomatous grasses on contaminated land: a strategy for combining phyto-management with sustainable biomass production?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7435, https://doi.org/10.5194/egusphere-egu24-7435, 2024.

EGU24-8557 | Posters on site | SSS7.1

Simultaneous immobilization of several heavy metals in naturally contaminated soils using waste and recycled materials 

Takeshi Saito, Yoshishige Kawabe, and Naoki Watanabe

The water leachable amounts of heavy metals including arsenic (As), lead (Pb), and cadmium (Cd) can be found in relatively higher concentrations in surplus soils from construction activities. There is a potential risk to human health and negative impacts on the soil and water environment. One of the cost-effective and efficient strategies for remediation techniques is the immobilization of heavy metals based on natural and artificial materials. The objective of this study is therefore to use five waste and recycled materials such as fly ash and recycled concrete. It tries to achieve simultaneous immobilization of several heavy metals in naturally contaminated soils. Two representative natural soils containing relatively higher concentrations of water leachable As, Pb, and Cd were selected and tested for a simple batch immobilization experiment in the laboratory. The weight percent of each waste and recycled material added to each soil was 2.5%, 5%, and 10%. After 24 hours of curing at 20oC, 10 times the volume of ultrapure water was added and shaken for 6 hours. The supernatants were filtered through a 0.45 µm filter and the concentrations of heavy metals were measured by ICP-MS. Generally, the immobilization rate of As, Pb, and Cd increased with increasing additive weight of waste and recycled materials. Recycled concrete especially demonstrated simultaneous immobilization of these heavy metals above with its addition of 2.5% to 5%, suggesting a better immobilization performance compared to other waste and recycled materials.

How to cite: Saito, T., Kawabe, Y., and Watanabe, N.: Simultaneous immobilization of several heavy metals in naturally contaminated soils using waste and recycled materials, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8557, https://doi.org/10.5194/egusphere-egu24-8557, 2024.

EGU24-11675 | ECS | Orals | SSS7.1

Understanding the influence of postfire oak afforestation on soil properties 

Luis Filipe Lopes, Erika S. Santos, Leónia Nunes, Paulo M. Fernandes, and Vanda Acácio

The Mediterranean is a fire-prone region where fires have occurred for millennia. Since the late nineteenth century, restoration techniques like tree planting have been widely implemented following fire events. However, at soil level, postfire measures have been mostly focused on soil erosion processes. Depending on several factors, fire can cause more or less significant impacts on soils, such as changes in soil structure and in the availability of element concentrations, or loss of organic matter. Understanding fire impacts on soil is not only crucial for developing effective postfire rehabilitation strategies, but also to mitigate the long-term consequences on soil health and ecosystem functioning.

In our study, we evaluated the effect of postfire afforestation projects on soil characteristics in the long term. We studied 15 afforestation projects implemented in North-Centre Portugal in the period 1994-2006, in deciduous oak stands dominated by Quercus pyrenaica (including seven projects with pure oak stands and eight projects with mixed oak stands). For each project, we established a sampling plot and selected a nearby control area, affected by the same fire event but without oak afforestation or evident management. Fieldwork was conducted in 2021, when most projects (10) were between 12 and 17 years old, while the remaining projects (5) had been implemented between 21 and 25 years ago. One composite sample of superficial soil (0-5 cm of depth) was collected per plot, performing 15 soil samples in project areas and 15 samples in control areas. Each soil sample was characterized physicochemically for: proportion of fine/coarse fraction; pH(H2O); organic Carbon (Corg); total N content; and available nutrients concentration. Posteriorly, we calculated two proxy variables: Soil Quality Index (SQI), which allows to evaluate the overall soil health condition; and the C/N ratio, as an indicator of organic matter mineralization process.

For both afforested and control areas, soils (mostly classified as Cambisols) presented pH values of approximately 5 (slight acidity), fine particles (< 2 mm) averaged between 67% and 69%, and no trace elements of enrichment. Soils from afforestation plots displayed higher K concentrations, while soils from control plots exhibited higher fertility levels based on Corg, N, and available P. No significant differences were observed in C/N ratios between afforested and non-afforested areas (14.9 vs 16.6), which indicates a relatively fast decomposition and N mineralization. Similarly, no significant differences were observed in the SQI. The lower Corg contents of afforested soils can be attributed to soil management (soil mobilization and management of the understory), which can contribute to the degradation of organic matter when the ecosystem is sensible due to the fire perturbation. Soil mobilization with disc harrowing was the predominant technique (40%). Further research should focus on understanding the effects of different postfire management options on soil properties over time, including in areas without evident enrichment/contamination problems, to improve postfire soil rehabilitation and sustainable forest management.

Acknowledgment: This research was supported by UID/AGR/04129/2020, UID/BIA/50027/2019, PD/BD/142963/2018 and PD/00157/2012.

How to cite: Lopes, L. F., Santos, E. S., Nunes, L., Fernandes, P. M., and Acácio, V.: Understanding the influence of postfire oak afforestation on soil properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11675, https://doi.org/10.5194/egusphere-egu24-11675, 2024.

EGU24-11896 | Posters on site | SSS7.1

Soil restoration for urban areas: Exploring water-related ecosystem services and hydrological functionality  

Vesna Zupanc, Anna Zeiser, Sebastian Rath, Peter Strauss, Helena Grčman, Marko Zupan, Anja Gantar, Urša Pečan, Matjaž Pirnat, and Thomas Weninger

The challenge of restoring degraded landscapes or ecosystems and recultivating them in a way that maximizes the multifunctionality of the artificial soil depends on the extent of soil degradation and its causes. The process of land restoration is expensive, time-consuming and requires careful planning and collaboration between different stakeholders and sectors. In densely populated regions such as Central Europe, there are two major types of artificial soil ecosystems: restoration of landfills or mining pits and urban green infrastructure (e.g. urban tree sites, stormwater retention areas). To compensate for the increasing scarcity of arable land, soils with unfavorable properties must be improved and degraded land must be rehabilitated in order to fulfill soil functions and promote agricultural production.

Engineered soils offer a solution for construction the top layer that allows the restored ecosystem to function. Such soils are made from excavated material and other mineral or organic waste and are composed to provide suitable conditions for plant growth and other ecosystem services provided by the soil.

As the need for green spaces in urban areas is also increasing, e.g. to adapt and mitigate the urban heat island effect, soil is needed as a habitat for plants and engineered soil mixtures are required depending on the target location and purpose. Soil mixtures with suitable chemical, physical, biological and geotechnical properties (i.e. physical structure) are needed, which are suitable for the restoration of topsoil for various purposes (e.g. mining reclamation, urban greening) and can be used for the near-natural composition of functional soil layers suitable for reclamation and plant growth. Soil structural properties such as infiltration rate, pore volume and water retention capacity are crucial for the functionality of restored soils in the water cycle, especially in view of the increasing challenges posed by ongoing climate change.

The aim of this study is to provide a comprehensive overview of the experiences made at research sites in Slovenia and Austria with the application of engineered soils for the restoration of degraded areas. The focus of the contribution is set on different regulatory requirements and methods to ensure the proposed soil hydrological functionality.

This research has been financed by ARIS BI-AT-22-23-019, LIFE20 IPE/SI/000021 ReStart and OEAD WTZ SI 01/2023.

How to cite: Zupanc, V., Zeiser, A., Rath, S., Strauss, P., Grčman, H., Zupan, M., Gantar, A., Pečan, U., Pirnat, M., and Weninger, T.: Soil restoration for urban areas: Exploring water-related ecosystem services and hydrological functionality , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11896, https://doi.org/10.5194/egusphere-egu24-11896, 2024.

EGU24-12080 | ECS | Orals | SSS7.1

Boosting CO2 sequestration potential of a degraded soil by hydrochar from sewage sludge 

Álvaro Amado-Fierro, Rubén Forján, Erika S. Santos, José Luis R. Gallego, and Teresa A. Centeno

A dramatic loss of healthy soils is occurring worldwide due to degradation and desertification by both natural and anthropogenic processes. Such actions accelerate the depletion of soil organic carbon (SOC), turning soil from a major CO2 sink to a source of CO2 emissions.

On the other hand, global overpopulation is causing an unprecedented generation of sewage sludge. The high water content of sewage sludge makes it ideal for hydrothermal carbonization (HTC), a novel thermochemical conversion technology in which water acts as a reagent and catalyst to obtain a C-enriched solid known as hydrochar.

In this study, the impact of a hydrochar (H) obtained from sewage sludge (HTC at 195 °C for 3 hours) and a biochar (B) produced by standard carbonization of holm oak (500 °C) on the capacity of a degraded soil for capturing carbon is evaluated. The soil under study comes from a landfill of industrial origin that over time was mixed with natural sandy soil, resulting in a technosoil with a low SOC content and incapable of supporting stable vegetation.

The experiment was carried out in 60-l IBC containers, thus constituting a larger scale variation of the classic pot tests. Containers with only original soil (S) and those amended with 10 wt.% hydrochar (SH) and biochar (SB), after 15 days of stabilisation of the amendments, were vegetated with Lolium perenne and left for 12 months outdoors.

At a depth of 0-10 cm, both treatments increased the concentration of labile fractions of SOC, extracted respectively with cold water and hot water. In contrast, in the 10-20 cm layer, this effect was also relevant in the container SH. This could be attributed to the migration of the hydrochar along the profile, facilitated by its finer particle size. Both materials, B and H, contributed positively to enhancing the amount of recalcitrant organic carbon (R) in the soil, although the impact was greater with the use of biochar. Average values of R~30 g·kg-1 have been detected for both 0-10 and 10-20 cm depths in the container with SB. In the case of SH, the migration of hydrochar led to R concentration of 13.08 g·kg-1 in the upper 10 cm and 27.40 g·kg-1 at 10-20 cm layer.

Biochar and hydrochar efficiently managed to store organic carbon in soil, but the former caused a higher increase in reserves due to a greater contribution of recalcitrant carbon (Pearson correlation between R and SOC stock of 0.96, P < 0.01). The stock in SB reaches 48.13 and 32.10 tC·ha-1 at 0-10 and 10-20 cm, respectively, whereas the corresponding values in SH were 20.53 and 32.13 tC·ha-1.

On the other hand, it was found that the 197 g of biomass generated in SC was reduced to 165 g when biochar was added, suggesting the capacity of B to fix certain nutrients and make them less accessible to vegetation in the short term. In contrast, hydrochar application increased the amount of vegetation to 478 g, thus favouring greater carbon sequestration.

How to cite: Amado-Fierro, Á., Forján, R., S. Santos, E., R. Gallego, J. L., and A. Centeno, T.: Boosting CO2 sequestration potential of a degraded soil by hydrochar from sewage sludge, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12080, https://doi.org/10.5194/egusphere-egu24-12080, 2024.

EGU24-12514 | ECS | Posters virtual | SSS7.1

Post-fire restoration impacts on soil microbial communities in a Mediterranean region 

Beatriz Roncero Ramos, Montserrat Romero, Pedro Antonio Plaza Álvarez Plaza Álvarez, Manuel Esteban Lucas-Borja, and Miriam Muñoz-Rojas

Fire is a natural element of the landscape; however, it can also have serious effects on the environment. Although the effect of fire on plant communities has been broadly studied, we lack information on the effect of fire on soils. Several types of post-fire treatments have been applied in Mediterranean areas for soil protection and potential regeneration of soil fertility, i.e. logging or mulching. Yet, the effect of these treatments on the soil biodiversity are not fully understood.

Here, using different soil physical and biological approaches methods, we analysed the impacts of different post-fire treatments on the composition and diversity of microbial communities (bacteria and fungi) in a Mediterranean forest. Our results showed substantial differences in the responses of the fungal community to the different post-fire treatments, i.e. straw mulching and salvage logging . Opposite, the soil bacterial community was not affected by the post-fire treatments. Overall, soil fungi were more sensitive than bacteria to fire, but the recovery of this taxa following the fire event was faster. Our results can provide useful information for restoration of fire-impacted areas in the Mediterranean region.

How to cite: Roncero Ramos, B., Romero, M., Plaza Álvarez, P. A. P. Á., Lucas-Borja, M. E., and Muñoz-Rojas, M.: Post-fire restoration impacts on soil microbial communities in a Mediterranean region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12514, https://doi.org/10.5194/egusphere-egu24-12514, 2024.

EGU24-12662 | ECS | Posters virtual | SSS7.1

Indigenous soil microbial inoculants promote restoration of arid plants in saline soils 

Fred Dadzie, Nathali Machado, and Miriam Muñoz-Rojas

Salinity is one of the challenges affecting seed germination and establishment in dryland restoration projects. Seeds must overcome the osmotic pressure present in saline soils before they can germinate. An ideal method is to reduce the osmotic potential through continuous irrigation to flush out the excess salts from the soil to enable seeds to germinate. However, such a system is impractical at scale and would exponentially increase restoration budgets. Research has shown that bacteria and cyanobacteria individually improve seedling germination. However, it is unclear whether bacteria and cyanobacteria improve seedling germination individually and as combined entities under dryland conditions. In this glasshouse study, we test the hypothesis that, inoculating seeds with bacteria, cyanobacteria and the combination of both will increase seed germination outcome compared to their none inoculated counterpart. We also examined which microbial inoculation would yield the greatest seedling germination and biomass. We found that all inoculated seeds with microorganisms significantly increased seedling emergence and biomass production compared to the non-inoculated seeds. The highest seedling emergence was found in the cyanobacteria treatment followed by the combined bacteria and cyanobacteria treatment. Similarly, the highest biomass production occurred when seeds were inoculated with cyanobacteria treatment followed by bacteria treatment. Our results suggest that, cyanobacteria can be used as a potential tool to overcome seedling germination challenges in saline dryland ecosystems during restoration.

How to cite: Dadzie, F., Machado, N., and Muñoz-Rojas, M.: Indigenous soil microbial inoculants promote restoration of arid plants in saline soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12662, https://doi.org/10.5194/egusphere-egu24-12662, 2024.

EGU24-13763 | ECS | Posters on site | SSS7.1

Removal of strontium and cesium from soil using ion-based washing agents with similar hydrated radii 

Hojae Song, Gunwoo Shim, and Kyoungphile Nam

The environmental hazards associated with nuclear power plants, specifically the release of fission byproducts such as strontium (Sr) and cesium (Cs) are highlighted for their harmful attributes, even in non-radioactive forms owing to their physicochemical characteristics and potential health risks. Sr and Cs exhibit significant physicochemical resemblances to calcium (Ca) and potassium (K), respectively. These similarities are so pronounced that the human body often confuses Sr and Cs with Ca and K, leading to their accumulation. This accumulation can give rise to detrimental health conditions, including leukemia, thyroid cancer, bone marrow cancer, and general paralysis. In this study, a soil washing method was employed to eliminate Sr and Cs contaminants from the soil. We hypothesize that the efficiency of Sr and Cs removal is influenced by the resemblance in physicochemical properties. Physicochemical properties such as atomic radius, hydrated radius, electronegativity, and electron affinity of Sr, Cs, Na, Mg, K, Ca, Ba, and Al were carefully studied and summarized for the investigation. Subsequently, solutions with Na, Mg, K, Ca, Ba, and Al at concentrations of 0.1 and 0.01 M, with a pH of 7, were tested for their efficacy in removing Sr and Cs from the soil. The results showed that the greater similarity in hydrated radius between heavy metals and ions appears to be responsible for increased removal efficiencies. For example, both Ca and Sr share the same hydrated radius of 0.412 nm. Interestingly, Ca exhibited the highest efficiency in removing Sr compared to Na, K, Mg, Ba, and Al. Additionally, Ba, with a hydrated radius of 0.404 (the second closest to Sr), demonstrated the second-highest efficiency in Sr removal. Examining results for other heavy metals (i.e., Cd, Co, Cu, Ni, Pb, and Zn), a heightened resemblance in hydrated radii between the heavy metal and ion corresponded to increased removal efficiency, indicating a strong positive correlation. Overall, this study contributes valuable insights into effective strategies for mitigating the environmental impact of nuclear power plant activities on soil contamination.

How to cite: Song, H., Shim, G., and Nam, K.: Removal of strontium and cesium from soil using ion-based washing agents with similar hydrated radii, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13763, https://doi.org/10.5194/egusphere-egu24-13763, 2024.

EGU24-16797 | Posters virtual | SSS7.1

 Soil microbial based strategies and seed enhancement technologies reconnect plant-soil biodiversity and improve restoration outcomes  

Miriam Muñoz-Rojas, Frederick Dadzie, and Nathali Machado de Lima

Soil microorganisms control important ecosystem functions such as nutrient cycling, plant productivity and climate regulation. Thus, microbially assisted conservation and restoration has the potential to reconnect above and belowground dynamics, creating functional ecosystems that are more resilient to climate change impacts. In this research, we (i) assessed the responses of soil microbial communities to disturbance, e.g., severe fire, and extractive activities such as mining, and (ii) developed bioinoculants composed of locally sourced soil bacteria from the rhizosphere and biocrust cyanobacteria, to promote plant growth and soil fertility and enhance ecosystem capacity for global change adaptation. This presentation will showcase some key findings of these studies conducted in contrasting Australian ecosystems (shrubland-grassland in the arid zone, and subtropical/temperate forests). These outcomes include the successful translocation of whole-soil communities for inhibiting weeds, and the effective use of indigenous microbes (rhizobacteria and cyanobacteria combinations) for soil carbon sequestration, nitrogen fixation, and growth promotion of key arid and temperate plant species.

Overall, our research demonstrates the benefits of using native microbial communities as bioinoculants in ecosystem restoration. The emerging technologies used in our research, i.e. seed enhancement through seed biopriming and biopellets, have a large potential for landscape-scale conservation and restoration programs in the context of global change.

How to cite: Muñoz-Rojas, M., Dadzie, F., and Machado de Lima, N.:  Soil microbial based strategies and seed enhancement technologies reconnect plant-soil biodiversity and improve restoration outcomes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16797, https://doi.org/10.5194/egusphere-egu24-16797, 2024.

EGU24-16991 | Orals | SSS7.1

Anticoccidia presence in slurries/manures and agricultural soils in Galicia (NW Spain) 

Ana Barreiro, Raquel Cela-Dablanca, Ainoa Míguez-González, Debora Casagrande Pierantoni, Carolina Nebot, Avelino Núñez-Delgado, María J. Fernández-Sanjurjo, and Esperanza Álvarez-Rodríguez

Coccidiosis is one of the most important parasitic diseases, responsible for significant damage affecting animal production worldwide. It is caused by different protozoan species belonging to the genera Eimeria and Isospora. To treat and prevent this disease ionophore antibiotics are widely used in veterinary medicine especially in food-producing animals as food additives. Ionophore coccidiostats, such as monensin, salinomycin, lasalocid or narasin have been a key tool in the fight against coccidiosis for more than 40 years. Non-ionophore coccidiostats, such as robenidine, toltrazuril and decoquinate are also widely used to treat coccidiosis. All these compounds are toxic to humans, which explains why they are not used as pharmaceuticals in human medicine and are only used in veterinary medicine. Release of these anticoccidiostat in agricultural soils, through the application of manures and slurry from treated animals, poses a risk as crops could uptake coccidiostats and start entering the food chain, risking human health. The objective of this study was to perform a survey of the presence of anticoccidial in slurries from medicated animals and the soils where these manures were applied, to assess the risk of soil pollution.

A total of 66 slurries/manures from different animals were collected: poultry (16), veal (17), cow (10), pig (10), rabbit (12), and one sample which was a mixture of cow and pig slurry. Likewise, the soils that were amended with those slurries (76 in total) were also sampled by collecting samples at two different depths: 0-5 cm and 5-20 cm. The presence of ionophore antibiotics, non-ionophore and compounds from various therapeutic groups were analysed in all the samples (slurries/manures and soils) by HPLC-MS/MS. The results showed that 53% of the slurry/manure samples and 25% of the soil samples presented some pharmaceutical product. Focusing on ionophore antibiotics in slurry/manure, 21% and 4.5% of the samples presented narasin and salinomycin, respectively; these two antibiotics were not detected in the soils, but other ionophore, such as monensin, was detected in 4% of the soil samples in the 0-5 cm soil depth. Ionophore antibiotics were not detected in the soil depth of 5-20 cm, indicating a low mobility of these compounds, possibly related to a strong adsorption by soil components. The non-ionophore anticoccidial robenidine and decoquinate were present in 8% of manure/slurry and 1% and 11% of soil samples respectively; meanwhile toltrazuril appeared in 2% of manures/slurries. Moreover, 15 other pharmaceutical compounds were detected:  one corticosteroid (dexamethasone), one anti-inflammatory (diclofenac), one antifungal (griseofulvin) and 12 antibiotics from different groups (tylosin, trimethoprim, sulfadiazine, sulfamethazine, sulfachloropyridazine, enrofloxacin, ciprofloxacin, levofloxacin, lincomycin, doxycycline, oxytetracycline, tetracycline). In summary, narasin was the most frequent present in slurries/manures and the decoquinate in soils.

Even though the focus of our project was the anticoccidial compounds, the fact that we detected a wide array of other pharmaceutical products highlight the risk that suppose the overuse of these compounds in animal farms for both environmental and human health.

How to cite: Barreiro, A., Cela-Dablanca, R., Míguez-González, A., Casagrande Pierantoni, D., Nebot, C., Núñez-Delgado, A., Fernández-Sanjurjo, M. J., and Álvarez-Rodríguez, E.: Anticoccidia presence in slurries/manures and agricultural soils in Galicia (NW Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16991, https://doi.org/10.5194/egusphere-egu24-16991, 2024.

EGU24-17992 | Posters on site | SSS7.1

Adsorption and desorption of the ionophore antibiotics narasin and monensin in soils and bioadsorbents from Galicia (NW Spain) 

Esperanza Alvarez-Rodríguez, Raquel Cela-Dablanca, Ana Barreiro, Ainoa Míguez-González, Avelino Nuñez-Delgado, and María J. Fernández-Sanjujo

Ionophore antibiotics, such as narasin and monensin, are widely used in the poultry industry and are the only type of antibiotics that the EU allows to incorporate as feed additives, and use them without veterinary prescription, with the consequent risk of favouring antibiotic bacterial resistance. In the case of the narasin it has been proved that, in poultry, the use of this antibiotic may increase the number of enterococci bacteria that are resistant to the human antibiotic vancomycin; meanwhile ruminal Prevotella strains might become resistant to monensin. Furthermore, these drugs are very toxic to humans. For these reasons, the entrance of antibiotics in the environment due to the use of manure and slurry as fertilizers in agricultural soils is an important environmental problem and a risk for human and animal health. The soil can adsorb these antibiotics and prevent their entry into the food chain, but sometimes its retention capacity is low and could be improved by incorporating residues that can act as contaminant adsorbents. The objective of this study was to analyse the adsorption and desorption processes in three soils and four different biadsorbents for narasin and monensin. The study was perform using one forest soil under Eucalyptus and two crop soils, and four different by-products as bioadsorbents (wood ash, pine bark, mussel shell and olive residue). Different concentration (5, 10, 20, 50, 100, 200, 400, 800, 1000 µmol L-1) of both antibiotics were added to both soils and bioadsorbents and adsorption / desorption test were performed by means of HPLC.

The results showed that the soils adsorbed 100% of the added monensin at low concentrations, and this percentage decrease to 80-86% when 1000 µmol L-1 of antibiotic were added. The adsorption was irreversible for the low concentrations and the desorption increase up to a maximum of 1-12% for the higher ones. Regarding the bioadsorbents, for the higher concentration of monensin added, the olive residue and wood ash adsorbed 99 and 98% of the antibiotic, respectively. On the other hand, the pine bark and mussel shell adsorbed a maximum of 64 and 48%, respectively, for the lower concentrations and these percentages decreased to 25 and 34% when 1000 µmol L-1 were added, with generally small desorption values. For the antibiotic narasin, the soils adsorbed 100% of the added antibiotic, and only decreases to 99% when 1000 µmol L-1 are added; and they desorbed less than 1% of the absorbed at that concentration. Regarding the bioadsorbents, the olive residue adsorbs irreversibly 100% of the narasin added for all concentrations, meanwhile the mussel shell, wood ash and pine bark adsorbed 86, 89 and 96%, respectively, for the highest narasin concentration, with no desorption for any antibiotic concentration.

The soils, olive residue and wood ash were good bioadsorbents for both antibiotics, due to their high adsorption capacity, irreversible in most cases. The pine bark and mussel shell were as well good bioadsorbents for naransin, but that´s not the case for monensin.  

 

How to cite: Alvarez-Rodríguez, E., Cela-Dablanca, R., Barreiro, A., Míguez-González, A., Nuñez-Delgado, A., and Fernández-Sanjujo, M. J.: Adsorption and desorption of the ionophore antibiotics narasin and monensin in soils and bioadsorbents from Galicia (NW Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17992, https://doi.org/10.5194/egusphere-egu24-17992, 2024.

EGU24-18570 | ECS | Posters on site | SSS7.1

Salinomycin and lasalocid adsorption/desorption by different soils and bioadsorbents from Galicia (NW Spain). 

Raquel Cela Dablanca, Ana Barreiro, Ainoa Míguez González, Avelino Núñez Delgado, María J. Fernández Sanjurjo, and Esperanza Álvarez Rodríguez

Salinomycin and lasalocid are polyether ionophore antibiotics commonly used in animal production as anticoccodia. These antibiotics are partially metabolised and excreted at least partially in the active form. Therefore, these drugs enter the environment mainly by direct deposition of urine and faeces on soil, or when manure is applied to soils as fertilizer, facilitating their subsequent entry into the food chain, as well as the development of bacterial resistance and risks to human and animal health. Soils can potentially reduce environmental risks related to these antibiotics through the adsorption on their components, which implies its immobilization. Adsorption depends on the antibiotic characteristics and physicochemical soil´s properties. Some soils have a low capacity to retain antibiotics, for this reason is necessary to investigate low-cost strategies to increase the adsorption capacity of the soils, minimizing environmental pollution. Pine bark, oak ash, mussel shell and olive residue could be used as bioadsorbents of these contaminants, since they have a high adsorption capacity for other antibiotics and are produced in large quantities in several countries. The objective of this work was to investigate the adsorption/desorption capacity of salinomycin and lasalocid of three soils from Galicia (NW Spain) with different properties, and also that of the four residues previously indicated, which could be added to soils to improve the adsorption capacity of these antibiotics. To carried out this work, batch experiments were performed, adding different concentrations (5; 10; 20; 50; 100; 200; 400; 800 and 1000 µmol L-1) of these antibiotics at 2 grams of soil or 0.5 grams of bioadsorbent samples; the antibiotic concentration in equilibrium solution was measured by HPLC-UV

The results obtained showed that lasalocid was adsorbed completely by the soils in all cases, whereas salinomycin was adsorbed totally by soils when the concentration added was between 5-200 µmol L-1, however when the concentration added increased (1000 µmol L-1), adsorption decreased up to 68%.  The results showed that soil with a high pH value (pH=7.97), presented slightly lower adsorption values. In the case of the bioadsorbents, pine bark (pH=3.99), olive residue (pH=5.95) and ash (pH= 11.31) adsorbed 100% of salinomycin in all added concentrations, therefore, these residues could increase the capacity of the soil to adsorb this antibiotic. However, in the case of lasalocid the adsorption by ash was 75%, by olive residue was 94% and 95% by pine bark, when the maximum concentration of antibiotic was added. Mussel shell (pH= 9.39) was the bioadsorbent that presented the lowest adsorption for both antibiotics, 87% for salinomycin and 22% for lasalocid, when 1000 µmol L-1 was added. Desorption results of salinomycin showed that this is always less than 10% for soils and less than 5% for bioadsorbents. In the case of lasalocid, desorption was less than 3% for soils and bioadsobents.

In conclusion, soils adsorbed 100% of lasalocid, however, salinomycin adsorption was lower. To retain this antibiotic, the use of bioadsorbent would be interesting, specially, pine bark, olive residue and ash, which adsorbed all the added salinomycin.

How to cite: Cela Dablanca, R., Barreiro, A., Míguez González, A., Núñez Delgado, A., Fernández Sanjurjo, M. J., and Álvarez Rodríguez, E.: Salinomycin and lasalocid adsorption/desorption by different soils and bioadsorbents from Galicia (NW Spain)., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18570, https://doi.org/10.5194/egusphere-egu24-18570, 2024.

EGU24-20237 | ECS | Posters virtual | SSS7.1

Experience of a two-year phytoremediation field trial in the “Phy2Climate” project: Lithuanian case 

Zygimantas Kidikas, Mantas Rubezius, and Alfreda Kasiuliene

Phytoremediation is considered as an environmentally friendly and cost-effective technology for the treatment of contaminated soil. Recently, there has been an increase in large-scale phytoremediation projects, one of the key moments of which is the transition from a pot experiment to large-scale field research under real conditions. The “Phy2Climate” project aims to provide clean biofuel production and phytoremediation solutions from contaminated lands worldwide, and field trials under real conditions was a focal point in this project. The trials were established in countries like Serbia, Spain, Argentina, and Lithuania, to cover different climatic conditions and differently polluted areas.

In Lithuania, the field trials were established in a site that was formerly used as oil base in Soviet times and up-until-today exhibits contamination with petroleum hydrocarbons. Main method for phytoremediation of petroleum-contaminated soil is the rhizodegradation, which focuses on stimulating the population of organic-degrading microorganisms through the plant rhizosphere. Thus, contaminated soil in the site was amended with organic and mineral fertilizers to promote plant development and increase biomass outputs. Furthermore, microbial  additive applied to ensure rhizodegradation. Two monocultures (amaranth (Amaranthus caudatus) and Jerusalem artichoke (Helianthus tuberosus) and a mix of herbaceous plant species were grown on different subplots in the prepared soil for two consecutive years. The key parameters used to assess the efficiency of phytoremediation included biomass output, crucial for ensuring an adequate amount for biofuel production, and the phytoremediation factor, indicating changes in petroleum hydrocarbon concentration in the soil.

How to cite: Kidikas, Z., Rubezius, M., and Kasiuliene, A.: Experience of a two-year phytoremediation field trial in the “Phy2Climate” project: Lithuanian case, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20237, https://doi.org/10.5194/egusphere-egu24-20237, 2024.

EGU24-21208 | Orals | SSS7.1

Development of technical possibilities to restore the ecosystems of quarry heaps 

Annely Kuu and Merrit Shanskiy

The increased global demand for energy has led to the opening of large mining areas worldwide. The largest commercially exploited oil shale deposit in the world (total amount of resources 7x109 tons) is located in North-East Estonia. Mining is essential to provide the resources for industries but can result in a destruction of pre-mining and post-mining ecosystem. Restoring ecosystems is one of the most important aspects of contemporary environmental conservation. Naturally, vegetation and soil develop slowly in quarry areas, and so far, quarry reclamation has been in use. One of the primary challenges encountered in the reclamation of mined areas is the low water retention of the soil, known as hydrophobicity, which hinders the establishment of vegetation and soil development. The aim of current work is to find out the suitable technique and technology for the crust material to cover the planting surface that retains moisture and nutrients, which can be used in plant cultivation and ecosystem restoration when covering quarry areas. The goal is to promote plant growth and thus accelerate forest ecosystem establishment. Four test areas were selected: a technically reclaimed oil shale quarry, an unrecultivated sand quarry, a reclaimed gravel quarry, and an unrecultivated gravel quarry.The tree species used were pine (Picea abies), spruce (Pinus sylvestris), and hybrid aspen (Populus tremula × Populus tremuloides Michx). Planting density was calculated according to the recommendations of the Estonian State Forest Management Centre. In each quarry, 100 pines, 100 spruces, and 100 hybrid aspens were planted. The experimental design included a control variant, biochar, sheep wool pellets, sheep wool discs (that are used as mulching material), and two types of biodegradable mulch film, in two replications. The trees were planted in May 2023, and the monitoring of their survival is still ongoing. However, based on the preliminary results, it can be stated that biochar, sheep wool discs, and various biodegradable mulch films had a positive impact on the survival of forest trees. This research is supported by the Circular Economy program of the Environmental Investment Centre through a project with the number RE.4.09.22-0034 and by developmental project of Estonian University of Life Sciences “Valorization of sheep wool for agricultural utilization”.

How to cite: Kuu, A. and Shanskiy, M.: Development of technical possibilities to restore the ecosystems of quarry heaps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21208, https://doi.org/10.5194/egusphere-egu24-21208, 2024.

EGU24-21714 | Orals | SSS7.1

Phytoremediation of pesticide- and mineral oil-contaminated soils with perennial grasses in Ukraine 

Oleksandra Tryboi, Ludmila Romantschuk, and Nataliia Matviichuk

The most frequent contaminants of soil in Europe are heavy metals and mineral oil [1]. There are more than 5000 pesticide-contaminated in Ukraine that require cleanup [2]. In Ukraine before Russian invasion, according to the State Service of Ukraine for Geodesy, Cartography and Cadastre (StateGeoCadastre) there were around 125.44 thousand hectares of lands, contaminated by industrial and other waste as of January 1, 2019 [3]. Areas contaminated with explosives and mineral oil as a result of military activities after Russian invasion are under assessment, but can amount at least 5 million hectares of agricultural lands [4].

Phytoremediation with perennial grasses can be a solution to large areas of contaminated lands in Ukraine, as it can be used to extract heavy metals and speed up degradation of organic contaminants [5].

During 2021-2023, field trials performing phytoremediation approach were conducted at two contaminated sites in Ukraine within CERESiS (ContaminatEd land Remediation through Energy crops for Soil improvement to liquid biofuels Strategies) H2020 Project (GA 101006717). First site with fuel and mineral oil contamination and the second - with pesticides contamination, located in the north-western region of Ukraine. Pesticide contamination of the site occurred through minor leaks as a result of a long-term use of pesticides warehouse. Contamination with the fuel oil occurred through small leaks as a result of over 40 years of use and storage of fuel and lubricants by refuelling agricultural machinery. Both contaminated sites represent historical contamination as neither pesticides, nor fuel have been used or stored on the farm for more than 10 years. Baseline soil characterization showed that sites had significant chromium contamination, as well as high quantities of antimony, cadmium, hexachlorocyclohexane and petroleum products.

For phytoremediation, trial sites were planted with Miscanthus x giganteous and Phalaris arundinacea. Both plants showed good performance, but Phalaris presented strong dependency on water availability. The second year harvest showed Miscanthus yield around 20 t of dry matter per hectare, and Phalaris more than 5 t of dry matter per hectare at both contaminated sites. Soil characterization after 2 years of growing showed promising phytoremediation potential of both crops with Miscanthus showing better results with decontamination from HCH, Chromium, Cadmium, Antimony and Stanum, and Phalaris performing more efficiently regarding decontamination from petroleum products and phenols.

[1] Pérez & Eugenio (2018).

[2] Moklyachuk et al. (2010).

[3] Information of State Service of Ukraine for Geodesy, Cartography and Cadastre №6-28-0.21-4979.2-19 from 07.06.2019.

[4] https://www.pravda.com.ua/eng/news/2023/03/3/7391820/

[5] https://www.bbc.com/future/article/20230221-the-toxic-legacy-of-the-ukraine-war

 

How to cite: Tryboi, O., Romantschuk, L., and Matviichuk, N.: Phytoremediation of pesticide- and mineral oil-contaminated soils with perennial grasses in Ukraine, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21714, https://doi.org/10.5194/egusphere-egu24-21714, 2024.

EGU24-21724 | Orals | SSS7.1

A novel method for reforestation of desertified areas using composites for encapsulating moisture 

Merrit Shanskiy, Jüri Liiv, Annely Kuu, Jordi Escuer Gatius, Catherine Githuku, and Marclus Mwai

Soil has stored organic carbon in the form of humus for thousands years. One of the main problems in the near future is agricultural land degradation due to excessively intensive farming. The aric and semi-arid lands in Kenya constitues about 80% (467,200 sq.km) of total land mass. Thus, the arid and semiarid land hosts 35% of Kenyas population (13 million people). The objective of the project was to explore the feasibility of restoring vegetation in desertified areas by implementing individual, isolated moisture reservoirs for each plant, filled with a water-binding composite material. The ultimate goal of this study includes the rapid reforestation of desertified areas, accompanied by the restoration of the region's moisture regime to mitigate climate change. Additionally, it aims at carbon dioxide sequestration in emerging forest areas, as well as C binding in a solidifying composite material. The study also seeks to create conditions for the regeneration of the natural ecosystem and reduce the pressure on the remaining forests by providing additional wood resources.

It is essential to acknowledge that the experimental plantation, situated at Kenyatta University, would remain part of the permanent landscaping according to the university's agreement. The eucalyptus sp. was excluded, and more widely used plant species for the region were chosen. After careful deliberation —Grevillea robusta, Casuarina equisetifolia, and Jacaranda mimosifolia—were chosen as commonly used species for local agroforestry systems. The plantation was established after dry season in september, 2023. The local resource based biomaterials were used for composites mixtures and planting materials were created. For some variants hydroinsulation with bioplymer designed biofilm was used.

How to cite: Shanskiy, M., Liiv, J., Kuu, A., Escuer Gatius, J., Githuku, C., and Mwai, M.: A novel method for reforestation of desertified areas using composites for encapsulating moisture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21724, https://doi.org/10.5194/egusphere-egu24-21724, 2024.

EGU24-21834 | Posters on site | SSS7.1

The use of coal as ameliorant for soils with constraints for plant growth 

Thomas Baumgartl, Nima Baghbani, and Franziska Bucka

Increasing global population demands an increased intensity of use of agricultural land, but also to an extension of the use of land previously not suited for agriculture. Likewise, the stabilisation of degraded or reclaimed land e.g. from mining often requires intervention to create conditions which allow soil stabilisation by vegetation.

Mine rehabilitation is often challenged by hard setting or clay rich substrates as the available substrate for shaping the final landform and amelioration is necessary. While chemical amelioration has time limited benefits, long-term physical/mechanical property improvements may lead to better outcomes above all in water limited environments.

In this study we investigated the amelioration of clay substrate with coal with the objective to improve the physical, and potentially also chemical conditions for plant growth. Clay substrate was amended with up to 20%-wt lignite-type coal. The addition of coal occurred in two ways, as fine coal and as crushed coal, still containing aggregates. The clay and clay/coal mixtures were filled into boxes at a height of approximately 0.15m and a total volume of approx. 60 liters. Hydraulic properties were measured following consolidation of the substrate in multiple wetting-drying cycles until the substrate reached a constant height. Samples were extracted to characterise the substrates for their hydraulic and mechanical properties and their biotic activity potential. The test is based on quantifying the production of CO2 through the microbial oxidation of organic carbon compounds in the soil.

The water retention curve tests and analysis (using HYPROP) showed in general an increase of the total pore volume with increase in coal content. The amount of plant available water increased with increase in coal content and was higher with the addition of fine coal, compared to the aggregated coal. The shear strength and cohesive strength decreased with addition of coal. The microbial activity tests showed only small increases in CO2 production and respiration, along with a low mineralisation rate of the added coal based carbon source. The results show, that the addition of a stable carbon source can be beneficial for the improvement of substrate properties.

How to cite: Baumgartl, T., Baghbani, N., and Bucka, F.: The use of coal as ameliorant for soils with constraints for plant growth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21834, https://doi.org/10.5194/egusphere-egu24-21834, 2024.

EGU24-2264 | ECS | Posters on site | BG8.16 | Highlight

Potential of land-based terrestrial carbon sinks to mitigate climate change 

Ang Wang, Yunting Fang, and Geshere Abdisa Gurmesa

Enhancing terrestrial ecosystem carbon sinks is one of the effective strategies to achieve carbon neutrality targets for climate change mitigation. However, efforts to enhance the carbon sink mainly focused on natural climate solutions, including protecting, restoring, and managing terrestrial ecosystems. The contributions of artificial measures, such as rock weathering, urban alkaline material weathering, and desert saline alkali soil water to terrestrial ecosystem carbon sinks have often been overlooked by previous estimates of terrestrial carbon sinks. To account for major carbon sink measures, we proposed a new concept of “four-color” terrestrial carbons based on their formation/sink mechanisms, i.e., green carbon (the carbon sequestered by forest, grassland, and inland wetland), black carbon (carbon sink through the addition of carbon-rich materials, such as straw, organic fertilizers, and biochar to the soil), blue carbon (the carbon stored in coastal ecosystems), and white carbon (carbon sink by chemical processes). We reviewed the potential measures for enhancing the different carbon sinks to provide a framework for achieving carbon neutrality targets.

We identified 15 measures for enhancing the sink of the different carbon groups. The enhancement approaches for green carbon sinks mainly include protecting, restoring, and managing forest, grassland, and inland wetland ecosystems. Adding carbon-rich materials to cropland soil is the major measure to enhance black carbon sink. The enhancement of blue carbon sink mainly focuses on ecosystem protection and restoration. We proposed enhancing silicate and carbonate rock weathering, irrigation and salt washing in arid regions, and utilizing urban alkaline materials as measures to enhance white carbon sink. With proper implementation of the above measures, we estimated C sequestration of 16.7 Pg CO2 yr-1 for green carbon, 5.8 Pg CO2 yr-1 for black carbon, 1.1 Pg CO2 yr-1 for blue carbon, and 7.7 Pg CO2 yr-1 for white carbon. Our results showed the potential to enhance the “four-color” carbon sinks globally by 31.4 Pg CO2 yr-1, higher than the estimate in the IPCC AR6. However, large uncertainties still exist in the estimation of current and future carbon sink potential in terrestrial ecosystems due to the different approaches used in different studies, large spatiotemporal variation, and insufficient data of carbon storage and sink. Therefore, we emphasize the need for strengthening monitoring and basic data acquisition and establishing rapid and accurate quantification techniques for terrestrial carbon sinks. Furthermore, future research should focus on the potential and multiple enhancement measures of white carbon under different climates and its response to global change.

How to cite: Wang, A., Fang, Y., and Gurmesa, G. A.: Potential of land-based terrestrial carbon sinks to mitigate climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2264, https://doi.org/10.5194/egusphere-egu24-2264, 2024.

Between 2000 and 2020, global wildfires emitted approximately 7.32 billion metric tons of CO2, constituting about 18.5% of fossil fuel-related emissions. Despite a decrease in the global burned area, wildfire carbon emissions showed no significant trend. This is because carbon emission of forest fires is increasing, and thus compensates for the reduction in carbon emission from savanna fires. Forest fires is about 5% of global burned area but contribute roughly 20% (1.5 billion metric tons) of these emissions. Increases in forest fire carbon emissions, particularly in the northern high latitudes, are attributed to climate change and human activities. In recent years, the rise in extreme wildfire emissions affects over 40% of global vegetated lands, often linked to extreme fire weather conditions. Addressing this requires the development of advanced forest fire risk identification and prevention technologies.

How to cite: Liu, Z.: Spatial patterns and drivers of wildfire carbon emission since 2000, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2408, https://doi.org/10.5194/egusphere-egu24-2408, 2024.

EGU24-2440 | ECS | Orals | BG8.16 | Highlight

Global Ecosystem Restoration and Carbon Neutrality Programme 

Ruiyang Zhang, Shuli Niu, Werner L. Kutsch, and Guirui Yu

Currently, 25% of global terrestrial ecosystems are degraded, expected to rise by 75% by 2050, threatening 3.2 billion people worldwide. The United Nations launched “UN Decade on Ecosystem Restoration” to promote restoration efforts from 2021-2030. Additionally, achieving carbon neutrality has become an international consensus to combat climate change and protect the human living environment. However, there is a lack of existing international scientific programs for ecological restoration and carbon neutrality, coupled with insufficient long-term observations and experimental data, particularly in developing countries facing ecosystem degradation and management challenges. Therefore, it is crucial to integrate global efforts and establish monitoring and assessment systems for global ecological restoration and carbon neutralization. In this talk, we will introduce the Global Ecosystem Restoration and Carbon Neutrality (Global-ERCaN) program, which aims to promote global ecosystem restoration and carbon neutrality through monitoring and assessing the restoration process, exploring changes in carbon sinks and related processes, and summarizing sustainable ecosystem management models. Global-ERCaN plans to establish international cooperation for 1) sharing carbon neutral research methods and technologies, 2) assessing the role of ecological restoration in carbon neutrality, 3) proposing management and policy options for sustainable development of degraded ecosystems, ultimately accelerating carbon neutrality goals.

How to cite: Zhang, R., Niu, S., Kutsch, W. L., and Yu, G.: Global Ecosystem Restoration and Carbon Neutrality Programme, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2440, https://doi.org/10.5194/egusphere-egu24-2440, 2024.

EGU24-2500 | Posters on site | BG8.16

Soil GHGs Emission response to Landuse Change in Tropics, Southwest China 

Wenjun Zhou, YIping Zhang, Liqing Sha, Qinghai Song, Jingo Gao, Xunhua Zheng, Junhui Zhang, Dan Xi, and Yunting Fang

To explore the response of soil greenhouse gas emissions(GHGs) from tropical forest to landuse change in Yunnan, Southwest China, we have conducted a series of studies based on the GHGs monitoring platform established since 2003 in tropical rainforest (TRF) and rubber plantation(RP). The research results indicate that 1) TRF transplanted to RP did not change the annual soil CO2 emissions (TRF, 359 ±91 and RP 352 ±41 mg CO2 m-2 h -1) but decreased soil CH4 uptake significantly (TRF, -0.11 ± -0.18 mg CH4 m -2 h -1; RP, -0.020 ± -0.087 mg CH4 m-2 h-1). (2) The most important influence on soil CO2 and CH4 emissions in the RP was the leaf area index and soil water content, respectively, whereas the soil water content, soil temperature, and dead fine roots were the most important factors in the TRF. Variations in the soil CO2 and CH4 caused by landuse transition were individually explained by soil temperature and fine root growth and decomposition, respectively. (3)  The N2O emissions from the fertilized and unfertilized plots in RP were 4.0 and 2.5 kg N ha−1 yr−1, respectively; Annual N2O emissions from the control and no litter input treatments were 0.48 and 0.32 kg N2O–N ha-1 year in TRF, respectively.(4) When entire land area in Xishuangbanna is considered, N2O emissions from fertilized rubber plantations offset 17.1% of the tropical rainforest’s carbon sink. The results show that if tropical rainforests are converted to fertilized rubber plantations, regional N2O emissions may enhance local climate warming. (5) And further, land use change alter the structure and sources of soil organic matter, which in turn feedback to the microbial processes involved in soil greenhouse gas production and alter the mechanisms of soil greenhouse gas emissions.(6) The 15N isotope tracing experiment used isotope tracing technology to distinguish the microbial process of N2O production in tropical rainforest soil, proving that the microbial process of N2O production in tropical rainforest soil during the dry season is a nitrification process; In the future, we will use 13C,14C and 15N isotope and qPCR to study the microbiological mechanisms of land use change on soil greenhouse gas production in the context of climate change, providing scientific basis for quantifying the underground processes of soil greenhouse gas production; Provide mechanism support for accurately estimating soil greenhouse gas emissions to achieve the dual carbon goals in the context of climate change.

How to cite: Zhou, W., Zhang, Y., Sha, L., Song, Q., Gao, J., Zheng, X., Zhang, J., Xi, D., and Fang, Y.: Soil GHGs Emission response to Landuse Change in Tropics, Southwest China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2500, https://doi.org/10.5194/egusphere-egu24-2500, 2024.

Terrestrial ecosystems sequester about a third of anthropogenic CO2 emissions by natural processes and, thus, play a critical role in mitigating climate warming. As climate change become more aggravated, the need to remove CO2 from the atmosphere to the terrestrial and aquatic ecosystems becomes more urgent over time. A score of new techniques of carbon dioxide removal (CDR) have been recently proposed based on a notion of actively managing land carbon cycle processes to increase carbon sequestration and/or reduce greenhouse gas (GHG) emissions. These actively managed climate solutions by human (i.e., human-based) should be complementary to the nature-based climate solutions to combat climate change together with concurrent and dramatic economy-wide decarbonization. However, what are ecological principles behind the terrestrial CDR techniques? How can the ecological principles identified from these removal techniques be used to guide the design of more effective, future CDR techniques? These questions remain unanswered.

 

This presentation will show ecological principles we identified from our analysis of these existing CDR techniques and propose more effective techniques for carbon dioxide removal. We analyzed a dozen of existing CDR techniques, such as afforestation and reforestation, biochar from crop residues or slashed woods, and peatland restoration. All these existing CDR techniques manage carbon residence time more than carbon input. As carbon storage is jointly determined by carbon input and residence time, elongation of residence time or increase in carbon input or both all result in increased carbon sequestration (i.e., increased carbon dioxide removal from the atmosphere).  It appears that there are more rooms to manage carbon residence time than carbon input as carbon residence time can change from a few months or years to thousands of years. Thus, we can evaluate and design CDR techniques using methods that can substantially elongate carbon residence time. 

How to cite: Luo, Y.: Terrestrial carbon dioxide removal from the atmosphere: Ecological Principles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2943, https://doi.org/10.5194/egusphere-egu24-2943, 2024.

The carbon sequestration potential of forest ecosystems is influenced by various factors, including climate change and forest management. Climate change directly impacts the rate of forest growth and the accumulation of biomass. Effective forest management measures could enhance the structural integrity of forests, thereby improving the carbon sequestration capacity and adaptability to climate change of forest ecosystems. However, the impacts of these factors on future carbon sequestration and its potential of forests remain unclear. There is a pressing scientific need to focus on whether future climate change will increase carbon sequestration potential, and how forest management should be carried out in the future, as part of the current efforts to develop nature-based climate solutions. This study focuses on the forests of Northeast China, located in a mid-latitude zone sensitive to global climate changes, possessing abundant forest resources and serving as one of China's primary carbon reservoirs, where extensive forest management has been implemented over the past decades. We assessed the carbon sequestration potential of Northeast China's forests under future climate change and forest management strategies. Specifically, we utilized multi-source data (such as forest inventory and remote sensing data), coupled with ecosystem process-based model LINKAGES and forest landscape model LANDIS PRO, to predict the forest succession and carbon storage dynamics of Northeast China during the 21st century. The study conducted multi-scale validation of the simulation results through multi-source data, thereby enhancing the accuracy of the model simulations. Then, we estimated the future forest above-ground carbon sequestration potential and quantified the impacts of climate change and forest management. The results suggested: (1) The simulation of the current spatial distribution of above-ground carbon storage and age structure in Northeast China's forests aligns closely with remote sensing products and inventory data; (2) Considering only forest succession, the above-ground carbon sequestration is projected to peak in 2060, with the rate of carbon sequestration reaching its apex in 2025-2030 at 0.08Pg C·a-1; (3) Climate change is likely to enhance the carbon sequestration potential and rate of Northeast China's forests, but to a limited extent, with an increase of 7.3% and 13.6% under the SSP245 and SSP585 scenarios, respectively; (4) It remains essential to continue forest management practices in the future to address the challenges posed by climate change.

How to cite: Liang, Y.: The effects of climate change and forest management on forest carbon sequestration potential, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3276, https://doi.org/10.5194/egusphere-egu24-3276, 2024.

EGU24-3350 | Orals | BG8.16

Responses of soil organic carbon to wetland restoration—A global meta-analysis 

Yanan Wu, Ruiyang Zhang, and Shuli Niu

Wetlands are an important part of the terrestrial carbon pool in the global carbon cycle, and exploring the impact of wetland restoration on soil organic carbon (SOC) is of great significance for implementing effective wetland restoration measures to mitigate global warming. We conducted a global meta-analysis to analyze the response of SOC content to different wetland restoration approaches by comparing restored wetlands with degraded and natural wetlands, respectively. We also aimed to identify their temporal evolution, driving factors and potential mechanisms of wetland restoration. The results of this study showed that natural restoration methods, such as farmland abandonment and grazing prohibition, were effective in increasing wetland SOC. Specifically, the SOC contents of wetlands restored using these methods were significantly higher than those of degraded wetlands. Wetland restoration initially caused SOC to show a rapid growth trend, peaking in years 10-20, before levelling off over a longer period of time. After 40 years of restoration, wetland SOC levels were able to approach those of natural wetlands. Important factors driving wetland SOC restoration include total nitrogen, mean annual temperature, and mean annual precipitation. This study would provide insights for mitigating climate change through wetland SOC restoration.

How to cite: Wu, Y., Zhang, R., and Niu, S.: Responses of soil organic carbon to wetland restoration—A global meta-analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3350, https://doi.org/10.5194/egusphere-egu24-3350, 2024.

Separating soil organic carbon (SOC) into particulate (POC) and mineral-associated organic carbon (MAOC) fractions has provided fundamental knowledge on the structure and protection of SOC. However, the global distribution and key drivers of POC and MAOC remain elusive. Here, we compiled a global database of POC and MAOC with 2744 observations across six continents. Initial analysis showed that the mean POC was 2.73 kg m-2 and MAOC was 3.85 kg m-2 at 0-30 cm. At the global scale, POC and MAOC accounted for 39.98 % and 63.48 % of SOC, respectively. The global distribution of POC and MAOC was driven collectively by vegetation, climatic, and soil attributes. The lowest POC and MAOC stock were observed in cropland, suggesting the possibility of increasing C sequestration in soils by using management practices that increase POC and MAOC in croplands. Despite this great potential, we predicted the largest reduction in MAOC in cropland under future climate change, highlighting the high vulnerability of SOC stock in cropland. Understanding the role of environmental controls in the global distribution of POC and MAOC could help designing terrestrial carbon sequestration strategies.

How to cite: Chen, J., Cotrufo, M. F., and Sun, S.: Global soil carbon storage and stability informed by the particulate and mineral-associated organic carbon fractions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7373, https://doi.org/10.5194/egusphere-egu24-7373, 2024.

EGU24-7904 | Posters on site | BG8.16

Limited future carbon sink in China as forests become mature 

Wei Li and Yi Leng

China has experienced large land-use and land-cover changes (LULCC) over recent decades, resulting in a complex, mostly young, forest age structure. However, the impact of forest age dynamics on China’s terrestrial ecosystem carbon sink remains unclear. Here, using a process-based ecosystem model with an explicit representation of forest age cohorts, forced by satellite- and inventory-based maps of LULCC, we estimate China’s terrestrial carbon sink as 198 ± 54 Tg C yr-1 in the 2010s. The forest carbon sink represents 124 ± 25 Tg C yr-1, being predominantly (71.7%) contributed by middle-aged (16~50 year-old) forests. Following the national re/afforestation target of reaching 30% forest coverage by 2060 and assuming constant wood harvest rates in the future equal to present-day levels, the forest carbon sink is projected to be 181~217 Tg C yr-1 during 2041-2060 but to decrease to 142~212 Tg C yr-1 during 2081-2100 under Representative Concentration Pathway (RCP) 2.6, 4.5, 6.0 and 8.5. The carbon sink in established forests that were planted or existed before 2020 is the largest contributor to the future total carbon sink, but this contribution will decrease significantly (p<0.05) each year by -1.1 ~ -0.35 Tg C yr-1 until 2100 due to forest aging and the slowdown of CO2 concentration growth. New re/afforestation after 2020 will enhance the carbon sink in China by increasing forest area and rejuvenating forest demography. Our study emphasizes the importance of forest age dynamics on the carbon sink and implies that realizing China’s carbon neutrality target should not rely excessively on the ecosystem carbon sink.

How to cite: Li, W. and Leng, Y.: Limited future carbon sink in China as forests become mature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7904, https://doi.org/10.5194/egusphere-egu24-7904, 2024.

To help achieve carbon neutrality and mitigate climate change, vegetation restoration and wildlife conservation have recently been promoted as two key natural climate solutions. Although ecological studies have widely reported the profound top-down impacts of wildlife on the structure and function of vegetation, vegetation restoration and wildlife conservation are often viewed and implemented as two independent natural climate solutions. Combining field experiments in degraded coastal wetlands and meta-analyses of experimental studies from vegetated ecosystems globally, we explore the impacts of wildlife on vegetation restoration and related carbon cycling processes. In the field experiments, we find that vegetation restoration through planting alone failed to lead to vegetation recovery due to grazing by herbivores and did not increase plant and soil carbon stocks. In contrast, co-restoring threatened predators or simulating their consumptive or nonconsumptive effects facilitated the establishment of planted seedlings, led to successful recovery of vegetation, and increased plant and soil carbon stocks. These effects of herbivores and predators on vegetation restoration were generally supported in our global syntheses of experimental studies from all vegetated ecosystems, although these effects were context-dependent and often varied with biotic and climatic factors such as herbivore density, temperature, and precipitation. Taken together, these results suggest that vegetation restoration, if synergized with wildlife conservation, can be more promising for enhancing carbon sequestration in many ecosystems. We conclude by outlining possible ways to achieve synergies of vegetation restoration and wildlife conservation and by highlighting their policy implications.

How to cite: He, Q.: Synergizing vegetation restoration and wildlife conservation to enhance natural climate solutions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8586, https://doi.org/10.5194/egusphere-egu24-8586, 2024.

EGU24-12484 | ECS | Orals | BG8.16

Identifying success factors for the recovery of Andean tropical forests using observational and experimental plots 

Franklin Marín, Marijn Bauters, Selene Báez, Ximena Palomeque, Michael Perring, Susana León-Yánez, and Hans Verbeeck

The Andean tropical forests (ATF) are a well-known biodiversity hotspot, and they provide numerous ecosystem services such as carbon storage and water regulation. However, human activities including establishing pastures, cultivating crops, and fires, have significantly reduced the area covered by tropical forests and altered their structure, composition, and function. To counter forest degradation, various active restoration programs have been conducted. However, there is limited understanding regarding what factors influence the success of Andean forest recovery. Using a network of observational and experimental plots, that allow an understanding of recovery pathways across time and over environmental conditions, we address the question: what are the driving factors influencing establishment success in reforestation efforts? We established 118 observational plots along different environmental conditions (e.g. climate and soil types), and 96 experimental plots across an elevation gradient in Ecuador. The observational plots were established in 18 different young reforested sites (5 -10 years) to assess carbon productivity. On the other hand, the experimental plots were installed at three elevations (2200, 2800, and 3200 m a.s.l.) to evaluate the effects of pasture competition and artificial shading, in a factorial design, on survival and growth rate of five native tree species. Our findings from the observational plots revealed that grazing exclusion, precipitation, planted species richness, and soil properties significantly influence carbon productivity in reforested sites. Preliminary results from the experimental plots revealed that the effect of grass competition and shade on seedling performance varied tremendously according to species and elevation. In summary, our results suggest that land management practices, planted species richness and species type, and climate conditions are determining factors in regard to successful forest recovery.

How to cite: Marín, F., Bauters, M., Báez, S., Palomeque, X., Perring, M., León-Yánez, S., and Verbeeck, H.: Identifying success factors for the recovery of Andean tropical forests using observational and experimental plots, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12484, https://doi.org/10.5194/egusphere-egu24-12484, 2024.

Forest ecosystems are large carbon sinks, that absorb around 50% of the carbon in terrestrial ecosystems. Forests are being destroyed by a variety of factors, including climate change, human activities, and natural disturbances. Especially, forest fires cause catastrophic damage to forest ecosystems. This destruction of forest ecosystems negatively affects carbon uptake and creates uncertainty in achieving carbon neutrality.
In Korea, nature-based solutions are being applied in forest restoration projects in areas damaged by forest fires. As forest restoration projects cause further ecosystem instability, it is uncertain how much they will change carbon uptake in achieving carbon neutrality.
We analyze the stability period of forest ecosystem recovery using the BFAST algorithm for forest damage recovery areas in Korea, and estimate the change in carbon uptake using the CASA model. Based on this, we will examine the effectiveness of nature-based solutions and discuss the stabilization period that can be recognized as carbon credits and the possibility of carbon neutrality.

How to cite: Kim, S. and Park, C.: Impact of forest ecosystem restoration project on achieving carbon neutrality :  A case study of Post-Wildfire Restoration areas, South Korea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16178, https://doi.org/10.5194/egusphere-egu24-16178, 2024.

Increasing water stress on forests is emerging as a global phenomenon, resulting in the episodes of tree mortality, canopy die-offs and declines in ecosystem resilience, threatening the progress of global carbon neutrality. The role of tree functional strategies is pivotal in regulating forest ability to cope with water stress. To date, the species-level water stress strategies including closing leaf stomatal early, investing in stronger water transport structures, dropping leaves, storing water and developing deeper roots are well documented. However, how strategies found at the tree or species level scale up to characterise forest communities and their variation across regions is not yet well-documented. By combining eight water stress-related functional traits with forest inventory data from the USA and Europe (219,518 plots), we investigated the community-level trait coordination and the biogeographic patterns of water stress strategies for woody plants, and analysed the relationships between the strategies and climate factors. We found that the range of water stress strategies which dominated at community-level were consistent with those available at species-level. Traits associated with acquisitive-conservative strategies formed one dimension of variation, while leaf turgor loss point, associated with stomatal water strategy, loaded along a second. Surprisingly, spatial patterns of local water stress strategies were better explained by temperature than by aridity, suggesting a greater selective pressure on water demand over supply. These findings provide a basis on which to build predictions of forest response under water stress which are grounded in the dominant functional strategy, with particular potential to improve understanding of forest carbon sink potential in a changing climate.

How to cite: Liu, D.: Integrating functional strategies to optimize temporal forest carbon sink potential, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16305, https://doi.org/10.5194/egusphere-egu24-16305, 2024.

EGU24-686 | ECS | Orals | SSS7.3

Can increased cover crop diversity bind more soil in the field and mitigate overland flow erosion? 

Cristina McBride-Serrano, Ian C. Dodd, Timothy S. George, Alison J. Karley, and John N. Quinton

Agricultural intensification has simplified landscapes thereby reducing biodiversity, depleting natural resources, and threatening ecosystem services. Resilience to abiotic stress is therefore decreasing, creating uncertainty about effects of climate change on agricultural production and environmental degradation. While much research has focused on the direct benefits of increased plant diversity for crop productivity, there is limited evidence on how diversity and species selection affect soil stabilisation. How cover crops bind soil (rhizosheath development) has attracted little attention even though they can decrease soil erodibility.

A field trial investigated the impact of cover crop diversity on rhizosheath development and soil erodibility by conducting overland flow simulations. Species (Secale cereale, Brassica juncea, Vicia faba) were chosen for their suitability to UK environmental conditions. Results established that root biomass increased with cover crop diversity and was determined by the presence of Vicia faba. Rhizosheath formation was not affected by crop diversity and was greater in treatments containing Secale cereale. Overland flow simulations showed neither rhizosheath mass nor species diversity had an impact on soil erodibility, and the field variability of soil structural and hydraulic properties had a greater influence.

By providing evidence for increased plant diversity effects on agroecosystem function, this work will inform land managers about cropping practices to conserve soil function and aid in delivering environmental policy targets.

 

How to cite: McBride-Serrano, C., Dodd, I. C., George, T. S., Karley, A. J., and Quinton, J. N.: Can increased cover crop diversity bind more soil in the field and mitigate overland flow erosion?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-686, https://doi.org/10.5194/egusphere-egu24-686, 2024.

EGU24-2242 | ECS | Orals | SSS7.3

Effects of Different Drip Irrigation Belt Layout Modes on Soil Allelochemicals and Microorganisms in Apple - Soybean Intercropping System  

Xin Wang, Ruoshui Wang, Li Chen, Houshuai Dai, Chang Xiong, Meng Zhang, and Lisha Wang

This study aimed to investigate the impact of different layouts of drip irrigation belts on the distribution of soil phenolic acids, enzyme activities, and microorganisms in a fruit-crop intercropping system. Specifically, we focused on the apple-soybean intercropping system in the loess region of western Shanxi. Three types of drip irrigation belt spacing (L1, L2, and L3) were employed in the study: L1 involved the arrangement of a drip irrigation belt for each row of soybean, L2 had a drip irrigation belt at intervals of one row of soybean, and L3 had a drip irrigation belt for the third row of soybean from the fruit tree.We analyzed the spatial distribution changes of soil phenolic substances, enzyme activity, and microbial quantity under different water distributions. Principal component analysis was then applied to establish the relationship between soil factors and drip irrigation treatments.The results indicated that, apart from benzoic acid and phloroglucinol, the spacing of the drip irrigation belt significantly influenced the distribution of phenolic acids in the soil. Likewise, except for catalase, the spacing of the drip irrigation belt had a significant impact on the distribution of enzyme activity and microbial quantity. The effects of different drip irrigation belt layout modes on the distribution of soil phenolic acids, bacteria, and fungi were consistent with those observed in the intercropping control treatment, where the distribution increased as the distance from the tree increased. Enzymatic activity decreased initially and then increased with increasing distance from the tree under drip irrigation.Principal component analysis revealed that different drip irrigation belt spacings altered the content of soil allelochemicals, microbial quantity, and enzymatic activity. Additionally, the total amount of phenolic acids in intercropping soil was found to be lower than that in monocropping. Treatment L1 exhibited the highest soil enzyme activity and total microbial biomass, while treatment L2 had the lowest accumulation of phenolic acids in the soil. Notably, treatment L2 demonstrated relatively high soil enzyme activity, despite the lowest accumulation of phenolic acids. Based on our findings, we recommend adopting the arrangement of a drip irrigation belt at intervals of one row of soybean in fruit-crop intercropping systems. This layout not only improves the soil micro-ecological environment but also alleviates the inhibition of allelochemicals.

How to cite: Wang, X., Wang, R., Chen, L., Dai, H., Xiong, C., Zhang, M., and Wang, L.: Effects of Different Drip Irrigation Belt Layout Modes on Soil Allelochemicals and Microorganisms in Apple - Soybean Intercropping System , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2242, https://doi.org/10.5194/egusphere-egu24-2242, 2024.

EGU24-2284 | ECS | Orals | SSS7.3

Simulation of soil water transport in apple-soybean intercropping system under drip irrigation and film mulching 

Lisha Wang, Ruoshui Wang, Houshuai Dai, Chang Xiong, Meng Zhang, Li Chen, and Xin Wang

Intercropping and mulched drip irrigation are widely used techniques for achieving high yields and water savings. Understanding the soil moisture distribution characteristics of intercropping farmland under mulched drip irrigation is crucial for improving water use efficiency, increasing yields, and boosting income. This study aimed to investigate soil moisture under different irrigation amounts and film mulching times through a two-year field experiment.In the experiment, two upper limits of irrigation amount (50% and 80% of field water holding capacity) and two film mulching times (soybean sowing to pod setting stage and film mulching throughout the growth period) were set. The HYDRUS2D model was used to simulate the difference in soil moisture at various positions and the two-dimensional distribution characteristics of soil moisture in intercropping drip irrigation farmland. The results showed that the soil moisture model based on HYDRUS2D had high precision, with a coefficient of determination ranging from 0.60 to 0.93 and a root mean square error ranging from 0.006 to 0.038 cm3/cm3. In the horizontal direction, the soil moisture content at 2.3 m from the tree row increased by an average of 4.87% to 17.65% compared to other distances. In the vertical direction, the maximum soil moisture content was observed in the 40 cm soil layer, with an increase of 26.04% to 42% compared to the 10 cm soil layer. The 2-D soil moisture distribution showed that the moisture saturation zone of drip irrigation was mainly concentrated in the 0-20 cm soil layer. These findings can serve as a reference for developing irrigation schedules for intercropping farmland under drip irrigation.

How to cite: Wang, L., Wang, R., Dai, H., Xiong, C., Zhang, M., Chen, L., and Wang, X.: Simulation of soil water transport in apple-soybean intercropping system under drip irrigation and film mulching, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2284, https://doi.org/10.5194/egusphere-egu24-2284, 2024.

EGU24-2434 | ECS | Posters virtual | SSS7.3

Effects of Different Micro-Irrigation Methods on Water Use and the Economic Benefits of an Apple–Soybean Intercropping System 

Houshuai Dai, Ruoshui Wang, Li Chen, Lisha Wang, Xin Wang, Chang Xiong, and Meng Zhang
Intercropping systems reduce ineffective evaporation between trees but also intensify interspecific competition and reduce productivity. To improve the water-use efficiency and the economic benefits of an intercropping system on the Loess Plateau, China, where rainfall is limited and evaporation intense, an apple–soybean intercropping system with micro-irrigation water control was adopted to analyze the soil water, root density, water-use efficiency, yield, and economic benefits of intercropping under different micro-irrigation methods. Subsurface seepage irrigation, bubbler irrigation, and drip irrigation under mulching were used with irrigation upper limit levels of three maximum irrigation levels [60% (W1), 75% (W2), and 90% (W3) of field capacity (FC)]. Rainwater harvesting from ridges and furrows (GL) without irrigation was the control. Bubbler irrigation increased the soil water content, optimized the vertical soil water distribution, and promoted root growth. Except for the control treatment (GL), the other micro-irrigation treatments increased with the irrigation amount, but the water-use efficiency decreased. Drip irrigation under mulch combined with W2 (75%Fc) irrigation could obtain the maximum intercropping yield, which was increased by 71.1% compared with the GL treatment. Drip irrigation under a mulch combined with W2 produced the maximum intercropping yield; the economic benefits were higher under drip irrigation with mulching combined with W1; and all three micro-irrigation methods combined with W2 improved the economic benefits by 52.1–115.5% compared to GL. Drip irrigation under mulching or bubbler irrigation combined with W2 should be used when there are sufficient water resources, but drip irrigation under a mulch combined with W1 when there is a water shortage.

How to cite: Dai, H., Wang, R., Chen, L., Wang, L., Wang, X., Xiong, C., and Zhang, M.: Effects of Different Micro-Irrigation Methods on Water Use and the Economic Benefits of an Apple–Soybean Intercropping System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2434, https://doi.org/10.5194/egusphere-egu24-2434, 2024.

EGU24-2503 | ECS | Posters virtual | SSS7.3

Soil Moisture, Nutrients, Root Distribution, and Crop Combination Benefits at Different Water and Fertilizer Levels during the Crop Replacement Period in an Apple Intercropping System 

Chang Xiong, Ruoshui Wang, Xin Wang, Lisha Wang, Li Chen, Houshuai Dai, and Meng Zhang

Uneven soil moisture and nutrient distribution before and after intercropping limits apple cropping system productivity in the western Shanxi loess area. To address the problem, a field experiment was conducted between 2020 and 2021 to investigate the effects of different water and fertilizer management practices on soil moisture, nutrients, root distribution, and overall benefits of the intercropping system during the crop replacement period. The experimental set up included three factors: irrigation method, irrigation level, and fertilizer application; irrigation methods included drip (D) and flood (M) irrigation; irrigation levels included rain-fed without irrigation (W0), 50% of the field water holding capacity (Fc)-W1, and 80% of the field water holding capacity (Fc)-W2; fertilizer treatments included F0 (no additional fertilizer application), F1 (N 206.2 kg∙hm-2 + P2O5 84.4 kg∙hm-2 + K2O 84.4 kg∙hm-2), F2 (N 412.4 kg∙hm-2 + P2O5 168.8 kg∙hm-2 + K2O 168.8 kg∙hm-2), and control (CK) without irrigation and fertilization, for a total of 15 treatments. According to the results, soil water content (SWC) decreased after the crop replacement. Besides, nitrate nitrogen (NN), ammonium nitrogen (AN), and organic matter (OM) contents in all treatments increased, whereas total phosphorus (TP) content decreased. The main soil aggregate layer with crop roots shifted downwards (from the 0–40 cm soil layer before crop replacement to the 0–60 cm soil layer) after crop replacement, and partial fertilizer productivity (PFP), irrigation water use efficiency (IWUE), and water use efficiency (WUE) under both irrigation treatments were decreased. Principal component analysis showed that the W2F2 treatment had the highest combined benefits both irrigation treatments during the crop replacement period. Structural equation modeling showed that apple tree and maize RLDs had no significant effects on water use (ET) and WUE before crop replacement. Apple tree and soybean RLDs had significant positive correlations with ET and significant negative correlations with WUE after crop replacement. According to our results, to optimize the benefits of apple-crop intercropping, drip irrigation with complete water supply and flood irrigation with incomplete water supply are recommended during crop replacement. In addition, an upper irrigation limit of 80% of the field water holding capacity and a fertilizer application rate of N 412.4 kg∙hm-2 + P2O5 168.8 kg∙hm-2 + K2O 168.8 kg∙hm-2 are recommended for optimal water and fertilizer regulation.

How to cite: Xiong, C., Wang, R., Wang, X., Wang, L., Chen, L., Dai, H., and Zhang, M.: Soil Moisture, Nutrients, Root Distribution, and Crop Combination Benefits at Different Water and Fertilizer Levels during the Crop Replacement Period in an Apple Intercropping System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2503, https://doi.org/10.5194/egusphere-egu24-2503, 2024.

EGU24-2795 | ECS | Posters on site | SSS7.3

Effects of biochar and its co-application with inorganic and organic fertilizers on soil microbial respiration and temperature sensitivity of carbon mineralization. 

María José Carpio Espinosa, Clément Bonnefoy-Claudet, Mathieu Thévenot, Olivier Mathieu, Iria Benavente-Ferraces, Juan Carlos García-Gil, César Plaza, and Marco Panettieri

Biochar application to agricultural soils represents a strategy for carbon sequestration and soil quality enhancement. However, long-term field studies on the interactive effects of combined application of biochar and inorganic or organic fertilizers on temperature sensitivity of soil respiration (Q10) are still scarce. To address this gap, a long-term field experiment with a randomized block design was established in a semiarid agricultural soil in Central Spain in 2012. The treatments used for this study included unamended control, amendment with biochar (B) at a rate of 20 t ha-1 year-1, mineral fertilizer (MF), municipal compost (MC) and sewage sludge (SS) at rates to meet N crop demands and the co-amended B+MF, B+MC and B+SS applied at the same application rates used for the individual treatments. Soil samples were taken post-harvest of 2023, eight months after the latest soil amendments. A series of soil incubations were set to a range of 5-35 °C for CO2 measurements, which were addressed using the fully automated system Respicond respirometer X. Overall, Q10 values were not affected by the co-application of biochar and fertilizers. Only soils amended with MC showed a significant increase in the Q10 value in comparison to the B, MF and unamended control treatments. Furthermore, MC-amended soils showed higher respiration rates than those amended with SS. This difference could be attributed to the rapid mineralization of labile carbon fractions added with SS in preceding months or to the presence of preserved complex substrates in MC treatments that could decompose over the long-term. It could also be linked to a higher accumulation of SOC over the past 12 years in MC-treated soils compared to those treated with SS, thereby influencing the observed variations in respiration rates. On the other hand, co-application of biochar with fertilizers decreased soil CO2 fluxes, especially for B+MC and B+SS, in comparison to the treatments applied alone. The study suggests that in semiarid soils the combined application of biochar with other fertilizers may induce beneficial synergistic effects, creating a nutrient-rich soil environment while either limiting soil CO2 fluxes and mitigating the adverse impact on the temperature sensitivity of carbon mineralization. 

Acknowledgments: This research was supported by the Ministry of Science and Innovation (“BIOGEOCHAR” Project grant ref. TED2021-132342B-I00). M.J.C thanks to the Embassy of France in Spain for supporting her postdoctoral stay in the Biogéosciences Unit and MINECO for her “Juan de la Cierva-Formación” postdoctoral contract.

How to cite: Carpio Espinosa, M. J., Bonnefoy-Claudet, C., Thévenot, M., Mathieu, O., Benavente-Ferraces, I., García-Gil, J. C., Plaza, C., and Panettieri, M.: Effects of biochar and its co-application with inorganic and organic fertilizers on soil microbial respiration and temperature sensitivity of carbon mineralization., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2795, https://doi.org/10.5194/egusphere-egu24-2795, 2024.

EGU24-2929 | Posters on site | SSS7.3

A field guide for evaluation of erosion risk in olive orchards under contrasting environmental and management conditions. 

Jose Alfonso Gomez, Ignacio Domenech, Maria Auxiliadora Soriano, and Maria Gema Guzman

Olive is one of the dominant crops in the Mediterranean basin, although is also an expanding crop in other areas of the World with similar climate type (Camposeo and Gómez, 2023). Olive trees are cultivated in arid and semi-arid areas, and this has resulted in a management strategy oriented towards limited vegetative ground cover to improve water availability for the crop. This fact, combined with cultivation in sloping areas and periodic high-intensity rainfall events, has led to high erosion rates in many olive-growing areas (Milgroom et al., 2007; Camposeo and Gómez, 2023).  
Implementation of appropriate soil management and strategies for erosion control relies on an adequate appraisal of the erosion intensity, processes and the relationship between soil management and environmental (soil, climate…) conditions by stakeholders. Evaluation of water erosion risk at the farm level is usually a complex process based on modelling approaches and it is not appealing to end-users who need simpler and easier-to-understand tools. There are successful examples of tools for appraisal erosion risk at farm level in olives trees, like the one of Milgroom et al. (2006, 2007). However, the implementation of these tools is limited to some management practices and region in which they were developed (e.g. organic olive orchards in southern Spain, Milgroom et al., 2006). 
Within the context of the TUdi project, there is on-going research to develop generalized versions for appraising erosion risk in woody crops in contrasting environments and management strategies (Gómez et al., 2023). This communication will show the complete version of a field tool for appraising water erosion risk in olive groves, valid for all olive-growing areas, developed in cooperation with projects SCALE, TUdi, ECOMED and BIOLIVAR. It is based on a dual approach combining erosion risk estimation from basic farm and management features, based on simplified RUSLE factors (Renard et al., 1997) combined with erosion symptoms. In this communication, the theoretical basis of the tool and its calibration, and the interpretation of the results based on several examples across the contrasting areas will be presented. 
With this approach, this tool aims to achieve these objectives:
1- To provide a standardized tool valid across multiple environments and cropping conditions to evaluate water erosion risk in olive cultivation.
2- To develop an educational tool to provide training on prevention water erosion in olive orchards.

Acknowledgements: This work is supported by the projects SCALE (EJP Soil Horizon 2020 GA 862695), ECOMED (PR.AVA23.INV202301.035), GOPO-SE-20-0002 (EIP-Agri), TUdi (Horizon 2020, GA 101000224) and PID2019-105793RB-I00 (Spanish Ministry of Science and Innovation). 
References:
Camposeo, S. and Gómez, J.A. 2023. Soil Management, In: The Olive, Botany and Production, pp 325-349, CABI International
Gómez J.A. et al., 2023. A standardized, hybrid, field guide for appraising water erosion risk by practitioners in multiple woody crops and environments. EGU23-1398, https://doi.org/10.5194/egusphere-egu23-1398 
Milgroom et al., 2006. Erosión en olivar ecológico. Manual de campo: diagnóstico y recomendaciones, http://hdl.handle.net/10261/66497
Milgroom et al., 2007. Land Degradation & Development, 18: 397-411.
Renard et al., 1997. Agricultural Handbook 703, USDA-ARS. Washington, DC.

How to cite: Gomez, J. A., Domenech, I., Soriano, M. A., and Guzman, M. G.: A field guide for evaluation of erosion risk in olive orchards under contrasting environmental and management conditions., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2929, https://doi.org/10.5194/egusphere-egu24-2929, 2024.

EGU24-3052 | ECS | Posters on site | SSS7.3

Vegetative barriers as a nature-based solution for agricultural landscapes diversification: design and management of this green infrastructure in a Mediterranean climate. 

Javier Montoliu, Gema Guzmán, Ángel Lora, José Mora, Maria Auxiliadora Soriano, and José Alfonso Gómez

Agricultural intensification has used technological advances to raise food production, but it has also created environmental imbalances. Environmental degradation, e.g. soil loss and offsite contamination, and loss of biodiversity, related to the expansion and intensification of agriculture, have been documented internationally[1][2]. Since the 1980s, with the Single European Act[3] as a legal basis, different attempts have been made to address this threat at European level through better focused environmental policies. For instance since the CAP reform in 1992, environmental sustainability of agriculture has been constantly ongoing. In fact, the latest reform post-2021 shows more ambitious objectives with the introduction of eco-regimes. Other key initiatives like the Green Infrastructure Strategies and the EU Mission: A Soil Deal for Europe have emerged[4][5][6] being focused on recovering natural capital as a source of ecosystem services.

In this context, ALIve[7], SCALE[8] and ECOMED[9] projects and the Rural Landscape Diversification Program of the Córdoba Countryside[10] aim to provide scientific and technical knowledge for the sustainable intensification of agriculture in Mediterranean areas, in particular southern Spain, through nature-based solutions.

Although vegetative barriers are one of the key instruments to manage agricultural landscapes towards sustainable intensification, detailed empirical information on how to implement them still scarce. This communication presents an experiment on different alternatives on how to stablish a vegetative barrier combining fifty-two herbaceous and woody species adapted for Mediterranean conditions. This experiment explores seventeen different strategies, combining different irrigation, mulching and tillage combinations. In these plots, growth, survival and phytosanitary status of the plants, and soil moisture at the end of each hydrological year were monitored since its implantation in February 2021. This communication presents results from the first year of implementation, as well as a costs analysis of the different strategies evaluated. This information can be valuable for practitioners and planners interested in these nature-based solutions.

After the first year, it was observed that all the treatments presented a remarkable survival rate, above 48% (CoT4), albeit this increases with better management reaching 100% with better tillage, mulching and drip irrigation. Plant growth also responded to best management ranging from 14.1 cm in height (CoT4) and 11.8 cm in diameter (CoT3) to 46.7 cm in height (CoT9) and 58.8 cm in diameter (CoT9). The cost of implementation ranged from 1.7 €/m2 (CoT4) to 6.0 €/m2 (CoT9). Among the most successful individual operations is mulching with a fabric film, which despite having the highest implementation cost 2.5 €/m2 results in the lowest maintenance cost 0.4 €/m2.

Acknowledgements: ALIve (PID2019-105793RB-I00), SCALE (Nº 862695) and ECOMED (PR.AVA23.INV202301.035).

References:

[1] MITECO, «Plan estratégico estatal del patrimonio natural y de la biodiversidad a 2030». 2022.
[2] European Commission, «EU Biodiversity Strategy for 2030». 2020.
[3] European Economic Community, «Single European Act». 1987.
[4] European Commission, «Green Infrastructure (GI) — Enhancing Europe’s Natural Capital». 2013.
[5] MITECO, «Estrategia Nacional de Infraestructura Verde y de la Conectividad y Restauración Ecológicas». 2021.
[6] European Commission, «EU Mission: A Soil Deal for Europe». 2023.
[7] https://alive.csic.es/
[8] https://ejpsoil.eu/soil-research/scale/
[9] https://www.juntadeandalucia.es/agriculturaypesca/ifapa/web/node/60947
[10] https://www.jardinbotanicodecordoba.com/investigacion/diversificacion-del-paisaje-agrario/

How to cite: Montoliu, J., Guzmán, G., Lora, Á., Mora, J., Soriano, M. A., and Gómez, J. A.: Vegetative barriers as a nature-based solution for agricultural landscapes diversification: design and management of this green infrastructure in a Mediterranean climate., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3052, https://doi.org/10.5194/egusphere-egu24-3052, 2024.

Windbreak plays an important role in soil conservation in arid and semiarid areas. Owing to its protective effects on soil, windbreak could potentially serve as a reference of no erosion to identify the soil erosion rates in the nearby croplands. To testify the applicability, a case study was implemented in a wind and water eroded agro-pastoral transition zone in North China. A Real Time Kinematic Global Positioning System (RTK GPS) was applied for a series of croplands to quantify the total soil erosion induced by both wind and water over a period of 44 years. By comparing the elevation of the eroded croplands and the windbreaks without erosion, the total soil erosion modulus and its spatial variation were determined. Results showed that the erosion moduli of the six croplands ranged from 1.09 to 45.34 Mg ha−1 y−1 with an average modulus of 17.02 Mg ha−1 y−1. The croplands in the west suffered from more intense wind erosion compared to the middle and eastern areas, which was a result of the effects of the windbreaks. The reliability and uncertainty of this approach were discussed in terms of the equipment precision, results accuracy, and possible deposition in the windbreaks. This study confirms that windbreak can be a feasible reference for quantifying soil erosion. Furthermore, such quantification is a direct measurement of total soil erosion, which is essential for assessing the contributions of wind erosion and water erosion as well as the interaction between them.

How to cite: Zhang, Z., Luo, J., and Chen, B.: Effects of windbreak on soil conservation: Serving as a potential reference for quantifying soil erosion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3685, https://doi.org/10.5194/egusphere-egu24-3685, 2024.

EGU24-3716 | ECS | Posters virtual | SSS7.3

Vegetation phenology and its response to climate change in the Yellow RiverBasin from 2001 to 2020 

wang yichen, he jie, he liang, zhang yujie, and zhang xiaoping

     Vegetation phenology is widely recognized as a comprehensive indicator of global climate change. Studying the spatiotemporal characteristics and trends of regional vegetation phenology can improve our understanding of the stability and dynamic changes of the ecosystem. Based on the 16day, 250m resolution MODIS NDVI data from 2001 to 2020, this study used the S-G filtering method and the relative threshold method to extract vegetation phenology parameters in the Yellow River Basin. Combined with the ERA5-LAND hourly climate reanalysis dataset and CHIRPS daily precipitation dataset provided by GEE platform, using trend analysis and partial correlation analysis methods, we explored the spatial distribution characteristics and change trends of vegetation phenology in different vegetation zones under global climate change.We also analyzed its response to climate factors.The results show that: (1) the climate in the Yellow River Basin presented a warm and humid development trend from 2001 to 2020, with an annually average temperature increase of 0.15℃/10a (P>0.05) and an annual precipitation increase of 24mm/10a (P<0.05). (2) The warm temperate deciduous broad-leaved forest region in the Yellow River Basin had the earliest start of the growing season and middle time of the season, while the typical grassland subzone in the southern temperate zone and the desert grassland subzone in the southern temperate zone had the latest start of the growing season and middle time of the season. The end of the growing season in the temperate shrub-grass semi-desert zone was the latest, and the length of growing season in the alpine vegetation region on the Qinghai-Tibet Plateau was the shortest. (3) Within the whole basin, 69.3% and 66.4% of the area showed an advance trend (P<0.05) for start of the growing season and middle time of the season, respectively, 50.9% of the area showed a delay trend (P<0.05) for end of the growing season, and 66.1% of the area showed an extension trend (P<0.05) for length of growing season. (4) There were differences in climate impacts on phenology parameters among different vegetation zones. Temperature had a greater impact on phenology parameters in typical grassland subzone in northern temperate zone, alpine grassland zone, and alpine meadow zone, while precipitation and solar radiation factors had a greater impact on phenology parameters in typical grassland subzone in southern temperate zone, temperate shrub-grass semi-desert zone, desert grassland subzone in southern temperate zone and mid-subtropical evergreen broad-leaved forest zone.

How to cite: yichen, W., jie, H., liang, H., yujie, Z., and xiaoping, Z.: Vegetation phenology and its response to climate change in the Yellow RiverBasin from 2001 to 2020, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3716, https://doi.org/10.5194/egusphere-egu24-3716, 2024.

Abstract: Mulching and supplementary irrigation are commonly used water-saving techniques ensuring agricultural sustainability in drylands of northwest China. However, the effects of the combination of mulching and supplementary irrigation on the soil environment, and the growth of apple trees remain unclear. Field experiments were conducted in 2023 to evaluate the effects of the combination of mulching and supplementary irrigation on the soil water and heat, and the growth of apple trees. In the experiments, one mulching method (corn straw mulching, SM), two types of drip irrigation, which included above-ground ring drip irrigation (M1) and above-ground two-row drip irrigation (M2), were used. Additionally, three irrigation levels of 100% (W1), 75% (W2), and 50% (W3) of full irrigation (referred to as full, moderate deficit, and severe deficit irrigation, respectively) were used. The results showed that SM significantly increased the soil water content (SWC), especially in the early stage of the growth period. SM significantly reduced and stabilized the soil temperature during the whole growth season, while M1 and M2 had no significant effect on the soil temperature. Both mulching and drip irrigation significantly increased the net photosynthetic rate (Pn) of leaves. Supplementary irrigation had no significant effect on shoot length, but increased shoot diameter. The evapotranspiration of various stages on apple trees was in the following descending order: fruit expansion stage (III), bud development and flowering stage (I), leaf expansion stage (II), and fruit maturing stage (IV). Therefore, SM has the potential to increase apple yields in the Loess Plateau by improving the soil environment and regulating the growth and physiology of apple trees.

How to cite: Yang, Y.: Integrating mulching and supplementary irrigation for soil environment improvements in apple orchards of northwest China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3768, https://doi.org/10.5194/egusphere-egu24-3768, 2024.

The transfer of particle-bound prokaryotes and substrates from slopes to rivers during soil erosion is a crucial dynamic process that greatly influences terrestrial biological and geochemical cycles. Particle size strongly affects the transport distance of suspended sediments and likely induces prokaryote and substrate variations along the course of the river. Previous studies have mainly focused on the spatial redistribution of soil prokaryotes, whereas the variation in prokaryotic diversity and community composition among different particle size-fractions in suspended sediments remain unclear. In this study, suspended sediments were collected at four plots (upstream, middle stream, downstream, and dam) along a river that runs through a valley. Sampled sediments were size-fractionated into > 63 μm and < 63 μm particles (referred to as small and large particle fractions hereafter), to identify the corresponding prokaryotic community composition, interactions, and functions. The richness index (Chao1 and observed species) and the diversity index (Shannon) of sediment-associated prokaryotic communities significantly decreased from upstream towards dam plots, except in the small particle fraction in downstream and dam plots. The highest β-diversity index value was found for the large particle fractions, while the geospatial contribution to β-diversity varied. The concentration of Proteobacteria in downstream (41.39%) and dam (34.86%) plots was lower than that in the upstream (47.65%) and middle stream (45.90%) plots. In contrast, Cyanobacteria (4.89% and 6.75%) and Verrucomicrobiota (5.98% and 11.00%) concentrations were greater in the downstream and dam plots, respectively, than those in the upstream (0.93% and 2.43%) and middle stream (3.37% and 3.11%) plots, respectively. Additionally, the concentrations of Verrucomicrobiota and Bacteroidota were significantly higher in the small particle fractions (2.26–8.12% and 4.33–7.72%) than those in the large particle fractions (2.03–5.94% and 3.70–7.11%). Compared to the other plots, upstream plots had a larger clustered network and a greater number of co-occurrences within the prokaryotic community in the bulk sediment and in the small particle fraction, whereas more complex interactions among prokaryotic communities were found in the large particle fraction from the dam plots. Soil organic carbon (SOC), total nitrogen (TN), and Olsen phosphorus were the three most influential factors, explaining 67.41% of the variation in prokaryotic community. Proteobacteria and Myxococcota correlated negatively with SOC, TN, and Olsen P but positively with C=O. Conversely, Cyanobacteria and Verrucomicrobiota correlated positively with SOC, TN, and Olsen P but negatively with C=O. Functional groups linked to the biogeochemical cycling of carbon (methanol oxidation and methylotrophy) were found in high concentrations, whereas those linked to nitrogen (nitrogen and nitrate respiration) were found in low concentrations in upstream and middle stream plots. Reassembly of the sediment physicochemical characteristics among geospatial plots along the transport transect significantly altered the prokaryotic community composition and metabolic functional groups.

How to cite: Li, T., Wang, R., and Guo, S.: Differentiation of prokaryotic community composition in suspended sediment size-fractionation in a small loess watershed, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3775, https://doi.org/10.5194/egusphere-egu24-3775, 2024.

Soil aggregates influence bacterial spatial distribution by providing varying substrate-laden micro-habitats. Understanding the nuances of bacterial variation within aggregates is essential for comprehending the involvement of soil microbes in biogeochemical processes. However, as a common practice for improving crop yields, it remains unclear how aggregates influence the redistribution of bacterial communities and functional composition across different fertilizer regimes. In this study, we used high-throughput sequencing of the 16S rRNA to examine the variation in soil bacterial communities across three different aggregate sizes (macroaggregate: >250 μm; mesoaggragate: 250-63 μm, and microaggregate: <63 μm) under three fertilizer regimes (CK, unfertilized soil; NP, nitrogen & phosphorus; NPM, nitrogen, phosphorus & manure) in calcareous soil in a 38-year experiment. The higher richness (Chao1) and diversity (Shannon) were found in microaggregate in the NP treatment, whereas the higher values were found in the macroaggregate after farmyard manure application (NPM) compared with meso and microaggregates. Bacterial community compositions had significantly difference among aggregate sizes from non-metric multidimensional scaling (NMDS). Further, we observed more complex co-occurrence networks (more links and a higher average degree) in the mesoaggregates compared with both micro and macroaggregates. The relative abundance of metabolic pathways related to C5-Branched dibasic acid metabolism, Biosynthesis of vancomycin group antibiotics and Fatty acid biosynthesis were higher in macroaggregates. However, the relative abundance of Biosynthesis of ansamycins was higher in mesoaggregates. Bacterial richness was positively correlated with biological index, but negatively with quantity and quality of soil carbon (dissolved organic carbon, fluorescence index and humification index). Our study highlights the distinct distribution characteristics of bacterial communities in different-sized aggregates with fertilization regimes. These findings contribute to a better understanding of the complex interactions between soil aggregates, bacterial communities, and agricultural practices.

How to cite: Zhang, W., Wang, R., and Guo, S.: Soil aggregates differently modulated bacterial community and function composition with fertilized regimes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3800, https://doi.org/10.5194/egusphere-egu24-3800, 2024.

Mulching is an important measure to conserve moisture and increase yield in dryland orchards of the Loess Plateau, and it is critical to realize high and stable yield and sustainable development of fruit crops. Based on field positioning obervation, the comprehensive effects of different mulching methods on soil water storage, fruit tree growth and physiological status, yield were investigated. Treatments were straw mulching (SM), horticultural fabric mulching (BF), black plastic film mulching (BM), white plastic film mulching (WM) and no mulching (CK). The results showed that: (1) Compared with CK, different mulching measures can significantly increase the average soil water storage in the 0-120 cm soil layer during the whole reproductive period, which can provide a basis for the realization of inter-temporal water regulation; (2) Different mulching methods can significantly increase the growth of apple branches and LAI, and enhance the tree strength; (3) SM, BF, and BM can significantly increase the net photosynthetic rate, and BM inhibited the occurrence of midday depression; (4) Under the BF treatment, the yield, the anthocyanin content, the soluble sugar content, sugar-acid ratio and fruit hardness were higher than CK. Using the comprehensive scoring method to obtain BF as the optimal mulching method, so BF was an appropriate technique to improve the hydrological status, fruit yield and quality of apple orchard soil in the Loess Plateau.

How to cite: Liu, W., Han, Y., Yang, Y., and Zeng, L.: Effects of different mulching methods on soil moisture, fruit tree growth and yield in apple root zone yield of apple, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4871, https://doi.org/10.5194/egusphere-egu24-4871, 2024.

EGU24-4934 | Posters on site | SSS7.3

Responses of leaf functional traits to soil environment at different sand fixation stages in the Mu Us desertland 

Yun Tian, Yuanmeng Dai, Mingze Xu, Yuhan Zhou, Xiaoqian Ju, Tianshan Zha, Xin Jia, and Peng Liu

Leaf functional traits (LFTs) can directly or indirectly reflect the adaptation strategy of plants to the environment, influencing their survival, growth, and reproduction. However, there is still uncertainty as to the relationship between LFTs and environmental gradients, especially in resource-limited regions. In this study, we selected Artemisia ordosica communities as the research objects at four different dune fixation stages, including semi-fixed (D1), fixed (D2), soil-crust fixed (D3) and herbaceous-plant-covered fixed sand dunes (D4) in Mu Us Desert. Based on field investigation and laboratory analysis, we examined the characteristics of 13 LFTs and the relationship between of LFTs trade-offs and soil physicochemical environment under different dune fixation stages. It was found that (1) in community level, leaf area (LA) and specific leaf area (SLA) were the largest at D1, while leaf tissue density (LTD) and leaf dry matter content (LDMC) shown gradually increasing trend with dune fixation. The results indicated that plants will adapt to progressively increasing competition by reducing their photosynthetic capacity and enhancing their physical defense structures. (2) with ongoing dune fixation, the soil organic carbon content (SOC) and soil total nitrogen content (STN) were significantly higher in D2-D4 than that in D1, and soil water content (SWC) was the highest in D2, then decreased significantly in D3-D4 with increasing community species. (3) according to the results of redundancy analysis (RDA), the two main axes represented the soil physical condition (54.11%) and chemical condition (30.06%), respectively. And the SWC and SOC were the main factors affecting changes in LFTs during the dune fixation. Our results provide theoretical basis for understanding the resource use strategy and adaptation mechanism of desert plants under stress environments.

How to cite: Tian, Y., Dai, Y., Xu, M., Zhou, Y., Ju, X., Zha, T., Jia, X., and Liu, P.: Responses of leaf functional traits to soil environment at different sand fixation stages in the Mu Us desertland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4934, https://doi.org/10.5194/egusphere-egu24-4934, 2024.

EGU24-5554 | ECS | Posters on site | SSS7.3

Unraveling the resilience of micro-dams on Austrian potato fields during intense rainfall  

Matthias Konzett, Peter Strauss, and Elmar Schmaltz

Potatoes are especially susceptible to erosion when grown on long and sloped fields due to late seed development and the unique structure of their seedbed. Previous research has shown that micro-dams can effectively reduce surface runoff and sediment yield while also increasing soil water content. One way to further improve micro-dams is to cover them with a greening crop, such as oat or wheat. During intense precipitation events, micro-dams may break and lose their protective effects, whereas micro-dams with cover crops are more sustainable and stay intact. Therefore, this study aims to analyze the resilience of both micro-dams and micro-dams with cover crops on selected fields and all Austrian potato fields in 2022 to intense rainfall events.

Between 2019 and 2022, seven potato fields with both micro-dams and covered micro-dams were surveyed using UAVs (Unmanned Aerial Vehicles) to collect elevation data. This data was used to create digital elevation models (DEM), which were then utilized to evaluate the state of each micro-dam on the field, i.e., whether it was intact, damaged, broken, or undefinable, as well as to calculate topographic parameters, such as slope and LS-Factor, for each micro-dam's position. After a specific precipitation event, the state of each micro-dam was compared with its respective slope and LS-Factor. The obtained data was subsequently applied to all Austrian potato fields of 2022 to assess the potential of micro-dams and micro-dams with cover crops to withstand intense precipitation events and their potential effectiveness.

The first results indicate that there is a distinct difference in slope and LS-Factor between stable and broken micro-dams, regardless of whether they are covered with a greening crop or not. The median slope of all broken micro-dams, whether covered or uncovered, is 8.4%, while stable micro-dams are situated at a median slope of 6%. A similar ratio can be observed in the LS-Factor, with a median of 1.75 for broken micro-dams and 1.15 for stable micro-dams. There are differences between uncovered and covered micro-dams regarding their slope or LS-Factor in all possible states for micro-dams, yet these differences are small and not significant. The application of the data to all potato fields in Austria in 2022 is still ongoing.

How to cite: Konzett, M., Strauss, P., and Schmaltz, E.: Unraveling the resilience of micro-dams on Austrian potato fields during intense rainfall , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5554, https://doi.org/10.5194/egusphere-egu24-5554, 2024.

EGU24-6323 | ECS | Orals | SSS7.3

Does nitrogen management in winter wheat affect its yield and nitrate-N leaching in a wheat-soybean double cropping system? 

Oluwaseun Ola, Osman Guzel, Karla Gage, Karl Williard, Jon Schoonover, Steffen Mueller, and Amir Sadeghpour

Conventional corn (Zea mays L.)-soybean (Glycine max L.) rotation contributes to nitrate-N and phosphate leaching to waterbodies causing water quality concerns. Two strategies that could minimize N and P losses include (i) incorporating winter rye (Secale cereale L.) (WR) as a cover crop to capture residual nutrients or (ii) intensifying the corn-soybean rotation with winter wheat (WW) (Triticum aestivum L.) (Double cropping). Double cropping WW at a right N management could increase farm profit and provide incentives for adoption as well. A trial was established at two sites (Carbondale, and Belleville, IL) to evaluate soybean and overall cash crop performance along with nitrate-N and phosphate losses in a single season [soybean following a no-cover crop control vs. WR as compared to three double cropping scenarios (low, medium, and high intensity N management of WW prior to soybean). The results indicated that double cropping decreased soybean yield regardless of N management intensity during the previous WW. Nitrogen addition to WW resulted in increased nitrate-N leaching during the WW phase but at medium and high N intensity scenarios, decreased the nitrate-N leaching during the following soybean phase and overall WW-soybean growing seasons suggesting double cropping could minimize N losses and provide farm profit.

How to cite: Ola, O., Guzel, O., Gage, K., Williard, K., Schoonover, J., Mueller, S., and Sadeghpour, A.: Does nitrogen management in winter wheat affect its yield and nitrate-N leaching in a wheat-soybean double cropping system?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6323, https://doi.org/10.5194/egusphere-egu24-6323, 2024.

EGU24-6470 | Posters on site | SSS7.3

Effects of common inter-row management practices on vineyard soils in four European vineyard regions 

Peter Strauss, Stefan Strohmeier, Marton Toth, and Gunther Carl Liebhard

Vineyards are often located in areas with poor soil quality and hilly terrain. Conservation agricultural management with the inclusion of cover crops helps to maintain or increase the existing soil fertility in these areas that are difficult to cultivate. However, there are also several reasons in favour of keeping vineyard inter-rows bare, including competition for water and nutrients, restrictions in pest control, and additional costs. As a result, a variety of site-adapted inter-row management systems have been developed in the different wine-growing regions. We investigated the effects of common management practices on soil organic carbon and soil physical parameters in topsoils of Austrian, French, Romanian, and Spanish wine-growing regions. In each region, we analysed management systems with and without cover crops. The comparison between the vineyard regions shows the variety of management intensities across the vineyard regions and their effects on soil quality parameters. Due to the differences in climate, soil, and management systems and, in particular, the mechanical soil disturbance intensity, bare soil, and cover crop management led to a broad range of soil organic carbon stocks, soil structure parameters, and soil hydraulic properties. While cover crop management caused an increase in carbon stocks in most vineyards compared to bare soil management, cover crop management in Spain was not effective in increasing soil organic carbon accumulation. In line with the increase in organic carbon also the measured soil structure parameters improved, yet the extent depended on the type and intensity of soil disturbance. The least clear effects of inter-row management systems were found for soil hydraulic parameters. As the local management strategies are a combination of adaptations to local conditions, farmers' experiences, and historical developments, the findings from the comparison of the systems can be used to rethink local strategies and improve the individual systems. This primarily concerns the type and intensity of cover crop management.

How to cite: Strauss, P., Strohmeier, S., Toth, M., and Liebhard, G. C.: Effects of common inter-row management practices on vineyard soils in four European vineyard regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6470, https://doi.org/10.5194/egusphere-egu24-6470, 2024.

EGU24-6991 | Orals | SSS7.3

Calculation and Analysis of Soil Erodibility Factor (K) on a Global Scale 

Miaomiao yang, Qinke Yang, Keli Zhang, Guowei Pang, Chunmei Wang, Lei Wang, and Yongqing Long

The soil erodibility factor (K) is the main data required for regional soil erosion investigation and mapping using soil erosion models. USLE-K, RUSLE2-K, EPIC-K and Dg-K are four widely used methods for calculating soil erodibility factor (K). However, it remains to be studied which algorithm is more suitable to calculate soil erodibility factor (K) in the global scale. While, soil erodibility factor (K) is mostly calculated based on soil physical and chemical property data, which does not involve the content of rock fragments in these algorithms. However, the amount of rock fragments and thier distribution difference have a certain influence on soil physical and chemical properties, and then affect the accuracy of the estimation of soil erodibility factor (K). In this paper, USLE-K, RUSLE2-K, EPIC-K and Dg-K algorithms were used to estimate global soil erodibility factor (K), and its spatial pattern and main controlling factors were analyzed. In this paper, the measured data of soil erodibility factor (K) were retrieved by literature search, and the measured database of K factor value was established. The rationality of the results of the above four algorithms was analyzed, and the above four algorithms for calculating K factor were modified according to the measured database of K factor. At the same time, USLE-K and RUSLE2-K algorithm are taken as an example to calculate the effect of rock fragments in the soil profile and rock fragments on the soil surface. The results showed that (1) The spatial pattern of global K factors estimated by the USLE-K, RUSLE2-K, EPIC-K and Dg-K models is similar, but the values in the K surfaces are different in some extent. (2) Comparing to 106 measured values, the mean value of estimated RUSLE2-K is the closest to the measured K factor, followed by the USLE-K algorithm and the EPIC-K algorithm, while the estimated K by Dg-K algorithm is quite different from the measured K factor. (3) The presence of rock fragment in the soil profile increased the global soil erodibility factor. The rock fragment on the soil surface reduces soil erodibility. This article made the calculation of K more complete and accurate, thereby improving the accuracy of regional soil erosion estimation. And provide the necessary scientific basis for the selection of K algorithms globally.

How to cite: yang, M., Yang, Q., Zhang, K., Pang, G., Wang, C., Wang, L., and Long, Y.: Calculation and Analysis of Soil Erodibility Factor (K) on a Global Scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6991, https://doi.org/10.5194/egusphere-egu24-6991, 2024.

EGU24-7265 | ECS | Orals | SSS7.3

Assessment of Soil Erosion in the Pan-Third Pole Region 

Xuyan Yang, Chaozheng Du, Qinke Yang, Chunmei Wang, Guowei Pang, Lei Wang, and Yongqing Long

Abstract: Climate change and human activities are seriously affecting the intensity and extent of soil erosion in the Pan-Third Pole region (PTP), which covers an area of approximately 5.14 × 107 km2. Accurate assessment of soil wind and water erosion is crucial for controlling soil degradation. In this study, soil water erosion in the PTP was estimated for 2018 using sampling units and the China Soil Loss Equation (CSLE), and soil wind erosion in the PTP from 1982 to 2020 was simulated using the Revised Soil Wind Erosion Equation (RWEQ), based on meteorological, soils, topographic, and remote sensing data. The results showed that: (1) Soil water erosion in the PTP mainly occurs in East Asia, South Asia, and the Black Sea coastal region, and the average soil wind erosion rate of the whole region is 263.4 t•km-2•a-1, and the average water erosion rate of the key erosion areas with water erosion rates exceeding 2,500 t•km-2•a-1 is 22.6 times higher than the average water erosion rate of the study area, and annual erosion amounted to 57.1×108t, accounting for 38.6% of total erosion amount. The soil water erosion rates of cropland, grassland, and forest were 525.7 t•km-2•a-1, 362.6 t•km-2•a-1, and 185.6 t•km-2•a-1, respectively. (2) Soil wind erosion in the PTP mainly occurs in cropland and grassland in semi-arid areas, and aeolian sand activity primarily occurring in extremely arid and arid areas (deserts), and the average multi-year soil wind erosion rate in regions other than deserts is 633.65 t•km-2•a-1, of which the mean soil wind erosion rate in the area where soil wind erosion rate is greater than 50 t•km-2•a-1 was 4,316.94 t•km-2•a-1, for cropland, grassland, and scrubland were 1,981.14 t•km-2•a-1, 3,815.05 t•km-2•a-1, and 4,010.95 t•km-2•a-1, respectively. (3) From 1982 to 2020, the soil wind erosion rate in the PTP decreased by 10.61 t•km-2•a-1. The proportion of the area with a decreasing trend was 19.53%, while the proportion of the area with an increasing trend was 28.35%. (4) Soil wind and water combined erosion mainly occur in cross-border regions of northern Syria, the Indus River Plain, the northern border of Iran and Afghanistan, the southwestern part of the Qinghai-Tibet Plateau, central Mongolia, the central part of the Loess Plateau, Inner Mongolia, and the bordering areas of the three eastern provinces, the average soil erosion rate of is 4,534.77 t•km-2•a-1, with the average soil erosion rates for grassland and cropland being 4,752.41 t•km-2•a-1 and 1,495.68 t•km-2•a-1, respectively. This study provided a comprehensive understanding of soil erosion (both soil wind and water erosion) in the PTP, and offered valuable data and decision-making support for current and future soil erosion prevention and ecological restoration projects.

How to cite: Yang, X., Du, C., Yang, Q., Wang, C., Pang, G., Wang, L., and Long, Y.: Assessment of Soil Erosion in the Pan-Third Pole Region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7265, https://doi.org/10.5194/egusphere-egu24-7265, 2024.

EGU24-7414 | ECS | Orals | SSS7.3

Modelling the effects of long-term tillage practices on soil organic carbon stocks in Pyhra 

Marton Toth, Jess Davies, John Quinton, Christine Stumpp, Andreas Klik, Bano Mehdi-Schulz, Gunther Liebhard, Peter Strauss, and Stefan Strohmeier

In contrast to conventional tillage, conservation practices can increase carbon storage in the topsoil. However, it remains unclear how soil organic carbon (SOC) changes under future climate, which would be essential striving towards sustainability. Process-based models are useful for exploring future environmental changes and understanding how systems may respond to multiple future drivers. Here, we applied the model N14CP, an integrated terrestrial C-N-P cycle model, to a nearly three-decadal long-term field experimental site in Lower Austria to simulate and determine the impacts of conventional tillage (CT), mulch tillage (MT), and no-till (NT) practices in combination with climate scenarios on SOC stocks in the topsoil (0-15 cm). Presumably, the experimental site was used as a grassland for centuries before being converted into conventionally tilled arable land in 1970; the MT and NT tillage plots were laid out in 1994. Since then, the study site was comprehensively sampled in 2002, 2013, and 2023. The research quantifies the long-term SOC stock changes from 1994 to 2100, considering the three tillage practices and RCP4.5 and RCP8.5 climate scenarios in the near (2021-2050) and far (2071-2100) future. The N14CP model performed well with the measured and simulated data validation. Based on our estimations, the NT is the only tillage practice that could increase SOC stocks between 1994 to 2100. However, considering +1.4 °C and +2.3 °C (RCP4.5) as well as +1.3 °C and +4.0 °C (RCP8.5) potential changes in the short-term and late-term future led to a decrease in the carbon stocks in the NT topsoil. SOC stock significantly decreased under CT and MT. Since the NT was the tillage practice that could retain the topsoil carbon, it can be considered an appropriate approach to deal with climate change in comparable agro-ecosystems.

How to cite: Toth, M., Davies, J., Quinton, J., Stumpp, C., Klik, A., Mehdi-Schulz, B., Liebhard, G., Strauss, P., and Strohmeier, S.: Modelling the effects of long-term tillage practices on soil organic carbon stocks in Pyhra, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7414, https://doi.org/10.5194/egusphere-egu24-7414, 2024.

EGU24-7421 | Posters virtual | SSS7.3

Ecological environment quality evaluation of the gully area in the Loess Plateau based on remote sensing ecological index 

Yujie Zhang, Xiaoping Zhang, Jie He, Liang He, Weinan Sun, Wenliang Geng, Haojia Wang, Yichen Wang, Zefeng An, Kaiyang Yu, and Xuanhao Liu

Abstract: As the fundamental foundation for human survival and development, the ecological environment is an important guarantee for social progress. With the accelerated development of society, the impact of human activities on the ecological environment has become increasingly significant. Fu County (4,182 km2) is located in the gully area of the Loess Plateau, an important ecological security barrier in the north of China. Clarifying the current situation of the ecological environment and the temporal and spatial changes of ecological environment quality in Fu County is conducive to the construction of ecological civilization. It provides scientific support to improve ecological quality.

Based on the remote sensing images of Landsat in Fu County from 1992 to 2019, we considered four indexes of Normalized Difference Vegetation Index (NDVI), Tasseled Cap Transformation Humidity Index (Wet), Normalized Difference Bare Soil Index (NDBSI), and Land Surface Temperature (LST) to represent greenness, humidity, dryness and heat of the environment. The principal component analysis was uesd to establish a remote sensing ecological index model (RSEI). And then we evaluated the ecological quality in the area in the past 30 years.The results showed that: (1) The average correlation between RSEI and four indexes was 0.874, which means RSEI can comprehensively reflect the ecological environment quality status of the study area compared with a single index. (2) The regional mean values of RSEI in Fu County showed an upward trend from 0.621 to 0.806 between 1992 and 2019, and the increase in ecological environment quality gradually increased from northwest to southeast of the county. (3) The increasing area and magnitude of the ecological level of the county from 1992 to 2019 were much greater than the decling area and magnitude. Over the past 30 years, the relatively sparsely populated townships of Zhiluo, Niwu and Zhangjiawan, which have a high degree of vegetation cover, have always been in a better state, while the densely populated townships of Jizixian, Jiaodao and Yangquan has always been poor. From the perspective of the degree of change in the quality level of the ecological environment, all townships have been improved to different degrees, and the improvement is the most obvious in Jizixian Town, Jiaodao Town and Yangquan Town.

The improvement of ecological environment quality level from good to excellent is probably because that the implementation of many ecological projects and the increase in rainfall, and the decrease in bare soil area and surface heat decreased in Fu County in the past 30 years.This study can provide method reference and data support for ecological environment monitoring, governance and protection.

 

Keywords: Fu County; Ecological environment quality evaluation; RSEI; Dynamic monitoring

How to cite: Zhang, Y., Zhang, X., He, J., He, L., Sun, W., Geng, W., Wang, H., Wang, Y., An, Z., Yu, K., and Liu, X.: Ecological environment quality evaluation of the gully area in the Loess Plateau based on remote sensing ecological index, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7421, https://doi.org/10.5194/egusphere-egu24-7421, 2024.

EGU24-8651 | ECS | Posters on site | SSS7.3

Evaluating agricultural management systems: Case study of apple orchards in Chinese Luochuan 

Weinan sun, xiaoping zhang, José Alfonso Gomez, Gangshuan Bai, Zefeng An, and Xuanhao Liu

Agricultural management behavior is one of the core features of agricultural soil ecosystems. Poor human management may contribute to the rapid degradation of soils on a world-wide scale.Traditional management, which usually aims to maximize productivity, faces great challenges when pursuing agricultural soil health, high efficiency, and sustainable development. Evaluating the agricultural soil management system based on multiple perspectives is crucial for effectively guiding the management framework. A large number of research on agricultural management evaluation mainly focues on national and regional scales, and the evaluations are dominated by socio-economic indicators. Comprehensive evaluations at the sample scale, that incorporate specific agricultural management techniques need to be further explored.This paper establishes an agricultural management evaluation system at sample-scale based on the DSR logical framework. The capital- and labor-related indicators are used as system Drivers, technical indicators resulted from soil management and soil properties to characterize the management Status, and economic output-related indicators as system Responses. Then, a comprehensive index is calculated to inform the economic characteristics, ecological friendliness, and soil health status. As the case study, three distinct agricultural soil management systems of apple orchards in Chinese Luochuan were assessed. The results show that organic-management system is superior for excellent management skills, the conventional management system is lowest in the index due to inferior drivers and technical indicators. The green- management system is middle one. The method is useful for evaluating the soil management system in the similar agricultural areas in the world.

How to cite: sun, W., zhang, X., Gomez, J. A., Bai, G., An, Z., and Liu, X.: Evaluating agricultural management systems: Case study of apple orchards in Chinese Luochuan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8651, https://doi.org/10.5194/egusphere-egu24-8651, 2024.

EGU24-8732 | ECS | Posters virtual | SSS7.3

Preliminary exploration of understory leaf area index inversion based on multi-angle remote sensing. 

Haojia Wang, Xiaoping Zhang, Liang He, Wenliang Geng, and Weinan Sun

    Soil erosion is one of the most widespread and serious environmental problems globally. Accurately obtaining understory vegetation parameters is a challenge for regional soil erosion assessment. This article introduces a method for obtaining understory vegetation Leaf Area Index (LAI) using multi-angle remote sensing techniques. Based on the Moderate-resolution Imaging Spectroradiometer (MODIS) Bidirectional Reflectivity Distribution Function (BRDF) data product (MCD43A1), the 4-scale geometric optical model was used to separate forest canopy and background reflectance. Combined with the measured understory LAI, a model for the inversion of understory LAI in the study area was developed. The results demonstrated that the background reflectance showed a similar seasonal variation trend as the reflectance of adjacent grassland, and significant difference was found between the background reflectance and the corresponding pixel total reflectance. Total reflectance was fitted separately with the measured canopy LAI and understory LAI. The coefficient of determination, R-square value between total reflectance and measured canopy LAI was 0.419, while the R-square value between total reflectance and measured understory LAI was only 0.053, it was indicated that the total reflectance mainly represents the information of the canopy. Established simple inverse models for the leaf area index of understory vegetation. the correlation between understory vegetation LAI and Ratio Vegetation Index (RVI) calculated based on background reflectance was the best, with the R-square value of 0.4733, Root Mean Square Error (RMSE) of 0.55, and Mean Relative Error(MRE) of 14.62%. This research can provide a method for evaluating understory vegetation in the quantitative estimate of regional soil erosion.

KeyWords:Leaf area index; Multi-angle remote sensing; Background reflectance; Understory vegetation.

How to cite: Wang, H., Zhang, X., He, L., Geng, W., and Sun, W.: Preliminary exploration of understory leaf area index inversion based on multi-angle remote sensing., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8732, https://doi.org/10.5194/egusphere-egu24-8732, 2024.

Loess Plateau is a typical ecologically-fragile area worldwide. Vegetation restoration acts as a long-term and important strategic program wherein, while the ecological effects after long-term vegetation restoration need to be assessed in detail to support for ecological restoration in similar areas. Across the Loess Plateau, four representative sites: the P. tabulaeformis artificial forest, P. orientalis artificial forest, R. pseudoacacia artificial forest and natural Secondary forest were selected as typical artificial plantations and natural forests in this study. To analyze ecological benefits under different vegetation restoration types and discuss the optimal model of afforestation in the future, soil properties in 0-100 cm, vegetation attributes at four synusium, hydrological processes of 23 rainfall events and ecosystem functions (10-years soil water storage) were measured and compared. The results showed that: (1) the soil properties of natural forest, especially soil water retention, were better than that of planted forests; (2) the biomass of arborous synuium in natural forest was lower than that in artificial forest, while it was significantly higher at shrub and herbaceous synuium; (3) there were differences in rainfall redistribution between natural and artificial forest with the satisfactory water storage conversion in study, but the natural forest had the highest soil water storage (414.33 mm) during the last decade; (4) according to the structure equation model (SEM), the vegetation attributes at arborous and herbaceous synuium had the most direct and total effects on the hydrological processes and function in ecosystems. The results indicate that afforestation should be conducted in a nature inclusive manner, which can provide guidance for vegetation restoration in the Loess Plateau and similar ecologically-fragile regions in the future.

How to cite: Feng, T., Zhang, Y., and Wang, P.: Long-term effects of restoration strategies on ecosystem functions, soil conservation and afforestation on the Loess Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9142, https://doi.org/10.5194/egusphere-egu24-9142, 2024.

EGU24-9522 | ECS | Posters virtual | SSS7.3

Estimation and evaluation of carbon sink of terraces measures in Loess Plateau : A Case Study of Wuqi County 

Kaiyang Yu, Xiaoping Zhang, Hui Cheng, Weinan Sun, Wenliang Geng, Haojia Wang, Xuanhao Liu, Liang He, Yujie Zhang, Zefeng An, and Yichen Wang

Estimation and evaluation of carbon sink of terraces measures in Loess Plateau : A Case Study of Wuqi County

Kaiyang Yu1, Xiaoping Zhang1, Hui Cheng2, Weinan Sun1, Wenliang Geng1, Haojia Wang1, Xuanhao Liu1, Liang He1, Yujie Zhang1, Zefeng An1, Yichen Wang1

1Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi 712100, China

2Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China

Abstract: Extensive terracing to cultivate land or plant trees and grasses, will affect biogeochemical processes in terrestrial ecosystem especially in areas with severe erosion. In order to clarify the carbon sequestration function and capacity of terrace in Loess Plateau, terraced fields with different planting types and years were selected to compare with corresponding slope land within Wuqi County (3,791 km2) of Loess Plateau to investigate the distribution characteristics of SOC on soil profile in 100 cm and searching for the influencing factors in the area. The results showed that:(1) Level terrace has significant carbon sink function in Loess Plateau. After the construction of terraced fields, SOC of six soil layers has the same variation trend with the construction years. The total SOC in the profile undergoes a rapid accumulation in the early 5-10 years of terracing construction, then exceeded the control group, and reaching a stable level after 20 years. (2) SOC in terrace dramatically decreases from surface layer to bottom layer, which exhibits surface aggregation effects. The content of SOC in 0-10 cm is significantly higher than that in deep soil layers, and the difference in SOC in deep soil is not significant. (3) The contents and accumulation rate of SOC in terrace are different with the planting types and years. Terraces with forest land generally has higher accumulating rate than other planting types. (4) There is significant correlation between total SOC and organic carbon content of large soil aggregates. Soil aggregates with particle size greater than 0.25mm determined the amount and trend of SOC content in the soil.  These results can provide an essential basis for improving the soil fertility and evaluating the benefit of terrace in carbon conservation on the Loess Plateau.

Key words: Terrace; Soil organic carbon; Soil aggregate; Loess Plateau

How to cite: Yu, K., Zhang, X., Cheng, H., Sun, W., Geng, W., Wang, H., Liu, X., He, L., Zhang, Y., An, Z., and Wang, Y.: Estimation and evaluation of carbon sink of terraces measures in Loess Plateau : A Case Study of Wuqi County, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9522, https://doi.org/10.5194/egusphere-egu24-9522, 2024.

EGU24-11211 | ECS | Posters on site | SSS7.3

Assessment of Nitrogen Dynamics in an Acidic Sandy-Loam Soil: Impact of Varied Nitrogen Sources and Incorporation of Chabazite Zeolite Tuff 

Matteo Alberghini, Giacomo Ferretti, Giulio Galamini, Barbara Faccini, Silvia Balzan, and Massimo Coltorti

Volcanic tuffs containing high percentage of zeolites have been extensively studied, both in their natural state  or enriched with nitrogen, as a means of enhancing soil properties and fertilizer efficiency. Limited data however exist on their application in acidic sandy soils and in conjunction with organic fertilizers.

This work consists of a 50-day laboratory incubation study wherein the nitrogen dynamics in an acidic sandy-loam agricultural soil fertilized with various nitrogen sources were investigated. These sources included urea, nitrogen-enriched chabazite zeolite tuff, and pelleted composted manure. Additionally, the nitrogen sources were tested in combination with the addition of chabazite zeolite tuff in its natural state to act as a soil improver.

The results revealed distinct behaviors among the various nitrogen sources, particularly affecting soil pH and nitrogen dynamics. Mineralization was very slow in manure-fertilized soil, whereas nitrogen-enriched zeolite exhibited a more balanced behavior in terms of net nitrate production and ammonium consumption. Nitrogen-enriched zeolite and urea demonstrated a temporary "liming" effect, while pelleted manure promoted a prolonged shift of soil pH toward neutral values.

In conclusion, nitrogen-charged chabazite zeolite tuff proved to be a valuable nitrogen source in acidic sandy-loam soil, serving as a viable alternative to synthetic fertilizers and an effective means of nitrogen recycling.

 

How to cite: Alberghini, M., Ferretti, G., Galamini, G., Faccini, B., Balzan, S., and Coltorti, M.: Assessment of Nitrogen Dynamics in an Acidic Sandy-Loam Soil: Impact of Varied Nitrogen Sources and Incorporation of Chabazite Zeolite Tuff, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11211, https://doi.org/10.5194/egusphere-egu24-11211, 2024.

EGU24-13581 | ECS | Orals | SSS7.3

The IN-GEST SOIL Project: results of the introduction of good practices for soil management in piedmont vineyards 

Giorgio Capello, Marcella Biddoccu, Francesco Palazzi, Laura Allemanno, Fermin Maggi, Matteo Tasca, Davide Ferrarese, Daniela Tornato, Andres Manunta, Simone Bussotti, and Elisa Paravidino

The IN-GEST SOIL Project (Innovation in viticulture soils management trough the adoption of good practices and tools to support field activities), funded by the EU and Regione Piemonte within Rural development program 2014-2020 for Operational Groups, aims to reduce soil erosion and enhance soil and vine quality in Piedmont hillside vineyards. This is achieved through the introduction of three key innovations: 1) Improved best soil management practices; 2) Agro-meteorological monitoring for improved water and soil management; 3) ICT tools for the management of monitored data and field observations, to support farmers in vineyard management and water-soil conservation. This study aims to improve the environmental sustainability of the vineyard, a goal that gains significance in the face of the context of the climate change. With forecasts predicting rising temperatures, decreasing rainfall, and an increase in extreme events like droughts and intense rainfall in thein the Mediterranean region, the project’s relevance is underscored. In Piedmont, recent rainfall scarcity has led wine growers to reduce the use of permanent grassing, opting instead for temporary or partial cover crops. While beneficial to soil functioning regardless of soil type, these cover crops often compete for water with grapevines, necessitating careful management in water-scarce areas. To explore the impact of different soil management systems and appropriate field operation planning, the IN-GEST project implemented study cases in 2021. These were conducted over two growing seasons in one experimental and five commercial vineyards located in the Alto Monferrato, Gavi and Colli Tortonesi vine-growing areas. In each vineyard, a more conservative soil management practice was compared with current or traditional practices. The effects on soil quality and vineyard production were investigated through monitoring runoff and soil erosion at plot scale, bulk density and soil penetration resistance, soil water content, hydraulic conductivity, ground cover and surface biomass, and grapevine development and production. Vine-growers and agrotechnicians actively collaborated to the study cases, by collecting runoff data and recording field observations and operations through a specific app, which also provide information for vineyard’s management.

The results of the study confirmed the positive effect of permanent spontaneous grass in reducing runoff, erosion and soil compaction, especially in sloping vineyards. Grape production in 2021 and 2022 was higher or stable with the innovative soil management in the case of sown green cover. However, it was lower with permanent grass cover compared to tillage, especially in the younger and flat vineyard. It should be noted that the monitored seasons were exceptionally dry, with the latter characterized by low production across the region. In most of the monitored vineyards, less intensive soil management resulted in increased water infiltration during rainfall events and higher soil moisture in topsoil and, in some cases, at depth of 40 cm. The benefits of grass cover were more evident when a selected grass mixture was sown and used as green manure, resulting in reduced soil bulk density and increased soil moisture, even during very dry seasons.

How to cite: Capello, G., Biddoccu, M., Palazzi, F., Allemanno, L., Maggi, F., Tasca, M., Ferrarese, D., Tornato, D., Manunta, A., Bussotti, S., and Paravidino, E.: The IN-GEST SOIL Project: results of the introduction of good practices for soil management in piedmont vineyards, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13581, https://doi.org/10.5194/egusphere-egu24-13581, 2024.

To research the soil health of different vegetation restoration measures in black soil region of Northeast China, the 0-10cm soil layer with different vegetation restoration measures (pure larch forest and mixed forest) were selected to be the object of study in Binxian County, Harbin City, Heilongjiang Province, China. The farmland were selected to be the control check (CK). The soil physical, chemical and biological indexes have been measured to determine the soil health of the soil with different vegetation restoration measures. The results showed that (i) in the 0-10cm soil layer, the soil bulk density of pure larch forest and mixed forest decreased significantly by 16% and 23%. The soil of the mixed forest has a lower soil bulk density and a higher soil water holding capacity and porosity. Compared with the soil of CK, the soil mean weight diameter of pure larch forest and mixed forest were significantly increased by 211.73% and 338.35%. The soil geometric mean diameter (GMD) of pure larch forest and mixed forest were significantly increased by 180.78% and 248.99%. (ii) The soil total carbon of pure larch forest and mixed forest were significantly increased by 39.98% and 43.98%. The soil total nitrogen of pure larch forest and mixed forest were significantly increased by 54.95% and 53.47%. The soil available K of pure larch forest and mixed forest were significantly increased by 26.88% and 133.67%. (iii) The soil microbial carbon (S-MC) of pure larch forest and mixed forest were significantly increased by 84.87% and 165.17%. The soil microbial nitrogen of pure larch forest and mixed forest were significantly increased by 10.80% and 62.32%. The Solid-Sucrase of pure larch forest and mixed forest were significantly increased by 45.79% and 73.68%. In general, there were significant differences in soil health among the soil with different vegetation restoration measures and CK. The mixed forest has the best restorative effects in the 0-10cm soil layer, which has the largest increase in GMD, available K and S-MC. The study would like to provide reference for the restoration of land and soil health evaluation in black soil region of Northeast China.

How to cite: Liu, B. and Fu, Y.: Effects of Different Vegetation Restoration Measures on Soil Health in Black Soil Region of Northeast China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13810, https://doi.org/10.5194/egusphere-egu24-13810, 2024.

To explore the soil water holding capacity and soil structure on sloping farmland with terrace measures in Black Soil Region of Northeast China. The construction of terraces slope farmland in different soil types (Black soil, Dark brown soil and Brown soil) is taken as the research object, the slope farmland (non- terraced slopes) was used as a blank control (CK). In the study, the spatial uniform distribution method was used to quantify the soil water holding capacity, soil structure characteristics and spatial distribution characteristics of construction of terraced slope farmland. The results showed that (i) the physical properties of soil after terrace construction in Black Soil Region were better than that of CK, and the improvement degree was Brown soil > Black soil > Dark brown soil. (ii) Compared with the CK, the soil physical properties of Brown soil in terrace slope farmland were improved obviously. The soil saturated water holding capacity of terrace slope farmland increased by 10.24 %. Besides, the soil capillary water holding capacity of terrace slope farmland increased by 16.77 %, and the soil field water holding capacity of terrace slope farmland increased by 16.10 %. Compared with the CK, the soil structure characteristics of Brown soil in terrace slope farmland were also more stable, and he total soil porosity and capillary porosity of terraced slope farmland increased by 9.14 % and 15.56 %. (iii) Terraced slope farmland of Brown soil mainly affect soil moisture characteristics and soil porpsity, in which soil capillary water holding capacity with 12.11 % of contribution rate, and the contribution of terraces to total soil porosity was 11.21 %. The main influencing factors of terraces in Dark brown soil were soil structure characteristics, in which the contribution of soil total porosity was 13.84 %, and the contribution of water-stable aggregate content was 13.31 %, which were greater than that of CK ; The contribution rate of each index of terrace of Black soil is relatively uniform, at 10.24 % -12.5 %. In summary, the terraces of Brown soil affect the characteristics of soil moisture and soil structure. The terraces of Dark brown soil mainly affects the characteristics of soil structure. Terraces of Black soil mainly affect soil moisture characteristics.

Keywords : black soil region; terraces; soil water holding capacity ; characteristics of soil structure ;

How to cite: Wei, S. and Fu, Y.: Study on Soil Physical Properties of Terraced Slope Farmland in Black Soil Region of Northeast China., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13812, https://doi.org/10.5194/egusphere-egu24-13812, 2024.

EGU24-13815 | Posters virtual | SSS7.3

How does vegetation restoration affect the soil quality on the Loess Plateau? A meta-analysis 

Wenliang Geng, Shunxia Duan, Yangyang Li, Xiaoping Zhang, and Csilla Hudek

Abstract: Soil degradation is one of the biggest environmental problems facing the earth today, with which more than 33% of the earth’s soil currently degraded. Soil erosion is considered to be one of the dominant and prevalent form of soil degradation in the developing countries. The Loess Plateau is the areas with the most serious soil erosion in China and even in the world. A number of literatures showed that vegetation restoration was one of the most effective measures in controlling soil erosion and preventing soil degradation. But the effects of vegetation restoration across climate, vegetation types and restoration years are not clear. A meta-analysis was conducted and achieved 1731 paired observations from 71 peer-reviewed papers to improve the understanding of the effects of vegetation restoration on soil quality and to identify the factors influencing its changes.

       The results showed that: (1) The literatures are distributed in various provinces of the Loess Plateau, with the most concentrated distribution in northern Shaanxi Province. In terms of specific data, the relevant data covered several aspects of soil quality indicators, such as Bulk density (n=180), Soil total porosity (n=91), Soil aggregate stability (n=65), Soil organic matter (n=180), Total nitrogen (n=166), Total phosphorus (n=112), Available nitrogen (n=47), Available phosphorus (n=63), Microbial biomass carbon (n=46), Microbial biomass nitrogen (n=29), Microbial biomass phosphorus (n=20), and others.

       (2) Compared with the farmland, after vegetation restoration on the Loess Plateau, soil bulk density was significantly reduced by 6-10 %, soil total porosity was significantly increased by 12-16 %, soil aggregate stability was significantly increased by 18-24 %, soil saturated hydraulic conductivity was significantly increased by 12-18 %, soil organic carbon and total nitrogen content was significantly increased by 47-55 % and 43-52 %, microbial biomass carbon, nitrogen, phosphorus and enzyme activity were also significantly increased.

       (3) The effect of vegetation restoration on soil quality mainly depends on soil texture, vegetation type and restoration year. Generally, the effect of forest on soil quality is higher than that of shrub and grass. The effect of vegetation restoration on soil quality increases with the increase of vegetation restoration years.

       The results of the study provide a basis for the evaluation of the ecological effects of vegetation restoration in the Loess Plateau, and can provide a reference for the selection of reasonable vegetation allocation methods under different restoration conditions, thereby improving soil degradation in arid and semi-arid areas.

Keywords: Vegetation restoration; Soil quality; Meta analysis; Loess Plateau

How to cite: Geng, W., Duan, S., Li, Y., Zhang, X., and Hudek, C.: How does vegetation restoration affect the soil quality on the Loess Plateau? A meta-analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13815, https://doi.org/10.5194/egusphere-egu24-13815, 2024.

The total area of soil degradation in China is about 460 million hectares, and the problem of soil degradation needs to be solved urgently. Can government regulation, as an important means to encourage farmers to use soil remediation technology, and guide farmers to improve their awareness and thus promoting their adoption? Based on the survey data of 403 rural households in Shaanxi and Shanxi provinces of China, the orderly probit model was used to empirically analyze the direct effects of government regulations on various soil remediation behaviors of rural households. Factor analysis was used to measure the cognition level of policy effectiveness, ecological benefit, social value and subject responsibility, and their effect on the government regulation is analyzed through the intermediary effect model. It was found that farmers in loess area had good soil remediation behavior and adopted 3 remediation techniques on average. The influence of different government regulations on farmers' soil remediation behavior is heterogeneous. Government subsidies and technical training significantly promoted farmers to implement soil remediation behavior, while publicity and education had no significance and negative impact. Further mechanism test showed that policy cognition and subject responsibility cognition played a positive moderating role, while social value cognition and ecological benefit cognition played a negative masking effect. The influence of propaganda and training on farmers' soil remediation behavior was 42.69% and 32.73% through social value cognition by masking effect. Therefore, it was necessary to put more allowances, carry out in-depth and meticulous publicity and education, broaden technical guidance channels, and adhere to the combination of rewards and punishments, to promote farmers' scientific soil testing and precision fertilization, and improve the agricultural green development mechanism.

How to cite: Li, S. and Liu, J.: How Does the Government Regulation Affect Farmers’ Soil Remediation Behavior?—Based on a Mediation Effect Analysis of Farmers’ Cognition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14064, https://doi.org/10.5194/egusphere-egu24-14064, 2024.

Under the common requirements of ensuring food security and agricultural green development goals, how to explore a way of coordinated development of cultivated land protection and utilization, and effectively achieve "storing grain in the land and storing grain in technology" is the focus of sustainable agricultural development in China. Based on the field survey data of 233 apple growers in typical apple growing areas of Shaanxi and Shanxi in China, this paper used the Super-SBM model to measure agricultural technical efficiency and the propensity score matching (PSM) method to analyze the impact of green production technology adoption behavior on agricultural technical efficiency, and the dimension of green production technology adoption was further expanded to analyze the impact of different technology adoption conditions on technical efficiency. The results showed that the average production technical efficiency of apple growers in typical apple growing areas of Shaanxi and Shanxi was 0.513, which had a large room for improvement on the whole. After eliminating sample selection bias by using PSM method, adopting green production technology could significantly improve the technical efficiency of apple growers. According to the results, the corresponding policy suggestions were provided to promote the adoption of technology by apple growers, protect the health of soil, improve the production efficiency of apple growers and realize the green development of agriculture.

How to cite: Han, C. and Liu, J.: Behavior of Green Production Technology and Impact on Technical Efficiency——Evidence from China's Apple Growers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14069, https://doi.org/10.5194/egusphere-egu24-14069, 2024.

EGU24-17024 | ECS | Orals | SSS7.3

A long-term soil erosion modeling example in Central Europe over the last 150 years. 

Raquel Falcao, Adam Babuljaka, Martina Mazancová, Tomáš Dostál, Anton Van Rompaey, Dominik Kaim, and Josef Krasa

Land use and climate change are the main anthropogenic factors influencing soil erosion (Borrelli et al., 2020), the former providing instant and abrupt effects. This justifies the profusion of related studies and their relevance in providing support for public policies. Europe acknowledges this importance, as the 8th EAP includes the goal of no net land take by 2050. The Rimov catchment, in the southern part of the Czech Republic and partly in Austria, has undergone many land use changes in the region over the last 150 years. It has undergone two opposing processes in terms of their contribution to soil erosion potential: on one hand, agricultural land has been left for spontaneous vegetation recovery (therefore, reducing its potential for soil erosion); on the other hand, the enlargement of parcel size after the collectivization of agriculture has the potential to increase soil erosion. In addition, long-term soil erosion modeling should consider the effect of the change in the rain erosivity factor (R-factor), with the calibration of the model done with the rainfall data covering the study period, which will be considered on the hydrological modeling prior to the soil erosion modeling in this study. Using the WATEM/Sedem model, we analyze whether the regeneration of vegetation has been enough to counteract the effects of an increasing R-factor in the Rimov catchment.

Research has been supported by project TUDI (European Union's Horizon 2020 research and innovation programme under grant agreement No 101000224) and by Program CELSA-fonds (Project The impact of depopulation on ecosystem services in Europe. A Pilot study in France, Czech Republic, and Poland No 3E220627)

References

The European Parliament and the Council of the European Union, Decision (EU) 2022/591 of the European Parliament and of the Council of 6 April 2022 on a General Union Environment Action Programme to 2030. https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32022D0591, 2022

Borrelli, P., Robinson, D. A., Panagos, P., Lugato, E., Yang, J. E., Alewell, C., Wuepper, D., Montanarella, L., & Ballabio, C. (2020). Land use and climate change impacts on global soil erosion by water (2015-2070). Proceedings of the National Academy of Sciences, 117(36), 21994–22001. https://doi.org/10.1073/pnas.2001403117

How to cite: Falcao, R., Babuljaka, A., Mazancová, M., Dostál, T., Van Rompaey, A., Kaim, D., and Krasa, J.: A long-term soil erosion modeling example in Central Europe over the last 150 years., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17024, https://doi.org/10.5194/egusphere-egu24-17024, 2024.

EGU24-17404 | ECS | Posters on site | SSS7.3

From plot to catchment scale: evaluating historical and adapted land management practices in an agricultural watershed in Tajikistan 

Oliver Konold, Cosima Benedek, Peter Visintin, Maximilian Thier, Victoria Stoisser, Christine Stumpp, Bano Mehdi-Schulz, Faridun Khudonazarov, Shinan Kassam, Sharif Aminov, Davlatshoh Khojaev, Sharif Khojaev, Mira Haddad, Akmal Akramkhanov, and Stefan Strohmeier

Societal and agronomic changes during Tajikistan’s post-soviet era have altered the rural farmland management and the related catchment hydrology. The increasing demand for food production and the limited crop diversity eventually affected soil health and surface hydrological processes. Late planting of summer crops, the removal of plant residues and intense soil disturbance through ploughing are accompanied with limited rainfall interception, which fosters runoff and eventually erosion with potentially disastrous consequences in the downstream areas. As part of Caritas Switzerland's Weather, Water, Climate Services (WWCS) initiative, jointly funded with the Swiss Agency for Development and Cooperation, this study assesses the adoption of Sustainable Land Management (SLM) practices at the field level to reduce surface runoff and erosion, while diversifying and enhancing crop production. This study focuses on a 6356 km2 large watershed in the Khatlon region of Tajikistan and couples field experimental runoff plot monitoring with process-based hillslope scale modeling (Water Erosion Prediction Project; WEPP), eventually connected with watershed level hydrological assessment (Soil and Water Assessment Tool; SWAT). Field experimental procedures are being conducted through national, international and local citizen scientists. The study is in its initial phase – however, one season of plot monitoring has been conducted that allows a preliminary assessment of the surface runoff and erosion response of bare, summer wheat, chickpea, alfalfa and esparcet plots. The experiment enables the assessment of the single crops’ performances, as well as integrating crops into rotations through modeling. At the same time, land use and land cover (LULC) ground truthing within the Khatlon watershed was undertaken to validate two freely available global data products provided by the European Space Agency ESA; the CCI LC 300m and the ESA WorldCover 10m datasets. From the ESA CCI LC product, a comprehensive time series from 1992 to 2020 was developed to analyse the changes in LULC within the research area. The validation process enhances the reliability of the LULC data, which is also important for modelling purposes, in the Khatlon region. In a next step, involving multiple stakeholders, land suitability assessment and mapping will yield plausible watershed management scenarios to evaluate the potential of diversification and the introduction of multi-seasonal crops (i.e. alfalfa and esparcet) to reduce surface runoff and sediment yields from the farmlands and to strengthen the local agro-ecosystems and their sustainable production.

How to cite: Konold, O., Benedek, C., Visintin, P., Thier, M., Stoisser, V., Stumpp, C., Mehdi-Schulz, B., Khudonazarov, F., Kassam, S., Aminov, S., Khojaev, D., Khojaev, S., Haddad, M., Akramkhanov, A., and Strohmeier, S.: From plot to catchment scale: evaluating historical and adapted land management practices in an agricultural watershed in Tajikistan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17404, https://doi.org/10.5194/egusphere-egu24-17404, 2024.

EGU24-18000 | ECS | Posters on site | SSS7.3

Watershed Resilience - Soil and Water Management in Arid Regions to Prevent Desertification 

Mira Haddad, Abeyou Worqlul, Doa’a Abu Hammour, Muhi El-Dine Hilali, and Osama Gazal

 Jordan faces a critical challenge of land degradation and water scarcity, primarily affecting the extensive natural rangeland (Badia), which covers over 80% of the country's area. The degradation of natural vegetation, adversely affects local agropastoral communities that are depending on livestock farming and triggeing downstream issues such as flash floods and sedimentation in dams. Water harvesting and increasing vegetation cover are promising technologies to adapt and reduce the impact.

  The Badia Research Site (BRS), a confined watershed of approximately 1000 hectares, rainwater harvesting (RWH) and plantation techniques have shown promise in reducing soil erosion and runoff rates and enhancing various ecosystem services. The BRS research is mainly led by the International Center for Agricultural Research in the Dry Areas (ICARDA) and the Jordan National Agriculture Research Center (NARC), supported by the United States Forestry Service (USFS).

  This study involves (1) scaling out two RWH techniques, namely the Vallerani and the Marab, on a larger basin. The scaling out utilises local and international datasets, incorporating biophysical parameters such as land use, digital elevation models, slope, topographic wetness index, soil texture, and climate data. Optimal ecological conditions for plants, including temperature and soil pH, are considered. (2) The Soil and Water Assessment Tool (SWAT) is employed to analyse and assess the impact on surface hydrological processes.

  The focus is on the Wadi Al Mujib basin, covering 6584.37 km2 in the central part of Jordan. The semi-arid to arid environment comprises two principal wadies, Wadi Al Walah and Wadi Mujib, with distinct catchment surfaces. The basin's predominantly desert land, receiving varying levels of rainfall, poses challenges to 80% of its area, while the remaining 20% is dedicated to agricultural and residential use.

  The study further employs the model to evaluate global climate change scenarios, assessing the impact and quantifying changes in ecosystem services with and without restoration efforts. These findings contribute to supporting the Jordanian government's restoration endeavours, offering a holistic approach to addressing land degradation and water scarcity challenges in the region.

 

Keywords: Watershed assessment, Degraded land restoration, Suitability mapping, Water harvesting techniques, Sustainable land management, and Ecosystem Services

How to cite: Haddad, M., Worqlul, A., Abu Hammour, D., Hilali, M. E.-D., and Gazal, O.: Watershed Resilience - Soil and Water Management in Arid Regions to Prevent Desertification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18000, https://doi.org/10.5194/egusphere-egu24-18000, 2024.

EGU24-18113 | ECS | Orals | SSS7.3

Enhancing Crop Production and Soil Health: A Dual Approach with Process-Based Modeling and Continuous Soil Health Monitoring in Rainfed and Irrigated Agriculture in Tajikistan 

Peter Visintin, Maximilian Thier, Cosima Benedek, Victoria Stoisser, Oliver Konold, Reinhard Nolz, Bano Mehdi-Schulz, Faridun Khudonazarov, Shinan Kassam, Sharif Aminov, Davlatshoh Khojaev, Sharif Khojaev, Mira Haddad, Akmal Akramkhanov, and Stefan Strohmeier

Unsustainable agricultural management in Tajikistan's norther Laksh district has caused significant land degradation. Climate change and the related hydrological shifts further disrupt water management, particularly in irrigated systems. The current farming practices such as inefficient furrow irrigation with saline water and conventional soil cultivation hamper the soil's infiltration capacity, intensify runoff, and eventually degrade various ecosystem functions including crop production. Advanced Information and Communications Technology (ICT) based decision support systems e.g. for irrigation scheduling are under development; however, key soil parameters, including soil hydraulic properties, are largely unknown. As part of Caritas Switzerland's Weather, Water, Climate Services (WWCS) initiative, jointly funded with the Swiss Agency for Development and Cooperation, this research combines monitoring and modeling based approaches to investigate the local soil-water-crop processes and to eventually enhance the according management, functionality and productivity in both irrigated and rainfed agricultural systems. Field-assessed soil physical, chemical and biological properties serve as the benchmarks for establishing a Soil Health Index and crafting process-based modeling scenarios. In irrigated systems a surrogate modeling approach is employed combining Hydrus 2D and its ‘Furrow’ submodule with AquaCrop. The establishment of the Soil Health Index is currently underway, with successive monitoring aimed at evaluating changes in soil health over time in relation to selected conservation practices. The assessment of soil hydraulic and physical properties has provided key parameters, including hydraulic conductivity, field capacity and permanent wilting point. Those parameters and knowledge can be directly integrated into ICT applications (e.g. weather-based irrigation advisory services) that optimize the use of scarce inputs (water, fertilizer, etc) within sustainable production systems; and simultaneously enhancing resilience to short term weather changes and longer-term climate change.

How to cite: Visintin, P., Thier, M., Benedek, C., Stoisser, V., Konold, O., Nolz, R., Mehdi-Schulz, B., Khudonazarov, F., Kassam, S., Aminov, S., Khojaev, D., Khojaev, S., Haddad, M., Akramkhanov, A., and Strohmeier, S.: Enhancing Crop Production and Soil Health: A Dual Approach with Process-Based Modeling and Continuous Soil Health Monitoring in Rainfed and Irrigated Agriculture in Tajikistan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18113, https://doi.org/10.5194/egusphere-egu24-18113, 2024.

EGU24-19118 | Orals | SSS7.3

Vegetation Scenarios to Improve the Conditions at the Desiccated Aral Seabed and to Reduce the Impacts of Sand and Dust Storms 

Mira Haddad, Akmal Akramkhanov, Abeyou Worqlul, Stefan Strohmeier, Steven de Jong, Abduvokhid Zakhadullaev, Ioannis A. Chaniotis, Platon Patlakas, and Christos Stathopoulos

Although Central Asia has been exposed to sand and dust storms (SDS) due to the Kyzylkum and Karakum deserts, it is also the place of a most tragic environmental disaster of the 20th century: the drying out of the Aral Sea created the Aralkum desert that is considered a relatively new addition to the global hotspot SDS sources. The loss of Aral Sea transformed the surrounding environment into a vast area of bare land dominated by solonchak soils prone to further degradation and desertification. Consequently, the exposed saline sediments have become SDS sources across the region, causing negative impacts on multiple socio-ecological aspects. Recently, the government of Uzbekistan launched and further investigated various campaigns on planting adapted shrub and tree species to establish a robust rangeland ecosystem.

This study aims to determine the effects of the vegetation-based options on protecting the erodible sediments from wind-induced movement and improving the local ecological conditions. Wind erosion depends on soil erodibility, selected plant species for out-planting, and vegetation cover succession that might develop. This study developed six vegetation cover scenarios to represent a broad spectrum of potential vegetation cover and stages, ranging from a bare surface (newly dried seabed) to dense vegetation cover conditions. Local 3-hourly wind speed data of the past 20 years was analyzed to define erosive wind events. Each vegetation cover scenario was used in the wind erosion simulation model to assess the impact of different covers on soil erosion.

The simulation of the physical-based erosion model revealed critical wind speed thresholds of erosion initiation that most likely occur when wind velocities exceed 10-15 m/s. The erosion ranges linked to the exceedance of three hourly wind speeds of >= 15 m/s (class 1), >= 20 m/s (class 2), and >= 25 m/s (class 3), respectively, were investigated for the six clearly defined vegetation scenarios. The simulation unveils that dense vegetation covers of assorted trees, shrubs, and grasses could ultimately stop erosion, as locally verified through observations in scattered and well protected well-vegetated areas. A more likely and large coverage of a lower-density vegetation could reduce erosion by around 40%. Combining shrubs and potentially emerging grasses would reduce wind erosion by up to 70%.

The study indicates that plantation and increasing vegetation cover could remarkably enhance SDS prevention. In addition, it would improve the local ecosystem services such as e.g. storing carbon and serving as potential feed sources for livestock, while preventing contaminated and saline dust from being transported to vulnerable off-site areas.

How to cite: Haddad, M., Akramkhanov, A., Worqlul, A., Strohmeier, S., de Jong, S., Zakhadullaev, A., A. Chaniotis, I., Patlakas, P., and Stathopoulos, C.: Vegetation Scenarios to Improve the Conditions at the Desiccated Aral Seabed and to Reduce the Impacts of Sand and Dust Storms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19118, https://doi.org/10.5194/egusphere-egu24-19118, 2024.

EGU24-19272 | ECS | Posters on site | SSS7.3

Validation of a sediment connectivity binary model improved with a probabilistic approach in the effect of prairie strips. 

Jose Antonio Muñoz, Brian K. Gelder, Gema Guzmán, and Jose Alfonso Gómez

Prairie strips (PS) have demonstrated remarkable effectiveness in sediment control and partially interrupting sediment connectivity (SC). Research projects such as STRIPS have devoted two decades to investigate this strategy and to promote associated and additional ecosystem services at agricultural landscapes.
The experimental area was within the Neal Smith National Wildlife Refuge (Iowa, USA). Since 2007, an assessment involving 12 watersheds (3 controls, 9 treatments) was conducted to evaluate the advantages of incorporating PS into rowcrop (Corn-Soybean rotation). Treatments consisted in altering the PS number and area. Helmers et al. (2012) exhibited sediment trapping efficiencies (STE) averaging above 90%.
To the extent of our knowledge, current models attempting to calculate STE are complex. Mahoney et al. (2018) parameterized the probability of SC with a binary model, combining various individual probabilities. One of these probabilities is buffer disconnectivity, where buffers interrupt runoff and disconnect the entire upstream area. If we consider a PS as a buffer, sediment will not pass when the PS is present, and vice versa. Another approach is the one from Muñoz et al. (2023), who analysed STE in vegetation strips using a probabilistic approach, finding a wide range of variation in STE, from -109 to 100%. 
This communication presents the integration of this approach to the previous model from Mahoney et al. (2018), going from a binary model in the buffer disconnectivity probability to a model with a range of values between -∞ and 1. Assuming a direct correlation between sediment load and connected pixels, we ran the model across the experimental watersheds during a period of 7 years to validate the result of SC in the model. The results of the model by events and in each watershed were poor due to the variability between precipitation and sediment load. However, considering a weighted arithmetic mean with the rainfall for sediment load and connected pixels, good positive relationships emerged between average sediment load and average connected pixels when the model was applied individually to each watershed for the whole period. As a final part, we extended the model to the set of watersheds, where the correlation was absent.
Nevertheless, the combination of both approaches allows one to factor the probability of STE for specific management practices without significant added complexity, resulting in a strong fit for small watersheds with management with PS. 

Acknowledgement: Work was funded by Spanish Ministry of Science and Innovation (PID2019-105793RB-I00), project SCALE (EUHorizon2020 GA 862695), and a predoctoral fellowship (PRE2020-093846). We also acknowledge and appreciate the numerous funders and researchers of previous STRIPS Project investigations.

References
Helmers et al. (2012). Sediment removal by prairie filter strips in row‐cropped ephemeral watersheds. Journal of Environmental Quality, 41(5), 1531-1539. 
Mahoney et al. (2018). Watershed erosion modeling using the probability of sediment connectivity in a gently rolling system. Journal of Hydrology, 561, 862–883. 
Muñoz et al. (2023). Appraising trapping efficiency of vegetative barriers in agricultural landscapes. Strategy based on a probabilistic approach based on a review of available information. International Soil and Water Conservation Research

How to cite: Muñoz, J. A., Gelder, B. K., Guzmán, G., and Gómez, J. A.: Validation of a sediment connectivity binary model improved with a probabilistic approach in the effect of prairie strips., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19272, https://doi.org/10.5194/egusphere-egu24-19272, 2024.

EGU24-20790 | Posters on site | SSS7.3

Optimized fertilizer N rates for bioenergy feedstock production and water quality in drylands 

Brett Allen, Upendra Sainju, and Sadikshya Dangi

Bioenergy feedstocks offset demand for conventional petroleum-based energy resources. Switchgrass (Panicum virgatum L.) is a warm-season perennial grass that has been utilized for lingo-cellulosic ethanol production and direct energy via combustion. However, little is known about its potential as a feedstock in the semi-arid northern Great Plains USA, including effects of N fertilizer application on system productivity and environmental quality. A field study initiated in 2009 seeded ‘Sunburst’ switchgrass into plots with fertilizer N broadcast each spring at 0, 28, 56, and 84 kg N per ha as urea, with four treatment replicates. Each fall beginning in 2011, aboveground biomass was harvested, weighed, and dried. Soil cores to a depth of 1.2 m were taken in fall 2018, air-dried, and analyzed for soil nitrate. Switchgrass biomass ranged from 1.8 to 12.3 Mg per ha. In most years, N application increased switchgrass biomass, but response to N rates above 28 kg per ha was inconsistent. Biomass from fertilized switchgrass averaged 6.5 Mg per ha compared to 4.4 Mg per ha for the unfertilized control.  Soil nitrate levels indicated the potential of over-fertilization of switchgrass feedstocks to negatively impact water resources in drylands. 

How to cite: Allen, B., Sainju, U., and Dangi, S.: Optimized fertilizer N rates for bioenergy feedstock production and water quality in drylands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20790, https://doi.org/10.5194/egusphere-egu24-20790, 2024.

EGU24-21032 | Orals | SSS7.3

Implementation of soil restoration strategies based on methodology for defining soil health farm types in EU 

Dimitre Nikolov, Ivan Boevsky, Krasimir Kostenarov, Ekatherina Tzvetanova, Martin Banov, Magardich Huliyan, Laura Zavattaro, Josef Krasa, Tomas Dostal, Gunther Carl Liebhard, Peter Strauss, Zsofia Bakacsi, Csilla Hudek, and Jose A. Gomez

Soil health is a significant problem in agriculture which demands a tailor-made approach. The study aims to develop a methodological approach for farm typology construction in terms of soil health. Thus, the focus is on EU farms, which produce in the three key cropping systems - grassland, cereal-based rotation, and tree crops. It was applied principal component analysis based on which it was constructed four factors, related to soil health. This approach bridges soil health problems with socioeconomic, environmental, and technology assessments. Soil health farm typology determinations is an essential step in any realistic evaluation of constraints and opportunities that farmers face and helps develop appropriate technological solutions, policy interventions, and comprehensive environmental assessment. It can be used to describe the possibilities and implications at larger regional scales of new strategies for promoting soil restoring and best fertilization technologies in agriculture and its inclusion in agricultural and environmental policies. The farm typology in term of soil health was constructed applying two sequential multivariate techniques: principal component analysis (PCA), and cluster analysis (CA).

Key words: soil health, farm typology, crops, tree crops, cereal-based rotation, grassland

Acknowledgement: The research is made under the project “Transforming Unsustainable management of soils in key agricultural systems in EU and China. Developing an integrated platform of alternatives to reverse soil degradation” – TUdi. This project receives funding from the European Union’s Horizon 2020 Research and Innovation action under grant agreement No 101000224.

How to cite: Nikolov, D., Boevsky, I., Kostenarov, K., Tzvetanova, E., Banov, M., Huliyan, M., Zavattaro, L., Krasa, J., Dostal, T., Liebhard, G. C., Strauss, P., Bakacsi, Z., Hudek, C., and Gomez, J. A.: Implementation of soil restoration strategies based on methodology for defining soil health farm types in EU, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21032, https://doi.org/10.5194/egusphere-egu24-21032, 2024.

EGU24-364 | ECS | Orals | SSS7.7

Transport Mechanisms of Microfibers and Their Effects on Soil-Plant Systems 

Zhangling Chen, Steven.A Banwart, Paul Kay, Devlina Das Pramanik, David Ashley, Weiyi Feng, and Thomas Nash

Microplastics (MPs) have emerged as a global environmental concern due to the uncertainties surrounding their occurrence, fate, and potential implications for environmental and human health. While research on the impact of MPs on aquatic systems is expanding, studies investigating their influence on terrestrial systems are limited. Agricultural soil acts as a dominant reservoir for MPs, with microfibers being a predominant form due to the application of organic amendments. Despite their ubiquity, the transport mechanisms of these particles and their effects on soil-plant systems remain largely unknown. This study addresses critical knowledge gaps by conducting a series of soil incubation experiments aimed at exploring the effects of polyester (PES) microfibers on soil quality and the growth of three common crops: lettuce, Chinese cabbage, and radish. Plants were cultivated in glass jars containing 100mg/kg fluorescent microfibers thoroughly mixed with the soil. Microfiber distribution was visualized using EVOS Auto FL 2. Soil endpoints revealed that the presence of microfibers induced significant alterations in soil bulk density, with minimal impact on soil carbon and nitrogen content across all plant treatments. Additionally, microfibers exerted a significant decrease in soil pH in lettuce-growing soil, while exhibiting a marginal pH increase in cabbage-growing and radish-growing soils. Microfibers were also found to diminish the formation of water-stable aggregates, particularly in the cabbage-growing soil. In terms of plant endpoints, the study observed accelerated germination of lettuce in the presence of microfibers, while the root length of radish was substantially affected. Microfibers led to a reduction in chlorophyll content in lettuce and cabbage leaves, whereas radish leaves exhibited an increase when exposed to microfibers. Microfibers were detected in both lettuce and radish roots and stems, and weak fluorescence was detected in lettuce leaves. Notably, the impact of microfibers varied among plant species, emphasizing the necessity for species-specific considerations. Furthermore, this study highlights the negative, positive, and neutral effects of microfibers on soil properties and plant performance and proves the potential uptake of microfibers by certain edible plants. The observed outcomes are attributed to the distinctive characteristics of fibers, including their unique shape, surface area, and flexibility, which may interact with soil particles and crops. Given the widespread distribution and accumulation of microfibers in agricultural soil, this study provides crucial insights for ecotoxicological assessments related to soil and terrestrial higher plants. It also holds implications for stakeholders in environmental pollution, food safety, and human health.

How to cite: Chen, Z., Banwart, S. A., Kay, P., Pramanik, D. D., Ashley, D., Feng, W., and Nash, T.: Transport Mechanisms of Microfibers and Their Effects on Soil-Plant Systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-364, https://doi.org/10.5194/egusphere-egu24-364, 2024.

Column experiments are used to study infiltration and transport behavior of microplastics (MP) in aquifers. The transport behavior of various MP polymer types, including PET, POM, PMMA, and PS, which differ in size (0.8 – 3 mm), density (1.03 – 1.42 g/cm3), and shape, has been examined. The MP particles were added to the inflow of columns containing different gravel compositions, having both unimodal (d50 = 12, 6.5, 2.5, 1.2 mm) and bimodal distribution (d50 = 10, 6, 3.5 mm), and also of columns filled with sand (d50 = 0.031 and 0.065 mm). To introduce MP particles into the sediment, a novel approach involving melting frozen MP particles embedded in ice layers was employed. This method naturally replicated the infiltration process while minimizing blockages or particle losses in the circuit's pipes and connectors. After infiltration at defined flow rates for three days, MP particles have been separated from sediment layers of 3 cm thickness manually or using density separation. The depth where they were identified is defined as infiltration depth. Micro computed tomography (Micro-CT) was applied to visualize sediment pores and throats where MP passed through. Results for infiltration in different gravel textures showed as expected that smaller MP are transported to a greater depth. Lighter MP were also found in deeper layers due to its shape. Concerning shape effects, flat circular discs showed a higher potential to be found at greater infiltration depth, compared to spheres, fibers and pellets. Concerning the size ratio between MP and sediment grains bimodal sediment reveals to hinder the infiltration of MP due to its lower pore size, which is consistent with results from the Micro-CT pore measurement. Initial results from sand column experiments will be analyzed to explore the size ratio range between sediments and MP under saturated conditions, highlighting the differences in MP behavior between sand and gravel. The findings enhance our understanding of MP transport mechanisms in aquifer sediments and infiltration basins and offer insights for groundwater and sediment MP contamination mitigation.

How to cite: Ding, J. and Grischek, T.: Laboratory Experiments on the Transport of Microplastic Particles in Gravel and Sand Sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3856, https://doi.org/10.5194/egusphere-egu24-3856, 2024.

EGU24-4033 | ECS | Orals | SSS7.7

A field experiment on macroplastic redistribution and fragmentation by soil tillage  

Ahsan Maqbool, Gema Guzman, Peter Fiener, Florian Wilken, María-Auxiliadora Soriano, and Jose Alfonso Gomez

Soil is polluted with plastic waste from macro to submicron level, and research has intensified on the fate and transport of plastic with more focused particulate plastic, including fibers (<5mm). Yet, our understanding of macroplastic (>5mm) occurrence and behavior has remained comparatively elusive, mainly due to a lack of tracing mechanism. This study utilized magnetically tagged soil movement and provided a comparison with a method for tracing macroplastic pieces labeled with a physically adhesive passive radiofrequency identification transponder used as an innovative and efficient approach. A field study following best practice approaches of soil tillage was carried out to determine the displacement of macroplastic during the non-inversion chisel and inversion disk tillage process to understand the fate of macroplastic in arable land. All the experiments were performed at plain topography to eliminate the downslope and drift effect, while tillage depth (0.15 m) and speed (4.5 km h-1) were kept constant during the tillage process. The results indicate that non-inversion tillage has a significantly more protracted macroplastic transport displacement compared to inversion tillage by a factor of 2.4.  The mean displacement of macroplastic by tillage erosion is 0.36 ± 0.25 m chisel and 0.15 ± 0.13 m disk tillage per pass. However, inversion tillage caused substantially more fragmentation of macroplastic. In general, both tillage implements drove the burial of surface macroplastic into the plow layer.  This highlights that soil can act as a long-term sink for macro and microplastic and would expect less plastic to be transported into the atmosphere and aquatic system from arable land.

 

This project gets financing from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement number 955334.

How to cite: Maqbool, A., Guzman, G., Fiener, P., Wilken, F., Soriano, M.-A., and Gomez, J. A.: A field experiment on macroplastic redistribution and fragmentation by soil tillage , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4033, https://doi.org/10.5194/egusphere-egu24-4033, 2024.

Plastic films are essential in modern livestock and crop production. According to the Plastics Europe Report 2022, Light Polyethylene (LDPE) and Polypropylene (PP) are the primary plastic material demand in the agricultural sector. Especially for crop production, plastic mulching films cover arable soil to increase temperature, reduce evaporation, and prevent weed growth. However, mechanical and environmental weathering removes microplastics from the mulch film and can stock in the soil. Additionally, sewage sludge and compost use in agriculture lead to further microplastic contamination. Obviously, microplastic input to soils is critically high, but an accurate quantification is still lacking. This is partly caused by challenges in detection and analysis of microplastic in soils. First, it is challenging to extract microplastic from a matrix of organic and inorganic particles of similar size. Second, the well-established spectroscopic methods (e.g., Raman and FTIR) for detecting microplastics in water samples are sensitive to soil organic matter, and they are very time-consuming. Eliminating very stable organic particles (e.g., lignin) from soil samples without affecting the microplastic to be measured is another challenge. Hence, a robust analytical approach to detect microplastic in soils is needed. In this context, we developed a methodological approach that is based on a high-throughput (25 g soil sample) density separation scheme for measurements in a 3D Laser Scanning Confocal Microscope (Keyence VK-X1000, Japan) and subsequently using a Machine-Learning algorithm to classify and analyze microplastic in soil samples. Our aim is to develop a method for a fast screening of microplastic particle numbers in soils while avoiding the use of harmful substances (e.g., ZnCl2) or prolonged organic carbon destruction. For method development, we contaminate three different soil types (sandy soil: 86.6% sand, 9.7% silt, 3.7% clay, 0.58% organic carbon; silty loam: 6% sand, 59% silt, 25% clay, 1.3% organic carbon analysis and loamy sand: 72% sand, 18% silt, 10% clay, 0.9% organic carbon) with transparent LDPE, black LDPE and PP microplastic in three different size ranges (< 50, 50 – 100 and 100 – 250 µm). Moreover, we test our method on microplastic fibers (PP, 1000 µm). The separated microplastic plus organic particles and some small mineral particles were scanned using a 3D Laser Scanning Confocal Microscope. For each sample, the 3D Laser Scanning Confocal Microscope generates three different main outputs: color, laser intensity, and surface characteristics with a pixel size of 2.72 µm. Based on these data outputs, a Machine-Learning algorithm distinguishes between the mineral, organic, and microplastic particles. It was found that color changes of microplastics due to soil contact challenge the classification but can be compensated by surface characteristics that become an essential input parameter for the detection. The presented methodological approach provides an accurate and high-throughput microplastic assessment in soil systems, which is critically needed to understand the boundaries of sustainable plastic application in agriculture.

How to cite: Scheiterlein, T. and Fiener, P.: Microplastic detection in arable soil using a 3D Laser Scanning Confocal Microscope coupled with a Machine-Learning Algorithm, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5018, https://doi.org/10.5194/egusphere-egu24-5018, 2024.

EGU24-5824 | ECS | Posters on site | SSS7.7

Denser microplastics migrate deeper? Effect of particle density on microplastics transport in artificial and natural porous media 

Wang Li, Giuseppe Brunetti, Annastasiia Bolshakova, and Christine Stumpp

Predicting the fate of microplastics (MPs) in porous media has been challenging and previous research mainly focused on the transport of MP considering plastic size and shape effects, media size effects, and solution chemistry effects. However, few studies examined the plastic density impact on the transport behavior of MPs in porous media. This is significantly important to gain insight into how the MP density influences its fate in the environment. Therefore, column experiments under saturated conditions were conducted to explore the MP transport in columns packed with glass beads and gravel and using polyethylene microspheres with different densities within the same size range together with a conservative tracer. Experimental results were fitted well (R2 > 82.3-98.7 %, and low RMSE value) with a two-site transport model with a depth-dependent blocking function in HYDRUS-1D. The results showed that particle density influences the transport of MPs, and the deposition rate varied with particle density in the following order: 1.12 g/cm3 > 0.995 g/cm3 > 1 g/cm3. This suggests that compared to neutrally buoyant and buoyant MP, denser MPs tend to deposit in the selected material under the tested flow rate. The coupled experimental and simulated results indicate that denser MPs may be retained but neutrally buoyant MPs can be potentially migrated with infiltrated water into subsurface systems, thus posing groundwater contamination risk. Hence, further studies are needed with viable densities and diverse conditions to advance the understanding the impact of plastic density on its transport fate.

Keywords: Microplastics, density, transport, sediments, glass beads

How to cite: Li, W., Brunetti, G., Bolshakova, A., and Stumpp, C.: Denser microplastics migrate deeper? Effect of particle density on microplastics transport in artificial and natural porous media, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5824, https://doi.org/10.5194/egusphere-egu24-5824, 2024.

EGU24-6319 | ECS | Posters on site | SSS7.7

Detection of plastic film residues on cropland using remote sensing techniques: from proximal to UAV-based remote sensing 

Alessandro Fabrizi, Peter Fiener, Kristof Van Oost, and Florian Wilken

Plastic residues found on cropland span across a wide range of polymers, shapes, sizes, and sources, which are all factors influencing the environmental risks of plastic pollution. A major potential plastic source of cropland soil systems is the intentional use of plastic in agriculture. Despite their role in improving crop production and management, plastic films have been associated with the generation of macro- and micro-plastic residues. Understanding the variables driving plastic film pollution and residue generation is important to quantify the overall input into soil systems and design good management practices. However, plastic residues are usually collected by manual sampling and quantified by ex-situ analyses, which is very time-consuming and limits data acquisition to small areas.

This study aims to analyse the potential of remote sensing data acquired from Unmanned Aerial Vehicles (UAVs) as a fast and cost-effective method for the detection of macroplastic residues on cropland. To understand the factors influencing plastic film detection when moving from pristine films to residues in soil, we collected hyperspectral (i.e., with a spectroradiometer) and multispectral data (i.e., with a multispectral camera) on different plastic films in an experimental outdoor setup. We used two different soils as a background and simulated the following conditions: pristine films, crumpled films, soil-covered films, and crumpled and soil-covered films. In this way, we built spectral libraries and identified absorption peaks. Moreover, the simulated spectral signature of plastic film residues matched the magnitude of changes observed in field samples available for black mulching films. We then assessed major challenges and possible workflows for detecting plastic residues with a multispectral camera mounted on a UAV.

How to cite: Fabrizi, A., Fiener, P., Van Oost, K., and Wilken, F.: Detection of plastic film residues on cropland using remote sensing techniques: from proximal to UAV-based remote sensing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6319, https://doi.org/10.5194/egusphere-egu24-6319, 2024.

EGU24-7949 | ECS | Orals | SSS7.7

Plastic input and dynamics in industrial composting 

Stoyana Peneva, Quynh Nhu Phan Le, Davi Munhoz, Olivia Wrigley, Flora Wille, Giovana P.F. Macan, Heidi Doose, Wulf Amelung, and Melanie Braun

Despite various attempts by composting facilities to remove plastics from compost, high levels of particularly small microplastics (1 µm - 5 mm, MiPs) are detected in compost.

To elucidate the potential removal or enrichment of MiP during the composting process, we first analyzed the input of macroplastics (> 20 mm, MaPs) via bio-waste collection in an industrial composting plant. Then, we further determined MiPs at five different stages during the composting process (before and after distinct shredding and screening processes), as well as in the water used for irrigation.

We found varying total concentrations of MaP in the bio-waste collected from different municipalities, ranging from 0.36 - 4.72 kg ton-1 bio-waste, with polyethylene (PE) and polypropylene (PP) being the most abundant types. Further, we found a similar presence of “foil” and “non-foil” plastics, with 0.824 ± 0.34 kg ton-1 and 0.83 ± 0.34 kg ton-1 bio-waste, respectively; only 0.3 ± 0.1 kg ton-1 bio-waste of biodegradable plastic was found. The total concentration of MaP and MiP increased from 12 items kg-1 before shredding to 34 items kg-1 bio-waste in the final compost, indicating a relative enrichment of the number of particles during the process. Analyzing the rain water used for moistening the compost (collected on the roof of the compost facility) revealed that already high amounts of PE, polyamide (PA) and PP particles with sizes of 6 - 70 µm were found in rainwater (22,714 ± 2,975; 3,108 ± 748 and 685 ± 398 particles L-1, respectively). These plastic loads were 1.4 to 5-fold lower in the process water collected after irrigation, indicating a co-contamination of compost by irrigation. 

This study highlights the importance of reducing plastic input via bio-waste, as it is one of the main sources for MiP contamination of compost, while also recognizing the challenges in effectively removing MiP during composting. The complex dynamics of MiPs, i.e. the enrichment of small MiPs, is problematic as small particles in particular have many ecotoxicological properties. We could identify irrigation water as a plastic source for compost, an input pathway that has been overlooked so far. Therefore, our results underline the need for comprehensive strategies to tackle plastic pollution throughout the composting cycle, from bio-waste input to final compost products.

 

How to cite: Peneva, S., Phan Le, Q. N., Munhoz, D., Wrigley, O., Wille, F., Macan, G. P. F., Doose, H., Amelung, W., and Braun, M.: Plastic input and dynamics in industrial composting, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7949, https://doi.org/10.5194/egusphere-egu24-7949, 2024.

EGU24-8145 | ECS | Orals | SSS7.7

Interaction of biosolids-derived dissolved organic matter with microplastics: EEM analysis 

Rashika Solomon and Gilboa Arye

Composted biosolids are commonly used in agricultural lands as organic amendments. However, biosolids application also exposes the soil to pollution risk from various contaminants including microplastics (MPs). The MPs inevitably interact with the dissolved organic matter (DOM), which is the most active fraction of the soil organic matter. The physiochemical properties of the DOM, which vary based on the organic matter origin, are one of the key factors influencing these interactions. The majority of studies on DOM-MP interactions employ commercially available humic and fulvic acid as the DOM source and may not accurately represent the polydisperse nature of DOM released from organic amendments used in agricultural fields. The motivation for this study stems from recognizing the knowledge gap in understanding the interaction between the naturally occurring DOM in the soil and the MPs. It is imperative to investigate these interactions to determine consequential changes in DOM composition and to evaluate the fate and cotransport with other pollutants in the soils. For this purpose, we conducted adsorption experiments with various concentrations of biosolids-derived DOMs and different MP particles. We used the Excitation-Emission matrix (EEM) obtained by fluorescence spectroscopy to study the changes in the DOM due to its adsorption on the MPs. PARAFAC modeling of the EEMs was used to identify the preferential binding affinity of distinct fluorescent DOM components to the MPs. The results of the adsorption experiment and the EEM analysis will be presented and discussed.

Keywords: microplastics, dissolved organic matter, biosolids, adsorption, fluorescence spectroscopy, EEM

How to cite: Solomon, R. and Arye, G.: Interaction of biosolids-derived dissolved organic matter with microplastics: EEM analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8145, https://doi.org/10.5194/egusphere-egu24-8145, 2024.

EGU24-8493 | ECS | Posters virtual | SSS7.7

Microplastic effects on soil organic matter dynamics and bacterial communities under contrasting soil environments 

Mariana Vezzone, Maria Heiling, Christian Resch, Chunhua Jiang, Vitória Almeida, João Paulo Felizardo, Roberto dos Anjos, and Gerd Dercon

The widespread use of plastic in agriculture and forestry includes several applications such as mulch, fertilizer bags, pesticide containers, seed germination tubes, greenhouse films, silage films, fruit protection bags, and irrigation pipes. Numerous studies have highlighted a substantial accumulation of plastic residues in soil, potentially leading to adverse effects on soil quality and agricultural productivity. A proposed solution for plastics that cannot be collected is to replace them with biodegradable plastics. However, the impact of biodegradable microplastics (MP) on the soil, especially in tropical regains, remains understudied. Climate and soil geochemical properties have an impact on microbial communities and their nutrient acquisition strategy. The minerals typical of highly weathered soils in tropical climates (kaolinite, gibbsite, goethite, and hematite) have functional groups that are reactive with soil organic matter (SOM) under acidic pH conditions, which enables the sorption and stabilization of SOM, making it physically inaccessible to microorganisms. Since MPs affect soil physicochemical characteristics, they indirectly affect SOM stability impacting soil carbon stock and fertility. In this work, we conducted an incubation experiment to evaluate MP biodegradation (pure polylactic acid - PLA and commercial polybutylene adipate terephthalate - PBAT, 1-2mm, 1 mgMP.g-1dry soil), and their effects on SOM dynamics in contrasting soils typical from tropical climates (Ferralsol from Brazil) and temperate climates (Chernozem from Austria). The experiment was conducted under 60% WHC at distinct temperatures (22ºC and 27ºC) with four replicates. The control treatment involved MP-free soil, and empty jars as blanks. The CO2 concentration and isotopic signature were measured by cavity ring-down spectroscopy. The geochemical soil properties were evaluated by EA-IRMS (C, N, δ13C and δ15N) and XRF (Ca, Na, K, Mg, P, Si, Al, Fe, and Mn) and the chemical index of alteration (CIA) was calculated as a proxy for its potential effects on microbial properties. The analysis of phospholipid fatty acids (PLFA) allowed the distinction of microbial groups and correlations between soil properties and microbial activity. CIA value was 39.7 for Chernozem and 96.6 for Ferralsol, which reflects the high degree of weathering of Ferralsol. C/N ratio was 14.0 for Ferralsol and 13.3 for Chernozem. The preliminary results (42 days) show that PLA inhibited microbial activity in both soils. CO2 emissions in PBAT treatments was more than 200% higher in Chernozems than in Ferralsols. The higher biodegradation rate in Chernozem may be associated with the greater availability of nutrients, as they are eutrophic soils, while Ferralsols are dystrophic. Microbial communities adapt their nutrient acquisition strategies to changes in the soil geochemical properties and may shift, with increasing CIA, from the predominant demand for carbon to phosphorus. In high CIA soils, changes in land use might favor fungi, which tend to adopt a conservative nutrient allocation strategy in acidic and nutrient-poor conditions, minimizing C loss through respiration. Conversely, low CIA soils predominantly harbor bacterial communities that prioritize C acquisition over biomass, leading to increased CO2 emissions via respiration. These dynamics must be evaluated with PLFA results and isotopic data to assess microbial changes and impacts on SOM.

How to cite: Vezzone, M., Heiling, M., Resch, C., Jiang, C., Almeida, V., Felizardo, J. P., dos Anjos, R., and Dercon, G.: Microplastic effects on soil organic matter dynamics and bacterial communities under contrasting soil environments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8493, https://doi.org/10.5194/egusphere-egu24-8493, 2024.

EGU24-9723 | ECS | Orals | SSS7.7

Farmers’ preferences for reducing agricultural plastics: A discrete choice experiment among UK farmers. 

Manuel Barrientos, Ashar Aftab, and Riccardo Scarpa

Post-Brexit agricultural policy has generated an extensive range of new instruments to improve the sustainability of UK farming. However, none of these proposed policies deal with plastic pollution on UK farmlands. In this article, we use the UK's evolving policy context regarding farming payments to propose a monetary incentive whose environmental policy target is to change or reduce the use of -potentially harmful- agricultural plastics. We conducted a Discrete Choice Experiment among a sample of northern England farmers in which they considered two hypothetical Sustainable Farming Incentive (SFI) contract alternatives plus an opt-out alternative. The proposed SFI contracts include five attributes, including the contract length, the SFI payment, and three agricultural plastic-reducing actions: i) reduce the use of polymer-coated fertilizers, ii) reduce the use of plastic mulch film, and iii) reduce the use of silage films made only of virgin plastics. These actions can be accomplished at a lower, medium, and high level of compromise, and the payment varies with them. As agricultural plastics are essential for farm productivity, farmers are not asked to completely eliminate their use but replace them with more sustainable alternatives. Moreover, we used a within-farmers design to test the effect of a stringent enforcement strategy on their participation and willingness to accept SFI. We hypothesize relevant trade-offs between the contract's compromise level, the monetary payment offered, and farm and farmer-specific variables such as farm size, farming activities, and plastic and microplastic pollution awareness, among many others. Likewise, stringent enforcement may lead to a reduction in the stated participation and an increase in the monetary compensation needed to perform the indicated activities. This research may help develop incentive-compatible agricultural policies to reduce the usage of harmful agricultural plastics and improve our understanding of key factors explaining farmers’ adherence to new agri-environmental schemes in the UK.

How to cite: Barrientos, M., Aftab, A., and Scarpa, R.: Farmers’ preferences for reducing agricultural plastics: A discrete choice experiment among UK farmers., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9723, https://doi.org/10.5194/egusphere-egu24-9723, 2024.

EGU24-9739 | ECS | Posters on site | SSS7.7

Agricultural mulch films as soil microplastic contamination factor 

Ana Carolina Cugler Moreira, Florian Wilken, and Peter Fiener

Plastic mulch films are increasingly used in agriculture to improve yields and simplify harvest as well as work processes. Beside the agronomic advantages, the use of mulch films is also associated with the risk of (micro) plastics entering the soil system. To which extend weathering and fragmentation of mulch films potentially leads to a soil contamination depends on the plastic characteristics, e.g. in terms of thickness, colour and UV resistance, which is associated with different purposes of mulch film application. This study aims to analyse the changes in plastic film properties as basis for plastic fragmentation and finally microplastic contamination, resulting from photodegradation and mechanical stress. We used different plastic mulch films and applied fixed UV light intensities at 50ºC temperature. We applied varying time of UV exposure and performed an abrasion test, where plastic film and soil were mixed at 4 rpm for 2 months to simulate mechanical stress. After the different treatments the effects on chemical groups, surface characteristics, hydrophobicity and mechanical stability of the mulch films were analysed. Therefore, the following techniques were utilized: (i) Fourier transform infrared with attenuated total reflectance (FTIR-ATR) spectroscopy, (ii) 3d laser confocal scanner microscopy (LSM), (iii) optical contact angle (OCA) analysis, and (iv) universal nanomechanical testing (UNAT). The FTIR-ATR analysis revealed spectral changes indicating an alteration in the carbonyl group content, related to photodegradation, when compared with samples without UV treatment. The OCA also demonstrated variations in the wettability of samples in both treatments, caused by the variation on the carbonyl content. Mechanical stress treatment also highlights changes on the sample surface, e.g., new scratches on the sample surface. UNAT results indicate variation on the Young’s modulus, related to the samples crystallinity. Overall, the combination of analyses suggests that photodegradation and mechanical stress cause changes in the carbonyl content, which can influence wettability and mechanical stability. Together with the surface changes under mechanical stress, the study presents a potential pathway of mulch foil fragmentation and MP formation.

How to cite: Cugler Moreira, A. C., Wilken, F., and Fiener, P.: Agricultural mulch films as soil microplastic contamination factor, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9739, https://doi.org/10.5194/egusphere-egu24-9739, 2024.

EGU24-10326 * | ECS | Orals | SSS7.7 | Highlight

Impact of plastic mulch and their associated leachates on seed germination 

Giovana P. F. Macan, Davi Renato Munhoz, Leo A. J. Willems, Paula Harkes, Violette Geissen, and Blanca B. Landa

The benefits of plastic mulch in agriculture, including higher crop yields, early seedlings development, and earlier harvests, are countered by challenges associated with their complete removal from the soil and proper disposal, ultimately contributing to plastic pollution. Plastic mulching is identified as a major source of microplastic pollution in agricultural soils, with an increasing number of reports indicating its impact on both soil and plant health. However, the causes of the adverse effects are still not clear. The risk posed by microplastics can arise from the plastic particles or as a consequence of the toxicity of chemical additives and plastic-derived compounds, which can be leached over time. In this study we assessed the impact of macro- and microplastic particles, along with their associated leachates, from both conventional (LDPE-based) and biodegradable (PBAT-based) mulch films on the germination of three plant species: arabidopsis (Arabidopsis thaliana), cotton (Gossypium hirsutum L.), and tomato (Solanum lycopersicum). We developed a comprehensive methodology for leachate extraction from macro and microplastics at concentrations of 0.2% and 2% w/w. This process involved monitoring various parameters over time including electrical conductivity (E.C), pH, total dissolved solids (TDS), and UV-visible absorbance indices. Additionally, we employed a semi-automated germination scoring pipeline, obtaining cumulative germination data that allowed the estimation of multiple germination parameters, including the maximum germination capacity (Gmax), the time required for 50% of the seeds to germinate (t50), and the area under the germination curve (AUC). Leachates from PBAT-based mulch showed a significant increase in the solution electrical conductivity (E.C), total dissolved soils (TDS), and absorbance indices for both macro and microplastics over time. Furthermore, a gravimetric weight loss of the biodegradable mulch samples occurred, indicating the release of certain compounds to the solution. Although there were no significant changes in the assessed proxies of leachates derived from LDPE-based mulch after one week, the leachates started to be released more pre-eminently after 35 days.  The seed germination assay revealed a negative effect of the leaching solution from the higher concentration of PBAT-based  leachates on the germination of arabidopsis seeds, as indicated by reduced Gmax(%), increased t50, and decreased AUC in comparison with the control. Although a slight reduction in germination was observed for the other plant species, the values were not statistically significant. When testing the impact of leached or new microplastic particles on the seeds, they did not significantly impact the seed germination parameters. This suggests a potential toxic effect of plastic leachates rather than the microplastics themselves. Further detailed characterization of leachate solutions will be conducted to gain a better understanding of the leaching process and the compounds released to determine the potentially hazardous substances affecting seed germination. These findings can offer valuable insights to the plastic industry, indicating the need to reduce or replace certain plastic building blocks and additives while exploring environmentally friendly alternatives. Moreover, the study underscores the need for increased attention to the environmental repercussions of plastic pollution in agriculture and its potential effects on plant health. 

How to cite: Macan, G. P. F., Munhoz, D. R., Willems, L. A. J., Harkes, P., Geissen, V., and Landa, B. B.: Impact of plastic mulch and their associated leachates on seed germination, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10326, https://doi.org/10.5194/egusphere-egu24-10326, 2024.

EGU24-10940 | ECS | Orals | SSS7.7

Influence of polymer age and soil aggregation on microplastic transport in soil erosion events 

Emilee Severe, Quynh Nhu Phan Le, Ahsan Maqbool, Benjamin Surridge, Crispin Halsall, José A. Gómez, and John Quinton

The transport of microplastics within and across terrestrial ecosystems is a critical factor controlling plastic pollution in the environment. However, our understanding of these transport processes remains extremely limited. Particular uncertainty surrounds how the changes driven by aging of plastics, for example in surface roughness or hydrophobicity, affect polymer transport.  In this study we compare the rate of transportation of pristine and aged polystyrene microplastics in a simulated rainfall event providing the first empirical data describing these processes. Additionally, we quantified the proportion of both aged and pristine microplastics incorporated into soil aggregates after several wet-dry cycles and the influence wet-dry cycles had on microplastic mobilization. The results from this study will provide critical insights into the influence of polymer age on microplastic mobility and retention in terrestrial environments.  

How to cite: Severe, E., Phan Le, Q. N., Maqbool, A., Surridge, B., Halsall, C., Gómez, J. A., and Quinton, J.: Influence of polymer age and soil aggregation on microplastic transport in soil erosion events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10940, https://doi.org/10.5194/egusphere-egu24-10940, 2024.

EGU24-11887 | ECS | Posters on site | SSS7.7

Global soil microplastic assessment in different land-use systems is largely determined by the method of analysis 

Olivia Wrigley, Wulf Amelung, and Melanie Braun

Although microplastics (1 μm - 5 mm, MPs) are increasingly recognised as a novel entity of pollutants, we still lack a basic understanding of their prevalence in different terrestrial environments, such as managed soils. Here, we aimed at elucidating the global MP pollution of managed soils, with specific focus on continental differences, input pathways, and land use types as impact factors, whilst considering the effect of the respective analytical methods on the reported results. After evaluation of 305 sites from 51 studies, we found that the analytical method mostly determined the reported MP load, as analysis of both small and large MPs, use of high density separation solution, and of post-density separation soil organic matter removal yielded significantly higher MP loads. The global means of MP loads benchmarks 2,081 ± 6323 MP items kg-1 soil (global median of 476 (0 - 72,200) MP items kg-1), with 75% of studies located in Asia. Highest mean numbers of MP items were found for Asia and The Americas (2,408 ± 7,194 and 2,138 ±  2,142 MP items kg-1 respectively), with the former being significantly higher than the mean MP concentration of Europe (1,153 ± 1,721 MP items kg-1, p < 0.05). Maximum MP numbers were found for soils under plastic mulching (2,576 ± 8,568 MP items kg-1), followed by greenhouses and polytunnels (1,980 ± 1,200 MP items kg-1), and sludge amendments (1,845 ± 1,925 MP items kg-1). There was no evidence of elevated MP loads in horticultural fields relative to other agricultural management practices (agronomy). Yet, quantitative comparisons were biased by the methodology selected for MP analyses, as looking at the effect size methodology had the largest effect on MP loads. Hence, we conclude that based on the current database, comparisons across studies and input pathways as well as land-use systems are hampered by methodological inconsistencies.

How to cite: Wrigley, O., Amelung, W., and Braun, M.: Global soil microplastic assessment in different land-use systems is largely determined by the method of analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11887, https://doi.org/10.5194/egusphere-egu24-11887, 2024.

EGU24-12094 | Posters on site | SSS7.7

Plastic fruit stickers - changes of surface and structure during industrial composting 

Melanie Braun, Max Groß, Matthias Mail, Olivia Wrigley, Rafaela Debastiani, Torsten Scherer, and Wulf Amelung

In the past, large amounts of plastic particles have been found in compost, which often originate from the improper disposal of plastics in organic waste. A so far little-noticed input pathway of plastic in compost are so-called price look-up stickers made of conventional plastic. For example, such fruit stickers remain in the organic material despite sorting processes in the composting plant. However, little is known about alterations of price look-up stickers during industrial composting. Thus, this study aimed to investigate whether an industrial composting process leads to surface and structural changes of fruit stickers. For this purpose, fruit stickers made of polypropylene were placed on banana peels in an industrial composting plant and sampled after pre-rotting (11 days) and main rotting (25 days). Afterwards, composted stickers as well as non-composted stickers (control) were analysed by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), micro- and nano-computed tomography (CT). After industrial composting, all stickers showed signs of surface changes and degradation in the form of cracks, irregularities, and microbial colonisation on both the front and the back. Microbial growth was visible from day 11. Structural changes were observed, with large adhesions penetrating the sticker's surface and an increase in the volume from 16.7 to 26.3% during composting, accompanied by an increase in the carbonyl index. The delamination observed on some stickers after 25 days of composting indicates the formation of smaller microplastic or even submicron plastics.

How to cite: Braun, M., Groß, M., Mail, M., Wrigley, O., Debastiani, R., Scherer, T., and Amelung, W.: Plastic fruit stickers - changes of surface and structure during industrial composting, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12094, https://doi.org/10.5194/egusphere-egu24-12094, 2024.

EGU24-12722 | ECS | Posters on site | SSS7.7

Potential degradation rates of contrasting plastic additives in agricultural soils 

Michaela Reay, Martine Graf, Maddy Murphy, Charlie Monkley, Perrine Florent, Hien Nguyen, Tien Tran Minh, Andreia Fernandes, Tapan Adhikari, Samantha Vilijoen, Ahmed Mosa, David Chadwick, Davey Jones, Richard Evershed, and Charlotte Lloyd

Plastic additives associated with plastic products are essential to their function. However, a number of compounds, which are included at relatively high abundances, and frequency in plastic products, have known associated hazards. These include phthalates, which are endocrine disruptors, as well as antioxidants and UV stabilisers, which may bioaccumulate. As additives are not chemically bound, they are susceptible to leaching to the wider environment, including into soils. However, the potential abiotic controls on degradation of additives in soil, such as soil type, pH and nutrient availability, following leaching remains unknown. This study investigates the degradation of three contrasting, high production plastic additives in soil to elucidate potential controls on the bioavailability of the plastic additives.

Three additives of contrasting function were selected: bis(2-ethylhexyl) phthalate (DEHP), a plasticiser, which is an endocrine disruptor; tris(2,4-di-tert-butylphenyl)phosphite (Irgafos® 168, an antioxidant under assessment as bio accumulative under EU REACH, and octabenzone, a UV stabiliser. An agricultural soil from North Wales with no previous history of plastic use was sieved (2 mm) and maintained at constant moisture (30% WHC). Additives were dried onto sand then homogenised in soil to yield a concentration of 500 ng g−1 soil. The degradation of additives was monitored over a 21 d time course with light exclusion. In the UK soil, Irgafos® 168 was not detected after t=0 d, due to rapid conversion to its oxidation product, tris(2,4-di-tert-butylphenyl)phosphate (Irgafos® 168ox), which also occurs abiotically during plastic production. However, no further microbial degradation of this antioxidant was observed over the 21 d period. DEHP and octabenzone both exhibited rapid degradation within 4 d, yet remained at 223 ng g−1 and 51 ng g−1, respectively, for the remainder of the 21 d experiment. The degradation of DEHP and octabenzone is proposed to be microbial, with 49% and 78% removed over 21 d, and the relative bioavailability of the additives was octabenzone>DEHP>>Irgafos® 168(ox). This will be expanded to include soils from across climatic zones (India, Vietnam, Australia, Brazil, Egypt), to elucidate controls on additive degradation linked to soil properties, including pH, soil type and nutrient availability, which are hypothesised to influence the bioavailability and preference for additive degradation.

How to cite: Reay, M., Graf, M., Murphy, M., Monkley, C., Florent, P., Nguyen, H., Tran Minh, T., Fernandes, A., Adhikari, T., Vilijoen, S., Mosa, A., Chadwick, D., Jones, D., Evershed, R., and Lloyd, C.: Potential degradation rates of contrasting plastic additives in agricultural soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12722, https://doi.org/10.5194/egusphere-egu24-12722, 2024.

EGU24-12964 | ECS | Posters on site | SSS7.7

Sewage Sludge in Farmlands: A Gateway to Soil Microplastic Pollution? 

Quynh Nhu Phan Le, Crispin Halsall, Marco Kunaschk, Shengkai Cao, Emilee Severe, Lorna Ashton, Ben Surridge, and John Quinton

This study examines the accumulation of microplastics in agricultural soils, an emerging concern linked to the widespread application of sewage sludge. In the UK, 87% of sludge is disposed of through this route. To investigate this potential pathway for microplastic transfer to soils, we analysed dewatered-anaerobically digested sludge from a local wastewater treatment plant and adjacent fields with varied sludge usage histories, including control fields with no sludge application.

Utilising fluorescent microscopy, Fourier-transformed infrared and Raman micro-spectroscopies, we detected significant microplastic presence in sludge samples (2900 ± 1400 particles/g DW and 1200 ± 400 fibres/g DW), predominantly polyethene, polyester, polypropylene, polystyrene, polyvinyl chloride and polyamide, sized between 20-500 µm. Preliminary results revealed elevated microplastic levels in fields that ceased sludge usage a decade ago in the topsoil (62 ± 33 particles/g DW), compared to control fields (8 ± 4 particles/g DW), with pronounced weathering effects on the surfaces of the microplastics.

The study also discusses differences in microplastic concentrations detected by different analytical methods and is one of the first to investigate microplastic retention in soil after sludge disposal as dependent on soil characteristics.  These insights into microplastic fate in soil post-sludge disposal are crucial for enhancing environmental risk assessments and supporting the development of evidence-based policy revisions for sustainable land management.

How to cite: Phan Le, Q. N., Halsall, C., Kunaschk, M., Cao, S., Severe, E., Ashton, L., Surridge, B., and Quinton, J.: Sewage Sludge in Farmlands: A Gateway to Soil Microplastic Pollution?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12964, https://doi.org/10.5194/egusphere-egu24-12964, 2024.

Preselection of polymer characteristics has been demonstrated to streamline the recovery process in microplastic transport studies, obviating the need for extensive post-examination procedures. Nevertheless, the labor-intensive nature of microplastic extraction and identification remains a significant challenge. This study introduces a novel protocol employing fluorescent microplastic particles for expeditious identification and enumeration without the requirement for extraction, thereby contributing to the cost-effective advancement of microplastic transport research. Size fractionation was utilized to evaluate the protocol's efficacy with respect to 100–500 µm polyethylene (PE) and polylactic acid (PLA) microplastics in soil and sediment matrices, resulting in a substantial 90 to 95% reduction in sample volume post-sieving. Sample assays were conducted under controlled darkroom conditions using a 365 nm excitation wavelength UV lamp, with a digital camera set at 0.2 s, ISO200, and F5.6. Image J analysis ensured meticulous identification, quantification, and characterization of fluorescent microplastics, revealing 95% precision, a 90% F-score, and an 85% recovery rate. Application of the protocol to an agricultural plot-scale case study demonstrated its effectiveness in identifying and quantifying fluorescent microplastic particles in soil samples. This investigation, conducted on five plots (1m x 1m) subjected to rainfall simulations at an intensity of 60 mm h−1, involved the addition of 7.1 g m−2 of fine (size 125-150 µm) and coarse (size 425-500 μm) fluorescent polyethylene to the topsoil (1 cm). The results indicated a preferential erosion and transport of the microplastics. Overall, our study underscores the utility of fluorescent particles as proxies and their identification through our developed protocol as an effective means of advancing microplastic fate, transport, and deposition research in field and laboratory-scale experiments. Additionally, it highlights that agricultural land susceptible to soil erosion can constitute a significant reservoir of microplastics for aquatic ecosystems.

How to cite: Sinha Ray, S., Zumr, D., and Dostal, T.: Enhancing Microplastic Transport Research in Agricultural Soils through Fluorescent Particles: A Simplified Method for Detection and Quantification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13563, https://doi.org/10.5194/egusphere-egu24-13563, 2024.

EGU24-15173 | Orals | SSS7.7

Non-invasive detection and visualization of microplastic particles, films and fibers in sandy soils  

Christian Tötzke, Nikolay Kardjilov, and Sascha E. Oswald

The continuous input of microplastics into terrestrial environments is altering the physico-chemical properties of soils. The wide variety of microplastic particles in terms of particle shape, size, polymer type and additives makes microplastic pollution a multifaceted problem. Recent research efforts aim to improve the mechanistic understanding of how microplastics change soil structure and function and how this affects plants and other soil biota. A number of analytical detection methods are now available, but these typically involve sampling or processing steps that destroy the integrity of the sample. As a result, essential information about the soil structure and the spatial distribution of microplastics in the sample is irretrievably lost. Non-invasive tools are needed to directly study the interplay between microplastic particles and the 3D structure of the soil matrix. We introduce a combination of neutron and X-ray tomography as a non-invasive method capable of detecting and localizing microplastic particles in sandy soils (by neutrons) and simultaneously analyzing the 3D microstructure of the surrounding soil (by X-rays). The feasibility and limitations were tested in a series of sandy soil samples containing organic matter and microplastics of different plastic types and shapes, including particles, films, or fibers. Pretreatment with H2O2 was tested to facilitate the image analysis for samples with higher organic content.

Our three-dimensional imaging approach can provide detailed information about the spatial distribution of microplastics in the sample and can reproduce the size, shape, and orientation of particles, although it cannot distinguish between plastic types. Visualization of embedded polyethylene film fragments as well as fibers revealed perturbations in the soil matrix that can clearly affect its hydraulic and mechanical properties. Finally, we analyzed microplastics in the spatial context of plant-soil interactions for the root system of a lupine plant, demonstrating that it is also an attractive tool for in-situ studies of soil microplastic effects on plant roots. Overall, this approach offers the opportunity to study the impact of microplastics on soil hydromechanical properties, the interaction of biota with microplastics, and possibly also microplastics local fate in sandy soil, albeit not as a screening or high-throughput tool, but suited as powerful tool for dedicated process studies.

How to cite: Tötzke, C., Kardjilov, N., and Oswald, S. E.: Non-invasive detection and visualization of microplastic particles, films and fibers in sandy soils , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15173, https://doi.org/10.5194/egusphere-egu24-15173, 2024.

EGU24-16832 | ECS | Orals | SSS7.7

Plastic quantification and limitations in different soil types using large-volume pyrolysis and TD-GC-MS/MS 

Ryan Bartnick, Andrei Rodionov, Simon David Jakob Oster, Martin G. J. Löder, and Eva Lehndorff

It is a continuing challenge to analyze plastic in soil on an environmentally relevant level given the large variety and complexity of soil composition. Improvement of methods is required to: increase sample volume to meet soil heterogeneity, and simultaneously detect and quantify different types of plastic with high accuracy and precision independent of soil properties. A new combination of large-volume pyrolysis with thermal desorption-gas chromatography-tandem mass spectrometry (TD-GC-MS/MS) was used to detect a variety of polymer types without prior clean-up in larger (>1 g) soil samples. Characteristic MS/MS profiles for PA, PBAT, PE, PET, PLA, PMMA, PP, and PS were derived from plastic pyrolysis. Specifically developed rectangular, volume-defined reference micro-particles with respective weight (PE 0.48±0.12, PET 0.50±0.10, PS 0.31±0.08 µg), which can be directly introduced into solid samples for pyrolysis, were used as internal standards. For PE quantification in soil, we suggest a mathematical correction, PEcorrected, when analyzed without clean-up to account for organic matter contribution. In soil with organic carbon >1.5%, PE detection would require removal of organic matter. With a standard addition method, we quantified PS, PET and PEcorrected in complete soil matrices. To evaluate the reproducibility of plastic quantification for soils with different properties, sandy, clayey, oxide-rich and soils rich in organic matter were tested. We can now give recommendations for a simplified, more time-efficient quantification of various plastic types in a range of soil matrices and, hence, provide a robust base for future studies on the fate and effect of plastic in the environment.

How to cite: Bartnick, R., Rodionov, A., Oster, S. D. J., Löder, M. G. J., and Lehndorff, E.: Plastic quantification and limitations in different soil types using large-volume pyrolysis and TD-GC-MS/MS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16832, https://doi.org/10.5194/egusphere-egu24-16832, 2024.

EGU24-16962 | ECS | Orals | SSS7.7

Vertical transport of microplastics from agricultural mulching films and associated chemical additives in soil ecosystems  

Rachel Hurley, Chiara Consolaro, Sam van Loon, Aristeidis Tsagkaris, Darina Dvorakova, Lotte de Jeu, Laura J. Zantis, Cornelis A.M. van Gestel, and Luca Nizzetto

Agricultural soils receive substantial inputs of microplastic pollution from a range of different sources. The degradation and fragmentation of mulching films during and after use is expected to represent an important source of microplastic particles to soils, backed up by emerging evidence from monitoring activities. Yet, the transport and fate of these particles after they enter soil environments remains a persistent knowledge gap. This is important as soils may effectively retain these particles – resulting in increasing pollution with successive inputs – or particles may be mobilised from soils, contaminating other environments such as groundwater or surface waters. The processes that control retention versus export of particles have been poorly constrained and are expected to be complex. Chemical additives are routinely added to plastic mulching films to bestow a range of specific material properties. The extent to which these chemicals may leach out of particles in soil environments, and their potential to be transformed or mobilised in soils following release is not well known.

This study tracked the vertical transport of microplastic fragments derived from two relevant mulching films and associated chemical additives within soils: one biodegradable mulching film and one conventional plastic mulching film. The study specifically investigated the influence of factors expected to exert a control on particle/chemical fate: bioturbation and soil water inputs. The experiment was conducted in the CLIMECS (CLImatic Manipulation of ECosystem Samples) facility at Vrije Universiteit Amsterdam, which comprises 40 soil columns that simulate ecosystems – with soil, vegetation, and fauna – and are individually controlled for different environmental conditions. The two types of microplastic fragments were added to the upper layer (10 cm) of soil columns (total length: 40 cm) to represent a contaminated plough layer. Different treatments consisted of high and low microplastic concentrations, high and low watering regimes, and the presence and absence of earthworms. The columns were maintained for a period of twelve weeks. Microplastic and chemical additives content was measured in six different depths within each core at the end of the three months, to assess the extent of vertical transport. The results from this study reveal important insights on the mobility of mulching film fragments within soil systems and elucidate some of the important controls on particle movement. This provides crucial context related to the exposure of soil environments to soil microplastic and chemical additive pollution derived from mulching film use.

How to cite: Hurley, R., Consolaro, C., van Loon, S., Tsagkaris, A., Dvorakova, D., de Jeu, L., J. Zantis, L., A.M. van Gestel, C., and Nizzetto, L.: Vertical transport of microplastics from agricultural mulching films and associated chemical additives in soil ecosystems , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16962, https://doi.org/10.5194/egusphere-egu24-16962, 2024.

Mulch films are widely used in modern agriculture due to their many benefits, including extension of the growing season, control on weeds, and saving irrigation water. Biodegradable mulch films (BDMs) — films containing one or more polymer(s) that can be fully metabolically utilized by soil microorganisms to form CO2 and microbial biomass — are considered a viable substitute to conventionally used, environmentally persistent polyethylene films that accumulate in soils over time if not completely removed after harvest. The European Norm for BDMs (EN 17033:2018) stipulates laboratory incubations at 20-28°C to test biodegradation of BDMs for certification. However, to comprehend and predict the fate of BDMs in situ in field soils, it is crucial to understand how temperatures (and variations thereof in the field) affect biodegradation dynamics. Research on this subject is currently limited. In the work presented here, we systematically assess the effect of temperature on the biodegradation dynamics of three commercially available BDMs which are mainly composed of the biodegradable polyesters poly(butylene adipate-co-terephthalate) (PBAT) and polylactic acid (PLA). Laboratory soil incubations were conducted at four environmentally relevant temperatures (i.e., 5, 15, 25, and 35°C) across three different agricultural soils over a two-year period. The biodegradation extents were monitored by quantifying residual PBAT and PLA in the soils at five specific timepoints by Soxhlet extraction of the polymers from the soils combined with polymer quantification using proton nuclear magnetic resonance spectroscopy analysis (1H-NMR). The results show that the biodegradation of both PBAT and PLA is substantially affected by temperature, with a general trend of higher temperatures leading to increased biodegradation rates and extents. In the case of PLA, increasing temperature consistently increased biodegradation across all tested soils and BDMs. PBAT exhibited similar trends, except for one soil, in which the highest temperature (35°C) did not result in the highest PBAT biodegradation extents. The differences between PLA and PBAT likely reflect their distinct primary hydrolysis pathways — enzymatic hydrolysis for PBAT and abiotic hydrolysis for PLA — as well as differences in the presence and activity of polymer-specific microbial degraders between the soils. The results of modeling efforts will be presented that aim to further clarify the temperature effects on biodegradation rates and assess the extent to which these dynamics can be captured by temperature-reactivity relationships, such as the Arrhenius rate law. The results of this work will provide a basis towards predicting the effects of temperature on in situ field biodegradation rates, using laboratory incubations at temperatures of 20-28°C (as specified by the European Norm for BDMs (EN 17033:2018)) as a basis.

How to cite: Wille, F. and Sander, M.: Assessing the Effect of Temperature on the Biodegradation Dynamics of Biodegradable Mulch Films in Laboratory Soil Incubations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17809, https://doi.org/10.5194/egusphere-egu24-17809, 2024.

EGU24-18087 | ECS | Orals | SSS7.7

Earthworms transport microplastic fibres in soils 

Wiebke Mareile Heinze, Denise M. Mitrano, and Geert Cornelis

Microplastic (MP) contamination of agricultural soils is a growing concern. Synthetic textiles shed MP fibres throughout their lifecycle, which can end up in agricultural soils through the application of urban by-products as soil amendment. MP fibres can affect soil structure and have potentially adverse effects on soil organisms in high concentrations. Polyesters, such as polyethylene terephthalate (PET), are highly resistant to biodegradation and thus very persistent in soils. Understanding the fate and transport behaviour of MP fibres in soils is therefore essential for estimating long-term exposure levels and the potential effects of MP fibres on soil health. Fibres are considered less mobile in soil porewater compared to other particle shapes, but earthworms potentially displace or ingest and excrete fibres, even those within the millimetre size range. Hence, MP fibres may be prone to biologically driven transport despite their relatively large length.

We therefore investigated whether earthworm burrowing causes vertical transport of relatively large MP fibres in soil. We measured the redistribution of MP fibres in laboratory-based process-studies introducing anecic earthworms (Lumbricus terrestris) to soil columns (30 cm depth) spiked with PET MP fibres of 1.3±0.7 mm length. The MP fibres were spiked to an upper surface layer of soil and doped with a metal tracer to facilitate detection with inductively-coupled plasma mass-spectrometry after acid extraction. MP fibre transport was monitored over a total of 4 weeks in different depth segments of the soil columns. We further analyzed the size distribution of MP fibres for the different depths using a visual microscope. At the end of the experiment, MP fibres were detectable in all depth segments, highlighting the transport potential of MP fibres by larger earthworms, such as L. terrestris. We also observed that the depth-dependent decline for MP fibres was stronger in comparison to previous studies with smaller particles proposedly because these are ingested more easily. Accordingly, we expect a relative enrichment of smaller MP fibres in the deeper soil layers. We conclude that biologically driven transport may overall be influenced, but less dependent, on particle length than other transport processes such as advective transport in soil pores. In the field, MP fibres will be exposed to bioturbation processes for much longer times than in this current study, likely resulting in a successive downward transport of even larger fibres depending on the local soil conditions and earthworm activity.

How to cite: Heinze, W. M., Mitrano, D. M., and Cornelis, G.: Earthworms transport microplastic fibres in soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18087, https://doi.org/10.5194/egusphere-egu24-18087, 2024.

Transport of microplastics (MPs) in terrestrial compartments has been a growing body of research in recent years, however many of these soil models do not include the realistic role that soil organisms play in terrestrial MP movement. Here, we explore, for the first time, MP transport capabilities of multiple soil species from various ecological niches to investigate complex community structure’s interaction with MPs. Soil column mesocosms were incubated for 18 weeks with 250mg LLDPE (300-600µm) placed on soil surface and introduced were communities of naturally sourced earthworms from single and combined ecological niches (anecic, epigeic and endogeic) along with further integration of the three major ecological niches of collembola (epedaphic, hemiedaphic and euedaphic). Infiltration was performed bi-weekly to simulate intermittent rainfall events and to investigate leaching potential of microplastics through the soil columns with and without the influence of organisms. Throughout the experiment MPs were counted from leachate collected every two weeks and at the end the columns were separated into 11 layers to analyze the distribution of MPs. The presence of anecic, deep burrowing, earthworms significantly increased transport of MPs through the column into the leachate, yet there was an additive effect of leached MPs with all three types of earthworms present together and an even more so when collembola were present with anecic and all earthworms together. Thus, complex community structure increases vertical transport of MPs. At the end of the experiment significantly more MPs were still present at the soil surface of treatments with no organisms and only collembola present, treatments with earthworms present had much less MPs at soil surface and more integration of MPs in each soil layer throughout the entirety of the column. This study highlights the importance of factoring in realistic communities of soil inhabitants as a driver for intensified MP movement and needs to be considered in MP transport modeling.

How to cite: Quigley, E. and Briones, M. J.: Leaching of Soil Microplastics Through Meso- and Macrofuanal Community Transport (manuscript introduction), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18929, https://doi.org/10.5194/egusphere-egu24-18929, 2024.

EGU24-19793 | Orals | SSS7.7

Soil microbial responses to nanoplastic particles investigated in transparent soil micromodels 

Edith C. Hammer, P. Micaela Mafla-Endara, Jason Beech, and Pelle Ohlsson

Micro- and nanoplastics have become very common pollutants of soil ecosystems, yet their impact on soil microorganisms remains poorly understood. We exposed a model soil bacterium (Pseudomonas putida) and a model soil fungus (Coprinopsis cinerea) to different concentrations of nanosized polystyrene beads in microfluidic soil chips. The transparent micromodels allowed us to perform direct investigation of the effect of beads on abundance of the microbes and on interactions of individual cells with the nanobeads. Growth of both the bacteria and the fungi was reduced by the exposure to nanoplastics, along with a reduction in bacterial enzymatic activity. Nanobeads were strongly attracted to fungal hyphae, causing a high concentration of beads along the first hyphae to enter a pore space, and thus freeing the surrounding from a large proportion of the beads. We also found plastic particle accumulation along fungal hyphae in setups with soil inocula.  Chips with soil inocula also allowed us to investigate direct interactions of microbes with plastic particles, and particle aggregation under the influence of the microbe-affected soil solution over time. These studies contribute to our understanding of direct toxicity effects and interactions of nanoplastics and soil microbes.

How to cite: Hammer, E. C., Mafla-Endara, P. M., Beech, J., and Ohlsson, P.: Soil microbial responses to nanoplastic particles investigated in transparent soil micromodels, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19793, https://doi.org/10.5194/egusphere-egu24-19793, 2024.

EGU24-19927 | ECS | Posters on site | SSS7.7

The effect of soil water content on the biodegradation dynamics of polyesters from a commercial biodegradable mulch film 

Davi R. Munhoz, Flora Wille, Paula Harkes, and Michael Sander

Plastic mulch films are increasingly used in agriculture to enhance productivity by assisting in weed control, saving water, and extending the growing season. Many commercial, certified soil-biodegradable mulch films (including the film Bionov B tested herein) contain varying amounts of the two polyesters poly(butylene adipate-co-terephthalate) (PBAT) and polylactic acid (PLA). These polyesters are biodegraded by soil microorganisms as demonstrated under favorable soil incubation conditions. These biodegradable mulch films are seen as viable alternatives to the non-biodegradable conventional mulch films typically composed of low-density polyethylene (LDPE). While the tested biodegradable mulch is certified biodegradable according to the EN:17033:2018 norm, this biodegradability was tested under controlled laboratory incubation conditions with constant temperature and soil moisture. An in-depth understanding of the impact of soil moisture content and the interplay between moisture and temperature on the biodegradation dynamics of these biodegradable mulch films is still missing. In this work, we assessed the effect of soil moisture content on the biodegradation dynamics of PBAT and PLA from the tested mulch film and compared it to that of LDPE-based mulch film (negative control) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) powder as positive control. Laboratory incubations in three soils (a German standard clay soil (LUFA 6S), a Dutch silty loam soil (LOESS), and a Swiss silt clay loam soil (AGR2)) were performed over two years at 23°C at four soil moisture contents (20, 35, 50, and 65% of the soil water holding capacities (WHC)) and, in addition, at 15°C in LUFA6S at all four water contents. Biodegradation was assessed by quantifying residual PHBH, PBAT, and PLA in the soils after 6 and 12 months of incubation by Soxhlet extraction coupled to proton nuclear magnetic resonance spectroscopy analysis (1H-NMR) and, for PE, gravimetrically. PE did not biodegrade under any conditions. After six months, PHBH had extensively biodegraded in all soils at all water contents, except for LUFA6S and AGR2 at the lowest water content with much smaller extents of biodegradation. Residual amounts of both PBAT and PLA after six months were generally higher than for PHBH, demonstrating slower biodegradation of mulch film polyesters than of the positive control. PBAT and PLA exhibited very similar trends. LOESS showed a continuous decrease in biodegradation of PBAT and PLA with increasing water content; ARG2 showed the highest biodegradation at the highest water content; LUFA6S showed optimal biodegradation at intermediate water content. These findings as well as results after 12 months, clearly show that the effect of soil water content on biodegradation of PBAT and PLA is large and highly soil dependent. By comparison, lowering the temperature from 23°C to 15°C had a smaller effect on biodegradation. Ongoing efforts are directed towards linking the effects of soil moisture to soil texture. Our results provide the basis on which to assess the effect of soil water content on the biodegradation dynamics of biodegradable mulch films in field soils under in situ conditions.

How to cite: Munhoz, D. R., Wille, F., Harkes, P., and Sander, M.: The effect of soil water content on the biodegradation dynamics of polyesters from a commercial biodegradable mulch film, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19927, https://doi.org/10.5194/egusphere-egu24-19927, 2024.

EGU24-21237 | ECS | Orals | SSS7.7

The potential of participatory citizen science in observing change in plastics in soils 

Taru Sandén, Julia Miloczki, Sophia Götzinger, Philipp Hummer, Agnes Milewski, Heide Spiegel, and Mia Sol Guggiari Dworatzek

In Europe, about 50 million tons of plastic are produced per year out of which ca 40% is processed into packaging (Plastic Europe, 2022). Packaging often ends up in landfill or in the environment after only a short or single use. Unfortunately, recycling is often inadequate, contributing to only about 10% of the European demand for plastic being met by recycled plastics (Plastics Europe, 2022). Large amounts of plastic end up in the oceans, accumulating as "garbage patches" and washing up on shores. However, the amounts of plastics that end up in soils is not precisely known. Scientific studies have concluded that 4 to 32 times as much plastic ends up in soils as in water bodies (Horton et al., 2017). In addition, little is known about what types of plastics enter the soil environment, and in what proportions.

The Soil Plastic App allows citizens to input observations of visible plastics and their characteristics, with a strong focus on agricultural plastics, on soils and enable to monitor the change of plastics in soils. The App runs on the citizen science Spotteron Platform and is available for iOS, Android and as a web application. This way, observations can be entered anywhere on the globe and anytime. Since December 2022, citizens have already made over 22.000 plastic observations in the SoilPlastic App. The first set of validated Austrian citizen observations between beginning of April 2023 and end of July 2023 resulted in ca 6000 observations, as part of the Austrian Citizen Science Award Project Bunter Boden. This presentation will present the first results from Austria and discuss the potential of SoilPlastic App in observing change of plastics in soils.

How to cite: Sandén, T., Miloczki, J., Götzinger, S., Hummer, P., Milewski, A., Spiegel, H., and Guggiari Dworatzek, M. S.: The potential of participatory citizen science in observing change in plastics in soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21237, https://doi.org/10.5194/egusphere-egu24-21237, 2024.

The abundance of short-range order (SRO) iron and aluminum minerals with high phosphorus (P) binding capacity makes this essential nutrient a major limiting factor for agriculture in tropical volcanic soils. These reactive minerals also possess a significant capacity to form organo-mineral associations, thereby contributing to stabilizing soil organic carbon. Adding organic amendments can enhance P use efficiency in volcanic soils due to the competitive effect of organic ligands with P for the adsorption on the surfaces of SRO minerals. Here, using two tropical volcanic soils from Costa Rica with low (LR) and high (HR) mineral reactivity, we assessed the effect of short-term incubations with compost at various rates (0%, 5%, and 20% m/m) on the solubility of different P fractions (measured as P-Olsen and P-CaCl2). Additionally, we determined P adsorption isotherms to evaluate changes in the adsorption behavior of this nutrient. Furthermore, in a bioassay using Sorghum bicolor as a model plant, we investigated the potential influence of compost addition on the agronomic efficiency of P fertilizers in these volcanic soils.

The results of the incubation experiment showed that the addition of organic matter mostly affected the desorption of the P pool related to the capacity (Q) factor of soils (measured as P-Olsen), whereas the P intensity factor (I) (measured as P-CaCl2) remained mostly unchanged. The I factor was significantly increased only at the highest rate of compost addition in the LR soil. Description of the adsorption isotherms using the Langmuir equation revealed changes in the adsorption behavior of P due to the addition of compost. The maximum P adsorption capacity (Qmax) of the soils decreased as the amount of added organic amendment increased, particularly in the HR soil. The binding affinity of P (KL) to the mineral surfaces was also reduced due to the compost addition, and this effect was more pronounced in the HR soil. Lastly, higher agronomic efficiencies of P fertilizers were measured when compost was incubated in the HR soil, whereas in the LR soil the agronomic efficiencies of P fertilizers were unaffected by the compost addition. This study contributes to unraveling how the competitive interaction between organic ligands and P is modulated by the mineralogical properties of volcanic soils, particularly due to the reactivity of SRO minerals. Overall, our results indicate that the addition of organic amendments can be an effective alternative to improve P availability in soils with abundance of SRO minerals. From a broader perspective, adding organic amendments to soils with high P binding capacity would result in a “win-win” situation that contributes to improving the use efficiency of this limited resource while promoting the C storage in soils.

How to cite: Mendez, J. C. and Vargas, E.: Organic amendment addition distinctly influences phosphorus solubility in tropical volcanic soils with different mineralogical properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-183, https://doi.org/10.5194/egusphere-egu24-183, 2024.

The effect of a naturally occurring soil mineral, pyrite, on the degradation of 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) by Fenton process with micro scale zero-valent iron (ZVI) as the catalyst was studied in batch reactors. Our batch data show that while the CP degradation with ZVI/H2O2 system was adversely affected by the aggregation of ZVP particles, the use of pyrite in systems containing ZVI/H2O2 greatly improved the oxidative degradation of CPs. Surface measurements, including salt titration, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), revealed that the ZVI particles and surface oxidation precipitates dispersed on pyrite particles, thus preventing ZVI particle aggregation, and subsequently promoting iron redox cycling for enhanced ZVI corrosion and surface site regeneration. Following Fenton degradation, the oxidative degradation intermediate species of CPs became significantly more biodegradable relative to their mother compounds. Overall, combining ZVI and pyrite at the optimum dose might be a cost-effective technology for developing novel treatment methods for the treatment of groundwater and wastewater contaminated with chlorophenolic chemicals.

How to cite: Kantar, C., Oral, O., and Yildiz, I.: Role of pyrite on oxidative degradation of some chlorophenolic compounds with zero-valent iron/H2O2 system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-236, https://doi.org/10.5194/egusphere-egu24-236, 2024.

EGU24-1058 | ECS | Orals | SSS7.9

How should we measure clay? 

Urmi Ghosh, Ernest Afriyie, Ahmed Abd Elmola, Stephen Hillier, Jean Robertson, and Nikki Baggaley

There is an international commitment to monitor soil, as reflected in the new EU soil monitoring law on 5th July 2023.  However, direct measurements of soil properties, such as water retention, cation exchange capacity, adsorption isotherms etc. are expensive and time-consuming. Pedotransfer functions (PTFs) utilize soil properties that are easy to measure and inexpensive as predictors of these critical soil parameters. Clay content plays a crucial role in the estimation of many PTFs.  However, it is often universally estimated by particle size, which fails to capture the diversity of clay mineral types which exhibit markedly different and diverse effects on the physico-chemical behaviors of soils1, 2.  Non-clay minerals often constitute a significant portion of the clay size fractions. Furthermore, clay minerals may not disperse and instead remain in larger size fractions, further complicating the understanding of the effects of clay. The crucial question arising is: “How should we quantify clay content”? We have devised a predictive modelling framework that combines soil spectroscopy analysis, which is more widely available in soil databases worldwide, with X-ray Powder Diffraction (XRPD). This approach serves as a method for predicting the clay 'mineral' content, providing a  much more useful predictor of soil properties. The 703 soil samples from the National Soil Inventory of Scotland 2007-2009 (NSIS2)3 with both high-quality XRPD and IR spectral data are used to develop a predictive model for quantifying clay mineral content from MIR spectroscopy by correlating the spectral data to the quantitative assessment of clay minerals from XRPD (reduced using powdR package in R) using Machine Learning (ML) techniques (e.g., Cubist, Random Forest). Our current study attempts to answer two key scientific questions: 1. Can spectra data in the MIR region, combined with ML algorithms, accurately predict mineral clay concentrations generated from XRPD? 2. Which machine learning proves most effective in developing a national-scale calibration model for prediction?

 

 

References:

[1] Schmitz, R.M., Schroeder, C., Charlier, R., 2004. Chemo – mechanical interactions in clay : a correlation between clay mineralogy and Atterberg limits 26, 351–358. doi:10.1016/j.clay.2003.12.015

[2] Six, J., Conant, R.T., Paul, E.A., Paustian, K., 2002. Stabilization mechanisms of soil organic matter: Implications for C-saturation of soils. Plant Soil 241, 155–176. doi:10.1023/A:1016125726789

[3] Lilly A, Bell JS, Hudson G, Nolan AJ, Towers W. 2011. National Soil Inventory

of Scotland 2007-2009: Profile description and soil sampling protocols. (NSIS_2). Technical

Bulletin, James Hutton Institute. DOI: 10.5281/zenodo.7688040.

How to cite: Ghosh, U., Afriyie, E., Abd Elmola, A., Hillier, S., Robertson, J., and Baggaley, N.: How should we measure clay?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1058, https://doi.org/10.5194/egusphere-egu24-1058, 2024.

Formation of ferromanganese nodules (FMNs) is an important pedogenic process which is commonly observed in the Ganga alluvium. We have studied geochemistry of the host alluvium and FMNs from the eastern Uttar Pradesh, India. The FMNs were categorized in three sizes (>5.6mm, 5.6 to 2mm, and 2 to 0.5mm). The major and trace elements present in the sediments and FMNs of three size ranges were analysed using XRF and ICP-OES. The geochemical composition of the sediments and FMNs were compared with the geochemical values of the Upper Continental Crust (UCC). The enrichment factor (EF) of the analysed elements were calculated for both the host sediments and the FMNs. Additionally, the Chemical index of weathering (CIA) was calculated to quantify the extent of chemical weathering of the sediments and FMNs in the alluvium. The sediments and FMNs both showed moderate chemical weathering. We propose that the weathering of aluminosilicate stages may have given Fe, Mn, and related trace elements for the nodule formation. Prolonged dry spells and monsoonal wet seasons in the Ganga plain region may be key contributors to the weathering, mobilization, precipitation, and redistribution of the Fe and Mn phases in nodules. Certain elements, such as Pb and Cr, which are considered to be harmful to the environment got sequestered in FMNs. This helped immobilization of these contaminants. Whereas, elements like P, Co, Zn, and Cu were also got sequestered during the formation of FMNs. Therefore, it has also impacted soil nutrient availability.

How to cite: Kumar, A., Sharma, D., and Tripathi, J. K.: Elemental mobilisation and redistribution during the ferromanganese nodule formation in the sediments of Ganga plain, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2822, https://doi.org/10.5194/egusphere-egu24-2822, 2024.

EGU24-11914 | ECS | Posters on site | SSS7.9

Crystalline, poorly-crystalline and organic matter-complexed Fe and Al phases in acid and calcareous temperate forest topsoils and subsoils 

Dóra Zacháry, Christopher Zatykó, Victor G. Mihucz, Tibor Filep, Gergely Jakab, Marianna Ringer, and Zoltán Szalai

The importance of the crystalline and poorly-crystalline phases of Fe and Al in the stabilization of soil organic matter (SOM) is well studied mostly in acidic forest soils. As pH shifts from acidic to basic conditions, the effect of Fe and Al on SOM stabilization is declining. In addition, Fe and Al phases are suspected to influence SOM vertical distribution in soil profiles. Therefore, in this research the different Fe and Al phases of samples derived from acid and calcareous topsoil and subsoil layers were studied.

Topsoil (0–20 cm) and subsoil (30–50 cm) samples were collected from a silty Luvisol, a sandy Arenosol and three silty Cambisols from Hungary. All of the samples are derived from forest sites with a dominant oak vegetation. The pH of the samples is in the range of 5.4 to 8.1: five soils are acidic and five are neutral/alkaline. The organic carbon content of the soils is in the range of 0.8 to 6.64 %. Six soils have inorganic carbon content (0.03 to 3.98 %).

“Free” (crystalline and poorly-crystalline) Fe and Al compounds were extracted with dithionite–citrate–bicarbonate (FeDCB, AlDCB) solution. “Active” (poorly-crystalline) Fe and Al compounds were extracted with acid ammonium oxalate (FeOX and AlOX in case of carbonate-free soils) and sodium citrate-ascorbate (FeCA and AlCA in case of calcareous soils) solutions. For extraction of Fe and Al present in organic matter complexes, sodium-pyrophosphate (FePy and AlPy) solution was used. The Fe and Al concentration of the extracts were analyzed with ICP-MS (Thermo Scientific iCAP Q). Crystalline Fe and Al phases were calculated as FeDCB and AlDCB minus FeOX and AlOX (or FeCA and AlCA). Iron and aluminium associated with inorganic short-range order material was calculated as FeOX and AlOX (or FeCA and AlCA) minus pyrophosphate FePy and AlPy.

Results showed that Al was typically in organic matter-complexed form, whereas Fe was rather in crystalline form in all of the samples. Only the Luvisol samples with the lowest pH had highest amount of Fe and Al in short-range ordered minerals. The amount of crystalline Fe minerals was generally higher in subsoils than in topsoils, whereas, the amount of poorly-crystalline Fe and Al phases was higher in topsoils than in subsoils, regardless of the acidity of the samples. Organic matter-complexed Fe and Al phases were more abundant in topsoils than in subsoils without exception.

Correlation analysis showed significant positive relationship between total organic carbon content and the amount of “free”, “active” and organic matter-complexed Fe and Al phases of the samples studied. Clay content had a positive effect on the amount of “free” and “active” Fe and Al phases and on the amount of short-range ordered Fe minerals. In contrast, pH showed no effect on any of the Fe and Al forms.

This work was supported by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund under the NRDI - Young researchers’ excellence programme - funding scheme [project no. FK 142936].

How to cite: Zacháry, D., Zatykó, C., Mihucz, V. G., Filep, T., Jakab, G., Ringer, M., and Szalai, Z.: Crystalline, poorly-crystalline and organic matter-complexed Fe and Al phases in acid and calcareous temperate forest topsoils and subsoils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11914, https://doi.org/10.5194/egusphere-egu24-11914, 2024.

EGU24-13559 | ECS | Posters on site | SSS7.9

Interactions between soil mineral composition and particulate organic matter mediate bioavailable nitrogen  

Andrea Jilling, Marian Carrell, A. Stuart Grandy, Rachel Hestrin, Marco Keiluweit, Erik Knatvold, and Andrew Whitaker

Soil organic matter (SOM) can supply critical quantities of nitrogen (N) to plants, but fundamental questions remain regarding from what pools and by which processes plants and microbes obtain N. The source of bioavailable N is generally assigned to polymeric or particulate organic matter (POM), but in mineral soils, POM is often a minor pool of N and can be a poor predictor of bioavailable N or plant N uptake. Mounting evidence suggests mineral-associated organic matter (MAOM) is significantly more dynamic than previously assumed and may serve as an important source of N for plants and microbes. The abundance and chemical traits of POM (e.g., C/N ratio) are likely key controls on N mineralization, but bioavailable N is also regulated by the capacity for minerals to intercept, immobilize and release DON via sorption and desorption.

Our objective was to assess how the relative abundance of and chemistry of MAOM controls N bioavailability. The conceptual underpinnings for this project will be presented as will the result of an associated lab incubation. We assembled mixtures of POM and MAOM and manipulated the MAOM type and the POM:MAOM ratio to achieve varying levels of POM-N supply and mineral sorption capacity. MAOM was isolated with a particle-size based fractionation technique from four soil types that differed in mineralogical composition as determined via X-ray diffraction. Wheat residue was partially decomposed in the lab to 60% of original mass to generate POM, which was then mixed in varying ratios with a fixed amount of MAOM to achieve 5, 10, 15, and 20% of POM-N out of total soil N. Mixtures were brought to 40% of water-holding capacity and incubated for seven days. Destructive sampling occurred on days 0, 2, and 7 to assess KCl-extractable inorganic N (ammonium + nitrate), pH, and gross ammonification and nitrification rates. Greater abundance of POM-N was associated with increased inorganic N. However, when normalized to total N, we observe notable differences by MAOM type where ammonium was more bioavailable in soils with greater 2:1 clays and iron oxide minerals. We expect gross mineralization results to shed more light on how MAOM-N quantity and mineral surface properties interact with POM-N supply to control the supply of bioavailable N.

How to cite: Jilling, A., Carrell, M., Grandy, A. S., Hestrin, R., Keiluweit, M., Knatvold, E., and Whitaker, A.: Interactions between soil mineral composition and particulate organic matter mediate bioavailable nitrogen , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13559, https://doi.org/10.5194/egusphere-egu24-13559, 2024.

EGU24-15148 | Orals | SSS7.9

Using biomarker lipids to reconstruct soil fertility through time 

Cindy De Jonge, Jing jing Guo, Petter Hällberg, Marco Griepentrog, Hamdi Rifai, Andreas Richter, Edson Ramirez, Xinbao Zhang, Rienk Smittenberg, Francien Peterse, Pascal Boeckx, and Gerd Dercon

Glycerol dialkyl glycerol tetraethers (GDGTs) are ubiquitous membrane-spanning lipids with a wide environmental distribution. In soils, branched GDGTs are produced by a possibly large diversity of bacteria. The relative abundance of methyl groups attached to the central alkyl chains forms the basis of the paleotemperature proxy MBT’5ME. However, MBT’5ME values in soils can also be directly influenced by pH (De Jonge et al., 2021). A second group of compounds, the isoprenoid GDGTs, are produced by archaea. They have been used only sparsely as environmental proxies in soils, although they are at the base of the marine paleotemperature proxy TEX86. In soils, a compilation by Yang et al. (2016) illustrates that the temperature dependency of TEX86 is sometimes present, but potentially influenced by other soil (chemistry) parameters.

In addition to temperature, other soil parameters are expected to vary with time, even on a Holocene timescale. For instance, soil mineral fertility (specifically, the concentration of exchangeable cations) will vary following ongoing soil formation influenced by climate, vegetation and/or land use changes. As soil mineral fertility will impact the soil nutrient status for vegetation and impact the soil capacity to store organic carbon (von Fromm et al., 2021), it is a relevant parameter to reconstruct over time. However, as soil fertility of surface soils will decrease during erosion or burial, this parameter can currently not be reconstructed quantitatively.

To investigate the potential of GDGTs as soil fertility proxies, branched and isoprenoid GDGTs were measured in soils from 5 elevation transects (Austria, Bolivia, China, Indonesia and Tanzania; De Jonge et al., 2024) that cover a large gradient in mean annual temperature (0-28 ℃), seasonality, and soil chemical parameters. Supplemented with temperature and precipitation data, we evaluate both changes in absolute concentration and relative distribution of the GDGTs. Of the chemical parameters, exchangeable calcium and exchangeable iron are shown to correlate with the absolute abundance of several branched (6 methyl brGDGTs) and isoprenoid (crenarchaeol isomer) GDGT compounds. Based on these relations we have developed ratios as proxies for calcium (and summed bases) and iron (and summed metals) [r2=0.61-0.68, p<0.001] concentrations using GDGTs in soils. As GDGTs are preserved after burial, their presence in paleosol sequences allow reconstruction of ancient topsoil fertility (specifically, calcium and iron) through time, even after the mineralogy of the original topsoil has changed upon further weathering.

De Jonge, C. et al. The influence of soil chemistry on branched tetraether lipids in mid- and high latitude soils: implications for brGDGT- based paleothermometry. Geochimica et Cosmochimica Acta (2021).

De Jonge, C. et al. The impact of soil chemistry, moisture and temperature on branched and isoprenoid GDGTs in soils: A study using six globally distributed elevation transects. Organic Geochemistry 187, 104706 (2024).

von Fromm, S.F., et al. Continental-scale controls on soil organic carbon across sub-Saharan Africa. SOIL 7, 305–332 (2021).

Yang, H., Pancost, R. D., Jia, C. & Xie, S. The Response of Archaeal Tetraether Membrane Lipids in Surface Soils to Temperature: A Potential Paleothermometer in Paleosols. Geomicrobiology Journal 33, 98–109 (2016).

How to cite: De Jonge, C., Guo, J. J., Hällberg, P., Griepentrog, M., Rifai, H., Richter, A., Ramirez, E., Zhang, X., Smittenberg, R., Peterse, F., Boeckx, P., and Dercon, G.: Using biomarker lipids to reconstruct soil fertility through time, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15148, https://doi.org/10.5194/egusphere-egu24-15148, 2024.

EGU24-16386 | ECS | Posters on site | SSS7.9

Li and Mg adsorption onto soil phyllosilicates and oxides 

Jean-Michel Brazier, Anna L. Harrison, and Vasileios Mavromatis

Continental silicate weathering is of great importance for global climate regulation as it represents one the most important atmospheric CO2 removal mechanism over long timescales. In this regard, many geochemical tools have been developed over the last decades to trace and quantify continental weathering, and amongst them lithium and magnesium isotopes are considered as robust proxies that provide complementary information. For example, lithium isotopes (i.e., δ7Li) are robust weathering tracers due to the narrow range of δ7Li values of the silicate continental primary rocks compared to the isotope fractionation generated by weathering processes and subsequent secondary mineral formation (e.g., clays, oxides) affecting the isotope composition of the rivers reaching the oceans (e.g., Pogge von Strandmann et al., 2012). Magnesium isotopes (i.e., δ26Mg) are also robust proxies because δ26Mg composition of silicates are rather homogeneous and significantly different from secondary carbonates. Therefore, δ26Mg values of rivers can provide information on the silicate/carbonate ratio of the altered source rock, in addition to being affected by secondary mineral formation (e.g., Tipper et al., 2006, 2008). Beyond this secondary mineral formation, the effects of many interactions occurring within the critical zone on the isotope fractionation of Li and Mg remain poorly constrained. Amongst these interactions, adsorption onto silicate minerals and oxides is one of the most important elemental retention mechanisms within soils and is controlled by numerous environmental parameters (e.g., pH, elemental concentration in the soil solution, solid-solution ratio). Adsorption often generates isotope fractionation, therefore influencing the isotope budget of river waters. The aim of this study is first to explore the adsorption behaviour of Li and Mg on commonly encountered minerals within soil environments (smectite, chlorite, vernadite, gibbsite, and ferrihydrite), and second to determine the isotope fractionation generated during adsorption. Adsorption experiments were performed in batch reactors over a large range of pH and initial cation concentration providing new insights on the dependence of Li and Mg adsorption on (i) the mineralogy, and (ii) solution composition (e.g., pH-dependent speciation). These results will provide insights into the processes controlling Li and Mg mobility and isotope fractionation in soils, and their ultimate release into rivers.

 

Tipper, E. T., Galy, A., & Bickle, M. J. (2006). Riverine evidence for a fractionated reservoir of Ca and Mg on the continents: implications for the oceanic Ca cycle. Earth and Planetary Science Letters, 247(3-4), 267-279.

Tipper, E. T., Galy, A., & Bickle, M. J. (2008). Calcium and magnesium isotope systematics in rivers draining the Himalaya-Tibetan-Plateau region: Lithological or fractionation control? Geochimica et Cosmochimica Acta, 72(4), 1057-1075.

Pogge von Strandmann, P. A., Opfergelt, S., Lai, Y. J., Sigfússon, B., Gislason, S. R., & Burton, K. W. (2012). Lithium, magnesium and silicon isotope behaviour accompanying weathering in a basaltic soil and pore water profile in Iceland. Earth and Planetary Science Letters, 339, 11-23.

How to cite: Brazier, J.-M., Harrison, A. L., and Mavromatis, V.: Li and Mg adsorption onto soil phyllosilicates and oxides, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16386, https://doi.org/10.5194/egusphere-egu24-16386, 2024.

Fluorine, in the form of fluoride, is a minor but ubiquitous element found in magmas. It is released into the environment during volcanic degassing and exists as various salts on the surfaces of ash particles. Fluoride is also liberated during the weathering of magmatic rocks. The presence of fluoride in surface/ground waters and soils can pose a health hazard to humans and livestock. Additionally, fluoride enhances the dissolution of aluminosilicates during water-rock interaction. However, fluoride interacts strongly with iron (oxy)hydroxides (notably, ferrihydrite) and allophanes, secondary poorly crystallised minerals commonly found in volcanic soils. In volcanic regions, these reactions limit the mobility of fluoride significantly while causing its accumulation in the soil. We lack a quantitative description of the factors that control fluoride adsorption in volcanic soils, which hinders a comprehensive assessment of the geochemical behaviour of fluoride in these environments. Here we measured the fluoride adsorption envelopes (pH 2.8–7) of Icelandic volcanic soils with different weathering degrees and organic matter contents. The experiments were performed with a 1.3 mmol l-1 NaF solution and using pH-stat titration. The minimum and maximum fluoride adsorption typically occurs at pH of 2.8 and ≥6, respectively, reflecting the combined influence of pH and soil anion exchange capacity (AEC). At pH <6, fluoride forms positively charged alumino-fluoride complexes (AlFx(3-x)). Since the AEC of allophanes (point of zero charge, PZC = 6) and ferrihydrite (PZC = 6.5) increases with solution acidity, adsorption of AlFx(3-x) becomes restricted at lower pH values. At higher pH, the fluoride ion (F-) predominates in solution, but its adsorption is limited as the AEC decreases. More weathered soils, characterised by higher allophanes+ferrihydrite content, exhibit a greater capacity to adsorb fluoride. However, we also emphasise the role of organo-aluminium/iron complexes in reacting with fluoride. Based on the results of our adsorption/desorption experiments, we have developed a constant capacitance model to predict fluoride adsorption in volcanic soils.

How to cite: Denis, A., Saldi, G., and Delmelle, P.: Differential influence of solution pH on the adsorption of fluoride in Icelandic volcanic soils varying in weathering degree and organic matter content, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18076, https://doi.org/10.5194/egusphere-egu24-18076, 2024.

EGU24-20847 | ECS | Orals | SSS7.9

The spatial distribution of Zn and Cd across the soil microscale architecture as mediated by different mineral phases in a supplemented arable soil 

Steffen A. Schweizer, Jill Bachelder, Carmen Hoeschen, Emmanuel Frossard, and Matthias Wiggenhauser

Zinc (Zn) is an essential trace element for human nutrition as well as for plant growth and soil organisms. Cadmium has similar biogeochemical properties like Zn, but is non-essential for most biota and highly toxic. Due to the on the heterogeneous arrangement of soil mineral phases and organic compounds within a functional soil architecture, there is a lack of knowledge on how the microscale arrangement is interrelated with ecosystem-relevant soil functions such as the storage and cycling of nutrients and contaminants. Here, we present an analytical approach aiming to resolve the spatial distribution of Zn and Cd in a soil at the microscale. Zn and Cd were supplemented in three increasing concentrations to an arable soil from the Jura region, Switzerland. Our image-based investigation was obtained using a dual primary ion source workflow by Nanoscale secondary ion mass spectrometry (NanoSIMS) combining the Cs+ and the RF plasma O source. The dual workflow enabled correlating the distribution of Zn and Cd with Fe, Al, Si, P, Mg, Ca, S, C and N at a lateral resolution of 120nm. Our observations indicate a high co-localization of Zn and Cd hotspots, whereas these were not related with organic matter patches. Of the three mineral phases identified using a machine-learning image segmentation, most areas were occupied by Al-dominated regions followed by Si-dominated and Fe-dominated parts. Across the increasing supplementation, the Zn and Cd hotspots were preferably co-localized to mineral phases in the following order: Fe-dominated > Al-dominated > Si-dominated. With increasing Zn and Cd supplementation, the Cd/Zn ratio as well as the N/C ratio decreased indicating changes in the biochemical composition of . Our model soil approach illustrates how the spatial arrangement of essential and toxic trace elements at the microscale regulates their fate in the soil. The developed NanoSIMS-based dual primary ion source workflow enables emerging opportunities to characterize how environmental changes affect the spatial distribution of nutrients and contaminants in dynamic soil architectures.

How to cite: Schweizer, S. A., Bachelder, J., Hoeschen, C., Frossard, E., and Wiggenhauser, M.: The spatial distribution of Zn and Cd across the soil microscale architecture as mediated by different mineral phases in a supplemented arable soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20847, https://doi.org/10.5194/egusphere-egu24-20847, 2024.

EGU24-21838 | Orals | SSS7.9

The effect of soil mineral composition on K availability to plants 

Shikma Zaarur and Ran Erel

Potassium (K) is an essential macronutrient that takes part in a wide variety of processes in the plant,
from enzymatic activity to cell development and osmotic balance. Excess K has a minor effect on the plant,
mostly due to imbalanced nutrition. Accurately determining K requirements for optimal growth and high
fertilizer utilization efficiency is therefore challenging, and often results in excess fertilizer application. It
is customary to refer to four soil K reservoirs which vary greatly in their size and availability to the plant:
(1) soil solution is the smallest and the one from which plants uptake K, (2) exchangeable - K adsorbed
onto clay mineral surfaces, oxides and organic matter (1-2%), (3) interlayer - K fixed between clay mineral
sheets (up to 10%), and (4) structural K – most commonly found in K-feldspar and usually considered
unavailable to the plant (90-98%). The interlayered - K is a dynamic and important pool that may supply
K for the plant in case of K deficiency, or act as a sink by fixing excess K.
Fertilization recommendations often relay on soil tests that estimate the exchangeable-K pool. The
common paradigm is that exchangeable K represents the capacity of the soil to supply plant-available-K.
In alkaline soils, however, there is a growing number of studies from both short- and long-term experiments
(several growth seasons to a few decades), reporting little to no response to K fertilization, indicating that
the soils supply greater amounts of K than indicated the exchangeable K tests. These findings evoke
questions regarding the intrinsic soil K reservoirs and the extent to which the natural supply of K to the
soils from weathering or dust deposition, readily supply K to plants.
In this study, we examine the affect of different K-bearing mineral phases (soil K pools) on the soil K
cycle and K availability to the plant. Our study focusses on intensively used agricultural soils in Israel that
vary in their clay compositions- illite and illite-smectite and K-feldspar. We think that illite and illite-
smectite are instrumental in buffering the excess K fertilizer that we observe in short- and long-term
experimental plots. Over time, we suggest, that agriculturally driven enhanced weathering of the illite and
K-feldspar releases significant amounts of K, that had been previously considered unavailable. Taking into
consideration the abundance of these mineral phases in the regional dust, we further suggest that dust
deposition and location along the regional dust gradient play a significant role in replenishing and
maintaining soil K levels.

How to cite: Zaarur, S. and Erel, R.: The effect of soil mineral composition on K availability to plants, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21838, https://doi.org/10.5194/egusphere-egu24-21838, 2024.

Disturbance is an important factor in controlling vegetation diversity, and distribution of trace metals in the environment, including through their mobilization by disturbance-induced runoff and related to movement of soil particles. Disturbance-induced access of these trace metals into the ecosystem is toxic for soil contamination and experiences varying degrees of ecological implications in different ecosystems. The present study aimed to evaluate the impact of different degrees of land disturbances on the changes in vegetation diversity, soil characteristics, and trace metals in the Himalayan forest ecosystem, which is limitedly documented. Forest sites were categorized into four distinct disturbance classes based on disturbance index score (DI): no disturbance (ND, DI ≤ 5 %), low disturbance (LD, 5 < DI ≤ 20 %), moderate disturbance (MD, 20 < DI ≤ 50 %), and high disturbance (HD, DI > 50 %). Data comprised trace metals, and soil physicochemical characteristics across the distinct disturbance classes and soil layers (0-15 and 15-30 cm). Using two-way ANOVA, vegetation attributes (diversity (H′), and tree density), soil properties, and trace metals were tested for their effects, including interactions among different disturbances and depths. Multivariate correlation was used to investigate the relationship between disturbance classes, depths, soil characteristics, and trace metals. The important findings of the study are the following: (1) The recruitment of new trees (Treerecru.), diversity, and soil organic carbon (Corg) were significantly varied across the disturbance classes (p< 0.05) and followed the order: MD > HD > LD > ND; (2) Average concentration metals were significantly distributed along disturbances gradient HD > LD > MD > ND in the order: B > Mn > Pb > Cu > Ni in distinct soil layer. (3) Contamination factor of trace metals in order B > Mn > Pb > Ni > Co > Cu in 0-15 and 15-30 cm soil depths. (4) Persistent ecological risk index (PERI) was higher for HD sites and lowest for ND sites. The result illustrated that moderate disturbance increases diversity and soil nutrients. The study highlighted the important role of disturbance in regulating the trace elements in association with changes above-below ground interaction, suggesting HD sites as a potential source of environmental contamination.

How to cite: Shankar, A. and Garkoti, S. C.: Trace metals interaction to soil properties, and their ecological risk assessment in different disturbance regimes of sal forests of the western Himalaya, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-826, https://doi.org/10.5194/egusphere-egu24-826, 2024.

EGU24-1652 | Posters on site | SSS7.13

Health Risk Assessment For Soil From The İzmir City Center, Western Türkiye 

Atilla Kılıç and Fatma Toksoy Köksal

The geochemical characteristics of soil horizons and specific rock types in the vicinity of Izmir city center were studied for interpretation to see the possible health risk associated with geogenic control. The purpose of this study was to interpret and assess the potential health risks associated with geogenic control. A total of 140 samples, consisting of 60 soil sites representing various soil horizons and 48 rock sites located in the İzmir city center, were collected for geochemical analysis using the ICP-MS method. The presence of potentially toxic elements (PTE) including As, Ba, Be, Cd, Co, Pb, Mo, Ni, Sb, Se, Sn, and Zn were identified, posing potential health risks. Therefore, the values of contamination factor (CF), geo-accumulation index (Igeo), pollution load index (PLI), as well as health risk factors for adults and children (carcinogenic risk and hazard index) are computed.

The risk factor findings demonstrate that certain areas in the city center of İzmir pose carcinogenic and noncarcinogenic health risks to various segments of the population, encompassing both children and adults. For children, the median HI value is 0.95 (lower than unity) and the mean value is 2.02 (greater than unity). The median carcinogenic risk value for children exceeds the risk threshold of 10-4, measuring at 2.06x10-4, while the mean carcinogenic risk value stands at 7.32x10-4. Elemental contributions for hazard index are mainly caused by As, Co, Pb and Sb, for risk As, Be and Ni and Pb.

The correlation between the source of PTE in soil levels and the geochemical results of rock samples from the city center suggests a potential link between contamination and geogenic effects.

 

Keywords: Medical geology, health risk, toxic elements, arsenic enrichment, Western Anatolia.

How to cite: Kılıç, A. and Toksoy Köksal, F.: Health Risk Assessment For Soil From The İzmir City Center, Western Türkiye, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1652, https://doi.org/10.5194/egusphere-egu24-1652, 2024.

EGU24-2566 | Posters on site | SSS7.13

Assessing the Ecotoxicological Risks of Heavy Metals in Contaminated Sites Using the Life Cycle Impact Assessment Method 

Seung-Woo Jeong, Prakash Gautam, Songhee Kim, Youn-Joo An, Seunghun Hyun, and Sunhee Hong

Heavy metal pollution has a detrimental impact on both the ecosystem and human health. In order to accurately assess the risk of contamination at a site, it is necessary to conduct sampling and ecological investigations on site, followed by laboratory analysis of contamination concentrations and toxicity. This process also requires the use of various experimental equipment and materials for ecological risk assessment. This study proposes a method for assessing ecological risks at metal-contaminated sites using life cycle impact assessment (LCIA) approaches. LCIA quantifies environmental impacts by multiplying mass-environmental loads with impact characterization factors (CF). This study aimed to develop exposure and effect factors in order to obtain site-specific CFs for metal soil contamination. The ecological risks at two mine sites were then estimated solely based on soil metal concentrations. These estimated risks were compared between sites and with detailed ecological risk results obtained using the TRIAD method. The estimated results were found to be in good agreement with the actual experimental results. This method has the potential to save time, resources, and effort in assessing the ecological risks of metal-contaminated sites. (This work was supported by the Korea Environmental Industry and Technology Institute (KEITI) funded by the Korea Ministry of Environment (No. 2022002450002)).

How to cite: Jeong, S.-W., Gautam, P., Kim, S., An, Y.-J., Hyun, S., and Hong, S.: Assessing the Ecotoxicological Risks of Heavy Metals in Contaminated Sites Using the Life Cycle Impact Assessment Method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2566, https://doi.org/10.5194/egusphere-egu24-2566, 2024.

EGU24-4109 | Posters on site | SSS7.13

Pb Isotopic Compositions of Soils and the Impact of Heavy Metal Smelters in Urbanized Industrial Settings, East Los Angeles, California, U.S.A.  

Robert Ayuso, Nora Foley, Jill Johnston, Rani Indela, John Jackson, and Damon Bickerstaff

Lead isotopes of soil profiles were measured to survey possible sources of lead. Thirty-seven soil profiles (n > 150 samples) were obtained near two lead battery recycling smelters: Exide (recently shutdown) and Quemetco/Ecobat (currently in operation) affecting thousands of residential sites. Preliminary soil Pb isotopic compositions plot as a band in Pb isotope space from radiogenic values typical of rock-derived lead to lower values that likely indicate anthropogenic lead. Three overlapping soil groups were established based on Pb isotope analysis by TIMS (Thermal Ionization Mass Spectrometry). Group 1 consists mainly of soils near the Exide smelter and nearby residential sites. Group 1 has low isotopic values with moderate variations in 206Pb/207Pb ~1.167–1.176, 208Pb/207Pb ~ 2.432–2.438, 206Pb/204Pb ~18.24–18.344. Group 2 has more radiogenic values than Group 1: 206Pb/207Pb ~1.178–1.190, 208Pb/207Pb ~2.439–2.443, 206Pb/204Pb ~18.34–18.56 and consists mostly of residential soils surrounding the Exide smelter. Group 3 is more radiogenic than Groups 1 and 2: 206Pb/207Pb >~1.190, 208Pb/207Pb >~2.443, 206Pb/204Pb >~18.56. Soils near the Quemetco facility have similar variations and overlap the three groups.  About 80% of the Pb isotopes in leached soils near Exide have Pb compositions that match those of the smelters. Group 2 has up to about 67% Pb resembling the Exide smelter output and Group 3 yields up to about 18% matching Pb. Sites near Quemetco contained up to about 86% Pb isotopically similar to the Exide signature. Sites containing lead that isotopically matches soils near the Exide smelter are interpreted as contaminated by human activities. Smelter isotopic signatures are found as deep as 30 cm in the soil profiles.  Our results demonstrate the need for establishing baselines and background concentrations of lead (and other metals such as As, Cd, Zn, Sb, and Cu) and Pb isotopic compositions of soils, waters, and air before smelters and other industrial facilities are in operation (which are commonly located in disadvantaged communities, for example in East Los Angeles), and especially during property transitions. Elemental and isotopic data can be used to assess legal liability and assist local, State, and national agencies for effective cleanup and proper remediation.

How to cite: Ayuso, R., Foley, N., Johnston, J., Indela, R., Jackson, J., and Bickerstaff, D.: Pb Isotopic Compositions of Soils and the Impact of Heavy Metal Smelters in Urbanized Industrial Settings, East Los Angeles, California, U.S.A. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4109, https://doi.org/10.5194/egusphere-egu24-4109, 2024.

EGU24-4585 | Posters on site | SSS7.13

Spatial distribution and health risk assessment of heavy metals pollution in soil within Agricultural and industrial areas in the Eastern Province, Saudi Arabia 

Mohamed Yassin, Zaher Mundher Yaseen, Bassam Tawabini, Sani Abba, Syed Muzzamil Hussain Shah, Bijay Halder, and Isam Aljundi

This study aimed to explore the level of heavy metal contamination in the soil of agricultural and industrial areas in the Eastern Province of Saudi Arabia. It adopted a novel approach integrating multiple disciplines including sampling, laboratory analysis, spatial analysis, and risk evaluation. The research focused on pinpointing levels of contamination, identifying their sources, and evaluating associated ecological and human health hazards. Due to its varied agricultural and industrial activities, the Eastern Province faced potential environmental challenges linked to heavy metal pollution. This study tackled the essential task of understanding the spatial spread and associated risks of heavy metals in soil, offering insights critical for effective environmental management and policymaking. Over 60 soil samples were gathered from different industrial and agricultural sites. Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP-OES) was employed for the analysis of various heavy metals in these samples. The soil samples underwent evaluation for heavy metal presence, with their pollution levels assessed through indicators such as the heavy metal pollution index (HPI), heavy metal evaluation index (HEI), modified heavy metal index (MHMI), and degree of contamination (Cdeg). Experimental findings revealed average concentrations of heavy metals in mg/Kg for As, Ba, Hg, Pb, Ni, V, Cd, Cr, Cu, and Zn are 1.21, 110.62, 0.08, 6.34, 8.95, 9.98, 1.18, 31.79, 6.76, and 23.44 respectively. A general trend emerged in the concentration levels, with the highest averages observed in samples from industrial areas, followed by agricultural sites. Particularly notable were barium concentrations in the industrial area, peaking at 1966.5 mg/kg, and copper levels, with a maximum of 95.75 mg/kg in the same area, occasionally surpassing the permissible limits. This methodology provided crucial insights for enhancing water environment management and protection, addressing the urgent need for effective environmental governance and policy development. The findings from this project are not only relevant to the Eastern Province but also applicable to other regions experiencing similar soil contamination challenges.

How to cite: Yassin, M., Mundher Yaseen, Z., Tawabini, B., Abba, S., Muzzamil Hussain Shah, S., Halder, B., and Aljundi, I.: Spatial distribution and health risk assessment of heavy metals pollution in soil within Agricultural and industrial areas in the Eastern Province, Saudi Arabia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4585, https://doi.org/10.5194/egusphere-egu24-4585, 2024.

EGU24-5273 | Posters on site | SSS7.13

Sealing impacts soil properties and the soil microbial community in urban areas 

Carly Stevens, Marlon Correa Pereira, Raj Whitlock, Roisin O’Riordan, Leandro Israel da Silva, and Angeliki Kourmouli

Urbanisation inevitably alters the chemical, physical and biological soil properties. Consequently, it modifies environmental soil services. The sealing of soil – covering the soil surface with non-biological structures - has gained attention in urban area in relation to flooding, loss of soil carbon, loss of soil function and other problems, which can be mitigated introducing greenspaces in urban areas. To understand the impact of sealing and greenspaces on the urban soil properties, soil beneath three pavement types (concrete, slab and tarmac) and from paired unsealed areas (representing four cover types – bare soil, grass, shrub and tree) were sampled in forty sites in Lancaster, UK to access chemical [pH, total carbon (C), total nitrogen (N), C/N ratio], physical [moisture] and microbiological [microbial biomass (MB), 16S rDNA metabarcoding data metrics] parameters. Sealed soils had lower moisture, C, N and MB, and higher pH than unsealed soils. C/N ratio had no significative difference. Changes in chemical and physical soil parameter affected the bacterial diversity indexes (richness, Shannon, Simpson and α parameter of Fisher’s log series), which were significantly lower in sealed areas as well. NMDS analysis showed high variability in the bacterial community of sealed soil, but lower variability in unsealed soil. The sum of sequences of gram positive, gram negative, oligotrophic and copiotrophic bacteria, as well gram positive:gram negative  ratio (GP:GN), were lower in sealed soil. The reduced GP:GN ratio on sealed soil suggests low-quality organic matter and the impact of low moisture and N on bacterial community. Pavement type had no effect on sealed soil parameters. However, the cover type significantly changed GP:GN and copiotrophic:oligotrophic ratio on unsealed soil, indicating that soil in grassland may have higher resource availability (C and N) and microbial growth rates than shrub and trees. Our results reinforce that the sealing, unrelated to pavement type, has a negative impact on soil properties and deplete microbial diversity. Cover type may affect resources availability on unsealed soil. These changes can affect microbial processes related to biogeochemical cycles, impacting the carbon store and the potential for nutrient cycling in urban soils.

How to cite: Stevens, C., Correa Pereira, M., Whitlock, R., O’Riordan, R., Israel da Silva, L., and Kourmouli, A.: Sealing impacts soil properties and the soil microbial community in urban areas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5273, https://doi.org/10.5194/egusphere-egu24-5273, 2024.

EGU24-6326 | ECS | Orals | SSS7.13

Mercury Speciation in Soils and Its Influence on Bioaccumulation in Crops at a 33-Year-Old Solid Waste Dumping Site 

Arup Dey, Parthasarathi Chakraborty, and Prasad Padalkar

Mercury (Hg) pollution garnered global attention after the Minamata disaster. The complex biogeochemical processes governing soil Hg distribution, speciation, and its accumulation in crops have remained elusive. This study investigates the soil Hg distribution, speciation, and bioaccumulation in crops at Dhapa, a 33-year-old solid waste dumping station of the Kolkata Municipal Corporation. Vegetable cultivation in this 35-hectare area rely on industrial wastewater of the city for irrigation, and these sewage-irrigated vegetables find their way into markets across the Kolkata suburbs. Whole plant of vegetable crops and paired soil samples were collected from 92 locations in the study area. The findings unveiled a wide range of soil total Hg (THg) concentrations, spanning from 48 ± 2.4 to 8108 ± 405.4 µg/kg, with an average of 1697 µg/kg. 45% of the total samples surpassed the Maximum Permissible Concentration of Hg in agricultural soil (1500 µg/kg), and 91% exceeded the background concentration of world soils (400 µg/kg), indicating significant ecological risks. The chemical speciation study revealed that soil organic matter (SOM) was the dominant hosting phase for Hg in the studied soil. According to relative abundance, the different species could be arranged as follows: Hg bound to SOM> elemental Hg > Hg bound to sulphides > Hg bound to reducing binding phase > residual fraction of Hg. High elemental Hg contents (average: 21.86 ± 1.1% of THg) underscore prominent Hg (II) reduction in the soils. Among edible parts of the vegetables examined, the highest accumulation was observed in leafy vegetables. The edible parts, as per the bioaccumulation factor (Hg concentration in edible part / soil THg), could be sorted as Cauliflower < Bottlegourd < Malabar spinach (Poi) < Ipomea< Brinjal < Radish (root) < Amaranthus< Spinach. According to Polish, Serbian, and Chinese regulations, all vegetable crops (besides Cauliflower) exceeded the maximum tolerable limit (300 µg/kg). SOM-bound was identified as the chemical form of Hg primarily responsible for its root uptake. Interestingly, shoot Hg contents were significantly correlated to soil elemental Hg contents, which implies that soil Hg evasion contributes to Hg uptake in plant shoots. The findings of this study suggest that high organic matter input in polluted soils could enhance the phytoaccumulation of Hg. The outcomes of this study will contribute to assisting policymakers in minimizing human exposure to mercury (Hg) by providing comprehensive guidelines on vegetable intake from this area. Additionally, the study's results will be valuable for farmers, helping them select crops that demonstrate low uptake of mercury.

How to cite: Dey, A., Chakraborty, P., and Padalkar, P.: Mercury Speciation in Soils and Its Influence on Bioaccumulation in Crops at a 33-Year-Old Solid Waste Dumping Site, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6326, https://doi.org/10.5194/egusphere-egu24-6326, 2024.

EGU24-7298 | Posters on site | SSS7.13

Increase in anthropogenic mercury pollution over the past centuries in Northeast China as reconstructed from multi-lake sediment cores 

Bigyan Neupane, Kunshan Bao, Minqi Chen, Poonam Thapa, and Michael E. Meadows

The rise in human activities in northeast (NE) China has resulted in increased emissions of environmental pollutants. Their measurement is crucial to evaluate the extent and timing of the longer-term anthropogenic environmental changes. This study presents the measurement of mercury (Hg) concentration and accumulation rate in 11 lake sediment cores from Songnen Plain in NE China to reconstruct the historical deposition of Hg as an indicator of the changing scale of anthropogenic activities. The results demonstrate an increasing trend of Hg concentration, concurrent with the increased anthropogenic emission, beginning from the early 1900s, accelerating through the mid-1950s and slightly decreasing from the late 1990s up-core. The anthropogenic Hg increase coincides with New China's foundation, precipitating social and economic reforms and rapid industrial and economic growth. Measurements of the Hg enrichment factor in all the cores point out anthropogenic contribution to Hg accumulation, and the geoaccumulation index shows the lakes are generally moderately polluted by Hg. The historical trend of the Hg accumulation rate matches the region's temporal progression of biomass burning and fossil fuel consumption. The findings elucidate the extent of anthropogenic pollution in the Anthropocene and underline the importance of identifying Hg sources to reduce emissions and implementation of effective mitigation strategies.

How to cite: Neupane, B., Bao, K., Chen, M., Thapa, P., and Meadows, M. E.: Increase in anthropogenic mercury pollution over the past centuries in Northeast China as reconstructed from multi-lake sediment cores, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7298, https://doi.org/10.5194/egusphere-egu24-7298, 2024.

EGU24-9103 | Orals | SSS7.13

Assessing the Long-Term Leaching Behavior of Cadmium and Zinc in Soil Beneath a Smelter Site 

Juyong Bak, Chaeyoung Kim, Hosub Lee, Yongju Choi, and Kyoungphile Nam

In this study, we investigate the leaching behavior of heavy metals from soils beneath a smelter plant, with a focus on their migration to groundwater. Sequential extraction methods and traditional batch tests (e.g., SPLP, TCLP) often inadequately represent real-world leaching scenarios. We addressed this gap by conducting column experiments simulating long-term exposure to synthetic rainwater on soils heavily contaminated with cadmium (Cd) and zinc (Zn). Soil samples were collected from ten random points at each of the two distinct sites, showing varied contamination levels (Site A: Cd: 546 mg/kg, Zn: 28,597 mg/kg; Site B: Cd: 82.3 mg/kg, Zn: 5,582 mg/kg). We predicted 30-years cumulative elution (I30yr) of Cd and Zn, extrapolating concentration and the rate parameters determined by column experiments with an accumulated liquid-solid ratio of 10 to a leaching model described in RIVM report (report no. 771402007). The results indicated a broad range of I30yr values both within and between sites (Cd: 10 - 458,274 mg/m²; Zn: 170 - 2,225,537 mg/m²), suggesting heterogeneous leaching behavior. Statistical analyses revealed that I30yr values did not correlate with the total metal concentration in soils, while exhibiting a weak correlation with the exchangeable fraction from sequential extractions. However, I30yr were strongly correlated with SPLP leachate concentrations, and the degree of correlation was higher in the subsoil than in the topsoil (Cd: r=0.867, p=0.001; Zn: r=0.990, p<0.001). Our results confirm the high correlation between metal leaching behaviors determined by column experiments and batch SPLP extraction, and emphasize that the stabilizing Cd and Zn in soils under the smelter is crucial for preserving groundwater quality.

How to cite: Bak, J., Kim, C., Lee, H., Choi, Y., and Nam, K.: Assessing the Long-Term Leaching Behavior of Cadmium and Zinc in Soil Beneath a Smelter Site, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9103, https://doi.org/10.5194/egusphere-egu24-9103, 2024.

EGU24-9115 | Posters on site | SSS7.13

Plant functional type and species determine elemental concentrations in boreal mire vegetation 

Sari Peura, Peter Saetre, Betty Ehnvall, Mats B. Nilsson, and Mats G. Öquist

Uptake of radionuclides into plants is a key process in radioecological modelling.  Typically, the uptake is incorporated into these models and in environmental impact assessments using an empirical soil-to-plant transfer factor (CR). The elemental concentration in plants is expected to vary with plant species and plant functional type (PFT), but also with soil concentration and elemental properties. Specifically, elements subject to regulated plant uptake (i.e. essential elements) are expected to be less related to soil concentrations than non-essential elements with no or limited biological function. Environmental conditions may also influence the CR value, and for assessment purposes, differential values are commonly listed for different soil types. In this study, we have addressed the impact of PFT and species as well as environmental factors to the CR of four peatland species (Andromeda polifolia, Vaccinium oxycoccus, Eriophorum vaginatum and Carex rostrata) representing two different PFTs (heathers and sedges).

The results show that while plant species and PFT are the most important factors determining the CR value, environmental factors, such as pH and peat depth, also modify the CR. As expected, plant concentrations of essential elements were only weakly related to soil concentrations, whereas the correlation between soil and plants was stronger for non-essential elements.

Based on our results, we verify that CR values may vary substantially between species and PFTs also in wetland environments.  Further, we suggest that since PFT may have a large impact on the exposure pathway to humans, it would be reasonable to differentiate between PFTs and to account for between-species variation in environmental impact assessment. Since CR varies systematically with several soil properties, CR values could also be adjusted to illustrate effects of expected future changes in the soil environment.

How to cite: Peura, S., Saetre, P., Ehnvall, B., Nilsson, M. B., and Öquist, M. G.: Plant functional type and species determine elemental concentrations in boreal mire vegetation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9115, https://doi.org/10.5194/egusphere-egu24-9115, 2024.

EGU24-9885 | ECS | Posters on site | SSS7.13

Exploring the Impacts of Antibiotics in Manure on Soil Nitrogen Dynamics and Plant Growth in Grasslands 

Zhongchen Yang, Jan Willem van Groenigen, Bjorn J.A. Berendsen, Milou G.M. van de Schans, and Gerlinde B. De Deyn

Animal manure often contains antibiotic residues due to the prevalent use of these compounds in animal husbandry. After manure application, these residues could potentially affect soil microorganisms and plant growth, yet their impacts on soil nitrogen (N) dynamics in grasslands remain largely unexplored. We hypothesized that applying manure containing antibiotics would shift soil N dynamics by affecting plant morphology and certain N-cycling microbial guilds such as symbiotic N-fixing bacteria. To test this, we conducted a 64-day greenhouse experiment using field soil and including four plant treatments (no plants, ryegrass monoculture, clover monoculture, and a ryegrass-clover mixture) and three fertilizer treatments (antibiotic-free manure, manure containing oxytetracycline, and manure containing sulfadiazine). We measured nitrous oxide (N2O) emissions, N content in the shoot and root biomass, and antibiotic uptake in plant shoots, and used the δ15N technique to estimate symbiotic N fixation of clover. We also sampled soils at the end of the experiment to measure plant-available N pools (ammonia and nitrate) and the abundance of symbiotic N-fixing bacteria (by nifH gene). Our results showed that antibiotics in manure did not significantly alter soil N2O emissions, soil N pools, or plant aboveground N in any plant community. Both compounds were barely been taken up in plant shoots. However, both antibiotics significantly reduced root biomass in clover monocultures. Despite this root growth inhibition, N fixation (both aboveground and belowground) in clover monoculture was unaffected by both antibiotics. Interestingly, analysis of variance suggested that antibiotics in manure could lead to a higher abundance of nifH gene in soil than that of antibiotic-free manure in clover monoculture. In summary, although overall soil N dynamics were not impacted by antibiotics in manure, root growth inhibition in clover monoculture suggests varying grassland species susceptibilities to antibiotic stress. Our results also suggest that clover may adapt to antibiotic stress by modifying plant-microbe interactions. This study calls for further research on long-term environmental impacts of antibiotic residues in grasslands.

How to cite: Yang, Z., van Groenigen, J. W., Berendsen, B. J. A., van de Schans, M. G. M., and De Deyn, G. B.: Exploring the Impacts of Antibiotics in Manure on Soil Nitrogen Dynamics and Plant Growth in Grasslands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9885, https://doi.org/10.5194/egusphere-egu24-9885, 2024.

EGU24-11812 | Orals | SSS7.13

Mapping the soil pollution risk at territorial scale for urban planning: examples from French cities 

Blandine Clozel, Benjamin Deslandes, Alix Cornu-Lachamp, and Cécile Le Guern

The municipalities often lack a global knowledge of their soil quality, including soil pollution. Mapping soil geochemical quality is carried out in some cities using the URGE protocol. This approach is however not systematically applied due to financial reasons, but also due to strategies focusing on investigations at the scale of redevelopment project or at site scale, in a case by case approach. A global information may thus be missing for urban planning. The presentation deals with a methodology to map the soil pollution risk at territorial scale, based on historical and current pollution pressure.

The methodology takes into account information on historical and current industrial activities and agricultural activities, but also on anthropogenic deposits. The pressure linked to industrial sites uses a database that correlates activities and contaminants. This industrial pressure is considered higher than the agricultural one, because industrial activities generate more point-source contaminations, and agricultural activities generate more diffuse contaminations. The obtained maps are compared with neighbourhood scale studies. Two metropolis (Nantes and Rennes, France) serve as pilot cases.

The results show that a large part of urban soils of the 2 pilot metropolis are concerned by potential soil pollution. The technical services of the metropolitan areas were surprised by the large footprint of the anthropic activities. Some intend to use the results in the planning documents to alert on the potential presence of pollutants in soils. In this frame, they choose a precautionary approach taking into account the maximum potential extent of the former industrial sites. Some others would like to use this information to nuance the soil multifunctionnality, in order to take into account the soil quality to reach the no net land take objective. Another application concerns the mapping of the desealing potential of soils, where the potential soil pollution risk is one of the environmental constraints taken into account. The comparison with the local scale studies shows the satisfying approximation of the methodology. For former industrial sites and anthropogenic deposits, a detailed knowledge of their extent allows a better precision of the map.  

The progress concerns currently the sources of contamination. Further developments are needed to integrate the diffusion of contaminants linked to atmospheric deposition in particular. They could also consider potential pollution plume in groundwater. The pollution potential map should also be crossed with the potential natural anomalies linked to the geological setting.

How to cite: Clozel, B., Deslandes, B., Cornu-Lachamp, A., and Le Guern, C.: Mapping the soil pollution risk at territorial scale for urban planning: examples from French cities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11812, https://doi.org/10.5194/egusphere-egu24-11812, 2024.

EGU24-15326 | ECS | Posters on site | SSS7.13

Implementing Spatial Mapping and Monte Carlo Simulation for Probabilistic Risk Modeling of Heavy Metals Contamination in Urban Soils 

Hyunsoo Seo, Kyoung-Ho Kim, Jaehoon Choi, Young-Seop Cha, Jin-A Kim, Je-Seung Lee, and Seong-Taek Yun

Due to rapid and significant urbanization around the world, the land surface of urbanized areas has changed significantly through intensive construction via excavation and underground space development, and the natural state of environmental media such as soil has also altered through the emission of enormous amounts of diverse pollutants. Urban soil conditions, including heavy metal levels (esp., Cu, Zn, As, and Pb), have a significant impact on environmental assessments, so a better understanding of the source, distribution, and contamination of heavy metals is important for managing ecological and human health risks. The purpose of this study is to evaluate heavy metal (Cu, As, Pb, Zn) analysis data from 2,957 locations in Seoul, South Korea, representing the world’s fastest-growing metropolitan area. Statistical methods such as the additive log-ratio transformation-expectation maximization (EM) algorithm were used to process left-censored data below the limits of detection. We then used variogram analysis and ordinary kriging to interpolate the distribution of heavy metal concentrations to a 100m grid. The results showed an overall spatial distribution: more elevated levels of Cu, Pb, and Zn preferentially in the southwest of Seoul, and higher levels of As in the northeast. These patterns primarily imply spatial control of heavy metal enrichment mainly by land use activities in Seoul and warrant further investigation into specific sources of heavy metal pollution. Therefore, Monte Carlo simulation was utilized for risk assessment to provide comprehensive evaluations to incorporate uncertainties. As a result, a probabilistic risk mapping was prepared by running 1,000 randomized simulations per location. Then, the resulting risk maps were then combined with spatial data for vulnerable populations (i.e., infant and elderly populations) to assess potential health impacts. This study on the comprehensive spatial analysis of heavy metals in urban soils can provide key information on the characteristics, distribution, and exposure risk of multiple metals to develop targeted risk reduction strategies in metropolitan areas.

<Acknowledgements> This study was supported by the Korea Environment Industry & Technology Institute (KEITI) through the project ‘Integrated environmental forensic approaches to trace source and pathways of subsurface contaminants (2021002440003)’, funded by Korea Ministry of Environment (MOE), the Institute for Korea Spent Nuclear Fuel (iKSNF) and the BK Plus project in Korea.

How to cite: Seo, H., Kim, K.-H., Choi, J., Cha, Y.-S., Kim, J.-A., Lee, J.-S., and Yun, S.-T.: Implementing Spatial Mapping and Monte Carlo Simulation for Probabilistic Risk Modeling of Heavy Metals Contamination in Urban Soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15326, https://doi.org/10.5194/egusphere-egu24-15326, 2024.

EGU24-15682 | ECS | Orals | SSS7.13

Construction and demolition mineral-based waste impacts soil functioning and ecosystem services 

Angeliki Kourmouli, Carly Stevens, and John Quinton

Over half of the world’s population live currently in urban areas with future projections estimating an increase to 68% by 2050,with a projected additional 1.2 million km2 of land to be converted to urban areas by 20301. Poor practice in the construction industry, lack of established processes and lack of practitioners to undertake surveys assessing soils health prior to a development, as well as loopholes in laws and policies are key factors affecting soil health during construction. Millions of tonnes of soils coming from construction sites are being disposed of in the landfill2 but 90% is inert. Although there are policies in place advising multiple recovery pathways for construction soil (e.g. agricultural and ecological improvement schemes)3 that should take precedence, the most widely used recovery pathway is for civil engineering purposes.  

 

Urban soils are often overlooked but they play a major role in humans’ lives as the loss of soils functions can have not only disastrous consequences (e.g. loss of soil’s water infiltration function can cause increase flooding risk) but also huge financial repercussions. Construction inadvertently impacts soil health and functionality, due to soil loss, compaction, sealing, contamination, soil carbon loss, and soil biodiversity loss. In England and Wales the current approach for assessing the effects of a development on land and soil is restricted to the protection of biomass soil function for food, fibre and timber production,4 while other soil functions that are important in local, national and context of maintaining healthy ecosystems and mitigating climate change, are ignored.     

 

To better understand whether construction waste contamination has a serious impact on soil functioning, we carried out a study which aimed to assess the impact of three major mineral-based construction materials (concrete, brick and plasterboard) on soil multifunctionality and ecosystem services under future climates. The materials were mixed with soil in 6 different addition treatments (5, 10, 20, 30, 40, and 50% material addition) and were maintained for 5 months at three different moisture contents (10, 25 and 50%). Soil moisture, total carbon and nitrogen, microbial biomass carbon and nitrogen, ammonium and nitrate, nitrogen mineralisation rate and microorganism community structure and abundance were measured the first and the last day of the experiment. Immediate responses were observed in all variables and were sustained throughout the duration of the experiment. Preliminary results show statistically significant stepwise reductions of plant available ammonium and nitrate as the materials’ additions were increased. pH increased immediately (Day 1) following the material additions, and although the stepwise pattern was lost, the values remained significantly higher than the controls (Day 150). Our results suggest that mineral-based construction materials have a significant impact on soil functioning which warrants further investigation if these soils are to be reused under circular economy principles.    

 

References

1 https://www.worldbank.org/en/topic/urbandevelopment/overview.

2 Defra (2021) ENV23 - UK statistics on waste data.

3 Environment Agency (2021) – Guidance on waste suitability for deposit for recovery

4 IEMA (2022) – A new perspective on land and soil environmental impact assessment

How to cite: Kourmouli, A., Stevens, C., and Quinton, J.: Construction and demolition mineral-based waste impacts soil functioning and ecosystem services, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15682, https://doi.org/10.5194/egusphere-egu24-15682, 2024.

EGU24-16373 | Posters on site | SSS7.13

How P-nutrition status and the presence of non-essential metals (Al, REE) affect root carboxylate release and shoot element accumulation in plants with different nutrition strategies 

Oliver Wiche, Vuk Maksimović, Milica Stojanović Stojanović, Dragica Ristić Ristić, and Jelena Dragišić Maksimović

Rhizosphere processes related to nutrient acquisition and element exclusion overlap in time, space, and function depending on the composition of metal-chelating ligands released by plant roots in concert with rhizosphere pH. Thus, the presence of non-essential metals might influence the nutrient (phosphorus: P) acquisition in the rhizosphere, while processes related to nutrient acquisition might contribute to metal tolerance. However, until nowadays,  the interactions of essential and non-essential elements are poorly understood on a rhizosphere level. In the present study, we characterized the P-inefficient species Zea mays and Triticum aestivum with regard to their carboxylate release under conditions of P deficiency and compared the results with the P-efficient species Lupinus albus. In addition, we explored how the presence of microdoses of rare earth elements (REE) and aluminum (Al) alters carboxylate release and the shoot elemental composition of the plants. P deficiency increased carboxylate release in L. albus but not in T. aestivum. Lupinus albus released more carboxylates than T. aestivum did, regardless of the P-status. The exposure of plants to Al and REE in the early growth stage influenced biomass development, carboxylate release, and shoot elemental composition of mature plants. Notably, the effect of metal availability is clearly dependent on the plant species and the P status of the plants. The mechanisms remain poorly understood. However, these findings demonstrate that non-essential elements clearly shape chemical soil-plant interactions in the rhizosphere and have an impact on element acquisition.

How to cite: Wiche, O., Maksimović, V., Stojanović, M. S., Ristić, D. R., and Dragišić Maksimović, J.: How P-nutrition status and the presence of non-essential metals (Al, REE) affect root carboxylate release and shoot element accumulation in plants with different nutrition strategies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16373, https://doi.org/10.5194/egusphere-egu24-16373, 2024.

EGU24-16830 * | ECS | Orals | SSS7.13 | Highlight

Uptake of tire-derived compounds in lettuce under realistic growing conditions 

Luzian Elijah Hämmerle, Anya Sherman, Evyatar Ben Mordechay, Thorsten Hüffer, Benny Chefetz, and Thilo Hofmann

Tire wear particles represent a major fraction of global microplastic pollution, potentially entering agricultural ecosystems through biosolid application, treated wastewater irrigation, or atmospheric deposition. These particles contain high concentrations of organic additives and associated transformation products (tire-derived compounds), posing ecological and human health risks once released into the environment as some of these compounds exhibit high toxicity to fish and have been detected in human blood and urine.

We investigated the uptake by edible crops under realistic conditions of five tire-derived compounds: Benzothiazole (BTH), Diphenylguanidine (DPG), Hexamethylmethoxymelamine (HMMM), N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) and its transformation product 6PPD-quinone. In greenhouses, we grew lettuce (Lactuca sativa) in three well characterized soils varying in their physical-chemical properties collected from the Israeli Negev region. During the growing season, irrigation water was spiked every two days with tire-derived compounds at 500 μg/L. As a control, pots without plants were spiked with tire-derived compounds. After two months the plants were harvested and partitioned into three sections: inner leaves, outer leaves and roots. Soil samples were collected from the top soil (0-10 cm) and the bottom soil (10 cm - bottom of pot). Soil pore water samples were also collected at various time points. Tire-derived compound concentrations were quantified in all samples with HPLC-MS/MS. 

 

The bioavailable concentrations of DPG, HMMM and BTH in soil pore water decreased dramatically within 4 h of spiking, likely due to soil sorption, transport and plant uptake. At harvest, DPG, HMMM, 6PPD and 6PPDq were detected in the top soil, while in the bottom soil DPG, 6PPD and 6PPDq were detected only sporadically and at trace concentrations, suggesting limited vertical mobility in the soils. Compared to the no-plant controls, in pots with plants DPG and 6PPD had lower concentrations in top soil, indicating depletion by the plants. In the roots, tire-derived compounds were detected at concentrations in the order of 6PPDq > DPG > HMMM. 6PPD and BTH were not present at quantifiable concentrations. 6PPD, 6PPDq, DPG and HMMM were detected in the lettuce leaves at concentrations following the order of HMMM (max 62.1 ng/g dw) > 6PPDq (max 53.8 ng/g dw)  > DPG (max 42.3 ng/g dw)  >> 6PPD (max 2.1 ng/g dw). BTH was sporadically detected in leaves but was not quantifiable. Concentrations in the outer leaves were generally higher than in the inner leaves. The lowest leaf concentrations were found in plants grown in the soil with the highest clay content, likely due to a higher sorption and reduced bioavailability of the compounds in this soil.

Our findings show that tire-derived compounds can be taken up by edible crops under realistic growing conditions. Although the spiked concentrations were likely higher than environmental concentrations, our results indicate that plant uptake is a potential pathway for tire-derived compounds to enter the human food chain.

How to cite: Hämmerle, L. E., Sherman, A., Ben Mordechay, E., Hüffer, T., Chefetz, B., and Hofmann, T.: Uptake of tire-derived compounds in lettuce under realistic growing conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16830, https://doi.org/10.5194/egusphere-egu24-16830, 2024.

EGU24-17422 | ECS | Posters on site | SSS7.13

Climate impact on phytoremediation efficacy by the Cd/Zn hyperaccumulator Arabidopsis halleri in heavy metal contaminated agricultural soils 

Natalia Sánchez, Carolina Vergara-Cid, Sören Drabesch, Ines Merbach, Mika Tarkka, and E. Marie Muehe

Soil and plant health are major drivers of food production. Heavy metals are present in agricultural soils and their concentrations have been increasing due to anthropogenic activities. When toxic elements reach harmful concentrations in soils and become available, they adversely affect the environment, plant performance and consequently, crop production. Our group has shown that solubility of the toxic and non-biodegradable element Cd is expected to increase in agricultural soils under IPCC-projected climatic conditions likely for the year 2100. This increased mobility of the toxic Cd potentially enhances its transfer into crops, causing a threat for agricultural production. By contrast to agricultural crops, the heavy metal hyperaccumulating plants possess physiological traits that allow them to tolerate and accumulate high concentrations of heavy metals without exhibiting toxicity symptoms. Due to these traits the hyperaccumulators show great potential for phytoremediation, but the impact of climate change on their efficacy to remove heavy metals from the soil and translocate them to aboveground tissues is still unknown. We conducted greenhouse experiments growing A. halleri on five agricultural soils that vary in Cd contents ranging from 0.07 to 14 mg kg-1 dry soil. Temperature and atmospheric CO2 concentration were controlled during the experiments, so that today’s ambient climate was compared to future climate with +4°C and doubled atmospheric CO2 concentration. Cd accumulation in aerial parts was higher under future climatic conditions compared to plants grown under today’s climate. However, the metal transfer from soil to roots and from roots to shoots depended on the combination of soil biogeochemical processes as well as plant growth and physiology. If the soil had a Cd content between 0.1 and 0.5 mg kg-1 dry soil, hyperaccumulation might not be triggered, even if the mobility of Cd was still higher under future climatic conditions. On the other hand, despite that high concentrations of soil Cd stimulated metal accumulation, simultaneous presence of high content of other elements, such as Pb that is ultimately toxic to this species, negatively impacted the efficacy of Cd phytoextraction due to the increased plant stress. For soils with Pb contents that were not toxic and Cd concentrations above 0.5 mg kg-1 dry soil, in combination with future climatic conditions, Cd availability as well as Cd translocation and transfer from soil to root were affected, increasing phytoextraction. Our results indicated that translocation towards the shoots and a potential high efficacy of phytoextraction by A. halleri may be triggered by climate change mainly in soils with moderate Cd content. Under such growth conditions, phytoremediation could be considered as a feasible option to reduce mobile Cd fractions by using metal hyperaccumulators as cover crops in agricultural ecosystems.

How to cite: Sánchez, N., Vergara-Cid, C., Drabesch, S., Merbach, I., Tarkka, M., and Muehe, E. M.: Climate impact on phytoremediation efficacy by the Cd/Zn hyperaccumulator Arabidopsis halleri in heavy metal contaminated agricultural soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17422, https://doi.org/10.5194/egusphere-egu24-17422, 2024.

EGU24-17988 | Posters on site | SSS7.13

Influence of the soil water content and heavy metals/metalloid on woody plant’s aboveground biomass 

Viktoriia Lovynska, Oliver Wiche, and Svitlana Sytnyk

Toxic elements causing soil pollution and degradation are able to enter the substance cycle of ecosystem. Woody plants often act as critical objects for accumulating toxicants with their subsequent removal from the cycle of substances for a long period. Understanding the conditions of soil water saturation is essential for hydrological processes, and therefore influences this parameter in soil on the transfer of toxicants to vegetation too. The objective of this study was therefore to determine whether soil water saturation relate with heavy metals/metalloid accumulation in soils and whether it is possible to describe the relationship between accumulated toxic elements in soils and woody plants. The was conducted at 21 locations in the Freiberg region, Germany, where soil contamination with toxic metals is increasingly becoming problematic.The content of metals in the soil, leaves and branches were measured by ICP-MS. The relationship between soil saturation and accumulated heavy metals/ metalloid levels in the soil and the aboveground biomass of plants was analyzed. The maximum concentration of the studied toxic elements reached 7.36 mg kg-1 in the soil for Cd (Freiberg city forest), 618.1 for Pb (Freiberg Davidschaft vicinity), and 23276 for As (Davidschaft). The ability of woody plants Populus tremulae and Salix caprea to accumulate heavy metals/metalloid (Cd, Pb, and As) in aboveground biomass was studied under the condition of their growth in areas with increased content of these elements in the substrates.  The ability of the studied plants to absorb heavy metals/metalloid was determined based on the bioaccumulation coefficient. The accumulation of metal elements occurs more intensively in the assimilation part of plant biomass as compared to the wood of tree branches. The study demonstrates a more significant accumulation of toxic elements in  Salix caprea trees' aboveground biomass than Populus tremulae. The level of Cd accumulation in the biomass of Salix caprea defines this species as a potential hyperaccumulator of this element, allowing the strategies to be adjusted for the phytoremediation purposes of disturbed landscapes.

How to cite: Lovynska, V., Wiche, O., and Sytnyk, S.: Influence of the soil water content and heavy metals/metalloid on woody plant’s aboveground biomass, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17988, https://doi.org/10.5194/egusphere-egu24-17988, 2024.

EGU24-20088 | Posters virtual | SSS7.13

The effects of land use on soil moisture dynamics in loamy soils of southwest hungary 

Parisa Maleknia, Zana Fattah Ali, Rim Khedhri, Nelson Ugwonoh, István Geresdi, and Szabolcs Czigány

Over the past, increasingly severe hydrological extremes, droughts, floods, and changes in soil moisture have been significant consequences of climate change in the Carpathian Basin. These changes adversely affect agricultural yields, soil hydrological processes, leading to water scarcity, substantial economic damage, environmental losses, a reduction in surface water, and declining groundwater levels.

In this study, we aimed to compare the soil moisture dynamics (SM) of three land use types (pasture, ploughland, and orchard). All sites had soils of silt loam texture. As a second objective we aimed at analyzing the applicability of Hydrus 1D for simulating soil moisture dynamics in silty loam soils under three different land use types.

The three study areas are in the Transdanubian Hills (SW Hungary), a region of subhumid continental climate where matric potential, soil moisture, and rainfall were measured for the period of January 1, 2019, till February 28, 2023, for three land use types. Two monitoring stations were set up at each study site, one shoulder and a second one at foothill position. Volumetric soil moisture contents and matric potentials were measured at depths of 10 and 30 cm at each station (Teros-12 and Teros-21, respectively, Meter Group Inc., Pullman, WA, US). Data was stored in 15-minute intervals. The Blaney- Criddle formula was used for calculating aridity indices (ratio of annual evapotranspiration to annual precipitation total) for the summer of 2022.

Although the three sites were in relative proximity to each other, pasture had the most positive water balance, whereas orchard had the most negative, especially in 2022, when cherry trees were removed. Aridity indices in 2022 were 0.97, 1.18, 1.42 for the pasture, ploughland and orchard, respectively. Mean soil moisture values were 0.26, 0.21, and 0.21 (m3 m-3 ) for the pasture, ploughland and orchard for 10 cm, and 0.3, 0.22, and 0.22 (m3 m-3 )  for the pasture, ploughland and orchard for 30 cm, respectively. Pasture also demonstrated the lowest fluctuation of SM, whereas ploughland proved to have the poorest soil moisture dynamics over the studied period.

For the sensitivity test of Hydrus-1D, the largest difference was found for the orchard site at a depth of 30 cm in a shoulder position (RMSE = 0.029), whereas lowest difference was observed for the pasture at a depth of 10 cm in a foothill position (RMSE = 0.021).

We conclude that soil moisture dynamics was controlled by the cultivation methods. Our results confirmed the findings of (Horel et al., 2022) who found negative climate change effects on the SM content of vineyard and cropland soils. Hence, site-specific mapping and analyses of factors responsible for efficient moisture retention are indispensable for the maximization of agricultural productivity and the optimization of the efficiency of ecosystem services. Our findings could be valuable for the promotion of sustainable agricultural activities where loamy soils and subhumid continental climates prevail.

 

How to cite: Maleknia, P., Ali, Z. F., Khedhri, R., Ugwonoh, N., Geresdi, I., and Czigány, S.: The effects of land use on soil moisture dynamics in loamy soils of southwest hungary, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20088, https://doi.org/10.5194/egusphere-egu24-20088, 2024.

  • Ugwonoh1,3, P. Maleknia1, R. Khedhri1, Z.F. Ali1,4,S. Czigány2

1,3Doctoral School of Earth Sciences, University of Pécs, Ifjúság útja 6.,7624, Pécs, Hungary.

2Institute of Geography and Earth Science, University of Pécs, Ifjúság útja 6.,7624, Pécs, Hungary.

4Department of Geography, Faculty of Education, Koya University, Kurdistan region, Iraq.

3Corresponding author, ugwonohnelson@gmail.com

 

Abstract

As the demand for steel production increases, there is an increase in the disposal of steel slag, which may contaminate industrial soil due to the presence of heavy metals. Hence, this study examined the contamination of steel slag waste on industrial soil in southwestern Nigeria. Sample A (steel slag specimen) was provided by African Foundries Ltd. Sample B (soil samples) was collected using a soil auger at a dumping site in an industrial area. The three representative locations are Ogijo, Ogun State; Ibadan, Oyo State; and Ikeja, Lagos State.  Sample C was a mixture of steel slag and soil. The samples were pulverized, and the chemical composition of each sample for all locations was determined using an energy-dispersive X-ray fluorescence spectrometer (ARL QUANT’X EDXRF Analyzer) at the Research and Development Laboratory of the African Foundries Laboratory, Ogijo, Ogun State. The samples were dominated by Fe2O3, TiO2, SiO2, Al2O3, and MgO oxides. The soil pH after slag addition increased, and the higher the slag addition, the higher the soil pH. A comparison was made between industrial soil samples (sample B) and the mixture of soil with steel slag (Sample C) using Pearson’s coefficient of correlation method. it was observed that the computed value of the Product moment correlation coefficient (r = + 0.89) of the samples for the first location falls within the table value (1 > r > 0.8) indicating that there is a strong positive linear correlation between the soil sample and the steel slag while for the other two locations the computed value of the Product moment correlation coefficient (r = + 0.77 and r = + 0.74) of the samples fall within the table value (0.8 > r > 0.4). The contamination/pollution index for heavy metals in the soil showed that vanadium (V), manganese (Mn), and barium (Ba) had very severe contamination (VSC) in the humus soil. Nickel (Ni) and copper (Cu) are severely contaminated in the soil, whereas (Fe), Chromium (Cr), and Zinc (Zn) are moderately contaminated.  Titanium (Ti) has slightly contaminated the soil.

How to cite: Ugwonoh, N.: Contamination of steel slag waste on industrial soils of south-western Nigeria., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20435, https://doi.org/10.5194/egusphere-egu24-20435, 2024.

EGU24-21516 | Orals | SSS7.13

Human health risks and bioaccessibility of As and Pb in urban soils in the mining district of Riotinto (SW Spain) 

Annika Parviainen and Francisco José Martín-Peinado

Urban soils in the mining district of Riotinto in SW Spain contain high levels of As and Pb, in many cases surpassing the threshold values of polluted soils. Up to 84% of the soils have a Contamination Factor higher than 1 for As and 70 % for Pb, with maximum values of 432 for As and 373 for Pb. Natural soil forming processes from mineralized bedrock in the vicinity of the ore deposits, that are currently being exploited, influence the soil chemistry (Vázquez-Arias et al., 2023). On the contrary, calcareous aggregate pavements used as artificial soils covering public parks do not generally present risk for As and Pb. However, these soils may be influenced by deposition of atmospheric pollution derived from the mining activities (Vázquez-Arias et al., 2023).

The bioaccessibility tests simulating gastric fluids (using <150 µm soil fraction), exhibit low percentages for As in natural soils in comparison to the total concentration in the same fraction (average <18%) and in the artificial soils (<6%), whereas for Pb the bioaccessible portion ranged from 20 to 48% in natural soils, whereas it was insignificant for artificial soils. According to human health risk assessment modelling (using U.S.EPA protocols), 18% of the soils present risk of As toxicity for children, and merely one sample presents toxicity risk for adults, as well as, carcinogenic risk for both children and adults. Lead does not present human health risks except for one sample with toxicity risk for children.

We recommend covering the natural soils of the public parks, presenting potential human health risks, with calcareous aggregates as a cost-effective remediation measure. This material will act as a liming agent and will prevent the dusting of and the direct contact with polluted soils, minimizing human exposure via inhalation, ingestion and dermal contact and potential health risks.

 

Acknowledgment

This work has been financed by the EMC21_00056 project granted by the Council of University, Research and Innovation of the Regional Government of Andalusia, Spain.

 

References

Vázquez-Arias, A., Martín-Peinado, F.J., A., Parviainen. 2023. Effect of parent material and atmospheric deposition on the potential pollution of urban soils close to mining areas. Journal of Geochemical Exploration 244, 107131

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How to cite: Parviainen, A. and Martín-Peinado, F. J.: Human health risks and bioaccessibility of As and Pb in urban soils in the mining district of Riotinto (SW Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21516, https://doi.org/10.5194/egusphere-egu24-21516, 2024.

EGU24-2413 | Posters on site | SSS7.14

A Comprehensive Analysis and Validation of the Modified TRIAD Approach in Soil Ecological Risk Assessment  

Youn-Joo An, Dokyung Kim, Haemi Kim, Tae-Yang Lee, Seunghun Hyun, Sunhee Hong, and Seung-Woo Jeong

To protect and manage soil ecosystem from chemical pollution, the implementation of a site-specific soil ecological risk assessment is imperative. The TRIAD approach, endorsed by the International Standardization Organization, serves as a valuable tool for conducting site-specific assessments, integrating chemical, ecotoxicological, and ecological analyses. In Korea, efforts are underway to formulate guidelines based on the TRIAD methodology, organized into three key phases: desk study, TRIAD assessment, and risk management. The desk study phase reviews the need for a soil ecological risk assessment alongside a conceptual site model. If necessary, TRIAD assessments are initiated, considering screening and refined levels and socioeconomic factors. Following the determination of final risk values, a comprehensive risk management plan is created, involving monitoring and strategies such as removing or interrupting contamination sources. Case studies presented in this study demonstrate the adequacy and applicability of the proposed Korean guideline. The modified TRIAD technique and detailed toolbox introduced serve as valuable resources for efficient decision-making in protecting soil ecosystems in contaminated sites. Acknowledgement This work was supported by Korea Environment Industry & Technology Institute (KEITI) funded by Korea Ministry of Environment (MOE) 2022002450002 (RS-2022-KE002074).

How to cite: An, Y.-J., Kim, D., Kim, H., Lee, T.-Y., Hyun, S., Hong, S., and Jeong, S.-W.: A Comprehensive Analysis and Validation of the Modified TRIAD Approach in Soil Ecological Risk Assessment , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2413, https://doi.org/10.5194/egusphere-egu24-2413, 2024.

EGU24-9373 | ECS | Posters on site | SSS7.14

The soil safety situation in Hungary, especially around the military sites. 

Nóra Szűcs-Vásárhelyi, György Pátzay, Orsolya Szécsy, Sándor Koós, Nikolett Uzinger, János Mészáros, József Dobor, Mátyás Árvai, Anita Szabó, Gábor Garamhegyi, Gábor Szatmári, Zsófia Adrienn Kovács, and Márk Rékási

Effective management of soil damage is essential for national defence. In such a situation, chemical analytical methods are used to assess the contamination, which, although accurate, are time-consuming, costly and do not provide sufficient information on the state of the pedosphere on their own. Rapid decision making is of paramount importance, especially in disaster situations, and a rapid procedure for in situ assessment of the damage site, complemented by interpretation of soil health data, would be needed. The combined use of near-surface remote sensing methods, non-destructive analytical techniques and ecotoxicology could provide a new, optimised approach to soil safety. For the measurements in my research, I use in situ applicable non-destructive instruments (so-called proximal soil sensing) in the designated military sample area. The detection of soil radiation was performed by means of airborne remote sensing using an unmanned aerial vehicle (uav) mounted radiation measuring device. The potentially toxic element content was measured using a hand-held X-ray fluorescence spectrometer (PXRF). Ecotoxicological tests, soil column and microcosm experiments were set up to investigate soil ecosystem sensitivity. My objectives are to (i) implement improvements to facilitate effective operations of disaster management agencies (ii) streamline procedures for individual risk reduction and (iii) place the importance of pedosphere ecosystem sensitivity testing in a disaster management context during the execution of operations.

The research was funded by the National Research, Development and Innovation Fund of the National Defence Subprogramme of the Cooperative Doctoral Programme of the Ministry of Innovation and Technology.

How to cite: Szűcs-Vásárhelyi, N., Pátzay, G., Szécsy, O., Koós, S., Uzinger, N., Mészáros, J., Dobor, J., Árvai, M., Szabó, A., Garamhegyi, G., Szatmári, G., Kovács, Z. A., and Rékási, M.: The soil safety situation in Hungary, especially around the military sites., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9373, https://doi.org/10.5194/egusphere-egu24-9373, 2024.

EGU24-10725 | Posters on site | SSS7.14

Challenges of old mining cities in the application of the proposed EU Soil Monitoring Law – Outokumpu, Finland, as an example 

Juho Kupila, Soili Solismaa, Kirsti Loukola-Ruskeeniemi, Jaana Sorvari, Jussi Reinikainen, Helena Valve, and Juha Kaija

The city of Outokumpu in Eastern Finland occupies a Cu-Co-Zn mining region.  Mining and metallurgical activities began already in 1913. This area falls within a zone with naturally high concentrations of Ni, Cu, Co, and Zn in soil and bedrock. In addition, mining waste has been used in earthworks, especially in the construction of the city's streets.

In the summer of 2023, the European Parliament and Council proposed a Soil Monitoring Law, comparable to the earlier regulations established to protect air and water. The proposal mandates member states to address soil contamination. The European Union funded Horizon Europe project ISLANDR ‘Information-based Strategies for Land Remediation’ will provide data, tools, and methods to support the initiative. ISLANDR is a cross-disciplinary and multi-actor project and aims to promote the delivery of Green Deal objectives.

To provide real-world research context for different land use, climate and vegetation, seven test areas across Europe were chosen for a more detailed survey. Test areas were selected to characterize both point and diffuse sources of pollution, as well as by different soil pollution types.

The test area representing the brownfield mining areas is Outokumpu. Extractive wastes rich in sulphur, nickel, copper, zinc, cobalt, chromium, and other 'potentially toxic elements' (PTEs) were stored according to regulation which earlier was not as advanced as today. These wastes were also used for construction purposes, causing additional acidity and PTE load for the environment. Locally, elevated concentrations of PTEs have been observed in soil, groundwater, and surface waters.

Recommendations for regulation and remediation methods are compiled. Financial challenges, proposed solutions to improve the environmental status of the region, and opportunities for reusing or decontaminating degraded soils are discussed. Lessons learned in the historical Freiberg mining area in Germany will be utilized (Loukola-Ruskeeniemi et al., 2022: J. Haz. Mat. 424, 127677). The results from Outokumpu and Freiberg will be compared, for example, with the results of the EU MIREU project (Mining and Metallurgy Regions of EU MIREU GTK).

How to cite: Kupila, J., Solismaa, S., Loukola-Ruskeeniemi, K., Sorvari, J., Reinikainen, J., Valve, H., and Kaija, J.: Challenges of old mining cities in the application of the proposed EU Soil Monitoring Law – Outokumpu, Finland, as an example, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10725, https://doi.org/10.5194/egusphere-egu24-10725, 2024.

EGU24-13223 | Posters on site | SSS7.14

Relationships between bioaccessibility and speciation of ETPs in mining-affected soils. 

Carmen Pérez-Sirvent, Maria Jose Martínez Sanchez, Salvadora Martínez Lopez, Lucia Belen Martinez Martinez, MLuz Garcia Lorenzo, Carmen Hernandez Perez, Jaime Bech, and Manuel Hernandez Cordoba

The consequences of mining activities on the earth's surface inevitably lead to situations in which measures are needed to mitigate the impact on soil, water and air. The measures that counteract these negative effects are defined in what is known as remediation or remediation, recovery, rehabilitation and restoration. It constitutes the so-called R4 strategy (Lima et al., 2016), being sometimes difficult to be able to differentiate the nuances contained in these four terms when they are referred to the elimination of the effects produced by mining. In the case of large areas, such as a large natural area that is affected to varying degrees by mining, the strategies to be considered can be very varied and include more than one R, trying to minimize the impacts and reduce the risks by making them acceptable.

In the new European landscape, healthy soils are essential to achieve climate neutrality, a clean and circular economy and to stop desertification and land degradation. They are also essential to reverse biodiversity loss, provide healthy food and safeguard human health. The proposed tool to achieve this is the new Soil Monitoring Law provides a legal framework to help achieve healthy soils by 2050. In the case of soils with mining influence, the policies to be followed must be associated to the risk, since these soils naturally present a high level of PTEs.

In this work, 60 samples obtained from different abandoned mining sites in the Region of Murcia are evaluated to determine the risks they present in terms of the health of people, ecosystems and structures. For this purpose, different extracting media (water, acid and Olsen extraction (natural mobility), Mehra - Jackson extraction and oxidizing medium (potential mobility)) and the Solubility Bioaccessibility Research Consortium (SBRC) method are used, distinguishing two phases, stomach and intestinal. The PTEs evaluated were: As, Cd, Cu, Pb and Zn.

The results were contrasted with the differential mineralogy calculated for each sample, estimating the relationship between the mineralogical phase present and the mobility and bioaccessibility of the PTE. The bioaccessibility of the PTEs contained in the soils and their natural or potential mobility are determining factors in the risk assessment that will later affect the R measures, allowing to manage abandoned mining areas safely and efficiently.

Reference:

Lima, A.T., Mitchell, K., O’Connell, D.W., Verhoeven, J., Van Cappellen, P., 2016. The legacy of surface mining: Remediation, restoration, reclamation and rehabilitation. Environmental Science & Policy 66, 227-233.

How to cite: Pérez-Sirvent, C., Martínez Sanchez, M. J., Martínez Lopez, S., Martinez Martinez, L. B., Garcia Lorenzo, M., Hernandez Perez, C., Bech, J., and Hernandez Cordoba, M.: Relationships between bioaccessibility and speciation of ETPs in mining-affected soils., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13223, https://doi.org/10.5194/egusphere-egu24-13223, 2024.

EGU24-13302 | Posters on site | SSS7.14

Determination of the background levels of PTEs in arenosols of the Region of Murcia, SE Spain. 

Manuel Hernandez Cordoba, Maria Jose Martínez Sanchez, Salvadora Martínez Lopez, Lucia Belen Martinez Martinez, Carmen Hernandez Perez, Jaume Bech, and Carmen Perez Sirvent

Arenosols are soils mostly associated with coastal areas where coastal dynamics favor the accumulation of coarse fractions on the beaches. These sediments of marine origin give rise to coastal soils that support halophilic vegetation and a very special ecosystem. As they are included in urbanized areas and are a priority destination for recreational activities ( swimming, games, relaxation, etc.), they offer a very high level of contact for people. These areas are affected by marine erosion that modifies the coastal profiles, justifying anthropic actions to provide materials with similar granulometries and colors to meet the recreational purposes of the beaches.

The regulations on the quality of the materials that are contributed, regardless of their origin, continental or marine, are very strict in terms of the content of ETPs and other possible pollutants, however, the beaches and their neighboring areas can be affected by tides, spills, or drags that cause an increase in the natural concentration of ETPs. On the other hand, the existence of mining or industrial areas can affect the quality of these soils.

All this justifies a monitoring program in which the first step must be the establishment of the geogenic levels of the sandy soils and the background levels, pointing out the anomalous zones and their environment of influence.

For this purpose, a first sampling has been carried out on the Murcian coast, with a total of 250 samples, establishing the mineralogical groups and the content in ETPs (Pb, Cu, As, Zn, Cd, Hg). The methodology used was the same as that used for the determination of background levels in agricultural soils of the Region of Murcia, except for the sampling design, which was restricted to beach soils. The results confirm the main starting hypotheses and indicate the need to include underwater samples to confirm the implications of contaminant sources.

How to cite: Hernandez Cordoba, M., Martínez Sanchez, M. J., Martínez Lopez, S., Martinez Martinez, L. B., Hernandez Perez, C., Bech, J., and Perez Sirvent, C.: Determination of the background levels of PTEs in arenosols of the Region of Murcia, SE Spain., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13302, https://doi.org/10.5194/egusphere-egu24-13302, 2024.

EGU24-13373 | Posters on site | SSS7.14

Good agricultural practices on rainfed soils in Mediterranean areas for the European Green Pact. 

Maria Jose Martinez-Sanchez, Carmen Perez Sirvent, Salvadora Martínez Lopez, Lucia Belen Martinez Martinez, Imad El-Jamaoui, Jaume Bech, and Manuel Hernandez Cordoba

The European Green Deal (EU, 2019 b), the EU's growth strategy for a sustainable future, is based on the realization that ecological transformation is an opportunity and that inaction comes at a huge cost. In this sense, implementing nature-based solutions on a larger scale would increase resilience to climate change and contribute to multiple objectives of the Green Deal, as they are essential for maintaining healthy water, oceans and soils. Considering the risks and threats that climate change poses to agriculture in general and rainfed crops in particular, solutions are urgently needed to help farmers and land managers cope with climate risks.

This paper focuses on three points of this green pact:

- Achieve zero pollution and a pollution-free environment.

- Preserve and restore ecosystems and biodiversity.

- Achieving a healthy, fair and environmentally sustainable food system from the "Farm to Fork" strategy.

 

From the above points it is clear that, in the future and under climate change scenarios, it would be necessary to increase soil fertilization, mainly due to the loss of organic matter and soil fertility, which in the case of Mediterranean soils is already generally low. And, since inorganic fertilization is increasingly limited by regulation, this increase would have to be carried out by organic fertilization. This undoubtedly increases operating costs and thus the uncertainties regarding the economic viability of farms. It is necessary to adopt measures for mitigation and adaptation in rainfed agriculture, whose main benefits are increased soil fertility, CO2 retention, increased water infiltration and decrease in desertification.

To achieve these objectives it is necessary to implement mitigation measures based on the 4 per thousand initiative, improving and conserving the soil resource as a source of wealth and fertility, to halt rural abandonment and promote organic agriculture with the use of local waste, promoting the circular economy.

Among these measures, the following have been considered:

 Green manuring.

 Supply of composted plant material with local ingredients.

 Use of plant residues.

 Compost management.

 Crop rotation to promote soil fertility.

These monitoring works have been carried out in four plots located in the Region of Murcia in the context of the LIFE AMDRYC4 Project.

The introduction of good agricultural practices, incorporating the addition of organic matter to the soil and the restoration of natural vegetation, increases biodiversity and soil quality, slowing down desertification processes and contributing to Initiative 4 ‰. The results obtained with these proposals have been assessed and evaluated through indicators (DESERTNET Indicators of Fertility, Salinity and Phytotoxicity).

A baseline has been obtained to define the initial state of the monitored areas, thus making it possible to calculate the different indicators and the real cost of improving soil ecosystem services, concluding that in general, the measures that provide organic matter to the soil, increase soil fertility and do not include phytotoxicity problems, thus meeting the objectives proposed in the Green Pact, moving towards soil neutrality and increasing the ecosystem services it produces.

How to cite: Martinez-Sanchez, M. J., Perez Sirvent, C., Martínez Lopez, S., Martinez Martinez, L. B., El-Jamaoui, I., Bech, J., and Hernandez Cordoba, M.: Good agricultural practices on rainfed soils in Mediterranean areas for the European Green Pact., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13373, https://doi.org/10.5194/egusphere-egu24-13373, 2024.

EGU24-15409 | ECS | Posters on site | SSS7.14

Application of pXRF technique to the determination of major and trace elements in large soil datasets, advantages and limitations 

Iker Martínez del Pozo, Mónica Gomez-Pachón, Inmaculada Ferri-Moreno, José María Esbrí, Luz García-Lorenzo, Pablo Higueras, Saturnino Lorenzo, and Xabier Arroyo-Rey

Soil plays a fundamental role for both ecosystems and humans, and its characterization is an essential tool for strategic planning in areas such as agriculture, natural resource exploration and detection of potential soil contamination. To achive an effective geochemical characterization, it is necessary to study the background geochemical levels, considering the local geology of the environment and anomalous levels derived from point mineralization and anthropogenic activities such as mining or industrial activities. These background and reference levels are often published by each country or region. Although many regions in Spain have determined these levels, Castilla-La Mancha present incomplete partial information due to its extensive (79461 km2), complex geology (Variscan (meta)sedimentary and granitic domain, Alpine domain, Undeformed Mesozoic domain and Post-Alpine domain) and diverse mining activities (Almadén Hg district, Pg-Ag-Zn-Cu districts, Sb district, Campos de Calatrava volcanic field, clay, granite, Ca salts, Na salts and Diatomites mining areas). Given this scenario, the main objective of this work is to evaluate the applicability of portable x-ray fluorescence (pXRF) techniques to the determination of generic reference levels from large datasets. The proposal involves the analysis of a shortened pretreatment method to get an aliquot for analysis, and an analytical data quality study using certified reference materials (Soil-1, Soil-2, NIST-R, STSP-2, STSP-3 and STSP-4). For this purpose, the fine fraction dried in the laboratory were analyzed with a pXRF spectrometer in different modes, with “mining mode” and “soil mode”. Optimization of analysis times was carried out, setting it in 45s as the optimum time, after testing 60 and 90 seconds. Recovery percentages of major elements using “Mining mode” ranged Al, Mgand Si and “Soil mode” Ca, Fe and K, and for trace elements using “Mining mode” ranged Nb and P and using “Soil mode” As, Ba, Cr, Cu, Mn, Ni, Pb, Rb, Sn, Sr, Ti, V, Zn, Zr. The following elements, Ag, Au, Cd, Co, Hg, Mo, Sn, Ta, Th and U have been discarded as being too different from the reference materials used. In conclusion, this rapid analysis technique offers an efficient solution for the characterization of large surface areas or the sampling of large number of samples. Of the analytical modes of pXRF, the “soil mode” is the most suitable in terms of quantification, providing results that are optimally adjusted to the analyzed patterns and on a larger number of analyzed elements.

How to cite: Martínez del Pozo, I., Gomez-Pachón, M., Ferri-Moreno, I., Esbrí, J. M., García-Lorenzo, L., Higueras, P., Lorenzo, S., and Arroyo-Rey, X.: Application of pXRF technique to the determination of major and trace elements in large soil datasets, advantages and limitations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15409, https://doi.org/10.5194/egusphere-egu24-15409, 2024.

EGU24-16808 | ECS | Posters on site | SSS7.14

Dermal bioaccessibility and health risk of potential toxic elements (PTE) in mining environments (San Quintín Pb-Zn-Ag Mining Group and San Antonio Sb-W Mine, Spain). 

Inmaculada Ferri-Moreno, Iker Martínez-del-Pozo, Pablo Huertas, José María Esbrí, Luz García-Lorenzo, and Pablo Higueras

Metallic mining was very relevant in Spain last century. Because of this, currently there are numerous abandoned mines that suppose an environmental and human health risk. San Quintín Mining District (Ciudad Real) and San Antonio (Badajoz) are two examples of ancient metallic mining in Spain. In both mines there are a large volume of wastes like tailings, dumps or contaminated soils enriched with Zn, Pb, As, Cd, and Sb. San Quintín is currently being part of a project restoration that involves movement of tons of contaminated material. Twelve soil samples were collected from San Quintín Mining District and twenty-one were collected from San Antonio mine.

In these samples, the total trace element content was determined by X-Ray fluorescence spectrometry (XRF), in addition to other physicochemical parameters, such as pH and EC. To assess the human health risk, dermal bioaccessibility tests were carried out mixing wastes samples and two different synthetic sweats (EN1811 and NIHS96-10) during 2 and 8 hours.

The obtained results suggested that extraction interval percentages were: 0.01-57.29% for Cd, 0.001-55.768% for Pb, 0.001-93.180% for Zn, for San Quintín samples, 0.002-2.825% for Sb, for San Antonio samples and 0.001-0.707% for As, for all samples considered. The highest values correspond to extraction carried out with the lowest pH synthetic sweat (NIHS96-10) and specially for Zn, Cd and Pb. Metalloids appear to be less available or bioaccessible than heavy metals. Direct dermal contact between mine wastes and human skin, could mean the absorption of elements extremely harmful to health, thus restoration workers and anyone who can have contact with wastes, can be in danger if there are no security measures.

Contact with these mining residues poses a risk to human health, highlighting the necessity to assess not only dermal exposure but also inhalation and oral pathways for a comprehensive human risk assessment.

How to cite: Ferri-Moreno, I., Martínez-del-Pozo, I., Huertas, P., Esbrí, J. M., García-Lorenzo, L., and Higueras, P.: Dermal bioaccessibility and health risk of potential toxic elements (PTE) in mining environments (San Quintín Pb-Zn-Ag Mining Group and San Antonio Sb-W Mine, Spain)., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16808, https://doi.org/10.5194/egusphere-egu24-16808, 2024.

EGU24-19516 | Posters virtual | SSS7.14

Recycled Aggregates Effects on Acid Minesoils Response to Rainfall Events: Short-Term Study 

Cinta Barba-Brioso, Joaquín Delgado, Paloma Campos, Domingo Martín, and Antonio Romero-Baena

This investigation focused on the response of minesoils to which an upper substrate of recycled aggregates was added. The experience consisted in a first characterization of the minesoils (February’23) and two sampling after rainfall events, occurred in consecutive months (March and April’23). Soil sample reaction (pH-Eh and electrical conductivity) was studied with a portable multiparametric, chemical composition was analysed by X-Ray fluorescence and mineralogy was assessed by X-Ray diffraction and electron microscopy SEM.

Results showed that soil surface became less acidic, changing from 3.6 to up 6 units of pH. It was probed that the alkalinizing lost reactivity at depth, since level b and c were progressively more acid, but also that it was being depleted in time. Redox conditions, nevertheless, behaved in distinct way, increasing at the three levels in time, that could affect the distribution of elements. In fact, content of Al, Fe and S slightly decreased in surface with time, but specially Al increased in depth, suggesting any mobilization to leader elements. On the other side, trace elements, specially As, trended to concentrate at the intermediate level, marking the importance of redox conditions in their distribution.

Initial mineralogy hardly varied along time, maintaining the presence of the main minerals (quartz, mica and jarosite from the soil and calcite and dolomite from the amendment). Anyway, bassanite appeared during treatment, at the time than calcite and dolomite were depleted, showing the interaction of those with sulphur liberated from the oxidized pyrite observed by SEM.

How to cite: Barba-Brioso, C., Delgado, J., Campos, P., Martín, D., and Romero-Baena, A.: Recycled Aggregates Effects on Acid Minesoils Response to Rainfall Events: Short-Term Study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19516, https://doi.org/10.5194/egusphere-egu24-19516, 2024.

EGU24-20026 | Posters virtual | SSS7.14

Field Assessment of Recycled Aggregates as Mitigation Agents for Acid Leachates Caused by Rainfall Events over Mine Wastes: A Short-Term Study 

Joaquín Delgado, Cinta Barba-Brioso, Antonio Romero-Baena, Domingo Martín, Paloma Campos, and Isabel Gónzalez

This research represents the first step at a pilot field scale following the success of a previous laboratory study that demonstrated the favourable performance of a bed of recycled concrete aggregates, reducing the pollutant load of acid drainage generated by polymetallic sulfidic mining residues.

Mobility studies of trace metals in water and calcium chloride were conducted to evaluate the evolution of potential availability of an amended minesoil over three months, and to test the effect of each rainfall episode on it. Analysis of the solutions extracted were performed by ICP-OES.

Mobil fraction of the main elements in surface was dominated by Ca, Mg and S, demonstrating that reactivity of the recycled concrete aggregates played a key role on the neutralization of minesoil surface, by dissolution of carbonates in reaction with the acid environment during rainfall.

Trace elements reduced their mobility respect to the original soils while main elements increased. On the other hand, the mobility in calcium chloride showed no significant differences. Depth profiles indicate that particularly the concentration of Zn increases in the deeper levels, while As and Pb exhibit greater mobility at intermediate levels of the profile. Finally, Cu is the element that seems to have a more stable behaviour in depth. The potentially more hazardous elements have reduced their mobility compared to the initial conditions before the application of the amendment. However, the data suggest a higher efficiency of the treatment in the first centimetres of the profile, indicating a need for a readjustment of the proportions of reactive material in the amendment.

How to cite: Delgado, J., Barba-Brioso, C., Romero-Baena, A., Martín, D., Campos, P., and Gónzalez, I.: Field Assessment of Recycled Aggregates as Mitigation Agents for Acid Leachates Caused by Rainfall Events over Mine Wastes: A Short-Term Study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20026, https://doi.org/10.5194/egusphere-egu24-20026, 2024.

EGU24-214 | Orals | HS5.3.4

Impact of hydraulic conductivity on water quality and microbial ecology of rain gardens 

Vernon Phoenix, Erin Corbett, and Umer Ijaz

Rain gardens are a form of sustainable urban drainage which lower flood risk and reduce environmental contamination from stormwater.  A combination of processes including filtration, sedimentation and microbial metabolic processes work to remove contaminants from the stormwater.  In this study we examined the impact of hydraulic conductivity of raingarden soil on raingarden performance, exploring its impact on the removal of contaminants from the stormwater, as well as microbial community composition and function.  This was undertaken as part of a large scale project to install raingardens across the city centre of Glasgow, thus improving the city’s climate resilience.   The study utilized four raingardens fed real stormwater from a busy road.  All raingardens tested reduced contaminant concentrations in the stormwater, and reductions in contaminant concentrations were greatest when pollutant levels in the input water were higher.  Importantly, road salting in the winter did not cause dissolved metals to be released from the raingardens.  DNA was extracted from waters and soils for microbial community and function analysis using Illumina 16S sequencing and a bioinformatics suite.  A diverse community of bacteria capable of hydrocarbon degradation and metal resilience were found in stormwaters and raingarden soil.  Notably, the taxonomic evenness and overall diversity of the stormwater microbial community was increased as it passed through the raingarden. Furthermore, the raingarden soil displayed a greater functional richness compared to the input waters.  This demonstrates that the microbes in the raingardens can undertake a greater range of functions than those in the untreated stormwater, and highlights the importance of the raingarden bacteria in treatment of contaminants.   Microbial community composition and function showed little difference between rain gardens and PERMANOVA analysis identified that hydraulic conductivity had no significant impact on functional Beta diversity in the soil.  Overall, in this study, hydraulic conductivity did not appear to have a significant impact on microbial community composition, nor on the removal of contaminants by the raingarden, with all raingardens performing similarly well. 

How to cite: Phoenix, V., Corbett, E., and Ijaz, U.: Impact of hydraulic conductivity on water quality and microbial ecology of rain gardens, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-214, https://doi.org/10.5194/egusphere-egu24-214, 2024.

EGU24-607 | ECS | Orals | HS5.3.4

Ecosystem services supply-demand mismatches for urban heat mitigation  

Celina Aznarez, Sudeshna Kumar, Alba Márquez-Torres, Unai Pascual, and Francesc Baró

Urban areas, characterized by dense construction, often exhibit elevated land surface temperatures, leading to the formation of urban heat islands (UHIs). These UHIs pose significant environmental hazards, contributing to issues such as heat-related mortality, degraded air quality, and elevated heat stress on biodiversity and ecosystems. Moreover, the impact of UHIs is not uniformly distributed due to the heterogeneous nature of urban landscapes and socio-spatial inequities influencing factors like impervious surfaces and vegetation cover. Urban green infrastructure is increasingly valued as a nature-based solution to mitigate UHIs, offering essential ecosystem services (ES) like urban heat mitigation. To analyze the relationship between users' access and dependence on these benefits, we propose a modeling approach that integrates remote sensing, field, and socio-demographic data, along with Artificial Intelligence for Environment and Sustainability (ARIES) and GIS tools. This approach incorporates: i) indicators of UHI exposure and urban heat vulnerability indices; ii) spatial quantification of the supply and demand of urban green infrastructure related to ES for UHI mitigation; iii) spatially explicit (mis)matches of ES supply and demand balance and iv) coupled modelling. We applied it in the ‘green’ city of Vitoria-Gasteiz, in the Basque Country as a case study. Our findings evidence the unequal distribution of UHI burdens, with individuals vulnerable to heat experiencing disproportionate impacts, including higher exposure and limited access to temperature-regulating ES. This mismatch between the supply and demand of ES particularly affects disadvantaged communities. Conversely, areas associated with higher income levels indicate reduced vulnerability to heat. Incorporating environmental justice principles into UHI mitigation strategies is essential to ensure equitable outcomes for all residents. By considering the socio-spatial inequalities associated with supply-demand mismatches in ES and their impact on vulnerability to heat, our approach enables evidence-based decision-making and spatial prioritization to address the specific needs of vulnerable populations.

How to cite: Aznarez, C., Kumar, S., Márquez-Torres, A., Pascual, U., and Baró, F.: Ecosystem services supply-demand mismatches for urban heat mitigation , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-607, https://doi.org/10.5194/egusphere-egu24-607, 2024.

Most cities have climate goals such as lowering the Urban Heat Island (UHI) effect and reducing flood damages. Green infrastructure (GI) can help mitigate the UHI effects and has the potential to locally delay flood peaks. However, in dense urban infrastructure there is often little space for ground based vegetation. Green roofs are therefore a feasible implementation option even within city centres. While there is a myriad of types of green roofs available for flat roofs, and their performance is tested in various environments, sloped roofs as of yet have few design options available. To this end, Green Panels were developed as a novel type of GI for sloped roofs. As it is a novel design, its performance can be estimated only by literature results of GI applying different designs and materials. To overcome this research gap, in this case study a Green Panel prototype was constructed and its performance was monitored over a period of 3-4 months at the University of Twente, the Netherlands.

The experimental setup consisted of 1 m2 of Green Panels, and 1 m2 of regular roof tiles as control area, both at a slope of 45 degrees. The materials of the Green Panels, mounted on the same railing as solar panels, is High Density Polyethylene, while different substrates were tested: soil, rock wool, recycled fabric, and combinations thereof. Applied sensors were a soil moisture and temperature sensor (Truebner SMT50) and an environmental sensor (BME680), including a thermal sensor, both connected to Sensebox Mini dataloggers. The soil moisture sensors were placed in each of 6 Green Panel trays. The environmental sensors were placed above and below the roof tiles in both control and Green Panel locations, as well as above and below the Green Panels themselves. The measured parameters were air temperature, humidity, atmospheric pressure, VOC, soil temperature, and soil moisture. These values were compared to meteorological data from a local weather station at 5km distance. Other benefits such as increased biodiversity were not monitored, though species such as ladybug (family Coccinellidae) and fly (family Muscidae) were observed.

Analysis of the results shows that there is a small effect of Green Panels on reducing extreme temperatures, and errors in measurement setup and gaps in data continuity did not affect validity. The implications of this analysis were extrapolated to the urban scale for the city of Enschede to help answer what an appropriate performance monitoring scheme is for cities intending to implement GI and still uncertain about when their climate goals are being met.

How to cite: Vink, K.: Green Panel performance testing – Analysis from one season of monitoring data and implications for urban scale applications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1874, https://doi.org/10.5194/egusphere-egu24-1874, 2024.

EGU24-2833 | ECS | Posters on site | HS5.3.4 | Highlight

How do multilayer blue-green roofs affect the runoff water quality?  

Elena Cristiano, Alessandra Carucci, Martina Piredda, Emma Dessì, Salvatore Urru, Roberto Deidda, and Francesco Viola

To ensure a sustainable urban development, the large-scale implementation of green roofs and, more in general, of several nature-based solutions is an essential aspect to be considered. Thanks to their multiple benefits (e.g., pluvial flood mitigation, acoustic and thermal insulation of building, urban heat island reduction, air quality improvement, increase of biodiversity and additional aesthetic value) green roofs have been widely investigated. Among them, the multilayer blue-green roofs present an additional storage layer, that enables to accumulate the rainwater that percolates from the soil when it reaches saturation. This water can potentially be used for several domestic non-potable purposes, such as garden irrigation, street cleaning or flushing the toilets. To identify the possible rainwater reuse, it is fundamental to know the physical and chemical properties of this unconventional resource and evaluate whether they respect the regulations limits. Many studies investigated the effects of traditional green roofs on the runoff quality, without reaching a complete agreement. Moreover, the influence of the additional storage layer on the water quality has not been explored yet. In this context, the multilayer blue-green roof prototype installed at the University of Cagliari has been used as case study to analyze the quality of the outflow during three artificial and three natural rainfall events, comparing the runoff with the one obtained from a traditional roof. The prototype is constituted by 8 cm of soil (classified as sand) and 10 cm of storage layer, and it is characterized by Cactacee vegetation, that does not require additional irrigation or maintenance. For each artificial event, three samples every five minutes have been collected from both traditional roof and multilayer blue-green roof, to evaluate how the water quality varies during time. For the natural events only one sample has been collected as representative of the average quality of the accumulated water. The collected samples have been analyzed, evaluating temperature, pH, conductivity, total and volatile suspended solids, Chemical Oxygen Demand (COD), most common cations and anions and heavy metals concentrations. Results showed that suspended solids and heavy metal concentrations observed in the multilayer blue-green roof outflow are lower than by the traditional roofs, underlying the beneficial effects of this Nature-based solution. On the other hand, multilayer blue-green roof outflow presents high COD concentrations, caused by the accumulation of organic matter in the additional storage layer. Hence, the collected water can be used only for irrigation either of the multilayer blue-green roof itself or of gardens. It is important to notice that results obtained in this work are limited to one single soil (sand) and vegetation (Cactacee) type: the response with different vegetation, soil type and thickness, and fertilizer should also be investigated, as well as under different climatological conditions. 

How to cite: Cristiano, E., Carucci, A., Piredda, M., Dessì, E., Urru, S., Deidda, R., and Viola, F.: How do multilayer blue-green roofs affect the runoff water quality? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2833, https://doi.org/10.5194/egusphere-egu24-2833, 2024.

EGU24-4670 | Posters on site | HS5.3.4

Investigation on Flood Resistance Characteristics of Waterfront Plants: A Case Study of Baxi Stream in Fujian Province, China 

Jinn-Chyi Chen, Feng-Bin Li, Jian-Qiang Fan, Xi-Zhu Lai, Gui-Liang Li, and Wen-Sun Huang

Urban waterfront green spaces are pivotal in maintaining urban-rural landscape patterns, enhancing habitats and biodiversity, modulating temperature and humidity, purifying air, mitigating noise, and improving the urban microclimate. They play a crucial role in regulating the urban ecological environment and enhancing natural environmental capacity. Several waterfront plants demonstrate a high adaptability to local hydrological and climatic conditions, and are resilient to drastic water level changes. Their roots can stabilize riverbanks or riverbeds during abnormal floods. However, there is a dearth of empirical research data on these native plants. This study focuses on the flood that occurred on June 13, 2022, in Baxi Stream, Yong'an City, Fujian Province, China, causing damage to revetments, sidewalks, plants, roads, and disrupting urban traffic. Utilizing this flood event as a case study, we collected terrain data via real-time kinematic (RTK) surveying and unmanned aerial vehicles (UAV). We examined flood traces on structures, buildings, and trees to determine the water level, water surface slope, and inundation depth of waterfront green space during the flood event. We also investigated several common invasive natural plants, including Gramineae, Cyperaceae, and Polygonaceae families, and artificially cultivated plants like Cannaceae. Using the plant type survey data, we calculated the shear stress and flow velocity during the flood event to comprehend the anti-flow characteristics of waterfront plants in the study area. Our findings revealed that naturally invasive Gramineous plants, such as Saccharum spontaneum L. and Phragmites australis, possess a high flood resilience, withstanding  mean flow velocity exceeding 5m/s. This study can provide a valuable reference for the selection of greening plants for waterfronts or plant engineering methods to safeguard waterfronts or riverbeds.

How to cite: Chen, J.-C., Li, F.-B., Fan, J.-Q., Lai, X.-Z., Li, G.-L., and Huang, W.-S.: Investigation on Flood Resistance Characteristics of Waterfront Plants: A Case Study of Baxi Stream in Fujian Province, China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4670, https://doi.org/10.5194/egusphere-egu24-4670, 2024.

EGU24-5209 | Posters on site | HS5.3.4

Retention capacity and thermal properties of a multilayer blue-green roof in Sardinia: two years of monitoring 

Francesco Viola, Elena Cristiano, Salvatore Urru, and Roberto Deidda

Many different nature-based solutions have been proposed in the literature to contribute to the sustainable development of the urban environment. Among them, multilayer blue-green roofs are becoming more and more popular, thanks to their multiple benefits. As traditional green roofs, the multilayer ones guarantee high retention capacity during rainfall events, contributing to the pluvial flood mitigation. Thanks to the additional storage layer, not only the mitigation capacity is increased, but there is the possibility to store the collected water, and reused it for some urban purposes, such as garden irrigation. Moreover, these nature-based solutions ensure thermal insultation for the underneath buildings and they help lowering the air temperature, contributing to the mitigation of the urban heat island effects.  Finally, they improve the air quality, promote the biodiversity, and increase the aesthetic value of the overall city. In June 2019, a multilayer blue-green roof prototype has been installed at the university of Cagliari, and subsequently equipped with multiple sensors to monitor and evaluate the ecohydrological and thermal dynamics. The multilayer blue-green roof, with a surface of 16 m2, presents an 8 cm layer of soil, classified as sand, and a 10 cm additional storage layer. It is characterized by Cactaceae vegetation, which shows resistance to the high temperature and low water availability and does not require additional maintenance. The prototype has been equipped with a Smart Mill, that beside opening and closing of the valve to control the storage layer, enables to measure climatological variables, such as rainfall, air temperature and wind speed, and the water level in the additional layer. Four HOBO thermometers have been installed to measure the temperature in the soil, underneath the structure and on the lateral side. Two soil moisture sensors have been placed at opposite sides of the multilayer blue-green roof. Finally, a tank with a sensor to measure the water level have been collocated at the valve opening, to measure the outflow from the additional storage layer. The collected data have been used to model the ecohydrological and thermal dynamics, with the aim to quantify the potential benefits in terms of pluvial flood mitigation and thermal insulation. Results, collected during two full years of monitoring the prototype in Cagliari, are discussed, highlighting the potential benefits of a large-scale installation for the sustainable development of urban areas.

How to cite: Viola, F., Cristiano, E., Urru, S., and Deidda, R.: Retention capacity and thermal properties of a multilayer blue-green roof in Sardinia: two years of monitoring, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5209, https://doi.org/10.5194/egusphere-egu24-5209, 2024.

EGU24-5811 | ECS | Posters on site | HS5.3.4

Understanding Soil Characteristics and Hydrology to Optimise FloodWall®: Another Step Towards Effective Green Infrastructure 

Devakunjari Vadibeler, Joseph Holden, Fleur Loveridge, Andrew Sleigh, and Gerbren Haaksma

With rising urbanisation and environmental concerns, green infrastructure has become increasingly used to address a range of environmental issues, including flood hazards. By incorporating green infrastructure into their innovation strategies, cities may achieve a better balance between development and environmental conservation. In accordance with these global initiatives, Andel Ltd.’s FloodWall® stands out as an affordable, green substitute for perimeter flood defence made primarily of non-porous, post-industrial plastic waste, reinforced at the posts with steel pipes for added durability. This flood defence system, made from recycled materials and powered by renewable energy, can be installed in new constructions, existing buildings, and commercial settings. With the goal to maximise the potential of FloodWall® as a sustainable flood defence system, a collaborative effort has been made to develop specific site investigation methods to better understand the local soil hydrology and other characteristics that will control excess water flow beneath the wall and hence determine its effectiveness. Integrated methods are used including analysing geographic information system (GIS) data alongside in-situ and controlled laboratory findings to improve the efficiency of FloodWall® while cutting down its cost. For such green infrastructure solutions to be effectively and successfully implemented, a thorough understanding of site-specific soil properties such as permeability, soil water holding capacity, and the precise location of underground water pipelines and electrical equipment is vital. Accurate temporal and geographical soil hydraulic data are also critically needed for strategic management and accurate flood predictions. Precise soil moisture change measurements across larger areas can be difficult due to the dynamic nature of soil moisture levels. Although AI tools have a lot of potential in tackling this issue, the effectiveness of this approach is restricted by data availability.  As a result, it is critical to prioritise localised research and modelling to maximise flood defence design, reliability, and cost. The main objective of this study is to determine an efficient evidence-based workflow that enables key decisions on how to implement installation of sustainable and cost-effective flood walls around properties in locations where public or private funding for community defences are not viable. Our study uses (i) analysis of satellite imagery, (ii) controlled laboratory experiments, (iii) in-situ analysis using cutting-edge sensors, and (iv) appropriate machine learning (ML) and artificial intelligence (AI) techniques to investigate site-specific soil hydraulic properties. Data feeds a suitable numerical model to estimate soil water flow and water seepage beneath flood defence structures. With this integrated approach, environmental stakeholders and flood researchers are provided with extensive site-specific data as well as comprehensive reports that will allow well-informed decisions regarding the implementation of sustainable flood defence technologies in cities, with a particular focus on the FloodWall®.

How to cite: Vadibeler, D., Holden, J., Loveridge, F., Sleigh, A., and Haaksma, G.: Understanding Soil Characteristics and Hydrology to Optimise FloodWall®: Another Step Towards Effective Green Infrastructure, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5811, https://doi.org/10.5194/egusphere-egu24-5811, 2024.

EGU24-7564 | ECS | Posters on site | HS5.3.4

Evaluation of the Performance of Green Roof Substrates with Recycled Materials: A Three-Year Comparative Study 

Barbora Rybova, Marek Petreje, Petra Heckova, and Michal Snehota

The aim of this study was to test newly developed green roof substrates with a significant content of recycled materials under real conditions and to compare them with a commercially available substrate.

A two-layer extensive green roof of 7×5 m2 was constructed in 2020 and divided into four sections, two of which had top layers based on new substrates. These two substrates contained the same amount of crushed brick from demolition waste (37.5% by volume) but differed in the amount of pyrolyzed sewage sludge biochar (9.5% by volume in one and none in the other). The commercial substrate was mostly based on expanded shale, lava, and pumice. Hydrophilic mineral wool was used as the bottom layer of the green roof system to improve the water retention layer. Vegetation was established with sedum carpets.

Undisturbed substrate samples were taken in 2021, 2022 and 2023 to monitor changes in hydrophysical properties (retention curves, saturated hydraulic conductivity, grain size). At the same time, vegetation development over time was monitored visually, and substrate temperature and humidity were continuously measured by autonomous sensors.

Plants in the biochar and demolition debris plots rooted faster into the substrate and achieved higher cover. While plants in plots with commercial substrate or without biochar turned red in response to stress during periods of lower rainfall or more extreme temperatures, plants in the biochar-containing plot remained lush green longer. In the following year, a greater number of emergent plants (primarily grasses) that spread from the surrounding area were observed on the biochar-amended substrate. This was thought to be due to the increased availability of nutrients from biochar.

Surface temperature amplitudes were higher than substrate and mineral wool temperatures, locally influenced by the plant biomass surrounding the sensors. Temperatures of the substrate and hydrophilic mineral wool were more stable. Differences in substrate temperatures were observed particularly between substrates containing recycled materials and the commercially available substrate.

How to cite: Rybova, B., Petreje, M., Heckova, P., and Snehota, M.: Evaluation of the Performance of Green Roof Substrates with Recycled Materials: A Three-Year Comparative Study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7564, https://doi.org/10.5194/egusphere-egu24-7564, 2024.

EGU24-9959 | Orals | HS5.3.4

Modelling the environmental impact of combined urban drainage systems with a lumped hydrological approach 

Roberto Greco, Alessandro Farina, and Rudy Gargano

The management of combined urban drainage systems is a complex task, as it requires detailed knowledge about precipitation regime, hydrological features of the catchment, hydraulic characteristics of the drainage network, and information about the water use by the served inhabitants. Heavy semi-distributed hydrological and physically based hydraulic models are used for network conduits design. However, in many management problems, the knowledge of the hydraulic flow characteristics in all the conduits is not required, and the uncertainty of the available information hampers the use of complex hydrological models. Hence, simple models with few parameters and small computational effort may be preferable, especially for management and planning problems requiring the execution of many simulations.

In this study, a novel approach is proposed for the definition of effective lumped simplified models of urban drainage systems, the parameters of which can be estimated directly from cartographic information. For several case studies, the hydrographs predicted by lumped simplified models result close to those obtained with semi-distributed models in SWMM. The results show that robust relationships linking lumped model parameters with morphological and topological characteristics of the urban catchment can be established (Farina et al., 2023).

The proposed lumped modelling approach is applied to carry out a sensitivity analysis of the effects of parameters characterizing climate, urban catchment, and overflow discharge device, on several indicators of the environmental impact of combined sewer overflows (CSO) (Farina et al., 2024). In fact, pollution from CSO is still not satisfactorily addressed by current management practices and regulations, usually setting a dilution threshold for the discharged overflow, and enforcing limitations to the number of overflow activations per year. The sensitivity analysis indicates that the percentage of impervious surface of the catchment is the most influent parameter on all the indicators, and its reduction can effectively contain the yearly discharged pollutant mass. The overflow activation threshold, instead, results the second least influent parameter, suggesting that its regulation alone would not be a suitable strategy to control CSO pollution. The results also indicate that neither sustainable urban drainage practices, nor interventions on the CSO device, significantly affect the frequency of the overflows, which is indeed controlled by the local precipitation regime. Furthermore, the yearly discharged pollutant mass and the mean concentration of pollutants in the overflow result independent on the overflow activation frequency. Hence, the regulation of this latter does not seem a suitable means to reduce the environmental impact of combined urban drainage systems.

References.

Farina, A., Di Nardo, A., Gargano, R., van der Werf J.A. & Greco, R. (2023). A simplified approach for the hydrological simulation of urban drainage systems with SWMM. Journal of Hydrology, 623, 129757.

Farina, A., Gargano, R., & Greco, R. (2024). Effects of urban catchment characteristics on combined sewer overflows. Environmental Research, 244, 117945.

How to cite: Greco, R., Farina, A., and Gargano, R.: Modelling the environmental impact of combined urban drainage systems with a lumped hydrological approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9959, https://doi.org/10.5194/egusphere-egu24-9959, 2024.

EGU24-9991 | ECS | Posters on site | HS5.3.4

Study of Filtralite Depletion and pH Influence on Nickel Removal 

Marlon Mederos, Concepción Pla, and Javier Valdes-Abellan

This work delves into the efficiency of Filtralite in managing Sustainable Urban Drainage Systems (SUDS) for nickel (Ni) removal from urban runoff water. It addresses the optimization of green infrastructure in relation to water pollution and public health, due to the toxicity of heavy metals in general and Ni in particular, and their potential accumulation in living organisms (Ricco et al., 2015). The study's relevance lies in the growing need for innovative and sustainable solutions in urban water management, particularly in semi-arid and urbanized areas where runoff carries heavy metals into water sources (Wang et al., 2017).

The experimental procedure was carried out using flow tests in 10 cm-length columns filled with Filtralite. This porous medium has proven effective in removing heavy metals, including Ni (Pla et al., 2021b) jointly with the requirement of a high hydraulic conductivity. A Ni pulse was introduced into the column and the breakthrough curve was continually monitored at the outflow. The laboratory experiment is underpinned by a numerical model in HYDRUS-PHREEQC-1D (HP1), incorporating three Ni removal processes: Dispersion, Chemical Precipitation, and Adsorption, achieving a determination coefficient (R2) of 98%. With the calibrated HP1 model, it is feasible to analyze the impact of pH as a key element in metal removal.

The interaction between the contaminated solution and Filtralite leads to a rapid and noticeable increase in the solution’s pH. Ni solubility is highly dependent on pH (Amiri & Nakhaei, 2021); an increase in pH causes the Saturation Index of Ni to decrease, thereby facilitating its precipitation as hydroxide. The results demonstrated that the final concentration of the pollutant directly depends on pH values, with the lowest concentrations occurring at the highest pH (Pla et al., 2021a).

Laboratory tests were conducted to analyze Filtralite's wear over time in its capacity to modify the pH of the circulating water. Distilled water circulated for 100 days in continuous flow. When Ni was injected at two different pH levels, 9.27 and 8.28, removal efficiencies of 94% and 47% were observed, respectively. This confirms the relationship between pH and pre-removal efficiency, underscoring the importance of pH control for process effectiveness. Representing Filtralite's depletion over time, a gradual decrease in pH is observed as water circulates. Polynomial adjustments with an R2 of 93% help to determine the relationship between pH, time, and flow rate.

This finding is significant for SUDS design, which aims not only for water regeneration but also for the reduction of metal pollution (Ghadim and Hin, 2017). The research underscores the importance of green infrastructure in managing urban risks, demonstrating how nature-based solutions can effectively mitigate complex environmental challenges. The Filtralite study provides a firm foundation for integrating these systems into a broader urban risk management framework, aligned with green infrastructure and sustainability guidelines.

How to cite: Mederos, M., Pla, C., and Valdes-Abellan, J.: Study of Filtralite Depletion and pH Influence on Nickel Removal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9991, https://doi.org/10.5194/egusphere-egu24-9991, 2024.

Urban waterlogging has become a frequent and threatening issue in recent years due to rapid urbanization and extreme weather conditions, resulting in economic losses and health hazards. In this context, green roofs (GRs) emerge as a sustainable and innovative solution to mitigate these issues by absorbing rainfall, reducing runoff, and enhancing urban biodiversity. Despite the apparent benefits, the adoption of GRs remains limited, largely due to a lack of quantitative understanding of the factors that influence urban residents' GR adoption willingness.

This study aims to fill this knowledge gap via a survey approach, and distribute and collect survey responses from 999 residents in Shenzhen, a rapidly developing coastal city in China. The survey is designed to capture a range of variables that may influence residents' decision-making regarding GR adoption, including demographic information, housing characteristics, waterlogging experiences, roof utilization preference, knowledge of and preference for GR, and willingness to adopt GR. The GR adoption willingness is collected assuming two policy scenarios, one with government subsidy and the other without. By leveraging a machine learning model for data analysis, the study identifies five key predictors that commonly influence GR adoption willingness with and without subsidy: recognition of the advantages of GRs (GR_advantage), whether a resident lives on the top floor (Top_floor), the degree of concern about GRs (GR_concern), the duration of waterlogging experienced in and around the community (WL_time), and the individual's level of education (Education). Interestingly, the study also reveals that GR adoption willingness is affected differently under scenarios with and without policy incentives. In the absence of subsidies, the property fee (Pro_fee) is a significant factor; conversely, when policy incentives are present, age and house ownership (House_own) emerge as influential factors.

The complexity of these influencing factors is further evaluated using the SHAP (SHapley Additive explanation) model, which provides a nuanced interpretation of how these factors interact and exert nonlinear impacts on residents' willingness to adopt GRs. The insights derived from this analysis are critical for policymakers and urban planners who are looking to promote GRs as part of an integrated urban water management strategy. Specifically, a combination of long-term subsidies and one-time subsidies can be combined to motivate residential adoption. Recognizing the general unfamiliarity with GRs and related policies among residents, relevant outreach and education programs are essential. In addition, targeted subsidy levels could be helpful in stimulating more GR adoptions. An important consideration in this targeting process is the frequency of waterlogging events, which has been shown to significantly influence residents' willingness to pay for GRs.

 

How to cite: Yang, P. and Wu, J.: An analysis to interpret the heterogeneous resident's willingness to pay for green roofs to improve the understanding of decision heterogeneity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11013, https://doi.org/10.5194/egusphere-egu24-11013, 2024.

Groundwater, as the predominant freshwater resource globally, faces a growing scarcity challenge amid the rising global population, making it a critical resource in developing nations. Understanding the key factors influencing groundwater availability under current climatic and human-driven conditions is vital for achieving the sustainable development goals (SDGs). In regions like Assam's shallow alluvial aquifers, located in northeastern India along the flood-prone Brahmaputra River and the Himalayan foothills, the quality of groundwater is of paramount concern for managing its extraction and recharge. Despite its huge water potential, the region accounts for some of the most water-stressed pockets of the country, emphasising the need for thorough groundwater resource assessment for effective protection and management. The present study delves into the high vulnerability of groundwater in Assam due to both natural hydrogeological conditions and human-induced factors using geospatial models. Utilising DRASTIC and Risk Index (RI) models, we discovered that shallow groundwater tables and alluvial deposits are particularly susceptible to adverse effects from unplanned changes in land use and land cover (LULC). The findings indicate a significant correlation between urban-induced LULC changes and groundwater quality deterioration. This highlights the likelihood of industrial and domestic pollutants seeping from the soil into the underground aquifers, thus elevating the vulnerability of groundwater. To remediate the non-biodegradable and persistent heavy metal contaminants exposed to the soil from LULC activities, we propose a Nature-based Solution (NbS): phytoremediation using Chrysopogon zizanioides (vetiver grass). Laboratory-controlled experiments were conducted for two months with initial metal concentrations of lead (Pb), cadmium (Cd), and zinc (Zn) at 500 mg/kg. Results from the atomic absorption spectrometer showed selective metal absorption by the plants. The highest extraction capacity observed was 43% for Zn in the plant shoots, likely due to its role in plant metabolism, while 31% Cd and 35% Pb were removed. The study notes phytotoxicity signs, such as leaf chlorosis and shedding, indicating the plant's response to metal stress. However, with survival rates over 50%, the vetiver grass demonstrates significant metal tolerance. By integrating geospatial vulnerability assessment with the ecological technique of phytoremediation, this research presents a comprehensive strategy to enhance groundwater resilience. It showcases the efficacy of vetiver grass in developing green infrastructure solutions, offering a scalable and eco-friendly approach to mitigate soil and groundwater contamination. This study provides valuable insights for environmental policymakers and advocates, promoting sustainable NbS practices for regions facing similar challenges in groundwater management.

Keywords: Groundwater, LULC, Vulnerability, Phytoremediation, Heavy Metals, Vetiver Grass

How to cite: Deka, D., Ravi, K., and Nair, A. M.: Phytoremediation for mitigating soil heavy metal contamination: A strategic approach to enhance groundwater resilience in vulnerable shallow aquifer systems , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11423, https://doi.org/10.5194/egusphere-egu24-11423, 2024.

EGU24-13624 | ECS | Orals | HS5.3.4

Role of Vegetation in mitigating urban heat risk in Twelve American Cities - Applying the ARIES Modelling Approach 

Sudeshna Kumar, Alba Marquez, Celina Aznarez, G Darrel Jenerette, Marco Bidoia, Peter C Ibsen, Ken Bagstad, Stefano Balbi, and Ferdinando Villa

The anthropogenic urban realm exacerbates surface urban heat island (UHI) effects, triggering health hazards, such as mortality attributable to heat exposure in cities. The study makes a concerted effort to unravel the complex interplay between various spatial, quantitative, and qualitative attributes of vegetation, aiming to comprehend its pivotal role in mitigating urban heat risks within urban environments. The UHI risk is related to land surface temperature (LST). The study models UHI risk in twelve American cities in diverse Köppen-Geiger Climate zones spanning the contiguous USA. To address this, the Integrated Modelling approach by the ARtificial Intelligence for Environment & Sustainability (ARIES) initiative has been adopted in the study. This approach based on FAIR (Findable, Accessible, Interoperable, and Reusable) principles is accessible at https://aries.integratedmodelling.org/. Utilizing the k.LAB software with semantic reasoning our modeling approach assesses the UHI risk. It maps the spatial distribution of UHI considering hotspots of anthropogenic heat, vegetation, land cover, and land surface temperature. UHI risk is assessed at a resolution of 30 meters alongside census tract-level data using an ordered weighted approach. The study found variations in the relationship between greenness, as indicated by the Normalized Difference Vegetation Index (NDVI), and Land Surface Temperature (LST) across 12 different cities. The findings highlight the cooling effect of the water bodies, especially in areas near the port and green spaces. Linear parks such as roadside tree plantations typically feature uniform tree species and often lack smaller trees and shrubs, making them susceptible to heat infiltration from surrounding areas and resulting in a lesser overall temperature reduction. It identifies at least 30 percent of census tracts across 12 cities necessitate urban greening intervention. The study provides scientific insight into the cooling effects of urban parks, offering valuable guidance for urban planning and aiding decision-makers in addressing the UHI effect and enhancing overall urban sustainability. The study also underscores the significance of open science in developing environmental models addressing global sustainability challenges concerning the pressing issue of assessing urban climate risks. Models and scientific artifacts often face challenges in reusability, transferability, and sharing across diverse programming languages or modeling systems, revealing a significant lack of interoperability. By delving into the factors of LAI, NDVI, and Landscape Shape Index (LSI), the study aims to enhance understanding of the role of vegetation in ameliorating the adverse effects associated with UHI, thus paving the way for more effective urban heat management strategies. 






How to cite: Kumar, S., Marquez, A., Aznarez, C., Jenerette, G. D., Bidoia, M., Ibsen, P. C., Bagstad, K., Balbi, S., and Villa, F.: Role of Vegetation in mitigating urban heat risk in Twelve American Cities - Applying the ARIES Modelling Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13624, https://doi.org/10.5194/egusphere-egu24-13624, 2024.

EGU24-14278 | ECS | Posters on site | HS5.3.4

Sensitivity Analysis of Bioretention Cells for Stormwater Management: A Study in Secondary Cities of India 

Indra Mani Tripathi and Pranab Kumar Mohapatra

The present study conducts a comprehensive sensitivity analysis of bioretention cells, a green stormwater management infrastructure, in the context of urban stormwater systems in secondary cities of India (Bhopal and Kozhikode). The research aims to enhance our understanding of the performance and effectiveness of bioretention cells in mitigating the impacts of urbanization on stormwater runoff. Utilizing the Storm Water Management Model (SWMM), the study employs a systematic approach to assess the sensitivity of bioretention cells to various design and environmental parameters. The initial screening of diverse design parameters is performed using the one-factor-at-a-time (OAT) sensitivity analysis method. Subsequently, pivotal parameters, namely, conductivity, berm height, vegetation volume, suction head, porosity, wilting point, and soil thickness, are identified for further sensitivity analysis. Around 500 randomly and uniformly distributed samples for each sensitive design parameter are simulated using a Python wrapper for the Storm Water Management Model (PySWMM). These simulations are conducted under varying design storm scenarios. This research contributes valuable insights into the optimal design and configuration of bioretention cells tailored to the specific challenges posed by stormwater in secondary cities of India. By systematically analyzing the sensitivity of these green infrastructure elements, the study aims to inform urban planners, engineers, and policymakers about effective stormwater management strategies.

How to cite: Tripathi, I. M. and Mohapatra, P. K.: Sensitivity Analysis of Bioretention Cells for Stormwater Management: A Study in Secondary Cities of India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14278, https://doi.org/10.5194/egusphere-egu24-14278, 2024.

EGU24-14353 | Posters on site | HS5.3.4

Radiation budget and surface energy balance of green roofs using flux profile method 

Yongwon Seo and Woo Chang Jeong

One of the primary advantages offered by a green roof is its ability to regulate indoor temperatures more effectively in response to changing outdoor temperatures, in contrast to a traditional concrete roof on a building. This advantage aids in decreasing the amount of energy needed to cool the building during warm seasons and heat it in colder seasons. This investigation gathered data from four recently constructed detached buildings: one with a bare concrete roof, another with a highly reflective paint roof, and two with green roofs. The focus was on examining the complete radiation budget and surface energy balance of green roofs compared to other roof types during a summer season in Korea. The thorough data collected allowed for a quantitative assessment of how green roofs behave in terms of energy balance, particularly when compared to bare concrete roofs. The monitoring period for this study took place over a week, from July 21, 2021, to July 28, 2021. Results indicated that, on average, green roofs reduced the maximum indoor temperature by 6.83℃ compared to buildings with bare concrete roofs, potentially resulting in significant energy savings required for cooling. Additionally, the analysis of energy balance using the flux profile method highlighted the significance of the difference in ground heat flux in determining indoor building temperature. The findings also revealed that green roofs utilized a substantial portion of net radiation for latent heat flux (70.7%), but a minimal amount for ground heat flux (0.5%). Conversely, bare concrete roofs used a larger portion of net radiation for ground heat flux (16.2%) and sensible heat flux (45.3%), resulting in greater warming of both indoor building areas and the air near the surface. These outcomes illustrate that green roofs not only stabilize indoor temperature fluctuations but also directly assist in mitigating the heat island effect.

How to cite: Seo, Y. and Jeong, W. C.: Radiation budget and surface energy balance of green roofs using flux profile method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14353, https://doi.org/10.5194/egusphere-egu24-14353, 2024.

EGU24-15236 | ECS | Posters on site | HS5.3.4

Balancing Urban Heat, Flood and Water Scarcity: Blue-Green Infrastructure in Alpine Cities  

Lisa Ambrosi, Manfred Kleidorfer, Thomas Einfalt, Yannick Back, Alrun Jasper-Tönnies, Claudia Fennig, Martina Hauser, Fabian Funke, and Georg Leitinger

In Alpine cities, water management needs to be adapted to the challenges of climate change, including altering temperature and precipitation patterns. Blue-green infrastructure (i.e., the combination of nature-based and technical solutions) can help to improve the water and energy balance, to increase the evaporative cooling effect, to maintain sufficient soil water availability and to reduce runoff peaks. Thus, it can reduce the risks of heat, drought and flooding, and improve the overall quality of life in cities. The implementation of blue-green infrastructure requires an interdisciplinary approach, as mechanisms of urban water management and ecohydrology (i.e., energy balance and soil-plant-atmosphere continuum) must be optimized with regard to the common goal.

In the research project 'BlueGreenCities', ecological and technical disciplines are integrated to close knowledge gaps regarding (1) land-atmosphere interactions in ecological, hydrological and meteorological systems, and (2) the performance of blue-green adaptation measures under different climate scenarios in alpine urban areas. We present first results of measurement campaigns and eco-hydrological modelling to better understand the energy budget of various green spaces in the city of Innsbruck, Austria. Moreover, we give first insights if the specialty of the alpine setting (increasing summer droughts, but still cold winter temperatures) will be a chance or a burden for the current urban vegetation in the future.

The outcomes of our project underpin the importance of climate-friendly and future-proof planning of urban green spaces to ensure proper functioning of the blue-green infrastructure concept. The results support scientists as well as urban planners, land developers and policy stakeholders in decision-making for sustainable and flexible water management systems that maintain human well-being, economic development and environmental protection. This work is funded by the Austrian Climate and Energy Fund in the project BlueGreenCities (Project No. KR21KB0K00001), funding period: October 2022 until September 2025.

How to cite: Ambrosi, L., Kleidorfer, M., Einfalt, T., Back, Y., Jasper-Tönnies, A., Fennig, C., Hauser, M., Funke, F., and Leitinger, G.: Balancing Urban Heat, Flood and Water Scarcity: Blue-Green Infrastructure in Alpine Cities , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15236, https://doi.org/10.5194/egusphere-egu24-15236, 2024.

Climate adaptation and climate change prevention have become essential aspects of city planning. Urbanization and changing climatic conditions pose a threat to the sustainability of cities, and excess stormwater exacerbates these challenges by causing flooding and pollution of the receiving water bodies. To address these issues, cities must enhance the sustainability and climate resilience of their stormwater management systems. Nature-Based Solutions (NBS) offer a sustainable alternative to traditional grey infrastructure by providing water retention, detention, and pollutant reduction capabilities. Despite their numerous benefits, the adoption of NBS lags behind, with conventional solutions often being favored. Effective policy measures are crucial for promoting the integration of NBS into urban water management systems and aligning them with overall sustainability goals.

This study uses multilevel analysis that begins with an examination of EU policies and national legislation to understand the regulatory landscape. The focus then shifts to local stormwater regulation practices, which are explored through interviews with stormwater experts from various cities. These interviews provide insights into the practicalities, functionality, and shortcomings of stormwater regulation practices. Finally, this study focuses on Turku, analyzing the impact of the Blue-Green Index (BGI), which has been used to direct new constructions to use Green Infrastructure and NBS. The analysis of Turku's construction plans serves as a real-world case study to evaluate the actual effects of BGI on NBS implementation.

This research adds to the academic conversation by examining the complex relationship between regulatory measures and the practical application of Nature-Based Solutions (NBS) in urban water management. By analyzing decision-making processes at various levels, this study offers detailed insights into the difficulties and potential opportunities associated with promoting environmentally sustainable water solutions in cities. The findings of this research have significant implications for policymakers, urban planners, and environmental practitioners and could help inform strategies that encourage the adoption of NBS and create more resilient and sustainable urban water management systems.

How to cite: Saarinen, A., Leskinen, P., Reini, A., and Kasvi, E.: Examining the Impact of Regulatory Measures on the Implementation of Nature-Based Solutions in Urban Water Management: Insights from Finland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16057, https://doi.org/10.5194/egusphere-egu24-16057, 2024.

EGU24-16239 | ECS | Orals | HS5.3.4

Nature-based solution enhances resilience to saturation excess flooding in coastal cities in the Global South 

Emmanuel Dubois, Saleck Moulaye Ahmed Cherif, Montana Marshall, Mohamed Mahmoud Abidine, Charlotte Grossiord, and Paolo Perona

Coastal cities are facing a rise in groundwater levels induced by sea level rise, further triggering saturation excess flooding where groundwater levels reach the topographic surface or reduce the storage capacity of the soil, thus putting stress on the existing infrastructure. Lowering groundwater levels is therefore a priority for sustaining the long-term livelihood and resilience of coastal cities. This project discusses the feasibility of using tree-planting as a Nature-based solution to alleviate saturation excess flooding as a result of rising groundwater levels in coastal cities in the Global South. In environments with shallow groundwater, trees uptake groundwater by intercepting water that percolates in the unsaturated zone or reduce groundwater recharge by canopy interception of rainwater. These contributions, in turn, lower groundwater levels and increase the unsaturated zone thickness, further mitigating the risk of saturation excess flooding. A case study was conducted in Nouakchott City (Mauritania) where rising groundwater levels has led to permanent saturation excess flooding for more than a decade, making parts of the city inhabitable and posing long-term health threats. Consequently, this work presents an interdisciplinary approach using both ecohydrogeology and plant physiology to model the dewatering capacity of five local tree species. These species were selected based on their tolerance to the exceptionally challenging conditions for vegetation posed by the hot desert climate and the shallow and brackish groundwater table. Preliminary results from a 3D groundwater model indicate that a city-scale tree-planting program could induce a groundwater drawdown of up to 70 cm within a 40-year horizon. Thus, a tree-planting program is anticipated to lower the groundwater levels, thereby reducing flooding during the wet season. Tree-planting programs constitute long-term solutions, sustained by environmental factors, that complement conventional engineering solutions. The multi benefits of such Nature-based solutions, as well as the expected positive environmental, economic, and social outcomes, makes them particularly promising for alleviation of saturation excess flooding.

How to cite: Dubois, E., Cherif, S. M. A., Marshall, M., Abidine, M. M., Grossiord, C., and Perona, P.: Nature-based solution enhances resilience to saturation excess flooding in coastal cities in the Global South, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16239, https://doi.org/10.5194/egusphere-egu24-16239, 2024.

The concept of water-sensitive cities continues to gain traction globally, as the disruptive effects of urbanisation on local hydrological processes and the potential benefits of green infrastructure become increasingly evident. Despite this, in many planning instances, consideration is only given to how the water balance will be altered and hazard risk reduced from the current urbanised state to the state after implementation of green infrastructure. Why is the understanding of the natural water balance in the pre-urbanisation state often not considered as reference point for planning? If urban green infrastructure should provide hydrological and ecosystem services, should these services be similar to those in the natural condition before urbanisation?

For our study, we recreated the daily near-natural water balance for the city of Hamburg to quantify how urbanisation has already affected the water balance, particularly in years of hydrological extremes that represent hydrological hazards. Using the fully-distributed daily water balance model mGROWA, we developed two very high resolution (25 m) models for the city of Hamburg for 1991–2020; one representing the current hydrological situation and one representing a theoretical near-natural situation. To generate the near-natural scenario, the input datasets for topography, soil and land cover were adjusted through the integration of various datasets representing non-anthropogenic conditions, while sealed surfaces and artificially drained areas were removed from the datasets. As expected, due to the lack of runoff from sealed surfaces the actual evapotranspiration is much higher (+40%) in the near-natural scenario than in the current one. Groundwater recharge was also higher in the near-natural scenario (+27%), mainly due to the lack of surface sealing. We then compared the water balance components for the two models against the SPEI meteorological drought index to assess differences in the extremely wet and extremely dry periods that represent potential hydrological hazards. This revealed an increasing divergence in some water balance components between the scenarios for the extreme conditions, quantifying the extent to which the urbanisation of the city has exacerbated hydrological hazard risks. Our study presents a transferable methodology for assessing how urbanisation has affected the natural water balance of a region, which can be used as a starting point for defining targeted solutions for green infrastructure, with the aim of achieving water-sensitive cities.

How to cite: McNamara, I., Wolters, T., Schröder, M., Wotha, N., and Wendland, F.: How has urbanisation already altered a city’s natural water balance? The case study of Hamburg to present a commonly missing step before considering green infrastructure interventions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17797, https://doi.org/10.5194/egusphere-egu24-17797, 2024.

EGU24-19732 | ECS | Orals | HS5.3.4

Insights on permeable pavement hydraulic performance from large-scale laboratory experiments and physically based modelling 

Giulia Mazzarotto, Matteo Camporese, and Paolo Salandin

Among other Sustainable Urban Drainage Systems, Permeable Pavements (PPs) are one can be easily retrofitted in  the urban environment. However, they suffer of clogging phenomena that reduces their efficiency over time. Laboratory experiments to assess the hydraulic performance of a newly constructed PP subjected to different rainfall intensities have been conducted using a large-scale laboratory model (2x6 m2 with 1.2\% slope). The surface of the upstream portion (1.7x2 m2) is impermeable to simulate runoff generation over impermeable surfaces, while the downstream portion (4.3x2 m2) is realized with PICP. The downstream vertical side of the PP is made of permeable bricks and two gutter channels are placed crosswise to separately collect runoff and subsurface discharge. The remaining sides, as well as the bottom of the model, are impermeable. The filter package below the PICP consists of three layers: 5 cm bedding (3-6 mm gravel), a 10 cm base layer (8-12 mm gravel) and a 30 cm sub-base layer (20/40 mm gravel), which is laid on top of a 40 cm layer of native sand (silty sand with d50=0.23 mm). A geotextile separates the bedding and base layers and a 4m long drainpipe (D=150 mm) was inserted in the sub-base layer. The facility is equipped with probes on both lateral sides: 6 tensiometers in the native sand, 4 water content reflectometers in the base and sub-base layers, and 3 piezometers to record water table evolution throughout the experiments and degree of saturation of the filter layer package. Runoff and subsurface discharge are separately conveyed to two tipping bucket rain gauges. A rainfall simulator is used to generate quite uniform rainfall distribution (80 - 150 mm/h intensity) for 15 minutes or 30 minutes. Moreover, an Integrated Surface-Subsurface Hydrological model (CatHy) has been used to model the permeable pavement, assess and support data collected from the laboratory experiments.

Results from the laboratory experiments performed have proven the efficiency of a newly constructed permeable pavement to very intense rainfall events. The monitoring with spatially distributed sensors allowed to assess the evolution in time of the water table as well the “recovery” phase to pre-event conditions after the event. This is useful to assess the effect of repeated rainfall events at short distance in time. For each experiment performed, a rapid increase of subsurface discharges was recorded by the tipping bucket, whereas surface runoff occurred only for short and intense rainfall events (approximately 150 mm/h for 15 min). The system did not reach saturated conditions in any of the performed experiments due to the high permeability of the filter layer package. The monitoring with spatially distributed sensors also allowed to assess the heterogeneities of the physical processes (synthetic rainfall events, infiltration processes) as well as of the filter layer package. 

Future laboratory experiments simulating clogging phenomena will be performed and compared to the results obtained from the developed experiments up to now and of the ISSH model.

How to cite: Mazzarotto, G., Camporese, M., and Salandin, P.: Insights on permeable pavement hydraulic performance from large-scale laboratory experiments and physically based modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19732, https://doi.org/10.5194/egusphere-egu24-19732, 2024.

EGU24-20460 | ECS | Orals | HS5.3.4

Integration of Nature-based Solutions for stormwater control and management 

Noemi Maglia and Anita Raimondi

In the last decades, all over the world, cities have been characterized by the growth of urban population and urbanization. This involves some issues related to water resource management in terms of water supply during drought periods and stormwater control during rainfall events.

In this context, Nature-based Solutions (NBSs) are increasingly encouraged and used as support for traditional urban drainage systems to make urban areas more sustainable and resilient to the effects of climate change. They contribute to runoff control and management and natural water balance restoration, providing several benefits to the environment and communities. Moreover, NBSs meet several Sustainable Development Goals (SDG) of United Nations Agenda 2030, such as Goal 6 (“Clean Water and Sanitation”), Goal 11 (“Sustainable Cities and Communities”), and Goal 13 (“Climate Action”).

The study presents the integration of a rainwater tank with an infiltration system to limit both the water demand for drinking supplies and the overload of sewers. An analytical probabilistic approach is developed to balance the different purposes of the system and to overcome the limits of the traditional methods for performing multi-objective analysis. The proposed method enables the relationship between the main characteristics of the system and a return period and considers the possibility of storage capacity pre-filling from previous rainfall events. It can be applied under different climatic scenarios and management rules of the system.

The goodness of the theoretical framework is verified by applying it to a real case study in Milano (Italy) and successfully tested by comparing the results of its application with those from the traditional methods proposed in the literature. The use of integrated NBSs can be useful for the optimization of both water supply and urban drainage systems in terms of limiting drinking water waste and flood risk and also acting on water resource protection in terms of high-quality source preservation and aquifer recharge.

How to cite: Maglia, N. and Raimondi, A.: Integration of Nature-based Solutions for stormwater control and management, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20460, https://doi.org/10.5194/egusphere-egu24-20460, 2024.

SSS8 – Soil, Environment and Ecosystem Interactions

EGU24-729 | ECS | Orals | BG3.15

Ground beetles trophic interactions alter available nitrogen in forest soils 

Janey Lienau, Marlyse C. Duguid, and Oswald J. Schmitz

The dominant paradigm is that nitrogen cycles from plants to soil organic matter, being released in mineral form in the soil after organic matter is decomposed by microbes to be taken up again by plants. It is generally held that the process of decomposition is the rate-limiting step in the cycle. Ground dwelling macroinvertebrates may play a large role in ecosystem function by mediating microbe decomposition via predation and could be key links between plant litter and nitrogen availability in soil nutrient cycles. Ground beetles (Carabidae) are an abundant family of soil invertebrates that prey on groups of decomposing invertebrates. The goal of this study was to develop how predation from ground beetles contributes to nitrogen cycling as forests age. We hypothesized that ground beetles in young and old forests would indirectly impact available nitrogen. Our approach to addressing predator impacts on nitrogen cycling in forest soils was an experiment in young and old forest stands at Yale-Myers Forest in the northeastern United States using mesocosm cages stocked with predatory and detritivore ground beetles to create a trophic cascade over 68-days. Both forest sites had five blocks of three clustered treatments (n = 30). Treatments consisted of a control, detritivore, and predator and we took soil cores in each cage to assess available nitrogen. We used standard mesocosm cages that were designed for research on arthropod trophic interactions in ecosystems 1 m2, 0.8 m tall cylindrical mesocosms constructed with a scaffolding covered with fine mesh aluminum stocked with live beetles. We conducted a series of linear mixed-effect models in RSudio from the nlme package and lme() function in R Studio to predict the delta nitrogen mineralization rate by treatment in both young and old forests separately. We used ground beetle treatment as a fixed effect and block as a random effect to account for variation in microsite differences. Here we show differences in available nitrogen between forest types (P-value = 0.03). Our hypothesis that predators would impact available nitrogen was supported in young forests. Net nitrogen mineralization (P-value = 0.007) was consistently higher in the predator treatments compared to the control. In conclusion, this study suggests predator top-down control may be important for soil nitrogen availability in temperate forest soil via mediating microbe decomposition. Macroinvertebrates and their food web interactions in the soil should be further investigated and included in soil biogeochemical models.

How to cite: Lienau, J., Duguid, M. C., and Schmitz, O. J.: Ground beetles trophic interactions alter available nitrogen in forest soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-729, https://doi.org/10.5194/egusphere-egu24-729, 2024.

EGU24-1454 | ECS | Orals | BG3.15

A meta-analysis addressing the effects of eucalypt plantations on soil invertebrate density and diversity 

Raquel Juan-Ovejero, Marie L.C. Bartz, Dilmar Baretta, José Paulo Sousa, and Verónica Ferreira

Eucalypt plantations may have negative consequences on soil properties, yet a comprehensive understanding of their impact on soil invertebrate communities is lacking. This knowledge gap constrains our ability to unravel the potential effects of these fast-growing plantations on soil functioning. Hence, to analyze the overall impact of eucalypt plantations on soil invertebrates and to determine the main factors influencing these effects, we conducted a meta-analysis of studies comparing eucalypt plantations with different land use types (i.e. native forests, other forestry plantations, croplands, grasslands, integrated production systems, and invasive copses). We assessed their effects on both the density (analyzing 26 studies with 143 comparisons) and diversity (examining 14 studies with 168 comparisons) of soil invertebrate communities. The impact of eucalypt plantations on the density and diversity of soil invertebrate communities did not show statistically significant differences when considering all land use types together. However, the effects of eucalypt plantations on soil invertebrate density and diversity varied based on the specific land use types considered for comparison. The density was lower in eucalypt plantations relative to other forestry plantations but higher than in grasslands and integrated production systems. Contrarily, diversity was lower in eucalypt plantations compared to native forests but higher compared to other forestry plantations. Furthermore, the impacts of eucalypt plantations on soil invertebrates relative to other forestry plantations were influenced by factors such as the type of other forestry plantation (angiosperms versus gymnosperms), mean annual temperature, and annual precipitation of the study sites. These findings suggest that the effects of eucalypt plantations on soil invertebrate communities are context-specific and heavily influenced by the diverse characteristics of the different land use types considered for comparison. Taking into account the specific management practices and environmental conditions within eucalypt plantations and other land use types can provide insight into how alterations in land cover affect soil invertebrate communities.

How to cite: Juan-Ovejero, R., Bartz, M. L. C., Baretta, D., Sousa, J. P., and Ferreira, V.: A meta-analysis addressing the effects of eucalypt plantations on soil invertebrate density and diversity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1454, https://doi.org/10.5194/egusphere-egu24-1454, 2024.

Earlier studies show that across all biomes about half of litter fall is consumed by soil fauna. Part of that litter can be incorporated in to mineral soil by process called bioturbation. Soil fauna bioturbation may affect various processes related to decomposition and stabilization of organic matter, soil water retention, formation of habitat for soil biota and so on. 

In this contribution I summarized global experiment aimed to estimate amount of litter which is incorporated in soil by soil fauna bioturbation.  To do so a I used a filed mesocosm experiment located in 23 locations in all major biomes of northern hemisphere from tundra to tropical rain forest.   Mesocosms containing litter and mineral soil in two separate compartments were exposed in soil litter interface. These mesocosm were either accessible to soil fauna or not which allow to measure removal of litter from soil surface as well as accumulation of litter in mineral soil as well as overall loss of litter from the mesocosm. Mesocosm were supplied in local litter. Overall fauna significantly increased carbon accumulation in mineral soil. The effect was higher in temperate and tropical climate and lover in cold and dry biomes. Amount of carbon incorporated by fauna into mineral soil significantly positively correlated with actual evapotranspiration and negatively with CN ratio of litter.  In comparison with previous studies of litter consumption it can be estimated that about half of litter consumed by soil fauna is incorporated in mineral soil.  To put this together it appears that in natural ecosystem about half of annual litter fall is consumed by soil fauna and half of that fauna incorporate into mineral soil. This makes soil fauna important player in global carbon cycle

How to cite: Frouz, J.: Global pattern of soil fauna drivel litter mixing incorporation to soil in relation to climate and litter quality , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3228, https://doi.org/10.5194/egusphere-egu24-3228, 2024.

EGU24-3873 | Orals | BG3.15

Alleviation of functional limitations by soil fauna is key to climate feedbacks from arctic soils 

Eveline J. Krab, Gesche Blume-Werry, Jonatan Klaminder, and Sylvain Monteux

Alleviation of functional limitations by soil fauna is key to climate feedbacks from arctic soils

Arctic soils play an important role in Earth’s climate system, as they store large amounts of carbon that, if released, could strongly increase greenhouse gas levels in our atmosphere. Most research to date has focused on how the turnover of organic matter in these soils is regulated by abiotic factors, and few studies have considered the potential role of biotic regulation. However, arctic soils are currently missing important groups of soil organisms, and here, we highlight recent empirical evidence that soil fauna presence or absence is key to understanding and predicting future climate feedbacks from arctic soils. We propose that the arrival of certain soil fauna into arctic soils may introduce “novel functions”, resulting in increased rates of, for example, nitrogen cycling, litter fragmentation, or bioturbation, and thereby alleviate functional limitations of the current soil organism community. This alleviation can greatly enhance decomposition rates, in parity with effects predicted due to increasing temperatures. We base this argument on a series of emerging experimental evidence suggesting that the dispersal of until-then absent micro- meso-, and macroorganisms into new regions and newly thawed soil layers can drastically affect soil functioning. These new observations make us question the current view that neglects organism-driven “alleviation effects” when predicting future feedbacks between arctic ecosystems and our planet’s climate. We therefore advocate for an updated framework in which soil biota and the functions by which they influence ecosystem processes become essential when predicting the fate of soil functions in warming arctic ecosystems.

How to cite: Krab, E. J., Blume-Werry, G., Klaminder, J., and Monteux, S.: Alleviation of functional limitations by soil fauna is key to climate feedbacks from arctic soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3873, https://doi.org/10.5194/egusphere-egu24-3873, 2024.

EGU24-5867 | Orals | BG3.15

Tree species effects on stocks and stability of soil carbon: Links to mycorrhizal association and soil biota composition and functioning 

Lars Vesterdal, Christina Steffens, Yan Peng, Haifeng Zheng, Huimin Yi, and Petr Hedênec

Tree species with leaf litter traits driving slow rates of leaf litter decomposition have traditionally been associated with accumulation of higher soil organic carbon (SOC) stocks than tree species with fast litter decomposition rates. This hypothesis has mainly been based on observations of thick C-rich forest floors under tree species associated with ectomycorrhizae (ECM). However, a recent hypothesis suggested that tree species with foliar litter traits conducive to fast decomposition will lead to more pronounced microbial transformation and stabilization of litter C. The latter tree species are often associated with arbuscular mycorrhizae (AM) and may enhance deeper incorporation of C by more active soil fauna communities and by higher belowground rates of litter input. The Danish multi-site common garden tree species experiment includes ECM and AM tree species that differ widely in traits such as foliar litter chemistry. The experiment has been studied over the last 15 years to document and explain soil C stocks supported by emerging studies of soil fauna and soil microbial community composition and functioning.

The six common European tree species formed distinct groups in soil carbon characteristics as well as in soil biota community composition and functioning that partly reflected their mycorrhizal association. Forest floor C stocks were consistent with the traditional perception of slowly decomposing leaf litter in ECM species being conducive to high C stocks. However, an intriguing pattern of higher C stocks in the mineral soil in AM tree species with high litter quality and characteristic soil biota functioning supported the recent microbial stabilization hypothesis and suggested deeper incorporation of C in more stable forms.

Based on new results on microbial, macro- and mesofauna communities and their functioning, and on repeated soil sampling, this talk will revisit the common garden experiments for a synthesis of processes and patterns in organic matter formation that may explain observed patterns in quantity and quality of SOC.

How to cite: Vesterdal, L., Steffens, C., Peng, Y., Zheng, H., Yi, H., and Hedênec, P.: Tree species effects on stocks and stability of soil carbon: Links to mycorrhizal association and soil biota composition and functioning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5867, https://doi.org/10.5194/egusphere-egu24-5867, 2024.

EGU24-6636 | ECS | Posters on site | BG3.15

Soil fauna presence in post-mining area after afforestation with diverse tree species 

Wiktoria Ogar, Rüdiger M. Schmelz, Bartłomiej Woś, Tomasz Wanic, Marcin Pietrzykowski, and Agnieszka Józefowska

Soils around the world are facing increasing degradation due to human activities such as mining. This degradation adversely affects soil functioning and, consequently, the ecosystem services it provides. Therefore, our research concerns various strategies for restoring forest ecosystems at such sites. Soil fauna can play a key role in restoring degraded soils, positively influencing their properties, especially in the case of newly formed soils. Providing an influx of organic matter, such as through afforestation, can promote the growth of microorganisms and subsequently facilitate the emergence of soil fauna and the process of soil formation.

Our main research question is how different tree species and soil disturbances, in this case especially mining, affect enchytraeid and earthworm communities and how soil fauna contribute to the soil-forming process in post-mining soil. We selected sandy soil in sandpit excavations afforested with various tree species, including Scots pine (Pinus sylvestris L.), European larch (Larix decidua Mill.), Silver birch (Betula pendula Roth) and European oak (Quercus robur). Soil profiles were described and samples were taken for basic soil analysis, including pH, soil organic carbon and nitrogen content, and soil porosity. In addition, earthworms and enchytraeids were collected from all plots to assess the density and species diversity of the soil fauna.

Based on the WRB classification, the studied soils were classified as Arenosols. The studied soils generally showed acidic pH, subangular structure in the upper layers and slightly acidic pH with a lack of structure in the subsoil. Slight differences were observed in the thickness of the humus layer between the soil profiles. Areas undergoing reclamation after sand mining were characterized by low enchytraeid densities. The Shannon index reached the highest value for the birch site and was 0.64 and the lowest for the pine site and was 0.08. In turn, the highest density of enchytraeid occurred at the oak site and was 34574 ind. m-2 and the lowest at the larch site and was 10123 ind. m-2. Soils under deciduous species show higher density and biomass of earthworms compared to soils under coniferous species. The highest density of earthworms was noted at the birch site and was 25 ind. m-2 and the lowest at the larch site and was 0 ind. m-2. It is worth noting that the birch site showed the highest diversity of enchytraeid species and highest abundance of an earthworm species. The density of the studied soil fauna was not high, but their presence and diversity may indicate a positive trajectory of changes occurring in these soils. 

This research was funded by The National Science Centre, Poland, grant No. 2021/42/E/ST10/00248. The analyses were performed in the Laboratory of Forest Environment Geochemistry and Reclaimed Areas, University of Agriculture in Krakow.

Key words: earthworm, enchytraeid, sand mine, sandy soil

How to cite: Ogar, W., Schmelz, R. M., Woś, B., Wanic, T., Pietrzykowski, M., and Józefowska, A.: Soil fauna presence in post-mining area after afforestation with diverse tree species, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6636, https://doi.org/10.5194/egusphere-egu24-6636, 2024.

EGU24-6768 | Posters on site | BG3.15

Earthworms impact on soil organic matter mineralization sheds new light on their ecological groups  

Gwenaëlle Lashermes, Luna Vion-Guibert, Yvan Capowiez, Gonzague Alavoine, Ludovic Besaury, Olivier Delfosse, and Mickaël Hedde

Earthworms contribute to numerous ecological functions by impacting the soil biogeochemistry. Through their bioturbation activity, they modify the soil structure and the distribution of its components. By ingesting soil and secreting mucus, earthworms bring microorganisms and organic matter into contact under conditions that favor microbial activity, thus stimulating the mineralization of carbon and nutrients by soil microorganisms. While these effects are relatively well known for the dominant agricultural species, the diversity of earthworm habitats and functional traits suggests that not all would have the same impact.

Recently, Capowiez et al. (2024) proposed a classification of earthworms into functional groups (sensu Hedde et al. 2022) in relation to bioturbation (reorganization of soil particles). The aim of our work was to study the linkages between the organic matter mineralization and soil bioturbation functions performed by earthworms. We aimed to assess the different impacts on biogeochemical cycles of earthworm species belonging to different bioturbation functional groups.

Six earthworm taxa were incubated in soil columns in the presence of alfalfa litter: Octodrilus complanatus (intense tunneler or anecic), Lumbricus terrestris and Aporrectodea caliginosa meridionalis (burrower or epi-anecic), Alollobophora chlorotica (shallow biotubator or epi-endogeic), Octolasion cyaneum (deep bioturbator or hypo-endogeic), Microscolex dubius (intermediate). After 6 weeks of incubation, the gallery networks were scanned, and pictures were analyzed. The columns were then opened, and soil samples were taken to quantify carbon and nitrogen mineralization, as well as the abundance and diversity of microorganisms in different soil compartments: casts (earthworms surface excrement), drilosphere (soil around the galleries) and surrounding bulk (soil not directly altered by earthworms).

The results on earthworm bioturbation activity were consistent with those obtained by Capowiez et al. (2024) and made it possible to distinguish five functional groups (A. c. merdionalis and O. cyaneum being indistinguishable from each other). The presence of earthworms increased carbon and nitrogen content and stimulated mineralization in the casts but had low impact on the drilosphere. Biogeochemical and microbiological measurements tended to separate the taxa studied into two groups: species that stimulated carbon and nitrogen mineralization in the casts, by selecting bacteria (during passage through the digestive tract) and maintaining high humidity, and those that had little effect on microbial communities and their activity. Furthermore, the results showed that L. terrestris, often used as a "model" worm, had a higher impact on soil structure and on the mineralization of organic matter than most of the other taxa studied, and is therefore not representative of the role of earthworms in soils.

References:

Capowiez, Y., Marchán, D., Decaëns, T., Hedde, M., & Bottinelli, N. (2024). Soil Biology and Biochemistry, 188, 109209.

Hedde, M., Blight, O., Briones, M. J., Bonfanti, J., Brauman, A., Brondani, M., ... & Capowiez, Y. (2022). Geoderma, 426, 116073.

 

How to cite: Lashermes, G., Vion-Guibert, L., Capowiez, Y., Alavoine, G., Besaury, L., Delfosse, O., and Hedde, M.: Earthworms impact on soil organic matter mineralization sheds new light on their ecological groups , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6768, https://doi.org/10.5194/egusphere-egu24-6768, 2024.

Sugar maple (Acer saccharum Marsh.) forests are the dominant ecosystems in southern Quebec (Canada) and are widely used for maple syrup production, wood products manufacturing, recreation, and sometimes converted to hybrid poplar plantations. Consequently, human footprints on these ecosystems are multifarious, with potential impacts on soil greenhouse gas (GHG) emissions. We studied the principal and interactive effects of three anthropogenic factors (liming, introduction of non-native earthworms, and tree litter quality) on soil CO2 and N2O emissions, and on related soil properties. Thirty-two PVC pipes (1.0 m x 30 cm dia.) were set upright and filled with homogenized soil collected from a sugar maple stand. Each of these mesocosms was assigned one of eight treatments from a 2×2×2 factorial array of three experimental factors (± liming, ± earthworms, maple vs. poplar litter), replicated in four complete blocks. Over the course of a 15-month trial, we measured soil CO2 and N2O emissions from each mesocosm. At the conclusion of the trial, we measured soil pH, % organic matter (SOM), mineralizable nitrogen (Nmin), water-stable aggregate index (WSAI), δ13C, and mineral-associated organic matter (C-MAOM) at each of four soil depths (0, 20, 40 and 60 cm). The effects of earthworms (+EW) and liming on the response variables were generally greater than the effects of litter types. Liming increased pH by 0.6 units in the soil surface layer. Treatments had negligible effects on SOM throughout the soil profile. Nmin increased by factors of ×15 and ×7 in the surface layer of the Liming and EW treatments respectively. In contrast, mineralizable NO3-/NH4+ ratios were 125 and 80 in the EW and EW+Liming treatments respectively, and only 30 in the Liming and Control treatments, suggesting that nitrification was stimulated by soil mixing/aeration rather than by pH. Accordingly, cumulative N2O emissions were higher in the EW and Ew+Liming treatments (500 and 250 mg N2O-N m-2, respectively) compared to the Control and Liming treatments (< 50 mg N2O-N m-2). Likewise, cumulative CO2 emissions increased in the EW treatment and decreased in the Liming treatment relative to the Control; liming offset the positive effect of earthworms when both factors were combined.  Liming increased δ13C by 3‰ in the soil surface layer, hinting that lower CO2 emissions in this treatment could have resulted from higher microbial processing of litter leading to more stable SOM. However, all treatments had no effect on C-MAOM, suggesting instead that higher δ13C in the Liming treatment resulted from higher 13C in the liming material compared to native soil C. Moreover, both Liming and EW treatments increased WSAI, thus refuting the premise that CO2 and aggregate stability were related. We conclude that the spread of non-native earthworms in sugar maple forests of southern Quebec is potentially increasing soil N2O and CO2 emissions by up to one order of magnitude. Increased N2O emissions are likely due to increased nitrification, whereas CO2 emissions cannot be predicted by changes in C-stability. Liming could potentially be used to mitigate the positive effects of earthworms on soil GHG emissions.

How to cite: Jordan, F. and Ouimet, R.: Liming offsets the increase in soil greenhouse gas emissions due to non-native earthworms in sugar maple forests., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6967, https://doi.org/10.5194/egusphere-egu24-6967, 2024.

EGU24-7303 | ECS | Posters on site | BG3.15

Earthworm-microbe interactions: what can we learn from controlled earthworm introduction into boreal forest soil? 

Péter Garamszegi, Karina E. Clemmensen, Thomas Keller, Björn D. Lindahl, and Eveline J. Krab

Earthworms are considered ecosystem engineers due to their remarkable influence on the soil system. While creating the drilosphere in the soil, they interact with microorganisms both directly and indirectly and thereby greatly affecting soil carbon and nutrient cycling. Earthworm activity may reshape soil microbial communities in several ways. Amongst others, earthworms may cause shifts in microbial communities and activities/processes by damaging hyphal networks, selectively feeding on substrates hosting certain bacteria and fungi, and by redistributing nutrients in the litter-soil continuum of the soil. However, interactions between earthworms and soil microbes, especially fungi, are poorly understood, and the mechanisms by which earthworms affect microorganisms are challenging to study. First, given the widespread presence of earthworms, finding soils that have not been previously affected by earthworms is difficult. Second, controlled laboratory incubation experiments generally exclude certain functionally important groups of fungi such as plant-associated ectomycorrhizal (EcM) fungi. In our recently initiated project, we aim to study earthworm influence on soil fungal communities and associated soil biogeochemical processes by introducing soil-dwelling earthworms into to date yet uncolonised northern forest soils. Therefore, we established mesocosm boxes filled with soil turfs including tree saplings from northern boreal forests and placed them in an experimental forest in southern Sweden. Later on, we will introduce earthworms (Aporrectodea and Lumbricus spp) into the mesocosms and measure (depth specific) changes in microbial communities and genes using RNA and DNA sequencing. Potential microbial changes will be related to measurements of carbon and nitrogen cycling, such as carbon-dioxide flux measurements and soil mineral nitrogen content analysis in the growing season after earthworm introduction.

How to cite: Garamszegi, P., Clemmensen, K. E., Keller, T., Lindahl, B. D., and Krab, E. J.: Earthworm-microbe interactions: what can we learn from controlled earthworm introduction into boreal forest soil?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7303, https://doi.org/10.5194/egusphere-egu24-7303, 2024.

EGU24-7464 | Orals | BG3.15

Structure and functioning of soil animal food webs across temperate and tropical forests 

Anton Potapov, Sergey Thurikov, Stefan Scheu, and Alexei Tiunov

Soil biogeochemical cycles are regulated by soil food webs. However, variation of soil food web structure and functioning across key environmental gradients remains unknown, hampering generalisations of any suggested links between fauna and biogeochemistry. Here, we used two complementary approaches to quantify soil animal food web variation across forest types, from southern taiga to rainforests. First, we applied the energy flux approach to explore patterns of energy distribution across micro-, meso- and macrofauna. We showed that tropical soil food webs have consistently higher energy flux, proportionally higher predation rates (31 vs 18-27% of the total energy flux) and relied more on the plant energy channel (21 vs 10%), but less on the bacterial (5 vs 9-18%) and litter energy channels (14 vs 18-32%), than temperate soil food webs. Second, we compiled a large database (>8000 records) of stable isotope composition of soil animals to see how detritivory and microbivory in soil animal communities change with environmental temperature and litter quality. Despite little effect of temperature, shift in 15N concentrations suggested that in most cases low litter quality (high %C and low %N) result in a switch from feeding directly on litter to feeding on microorganisms. Thus, soil animals change their functional role from competitors to consumers of microbes. Our studies show how the functioning of soil animal food webs changes across biomes with different climate and litter quality and summarise functional roles animals play in different biomes.

How to cite: Potapov, A., Thurikov, S., Scheu, S., and Tiunov, A.: Structure and functioning of soil animal food webs across temperate and tropical forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7464, https://doi.org/10.5194/egusphere-egu24-7464, 2024.

EGU24-7897 | ECS | Orals | BG3.15

Trophic cascades in simplified soil food webs and consequences for carbon cycling 

Justine Lejoly, Yuxin Wang, Esther van Hoof, Valentin Favre, Casper Quist, Stefan Geisen, and Ciska Veen

The soil microbiome is widely recognized as an important driver of soil carbon (C) cycling but the role of soil fauna is largely overlooked. It is proven that microbivores, e.g., bacterivorous nematodes, can alter the microbiome composition and activity, but the microbivores themselves can be controlled by their predators. How these higher trophic interactions impact the soil microbiome, through trophic cascades, remains to be investigated, as well as the consequences for soil C cycling.

We tested the existence and direction of trophic cascades in soil food webs by manipulating the presence of bacterivorous-dominated nematode communities and their predators (nematode-feeding mite Gaeolaelaps aculeifer) in a full factorial design. After microbial re-inoculation of sterilized grassland soil and soil food web reconstruction, we monitored the decomposition of added grass litter and associated C mineralization during five weeks. We also characterized the soil microbiome composition by phospholipid fatty acid analysis and 16S sequencing.

While the presence of nematodes mostly did not affect C cycling, the addition of predators decreased C mineralization by 10 %. However, litter decomposition rates were unaffected by soil food web composition. Taken together, these results suggest that the presence of predators may result in enhanced soil C stabilization, at least in the short term. The presence of predators also resulted in a shift in microbiome composition, notably with higher Gram(+):Gram(-) ratios, but no change in microbial biomass, suggesting that nematodes may shift their diet because of predation. Our results confirm that the effects of nematodes and their predators on the soil microbiome are not additive and that predators can alter soil C cycling trough trophic cascades. As predators are often sensitive to land use change and intensification, these findings suggest that loss of belowground predators may result in increased C losses following litter decomposition.

How to cite: Lejoly, J., Wang, Y., van Hoof, E., Favre, V., Quist, C., Geisen, S., and Veen, C.: Trophic cascades in simplified soil food webs and consequences for carbon cycling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7897, https://doi.org/10.5194/egusphere-egu24-7897, 2024.

The most powerful tool to explore nutrient turnover in complex systems such as soils are stable isotope fractionation and labelling studies. This has been extensively used when investigating microbial carbon cycles by targeting the carbon stable isotopes in microbial phospholipid fatty acids (PLFA). However, exploring the role of mesofauna during carbon turnover in soil ecosystems has long been limited due to the small size and weight of those organisms and therefore issues in the detection and quantification of carbon stable isotope ratios. Only recently, carbon stable isotope analysis of fatty acids (FA) have been established and opened the window to include mesofauna into carbon turnover studies. We have used this new possibility after refining the available FA method to discover the role of microarthropods together with the microbial PLFA analysis. This study is to our knowledge the first, which has used 13C labelled plant material and has followed its incorporation into microbial PLFAs and microarthropodal FAs in a greenhouse experiment containing heavy metal contaminated and remediated soils.

Total microbial biomass and 13C incorporation into microorganisms was significantly increased and the PLFA pattern shifted after remediation of heavy metal contaminated soil. In accordance, the abundance of the microarthropodal groups Gamasina, Oribatida and Collembola were also increased, while Astigmata were not affected. The relative FA patterns of those groups differentiated significantly among each other, but were not influenced by soil treatment, meaning that the altered microbial PLFA pattern was not transferred into microarthropodal FA. However, the amount (nmol FA) per individuum was elevated in the heavy metal contaminated soil. In contrast, incorporation of 13C into FA was lower in contaminated soil in Gamasina, Astigmata and Collembola. 13C incorporation of Oribatida was at a constantly high level over the different soil treatments.

These first results revealed, that the relative FA pattern of the microarthropodal groups was not affected by changes in the microbial PLFA pattern due to soil treatments. Differences in the absolute FA amount per individuum and the 13C uptake were rather governed by the life and reproduction strategies, with higher fattiness and low abundance under adverse environmental conditions (contaminated soil), constant 13C incorporation in K-strategist (Oribatida) and higher 13C incorporation of mainly r-strategist (Gamasina, Astigmata and Collembola) under improved conditions.

How to cite: Watzinger, A., Christoph, N., Wissuwa, J., and Friesl-Hanl, W.: The role of microarthropodal groups in carbon turnover as revealed by 13C fatty acids analysis – method development and impact of heavy metal remediation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9456, https://doi.org/10.5194/egusphere-egu24-9456, 2024.

     Forested riparian buffer strips (FRBS) are common in temperate agroecosystems due to their ability to sequester nutrients from agricultural runoff and to sequester carbon. The full environmental benefits of FRBS can only be evaluated, however, by accounting for a wide range of criteria that go beyond stream water quality. For example, it is important to determine the net greenhouse gas (GHG) balance of FRBS relative to adjacent agricultural fields. It is also important to identify the factors controlling these GHG emissions in order to propose optimal FRBS designs that maximize their environmental benefits. One such factor is the spread of non-native earthworms, whose burrowing activities may modify soil emission rates of CO2, N2O and CH4. To test the effects of earthworms on GHG emissions, microcosm studies were conducted using a replicated factorial design comprising of three soil origins (deciduous FRBS, coniferous FRBS, agricultural field) × two soil textures (field conditions, high clay) × three EW life habits (anecic, endogeic, no earthworms). At different intervals over the course of a 10-week trial, we measured net CO2 emissions under aerobic conditions, as well as potential N2O emissions in microcosms amended with acetylene gas.  In a separate trial using the same experimental design, we measured gross production and consumption rates of CH4, in both aerobic and anaerobic conditions, using an 13CH4 isotope dilution technique. Anecic earthworms had a positive effect on soil CO2 and denitrification, which decreased after a few weeks. Increasing soil clay content had a negative effect on the emission of these two GHGs. Additionally, soils from FRBS emitted more CO2, N2O and CH4 than soils from agricultural fields. Gross CH4 consumption rates were greater under aerobic than aerobic conditions, especially under deciduous trees.  Results suggest that the inclusion of trees in riparian buffer strips combined with the introduction of non-native earthworm species could substantially increase GHG emissions of agroecosystems and mitigate the environmental benefits of FRBS.

(Note: The first and second authors contributed equally to this presentation).

How to cite: Boilard, G., Cameron, A., and Šimek, M.: The inclusion of trees and the introduction of non-native earthworms may increase greenhouse gas emissions from riparian buffer strips.  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9819, https://doi.org/10.5194/egusphere-egu24-9819, 2024.

EGU24-10318 | Posters on site | BG3.15

The Impact of Tree Species and Charcoal on Soil Fauna in Post-Fire Forest Ecosystems 

Thi Hong Van Tran, Agnieszka Józefowska, Bartłomiej Woś, Marcin Pietrzykowski, Tomasz Wanic, Rüdiger M. Schmelz, and Jan Frouz

Soil fauna, particularly enchytraeids and earthworms, play a crucial role as soil engineers, actively contributing to nutrient cycling through the breakdown and ingestion of litter material. These organisms engage in intricate interactions with microorganisms responsible for decomposing and mineralizing detritus. The present study seeks to delve into the complex interplay among tree species, charcoal presence, and soil fauna within post-fire forest ecosystems. The investigation took place in Rudziniec, Poland, a site that witnessed one of Europe's largest fires in 1992. Two delineated areas were observed: one with post-fire charcoal presence and another with removed charcoal. Four distinct tree species—pine (Pinus sylvestris L.), larch (Larix decidua Mill.), birch (Betula pendula Roth), and oak (Quercus robur L.)—were selected as representative species for the study. Samples were obtained from locations adjacent to the trees at a depth of 0-10 cm for echytraeids and at a depth of 0-25 cm for earthworms. The study elucidates the impacts of post-fire charcoal removal or retention on soil fauna across diverse tree species. When considering the various tree species, enchytraeid density was higher in coniferous trees (pine and larch) compared to deciduous trees (birch and oak). Among these, oak trees exhibited the highest enchytraeid species diversity, yet their density was lowest (60944 ind.m-2). Among experimental plots, in birch plots with post-fire charcoal retention, enchytraeid density was lowest (27470 ind.m-2); conversely, in charcoal removal plots, it showed the highest number with 105355 ind.m-2. Regarding earthworm biodiversity, a maximum of two species were observed across all plots. Earthworm density was lower in coniferous trees (12.65 ind.m-2 in pine and 10.67 ind.m-2 in larch) compared to deciduous trees (20.09 ind.m-2 in birch and 14.67 ind.m-2 in oak). With charcoal presence, earthworm density sharply decreased in coniferous trees while increasing in deciduous trees. A similar trend was observed in earthworm biomass. Among all experimental plots, the highest biomass value was found in pine trees with charcoal removal (4.54 g.m-2) whereas the lowest value with charcoal presence (0.35 g.m-2). These differences suggest an intricate relationship between post-fire charcoal management, tree species, and their consequential impact on soil fauna. The insights gathered from this study hold valuable implications for informing ecosystem management and restoration strategies, contributing to a more comprehensive understanding of the intricate dynamics within post-fire environments.

This research was funded by The National Science Centre, Poland, grant No. 2021/42/E/ST10/00248. The analyses were performed in the Laboratory of Forest Environment Geochemistry and Reclaimed Areas, University of Agriculture in Krakow.

How to cite: Tran, T. H. V., Józefowska, A., Woś, B., Pietrzykowski, M., Wanic, T., Schmelz, R. M., and Frouz, J.: The Impact of Tree Species and Charcoal on Soil Fauna in Post-Fire Forest Ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10318, https://doi.org/10.5194/egusphere-egu24-10318, 2024.

To understand carbon dynamics and how it is affected by ongoing climate change, we need a better appreciation of the belowground ecological interactions driving plant allocation patterns and ecosystem carbon fixation. It has become increasingly clear that belowground root inputs contribute significantly more to soil carbon sequestration than aboveground plant inputs. Yet, current understanding of the role of belowground root herbivory in ecosystem carbon dynamics is weaker than that of aboveground herbivory. We addressed this gap by merging three complementary and novel areas of research, namely testing how: (1) biotic interactions between plants and nematode herbivores affect belowground biomass allocation in grasses; (2) how these biotic interactions and their consequences for biomass allocation are modified by a pervasive perturbation, namely drought, which is becoming more intense and frequent; and (3) how belowground responses vary across contrasting ecosystems. Results of complementary controlled and multi-site field experiments showed that: (1) nematode root herbivory modulates the relationship between water availability and belowground biomass allocation; (2) drought-induced increases in nematode root herbivory impede plants from increasing biomass allocation to roots under drought; and (3) these nematode effects are greater in magnitude in mesic compared to semiarid and arid grasslands. These findings suggest that the fate of carbon in mesic ecosystems under increasing drought frequency is highly influenced by nematode herbivores in the soil, and encourage investigations into the unknown consequences for soil carbon formation and persistence.

How to cite: Franco, A. and Gherardi, L.: The influence of belowground nematode herbivory on carbon allocation in drought-prone ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10509, https://doi.org/10.5194/egusphere-egu24-10509, 2024.

EGU24-11070 | ECS | Orals | BG3.15

Increased N2O emissions by the soil nematode community cannot be fully explained by enhanced mineral N availability 

Junwei Hu, Meng Kong, Astrid Françoys, Farideh Yarahmadi, Orly Mendoza, Ummehani Hassi, Mesfin T. Gebremikael, Wim Wesemael, Steven Sleutel, and Stefaan De Neve

Soil nematodes, being the most abundant soil fauna, can significantly impact soil N mineralization via interaction with soil microorganisms. As a consequence, nematodes likely also influence soil N2O production and emissions but the very few studies on this matter were carried out in simplified setups with single nematode species and in (highly) disturbed soil conditions. Here we measured soil N2O emissions in a 74-day incubation experiment in the presence or absence of the entire soil nematode community with minimal disturbance of the soil microbial community and soil nutrients. This was e.g. evidenced by readily recovery of nitrifiers after the mild and selective sterilization and soil powder inoculation. N2O emissions increased in the presence of nematodes, varying between soils +747.7 % in a loamy sand, +55.8 % in a loam, and +51.9 % in a silt loam cropland topsoil, in line with nematode abundance in these soils. In particular, the loamy sand soil showed an atypical N2O emission peak at the time of high nematode abundance. Soil nematodes also increased net N mineralization by +8.4, +6.8 and +4.75 %, in these respective soils and to a smaller extent C mineralization as well. The extra soil nitrate buildup and the overall net stimulation of N mineralization by nematodes could not or just slightly explain the observed increased N2O emissions. This research revealed the important role of soil nematodes in regulating N2O emissions, and further stresses the need to consider the change in community composition and activity of denitrifiers, and connectivity of soil pores, rather than the stimulation of N mineralization as potential explanations for this role of nematodes.

How to cite: Hu, J., Kong, M., Françoys, A., Yarahmadi, F., Mendoza, O., Hassi, U., Gebremikael, M. T., Wesemael, W., Sleutel, S., and De Neve, S.: Increased N2O emissions by the soil nematode community cannot be fully explained by enhanced mineral N availability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11070, https://doi.org/10.5194/egusphere-egu24-11070, 2024.

EGU24-16422 | ECS | Posters on site | BG3.15

Unraveling the structure and function of soil food webs using an untargeted lipidomics approach 

Rahul samrat and Wolfgang wanek

Belowground (soil) communities are highly diverse and encompass higher plants, bacteria, fungi, protists, invertebrates and vertebrates. The feeding relationships are as diverse, ranging from symbiotic associations (e.g. mycorrhizae), saprotrophs, grazers, shredders, predators and parasites. These material flows underly the biogeochemical functions of soils, driving organic matter decomposition, soil carbon sequestration, nutrient recycling and greenhouse gas emissions. Despite the importance of understanding the structure and dynamics of such complex soil food webs we are still lacking quantitative and detailed approaches to characterize them. Recently lipidomics analysis of intact polar lipids of soil communities has emerged indicating its potential to allow disentangling the food web structure beyond just abundances of bacteria and fungi based on phospholipid fatty acids or amplicon sequencing data, but extending this analysis across the whole soil food web including its base, higher plants, and including higher consumer levels with diverse protists and invertebrates Our study introduces and develops an untargeted lipidomics platform, employing reversed-phase liquid chromatography and electrospray ionization tandem mass spectrometry (UPLC ESI Orbitrap MS), to examine the intact polar lipidomes of soil biota. With advanced high resolution mass spectrometry and a newly adopted bioinformatics toolbox, we analyze lipidomes from complex soil communities and from pure cultures and single species, including plants, archaea, bacteria, fungi, protists (amoebozoa, ciliophora, cercozoa, etc.), collembola, mites, nematodes, and other soil fauna, as well as their diets. Our workflow facilitates the rapid identification and quantification of thousands of unique intact polar lipid molecules, representing a variety of biological classes, which we currently analyze for their biomarker potential, for being indicative for the presence and activity of specific groups of soil organisms. Utilizing this method of biomarker analysis, finally in combination with isotopic tracing into the fatty acyl residues (containing carbon, hydrogen and oxygen) and the lipid head groups (containing additionally nitrogen, sulfur and phosphorus), is expected to provide valuable quantitative insights into the structure of soil food webs and their activity and matter transfer, by following the incorporation and transfer of isotopically labeled matter and how this responds to climate and land use change. Thereby we foresee to improve our understanding of the contributions made by soil organisms to the stability and function of soil ecosystems, thus providing a foundation for ongoing ecological and environmental research.

How to cite: samrat, R. and wanek, W.: Unraveling the structure and function of soil food webs using an untargeted lipidomics approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16422, https://doi.org/10.5194/egusphere-egu24-16422, 2024.

Earthworms may act as double-edged swords for soil organic matter (SOM). While they can enhance organic matter (OM) mineralization via increased microbial activity they can also elevate OM stabilization in aggregates as particulate or mineral-associated OM. In this study, we are testing this potentially opposing impact in beech-dominated (Fagus sylvatica L.) mixed forests on limestone, a forest ecosystem with particularly high earthworm activity. A specific focus lies on OM transformation along the continuum from the forest floor (O horizons) to mineral soil (A horizons). The forest floor can represent a substantial OM-pool which is an important source for SOM formation via bioturbation or leaching but can be vulnerable to alterations due to climate change. In a lab mesocosm experiment, we are incubating local earthworm species in soil columns consisting of O and A horizons from two contrasting beech forest sites from 600 and 1250 m elevation in the Swiss Jura Mountain range. Both sites have a mull-type forest floor with the high-elevation site exhibiting an Of horizon present throughout the year while an Of horizon is not present all year at the low-elevation site. We established four earthworm treatments for each site all including the respective mineral soil and forest floor: (1) no earthworms, (2) two Octolasion cyaneum S., (3) one Lumbricus terrestris L., and (4) two O. cyaneum together with one L. terrestris. In this setup, the Ol horizon was replaced with beech litter highly enriched with 13C, 15N, and 2H. Soil respiration (CO2) and leaching (C, N, and H in dissolved OM) are repeatedly measured. Total respiration (12C and 13C) is measured weekly for the first four months and biweekly afterward. Every two months fluxes from A and O horizons are measured separately. After approximately 4 and 10 months each, a set of mesocosms is harvested to investigate isotope enrichment in earthworm biomass, cast, physical soil fractions, PLFAs, and microbial necromass. We find first indications for stabilization of new litter input as, under similar total CO2 fluxes, the litter-derived fraction is higher for treatments without worms. However, if both earthworm species are present, the cumulative heterotrophic respiration is elevated compared to the treatments involving only one earthworm species and the no-earthworm treatment. This is presumably due to higher earthworm density and, therefore, increased bioturbation. In contrast, we find no differences in the amount of dissolved organic matter leached out of the mesocosms between the treatments so far. X-ray CT scans will inform us about earthworm behavior within the mesocosms. This will help us understand how their activity translates into the vertical distribution of the isotopic label.

How to cite: de Jong, P., Schleppi, P., and Hagedorn, F.: The role of earthworms in the organic matter cycling of forest floors in temperate forests – A mesocosm experiment with labeled beech litter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18389, https://doi.org/10.5194/egusphere-egu24-18389, 2024.

Soils harbor a diverse fauna, ranging in size from <200 µm to several cm. These animals are direct producers of greenhouse gas (GHG) emissions via their respiratory and metabolic activities and can indirectly change soil carbon and nitrogen cycling by changing physical, chemical and biological soil properties, e.g. through bioturbation, defecation, herbivory, and litter fragmentation and redistribution. In addition, they can create microhabitats which offer more favorable conditions to microorganisms than bulk soil. Thus, soil fauna is able to substantially effect the spatial and temporal variability of GHG fluxes in ecosystems. However, emissions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from and associated with soil fauna remain poorly quantified and have been limited to only a few regions and species. The literature review presented here gives an overview of GHG emission studies addressing soil fauna taken place since 2010. For each GHG (CO2, CH4 and N2O) the keywords “emission* OR flux*” were combined with keywords querying different soil fauna groups. The initial search using the databases Web of Science Core Collection and Lens.org resulted in 282 and 531 journal articles, respectively, of which 165 studies were duplicates. This literature (n = 648) is being screened according to the following categories: i) location of study (geographical location, field, laboratory), ii) soil type, iii) ecosystem type, iv) species, v) GHG fluxes, and vi) methodologies (flux measurements, species monitoring). Based on this, the current state of knowledge, research gaps and methodological challenges will be identified to provide ideas and guidance for the design of future research projects trying to further our understanding of the quantitative role of soil fauna in the soil carbon and nitrogen cycle in natural and managed ecosystems.

How to cite: Görres, C.-M.: Greenhouse gas (CO2, CH4, N2O) emissions from soil fauna – what have we learned over the past decade?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18778, https://doi.org/10.5194/egusphere-egu24-18778, 2024.

EGU24-978 | ECS | Orals | HS8.3.3

What impacts the soil moisture dynamics in the near-natural beech forest? 

Alina Azekenova, Karl-Heinz Feger, and Stefan Julich

Soil moisture in forested regions displays considerable spatial and temporal variability within the soil-plant interaction. The high frequency of drying and wetting cycles exacerbates the uncertainty in this already complex relationship. Recent studies in forest hydrology have frequently postulated that soil physical properties and precipitation partitioning induce soil water content (SWC) variability. However, in-situ evidence for this linkage is scarce. To support the notion of SWC patterns corresponding to these two elements, a transect-based method was utilised. It clarifies the variation in soil moisture on a small scale and facilitates the identification of specific patterns with the distance from the tree stem. An intensive monitoring of SWC (52 profiles) and precipitation, including throughfall and stemflow, has been carried out in the near-natural beech forest in north-eastern Germany since 2022. It covers three study sites that are stocked over a terminal moraine and are classified as wet, intermediate and dry on the basis of the soil moisture gradient. The result stipulates increase of the SWC away from the stem during drying cycles at the dry study site. However, this appears to be the reverse for the wet site. During the wetting phase, soil moisture at intermediate and dry sites exhibited homogeneous variation, although the wet site experienced an increase in soil moisture by stem distance. Therefore, uncovering the distance from stem, root density distribution and canopy structure as possible controlling factors.  It is concluded, that within soil-plant interaction both soil physics and precipitation define the patterns of soil moisture variation during wetting cycles. Conversely, soil retention characteristics mainly anticipate water fluxes in the soil during drying periods.

How to cite: Azekenova, A., Feger, K.-H., and Julich, S.: What impacts the soil moisture dynamics in the near-natural beech forest?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-978, https://doi.org/10.5194/egusphere-egu24-978, 2024.

EGU24-1452 | ECS | Orals | HS8.3.3

The biomechanics of path of least resistance of roots in heterogeneous substrates 

Jiaojiao Yao, Jonathan Barès, Evelyne Kolb, and Lionel Dupuy

Rooting depth is critical for plants to acquire water and nutrient efficiently. However, when progressing deeper into the soil, a growing root must overcome physical obstacles such as stones and zones with different mechanical impedance (like hard pans and aggregates) which results in tortuous trajectories and a reduced ability to reach deeper soil horizons. We have developed different model systems which consists of roots growing in artificial substrates made of a customized arrays of stiff or deformable obstacles which the root can either bypass or penetrate based on the resistance of the obstacle. High-throughput imaging systems were used to capture time lapse data and image analysis techniques were used to track root responses to obstacles. In the presence of rigid obstacles, only a limited number of growth responses were observed with a transition from vertical to oblique trajectories observed as a function of size and distance between physical obstacles. When obstacles were deformable the likelihood of penetration could be predicted from factors such as the incidence angle, the length of the root that can bend freely, and the degree to which previous obstacles compress and anchor its base. Overall, our results showed that primary root growth in heterogeneous substrates is largely deterministic and can be predicted from the maximum curvature a root can bend, the spatial arrangements of obstacles and the mechanical stress anchoring the base of the root.

Keywords: root, soil, mechanical impedance, heterogeneity, biomechanics

How to cite: Yao, J., Barès, J., Kolb, E., and Dupuy, L.: The biomechanics of path of least resistance of roots in heterogeneous substrates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1452, https://doi.org/10.5194/egusphere-egu24-1452, 2024.

EGU24-2130 | ECS | Posters on site | HS8.3.3

The relationship between volatile organic compounds and apple replant disease 

Anne-Sophie Wachter, Alain Tissier, Esther Armah Harding, and Doris Vetterlein

Apple replant disease (ARD) refers to the observed decline in plant growth, fruit yield, and quality after repeated planting of apples at the same site. It is a phenomenon in all apple-producing areas worldwide which leads to an estimated profitability reduction of 50 % over the lifetime of an apple orchard. Up to now, the mechanisms behind ARD are only poorly understood. It has been attributed to the action of a site-specific, multi-kingdom, pathogenic, and parasitic biological complex. Thus, the soil faces (micro-) biome alterations due to previous apple cultures.

Upon initial contact, apple roots can detect and avoid soil affected by ARD. So far, it is not known how the roots can sense ARD in soil. Volatile organic compounds (VOCs) are promising candidates as communicators between soil and plant. It is known that VOCs mediate many cases of plant responses to pests or pathogens. Nevertheless, their role in ARD has so far been neglected.

A rhizobox experiment was set up to determine the volatile emission of apple plantlets growing in ARD and non-ARD soil. Volatiles are analyzed using untargeted gas chromatography-mass spectrometry with prior concentration on an adsorbents (here: stir bar sorptive extraction, SBSE) and thermodesorption.

This first pre-experiment run with the interpretation of the gas chromatogram as the next step. Our aim is to determine whether there are any differences between the volatiles detected in the close proximity of apple roots growing in ARD and in non-ARD soil. Noticeable VOCs will be identified to specify the occurring volatile profiles.

We will examine the potential role of VOCs as communicators between plants, the microbiome, and soil. It will be addressed whether the sensing of ARD is related to volatile production.

How to cite: Wachter, A.-S., Tissier, A., Harding, E. A., and Vetterlein, D.: The relationship between volatile organic compounds and apple replant disease, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2130, https://doi.org/10.5194/egusphere-egu24-2130, 2024.

EGU24-3544 | ECS | Posters on site | HS8.3.3

Sorghum water use efficiency and yield variations discerned by 13C isotopic technique under managed agricultural practices in Upper Eastern Kenya 

Jane Omenda, Milka Kiboi, Felix Ngetich, Gerd Dercon, Monicah Mucheru-Muna, Jayne Mugwe, Said Ahmed Hami, Fabian Kaburu, Samuel Nii Akai Nettey, Daniel Mugendi, Roel Merckx, and Jan Diels

Current knowledge on using 13C discrimination as an indirect measure of yield and water use efficiency (WUE) under different soil moisture conditions and soil fertility inputs in C4 crop species has considerable uncertainty. The objective of this study was to test for (i) the effect of selected soil water conservation measures and soil fertility inputs on sorghum yield, water use efficiency, and 13C discrimination, (ii) evaluate the relationship between various measures of water use efficiency and 13C discrimination, between sorghum yield and 13C discrimination; (iii) sorghum stem diameter and WUE and, the use of stem diameter and 13C discrimination as potential yield and WUE proxy. We implemented a field trial on-station for five seasons in the semi-arid areas of Upper Eastern Kenya. The experiment was designed in a randomized complete block design (RCBD) with three levels of nitrogen fertilization (120 kg ha−1, 60 kg ha−1, and 30 kg ha−1) application with four replications. The selected soil water conservation measures and soil fertility management were minimum tillage, mulching, tied ridging, and Managing Beneficial Interactions in Legume Intercrops (MBILI) along a control (no input). Water use efficiency was determined using carbon discrimination analysis and gravimetric technique. The leaves and post-harvest grain samples were analyzed for %N, %C, and δ13C on an Isotope Ratio Mass Spectrometer (IRMS). A clear and significant (p≤ 0.05) treatment effect was observed on the 13C isotopic discrimination and sorghum yield and growth attributes over the five seasons. The highest (4.85 Mg ha-1) grain yield was observed with minimum tillage with crop residue treatment. The δ13C values ranged from -13.14to -11.86‰for the sorghum grain. Treatments under minimum tillage with residue and tied ridges and the MBILI intercrop had significantly (p≤ 0.05) higher sorghum grain yield, WUE, stem diameter, chlorophyll content, and high δ13C values. The 13C discrimination was significantly (p≤ 0.05) associated with yield, WUE, stem diameter, and leaf chlorophyll. In the treatment with high N rate, the equation relating 13C discrimination to yield was Yield (Mg ha-1) = 1.4822δ13C + 20.879; R² = 0.3518. A significant positive relationship (R2 = 0.31) was observed between grain N fertilizer use efficiency and grain δ13C in sorghum harvested from plots with high N rate treatments. There was also a correlation (R2 = 0.341; p=0.001) between WUE and sorghum stem diameter. Based on these results, we conclude that grain 13C discrimination values at maturity and stem diameter are a potential complementary criterion for assessing sorghum yield performance and WUE under different soil moisture and nutrient availability conditions. Therefore, it can be deduced that minimum tillage with crop residue with a high fertilizer application rate (120N/ha) improves sorghum grain yield, WUE, and higher grain δ13C values. The high grain δ13C values observed with minimum tillage with crop residue over the five seasons indicate that plants suffered less water stress under minimum tillage with crop residue treatment. Therefore, grain δ13C discrimination and stem diameter can be used as water use efficiency proxy with C4 crops like sorghum.

How to cite: Omenda, J., Kiboi, M., Ngetich, F., Dercon, G., Mucheru-Muna, M., Mugwe, J., Hami, S. A., Kaburu, F., Nettey, S. N. A., Mugendi, D., Merckx, R., and Diels, J.: Sorghum water use efficiency and yield variations discerned by 13C isotopic technique under managed agricultural practices in Upper Eastern Kenya, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3544, https://doi.org/10.5194/egusphere-egu24-3544, 2024.

EGU24-3773 | ECS | Orals | HS8.3.3

Individual versus combined effects of drought, warming and eCO2 on grassland water uptake and fine roots 

Maud Tissink, Jesse Radolinski, David Reinthaler, Sarah Venier, Erich M. Pötsch, Andreas Schaumberger, and Michael Bahn

In a changing climate, grasslands are expected to experience major shifts in water supply and demand. To date, little is known about how projected future conditions of severe drought, climate warming, and rising CO2 affect grassland water uptake, and whether adaptations of fine roots affect the capacity to extract water from soil. Using a multifactor global-change experiment in a managed montane C3 grassland, we studied the individual and combined effects of drought, warming (+3 ℃), and elevated CO2 (eCO2; +300 ppm) on root water uptake (RWU) over three growing seasons. RWU was assessed across different layers of the main rooting horizon using diel soil moisture dynamics during non-rain periods. We also investigated treatment effects on fine roots (production, traits), fine-root-to-shoot ratios, and consequences for RWU capacity. By increasing vapour pressure deficit (VPD) and its effect on RWU rates normalized to soil water content (RWUSWC), warming reduced RWU during hot periods. Under sustained warming, grassland decreased specific root length, and increased root diameters and fine-root-to-shoot ratios. Conversely, eCO2 slowed RWUSWC at high VPD, though fine-root adaptations were negligible. Compared to warming alone, future conditions (warming, eCO2) increased RWUSWC to a lesser extent and induced no fine-root adaptations, but reduced RWU to a similar degree. Drought reduced RWU (-66–75%) and increased water sourcing from deeper soil layers; however, a hot season amplified any RWU reductions under future conditions by 20%. Altogether, our study demonstrates that (i) RWU in C3 grasslands declines in a warmer, drier future, though (ii) eCO2 will mitigate the need for fine-root adaptations, maintaining RWU capacity. However, (iii) rising temperatures will exacerbate RWU reductions under drought. Therefore, hot droughts should have significant repercussions for water dynamics in C3 grasslands.

How to cite: Tissink, M., Radolinski, J., Reinthaler, D., Venier, S., Pötsch, E. M., Schaumberger, A., and Bahn, M.: Individual versus combined effects of drought, warming and eCO2 on grassland water uptake and fine roots, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3773, https://doi.org/10.5194/egusphere-egu24-3773, 2024.

EGU24-5513 | Posters on site | HS8.3.3

Effect of adaptive rootzone development in quantitative land evaluation studies 

Martin Mulder, Marius Heinen, and Mirjam Hack-ten Broeke

For quantitative land evaluation studies often simulation models are used to determine differences between soil types in terms of water availability (actual transpiration) or crop productivity. In the Netherlands we developed a land evaluation system specifically for water authorities, provinces and drinking water companies. The system allows answering questions on how water management influences crop development due to too dry or too wet conditions in the unsaturated zone. This system is based on the linked simulation model SWAP (Soil-Water-Atmosphere-Plant) and WOFOST (WOrld FOod STudies). The impact of changes in climate or hydrology can then be studied in terms of effects on crop growth and farm income.

Although SWAP and WOFOST are process based models, the rootzone development is simulated in a straightforward way: the development of the root extension is specified by the user in advance and the root length density distribution is assumed static in time. Roots play a key role in the interaction between soil water and crop growth and crop yield simulation. Although plant roots are highly adaptable, their adaptability is often neglected in simulation models that are used for predicting impacts on yield. For a more realistic approach we implemented a simple and innovative root growth model which will react on the hydrological conditions within the rootzone. This means that newly formed roots will be assigned to regions where there is no or the least stress, and less or no new roots to regions where water stress was experienced. As a result the drought and oxygen stress will be less dependent on the initial root distribution as specified by the user.

The model performance of the adaptive root growth model is compared with a rhizobox experiment where the root growth of maize was tracked while influencing soil moisture conditions at the same time (Maan et al., 2023). An example for a regional study will be provided to show the relevance of adaptive rootzone development for assessing land qualities in space and time.

How to cite: Mulder, M., Heinen, M., and Hack-ten Broeke, M.: Effect of adaptive rootzone development in quantitative land evaluation studies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5513, https://doi.org/10.5194/egusphere-egu24-5513, 2024.

The functional role and genetic control of many root anatomical and architectural traits are poorly understood. Our research focuses on characterizing root traits for enhanced stress tolerance and identifying genetic mechanisms controlling the expression of root traits. We have identified a candidate gene for root cortical aerenchyma formation which mapped to a root cortex-expressed bHLH transcription factor gene. A bHLH121 Mu transposon mutant line and a CRISPR/Cas9 loss-of-function mutant exhibited reduced root cortical aerenchyma formation, whereas an overexpression line exhibited significantly greater root cortical aerenchyma formation when compared to the wildtype line in many environments. Overall functional validation of the bHLH121 gene’s importance in root cortical aerenchyma formation provides a functional marker to select varieties with improved soil exploration and thus yield. Characterization of these lines under suboptimal water and nitrogen availability in multiple soil environments revealed root cortical aerenchyma is plastic in response to abiotic stress. Our results suggest that phenotypic plasticity is highly quantitative and plasticity loci are distinct from loci that control trait expression in stress and non-stress conditions. The identification of genes and functional phenotypes of root traits will facilitate efforts for the development of novel nutrient and water efficient crop varieties.

How to cite: Schneider, H.: Genetic Control and Phenotypic Plasticity of Root Cortical Aerenchyma in Maize, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6403, https://doi.org/10.5194/egusphere-egu24-6403, 2024.

EGU24-7315 | Orals | HS8.3.3

From hydraulic root architecture models to efficient macroscopic sink terms  

Daniel Leitner, Andrea Schnepf, and Jan Vanderborght

Root water uptake strongly affects soil water balance and plant development. It can be described by mechanistic models of soil-root hydraulics based on soil water content, soil and root hydraulic properties, and the dynamic development of the root architecture. Recently, novel upscaling methods have emerged (Vanderborght et al. 2023, 2021), which enable the application of detailed mechanistic models on a larger scale, particularly for land surface and crop models, by using mathematical upscaling.

In this study, we explore the underlying assumptions and the mathematical fundamentals of the upscaling approach. Our analysis rigorously investigates the errors introduced in each step during the transition from fine-scale mechanistic models, which considers the nonlinear perirhizal resistance around each root, to more macroscopic representations. Upscaling steps simplify the representation of the root architecture, the perirhizal geometry, and the soil spatial dimension and thus introduces errors compared to the full complex 3D simulations. In order to investigate the extent of these errors, we perform simulation case studies: spring barley as a representative non-row crop and maize as a representative row crop, and using three different soils.

We show that the accuracy of the upscaled modeling approach strongly differs, depending on  root architecture and soil type. Furthermore, we identify the individual steps and assumptions that lead to the most important losses in accuracy. An analysis of the trade off between model complexity and accuracy provides valuable guidance for selecting the most suitable approach for specific applications.

 

References 

Vanderborght, J., Couvreur, V., Meunier, F., Schnepf, A., Vereecken, H., Bouda, M., and Javaux, M. (2021). From hydraulic root architecture models to macroscopic representations of root hydraulics in soil water flow and land surface models. Hydrology and Earth System Sciences, 25(9):4835–4860.

Vanderborght, J., Leitner, D., Schnepf, A., Couvreur, V., Vereecken, H., and Javaux, M. (2023). Combining root and soil hydraulics in macroscopic representations of root water uptake. Vadose Zone Journal, e20273.

How to cite: Leitner, D., Schnepf, A., and Vanderborght, J.: From hydraulic root architecture models to efficient macroscopic sink terms , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7315, https://doi.org/10.5194/egusphere-egu24-7315, 2024.

EGU24-7397 | Posters on site | HS8.3.3

Upscaling of 3D root hydraulic architectures of trees to 1D root hydraulic models 

Jan Vanderborght, Juan Baca Cabrera, Guillaume lobet, Daniel Leitner, Mathieu Javaux, Valentin Couvreur, and Andrea Schnepf

Root systems of trees are obviously much larger than those of herbaceous plants. Considering a root length of 30 km of roots below a surface area of 1m2 in a forest and considering that the root system of a single tree extends over a horizontal area of 10 m², this would mean that a root system of one tree is 300 km long. To simulate the water flow in the root system, the root system is typically discretized in 1cm long root segments and a set of flow equations is setup and solved to derive the water potential and flux in each segment of the 3D root hydraulic architecture. For a system with n root segments and n+1 nodes at which segments are connected, this results in a set of n equations that need to be solved. Solving this set of equations corresponds with inverting an n by n matrix. For the root system of a tree, the size of this matrix would be 3 107 by 3 107. The linear equation matrix is sparse and could be solved using equation solvers that do not calculate the inverse matrix. But, also these solutions might still be too expensive so that an upscaled and reduced set of equations is needed. We developed an approach to upscale flow equations in root hydraulic architectures (Vanderborght et al., 2021), which were subsequently coupled to non-linear flow equations that account for resistance to flow in the soil around root segments (Vanderborght et al. 2023). But, these upscaling approaches require an inversion of the linear equation matrix. In order to address this problem, we developed an inversion method that uses the hierarchical structure of the root network to divide the inversion into a set of smaller inversion problems that can be solved in parallel. In this presentation, we outline the principle of the inversion method and demonstrate it for large root systems of trees.

 

References

Vanderborght, J., et al. (2021) From hydraulic root architecture models to macroscopic representations of root hydraulics in soil water flow and land surface models. Hydrol. Earth Syst. Sci., 25(9), 4835-4860. https://doi.org/10.5194/hess-25-4835-2021

 Vanderborght, J., et al. (2023). Combining root and soil hydraulics in macroscopic representations of root water uptake. Vadose Zone Journal, n/a(n/a), e20273. https://doi.org/https://doi.org/10.1002/vzj2.20273

How to cite: Vanderborght, J., Baca Cabrera, J., lobet, G., Leitner, D., Javaux, M., Couvreur, V., and Schnepf, A.: Upscaling of 3D root hydraulic architectures of trees to 1D root hydraulic models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7397, https://doi.org/10.5194/egusphere-egu24-7397, 2024.

EGU24-7991 | ECS | Orals | HS8.3.3

Evolution of root hydraulic properties of wheat with breeding and its influence on root water uptake: insights from a field experiment and modelling 

Juan C. Baca Cabrera, Jan Vanderborght, Dominik Behrend, Thomas Gaiser, Thuy Huu Nguyen, Yann Boursiac, and Guillaume Lobet

Root water uptake is a pivotal process in the regulation of water movement within the soil-plant-atmosphere continuum. At a specific atmospheric demand, root water uptake is determined by the architecture of the root system and the hydraulic properties of individual roots and root segments. In agricultural settings, root traits are affected by management practices, including breeding. Specifically for wheat, the most important European crop, a decrease in root system size has been observed in modern varieties compared to historical ones1, and differences in root hydraulic properties between cultivated and wild species have been documented2. However, an assessment on the long-term evolution of root hydraulic properties with breeding is still absent.  

Here, we investigated the effect of breeding on root hydraulic properties of wheat and its implications for root water uptake at the plant scale. For this, an experiment encompassing six wheat cultivars spanning over a century of breeding history was conducted. We measured the number of root axes (crown roots and seminal roots) of plants grown in the field during the tillering phase (BBCH <30) and the root hydraulic conductivity of young plants grown in hydroponics (<12 days, no crown roots), using the pressure chamber technique.

Average root hydraulic conductivity (per root surface area) did not differ among cultivars, but a pronounced decrease in the number of root axes was observed in the most recent cultivars. Based on these observations, simulations with the whole-plant 3-D model CPlantBox were performed, indicating a higher whole-root system conductance in the oldest cultivars at the end of the tillering phase, associated with a higher number of tillers and root axes. This suggests an evolution of wheat cultivars towards more conserving root water uptake strategies, a feature of special importance under water-limited conditions.

 

References 

  • 1Zhao et al. (2005). 10.1111/j.1744-7909.2005.00043.x
  • 2Fradgley et al. (2020). 10.1007/s11104-020-04585-2 

How to cite: Baca Cabrera, J. C., Vanderborght, J., Behrend, D., Gaiser, T., Nguyen, T. H., Boursiac, Y., and Lobet, G.: Evolution of root hydraulic properties of wheat with breeding and its influence on root water uptake: insights from a field experiment and modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7991, https://doi.org/10.5194/egusphere-egu24-7991, 2024.

EGU24-8276 | Posters on site | HS8.3.3

Inter-row soil management affecting the soil-plant-water system in vineyard  

Ágota Horel, Levente Czelnai, Tibor Zsigmond, Imre Zagyva, and Csilla Farkas

The objectives of the study was to 1) investigate soil-plant-water interactions based on field measurements of plant reflectance and soil water content (SWC) in different inter-row managed vineyards, and 2) modeling changes in the SWC due to differences in soil physical parameters among slope positions and management methods. The study explored the impact of three different soil management practices on grapevine growth and soil health in vineyards: tilled (T), cover crops (CC), and perennial grass (NT) inter-rows. Data was collected for 2022 and 2023. At each study slopes, we had two measurement points along a slope section. To continuously monitor soil water and temperature conditions, sensors were strategically positioned at two depths of 15 cm and 40 cm below the soil surface along the slopes, both at the upper and lower points of the vineyard, while topsoil SWC was measured bi-weekly. Normalized Difference Vegetation Index (NDVI) and Photochemical Reflectance Index (PRI) sensors were used to measure leaf reflectance, while handheld instruments were used to measure additional NDVI and leaf Chlorophyll contents (SPAD). For the hydrological modeling we used SWAP (Soil-Water-Atmosphere-Plant), where the rswap R-package was used for calibration (2020 15 and 40cm data), validation (2021 15 and 40cm data), and statistical evaluation.

In 2022, all three slopes showed a significantly higher SWC content for the higher points compared to the lower, while in 2023 the grassed slope upper point showed higher SWC (0.18 vs 0.15%). The highest NDVI values were measured for the cover cropped vineyard site (0.68). However, we found no significant differences among NDVI values based on inter-row management or slope position, only the grassed inter-row vineyard had differences in the NDVI values at the lower and upper points (p=0.034). The highest leaf chlorophyll contents were measured for the cover cropped vineyard site (305). Most of the leaf Chlorophyll values were not significantly different among slope positions. Using the SWAP model, data from the cover cropped inter-row vineyard was used for calibration and validation. We found good model fitting (NSE > 0.52; d_daily > 0.81). Reduced-tillage (RT) and drought tolerant plant (DTP) management scenarios were run to simulate SWC changes over time. Preliminary data shows that DTP significantly reduced, while RT did not significantly affect our site’s SWC.

Acknowledgments: This material is based upon work supported by the Hungarian National Research Fund (OTKA/NKFI) project OTKA FK-131792. The research presented in the article was carried out within the framework of the Széchenyi Plan Plus program with the support of the RRF 2.3.1 21 2022 00008 project.

How to cite: Horel, Á., Czelnai, L., Zsigmond, T., Zagyva, I., and Farkas, C.: Inter-row soil management affecting the soil-plant-water system in vineyard , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8276, https://doi.org/10.5194/egusphere-egu24-8276, 2024.

EGU24-9160 | ECS | Posters on site | HS8.3.3

Impact of drought on Sentinel-2 derived winter wheat growth dynamics and the relation to soil properties 

Hanna Sjulgård, Lukas Graf, Tino Colombi, Juliane Hirte, Thomas Keller, and Helge Aasen

Drought can severely limit plant growth, and in turn crop productivity, and poses challenges to global food production. Plant growth can be measured with the Green Leaf Area Index (GLAI), and satellite images offer opportunities to estimate GLAI at field and landscape scales. Analysing satellite-estimated GLAI development at the landscape level could reveal new insights into how soil characteristics influence crop performance under various weather conditions, which in turn could provide information on how to mitigate the impacts of extreme weather. In this study, we quantified winter wheat growing patterns in two years with contrasting weather conditions (2018: early summer drought; 2021: normal growing conditions) on farmers’ fields using Sentinel-2 derived GLAI, and assessed the impacts of drought on GLAI dynamics. Moreover, we tested whether soil properties can explain differences in GLAI dynamics between a dry and a normal weather year.

Sentinel-2 scenes were downloaded from Microsoft Planetary Computer and the radiative transfer model PROSAIL was used to estimate GLAI throughout the winter wheat vegetative growing season on farmers’ fields in the south of Sweden. Characteristic GLAI parameters such as growth rate, area under the curve, peak GLAI and timing of the peak were calculated from the GLAI time series. The impact of drought on winter wheat growth was assessed by comparing the GLAI parameters between the dry year 2018 with the normal weather year 2021. In addition, the GLAI parameters were related to several biological, chemical and physical soil properties measured on the farmers’ fields.

The results showed lower GLAI parameters during the dry year compared to the normal weather year on the farmer’s fields. For some fields, there was a large difference between the years while for other fields a smaller difference. Plant available water content was found as the most important soil property in explaining the differences in GLAI parameters between the years. Our study demonstrates that satellite image analysis of GLAI dynamics can be used to identify plant stress responses on farmer’s fields. By analysing a dry and a normal year, we show that the impacts of drought can vary considerably between fields, and by combining GLAI estimates with measurements of soil properties, we identified plant available water content as a key soil property to explain differences between years. Thus, our results contribute to knowledge towards developing soil management strategies to mitigate the impacts of extreme weather.

How to cite: Sjulgård, H., Graf, L., Colombi, T., Hirte, J., Keller, T., and Aasen, H.: Impact of drought on Sentinel-2 derived winter wheat growth dynamics and the relation to soil properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9160, https://doi.org/10.5194/egusphere-egu24-9160, 2024.

The SWAP model allows studying the behavior of agricultural systems at different spatial and temporal scales, addressing climate change adaptation and mitigation issues.

In recent years, it has been used in the viticultural sector to study the soil-plant-atmosphere (SPA) relationships in vineyards and to define and support the terroir concept and its resilience under climate change.

This contribution presents the results relating to the ability of the model to (i) shed light on the relationships between water stress and grape quality characteristics and (ii) evaluate the impact of climate change on the responses of the vineyard system of three vine varieties cultivated in southern Italy (Aglianico, Cabernet sauvignon and Greco).

In each case study, the calibrated and validated SWAP model output has been used to explore the relations between the plant water stress realized during the growing season and vine responses (physiological and productive responses). The identified relations were successively applied to evaluate the climate change (CC, RCP 4.5 and 8.5 ) adaptation of each vineyard system studied. Furthermore, in the case of the Aglianico grapevine, the evaluation of adaptation to CC was spatially extended to a region of southern Italy (Valle Telesina, BN; 20.000 ha) devoted to high-quality wine production, and the resilience of the terroir concept evaluated.

Finally, the strengths and limitations of SWAP application in the viticultural context will be discussed.

Keywords: grapevine, SPA system, terroir, climate change, vine water stress, grape quality.

How to cite: Bonfante, A.: SWAP model potentiality in the viticultural system study and analysis., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9239, https://doi.org/10.5194/egusphere-egu24-9239, 2024.

EGU24-9866 | ECS | Posters on site | HS8.3.3

The concomitance of water use regulations and loss in soil-plant hydraulic conductivities 

Mohanned Abdalla, Andrea Carminati, and Mutez Ahmed

Stomatal regulation, which governs water loss and hence plant water use, is a key feature facilitating plant adaptation to water-limited environments. Nevertheless, the underlying mechanisms governing stomatal closure remain disputed. Recent studies proposed that the loss in hydraulic conductivities within the soil-plant system is the main driver of stomatal closure. However, the primary hydraulic constraint along the system, being in the soil and/or within the plant, remains without consensus. Furthermore, simultaneous measurements of the hydraulic limitation and stomatal regulation, especially in intact plants, is challenging. Here, we reviewed the recent literature on the relationship between stomatal closure and the loss of hydraulic conductance of key elements across the soil-plant-atmosphere continuum: soil, root, root-soil interface, xylem and leaf. We observed higher correlation between stomatal closure and declining below-ground hydraulics rather than leaf and/or xylem hydraulics. This analysis confirms the notion that stomatal closure is triggered by the decline of the soil-plant hydraulic conductance, and that this decline has often a below-ground origin. Understanding the key regulatory role of below-ground hydraulics is critical for forecasting and managing plant behavior under drought. 

How to cite: Abdalla, M., Carminati, A., and Ahmed, M.: The concomitance of water use regulations and loss in soil-plant hydraulic conductivities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9866, https://doi.org/10.5194/egusphere-egu24-9866, 2024.

EGU24-11051 | ECS | Orals | HS8.3.3

The effect of lithology on leaf litter decomposition of Pinus pinaster forests along a Mediterranean precipitation gradient 

Daniel Fishburn, Andy Smith, Lars Markesteijn, and Ana Rey

Above-ground plant litter decomposition has a major influence on the global carbon (C) cycle by transferring 50% of net primary productivity to soil organic matter and releasing 60 Pg C annually into the atmosphere. Despite extensive research devoted to disentangling the main drivers controlling litter decomposition, the role of lithology remains understudied. Here, two studies were conducted to investigate the combined effects of lithology and climate on needle litter decomposition on three distinctive lithological substrates (calcareous, peridotite, and metapelite) along a precipitation gradient (ranging from 641 to 1097 mm yr-1) in the province of Málaga, south of Spain.

Study one examined needle litter decomposition of Pinus pinaster (maritime pine) along the experimental gradient, and study two was a reciprocal transplant experiment established on calcareous and peridotite lithological substrates located in the centre of the precipitation gradient with litter of contrasting chemical recalcitrance obtained from P. pinaster and Abies pinsapo (Spanish fir) to assess the impact of lithology on the home field advantage hypothesis.

Total litter mass loss during decomposition was highest in the calcareous substrate, exceeding metapelite and peridotite substrates by 24% and 50%, respectively. Decreased precipitation reduced litter mass loss only in calcareous soils (35%) but had little effect on metapelitic and peridotite sites indicating that more productive bedrock types are influenced to a greater degree by reducing precipitation, supporting the boom-bust hypothesis. On peridotite substrates, decomposition of the labile soluble cell fraction and cellulose-based crude fibre fractions of intermediate recalcitrance was delayed by one dry season whereas lignin decomposition ensued immediately highlighting physicochemistry-induced modification of substrate accessibility.  Moreover, study two demonstrated a pronounced home-field advantage for litter on calcareous substrates, contrasting with an away-field advantage for litter derived from peridotite substrates. These results underscore the significant role of lithology in dictating litter decomposition dynamics, directly influencing both litter quality and microbial substrate accessibility.

Given that lithology directly impacts litter quality and its response to changing precipitation patterns—both critical variables in global ecosystem carbon models—incorporating lithological factors is essential for accurately predicting how plant litter decomposition will respond to climate change.

How to cite: Fishburn, D., Smith, A., Markesteijn, L., and Rey, A.: The effect of lithology on leaf litter decomposition of Pinus pinaster forests along a Mediterranean precipitation gradient, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11051, https://doi.org/10.5194/egusphere-egu24-11051, 2024.

EGU24-11140 | ECS | Posters on site | HS8.3.3

Genotypic variability of plant water use strategies during increasing atmospheric drought in 15 spring wheat (Triticum aestivum L.) genotypes 

Emma Ossola, Tina Köhler, Andrea Carminati, and Walid Sadok

The rise of global temperatures and shifts in precipitation patterns lead to increasing vapour pressure deficit (VPD), which was shown to have a detrimental impact on yield of many crops. A reduction in the transpiration rate (TR) at high VPD has been proposed as a key drought tolerance breeding trait to avoid excessive water loss. Our hypothesis is that with climate change, it will be more convenient for plants to have traits that restricts TR under high VPD levels. With this research we aimed to identify relevant hydraulic traits impacting plant water use during atmospheric drying.

We measured water use and hydraulic traits of 15 different Minnesota spring wheat (Triticum aestivum L.) genotypes. We grew 45 plants (3 replicates for each genotype) in a climate chamber with controlled climatic conditions, while the soil was kept moist. After six weeks of growth, we monitored TR at 6 different VPD levels, between 0.5 and 2.8 kPa. Additionally, we measured maximum stomatal conductance (gs), leaf area (LA), plant hydraulic conductance (Kplant), stomatal density (SD), and root and leaf total biomass.

Our findings show that total transpiration per LA, LA, and root/shoot-ratio differed significantly between genotypes. Conversely, transpiration sensitivity to rising VPD (indicated by the critical VPD upon which plants restricted transpiration, VPDBP), Kplant and maximum gs did not significantly differ between genotypes. However, we observed that plants with a low Kplant and a high maximum gs expressed a relatively low VPDBP, indicating a higher transpiration sensitivity to VPD. Our results align well with a hydraulic explanation of the TR response to increasing VPD and suggest that plant hydraulics play a key role in regulating TR during atmospheric drying. If the goal of future breeding is to modify plant water use under increasing VPD, targeting hydraulic traits has still much underexplored potential.

How to cite: Ossola, E., Köhler, T., Carminati, A., and Sadok, W.: Genotypic variability of plant water use strategies during increasing atmospheric drought in 15 spring wheat (Triticum aestivum L.) genotypes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11140, https://doi.org/10.5194/egusphere-egu24-11140, 2024.

EGU24-11972 | Orals | HS8.3.3

Ecosystem scale evapotranspiration is controlled by small scale processes and soil hydraulic properties 

Andrea Carminati, Fabian Wankmüller, Louis Delval, Martin J Baur, Mathieu Javaux, Sebastian Wolf, Peter Lehmann, and Dani Or

The upscaling of hydrologic processes at catchment scale from small scale soil hydraulic parameterization has been met with limited success. For example, spatially variable attributes (topography, surface properties, preferential flow paths) affect infiltration and runoff rates, introducing uncertainties that mask the role of soil properties at catchment scales. In contrast, evidence suggests that evapotranspiration (ET) remains controlled by small scale processes (flow of water to roots, capillary pumping to drying surface) that are critically dependent on soil hydraulic properties. This scale invariance of ET offers opportunities for upscaling emergent ecosystem scale ET dynamics from basic soil information.

ET switches from being energy to water limited at a critical soil water threshold when the water flow through the soil matrix can no longer sustain the atmospheric water demand. This transition depends on the soil water characteristics and soil hydraulic conductivity curve (characterized by their nonlinearity and dependence on soil texture), on plant traits (root length density, leaf area, and xylem vulnerability), and on atmospheric conditions (e.g., vapor pressure deficit and wind velocity). Despite the importance of plant hydraulic traits and atmospheric conditions, the large variations in soil hydraulic properties as a function of soil texture, make small scale hydraulic properties the key in controlling ET during soil drying (Lehmann et al. 2008, Carminati and Javaux 2020). It follows that soil moisture thresholds of ET are controlled by water flow in soils and by the soil hydraulic conductivity. Accordingly, small-scale models of water flow to the soil surface and to the roots successfully predict soil moisture thresholds that have been measured at the ecosystem scale.

The question of why upscaling flow equations and properties derived from small sample and single plants to ecosystems proved to be successful is an important one. In contrast to water infiltration and run-off affected by the scale-dependent size of surface heterogeneities, the spatial scale of water flow from soils to roots does not increase with the scale of observation. It is the limiting flow through the soil matrix, with spatial scales of 0.01-0.1 m, which sets the point when plants downregulate transpiration and photosynthesis as the soil dries; a process that is similar to the evaporation from the soil surface.

In conclusion, despite the challenges and uncertainties in applying soil physical laws to larger scale, the application of Buckingham-Darcy law to properly predict matrix flow and evapotranspiration at the ecosystem scale is doable and relevant for understanding drought effects on ecosystem water use and productivity.

 

Carminati A, Javaux M. Soil rather than xylem vulnerability controls stomatal response to drought. Trends in Plant Science. 2020 Sep 1;25(9):868-80.

Lehmann P, Assouline S, Or D. Characteristic lengths affecting evaporative drying of porous media. Physical Review E. 2008 May 16;77(5):056309.

How to cite: Carminati, A., Wankmüller, F., Delval, L., Baur, M. J., Javaux, M., Wolf, S., Lehmann, P., and Or, D.: Ecosystem scale evapotranspiration is controlled by small scale processes and soil hydraulic properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11972, https://doi.org/10.5194/egusphere-egu24-11972, 2024.

EGU24-12359 | Orals | HS8.3.3

 Improving the sustainability of arable cropping systems by modifying root traits: a modelling study for winter wheat 

Elsa Coucheney, Thomas Kätterer, Katharina Meurer, and Nick Jarvis

Crop breeding to increase below-ground production and inputs of organic matter into soil has been attracting increasing attention as a potentially effective strategy to enhance soil organic matter (SOM) stocks and thus the quality of soil and sustainability of arable cropping systems. We used the new soil-crop model USSF (Uppsala model of Soil Structure and Function) to investigate the potential for increasing SOM whilst maintaining or improving yields by modifying the root system of winter wheat in terms of below-ground allocation of carbon and key root traits. USSF combines physics-based descriptions of soil water flow, water uptake and transpiration by plants, with a simple (generic) crop growth model and a model of soil structure dynamics and soil organic matter turnover that considers the effects of soil physical protection and microbial priming. 

The USSF model was first calibrated against field data on soil water contents and both above-ground and root biomass of winter wheat measured during one growing season in a clay soil in Uppsala, Sweden. Based on five acceptable calibrated parameter sets, we created four model crops (ideotypes) by modifying root-related parameters to mimic winter wheat phenotypes with improved root traits. Long-term (30-year) simulations of a conventionally tilled monoculture of winter wheat were then performed to evaluate the potential effects of cultivating these ideotypes on soil water balance, soil organic matter stocks and grain yields.

Our results suggest that exploiting winter wheat varieties that allocate more assimilate to the root system would not in itself have any positive effect on soil organic matter storage and would also decrease grain yields. In contrast, deeper root systems or root systems that are more effective for water uptake were predicted to slightly increase grain yields, as well as increasing SOM stocks in the soil profile by ca. 3 to 5%. Combining all three improved root traits showed even more promising results: compared with the baseline “business-as-usual” scenario, SOM stocks in the soil profile were predicted to increase by ca. 7% in a 30-year perspective (as an average of the five parameter sets) without negatively impacting yields.

How to cite: Coucheney, E., Kätterer, T., Meurer, K., and Jarvis, N.:  Improving the sustainability of arable cropping systems by modifying root traits: a modelling study for winter wheat, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12359, https://doi.org/10.5194/egusphere-egu24-12359, 2024.

EGU24-12431 | Posters on site | HS8.3.3

Effect of soil-plant interactions on nutrient availability and supply in a tropical Andean ecosystem  

Armando Molina, Veerle Vanacker, Oliver Chadwick, Santiago Zhiminaicela, Marife Corre, and Edzo Veldkamp

Plants play a key role in absorbing nutrients and water through their roots, and modulate the biogeochemical cycles of terrestrial ecosystems. Nutrient uptake mechanisms of water and nutrient by plants depend on climatic and edaphic conditions, as well as of their root systems. Soil solution is the medium in which abiotic and biotic processes exchange nutrients, and nutrient concentrations vary with the abundance of reactive minerals and fluid residence times. High-altitude grassland ecosystems of the tropical Andes are particularly interesting to study the relationship between vegetation communities, soil hydrology and mineral nutrient availability. In páramo ecosystems, forest, tussock grasses and cushion plants co-occur across the landscape. In the nutrient-depleted nonallophanic Andosols, the plant rooting depth varies with drainage and soil moisture conditions. Vegetation composition is a relevant indicator of rock-derived nutrient availability in soil solutions. Significant variations in the soil solute chemistry revealed patterns in plant available nutrients that were not mimicking the distribution of total rock-derived nutrients nor the exchangeable nutrient pool, but clearly resulted from strong biocycling of cations and removal of nutrients from the soil by plant uptake or deep leaching. Our findings highlight the importance of vegetation communities, soil hydrological condition, and the bioavailability of mineral nutrients to trigger rapid and complex changes in the biogeochemistry of soil waters. Moreover, the findings have important implications for future management of Andean ecosystems where vegetation type distributions are dynamically changing as a result of warming temperatures and anthropogenic disturbances. Such alterations may not only lead to changes in soil hydrology and solute geochemistry but also to complex changes in weathering rates and solute export downstream with effects on nutrient availability in Andean rivers and high-mountain lakes.

How to cite: Molina, A., Vanacker, V., Chadwick, O., Zhiminaicela, S., Corre, M., and Veldkamp, E.: Effect of soil-plant interactions on nutrient availability and supply in a tropical Andean ecosystem , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12431, https://doi.org/10.5194/egusphere-egu24-12431, 2024.

EGU24-12839 | ECS | Posters virtual | HS8.3.3

Sensitivity analysis of a process-based root water uptake model to predict drought stress in soybean and wheat in a tropical winter-dry climate 

Marina Luciana Abreu de Melo, Quirijn de Jong van Lier, Jos C. van Dam, and Marius Heinen

Drought stress is one of the main reasons for reduced yields in soybean and wheat crops in Brazil. Process-based root water uptake (RWU) models are valuable tools to assess soil-water-plant relations and improve crop water management. We aimed to perform a pioneer sensitivity analysis (SA) of a process-based RWU model using three methods and two sampling strategies. The SWAP agro-hydrological model with the recently implemented MFlux RWU function was used to predict drought stress in soybean and wheat crops simulated on five soils with different hydraulic properties sampled in southeast Brazil, characterized by a tropical winter-dry climate. Three SA methods were used: local, global Morris, and global Sobol. Seven parameters of the MFlux function were selected, together with their reference values and ranges of variability. The local sensitivities were predominately negative, indicating that the drought stress increased as the values for each RWU parameter decreased. The Morris method revealed parameter interactions not addressed in the local method. The Sobol method also evidenced parameter interactions calculated through robust variance-based indices. Although the three SA methods provided different results regarding parameter contributions to drought stress prediction, the root length density was the most sensitive parameter for all simulated scenarios. Hence, it should be a priority in future model calibration efforts.

How to cite: Abreu de Melo, M. L., de Jong van Lier, Q., C. van Dam, J., and Heinen, M.: Sensitivity analysis of a process-based root water uptake model to predict drought stress in soybean and wheat in a tropical winter-dry climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12839, https://doi.org/10.5194/egusphere-egu24-12839, 2024.

Desertification is one of the most important environmental problems in the world. In arid and semi-arid regions, desert shrub reconstruction is one of the most effective ways to prevent desertification and promote ecological restoration. Recently, many studies have reported the hydraulic trade-off, coordination, and hydraulic segmentation of woody plants, however, the mechanism of how the hydraulic segmentation drives morphological adjustment of desert shrub to response to drought is still largely unclear. Here, the two-year-old seedlings of Caragana korshinskii and Artemisia ordosica as materials were subjected to continuous drought treatment. The aim is to explore hydraulic strategies and quantify the hydraulic threshold when morphological adjustments drive occurs. The results showed that tissues water content of C. korshinskii and A. ordosica under persistent drought showed an exponential decrease with the decrease of soil water content, but it is with a certain lag effect. Meanwhile, the leaf water potential, xylem specific hydraulic conductivity, degree of natural embolism and photosynthetic rate, etc. showed decrease trend with persistent drought. Above results suggested that hydraulic functional traits were drove by changes of soil water, but the tissue hydraulic capacitance acts as a buffer against decline of above traits. Moreover, the water potential thresholds of 88% stomatal closure and hydraulic safety margin in C. korshinskii was significant high than A. ordosica’s, which indicated that C. korshinskii are more vulnerable to drought. Then, the morphological adjustments such as leaf wilting and lateral branches wilting further occurred with the continued drought, however, the lateral branches of C.korshinskii could germinate again after soil water recovery, but A.ordosica could not. Overall, the water potential and hydraulic conductivity threshold for morphological adjustment of desert shrub such as leaves wilting and lateral branches wilting under continuous drought were quantified and the hydraulic strategies were elucidated that was regulated by hydraulic segmentation.

How to cite: Huo, J. and Zhang, Z.: Hydraulic strategies of desert shrubs responding to morphological adjustment under persistent drought, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14434, https://doi.org/10.5194/egusphere-egu24-14434, 2024.

EGU24-15054 | ECS | Posters on site | HS8.3.3

Sensitivity analysis of root water uptake reduction using the Bartholomeus model in shallow water table scenarios 

Laura Raquel Quinonez Vera and Quirijn de Jong van Lier

A frequently used approach to estimate the reduction of the root water uptake (RWU) caused by oxygen stress in hydrological models such as SWAP is the empirical model of Feddes, which describes RWU using a piecewise linear function. Critical values associated with the threshold pressure heads defining oxygen stress (h1 = -10 cm and h= -25 cm) seem not to be able to represent properly this condition, because oxygen may start at more negative values of h. As an alternative, Bartholomeus et al. (2008) proposed a model based on physical and physiological soil and root processes to calculate the minimum gas-filled porosity of the soil at which oxygen stress occurs. We performed a sensitivity analysis of the Bartholomeus model focusing on two parameters, the threshold to stop root extension in case of oxygen stress and the air-filled root porosity in shallow water table scenarios cropped with soybean. We performed simulations for five soil types in combination with several water table depths. To do so, the water table was used in SWAP as the lower boundary condition. The sensitivity of the RWU and relative transpiration to combinations of parameters will be shown and discussed.

 

How to cite: Quinonez Vera, L. R. and de Jong van Lier, Q.: Sensitivity analysis of root water uptake reduction using the Bartholomeus model in shallow water table scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15054, https://doi.org/10.5194/egusphere-egu24-15054, 2024.

EGU24-15318 | ECS | Orals | HS8.3.3

In situ grapevine hydraulic response to drought is soil-texture specific 

Louis Delval and Mathieu Javaux

Climate change will exacerbate drought events in many regions, increasing the demand on freshwater resources and creating major challenges for viticulture. The knowledge on grapevine drought stress physiology has increased significantly in recent years, but a holistic comprehension on how soil-grapevine hydraulic conductances develop and are regulated in the soil-grapevine-atmosphere continuum (SPAC) remains poorly understood. In particular, how soil type affects the grapevine hydraulic response to drought is still an open question.

The aim of this work is to understand how the hydraulic conductances in the SPAC continuously evolve according to soil type, during drought.

The continuous, concomitant and automatic monitoring of soil and collar water potentials, as well as sap flow, made it possible to characterize the evolution of the soil-grapevine hydraulics in situ in real-time. To investigate the impact of the soil type, two vineyards planted with Vitis vinifera cv. Chardonnay were selected due to their intra-field heterogeneity of soil properties (two subplots per vineyard). In a first vineyard, soil-grapevine hydraulics were measured on a sandy subplot and on a loamy subplot. In a second vineyard, we worked on a loamy subplot and on a silty-clay subplot.

We found that grapevine hydraulic response to soil drying is soil texture specific. Stomatal closure was observed for grapevines planted on coarse-textured soils, but not, or little, on fine-textured soils. This stomatal response was triggered by a decrease in belowground hydraulic conductance and not xylem cavitation in the trunk. This suggests that the interaction between the grapevine and the soil hydraulic environment plays a crucial role in shaping hydraulic behaviour of Chardonnay during drought periods.

While soil dries out, the decline in soil hydraulic conductivity led to a steep and nonlinear reduction in soil matric potential at the soil-root interface, with greater reduction in sandy soils compared to loamy soils. This rapid decline in soil hydraulic conductivity implies that the soil is more rapidly limiting (at less negative soil water potential), triggering earlier stomatal closure in coarse-textured soils. Stomatal regulation is amplified in sandy profile as compared to fine textured profile within the same grape variety.

How to cite: Delval, L. and Javaux, M.: In situ grapevine hydraulic response to drought is soil-texture specific, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15318, https://doi.org/10.5194/egusphere-egu24-15318, 2024.

EGU24-15448 | ECS | Posters on site | HS8.3.3

Multi-year aboveground dataset of minirhizotron facilities on a cropland site with two soil types in Western Germany 

Thuy Nguyen, Gina Lopez, Sabine Seidel, Lena Lärm, Felix Bauer, Anja Klotzsche, Andrea Schnepf, Thomas Gaiser, Hubert Hüging, and Frank Ewert

Improved understanding of crops’ response to soil water stress is important to advance soil-plant system models and to support crop breeding, crop and varietal selection, and management decisions to minimize negative impacts. Studies on eco-physiological crop characteristics from leaf to canopy for different soil water conditions and crops are often carried out at controlled conditions. In-field measurements under realistic field conditions and data of plant water potential, its links with CO2 and H2O gas fluxes, and crop growth processes are rare. Here, we presented a comprehensive data set collected from leaf to canopy using sophisticated and comprehensive sensing techniques (leaf chlorophyll content, hourly leaf stomatal conductance and photosynthesis, canopy CO2 exchange, sap flow, and canopy temperature) including detailed crop growth characteristics based on destructive methods (seasonal dynamics of crop height, leaf area index, above-ground biomass, and yield). Data were acquired under field conditions with contrasting soil types, water treatments, and different cultivars of wheat and maize. The data from 2016 up to now will be made available together with the below-ground data. This dataset produced under field conditions is unique and could be used by different users (agronomists, hydrologists, crop modelers, breeders, etc.) for studying soil/water-plant relations and improving soil-plant-atmospheric continuum models.

How to cite: Nguyen, T., Lopez, G., Seidel, S., Lärm, L., Bauer, F., Klotzsche, A., Schnepf, A., Gaiser, T., Hüging, H., and Ewert, F.: Multi-year aboveground dataset of minirhizotron facilities on a cropland site with two soil types in Western Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15448, https://doi.org/10.5194/egusphere-egu24-15448, 2024.

EGU24-15520 | Orals | HS8.3.3

The influence of irrigation on root zone storage capacity 

Ruud van der Ent, Fransje van Oorschot, Andrea Alessandri, and Markus Hrachowitz

Vegetation plays a crucial role in regulating the water cycle through transpiration, which is the water flux from the subsurface to the atmosphere via vegetation roots. The amount and timing of transpiration is controlled by the interplay of seasonal energy and water supply. The latter strongly depends on the size of the root zone storage capacity (Sr) which represents the maximum accessible volume of water that vegetation can use for transpiration. Sr is primarily influenced by hydro-climatic conditions as vegetation optimizes its root system in a way it can guarantee water uptake and overcome dry periods. Sr estimates are commonly derived from root zone water deficits that result from the phase shift between the seasonal signals of root zone water inflow (i.e., precipitation) and outflow (i.e., evaporation). In irrigated croplands, irrigation water serves as an additional input into the root zone. However, this aspect has been ignored in many studies, and the extent to which irrigation influences Sr estimates was never comprehensively quantified. In this study, our objective is to quantify the influence of irrigation on Sr and identify the regional differences therein. To this aim, we integrated two irrigation methods, based on irrigation water use and irrigated area fractions, respectively, into the Sr estimation. We evaluated the effects in comparison to Sr estimates that do not consider irrigation for a sample of 4511 catchments globally with varying degrees of irrigation activities. Our results show that Sr consistently decreased when considering irrigation with a larger effect in catchments with a larger irrigated area. For catchments with an irrigated area fraction exceeding 10%, the median decrease of Sr was 17 mm and 22 mm for the two methods, corresponding to 12% and 17%, respectively. Sr decreased the most for catchments in tropical climates. However, the relative decrease was the largest in catchments in temperate climates. Our results demonstrate, for the first time, that irrigation has a considerable influence on Sr estimates over irrigated croplands. This effect is as strong as the effects of snow melt that were previously documented in catchments that have a considerable amount of precipitation falling as snow.

A manuscript associated with this abstract is available as preprint:

van Oorschot, F., van der Ent, R. J., Alessandri, A., and Hrachowitz, M.: Influence of irrigation on root zone storage capacity estimation, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2023-2622, 2023.

How to cite: van der Ent, R., van Oorschot, F., Alessandri, A., and Hrachowitz, M.: The influence of irrigation on root zone storage capacity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15520, https://doi.org/10.5194/egusphere-egu24-15520, 2024.

EGU24-15793 | ECS | Orals | HS8.3.3

Spatial variation in soil hydraulic properties in an agricultural field estimated using Tension Disc Infiltrometer 

Nirali Vashishth, Souradip Dey, and Dr. Richa Ojha

Understanding spatial variation in soil hydraulic properties is important for comprehending the physical behaviour of soil and for analysing field-scale water flow and solute transfer processes. Tension disc infiltrometers are commonly used for measuring in-situ unsaturated hydraulic properties of soil. In this study, spatial variation in soil hydraulic properties is analysed for an experimental plot at IIT Kanpur, India after harvest of rice crop using tension disc infiltrometer. Measurements were taken at three different depths of 10, 25 and 50 cm and at multiple locations in the field for consecutive supply pressure heads of -12, -9, -6 and -3 cm. The measured data was analysed using HYDRUS-2D model and four Maulem-van Genutchen parameters (θs, α, n and Ks) were inversely estimated. The maximum variation was observed in α at the depth of 50 cm. The reduced variability observed in pore size distribution index (n) could be attributed to the flooded irrigation practice in rice. The findings of this study enhance our understanding of soil-water interaction in agricultural settings.

Keywords: Soil hydraulic properties, Tension disc infiltrometer, HYDRUS-2D

How to cite: Vashishth, N., Dey, S., and Ojha, Dr. R.: Spatial variation in soil hydraulic properties in an agricultural field estimated using Tension Disc Infiltrometer, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15793, https://doi.org/10.5194/egusphere-egu24-15793, 2024.

EGU24-16031 | ECS | Posters on site | HS8.3.3

New methods of measuring and modeling biomass partitioning in winter wheat under field conditions. 

Dominik Behrend, Thuy Huu Nguyen, Hubert Hüging, Juan C. Baca Cabrera, Guillaume Lobet, Clara Oliva G. Bazzo, Sabine J. Seidel, and Thomas Gaiser

Partitioning of biomass between roots and the above ground organs of crops is a key plant physiological processes that is closely linked to root growth and, thus, water and nutrient uptake. This makes investigations and knowledge about the partitioning of carbon between below and above ground plant organs important for accurately simulating water and carbon fluxes from croplands. Previous experiments have shown that carbon partitioning between root and shoot of crops could be altered by drought. However, most crop models do not explicitly consider the alteration of carbon partitioning caused by drought. This might partly be due to the difficulties in measuring the complete root biomass under field conditions and, thus, a lack of data on the field scale. Current methodologies such as soil coring and shovelomics are time-consuming and limited with regards to the measured depth, they do not necessarily capture the whole root biomass of deep rooting winter crops like winter wheat.

The overall aim of the study is to improve our understanding of responses of below and above ground growth processes to different soil water availability. A field experiment has been conducted to investigate how drought stress affects the root: shoot ratio of different winter wheat cultivars under field conditions. A carbon partitioning subroutine, based on the sink strength principle and considering the direct effects of drought stress on carbon allocation, is implemented in the crop model SIMPLACE<LintulCC2>. The experimental data was used to test whether this newly developed model could successfully represent the effects of drought stress on biomass partitioning for different wheat cultivars.

In the experiment, tubes with a diameter of 11 cm and a length of 1 m, filled with a sandy substrate and closed on the bottom with a fine mesh fleece that allows water to flow through but stops roots from growing through, were buried in 1m deep holes. Winter wheat was sown inside the tubes and the field around them to catch the whole plant biomass under canopy conditions. Half of the tubes were watered during the growth period, the other half were sheltered from rain during early growth stages. Root biomass and traits were investigated after harvesting the tubes. The data from this experiment was used to calibrate the carbon partitioning subroutine in the crop model under non-stressed and water-stressed conditions. The carbon partitioning subroutine calculates organ-specific potential daily growth rates. These growth rates are used to calculate the organ-specific sink strength, which can be affected by water stress and is used to define the amount of carbon distributed to each organ per day.

The first experimental results show that water stress did affect the carbon partitioning between root and shoot biomass of winter wheat. The implemented model improved the simulation of biomass partitioning between root and above ground plant organs under drought conditions.

How to cite: Behrend, D., Nguyen, T. H., Hüging, H., Baca Cabrera, J. C., Lobet, G., G. Bazzo, C. O., Seidel, S. J., and Gaiser, T.: New methods of measuring and modeling biomass partitioning in winter wheat under field conditions., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16031, https://doi.org/10.5194/egusphere-egu24-16031, 2024.

EGU24-16651 | Orals | HS8.3.3 | Highlight

Tropical humid forests: water consumers or producers? The case of a forest fragment in the Atlantic Forest 

Laura Borma, Fabio Sakagushi, Wilian Demetrio, Breno Pupin, Dione Ventura, Carlos Daniel Meneghetti, Basile Devoie, Charlotte Dermauw, Lola Parmentier, and Mathieu Javaux

Given the critical role of tropical forests in providing ecosystem services, extensive global efforts have been made to conserve and restore these vital areas. Despite the recognized environmental value of preserved forests, substantial uncertainties persist regarding the impact of reforestation activities on water recharge. While some studies suggest that reforestation might lead to a reduction in surface and groundwater reserves, other research, backed by public opinion, indicates that forest recovery enhances water reserve.

Recognizing this as a crucial scientific and environmental management concern, our study aims to explore the role of de and reforestation on soil hydraulic properties. Combining in situ monitoring of water status and soil physical properties, our study aimed at addressing the following scientific question: how does soil structure evolve with different revegetation stages?

We selected several plots along a hillslope transect in the oceanic forest (Sao, Paulo, Brasil), with different reforestation stages (40 y.o. forest vs deforested pasture).  Deep percolation measurements were conducted using sealed bottom lysimeters. A comparative analysis of soil conditions in contrasted study areas involved soil physical properties such as texture, permeability, and bulk density, along with assessing the seasonal variability of matric potential and soil moisture content.

Our findings reveal that soil infiltration capacity of pasture was lower than under a 40 yr-old forest. We also observed that soil macroporosity  was higher under the forest area than  under the pasture area, potentially influencing infiltration rates and favoring deep drainage in the forest compared to the pasture.

How to cite: Borma, L., Sakagushi, F., Demetrio, W., Pupin, B., Ventura, D., Meneghetti, C. D., Devoie, B., Dermauw, C., Parmentier, L., and Javaux, M.: Tropical humid forests: water consumers or producers? The case of a forest fragment in the Atlantic Forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16651, https://doi.org/10.5194/egusphere-egu24-16651, 2024.

EGU24-16680 | ECS | Posters on site | HS8.3.3

Eco-hydrology modelling in arid areas : Study of root density impact on water fluxes in the Sahelian region 

Lucie Rapp-Henry, Jean-Martial Cohard, Mahamadi Tabsoba, Basile Hector, Jérôme Demarty, and Laura Condon

The Sahelian region experienced intense droughts between 1970 and 1990 and despite a precipitation « recovering », soils remain degraded and a decrease in the soil ability to infiltrate - an essential characteristic for vegetation recover – is observed, together with an increase of desertification and of eroding floods frequency.

To tackle with this phenomenon, coordinated agricultural strategies, like the Great Green Wall project, have been encouraged and spread over large areas through NGOs. This consists in applying agro-ecological practices, like micro dams, to harvest water, favor infiltration, and hence vegetation growth. These strategies still require critical assessments and optimisation. To study such agroecological practices we are developing a modelling framework based on ParFlow-CLM to simulate the interactions between surface hydrology and vegetation in the context of crusted Sahelian soils where water transfers are highly dependent on both surface hydrodynamical properties and root distribution below the surface. Indeed, the very thin eolian crust acts as a hydraulic discontinuity that slows down soil evaporation transfers but not transpiration, which benefits from the roots below the crust and from the stems which bridge to the atmosphere.

However, since the CLM family models were designed for large scale with a relatively thick mesh at the surface, the root density function proposed as a decreasing exponential function distribute the majority of roots just below the surface. This disposition is irrelevant for finer millimeter underground meshes modelling, particularly in areas with a hot and dry climate such as the Sahelian one, that dries very rapidly the first centimetres of soil.

Thus, In the CLM land surface model framework and according to literature, we propose a new root distribution in the soil, using a parameterised function which is zero at the surface and at infinity, and adapt the maximum root density depth and the root concentration around this maximum. We compare the impact of both initial and proposed root functions on a Sahelian case study in Niger where all necessary data are available thanks to the AMMA-CATCH observatory. Studying this function highlighted simple causal relations between root density function parameterisation and evapotranspiration flux.

By modifying the root density function, we can find a set of parameters corresponding to a better representation of transpiration, global evapotranspiration and soil moisture, and accordingly, a better representation of the studied ecosystem.

Once this representation is relevant, a dynamic LAI based on allocation laws, available in the latest version of CLM, will then complete this modification of the vegetation scheme. We will then introduce the changes on surface due to agricultural practices and study the impact of their sizing.

How to cite: Rapp-Henry, L., Cohard, J.-M., Tabsoba, M., Hector, B., Demarty, J., and Condon, L.: Eco-hydrology modelling in arid areas : Study of root density impact on water fluxes in the Sahelian region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16680, https://doi.org/10.5194/egusphere-egu24-16680, 2024.

EGU24-16788 | ECS | Posters on site | HS8.3.3

Investigating electrical polarization signatures of sugar beet and maize: A field study using spectral electrical impedance tomography 

Valentin Michels, Maximilian Weigand, and Andreas Kemna

Despite their vital role for agricultural management practices and plant breeding experiments, it is still challenging to characterize plant roots non-invasively in their natural environment. A promising new method for plant root characterization is the spectral electrical impedance tomography (sEIT) method, which is able to image the conductive and polarizable subsurface properties with high spatio-temporal resolution. Electrical polarization signatures have been shown to be sensitive to root structure and activity, although superimposed soil signatures complicate the interpretation. Recent studies have demonstrated that impedance measurements can be used to estimate root traits under laboratory conditions, especially in hydroponic experiments. However, field studies using sEIT on plant-root systems are still scarce.

In this study we present a field dataset of multi-frequency sEIT measurements on sugar beet and maize. Three different growth stages were measured during a whole growing season. We performed complex resistivity inversions for each measurement frequency, and subsequently analyzed the spatially resolved spectral response using a Debye decomposition analysis. Characteristic relaxation times, extracted from the spectral analysis, serve as proxies indicating the length scales of the observed polarization processes. We find that the physiologically different plant root systems cause distinct polarization responses in the low-frequency range. While both root systems exhibit an increasing polarization response towards higher frequencies, sugar beet develops an additional low-frequency polarization peak near 10 Hz later in the season, corrseponding with increasing size of the sugar beets. We attribute this peak to the polarization of root structures associated with the macroscopic dimensions of the beet roots, and demonstrate this link through the correlation of the retrieved mean relaxation time at the sugar beet positions with the square of the respective maximum beet diameter. Additionally, we evaluate the intrinsic spectral form of the polarization signatures extracted from the maize root area, and find a moderate correlation with the fresh biomass.

In conclusion, our results highlight that sEIT can be used in the field for plant root trait estimations, but structurally differing plants require different analysis procedures to extract root information. Additionally, environmental factors, like a varying soil composition or soil water content, have a strong influence on the measured impedance signal, and can make precise root trait estimation difficult.

How to cite: Michels, V., Weigand, M., and Kemna, A.: Investigating electrical polarization signatures of sugar beet and maize: A field study using spectral electrical impedance tomography, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16788, https://doi.org/10.5194/egusphere-egu24-16788, 2024.

EGU24-17711 | ECS | Orals | HS8.3.3 | Highlight

How grasslands are managed will determine their ability to adapt to increased water scarcity under climate change 

Sven Westermann, Jan Bumberger, Martin Schädler, Stephan Thober, and Anke Hildebrandt

Grasslands are highly dynamic ecosystems that adapt to environmental drivers such as climate, soil properties and anthropogenic management. However, the belowground response and adaptation of grassland communities to environmental drivers are poorly understood. Here, we investigate differences in the temporal dynamics of root water uptake, its depth pattern and the evolution of plant-available soil water storage between three different grassland management types and in two different climate treatments (control and future). The climate scenarios included treatments with and without a precipitation manipulation that partially shifts the precipitation from summer to spring and autumn. Soil moisture measurements were carried out at 6 depths up to 90 cm on three land use types (i) extensively and (ii) intensively managed grassland and (iii) extensive pasture at the Global Change Experimental Facility (GCEF) in Central Germany. Afterwards, root water uptake was estimated from diurnal variations in soil water content. We found that the grassland vegetation, in general, extracts water to depths of up to 90 cm during the growing season and can go even deeper. Extensively managed grasslands in the future climate scenario had increased root water uptake depths even in spring when water was not limiting indicating an adaptation to changing rainfall patterns. In contrast, more intensively managed grasslands could not compensate for greater water limitation with deeper root water uptake. Root water uptake depths during summer differed between the management types only in the future climate scenario, with drier conditions, along with the management intensity: The more intense, the shallower the uptake. This demonstrates that the ability to adapt to changing climate depends on management. Cumulative atmospheric water deficit was the main driver of root water uptake depth until the first mowing while ecosystem structure (vegetation height) and soil properties (plant available water at the beginning of the vegetation period) affect that relationship.

How to cite: Westermann, S., Bumberger, J., Schädler, M., Thober, S., and Hildebrandt, A.: How grasslands are managed will determine their ability to adapt to increased water scarcity under climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17711, https://doi.org/10.5194/egusphere-egu24-17711, 2024.

EGU24-17850 | ECS | Orals | HS8.3.3

Coupling a Functional-Structural Plant Model with a Rhizosphere Model To Gain Multiscale Insights into Plant-Soil-Atmosphere Interactions for Water and Carbon Cycles 

Mona Giraud, Ahmet Sircan, Guillaume Lobet, Thilo Streck, Daniel Leitner, Holger Pagel, and Andrea Schnepf

To assess the impact of agricultural practices on water and carbon cycles within specific Genome-Environment-Management combinations, understanding the interactions across the Soil-Plant-Atmosphere continuum (SPAC) is crucial.

Indeed, soil water conditions influence carbon concentration and transport, impacting soil carbon physical and biochemical reactions.

The soil water and carbon status affect, in turn, the plant water and carbon dynamics directly via the plant-to-soil water or carbon gradient, and indirectly via plant water status, influencing its inner balance of water (uptake, transpiration and flow) and carbon (assimilation, usage for maintenance and growth, storage, respiration, rhizodeposition, and transport).

Reciprocally, plant water and carbon balances affect the soil carbon cycle in the short term through root water uptake and rhizodeposition. Those rhizodeposits are, for the most part, made of exudates and mucilage. Root exudates are low molecular weight organic compounds that are mainly passively diffused, while mucilage is a fluid made of polymers with high molecular weight created from starch via an active process.

Modelling plant and soil water and carbon processes, along with their interactions, can help to understand better and represent the effects of the underlying feedback loops. In this study, we therefore coupled the Functional Structural Plant Model (FSPM) CPlantBox with the rhizosphere model TraiRhizo, implemented using the porous medium flow and transport solver DuMux.

The overall coupled model and multiscale framework includes a module of 3D plant architecture development, and modules to represent flow and transport within the plant, the soil and the perirhizal zone around each root segment. Flows between compartments are solved implicitly via fixed-point iteration, using parallel computation for both the 3D soil and rhizosphere models.

We present a case study in which we simulated the growth of a C3 monocot and observed how changes in soil water content, due to root water uptake, influenced dissolved carbon concentration and (de)activation of the soil microbial communities during a dry spell.

In the future, the model will be applied to assess the impact of small dry spells at various stages of plant development against a baseline scenario. In time, this model could support plant breeding efforts to find root traits that aim for more drought-resistant plants in specific pedoclimatic environments.

How to cite: Giraud, M., Sircan, A., Lobet, G., Streck, T., Leitner, D., Pagel, H., and Schnepf, A.: Coupling a Functional-Structural Plant Model with a Rhizosphere Model To Gain Multiscale Insights into Plant-Soil-Atmosphere Interactions for Water and Carbon Cycles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17850, https://doi.org/10.5194/egusphere-egu24-17850, 2024.

EGU24-19179 | ECS | Posters on site | HS8.3.3

Effect of soil texture on root water uptake   

Imen Mhimdi, Dagmar van Dusschoten, and Mathieu Javaux

Effect of soil texture on root water uptake 

I.Mhimdi, D.van Dusschoten, M.Javaux

Forschungszentrum Jülich, Institute for Plant Sciences (IBG-2 ),  Jülich, Germany

Catholic University of Louvain, Earth and Life Institute, Louvain La Neuve, Belgium

Understanding how root water uptake (RWU) depends on soil properties is a key to estimate plant transpiration dynamics and its response to climate. Despite the fact that soil texture plays an important role in determining plant water availability and mechanical resistance, texture and RWU have not often been considered simultaneously in literature. Recently, a novel method was developed by (van Dusschoten et al, 2020), the SWaP (Soil Water Profiler), in which soil water content and its depletion could be monitored during a modulated light regime in order to derive the RWU profile. The scope of our work is to investigate with the SWaP how soil texture impacts RWU dynamics. We hypothesize that the soil texture will impact the distribution of the rhizosphere resistance in the rhizosphere and thereby its RWU.

Eight faba bean (Vicia Faba) plants were grown in 45cm PVC pots, two soil textures (Loamy and Sandy) with different dry density were used. The plants were subjected to progressive water deficits, and were measured continuously with the SWaP, while applying light modulations during daytime to measure instantaneous 1D water content and derived root water uptake profiles. In combination with the SWaP, several MRI measurements were performed combined with image analysis, in order to determine the local root length distribution and its relation to RWU.

For loamy soil, MRI measurements showed a structured spiral shape, an extensive and deeper root system with higher root diameter. Roots were less smooth, tortuous and with denser lateral roots in sandy soil. In both textures, root water uptake decreased with depth, which can be explained by the less abundant roots in lower soil layers and a higher resistance for the deeper roots (Müllers et al, 2023). Root water uptake profiles and total water uptake dynamics were different, between soil types, which could partially be attributed to differences in root distribution.

References

van Dusschoten et al., 2020, Spatially resolved root water uptake determination using a precise soil water sensor, Plant Phys.

Müllers et al., 2023, Deep-water uptake under drought improved due to locally increased root conductivity in maize, but not in faba bean, Plant, Cell & Environment.

How to cite: Mhimdi, I., van Dusschoten, D., and Javaux, M.: Effect of soil texture on root water uptake  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19179, https://doi.org/10.5194/egusphere-egu24-19179, 2024.

EGU24-20215 | Orals | HS8.3.3

Modelling of soil water regime in forested areas: potential benefits of seasonally variable soil hydraulic properties 

Václav Šípek, Lukáš Vlček, Jan Hnilica, and Miroslav Tesař

Soil moisture plays a key role in the hydrological cycle by partitioning of precipitation between evapotranspiration and deep infiltration. The ongoing climate change is causing an increase in air temperatures, changes in precipitation patterns and decrease in winter snow cover. It simultaneously shifts spring snowmelt towards winter months. Both air temperature and precipitation patterns are suspected to be one of the influential factors affecting changes in soil hydraulic properties. Thus, the ongoing climate change can alter soil hydraulic properties, commonly considered time-invariant, and the prediction of future soil moisture regime can therefore be more uncertain than originally thought.

We measured a saturated hydraulic conductivity using an automatic single-ring infiltrometer thorough one entire year in a monthly time-step in the spruce covered site. Higher infiltration rates were regularly observed in the middle of a vegetation season compared to lower rates observed in a dormant season. Based on this finding we implemented a new function, enabling the seasonal variation of the saturated hydraulic conductivity, into the simple bucket-type soil moisture model. The root-mean square error of soil moisture prediction decreased by one-third and Nash-Sutcliffe efficiency increased significantly indicating possible benefits of a new concept. Main reasons behind the seasonal variability of soil hydraulic properties in uncultivated sites can be numerous (encompassing biological activity, changes in the root architecture, wetting/drying and freezing/thawing cycles altering the pore space) and deserve further investigation.

The major outcome is represented by the concept enabling a more efficient prediction of soil moisture regime outside the vegetation season, which is increasingly more important as the onset of soil drought can often be observed at the end of the dormant season. Furthermore, modelling of a climate change impact on the availability of water resources will also benefit from a better prediction of the soil moisture by considering regular structural changes of soil.

How to cite: Šípek, V., Vlček, L., Hnilica, J., and Tesař, M.: Modelling of soil water regime in forested areas: potential benefits of seasonally variable soil hydraulic properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20215, https://doi.org/10.5194/egusphere-egu24-20215, 2024.

EGU24-21812 | Orals | HS8.3.3

SWAP 50 year: Advances in modelling soil-water-atmosphere-plant interactions 

Marius Heinen, Martin Mulder, Jos van Dam, Ruud Bartholomeus, Quirijn de Jong van Lier, Janine de Wit, Allard de Wit, and Mirjam Hack-ten Broeke

Modelling soil-water-atmosphere-plant interactions and the modelling of processes in the unsaturated zone is performed in research and engineering projects worldwide, often extended to practical applications by stakeholders. The hydrological model SWAP stands out as a frequently used tool in this context. We consider the SWAP model and its predecessors like SWATR and SWACROP to have been initiated half a century ago, in 1974, in an article by Feddes, Bresler and Neuman in Water Resources Research entitled ‘Field test of a modified numerical model for water uptake by root systems’.

 

Over the years, the evolution to the present version of SWAP went through a great number of alterations, additions and improvements. In this contribution we will provide an overview on these developments, especially those from most recent years. This will include, amongst others, root growth dynamics, root water uptake and links to crop growth modelling. We aim on further improvements given new challenges like those resulting from climate change, extreme weather events, aspects of environmental sustainability, model parameterization, and model structure.

 

How to cite: Heinen, M., Mulder, M., van Dam, J., Bartholomeus, R., de Jong van Lier, Q., de Wit, J., de Wit, A., and Hack-ten Broeke, M.: SWAP 50 year: Advances in modelling soil-water-atmosphere-plant interactions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21812, https://doi.org/10.5194/egusphere-egu24-21812, 2024.

EGU24-22231 | Orals | HS8.3.3

Forest succession drives systematic change of root-mycorrhizal foraging strategies 

Zeqing Ma, Gaigai Ding, Wenjing Zeng, Tao Yan, and Lijuan Sun

Plant nutrient foraging depends on roots and mycorrhizal fungi, which are affected by plant carbon (C) investment and soil nutrient availability. The C supply for root metabolism and associated fungi might be diminished as the host plant size increases, while the quality and quantity of soil nitrogen (N) change with forest succession. There is still no holistic understanding of how the organization of belowground mycorrhizal root structure and fungi in the nutrient acquisition continuum shifts with forest age and soil resources, which restrains our understanding of the functional relations among roots, fungi, and soil. Here we examined the shifts in the absorptive root and mycorrhizal strategies, and changes in soil-associated fungal community compositions along a temperate larch forest chronosequence nested with a long-term N fertilization gradient. We found that the effect of forest age outweighed soil N addition in our forest. As tree age increased, root respiration and specific root length decreased, but protective investments such as tissue density and phenolics decreased. Meanwhile, the proportion of ectomycorrhizal fungi with a short-distance exploration type increased, but those with a long-distance exploration type decreased. The shifts in root and mycorrhizal fungal traits demonstrate a nutrient acquisition continuum from "young explorative roots with long mycorrhizas" to "mature conservative roots with short mycorrhizas". A trade-off between the root architecture and root segment metabolism, and a complementarity between the size of the root system and mycorrhizal exploration types functionally constrains this nutrient acquisition continuum. Our results thus suggested forest succession drives the covariations among root system size, root metabolic rate, mycorrhizal fungal exploration type, and soil-associated fungal functional groups.

How to cite: Ma, Z., Ding, G., Zeng, W., Yan, T., and Sun, L.: Forest succession drives systematic change of root-mycorrhizal foraging strategies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22231, https://doi.org/10.5194/egusphere-egu24-22231, 2024.

EGU24-219 | ECS | Posters on site | BG3.13

Rhizodeposition in the Plant Economic Space for 15 grassland species and its links to biogeochemical cycles (C,N) 

Chloé Folacher, Estelle Forey, Angèle Branger, Matthieu Chauvat, and Ludovic Henneron

Understanding how photosynthetic carbon is delivered into the soil system through rhizodeposition is of utmost importance in a changing world, as it represents an essential part of carbon cycling in soils. The plant economic space (PES) is a theoretical model representing plant strategies resource acquisition strategies based on two independent trade-offs: (i) resource acquisition vs conservation and (ii) exploration outsourcing (cooperation with mycorrhizal fungi) vs do-it-yourself. The PES is known to be related to a set of chemical and morphological traits, but some physiological traits such as rhizodeposition lack attention because they are harder to measure, while they are crucial for our understanding of resource allocation strategies and their linkages to ecosystem processes. For example, gross rhizodeposition can represent more than 40% of belowground carbon allocation.

We aimed to provide more insights on the relationship between rhizodeposition and the two dimensions of the PES, with a focus on the second axis, as arbuscular mycorrhizal fungi (AMF) are supposed to play an essential role of sink in the sink/source model of rhizodeposition. To do so, we grew 15 grassland plant species with contrasting resource acquisition strategies in a 3-month long pot experiment, with or without litter inputs. By means of 13C pulse-labelling, we traced carbon fluxes from recent photosynthates in major pools, including above-and belowground parts of the plant, but also in microbial biomass and microbial functional groups using PLFAs, soil organic matter, and soil respiration. We also measured net and gross nitrogen mineralisation.

We hypothesise that (i) rhizodeposition will be strongly link to the fast-slow gradient, fast-growing species being associated with higher rhizodeposition rates, but (ii) rhizodeposition will also show significant relationships with the exploration gradient, as tighter plant-soil biota association – including more AMF colonisation – could promote higher rhizodeposition rate, because of sink mechanisms. Higher rhizodeposition should also be associated (iii) with a shift in microbial community toward functional groups more dependant to plant carbon such as AMF and Gram negative bacteria, as well as (iv) higher soil respiration and nitrogen mineralisation.

How to cite: Folacher, C., Forey, E., Branger, A., Chauvat, M., and Henneron, L.: Rhizodeposition in the Plant Economic Space for 15 grassland species and its links to biogeochemical cycles (C,N), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-219, https://doi.org/10.5194/egusphere-egu24-219, 2024.

EGU24-743 | ECS | Posters on site | BG3.13

Assessing Fine Root Production in Terrestrial Forests: A Comparative Analysis of AI and Human Annotation Using Minirhizotron Images 

Imogen Carter, Grace Handy, Marie Arnaud, Rob Mackenzie, Gael Denny, Abraham Smith, and Adriane Esquivel-Muelbert

Fine roots are a major source of the stabilised carbon in soils. However, the response of fine root production to an increase in atmospheric CO2 and its impact on carbon dynamics in terrestrial forests remain poorly understood. Minirhizotrons can help to quantify fine root production and associated carbon dynamics in long-term, in-situ experiments such as Free Air CO2 Enrichment experiments. Yet, using minirhizotrons requires the manual annotation of thousands of images. Artificial Intelligence (AI) technology for image processing is fast developing and has proven to be successful in simple systems, such as agronomous crops. Here, we quantified how AI (RootPainter) annotation compares with humans, and determined the implications in terms of root production and carbon dynamics in a mature deciduous forest (BIFOR-FACE). Firstly, we quantified the variation in outputs of 30 annotated minirhizotron images using AI and human analysts of varying levels of expertise, comparing them to a gold standard established through expert consensus. We find that root annotation varied substantially among humans, with novices and AI over-annotating root length by 244% and 206% respectively, compared to our gold standard. Secondly, we quantified root length for five minirhizotron tubes in March and June (n = 1060 images) using AI and then a trained human analyst. AI over-estimated root length by more than an order of magnitude compared to a trained human user, and there was a poor linear relationship between annotated images with  AI and humans (r² < 0.22 for both months). This over-annotation by AI resulted in inaccurate quantification of root production and mortality, and thus erroneous carbon budget.

How to cite: Carter, I., Handy, G., Arnaud, M., Mackenzie, R., Denny, G., Smith, A., and Esquivel-Muelbert, A.: Assessing Fine Root Production in Terrestrial Forests: A Comparative Analysis of AI and Human Annotation Using Minirhizotron Images, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-743, https://doi.org/10.5194/egusphere-egu24-743, 2024.

The enhancement of biodiversity's positive impact on ecosystem functioning (BEF) over time is commonly observed and attributed to the accumulation of mutualists and dilution of antagonists in more diverse communities. If antagonists play a role in the BEF relationship, the reduction of plant antagonists in more diverse communities, could allow plants to reduce allocation to defence. This study aimed to assess the influence of plant diversity on the expression of defence traits in 16 plant species. Our hypotheses were: (1) increased plant diversity reduces allocation to defence, (2) this reduction is more pronounced in roots than in leaves, and (3) this effect varies among species.

We measured both physical and chemical defence traits in leaves and fine roots across communities with varying plant species richness in a 19-year-old biodiversity experiment. Using established methods and an innovative metabolome approach, we explored the interactive effects of plant diversity and species identity on defence traits through linear mixed models.

Our findings were mixed concerning the first hypothesis, with only some leaf defence traits (leaf mass per area, leaf dry matter content, and hair length) showing reduction along the diversity gradient. Unexpectedly, the values of some root traits, root tissue density and nitrogen content, suggested increased allocation to defence along the same gradient. This might be attributed to these traits serving other functions, e.g. in resource acquisition and competition, which potentially overruled the impact of declining antagonists on plant defences. Our results did not support the third hypothesis, suggesting an overall convergence responses to biotic and abiotic factors related to plant diversity after two decades.

While evidence for a consistent reduction in defence trait expression along the diversity gradient was limited, our findings underscore the complex nature of BEF relationships. Further experiments, possibly controlling confounding factors on trait expression or manipulating antagonist pressures along diversity gradients, are needed to elucidate the underlying mechanisms.

How to cite: Bassi, L.: Intra- and inter-specific changes in leaf and root defence traits along an experimental plant diversity gradient., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3368, https://doi.org/10.5194/egusphere-egu24-3368, 2024.

Road construction efforts have significantly increased in developing countries in recent decades. While expanding road networks have promoted economic development, it may result in the fragmentation of ecological landscapes and an increased risk of soil erosion. However, knowledge about these consequences is limited. This study aimed to characterize the expansion of the road network, landscape ecological risk, and soil erosion sensitivity on the Luochuan tableland of the Chinese Loess Plateau from 1990 to 2020. In this study, the landscape ecological risk refers to the spatial and temporal heterogeneity within a region, as well as the scale effect and the impact of landscape pattern fragmentation on regional ecological risk. The results of this study showed that 1) the road network on the Luochuan tableland has significantly expanded over the past 30 years, and the proportion of areas with high road density (kernel density value > 120 km/km2) increased from 10.13% to 37.18% of the total area between 1990 and 2020. 2) The landscape ecological risk was the highest in 2005; from 1990 to 2005, the land area with extra-high landscape ecological risk increased from 0 to 13.30 km2 and then decreased to 0 in 2020. 3) Similar to the variations in landscape ecological risk, the soil sensitivity was severe in 2005 on the Luochuan tableland. 4) Areas with a higher landscape ecological risk were mainly concentrated in areas of high road density. The road kernel density was significantly and positively correlated with landscape ecological risk and soil erosion sensitivity (P < 0.01). This study could help to understand the potential impact of road network expansion on landscape ecological risk and soil erosion at a regional scale.

How to cite: Yang, S. and Jin, Z.: Impact of road network expansion on landscape ecological risk and soil erosion sensitivity on the Luochuan Tableland of the Chinese Loess Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3397, https://doi.org/10.5194/egusphere-egu24-3397, 2024.

EGU24-3412 | ECS | Posters on site | BG3.13

Unravelling the spatial structure of regular environmental spatial patterns  

Karl Kästner, Roeland C. van de Vijsel, Daniel Caviedes Voullieme, and Christoph Hinz

Spatial patterns where patches of high biomass alternate with bare ground occur in many resource-limited ecosystems. Especially fascinating are regular patterns, which are self-similar at a lag distance corresponding to the typical distance between patches. Regular patterns are understood to form autogenously through self-organization, which can be generated with deterministic reaction-diffusion models. Such models generate highly regular patterns, which repeat at the characteristic wavelength and are therefore periodic. Natural patterns do not repeat, as they are noisy and as the patch size and spacing vary. Natural patterns are therefore usually perceived as perturbed periodic patterns. However, the self-similarity of natural patterns decreases at longer lag distances, which indicates that their spatial structure is not a perturbed periodic structure originating through deterministic processes. Here, we provide an overview of our recent work on the spatial structure and formation of natural environmental spatial patterns as a basis for discussion: First, we develop a statistical periodicity test and compile a large dataset of more than 10,000 regular environmental spatial patterns. We find that neither isotropic (spotted) nor anisotropic (banded) patterns are periodic. Instead, we find that their spatial structure can be well described as random fields originating through stochastic processes. Second, we recognize the regularity as a gradually varying property, rather than a dichotomous property of being periodic or not. We develop a method for quantifying the regularity and apply it in a metastudy to a set of natural and model-generated patterns found in the literature. We find that patterns generated with deterministic reaction-diffusion models do not well reproduce the spatial structure of environmental spatial structure, as they are too regular. Third, we develop an understanding of pattern formation through stochastic reaction-diffusion processes, which incorporate random environmental heterogeneities. We find that regular patterns form through filtering of the environmental heterogeneities and identify stochastic processes which reproduce both isotropic and anisotropic patterns.

How to cite: Kästner, K., van de Vijsel, R. C., Caviedes Voullieme, D., and Hinz, C.: Unravelling the spatial structure of regular environmental spatial patterns , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3412, https://doi.org/10.5194/egusphere-egu24-3412, 2024.

EGU24-5143 | Posters on site | BG3.13

Quantification of rhizodeposition and priming effect of intermediate crops via 13CO2 labeling. 

Baptiste Hulin, Simon Chollet, Folrent Massol, and Samuel Abiven

When assessing the carbon storage potential of a crop, it is useful to 1) quantify the inputs that return to the soil, such as roots, rhizodeposition and sometimes aboveground biomass, and 2) estimate the carbon gains or losses attributed to the priming effect. This allows to draw up a balance of inputs and outputs at the end of the growing season. While the quantity of carbon supplied by roots and aboveground biomass is relatively easy to measure, the quantity of rhizodeposition and the priming effect are not.

To establish such a balance, 12 intercropping plant species from 3 plant families (brassicaceae, fabaceae and poaceae) were grown for two months in mesocosms (15 liters) under controlled conditions simulating a temperate summer climate in real time in an ecotron. Multi-pulse atmospheric labeling with 13CO2 99% was used to trace photosynthesized carbon and thus quantify aboveground and root biomass, rhizodeposition and variations in carbon stock due to the priming effect.

The results show that rhizodeposition represents a significant carbon input (around a quarter of root biomass), positively correlated with root biomass. Root biomass is therefore one of the main traits to be considered for increasing inputs. At the same time, 10 out of 12 plants accelerated the mineralization of soil organic matter (positive priming effect), resulting in a cumulative carbon loss over the course of the plant's growth that can be of the same order of magnitude as the biomass input.

This priming effect is highly heterogeneous and difficult to explain by plant traits, but seems quantitatively more important for brassicaceae. We propose that this variability is due both to the spatial heterogeneity inducing these processes, but also to the great variability of processes that can occur in the rhizosphere, processes that can simultaneously lead to an acceleration and/or deceleration of the decomposition of native soil organic matter.

How to cite: Hulin, B., Chollet, S., Massol, F., and Abiven, S.: Quantification of rhizodeposition and priming effect of intermediate crops via 13CO2 labeling., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5143, https://doi.org/10.5194/egusphere-egu24-5143, 2024.

EGU24-5403 | ECS | Posters on site | BG3.13

Effects of soil phosphorus on root exudates in central Amazonia 

Tatiana Reichert, Lucia Fuchslueger, Sara A. L. de Andrade, Taryn Bauerle, Alexandre Borghi, João P. Darela-Filho, Katrin Fleischer, Benjamin Hafner, Iain P. Hartley, Raffaello Di Ponzio, Carlos A. Quesada, Anja Rammig, Jessica Schmeisk, and Laynara F. Lugli

Plants in tropical forests are thought to allocate a substantial portion of their photosynthetically fixed carbon (C) to the rhizosphere as exudates. These exudates serve multiple functions, including the mobilization of soil nutrients such as phosphorus (P), which is crucial for plant growth. In Amazonia, the predominant soils have notably low P concentrations, and plants likely employ a variety of strategies for P acquisition. However, the role of root exudates in P-impoverished Amazonian soils has not been empirically explored so far. To fill this gap, we investigated the largely uncharted territory of root exudation, as part of the Amazon fertilization experiment (AFEX), in a mature tropical forest growing on highly-weathered P-impoverished soils of central Amazonia. Our research examined root exudation in situ, both under natural soil conditions and P addition. We assessed the concentration of total organic carbon (TOC), total nitrogen (TN), and a suite of organic acids in root exudates, as well as additional root physiological and morphological traits of relevance, to potentially explain the variability in root exudation rates.

Our study revealed higher root exudation rates of TOC and organic acids in control, compared to P-addition plots, which suggests that plant C allocation to root exudates is an adaptive response to P availability. We also found that root exudation traits align with various morphological and physiological traits within the root economic space. Our findings provide insights into the hidden dynamics of root-soil interactions and have significant implications for understanding C cycling in tropical forests, shedding light on the complex coordination of root P acquisition strategies under different soil P conditions. 

How to cite: Reichert, T., Fuchslueger, L., de Andrade, S. A. L., Bauerle, T., Borghi, A., P. Darela-Filho, J., Fleischer, K., Hafner, B., Hartley, I. P., Di Ponzio, R., A. Quesada, C., Rammig, A., Schmeisk, J., and Lugli, L. F.: Effects of soil phosphorus on root exudates in central Amazonia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5403, https://doi.org/10.5194/egusphere-egu24-5403, 2024.

EGU24-7383 | Orals | BG3.13

Water availability controls seasonal shifts in root growth timing 

Richard Nair, Martin Strube, Marion Schrumpf, and Mirco Mirco.MIGLIA

Root growth dynamics are difficult to observe both on phenological and sub-daily scales as manual destructive measurement is high effort and prone to error. Close synchrony and prescriptive links with more easily observed above ground dynamics on seasonal timescales are often assumed, affecting interpretation of greenhouse gas fluxes without a solid basis in observational whole system data. Increasingly, we now recognize that seasonal root growth can be desynchronized from leaves, causing a rethink of these relationships. However sub-daily patterns are still opaque because measuring field root dynamics remains extremely difficult, especially this frequently. This is even more true over sustained, seasonal timescales where controls and dynamics may shift. Potential drivers of diel growth include photosynthesis (carbon), cell turgor (water), environmental temperature, and intrinsic circadian rhythms. Controls may differ through time, and between organs, and are difficult to separate under natural conditions in observational studies.

We use automated minirhizotrons and neural networks for image interpretation to bypass many previous observational constraints and gather resampled root dynamics data at up to sub-daily resolution. We observing roots four times a day for two years, every day, in a temperate grassland in Germany. We observed a strong underlying cell turgor signal in these uniquely frequent observations, visible through diel oscillation of root width. Removing this signal, we found root growth generally had little diel pattern except in periods of leaf-level water stress. Here roots consistently grew during the day and not at night. We examine the reasons for this switch in diel dynamics through the lens of potential environmental, water and carbon control. We found little evidence for direct temperature limits in our system. Instantaneous C supply, which should increase as canopies develop through the season, also did not appear to impact rate of growth despite previous isotope tracer studies showing a tight temporal coupling between carbon assimilation and bulk soil CO2 efflux. Our observations point towards water and cell turgor as the main control on root growth timing variation in contrast to the carbon-centric view of plant-soil system functioning indicated by pulse chase experiments. Underlying growth dynamics and their controls should be considered when interpreting whole system fluxes, and their sensitivity to environmental conditions in our dynamic and changing world.  

How to cite: Nair, R., Strube, M., Schrumpf, M., and Mirco.MIGLIA, M.: Water availability controls seasonal shifts in root growth timing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7383, https://doi.org/10.5194/egusphere-egu24-7383, 2024.

EGU24-7528 | ECS | Posters on site | BG3.13

Increasing root-derived soil carbon input to agricultural soils by variety selection of winter wheat 

Henrike Heinemann, Felix Seidel, Axel Don, and Juliane Hirte

Climate change mitigation and adaptation is a major challenge of modern agriculture. Increasing the incorporation of atmospheric carbon (C) as organic matter into soils through improved crop management seems to be a promising agricultural management option for supporting climate change mitigation. In order to build up soil organic C increased organic C inputs to the soil are urgently needed. In agricultural soils, crop roots are the major source of C inputs and pivotal for long-term C storage compared to aboveground biomass as their turnover is 2 to 3 times slower. This suggests, that variety selection towards increased root biomass can enhance root C inputs to the soil and could therefore increase C stocks and potentially facilitate C sequestration in soils. To quantify whether biomass allocation is affected by variety x environment interaction, we assessed root biomass, root distribution to 1 m soil depth and root: shoot ratios in a set of 10 different varieties grown at 11 experimental sites, covering a large European climatic gradient from Spain to Norway.

Preliminary results show a broad variety-specific variation in biomass production and its allocation between roots and shoots. Root biomass ranged from 1 to 3.5 Mg ha-1 in the best variety and could be increased by 20% by selecting the best variety compared to the average root biomass without compromising yield. Root to shoot ratios varied between 0.04 and 0.58 with a mean of 0.16. Increased root biomass due to deeper roots may stabilise yields under future climate change conditions where increased frequency of drought events during vegetation periods are expected and may therefore be a climate change adaptation measure that increases the crops resilience towards changing environmental conditions. Thus, improved variety selection can help to achieve both goals of modern agriculture: climate change mitigation and adaptation.

How to cite: Heinemann, H., Seidel, F., Don, A., and Hirte, J.: Increasing root-derived soil carbon input to agricultural soils by variety selection of winter wheat, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7528, https://doi.org/10.5194/egusphere-egu24-7528, 2024.

EGU24-8136 | ECS | Posters on site | BG3.13

Model-based evaluation of the impact and longevity of a novel sustainable subsoil melioration method (Soil³ method) on root growth  

Tobias Selzner, Anne E. Berns, Daniel Leitner, and Andrea Schnepf

The subsoil, commonly defined as the soil beneath the tilled or formerly tilled soil horizon, contains large amounts of nutrients and water. Large fractions of these subsoil resources are not readily available to agricultural crops due to compacted layers of high bulk density. Although there are conventional methods for loosening compacted subsoils (e.g., mechanical subsoiling and deep ploughing), their effects are often quickly reversed or can even be harmful to the soil structure. Eventually, the brief enhancement in subsoil access for crops is often insufficient to justify the considerable expenses associated with the methods. To facilitate a more efficient use of subsoil resources, the Soil³ project for sustainable subsoil melioration derived a novel  approach, which is carried out in a single crossing of the field. First, the top soil of a 30 cm wide strip is excavated and deposited on the soil surface beside the strip, creating a furrow. The subsoil in this furrow (30-60 cm depth) is then loosened and intermixed with organic material (e.g., compost). After mixing, the excavated topsoil is lead back into the furrow, thus closing it again. The method therefore preserves the natural soil structure by not mixing the top and subsoil substrates, while the loosened subsoil structure is stabilized by incorporating organic material. Additionally, the operating costs are kept reasonable by only loosening the soil in a strip-wise manner.

Here, we use and extend the 3D functional-structural plant model CPlantBox to investigate the impact of the Soil³ method on root growth. On the soil side, we employ pedo-transfer functions to model the evolution of soil bulk density (soil setting) and the resulting changes in soil hydraulic properties in time. The pedo-transfer functions are parameterized based on data of the Soil³ field trials and are solved for different soil depths, as well as for the soil layers on and beside the melioration strips. In our model, we account for the time-dependent changes in soil hydraulic properties of all soil layers by implementing the usage of variable Van-Genuchten parameter sets within a single simulation run. Based on the parameterized soil domain, we simulate root growth and root water uptake from the different soil layers. Experimental data is used to parameterize general root growth parameters (e.g., root length density, planting density, transpiration). The explicit 3D root system architecture, however, is a result of the model, and its growth is modeled as a function of bulk density, water content and penetration resistance. By performing virtual replications of the field trials over multiple consecutive years, we can evaluate the impact and longevity of the subsoil melioration on root growth and its underlying processes.

How to cite: Selzner, T., Berns, A. E., Leitner, D., and Schnepf, A.: Model-based evaluation of the impact and longevity of a novel sustainable subsoil melioration method (Soil³ method) on root growth , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8136, https://doi.org/10.5194/egusphere-egu24-8136, 2024.

EGU24-8292 | ECS | Orals | BG3.13

Exploring the root economics space in shrub-encroached subalpine grasslands 

Elena Tello-García, Anna-Lena Neunteufel, Lucía Laorden-Camacho, Marie-Nöelle Binet, Camille Marchal, Marie-Pascale Colace, Karl Grigulis, Bello Mouhamadou, Ursula Peintner, Ulrike Tappeiner, Sandra Lavorel, and Georg Leitinger

Shrub encroachment, a global phenomenon caused by land abandonment and shifts in traditional land use practices, is particularly prevalent in subalpine grasslands. This ecological shift is characterized by increased woodiness, which leads to changes in biogeochemical cycles and microbial composition. These changes in turn impact the soil's abiotic environment, particularly on carbon and nitrogen availability. While the influence of these changes on aboveground plant traits is well recognized, a substantial knowledge gap remains regarding their effects belowground. Understanding how shrub encroachment affects root morphological traits and mycorrhization is crucial, as they play a key role in nutrient uptake and transfer. This study focuses on the effects of shrub encroachment on root morphological traits and arbuscular mycorrhiza fungi (AMF) colonization at the levels of both herbaceous plants and of communities, i.e. including herbaceous and dwarf shrub plants, along a gradient of shrub encroachment in subalpine grasslands. We also aimed to describe the root economics space in encroached grasslands and to identify key soil changes correlated with changes in root traits. In herbaceous plants, shrub encroachment decreases AMF colonization and specific root length (SRL), and increases root tissue density (RTD). At the community level, AMF colonization, SRL, and RTD all decrease with shrub encroachment. Surprisingly, the observed root economics space at the community level does not follow the already established negative correlations of “do-it-yourself” strategies with high SRL and “outsourcing” strategies with increased root diameter and AMF colonization. Moreover, we observed a negative correlation between RTD and AMF. Our results highlight the importance of soil characteristics, specifically the carbon/nitrogen ratio (C:N) and soil pH, for changes in root traits. We conclude that shrub encroachment promotes the development of shorter and less dense roots and causes a decrease in AMF colonization through changes in the soil abiotic environment, such as an increase in C:N and a decrease in pH. This research provides valuable insights by expanding our understanding of belowground responses to shrub encroachment and highlights the importance of considering root traits in the broader context of ecosystem functioning.

How to cite: Tello-García, E., Neunteufel, A.-L., Laorden-Camacho, L., Binet, M.-N., Marchal, C., Colace, M.-P., Grigulis, K., Mouhamadou, B., Peintner, U., Tappeiner, U., Lavorel, S., and Leitinger, G.: Exploring the root economics space in shrub-encroached subalpine grasslands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8292, https://doi.org/10.5194/egusphere-egu24-8292, 2024.

EGU24-9347 | ECS | Posters on site | BG3.13

The impacts of several global change drivers on tropical root traits and dynamics 

Laynara F. Lugli and Daniella Yaffar and the TropiRoots Network - Tropical Root Trait Initiative

Tropical ecosystems are threatened by escalating anthropogenic activities that worsen global change, potentially disrupting the carbon (C) equilibrium in tropical forests and affecting global climate regulation. While considerable research has explored the impact of global change on aboveground tropical vegetation, our comprehension of belowground components, particularly roots that mediate plant-soil interactions, such as nutrient and water uptake, remains limited. We conducted an analysis of existing research on how tropical roots respond to key global change drivers, including warming, drought, flooding, cyclones, nitrogen (N) deposition, elevated (e) CO2, and fires. Drawing from tree species- and community-level outcomes from experimental studies, we compiled 266 root trait observations from 96 studies conducted across 24 tropical countries. From the existing knowledge, we noted in this review that tropical root systems tend to increase in biomass in response to warming and eCO2, but community-level experiments were rare for warming and non-existent for eCO2. Drought increased root:shoot ratio without changing root biomass, indicating a reduction in aboveground biomass. While N deposition may not greatly impact most tropical forests in the short term due to strong phosphorus limitation, mycorrhizal colonization and root phosphatase exudation were predominantly down- and up-regulated, respectively. Cyclones, fires, and flooding resulted in decreased root biomass, which, under elevated CO2 and warming, could lead to greater carbon losses from tropical soils. Cyclones and fires increased root production, potentially in response to plant community shifts and nutrient input, while flooding altered compounds related to plant regulatory metabolism due to low oxygen conditions. We also emphasize the importance of in situ studies, comparing adapted versus non-adapted species to these disturbances and the need for methodological consistency among experiments. Our findings underscore the necessity for further research to enhance our understanding of tropical root responses to global changes. The responses of root traits and dynamics to several global change drivers would affect the functioning of the whole forest and, consequently, carbon cycling and stocks above and belowground.

How to cite: Lugli, L. F. and Yaffar, D. and the TropiRoots Network - Tropical Root Trait Initiative: The impacts of several global change drivers on tropical root traits and dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9347, https://doi.org/10.5194/egusphere-egu24-9347, 2024.

EGU24-9636 | ECS | Posters on site | BG3.13

Exudate dynamics and rhizosphere priming in wetland ecosystems 

Namid Krüger and Peter Mueller

The release of organic substances from roots (exudates) to the soil system can induce changes in the mineralization rate of soil organic carbon (SOC) via so-called priming effects. Compared to other terrestrial ecosystems, mechanistic knowledge about priming effects in anoxic wetland soils is scarce, and few studies have investigated the composition and magnitude of root exudation in wetland plants. Given the disproportionate role of wetlands in the global soil carbon budget, this represents a critical knowledge gap in our understanding of terrestrial soil-climate feedbacks.

Here we present data from (1) a meta-analysis to summarize all quantitative and qualitative observations on wetland root exudation; and (2) exudate-surrogate incubation experiments testing for exudate effects on wetland SOC decomposition under anoxic conditions.

The meta-analysis shows that few comparable data on wetland exudation rates exist because extraction methods differ strongly, and only few species have been evaluated frequently. The data demonstrate that wetland plants not only release sugars, amino acids and organic acids into the rhizosphere, but also secondary compounds with a high allelochemical (e.g. gallic acid) or decomposition-hampering potential (e.g. phenolics). Their combined effect on the stability of soil carbon stocks is currently unpredictable on the ecosystem level. Our incubation experiments show that labile C inputs into an anoxic soil have a great potential to suppress SOC decomposition via negative priming. This finding contrasts to positive priming effects commonly found in oxic terrestrial soils and yields important implications for the stability of wetland SOC stocks in response to climate induced vegetation shifts.

How to cite: Krüger, N. and Mueller, P.: Exudate dynamics and rhizosphere priming in wetland ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9636, https://doi.org/10.5194/egusphere-egu24-9636, 2024.

The Hengduan Mountains (HDM) is one of the most biologically diverse mountain ranges on the planet, with exceptionally high levels of endemism. We expect that the geological and climate changes of the regions shaped endemism though dispersal and speciation processes by modulating landscape connectivity. Here, we characterise the plant endemism in the HDM, by mapping the distribution of 3,165 endemic species, representing approximately 25% of the total plant species richness. We show that endemic richness is highest along the southern front of the HDM, and especially concentrated along the Shangri-la Plateau and the three-river parallel region at elevations between 2,700 and 4,200 meters a.s.l. We demonstrate a geographically differentiated effect of connectivity on endemic richness and composition. In the endemic hotspot, we find a negative connectivity-diversity relationship, while we find a positive connectivity diversity relationship in the northern and southern HDM. Our result suggests a dominant role of isolation-induced allopatric speciation. Low connectivity may facilitate allopatric speciation in shaping distinct lineage in central HDM; while in the north of HDM, similar cold habitats in high elevation where habitats are more connected than the southern part, have likely facilitated species migration during the Quaternary glaciation. Thus, the degree of connectivity varied within HDM depending on their topographical configuration. Geographic contrasts in diversity further match endemic composition, which suggest the effect of geological history in shaping the diversity and composition of this exceptional flora. Overall, we conclude that landscape connectivity is a key driver of endemic plant speciation in HDM, explaining richness patterns that cannot be explained by temperature and other classic predictors.

How to cite: Yuan, Z.: Regional hotspots of Hengduan plant endemism inferring local speciation in response to connectivity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9893, https://doi.org/10.5194/egusphere-egu24-9893, 2024.

EGU24-12367 | ECS | Posters on site | BG3.13

Increasing root trait complementarity in species mixtures may be detrimental for soil carbon storage 

Shuang Yin, Xinli Chen, César Terrer, Zhenghu Zhou, Ji Chen, and Diego Abalos

Designing plant mixtures with potential to increase soil organic carbon (SOC) appears to be a powerful nature-based tool to restore some of the carbon lost in agroecosystems. However, we are uncertain about the best way to design such benign plant mixtures. Trait-based approaches are increasingly used to explain the relationship between plant diversity and ecosystem functions, offering a conceptual opportunity to address this knowledge gap. In this study, we combine a global meta-analysis of 407 paired SOC content observations with a root traits database from GRooT, to explore the optimum way for the design of plant mixtures to increase SOC. We found that specific root traits at the community level were important predictors of the response of SOC to plant mixtures. Species mixtures could increase SOC content when the overall plant community had low variation in root mycorrhizal colonization and root tissue density. The positive response of SOC content to species mixtures was linked to increases in soil microbial biomass carbon and root biomass. Additionally, the SOC enhancements by plant mixtures were often found in regions with high precipitation and low sand content. Our meta-analysis presents a framework based on plant traits to enhance SOC sequestration using plant mixtures, which will enable farmers to optimize plant mixtures towards soil carbon sequestration.

How to cite: Yin, S., Chen, X., Terrer, C., Zhou, Z., Chen, J., and Abalos, D.: Increasing root trait complementarity in species mixtures may be detrimental for soil carbon storage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12367, https://doi.org/10.5194/egusphere-egu24-12367, 2024.

EGU24-13758 | ECS | Posters on site | BG3.13

Assessing Sediment Delivery from Catchment Areas to Coastal Ecosystems in the Pacific Islands: A Study in an Urban Context 

Eliana Jorquera, Jose Fernando Rodriguez, Patricia Mabel Saco, Juan Pablo Quijano Baron, Angelo Breda, Steven Sandi, Danielle Verdon-Kidd, and Filomena Nelson

Coastal mangroves provide vital habitats for marine and coastal ecosystems while also stabilising coastlines, preventing erosion and mitigating the impact of storms. Sea-level rise poses a significant threat to these areas, causing submergence, vegetation changes, and hydrodynamic alterations. Sediment accretion can attenuate the effects of sea-level rise by promoting sedimentation. Mangroves trap sediments with their roots, which gradually create soil layers. The balance between soil accretion and sea-level rise will determine the mangrove's ability to adapt and survive. It is, therefore, crucial to determine the amount of water and sediments produced in the tributary catchment that reaches mangrove areas.

Moata'a is an urban village on the Upolu Island of Samoa, comprising around 300 to 500 households. It is home to a mangrove wetland that has been negatively impacted by human activities such as urban expansion, uncontrolled extraction of natural resources, pollution, and modification of input flows and tidal regime. Furthermore, Moata'a is susceptible to extreme weather conditions such as tropical cyclones, floods, and droughts, which may worsen as a result of climate change.

The amount of water and sediments that flow into the Moata'a mangrove area is influenced by the Vaisigano River. Moata'a is situated in the Vaisigano River's floodplain region, one of the primary rivers on Upolu Island. The Vaisigano River catchment is characterised by a hilly terrain covered with forests and a narrow coastline. During significant flooding events, water is transferred from the Vaisigano to the Moata'a catchment. Significant sediments can be discharged into the mangrove areas in these extreme circumstances.

This contribution presents a hydro-sedimentological assessment of the Moata’a’s mangrove catchment. The Soil & Water Assessment Tool (SWAT) was used to quantify the amount of water and sediment generated in the Moata’a’s catchment and the water and sediments produced by the Vaisigano catchment that are transferred to Moata’a’s mangroves during extreme events.

How to cite: Jorquera, E., Rodriguez, J. F., Saco, P. M., Quijano Baron, J. P., Breda, A., Sandi, S., Verdon-Kidd, D., and Nelson, F.: Assessing Sediment Delivery from Catchment Areas to Coastal Ecosystems in the Pacific Islands: A Study in an Urban Context, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13758, https://doi.org/10.5194/egusphere-egu24-13758, 2024.

EGU24-14679 | ECS | Orals | BG3.13

Changes in soil organic carbon content affect plant available water more strongly in subsoil than in topsoil 

Laura Skadell, Ullrich Dettmann, and Axel Don

With the increase of drought events due to climate change, agricultural production is under pressure to maintain yields. The subsoil (> 30 cm) often harbours unexploited water and nutrient resources that can meet the needs of plants when the topsoil has already dried out. The fertility of the soil is also closely linked to its organic carbon (OC) content. A higher soil organic carbon (SOC) content can improve the soil structure, which is associated with a higher water infiltration rate and a higher water retention capacity and thus can facilitate the adaptation of agriculture to a changing climate. However, the knowledge about quantity changes, especially in subsoils, is insufficient. Therefore, we analysed soils from eleven field sites to quantify the effects of SOC content on topsoil and subsoil plant available water (PAW), here defined as the water content between pF = 1.8 and pF = 4.2. Long-term experiments were set up at four sites, which we sampled after a duration of 57-68 years. In addition, four short- to medium-term trials with a duration of <1-10 years were sampled, as well as three treposols that were deep ploughed once 52-54 years prior to sampling. At all sites there is a management-related OC gradient over a wide range of clay contents (4-28%). Preliminary results of the long-term experiments showed that topsoil SOC contents increased on average by 43 % after the application of farmyard manure. PAW was also higher, with an average increase of 6 %, indicating a positive correlation between SOC content and PAW, although this was not linear. Significantly stronger effects on PAW were observed in the subsoil, where changes averaged 40 %. Our results therefore emphasise the importance of considering the subsoil when adapting agriculture to changing climatic conditions.

How to cite: Skadell, L., Dettmann, U., and Don, A.: Changes in soil organic carbon content affect plant available water more strongly in subsoil than in topsoil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14679, https://doi.org/10.5194/egusphere-egu24-14679, 2024.

EGU24-14784 | ECS | Posters virtual | BG3.13

Vegetation Phenological Metrics and Accumulated Antecedent Precipitation (AAP) in dryland pastures. 

Carlos Brieva, Jose Rodriguez, and Patricia Saco

Vegetation dynamics in dryland systems is highly dependent on soil moisture availability. Arid and semi-arid ecosystems are under the pressure of climate change and are facing overgrazing and logging, leading to increased degradation and desertification. The drylands of Mendoza, Argentina, are fragile ecosystems devoted to cattle breeding on native bushes and rangelands. Livestock farming relies on the productivity of natural resources, closely related to the monthly, annual, and seasonal rainfall, which is a critical driver of vegetation productivity and dynamics. However, the limited availability of precipitation data from gauging stations prevents a detailed analysis of the relationship between rainfall and vegetation. Therefore, satellite-estimated rainfall becomes a valuable information source to overcome this constraint.

This study aims to analyze the relationship between the antecedent accumulated precipitation (AAP) and the vegetation dynamics in terms of phenological metrics (Length of Growing Season – LGS; Peak of Growing Season – PGS; Amplitude of Growing Season – AGS) for four vegetation types in Southeast Mendoza, Argentina (Bush steppe with low land cover; Open Bush; Forest of Prosopis Flexuosa; and Psammophilous Grassland).

Vegetation parameters were derived using the software TIMESAT from Savitzky-Golay smoothing NDVI series of MODIS-Terra (MOD13Q1 V6.1) over 20 years (June 2000 to May 2020) and then correlated to AAP estimated by satellite using GPM (Global Precipitation Measurement) considering three time periods: Spring (accumulated precipitation of September to December), Spring plus Summer (September to February) and the duration of the Growing Season of each vegetation type.

All vegetation types showed a similar response and behavior regarding the AAP and vegetation dynamics metrics. The LGSs are similar, from 187 days for Psammophilous grassland to 198 days for Forest of Prosopis. However, there are differences at the start of the season. The PGSs (peak of NDVI) and the AGS show higher correlations to the spring and summer precipitation, while the LGS correlates to spring and accumulated precipitation during the growing season.

This information can help manage cattle grazing, avoid overgrazing, and manage production sustainably. Tracking vegetation responses to rainfall in space and time is of utmost importance for managing the limited resources,

How to cite: Brieva, C., Rodriguez, J., and Saco, P.: Vegetation Phenological Metrics and Accumulated Antecedent Precipitation (AAP) in dryland pastures., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14784, https://doi.org/10.5194/egusphere-egu24-14784, 2024.

EGU24-16942 | Orals | BG3.13

Temperate Forest of 2050's: carbon and nutrient cycling responses to seven years of elevated CO2 enrichment at BIFoR-FACE 

Sami Ullah, Carolina Mayoral, Manon Rumeau, Richard Norby, Anna Gardner, Johanna Pihlblad, Michaela Reay, Grace Handy, Liz Hamilton, Kris Hart, Andy Smith, Iain Hartley, and Robert MacKenzie

Land ecosystems absorb ~29% of the total CO2 emissions from anthropogenic sources. Global forests contributes ~62% to the total land ecosystem atmospheric CO2 sinks. The carbon (C) sink in forests is predicted to increase with increasing atmospheric CO2 concentration, called the “CO2 fertilization effect”. However, the projections of the land C sink by the end of the 21st Century based on simulations of state-of-the-art Earth System Models (ESM) is relatively uncertain where a 25 to 50% reduction in the C sink is predicted when nutrient  availability including nitrogen (N)  is accounted for. This uncertainty emanates from poor representation of key ecosystem types, particularly mature forests, to changing nutrient supplies under eCO2.

To elucidate the feedbacks between elevated CO2 (eCO2), C capture and nutrient availability, the Birmingham Institute of Forest Research (BIFoR) established a Free-Air CO2 Enrichment (FACE) facility in a mature temperate forest in the UK, where three FACE arrays (30 m dia) are exposed to elevated CO2 (+150 ppm above the ambient) during the growing season.1 The FACE enrichment started in 2017 and continues to date. In response to the CO2 enrichment, photosynthetic CO2 uptake increased by an average of 23% in the first three years and this enhanced uptake was sustained by the seventh year of CO2 enrichment.2 The enhanced CO2 uptake resulted in an overall significant increase in tree dry matter (+10.5%) and a 28% increase in tree basal area increments.  Belowground C allocation via litter fall (+9.5 %), root exudates (+40%) and fine root biomass and specific root length in organic and mineral soil layers were increased as well. The overall net primary productivity calculated for years 2021 and 2022 was higher by ~2 tons of dry matter under eCO2 compared to ambient arrays confirming and quantifying the extent of the CO2 fertilization effect.

Whilst the litter fall increased under elevated CO2, the N content of the litter decreased significantly pointing towards N conservation via resorption by trees before senescence. Similarly, root C exudation increased; however, exudation of N was not affected, thus leading to a shift in the C:N ratio from an average of 13 to 18 under eCO2. Thus N was conserved via resorption and low root N exudation by trees to sustain enhanced photosynthesis and growth. Gross N mineralization rates were 20% higher under eCO2.3 Enhanced N cycling processes sustained larger soil mineral N supply (~25 kg N ha-1 y-1) under eCO2. Root uptake of N increased by 26% and potential uptake rates of amino acids was larger than mineral N. Tree N conservation and faster N cycling in soils appear to have sustained enhanced tree N uptake and demands. The implications of nutrient availability for C sequestration will depend on how long upregulation of soil N availability via soil organic matter decomposition will last before manifestation of nutrient limitation, if any.

References

1 Hart, K. M. et al. 2020. Global Change Biology 26, 1023-1037. https://doi.org:10.1111/gcb.14786

2 Gardner, A., et al. 2022. Tree Physiology 42, 130-144. https://doi.org:10.1093/treephys/tpab090

3 Sgouridis, F. et al. 2023. Soil Biology & Biochemistry 184. https://doi.org:10.1016/j.soilbio.2023.109072

 

How to cite: Ullah, S., Mayoral, C., Rumeau, M., Norby, R., Gardner, A., Pihlblad, J., Reay, M., Handy, G., Hamilton, L., Hart, K., Smith, A., Hartley, I., and MacKenzie, R.: Temperate Forest of 2050's: carbon and nutrient cycling responses to seven years of elevated CO2 enrichment at BIFoR-FACE, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16942, https://doi.org/10.5194/egusphere-egu24-16942, 2024.

EGU24-17586 | ECS | Orals | BG3.13

Root functional strategies as drivers of the functional composition of soil fungal communities 

Justus Hennecke and Alexandra Weigelt

Plant functioning heavily relies on roots. Many root functions, however, are intrinsically linked with fungal mutualists or can be reduced by fungal antagonists. Consequently, a better knowledge of the factors shaping fungal community composition is essential for our understanding of plant and ecosystem functioning. Beyond abiotic factors, the identity and composition of the plant community itself influence the soil fungal community. Depending on their root functional strategies, plants may engage differently with the soil microbial community. The root economics space (RES) has advanced our understanding of these root functional strategies, and the close association of the collaboration gradient with mycorrhizal fungi indicates that root traits could provide insights into soil fungal communities.

We hypothesize that root trait strategies along the collaboration and conservation axes of the RES, as well as plant diversity, influence the composition of soil fungal communities. For instance, we hypothesize a decrease in the abundance of plant pathogenic fungi in more diverse plant communities and those with well-defended species. Higher plant defense is typically associated with root traits related to high mycorrhization ("outsourcing") and high tissue density ("slow"). Arbuscular mycorrhizal fungi are expected to exhibit contrasting trends compared to pathogens. We expect saprotrophic fungi to be mostly affected by the change in litter quality along the conservation gradient (‘fast-slow’). Hence, our study explores the interactive and additive effects of root trait gradients and plant species richness on soil fungal communities.

In plots of the Jena Experiment with varying levels of plant species richness, we measured root traits at the community level and sampled soil microbial communities. Using amplicon sequencing, PLFA analyses, and microbial respiration measurements, we determined relative abundances of mycorrhizal mutualists, plant pathogens, and saprotrophs as well as absolute fungal and microbial biomass. Our findings indicate a significant decrease in the diversity and relative abundance of plant pathogenic fungi in plant communities with outsourcing root strategies. This highlights the central role of the root collaboration axis in shaping soil fungal communities beyond the direct link with arbuscular mycorrhiza. Changes in fungal and microbial biomass, however, are strongly determined by plant diversity and not driven by root traits.

How to cite: Hennecke, J. and Weigelt, A.: Root functional strategies as drivers of the functional composition of soil fungal communities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17586, https://doi.org/10.5194/egusphere-egu24-17586, 2024.

EGU24-17904 | Posters on site | BG3.13

Improved root development leads to higher root derived carbon stocks in formerly deep-plough soils - A biomarker-based approach 

Martina Gocke, Dymphie Burger, Florian Schneider, Arne Kappenberg, and Sara Bauke

Roots can add significant amounts of carbon (C) to the subsoil, which enhances soil fertility and can mitigate climate change. About 5% of agricultural soils in Germany have been deep-ploughed (ploughing depth 30-120 cm) at least once. This technique can provide better root access to the subsoil and may help to increase yields. Studies on deep-ploughed soils focused on C stability, whereas not much is known about root-derived C in the subsoil (>0.3 m). We hypothesized that five decades after deep-ploughing, root-derived C stocks were higher compared to conventionally ploughed treatments due to better root development. This was measured by analysing suberin and cutin monomers as tracers for root- and shoot-derived C at three former deep-ploughed sites in N Germany with different soil textures and different deep-ploughing depths. Concentrations of suberin monomers in the soil were positively correlated with root biomass, this was especially strong at one sandy site. Suberin contributed more to the bulk soil organic carbon (SOC) stocks than cutin throughout the soil profile, independently of the ploughing depth. The three sites responded differently to deep-ploughing. The contribution of suberin monomers to the bulk SOC stock at silty site Banteln and the sandy site Essemühle was 38% higher in the deep-ploughed plots than at the reference plot, respectively, these differences were most visible in the subsoil of Essemühle. We conclude that when deep-ploughing enhances C stocks and root development, suberin SOC stocks increase as well, especially in the subsoil of sandy sites with low pH.

How to cite: Gocke, M., Burger, D., Schneider, F., Kappenberg, A., and Bauke, S.: Improved root development leads to higher root derived carbon stocks in formerly deep-plough soils - A biomarker-based approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17904, https://doi.org/10.5194/egusphere-egu24-17904, 2024.

EGU24-18166 | Posters on site | BG3.13

Subsoil management as tool for climate-change adapted agriculture 

Wulf Amelung, Sabine Seidel, Kathlin Schweitzer, Michael Baumecker, Martina Gocke, Sara Bauke, and Oliver Schmittmann

Agricultural production in Central Europe increasingly suffers from extreme drought events. Improving root access to nutrient and water resources in the subsoil below the plow layer is a potential option to maintain productivity during dry summers. Here, we tested a strip-wise subsoil amelioration system that combines subsoil loosening with injections of 50 t per hectare fresh weight organic matter incorporation into the subsoil (biowaste or green waste compost) and compared it with a treatment comprising only subsoil loosening or a non-ameliorated control. Randomized block design field experiments were conducted on Luvisols and Retisols with an argic (Bt) horizon and rotations of spring barley and winter wheat as well as of rye and maize, respectively. We then monitored yields, protein contents as well as physical and chemical soil properties including changes in stable isotope composition as indicators for plant stress and nutrient uptake. We found that subsoil amelioration has the potential to prevent yield losses of up to 20% for cereals and up to 50% for maize after biowaste compost injection, particularly in dry summers, i.e., depending on weather conditions. These benefits were accompanied by a decrease in soil bulk density at the depth of compost incorporation when biowaste compost was used, but not when green waste compost had been incorporated. In contrast, nutrient stocks, nutrient availability, and microbial biomass were not consistently affected by the subsoil amelioration, but root growth was. Differences in crop development could not be explained by any single soil parameter, suggesting that it was rather a combined effect of loosened subsoil and better supply of subsoil resources that increased subsoil root length density and subsequent better crop performance when the summer was dry.

How to cite: Amelung, W., Seidel, S., Schweitzer, K., Baumecker, M., Gocke, M., Bauke, S., and Schmittmann, O.: Subsoil management as tool for climate-change adapted agriculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18166, https://doi.org/10.5194/egusphere-egu24-18166, 2024.

EGU24-19210 | Posters virtual | BG3.13

Management of belowground inputs is crucial to maintain soil carbon storage under climate change 

Cornelia Rumpel, Teng Hu, Sparkle Malone, and Abad Chabbi

Globally, agricultural soil management leads to soil organic carbon (SOC) losses, which contribute to increase atmospheric CO2 concentrations and thereby climate change. Grassland introduction into cropping phases (ley grasslands) was suggested as an appropriate management strategy to reduce these losses. Here we examine the impact of ley grassland durations in crop rotations on soil organic carbon in temperate climate from 2005 to 2100. We considered two IPCC scenarios, RCP4.5 and RCP8.5, with and without atmospheric CO2 enhancements. We used the DailyDayCent model and a long-term field experiment to show that ley grasslands increase SOC storage by approximately 10 Mg ha−1 over 96 years compared with continuous cropping. Surprisingly, extending ley duration from 3 to 6 years does not enhance SOC, while it had a positive effect on plant residue accumulation in soil. Furthermore, in comparison with non-renewed grasslands, those renewed every three years demonstrated a notable increase in SOC storage, by 0.3 Mg ha−1 yr−1. These results may be explained by the enhanced input of root C in young grassland systems and its preferential contribution to soil organic matter formation. We concluded that management of root C inputs by ley grassland ploughing and renewal intervals is crucial for maximizing SOC stocks in agricultural soils, through balancing biomass carbon inputs during regrowth and carbon losses through soil respiration.

How to cite: Rumpel, C., Hu, T., Malone, S., and Chabbi, A.: Management of belowground inputs is crucial to maintain soil carbon storage under climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19210, https://doi.org/10.5194/egusphere-egu24-19210, 2024.

EGU24-19602 | Posters on site | BG3.13

Influence of soil moisture content on water repellency after a forest burnt 

Glenda Garcia-Santos, Manjana Puff, Christian Kogler, Angel Fernandez, and Eileen Eckmeier

A wildfire occurred in 2012 in one of the protected relic laurel forests of Europe (the National Park of Garajonay, Canary Islands). Soils from unburnt and burnt areas were studied and compared on its water repellence level at different soil moisture content from 2004 till 2023. 32 study sites and more than 100 soils were prepared under saturation conditions (sprayed of distilled water on the surface of each sample). Starting from saturation till oven-dried conditions, lower soil moisture contents were established in successive increments after the end of the WDPT test. The petri dishes were weighted at each step to determine the gravimetric soil water content (g g -1) by the thermogravimetric method at the end of the sequence. To describe the influence of soil moisture content on water repellency, three phases were distinguished. Phases I and II corresponded with the air-drying phase and phase III to the oven-drying phase.

Results of the study highlight that the water repellency of in both unburned and burnt sites strongly depended on the soil moisture content. After 11 years from the fire, the infiltration capacity of the soils showed improved levels of water repellency and in some cases total recovery. In order to reproduce the soil hydrophobic behavior under naturally occurring drying conditions (phases I and II), the time required for infiltration was modelled as a function of gravimetric moisture content during air-drying. Variability (standard deviation) increased with increasing times to infiltration (i.e. decreasing moisture content), which can be attributed to evaporation and soil hydraulic effects influencing the results during longer tests.

 

How to cite: Garcia-Santos, G., Puff, M., Kogler, C., Fernandez, A., and Eckmeier, E.: Influence of soil moisture content on water repellency after a forest burnt, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19602, https://doi.org/10.5194/egusphere-egu24-19602, 2024.

EGU24-19700 | ECS | Orals | BG3.13

Topographic controls on lateral expansion and large-scale patterns of peatlands in the northern boreal landscape 

Betty Ehnvall, Joshua L. Ratcliffe, Elisabet Bohlin, Mats B. Nilsson, Mats G. Öquist, Ryan A. Sponseller, and Thomas Grabs

Despite their importance in global carbon and hydrogeochemical cycles, large-scale spatiotemporal analyses of the lateral expansion and landscape patterns of peatlands have been scarce. This has impeded our possibility to scale-up important peatland processes and properties, such as carbon accumulation to the landscape level. Here we combine landscape-level analysis of ten mire chronosequences to study lateral expansion rates, with an in-depth analysis of mire morphometry in a single chronosequence, to quantify controls on peatland distribution patterns. All ten chronosequences are located along the Swedish coast of the Bothnian Bay Lowlands, and span an age range of 0-9000 years of post-glacial land-uplift. Our findings challenge the widespread misconception of linear mire expansion, and showcase how the extent of entire mire populations evolved over the Holocene, and under the control of upland hydro-topography. Landscape wetness, for instance, favored more rapid lateral expansion rates in relatively young parts of the landscapes. Moreover, based on the in-depth analysis of over 3 000 peatlands at one chronosequence, we found time since land emergence an important control on peatland coverage, and on the formation of large mire complexes. Topography, on the other hand, controlled peatland fragmentation and number regardless of landscape age. Altogether, our results illustrate how time since initiation combined with topographic controls influenced lateral expansion, and present-day peatland distribution patterns in the northern boreal landscape.

How to cite: Ehnvall, B., Ratcliffe, J. L., Bohlin, E., Nilsson, M. B., Öquist, M. G., Sponseller, R. A., and Grabs, T.: Topographic controls on lateral expansion and large-scale patterns of peatlands in the northern boreal landscape, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19700, https://doi.org/10.5194/egusphere-egu24-19700, 2024.

EGU24-19872 | Posters on site | BG3.13

Subsoil amelioration in agriculture: Deep loosening and compost incorporation in a Retisol 

Julien Guigue, Kathlin Schweizer, Oliver Schmittmann, Michael Baumecker, and Ingrid Kögel-Knabner

Subsoils can store significant amounts of water, soil organic carbon and nutrients. In consequence, agricultural subsoil management is being increasingly tested as an option to sustain crop productivity under unfavourable conditions.

The Soil3 project funded by the Federal Ministry of Education and Research of Germany aims at investigating the potential of subsoil management for agriculture. In the frame of this project, we collected samples from a field experiment taking place in Thyrow (Brandenburg, Germany), at a location with low precipitations and the soil was classified as a Retisol. The experiment was designed to investigate the potential benefits of deep ploughing together with deep placement of organic fertilizers on agricultural productivity and soil organic matter stocks. We focus on three treatments, namely the control plots, the plots after deep loosening, and the plots after deep loosening and compost incorporation.

We quantified the changes in C and N stocks and in two size fractions obtained by wet sieving (<20µm and >20µm). We also recorded hyperspectral images of 1-metre soil cores in the Vis-NIR range (400-990 nm) and modelled the C distribution at a high spatial resolution (pixel size = 53×53 μm²).

The spatial distribution of soil organic matter resulting from the incorporation of organic fertilizer in the subsoil is modelled at the sub-millimetric scale. The organic matter stocks and C:N stoichiometry are both impacted by the agricultural management and the imaging technique allows us to distinguish between increased amount of organic matter in hotspots or in soil mineral matrix, and to discuss the mechanisms controlling the observed changes.

How to cite: Guigue, J., Schweizer, K., Schmittmann, O., Baumecker, M., and Kögel-Knabner, I.: Subsoil amelioration in agriculture: Deep loosening and compost incorporation in a Retisol, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19872, https://doi.org/10.5194/egusphere-egu24-19872, 2024.

EGU24-20148 | Posters on site | BG3.13

Exploring Non-traditional Metal(loid) Stable Isotope Tools for Agricultural Systems  

Anne E. Berns, David Uhlig, Bei Wu, Kathlin Schweitzer, Sara L. Bauke, Arnd J. Kuhn, Roland Bol, and Amelung Wulf

Ratios of non-traditional metal(loid) stable isotopes are a well-established tool in geosciences, used to semi-quantitatively trace geological transformation processes and biological cycling of mineral nutrients in the soil-plant system. Even though these processes also occur in agricultural systems, non-traditional metal(loid) isotope ratios are rarely used in agronomy. Their potential lies in revealing variations in isotope composition of metal elements like Fe and Mg between soil compartments and crops due to isotope fractionation occurring along the solubilization-uptake-translocation pathway [e.g., 1-5]. Agricultural management practices may influence isotope ratios in plant-available soil pools and, consequently, in plants.

The BonaRes-project Soil3 aims to enhance crop yield by optimizing nutrient and water use efficiency for field crops through subsoil management. We hypothesized that creating favorable conditions for crops in subsoil, like reducing physical resistance for roots or creating nutrient-rich hotspots, will stimulate crops to develop deeper root systems than without subsoil management. To examine our hypothesis, we altered subsoil conditions in field trials by cultivating deep-rooting pre-crops and employing technical subsoil improvement techniques through strip-wise deep loosening and organic matter injection. To assess the influence of standard management practices, such as liming, and possible nutrient deficiencies on isotope ratios in soil compartments and plants, we also investigated the isotope composition of nutrient pools in the deep subsoil of long-term field experiments and set up controlled pot experiments with defined nutrient conditions.

In the context of subsoil management experiments, we first conceptually explored the extent to which the Mg isotope composition of soil compartments and crops would be influenced by subsoil management. The novel outcome of this concept is that the Mg use efficiency of crops can be solely quantified from Mg stable isotope ratios, provided that agricultural lime is not applied to the fields [2]. Secondly, we used 87Sr/86Sr ratios to assess alterations in nutrient uptake depth in the subsoil managed plots. Our findings indicate that deep loosening with compost incorporation indeed deepened the nutrient uptake depth, with crops reaching previously unused nutrient reservoirs [6].

Regarding the influence of liming on Fe and Mg isotope compositions in a 100-year field experiment, we found a shift towards heavier Fe isotopes in rye, indicating an upregulation of the phytosiderophore complexation mechanism to counteract reduced Fe solubility at higher pH [5], and a pronounced shift towards lighter Mg isotopes in the exchangeable Mg pool, mainly attributed to an increased removal of heavy Mg isotopes by plant uptake [3]. A controlled pot experiment revealed that Mg deficiency altered the Mg isotope composition in wheat organs, indicating stress-induced shifts in Mg translocation within the plant [4].

Non-traditional metal(loid) stable isotopes hence provide powerful insights into biogeochemical cycling of nutrients that conventional analyses cannot detect.

[1] Wu et al., Earth-Science Reviews 2019, 190:323-352.

[2] Uhlig et al., Chem. Geol. 2022; 611:121114.

[3] Wang et al., Eur. J. Soil Sci. 2021; 72:300–312.

[4] Wang et al., Plant Soil 2020; 455:93–105.p

[5] Wu et al., Eur. J. Soil Sci. 2021; 72:289-299.

[6] Uhlig et al., Plant Soil 2023; 489: 613–628.

How to cite: Berns, A. E., Uhlig, D., Wu, B., Schweitzer, K., Bauke, S. L., Kuhn, A. J., Bol, R., and Wulf, A.: Exploring Non-traditional Metal(loid) Stable Isotope Tools for Agricultural Systems , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20148, https://doi.org/10.5194/egusphere-egu24-20148, 2024.

During last glacial cycle that peaked ~18,000 years (B.P.), the southwestern United States was much wetter and cooler than in the Holocene (last 11,000 years) and today. Since the Last Glacial Maximum (LGM), wetter and cooler climate in most arid and semiarid regions has generally transitioned to drier and warmer conditions, establishing their characteristic (i.e., today’s native) ecosystems and fire regimes 3,000 - 5,000 years B.P. We use the Landlab earth surface modeling toolkit to explore the implications of the climate since the late Pleistocene on ecosystem patterns, driven by a reconstructed climate. Alternative grass and shrubs states emerged as the modern climate established due to randomness in fire arrivals. The role of topography is explored. Our findings offer an explanation for observed shrub and grass ecotones under similar environmental conditions in central New Mexico. 

How to cite: Istanbulluoglu, E., Nudurupati, S., and Collins, S.: Alternative grass and shrub states emerge in paleo-climatic cellular-automaton ecohydrology model simulations for central New Mexico, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21054, https://doi.org/10.5194/egusphere-egu24-21054, 2024.

EGU24-21749 | Orals | BG3.13

Effect of different methods of subsoil loosening on the physical soil properties, root growth, soil water withdrawal and crop yield of a dry sandy soil 

Kathlin Schweitzer, Michael Baumecker, David-Paul Klein, Vera Porwollik, and Oliver Schmittmann

Compaction of the subsoil on intensively used arable land is one of the main causes of restricted vertical root growth. As a result, nutrient and water resources from the subsoil can only be used by the plant to a very limited extent. Particularly during temporary drought, the drying out of the topsoil and the associated reduction in nutrient availability, is no longer possible to compensate by using the water and nutrient reserves from the subsoil.

Subsoil loosening is increasingly discussed as a suitable method to increase crop yields in drought-prone areas. In the “Soil^3”project funded by the Federal Ministry of Education and Research of Germany, a field trial with winter rye and silage maize has been carried out on a dry highly compacted sandy soil in Thyrow (Germany) since 2019. The soil of the experimental site is classified as a Retisol, the climate is humid continental.

Five treatments are tested in the trial, where mechanical subsoiling using the Soil^3 method (Schmittmann et al., 2021) in 45 cm deep furrows with a spacing of 1 m (FU), in furrows with incorporation of organic compost (FU+CO) or with incorporation of straw (FU+ST) is compared with subsoiling with Paraplow to a depth of 50 cm (PP) and with reduced tillage to a depth of 15 cm (RT) as a control treatment. The effects of subsoiling on physical soil properties, penetration resistance and soil moisture profile as well as on root growth (vertical distribution of root length density down to a depth of 90 cm) and crop yield are being investigated.

The results of the first four years of the trial have shown that soil loosening with Soil^3 technology improved the physical soil properties within the furrows, with the water holding capacity of the soil only being increased in the furrows with incorporated organic matter. Root growth was limited to the first 20 cm of soil depth in the control treatment and in the area between the furrows. In the furrows, root length increased uniformly up to a depth of 50 – 60 cm. Total root length and rooting depth was highest in furrows with compost. The incorporation of straw can inhibit root growth. The cultivation with the Paraplow also led to an even vertical root distribution up to a depth of 50 cm, but not to a greater total root length.

The net water removal from the furrows in treatments with Soil^3 technology, but also from the areas between the furrows, was up to 50 % higher than in the control treatment. However, significant furrow effects were observed in winter rye during prolonged drought, with emergency ripening occurring in the areas between furrows.

On average over the first four years of the field trial, subsoiling achieved a maximum yield increase of 0.8+0.1 t ha-1 DM ha for winter rye in the "PP" treatment and 2.3 +1.4 t ha-1 DM ha for silage maize in the "FU" treatment of the Soil^3 technology. Thus, loosening in furrows appears to be particularly effective for row crops.

How to cite: Schweitzer, K., Baumecker, M., Klein, D.-P., Porwollik, V., and Schmittmann, O.: Effect of different methods of subsoil loosening on the physical soil properties, root growth, soil water withdrawal and crop yield of a dry sandy soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21749, https://doi.org/10.5194/egusphere-egu24-21749, 2024.

EGU24-22049 | Posters on site | BG3.13

Rapid alteration of organic matter cycling in a boreal peatland in response to rising temperatures 

Guido L.B. Wiesenberg, Nicholas Ofiti, Arnaud Huguet, Paul J. Hanson, and Michael W.I. Schmidt

Global warming and increasing air temperatures also result in rising soil temperatures. Although acceleration of soil organic carbon cycling can be expected, the order of magnitude and speed of adaptation of carbon cycling to warming still remains largely unknown. This is especially crucial in boreal peatlands, where large reserves of terrestrial carbon are stored and these systems are known for their vulnerability to environmental changes.

We investigated the organic matter composition in the SPRUCE (Spruce and Peatland Responses Under Changing Environments) experiment, where a boreal peatland was exposed to temperatures of up to +9°C and increased CO2 concentration compared to control conditions in open top chambers. A broad set of molecular markers (e.g., free extractable and bound lipids, lignin, benzene polycarboxylic acids) was used to trace incorporation and cycling of organic matter in the peat profile down to three meters depth four years after the start of the experiment.

A strong response to increasing temperature was observed in the plant, microbial and peat chemical composition, the latter mainly in the acrotelm (0-30 cm) and partially also in the mesotelm (30-70cm). The response of the plant chemical composition was species-specific with the exception of nitrogen concentrations that increased for all plants. This is related to the stronger degradation of peat organic matter and thus increasing availability of nitrogen with rising temperature. All investigated molecular markers indicated a very fast response of carbon cycling in the whole acrotelm of the peat profile. This resulted from a dropping water table and thus more oxic conditions in the peat, which further enabled increasing shrub and tree root growth and increasing microbial abundance and activity. As a consequence of the more aerobic conditions, not only the comparatively easily degradable free extractable lipids, but also slow cycling polymeric substances such as suberin/cutin, lignin, and benzene polycarboxylic acids rapidly degraded and reflect an unexpectedly fast cycling of organic matter in the boreal peatland with increasing temperature. The acceleration of carbon cycling within the peatland with rising temperature is also reflected by the partial uptake of respired CO2 by the plants as indicated by the bulk and compound-specific d13C composition of the plants. Overall, our results illustrate the fast alteration of organic matter cycling in a boreal peatland when exposed to increasing temperature.

How to cite: Wiesenberg, G. L. B., Ofiti, N., Huguet, A., Hanson, P. J., and Schmidt, M. W. I.: Rapid alteration of organic matter cycling in a boreal peatland in response to rising temperatures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22049, https://doi.org/10.5194/egusphere-egu24-22049, 2024.

EGU24-22056 | ECS | Posters on site | BG3.13

The use of cover crops in climate change scenarios 

Derlis Enciso Santacruz, Raúl de Pablo Gonzalez, Jorge D. García, Mariela Navas, Chiquinquirá Hontoria, Ana Moliner, Fernando Peregrina, and Ignacio Mariscal-Sancho

Cover crops (CC) are emerging as key tools in agrosystems, providing essential ecosystem services for climate change adaptation and mitigation. The great diversity of possible cover crops and climate scenarios makes it necessary to investigate how combinations of these two factors (cover crop type and climate scenario) affect agrosystems.

The experiment was carried out with mesocosms with soil of a Typic Calcixerept, inside a growth chamber with continuous control and programming of temperature, humidity, luminosity and ventilation. The climatic scenarios studied correspond to an average temperature increase of +3 oC and three levels of rainfall or water availability of: +10%, -5% and -20% with respect to the records of the reference area in the center of the Iberian Peninsula in the period 1950-2015.

In this work, the effect of five CC was evaluated: i.e. 1) without CC. 2) With CC composed by a Brassica (Camelina sativa L.). 3) with CC composed of a grass (Hordeum vulgare L.). 4) with CC composed of a legume (Vicia sativa L.) and 5) with CC composed of a mixture of the three species mentioned above. After the simulation from October 15 to January 1, the total population of Fungi (ITS), Archaea (16SA), Bacteria (16SB), electrical conductivity, macro and micro nutrients in the rhizospheric soil were evaluated. In addition, the biomass production and their macro and micronutrient concentrations were quantified.

The results obtained were modulated by water availability and microbial activity in the soil. In this sense, an increase in the population of ITS and 16SB was observed as the available water increased, especially at the +10% level. These results allow us to establish that the increase in moisture favored microbial activity in the study conditions, which is related to greater mineralization of organic matter. The CC composed of grasses and +10% rainfall stood out with a greater contribution of plant biomass, revealing the importance of soil moisture and the presence of grasses to increase the contribution of organic matter to the soil. On the contrary, the lower water availability (-20%) and the soil without cover produced an increase in electrical conductivity with respect to other treatments, and adversely affected numerous variables.

Among the cover crops, the legume and the mixture proved to be less affected by changes in the amount of available water. In addition, the mixture exhibited a mechanism that enabled it to achieve the highest Mg concentration in the plant. Possibly because the acquisition traits of the different species showed some complementarity.

For future research, the study of these CC will be carried out under other climatic scenarios, in order to elaborate a digital twin of each CC that will provide a more accurate information on their effects on the agrosystem according to the expected temperatures and water availability. This could help to choose the best cover crop for each scenario and objective.

How to cite: Enciso Santacruz, D., de Pablo Gonzalez, R., García, J. D., Navas, M., Hontoria, C., Moliner, A., Peregrina, F., and Mariscal-Sancho, I.: The use of cover crops in climate change scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22056, https://doi.org/10.5194/egusphere-egu24-22056, 2024.

SSS9 – Soils, Forestry and Agriculture

EGU24-835 | ECS | Orals | SSS9.5

Differential Tillage Practices in Agronomy Influence Soil Carbon Content, Nutrient Availability and Microbial Community Dynamics: Field to Genomics 

Arnab Majumdar, Munish Kumar Upadhyay, Biswajit Giri, Ashish Kumar Srivastava, and Tarit Roychowdhury

Globally, there is a dilemma in using tillage practice1 and here we establish that using tillage is beneficial for maintaining soil quality. Consecutive four seasonal rotations (two wintery and two monsoonal in two years) during rice cultivation in India have compared a tilled field (TF) to a non-tilled field (NTF). The novelty of our study lies in the combination of the alternate wetting-drying (AWD) cycle in this tillage/no-tillage practice2. Before the field trial started, we conducted a survey of literature and farmers to set the optimal degree of tillage, 5 cm from the top in this case. The analyzed parameters are soil pH, redox potential, conductivity, total soil organic carbon (SOC), labile carbon (LC) content, and microbial biomass (MB), followed by a thorough assessment of nutrients3,4 like total nitrogen (N), phosphorus (P), potassium (K), iron (Fe), calcium (Ca), magnesium (Mg), copper (Cu), zinc (Zn). Further, we used metagenomics and high throughput sequencing to define the total microbial community change5 during tillage and non-tillage practices. Using genomics, we found that genes responsible for nutrient modulation in soil were actively expressed under tilled soil in many of these microbial species. Clear differences in SOC and LC content, microbial biomass and nutrient bioavailability were found6 in TF and NTF by 9.87%, 13.69% and 14.25% respectively when AWD was applied (Figure 1). Nutrients were higher in TF due to the ‘Birch effect’, which enriched the soil and induced the microbial genus Nitrospira, Bacillus, Pseudomonas, Azospira, and Bradyrhizobium. These genera contribute significantly to nutrient modulation and availability. Gene ontology, KEGG Pathway and Panther Pathway analyses showed a higher gene expression and greater metabolic activities were maintained in TF-AWD microbes (Figure 2) resulting in better soil quality under tillage practice proving the benefit of surface tillage practice.

1Mondal, S., et al., 2020. Land Degradation & Development, 31(5), pp.557-567. 2Majumdar, A., et al., 2020. Arsenic in Drinking Water and Food, pp.425-443. 3Wang, H., et al., 2020. Archives of Agronomy and Soil Science, 66(11), pp.1509-1519. 4Majumdar et al., 2023. Soil and Tillage Research, 232, p.105752 5Majumdar, A., et al., 2021. Journal of Hazardous Materials, 409, p.124443. 6Liu, X., et al., 2022. Soil and Tillage Research, 215, p.105188.

Figure 1. 

Figure 2.

 

How to cite: Majumdar, A., Upadhyay, M. K., Giri, B., Srivastava, A. K., and Roychowdhury, T.: Differential Tillage Practices in Agronomy Influence Soil Carbon Content, Nutrient Availability and Microbial Community Dynamics: Field to Genomics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-835, https://doi.org/10.5194/egusphere-egu24-835, 2024.

EGU24-1467 | ECS | Orals | SSS9.5

Perennial grain cultivation promotes functional nematode diversity in soil 

Alena Förster, Karin Hohberg, and Christoph Emmerling

Perennial cropping systems are known to highly support soil fauna and its diversity. This has already been investigated for grassland and bioenergy systems. Recently, perennial wheat (Kernza®) is increasingly recognised throughout European agriculture. However, the detailed impacts of perennial grain on soil functioning are not well investigated yet.

Within the EU-Biodiversa project NAPERDIV nematode communities, among other research areas, were investigated in a Pan-European transect from South France to Belgium to South Sweden representing a climatic gradient from south to north and variations in soil conditions. Additionally, two soil depths (5-15 cm; 25-35 cm) were investigated.

In total, nematodes from 31 families were identified, with the perennial cropping system having a greater number of taxa and biomass. Additionally, this cropping system was characterised with system stability and food web complexity due to greater proportions of predators and  omnivores and a higher maturity index, channel index and structure index as compared to annual wheat. In contrast, the enrichment index was highest in the annual cropping system, representing nutrient enrichment and rapid responses of opportunistic nematodes. Nematode diversity was greater for the upper soil depth.

In summary, nematode communities mainly reflect the impact of land-use, tillage, fertilisation, and soil organic matter on their feeding behaviour. The promotion in diversity for the perennial cropping system for all study sites shows that differences in soil and climate conditions do not interfere with the beneficial effects of perennnial wheat.

How to cite: Förster, A., Hohberg, K., and Emmerling, C.: Perennial grain cultivation promotes functional nematode diversity in soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1467, https://doi.org/10.5194/egusphere-egu24-1467, 2024.

EGU24-6070 | ECS | Orals | SSS9.5

Reconciling climate change mitigation, biodiversity conservation and rice production through changes in water management strategies 

Sebastián Echeverría-Progulakis, Maite Martínez-Eixarch, and Néstor Pérez-Méndez

Tackling climate change while enhancing biodiversity without compromising production is a main goal in agricultural policy. In rice farming, water-saving irrigation techniques alternative to permanent flooding are necessary to face water scarcity and have proven effective in reducing greenhouse gas (GHG) emissions, yet potential trade-offs with biodiversity conservation are often overlooked. Here we used a field-scale experiment to compare the effects of water management strategies representing a water use gradient on i) GHG emissions, ii) the diversity of aquatic macroinvertebrate and vertebrate (fish and amphibians) communities, and iii) crop productivity. Reduced methane emissions were observed in rice fields with lowest water use when compared to fields permanently flooded, yet the effect on aquatic biodiversity and crop yield was the opposite. Through this holistic assessment approach, we were able to identify an intermediate rice water-saving irrigation strategy that conciliates climate change mitigation, biodiversity conservation and crop production in rice agrosystems.

How to cite: Echeverría-Progulakis, S., Martínez-Eixarch, M., and Pérez-Méndez, N.: Reconciling climate change mitigation, biodiversity conservation and rice production through changes in water management strategies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6070, https://doi.org/10.5194/egusphere-egu24-6070, 2024.

EGU24-6722 | ECS | Posters virtual | SSS9.5

Functional and genotypic diversity of pea (Pisum sativum L.) microsymbionts in several geographical sites in Tunisia: Selection of inoculant strains for biofertilizer formulation 

Amira Hachana, Imen Hemissi, Amir Souissi, Anissa Riahi, Neila Abdi, Manel Bouraoui, Hanen Arfaoui, Imen Ouzari Cherif, Raoudha Ferjani, and Bouaziz Sifi

Pea (Pisum sativum L.) is a leguminous plant that is cultivated for its nutritional value and advantageous effects on soil fertility when used as a preceding crop. Its symbiotic nitrogen fixation and phosphorus solubilization properties thanks to the association with rhizospheric bacteria make it crucial component in cereal-based cropping systems. In Tunisia, the upscaling of pea cultivation faces numerous challenges, including low yields attributed to soil fertility depletion and the low abundance or ineffectiveness of specific rhizobia for achieving optimal pea nodulation.

The current study aims to assess the diversity and plant growth promoting traits of pea endophytic bacteria in order to select effective inoculant strains. For this purpose, 166 bacterial strains were isolated from root nodules of pea plants, collected from 46 regions in Tunisia. The strains were subjected to thorough in vitro assays, involving morphological, functional, and genetic characterization.

The results demonstrated that 153 strains were tested Gram-negative and 13 strains Gram-positive. Among the Gram-negative isolates, 44 strains induced nodule formation on pea plants of the 'Lincoln' variety, but mostly produced low nodule number and biomass and poor plant growth. The assessment of phosphorus solubilization among the whole isolates collection revealed a highly significant difference in the halo diameter formed on Pikovskaya medium and the phosphorus solubilization index. One hundred thirteen isolates were capable of solubilizing inorganic phosphorus.

The analysis of functional diversity of pea microsymbionts showed that Rhizobium strains (Oued Bj0.16, BjD, KalAM, MzBrg, Jbn, Morg15, Jed3, Sbit1, and Sb4), that were originated respectively from Beja, Kalaat Andalous, Menzel Bourguiba, Jbeniana, Morneg, Jedaida, Sbitla, and Sbiba sites, presented the highest efficiency in regards of nitrogen fixation. Furthermore, the strain Oued Bj0.16 demonstrated a moderate ability to solubilize phosphorus whereas the strain SoliL stands as the most efficient phosphorus-solubilizing bacteria (PSB). Concerning non-nodulating bacteria, BsM, Mat3L, MzelTM, and Mok4 were identified as a highly efficient PSB. In addition, the Gram-positive strain TebkL, originated from Beja, was identified as the most efficient P-solubilizer. The 16S gene sequencing revealed that pea nodular microsymbionts were attributed to 6 different genera: Rhizobium sp., Rhizobium leguminosarum, Parabulkolderia fungorum, Pantoea sp., Pseudomonas fluorescens, Pseudomonas baetica, Bacillus subtilis, Paenibacillus polymyxa, and Rhizobium nepotum. The exploration of pea microsymbionts diversity demonstrated extensive functional and genetic variations associated with the isolates origin.

In a nutshell, the application of single or mix of these beneficial bacteria as inoculant is an eco-friendly option that provides nitrogen and phosphorus to the crops and gets rid of chemical fertilizer, thereby promoting plant growth and preserving the environment in a Mediterranean context.

How to cite: Hachana, A., Hemissi, I., Souissi, A., Riahi, A., Abdi, N., Bouraoui, M., Arfaoui, H., Ouzari Cherif, I., Ferjani, R., and Sifi, B.: Functional and genotypic diversity of pea (Pisum sativum L.) microsymbionts in several geographical sites in Tunisia: Selection of inoculant strains for biofertilizer formulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6722, https://doi.org/10.5194/egusphere-egu24-6722, 2024.

EGU24-8996 | Posters on site | SSS9.5

Diversifying maize rotation with industrial crops can improve maize yield, soil nutrient stocks, and nitrate leaching losses depending on time since adoption and crop species 

Mingming Zong, Kiril Manevski, Zhi Liang, Diego Abalos, Mohamed Jabloun, Poul Erik Lærke, and Uffe Jørgensen

Maize (Zea mays L.) is a major crop worldwide, commonly used as monoculture and with high nitrate leaching losses. Diversified maize rotations can improve the environmental problems of maize monoculture without reducing yields and soil nutrients. Previous research focused on maize-legume or maize-cereal rotations, with limited exploration of rotations with industrial crops for biorefining. Furthermore, long-term field trials are rare, hindering our understanding of the crop performance and nutrient dynamics over time. In a four-year rotation system of maize, hemp (Cannabis sativa L.), beet (Beta vulgaris L.), and triticale (Triticosecale) established in 2012 on a sandy soil in Denmark, quadruplicated for maize to appear each year, we examined dry matter yield, yield stability, biomass nitrogen (N) and biomass N stability of maize in rotation compared to monoculture across two rotation cycles. We also quantified nitrate leaching, soil carbon (C) and N stocks in the root zone of 0-100 cm. Moreover, the period between the main crops was covered with “secondary crops”- winter rye (Secale cereale L.), winter rape (Brassica napus L.), grass/clover (Festuca rubra L. – Trifolium repens L.). The results showed that in the initial four years, the aboveground biomass yield of maize in rotation (15.5 Mg ha-1) was significantly lower (by 7%) than that in monoculture (16.6 Mg ha-1), but this difference disappeared in the following four years (17 and 16.5 Mg ha-1). The maize biomass N yield in rotation (194.5 kg ha-1) was similar to that in monoculture (196.6 kg ha-1) in the first cycle and was significantly higher (by 8%) in the second cycle (195.5 and 165.7 kg ha-1). Nitrate leaching showed interannual variability affected by double-cropping, being almost halved by the diverse rotation compared to the monoculture at the start of the rotation, but increasing at the onset of the second cycle when the preceding winter rape did not survive in the winter. Also, winter rye following maize reduced nitrate leaching, except when the preceding secondary crop was grass-clover or poorly thriving winter rape. During the whole period, the rotation system can increase both soil C and N stocks. This study shows that several of the benefits of diverse crop rotations in comparison to monoculture require several years to take place, and that the management of the secondary crops is particularly vital for reducing nitrateleaching.

How to cite: Zong, M., Manevski, K., Liang, Z., Abalos, D., Jabloun, M., Lærke, P. E., and Jørgensen, U.: Diversifying maize rotation with industrial crops can improve maize yield, soil nutrient stocks, and nitrate leaching losses depending on time since adoption and crop species, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8996, https://doi.org/10.5194/egusphere-egu24-8996, 2024.

EGU24-11889 | ECS | Posters on site | SSS9.5

Weed management strategies with Picea abies L. sawmill by-products 

Valeria Xotta, Giacomo Trespidi, Nebojša Nikolić, Stefan Otto, Roberta Masin, and Donato Loddo

Weeds can cause significant impact on agriculture and require effective management; however, traditional control measures can lead to serious environmental damage. Considering both the need and demand for more sustainable use of pesticides in Europe, regenerative bio solutions are gaining much attention, especially the possibilities for by-product usage. Here, such a possibility was examined using sawdust and bark from Picea abies L., the most common conifer in the Alpine region forestry, known for generating large quantities of these by-products in sawmills.

The tests comprised the assessment in Petri dishes of phytotoxic effects on germination and root growth of two weeds Abutilon theophrasti Medik. (ABUTH), Lolium rigidum Gaudin (LOLRI) and two crops Triticum aestivum L. (wheat) and Sinapis alba L. (mustard) treated with P. abies bark and sawdust aqueous extracts at different concentrations (from 0 to 100% v/v). Another test was carried out in pots to evaluate the effects of these by-products as mulches and phytotoxicity by incorporation in the first 10 cm of soil. For this trial, Amaranthus retroflexus L. (AMARE) and Glycine max L. (soybean) were added to the species used in the Petri test.

The by-product incorporation test showed no germination reduction but increased AMARE germination by 9%. This corresponds to the Petri tests where no effect on germination was observed. Regarding root elongation, sawdust extract shows no relevant effects except for 35.3 % reduction in mustard root growth at the 100 % v/v concentration. Bark extracts were more effective, particularly at the highest extract concentration (100 % v/v), reaching root growth reduction from 41.8 to 69 % for all species. The most susceptible species was LOLRI with root growth reduction by 44.5 and 69 % at concentrations of 40 and 100 % v/v, respectively.

Conversely, bark and sawdust mulching effectively reduced germination in species with smaller seeds (-51% in AMARE and mustard, -27% in LOLRI), while having little or no effect on the others. In addition, mulching delayed emergence of all species by no more than one day compared to untreated. LOLRI and ABUTH showed the most significant germination slowdown with an average of 35% at the higher mulching dose of 2.25 kg/m2.

As an innovative solution, the use of sawmill by-products as mulch seems to be the most viable strategy for sustainable weed control and increasing its use is desirable considering the environmental benefits. Results suggest that the mulching effect is purely physical, while releasing allelopathic compounds from by-products does not affect the species germination. The development of natural herbicides from waste bark and sawdust has not yielded satisfactory results, but the presence of phytotoxic compounds, especially in bark extracts, is suspected. Chemical analyses may be carried out to assess their presence.

How to cite: Xotta, V., Trespidi, G., Nikolić, N., Otto, S., Masin, R., and Loddo, D.: Weed management strategies with Picea abies L. sawmill by-products, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11889, https://doi.org/10.5194/egusphere-egu24-11889, 2024.

EGU24-16731 | Posters on site | SSS9.5

Conventional vs. organic soil management practices in German apple orchards: Correlation between bitter pit disease incidence and nutrient status 

Magdalena Sut-Lohmann, Mark Grimm, Thomas Raab, and Martina Heinrich

Apple orchard soils in Germany face numerous challenges, including pest and disease control and soil nutrient management, leading to the potential accumulation of potentially toxic elements (PTEs). Producing high-quality fruit requires effective management of these challenges, which is additionally intensified by the impact of changing climate and associated weather patterns. One example is bitter pit (BP) disease, a significant disorder in apple orchards that results in substantial economic loss when symptoms manifest in the fruit.

This study aimed to assess macronutrient ratios in German apple orchards and explore the relationship between BP disease incidence and variations in fruit composition across orchards with diverse locations and management practices. Soil and composite plant samples (apples, leaves, and branches) were collected from 16 apple orchard sites (a total of 32 sample sites) in the Eastern region of Germany, encompassing both conventional and organic farming systems (CFS and OFS). MP-AES was used for total macronutrients and trace element plant and soil analysis, and relevant physiochemical soil properties, such as pH, EC, OM, and carbonate content (%) or texture, were examined. Data were evaluated using bioaccumulation (BAF) and translocation (TF) factors, Pearson correlation coefficient, and principal component analysis (PCA).

The study revealed that fruits with an elevated Mg+K/Ca ratio were more affected by BP incidence. Based on PCA, a correlation between orchard location (region), management practices (CFS and OFS), and BP occurrence was observed. We conclude that macronutrient ratios, especially the Mg+K/Ca ratio, play a crucial role in BP disease development in apple orchards, and orchard location and management practices influence these ratios. Knowledge regarding these correlations can support the development of strategies for preventing and managing BP disease, leading to enhanced apple orchard productivity and reduced economic losses.

 

How to cite: Sut-Lohmann, M., Grimm, M., Raab, T., and Heinrich, M.: Conventional vs. organic soil management practices in German apple orchards: Correlation between bitter pit disease incidence and nutrient status, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16731, https://doi.org/10.5194/egusphere-egu24-16731, 2024.

A third of the world’s arable land has been lost since the 1950’s largely attributed to the rise of industrialised conventional agriculture, since its practices severely deplete the soil of essential organic matter, nutrients, and crop diversity, increasing its vulnerability to disease, drought, and flooding. Therefore, there is a pressing need to develop regenerative methods of cultivation to enrich soil fertility. Permaculture is a form of agroecology adopting holistic management to create a set of principles and design frameworks enriching soil based on a whole ecosystem approach. To date, there is little scientific evidence on the influence permaculture management has on soil fertility and subsequently microbial abundance and diversity. This study investigates the effect of permaculture management on soil fertility by comparing two mature permaculture managed allotment soils with a conventional arable soil. Soil fertility was assessed by microbial biomass and diversity (measured by phospholipid fatty acid analysis), soil nutrient (nitrate, ammonium and phosphate) and soil organic carbon contents. The greenhouse gas emission potential of soils was also measured with an in vitro incubation and gas chromatography analysis. Both bacterial and fungal abundance were 3-4 times higher under permaculture managed soils (with the more mature site showing higher fungal abundance) compared to conventionally managed soils. Furthermore, the bacterial/fungal ratio significantly varied between sites, with the arable soil showing a much lower abundance of fungi compared to its bacterial biomass. The greater soil microbial abundance and diversity under permaculture management was attributed to the use of organic amendments, crop rotation and diversity and no till practices promoting symbiotic relationships between the soil microbes and crop, exchanging essential nutrients and minerals. Consequently, permaculture soils had significantly higher organic matter, organic carbon, and nutrient contents as well as soil moisture compared to the arable soil. Regarding greenhouse gas emissions, the permaculture soils had 2-3 times higher soil respiration rate measured as carbon dioxide, which was explained by a multiple linear regression combination of soil nitrogen, organic carbon and moisture (77.34 % variance explained). Nitrous oxide (N2O) and methane (CH4) emissions were not statistically different between soil types due to high variability between replicates. However, N2O from permaculture soils was marginally higher representing soil conditions at the time of sampling (October), which did not include fertilisation effects of the arable soil. This study found permaculture management of soils leads to increased fertility compared to conventionally managed arable soil, as expressed by the soils’ higher microbial abundance, nutrient, and organic carbon contents. The management of permaculture focused on mimicking the natural recycling of an ecosystem with addition of organic amendments, little disturbance to the soil using no dig raised beds, and crop diversity and rotation to aid microbial activity and synergy with the plant, creating a dense network of hyphae within the soil that contributes to enriched carbon and nutrient content.

How to cite: Williamson, R., Reay, M., and Sgouridis, F.: Permaculture management of arable soil increases soil microbial abundance and diversity, nutrient and carbon stocks compared to conventional arable agriculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19083, https://doi.org/10.5194/egusphere-egu24-19083, 2024.

EGU24-19619 | ECS | Orals | SSS9.5

Integrating Morphological and Molecular Approaches for Assessing Soil Biodiversity in Agroecosystems 

Luísa F. Dornellas, Vanessa A. Mata, Marie Bartz, Ricardo Leitão, Eduardo Nascimento, Sara Mendes, Joana Costa, José Paulo Sousa, and Luís Cunha

The One Health paradigm, emphasizing the interdependence of human, animal, and environmental health, demands a comprehensive approach for ecosystem monitoring. This study underscores the vulnerability of Mediterranean ecosystems to desertification and climate change, emphasizing the critical role of soil biodiversity in agroecosystems. Interdisciplinary collaboration is imperative to mitigate these challenges and foster a resilient balance between human, animal, and environmental well-being in the region. In this context, monitoring soil biodiversity, an essential component in ecosystem functioning, remains relatively understudied compared to above-ground organisms, posing conservation and management challenges. Depending on the land management practices, agroecosystems can pose a significant impact on various aspects of the environment, including soil biodiversity, food security, and the provision of essential ecosystem services. Molecular methods (e.g. barcoding, metabarcoding) offer promising results in assessing soil biodiversity more efficiently. This study addresses the problem of thoroughly evaluating soil macrofauna diversity in agroecosystems with differing management intensities; morphotaxonomy and metabarcoding methods were used to explore their validation and integration. In this study, we morphologically identified 9418 individuals, representing 13 taxonomic groups; metabarcoding identified more than 800 OTUs (Operational taxonomic Units) , belonging to seven different classes. Significantly higher levels of biodiversity were recorded in the traditional agroecosystems, while improved pastures had the lowest. Moreover, metabarcoding results showed that all sites differ significantly from each other regarding OTU communities, with a separation into two clusters: one encompassing extensively managed agroforests and another with intensive, hyperintense, and improved pastures agroecosystems. This study underscores the importance of an integrative approach that combines morphotaxonomy and molecular methods to improve species identification accuracy, shedding light on the potential of molecular techniques such as metabarcoding to provide fast and precise species identification. However, further refinement of molecular methods is still required, and collaboration between researchers and taxonomists is essential. The data gathered here might help define efficient management practices according to the different land-use types, to promote a sustainable balance between biodiversity and productivity. By adopting an integrative and interdisciplinary approach, we can better understand and conserve soil biodiversity in agroecosystems, ultimately contributing to a more sustainable and secure world.

How to cite: F. Dornellas, L., Mata, V. A., Bartz, M., Leitão, R., Nascimento, E., Mendes, S., Costa, J., Sousa, J. P., and Cunha, L.: Integrating Morphological and Molecular Approaches for Assessing Soil Biodiversity in Agroecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19619, https://doi.org/10.5194/egusphere-egu24-19619, 2024.

EGU24-20475 | ECS | Posters on site | SSS9.5

Biochar application on a rainfed barley crop under a climate change scenario does not improve grain yield and quality 

Iria Benavente-Ferraces, María José Carpio Espinosa, Verónica Perciun, Marco Panettieri, Juan Carlos García-Gil, and César Plaza

Climate change effects on agriculture is already a major threat for global crop production in terms of yields and quality of grains. In particular, sustainability of rainfed agriculture in semiarid regions is severely affected by warming and prolonged drought periods. Exploring new soil amendments such as biochar, which holds in countering climate change effects may be a sustainable method aimed at storing carbon, increasing soil quality and buffering the warming and drought stresses on soil and crops. However, we still need to better understand the effects of biochar application on crop yields, particularly under climate change conditions.

To fill this knowledge gap, in a long-term field experiment, we investigated how cumulative biochar addition (20 t ha-1 year-1) under climate change conditions affected a barley crop. Rainout shelters and open-top chambers were set up to simulate a 30% rainfall reduction combined with an increase of 2°C in soil temperature. Unamended soils for both ambient conditions and climate change manipulation were used as a control. Our findings revealed that the barley yield was greatly impacted by climate manipulation reducing the grain yield by 74-81%. However, the application of biochar did not lead to improvements in crop yield under these altered conditions. Moreover, grain quality parameters (specific grain weight and weight of 1000 grains) were not enhanced by the application of biochar nor the simulated climate change conditions.

Acknowledgments: this work was supported by the research projects TED2021-132342B-I00 (Spanish MICINN) and TUdi (Horizon 2020, GA 101000224).

How to cite: Benavente-Ferraces, I., Carpio Espinosa, M. J., Perciun, V., Panettieri, M., García-Gil, J. C., and Plaza, C.: Biochar application on a rainfed barley crop under a climate change scenario does not improve grain yield and quality, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20475, https://doi.org/10.5194/egusphere-egu24-20475, 2024.

EGU24-20791 | ECS | Posters virtual | SSS9.5

Conservation Agriculture to increase water productivity of durum wheat under semi-arid Mediterranean conditions 

Amir Souissi, Haithem Bahri, Hatem Cheikh M’hamed, Salah Benyoussef, and Mohamed Annabi

Tunisia is facing twin challenges, namely, food and water security, which are pressing now and likely to increase in the future mainly due to climate change. To face this alarming situation, the implementation of conservation agriculture (CA) remains crucial for facing interannual variability in climatic conditions that impact durum wheat production. The current study aims to assess the effect of tillage systems on grain yield (YLD), above-ground biomass (AGB), and crop water productivity. The experiment was conducted at the Bourabia experimental station of the National Institute of Agricultural Research of Tunisia, located in a semi-arid zone of Tunisia, during cropping seasons (2013-2014 and 2014-2015). At harvest, above-ground biomass, yield, and yield components of durum wheat (Maali cultivar) were determined. Tillage practices included no-tillage (CA) and conventional tillage (CV). Preceding crops were either common vetch or bread wheat. The N rates applied were: 0, 75, 100, 120, and 140 kg N ha−1. The experiments were laid out in a ‘Split-Plot’ design with three replications. The results show that the relationship between water productivity (quantity of water used to produce a ton of grain) and grain yield illustrated a better water valorization in CA system. For yields lower than 2 t ha-1, more water was needed in AC than in CV to produce the same amount of grain; Whereas for yields greater than 2 t ha-1, the opposite was revealed. On the other hand, grain yield and above-ground biomass were higher under CA compared to CV (+806 and +2468 kg ha−1 for YLD and AGB respectively) in the dry growing season (year2), while in the favorable growing season (year1), the opposite was observed (-315 and -604 kg ha−1 for YLD and AGB respectively). This feature illustrates the positive effect of CA in low-rainfall growing season due to good soil infiltration and reduction of evapotranspiration. Therefore, these findings provide evidence of the positive impact of CA on rainfed durum wheat under semi-arid Mediterranean conditions.

How to cite: Souissi, A., Bahri, H., Cheikh M’hamed, H., Benyoussef, S., and Annabi, M.: Conservation Agriculture to increase water productivity of durum wheat under semi-arid Mediterranean conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20791, https://doi.org/10.5194/egusphere-egu24-20791, 2024.

EGU24-21407 | Posters on site | SSS9.5 | Highlight

Relationships between the structure and activity of microbial communities in legume-cereal intercropping - new possibilities of old plant cultivation methods 

Magdalena Frąc, Dominika Siegieda, Agata Gryta, Jacek Panek, Michał Pylak, Mateusz Mącik, Giorgia Pertile, Karolina Oszust, Priyal Sisodia, Beata Feledyn-Szewczyk, Shamina Pathan, and Giacomo Pietramellara

Intercropping has been known for a long time, but despite its many agronomic benefits, it still constitutes a small niche in agricultural cropping systems. It is known that this type of cropping systems improves biodiversity through several synergistic effects between plant species cultivated together. Legume-cereal intercropping, may also contribute to reducing expenditure on mineral fertilization, due to legume symbiosis with microbes that fix atmospheric nitrogen.

The assumption of this study is that intercropping creates more complex and lasting systems and interactions in the soil-plant-microbiome system. Therefore, they stimulate various part of communities, contributing to a more diverse community, which drives the processes of environmental changes resulting from various root exudates. Moreover, they also increase the co-occurrence of various bacteria and fungi, thus ensuring greater stability, health and quality of agroecosystems.

The research was carried out based on a large-scale field experiment conducted at the Experimental Station in Osiny (Lubelskie Voivodeship, Poland, N: 51°28, E: 22°4) established in 1994, the aim of which was a comparison of different agricultural production systems: organic, integrated and conventional high-input. The general design of the field experiment has been described by Feledyn-Szewczyk et al. (2019).

The aim of this study was to determine differences in the structure and activity of the microbiome of wheat and the soil under its cultivation in an organic, integrated and conventional cultivation systems of this plant, taking into account the complexity of plant communities occurring simultaneously in the field during the growing season. The organic system included intercropping of wheat with clovers and grasses, integrated wheat and clover, and conventional wheat cultivation with pure sowing. The research methods included spectrophotometric approach for enzymatic activity and EcoPlates functional diversity evaluation and next-generation sequencing was used for microbial structure determination of various ecological niches (soil, rhizosphere, roots and shoots).

The results may constitute an important link for a new vision of agriculture, including the use of a close connection between the soil-plant- microbiome for the development of sustainable crop production strategies and management practices for future resilient crop cultivations.

This work was supported in the frame of Horizon Europe Programme, agreement no. Project 101082289 — LEGUMINOSE

Feledyn-Szewczyk B., Matyka M., Staniak M., 2019, Comparison of the Effect of Perennial Energy Crops and Agricultural Crops on Weed Flora Diversity. Agronomy 2019, 9, 695; doi:10.3390/agronomy9110695

How to cite: Frąc, M., Siegieda, D., Gryta, A., Panek, J., Pylak, M., Mącik, M., Pertile, G., Oszust, K., Sisodia, P., Feledyn-Szewczyk, B., Pathan, S., and Pietramellara, G.: Relationships between the structure and activity of microbial communities in legume-cereal intercropping - new possibilities of old plant cultivation methods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21407, https://doi.org/10.5194/egusphere-egu24-21407, 2024.

EGU24-3923 | ECS | Posters on site | SSS9.10

Long term response and adaptation of farmland water, carbon and nitrogen balances to climate change in arid to semi-arid regions 

Yue Li, Michael Herbst, Zhijun Chen, Xinguo Chen, Xu Xu, Yunwu Xiong, Quanzhong Huang, and Guanhua Huang

Climate change poses a challenge for resource utilization and environmental pollution issues caused by agricultural production, especially in arid to semi-arid regions. Farmland water, carbon and nitrogen (WCN) balances are closely related to these resource and environmental issues. Thus, the Agro-Hydrological & chemical and Crop systems simulator (AHC) was used to assess the response of WCN balances to climate change in a spring wheat farmland of arid Northwest China and to propose adaptation strategies. Five Global Climate Models from the Coupled Model Intercomparison Project 6 and two Shared Socioeconomic Pathways (SSP1-2.6 and SSP5-8.5) were used to establish scenarios with the AHC model to simulate farmland WCN balances for the 2025–2100 period. Various irrigation amounts and nitrogen fertilization rates were tested as compensation strategies. Results indicated that precipitation showed an increasing trend, thus percolation increased and soil water consumption decreased from 2025 to 2100. However, for the carbon budget, although the soil CO2 emissions tend to decrease, the net primary production (NPP) was also significantly reduced, which resulted in declining the net ecosystem carbon budget (NECB) under future climatic conditions. In addition, higher temperature and increased precipitation enhanced soil inorganic nitrogen leaching and N2O emissions but reduced NH3 volatilization from 2025 to 2100. Overall, the soil total nitrogen loss was increased over time, whereas crop nitrogen uptake (CNU) was significantly reduced. In relation to the SSP1-2.6 scenario, the SSP5-8.5 scenario accelerated the increase rates of soil water percolation and total nitrogen loss over time, as well as the decrease rates of CNU and NPP over time. The negative effects caused by climate change can be mitigated by reducing irrigation and increasing nitrogen fertilization. For the SSP1-2.6 scenario, 30% irrigation reduction and 30% nitrogen fertilization increase can effectively decrease soil water percolation and the related nitrogen losses while CNU, NPP and NECB increase in relation to the current management (240 mm irrigation and 200 kg ha–1 nitrogen fertilization). For SSP5-8.5 the strategy with 45% irrigation reduction and 45% nitrogen fertilization increase can also decrease nitrogen losses and increase CNU, NPP and NECB.

How to cite: Li, Y., Herbst, M., Chen, Z., Chen, X., Xu, X., Xiong, Y., Huang, Q., and Huang, G.: Long term response and adaptation of farmland water, carbon and nitrogen balances to climate change in arid to semi-arid regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3923, https://doi.org/10.5194/egusphere-egu24-3923, 2024.

EGU24-6040 | Posters on site | SSS9.10

The contribution of W-band radar monitoring for understanding of runoff and soil erosion response at field scale 

Marcella Biddoccu, Giorgio Capello, Alexander Myagkov, Tatiana Nomokonova, Gerrit Maschwitz, Davide Canone, and Stefano Ferraris

Vegetation cover has a great influence on hydrological response at field scale, and, consequently, on runoff and soil erosion processes. The maintenance of bare soil in vineyard inter-rows with tillage, as well as the tractor traffic, are known to expose the soil to compaction, reduction of soil water holding capacity and increase of runoff and erosion. The use of grass cover is one of the most common and effective practices in order to reduce such threats.

Rain-driven runoff (RO) and soil loss (SL) at sites with different cover have been investigated over last decades. It has been found that RO and SL often correlate with rain properties. This correlation, however, is highly variable among different sites and also for different time periods. In many studies rain is represented only by a few parameters such as e.g. maximum intensity and total precipitation. Size of rain drops is rarely analysed, although it is important for an accurate estimation of kinetic energy of rain. Polarimetric millimetre-wavelength radars are one of the instruments capable of drop size measurements. In contrast to in-situ rain sensors, such radars have much larger sampling area and can estimate range profiles of drop size distributions with high spatial and temporal resolution.

The objective of this work is to relate runoff and soil erosion to rain properties based on traditional monitoring techniques complemented by observations from a radar. With this aim, a site in the Alto Monferrato vine-growing area (Piedmont, NW Italy) was equipped with a 94-GHz radar in June 2023. The site has two vineyard-field-scale plots with inter-rows managed with conventional tillage (CT) and grass cover (GC), respectively. The radar is located about 100 m from the plots. The radar elevation was set to 30° so that the radar samples rain above the plots.

During the summer and autumn seasons of 2023, 26 rain and 13 runoff events were observed. The preliminary results of the conventional analysis show that in this period runoff is directly related to erosivity index (EI30) both in CT and GC plots, and, only in GC treatment to maximum rainfall intensity over 10 minutes and antecedent rainfall in previous 7 days. Maximum rainfall intensity over 30 and 60 minutes, on the contrary, has a negative direct proportion with runoff. Soil erosion for both treatments was also directly related also with maximum rainfall intensity over 10 minutes and antecedent rainfall in previous 7 days and, in addition has a negative proportion with rainfall energy. It should be noted the relevant role played by rainfall intensity over short time interval and the antecedent rainfall, resulting in increased soil moisture. Relationships are different from those obtained in the same site in a previous study, reflecting the peculiarity of summer 2023, characterized by few rainfall events occurred on very dry soil. Information obtained from W-Band radar monitoring allows to investigate relationships in a deeper way among rainfall characteristics and generation of runoff and soil erosion.

How to cite: Biddoccu, M., Capello, G., Myagkov, A., Nomokonova, T., Maschwitz, G., Canone, D., and Ferraris, S.: The contribution of W-band radar monitoring for understanding of runoff and soil erosion response at field scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6040, https://doi.org/10.5194/egusphere-egu24-6040, 2024.

EGU24-10140 | ECS | Posters on site | SSS9.10

BODIUM4Farmers: A tool to assess the impact of management measures on soil functions 

Judith Rüschhoff, Ulrich Weller, Sara König, Leonard Franke, Julius Diel, Ute Wollschläger, and Hans-Jörg Vogel

The BODIUM model (König et al., 2023) is a systemic soil model which aims to simulate the effect of changing agricultural management practices on soil functions such as yield, water storage and filtration, nutrient recycling, carbon storage and habitat for biodiversity. For this purpose, the influence of crop rotation, soil cultivation, fertilisation as well as the effect of a changing climate is taken into account site-specifically.

A version of this model, the BODIUM4Farmers, is intended to serve farmers as an on-site decision support tool for long-term planning of soil management measures in response to actual economic and ecological requirements. The model considers site- and farm-specific conditions and requires a number of input variables: a description of the soil profile, weather and management data.
In cooperation with farmers and agricultural advisors, we are currently developing an optimised interface that allows farmers to use the tool as efficiently as possible. Co-design workshops with users from agricultural practice have provided important impulses on technical realization such as database connectivity and graphical user interface design. Furthermore, we discussed potential future management options to be implemented for users in the tool and how to present results in an easy-to-understand manner.
With this contribution, we introduce BODIUM4Farmers, present the current state of development and encourage discussions and feedback from scientists experienced in science-to-practice transfer.

König, S., U. Weller, B. Betancur-Corredor, B. Lang, T. Reitz, M. Wiesmeier, U. Wollschläger, and H.-J. Vogel (2023): BODIUM – a systemic approach to model the dynamics of soil functions. Europ. J. Soil Sci., doi:10.1111/ejss.13411

How to cite: Rüschhoff, J., Weller, U., König, S., Franke, L., Diel, J., Wollschläger, U., and Vogel, H.-J.: BODIUM4Farmers: A tool to assess the impact of management measures on soil functions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10140, https://doi.org/10.5194/egusphere-egu24-10140, 2024.

EGU24-14225 | ECS | Posters on site | SSS9.10

Can in-field NIR spectroscopy provide an option for soil carbon monitoring? 

Jessica Underwood, Aidan Keith, Alister Leggatt, and Christopher Collins

Current soil sampling methods are expensive, time consuming and destructive. These constraints result in a standard practice that combines samples from a W transect across a field, into one composite sample for laboratory analysis. This presents a challenge for farmers, policy makers and industry, as this method of sampling doesn’t give the required detail about the variability of soil properties across the field. The heterogenous nature of soil means that differences between monitoring results across years could be due to changes in sample location, and the natural variability of the soil. This is of particular concern for farmers and policy makers monitoring soil carbon under the transition to sustainable farming methods, as they want to be sure that the change they see is due to management changes, not inherent variability.

Simple, handheld, near-infrared (NIR) spectroscopy devices can be used in the field by practitioners. They are cheap, quick and non destructive. This allows for more samples to be taken across a field, and GPS allows repeat sampling of the same location over time. This paper looks at how accurate in-field soil spectroscopy performs compared to laboratory results, how variable soil properties are across a field, and how different sampling methods (W transect, random sampling) capture that variability.

How to cite: Underwood, J., Keith, A., Leggatt, A., and Collins, C.: Can in-field NIR spectroscopy provide an option for soil carbon monitoring?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14225, https://doi.org/10.5194/egusphere-egu24-14225, 2024.

EGU24-17919 | ECS | Posters on site | SSS9.10

Assessing the effect of conventional and conservation tillage methods on soil moisture under drought progression 

Adane Irkiso, Abel Chemura, Michael Kuhwald, and Annegret Thieken

Tillage is an agricultural practice that aims to create a favorable environment for crop production. Nonetheless, the intense field traffic by tillage, in the worst-case, is considered a detrimental anthropogenic practice to the soil. By impeding soil water movement, tillage might exacerbate the impact of droughts. To limit drought impacts, adapting tillage practices is one management option.

In this study, we aimed to evaluate the effect of tillage practices on soil moisture. For this purpose, we deployed 28 point-based plant care soil moisture sensors at 20 and 40 cm soil depths, in a farm field in Lower Saxony, Germany on silt loam divided into three different sections based on tillage type with different tillage depths (moldboard – 30 cm, chisel plow – 25 cm and disk harrow – 10 cm) implemented consistently for more than twenty years. The effect of tillage types on soil moisture was analyzed for different crop development phases of sugar beet and drought severity levels in 2022. For the latter, the soil water deficit index was used, which is computed based on soil moisture content at field capacity and permanent wilting point. Additionally, we ran DSSAT model simulations to evaluate the potential of nature-based solutions, such as no tillage and mulching, on maximizing soil moisture conservation during drought period.

Our result showed a temporal variability in soil moisture content between the three different mechanical tillage depending on the drought severity level. Moreover, our DSSAT simulation indicated that mulching tends to improve soil moisture content and to reduce runoff and soil evaporation.

How to cite: Irkiso, A., Chemura, A., Kuhwald, M., and Thieken, A.: Assessing the effect of conventional and conservation tillage methods on soil moisture under drought progression, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17919, https://doi.org/10.5194/egusphere-egu24-17919, 2024.

EGU24-18763 | ECS | Posters on site | SSS9.10

Optimizing of alternative water resources reutilization on extreme sandy soil 

Gift Nxumalo, Nikolett Éva Kiss, Zsolt Zoltán Fehér, Tamás Magyar, Erika Budayné Bódi, Andrea Szabó, Dávid Pásztor, János Tamás, and Attila Nagy

All agricultural areas in the European Union, as one of the largest water-using sectors, are under increased threat from the growing frequency of extreme water-holding events due to climate change. These focus on alternative water resource management, spectral data integration and soil moisture modelling. Furthermore, the irrigated area in Hungary covers 2% of agricultural land, mostly with outdated irrigation technology. This research will evaluate farm-level water resource management and irrigation technology developments and research results based on the results of the Hungarian test area.

The study area was conducted on a 85 ha maize field on sandy soil, located in a nitrate-sensitive area (based on European guidelines) and owned by the private company. The case study site situated at the alluvial cone plain is covered mainly with quicksand which is not optimal for maize production from a water management point of view. Irrigation is implemented by a GPS controlled, VRI technology controlled, reversible linear irrigation system with zone and nozzle irrigation control. However there is limited available water resources at the site, therefore alternative water sources utilization system was set up for irrigation to adapt to climate change and reduce fertilizers. The basis of the alternative water resources are excess water, treated wastewater, biogas fermentation sludge which is collected in a water reservoir with 114000 m3 capacity.

In this research the role of these alternative water resources were evaluated in the hydrological system and in the water cycle. A wide variety of remote sensing platforms were used in this research, as satellites, drones, and laboratory instruments. These remote sensing (pigment and plant phenology) data formed the basis of time series studies. The results can contribute to a spatially and temporally optimal stress monitoring of plants and their water supply at the same time. Beside better irrigation management due to the used irrigation techniques as up to 30-50% of the required water can be replaced by using alternative water resources.

This research was financed by project no. TKP2021-NKTA-32, which has been implemented with the support provided from the National Research, Development and Innovation Fund of Hungary, financed under the TKP2021-NKTA funding scheme. This research was supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences.

 

How to cite: Nxumalo, G., Kiss, N. É., Fehér, Z. Z., Magyar, T., Bódi, E. B., Szabó, A., Pásztor, D., Tamás, J., and Nagy, A.: Optimizing of alternative water resources reutilization on extreme sandy soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18763, https://doi.org/10.5194/egusphere-egu24-18763, 2024.

EGU24-998 | ECS | Orals | SSS9.11

Investigation of SOM sequestration and storage in the Southern Transdanubian region of Hungary 

Péter Végh, Pál Balázs, András Bidló, and Adrienn Horváth

Site factors determine the occurrence and growth of forest stands. The climate is one of the most important. In Hungary, several forest stands located near to the Xeric limit, where climate change is more sensitive. Therefore carbon-rich forests and their soils are being prioritized to achieve carbon neutrality as soon as possible. Our research aims to assess and compare the organic carbon stored in oak and beech forest ecosystems of different climate classes.

In the last period, we sampled 2 Beech, 11 Sessile oak and 13 Turkey oak forest stands to determine the amount of soil organic carbon stored in the soil.

The soils were collected by soil boring to 0-110 cm. Besides the soil sampling, the existing forest stand composition assessed on each stand near to sampling points.

Based on the analyses carried out in the 26 selected forest stands, the soils of the sites can be classified as Cambisols and Luvisols (WRB 2023). The soil pH showed slightly acidic to neutral (mean H2O = 6.7), and the texture can be determined as loam. The relative organic matter content (SOM) was 0.67% on average between 0-110 cm. It corresponds to ~8.2 t of carbon per hectare.

With the accelerated rate of climate change (drought), there is an increasing urgency to assess the status of ideal organic matter-rich soils and to develop adaptation strategies to increase the carbon stock.

This article was made in the frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme. This publication was supported by the project GINOP-2.3.3-15-2016-00039.

How to cite: Végh, P., Balázs, P., Bidló, A., and Horváth, A.: Investigation of SOM sequestration and storage in the Southern Transdanubian region of Hungary, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-998, https://doi.org/10.5194/egusphere-egu24-998, 2024.

Different climate scenarios predict a clear rise in temperatures and a modest increase in precipitation to high latitudes. In forested peatlands, the consequent lowering of the water table and increasing peat temperature will enhance organic matter decomposition leading to higher nutrient release and CO2 emissions from the peat. These biogechemical changes will fundamentally alter the management schemes of peatland forests. Hydrological and biogeochemical processes in forested peatlands are complicated, interlinked and characterized by different feedback mechanisms. In addition, all these are dependent on weather conditions, peat characteristics, drainage dimensions, and stand structure.  High-resolution geospatial data combined with process-based ecosystem models provides a solution in searching for new forest management schemes that balance between different ecosystem services. We have developed this kind of ecosystem model, peatland simulator SUSI, and applied it to study how manipulation of drain network, ash fertilization and forest management affect tree growth, greenhouse gas balance and nutrient export to water courses under different temperature and rainfall scenarios. We found that without a change in the water management, the stand growth, the soil C emissions and nitrogen export to water courses will increase substantially. However, less intensive drainage together with ash fertilization helped to mitigate the harmful effects of changing climate whilst keeping the stand growth in adequate level. 

How to cite: Laurén, A. and Palviainen, M.: Decreasing carbon emissions in boreal peatland forests using fertilization and less intensive drainage in current and changing climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3103, https://doi.org/10.5194/egusphere-egu24-3103, 2024.

EGU24-3172 | Posters on site | SSS9.11

Is it more conservative to use the crab steering during sugar beet harvesting? A case study from Lower Saxony, Germany 

Katja Augustin, Marco Lorenz, Rainer Duttmann, and Michael Kuhwald

Sugar beet is one of the crops grown in Germany with the highest intensity of traffic on the field. Not only are there very high numbers of passes by the machines during the season, but the sugar beet harvesting vehicles are also among the largest and heaviest machines in use in Germany. The heavy harvesters are also used elsewhere in the world. In order to avoid multiple passes with the heavy wheel loads, the machines can often offset their rear axles parallel to the direction of travel - the so-called crab steering (CS). This distributes the load over a larger area, but also means that more area is covered in the field.

This study examines whether the distribution of wheel loads over a larger area using CS shows a significant difference in soil settlement and deformation compared to traffic without the use of crab steering (wCS). Different moisture contents of the soil are taken into account.

The model named FiTraM was used to model the traffic. The calculation of the soil deformation is based on empirical formulas, which are specially adapted to this field and the harvester.

The subsoil in particular is considered, as soil deformation should be avoided there, since it is difficult and cost-intensive to repair.

The results show that there are no significant differences in the distribution of soil deformation between CS and wCS.  In general, the moisture content of the soil determines the extent of deformation. In moist to very wet conditions (approx. 35 - 37 Vol-%), the first pass already achieves such a high degree of soil deformation that it should be avoided in practice. When the soil is dry (approx. 25-30% by volume), no soil deformation occurs in the subsoil in any of the variants - only slight deformation occurs in the topsoil. There are likewise no significant differences between the two traffic variants between 31 and 34 Vol.-% soil moisture.

In summary, it can be assumed that a wheel or axle of the beet harvester is already so heavy that it makes little difference whether the machine is running in CS or not. The limiting factors are the total weight and the soil moisture content during traffic.

How to cite: Augustin, K., Lorenz, M., Duttmann, R., and Kuhwald, M.: Is it more conservative to use the crab steering during sugar beet harvesting? A case study from Lower Saxony, Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3172, https://doi.org/10.5194/egusphere-egu24-3172, 2024.

EGU24-3244 | Posters on site | SSS9.11

Wetland restoration for the future - ALFAwetlands 

Liisa Ukonmaanaho, Tuula Larmola, Tuula Aalto, Erik Andersson, Kaido Soosaar, Alexandra Barthelmes, Marina Abramchuk, Juraj Balkovic, Emmi Haltia, Iryna Shchoka, Maud Raman, Kris Decleer, Andis Lazdins, Josep Penuelas, Adria Descals, Jose Miguel Sanchez-Perez, Odette Gonzalez, Julien Tournbize, and Francesc de Paula Sabater Comas

The global goal to mitigate climate change (CC) is to achieve net zero greenhouse gas emissions (GHGE) by 2050; the European Union (EU) aim is to cut GHGE at least by 55% already by 2030. These ambition targets require new GHGE mitigation measures across all land use sectors (LULUCF), where wetlands, as carbon (C) rich ecosystem, can effectively contribute to climate targets, biodiversity, and water-related ecosystem services. Natural peatlands accumulate C effectively due to water-logged conditions. However, they can turn into high GHG sources if they are drained, therefore there is still need to enhance knowledge regarding how and/or how much C is sequestered or released by peatlands after their restoration, as well as the socioeconomic effects.

“ALFAwetlands - Restoration for the future” (www.alfawetlands.eu) is a Horizon Europe funded project (2022-2026), which is coordinated by Luke and carried out at local to EU levels with 15 partners across Europe. It’s main goal, in short, is to mitigate CC while supporting biodiversity and ecosystem services (BES) and being socially just and rewarding. This includes, e.g., increasing the knowledge about C storage and release in peatlands, specifically after restoration. While, in terms of C fluxes, focussing on peatlands, the project scope is larger and includes additionally floodplains, coastal wetlands and few artificial wetlands. ALFAwetlands will develop and indicate management alternatives for wetlands including such that have been or will be restored during this project. Measures under this project are not restricted to ecological restoration but include rehabilitation and re-vegetation action to improve ecosystem conditions (e.g., peatland forest: continuous-cover-forestry, cultivated peatlands: paludiculture). Studies are conducted in 9 Living Labs (LL’s) including 30 sites, which are located in wetlands in different parts of Europe (north-south gradient). At the local level, LL’s support and integrate interdisciplinary and multi-actor research on ecological, environmental, economic, and social issues. Experimental data from local sites are scaled-up and will be utilized e.g., by models to gain and understanding the potential impacts of upscaled wetland restoration measures. To achieve ALFAwetlands goals, 5 research workpackages are being implemented, namely: 1)improve geospatial knowledge base of wetlands, 2)co-create socially fair and rewarding pathways for wetland restoration, 3)estimate effects of restoration on GHGE and BES, with the data achieved from field experiments, 4)develop policy relevant scenarios for CC and BES, and 5)study societal impacts of wetland restoration. The project will also encourage stakeholders to utilise outputs and support their active participation in wetland management.

How to cite: Ukonmaanaho, L., Larmola, T., Aalto, T., Andersson, E., Soosaar, K., Barthelmes, A., Abramchuk, M., Balkovic, J., Haltia, E., Shchoka, I., Raman, M., Decleer, K., Lazdins, A., Penuelas, J., Descals, A., Sanchez-Perez, J. M., Gonzalez, O., Tournbize, J., and Sabater Comas, F. D. P.: Wetland restoration for the future - ALFAwetlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3244, https://doi.org/10.5194/egusphere-egu24-3244, 2024.

EGU24-3514 | Posters on site | SSS9.11

Physical characteristics of peat and their influence on peat CO2 emission potential in a drained boreal peatland forest 

Salla Tenhovirta, Marjo Palviainen, Elina Peltomaa, and Annamari Laurén

Peatlands are a significant global storage of carbon (C), but also major sources of nutrients and dissolved organic carbon (DOC) to surface waters. Export of DOC from peatlands to watercourses cause emissions of  carbon dioxide (CO2) due to degradation of DOC, as well as enhances the brownification of surface waters, altering the ecological networks of the aquatic ecosystems. Managed peatland forests are hotspots for DOC export into downstream water bodies due to forestry practices such as harvesting and drainage. Water table, soil oxygen availability and vegetation control the release and transport of DOC.

Drainage of peatlands also alters the physical characteristics of peat (Word et al., 2022). However, the role of these peat characteristics in the processes and release of DOC, as well as their influence on the lateral fluxes of carbon from forested peatlands, remains unknown.

In this contribution, we present results from a laboratory experiment where the physical properties of peat and their relationship to peat decomposition are studied in a minerotrophic, nutrient-rich peatland forest that has been drained for ~80 years. The peat for the study was collected from the field site, located in southern Finland, into 50 cm columns along three transects. The transects  extend from 1 to 30 meter distance from the  ditch. In laboratory, the bulk density and water retention characteristics of the peat will first be determined in relation to distance to the ditch. The CO2 emission potential is then defined as the function of these peat properties. This is done by measuring the CO2 fluxes of the peat with a chamber enclosure method, using a Li-7810 online CH4-CO2-H2O analyser.

The results of this experiment will increase the process-level understanding of the mechanisms that drive the export of DOC from peatlands. The produced data will be further utilized in an ecosystem model, to be used in assessing and evaluating environmental impacts of forest management practises.

 

References

Word CS, McLaughlin DL, Strahm BD, Stewart RD, Varner JM, Wurster FC, Amestoy TJ, Link NT. 2022. Peatland drainage alters soil structure and water retention properties: Implications for ecosystem function and management. Hydrological Processes 36: e14533.

How to cite: Tenhovirta, S., Palviainen, M., Peltomaa, E., and Laurén, A.: Physical characteristics of peat and their influence on peat CO2 emission potential in a drained boreal peatland forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3514, https://doi.org/10.5194/egusphere-egu24-3514, 2024.

EGU24-3804 | Posters on site | SSS9.11

Reforestation based on the ditch-and-embankment technique increased soil carbon stock and alleviated soil salinity in a coastal area subject to land subsidence- a preliminary study 

Chun-Yu Lee, Guan-Ying Lin, Yu-Hsuan Liu, Hsiang-Wua Wang, Chien-Fan Chen, and Li-Wan Chang

The coastal areas are renowned for their exposure to strong winds, salt sprays, and blowing aeolian sands, collectively posing threats to farming and the health of residents. Well-established coastal forests offer protection to alleviate these adverse effects and provide various ecosystem functions, such as carbon sequestration and soil conservation. Soils account for approximately 74% of the carbon stock in terrestrial ecosystems. Consequently, even a subtle increase in soil carbon can lead to significant carbon sequestration. Reforestation is considered a suitable practice to enhance both above- and belowground carbon sequestration. However, the benefits of reforestation in coastal areas are hindered by land subsidence and seawater intrusion due to over-exploitation of groundwater for fish farming or manufacturing. To overcome these obstacles, a reforestation practice known as the "ditch-and-embankment technique (D-E technique)" is adopted. This technique involves reforesting coastal lands suffering from land subsidence by constructing inter-parallel ditches and hills. By applying the D-E technique, soil properties can be improved through salt leaching, and soil organic carbon (SOC) stock can be enriched by organic matter inputs from reforested trees. However, the effectiveness of this technique in terms of soil carbon and soil amelioration lacks sufficient evidence. In this study, we investigated the soil carbon stock and soil salinity of a 15-year-old coastal plantation, consisting of four dominant species (Casuarina equisetifolia, Millettia pinnata, Melaleuca leucadendra, Cerbera manghas) established by the D-E technique on the western coast of Taiwan. Soil samples from hills (O horizon and mineral soil) and ditches were collected using soil cores and a piston sampler. A proximate submerged forest was used as a reference baseline. Soil carbon was determined as organic, inorganic, and elemental carbon with a TOC analyzer. Soil salinity was measured in terms of soil pH and electrical conductance (EC1:5). Our results showed that the D-E technique could increase the total SOC stock (O horizon + 0-50 cm mineral SOC) to an average of 48.38 Mg C ha-1, compared to the submerged forest (12.22 Mg C ha-1). The total SOC stocks of hills ranged from 38.02-60.33 Mg C ha-1, significantly higher than the submerged forest, irrespective of species, although there were no significant differences in total SOC stocks between species. Consistent with total SOC stocks, mineral SOC stocks of hills (13.91 -24.49 Mg C ha-1) were generally higher than the submerged forest, with only those from Cerbera manghas and Millettia pinnata being significantly or marginally higher. The similar amount of total inorganic carbon stock between hills and the submerged forest further supported the contribution of reforestation. Soil pH at the 0-5 cm layer of hills was lower than in the deeper soil layer and soils from the ditch. Additionally, EC generally were lower at soil at 0-5 cm or 5-10 cm layers, suggesting the occurrence of salt leaching. In conclusion, our preliminary study suggests that the D-E technique could be an appropriate reforestation approach to establish coastal plantations in areas subject to land subsidence, meeting multiple objectives, including protecting residents' well-being, soil carbon sequestration, and soil salinity amelioration.

How to cite: Lee, C.-Y., Lin, G.-Y., Liu, Y.-H., Wang, H.-W., Chen, C.-F., and Chang, L.-W.: Reforestation based on the ditch-and-embankment technique increased soil carbon stock and alleviated soil salinity in a coastal area subject to land subsidence- a preliminary study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3804, https://doi.org/10.5194/egusphere-egu24-3804, 2024.

Aim: Anthropogenic compaction is typically assumed to be major threat to soil health in agriculture. Compaction of the subsoil is considered irreversible and therefore more severe than topsoil compaction. To-date, quantitative estimates about the extent and severity of soil compaction are hardly available. This study aims to quantify anthropogenic subsoil compaction in German croplands by reanalyzing data from the German Agricultural Soil Inventory (BZE-LW). Grassland sites, which are assumed to exhibit negligible traffic-induced compaction below 30 cm depth, serve as a reference for the prediction of bulk density in cropland sites before anthropogenic compaction.


Methods: A data-driven reciprocal modelling approach is employed to estimate human-induced increases in bulk density at 1477 cropland sites scattered in a regular 8 x 8 km grid across Germany. The model is trained on data from ~400 grassland sites using information about soil texture, organic C content, soil pH, climate, and geological parent material. The model is then applied to the cropland sites to predict the bulk density of the upper subsoil in 30-50 cm depth prior to anthropogenic compaction. The disparity between modelled and observed bulk density represents the trafficking induced changes in soil compactness. To explain the drivers of this change, another data-driven model, incorporating soil and climate information as well as cropland management data, is trained and interpreted.


Results: Traffic-induced compaction has significantly increased the median bulk density of subsoils under cropland by 0.055 g cm⁻³, corresponding to a 4% increase. The modelled effects ranges from -0.07 g cm-3 to 0.180 g cm⁻³ (10th and 90th quantile), with the largest increases in subsoil compaction observed in eastern Germany. For the 20% most severely affected sites in Germany, the median increase in bulk density was 0.180 g cm⁻³ (0.142 g cm⁻³ – 0.267 g cm⁻³, 10th and 90th quantile), which corresponds to a 12% increase in subsoil bulk density. The anthropogenic increase in soil bulk density was most pronounced in loamy soils with relatively low soil organic carbon content.


Conclusion: This study represents a significant advancement in our ability to quantitatively assess the extent and severity of anthropogenic subsoil compaction at a national scale. The data-driven reciprocal modelling approach employed is promising for broad application in relation to soil health monitoring initiatives across Europe. 

How to cite: Harbo, L. S. and Schneider, F.: Estimating anthropogenic subsoil compaction in Germany using data-driven reciprocal modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5503, https://doi.org/10.5194/egusphere-egu24-5503, 2024.

EGU24-6522 | Orals | SSS9.11

On the impact of timber harvesting on soil water retention and surface runoff 

Max Behringer, Christian Scheidl, Gerhard Markart, Gertraud Meißl, Marcus Froemel, Lisa Gasser, Julian Grünberg, Christoph Haas, Armin Hofbauer, Barbara Kitzler, Martin Kühmaier, Nikolaus Nemestothy, Boris Rewald, Alexandra Wieshaider, and Klaus Katzensteiner

Structural properties of undisturbed soils are critical for water retention and the reduction of peak flows after heavy rainfall events. Forest soils commonly show high infiltration rates that can be attributed to a high organic content and the formation of larger pores through biological activity. Though soil disturbances, especially soil compaction, due to timber logging can be considered a rare event, the impacts may be long lasting. The productive, often fine textured soils of the Alpine Flysch belt are particularly susceptible to compaction, posing a challenge for timber harvesting.

In a controlled experiment in the Flysch zone (Vienna Woods, Austria), we assessed the effects of different timber harvesting technologies – specifically harvester-forwarder (with or without bogie tracks) and chain saw-cable yarder – on soil functions. For the quantification of the surface runoff, we applied rainfall simulation experiments on seven plots of 50 m² each. All rainfall simulation experiments were conducted for one hour with a targeted intensity of 100 mm/h before and after harvesting. Within each irrigation plot, we sampled undisturbed soil cores at up to five depth levels (5, 15, 25, 40, 65 cm) for further analyses in the laboratory. We measured saturated hydraulic conductivity (KSAT device; METER Group, Munich, Germany), as well as soil water retention in the wet and medium soil moisture range using the HYPROP device (METER Group, Munich, Germany). In the dry soil moisture range (pF>4.2) we measured water retention with the dew point method using the WP4C device (METER Group, Pullman, USA). Additionally, soil texture and soil organic carbon were determined from the same soil samples.

Preliminary results suggest a strong impact of the harvester-forwarder system (w/wo bogie tracks) on all hydrologically effective soil properties, while the cable yarder system seems to have lower, yet still noticeable impacts. For the log10 of the saturated hydraulic conductivity (log10KS) the harvester-forwarder treatments cause significantly lower values, with reductions of up to >99% compared to values prior to harvesting. The decline of log10KS in cable yarding systems is only marginally significant (up to -49%). First order analyses of runoff coefficients show a strong effect of the harvester-forwarder system with observed values of up to 0.66. Undisturbed sites had no surface runoff and cable yarding only generated minimal surface runoff. 

How to cite: Behringer, M., Scheidl, C., Markart, G., Meißl, G., Froemel, M., Gasser, L., Grünberg, J., Haas, C., Hofbauer, A., Kitzler, B., Kühmaier, M., Nemestothy, N., Rewald, B., Wieshaider, A., and Katzensteiner, K.: On the impact of timber harvesting on soil water retention and surface runoff, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6522, https://doi.org/10.5194/egusphere-egu24-6522, 2024.

EGU24-6553 | Orals | SSS9.11

Could continuous cover forestry on drained peatlands increase the carbon sink of Finnish forests?  

Aleksi Lehtonen, Kyle Eyvindson, Kari Härkönen, Kersti Leppä, Aura Salmivaara, Mikko Peltoniemi, Olli Salminen, Sakari Sarkkola, Samuli Launiainen, Paavo Ojanen, Minna Räty, and Raisa Mäkipää

Land-based mitigation measures are needed to achieve climate targets. One option is mitigation of currently high greenhouse gas (GHG) emissions of nutrient-rich drained peatland forest soils. Continuous cover forestry (CCF) has been proposed as a measure to manage this GHG emission source; however, its emission reduction potential and impact on timber production at regional and national scale have not been analysed.

To quantify the potential emission reduction, we simulated four management scenarios for Finnish forests: (i) clearcutting of nutrient-rich drained peatlands replaced by selection harvesting (CCF) and (ii) the current prevailing forest management regime (BAU), and both at two harvest levels, namely (i) the mean annual harvesting (2016–2018) and (ii) the maximum sustainable yield. The simulations were conducted with a forest simulator (MELA) coupled with hydrological model (SpaFHy), soil C model (Yasso07) and empirical GHG exchange models.

Simulations showed that the management scenario (CCF) that avoided clear-cutting on nutrient-rich drained peatlands produced approximately 1 Tg CO2 eq. higher carbon sinks annually compared to the BAU at equal harvest level for Finland. This emission reduction can be attributed to the maintenance of higher biomass sink and to the mitigation of soil emissions from nutrient-rich drained peatland sites.

How to cite: Lehtonen, A., Eyvindson, K., Härkönen, K., Leppä, K., Salmivaara, A., Peltoniemi, M., Salminen, O., Sarkkola, S., Launiainen, S., Ojanen, P., Räty, M., and Mäkipää, R.: Could continuous cover forestry on drained peatlands increase the carbon sink of Finnish forests? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6553, https://doi.org/10.5194/egusphere-egu24-6553, 2024.

EGU24-8055 | ECS | Orals | SSS9.11

Soil compaction signatures on electromagnetic and DC-current geophysics 

Alberto Carrera, Luca Peruzzo, Giorgio Cassiani, and Francesco Morari

Monitoring soil structure is of paramount importance due to its key role in the critical zone as the foundation of terrestrial life. Variations in the arrangement of soil components significantly influence its hydro-mechanical properties, and therefore its impact on the surrounding ecosystem. Soil compaction, resulting from inappropriate agricultural practices, not only affects soil ecological functions by reducing soil porosity and water infiltration, but also decreases the yields spoiling the socio-economic aspect.

In this study, we compared the ability of electrical and electromagnetic geophysical methods, i.e. Electrical Resistivity Tomography and Frequency-domain Electromagnetic Method, to monitor the effects of compaction on agricultural soil. The objective is to highlight the electro-magnetic response caused by plastic deformation of the soil generated by both a super-heavy vehicle and the usual interrows surface compaction generated by tractor traffic for common practices. The survey was conducted both on a small scale, covering an area of 1.5 hectares, and in detail on individual targeted transects. This allowed to capture the 2-D and 3-D spatial heterogeneity that is often difficult to obtain with punctual and invasive traditional methods.

This work aims to contribute to the methodological optimization of agro-geophysical acquisitions and data processing, so as to obtain accurate soil models through non-invasive approach. Results, validated with traditional soil characterization techniques (i.e. penetration resistance, bulk density and volumetric water content on collected samples), show pros & cons of both techniques and how differences in their spatial resolution heavily influence the ability to characterize compacted areas with good confidence.

How to cite: Carrera, A., Peruzzo, L., Cassiani, G., and Morari, F.: Soil compaction signatures on electromagnetic and DC-current geophysics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8055, https://doi.org/10.5194/egusphere-egu24-8055, 2024.

EGU24-8649 | ECS,ECS | Orals | SSS9.11

Unearthing the effects of harvesting methods applied in continuous-cover forestry and rotation forest management on soil carbon storage 

Eva-Maria Roth, Kristiina Karhu, Matti Koivula, Heljä-Sisko Helmisaari, and Eeva-Stiina Tuittila

Boreal forests hold about 32% of the global forest carbon (C) stock and the majority of this C is stored in the soil. Forest management affects species composition, microclimate, plant growth, and litter production, and thus affects the soil organic carbon (SOC) storage. Hence, it is important to understand the effects of forest management practices on SOC storage and to adopt management strategies that protect SOC storage.

We aimed to assess how two major forest management approaches differ in their impact on SOC quality and degradability to evaluate their effects on long-term SOC storage. Rotation forest management (RFM) based on clear-cut harvesting is the most common forest management practice worldwide. Continuous-cover forestry (CCF) as an integrated forest management approach has been suggested to enhance SOC storage. It uses repeated partial harvesting and retains a continuous tree cover.

We present our recently published results from a field study in Ruunaa, Lieksa, eastern Finland. We compared the effects of logging methods applied in CCF and RFM on SOC storage and quality in boreal Scots pine (Pinus sylvestris) dominated forests ten years after the logging operations. We sampled gap-cuts as logging method applied in CCF, retention-cuts (20% of tree volume retained), and uncut mature forests and clear-cuts as two opposing stages of RFM. We tested the hypotheses: (1) colder microclimate and continuous litter input lead to higher SOC stocks in CCF plots than in clear-cuts and (2) more labile litter of grass- and herb-rich vegetation typical for clear-cut sites enhances SOC decomposition rates. We analyzed the SOC concentration and stock and modelled annual above- and belowground litter inputs based on stand characteristics (diameter at breast height, basal area, dominant tree height, understory species coverage). We used sequential chemical fractionation of organic layer samples and laboratory incubation to analyze the quality of SOC and its degradability under standardized conditions. To estimate the decomposition rate as impacted by the environment we incubated cellulose bags in situ. We assessed the impact of varying microclimate with field measurements of soil temperature and soil moisture. We analyzed the microbial biomass C pool with chloroform fumigation extraction.

The SOC content and stock did not differ significantly between the treatments, despite the warmer microclimate and lower litter input recorded in clear-cut plots than in CCF plots. However, we detected differences in quality and degradability of SOC. Soils in clear-cut sites held lower proportions of labile SOC compounds than the other treatments. As hypothesized, decomposition rate was elevated in clear-cuts, but was equally high within the canopy gaps of gap-cuts. Accumulation of labile SOC due to cooler microclimate, combined with decreased decomposition rate – both found in uncut forests and retention-cuts – indicate a higher potential for future SOC accumulation in these treatments than in clear-cuts. Our study highlights that forest management affects the quality, degradability, long-term accumulation and storage of SOC. Thus, the chosen logging method can be an important tool in climate change mitigation and the forest management regime needs to be adapted accordingly.

 

Publication in Forest Ecology and Management [2023]: https://doi.org/10.1016/j.foreco.2023.121144

How to cite: Roth, E.-M., Karhu, K., Koivula, M., Helmisaari, H.-S., and Tuittila, E.-S.: Unearthing the effects of harvesting methods applied in continuous-cover forestry and rotation forest management on soil carbon storage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8649, https://doi.org/10.5194/egusphere-egu24-8649, 2024.

EGU24-9353 | ECS | Orals | SSS9.11

Restricted root growth caused by traffic induced soil compaction – a field study in wheat and maize 

Elron Wiedermann, Laura Reinelt, Lennart Rolfes, and Axel Don

Soil compaction has adverse impacts on key soil functions and can result in restricted root distribution. However, deep roots provide access to water and nutrient reservoirs and might enhance carbon (C) storage in subsoils. Deep rooting is thus a central element for climate-adapted plant productivity and has potential for climate mitigation. Clarity is missing, to what extent different soil traffic intensities impact root depth distribution and root-derived C inputs at field scale.

The present study was conducted to assess the impact of differing soil traffic intensities (i) on soil physical parameters related to compaction, and (ii) to what extent this affects root length density and depth distribution, as well as (iii) above ground biomass and (iV) SOC-stocks. Negative effects of increasing traffic intensities on soil physical parameters are expected to result in reduced root depth distribution and therefore reduced biomass productivity and root-induced carbon allocation.

Soil and plant biomass were sampled along increasing soil traffic intensities at three field sites in central Germany characterized as Luvisols. Penetration resistance was measured in the field, and undisturbed soil rings of top and sub soils were analyzed for bulk density and air capacity. Undisturbed soil cores were taken up to one meter depth during peak root biomass. Root biomass, depth distribution and root length density were evaluated with the core-break method using an automated root spectroscopy imaging system. Based on the results, root-derived C inputs were estimated and C/N-measurement of soil core samples was conducted.

Preliminary findings indicate higher penetration resistance and bulk density, coupled with reduced air capacity in top and subsoils on the headland, where greater traffic intensity takes place. The complete data set will be presented and discussed at the conference.

The conclusions of this study will provide a better understanding of the interactions between soil compaction, root growth and carbon storage. These findings are relevant to assess how soil management affects soil compaction and thus may hinder climate-adapted agriculture.

How to cite: Wiedermann, E., Reinelt, L., Rolfes, L., and Don, A.: Restricted root growth caused by traffic induced soil compaction – a field study in wheat and maize, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9353, https://doi.org/10.5194/egusphere-egu24-9353, 2024.

EGU24-9810 | ECS | Orals | SSS9.11

Grey alder and birch as an admixture in Norway spruce stands: Effects on soil nitrogen and carbon pools 

Päivi Soronen, Sandra Jämtgård, Mari Myllymäki, and Aino Smolander

Norway spruce monocultures in the boreal region are vulnerable to the effects of climate change and unfavourable in terms of soil fertility. Introducing broadleaved tree species to these forests may increase not only the resilience of the forest ecosystem to climate change but also enhance soil productivity and carbon (C) stock. We studied how grey alder, having symbiosis with N2-fixing Frankia, and birch affect soil nitrogen (N) and carbon pools as an admixture in Norway spruce stands in Southern Finland.

Study sites were three 40–60-year-old Norway spruce (Picea abies (L.) Karst.) -dominated stands with both grey alder (Alnus incana) and birch (both Betula pendula and Betula pubescens) as an admixture and a 20-year-old spruce stand with an admixture of grey alder. The forest type was a relatively fertile Oxalis acetosella – Vaccinium myrtillus type (OMT) on the two older (60 yr) sites and a slightly less fertile Vaccinium myrtillus type (MT) on the two younger sites (20–40 yr), applying the Finnish forest type classification. We took the soil samples at a 50–100 cm distance from 3–8 stems of the different tree species for the determinations of soil C and N stocks from all sites and for additional characterisation of organic matter only from the 60-year OMT sites. Soil diffusive N fluxes were measured using in situ microdialysis sampling and the subsequent laboratory analyses of plant-available N compounds.

On average, forest floor N stock was larger under the canopy of alder versus birch or spruce. C-to-N ratios of forest floor and topmost 10 cm mineral soil layer were lower under alder versus spruce. Soil C stock was affected by tree species only at the 40-year MT site, where alder had a higher forest floor C stock than birch or spruce. Differences in diffusive N fluxes between tree species were non-significant, and we observed inconsistent trends at different sites. C mineralisation rate tended to be lower under alder versus spruce on the two 60-year OMT sites, and the amount of microbial biomass N was lower under alder versus birch. Microbial biomass C-to-N ratio and forest floor thickness were lower under birch than spruce on one of the 60-year OMT sites.

The results point towards complex interactions and dynamics between tree species in mixed forests. Although we observed tree-species-induced spatial variation in soil properties, the distribution of above- and belowground litter and root activities in mixed stands reduces the differences between tree species. We found tree species to affect N stocks and C-to-N ratios most strongly, alder altering soil properties of spruce stands more than birch.

How to cite: Soronen, P., Jämtgård, S., Myllymäki, M., and Smolander, A.: Grey alder and birch as an admixture in Norway spruce stands: Effects on soil nitrogen and carbon pools, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9810, https://doi.org/10.5194/egusphere-egu24-9810, 2024.

EGU24-9895 | ECS | Orals | SSS9.11

Revisiting the relationships between maize root elongation and penetrometer resistance, air-filled porosity and macro- porosity on a clay loam Mollisol 

Shijie Qin, Lingling Liu, W. Richard Whalley, Hu Zhou, Tusheng Ren, and Weida Gao

Analysis of the effects of soil penetrometer resistance (PR) on root elongation and relative classic prediction models mostly ignore the role of macropores, which are important for root to penetrate compacted soils. In this study, undisturbed soil samples were collected from an 11-years tillage experiment (no-tillage and conventional tillage) in Northeast China, and their bulk density (BD), PR, air-filled porosity (AFV), and pore-size distribution were determined. Root elongation of maize seedlings was determined on each soil cores following equilibration at -20 kPa. Our results showed root elongation is significant negatively correlated with BD, PR, and the volume of Pores < 6 µm, while positively correlated with the AFV and macropores (Pores > 60 µm) (P < 0.001). Root elongation rate exhibited a 50% reduction when PR was over 1.3 MPa or AFV was below 10%. A new model has been developed to estimate the rate of root elongation that taken into account the interaction between PR and macropores. The new model had a better performance than previous ones and the root mean square error (RMSE) was 0.13.

How to cite: Qin, S., Liu, L., Whalley, W. R., Zhou, H., Ren, T., and Gao, W.: Revisiting the relationships between maize root elongation and penetrometer resistance, air-filled porosity and macro- porosity on a clay loam Mollisol, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9895, https://doi.org/10.5194/egusphere-egu24-9895, 2024.

Compaction is one of the main types of soil degradation worldwide. The macropores left by ex-plant roots were expected to provide channels to root to penetrate hard soil layers. However, there are few studies to quantitate the relationship between the elongation of maize roots and the root pores, due to complex morphological characteristics of the real root pore systems. In this study, we tried to build an artificial pore with sheath to simulate the effects of root pores on maize root growth in the compacted soil by X-ray CT. Our results indicated that the method for simulating root pores worked well. The sheath width of artificial root-pore was about 2.69 mm. Moreover, sheath of pores had higher organic carbon content and abundance of actinobacteria compared with bulk soil. Compared with artificial macropores, the presence of artificial root-pores diminished the border effects of the pot wall and increased the growth angle of node1 roots and the maximum growth depth of maize roots. However, there were no significant differences in terms of roots spatial distribution (in soil matrix, macropore sheath, macropore), and the ways (crossing or colonizing) of utilization by maize roots to macropores between the treatments with artificial macropores and artificial root-pores. This study provides a new insight into the interactions between root pore, root-pore sheath and maize roots.

How to cite: Gao, W., Liu, L., and Qin, S.: Effects of artificial root-pores on maize roots growth in compacted soil using X-ray computed tomography, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10487, https://doi.org/10.5194/egusphere-egu24-10487, 2024.

EGU24-10630 | ECS | Orals | SSS9.11

Effects of timber harvesting techniques on soil biodiversity and greenhouse gas fluxes of temperate forest soils susceptible to compaction 

Armin Hofbauer, Maximilian Behringer, Marcus Froemel, Lisa Gasser, Julian Grünberg, Christoph Haas, Klaus Katzensteiner, Martin Kühmaier, Gerhard Markart, Gertraud Meissl, Nikolaus Nemestothy, Boris Rewald, Christian Scheidl, Matthias Schlögl, Alexandra Wieshaider, and Barbara Kitzler

Temperate forests are a substantial sink for the greenhouse gases (GHG) methane (CH4), carbon dioxide (CO2) and soil emissions of nitrous oxide (N2O) are low. However, most of these forests are managed with ground-based harvesting systems causing severe soil disturbance. Soil displacement and compaction has a long-term effect on the soil microbial community structure and alters soil respiration, CH4 uptake, and nitrogen turnover. This significantly reduces the soil ecosystem services on extraction tracks and landings. Soil disturbance is particularly severe and persistent in compaction-prone silty and loamy soils, emphasizing the urgent need for specific techniques for these sites.

In an empirical Before-After Control-Impact study we compare the effects of harvester-forwarder use with/without tracks (HF/HFt) and cable-yarding with motor-manual-felling (CMM), on the soil chemistry, microbial community, and the soil-GHG balance. Our study is carried out within the project HoBo: Securing the Sustainability of Forest Soil Functions via Optimized Harvesting Technologies (https://dafne.at/projekte/hobo). The study sites are located in the Flysch zone and in the Molasse basin (North Alpine foreland basin). Soil GHG flux rates of CO2, CH4, and N2O are measured with trace gas analyzers (Li-Cor 7810 and 7820), either manually at the recently thinned stands, or continuously with automatic chambers at plots that were thinned in 2016.  For deeper understanding of the effects on soil chemistry and the changes in the microbial community, we determine nitrogen availability, microbial biomass carbon and nitrogen as well as the phospholipid fatty acids (PLFA).

Preliminary results show a significant impact of all applied mechanized timber harvesting systems (HF/HFt/CMM) reducing CH4 uptake rates and increasing N2O emissions of both skid trails and cable yarding corridors, compared to the control plots outside the extraction tracks (thinned stand). Our findings underline that sustainable forest management practices should not only reduce soil compaction. It should also consider additional factors, particularly soil displacement induced by logging activities.

How to cite: Hofbauer, A., Behringer, M., Froemel, M., Gasser, L., Grünberg, J., Haas, C., Katzensteiner, K., Kühmaier, M., Markart, G., Meissl, G., Nemestothy, N., Rewald, B., Scheidl, C., Schlögl, M., Wieshaider, A., and Kitzler, B.: Effects of timber harvesting techniques on soil biodiversity and greenhouse gas fluxes of temperate forest soils susceptible to compaction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10630, https://doi.org/10.5194/egusphere-egu24-10630, 2024.

EGU24-12361 | Posters on site | SSS9.11

Spatio-temporal modelling of wheel load carrying capacity (WLCC) to mitigate soil degradation at regional scale 

Michael Kuhwald, Katja Kuhwald, and Rainer Duttmann

Soil compaction caused by intensive field traffic is one of the main threats to agricultural soils. Soil compaction occurs when the applied soil stress is higher than the soil strength. Both, soil strength and stress, are highly variable in space and time. While soil strength mainly depends on environmental conditions (e.g. weather, soil type, crop type), soil stress results from the used machinery. One key parameter for the applied soil stress is the wheel load which results from the machinery setup. The wheel load carrying capacity (WLCC) approach takes this into account and specifies the maximum wheel load until soil stress does not exceed the soil strength.

The objective of this study is to model and analyse the dynamic variation of WLCC at regional scale for a 5-year period (2016-2020). We selected a study area (~2000 km²) with highly mechanized agriculture in Northern Germany where the main crops are cereals, maize and sugar beets. Sentinel-2 images were used to derive the crops for the 5-year period. We calculated the WLCC using an advanced version of the SaSCiA-model (Spatially explicit Soil Compaction risk Assessment) for each day of the 5 years.

The results show a high temporal dynamic characteristic of the WLCC during the crop rotation at regional scale. The relatively dry years 2016 and 2018 increased the maximum allowable wheel load, especially during harvesting of maize and sugar beets in autumn. In all 5 years, spring was the time with the lowest WLCC. At this time, however, high soil stresses occur due to the application of slurry and digestates, which is associated with high soil compaction risk. The spatial variation of WLCC depends on the one hand on soil properties such as soil texture. On the other hand, the used crop has a high effect on the WLCC due to different soil water utilization.

Based on the spatio-temporal analysis of WLCC at regional scale, an assessment can be performed to reduce the soil compaction risk either by increasing the soil strength or by decreasing the soil stress. We show exemplarily how the adjustment of tire inflation pressure affects the WLCC. Finally, this study may contribute to understand WLCC dynamics in crop rotations at regional scale and may help to mitigate further soil compaction.

How to cite: Kuhwald, M., Kuhwald, K., and Duttmann, R.: Spatio-temporal modelling of wheel load carrying capacity (WLCC) to mitigate soil degradation at regional scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12361, https://doi.org/10.5194/egusphere-egu24-12361, 2024.

EGU24-12523 | Orals | SSS9.11

Correlating tomography structure parameters with physical soil functions in representative sites in Schleswig-Holstein, Germany 

Svenja Roosch, Jocelyn Ormeno, Daniel Uteau, Heiner Fleige, Anneka Mordhorst, Jens Rostek, Conrad Wiermann, Gerrit Müller, and Stephan Peth

Soil structure influences important soil functions like hydraulic conductivity and air permeability, which in turn influence plant growth. The physical structure of soils is thus, besides chemical and biological parameters, one major component of soil fertility. Unfortunately, this physical fertility is often impaired by agricultural practices.

To study the structural status and the relationships between structural and functional parameters, 45 representative arable sites in Schleswig-Holstein, Germany, were sampled at three depths in top- and subsoil. Soil structure was described quantitatively using X-ray computed tomography of soil cores (continuity and size distribution of macropores). Measured soil functions included saturated hydraulic conductivity, air permeability, air capacity, and pore size distribution (via water retention curves).

The results not only help elucidate relations between structural and functional soil parameters. They also give a detailed and comprehensive insight into the structural state and their relation to soil physical functions of typical arable sites across Schleswig-Holstein that has not existed before.

How to cite: Roosch, S., Ormeno, J., Uteau, D., Fleige, H., Mordhorst, A., Rostek, J., Wiermann, C., Müller, G., and Peth, S.: Correlating tomography structure parameters with physical soil functions in representative sites in Schleswig-Holstein, Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12523, https://doi.org/10.5194/egusphere-egu24-12523, 2024.

EGU24-15630 | Posters virtual | SSS9.11

How do land use and land cover changes affect soil properties and nutrients in abandoned agricultural terraces? 

Noemí Lana-Renault, Manel Llena, José Arnáez, Elena Gómez-Eguílaz, Estela Nadal-Romero, and Erik Cammeraat

Agricultural terraces are very conspicuous features of many mountain landscapes in the world. In the Mediterranean region, rural depopulation and farmland abandonment has led to a process of vegetation expansion on former cultivated terraces, either by natural revegetation or afforestation programs. The main objectives of this study were i) to determine land use changes in a representative Mediterranean mountain area dominated by agricultural terraces in the past, and ii) investigate the effect of different land use and land cover (LULC) on soil properties, SOC and N stocks. For this purpose, five different LULCs (cultivated land, dense and sparse shrublands, old Q. ilex forest and P. sylvestris afforestation) were selected in terraced slopes in the Iberian range, in N. Spain. For each LULC, soil samples were collected every 10 cm down to 50 cm. The results showed that in the last 70 years, shrub cover has doubled (from 280 ha in 1957 to 430 ha in 2020) and forest cover has increased from 46 ha to 171 ha. SOC and N contents strongly decreased with depth, except for the cultivated plots, where the values remain similar through the soil profile. In the top layer, SOC contents were higher in Q. ilex, followed by afforested P. sylvestris, dense and sparse shrubland and cultivated plots. N contents presented a similar pattern except for afforested P. sylvestris, which presented the lowest values. SOC and N stocks were higher in Q. ilex, cultivated land, dense and sparse shrubs, and afforested P. sylvestris. Understanding the effects of LULCC on soil properties and nutrients is essential to assess land management practices after farmland abandonment on agricultural terraces.

Acknowledgements: This research was supported by the MANMOUNT project (PID2019-105983RB-100/AEI/10.13039/501100011033), funded by the MICINN-FEDER.

How to cite: Lana-Renault, N., Llena, M., Arnáez, J., Gómez-Eguílaz, E., Nadal-Romero, E., and Cammeraat, E.: How do land use and land cover changes affect soil properties and nutrients in abandoned agricultural terraces?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15630, https://doi.org/10.5194/egusphere-egu24-15630, 2024.

EGU24-16030 | ECS | Orals | SSS9.11

Could tree species be a key factor on soil carbon balance in temperate forest? 

Clément Bonnefoy-Claudet, Mathieu Thevenot, Jean Lévêque, Elodie Cognard, Anne-Lise Santoni, Jean Cacot, and Olivier Mathieu

Soils play a key role in regulating atmospheric concentrations of greenhouse gases notably by their action on organic carbon dynamics (storage vs. release). Forests occupy 31% of the continental surface and store around 40% of the continental organic carbon, half of it in soils. Ongoing climate change could alter the balance of this stock, and the effect of temperature on soil carbon fluxes remains an important question. In this study, we use the Q10 parameter (i.e. increase in CO2 emission for a 10°C rise in temperature) to estimate the temperature sensitivity of soil organic matter in four forest tree species (beech, spruce, douglas fir and silver fir). In addition, soil organic carbon stocks were estimated and compared with Q10 values and forestry data (volume, basal area, density and dead wood).

The mont Beuvray site (Morvan Regional Park, France), a mid-mountain area of around 1,000 ha with a quite homogeneous geology and pedology, was selected. On this site, Beech forests correspond to historical land use, while softwood forests have been gradually introduced over the past 70 years. Thus, 48 soil samples (0-20 cm) were collected (12 per tree species) and the main physicochemical characteristics were determined (bulk density, stone content, pH, organic carbon and total nitrogen contents, water-extractable organic carbon). The Q10 was calculated for a temperature range of 5 to 25°C in the laboratory using a Respicond X (Nordgren Innovations AB, Sweden).

Results show that soil organic carbon and water-extractable organic carbon contents are higher in silver fir and beech stand soils than in Douglas fir stand soils. For soil organic carbon stocks, the average values are slightly higher for beech and silver fir than for Douglas fir and spruce, but there is no statistical difference between the four tree species.  Q10 values range from 2.3 to 3.0, with a statistical higher value for beech (2.8 ± 0.1) than for the other softwood species (2.6 ± 0.1). This last result suggests that, for similar initial soil conditions, CO2 emissions from soil in beech stands would increase more strongly with temperature than in other species.

In conclusion, several decades after the introduction of softwood species, we did not measure in the top soil (0-20 cm) significant difference in carbon stocks. However, CO2 emissions and Q10 values are different and related to forest species. Hence, beech stand soils, corresponding to the historical land cover, could see their CO2 flux increase as they are the most sensitive to temperature. Conversely, silver fir stands, with their lower sensitivity to temperature, could be of interest in mitigating emissions. These results need to be confirmed by field data on soil respiration and compared with above-ground forest biomass and stand health.

How to cite: Bonnefoy-Claudet, C., Thevenot, M., Lévêque, J., Cognard, E., Santoni, A.-L., Cacot, J., and Mathieu, O.: Could tree species be a key factor on soil carbon balance in temperate forest?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16030, https://doi.org/10.5194/egusphere-egu24-16030, 2024.

EGU24-17045 | ECS | Orals | SSS9.11

The legacy of compost and slurry amendments to soil on physical resilience to compaction 

Utibe Utin, Jo Smith, Josie Geris, and Paul Hallett

Organic amendment of soils with composts or slurries affects compaction resistance and resilience, but the longevity of these impacts has not been explored, and few data are available from controlled field studies.  Here we carried out a rapid soil compaction resilience test, where coarsely sieved soil to simulate a freshly prepared seedbed are exposed to controlled compaction and cycles of wetting and drying in the laboratory. Agricultural soils with long history of compost and slurry amendments were sampled from the Lower Pilmore field of the James Hutton Institute, Dundee, UK.  Replicated plots received three levels of compost (35, 100 and 200 Mg ha-1), three levels of slurry (10, 20 and 40 Mg ha-1) and control (no amendment) from 2005 to 2009. Subsequently, normal rates of 35t ha-1 and 10 t ha-1 were applied until 2014. Loose soils sampled in 2023 were sieved to 4mm and then compressed cyclically under uniaxial stresses of (i) 50kPa to simulate a roller, (ii) 200kPa to simulate a tractor, and (iii) again at 200kPa. Between each of these stress cycles the soils were saturated (wetting) for 24 hours and drained (drying) to field capacity (5kPa) for 12 hours on a sandbox. Changes in void ratio during the loading and unloading phases were obtained directly from sample displacement, while the void ratio after wetting and drying was calculated from soil mass-volume relationship. Void ratio increased with increase in organic carbon in both compost and slurry soils. Soil wetting-drying following the first and second 200kPa compression cycles caused significant recovery of void ratio for both compost and slurry. Final void ratio (measured after the wet-dry cycle that followed the second 200kPa compression) was 0.40 m3 m-3 in the control, versus 0.45 m3 m-3 in 35 Mg ha-1 compost and 0.49 m3 m-3 in both 100 and 200 Mg ha-1 compost. For slurry soils, final void ratio was 0.40, 0.41 and 0.45 m3 m-3 for 10, 20 and 40 Mg ha-1, respectively. Organic carbon accounted for a significant percentage (R2 = 0.48; p = 0.00) of variability in the final void ratio for compost soils whilst there was no significant relationship between void ratio and organic C in slurry soils. Compression and recompression indices increased more with increase in compost than with increase in slurry, but overall, they displayed no significant (p≤0.05) relationships with organic carbon. Soils treated with compost are therefore, better able to absorb compressive stresses than their slurry counterparts and could significantly recover their form and capacity to perform their ecological functions following stress withdrawal. Moreover, legacy applications of compost than slurry can affect compaction resilience for several years.

How to cite: Utin, U., Smith, J., Geris, J., and Hallett, P.: The legacy of compost and slurry amendments to soil on physical resilience to compaction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17045, https://doi.org/10.5194/egusphere-egu24-17045, 2024.

EGU24-17138 | Orals | SSS9.11

Increased sensitivity of microbial respiration to soil water content in a fertilized boreal forest 

Boris Ťupek, Aleksi Lehtonen, Stefano Manzoni, Petr Baldrian, Bartosz Adamczyk, and Raisa Mäkipää

Projections of soil carbon (C) models are known to underestimate soil C stocks in boreal soils with higher nutrient status which is likely because they do not account for effects of soil nutrient status on the kinetics of microbial respiration and their sensitivities to environmental conditions. Here we evaluated the effects of long-term N addition (once per decade since 1960 until 2020) on soil heterotrophic respiration (Rh) and its dependence on soil temperature and moisture in an originally N limited boreal Scots pine (Pinus sylvestris) forest.

We measured Rh, soil temperature and soil moisture biweekly during the vegetative seasons of 2021-2023 in both fertilized and control forests. We fitted Rh rates to soil temperature and moisture separately for the control and N fertilization treatment using parametric non-linear regression models and non-parametric machine learning (boosted regression tree) models.

The functional dependencies of Rh were similar between fertilized and control forests for soil temperature but differed for soil moisture. In the N fertilized forest soil, Rh increased rapidly from dry conditions towards a soil moisture optimum followed by a clear reduction in wet conditions. In contrast, in the N limited forest soil, Rh mainly increased with soil moisture.

The models based solely on temperature (assuming identical and non-limiting effect of moisture) predicted higher annual Rh than the models accounting for soil moisture effects. Thus, to avoid overestimation of soil CO2 emissions and underestimation of soil C stocks accumulation in fertile boreal soils, it is crucial to link the soil moisture dependencies in soil C models to nutrient status. The different Rh response to moisture between N limited and N fertilized soils could be related to different levels of enzyme activities and contrasting microbial traits found by other studies.

How to cite: Ťupek, B., Lehtonen, A., Manzoni, S., Baldrian, P., Adamczyk, B., and Mäkipää, R.: Increased sensitivity of microbial respiration to soil water content in a fertilized boreal forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17138, https://doi.org/10.5194/egusphere-egu24-17138, 2024.

EGU24-17507 | ECS | Orals | SSS9.11

Effects of Logging-Induced Soil Compaction on the Abundance and Characteristics of Fine Roots and Mycorrhizal Associations in Forest Soils and their Recovery 

Lisa Gasser, Maximilian Behringer, Marcus Froemel, Douglas Godbold, Julian Grünberg, Christoph Haas, Armin Hofbauer, Klaus Katzensteiner, Barbara Kitzler, Martin Kühmaier, Gerhard Markart, Gertraud Meissl, Nikolaus Nemestothy, Hans Sandén, Christian Scheidl, Alexandra Wieshaider, and Boris Rewald

Soil compaction in forests, often a result of logging activities, poses a significant threat to soil functioning and ecosystem services. Root systems and their symbiotic relationships with mycorrhizae are particularly affected. Given the vital role that sustainably managed forest ecosystems play for climate change resilience and mitigation, understanding the effects of soil compaction on belowground functioning is critical. To address knowledge gaps on the interactions between soil compaction, root growth, and mycorrhizal associations under real-world conditions, it is essential to conduct comparative studies on different harvesting methods. Detailed analyses are required to better understand the spatiotemporal effects of logging on soil as a rooting space. 

To investigate the complex relationships, we implemented different harvesting methods (harvester-forwarder with or without bogie tracks, cable-yarding with motor-manual-felling) and a control treatment between skidding trails in a beech-dominated forest in Lower Austria during the winter of 2022/23. In addition, we sampled ~20-year-old skidding trails (harvester-forwarder) to assess soil recovery.

Using a replicated transect approach across the skidding trails, we studied spatially explicit effects on standing fine root biomass to a depth of ~45 cm in a before-after control-impact design. To allow for upscaling, each transect included areas directly impacted by logging (i.e. skidding trails, cable-yarding corridors) and areas potentially indirectly affected (i.e. between the ruts, bulge area etc.). We conducted comprehensive assessments of fine root biomass depth distribution, and key traits such as anatomy, morphology and fine root nutrient content, as well as mycorrhization rates. 

The data indicate a significant negative influence of both recent and historical timber harvesting on standing root biomass, revealing altered patterns of root distribution with notable differences between and within transects. Our results suggest that different harvesting methods result in very different levels of soil compaction, leading to contrasting effects on fine root traits such as a reduction of absorptive surface area relative to biomass in compacted soil. 

The persistence of negative effects on the old skidding trails highlights the long-lasting impact on root systems and their mycorrhizal symbionts, and thus key ecosystem functions. This emphasizes the importance of conserving forest soils and the need to identify and implement management strategies to minimize soil compaction and promote recovery. These efforts are vital for ensuring the sustainable provision of ecosystem services by the 'hidden half' of forests.

How to cite: Gasser, L., Behringer, M., Froemel, M., Godbold, D., Grünberg, J., Haas, C., Hofbauer, A., Katzensteiner, K., Kitzler, B., Kühmaier, M., Markart, G., Meissl, G., Nemestothy, N., Sandén, H., Scheidl, C., Wieshaider, A., and Rewald, B.: Effects of Logging-Induced Soil Compaction on the Abundance and Characteristics of Fine Roots and Mycorrhizal Associations in Forest Soils and their Recovery, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17507, https://doi.org/10.5194/egusphere-egu24-17507, 2024.

EGU24-18128 | Posters on site | SSS9.11

A new measure to mitigate soil compaction: Stabilisation effects of greening headlands 

Carolin Körbs, Michael Kuhwald, Marco Lorenz, and Rainer Duttmann

A new measure to mitigate soil compaction: Stabilisation effects of greening headlands

Authors: C. Körbs1, M. Kuhwald1, M. Lorenz2, R. Duttmann1,

1Working group of Landscape Ecology and Geoinformation, Institut of Geography, Kiel University, Christian-Albrechts-Platz 4, 24118 Kiel, Germany

2Johann Heinrich von Thünen-Institut (TI), Thünen Institute of Agricultural Technology, Bundesallee 47, 38116 Braunschweig, Germany

 

Submitted 10. January 2024 to the EGU24

Session: SSS9.1- Soil degradation by soil compaction on arable land, grassland and in forests

 

The greening of fields is a common measure in agriculture to prevent soil erosion and often serves as an intercrop. Grass buffer stripes can stabilise the topsoil and thus reduce runoff and promote sediment retention and water infiltration. The existing literature lacks emphasis on examining the stabilising effects specifically related to the greening of headlands. Moreover, there is a need to explore how the implementation of greening practices can mitigate the adverse effects of field traffic and to what extent it can contribute to reducing soil compaction.

As part of the SOILAssist project investigations were carried out on a selected field at the experimental farm in Adenstedt (Lower Saxony, Germany) to study soil structure and functionality. One part of the headland was used to establish a greening with a width of 18m.

To analyse the effects of the greened headland, soil samples were taken in the core field, the greened headland, and the non-greened headland directly after the greening in 2019 and after 4 years in 2023. Disturbed and undisturbed soil samples were taken at 20, 35 and 50cm depth. Afterwards, the soil samples were analysed in the laboratory to provide information on physical soil properties e.g. dry bulk density, air conductivity, air capacity and aggregate stability. In addition, the yield was measured every year in each of the variants.

The results show that the dry bulk density in 2023 was predominantly lower in the core field in 2023 compared to 2019. In contrast, the dry bulk density in the greened headland was generally constant and in the non-greened headland it was slightly lower in 2023 than in 2019 at the depth of 20cm. The lower dry bulk density in the non-greened headland can be explained by the used primary tillage, which lowered the dry bulk density in the topsoil. Since there was no tillage on the greened headland, the effects despite the similar intensity of field traffic remained constant at this part of the field. However, the dry bulk density did not increase in the greened headland which indicates a stabilisation by the vegetation and thus lower the negative impacts of field traffic. At the depth of 35 and 50cm no significant changes were measured, neither for greened nor for non-greened headland.

Whether these effects become more apparent considering the correlation between various soil properties and to which extent a change in soil type plays a role in the stabilisation of headlands through greening will be investigated in the following studies.

How to cite: Körbs, C., Kuhwald, M., Lorenz, M., and Duttmann, R.: A new measure to mitigate soil compaction: Stabilisation effects of greening headlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18128, https://doi.org/10.5194/egusphere-egu24-18128, 2024.

EGU24-20393 | Posters on site | SSS9.11

Effects of drought and disturbance on the CO2 and CH4 fluxes in a mixed forest and spruce monoculture 

Michal Bosela, Boris Tupek, Peter Marcis, Dominik Poltak, Jergus Rybar, Jaroslav Vido, Paulína Nalevanková, Aleksi Lehtonen, and Raisa Makipaa

Spruce monocultures have been intensively planted across a wide area of Europe to increase timber production and meet the demand from society. However, evidence suggests that species monocultures may not be as resilient to drought spells and heat waves compared to mixtures of two or more species. The advantage of mixed forests over monocultures is particularly evident when the mixed species occupy different niches, reducing inter-specific competition and enabling better growth and increased carbon sequestration. However, it remains unclear how drought events and heat waves affect carbon sequestration in the soil and how this differs between mixed forests and species monocultures. In this study, we conducted two years of intensive monitoring of soil CO2 and CH4 fluxes, measured soil microbial diversity, and assessed long-term (tree ring) and seasonal tree growth to quantify carbon sequestration in a mixed forest and a spruce monoculture. Results showed that severe drought in 2022 significantly reduced the growth of Norway spruce stand and its' forest floor and soil CO2 fluxes but at lesser intensity impacted C fluxes of European beech and silver fir stand. The bark beetle outbreak in 2023 caused rapid tree infestation and die-back only in the spruce stand (followed by salvage clear-cut harvesting) which subsequently increased soil CO2 emissions via a sudden increase in litter input from dead trees, soil temperature and water content from reduction of shade and evapotranspiration.

How to cite: Bosela, M., Tupek, B., Marcis, P., Poltak, D., Rybar, J., Vido, J., Nalevanková, P., Lehtonen, A., and Makipaa, R.: Effects of drought and disturbance on the CO2 and CH4 fluxes in a mixed forest and spruce monoculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20393, https://doi.org/10.5194/egusphere-egu24-20393, 2024.

EGU24-21890 | Posters on site | SSS9.11

Identifying areas of multiple soil degradation processes at regional scale 

Bastian Steinhoff-Knopp, Michael Kuhwald, Katharina Bäumler, Philipp Saggau, and Marco Lorenz

Soil compaction and soil erosion by water are among the top 5 threats to agricultural soils in Europe. Soil compaction has a direct impact on soil erosion, for instance by reducing infiltration rates. Therefore, measures directly addressing soil compaction (e.g. optimized field traffic and reduced wheel load) have an impact on soil erosion by water. In addition, measures such as crop rotation management, including cover crop management, allow combined effects on soil erosion and soil compaction. Currently, no evidence at regional scale is available that indicates which measures can generate this co-benefit and which regions having a high risk of soil erosion and compaction can benefit from those measures. Modelling exercises provide the option for generating this information and are tested here in a regional scale case study.

As a first step, we identified cropland with a combined risk of soil compaction and soil erosion by water in Lower Saxony (northern Germany). To this end, we derived typical crop rotations for 2017 to 2021 based on high-resolution crop type maps for three soil regions in the study area. Depending on the crop rotations and farm size, typical machinery equipment was defined and field work dates were derived according to phenological data. This data was combined with three weather scenarios using real observational data (dry: 2020, wet: 2017, intermediate: 2004). We employed the USLE (Universal Soil Loss Equation) and the SaSCiA-model (Spatially explicit Soil Compaction risk Assessment) to model soil erosion and soil compaction risk for the different weather scenarios and the three typical crop rotations in the soil regions. The results help to identify regions with combined risk for soil erosion and soil compaction. The next step will be the analysis of measures addressing both degradation processes.

How to cite: Steinhoff-Knopp, B., Kuhwald, M., Bäumler, K., Saggau, P., and Lorenz, M.: Identifying areas of multiple soil degradation processes at regional scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21890, https://doi.org/10.5194/egusphere-egu24-21890, 2024.

EGU24-144 | Posters on site | SSS9.12

Growth of green manures under greenhouse: development of a plant selection for a sustainable soil management in Central Spain 

Carlos García-Villarrubia Bernabé, Marta M. Moreno Valencia, and José A. López-Perez

The application of green manure in agrarian soils is becoming a sustainable tool to improve soil quality and plant pathogen management. One of the expected characteristics of a plant to be used as a potential green manure is to produce a minimum amount of biomass in order to have sufficient material to perform their role adequately. Green manure management was selected to be included in a crop rotation in order to improve yield and sanitary properties. Five species were chosen due their beneficial properties: Brassica carinata cv Eleven, Camelina sativa cv Beemelina, Pisum sativum cv Viriato, Raphanus sativus cv Melody, and Tagetes patula cv Helen. Four replicates of each treatment were established. Seeds were sown after summer crop so that they grew enough to be applied as green manure before the establishment of the winter crop, Swiss chard. A seeded green manure planting scale has been developed to assess differences in germination when plants are at the 3-4 true leaf stage. The best growth and development was shown by R. sativus, probably due to its higher tolerance to thermic stress. After three seasons, the selected moment of implantation, right after the summer crop, showed a good performance of the selected green manures.

 

Operational programme FEDER 2021-2027 Castilla-La Mancha: Development of strategies for mitigation and adaptation of agricultural soils to climate change

How to cite: García-Villarrubia Bernabé, C., Moreno Valencia, M. M., and López-Perez, J. A.: Growth of green manures under greenhouse: development of a plant selection for a sustainable soil management in Central Spain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-144, https://doi.org/10.5194/egusphere-egu24-144, 2024.

This study introduces a novel smartphone-assisted imaging device for efficient control of agricultural inputs and environmental pollution monitoring by quantifying phosphate (PO43-) and nitrate (NO3) concentrations in soil and water samples. Utilizing the smartphone's digital camera, the cost-effective and portable device employs standard colorimetric procedures with chromotropic acid and ascorbic acid for NO3 and PO43- detection, respectively. The integrated back camera connects to a handheld system housing ocular sources and optical components, enabling on-the-go measurements. Leveraging the Value (V) component of the HSV color space model, the device estimates NO3 and PO43- concentrations, producing results comparable to laboratory spectrophotometers. Additionally, this study explored RGB, CMYK, and CIELAB color space models, validating the device's effectiveness with 30 soil and 15 water samples. In summary, this user-friendly device offers a reliable, cost-effective solution for measuring NO3 and PO43- levels in soil and water, presenting results comparable to traditional spectrophotometers without the need for laboratory apparatus.

Index Terms— soil, water, nitrate, phosphate, smartphone, imaging device, HSV, RGB, CMYK, CIELAB

How to cite: Veerabhadrappa, L., Dey, S., and Chakraborty, S.: Comparison of Different Color Space Model's Performance for Estimation of Nitrate and Phosphate in Soil and Water Using A Smartphone-Integrated Imaging Device, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2851, https://doi.org/10.5194/egusphere-egu24-2851, 2024.

EGU24-3195 | ECS | Orals | SSS9.12

Could amending different organic wastes with Pulp and Paper Mill Sludge (PPMS) thrive the production performance of Eisenia fetida?  

Dasinaa Subramaniam, Mano Krishnapillai, and Lakshman Galagedara

Large quantity (150 Mg/day) of Pulp and Paper Mill Sludge (PPMS) is being generated in Corner Brook Pulp and Paper Limited (CBPPL), Newfoundland, Canada. Since PPMS contains high level of organic matter-OM (80-85%) and moisture content-MC (50-60%), it may be considered for recycling as vermicompost and earthworm as animal feed. An initial attempt on vermicomposting PPMS using Eisenia fetida had a long processing time up to 80-90 days. Therefore, the current study was designed to shorten the processing time by amending PPMS with different organic wastes and monitoring production performance of Eisenia fetida.

Organic wastes - poultry bedding material (SP), vegetable peels (SV), soil (SS), fresh cow manure (SC-L) and composted cow manure (SC-C) were amended separately with PPMS in 2:1 ratio as the treatments while PPMS alone was the control (S). About 14.1-14.5 g of earthworms/ 3.6 kg of substrate (an average stocking density of 4 g/kg) were introduced in all the treatments which were triplicated in completely randomized design. Changes in vermicompost parameters such as pH, electrical conductivity (EC), OM, MC, etc. were monitored weekly and the population dynamics of earthworms were studied, bi-weekly. The MC was maintained at about 75-80% in all the treatments. Results showed that amending organic wastes with PPMS had a significant (p< 0.0001) influence on the quality and quantity of the final vermicompost produced. The total quantity of vermicompost produced was higher (73.8%) in SC-L followed by SV (70.4%), SC-C (69.8%), SS (67.3%), S (64.3%) and SP (8.8%) in 45 -50 days. pH decreased in all the treatments except in control until 30 days and increased afterward to reach the range between 6.1 and 7.3. EC in all the treatments S, SV, SS and SC-L (except SP and SC-C) reduced from the initial value of 2.90, 2.66, 1.23 and 3.18 to 2.58, 2.56, 2.69 and 2.69 mS/cm, respectively. Simultaneously, OM content showed a decline in all the treatments, while the reduction rate was higher in SS (4.71%) > SV (4.02%) > SP (3.94%) > SC-L (2.91%) > SC-C (2.67%) > S (1.81%). Total biomass gain of Eisenia fetida was 56.1%, 40.4%, 22.3% and 13.4% in SC-L, SC-C, SV and SS, respectively in day 45. Conversely, a reduction in earthworm biomass of 55.8% and 60.1% was observed for S and SP, respectively. The average biomass growth rate was higher in SC-L (1.73 g/day) followed by SV (1.35 g/day) and SS (1.22 g/day). As a whole SC-L, SC-C, SV and SS had no significant difference (p> 0.05) among them in both total biomass gain and growth rate while those treatments had the significant difference with S and SP (P< 0.0001). Therefore, we conclude that the PPMS can be an excellent substrate to reuse in vermicomposting. However, incorporating various organic manures and wastes could enhance the vermicomposting rate and significantly reduce the processing time. Further improvements can be achieved by adjusting factors such as the types and ratio of organic wastes, and the number of earthworms involved.

Keywords: Eisenia fetida, PPMS, cow manure, vegetable peels, poultry bedding, soil

How to cite: Subramaniam, D., Krishnapillai, M., and Galagedara, L.: Could amending different organic wastes with Pulp and Paper Mill Sludge (PPMS) thrive the production performance of Eisenia fetida? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3195, https://doi.org/10.5194/egusphere-egu24-3195, 2024.

EGU24-3532 | ECS | Orals | SSS9.12

A field trial study on long-term effects of organic farming on the retention of plant available soil water 

Michael Hofbauer, Václav Šípek, and Petr Dvořák

With regard to an increasing intensity and frequency of drought and heavy rainfall, there is a need to adapt arable farming to these climatic changes. In this respect, organic agriculture has a higher adaptation potential than conventional agriculture, since organic farming leads to an enrichment of soil organic carbon and a stimulation of soil biological activity in the long term. As a result, an improvement of soil structure, water infiltration and soil water retention can be expected as compared to conventional agriculture.

In April 2023, a study of soil hydraulic properties after 15 years of recognised organic management was commenced in the Czech Republic. The objective is to compare an organic farming system to a conventional farming system in terms of retention of plant available soil water. The hypothesis is that the retention of plant available soil water is higher in the organic farming system than in the conventional farming system.

The studied site is a long-term field trial on a clay loam soil in Praha-Uhříněves (P = 584 mm, T = 8.3 °C). In either farming system inversion soil tillage is carried out by mouldboard ploughing to a depth of 20 cm. For either farming system two plots with summer wheat (Triticum aestivum L.) are sampled in 2023 and 2024. In order to analyse soil water retention functions, saturated hydraulic conductivity, and soil organic carbon content, soil samples are taken in 10 cm and 30 cm soil depth each year in spring, summer, and autumn. In order to unravel the sources of plant available water, further soil samples are taken bimonthly in 10 cm, 30 cm, and 45 cm soil depth. The soil water’s isotopic composition (δ2H, δ18O) of these samples is analysed and compared to the rainwater’s isotopic composition. The volumetric soil water content is continuously recorded in 10 cm, 30 cm, and 45 cm soil depth.

Preliminary data from the first experimental year indicate that the volumetric soil water content in the organic farming system is higher than in the conventional farming system. In contrast, soil water retention and soil organic carbon content do not show differences between the two systems. However, for robust results with statistical validation, further data and analyses need to be waited for. Therefore, reliable conclusions regarding the hypothesis of a better retention of plant available soil water in the organic system will be possible in the course of the project.

This project is funded by the institutional support of the Czech Academy of Sciences (RVO: 67985874) and by the Faculty of Environmental Sciences of the Czech University of Life Sciences Prague (IGA grant No. 2023B0042).

How to cite: Hofbauer, M., Šípek, V., and Dvořák, P.: A field trial study on long-term effects of organic farming on the retention of plant available soil water, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3532, https://doi.org/10.5194/egusphere-egu24-3532, 2024.

EGU24-3688 | ECS | Posters on site | SSS9.12

Climate and soil properties cogovern rice arsenic: A longitudinal study 

Anh T.Q. Nguyen, Van M. Dinh, Nguyen T. Nguyen, and Minh N. Nguyen

Elevated accumulation of arsenic (As) in rice has recently been proposed as a tangible consequence of climate and environmental changes. This requires validation at global scale or at least regional scale. Unfortunately, no dataset is available that enables a direct connection of the levels of As in rice grain and climatic conditions. In this study, we collected soil and rice samples from 162 sites crossing a longitudinal transect (from latitude 8 to 22° N) that covers approx. 2000 km coastal line and numerous deltas in Vietnam territory. The sampling transect reflects the differences in terms of climate conditions, e.g., warm-wet (in the South including the Mekong River delta), warm-dry (South Central) and cold-wet (in the North Central and North). It was found that rice grain assimilated As at the concentrations ranging from 11.6 to 806.7 µg kg-1 ( = 153.1 µg kg-1). While rice tends to assimilate less As in the South ( = 110.3 µg kg-1), North ( = 154.9 µg kg-1) and North Central ( = 188.8 µg kg-1), peak accumulation of As was observed for rice grain in the South Central ( = 265.0 µg kg-1) where is warm-dry and soil As contents were lowest. This observation implies that rice in the South Central likely act less effectively to prevent the translocation of As from soil to rice. It is likely that climatic conditions through their geochemical effects, particularly in the fallow periods (when water is drained) have affected the translocation of As from soil to rice. This scenario is supported by statistical analysis that indicates close relations of grain As with Si, S, P and Fe in soils. However, more empirical evidence that demonstrates direct effects of climatic factors (such as temperature and humidity) on transformation/translocation of As in the soil-rice system are still required; and mesocosm experiments will be included in our future works.

Keywords: Arsenic; rice; climate; paddy soil; geochemistry

How to cite: T.Q. Nguyen, A., M. Dinh, V., T. Nguyen, N., and N. Nguyen, M.: Climate and soil properties cogovern rice arsenic: A longitudinal study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3688, https://doi.org/10.5194/egusphere-egu24-3688, 2024.

EGU24-5610 | Posters on site | SSS9.12

Rasch Model-Based Zone Delineation for Olive Orchard Management. 

Francisco Javier Rebollo Castillo, Francisco Jesús Moral García, Lourdes Rebollo Moyano, Cristina Aguirado Montero, Fulgencio Honorio Guisado, Abelardo García Martín, and Luis Lorenzo Paniagua Simón

Delineation of management zones in an olive orchard located in Badajoz, southwestern Spain was performed using the Rasch model. The objective was to obtain objective measures of production potential based on nine soil properties: soil apparent electrical conductivity, clay, sand, and silt content, organic matter, total nitrogen, available phosphorus and potassium, and cation exchange capacity. A total of 40 locations in the field were assessed, and the model integrated the soil properties to rank the locations according to their soil production potential. The influence of each individual soil property on the production potential was also determined. Any anomalies in the soil samples or properties were highlighted, providing information for site-specific treatments and enhancing cost-effectiveness and sustainability in field management. Geostatistical algorithms were employed to estimate and map soil production potential, enabling the delineation of management zones in the field based on a rational basis.

Keywords: predictive map, probabilistic model, soil production, Extremadura, olive tree.

How to cite: Rebollo Castillo, F. J., Moral García, F. J., Rebollo Moyano, L., Aguirado Montero, C., Honorio Guisado, F., García Martín, A., and Paniagua Simón, L. L.: Rasch Model-Based Zone Delineation for Olive Orchard Management., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5610, https://doi.org/10.5194/egusphere-egu24-5610, 2024.

EGU24-7995 | ECS | Posters on site | SSS9.12

Effects of biochar derived from wheat straw and chicken manure on the immobilization of Cu, Zn and Cd in sludge composting 

Weici Quan, Kai Yang, Yiwei Gong, Kaiming Yang, Yadi Ai, and Hongguang Cheng

The increasing production of sludge has added to the sewage treatment burden, making its disposal an important challenge for urban environmental management. Biochar has great potential to effectively reduce the mobility and bioavailability of heavy metals in municipal sludge due to its adsorption capacity. This study conducted a 20-day sewage sludge composting experiment with the addition of wheat straw and chicken manure biochars to test their effects on the sewage sludge physicochemical properties and immobilization of copper (Cu), zinc (Zn), and cadmium (Cd) in the sewage sludge. During composting, the physicochemical properties of the treatments changed to different degrees compared to the original pile. Specifically, pH, CEC, TP, and TK increased, while the content of OM and TN decreased. As a result of the concentration effect, the total contents of Cd, Cu, and Zn increased in both of the C1 and C2 treatments. In the present study, heavy metals were stabilized more effectively by the wheat straw biochar than that derived from the chicken manure. Both types of biochar are effective at immobilizing Cd, Cu, and Zn in the compost, while WSB is more effective. These results are affected by indirect physicochemical properties of the compost, as well as the direct ion exchange, complexation and precipitation. Therefore, these results indicate that it is feasible to use biochar, especially derived from the wheat straw, to immobilize heavy metals in the sludge.

How to cite: Quan, W., Yang, K., Gong, Y., Yang, K., Ai, Y., and Cheng, H.: Effects of biochar derived from wheat straw and chicken manure on the immobilization of Cu, Zn and Cd in sludge composting, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7995, https://doi.org/10.5194/egusphere-egu24-7995, 2024.

EGU24-9944 | ECS | Orals | SSS9.12

Long-term biochar and soil organic carbon stability – evidence from long-term field experiments in Germany 

Arthur Gross, Tobias Bromm, Steven Polifka, Daniel Fischer, and Bruno Glaser

Organic soil amendments with a long mean residence time (MRT), such as biochar have a high soil organic carbon (SOC) sequestration potential. The highly aromatic structure of biochar reduces microbial decomposition and explains the slow turnover of biochar. This stable aromatic structure indicates a long persistence in soils and thus potential SOC sequestration. However, there is a lack of data on these effects in the long-term and under real field experiment conditions.

To fill this knowledge gap, we sampled two long-term field experiments in Germany, where industrially produced  biochar has been applied nine and eleven years ago. Both locations differ in soil and climate characteristics as well as in the types and amounts of biochar amendments used. High biochar amount additions of 40 Mg ha-1 combined with digestate, compost or synthetic fertilizer on a very sandy and nutrient-poor soil in northern Germany led to a short-term increase of SOC stocks of 61 Mg ha-1, 38 Mg ha-1 dissipated in the following four years, and after nine years the biochar-amended soils showed only slightly higher SOC stocks (+7 Mg ha-1) than the control soil. Black carbon, which we additionally analysed as a molecular marker for biochar stability, increased in the short and mid-term and decreased almost to the original stock levels after nine years. Biochar amendments of 31.5 Mg ha-1, pristine, combined with compost or co-composted on a loamy soil in southern Germany led to an SOC stock increase of 38 Mg ha-1. After eleven years, this stock increase was still stable, thus confirming biochar-induced SOC sequestration. Black carbon stocks on the same soil showed large dispersion, indicating a loss of stability over the long-term.

This study proves that SOC sequestration through the use of biochar amendments is possible. However, it seems to depend on soil and biochar properties such as soil texture whether SOC stocks are stable in the long-term and dissipation can be mitigated, with the loamy soil seemingly offering better sequestration conditions. As considerable biochar dissipation was observed in both soils, further studies need to investigate whether the dissipation is due to lateral and/or vertical particle transport or microbial decomposition. This is an important question for the suitability of biochar as a reliable CO2 removal technology.

Keywords: Carbon sequestration, biochar dissipation, climate change mitigation, molecular marker

Acknowledgements: Funded by EU grant #101059546

How to cite: Gross, A., Bromm, T., Polifka, S., Fischer, D., and Glaser, B.: Long-term biochar and soil organic carbon stability – evidence from long-term field experiments in Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9944, https://doi.org/10.5194/egusphere-egu24-9944, 2024.

EGU24-10239 | Orals | SSS9.12

The impact of the sediment from agricultural diffuse pollution control surface-flow treatment wetland on soil fertility and grain yield 

Margit Kõiv-Vainik, Lii Lopp, Isaac Okiti, Mihkel Pindus, and Kuno Kasak

Climate change has brought more extreme and unexpected weather conditions that result in frequent storm events and longer drought periods that are making agricultural production much harder. Efficient production needs in addition to favorable weather conditions also sufficient amount of nutrients in the soil. In ecological agriculture common alternatives to artificial fertilizers are manure and digestates. The main role of agricultural diffuse pollution control treatment wetlands (TWs) is to mitigate contamination that is coming from agricultural fields. Captured nutrients and organic matter are stored in the TWs mainly as sediments. It is quite common practice to use lake sediments as an agricultural soil amendment, however, there is less information about the use of TW sediments for improving soil health and nutrition. 

The main aim of the current study was to determine the impact of TWs’ sediment on the soil fertility and grain yield during a large-scale field experiment conducted during one vegetation period from May until September 2023, in Estonia. The amendment effect of the sediment was compared with control (no amendment), digestate, and N:P:K mineral fertilizer. According to the initial soil composition and recommended fertilization rate for nitrogen and phosphorus, the needed amount of sediment, digestate, and fertilizer was applied to four field plots (48 m2 each) before spring wheat sowing. The experimental area had an onsite weather station measuring humidity, precipitation, and air temperature. Each plot had a total of 6 sampling points for monitoring: soil composition, microbial and fungal communities and roots development, wheat growth, and GHG emissions (LI7810 and LI7820 analyzers, LICOR Biosciences); and constant measurement of soil moisture, temperature, and electrical conductivity (probes WET-150; Delta-T Devices).  

One of the most important outcomes of the study was that during the extremely dry spring of 2023, the sediment amendment had much higher soil moisture content, which resulted in much earlier sprouting and earlier grain ripening. The soil fertility and composition were on average more favorable with sediment addition. After amendment with sediment, soil had an average TOC content of 3.1% of C, compared to 1.7% on the other plots. Sediment amendment resulted in much higher average plant-available Ca and Mg content compared to other plots. The highest average NO3 contents was with digestate and lowest with sediment (443 vs 112 mg/kg). The considerably higher yield was gained with sediment (on average 9417 kg/ha) while all other plots had a similar yield to each other (on average 6510 kg/ha). Further analyses will show how sediment affected soil communities and root development. 

Overall, we can conclude that agricultural soil amendment with TW sediment gave promising results for ensuring higher crop yield. Further studies are needed to determine if similar results can be shown with other crops and with combinations of different soil amendment practices. 

How to cite: Kõiv-Vainik, M., Lopp, L., Okiti, I., Pindus, M., and Kasak, K.: The impact of the sediment from agricultural diffuse pollution control surface-flow treatment wetland on soil fertility and grain yield, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10239, https://doi.org/10.5194/egusphere-egu24-10239, 2024.

EGU24-10274 | ECS | Orals | SSS9.12

Assessing the impact of valorized organic waste on plant productivity and soil health: a comprehensive performance evaluation 

Sana Boubehziz, Vidal Barrón, María del Carmen del Campillo, María de los Ángeles Martín Santos, María del Carmen Gutiérrez Martín, Lucia Guerrero-Gallardo, and Antonio Rafael Sánchez-Rodríguez

An expanding population with an increasing demand for alimentation exerts considerable stress on the agricultural system. This system depends on maintaining robust and fertile soils, typically achieved through the application of synthetic inputs such as fertilizers to preserve soil productivity. However, the availability of these fertilizers is finite, or their production and application have a negative impact on the environment. Consequently, the exploration of alternative, sustainable sources to ensure continued production minimizing the detrimental environmental effects are necessary. Therefore, alternative recycled organic wastes are potential soil fertilizers and / or amendment becomes an appealing choice, contributing to the establishment of a sustainable ecosystem and fostering soil health. Specifically, their phosphorus content has a specific relevance not only for the European Union but also for the rest of the world.

The aim of this research is to focus on evaluating the influence of applying various composted valorized organic wastes and by-products on enhancing soil productivity. Moreover, their influence on both soil composition and plant growth were evaluated. The characterization of physicochemical composition of soils and Durum wheat plant as well as crop yield were carried out. Heavy metals content was specially monitored.

With these purposes an experimental design under controlled conditions was built. Three soils (factor 1) with different physical-chemical characteristics were evaluated: a sandy non calcareous soil, Entisol (ENT), a calcareous Inceptisol (INC) and a calcareous Vertisol (VER). The soils were treated with different mineral products and organic valorized wastes, guaranteeing that the same quantity of phosphorus (P) was added with each by-product (50 mg  kg-1i.e,: C, a negative control with no P application,; DAP (Di-ammonium Phosphate), which was used as a positive control; EST (Estruvite), OMP (composted Olive Mill Pomace), OMP+EST; USW (composted Urban Solid Waste); USW+EST; S (composted Sludge from wastewater treatment plants) and S+EST. When combinations of composted wastes were used, each one was applied at a rate to add 50 % of the total P added. The main results showed that the OMP produced the lowest yield and biomass of the crop; however, EST, USW, and USW+EST produced the highest yields and biomass, which were similar or even higher than those produced with the application of DAP. In addition, the added organic treatments promoted enzymatic activity in the soil. Moreover, none of the added organic amendments significantly increased the heavy metal contents to critical levels. Finally, the added valorized products being used in agricultural conditions in Mediterranean soils had a positive effect on enhancing soil health and productivity depending on the soil type.

How to cite: Boubehziz, S., Barrón, V., del Campillo, M. C., Martín Santos, M. D. L. Á., Gutiérrez Martín, M. C., Guerrero-Gallardo, L., and Sánchez-Rodríguez, A. R.: Assessing the impact of valorized organic waste on plant productivity and soil health: a comprehensive performance evaluation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10274, https://doi.org/10.5194/egusphere-egu24-10274, 2024.

EGU24-10835 | ECS | Orals | SSS9.12

Comparative Analysis of Autonomous Agricultural Robots and Traditional Tractors in Mechanical Weed Control Efficiency 

Nebojša Nikolić, Marco Sozzi, Francesco Marinello, Luigi Sartori, and Roberta Masin

Mechanical weed control, as an alternative to pesticide use, offers dual benefits in terms of environmental and economic sustainability. However, the labour and resource intensity of conventional methods can be mitigated through innovative technologies, such as agricultural robots. This study assesses the performance of an agricultural robot ‘Robotti 150 D’ (Agrointelli, Aarhus, Denmark), in comparison to a traditional tractor, focusing on its efficiency in mechanical weed control in a maize field at the experimental farm of the University of Padova in northeastern Italy. The precision weeder employed for this assessment was Rotosark (OliverAgro s.r.l., Verona, Italy).

A 1.1-ha field was divided into 8 blocks worked halves by the robot and tractor, each further divided into sections with weeding operations conducted at 3 km/h and 5 km/h. Twenty-four randomly positioned 1 m² experimental plots were assessed for weed species presence via images analysed using ArcGIS Pro (v3.2.1. ESRI ArcGIS Pro©). Weed control efficiency was calculated by comparing weed presence and density before and after weeding operations. Long-term effects were evaluated by comparing weed biomass collected before harvest between plots managed by robot and tractor.

Both the robot and the tractor exhibited a weed control efficiency of approximately 95%, with no statistical differences observed between methods or velocities. Even at the species level, no significant differences were identified. Moreover, final weed biomass showed no significant distinctions between plots managed by robot and tractor.

These results suggest the autonomous robot demonstrates comparable efficacy in weeding to the traditional tractor. While further experiments are required to assess performance in diverse conditions, the study concludes that autonomous robots for mechanical weeding present a promising solution for precision agriculture. Despite their current availability on the market, these systems are in a developmental phase, requiring further refinement to meet user needs and preferences.

 

Acknowledgments: This study was carried out within the Agritech National Research Center and received funding from the European Union Next-GenerationEU (PIANO NAZIONALE DI RIPRESA E RESILIENZA (PNRR) – MISSIONE 4 COMPONENTE 2, INVESTIMENTO 1.4 – D.D. 1032 17/06/2022, CN00000022).

How to cite: Nikolić, N., Sozzi, M., Marinello, F., Sartori, L., and Masin, R.: Comparative Analysis of Autonomous Agricultural Robots and Traditional Tractors in Mechanical Weed Control Efficiency, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10835, https://doi.org/10.5194/egusphere-egu24-10835, 2024.

EGU24-11419 | Posters on site | SSS9.12

Research project: Hydromulches for weed control and water saving in a circular bioeconomy framework 

Marta María Moreno, Jaime Villena, Alicia Cirujeda, Gabriel Pardo, Jorge Pueyo, Lluís Martín-Closas, Josefa López-Marín, Amparo Gálvez, and Carmen Moreno

Weeds currently represent the most important factor limiting agricultural production, causing crop yield reductions estimated at 34% globally [1]. At present, herbicides and tillage are the most common weed control methods, and also plastic mulches for horticultural crops. However, the use of these techniques can cause negative effects: intensive tillage increases soil erosion, leading to a loss of fertility [2]; the use of herbicides pollutes the soil, water, food and air [3], and can cause phytotoxicities in young woody saplings or leave residues in aromatic or horticultural crops [4]; plastic mulches are difficult to recycle and have a negative impact on the environment because of its long degradation period [5]. In this context, and with the aim of avoiding these negative effects, hydromulches can be a more environmentally-friendly alternative, considering as such own made pasty mulches that dry out after application.

In this work, we present the coordinated research project “Hydromulches in woody, horticultural crops and urban environments for weed control and water saving which contribute to circular bioeconomy” (HMulchCircle) (ref. PID2020-113865RR), developed in Spain by different research teams from different institutions. The project complements a previous one (ref. RTA-2015-00047-C5), focused on the use of some hydromulches based on by-products derived from the agricultural sector, mixed with a binder and recycled paper paste and applied liquidly on the ground with subsequent solidification, and has the following objectives: 1) Evaluation of mechanized application of the two hydromulch blends that have shown the longest duration and potential in the previous project in different crops. Optimization of the mechanical application, monitoring and study of the effect on weed control. 2) Elaboration of new blends including own-made paper slurry and other lignocellulosic materials that contribute to the circular bioeconomy of each crop and agrifood industry, and characterization of the new blends (on bare soil). 3) Study of the life span of the new hydromulch materials and the weed control capacity in different crops (oak trees, aromatic plants, vegetables, saffron, vineyards, almond trees, fruit trees, forest tree nurseries, public gardens). 4) Effect of the new materials on the growth, productivity and quality of the different crops, and their interaction with the soil properties. 5) Economic, environmental and social assessments of the hydromulch use.

The multidisciplinary nature of the project and its developing in different edapho-climatic conditions and crops will allow solid conclusions to be drawn about the usefulness of the resulting hydromulches within the framework of the circular bioeconomy and a sustainable agriculture.

References:

1. Chauhan, B. S. 2020. Front. , 1:3.

2. Guccione, G.; Schifani, G. 2001. J. Econ. Agric. Environ., 3, 29-36.

3. Monteiro, A.; Santos, S. 2022. Agronomy, 12, 118.

4. Carrubba, A., Militello, M. 2013. Agron. Sustain. Dev., 33, 551-561.

5. Ghatge, S.; Yang, Y.; Ahn, J.H.; Hur, H.G. 2020. Appl. Biol. Chem., 63, 1-14.

Keywords: mulch, weeds, sustainable agriculture.

Acknowledgements: PID2020-113865RR/AEI/10.13039/501100011033 (Spanish Ministry of Science and Innovation).

How to cite: Moreno, M. M., Villena, J., Cirujeda, A., Pardo, G., Pueyo, J., Martín-Closas, L., López-Marín, J., Gálvez, A., and Moreno, C.: Research project: Hydromulches for weed control and water saving in a circular bioeconomy framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11419, https://doi.org/10.5194/egusphere-egu24-11419, 2024.

EGU24-11648 | ECS | Posters on site | SSS9.12

Hydrochar applications to an agroecosystem soil to improve its functionality 

Teresa Di Santo, Rossana Marzaioli, Lucio Zaccariello, Elio Coppola, Giovanna Battipaglia, Simona Castaldi, Maria Laura Mastellone, and Flora Angela Rutigliano

Soil, an indispensable component of natural capital, provides essential ecosystem services like food production, climate regulation, and nutrient cycling. However, agriculture, spanning roughly 33% of Earth's land surface, poses a significant threat to soil integrity and functionality, because it could cause the loss of soil organic matter, pollution and alteration of physical properties. According to the UN 2030 Agenda for Sustainable Development, resilient agricultural practices that progressively improve land and soil quality must be employed. The use of organic fertilizers, such as biochar and hydrochar, deriving from thermochemical treatments of wastes, instead of mineral fertilizers, may have the advantage of restoring the organic C stock in the soil, also helping to mitigate climate change. However, the use of these organic fertilizers at a large scale requires a comprehensive assessment to exclude any potential adverse effects on the soil biotic community which plays a key role in the provisioning of ecosystem services.

Within the interdisciplinary project “CHIMERA”, aimed to assess the hydrochar effects on the soil-plant-atmosphere system, this study evaluated the changes in the chemical and microbial properties after the addition of hydrochar to degraded agricultural soil. A controlled experiment was conducted within a greenhouse using pots (21 cm in diameter, 16 cm in height), each holding 1 kg of soil. Two types of hydrochar, derived from hydrothermal carbonization (250°C and 50 bar in the absence of oxygen) of two distinct sources (residues of thistle - Cynara cardunculus L. - and sewage sludge, labelled as HC and HS, respectively), were introduced into the soil at two different application rates (3 kg m-2 and 6 kg m-2). This resulted in a total of 5 treatments: four with hydrochar and one control without hydrochar addition. Moreover, the experimental design comprised five replicates for each treatment across three exposure times (18, 92 and 146 days). After each exposure time, soil samples were collected and analysed to assess pH, electrical conductivity, cation exchange capacity, total organic carbon content (Corg), extractable organic carbon (Cext), mineralizable carbon (Cmin), total microbial activity (as soil potential respiration, mg CO2-C kg-1 d.w. d-1), microbial biomass (Cmic), microbial percentage of total Corg (Cmic%Corg), quotient of mineralization (qM, Cmin%Corg) and metabolic quotient (qCO2, CO2-% Cmic d-1).

The results showed no negative effect of hydrochar on considered variables, while positive effects on some of them were found. The response of soil variables to the addition of hydrochar depended on exposure time, dose and type of hydrochar. Generally, better results were recorded at 92 days of exposure, especially in treatment with thistle-derived hydrochar at the highest dose. Data suggest that hydrochar may be regarded as a promising soil fertilizer, also considering other results from CHIMERA project showing positive effects on the growth of Populus alba L. and, limited to thistle-derived hydrochar, also a reduction of N2O emission from soil, compared to control. However, further studies are needed to ascertain whether the positive effects persist in the long term and whether they are also confirmed at the field scale and for other feedstock types.

How to cite: Di Santo, T., Marzaioli, R., Zaccariello, L., Coppola, E., Battipaglia, G., Castaldi, S., Mastellone, M. L., and Rutigliano, F. A.: Hydrochar applications to an agroecosystem soil to improve its functionality, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11648, https://doi.org/10.5194/egusphere-egu24-11648, 2024.

EGU24-12732 | Orals | SSS9.12

Utilization of hydrolyzed feather meal and chicken manure treated with micro-thermal method as recycled organic fertilizer 

Jukka Kivelä, Henrik Lindegren, Pirjo Niemelä, and Mika Tuomola
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The by-products of egg production are one of the most usable raw materials for organic fertilizer. Currently they are not used as effective fertilizers. The most of chicken manure is used as fertilizer on egg production farms in combination with mineral fertilizers. Such utilization of by-products is causing significant local environmental problems. The feathers are delivered to rendering companies which are in many cases mixing them with other animal by-products. However, then it is not possible to get optimal benefit from this high value protein.

There have been several projects focusing on recycling of food industry by-products. We have processed chicken manure (Fertilex Ltd) with micro thermal method developed by DTS Finland Ltd. At the first time we got chicken manure with about 4 % total nitrogen but in later trials it was possible to get a product which contained 6-7 % total N (Canasta project 2021-2023).

In another project (Honkajoki Ltd) feather meal was hydrolyzed and it contained 14,2 % of total nitrogen. Previous studies have shown that 90 % of feather dry weight consists of crude keratin protein, and feathers contain about 15 % total N (Papadopoulos et al., 1985, 1986). Keratin N is not usable as nitrogen fertilizer because keratin is a stable protein.

Pot trial in research greenhouse

We prepared a pot trial to find out what kind of fertilizers these developed products are. The treatments were hydrolyzed feather meal, meat bone meal (MBM), chicken manure pellets, DTS chicken manure and mineral fertilizer as control fertilizer. Hydrolyzed feather meal gave 80 % yield of mineral fertilizer which was as good as with MBM. The yield of DTS chicken manure was 5 % less compared to MBM but it was better than pelletized chicken manure.

In this trial we were not able to use mixture of DTS chicken manure and hydrolyzed feather meal but if it is possible to make this kind of product. It would be suitable fertilizer at least for organic farming. Consequently, recycling of egg production nutrients becomes much more efficient.

These projects were funded by the Programme for nutrient recycling of the Ministries of Agriculture and Forestry and Environment in Finland as well as Honkajoki Ltd.

 

How to cite: Kivelä, J. et al: Utilization of hydrolyzed feather meal and chicken manure treated with micro-thermal method as recycled organic fertilizer, EGU General Assembly 2024, Vienna, Austria, 14–19 April 2024, EGU24-,

How to cite: Kivelä, J., Lindegren, H., Niemelä, P., and Tuomola, M.: Utilization of hydrolyzed feather meal and chicken manure treated with micro-thermal method as recycled organic fertilizer, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12732, https://doi.org/10.5194/egusphere-egu24-12732, 2024.

EGU24-13625 | Posters on site | SSS9.12

BIOSOLID FROM SEWAGE TREATMENT PLANT INCREASES THE GROWTH OF JACK BEAN (Canavalia ensiformis) IN A COPPER CONTAMINATED SOIL 

Andressa Silveira, Fernanda Tamiozzo, Natielo Santana, Rodrigo Jacques, Bárbara Clasen, and Edivan Schein

Copper (Cu) mining have been carried out for more than a century in the Minas do Camaquã region, southern Brazil. Currently, this site has an extensive area impacted by the disposal of tailings and the soil has high levels of Cu. As a result of this contamination, the site has little or no vegetation cover, increasing the risk of other environmental compartments being affected. Phytoremediation can be used to mitigate this problem, and its efficiency can be enhanced by the use of organic amendments. Therefore, this study sought to evaluate the effect of sewage biosolids on the development of jack bean (Canavalia ensiformis) in a copper-contaminated soil after the cultivation of black oats (Avena strigosa). A biosolid obtained from the sludge of an aerobic domestic sewage treatment system was used in this study. The pots with soil from the area impacted by copper mining tailings (739 mg kg-1 of Cu Mehlih) received increasing doses of biosolid (0, 90, 180, 360, 720 and 1440 kg ha-1 of N) and black oat was grown in a greenhouse. After 75 days black oats were harvested, and then jack bean were cultivated in the same soil, using the same treatments of the black oat, but without new addition of biosolid. The jack bean was harvested at flowering to determine dry mass and copper content in tissues. The dry mass of the shoot increased with the addition of biosolid, but no significant difference was observed between treatments for dry mass of the roots. The highest dose (1440 kg ha-1 of N) promoted the highest dry mass production of the shoots (20 g pot-1), but did not differ (p < 0.001) from doses of 180, 360 and 720 kg ha-1 of N. In the control treatment (0 kg ha-1 of N) the plant presented less than 8 g pot-1of aerial biomass. The highest levels of Cu in shoot biomass were observed in the intermediate doses (180 and 360 kg ha-1 of N) and in the control treatment (average of 22.11 mg kg-1), differing (p < 0.05) only from the dose of 1440 kg ha-1 of N (12.42 mg kg-1). In the roots, no significant difference (p = 0.525) in Cu content was observed. Thus, our study indicates that intermediate doses (180 and 360 kg ha-1 of N) of biosolids promoted plant growth similar to the higher doses and increase the Cu contents in the shoot biomass. More studies must be carried out to evaluate the effects of biosolids on other soil and plant parameters, but our results indicate that the use of biosolids can be an alternative for increasing vegetation cover in phytoremediation strategies for soils contaminated by Cu mining tailings.

How to cite: Silveira, A., Tamiozzo, F., Santana, N., Jacques, R., Clasen, B., and Schein, E.: BIOSOLID FROM SEWAGE TREATMENT PLANT INCREASES THE GROWTH OF JACK BEAN (Canavalia ensiformis) IN A COPPER CONTAMINATED SOIL, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13625, https://doi.org/10.5194/egusphere-egu24-13625, 2024.

EGU24-15237 | Posters on site | SSS9.12

Effect of Multi-Walled Carbon Nanotubes on the Carbon and Nitrogen Cycling Processes in Saline Soil 

Yutian Zuo, Wenzhi Zeng, Chang Ao, and Guoqing Lei

 Soil salinization is a pressing issue that needs to be addressed in current agricultural production. In this study , we utilized novel materials, unfunctionalized multi-walled carbon nanotubes (MWCNT) and functionalized multi-walled carbon nanotubes (MWCNT-OH), to explore the effects of soil carbon and nitrogen cycles in saline soil. We set up four treatments, which were exposed to two exposure doses of 1 g/kg and 1 µg/kg and two MWCNT types of functionalized MWCNT-OH and unfunctionalized MWCNT. Our results demonstrate that exposure of saline soil to 1 g/kg functionalized MWCNT-OH significantly increased the soil inorganic nitrogen (p < 0.05), while also promoting the soil microbial biomass. This exposure can also potentially enhance greenhouse gas emissions from saline soil. Moreover, exposure to MWCNTs significantly increased the proportion of Actinobacteria and Proteobacteria, two dominant phyla (p < 0.05), which in turn improved their contribution to the carbon and nitrogen cycling processes within saline soil. High exposure dose treatments (1 g/kg) significantly increased the abundance of functional genes associated with carbon metabolism, carbon fixation, methane metabolism, and nitrogen cycling processes within saline soil. In contrast, low exposure dose treatments (1 µg/kg) had no significant effect on the abundance of functional genes related to nitrogen cycling, but significantly increased the abundance of special functional genes related to carbon cycling. Redundancy analysis revealed that the microbial community composition within saline soil was significantly impacted by the soil total carbon, total nitrogen, and nitrate nitrogen content. Furthermore, it was observed that over 80% of the carbon and nitrogen cycling processes within the saline soil were contributed by the dominant phyla. In summary , our research confirms the potential applicability of MWCNTs within saline soil. Notably, exposure of saline soil to 1 g/kg functionalized MWCNT-OH exhibited the most significant promoting effect on the carbon and nitrogen cycles.

How to cite: Zuo, Y., Zeng, W., Ao, C., and Lei, G.: Effect of Multi-Walled Carbon Nanotubes on the Carbon and Nitrogen Cycling Processes in Saline Soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15237, https://doi.org/10.5194/egusphere-egu24-15237, 2024.

EGU24-15577 | ECS | Posters virtual | SSS9.12

Impact of organic soil amendments on heavy metal losses and nutrient cycling –  medium-sized controlled lysimeter experimental assessment 

Nina Đukanović, Lutz Weihermuller, Jens Kruse, Nina Siebers, Slaven Tenodi, Marijana Kragulj Isakovski, Roland Bol, and Snežana Maletić

Heavy metals accumulate due to various human activities in sediments thereby negatively impacting on aquatic ecosystems and potentially via food chain transfers harming human health. To maintain the hydraulics of water bodies heavy metal (HM) polluted sediments are frequently simply dig out of the riverbeds and channels, and subsequently dumped on sites in their vicinity. We studied the ability of such clay and organic rich ‘waste’ sediments to acts as amendments for marginal soils. Their added organic matter could play a crucial positive role in soil fertility, nutrient cycling, and carbon sequestration.

The introduction of organic amendments can either diminish or mobilize heavy metals when applied to marginal soils. Lysimeters were filled with marginal sandy soil collected from the Danube riverbanks in Novi Sad, Serbia, ensuring it was free of HM contamination. Six distinct organic soil amendments (OSA) were introduced to the lysimeters: i) biochar, ii) sludge, iii) compost, iv) biochar + sludge, v) biochar + compost, and vi) biochar + sludge + compost.

The sludge utilized is derived from aquatic sediment in the Begej Canal, Serbia, known for its heavy pollution. Among others, this study aims to assess whether this specific sludge type can serve as a viable soil amendment rather than being relegated to landfill disposal. The compost utilized originated from green waste in Novi Sad, while the biochar was produced from Miscanthus, a C4 plant feedstock, at 550°C at the Technical University Aachen. Both the OSA and sandy soil underwent chemical and physical characterization before application. The maximum added amendments varied from 1 to 5% (w/w), depending on the OSA type.

All probes were established at Faculty of Science, University of Novi Sad, in triplicates, featuring lysimeters with a height of 435 mm and a diameter of 180 mm. The results of heavy metal leaching data under different OSAs will be presented at the meeting, highlighting key findings and conclusions. Additionally, we will discuss the role of water event-driven transport in the overall process.

Acknowledgement: "Funded by EU grant #101059546"

How to cite: Đukanović, N., Weihermuller, L., Kruse, J., Siebers, N., Tenodi, S., Kragulj Isakovski, M., Bol, R., and Maletić, S.: Impact of organic soil amendments on heavy metal losses and nutrient cycling –  medium-sized controlled lysimeter experimental assessment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15577, https://doi.org/10.5194/egusphere-egu24-15577, 2024.

EGU24-16903 | ECS | Posters on site | SSS9.12

Aging of biochar in a Cambisol for 13 years under organic farming field conditions affects its chemical structure but still shows positive impacts on plant growth 

Tamara Apostolović, Álvaro Fernando García Rodriguez, Snežana Maletić, Bruno Glaser, and Heike Knicker

Soil deterioration due to excessive fertilization and climate change has adverse effects on crop growth globally. In order to enhance soil fertility, application of organic soil amendments has gained importance. One of them represents biochar which is recognized as a sustainable agricultural practice with significant benefits for soil health as it bolsters fertility, enhances nutrient retention and soil structure while sequestering carbon on a long-time scale. However, during aging biochar has been shown to change its properties. Knowledge about those alterations and changes in performance as soil amendment is still scarce. Therefore, our research aimed to compare the impact of freshly added biochar to that of biochar and co-composted biochar having been allowed to age under natural organic farming field conditions for 13 years in a Cambisol on soil properties and the development of Lactuca sativa L. var. The plants were grown in pot experiments for 9 weeks under controlled greenhouse conditions. Compared to the soil freshly amended with biochar (5.93%), the organic matter content of the soils with the aged biochar and aged co-composted biochar was lower (4.76% and 4.91%, respectively) suggesting that some of the biochar was lost during 13 years of aging. However, their SOM content was still significantly higher than in the untreated control soil (3.62%), indicating a positive long-term effect of biochar treatment on soil carbon sequestration. Solid-state 13C NMR data showed significantly higher aromaticity of the soil amended with fresh biochar compared to the control soil, which can be directly linked to the polyaromatic nature of biochar. As indicated by the 13C NMR spectra, aging of biochar resulted in a relative loss of aromatic structures and a relative increase of O-alkyl C and alkyl C confirming the oxidation of biochar with ongoing aging. Addition of fresh biochar decreased the relative amount of available nitrogen forms (nitrates and ammonia) although its contribution to the soil increased with aging. Even after aging, biochar treatments resulted in a larger production of fresh and dry biomass if compared to the control soil. We noted that co-composted biochar led to greater photosynthesis indexes (SPAD and QY), better water use efficiency (WUE), nitrogen use efficiency (NUE) and phosphorus use efficiency (PUE). In addition, it increased the nutrients contents of the plants. This study also explored the multiple positive and negative interactions between different types of biochar addition as organic soil amendments and plant physiological traits. For this purpose, statistical analysis was performed as analyses of variance (ANOVA). Principal Component and correlation analysis (PCA) were also tested. The results of this study will help in understanding the complex relationships between soils, amendments, and plants, and as such are vital for optimizing soil health and achieving higher crop yields through organic amendments.

 

Acknowledgements: Funded by the European Union. Grant agreement No. 101059546, María Rocio Reinoso and Marta Velasco-Molina are thanked for their technical help in the laboratory.

How to cite: Apostolović, T., García Rodriguez, Á. F., Maletić, S., Glaser, B., and Knicker, H.: Aging of biochar in a Cambisol for 13 years under organic farming field conditions affects its chemical structure but still shows positive impacts on plant growth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16903, https://doi.org/10.5194/egusphere-egu24-16903, 2024.

EGU24-18420 | ECS | Orals | SSS9.12

Evaluating the Impact of Global Warming on Industrial Crops in Africa  

Temitope S. Egbebiyi, Chris Lennard, and Philip Mukwenha

Global warming will significantly affect agricultural sector in Africa but its implication on the future cultivation of industrial crops is still unknown. The present study examines the impact global warming on industrial crops (Soyabean, Coffee and Cotton) suitability and planting season in Africa under the new Shared Socio-economic Pathways (SSPs). Using the multi-model ensemble datasets from the CMIP6 simulations for SSP245 & 585 for the historical (1981-2010), near future (2035-2064) and end of century (2070-2099) periods as input into Ecocrop, a crop suitability model, we examine the impact of climate change on the suitability and planting season of industrial crops in SSA owing to their economic importance to the region. Our result shows Soyabean is most suitable across most part of the region in comparison to Coffee and Cotton with suitability index above 0.5 except south of 20oS in southern Africa and in the Sahel zone (north of 14oN) over the historical period. The impact of climate change shows increase,10 and 20% in suitable area for Soyabean over East Africa while no significant is expected change for Cotton in the near future and end of century respectively. In contrast, a decrease 15% and 25% in suitable/ cultivated area for Arabica coffee may be expected in the near future and end of century respectively over West and Central Africa. In addition, no change in planting season is expected over the two periods and SSPs for Soyabean and Cotton. However, a 2-month early planting for arabica and robusta coffee may be expected over West and southern Africa respectively by the end of century with SSP585.  Also, a 1-month delay in the planting season may be expected for robusta coffee over West and Central Africa by the end of century under ssp585. The study will assist to improve our understanding on the response of industrial crops to the impact climate change under different SSPs in Africa and its resultant effect on economy in sub-Saharan Africa. It will also help inform policy maker in their decision making of adaptation strategies to improve suitable areas for the cultivation of the crops to enhance the economy of the region.

 

Keywords: Industrial crops, Ecocrop, Global warming, Africa

How to cite: Egbebiyi, T. S., Lennard, C., and Mukwenha, P.: Evaluating the Impact of Global Warming on Industrial Crops in Africa , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18420, https://doi.org/10.5194/egusphere-egu24-18420, 2024.

EGU24-18851 | Posters on site | SSS9.12

Enhancing Sorption and Biodegradation: The Influence of Inoculated Biochar on the Transport of Organophosphorus Pesticides in Sandy Soil 

Marijana Kragulj Isakovski, Irina Jevrosimov, Dragana Tamindžija, Tamara Apostolović, Srđan Rončević, and Snezana Maletić

This study investigates how soil enriched with carbon-rich materials, such as biochar, influences the sorption and biodegradation capabilities of organophosphorus pesticides (Fenthion, Fenitrothion, Parathion Methyl) under nonequilibrium conditions. Additionally, experiments were conducted to enhance the biodegradation potential of biochar from Miscanthus×giganteus by introducing bacteria capable of degrading organophosphorus pesticides (OPPs).

Transport experiments were carried out in stainless-steel columns (4 cm diameter, 20 cm length) filled with soil amended with biochar previously inoculated with a biofilm of vegetative cells from the Bacillus megaterium BD5 strain. To assess the impact of inoculated biochar on pesticide transport, 0.5% of this adsorbent was added to the total soil mass in the column. Thiourea was included as a tracer at a concentration of approximately 4 mg/L. Pesticide solutions were pumped through the column, and eluates from the outlet were collected at various time intervals, and analyzed for pesticide concentrations using GC/MS Agilent 7890 A/5975C.

Data analysis involved the use of a mathematical transport model by solving the advection-dispersion equation (ADE), yielding transport parameters (retardation, Rd, and biodegradation, λ) and breakthrough curves. The retardation coefficient for investigated compounds ranged from Rd=40-100, with increasing order of Parathion-methyl < Fenthion < Fenitrothion. Biodegradation (λ) of the compounds ranged from λ=0.2-3.3, increasing in the same order. No clear correlation was observed between the octanol-water partition coefficient (Kow), retardation, and biodegradation, indicating that hydrophobicity alone did not solely determine sorption and transport characteristics under specific experimental conditions.

In summary, introducing inoculated biochar likely contributes to the simultaneous adsorption of organic compounds onto the added adsorbents within the porous material and biosorption onto the inoculated biochar. Generally, adding inoculated carbon-based materials to contaminated sediments shows potential as a remediation technique, inhibiting pollutant leaching to groundwater and facilitating immobilization.

 

Keywords: transport, biochar, organophosphorus pesticides, biodegradation

Acknowledgment

Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Executive Agency (REA). Neither the European Union nor the granting authority can be held responsible for them. Grant agreement No. 101059546

How to cite: Kragulj Isakovski, M., Jevrosimov, I., Tamindžija, D., Apostolović, T., Rončević, S., and Maletić, S.: Enhancing Sorption and Biodegradation: The Influence of Inoculated Biochar on the Transport of Organophosphorus Pesticides in Sandy Soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18851, https://doi.org/10.5194/egusphere-egu24-18851, 2024.

EGU24-20921 | Posters virtual | SSS9.12

Biochar Potential from Wildfire Crisis Wastes and Woody Energy Crop Wastes   

Maggie Davis and Chad Hellwinckel

As the United States charts a course towards net-zero targets, the U.S. Department of Energy (USDOE) will release the latest biomass assessment, the Billion-ton 2023 (BT23) report. These reports provide an advancement in the understanding of quantity, spatial distribution, and economic accessibility of biomass resources in the U.S. Building on this work, we present the potential for biomass resources to contribute to biochar production that can be used for agricultural soil amendments, as well as biomass used for energy and bioproducts. Through modeling using a partial-equilibrium linear programming model, we evaluate biomass resources on agricultural land. With producer responses to biochar market incentives and sustainability considerations, residues from these biomass resources can be leveraged for biochar boosting the sustainability of the energy crop system. This research also introduces the potential for biochar from Wildfire Crisis Strategy (WCS) generated biomass, an unprecedented effort by the U.S. Forest Service (USFS) to make wildfire-prone forests more resilient. We estimate biomass availability resulting from thinning and fuel reduction treatments on western landscapes and present this research as a potential case study for sourcing biochar material as a soil amendment. Beyond energy generation, the focus of this work is on co-production of bioproducts and creating a pathway for payments that contribute to more sustainable agricultural systems. This dual-use strategy not only fortifies the development of renewable energy systems but also accentuates the importance of resilience by incorporating biochar to enhance soil health and carbon sequestration.

How to cite: Davis, M. and Hellwinckel, C.: Biochar Potential from Wildfire Crisis Wastes and Woody Energy Crop Wastes  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20921, https://doi.org/10.5194/egusphere-egu24-20921, 2024.

EGU24-21710 | Orals | SSS9.12

The effects of plant biostimulants application on soil microbial activity and nutrient uptake under field conditions in Denmark 

Mesfin T. Gebremikael, Thayna Mendanha, Merete Edelenbos, and Hanne L. Kristensen

Plant biostimulants can play significant roles in organic agriculture by stimulating natural processes that enhance nutrient availability and plant uptake, improve abiotic stress tolerance, and boost overall plant growth and development. Despite their roles, data on the efficacy of biostimulants in organic agriculture is limited, particularly in Scandinavian countries such as Denmark. We evaluated the efficacy of 10 different biostimulants on organic snack carrots and potatoes in Denmark for two years.

A factorial experimental design was set up under field conditions for two years at two locations characterized by sandy clay (2021) and sandy (2022) soil textures at the experimental stations of Aarhus University in Denmark. The two factors were nitrogen levels (100% and 50% of recommended nitrogen) and biostimulants of different origins, namely, microbial origin (Proradix and Vesta), plant extracts (Crop-setand Combi-set), seaweed extract (Acadian), humic and fulvic acids (Humifirst). The biostimulants were applied at recommended rates, time, and application methods per the guidelines indicated on the product's label. Soil samples were collected to 0-25 cm depth a week before harvest and after removing the upper ground biomass. Two soil enzymes, dehydrogenase (DHA) and β-glucosidase (BGA), were selected as indicators of soil microbial activities. Macro (N, P, K, S, Ca, Mg) and micro (Fe, Mn, B, Cu and Zn) nutrients in the soil and the potato tubers were analyzed to evaluate the effects of biostimulants on nutrient use efficiency indices such as nutrient uptake.

There was no significant interaction effect of the biostimulants and nitrogen levels on both enzymes and most of the plant nutrient uptakes at the two locations. The 100% nitrogen level resulted in a significantly (p<0.05) higher DHA than the 50% nitrogen level only in the sandy soil. The biostimulants did not significantly change the DHA and BGA in sandy clay and sandy soil. Some of the biostimulants significantly increased (p<0.05) nutrient uptake for all the nutrients except Fe in sandy soil. However, significant effects (p<0.10) of biostimulants were observed only in P and Mg uptake in the sandy clay texture soil. The results indicate that the effect of biostimulant application on microbial activities and plant nutrient uptake depends on the type of biostimulant and soil texture used in organic potato production in Denmark.

How to cite: Gebremikael, M. T., Mendanha, T., Edelenbos, M., and Kristensen, H. L.: The effects of plant biostimulants application on soil microbial activity and nutrient uptake under field conditions in Denmark, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21710, https://doi.org/10.5194/egusphere-egu24-21710, 2024.

The biorefinery and blue bioeconomy project (BioResque) for treating both fresh and environmentally sedimented industrial cellulosic side streams was started in December 2023. It is a continuation for our earlier work for circulating all forest industry process residues into green chemicals, energy gases and organic soil improvement. In this effort microbial communities are instigated for process improvement and ecosystem engineering goals. For the fertilization uses zero fibres and other organic residues and biomasses could be microbiologically upgraded by a standardizable process. The resulting materials could be applied for establishing and complementing fertile soils, which is the main goal of sustainable soil managements.

How to cite: Hakalehto, E., Jääskeläinen, A., Hakalehto, J.-P., and Kivelä, J.: Cellulosic Factory Side Streams and Deposits as Organic Soil Improvement Resources in an Outlined Bioprocess Scheme - BIORESQUE Project of the EU CircInWater Program, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22062, https://doi.org/10.5194/egusphere-egu24-22062, 2024.

Human activities frequently cause soil degradation, altering its multifunctionality and therefore its capacity to provide ecosystem services. Urban soil degradation notably results in high bulk densities due to trampling and machine traffic, loss of biodiversity, and lack of organic matter. The anthropic and ecological functions of soils can then be dysfunctional.

One of the major pillars in maintaining the balance of these ecosystems are the living organisms that populate them. Through their diverse lifestyles, soil fauna plays an active role in soil functions at different scales, through the prism of their functional traits.

We would like to promote the development of “pedofauna engineering” as a tool for the ecological reclamation of moderately degraded urban soils.

A conceptual framework has been created, linking functional traits of interest to soil fauna in the water cycle regulation function. We considered two sub-functions (infiltration and retention of water) and four soil processes in relation to them (creation of porosity, bioturbation, aggregation and organic matter fragmentation). To assess the success of reclamation through functional traits, it also appears that residual activities (e.g. burrows, biogenic aggregates) of soil organisms could be considered as relevant indicators of the ecological processes.

In order to test these postulates, we have selected a list of functional traits and attributes of interest in relation to soil compaction. Three species of organisms carrying the traits of interest (Lumbricus terrestris anecic worm, Eisenia fetida epigeal worm and Porcelio scaber isopod) were introduced into cosmes with urban park soil, compacted at 1, 1.3 and 1.45 g cm-3.

Our results demonstrate that soil organisms with their related functional traits and attributes "Strong capacity to dig burrows", "Strong capacity to move in the soil" and "Body length between 12 and 22 cm", led to the creation of macroporosity and enhance the infiltration of water into the soil.

This conceptual framework is a work in progress but can surely provide a deeper and better understanding of the who and how of soil fauna's involvement in soil multifunctionality.

How to cite: Caron, L., Auclcerc, A., and Séré, G.: Reclamation of moderately degraded urban soils: creation of a cognitive model to link soil organisms’ functional traits to soil processes & functions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-274, https://doi.org/10.5194/egusphere-egu24-274, 2024.

Globally, excavated soils are the biggest construction wastes and are simultaneously the largest carbon repositories in terrestrial ecosystems. As urbanization continues to drive underground development, handling excavated soils has gained growing importance. The reuse or transfer of excavated soils has direct and long-term effects on regional and cross-border soil carbon dynamics. Soil carbon fluxes, the second largest in terrestrial ecosystems, play a crucial role in regulating the global carbon cycle. However, quantifying carbon fluxes in excavated soils and technologies to mitigate these overlooked carbon emissions have yet to emerge in the construction sector. In our study, we quantified annual soil carbon fluxes (CO2 and CH4) at varying soil capping depths (0, 20, and 40 cm) following the reclamation of excavated soils. Additionally, we investigated the impact of biochar, a commonly utilized agricultural amendment, on soil carbon fluxes. Our findings revealed that implementing a 40 cm soil capping depth led to a substantial 20.52% reduction in CO2 flux (from 11.46 to 8.87 tonC ha-1 yr-1) and a substantial 79.58% decrease in CH4 flux (from 0.219 to 0.045 tonC ha-1 yr-1). Furthermore, the incorporation of biochar resulted in a significant reduction in annual CH4 flux, with reductions of up to 28.62% (from 0.219 to 0.157 tonC ha-1 yr-1), while no significant differences were observed in annual soil CO2 flux. In summary, our study offers essential insights into the impact of excavated soils on regional carbon cycles and proposes viable strategies for mitigating excessive soil carbon emissions within the construction sector.

Keywords: urban soils, excavated soils, soil CO2 flux, soil CH4 flux, soil capping, biochar

How to cite: Bae, J., Jeong, M., and Yoo, G.: Large but overlooked carbon fluxes (CO2 and CH4) from excavated soils by urban development: Magnitudes, causes and possible mitigation strategies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2414, https://doi.org/10.5194/egusphere-egu24-2414, 2024.

Urban soils are pivotal to environmental health and urban ecosystems. They underpin green spaces, assist in pollution filtration, support biodiversity, and play a key role in water management. These functions are vital for sustainable urban development and the well-being of city residents. However, urban soil science faces significant challenges: a lack of comprehensive data, limited public awareness of soil's ecological roles, and difficulties in data collection within diverse, densely built urban environments. This presentation will demonstrate how citizen science initiatives can bridge these gaps in urban soil research. By leveraging community efforts, extensive soil data can be gathered across various urban landscapes. The goal is to engage and educate communities in soil data collection and monitoring, thereby enhancing public understanding and involvement in urban soil health. A multi-faceted approach, including interactive workshops, user-friendly mobile applications, and online resources, will be employed to educate and train citizens in soil science basics and data collection techniques. These strategies aim to simplify complex soil science concepts into engaging, easily understandable content, complemented by hands-on training in using soil testing kits and data recording tools. The integration of citizen science in urban soil research offers dual benefits: advancing soil science through expanded data collection and analysis, and enhancing public engagement in scientific endeavors. Citizen involvement in soil data collection increases the quantity and quality of soil data, covering a wider range of urban areas and incorporating diverse observations and localized knowledge from community members. The presentation will introduce the "Urban Soil Guide: Field and Lab Manual," a newly released comprehensive resource designed for both educational and general use. This manual provides practical guidance for understanding, testing, and managing urban soils, bridging the gap between theoretical knowledge and real-world application. Additionally, the role of social media in enhancing citizen science projects on urban soil research will be discussed. This includes strategies for community building, experience sharing, and the best platforms for data visualization and sharing results.

How to cite: Paltseva, A.: Empowering Communities: The Future of Urban Soil Science Through Citizen Science, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3217, https://doi.org/10.5194/egusphere-egu24-3217, 2024.

EGU24-4736 | Posters on site | SSS9.13

Investigation of Water Flow in Single-Layer and Multi-Layered Constructed Technosols of Green Roof 

Michal Snehota, Martina Sobotkova, Marek Petreje, Petra Heckova, Razbar Wahab, Barbora Rybova, and Vladimira Jelinkova

The performance of constructed soil systems with multiple layers for green roof applications was evaluated in this study. These systems may have advantages over single-layered soils, such as reduced evapotranspiration, increased infiltration, contaminant removal, and plant support. However, the water and solute fluxes across the interfaces between different layers are poorly understood. An experimental set-up of 18 rhizoboxes with two and four-layered soil systems was built on the roof in an open-air setting. Two green roof substrates were used to create the layers. The water balance components were measured to assess the hydraulic functioning of the soils. Invasive and noninvasive methods were applied to investigate the phenomena of capillary barrier, finger flow, and air entrapment in the multi-layered soils. Retention curves of substrates were determined. A modeling approach for water and solute fluxes in natural soils was adapted to multi-layered constructed soils. The results of the first six months of monitoring are presented and discussed. The study should provide valuable insights into the design and management of green roofs with multi-layered soils.

How to cite: Snehota, M., Sobotkova, M., Petreje, M., Heckova, P., Wahab, R., Rybova, B., and Jelinkova, V.: Investigation of Water Flow in Single-Layer and Multi-Layered Constructed Technosols of Green Roof, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4736, https://doi.org/10.5194/egusphere-egu24-4736, 2024.

EGU24-6776 | Orals | SSS9.13

Mapping soil multifunctionnality for urban planning and development: from research to "no net land take"  

Cecile Le Guern, Benjamin Deslandes, Clémentine Duvigneau, Mathilde Basuyau, Antoine Lemot, Bertrand Laroche, and Philippe Branchu

The French R&D MUSE project developed a methodology to map the potential multifunctionnality of unsealed soils based on existing data at national scale, in order to consider this information in urban planning. This method gives a partial idea of soil health. The data on rural areas allow mapping 4 ecological soil functions: potential of carbon storage, water storage, agronomic potential, and biodiversity reservoir. The lack of soil maps on urban area conducted to propose a simplified approach. The methodology was developed in collaboration with 3 pilot territories. The aim of this presentation is to establish feedback on the application of the methodology on various geographical and pedo-climatic contexts.

The analysis is carried out on more than 10 cases including Rennes Métropole, Ris-Orangis and Savoie Métropole, by checking the objectives of the application, the appropriation by operators and the adaptations proposed.

The feedback shows the ability to identify zones to be preserved, developed or disartificialised by crossing with other data. More detailed soil maps contribute to gain precision and are mandatory to design development projects. New methodological developments are proposed also to map soil multifunctionnality in urban areas. The integration of soil quality to reach the "no net land take" target is also in progress. It takes into account a moderation of the potential soil functions by knowledge on pollution risks and remediation projects.

The MUSE methodology is getting more and more applied in France, although its application needs some technical skills on soils and geomatics. In this frame, an automation script was developed to standardise the production of the 4 ecological soil function maps. It can be applied at various scales, according to the precision of the available data. The feedback underlines the need to wider characterise urban soil and to bank further the acquired data to improve the knowledge on urban soils. 

How to cite: Le Guern, C., Deslandes, B., Duvigneau, C., Basuyau, M., Lemot, A., Laroche, B., and Branchu, P.: Mapping soil multifunctionnality for urban planning and development: from research to "no net land take" , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6776, https://doi.org/10.5194/egusphere-egu24-6776, 2024.

EGU24-7583 | ECS | Posters on site | SSS9.13

X-ray study of soil structure changes in Constructed Technosol of the layered system of bioretention cells 

Petra Hečková, John Koestel, Ales Klement, Radka Kodesova, and Michal Snehota

Constructed Technosols play an important role in urban hydrology e.g. in the functioning of green roofs and stormwater bioretention cells. Water infiltration, colloid transport, and heat transport are affected by changes in pore system geometry particularly due to the development of macropores and clogging by particles. The aim of the study is to relate changes in bioretention cell performance to the structural changes of soils at the microscale by invasive and noninvasive methods. Noninvasive visualization method of X-ray microtomography was used to investigate soil of the biofilter in terms of structure development, pore-clogging and pore geometry deformations.

Two identical bioretention cells were established in December 2017. The first bioretention cell (BC1) collects the stormwater from the roof of the nearby experimental building (roof area 38 m2). The second bioretention cell BC2 is supplied from a tank using a controlled pump system for simulating artificial rainfall. Each BC is 2.4 m wide and 4.0 m long. Subsurface of the bioretention cell is formed by biofilter (Constructed Technosol), sand filter and a drainage layer. The 30 cm thick biofilter soil mixture is composed of 50% sand, 30% compost, and 20% topsoil. Bioretention cells are isolated from the surrounding soil by a waterproof membrane. The regular soil sampling program was initiated in 2018 in order to visualize and quantify the soil structure and internal pore geometry of samples. Undistributed samples were collected from the surface of the filter layer from each BC. The aluminum sampling cylinders had an internal diameter and height of 29 mm. Batches of 12 samples were collected on June 5, 2018 (7 months after establishment), November 1, 2018 (12 months after establishment), May 5, 2019 (18 months after establishment), June 29, 2019 (22 months after establishment) and the last batch of samples on June 18, 2020 (31 months after establishment) from each BCs. Those collected samples were scanned by CT imaging at the water content equilibrated at -330 hPa.

Analyses of pore network morphology were performed on the segmented 3D images of samples. Macroporosity, pore thickness, pore connection probability, critical diameter and Euler-Poincare density were determined to understand pore space in the biofilter. Furthermore, porosity, dry sample bulk density and volumetric water content at pressure head representing a field capacity of -330 hPa were measured on all samples.

During the first year, the macroporosity decreased in both BCs due to soil consolidation. A significant correlation was found between macroporosity and connection probability, as well as between macroporosity and critical diameter. Pore thickness analysis revealed that the most represented pore fraction during the three years was 80-310 μm in size. Results of the study show that short term consolidation was followed by gradual development of macropore system in Constructed Technosol of bioretention cell. The biofilter exhibited optimal conditions for plant growth, particularly in BC1 with natural water inflow. There was no significant drying in the biofilter layer in BC1 and the volumetric water content ranged from 0.2 to 0.4.

How to cite: Hečková, P., Koestel, J., Klement, A., Kodesova, R., and Snehota, M.: X-ray study of soil structure changes in Constructed Technosol of the layered system of bioretention cells, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7583, https://doi.org/10.5194/egusphere-egu24-7583, 2024.

EGU24-7673 | ECS | Orals | SSS9.13

Biodiverse dual-purpose wetland-green rooftop design based on recyclates 

Marek Petreje, Barbora Rybová, Petra Hečková, and Michal Sněhota

A circular economy-based hybrid green roof system and green roof substrate was developed and tested to reduce the environmental impact of using natural resources such as water and components of substrates based on common primary materials. Two case studies and laboratory analysis were conducted to assess the performance of green roof substrate consisting of recycled crushed brick-based demolition waste and biochar from pyrolyzed sewage sludge. Substrates were tested for their hydro-physical properties such as maximum water capacity, retention curves, bulk density, grain size and pH and suitability for vegetation growth.

The purpose of first case study, which involved a green roof of 7×5 m2, was to test two newly developed circular substrates in conditions of real green roof and to compare it with standard, commercially available, substrate. The new substrates differed in the amount of pyrolyzed sewage sludge biochar they contained (9.5 vol. % for one and none for the other), but both contained large proportion of crushed brick (37.5 vol. %). The impact of the pyrolyzed sewage sludge was the main focus of the evaluation. At the same time, the changes in hydrophysical characteristics (retention curves, hydraulic conductivity, grain size) over time were evaluated.

Second case study was conducted on two raised beds to test the newly developed substrates in the context of the novel solution combining an extensive green roof and rooftop constructed wetland that uses pre-treated grey water. This system is called Hybrid green roof (HGR). The viability of a hybrid green roof system that uses greywater for irrigation was evaluated by measuring water balance, testing water samples from different sections of the experimental beds, and monitoring temperature and water content along the height of the bed layers. The hybrid green roof system has a constructed wetland section that treats the greywater before it reaches the green roof.

Extensive green roof areas of experimental beds in both studies were planted with Sedum spp. Vegetation in both case studies is thriving. The biochar apparently provides nutrients for the plants, which results in more vigorous growth on the substrates containing biochar. In case of HGR, the nutrient (phosphorus and nitrogen) levels in the leachate from the test beds were relatively low, because the irrigation water goes directly to the drainage layer and does not wash out the nutrient rich substrate with biochar. The nutrient levels have only increased when there is rainfall. The recycled materials used to amend the substrates in this study had similar properties (maximum water capacity, bulk density, pH) to the commercial ones.

The results of the experiment show that hybrid green roof system can effectively reduce the nutrients concentrations in greywater and provide enough water for vegetation to grow, which can effectively reduce the urban heat island effect, cool the building underneath and even provide a source of good quality domestic water.

References:

  • Petreje, et.al, Performance study of an innovative concept of hybrid constructed wetland extensive green roof with growing media amended with recycled materials, J. Environ. Manag. vol, 331 (2023), 10.1016/j.jenvman.2022.117151

How to cite: Petreje, M., Rybová, B., Hečková, P., and Sněhota, M.: Biodiverse dual-purpose wetland-green rooftop design based on recyclates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7673, https://doi.org/10.5194/egusphere-egu24-7673, 2024.

EGU24-9048 | ECS | Posters on site | SSS9.13

Carbon storage in urban soils of Lausanne and Zürich, Switzerland 

Eloise Singer, Antoine Vialle, Kevin Vega, Denali Maeder, Tess Giacobbo, Yannick Poyat, Johan Six, Géraldine Bullinger, Claire Le Bayon, and Stephanie Grand

Some urban soils are likely to store large amounts of organic carbon, due to their perennial vegetation cover; yet we have very little empirical data on the organic carbon stocks of urban soils. In this study, we aimed to quantify the carbon stocks of urban topsoils developed from different geological substrates and under different land uses.

We selected the Lausanne-Morges agglomeration and the city of Zürich with a constrasting urban and geomorphological context. In order to quantify the carbon content, soils developed on 6 different parent materials and 7 primary vegetation types were sampled. In total, 107 soils were sampled from October 2022 to April 2023. In addition, data from the project Better Gardens (Tresch et al., 2018) and the master thesis of Eloïse Singer were also used to have a more representative view of the urban green surfaces (248 sites).

The samples were collected with a 2.5 cm auger by mixing 5 sub-samples in an area of 2 x 2 m, from a 0 to 20 cm depth. The analyses conducted were bulk density, soil organic carbon (SOC) content, texture by laser granulometry and carbon to nitrogen ratio (C:N). Soil parent material was assigned from existing geomorphological maps. Land use (vegetation type) was initially determined from urban maps then checked on-site.

We investigated differences in soil properties between cities, parent material and land uses using analyses of variance. The 4.3.1 version on R Studio was used to create exploratory graphs (boxplots and QQ-Plots) and for all statistical analyses.

Overall, Lausanne had siltier soils than Zürich. The C:N ratio was also narrower in Lausanne, with an average of 8 for Lausanne and 13 for Zürich. The mean bulk density results showed that the sampled soils were not as compacted as expected in an urban area (µ = 1.09 g/cm3). The highest bulk density was found on a lawn site in Zürich (µ = 1.20 g/cm3). Geomorphology class as determined from the maps was not found to have a significant effect on any of our soil properties. This could be explained by human soil disturbance and the overarching effect of management practices in urban areas.

The SOC topsoil stock of Lausanne’s public green spaces varied between 9.1 and 149.0 t/ha with an average of 61.8 t/ha, while those of Zurich varies between 29.5 and 141.2 t/ha with an average of 75.6 t/ha. The private gardens were found to have a significantly higher SOC % than the public green spaces, which was consistent with findings of previous studies. 

This study provides new empirical data on the carbon stocks in urban soils developed from different geomorphological substrates and under numerous land uses. Overall, results suggest that the ecosystem services supported by the soils are still functional. The carbon sequestration capacity of the urban soils should not be underestimated as part of the solution for global climate change mitigation and adaptation. It should be taken into account in decision making processes towards a sustainable urbanisation. 

How to cite: Singer, E., Vialle, A., Vega, K., Maeder, D., Giacobbo, T., Poyat, Y., Six, J., Bullinger, G., Le Bayon, C., and Grand, S.: Carbon storage in urban soils of Lausanne and Zürich, Switzerland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9048, https://doi.org/10.5194/egusphere-egu24-9048, 2024.

EGU24-11204 | ECS | Posters on site | SSS9.13

Reusing asphalt millings with excavated materials and compost to construct Technosols: effects on plant and soil properties 

Irina Mikajlo, Anne Pando, Henri Robain, and Thomas Z. Lerch

Desealing and soil renaturation is a major concern in European cities to rehabilitate degraded ecosystem services in urban areas. In order to minimize both the economic and environmental costs of urban greening, wastes generated by desealing operations could be reused for soil construction. To our knowledge, the effect of asphalt milling incorporation into constructed Technosols on soil physical, chemical and biological properties and plant growth has never been evaluated yet. In this study, we tested different compositions of Technosols including excavated deep horizons of soils (EDH) mixed with milled asphalt and with different ratios (0-10-20-30%) of compost. The same combinations were made with coarse sand instead of milled asphalt as a reference. The experiment was undertaken for 3 months in a phytotron, with planted ryegrass (Lolium perenne). Thereafter, plant root and shoot biomass were collected and elemental composition analysis was performed using X-ray fluorescence (XRF). The soil physicochemical properties (pH, water retention, CEC…) were measured as well as the microbial characterization (Biolog® Ecoplates, DNA extraction and qPCR). Results obtained showed that the milled asphalt addition had a small negative or no influence on soil properties depending on the dose of compost added. Plant biomass tends to decrease for the Technosol with the highest asphalt content but, again, these effects were mitigated by compost addition. The optimal substrate was with 10% of milled asphalt for low organic matter content. The highest compost content (30%) evened the shoot biomass differences among the treatments. The root biomass followed the shoot biomass, although the highest root/shoot ratio was observed for the modalities with low compost content (0-10%). A significant effect of asphalt millings was also detected in plant elemental composition with relative enrichment of more macro-elements (P, K, Cl, S), certain oligo-elements (Mn, Zn, Cu) and trace metals (Cr). Overall, these results suggest that asphalt millings could be used as parent material for constructed Technosols.

How to cite: Mikajlo, I., Pando, A., Robain, H., and Lerch, T. Z.: Reusing asphalt millings with excavated materials and compost to construct Technosols: effects on plant and soil properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11204, https://doi.org/10.5194/egusphere-egu24-11204, 2024.

EGU24-11435 | Orals | SSS9.13

Soil organic matter quality along an urbanization gradient in Paris region 

Thomas Z. Lerch, Ludovic Foti, Naoise Nunan, Luc Abbadie, Sebastien Barot, Xavier Raynaud, and Jean-Christophe Lata

Studying carbon stocks and fluxes in urban soils is becoming increasingly relevant, considering the continuous urbanization. Although they represent a relatively small area compared to forest or arable soils, urban soils could be considered as hot spots of anthropogenic carbon accumulation as it is estimated that they contain 3-5 times as much C per ha as natural soils (Vasenev & Kuzyakov, 2018). To date, few studies have investigated urban soil organic matter (SOM) quality and stability, i.e. its resistance to microbial decomposition. In this study, we evaluated the ability of thermogravimetry to predict SOM mineralization kinetic parameters at a regional scale. In order to achieve this, 180 soil samples were collected from two different land uses (lawns and woodlands) along a gradient of urban pressure (rural, suburban and urban areas) in the Paris region (France). We determined SOM mineralization kinetic parameters by measuring CO2 emissions in long-term incubations and the thermal stability of SOM by thermogravimetry combined with differential scanning calorimetry and evolved gas analyzes (TG-DSC-EGA).  The SOM quality was also characterized by using Mid Infra-Red Spectrometry (MIRS). Overall, SOM thermal stability increased from the rural to the urban areas in both land-use types. Urban woodland soils had greater SOM thermal stability than urban lawns, probably because the woodlands are much older than the lawns and because of historical soil management legacy in Paris region. Significant and strong relationships were found between SOM thermal analysis indices (CO2-T50 and energy density) and mineralization kinetics parameters (mineralizable C and turnover) measured in the laboratory. MIRS analyses revealed different chemical compositions depending on land use (higher aromaticity and condensation indices in lawns) and the urban gradient (lower polysaccharides content and aromaticity index in cities). This regional scale study suggests that 1) the thermal analysis of SOM, together with MIRS and soil physico-chemical measurements can be used to predict soil C mineralization potential and 2) SOM thermal stability and resistance to microbial mineralization are higher in urban soils, especially in woodlands.

How to cite: Lerch, T. Z., Foti, L., Nunan, N., Abbadie, L., Barot, S., Raynaud, X., and Lata, J.-C.: Soil organic matter quality along an urbanization gradient in Paris region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11435, https://doi.org/10.5194/egusphere-egu24-11435, 2024.

EGU24-12419 | ECS | Orals | SSS9.13

Large-scale mesocosm trials to optimise soil profiles for calcareous grassland habitat creation 

Christopher McCloskey, Silvia Arpano, Jane Rickson, Wilfred Otten, Rebecca Butler, Chris Cantle, Matt Hobbs, and Ceri Spears

Calcareous grasslands are important biodiversity sites and among Europe’s most floristically rich habitats. These habitats are, however, threatened; many of the UK’s calcareous grasslands were lost to changing land use during the 20th century and pressure on the surviving (often fragmented) sites persists. Due to their ecological value and threatened status there is significant interest in restoring and creating new areas of calcareous grassland, and an increasing number of projects are working to restore or re-create these internationally important ecosystems.

A major calcareous grassland creation project in the Colne Valley in the UK is being undertaken as part of the Central 1 section of the HS2 (High Speed 2) Phase One rail development, delivered by the Align joint venture. This will form a large area (90 hectare) of calcareous grassland as part of a larger (127 hectare) mosaic habitat including wood pasture and wetlands on former low-grade arable land subsequently used for construction. This represents the largest single area of habitat creation along the HS2 route and will significantly contribute to the project’s commitment to deliver ‘No Net Loss’ in biodiversity. To create soil profiles suitable for supporting species-rich calcareous grassland by-products from the HS2 development will be used; this will combine sustainable re-use of construction materials with the development of novel ways to create or restore chalk grassland habitats. These materials include 2.6 M m3 of excavated chalk from 16 km of tunnel construction, crushed limestone and concrete from decommissioned compounds/haul roads, and subsoils (stripped during site clearance).

However, how to best create soil profiles to support calcareous grassland habitat creation, including the potential for re-use of construction by-products, is not well understood. Success depends on establishing the specialised soil physical, chemical and biological environment required to support the diverse calcareous grasslands plant communities, including suitable soil structure, infiltration capacity and nutrient levels. We have therefore tested constructed soil profiles using different configurations of site-derived materials / construction by-products, using numerous soil and plant metrics through a combination of controlled environment and field trials to assess their ability to support calcareous grassland creation.

Here we present results from the main large-scale, controlled-environment trial at Cranfield University, in which we tested four soil profile configurations and the effect of upper soil layer depth in large (1 m3) soil mesocosms. The development of calcareous grassland on these profiles was closely monitored over a six-month period, including above- and below-ground imaging to monitor sward and root development, alongside close monitoring of soil hydrology, microbial dynamics, nutrient cycling, and vegetation establishment and diversity. This included a simulated drought period to assess how soil profile configurations affected the developing grassland vegetation’s resistance to water stress. Our results provide a uniquely high-resolution examination of how constructed soil profiles can be used to support calcareous grassland establishment and how profile design affects the ability of restored grassland to withstand environmental stress. This will allow improvements in circular re-use of infrastructure construction by-products in habitat restoration and development of novel strategies for the (re-)creation of biodiverse habitats.

How to cite: McCloskey, C., Arpano, S., Rickson, J., Otten, W., Butler, R., Cantle, C., Hobbs, M., and Spears, C.: Large-scale mesocosm trials to optimise soil profiles for calcareous grassland habitat creation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12419, https://doi.org/10.5194/egusphere-egu24-12419, 2024.

EGU24-12429 | Orals | SSS9.13

Carbon stocks in soils of Artic cities: factors of inter- and intra-city variation 

Viacheslav Vasenev, Maria Korneykova, Yurii Dvornikov, Dmitrii Sarzhanov, and Andrey Dolgikh

Climate mitigation strategies and targeted carbon neutrality highlight the potential of soils as important terrestrial stocks of organic carbon (C). Although global soil models and datasets (e.g., HWSD, SoilGrids, or S-world) provide information on soil C stocks’ distribution around the world, they remain biased both geographically and regarding different land-use types. Geographically, soils of high latitudes are usually underrepresented in global datasets compared to temperate or tropical climates. As for land use, the major part of soil data comes from natural and agricultural areas, whereas soils of urban areas remain overlooked or completely ignored. The research aimed to fill this gap by exploring soil C stocks and factors driving their spatial variability in the Russian Arctic zone.

Soil survey was carried out in four cities of the Russian Arctic zone: Apatity (67 N; 33 E), Murmansk (68 N; 33 E), Vorkuta (67 N; 64 E), and Norilsk (69 N; 88 E). Soils in all the cities are exposed to severe climatic conditions combined with strong anthropogenic pressure from the coal and ore mining industries. Vorkuta and Norilsk are located in the permafrost zone, whereas the soils of Apatity and Murmansk do not have the permafrost layer. In each city, 30 to 100 locations were sampled, including topsoil (0-10) and subsoil (till 100 cm) layers. In the collected samples, total and organic carbon (SOC) was measured at the CN analyzer. Bulk density and rock fraction were measured to estimate C stocks. Soil microbial (basal) respiration was measured in standardized lab conditions, and the ratio between basal respiration and SOC contents was used to analyze biodegradation coefficients and half-life time. Spatial patterns of SOC distribution, including inter- and intra-city variability were analyzed by factorial ANOVA.

SOC stocks in Arctic cities were quite heterogeneous with a coefficient of variance of up to 100%. Topsoil SOC stocks were similar or even higher compared to the data reported for Russian cities in temperate climates (e.g., Moscow, Saint-Peterburg, or Ekaterinburg). Subsoil stocks were significantly lower compared to topsoil due to a gradual decrease of SOC contents with depth and a high amount of gravel and rock fragments. Elevation, vegetation, and proximity to the sources of anthropogenic disturbance were the main factors driving the intra-city variability. The difference between the cities depended on bioclimatic conditions including permafrost. On average SOC stocks in cities with permafrost were significantly higher compared to those in cities without the permafrost layers. One of the possible reasons can be the conservation of organic matter in subsoil horizons when the mineralization of organic matter is hampered by low temperatures and low microbial activity. Indirectly this statement is confirmed by higher half-life time values, although the difference was not always statistically significant.

Under climate changes the role of Arctic soils in carbon balance will further increase, therefore the research outcomes are highly relevant to develop the strategies of sustainable urban development in the region.

Acknowledgements This research was supported by RSF # 19-77-30012 and RUDN University Strategic Academic Leadership Program

How to cite: Vasenev, V., Korneykova, M., Dvornikov, Y., Sarzhanov, D., and Dolgikh, A.: Carbon stocks in soils of Artic cities: factors of inter- and intra-city variation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12429, https://doi.org/10.5194/egusphere-egu24-12429, 2024.

EGU24-12915 | Orals | SSS9.13

Microbial communities of soils and soil constructions in the Russian Arctic cities 

Maria Korneykova, Kristina Ivashchenko, Andrey Dolgikh, Ekaterina Kozlova, and Viacheslav Vasenev

Arctic cities attract researchers’ interest by a unique combination of extreme climatic conditions and anthropogenic pressure. Urban soils are different from natural references in terms of the formation and functioning conditions. Urban soils are very heterogeneous ranging from semi-natural soils altered by: on the urbanization to artificial soil constructions composed from different materials and mixtures. These soil constructions are mainly created to support green infrastructure and can be considered a new ecological niche for microorganisms. This research aimed to identify the microbial features of urban soils and soil constructions in Arctic cities compared to the background soils.

The studies were carried out in the recreational zones of Kola region cities: Murmansk (68.58°N, 33.03°E), Monchegorsk (67.56°N, 32.52°E), and Apatity (67.33°N, 33.24°E), different in population, operating industry, and climate. Samples were taken from different soil horizons. Soil morphological (WRB classification), physicochemical properties (density; pH; C, N content (CN analyzer) etc., including heavy metals (ICP) were assessed. Microbiological indicators included the number of archaea, bacteria, fungi genes copies (PCR real time), functional diversity (MicroResp), microbial respiration (SIR).

Four main types of urban soil disturbance of the Kola Arctic have been revealed: slightly disturbed natural podzols and podburs; disturbed urban-stratified podzols and podburs; artificially created soil constructions with evidences of soil formation; artificially created soil constructions. Disturbed urban soil profiles contain a gray-humus urban stratified horizon with a low C content, but high N content and pH values. Urban soils in Murmansk and Monchegorsk had higher contents of C and N compared to those in Apatity. Whereas in terms of the content of heavy metals (Cu, Ni) in soils of Monchegorsk was higher compared to the other cities.

Microbial communities of soils and soil constructions in the Kola Аrctic cities responded differently to the influence of urban anthropogenic factors. The microbiological parameters were significantly influenced by age, land use history, the productivity and structure of vegetation, the degree of soil cover transformation, and the level of pollution. However, general patterns identified for the microbial communities were similar for all urban soils. There was a tendency towards an increase in the functional activity and diversity of microbial communities in artificially created soil constructions compared to natural urban soils and background references. In contrast, microbial respiration was higher in natural urban soils compared to soil constructions, but no general pattern was found across cities when compared to background soils. For example, in Murmansk and Monchegorsk the values were lower compared to background soils, whereas the opposite was shown for Apatity. The number of archaea genes copy was also higher in urban soils of Apatity compared to background soils. For most chemical and microbiological parameters of urban soils, the highest values were identified in the subsoil horizons, which may be due to the presence of buried horizons, various substrates, and artifacts.

Urban soils and soil constructions can provide a niche for microorganisms, but a complex of external factors affecting them in specific conditions plays a fundamental role.

Acknowledgements This research was supported by RSF #23-17-00118 and RUDN University Strategic Academic Leadership Program.

 

 

How to cite: Korneykova, M., Ivashchenko, K., Dolgikh, A., Kozlova, E., and Vasenev, V.: Microbial communities of soils and soil constructions in the Russian Arctic cities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12915, https://doi.org/10.5194/egusphere-egu24-12915, 2024.

EGU24-13024 | ECS | Posters on site | SSS9.13

A citywide analysis of urban soil in parks: metals and organic matter concentration and homogeneous infiltration capacity   

Sara Acevedo, Alejandra Vega, Pablo Pastén, and Carlos Bonilla

Urban soil parks have been extensively studied, but there is still no consensus on how urban soils properties change both spatially and at different urbanization levels. There is evidence that anthropogenic pressures such as the level of urbanization can affect the physical and chemical properties of urban soils, but the conclusions change depending on the city studied. This paper evaluates how topsoil properties differ as a function of urbanization level (parks located inner or outer the main city ring-road) and park characteristics (type of park i.e. treed or turf-covered). The following soil properties were measured in 59 urban topsoils: organic matter (OM), copper (Cu), lead (Pb), and zinc (Zn) Near-saturated hydraulic conductivity (Knear) was measured in two urban parks. Comparison of urban soils located inside and outside the main city ring showed a significant increase in the amount of OM (p < 0.05). Based on a soil survey from the 1990s, the increase in OM was confirmed by comparison with background values. Higher values of Cu, Pb and Zn (p < 0.05) inner the ring was found in comparison to outer. Knear ranged from 0.192 mm/hour to 150.0 mm/hour, near to the lower bound values reported in other similar urban soil studies. No statistically significant differences between parks were found (treed vs. turf-covered). OM and metals show higher values in more urbanized areas, showing the potential effect of anthropogenic pressure on urban soils, while Knear did not vary regards to different parks, showing a lower infiltration capacity than in other studies.

How to cite: Acevedo, S., Vega, A., Pastén, P., and Bonilla, C.: A citywide analysis of urban soil in parks: metals and organic matter concentration and homogeneous infiltration capacity  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13024, https://doi.org/10.5194/egusphere-egu24-13024, 2024.

EGU24-13032 | ECS | Posters on site | SSS9.13

Constructed Technosols as a nature-based solution for surface run-off filtration and treatment: a case study of blue-green infrastructures in Moscow   

Olga Romzaykina, Viacheslav Vasenev, Artyom Losev, and Ekaterina Sergeeva

Accelerating global climate change increases the frequency of extreme meteorological events: heat waves, hurricane-force winds, and rainstorms. Sustainability of urban ecosystems to these events becomes a priority for city planning and development. Urban soils provide the basis for the sustainable development of rain gardens - urban blue-green infrastructures, performing a wide range of ecosystem services that contribute to the mitigation of global climate change, detoxification of pollutants, infiltration, and purification of surface water and, as a result, improving the quality of life in the city. Therefore, the research aimed to model and assess the potential contribution of constructed Technosols to flood mitigation and surface runoff treatment in Moscow city.

The potential of Technosols to perform these ecosystem serves depends on the materials used for Technosols’ construction, construction design (sequence and depth of layers), and vegetation type. In this study, the assessment of the relationship between soil processes and ecosystem services of blue-green infrastructures included two stages. At first, the baseline chemical (organic matter and nutrients’ content, baseline total and mobile heavy metal content, ’pH), physical (texture, water retention curve and infiltration rate) and biological (microbial activity) properties of materials (substrates) were determined. Next, water and dissolved substances’ fluxes in the soil-plant system were monitored and modelled within the framework of a vegetation experiment. At this stage, analysis of water filtrate, estimation of evapotranspiration and transpiration of plants (Hemerocallis hybrid) were studied in parallel to monitoring soil properties.

Several types of river sand of medium (predominantly from 0.5 to 2.0 mm particular sizes) and fine (up to 0.5 mm) fractions, loams and sphagnum peat were used to create soil constructions. All components of soil constructions had no exceedances of pollutants in accordance with local sanitary and hygienic standards. The ratio of components in the design was selected to provide infiltration rate of 100 to 300 mm/h and sufficient nutrient’s content for plants. The best results (237 -315 mm/h) were shown by mixtures composed from the medium sand (not less than 70%) and peat. The results of the experiment with water retention curves showed that substrates with 70% sand had total water holding capacity ranging from 37 to 68%, whereas the total water holding capacity of pure peat reached 400%. To model the real-life rainfall conditions, peat infiltration was determined for unsaturated (long period without rains) and saturated (continuous intensive rainfall) samples. The obtained difference in filtration rates was in several orders of magnitude - 7 mm/h for unsaturated samples and over 1400 mm/h for the saturated samples. This outcome will be considered for further modeling the water-conducting capacity of peat-containing constructed Technosols in the HYDRUS 3D software. Subsequent phases of the project will include monitoring of leachate contamination with lead and zinc salts and evaluation of ecosystem service performance indicators in a real rain garden.

The research was supported by Russian Science Foundation project 23-77-01069.

 

How to cite: Romzaykina, O., Vasenev, V., Losev, A., and Sergeeva, E.: Constructed Technosols as a nature-based solution for surface run-off filtration and treatment: a case study of blue-green infrastructures in Moscow  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13032, https://doi.org/10.5194/egusphere-egu24-13032, 2024.

  This study focuses on artificial soil materials, which constitute the largest component of green roofs, and aims to compare and analyze the carbon balance of each material from a life cycle assessment perspective. The analyzed artificial soil materials comprise perlite, bottom ash, zeolite, vermiculite, peat moss, cocopeat, humus, carbonized rice hull, biochar, and bark.

  Initially, the carbon emissions of these 11 artificial soil materials were examined, spanning raw material collection, manufacturing, processing, packaging, and transportation. The data utilized comes from both domestic and foreign Life Cycle Inventory (LCI) databases. For materials not present in these databases, estimates were derived based on the values of materials sharing similar production and manufacturing processes.

  Subsequently, the study calculated the carbon balance during the use phase by measuring carbon emissions from the soil to the atmosphere upon application to rooftop planters. Monitoring took place on the roof of the Korea Institute of Civil Engineering and Building Technology (KICT) from September 2022 to September 2023. Measurements were conducted at regular intervals in three replicates of 11 soil material experiments using an EGM-5 portable CO2 gas analyzer. Additionally, Total Carbon (TC) analysis was conducted to assess carbon storage in the soil.

  Perlite and vermiculite, with energy-intensive manufacturing processes but minimal organic matter in the soil, emitted low carbon. Conversely, humus and bark, requiring less energy in manufacturing but containing high organic matter, emitted more carbon into the atmosphere. For peat moss and cocopeat, although manufacturing processes generated little carbon, significant emissions occurred during transportation due to their importation, coupled with notable carbon emissions from organic matter in the soil.

  This study emphasizes the significance of careful material selection when formulating artificial soil for rooftop greening. Even if soil carbon emissions are low, materials with substantial carbon generation during production may undermine carbon neutrality from a life cycle assessment perspective.

How to cite: Kim, H.: Carbon Balance Analysis of Artificial Soil Materials from the Perspective of Life Cycle Assessment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14419, https://doi.org/10.5194/egusphere-egu24-14419, 2024.

EGU24-15077 | ECS | Orals | SSS9.13

Plant and macrofauna communities dynamics in constructed Technosols over 10 years of experimentation 

José Araujo, Anne Pando-Bahuon, and Thomas Lerch

Greater progress in the circular economy is expected to enable large cities to benefit more from ecosystem services. Reusing urban wastes can help reshape the urban environment and make the ecosystem more suitable for human use. Excavated material from building sites is one of the most abundant waste resources in megacities around the world, and some of this mineral waste can be used to create substrates, known as constructed Technosols, for the development of new green spaces. However, long-term studies are needed to determine the influence of the parent materials used in Technosol formulations on the community dynamics and trajectory of these new ecosystems. In this study, we assessed the impact of organic amendment on the evolution of constructed Technosols and the diversity of plant and soil macrofauna. A large-scale experiment was set up in 2013 in the suburban region of Paris, France, using excavated mineral materials with or without green waste compost (10%, v/v). Flora and macrofauna inventories were carried out over 10 years, as well as the physico-chemical properties of both Technosols. Plant biomass was consistently higher in the Technosols amended with compost, while plant diversity converged towards the same level. Soil macrofaunal diversity was negatively affected by the organic amendment initially, but after 10 years it was similar between the two soils and the neighboring soil used as reference. Macroorganisms abundance increased linearly during the first 4 years, especially for earthworms in Technosols with compost, but after 10 years it also decreased to a lower level compared to the neighboring reference soils. This study showed that Technosols constructed with mineral waste is a promising alternative to natural topsoils for green spaces. The addition of compost promoted plant growth throughout the experiment and had no impact on the diversity of plants and soil macrofauna in the long term.

How to cite: Araujo, J., Pando-Bahuon, A., and Lerch, T.: Plant and macrofauna communities dynamics in constructed Technosols over 10 years of experimentation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15077, https://doi.org/10.5194/egusphere-egu24-15077, 2024.

EGU24-15747 | Posters on site | SSS9.13

Constructing Technosols: Prediction of soil hydraulic properties for binary mixtures – concept and application 

Thomas Nehls, Moreen Willaredt, and Peters Andre

Constructed Technosols are important for substituting natural soil material, such as peat and geogenic material, for use in urban green infrastructure. One characteristic of Technosols important to their role in urban green infrastructure, specifically with respect to urban water management, is their soil hydraulic properties (SHPs), depending on the composition of the constructed Technosols (e.g. their components and their mixing ratio). The diversity of possible components and the infinite number of mixing ratios practically prohibit the experimental identification of the composition needed to achieve suitable soil hydrological functions.

In this study, we propose a compositional model for predicting the water retention curves (WRCs) of any binary mixture based on the measured WRCs of its two pure components only (basic scheme) or with one additional mixture (extended scheme). The unsaturated hydraulic conductivity curves (HCCs) are predicted based on the modelled WRCs. The compositional model is developed from existing methods for estimating the porosity of binary mixtures. The model was tested on four data sets of measured WRCs of different binary mixtures. The distribution of water and air in 50 cm high soil columns filled with these mixtures was predicted under hydrostatic conditions in order to assess their suitability for typical urban applications.

The difference between the maxima of the pore size distributions ΔPSDmax (m) of the components indicates the applicability of the compositional approach. For binary mixtures with small ΔPSDmax, the water content deviations between the predicted and the measured WRCs range from 0.004 to 0.039 cm3 cm−3. For mixtures with a large ΔPSDmax, the compositional model is not applicable. The prediction of the soil hydraulic properties of any mixing ratio facilitates the simulation of flow and transport processes in constructed Technosols before they are produced (e.g. for specific urban water management purposes).

The study has been published under https://doi.org/10.5194/hess-27-3125-2023, 2023.

How to cite: Nehls, T., Willaredt, M., and Andre, P.: Constructing Technosols: Prediction of soil hydraulic properties for binary mixtures – concept and application, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15747, https://doi.org/10.5194/egusphere-egu24-15747, 2024.

EGU24-17456 | ECS | Posters on site | SSS9.13

Organic carbon stored in pavement joint material of paved urban soils 

Carlotta Marga Kollmann and Thomas Nehls

Cities emit large amounts of CO2 while urban soils can be crucial sinks for organic carbon (Corg), spatially highly variable due to human activities. In cities, paved soils - streets, sidewalks, plazas - account for about 1/3 of the surface area but little is known about its Corg. It is for instance stored in the soil between the pavers. As the pavement joint material, also called Dialeimmasol, is highly exposed to anthropogenic influences, we assumed that its Corg is not only natural e.g. humus but of technogenic nature, among it black carbon (BC).

Soil mapping guidelines propose to use the Munsell Soil Color chart and pedotransfer functions to predict humus contents. Subsequently, Corg can be calculated using conversion factors. To assess whether this method, designed for natural soil, is applicable to the seam material of paved urban soils, predicted contents were compared to measured Corg and BC of seam material from cities worldwide. The results are used to adjust the model accordingly and to discuss the sink function of paved soils regarding organic carbon.

Acknowledgements: We used data from soil samples that were provided from numerous international colleagues and data from samples that were partly analysed by late Sonja Brodowski, Institute of Crop Science and Resource Conservation, Soil Science and Soil Ecology, University of Bonn 

How to cite: Kollmann, C. M. and Nehls, T.: Organic carbon stored in pavement joint material of paved urban soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17456, https://doi.org/10.5194/egusphere-egu24-17456, 2024.

EGU24-21225 | ECS | Posters on site | SSS9.13

Impacts of intensive wetting, stagnation and drying cycles on carbon pools and allocation within stormwater processing system substrates designed for multifunctionality 

Lauren Porter, Nadja Berger, Franziska Bucka, Monika Egerer, and Ingrid Kögel-Knabner

Greening of our urban ecosystems provides a multiplicity of benefits, from the mood-lifting impact of nature-based aesthetics to the increased available habitat broadening the range of species within our densely packed cities. In recent years, greening efforts have largely been centered around the introduction of street trees, as their strong evapotranspiration effect mitigates increasing urban temperatures. However, the health and vitality of trees requires a significant amount of roadside space and are highly sensitive to stormwater dynamics as well as pollution, making implementation ill-suited in some urban spaces. Infiltration swales offer a practical, low-cost opportunity to counter-act the climatic increase in severe stormevents by purposely constructing substrates capable of processing polluted stormwaters and providing a habit for native plants to thrive. In testing high carbon organic amendments for their capabilities to adsorb road-side heavy metals and biocides as well as for their role in enhancing soil physical, chemical, and biological functioning - a mixture combining urban green waste compost with a high temperature biochar showed superior multidimensional functionality. In this follow-up experiment, informed substrate combinations are compared in their ability to support native plant diversity under cyclic flooded conditions across one growing season. An assessment is made on the potentials of carbon allocation to different pools between the plant, rhizosphere and bulk soil within this system. Results of this study hope not only to inform the scientific community but emphasize to city planners and officials the broadly interdisciplinary nature of soil systems, particularly the importance in pinpointing synergistic services as well as identifying those functions that may stand in opposition to one another.

 

How to cite: Porter, L., Berger, N., Bucka, F., Egerer, M., and Kögel-Knabner, I.: Impacts of intensive wetting, stagnation and drying cycles on carbon pools and allocation within stormwater processing system substrates designed for multifunctionality, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21225, https://doi.org/10.5194/egusphere-egu24-21225, 2024.

EGU24-21344 | Orals | SSS9.13

Impluvium and multifunctional tree planting pits for clean-water sponge cities 

Maha Deeb, Marie Palman, and Pascal Boivin

Soil artificialization goes together with increasing impermeable surface areas. The increased surface runoff and flood hazard is as a major threat in large cities. Moreover, runoff waters transport pollutants to downstream surface waters. A key strategy for sponge cities is to design permeable soils allowing for rain water infiltration, which should go together with runoff water depuration. High quality permeable soils are also necessary to secure and increase the tree cover in cities, which is highly recommended both to fight against heat waves, to provide a comfortable environment and contribute to urban biodiversity. We present a combined solution to these different goals.

To this end, a highly permeable and fertile growing media was designed based on recycled manure and partly pyrolyzed organic matter. The depuration properties of this substrate were quantified for road runoff pollutants (soluble and micro particle forms) and commonly used pesticides. About 100% removal of these pollutants were observed based on breakthrough experiments on Technosol columns, with outflow quality matching the Swiss Water Protection Agency requirements. The fertility of the substrate was assessed in greenhouse pot experiments. Faster plant growth than with conventional horticulture production methods was observed, though no fertilizer was applied to the growing media.

The growing media, named TP70, was then mixed with 70% stones (100-150 mm size) to obtain a Technosol (TP-P) with high bearing capacity such as required for urban use. An experimental 1m large tree plantation pit was built in Lausanne city using a 60 cm layer of the Technosol, covered with 20 cm of stone ballast. The pit was installed under the walkway of a 4% slope street. Runoff water was injected into the ballast via collectors and infiltrated into the Technosol porosity before drainage at the low-end of the pit.

The volume of the pit was designed to comply with the local regulation on runoff water regulation, namely offering a fast-drainage porosity volume larger than the amount 10-year return-time rainfall on the corresponding watershed, with full drainage in less than 4 hours. It was planted with trees and offered an available water volume corresponding to 9 days of maximum evapotranspiration in the experimented case. Both tree growth and hydrological functions of the pit offered high performance. Based on this first experiment, an eco-district was fully equipped with these impluvium pits, thus infiltrating all the rain waters on the district, and Lausanne city is now extending the technology to the city.

How to cite: Deeb, M., Palman, M., and Boivin, P.: Impluvium and multifunctional tree planting pits for clean-water sponge cities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21344, https://doi.org/10.5194/egusphere-egu24-21344, 2024.

EGU24-1443 | ECS | Orals | BG3.32

Nitrous oxide (N2O) emissions from a forested closed landfill site 

Alice Fraser-McDonald, Carl Boardman, Toni Gladding, Stephen Burnley, and Vincent Gauci

Many national governments, organisations and environmental groups have pledged to plant trees in an effort to increase carbon sequestration and mitigate climate change. Tree planting is commonly used as a restoration strategy for former landfill sites, and it is likely that many urban and urban-fringe areas, including closed landfills, will continue to be prioritised for tree planting in the coming years. Trees growing in natural and managed environments have the capacity to act as conduits for the transport of methane (CH4) produced belowground to the atmosphere. This process has also been observed in natural ecosystems for nitrous oxide (N2O) and we examined whether trees growing on closed landfills also mediate N2O emissions to the atmosphere. We investigated whether trees on a closed UK landfill site emitted more N2O than those on a comparable natural site. Measurements were made from stem and soil surfaces over a four-month period using flux chambers and Gas Chromatography. Results were then scaled up and the contributions of N2O stem fluxes to the total surface fluxes in different environments were compared. Analyses showed that stem and soil N2O fluxes from landfill were larger than from trees on the comparable non-landfill site. Tree stem N2O emissions on the former landfill also showed seasonal patterns and decreased with higher sampling positions above ground level. Findings indicated that tree stem N2O emissions accounted for less than 1% of the estimated total landfill surface flux, which was comparable to findings from a mesocosm study, but lower than estimates of the total N2O ecosystem flux in dry and flooded boreal forests (8% and 18%, respectively). Overall, this investigation suggested that trees planted on closed landfill sites may result in additional N2O emissions to the atmosphere, although the tree stem contribution to the total surface flux on the former landfill was a lower magnitude than that of fluxes previously reported from natural forested ecosystems.

How to cite: Fraser-McDonald, A., Boardman, C., Gladding, T., Burnley, S., and Gauci, V.: Nitrous oxide (N2O) emissions from a forested closed landfill site, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1443, https://doi.org/10.5194/egusphere-egu24-1443, 2024.

EGU24-3135 | Posters on site | BG3.32

Long-term nitrogen deposition does not affect nitrous oxide, methane and carbon dioxide exchange of mature beech tree stems 

Katerina Machacova, Thomas Schindler, Hannes Warlo, and Rossella Guerrieri

European beech (Fagus sylvatica L.) is a native and widely grown tree species typical for upland forests of Central and Southeast Europe. The soils of beech forests are regarded as predominant sources of nitrous oxide (N2O), sinks of methane (CH4) and sources of carbon dioxide (CO2), while the contribution of beech trees themselves to the ecosystem greenhouse gas (GHG) exchange varies by gas species and site. Moreover, forest nitrogen (N) and carbon cycling, and thus N2O, CH4 and CO2 turnover processes are affected by N deposition, yet, the long-term effect of N deposition on GHG exchange of soil and mature trees is far from being understood.

We aimed to investigate whether an increase in N deposition can alter forest GHG emissions. In September 2023, we measured N2O, CH4 and CO2 exchange of beech stems and adjacent soil, and various environmental parameters in a mature pre-alpine beech forest in Northeastern Italy, where a N manipulation experiment (4 treatments each replicated in 3 plots) has been carried out since 2015. Four experimental plots were selected: control (N0, only ambient deposition), canopy N addition (N30A, +30 kg ha-1 yr-1 sprayed over tree canopies) and soil N additions with two different doses (N30 and N60, +30 and +60 kg ha-1 yr-1, respectively).

The stems of mature beech trees were net sinks of CH4 (-11.9 ± 3.6 mg ha-1 ground area h-1, median ± 95% confidence interval) and sources of CO2 (639 ± 137 g ha-1 h-1), their N2O exchange potential (3.36 ± 3.82 mg ha-1 h-1) was rather low. The stem fluxes of all three GHGs were not affected by nine years of N treatment.

The long-term N deposition did not alter the soil CO2 emission (3015 ± 193 g ha-1 h-1). However, the N addition to the soil tended to increase the soil CH4 uptake (-642 ± 61 versus -901 ± 69 mg ha-1 h-1, N0+N30A versus N30+N60 plots). The soil N2O emissions were highest at the control plot (82.4 ± 33.9 mg ha-1 h-1), whereas the plots N30A and N60 showed significantly lower fluxes (1.56 ± 12.41 mg ha-1 h-1).

Our preliminary results detected high spatial variability in stem and soil GHG fluxes, which might be rather connected to the variable site topography than to the long-term N deposition effect. Future detailed soil GHG flux measurements across all experimental plots replicates will help to understand this variability and the effect of N deposition on the GHG fluxes.

 

Acknowledgement

This research was supported by the Ministry of Education, Youth and Sports of CR within the programs CzeCOS (grant number LM2023048) and LU - INTER-EXCELLENCE II (grant number LUC23162). We thank Federico Magnani and Alessandra Teglia from the University of Bologna and Reparto Carabinieri Biodiversità in Pian del Cansiglio for scientific and logistic support, respectively.

How to cite: Machacova, K., Schindler, T., Warlo, H., and Guerrieri, R.: Long-term nitrogen deposition does not affect nitrous oxide, methane and carbon dioxide exchange of mature beech tree stems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3135, https://doi.org/10.5194/egusphere-egu24-3135, 2024.

EGU24-3653 | Orals | BG3.32 | Highlight

Hot spots and hot moments of methane and nitrous oxide fluxes in forests: from soil to ecosystem 

Ülo Mander, Reti Ranniku, Thomas Schindler, Mikk Espenberg, Jordi Escuer-Gatius, Katerina Machacova, Jaan Pärn, Mohit Masta, Fahad Ali Kazmi, Lulie Melling, Lizardo Manuel Fachin Malaverri, Mari Pihlatie, Laura Kuusemets, Kuno Kasak, and Kaido Soosaar

Forests cover about 4 billion ha globally. They are important regulators of carbon dioxide (CO2) fluxes, whereas the comprehensive understanding of their overall greenhouse gas (GHG) budgets, especially for methane (CH4) and nitrous oxide (N2O), are still largely unknown.

Wetland forest soils are commonly recognized as emitters of CH4, whereas upland forest soils tend to consume CH4. However, several studies demonstrate that trees can emit a large amount of CH4 especially from tree stems and substantial amounts also from canopies through poorly studied and partly unidentified aerobic processes. Moreover, tree stems can have substantial concentrations of CH4 inside, which can originate from soil or be produced by methanogens within the wood, while canopy CH4 emissions are mostly abiotic and driven by light and temperature. Thus, forest vegetation can be a significant CH4 source.

Various soil microbiological, chemical and physical properties influence N2O fluxes in forests. In general, N2O emissions from tropical wetland forest soils are significantly higher than those from tropical upland forests, temperate and boreal forests. High nitrogen (N) availability, coupled with high moisture content, makes tropical peatland soils especially likely to emit N2O. Similarly, forests on drained N-rich peatland soils in temperate and boreal areas can be significant N2O sources. In temperate zone, a considerable part of such emissions appears in winter.

Understanding spatial and temporal dynamics of GHG emissions is crucial for adequate modelling and mitigation of emissions in forests. In comparison with CO2 fluxes, which are clearly temperature dependent, temporal and spatial variation of soil, tree stem and canopy CH4 and N2O emissions is more complex and poorly studied. Soil N2O emissions in wetland and upland forests are mainly determined by soil moisture (soil oxygen concentration), and N2O shows bell-shaped (unimodal) dependence on soil water content. In the wet periods, stem flux of CH4 can be the main source for ecosystem exchange, whereas in the dry periods, emission from canopy adds to the total fluxes from soil and stems. N2O fluxes from the soil and stems are normally low during the dry periods and peak during the wet periods and the freeze-thaw cycles.

Only a few examples are available on ecosystem-level CH4 and N2O budgets (fluxes from the soil, tree stems and shoots + eddy covariance (EC) measurements above the canopy). Nevertheless, estimation of the GHG balance in different forest ecosystems under various environmental conditions is essential for understanding their impact on the Earth’s climate.

In this presentation, we will bring results from ecosystem-level CH4 and N2O flux studies in forests growing on both organic and mineral soils in temperate and tropical zones.

How to cite: Mander, Ü., Ranniku, R., Schindler, T., Espenberg, M., Escuer-Gatius, J., Machacova, K., Pärn, J., Masta, M., Kazmi, F. A., Melling, L., Fachin Malaverri, L. M., Pihlatie, M., Kuusemets, L., Kasak, K., and Soosaar, K.: Hot spots and hot moments of methane and nitrous oxide fluxes in forests: from soil to ecosystem, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3653, https://doi.org/10.5194/egusphere-egu24-3653, 2024.

EGU24-3743 | Orals | BG3.32

Fertilization turns a rubber plantation from sink to methane source 

Daniel Epron, Rawiwan Chotiphan, Ornuma Duangngam, Zixiao Wang, Makoto Shibata, Sumonta Kumar Paul, Poonpipope Kasemsap, and Kannika Sajjaphan

Soils, particularly in upland forests, are the largest biological sink for atmospheric methane (CH4), providing a valuable ecosystem service. Rubber plantations have continually expanded in Southeast Asia, and it is known that converting forests to rubber plantations reduces soil CH4 uptake. However, the effect of management practices, and in particular fertilization, on the methane balance of a rubber plantation has not yet been studied. Rubber plantations cover almost 10% of the country's surface area and almost all rubber plantations are fertilized, two thirds of them intensively or very intensively.

We measured net soil CH4 fluxes over more than a year in a 9-ha experimental rubber plantation with four levels of fertilizer application. We observed a strong and significant reduction of net soil CH4 uptake with increasing fertilisation, which was not explained by differences in CH4 diffusion related to soil water content. Fertilisation not only decreased the methanotrophic activity but also stimulated methanogenic activities probably related to an increase in the availability of nitrogen and labile carbon substrates.

Our results show that intensive fertilization turned soil from methane sink to source, particularly during the rainy season. Given the areas cultivated with rubber trees in Thailand and more widely in South-East Asia, a transition towards rational fertilization of plantations would have a significant positive effect on national reporting greenhouse gas inventories.

How to cite: Epron, D., Chotiphan, R., Duangngam, O., Wang, Z., Shibata, M., Paul, S. K., Kasemsap, P., and Sajjaphan, K.: Fertilization turns a rubber plantation from sink to methane source, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3743, https://doi.org/10.5194/egusphere-egu24-3743, 2024.

EGU24-5902 | ECS | Posters on site | BG3.32

Stem and soil methane fluxes of different ecosystems in Central Amazon 

Hellen F. V. Cunha, Sam P. Jones, Hella Van Asperen, Santiago Botía, Shujiro Komiya, Lívia Rosalem, Jochen Schöngart, Maria Teresa Fernandez Piedade, Daniel Magnabosco Marra, Florian Wittmann, and Susan Trumbore

Trees can significantly influence the net exchange of methane between forests and the atmosphere but what controls this behaviour in hyper-diverse ecosystems of the Central Amazon is not well defined. Variations in topography and rainfall cause predictable, but poorly documented, changes to the balance between methanotrophy and metanogenesis in soils and sediments across the landscape and between seasons. Trees can act as conduits for methane produced below-ground, however, the rate of such transport is mediated by inter and intra-species traits that need to be understood.

To better understand the relationships among methane exchange, topographic position, seasonal rainfall and tree species in forests of the Central Amazon, we are conducting two related studies within the Uatumã Sustainable Development Reserve and Amazon Tall Tower Observatory, Amazonas, Brazil. The first is measuring soil and stem fluxes in six plots (6 trees / plot) along a topographic transition from a well-drained plateau, through slopes to a waterlogged valley. The second study is focusing on stem fluxes from six different species (5 trees / species), with differences in wood density and phenology, growing at a similar elevation in an Igapó forest of the adjacent Uatumã river. These observations, starting in September 2023, are being made every 2-3 months to capture the influence of seasonal rainfall and inundation.

During the dry season (September, 2023), soils in the plateau (-1.4 ± 0.27 nmol m-2 s-1) and slope (-1.66 ± 0.11 to -1.20 ± 0.29 nmol m-2 s-1) plots acted as a sink for methane, whilst, those in the valley plot where a source (11.40 ± 2.56 nmol m-2 s-1 ). Reflecting this pattern, stem emissions were mostly observed in the valley (10.7 ± 4.71 nmol m-2 s-1) and in particular from the palm Mauritia flexuosa. Stem fluxes in the plateau and slope plots were marginal (0.0028 ± 0.0039 to 0.224 ± 0.0554 nmol m-2 s-1). In the Igapó (November, 2023), the exposed soil behaved as a sink for methane. Differences were observed among the species studied, with the largest emissions from Nectandra amazonum – low wood density group (0.64 ± 0.14 nmol m-2 s-1 ) and Inga sp. – high wood density group (0.39 ± 0.049 nmol m-2 s-1), while the other 4 species had lower emissions (0.0023 ± 0.01 to 0.10 ± 0.01 nmol m-2 s-1). Together these results support methane produced below-ground as the main source of tree emissions across this landscape and highlight the need to take species composition into account when considering the net exchange of methane from these ecosystems.

How to cite: F. V. Cunha, H., P. Jones, S., Van Asperen, H., Botía, S., Komiya, S., Rosalem, L., Schöngart, J., Fernandez Piedade, M. T., Magnabosco Marra, D., Wittmann, F., and Trumbore, S.: Stem and soil methane fluxes of different ecosystems in Central Amazon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5902, https://doi.org/10.5194/egusphere-egu24-5902, 2024.

EGU24-6221 | Orals | BG3.32

Tree stem-atmosphere greenhouse gas fluxes in a boreal riparian forest 

Marcus Klaus, Mats Öquist, and Kateřina Macháčová

The cycling of greenhouse gases in forest ecosystems is significantly influenced by tree stems. Yet, little is known about the variability and drivers of stem-atmosphere greenhouse gas fluxes, especially in managed boreal riparian ecosystems where environmental conditions vary substantially at small spatial scales and throughout the year. Here, we report magnitudes and drivers of tree stem-atmosphere fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) in a riparian buffer zone of a Swedish boreal forest that has been subject to recent forest clearcutting and historic ditching. For two full years, we conducted CO2 and CH4 flux chamber measurements on a monthly basis in 14 spruce trees (Picea abies) and 14 birch trees (Betula pendula) that grew between one and fifteen meters from a headwater stream. We also performed N2O flux measurements during three occasions. All trees were net emitters of CO2 and CH4 over the majority of the year, while N2O fluxes were close to zero. CO2 fluxes correlated strongly and positively with air temperature and followed distinct seasonal cycles peaking in summer. CH4 fluxes correlated modestly with air temperature and solar radiation and peaked in late winter and summer. Trees with larger stem diameter released more CO2 and less CH4, and trees that were nearer the stream released more CO2 and CH4. The CO2 and CH4 fluxes did not differ between spruce and birch in general, but correlations of CO2 fluxes with stem diameter and distance to stream differed between the tree species. The absence of distinct vertical trends in the CO2 and CH4 fluxes along the stems and their lack of correlation with groundwater levels and groundwater greenhouse gas concentrations point to tree internal production as the primary source of the tree stem gas emissions. Upscaled to the ecosystem, the tree stem CO2, CH4 and N2O emissions represented 52% of the forest floor CO2 emissions and 2.5% and 11.3% of the forest floor CHand N2O uptake, respectively, during the snow-free season. The snow cover season contributed 15% and 35% to annual tree stem CO2 and CH4 emissions, respectively. In contrast to other riparian zone studies, the stem gas fluxes in our study generally exhibited characteristics of an upland rather than a wetland ecosystem, likely because of historical ditching and subsequent groundwater level declines.

How to cite: Klaus, M., Öquist, M., and Macháčová, K.: Tree stem-atmosphere greenhouse gas fluxes in a boreal riparian forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6221, https://doi.org/10.5194/egusphere-egu24-6221, 2024.

EGU24-7519 | Orals | BG3.32

Ecosystem-scale floodplain forest methane exchange 

Natalia Kowalska, Georg Jocher, Adam Bednařík, Hannes Warlo, Kaido Soosaar, and Katerina Macháčová

Floodplain forests play an important role in the exchange of methane (CH4) with the 
atmosphere. However, due to climate change and anthropogenic activities, main factors driving 
this exchange, such as ground water table and soil temperature, are constantly changing. The 
studied floodplain forest in Lanžhot, Czech Republic, represents nowadays relatively dry 
conditions.
The main aims of our study were to quantify the CH4 emission on the floodplain forest 
ecosystem level using the eddy covariance (EC) method, with special emphasis on 
environmental conditions, turbulence development and footprint, as well as to probe all 
potential CH4 sinks and sources within the studied ecosystem for arriving at a complete CH4
budget. The ecosystem-scale CH4 fluxes were analysed with regards to the CH4 emissions of 
water bodies within the EC footprint. CH4 fluxes from a stream located within the footprint of 
the EC tower were measured using floating chambers and bubble traps. Studies were 
complemented by the analysis of the contribution of trees to the CH4 exchange. For this 
purpose, stem chambers measured CH4 fluxes on hornbeam trees, one of the main tree species 
at the study site and in Central Europe. Additionally, CH4 fluxes from the soil were included in 
the analysis to capture all potential CH4 sources and sinks within the studied ecosystem.
We initially hypothesized that ecosystem-scale CH4 exchange will be negligible. Our results
showed, however, that the whole ecosystem is a small but constant CH4 source as we observed 
an average emission flux of 11.7 mg CH4 m-2
day-1 over the period June to December 2021. In addition, we observed variability of the CH4 fluxes in relation to the wind direction and to u*
(friction velocity, indicator for turbulence development). Further analysis shall answer on the 
question if more water bodies within a particular wind sectors means higher fluxes above the 
canopy and if higher turbulence is correlated with higher CH4 fluxes above canopy as hotspot 
emissions are better mixed up. The probed stream was a substantial source of CH4 with average
CH4 fluxes of 260 ± 107 mg CH4 m-2 day-1, respectively, over the period from April to 
December 2021. Ebullition was the dominant pathway of CH4 release throughout the whole 
monitored time period. Results from the stem and soil CH4 flux measurements identified 
hornbeam stems and soil as net sinks for CH4 (-0.025 and -0.999 mg CH4 m-2
day-1, respectively). Finally, after putting all pieces together we will arrive at a holistic view of CH4
dynamics within the studied floodplain forest ecosystem with the potential of transfer of 
knowledge to ecosystem of similar kind elsewhere.

How to cite: Kowalska, N., Jocher, G., Bednařík, A., Warlo, H., Soosaar, K., and Macháčová, K.: Ecosystem-scale floodplain forest methane exchange, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7519, https://doi.org/10.5194/egusphere-egu24-7519, 2024.

EGU24-9235 | Posters on site | BG3.32

Seasonal variation in ecosystem and soil methane and nitrous oxide fluxes in a tropical rainforest 

Laëtitia Brechet, Mercedes Ibáñez, Benoît Burban, Jean-Yves Goret, Clément Stahl, Damien Bonal, Rob Jackson, and Ivan Janssens

Tropical forests play a key role in the global carbon balance and in natural climate change mitigation, as they account for 68% of global forest carbon stocks and represent up to 30% of global soil carbon stocks. However, major uncertainties remain regarding the long-term sustainability of their carbon sink capacity when considering the full greenhouse gas exchange, including methane (CH4) and nitrous oxide (N2O) fluxes, and accurately identifying and quantifying all sources and sinks.

In this line, we present here original continuous high-frequency ecosystem (eddy covariance) and soil (automated chamber) CH4 and N2O flux data from a 2.5-year study in a seasonally wet tropical forest at the Guyaflux experimental site, French Guiana. The main objective of our study was to assess the seasonal patterns of CH4 and N2O exchange at the ecosystem and soil levels, and to identify the environmental drivers. Seasonal variations in ecosystem and soil CH4 and N2O fluxes were tremendous, with generally higher CH4 and N2O emissions in the wettest than in the driest season. Global radiation, soil water content and soil temperature were the main drivers of seasonal variation in ecosystem and soil CH4 and N2O fluxes. Furthermore, based on eddy covariance measurements of all greenhouse gases, i.e. CH4, N2O and CO2, the forest was overall a significant carbon sink (-1,875 ± 813 kgC ha-1 y-1, i.e. cumulative net ecosystem exchange), although the ecosystem shifted from a small sink to a small source of CH4 during the wettest season, and remained a more or less small but constant source of N2O. In contrast, soil fluxes in the upper part of the forest within the tower footprint were consistently a CH4 sink, while soil N2O fluxes shifted depending on the season, from a small N2O sink in the driest season to a small source in the wettest season.

Our study shows that the carbon sink potential of the Guyaflux forest is not yet compromised by CH4 and N2O emissions. However, under the more frequent extreme conditions of contrasting soil water content and global radiation expected in the future, CH4 and N2O emissions may increase and thus reduce the forest carbon sink.

How to cite: Brechet, L., Ibáñez, M., Burban, B., Goret, J.-Y., Stahl, C., Bonal, D., Jackson, R., and Janssens, I.: Seasonal variation in ecosystem and soil methane and nitrous oxide fluxes in a tropical rainforest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9235, https://doi.org/10.5194/egusphere-egu24-9235, 2024.

EGU24-9718 | ECS | Posters on site | BG3.32

The role of tree species and microbes for the development of net greenhouse gas fluxes from soils after afforestation of agricultural lands 

Karelle Rheault, Jesper Riis Christiansen, and Klaus Steenberg Larsen

Greenhouse gas (GHG) emissions, in the form of CO2, CH4 and N2O, from land use change and agriculture are responsible for up to 20% of anthropogenic emissions, mainly due to deforestation, livestock production and crop fertilization. Afforestation is proposed as an effective means to sequester atmospheric carbon in biomass and soils. However, there is a lack of knowledge about the resultant soil GHG fluxes from temperate afforested ecosystems, how they develop in the field and over many years. Furthermore, tree species choice (deciduous/conifers) may impact the soil biogeochemistry differently through the soil physicochemical properties and the soil microbiome with a currently uncertain outcome in relation to GHG fluxes and the climate mitigation potential.

In this study, we investigate the development of soil GHG fluxes, soil physicochemistry, and the soil microbiome on arable land using a well-established forest chronosequence (Vestskoven, Denmark), which is a former cropland area afforested over the last 50 years with Norway spruce (Picea abies), oak (Quercus robur) and beech (Fagus sylvatica). The total of 19 selected sites in Vestskoven includes 6 to 7 stand ages per tree species. We measured CH4 and CO2 fluxes in situ, and sampled soil for physicochemical and microbial analyses.

We present data on how net soil CH4 uptake and soil CO2 efflux develop with time since planting and how the net soil CH4 uptake correlates with the relative abundance of methanotrophic and methanogenic soil communities. We expect these relationships to be dependent of tree species due to differences in how soil physicochemical properties impact the microbial communities responsible for soil CH4 cycling.

Preliminary results show that afforestation increases net soil CH4 uptake, since all tree species had higher net soil CH4 uptake rates compared to cropland, but the effect of plantation age was only visible in oak stands after 50 years. This indicates tree species-specific regulation of the net CH4 flux and its development over time. There was no clear trend for a development of the soil CO2 efflux after planting for either tree species. We will further present analyses of structural equation modelling elucidating the interactions between gas fluxes, soil physicochemical environment and microbial communities. 

How to cite: Rheault, K., Riis Christiansen, J., and Steenberg Larsen, K.: The role of tree species and microbes for the development of net greenhouse gas fluxes from soils after afforestation of agricultural lands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9718, https://doi.org/10.5194/egusphere-egu24-9718, 2024.

EGU24-11317 | ECS | Posters on site | BG3.32

Long-term observations of CH4 and N2O fluxes in a subalpine Norway spruce forest using chamber and eddy covariance methods 

Luana Krebs, Mana Gharun, Susanne Burri, Iris Feigenwinter, Philip Meier, Liliana Scapucci, and Nina Buchmann

Methane (CH4) and nitrous oxide (N2O) substantially contribute to global greenhouse gas (GHG) emissions together with carbon dioxide (CO2). To understand their impact on future climate change, prioritizing the study of CH4 and N2O fluxes becomes critical. Forest ecosystems, primarily investigated for CO2 exchange, are less explored concerning their exchange of CH4 and N2O. Forests are known to be sinks for CH4, while their role in N2O fluxes varies, acting as either sources or sinks. However, comprehensive studies that concurrently examine CH4 and N2O fluxes in forests, particularly over extended periods and at high elevation, remain scarce. At high altitudes, measuring GHG fluxes with chambers during snowy periods is challenging, leading to a lack of winter flux data which are crucial for understanding flux dynamics related to freeze-thaw cycles and snow patterns. This study addresses this gap by investigating long-term CH4 and N2O fluxes in a subalpine Norway spruce forest (Davos, CH-Dav, ICOS Class 1 Ecosystem station, Switzerland), encompassing both soil and canopy interactions with the atmosphere.

Over five years (2017, 2020-2023 for CH4; 2017, 2020 for N2O), we employed automatic chambers to measure forest-floor fluxes, complemented by below-canopy eddy covariance CH4 flux measurements starting from May 2023, as well as static chamber measurements in 2023. Our research objectives were to 1) characterize the magnitude and seasonal dynamics of CH4 and N2O forest-floor fluxes, and 2) compare CH4 fluxes using chamber and eddy covariance techniques to better understand the interaction of soil and vegetation with the atmosphere.

We hypothesized that the forest floor primarily acts as a net sink for CH4, with soil temperature and snow dynamics being important drivers due to their impact on microbial activity and diffusion rates between soil and atmosphere. Given the low nitrogen availability at the study site, we anticipated very low N2O emissions. Additionally, we hypothesized that comparing CH4 fluxes from chambers and eddy covariance would reveal small differences in their magnitudes, attributable to the distinct measurement scales and scopes of these two techniques. Our results confirmed the forest floor as a consistent CH4 sink, exhibiting substantial short-term fluctuations driven predominantly by air temperature and snow cover. N2O fluxes were negligible over the two-year observation period. Our study contributes to a deeper understanding of how environmental drivers and seasonal dynamics influence CH4 and N2O fluxes in high-elevation forests.

How to cite: Krebs, L., Gharun, M., Burri, S., Feigenwinter, I., Meier, P., Scapucci, L., and Buchmann, N.: Long-term observations of CH4 and N2O fluxes in a subalpine Norway spruce forest using chamber and eddy covariance methods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11317, https://doi.org/10.5194/egusphere-egu24-11317, 2024.

EGU24-11673 | ECS | Posters on site | BG3.32

Foliar Methane and Nitrous Oxide Fluxes: A Comprehensive Study in Tropical Forest Ecosystems 

Khandaker Mohammed Rezaul Karim, Md Abdul Halim, and Sean Thomas

Comprising 45% of global forest cover, tropical forests are pivotal in the GHG budgets. Emerging research highlights the significance of tropical trees as CH4 sources, yet tree-foliage emissions have been minimally investigated. Moreover, the N2O fluxes from tropical tree foliage remain almost completely unexamined.

Objectives: This study presents a comprehensive survey of foliar CH4 and N2O fluxes across tropical forest tree species using integrated output spectroscopy and a purpose-built cuvette system for accurate in-situ flux rate measurements. It tests two key hypotheses: (1) broadleaf trees in well-drained soils of tropical forests exhibit foliar CH4 oxidation; (2) foliar CH4 and N2O flux patterns vary systematically among ecological and phylogenetic groups.

Methods: We measured foliar fluxes from 120 trees across 40 species within Lawachara National Park, Bangladesh, an upland mixed-tropical-evergreen forest, prioritizing diverse shade-tolerant canopy trees. We utilized a dynamic leaf chamber (CS-LC7000) with continuous gas flow and portable CH4 (LGR 915-001) and N2O (LI-7820) analyzers, alongside concurrent measurements of CO2 and H2O flux. In addition to gas flux data, our study incorporated leaf trait measurements (of leaf mass per area and leaf N content).

Results: Across all samples, the mean CH4 flux of 0.016 nmol m-2 s-1 did not display a significant deviation from zero (t = 19.44, df = 827, p > 0.05). In contrast, the mean N2O flux 0.54 nmol m-2 s-1, exhibited a significant elevation above zero (t = 19.42, df = 827, p < 0.001), indicating notable N2O emissions on average. Methane flux varied among species and various ecological successional groups, namely pioneer, mid-successional, and late successional species (F = 5.99, df = 2, p < 0.01). Pioneer species, which were sources of CH­4, demonstrated significantly higher CH4 flux compared to both mid (p < 0.01) and late successional (p < 0.05) species, which both acted as weak CH4 sinks. All ecological groups were sources of N2O, with significant variations among the ecological successional groups (F = 12.97, df = 2, p < 0.01). Pioneer species were identified as the highest emitters of N2O, followed by mid and late-successional species.

A comparative CH4 flux analysis among the 28 families revealed significant variability (F = 47.7, df = 27, p < 0.01), with certain species acting as sources and others as sinks of CH4. Notably, 11 families were classified as CH4 sources, while the remainder functioned as sinks. Meliaceae emerged as having the highest average CH4 emissions, and Thymeliaceae the greatest CH4 consumption. Similarly, a distinct variation in N2O flux was observed among families (F = 6.57, df = 27, p < 0.01), with Sapindaceae showing the highest, and Rubiaceae and Euphorbiaceae the lowest N2O emissions.

Conclusions: This study on foliar CH4 and N2O fluxes in tropical forests reveals trees' crucial role in greenhouse gas emissions. Pioneer species emerge as major emitters of both CH4 and N2O, suggesting that foliar emissions of these GHGs may be pronounced in secondary forests, and hence the importance of conserving intact forests dominated by later-successional species.

How to cite: Karim, K. M. R., Halim, M. A., and Thomas, S.: Foliar Methane and Nitrous Oxide Fluxes: A Comprehensive Study in Tropical Forest Ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11673, https://doi.org/10.5194/egusphere-egu24-11673, 2024.

EGU24-14034 | Orals | BG3.32

Wetland trees are a potential methane sink during dry soil conditions 

Carla Gomez, Sunitha Pangala, David Gowing, Karen Olsson-Francis, Susan Page, and Vincent Gauci

The contribution of trees to the wetland methane (CH4) budget remains highly uncertain. The water table level is an essential driver for stem CH4 emissions, which vary across seasons and soil hydrological conditions. Exceptionally dry conditions are increasingly affecting forests because of climate change, and wetland trees can potentially switch from CH4 sources to sinks. CH4 production and oxidation potentially occur in the oxic/anoxic microsites within wetland tree stems, as in soil, balancing the net stem CH4 emissions to the atmosphere. Yet, the microbial ecology behind these processes is still vastly unexplored, and understanding the role of microbial ecology is essential to predict stem CH4 emission patterns.

Our study focused on characterising stem CH4 fluxes using semi-rigid static chambers and assessing CH4 oxidation and production activities through gas-enriched incubations in two forested wetland ecosystems: a temperate wetland in Flitwick Moor (UK) and tropical peat swamp forests in the Sebangau Forest (Kalimantan, Indonesia), both experiencing lower water table levels than previous years during the same period. Targeted tree species were measured at multiple height intervals and were Alnus glutinosa and Betula pubescens in Flitwick Moor and Shorea balangeran and Xylopia fusca in the Sebangau Forest, the same tree species that were investigated in earlier studies at these sites. DNA analysis from bark, wood, and soil involved two-step PCR and sequencing targeting the 16S rRNA gene, complemented by whole shotgun metagenomics (WGS) to explore the microbial composition and CH4-cycling microorganisms.

Results from Flitwick Moor and the Sebangau Forest showed significantly reduced stem CH4 emissions (<50 µg m-2 hr-1) compared to earlier studies, with trees adopting an upland-like behaviour, displaying heterogenous fluxes with no clear axial pattern or relation to wood properties, as well as CH4 uptake. There was evidence of CH4 oxidation in trees of both ecosystems in the range of 7-47 µg m-3 hr-1. The aerobic and facultative anaerobic bacteria population dominated in tree tissues, and the same number of methanotrophic genera were present in soil and trees, suggesting that microbial groups were recruited from the soil. In A. glutinosa tree tissues a significant positive relation existed between the CH4 oxidising bacteria relative abundance and the oxidation activity. The methanotrophic fraction represented up to 5% of the bacteria in wood, confirming the hypothesis that methanotrophs are ubiquitous in trees of different ecosystems.

CH4-cycling microorganisms are likely to adapt to a soilborne-CH4 gradient up the tree stems; the reduced stem CH4 fluxes in this study resulted from dry soil conditions and potentially from microbial oxidation inside the stem. Conversely, the small proportion of CH4-cycling microorganisms compared to other microbial groups likely reflected the reduced stem CH4 fluxes along the soil-tree continuum. The ratio of CH4-cycling microorganisms might vary across seasons and different hydrological conditions; further long-term studies in forested wetlands will help elucidate the interplay between CH4-cycling microorganisms and stem CH4 fluxes and the importance of trees in balancing CH4 emissions in potentially drier future scenarios.

How to cite: Gomez, C., Pangala, S., Gowing, D., Olsson-Francis, K., Page, S., and Gauci, V.: Wetland trees are a potential methane sink during dry soil conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14034, https://doi.org/10.5194/egusphere-egu24-14034, 2024.

EGU24-14065 | ECS | Orals | BG3.32

Methane fluxes from soil and tree stem surfaces in flooded and non-flooded forests in the Central Amazon basin. 

Jhon del Aguila Pasquel, Jose Mauro Sousa Moura, Miércio Ferreira Junior, Keven dos Santos Lima, Raphael Tapajos, Laetitia M Brechet, Joost L M van Haren, and Scott R Saleska

Methane (CH4) is a greenhouse gas with 35 times the warming potential of carbon dioxide. In the last 15 years, the concentration of atmospheric CH4 has sharply increased and the signature of carbon stable isotope in CH4 has become more negative suggesting biotic sources, such as tropical wetlands, might be partly responsible of the current atmospheric methane budget. Floodplains in the Brazilian Amazon have been found to release vast amounts of CH4 but the methane dynamics in upland forests are not very well studied. We assessed the magnitude of CH4 fluxes from soil and tree stem surfaces across dry and wet seasons in two contrasting ecosystems in the Central Amazon basin: the seasonally flooded varzea and the upland terra firme forest. Likewise, some potential drivers of such fluxes were assessed: tree diameter, stem height of measurement, tree species, water table depth, and air temperature. Methane fluxes were measured using chamber-based techniques in the period 2022-2023. Overall, greater fluxes were released from the trees stems of the varzea forest during the first half of the wet season (June-August). On the other hand, the stem surface of upland trees emitted very low CH4 fluxes (< 1 mg m-2 h-1). Methane fluxes of most trees from the flooded forests decreased with stem height, a pattern not shown by tree fluxes in the upland forest. The fluxes from tree stem emissions varied by tree species in both forest types: Munguba tree (Pachira aquatica) and Jarana tree emitted more CH4 fluxes than other species in varzea and upland forests, respectively. The next step of our research will be the assessment of the microbial role in the methane cycle of both forest types using a combination of isotopic and -omic techniques.

How to cite: del Aguila Pasquel, J., Sousa Moura, J. M., Junior, M. F., dos Santos Lima, K., Tapajos, R., Brechet, L. M., van Haren, J. L. M., and Saleska, S. R.: Methane fluxes from soil and tree stem surfaces in flooded and non-flooded forests in the Central Amazon basin., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14065, https://doi.org/10.5194/egusphere-egu24-14065, 2024.

EGU24-14147 | ECS | Orals | BG3.32

Greenhouse gas fluxes from Downy Birch stems during the spring sap-run period and their dependence on dissolved gas concentrations in xylem sap 

Reti Ranniku, Joosep Truupõld, Mikk Espenberg, Jordi Escuer-Gatius, Fahad Ali Kazmi, Ülo Mander, and Kaido Soosaar

Tree stems are known to emit greenhouse gases CH4, CO2 and N2O to the atmosphere but the processes and drivers behind these fluxes are still contested. Soil water is taken up by tree roots and moves up the xylem due to a negative pressure gradient caused by transpiration through the leaves. Consequently, dissolved gases in the soil water move up the stem and are potentially diffused to the atmosphere through the bark. Periods of soil freeze-thaw in the spring are crucial hot-moments of GHG release from the soil, as well as stems. As birch trees go through a sap running period between the thawing of the soil and bud break, they provide an opportunity to study stem GHG fluxes during the peak time of emissions, together with the concentrations of dissolved gases in the birch sap.

We quantified the fluxes of CH4, CO2 and N2O from Downy birch (Betula pubescens), as well as Norway spruce (Picea abies) for comparison, in a temperate nutrient-rich drained peatland forest in April and May 2023. In addition, we studied the relationship between birch stem fluxes and dissolved gas concentrations inside the xylem sap. Stem fluxes were determined using static chambers attached to the tree stems and automatic LI-COR gas analysers. Dissolved gas samples were extracted from the collected birch sap and soil water after water-atmosphere equilibration, and were analysed in the lab using gas-chromatography. In addition, we analysed the relationships between the chemical and microbiological composition of the soil and soil and stem GHG fluxes.

Birch stem CH4, CO2 and N2O fluxes peaked in the end of April, following the the temporal trend of soil and air temperature, with higher fluxes during warmer days, likely related to increased microbial activity in the soil. Dissolved CH4 concentrations in the birch sap peaked with a delay in relation to peak stem emissions, indicating that xylem sap flow rate needs to be studied to comprehend the water dynamics inside the stem. Relationships between stem fluxes and dissolved gas concentrations were strongest at the bottom part of the tree. A more detailed analysis together with examination of the underlying soil chemistry and microbiology will be presented to further explain the processes behind soil and tree stem GHG flux dynamics.

How to cite: Ranniku, R., Truupõld, J., Espenberg, M., Escuer-Gatius, J., Ali Kazmi, F., Mander, Ü., and Soosaar, K.: Greenhouse gas fluxes from Downy Birch stems during the spring sap-run period and their dependence on dissolved gas concentrations in xylem sap, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14147, https://doi.org/10.5194/egusphere-egu24-14147, 2024.

EGU24-14220 | ECS | Posters on site | BG3.32

How remote sensing contributes to flux upscaling in natural bog ecosystems – a case study in Estonia 

Thomas Schindler, Olga Brovkina, Katerina Machacova, Ülo Mander, and Kaido Soosaar

The research potential to investigate and monitor a peatland site is often limited by difficult accessibility to the site, and a heterogeneous surface with diverse topography, hydrological features, and vegetation. Satellite remote sensing (RS) methods offer the advantage of past-to-present repeating cover research areas compared to field studies. Our case study examined the potential usability of applied satellite RS methods to determine greenhouse gas (GHG) fluxes in natural peatlands. Specifically, we tested several landscape indices on their correlation to GHG fluxes and basic environmental parameters.
The field campaign was carried out from 13.7.2018 to 24.7.2019 in a natural raised bog covered with young pine trees in central Estonia, measuring carbon dioxide (CO2) and methane (CH4) fluxes with manual static chambers, soil temperature, soil moisture, and the water table. The measured air temperature was provided by the nearest meteorological station.  

Land surface temperature (LST) was calculated from satellite Landsat-8 data using open-source code in Google Earth Engine cloud-based service. Normalized Difference Vegetation Index (NDVI), Water Index (NDWI), and Snow Index (NDSI) were calculated from Sentinel-2 data. The relationships between LST and indices with field-measured parameters were explored. Peatland site land covers were mapped using Sentinel-2 data supervised classification into dense trees, sphagnum mosses and grasses, and open water classes. The dynamics of open water locations were estimated based on the distribution of land covers for each month of study period. 

Our correlation analysis reflected different in-situ GHG dynamics throughout the investigated period and the micro-spatial heterogeneity of the land surface, with naturally wetter and dryer spots. The preliminary results show a close relationship between the in-situ measured CO2 fluxes and LST. The CO2 fluxes were further correlated with CH4 fluxes. Distribution of land covers from RS can significantly improve the GHG flux upscaling process. Thus, the obtained results can further help to identify locations in peatlands with the highest risks and priorities to provide detailed in situ monitoring.

Acknowledgements:

This work was supported by the Ministry of Education, Youth and Sports of CR within the CzeCOS program (grant number LM2023048) and project AdAgriF - Advanced methods of greenhouse gases emission reduction and sequestration in agriculture and forest landscape for climate change mitigation (CZ.02.01.01/00/22_008/0004635).

How to cite: Schindler, T., Brovkina, O., Machacova, K., Mander, Ü., and Soosaar, K.: How remote sensing contributes to flux upscaling in natural bog ecosystems – a case study in Estonia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14220, https://doi.org/10.5194/egusphere-egu24-14220, 2024.

EGU24-16677 | ECS | Posters on site | BG3.32

Effect of chamber closure time on soil CH4 and CO2 flux estimation by linear and non-linear model application 

Carl-Fredrik Johannesson, Klaus Steenberg Larsen, Hanna Silvennoinen, Holger Lange, and Jenni Nordén

Soils are key components of the global carbon cycle, releasing CO2 due to plant respiration and microbial decomposition processes and consuming or releasing CH4 depending on the dominance of methanotrophic or methanogenic activity. Gas flux measurements have been, and still are, widely employed to improve our understanding of greenhouse gas budgets as well as the processes and mechanisms regulating them. Thus, accurate estimation of flux rates and dynamics is important.

While there’s a multitude of techniques available for greenhouse gas flux measurements, non-steady state chambers are commonly used. They are however, like other chambers and flux measurement techniques in general, prone to measurement artefacts and biases. When a non-steady state chamber is deployed on top of bare soil, the concentration gradient between the soil and the atmosphere inside the chamber is artificially altered, leading to non-linear gas concentration increases (CO2 and CH4) or decreases (CH4) inside the chamber, even when chamber closure times are short. Whether the true flux rate can still be approximated using linear regression by keeping the chamber closure time short has been discussed for decades and non-linear models rooted in diffusion theory have been developed to account for the non-linearity of the concentration change (e.g., the Hutchinson-Mosier model and the non-steady state diffusive flux estimator (NDFE)). Nonetheless, only few studies have empirically evaluated the effect of chamber closure time on soil flux estimation by linear and non-linear model application, especially using high frequency data.

Using >3 000 forest soil CO2 and CH4 flux measurements collected with a high frequency and precision trace gas concentration analyzer (LI-7810 from LI-COR®), we evaluated the effect of sequentially increasing the time period used for linear and non-linear (Hutchinson-Mosier, (1981)) model fitting, up to a total of 300 seconds. Initial results show that using less time for non-linear model fitting results in higher release estimates for CO2 and higher consumption estimates for CH4 compared to when using the full 300 seconds. We also found that flux estimates from linear and non-linear models converged when decreasing the time period used for the linear fit and increasing the time period used for nonlinear fit, indicating that linear models can provide accurate flux estimates when the time period used for the linear fit is kept short. Our results have implications not only for robust estimation of flux rates, but also for field work and flux measurement logistics and planning.

How to cite: Johannesson, C.-F., Larsen, K. S., Silvennoinen, H., Lange, H., and Nordén, J.: Effect of chamber closure time on soil CH4 and CO2 flux estimation by linear and non-linear model application, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16677, https://doi.org/10.5194/egusphere-egu24-16677, 2024.

EGU24-17619 | ECS | Orals | BG3.32

Variability of tree methane emissions across regions of the Amazon rainforest 

Holly Blincow, Niall McNaramara, Alison Hoyt, Carla Gomez, Dafydd Elias, Jack Lamb, Rodrigo De Sousa, Darlene Gris, Leonardo Pequeno Reis, and Sunitha Pangala

Trees are recently understood to emit large quantities of CH4 through their stems, particularly in tropical wetland environments. There are still large uncertainties of the processes driving tree CH4 emissions, however, the primary mechanism is thought to be through transfer of CH4 produced in soil into tree biomass and then to the atmosphere. Another possible mechanism is via anaerobic decomposition of rotting tree biomass in stems. In the Brazilian Amazon, very little is known about sources and variability of tree CH4 emissions and how they may vary across different flooded regions.

Across regions of the Amazon we aim to understand the variation of CH4 emissions from trees. These regions are characterised as white water flooded forest (Várzea region) and black water flooded forest (Igapo region). Using two tree species of similar ages across two regions, we measured tree CH4 emissions and surrounding porewater CH4 concentrations for two flooded seasons. Across all study locations and tree species we found large but variable net CH4 emissions ranging from 0.01 to 84 mg m-2 hr-1. These variations in emissions are significantly influenced by the tree species. Furthermore, we measured significantly different fluxes when measuring the same tree species across two regions, suggesting there could be vast alterations in flux when attempting to measure emissions across the Amazon region.

Our work also revealed that CH4 emission was highest at the base of trees (30 cm) compared to measurements made higher up the stem (70 cm). This is consistent with radial diffusion of soil derived CH4 up the stem and also stongly suggests the source of CH4 is soil derived. Porewater concentrations of CH4 throughout the soil column further supports tree CH4 emission deriving from soil.

Furthermore, we analysed the stable isotopic carbon values of emitted CH4 and demonstrate that this vertical reduction in emitted CH4 is also in part a product of biological oxidation of CH4 by methanotrophic bacteria located in woody material. The isotopic profile varied between two tree species and at the base of the tree compared with higher up the stem. We also noted individual tree species had isotopic variability across the two sites.

These results show significant CH4 emissions from trees to atmosphere in the Amazon. By using common tree species of similar ages we demonstrate that the strength and variability of these emissions are strongly influenced by site specific variables that require further investigation.

How to cite: Blincow, H., McNaramara, N., Hoyt, A., Gomez, C., Elias, D., Lamb, J., De Sousa, R., Gris, D., Pequeno Reis, L., and Pangala, S.: Variability of tree methane emissions across regions of the Amazon rainforest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17619, https://doi.org/10.5194/egusphere-egu24-17619, 2024.

Trees can emit methane to the atmosphere through the stems. These fluxes might represent a large (and still unaccounted for) source of methane from forests to the atmosphere, but the uncertainties related with the spatial variability are still too large for properly estimating their contribution to the regional CH4 budgets. The general understanding is that these emissions are microbial–produced (either originated in soils or in the heartwood of trees), and thus, they are assumed to be temperature-and-water dependent. However, this assumption has not been tested yet at large scales, from different and contrasted ecosystems and with multiple species. In this study, we measured stem CH4 fluxes on more than 400 trees from 28 different species, spanning temperate, Mediterranean and tropical ecosystems. Our main goal was to distinguish between site-specific, species-specific, and environmental effects on controlling stem CH4 fluxes. Preliminary results showed that species identity regulates stem CH4 fluxes independently of environmental conditions, which might be due to wood properties providing a range of internal stem microhabitats for methanogenic communities or controlling gas diffusivity through the wood.  

How to cite: Barba, J. and Gauci, V.: Environmentally-uncoupled tree stem methane fluxes from temperate, Mediterranean and tropical upland ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20545, https://doi.org/10.5194/egusphere-egu24-20545, 2024.

EGU24-22027 | Orals | BG3.32

Resolving the aerobic methane emissions from Scots pine shoots 

Mari Pihlatie, Salla Tenhovirta, Lukas Kohl, and Markuu Koskinen

Release of CH4 from shoots remains the least understood and most enigmatic process of tree-mediated CH4 fluxes. While stem emissions of trees derive from transported or local, biotic pathways, CH4 emissions from shoots likely originate dominantly from abiotic, aerobic production within the canopies. The estimates of the global source strength of aerobic CH4 emissions suffer from large uncertainties, due to insufficient understanding of the source processes.

In this contribution, we show the environmental drivers, temporal patterns, and physiological determinants of the aerobic CH4 emissions from the shoots of Scots pines and discuss the contribution of aerobic canopy emissions to the boreal forest CH4 cycles. We present shoot-level CH4 fluxes from saplings and mature Scots pine trees, measured in various settings, outdoors and in the greenhouse. We used chamber enclosure methods with online greenhouse gas analysers in both manual and automated measurement settings. For the automated measurements we built a custom measurement system that allowed continuous measurements of greenhouse gas fluxes.

The results from CH4 flux measurements under different light sources indicate that aerobic CH4 emissions are to the most part determined by the intensity and spectral composition of light, and that the emissions are most prominent under direct solar radiation. Hence, the diurnal variations exhibited by these emissions are associated with the diurnal cycle of sunlight, but also vary depending on the cloud conditions. By exposing Scots pine saplings to drought, we further distinguished that the light-driven CH4 emissions from shoots are not a byproduct of photosynthesis-related biochemical reactions. Rather, these emissions result from abiotic thermal and photodegradation of plant compounds.

In ambient conditions, we show median aerobic CH4 emissions of 5.41 ng CH4 g-1 DW h-1under direct sunlight and 2.52 ng CH4 g-1 DW h-1 during variable cloudiness. These emissions are 1-2 % of the emission factor used in most of the global upscale estimates of aerobic CH4 emissions from vegetation. Therefore, Scots pine canopies in boreal climates are likely a CH4 source of only minor importance on a global scale. These emissions may, however, decrease the sink strength of the boreal upland forest soils: our conservative estimate is that the canopy emissions of CH4 may decrease this soil sink strength by 2.1 – 4.6 %. This estimate may yet underestimate the significance of canopy fluxes on the ecosystem scale due to the high spatiotemporal variation of both the canopy CH4 emissions and the CH4 uptake rates of boreal upland soils. To further refine the estimates of the source strength of aerobic CH4 emissions of tree canopies it is, therefore, important to gain more data of shoot-level CH4 fluxes from field measurements.

How to cite: Pihlatie, M., Tenhovirta, S., Kohl, L., and Koskinen, M.: Resolving the aerobic methane emissions from Scots pine shoots, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22027, https://doi.org/10.5194/egusphere-egu24-22027, 2024.

EGU24-1210 | ECS | PICO | BG8.10

Climate change effects of adaptation on annual and perennial crop yields in Uganda 

Catherine Mulinde, Revocatus Twinomuhangi, Edward Kato, and J. G. Mwanjalolo Majaliwa

Climate change impacts are expected to negatively affect crop productivity in several agricultural systems and agro-ecological zones of Africa, where the majority of the rural people derive their livelihood from rain-fed agriculture. In Uganda, mountainous and lake ecosystems are dominant growing areas for major annual and perennial crops, but are more susceptible to future changes in climate. This is likely to deteriorate agricultural livelihoods of these ecosystems through declining productivity of various crops. This study assessed the near-term future climate change effects of selected adaptation practices on yields of annual and perennial crops in coffee growing agro-ecological zones of Uganda. Based on a Cobb-Douglas logarithmic production function, the study examined whether future climate would increase crop productivity through the influence of adaptation practices at current and increased adoption levels in the near-term under RCP8.5 and RCP4.5 for five climate regimes. The study results showed that rainfall changes, particularly wetter conditions (cool-wet and hot-wet climate regimes) are expected to be the most damaging to coffee, banana, maize and beans yields than temperature changes with drier conditions (including ensemble mean, cool-dry and hot-dry) under various altitude gradients. Hence, current adaptation practices have significant potential to reduce crop yield losses especially if future climate becomes drier than wetter in the near-term. The study therefore, recommends that there is a need for further research to identify complementary adaptation practices e.g. through bioengineering, soil loss control and water draining efficiency technologies; that would boost positive crop productivity effects of current adaptation practices, as they are not sufficient on their own in the near-term future even with enhanced adoption rates. Also, plant breeding programs should focus on generating crop varieties that are drought tolerant but can also perform well in volatile hydrological conditions; and those that are more suitable for the various altitudinal changes in climate.

How to cite: Mulinde, C., Twinomuhangi, R., Kato, E., and Majaliwa, J. G. M.: Climate change effects of adaptation on annual and perennial crop yields in Uganda, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1210, https://doi.org/10.5194/egusphere-egu24-1210, 2024.

EGU24-1367 | ECS | PICO | BG8.10

Perspectives for expanding sorghum production in Europe in the face of climate change  

Mohsen Davoudkhani, Nicolas Guilpart, David Makowski, Nicolas Viovy, Philippe Ciais, and Ronny Lauerwald

Sorghum holds the fifth position worldwide in terms of both grain production and cultivation area. However, sorghum is still a minor crop in Europe where, on average, only 0.12% of the cropland area was used for sorghum production between 2017 and 2021. Nonetheless, its production is expanding in this region, with a 57% increase in total sorghum production during the last decade compared to the first decade of the 21st century. Indeed, sorghum is considered a crop of interest for climate change adaptation in Europe due to its high heat tolerance compared to other crops, especially maize. In this study, we aimed to investigate the feasibility of expanding sorghum cultivation in Europe under current and future (middle and end of the 21st century) climatic conditions. We also explored the possibility of replacing maize with locally-produced sorghum for feeding livestock in Europe.

To this end, we developed a machine-learning model that predicts sorghum yields from high-resolution climate data using a random forest algorithm. The model was trained on historical sorghum yield data collected in France, Italy, Spain, and the USA, covering the period from 2000 to 2020. The historical sorghum yield dataset comprises 11,644 data points at subnational ‎administrative levels‎. The set of predictors included monthly climate variables such as solar radiation, minimum and maximum temperature, rainfall, and relative humidity calculated over the growing season (April-November) from the ERA5-Land dataset. The model's performance was evaluated based on cross-validation (R2=0.83, RMSE=0.94 t ha-1) for the 2000 to 2020 period.

In total, we ran the model for 30 future scenarios using bias-corrected climate data produced by five Global Climate Models of the Coupled Model Intercomparison Project phase 6 (CMIP6), following three Representative Concentration Pathways scenarios (SSP1-RCP2.6, SSP3-RCP7.0, and SSP5-RCP8.5), and focusing on two periods (2041-2060 and 2081-2100). In almost all scenarios, sorghum yields decreased up to - 1.5 t ha-1 in the southern part of Europe (e.g., center of Spain, south of France, and Italy) but increased substantially up to + 3 t ha-1 in the northern part (e.g., north of Germany, Poland, and Lithuania) compared to historical yields. In all scenarios, at least 39% of European croplands were projected to support sorghum yields higher than 4.6 t ha-1 (the average sorghum actual yield in Europe in the last decade). Our results showed that sorghum production could increase significantly in Europe under future climates. Regardless of the scenario, if sorghum was grown in one out of three years (respectively, one out of six years), at least 90% (respectively, 45%) of maize used as livestock feed could be replaced by sorghum in Europe. These results could provide valuable information for improving feed security in Europe in the face of climate change.

How to cite: Davoudkhani, M., Guilpart, N., Makowski, D., Viovy, N., Ciais, P., and Lauerwald, R.: Perspectives for expanding sorghum production in Europe in the face of climate change , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1367, https://doi.org/10.5194/egusphere-egu24-1367, 2024.

This scientific inquiry delves into the far-reaching implications of global warming and the continuous emission of anthropogenic greenhouse gases into the Earth's atmosphere. With a primary focus on the semi-arid regions of Morocco, the study broadens its perspective to conduct a comparative analysis of similar challenges faced by Spain, Egypt, Italy, Jordan, Turkey, and Iran. The paper aims to illuminate the intricate interplay between climate change and agriculture, underscoring the imperative for sustainable practices to alleviate the detrimental impacts on food security and economic stability. The methodology employed centers around the utilization of the DSSAT (Decision Support System for Agrotechnology Transfer) model, a reliable tool for simulating yield across different seasons. In this study, the performance of wheat varieties in the Mediterranean and MENA (Middle East and North Africa) regions was evaluated. Optimal yields were observed under treatments involving sprinkler or furrow irrigation and nitrogen application ranging from 60 to 120 kg/ha, resulting in an average yield trend of around 6 t/ha. The identified optimal seeding date was the 1st of November, with conservation or adaptation practices demonstrating superior outcomes. This finding was further validated by MIROC5 climate change projections, estimating yields of up to 6.4 t/ha in Spain and a slight increase in Morocco and one of the sites in Jordan, alas a reduction of 20% in Italy and up to 88% in Iran at the end of the century. The study's significance lies in its evaluation of nutrient and water trends in the MENA and Mediterranean regions, offering farmers and policymakers valuable insights to guide a sustainable transition, both economically and ecologically.

How to cite: Tita, D., Devkota, K., Mahdi, K., and Devkota, M.: "Exploring pathways for the sustainable intensification of wheat production under current and future climate change scenarios in the Mediterranean region", EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3093, https://doi.org/10.5194/egusphere-egu24-3093, 2024.

Using numerical crop models that simulate fundamental plant-related processes is the most efficient way to get insights into crop responses to future potential climate-weather-environmental conditions. This is because numerical crop models can be easily manipulated while focusing on single or multiple factors. Based on functions (empirical relationships) and equations (physical representation of the processes) derived from experimental observations, such models are our most advanced attempts to predict crop “behavior” under future conditions. The current standard practice is to run as many crop models as possible and then use an ensemble of these model outputs to predict an “averaged” change in yield production and crop quality metrics in the future. However, even though tens of different crop models are often being used in the ensemble, the differences among the models can be reduced to very few core functionality processes being simulated differently in such models. Functionality-based model evaluation involves evaluating the model's ability to simulate the underlying processes that determine crop yield rather than just comparing the model output to observed data. This approach can help identify the sources of model discrepancies and improve the accuracy of crop yield projections.

Here, we used three crop models with different functionality-based approaches (DSSAT, WOFOST, and Gcros) to assess biophysical parameters, including leaf area index, aboveground biomass, and grain yield, in a maize–soybean cropping system in Nebraska, USA. We calibrated the models using field data from the US-Ne Mead site, acquired through the AmeriFlux net, as well as soil information derived from the POLARIS soil properties dataset (30 m spatial resolution). We run the models with the 4km GRIDMET weather dataset for maize and soybean across Nebraska to examine the conditions (meteorological, climatic, and other static factors) that drive the change in the results of the different crop models. We aimed to select the most suitable model for best representing the impacts of future climate and environmental changes on these crops in the area per local conditions. We present essential discrepancies among the models and attribute such differences to the functionality-based representation of key processes in the models.

How to cite: Michael, Y., Egorov, F., and Helman, D.: Functionality-based evaluation of three crop models with different key process simulation approaches across maize–soybean cropping systems in Nebraska, USA , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4594, https://doi.org/10.5194/egusphere-egu24-4594, 2024.

EGU24-5647 | ECS | PICO | BG8.10

Identifying effective strategies for cereal cultivation under dry climate in Bavaria 

Omer Shlomi, Bernhard Schauberger, Martin Wiesmeier, and Manuel Sümmerer

Farmers cultivating cereals in Germany have experienced unfavorable conditions during the recent decade due to more frequent droughts and heat episodes (Lüttger & Feike, 2018). These events are likely to aggravate in the future (Trnka et al., 2014). Drought and heat-related yield reductions were already being seen in cereal crops all over the country (Webber et al., 2020; Schmitt et al., 2022).

Franconia covers the northern part of Bavaria, the the most important region for wheat and silage maize cultivation. At the same time, Franconia is the driest region in Bavaria with mean annual precipitation <600 mm.  In the past decade, there has been a noticeable variability in crop yields. Particularly 2018 and 2020 had substantial yield shortfall due to lower rainfall amounts. However, not all regions experienced similar yield reductions. Therfore, further evaluation of the causes of yield variability in response to dry years is essential when choosing practices to increase plant resilience.

Previous studies investigating adaptation options of cereals to climate variability suggested practices such as early maturing cultivars, preceding sowing dates and breeding towards resistant varieties.

The objective of this study is to identify the challenges farmers in Franconia have faced in recent years regarding climate conditions. The temporal focus is from 2015 until the harvest of 2023. Based on that, by integrating farmer’s knowledge and experience we aim to identify successful adaptation strategies that reflect in higher and stable production under dry conditions – but also promise good yields in wet years.

Our approach is multi-faceted, including the evaluation of agricultural strategies applied by farmers, climate data analysis, and integration of satellite data and spatial characteristics. In addition, we use a long term experiment results on cereal cultivaiton methods to support the research findings. By conducting in-depth interviews with ~100 farmers in the region, we explore recent and local farming perspectives. With this combination of methods, we aim to dissect successful approaches and understand pivotal causes for sustainable productivity.

Eventually, we will be able to recommend a comprehensive set of scientifically sound and practical approaches for economic, climate resilient cereal farming under increasingly dry conditions in Northern Bavaria. 

Fig. 1. A flow chart of the data sources used in the research.

 

References:

Lüttger, A. B., & Feike, T. (2018). Development of heat and drought related extreme weather events and their effect on winter wheat yields in Germany. Theoretical and Applied Climatology, 132(1–2), 15–29. https://doi.org/10.1007/s00704-017-2076-y

Schmitt, J., Offermann, F., Söder, M., Frühauf, C., & Finger, R. (2022). Extreme weather events cause significant crop yield losses at the farm level in German agriculture. Food Policy, 112. https://doi.org/10.1016/j.foodpol.2022.102359

Trnka, M., Rötter, R. P., Ruiz-Ramos, M., Kersebaum, K. C., Olesen, J. E., Žalud, Z., & Semenov, M. A. (2014). Adverse weather conditions for European wheat production will become more frequent with climate change. Nature Climate Change, 4(7), 637–643. https://doi.org/10.1038/nclimate2242

Webber, H., Lischeid, G., Sommer, M., Finger, R., Nendel, C., Gaiser, T., & Ewert, F. (2020). No perfect storm for crop yield failure in Germany. Environmental Research Letters, 15(10). https://doi.org/10.1088/1748-9326/aba2a4

How to cite: Shlomi, O., Schauberger, B., Wiesmeier, M., and Sümmerer, M.: Identifying effective strategies for cereal cultivation under dry climate in Bavaria, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5647, https://doi.org/10.5194/egusphere-egu24-5647, 2024.

EGU24-6266 | PICO | BG8.10

Compound and cascading droughts and heatwaves decrease yields by more than half in Sinaloa, Mexico 

Samuel Jonson Sutanto, Susana Mora, Iwan Supit, and Mengru Wang

Drought and heatwave events contribute to agricultural loss worldwide. The impact is further exacerbated with the occurrences of compound and cascading droughts and heatwaves. Here we present a study that evaluates the impact of compound and cascading droughts and heatwaves on Maize yield in Sinaloa Mexico, simulated using the WOFOST crop model. Drought and heatwave events were identified using the Standardized Precipitation Index (SPI-3) and threshold method, respectively. Results show that significant yield reductions are found during extreme drought events, emphasizing the vulnerability of maize farming to unfavorable drought conditions. While heatwaves alone did not show a significant impact on maize yields, the compound and cascading droughts and heatwaves amplify the loss of Maize yields up to 44% compared to normal conditions. This study highlights the need for adaptive strategies in agriculture to sustain food security during extreme events, especially in the context of a multi-hazard framework.

How to cite: Sutanto, S. J., Mora, S., Supit, I., and Wang, M.: Compound and cascading droughts and heatwaves decrease yields by more than half in Sinaloa, Mexico, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6266, https://doi.org/10.5194/egusphere-egu24-6266, 2024.

EGU24-6993 | ECS | PICO | BG8.10

CO2 fertilization effects can fully offset the yield loss due to CO2 induced warming for major C3 crops 

Yuxing Sang, Xuhui Wang, Chenzhi Wang, and Christoph Müller

Rising atmospheric CO2 can enhance global crop yield directly through the CO2 fertilization effect (physiological effects, ), but can also reduce it indirectly through CO2-induced warming (radiative effects, ). The overall consequences of the two opposing CO2 effects have constituted large uncertainties in projecting future crop yields. Here, we first employ a site-level CO2 elevation experiment dataset to constrain the simulated  effect in yield projections of an ensemble of global crop models for four major cereal crops (wheat, maize, rice and soybean). Under well-watered and well-fertilized conditions, the constrained estimates show that elevated CO2 will increase yield of major C3 crops (spring/winter wheat, rice and soybean) by 16.7 ± 2.7% 100 ppm-1, 9.4 ± 2.7% 100 ppm-1, 11.2 ± 2.7% 100 ppm-1, and 12.9 ± 2.4% 100 ppm-1, respectively, while no significant yield gain was found for maize (1.6 ± 1.7% 100 ppm-1). Then, by combining CO2induced warming, crop yield response to warming and the interactive term of the physiological effects and radiative effects, we assess the integrated effects of increasing atmospheric CO2 on crop yield at global scale. The results show that the same level of increase in atmospheric CO2 tends to induce larger  than the yield loss by  for both wheat and rice. But for soybean and maize,  largely offsets , resulting in statistically not significant integrated effects of CO2 for soybean (4.2 ± 15.8%) and maize (-3.0 ± 4.6%).

How to cite: Sang, Y., Wang, X., Wang, C., and Müller, C.: CO2 fertilization effects can fully offset the yield loss due to CO2 induced warming for major C3 crops, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6993, https://doi.org/10.5194/egusphere-egu24-6993, 2024.

EGU24-8088 | ECS | PICO | BG8.10

Reducing nitrogen losses in agriculture: integrated modelling of fertilizer and climate change scenarios in Austria  

Elisabeth Jost, Martin Schönhart, Hermine Mitter, Ottavia Zoboli, and Erwin Schmid

The European Commission has initiated the Green Deal aiming to make the European Union climate-neutral by 2050, with the Farm to Fork strategy being one of its components. Apart from making food systems fair, healthy and eco-friendly, the Farm to Fork strategy targets to reduce nutrient losses and fertilizer use. Previous research has criticized the strategy for its expected negative impacts on European economy, agriculture, and food supply. We add to this research by using an integrated modelling framework to assess the impacts of fertilizer and climate change scenarios on agricultural production and the environment in Austria. The integrated modelling framework consists of the crop rotation model CropRota, the biophysical process model EPIC, and the spatially explicit bottom-up economic land use optimization model BiomAT. Besides other bio-physical and economic datasets, we employ national nitrogen-balance calculations to differentiate between regional and crop specific fertilization intensities as well as mineral and organic fertilizers. We have developed two fertilizer scenarios: a f20 scenario, which considers a uniform 20% reduction of mineral N fertilizer on cropland and grassland, and a fcm scenario, which combines several fertilizer restrictions such as -20% of mineral N fertilizer, a maximum application of 175 kg N ha-1 on cropland and grassland, and no mineral N fertilizer application on permanent grassland. In addition, we consider four climate change scenarios to support systematic analysis of potential effects of fertilizer reductions on land cover/use, fertilization intensities, potentially harmful nitrogen losses in air, water and soil sediments, and agricultural output. Our scenario results show a total reduction of N losses in air, water and soil sediment by 9% (f20) and 20% (fcm), yet imposed restrictions fall short of an intended 50% reduction. N loss reduction potentials are region, land cover/use and management specific. Magnitudes of N input reductions correspond well to potential N loss reductions to air. N losses to water and soil sediment seem to be determined by precipitation, temperature, and topographic factors. We conclude that agricultural measures need to be tailored to regional and topographic factors in order to effectively reduce nitrogen losses.

How to cite: Jost, E., Schönhart, M., Mitter, H., Zoboli, O., and Schmid, E.: Reducing nitrogen losses in agriculture: integrated modelling of fertilizer and climate change scenarios in Austria , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8088, https://doi.org/10.5194/egusphere-egu24-8088, 2024.

EGU24-8495 | PICO | BG8.10

Climate change projections coupled with microclimatic modelling for supporting decision making in viticulture 

André Fonseca, José Cruz, Joana Valente, Fernando Alves, Ana Neto, Rui Flores, and João Santos

Understanding the microclimate dynamics within vineyard living labs is paramount for sustainable and optimised grape production. This study delves into a comprehensive approach, using a microclimate NicheMapR model, local station hourly data, ERA5 land data, and a high-resolution Digital Elevation Model to refine microclimate analyses. The key innovation lies in achieving an unprecedented 10-meter spatial resolution of climate variables, providing a perspective on the intricate interplay of climatic variables within each living lab. The initial phase of the study involves the incorporation of local station data to perform bias correction on ERA5 land data, achieved through quantile mapping techniques. This bias-corrected dataset serves as a robust foundation for subsequent analyses, ensuring that the microclimate model accurately reflects the unique characteristics of the vine living labs under study. Integrating a high-resolution DEM further enhances spatial precision, capturing subtle variations in terrain that can profoundly impact local microclimates, such as shade and horizon angles. Additionally, the 10-meter spatial resolution output from the microclimate model is used to bias correct EURO-CORDEX ensemble models, providing the development of future climatic scenarios. This approach ensures that the future projections are not only regionally specific but also representative of each living lab. An important output of the research is the determination of future climate extreme indices and bioclimatic indices specifically designed for viticulture. By analysing the ensemble models at the 10-meter scale, the study aims to provide invaluable insights into potential shifts in temperature extremes, precipitation patterns, and other climatic variables critical to grape cultivation within a specific living lab. In conclusion, this study presents a holistic and forward-looking approach to microclimate analysis in vine living labs. By integrating advanced geospatial technologies, bias-corrected ERA5 land data, high-resolution DEMs, and the microclimate NicheMapR model, this research expands the knowledge of present microclimates and provides viticulturists with insights into future climate scenarios.

How to cite: Fonseca, A., Cruz, J., Valente, J., Alves, F., Neto, A., Flores, R., and Santos, J.: Climate change projections coupled with microclimatic modelling for supporting decision making in viticulture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8495, https://doi.org/10.5194/egusphere-egu24-8495, 2024.

EGU24-8911 | ECS | PICO | BG8.10

Modeling of farm-specific marginal abatement costs of non-CO2 greenhouse gas mitigation measures in Austria 

Verena Kröner, Katharina Falkner, Hermine Mitter, and Erwin Schmid

Agriculture is a major source of non-CO2 greenhouse gas (GHG) emissions, namely methane (CH4) and nitrous oxide (N2O), and reactive trace gases, such as ammonia (NH3). CH4 emissions originate primarily from enteric fermentation of ruminants and during manure storage. N2O emissions are produced in microbial processes of soils and manure. Emissions of NH3 arise from livestock housing systems, manure storage and application to the soil as well as during grazing. Mitigating GHG emissions has emerged as a key priority for policy makers, researchers and stakeholders, evident in the ambitious emission reduction targets set at both the EU and national levels. However, mitigation measures at the farm level incur different marginal abatement costs (MACs) due to farm and regional specific characteristics. Farm specific calculations of MACs are still limited. Therefore, we aim at (i) modeling non-CO2 GHG emissions, (ii) computing MACs of mitigation measures and (iii) identifying cost-efficient mitigation measures for the Austrian farms using the Farm Optimization Model FAMOS. FAMOS is a mixed-integer linear farm optimization model implemented in GAMS (General Algebraic Modeling Systems; https://www.gams.com/). It is extended with a non-CO2 GHG emission accounting module that follows the guidelines for national GHG inventories provided by the Intergovernmental Panel on Climate Change. Country and farm-specific emission factors are used in the non-CO2 GHG emission accounting. This module enhances the accuracy of emission calculations at the farm level. FAMOS maximizes farm net returns, defined as the sum of market revenues and policy payments minus the costs of production and investment, subject to the farm’s resource endowments such as available land, livestock housing capacity and farm family labor. Agronomic production relationships (e.g., fertilizer and feed balances), farm management practices (e.g., crop rotations, fertilization, irrigation, tillage, feeding and grazing strategies), and legal compliances (e.g., CAP measures and payments, fertilizer intensities as part of the Austrian agri-environmental OEPUL programme) are taken into account. The model uses farm level data from various data sources (e.g., Farm Structure Survey, Integrated Administration and Control System, Standard Gross Margin Catalogue) and is individually solved for each farm in Austria. The model results show that the MACs of mitigation measures differ between farm types and agricultural production regions. For instance, MACs are higher for specialized farms with few and labor-intensive management options. The MACs are lower for managerial measures (e.g., changes in fertilizer management), compared to technological (e.g., changes in livestock housing) and agronomic measures (e.g., cover cropping). Our analysis complements the existing research by calculating MACs of selected mitigation measures at farm level. These results may inform farmers, farm consultants and policy makers in fostering the implementation of cost-efficient mitigation strategies at farm level.

How to cite: Kröner, V., Falkner, K., Mitter, H., and Schmid, E.: Modeling of farm-specific marginal abatement costs of non-CO2 greenhouse gas mitigation measures in Austria, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8911, https://doi.org/10.5194/egusphere-egu24-8911, 2024.

EGU24-9832 | PICO | BG8.10

Crop modelling with AquaCrop during climate change in the Ancash region of the Peruvian Andes 

Patrick C. McGuire, Joy S. Singarayer, Andrew J. Wade, Harvey J.E. Rodda, Nicholas P. Branch, Dionisa Joseph Mattam, Francisco Araujo-Ferreira, Eric Capoen, Alden A. Everhart, Christian Florencio, Fernando Gonzalez, Alexander Herrera, Kevin Lane, Frank M. Meddens, Diana Santos Shupingahua, Martín E. Timaná, and Douglas Walsh

Peruvian Andean rural farmers often have precarious livelihoods and already experience less predictable weather conditions than in recent decades. With the goal of investigating hydrological and agricultural resilience in a region with an uncertain climate future (with regard to both temperature and precipitation), we present here the results obtained from using the AquaCrop software to model both crop growth and the consequent harvest yields in the valleys of the Peruvian Andes, including the Rio Santa Valley in the Ancash region. The crop models are presented for 1970-2099 (the historical and the future during climate change), using RCP2.6 & RCP8.5 Regional Climate Models (RCMs) from CORDEX at a spatial resolution of 0.22 degrees. We chose the CORDEX RCM data that was dynamically downscaled from the CMIP5 GCMs instead of the CHELSA statistically-downscaled data, since the downscaling of the CORDEX RCM data produces more locally-heterogeneous climate averages, which are more consistent with the variable topography. The CORDEX RCM model data has subsequently been bias-corrected to monthly CHIRPS precipitation and monthly ECMWF ERA-Interim temperature extremes from 1981-2005 for locations in the Ancash region, including Yungay and Aija. For the various crops that we modelled (maize/corn, potatoes, dry beans, quinoa, wheat), we find significant interannual variability of the dry yields from crop harvest (without irrigation or fertilizers), particularly when the climate is transitioning to a warmer one for those crops that prefer warmer climates. Without the consideration of irrigation or fertilizers, the possibility of high yield interannual variability could make it difficult for the Peruvian Andean farmers to plan ahead, and maintaining a diversity of crops within the Rio Santa Valley and the wider Ancash region could be advantageous for these farmers.

How to cite: McGuire, P. C., Singarayer, J. S., Wade, A. J., Rodda, H. J. E., Branch, N. P., Joseph Mattam, D., Araujo-Ferreira, F., Capoen, E., Everhart, A. A., Florencio, C., Gonzalez, F., Herrera, A., Lane, K., Meddens, F. M., Santos Shupingahua, D., Timaná, M. E., and Walsh, D.: Crop modelling with AquaCrop during climate change in the Ancash region of the Peruvian Andes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9832, https://doi.org/10.5194/egusphere-egu24-9832, 2024.

EGU24-9930 | ECS | PICO | BG8.10

Soil-crop long-term feedback matters to assess climate change impact on maize yield in Sub-Saharan Africa 

Antoine Couëdel, Gatien N. Falconnier, Myriam Adam, Rémi Cardinael, Kenneth Boote, Eric Justes, Alex Ruane, Ward Smith, Anthony Whitbread, and Marc Corbeels and the co-authors

Sub-Saharan Africa (SSA) faces significant food security risks, primarily due to low soil fertility leading to low crop yields. Climate change is expected to worsen food security issues in SSA due to a combined negative impact on crop yield and soil fertility. A common omission from climate change impact studies in SSA is the interaction between change in soil fertility and crop yield. Integrated soil fertility management (ISFM), which includes the combined use of mineral and organic fertilizers, is expected to increase crop yield but it is uncertain how this advantage is maintained with climate change.   

We explored the impact of scenarios of change in soil fertility and climate variables (temperature, rainfall, and CO2) on rainfed maize yield in four representative sites in SSA with no input and ISFM management. To do so, we used an ensemble of 15 calibrated soil-crop models. Reset and continuous simulations were performed to assess the impact of soil fertility vs climate change on crop yield. In reset simulations, SOC, soil N and soil water were reinitialized each year with the same initial conditions. In continuous simulations, SOC, soil N and soil water values of a given year were obtained from the simulation of the previous year, allowing cumulative effects on SOC and crop yields.

Most models agreed that with current baseline (no input) management, yield changed by a much larger order of magnitude when considering declining soil fertility with baseline climate (-39%), compared with considering constant soil fertility but changes in temperature, rainfall and CO2 (from -12% to +5% depending on the climate variable considered). The interaction between change in soil fertility and climate variables only marginally influenced maize yield (high agreement between models). The model ensemble indicated that when accounting for soil fertility change, the benefits of ISFM systems over no-input systems increased over time (+190%). This increase in ISFM benefits was greater in sites with low initial soil fertility. We advocate for the urgent need to account for soil-crop long-term feedback in climate change studies to avoid large underestimations of climate change and ISFM impact on food production in SSA.

How to cite: Couëdel, A., Falconnier, G. N., Adam, M., Cardinael, R., Boote, K., Justes, E., Ruane, A., Smith, W., Whitbread, A., and Corbeels, M. and the co-authors: Soil-crop long-term feedback matters to assess climate change impact on maize yield in Sub-Saharan Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9930, https://doi.org/10.5194/egusphere-egu24-9930, 2024.

EGU24-10313 | ECS | PICO | BG8.10

Learning from yields: Prevailing features for winter wheat yield variability and the role of farmers’ management decisions 

Luca Giuliano Bernardini, Gernot Bodner, Martin Hofer, and Emma Izquierdo-Verdiguier

The relationship between food security and climate change is a central concern for policymakers and society at large. Temperature fluctuations and extreme weather events significantly impact agriculture, notably affecting yield production. Effective management measures that enhance resilience of crop production to abiotic stress are thus highly important. This requires an appropriate understanding of the predominant stressors and their temporal impact on yield formation under given pedo-climatic conditions. Designing future climate-smart management systems will strongly profit from an appropriate evaluation of current yield variability, identifying the main underlying environmental and management related factors. Therefore, the two key questions addressed in this study are:     

  • At which temporal stage does crop development indicate differentiation in biomass growth that impacts the attainable final crop yield?
  • Are the distinctive crop growth and yield patterns in a region predominantly driven to environmental site effects (soil type, rainfall, temperature) and to what extent farmers’ management decisions (pre-crop, cover crop, seeding time) can influence the site-specific natural drivers? 

In recent decades, multiple approaches have been used to analyze factors driving crop yields, from classical replicated field trials over plot scale agroecosystem models to remote sensing-based machine learning approaches. This work is centered on a georeferenced polygon dataset, containing fields from 0.1 to 16.6 hectares in Lower Austria focused on the country's predominant staple crop, winter wheat, between the years 2013 and 2020. In total, the dataset contains 541 entries with winter wheat yield data and detailed management history of the respective fields. Using different types of feature selection techniques, from classical machine learning (i.e., random forest) to recent techniques (i.e., guided regularized random forest), we aim to (i) analyze the temporal growth pattern and extract the yield determinant features as well as their specific timing from several remote sensing derived indices (e.g., Enhanced Vegetation Index (EVI), Normalized Difference Vegetation Index (NDVI)), and (ii) the role of the site specific pedoclimatic information (e.g., surface air temperature, rainfall, soil data) as well as management data (e.g., previous crop, cover crop, seeding time, tillage type). 

Based on the most promising feature models, we will map the expected winter wheat yield variability for Lower Austria and evaluate yield predictability with regional winter wheat yield data from Lower Austria at NUTS3 level between 2015-2022. Since crop-specific crop yield maps are not currently available at the regional level, the validation data will be obtained by intersecting regional yield data and yearly land cover data.

From the results, we expect to provide an improved insight into yield-relevant time periods for winter wheat growth and their interplay with prevailing site-conditions such as soil type based on remote sensing indices. This can contribute to an improved understanding of winter wheat yield formation, thereby providing decision support for more targeted management adaptation and more realistic estimates of expectable management impacts over the unmanageable fate of natural site conditions.

How to cite: Bernardini, L. G., Bodner, G., Hofer, M., and Izquierdo-Verdiguier, E.: Learning from yields: Prevailing features for winter wheat yield variability and the role of farmers’ management decisions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10313, https://doi.org/10.5194/egusphere-egu24-10313, 2024.

EGU24-10424 | ECS | PICO | BG8.10

How to simulate canopy temperatures in a global, process-based model? 

Marie Hemmen, Werner von Bloh, Heidi Webber, Jens Heinke, and Christoph Müller

The frequency and intensity of high temperature events will very likely increase in the future, which could have significant effects on agricultural production. A suitable tool to assess potential heat stress damages in crops is the climate-driven simulation of crop growth and development processes with computer models. While studies show that process-based models reproduce observed yield variabilities, the temperature sensitivities of underlying growth and development processes are often not in accordance with observational data, which can be a significant source of uncertainty especially in future projections. We intend to reduce these uncertainties by improving process responses to high temperatures in the dynamic global vegetation model LPJmL.

A common weakness of models, including LPJmL, is the use of air temperatures in crop related processes. Depending on climatic factors and water status, these can deviate strongly from canopy temperatures, which can have significant effects on the triggering of temperature-related process responses. As a first step, we thus implemented a combination of energy balance and empirical model in LPJmL that computes canopy temperatures based on equations of Penman and Monteith and empirical findings from Idso and Jackson. First preliminary results of future scenarios (SSP585) show that projected wheat yields are substantially higher or lower in some regions when using canopy temperatures compared to solely air temperature-driven LPJmL simulations. However, while the implemented approach assumes neutral atmospheric stability and thus requires little computing capacity, a comparison study showed that more complex methods that include stability correction factors better reproduce observed canopy temperatures. The difficulty with these complex canopy temperature computations is that the high computing costs can be a limitation for already computationally expensive global models. To solve this problem, we built a complex stand-alone model based on the Monin-Obukhov Similarity Theory for computing canopy temperatures with consideration of the stability conditions and from this derived two emulators that reproduce the results of the complex model with significantly less computing power. The two emulators describe upper and lower canopy temperature bounds under two extreme states of water stress as a function of air temperature, radiation, wind, vapor pressure deficit and leaf area index. For this, we chose parametric models with a third-order polynomial basis function that also include interaction terms of the different variables. To train the emulators, we used a global dataset that covers a broad range of combinations of different weather variables. These two emulators will be implemented in LPJmL to simulate canopy temperatures by first calculating upper and lower canopy temperature bounds and from this deriving final canopy temperatures through scaling with actual water stress. We will then compare the results to those of the approach that assumes neutral atmospheric conditions.

The computation of canopy temperatures is a first step towards better crop yield projections accounting for responses to high temperatures. The first preliminary results highlight the importance of improving the representation of canopy temperatures in global models to better estimate future agricultural yields and to identify potential risks to food security.

How to cite: Hemmen, M., von Bloh, W., Webber, H., Heinke, J., and Müller, C.: How to simulate canopy temperatures in a global, process-based model?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10424, https://doi.org/10.5194/egusphere-egu24-10424, 2024.

Annual food caloric production is the product of caloric yield, cropping frequency (CF, number of production seasons per year) and cropland area. Existing studies have largely focused on crop yield, whereas how CF responds to climate change remains poorly understood. Here, we evaluate the global climate sensitivity of caloric yields and CF at national scale. We find a robust negative association between warming and both caloric yield and CF. By the 2050s, projected CF increases in cold regions are offset by larger decreases in warm regions, resulting in a net global CF reduction (−4.2 ± 2.5% in high emission scenario), suggesting that climate-driven decline in CF will exacerbate crop production loss and not provide climate adaptation alone. Although irrigation is effective in offsetting the projected production loss, irrigation areas have to be expanded by >5% in warm regions to fully offset climate-induced production losses by the 2050s.

How to cite: Zhu, P.: Warming reduces global agricultural production by decreasing cropping frequency and yields, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11585, https://doi.org/10.5194/egusphere-egu24-11585, 2024.

EGU24-13284 | ECS | PICO | BG8.10

Assessment and comparison of crop growth models for estimating wheat production in a semi-arid region of Morocco 

Oumaima Kaissi, Salah Er-raki, Elhoussaine Bouras, Salwa Belaqziz, and Abdelghani Chehbouni

Faced with growing food security challenges influenced by global factors such as population growth, climate change, and soil erosion, the need for sustainable agricultural practices is particularly relevant in Africa. In Morocco, wheat is the most dominant crop, but its production is highly dependent on rainfall. In this research, we evaluate several crop growth models, including AquaCrop, among others, focusing on their ability to effectively improve crop production predictions and yield gap analysis in Morocco. This evaluation is essential to develop adaptive agricultural practices that can mitigate the adverse effects of climate change on crop yields. This study employs AquaCrop-OSPy (ACOSP), an open-source Python version of the AquaCrop model, to simulate various indicators of crop growth such as canopy cover (CC), actual evapotranspiration (ETcact), biomass, and grain yield (GY) for wheat under drip irrigation in the semi-arid Chichaoua region of Marrakech in Morocco. The model was first calibrated by using the field data collected over two wheat fields during the 2016/2017 cropping season. Key parameters affecting CC, ETcact, biomass, and GY were calibrated by comparing field measurements with the model outputs. Then, model validation was carried out on the same fields but during the 2017/2018 cropping season. The results demonstrated that ACOSP effectively simulates CC, ETcact, biomass, and GY across two growing seasons. The comparative analysis between observed and simulated parameters yielded the following average values: for CC, R²=95%, RMSE=8.5%, and MSE=1.1%; for ETcact, R²=76%, RMSE=0.61 mm/day, and MSE=0.40 mm/day; and biomass, R²=87%, RMSE=0.22 t/ha, and MSE=0.05 t/ha during the calibration season. GY recorded was 3.87 t/ha. In the validation season, the model achieved similar accuracy for CC R²=95%, RMSE=8.0%, MSE=1.0 %; and biomass R²=91%, RMSE=0.15 t/ha, MSE=0.05 t/ha; with a GY of 3.29 t/ha. These results confirm the model's reliability in simulating key growth parameters of wheat in a semi-arid environment. Two main aspects are addressed through this study: firstly, to provide valuable information for agricultural policy and decision-making in Morocco, and secondly, to enrich the international conversation on sustainable agricultural practices, particularly in arid and semi-arid regions. Leveraging the findings of efficient simulation of wheat growth and production using the ACOSP model, this research provides a solid basis for local, national, and international key actors in developing robust strategies to improve wheat production, thus enhancing the sustainability and resilience of Moroccan agriculture.

How to cite: Kaissi, O., Er-raki, S., Bouras, E., Belaqziz, S., and Chehbouni, A.: Assessment and comparison of crop growth models for estimating wheat production in a semi-arid region of Morocco, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13284, https://doi.org/10.5194/egusphere-egu24-13284, 2024.

EGU24-13421 | ECS | PICO | BG8.10 | Highlight

Exploring the Opportunities and Challenges of Using Large Language Models to Represent Institutional Agency in Land Use Modelling 

Yongchao Zeng, Calum Brown, Mohamed Byari, Joanna Raymond, Ronja Hotz, and Mark Rounsevell

Institutional agencies play a crucial role in land use change, but modelling their decision-making processes is challenging due to the complexity of the environment they operate within and the bounded rationality of human organizations. Large Language Models (LLMs) offer a novel approach to simulating human decisions. This paper aims to investigate the challenges and opportunities that LLMs bring to land use change modelling by integrating LLM-powered institutional agents with the CRAFTY land use model, in which land users produce a range of ecosystem services. The study develops a structured prompt development approach for coupling LLM-powered agents with existing large-scale simulations. Four types of LLM-powered agents are examined, which use taxes to steer meat production toward a prescribed policy goal. The agents provide reasoning and policy action output in each simulation iteration. The study also uses a technique called quasi-multi-agent to simulate multiple roles involved in the policy processes. Unlike authentic multi-agent simulation, the LLM-powered quasi-multi-agent leverages the LLM's ability to generate contextually coherent text and allows the agents to work as a scriptwriter who composes conversations between different roles. This approach conserves computational resources and has the potential to manage conversational dynamics in policy discussions. The efficacy of these agents is benchmarked against two baseline scenarios: one without any policy intervention and another implementing optimal policy actions determined through a genetic algorithm.

The findings show that while LLM-powered agents perform better than the non-intervention scenario, they fall short of the performance achieved by optimal policy actions. However, LLM-powered agents demonstrate human-like decision-making, marked by policy consistency and transparent reasoning. The agents also generate real-world policymaking strategies, including incrementalism, considering delayed policy influence, proactive policy adjustments, and balancing multiple stakeholder interests. Agents equipped with experiential learning capabilities excel in achieving policy objectives through progressive policy actions. The order of reasoning and proposed policy actions in the prompts has a notable effect on the agents' performance. The research points to both promising opportunities and significant challenges in integrating LLMs into large-scale land-use simulations. The opportunities include exploring naturalistic institutional decision-making and its impact on land use change, using LLM's information retrieval to handle massive institutional documents, modelling institutional networks, and human-AI cooperation. However, challenges mainly lie in the scalability and reliability of LLMs due to the dependence on LLM providers, the paradox of pursuing realistic institutional behaviours versus abstraction and simplification in existing models, and the effectiveness and efficiency in scrutinizing massive textual output, detecting illogical content in prompts, and inaccurate formatting.

How to cite: Zeng, Y., Brown, C., Byari, M., Raymond, J., Hotz, R., and Rounsevell, M.: Exploring the Opportunities and Challenges of Using Large Language Models to Represent Institutional Agency in Land Use Modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13421, https://doi.org/10.5194/egusphere-egu24-13421, 2024.

EGU24-13942 | ECS | PICO | BG8.10

Future changes of Climate Suitability of Global Rainfed Food Crops under different CMIP6 scenarios 

Lucia Mumo, Christian Franzke, and June-Yi Lee

Achieving the second sustainable development goal, “Zero Hunger”, is challenging due to climate change, weather extremes and an unabated human population growth. The consequent increase in global food demand has put additional pressure on agricultural systems. Understanding spatial crop suitability alterations, yields and calories of the four major staple food crops around the globe is imperative for sustainable agricultural optimization, climate mitigation, and food security. This study uses three downscaled and bias-corrected shared socioeconomic scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) from the latest state-of-art climate models in Coupled Model Intercomparison Project phase 6 (CMIP6) courtesy of Worldclim: an ecological crop requirement model (Eco Crop) and a machine-learning extreme gradient boosting model (XGBoost) to estimate future crop suitability and yields. Our results elucidate a northward spatial shift in climate suitability and shrinkage of optimal crop-growing regions as the unsuitable and marginal areas expand. Notably, more reduction of suitable regions is observed for all the crops under the highest emission and in far-future climate (2061-2100) scenarios as compared to the SSP1-2.6 and during the near-future period (2021-2060). Nevertheless, gain in suitable areas for soybeans and wheat has been observed at high latitudes, while the tropics are projected to experience a significant loss of arable land. The optimal zone for maize is projected to significantly reduce by approximately 75% in all emission scenarios. This translates to a maize yield loss of 17.3%, and 8.5% in near and far-future climate periods respectively under SSP5-8.5 scenario. Spatial consistency shows that most of the suitable and optimal zones for soybeans are currently not been used. This study sheds light on crop production optimization as farmers are advised to shift to more suitable climate regions for a given crop rather than agricultural extensification that triggers desertification. Due to the considerable loss of climate-suitable regions for rainfed agricultural systems, global efforts should be directed to irrigation systems to ensure global food security and peace.

 

Keywords: Eco crop, Climate suitability, CMIP6, Food security, Crop Yield, XGBoost

How to cite: Mumo, L., Franzke, C., and Lee, J.-Y.: Future changes of Climate Suitability of Global Rainfed Food Crops under different CMIP6 scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13942, https://doi.org/10.5194/egusphere-egu24-13942, 2024.

EGU24-14354 | ECS | PICO | BG8.10

Comparison of developing WOFOST to model growth between typical fruit (chili pepper) and leafy (Chinese cabbage) vegetables 

Ruoling Tang, Iwan Supit, Ronald Hutjes, Fen Zhang, Xiaozhong Wang, Xuanjing Chen, Fusuo Zhang, and Xinping Chen

Most existed crop modelling studies are mainly cereal crops. Vegetables, the most economical and nutrient-dense crops, recieves insufficient attention, particularly on nutrient-uptake predictions. In open-field vegetable systems with shallower roots, shorter lifespan, and higher nutrient requirements, it is even more challenge to minize water pollution from fertilizers. To ensure both food and environment security, there is an urgent need of precise vegetable models to optimize productivity against fertilizer usage.

We adapted the WOrld FOod STudies (WOFOST) crop growth simulation model for chili pepper (Capsicum annuum L.)  and Chinese cabbage (Brassica rapa L.) to support better fertilizer management under various climate and soil conditions. We conducted field experiments with six various fertilizer strategies (etc., mixed synthetic and organic fertilizers, denitrification products, and slow-control-release fertilizers) in southwestern China from 2019 to 2021. In total about 20 parameters relevant to physiological development, dry matter accumulation, photosynthesis, and nutrient uptake were measured and used in model adaptation.

Our study shows that it is possible to model chili pepper’s growth without changing much from the WOFOST-generic model structure. We provide solutions by adapting user-defined developmental stages to mimic the growth from transplanting to fruiting and subsequently ripeness. As for WOFOST-Chinese cabbage, we further modify the phenological module to mimic the special vernalization habits of Chinese cabbage. Additionally, we design a new data re-analyzation method for accurate biomass partitioning predictions. Overall, both WOFOST-Chili and WOFOST-Chinese cabbage models show good model performance on biomass assimilation (rRMSE = 0.23/0.17 for chili/cabbage leaf dry weight; rRMSE = 0.06/0.17 for chili/cabbage storage organ dry weight) and nutrient uptake (rRMSE = 0.46/0.29 for chili/cabbage leaf N amount; rRMSE = 0.12/0.41 for chili/cabbage storage organ N amount). Besides, an improved leaf area index (LAI) simulation is found in WOFOST-Chinese cabbage (rRMSE = 0.11) than WOFOST-Chili (rRMSE = 0.76).

These findings improve our understanding of yield-nutrient interactions within crop models, provide insights on expanding application of original-designed-for-field crop models to different vegetable versions, also call for a refined dynamic nutrient simulation flow within soil module to evaluate mitigation effect of expanded fertilizer strategies under climate change.

How to cite: Tang, R., Supit, I., Hutjes, R., Zhang, F., Wang, X., Chen, X., Zhang, F., and Chen, X.: Comparison of developing WOFOST to model growth between typical fruit (chili pepper) and leafy (Chinese cabbage) vegetables, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14354, https://doi.org/10.5194/egusphere-egu24-14354, 2024.

EGU24-14402 | ECS | PICO | BG8.10

Model-based drought indicators improve the reliability of crop yield simulations with a statistical model in Poland 

Mamad Eini, Tobias Conradt, and Mikołaj Piniewski

Various inputs can be selected to establish a robust crop yield simulation based on statistical models. Typically, weather variables such as precipitation, temperature, relative humidity, etc., are used as inputs in these models. It is well known that drought is a major limiting factor for crop yield in Central Europe, as manifested in recent years. This study aimed to assess whether adding model-based drought indicators derived from a nationally calibrated and validated process-based agro-hydrological model (Soil and Water Assessment Tool - SWAT) could help increase the predictive power of crop yield prediction. The secondary objective was to assess future projections of crop yield. We considered two drought indicators: the Standardized Precipitation Index (SPI) and the Soil Moisture Index (SMI) with the following accumulation periods: 1970-2019. The ABSOLUT v1.2 (Assessing Best-predictive Sets fOr multiple Linear regressions throUgh exhaustive Testing) model was applied for the prediction of yield of major crops in Poland: winter wheat, spring barley, potatoes, sugar beet, and maize for 16 provinces of the country for the time period 1999-2019. ABSOLUT v1.2 is an adaptive algorithm that utilizes correlations between time-aggregated weather variables and crop yields for yield simulation. Future yield projections were derived based on bias-corrected EURO-CORDEX simulations driven by two Representative Concentration Pathways (RCPs), RCP4.5 and 8.5, corresponding to the radiative forcing levels of 4.5 W/m−2 and 8.5 W/m−2 in the year 2100, respectively. Our results indicate that incorporating drought indicators as predictors in statistical crop yield simulations slightly enhances the reliability of yield prediction in Poland. Projected crop yields reveal that in western parts of Poland, crop yields could experience a decrease of 8%, but in eastern parts, crop yields remain mostly unchanged.

How to cite: Eini, M., Conradt, T., and Piniewski, M.: Model-based drought indicators improve the reliability of crop yield simulations with a statistical model in Poland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14402, https://doi.org/10.5194/egusphere-egu24-14402, 2024.

EGU24-15603 | ECS | PICO | BG8.10

Assessing the Vulnerability of Agricultural Areas under Climate Change in Europe through a Heat Stress Index Approach  

Lioba Martin, Andrew Smerald, Edwin Haas, Tatiana Klimiuk, Antonio Sánchez-Benítez, and Clemens Scheer

Climate change poses a significant threat to agriculture, primarily through yield losses due to droughts and heat waves. The flowering phase of most crops is a critical period during which they are highly susceptible to heat, resulting in long-term damage and substantial yield reduction. Significant heat-induced yield cuts have already been observed in Europe, especially during the frequent and widespread heat waves occurring in the years 2018 to 2022.

By imposing the large-scale atmospheric circulation of the 2018 to 2022 heatwaves onto CMIP6 projections, the impact of such a multi-year event within future climate is made tangible as a storyline (Sánchez-Benítez et al., 2022). The +4K storyline, which gives a flavour of possible atmospheric conditions in the 2090s in the ssp370 scenario, indicates a potential increase of up to 7°C during the flowering phase of major crops in Europe. Using these storylines, we evaluated the impact of such a heatwave on cereal production in Europe under a warmer climate.

To achieve this, we developed a heat stress index, which gauges the amount of stress experienced by crops due to heat exposure during flowering relative to unstressed conditions. This index was then applied to the dynamically downscaled nudged storylines over the European domain and evaluated for major cereal crops (maize and wheat). As part of this evaluation, we modelled how a changing climate would affect planting dates and the area suitable for growing winter cropsand investigated the potential impact of heat on different crop cultivars.

In 2021, we estimate that approximately 4% of cropland in Europe experienced severe heat stress (i.e., yield losses of up to 50%) due to heat waves during flowering. Extrapolating to a scenario with global warming of +4 K, we show that almost 80% of the total European crop area for maize could be affected by heat stress, with 30% of the area experiencing a severe heat stress. This could lead to a 20% yield reduction across Europe. In south-eastern Europe, where the 2021 heatwave was particularly intense, 40% of the harvested area would be severely affected, leading to a yield loss of 32% relative to current conditions.

Our investigation of different stress vulnerabilities shows that some crop varieties may exhibit minimal stress while others face severe damage, leading to considerable intra-crop variability in yield reduction. Planting date plays a major role in the impact of heat stress, since an earlier planting shifts the sensitive window during which the plant is flowering to earlier in the year. For winter crops, such as winter wheat, the increased temperatures in winter could lead to a reduction of the winter wheat growing area of 50% by 2093. Addressing these challenges will require proactive management changes, including strategic decisions on planting dates, crop, and variety selection.

Sánchez-Benítez, A., Goessling, H., Pithan, F., Semmler, T., Jung, T., 2022. The July 2019 European Heat Wave in a Warmer Climate: Storyline Scenarios with a Coupled Model Using Spectral Nudging. Journal of Climate.

How to cite: Martin, L., Smerald, A., Haas, E., Klimiuk, T., Sánchez-Benítez, A., and Scheer, C.: Assessing the Vulnerability of Agricultural Areas under Climate Change in Europe through a Heat Stress Index Approach , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15603, https://doi.org/10.5194/egusphere-egu24-15603, 2024.

EGU24-17998 | ECS | PICO | BG8.10

Viticulture suitability for specific oenological objectives through machine learning integration in a multicriteria analysis: the case of Cannonau terroir in Sardinia (Italy) 

Emanuele Serra, Marta Debolini, Serena Marras, Luca Mercenaro, Giovanni Nieddu, Costantino Sirca, Antonio Trabucco, Pierfrancesco Deiana, and Donatella Spano

The projected warmer temperatures, together with the expected increase in seasonal dryness, frequency, and intensity of extreme climate events during sensitive phenological phases, may have strong effects on the regions’ suitability for grapevine cultivation determining a shift from currently suitable areas toward new ones. Furthermore, shortening phenological advancement is expected to affect the ripening period negatively, by affecting biochemical and physiological processes and thus impacting berry sugar-acid and flavonoid levels, colour, and aroma, especially for early ripening varieties. In this research, multiple climate, soil, topography, and land use data are analyzed and integrated into a multi-criteria evaluation (MCE) to classify suitable areas for grapevine according to FAO classification under actual and future climate conditions. In particular, through the adoption of machine learning techniques, some specific qualitative targets (BRIX, acidity, polyphenol content), functional to obtaining specific oenological objectives will be analyzed. The analysis is focused on the Cannonau terroir, in the region of Sardinia (Italy), and in particular the qualitative target data for land suitability model calibration and validation will be acquired from three wine cellars collecting production from single farmers located in three bioclimatic areas that can be considered as representatives of the whole Sardinia region (Nurra, Barbagia and Parteolla, located respectively in North-west, Center and South of Sardinia). A set of 8 bioclimatic, 5 pedological, and 3 topographic indicators with 1 land cover classification was selected and then divided into a range of values, according to the literature, each of which was associated with a suitability class (FAO). Bioclimatic indicators are obtained by the analysis of current and future climate scenarios from the regionalized climate models downscaled for the whole of Italy at 2.2 km spatial resolution. Considering main and secondary relevant and explanatory criteria with a hierarchical structure, after statistical autocorrelation analysis, different weights will be assigned, calculated, and associated with each factor using the analytical hierarchy (AHP) process and machine learning methods, depending on the importance of each factor in achieving specific production targets according to expert knowledge and literature. The performance of machine learning and statistical inference to define suitability as a function of environmental and bioclimatic characteristics (ANN, Random Forest, MaxEnt, Support Vector Machines), will be subsequently compared to GIS-based results to assess its applicability. The field measurements will be carried out in the pilot sites located in the north, center, and south of Sardinia and will be useful for obtaining pedological, phenological, and qualitative data for the calibration and validation of the model. This work aims to provide an assessment of the spatial variability of the environmental factors that drive terroir distribution, to preserve vineyard production and quality in a changing climate. The research is also a methodological contribution, with the integration of a machine learning approach to the multicriterial land suitability analysis techniques.

How to cite: Serra, E., Debolini, M., Marras, S., Mercenaro, L., Nieddu, G., Sirca, C., Trabucco, A., Deiana, P., and Spano, D.: Viticulture suitability for specific oenological objectives through machine learning integration in a multicriteria analysis: the case of Cannonau terroir in Sardinia (Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17998, https://doi.org/10.5194/egusphere-egu24-17998, 2024.

EGU24-18078 | PICO | BG8.10 | Highlight

An exploration of using large language models to integrate farmer behaviour into an agricultural systems model of the Peruvian Andes 

Joy Singarayer, Richard Bailey, Patrick McGuire, Francisco Araujo- Ferreira, Nicholas Branch, Fernando Gonzalez, Diana Santos Shupingahua, Douglas Walsh, Alexander Herrera, Andrew Wade, Harvey Rodda, Martin Timana, and Kevin Lane

The implications of climate change on agro-pastoral farming systems in the Peruvian Andes are not fully understood. There is already a significant impact on agricultural productivity from current climate variability and extreme weather in the region. This is exacerbated by chronic poverty in many rural areas and the need for improved government-led strategic planning. Tools to assist with policy planning for climate change adaptations that achieve environmental and social resilience are vital, and these require collaboration with rural communities to incorporate the complexities of behavioural responses to climate change, market dynamics, and policy shifts in agricultural and water management. 

In this study we further develop a recent agricultural systems model (the TELLUS model; Pilditch et al., in review). The model is an agent-based simulation focussed on the behaviour of interacting populations of individual farming agents. TELLUS offers the opportunity to analyse the impact of interventions/policies in light of key scenarios and conditions of interest, with potential to uncover unforeseen emergent behaviours within farming systems (e.g., tipping points, amplifiers, system adaptations) and potential unintended consequences of scenarios and policies (e.g., increasing in equalities; increased system fragility). A difficulty in applying such models to specific case studies is in choosing valid parameter values, especially for model behaviour associated with human behaviour and decision-making.

Our work over recent years includes extensive fieldwork in the Cordillera Negra and Cordillera Blanca, involving interviews and workshops with farming communities, and collaboration with regional NGOs. These interactions have been instrumental in understanding local challenges and priorities. The challenge in terms of modelling this system is turning information gained from qualitative methods (e.g. interviews) into parameter values for the model. Our novel approach is to assess the extent to which modern AI systems, specifically, Large Language Models (LLMs) can help perform this task.  We leverage the reasoning abilities of LLMs to directly estimate relevant model parameters from automated interview transcription/translations. We will discuss the extent to which this integration has aided the creation of a TELLUS model tuned specifically to the Peruvian Andes context. Our approach will hopefully serve as a novel tool, combining empirical research, community involvement, and advanced computational modelling, to explore future climate scenarios and the potential effects of policy interventions.

How to cite: Singarayer, J., Bailey, R., McGuire, P., Araujo- Ferreira, F., Branch, N., Gonzalez, F., Santos Shupingahua, D., Walsh, D., Herrera, A., Wade, A., Rodda, H., Timana, M., and Lane, K.: An exploration of using large language models to integrate farmer behaviour into an agricultural systems model of the Peruvian Andes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18078, https://doi.org/10.5194/egusphere-egu24-18078, 2024.

EGU24-18816 | ECS | PICO | BG8.10

Assessing the impacts of future climate scenarios on soil management practices and their hydraulic proprieties 

Edberto Moura Lima, Kristin Böning, Friederike Ding, Christine Stumpp, Annelie Holzkämper, and Bano Mehdi-Schulz

Soil management practices influence soil physical parameters and crop productivity. No-till farming, which is a key component of conservation agriculture, is considered a sustainable alternative to conventional agriculture. The extent to which soil conservation management practices can mitigate the impacts of extreme events (heavy precipitation events and drought) remains unknown, and is examined as part of the SoilX project. This study focuses on two different tillage management practices and their effects on soil hydraulic properties, soil structure, and crop yields under current and future climate conditions. An experimental study site that is a Long-Term Field Experiment (LTE) since 2006 located in Hollabrunn, Lower Austria, was used for soil sampling and crop modelling. The site is located in a Pannonian climate, with average annual (1991-2020) precipitation of 493 mm and a mean air temperature of 9.8 °C. The soil is classified as a silt loam calcareous Chernozem under the WRB or as Typic Vermudoll under the US Soil Taxonomy. The experimental layout comprised two soil tillage treatments (conventional tillage (CT) and no-tillage (NT), both with annual crops and winter cover crops) arranged in a randomized block design. The crop model APEX (Agricultural Policy/Environmental eXtender) model was set up for both treatments to assess the impacts of CT and NT on soil physical properties and their respective hydrological properties. Field soil samples were taken from both treatments (up to 50 cm depth) and analyzed for soil bulk density, soil organic matter (SOC), water stable aggregates (WSA), unsaturated infiltration rates (determined with TDI), water retention curves, and oxygen isotopes in soil pore water. These field measurements were used to parameterize the APEX model. Field operations between 2009 and 2023 also provided model inputs on crop cultivation cycles, tillage, fertilization, sowing, crop protection, and harvesting. The yield (dry matter Mg ha-1) per plot was used for model calibration. From the soil samples obtained in 2023 differences between CT and NT were determined with respect to bulk density and soil water content, i.e. at 10 cm, the unsaturated infiltration rates were higher in CT. The future climate simulations (2050-2100) derived from regional climate models (RCMs) with different representation pathways (RCPs) were input in APEX to assess the impacts of climate change on the soil physical and hydraulic properties (SOC, infiltration rates, soil water storage) under CT and NT. The research results quantify differences in soil physical and hydraulic properties in a future climate, particularly focusing on the extreme events. The findings provide information on soil management strategies to potentially mitigate the adverse impacts of heavy precipitation events and droughts in agricultural cropping systems.

How to cite: Moura Lima, E., Böning, K., Ding, F., Stumpp, C., Holzkämper, A., and Mehdi-Schulz, B.: Assessing the impacts of future climate scenarios on soil management practices and their hydraulic proprieties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18816, https://doi.org/10.5194/egusphere-egu24-18816, 2024.

EGU24-18994 | ECS | PICO | BG8.10

Multiple cropping in global-scale Land-Use Models and the role of Irrigation 

Felicitas Beier, Jens Heinke, Benjamin Leon Bodirsky, Christoph Müller, Sebastian Ostberg, Kristine Karstens, Gabriel Abrahao, Alexander Popp, and Hermann Lotze-Campen

Multiple cropping practices, i.e. planting and harvesting crops several times a year at the same plot of land, may increase global food production without further expanding cropland (Wu et al. 2014). Especially the combination of irrigation in the dry season to facilitate multiple harvests a year potentially facilitates more food production on the same amount of land. Global dynamic gridded vegetation models that inform global land-use models usually only model one growing season a year. Neglecting the yield that can be achieved in the second or third season leads to an underestimation of yields and irrigation water requirements and biased projections of the spatial allocation of rainfed and irrigated cropland.

With an update of our hydro-economic model (Beier et al. 2023), we are able to estimate multiple cropping potentials and model multiple cropping and irrigation expansion. It is the tandem of these two intensification measures that facilitates production gains without expanding cropland. We estimate multiple cropping potentials considering their interaction with irrigation and water availability limitations to determine how much cropland area can be managed in a multiple cropping system given local crop growth conditions (suitability for multiple cropping), the associated water requirements and locally limited water availability for irrigation. We obtain multiple cropping and irrigation potentials at a 0.5° spatial resolution using biophysical inputs from the global vegetation model LPJmL (Schaphoff et al. 2018, von Bloh et al. 2018). LPJmL provides crop-specific (irrigated and rainfed) crop yields and crop water requirements for the main growing season for 12 crop functional types and gross primary production (GPP) of grass for the entire year at a 0.5° spatial resolution. To derive a metric on the yield increase through multiple cropping, we need an aggregated approach that abstracts from the very high set of potential combinations of crops in multiple cropping. We therefore use the main-season-to-whole-year ratio of grass GPP to obtain the grid-cell-specific potential multiple cropping effect. This ratio is used to scale main season crop yields and crop water requirements. In terms of irrigation water availability, the spatial allocation of irrigation water takes upstream-downstream relationships into account and considers the monetary yield gain through irrigation to determine the location of potentially irrigated areas (Beier et al. 2023).

With this, we address the research question: What is the biophysical and economic multiple cropping production potential under consideration of local (spatially explicit) irrigation water availability constraints on current cropland?

References

Beier, F. et al. (2023a). Technical and Economic Irrigation Potentials within Land and Water Boundaries. Water Resources Research

Beier, F., et al. (2023b) ‘Mrwater: MadRat Based MAgPIE Water Input Data Library’. 10.5281/zenodo.5801680.

Schaphoff, S. et al. (2018). ‘LPJmL4 – a Dynamic Global Vegetation Model with Managed Land – Part 1: Model Description’. Geoscientific Model Development 11 (4)

Wu, W., et al. (2018) Global cropping intensity gaps: increasing food production without cropland expansion. Land Use Policy 76 (2018)

von Bloh, W. et al. (2018). Implementing the Nitrogen Cycle into the Dynamic Global Vegetation, Hydrology, and Crop Growth Model LPJmL (Version 5.0). Geoscientific Model Development 11 (7)

How to cite: Beier, F., Heinke, J., Bodirsky, B. L., Müller, C., Ostberg, S., Karstens, K., Abrahao, G., Popp, A., and Lotze-Campen, H.: Multiple cropping in global-scale Land-Use Models and the role of Irrigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18994, https://doi.org/10.5194/egusphere-egu24-18994, 2024.

EGU24-20735 | ECS | PICO | BG8.10

Testing for adaptation in the observed corn and soy yields in the US Midwest 

Adarsh Raghuram and Ethan Coffel

The positive effects of warm temperatures on crop yields reverses beyond a critical temperature threshold, where sharp decrease in yields is observed for all crops. In the light of warming trends observed globally, adaptation of crops to extreme climatic conditions could be crucial for ensuring a stable food supply in the future. While numerous studies have shown the potential positive impact of adaptation on food security, there is limited evidence showing observed changes in the sensitivity of major food crops to high temperatures at national and global levels. In this study, we use regression models to examine the spatiotemporal variations in critical temperature threshold for corn and soy in the US Midwest. Further, we also examine changes in yield response to exposure to temperatures beyond the critical temperature threshold. Overall, our work tests for the presence of adaptation in the observed yield trends of corn and soy in the US Midwest. 

How to cite: Raghuram, A. and Coffel, E.: Testing for adaptation in the observed corn and soy yields in the US Midwest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20735, https://doi.org/10.5194/egusphere-egu24-20735, 2024.

EGU24-20927 | PICO | BG8.10

Simulating future Food Value Chain components through the integration of biophysical and techno-economic spatial models 

Edmar Teixeira, Sylvain Leduc, Shubham Tiwari, Florian Kraxner, Jing Guo, Sam McNally, Richard Yao, Xiumei Yang, Paul Johnstone, Thomas Sowersby, Richard Edmonds, Shane Maley, Abha Sood, James Bristow, and Derrick Moot

We describe the methodological development and preliminary results of a new spatial modelling framework to support the evaluation and design of novel Food Value Chains (FVC). The sustainability of future FVCs will depend on how effectively these can be adapted to environmental (e.g., climate change) and socio-economic (e.g., resource access and dietary preferences) changes projected for coming decades. Our approach aims to account for the spatial and temporal complexity inherent to both biophysical (e.g., climate, genotypes and soils) and techno-economic (e.g., processing technologies and markets) components of FVCs to optimise supply- (e.g., production areas) and demand- (processing-plant locations) across landscapes. For that, we integrated georeferenced biophysical outputs of a process-based agricultural model (Agricultural Production Systems sIMulator, APSIM-NextGeneration) into a spatial techno-economic model (IIASA-BeWhere). We test the approach through a case-study to evaluate a novel (hypothetical) FVC to produce plant-based proteins from lucerne crops (Medicago sativa) across New Zealand’s agricultural landscapes. Results highlighted spatial protein production patterns driven by changes in crop canopy expansion and net carbon assimilation, with lower yields estimated in cooler and dryer environments, particularly when water supply was limited under rain-fed (non-irrigated) conditions with soils of low water holding capacity. Spatial variability in protein yields, production costs and emissions estimated by APSIM-NG running in the ATLAS framework were then used as inputs by BeWhere to optimise the location of production areas and protein-processing plants. We discuss potentials, limitations, and future development areas of this approach.

How to cite: Teixeira, E., Leduc, S., Tiwari, S., Kraxner, F., Guo, J., McNally, S., Yao, R., Yang, X., Johnstone, P., Sowersby, T., Edmonds, R., Maley, S., Sood, A., Bristow, J., and Moot, D.: Simulating future Food Value Chain components through the integration of biophysical and techno-economic spatial models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20927, https://doi.org/10.5194/egusphere-egu24-20927, 2024.

EGU24-1586 | ECS | Orals | BG3.35

Assessing Nitrous Oxide Emissions from Agricultural Soil: A Comparison of Two Grass-clover Proportions 

Meng Kong, Søren O. Petersen, Jørgen Eriksen, and Christian Dold

The inclusion of grass-clover (GC) leys in crop rotations on dairy farms may contribute to climate change mitigation by facilitating carbon sequestration in soils. A long-term experiment in Denmark found that soil organic carbon (SOC) and soil total nitrogen (STN) increased with the proportion of GC (i.e., 2 and 4 years of GC in a six-year rotation) from 2006 to 2020. However, the incorporation of GC residues may potentially increase nitrous oxide (N2O) emissions due to the increased SOC and STN stocks. Yet, limited information exists regarding N2O emissions with different proportions of GC. We hypothesized that N2O emission will increase with more GC years in the rotation. This study aimed to quantify the emissions of N2O in two long-term crop rotations with different proportions of GC years (1/3 or 2/3), and all crops present each year. A one-year experiment is currently conducted including the rotation year preceding, and the year following GC cultivation where spring barley is cultivated, in both crop rotations (n=2, total: 8 plots). Emissions of N2O were quantified starting from April 2023 (day of year, DOY 111). Surface N2O fluxes were measured with the LI-7820 N2O/H2O trace gas analyzer connected to the 8200-01S Smart Chamber (LI-COR Biosciences, Lincoln, NE, USA). Linear mixed models were used to analyze N2O with crop rotation (1/3 or 2/3 GC) and rotation year (pre- or post-GC) as fixed effects and sampling date and block as random effects. Preliminary results showed elevated N2O fluxes (up to 443 ug N2O-N m-2 h-1) with a longer high-flux period in post-GC rotation years (DOY 111-151), than pre-GC years (DOY 111-139). The highest cumulative emission was 420 mg N2O-N m-2 in the post-GC year of DOY 320 in 1/3 GC. For pre-GC in 1/3 GC, pre-GC and post-GC in 2/3 GC, emissions were 249, 341 and 252 mg N2O-N m-2, respectively. For both N2O fluxes and cumulative emissions, the 1/3 GC rotation was significantly higher (p<0.01) than the 2/3 rotation. In addition, the N2O fluxes and cumulative emissions in the post-GC year were significantly (p<0.01) higher than the pre-GC year in the 1/3 GC crop rotation, while the years pre- and post-GC showed no difference in rotation with 2/3 GC. In contrast to our initial hypothesis, the preliminary results did not show higher N2O emissions with increased GC years. This currently suggests that the 2/3 GC inclusion in crop rotations has a greater potential for climate mitigation as compared to 1/3 GC. Further investigations will focus on the drivers of N2O emissions and the climate mitigation potential, considering both C sequestration in soil and N2O emissions in the long term.

How to cite: Kong, M., Petersen, S. O., Eriksen, J., and Dold, C.: Assessing Nitrous Oxide Emissions from Agricultural Soil: A Comparison of Two Grass-clover Proportions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1586, https://doi.org/10.5194/egusphere-egu24-1586, 2024.

EGU24-3488 | ECS | Posters on site | BG3.35

Positive mitigation effects of glacial rock flour (GRF) addition on ecosystem CO2, CH4 and N2O fluxes – first results from a gradient experiment 

Qiaoyan Li, Klaus Steenberg Larsen, and Christiana Amalie Dietzen

The application of ground silicate minerals to agricultural ecosystems has recently gained popularity as a mechanism for CO2 removal via enhanced mineral weathering that also has the potential to provide valuable co-benefits, including improved crop yields and reduced emissions of other greenhouse gasses. In Greenland, finely grained glacial rock flour (GRF) is naturally generated in vast amounts by glacier movement causing bedrock erosion and deposition. The natural production of GRF means that less energy is needed for grinding the rock material prior to field application. To quantify the influence of GRF on ecosystem carbon balance and greenhouse gas emissions, we applied 10 to 50 t GRF ha-1 yr-1 to an agricultural field in Denmark in a gradient setup with 5 levels plus combinations with fertilizers. Preliminary results of the CO2 fluxes measured by a combination of automated and manual chamber measurements, show that gross primary productivity (GPP, carbon uptake) and ecosystem respiration (Reco, carbon release) both increased gradually with the increased addition of GRF leading to a slightly increased net ecosystem uptake of CO2. In contrast, CH4 and N2O emissions showed a negative response trend with the increasing addition of GRF. The annual quantifications of ecosystem carbon balance and greenhouse gas emissions need further observations including effects during the non-growing season to be finalized. However, our initial results support the hypothesis that silicate mineral amendment overall may enhance CO2 removal in agricultural settings and reduce greenhouse gas emissions, and therefore may be a useful tool for improving the capacity of farmlands to serve as a greenhouse gas sink.

How to cite: Li, Q., Larsen, K. S., and Dietzen, C. A.: Positive mitigation effects of glacial rock flour (GRF) addition on ecosystem CO2, CH4 and N2O fluxes – first results from a gradient experiment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3488, https://doi.org/10.5194/egusphere-egu24-3488, 2024.

EGU24-5275 | Posters on site | BG3.35

Impact of management and boreal climate on GHG exchange from Finnish grasslands on mineral and peat soils 

Narasinha Shurpali, Olli Peltola, Tulasi Thentu, and Perttu Virkajärvi

Grasslands are a key component of boreal agriculture and can play a significant role in soil carbon sequestration and mitigation. Grasslands have the potential to store substantial amounts of carbon in their roots and soil, making them important for soil carbon sequestration. Finland, located in the boreal climate zone, is known for its milk production with one of the highest per cow milk yields in Europe. Milk production in Finland relies heavily on grassland management. The growing season is short and varies from 105 days in the north to 185 days in the south. Finnish grasslands are managed on two types of soils: mineral soils and organic soils. Mineral soils are typically well-drained and have a low organic matter content, whereas organic soils are characterized by high organic matter content and high-water retention capacity. Therefore, we have initiated a long-term GHG monitoring framework for a sustainable grassland management and agriculture at the Natural Resources Institute Finland (Luke) across several agricultural research sites in Finland. The results presented in this study will shed light on the variability of GHG-fluxes from grasslands on different soil types and on the key drivers of the temporal and site variability of GHG-fluxes in a comparative way.

How to cite: Shurpali, N., Peltola, O., Thentu, T., and Virkajärvi, P.: Impact of management and boreal climate on GHG exchange from Finnish grasslands on mineral and peat soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5275, https://doi.org/10.5194/egusphere-egu24-5275, 2024.

EGU24-6572 | ECS | Posters virtual | BG3.35

Soybean growth and nitrous oxide emissions in response to tillage and crop rotation 

Folahanmi Adeyemi

Global climate change is forcing different sectors including agriculture to come up with mitigation strategies. Nitrous oxide is the most potent greenhouse gas that contributes to global warming and is mainly produced from agricultural soil management. Two mitigation strategies to potentially reduce nitrous oxide emissions while maintaining cash crop yields are (i) shifting from conventional tillage to no-till and (ii) incorporating winter rye (Secale cereale L.) into corn (Zea mays L.)-soybean (Glycine max L.) rotation as a typical production system in the Midwest, USA. We harnessed a long-term trial to evaluate soil N dynamics, moisture and temperature, soybean production, and nitrous oxide emissions during 2020 and 2022 growing seasons. Treatments were two tillage factors (no-till and conventional chisel-disk) and two cover crops (winter rye and a no-cover crop control) arranged in factorial design with three replications. Results indicated that in 2020, no-till-no-cover crop had less nitrous oxide fluxes than the winter rye treatments, however it had higher N2O-N losses than 2022.  A combination of winter rye-no-till provided similar soybean morphology, shoot biomass and grain yield compared to a tillage-based system with no cover crop but promoted soybean root biomass leading to greater carbon inputs. These results indicate the tradeoffs in benefits of winter rye in soybean cropping systems.

How to cite: Adeyemi, F.: Soybean growth and nitrous oxide emissions in response to tillage and crop rotation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6572, https://doi.org/10.5194/egusphere-egu24-6572, 2024.

EGU24-7225 | ECS | Posters on site | BG3.35

Environmental Footprint of Reactive Nitrogen in Indian Agricultural Sector: An Extended Input-Output Analysis   

Deepakshi Babbar, Shilpi Kumari, and Srinidhi Balasubramanian

Food, feed, and fuel production are vital for human well-being. Yet current agricultural practices have resulted in extensive multi-media damages, primarily due to reactive nitrogen (Nr) emissions (NH3, N2O, NOx). Managing Nr sustainably to alleviate food and feed insecurity has been identified as a Grand Engineering Challenge. Systematically analysing source contributions, flows, and impacts of Nr is crucial for an agro-dominant country like India that faces the dual challenge of food and environmental security for 1.6 billion people by 2050. Here, we construct an Environmentally Extended Input-Output model for Nr in the Indian agriculture sector (cropland + livestock) for 2000–2020. Our findings indicate an increase in total N input to cropland from 23 Tg-N to 33 Tg-N (2000–2020), largely attributed to synthetic fertilizers (62%), biological N fixation (17%), atmospheric nitrogen deposition (11%), and livestock manure use (7%). Despite these increases, nitrogen use efficiency has only improved marginally (45% in 2000 to 57% in 2020). Nr losses to hyrosphere constitute 55%-60% of total N, with atmospheric emissions accounting for 40%-45% of total N. Key pollutants include nitrites/nitrates lost through runoff (40%), NH3 emissions (34%), and NO3 leakage to groundwater (20%). Noteworthy are NH3 emissions from fertilizer (55%) and manure (28%) application, and nitrogen deposition (12%).

Flows from the cropland sector serves as an input to the livestock sector, e.g., the production of grain and straw as feed to turn plant protein into animal protein, with efficiency varying from 4% to 10%. The type of animal and manure management systems and practices influences the N flow outputs from the livestock sector. Nitrogen within the remaining fraction (90–96%) is found in urine and dung, leading to potential nitrogen losses, i.e., 13.7TgN in the year 2020 due to the volatilization, leaching, and runoff as a result of application on cropland and manure management system of manure. Bovine animals have the largest share in manure N production, i.e., non-dairy cattle (37%), dairy (20%), and buffalo (26%), which constitute 83% of the total manure N production. Of the total produced manure (17Tg-N), 80% is produced in agriculture, and 20% is in pastoral areas. Of the agriculturally produced region, 30% undergo manure management system for treatment, i.e., 4TgN, while 70% are used for fuel combustion. Manure subjected to treatment is reintegrated into cropland at a rate of 52%, with approximately half being environmentally lost. Of this loss, 27% is attributed to atmospheric dissemination, comprising 22% as NH3 resulting from volatilization and 5% through direct emissions of N2O. Furthermore, 22% of the nitrogen is lost to the hydrosphere, distributed as 19% through runoff (0.8TgN) and 3% (0.1TgN) via NO3- leaching.   Opportunities to alleviate N losses and boost feed conversion efficiency involve refining animal feed composition and the herd's genetic potential. However, a challenge remains in upgrading manure management practices. Our study constraints national-scale inputs, accumulation, and flows of Nr in Indian agriculture to enable a holistic approach to co-develop agriculture and environmental policies while identifying levers to enable greener agricultural production practices.

How to cite: Babbar, D., Kumari, S., and Balasubramanian, S.: Environmental Footprint of Reactive Nitrogen in Indian Agricultural Sector: An Extended Input-Output Analysis  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7225, https://doi.org/10.5194/egusphere-egu24-7225, 2024.

Global warming, mainly caused by greenhouse gas (GHG) emissions, is one of the major concerns of the current society. Accurate estimation of GHG emissions in various fields can help governments and international organizations to formulate emission reduction strategies.The main objectives of this study were to estimate CH4 and N2O emissions from rice-wheat crop fields using IPCC2006 Tier2 approach and DNDC model, and to compare the performance of the two methods; and to evaluate the accuracy of GHG emissions of the DNDC model with rotational and non-rotational simulation scenarios. In this study, we conducted a rice-wheat rotational field experiment from 2015 to 2018 to determine CH4 and N2O fluxes periodically using static chamber-gas chromatography measurement and analysis system. On this basis, combined with field management and meteorological data, we simulated GHG emissions from rotational and non-rotational crop scenarios using the IPCC2006 Tier2 approach and the DNDC model. The results show that (1) the DNDC model can simulate the time series of paddy CH4 and N2O emission fluxes and winter wheat N2O emission fluxes with estimation errors of -4.8%, -11.6%, and -10.8%, respectively, and the modeling accuracy is better than that of the IPCC2006 Tier2 approach; (2) the accuracy of the DNDC model for simulating the GWP under the rotational cropping scenarios was higher than that of the IPCC2006 Tier2 approach, the relative errors of GWP simulation in the DNDC model were -5.9% and -21.7% for rice and wheat fields, respectively; (3) the relative errors of winter wheat cumulative CH4 emissions in the rotational cropping scenario in the DNDC model were higher than those in the non-rotational cropping scenario, and the relative errors of cumulative emissions of other GHGs in the rotational cropping scenario were lower than those in the non-rotational cropping scenario.This study provides some references for estimating regional agricultural GHG emissions and formulating emission reduction targets and policies.

Keywords: Rice-wheat rotation; DNDC; IPCC2006 Tier2; Greenhouse gases

How to cite: Yuming, Y.: Study on the difference of rice-wheat rotation system greenhouse gas estimation by different simulation methods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7554, https://doi.org/10.5194/egusphere-egu24-7554, 2024.

EGU24-7588 | ECS | Orals | BG3.35

Modelling CO2 and N2O emissions from a tropical semi-arid parkland cultivated with groundnut and millet 

Yélognissè Agbohessou, Seydina Ba, Fabien Ferchaud, Joël Léonard, Sidy Sow, Fredéric Bouvery, Maxime Duthoit, Claire Delon, Rémi Vezy, Gatien N. Falconnier, Eric Mougin, Daouda Ngom, Simon Taugourdeau, and Olivier Roupsard

Agriculture contributes to climate changes through land use changes and greenhouse gas emissions. Models can provide crucial insights into the extent of this contribution; however, their effectiveness relies on proper evaluation within the application context. Moreover, crop models that can simulate greenhouse gas emissions have not been extensively tested for the semi-arid tropics. We calibrated and used the STICS soil-crop model to explore the skills of the model to reproduce observed variations in greenhouse gas emissions for a millet-groundnut rotation in an agro-silvo-pastoral parkland dominated by Faidherbia albida trees located in central Senegal. Model simulations were compared with observations of soil temperature, soil water content, N2O and CO2 emissions, aboveground and belowground biomass of millet and groundnut, collected between 2018 and 2022. CO2 emissions were simulated with a two-step approach. Initially, STICS simulated crop leaf area index and biomass (aboveground and belowground), and soil heterotrophic respiration. These variables were then integrated into an independent autotrophic respiration module, and summed with STICS simulated' heterotrophic respiration. In general, the STICS model tends to underestimate the observed minimum soil water content (wilting point) during the dry season and overestimate the observed soil water content after the wet season. However, the temporal dynamics of the soil temperature in the upper layer (0-30 cm) are generally well-represented by the model throughout the simulation period. Simulated N2O emissions were generally consistent in terms of magnitude compared to on-site measurements, although the model currently does not account for N2O absorption by the soil (i.e. negative fluxes). For instance, the simulated peak reached 0.041 kg N ha-1 d-1, while the observed peak was 0.048 kg N ha-1 d-1. The simulated average annual N2O emissions for the period 2018 to 2022 amounted to 0.368 kg N ha-1 yr-1. Simulated CO2 emissions were also comparable to on-site measurements (2021: EF = 0.63, BIAS = -0.75 kg C ha-1 d-1, and RMSE = 15.01 kg C ha-1 d-1; 2022: EF = 0.56, BIAS = -3.25 kg C ha-1 d-1, and RMSE = 5.01 kg C ha-1 d-1). These results indicate that the STICS model can be used to explore the impact of land use and crop management changes on greenhouse gas emissions in a tropical semi-arid context.

How to cite: Agbohessou, Y., Ba, S., Ferchaud, F., Léonard, J., Sow, S., Bouvery, F., Duthoit, M., Delon, C., Vezy, R., Falconnier, G. N., Mougin, E., Ngom, D., Taugourdeau, S., and Roupsard, O.: Modelling CO2 and N2O emissions from a tropical semi-arid parkland cultivated with groundnut and millet, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7588, https://doi.org/10.5194/egusphere-egu24-7588, 2024.

EGU24-8547 | ECS | Orals | BG3.35

Greenhouse gas emissions under nanomaterial co-application with reduced fertiliser input 

Jessica Chadwick, Iseult Lynch, and Sami Ullah

With the advent of synthetic nitrogen fertiliser, the proportion of reactive nitrogen (Nr) in terrestrial ecosystems has doubled. While this has enabled high crop productivity, it has also triggered mass environmental effects, with almost half of the applied fertiliser lost into air (in the form of N2O or NH3) as well as nutrient runoff and leaching of nitrates into water bodies. Nanomaterials present an opportunity to improve nutrient use efficiency of crops and minimise agricultural pollution via reducing losses. This study screened engineered nanomaterials, including zeolites and metal oxides, to assess their impact on greenhouse gas (CH4, N2O and CO2) emissions when co-applied with NPK (nitrogen, phosphorus and potassium) fertiliser to grow lettuce (Lactuca sativa). The findings show that there are highly differential emissions from soils with nanomaterial co-application with reduced fertiliser application rates. One of the zeolites used, ZSM-5-15, when co-applied with a reduced dose (50% of RB209 nutrient management guide recommendation) of NPK fertiliser, increased N2O emissions relative to reduced NPK fertiliser alone and negative controls. Another zeolite, BEA-19, had limited effect on either NH3 or N2O volatilization, but did reduce the concentration of ammonium in the leachate. Nitrate leaching gradually rose over the course of the 8-week experiment for full NPK fertiliser dose application, reduced NPK dose and negative control. This pattern was altered by BEA-19, triggering elevated nitrate leaching earlier in the experiment, peaking in week 1 compared to week 4 for other treatments. While nanomaterial treatment was able to increase lettuce biomass accumulation compared to full NPK and negative fertiliser treatments, understanding the impact of nanomaterials on N cycling has proven more complex. The mechanism for N loss from soils triggered by ZSM-5-15 application is unknown, potentially through impact on denitrifying enzymes. My work posits that the earlier release of nitrate from BEA-19 application is due to selective binding of the NPK to the nanomaterial surface. More data on nanomaterial endpoints is pending and may help elucidate the nature of this binding and nutrient release mechanisms.

How to cite: Chadwick, J., Lynch, I., and Ullah, S.: Greenhouse gas emissions under nanomaterial co-application with reduced fertiliser input, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8547, https://doi.org/10.5194/egusphere-egu24-8547, 2024.

EGU24-9530 | Orals | BG3.35

Effect of a salinity gradient on methane emissions in paddy rice: a mesocosm experiment 

Maite Martínez-Eixarch, Sruthi Padinhariyil, Yolanda Lucas, Míriam Guivernau, Carles Alcaraz, Lluís Jornet, Julie Garnier, Adrien Fernández, Joan Noguerol, and Marc Viñas

Rice is a crucial crop for food security, but it is also a significant source of anthropogenic greenhouse gas emissions, particularly methane (CH4). Projected sea level rise caused by climate change will impact on rice yield through increased salinity. On the other hand, increased salinity potentially mitigates CH4 emissions by inhibiting methanogenesis mediated by the dominance of sulphate-reducing bacteria. To investigate this dual effect, we conducted a mesocosm experiment creating a water salinity gradient with four levels: 2 ppm (control), 4 ppm, 6 ppm and 35 ppm (seawater). CH4 emissions, abundance and gene expression of microbial populations and grain yield were assessed.

The experiment took place in year 2022 at IRTA facilities (Spain) using a variety of japonica rice (Oryza sativa L.). Rice was grown following the standard practices, notably permanent flooding, and crop residue incorporation into the soil after the harvest. CH4 emissions were weekly assessed throughout the rice growing season (May to September) and the post-harvest (October to December). Gas samples were collected using gas chambers and analysed through gas chromatography. Yield and aboveground biomass were measured at harvest. Thereafter, crop residues in each mesocosm, where present, were incorporated into the soil. Soil samples for microbial analyses were taken twice during post-harvest:  6 days before the harvest and 28 days after straw incorporation.  The microbial community diversity was assessed based on 16S/ITS-metataxonomy of total (DNA) and metabolically active (cDNA) bacteria, archaea, and fungi, as well as the quantification of total bacteria (16S rRNA gene), methanogenic archaea (mcrA gene ), and sulphate-reducing bacteria (aprA gene) by qPCR.  The activity of methanogenic archaea and sulphate reducing populations were assessed by quantifying gene transcripts of mcrA and aprA by RT-qPCR.

Rice grain yield decreased by 30% with increasing salinity from 2 ppm to 4 ppm, while there was no yield above 6 ppm. The biomass of straw produced and then added into the soil declined along the salinity gradient: 72.9 ± 12.4 g and 49.8 ± 6.1 g at 2 ppm and 4 ppm treatments, respectively, and zero in the remainder. The results confirmed that salinity significantly reduces CH4 emissions, but the sensitivity of this response differed between the growing and post-harvest seasons. During the growing season, CH4 declined with increasing salinity, ranging from 8.0 ± 1.7 to 0.05 ± 0.02 mg CH4 m-2 h-1. However, in the post-harvest, no CH4 emissions were detected at water salinities above 4 ppm, in contrast to 14.8 ± 0.75 mg CH4 m-2 h-1 found at 2 ppm. In regard to the microbial processes, the abundance of methanogenic archaea declined with increased salinity and the gene expression was highly inhibited at salinities larger than 6 ppm. By contrast, the abundance of sulphate-reducing bacteria was preserved over the salinity gradient while gene expression remained active, though slightly reduced from 6 ppm, probably due to the lower availability of organic carbon at the highest salinities.

Acknowledgments: The study has been carried out within the framework of the MIC-RICE project PID2019-111572RB-I00 funded by AEI/10.13039/501100011033

How to cite: Martínez-Eixarch, M., Padinhariyil, S., Lucas, Y., Guivernau, M., Alcaraz, C., Jornet, L., Garnier, J., Fernández, A., Noguerol, J., and Viñas, M.: Effect of a salinity gradient on methane emissions in paddy rice: a mesocosm experiment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9530, https://doi.org/10.5194/egusphere-egu24-9530, 2024.

EGU24-10130 | ECS | Posters on site | BG3.35

Understanding the influence of soil compaction on greenhouse gas emissions 

Elysia Lewis, Matteo Longo, Sebastiano Rocco, Nicola Dal Ferro, Miguel Cabrera, Barbara Lazzaro, and Francesco Morari

Soil structure plays a crucial role in determining greenhouse gas (GHG) emissions from agricultural activities. Changes in soil structure, such as compaction, can alter the factors that govern GHG fluxes, leading to an increased potential for emissions. The extent to which soil compaction explains GHG emissions is still under investigation. To address this knowledge gap, a two-year experiment was conducted in Northeast Italy to examine the influence of soil compaction on GHG emissions. The experimental site comprised of 20 lysimeters representing five different cultivation systems, each with four replicates: bare soil (BS), conventional (CV), conventional + with cover crop (CC), conservation with shallow compaction (0-25 cm, CA1), and conservation with deep soil compaction (25-45 cm, CA2). Maize was cultivated as the main crop in 2022, followed by grain sorghum in 2023, with solid digestate (300 kg N ha-1) originated from mixed agricultural waste used for fertilization. Winter wheat served as a cover crop where necessary. Continuous automatic measurements of CO2, N2O, and CH4 emissions were collected using a non-steady state through-flow chamber system and an FTIR gas analyzer, enabling the capture of up to seven fluxes per day for each replicate. Additionally, water-filled pore space (WFPS) and soil temperature were continuously monitored in the 0-30 cm soil profile using Time Domain Reflectometry (TDR) sensors and thermocouples. Cumulative CO2 reached its peak under CV, followed by CC. Notably, observable N2O emissions were predominantly detected in the two weeks following fertilization with peaks reaching 0.8 kg N-N2O ha-1d-1 under CC, while CA1 and CA2 exhibited lower emissions. Conversely, CH4 emissions were negligible, and the soil primarily acted as a sink. The study provides crucial insights for sustainable agriculture by highlighting the impact of soil compaction on GHG.

How to cite: Lewis, E., Longo, M., Rocco, S., Dal Ferro, N., Cabrera, M., Lazzaro, B., and Morari, F.: Understanding the influence of soil compaction on greenhouse gas emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10130, https://doi.org/10.5194/egusphere-egu24-10130, 2024.

EGU24-10183 | Orals | BG3.35

Online pesticide concentration and fluxes measurements over crops with a PTRMS shows unexpected volatilisation rates 

Benjamin Loubet, Florence Lafouge, Sandy Bsaibes, Carole Bedos, Céline Decuq, Baptiste Esnault, Raluca Ciuraru, Julien Kammer, Raffaella Vuolo, and Valérie Gros

Pesticide usage has been expanding since the 1950s. Their use has been known to harm human and environmental health for decades. Pesticide volatilisation to the atmosphere is a known process which is however not well documented, especially for periods beyond a few days after pesticide application. This is partly due to the difficulty to measure gaseous pesticides concentration in the atmosphere continuously for long time periods. Indeed, current state-of-the-art measurements is made by thermo-desorption gaseous chromatography involving semi-manual sampling with cartridges.

In this study, we report first monthly outdoor online measurement of concentrations and volatilisation of one fungicide and two herbicides by proton transfer reaction, quadrupole injection, time of flight, mass spectrometry (PTR-QI-TOF-MS). The fungicide Chlorothalonil was measured over a wheat field in spring, while the herbicides Prosulfocarb and Pendimethalin were measured over a bare soil in autumn. Comparison with state-of-the-art TD-GC-MS and calibration by a home-made permeation system proved the PTRMS to be adapted for pesticides measurements.

Maximum measured concentrations ranged from 12 ppt for Chlorothalonil to 600 ppt Prosulfocarfb. Maximum daily volatilisation fluxes ranged from 35 ng m-2 s-1 for Chlorothalonil to 350 ng m-2 s-1 for Prosulfocarb. We found that volatilisation of Chlorothalonil lasted more than three weeks, leading to up to 50% of the applied quantity volatilised, a duration and an amount much larger that what has been reported before.

Volatilisation of pesticides may contribute much more significantly than expected to atmospheric burden, and be wet and dry deposited over larger areas. Further PTRMS pesticides measurements should be done to gain insight into pesticide transfer to the environment, and better characterize human exposure to these harmful compounds.

How to cite: Loubet, B., Lafouge, F., Bsaibes, S., Bedos, C., Decuq, C., Esnault, B., Ciuraru, R., Kammer, J., Vuolo, R., and Gros, V.: Online pesticide concentration and fluxes measurements over crops with a PTRMS shows unexpected volatilisation rates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10183, https://doi.org/10.5194/egusphere-egu24-10183, 2024.

EGU24-10933 | ECS | Orals | BG3.35

Optimizing Ammonia Volatilization Simulation in Agricultural Soils: Advancements of the EPIC Model 

Andrea Gozio, Matteo Longo, Miguel L. Cabrera, Roberto César Izaurralde, David E. Kissel, Barbara Lazzaro, Nicola Dal Ferro, and Francesco Morari

Agriculture is responsible for about 94% of UE ammonia (NH3) emissions, notably from livestock, manure management and soil fertilization. NH3 volatilization is a significant cause of reactive nitrogen (N) loss, leading to lower fertilizer efficiency as well as environmental and health concerns. Loss predictions can be estimated using process-based biogeochemical models, but many of them lack precise estimations of NH3 volatilization. In this work, we modified the Environmental Policy Integrated Climate (EPIC) model incorporating a mechanistic sub-model to simulate NH3 volatilization following the application of N fertilizers in agricultural fields. The newly added algorithm in EPIC functions on an hourly time step and describes the ammonium (NH4+) adsorption by clay and organic matter and estimates the partitioning of total ammoniacal N into NH3 and NH4+ based on the pH of the soil solution. The sub-model then determines the NH3 concentration in the gas phase using Henry’s law and estimates NH3 emission using a mass transfer coefficient that considers the resistance in the turbulent and laminar layers. Additionally, the sub-model uses the soil’s pH buffering capacity to recalculate pH following hydrogen ion consumption by urea hydrolysis and hydrogen ion release by NH3 volatilization. The sub-model further integrates a reduction factor for volatilization to account for the effects of soil layer depth and the depth of fertilizer application. The new EPIC sub-model was validated using datasets from Veneto, NE Italy, and Georgia, USA. In Italy, NH3 volatilization was measured in four experiments, testing cattle slurry, farmyard manure, and mixed silage maize and animal slurry digestate. Whereas in Georgia, NH3 volatilization was examined following surface application of urea and poultry manure to grasslands. The new sub-model improved NH3 loss prediction, yielding reasonable hourly NH3 fluxes and cumulative volatilization estimates. As a result, the EPIC model exhibited lower prediction errors for soil mineral N (e.g. NH4+and NO3-) dynamics. While the new sub-model marks a notable advancement in accurately modeling N cycling, additional enhancements should prioritize certain modeling aspects, including slurry infiltration rates, NH3 fluxes within the soil profile, and the mitigation effects resulting from urease inhibitor application.

How to cite: Gozio, A., Longo, M., Cabrera, M. L., Izaurralde, R. C., Kissel, D. E., Lazzaro, B., Dal Ferro, N., and Morari, F.: Optimizing Ammonia Volatilization Simulation in Agricultural Soils: Advancements of the EPIC Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10933, https://doi.org/10.5194/egusphere-egu24-10933, 2024.

EGU24-11524 | ECS | Posters on site | BG3.35

Understanding soil health across greenhouse gas emissions and soil characteristics 

Susanne Wiesner, Shabda Gajbhiye, Shourya Mehta, Paul Stoy, and Alison Duff

Decades of intensive agricultural production, consisting of monoculture crops like corn (Zea mays), has led to a drastic decline in soil health, indicated by a reduction in soil carbon, nutrient holding and water holding capacity. Shifting management from monoculture crops to perennial crops could improve these soil characteristics and boost the resilience of agricultural systems to climate change. Furthermore, dairy livestock production systems are major greenhouse gas (GHG) emitters. GHGs from crop-livestock systems originate from enteric fermentation, manure storage, soils, and farm energy use. Nevertheless, US dairy herd sizes have not changed significantly in recent decades, suggesting that annual enteric fermentation emissions remained constant, while manure and soil emissions (i.e., CO2, N2O, CH4) increased from the intensive management, including tillage and the application of agricultural chemicals. However, soil emissions such as CO2 efflux (efflux) also consists of natural biogenic emissions from plant and microbial activity. Hence, an efflux may indicate greater soil health, suggesting root activity and high soil microbial abundance. Similarly, less variability in soil moisture and temperature could indicate high compaction and inferior soil structure. Understanding the multiple responses of soils to agricultural management is critical for developing strategies to improve soil health.

Here we established a nested treatment experiment with four block replications and three replicated plots per block (30 by 30 feet) using six different cropping systems (corn, corn with cover crop, corn intercropped alfalfa (Medicago sativa), alfalfa, intermediate wheatgrass (IWG, Thinopyrum intermedium), and a five species mixture of pasture grasses and forbs), to understand the system tradeoffs among soil health, forage quality and milk production in a dairy agricultural system. To quantify changes in soil health, structure, and soil GHG emissions, we planted corn on all plots in year 1 (2020) before planting other treatments in year 2 (2021). We collected data on soil nutrients and carbon content, soil microbial abundance and diversity, soil CO2 efflux, soil moisture and temperature, as well as forage samples and multispectral drone flights to assess forage quality.

Corn plots (monocultures and intercropped) had lower variability in environmental characteristics like soil moisture and temperature, while their magnitudes were elevated, indicating a more compacted and less aerated soil compared to plots with greater root density and lower bulk density (i.e., pasture plots). Similarly, corn plots respired significantly less CO2, both in years 1 and 2, compared to perennial crop plots, conforming with soil microbial data, which indicated lower microbial diversity in corn plots compared to pasture plots. While corn biomass was greater at the time of harvest compared to other crops, pasture and alfalfa plots accumulated half of the corn biomass throughout three harvest cycles and showed to have lower variability in yield, while also having higher nutritious value compared to corn silage, with implications for milk quality. Our findings suggest that efforts to make dairy operations more resilient to climate change and weather extremes should focus on more variables than just GHG emissions and soil carbon storage, to sustain agricultural production, human nutrition, and biogenic nutrient recycling into the future.

How to cite: Wiesner, S., Gajbhiye, S., Mehta, S., Stoy, P., and Duff, A.: Understanding soil health across greenhouse gas emissions and soil characteristics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11524, https://doi.org/10.5194/egusphere-egu24-11524, 2024.

EGU24-15750 | ECS | Orals | BG3.35

Assessing different IPCC Tier Approaches for estimating Methane Emissions in Vietnamese Rice Agriculture 

Chien Nguyen, Thi Bach Thuong Vo, Phuong Loan Bui, Van Trinh Mai, Tanh Nguyen, Klaus Butterbach-Bahl, Bjoern Ole Sander, Reiner Wassmann, Ralf Kiese, and David Kraus

The IPCC provides three distinct protocols (Tier 1-3) that can be used for reporting on greenhouse gas (GHG) emissions under the UNFCCC. While Tier 1 and 2 use relatively straightforward methods based on global and region-specific emission factors, Tier 3 is more complex and uses process models for emission estimation. Although Tier 3 is considered to have higher accuracy potential, its complexity requires expert knowledge and extensive input data, which is often not available, hindering widespread adoption.

This study critically evaluates all three Tier approaches for CH4 emissions from rice production in Vietnam, using the ecosystem process model LandscapeDNDC for the Tier 3 approach. As a first step, we evaluate all three approaches based on a comprehensive dataset covering 73 cropping seasons from 36 sites across Vietnam. On this basis, we show the extent to which Tier 3 performs better when considering commonly available information, and which information is most important to outperform simpler methods. As a second step, we present national CH4 emission inventories for each approach and show under which circumstances the approaches differ the most. We also present a web-based tool that improves the accessibility of Tier 3 applications for users who are not familiar with the application of a particular complex process model.

Our findings aim to provide valuable insights into the effectiveness of UNFCCC reporting approaches, particularly the under-researched Tier 3.

How to cite: Nguyen, C., Vo, T. B. T., Bui, P. L., Mai, V. T., Nguyen, T., Butterbach-Bahl, K., Sander, B. O., Wassmann, R., Kiese, R., and Kraus, D.: Assessing different IPCC Tier Approaches for estimating Methane Emissions in Vietnamese Rice Agriculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15750, https://doi.org/10.5194/egusphere-egu24-15750, 2024.

EGU24-16270 | ECS | Posters on site | BG3.35

Impacts of biochar on nitrous oxide emissions and ammonia volatilisation in wheat and maize cropping systems 

Ferdinand Hartmann, Heide Spiegel, Eugenio Diaz-Pines, and Rebecca Hood-Nowotny

Agriculture and other land use practices are major contributors to greenhouse gas emissions. To meet the needs of an increasing global food demand while mitigating climate change, sustainable agricultural practices are necessary. Biochar seems to be a promising tool to support this transition to sustainability in agriculture. The application of nitrogen fertilizers increases N2O emissions and NH3 volatilisation. Nitrous oxide (N2O) is a highly potent greenhouse gas and ammonia (NH3) can re-react with soil and forms N2O or can lead to other environmental issues in the surrounding. Besides its carbon sequestration potential, it is known that biochar can positively influence soil properties like water holding capacity, nutrient leaching and mitigation of nitrous oxide emissions and ammonia volatilisation. However, these effects depend on pedoclimatic conditions, the properties of the applied biochar, and other agricultural practises. Therefore, it is necessary to expand the knowledge of these effects, especially under field conditions, to generate valid estimates on biochar’s mitigation potential for N2O and NH3 emissions. A good and extensive data basis is essential for recommendations and a large-scale application in agriculture. In a two-year field experiment in Grabenegg (Lower Austria) we cultivated silage maize (Zea mays) in 2022 and spring wheat (Triticum aestivum) in 2023 with different organic (external organic matter, EOM) and inorganic (NPK) fertilisers. For the biochar treatments we applied 7 t/ha hardwood biochar additionally. The original soil was loamy, low in organic carbon and slightly acidic. We found substantial reductions with 36% (NPK) and 53% (compost) for N2O and 56% (NPK) and 40% (compost) for NH3 emissions. There are several factors discussed in literature how biochar mitigates N2O and NH3 emissions. We suggest that the immobilisation effect of biochar on NH4+ and NO3- (which was observed in the soil), and possibly an increased dinitrogen monoxide reductase activity are responsible for this reduction. Our data support that biochar can be a suitable amendment for highly productive agroecosystems where high amounts of fertiliser are needed and often applied at one timepoint. Still, further investigations on the long-term effect on emission mitigation of biochar and the mechanisms behind are necessary.

How to cite: Hartmann, F., Spiegel, H., Diaz-Pines, E., and Hood-Nowotny, R.: Impacts of biochar on nitrous oxide emissions and ammonia volatilisation in wheat and maize cropping systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16270, https://doi.org/10.5194/egusphere-egu24-16270, 2024.

EGU24-16666 | Posters on site | BG3.35

Modeling N2O, NH3 fluxes, and Nmin concentrations in agricultural soils treated with biogas digestate using a modified DNDC model 

Balázs Grosz, Jörg Michael Greef, Linda Tendler, Mahboube Jarrah, and Rene Dechow

The positive and negative effects of animal manure application to agricultural soils on soil inorganic nitrogen content, crop yield, ammonia (NH3), and nitrous oxide (N2O) emissions are well known and integrated into biogeochemical models. However, it is unclear if the effects of using digestate from biogas plants as fertilizer can be described by biogeochemical process models too. Since in Germany, the number of biogas plants increased drastically in the last two decades, there is a need for an evaluation and calibration of biogeochemical models for the application of digestate on arable land. For this purpose, we used data from a field experiment consisting of a control without fertilization, 3 treatments with mineral fertilizer, and 3 treatments with biogas digestate application (each with 60%, 80%, and 100% of maximum required N) on two cereal/maize crop rotations. Digestate was applied using trailing hoses. Results from experiments are used to calibrate and improve the biogeochemical model DNDCv.Can. Starting from a simplified description of O2 transport, a new sub-module quantifies O2 concentration by coupling decomposition with a 1-dimensional diffusion approach. Since the size of the anaerobic balloon calculated by the model influences many processes occurring in the soil, such as nitrification and denitrification, we hypothesize that a more realistic description of O2 concentration, together with a model calibration addressing the decomposition kinetics of digestate, will lead to a more precise process description and, thus, to a better estimation of N2O and, indirectly, NH3 gas fluxes, and to more reliable estimation of NO3- and NH4+ contents in the topsoil.

How to cite: Grosz, B., Greef, J. M., Tendler, L., Jarrah, M., and Dechow, R.: Modeling N2O, NH3 fluxes, and Nmin concentrations in agricultural soils treated with biogas digestate using a modified DNDC model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16666, https://doi.org/10.5194/egusphere-egu24-16666, 2024.

EGU24-17542 | ECS | Posters on site | BG3.35

Spatial and temporal variability of soil GHG fluxes of urban greens 

Xiao Bai, Lars Andreassen, Gülnur Dogan, and Klaus Butterbach-Bahl

Global urbanization has significantly affected land use, with former agricultural or forested land being used for human settlements and urban green spaces. How this urbanization may have affected the spatial and temporal patterns of soil greenhouse gas (GHG) fluxes, especially those of nitrous oxide (N2O), remains largely unexplored, although a recent study indicated that urbanization accelerates GHG fluxes from soils.

In this study, we investigated soil GHG fluxes at Aarhus University Park (AU Park), a public park located in a hilly landscape with different use intensities. Soil GHG fluxes were measured 2-3 times per week over a period of 7 months using a fast chamber approach at about 55 sampling points with different management, vegetation, and landscape position (uphill, slope, foothill, ponds). Specifically, we focused on the identification of GHG flux hot and cold spots, and thereby investigated the temporal persistence of such spatial emission patterns.

Our results show that GHG fluxes were highly variable over the observation period, but that major GHG flux hotspots, such as those near a pond, were hotspots at all observation times. In addition, we were able to relate the spatio-temporal variations in soil GHG fluxes to landscape parameters such as slope and exposition, and to soil parameters such as soil organic carbon concentration, pH, and texture.

Our measurements show that there are significant spatio-temporal variations in GHG fluxes in urban parks and that these variations are strongly influenced by environmental and landscape parameters. This observation may allow a better scaling of GHG fluxes of urban green spaces and thus a better assessment of how urbanization changes landscape fluxes.

How to cite: Bai, X., Andreassen, L., Dogan, G., and Butterbach-Bahl, K.: Spatial and temporal variability of soil GHG fluxes of urban greens, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17542, https://doi.org/10.5194/egusphere-egu24-17542, 2024.

EGU24-17763 | Orals | BG3.35

SmartField – Accounting and mitigation of N2O emissions and N budgets of agricultural soils in Denmark 

Klaus Butterbach-Bahl and Ann-Britt Ann Britt Værge

In Denmark, the agricultural sector contributes almost 1/3 of total GHG emissions, second only to the energy sector. As significant GHG emission reductions have been achieved for the energy sector, there is increasing pressure on the agricultural sector to achieve GHG reductions of about 55-65% in the coming years.

While the current GHG emission inventory for the agricultural sector at national level in Denmark is based on a combination of Tier 1 and Tier 2 methodology following the standard IPCC methodology, the vision is to report national soil N2O emissions to the UNFCCC at either Tier 2 or Tier 3 level, the latter being the preferred level for the authorities as they plan to incentivize farmers to reduce emissions based on predictive yield and N2O emission models.

Against this background, the Danish SmartField initiative aims to establish an innovative field-scale platform for testing and validating solutions to reduce N2O emissions from agricultural fields. The data obtained will be used to further develop modeling tools for scaling, design and targeting of incentives to be included in regulatory frameworks to encourage adoption of knowledge and solutions by farmers and to ensure that these measures are accurately reflected in national inventories.

The core activities of SmartField are to establish: 1) a field measurement infrastructure to provide state-of-the-art benchmark datasets of N2O fluxes and other N loss and turnover pathways (NH3 volatilization and deposition, NOx fluxes, NO3 leaching, harvest N, soil N stock changes) for the most prominent field management practices in Denmark, including testing of classical and novel mitigation measures, 2) a data assimilation and modeling hub with a consolidated framework to provide evidence-based models for N2O emission quantification and to test N2O mitigation measures at large scale in scenario studies, and 3) a science-policy-practice interface (SPPI) to exchange knowledge and information and to build a smooth interaction with agricultural decision and policy models.

This will ensure that SmartField develops and delivers an improved methodology for accounting N2O emissions at field and farm scale, upon which policy incentives can be developed for farmers to adopt technologies and management measures with verified emission reductions.

SmartField is led by the Danish Technological Institute (DTI) in collaboration with Aarhus University (AU), the University of Copenhagen (UCPH), Colorado State University (CSU), SEGES Innovation (SEGES) and the Danish Ministry of Food, Agriculture and Fisheries (MFAF).

 

Note, that final funding decision for SmartField is pending approval

How to cite: Butterbach-Bahl, K. and Ann Britt Værge, A.-B.: SmartField – Accounting and mitigation of N2O emissions and N budgets of agricultural soils in Denmark, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17763, https://doi.org/10.5194/egusphere-egu24-17763, 2024.

EGU24-18307 | ECS | Posters on site | BG3.35

Measuring ammonia losses from winter wheat with eddy covariance: a comparative analysis with the integrated horizontal flux method 

Sina Kukowski, Björn Kemmann, Pascal Wintjen, Jeremy Rüffer, Jens-Kristian Jüdt, Hannah Götze, Melanie Saul, Andreas Pacholski, Heinz Flessa, and Christian Brümmer

Primary sources of ammonia (NH3) emissions originate from agriculture, impacting the environment, climate, and human health, thereby concomitantly reducing fertilizer nitrogen use efficiency. Accurate measurements under field conditions are required to provide a basis process understanding and for recommendations to policymakers and farmers. However, uncertainties remain regarding the accuracy and reliability of different low-cost NH3 measurement methods and new application of the eddy covariance method for emissions from low-intensity sources, such as synthetic fertilizers.

In this study we focused on the quantification of NH3 concentrations and fluxes determined by a quantum cascade laser spectrometer (QCL) with passivated inlet line within an eddy covariance setup and the comparison to low-cost passive diffusion samplers (ALPHA sampler) used for emission estimations with the integrated horizontal flux (IHF) method. Measurements were carried out in Central Germany during the vegetation periods in 2021 - 2023 in a winter wheat crop field, which received three urea fertilizer applications (to a total of 170 kg N ha-1) per year. The atmospheric NH3 concentrations measured by the QCL and the ALPHA samplers were compared. Then, the cumulative losses of NH3 over the measurement periods (March - July) in the different years (2021 - 2023) were calculated and compared between the two approaches (QCL-eddy covariance and ALPHA-IHF).

The NH3 concentration measurements showed that the ALPHA samplers generally yielded lower concentration values compared to the time-integrated QCL values. While the relative mismatch decreased with higher concentrations (>20 ppb), significant deviations were observed in the lower concentration regime. When ALPHA concentrations were corrected for measurement height to precisely align with QCL sampling height, a systematic underestimation was found. Reasons for the differences are currently under investigation and may be explained by the vertical and horizontal sampler separation from the main eddy flux tower and possibly due to varying environmental conditions.  

First results of NH3 eddy covariance fluxes (kg N ha-1 period-1) showed clear diurnal courses and emission peaks around noon on the days after each urea application throughout all years. High-frequency losses using a co-spectral method in the process of eddy flux calculation were estimated to be in the range of 25 to 30 %.

The performance of both methods (ALPHA-IHF and QCL-eddy covariance) in estimating NH3 losses from field-scale fertilizer applications is discussed, along with the sensitivity of input concentrations on NH3 emission estimates.

Our study is a step towards better comparability and integration of different NH3 measurement techniques and is expected to provide useful tools for robust estimation of NH3 emission factors for synthetic fertilizer applications.

How to cite: Kukowski, S., Kemmann, B., Wintjen, P., Rüffer, J., Jüdt, J.-K., Götze, H., Saul, M., Pacholski, A., Flessa, H., and Brümmer, C.: Measuring ammonia losses from winter wheat with eddy covariance: a comparative analysis with the integrated horizontal flux method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18307, https://doi.org/10.5194/egusphere-egu24-18307, 2024.

EGU24-18441 | Posters on site | BG3.35

Potential limitations of ammonia flux data beyond 72h after field application of slurries  

Albrecht Neftel, Christoph Häni, Thomas Kupper, Alex Valach, and Sasha Hafner

Ammonia volatilization from animal slurry applied to fields is a major source of air pollution in Europe. The ALFAM2 model  was developed for estimating ammonia emission from such sources and is used in research, as well as  for inventory calculations. Until now, the focus has been on emissions up to 72 hours after application (ALFAM2 model version 1.2), as it was generally assumed that over 90% of total emissions from the applied nitrogen occur during this period. The recently updated ALFAM2 model (version 2.3) now includes emission data up to 168 h after application, which has led the model to indicate substantial emissions between 72 and 168 h leading to a significant increase (<40 %) in total emissions.

However, ammonia fluxes from field applied slurry beyond 72 h after application are small and difficult to quantify accurately. A reassessment of the model input data for this period is required to determine whether the measured fluxes can still be causally attributed to the applied slurry and whether they differ significantly from the detection limit. We have examined the values included in the ALFAM2 database with regard to these questions, which has revealed patterns that lead to potential biases of the ALFAM-2 model results.

How to cite: Neftel, A., Häni, C., Kupper, T., Valach, A., and Hafner, S.: Potential limitations of ammonia flux data beyond 72h after field application of slurries , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18441, https://doi.org/10.5194/egusphere-egu24-18441, 2024.

EGU24-18445 | ECS | Orals | BG3.35

Greenhouse gas emissions from valley-bottom wetlands in an agricultural tropical highland system, Taita Hills, East Africa 

Sharon Gubamwoyo, Gretchen Maria Gettel, Damaris Guranya Kisha, Sonja Leitner, Gabriele Weigelhofer, and Thomas Hein

Globally, agriculture is one of the main drivers of wetland loss, leading to reduced soil carbon (C) and changes in greenhouse gas (GHG) emissions. In recent decades, wetland loss in Africa appears to be faster than the global losses, at about 43% compared to 35% globally. Valley-bottom wetlands in African highland regions support the livelihoods of >65% of the people who live there, but the effect of agricultural conversion on soil C and GHG emissions is understudied. This study compares GHG emissions between 1 intact, 12 agricultural (converted), and 10 recovered valley-bottom wetlands in Taita Hills, Kenya. Using the static gas chamber method, CO2, CH4, and N2O emissions were measured monthly from April 2023 to date along with soil NO3-N, NH4-N, soil C, and soil moisture. The results indicate that CO2 emissions from the converted wetlands is similar to recovered wetlands (mean = 183 ± 11 SE mg CO2-C m-2 h-1 and mean = 174 ± 13 SE mg CO2-C m-2 h-1 respectively; p > 0.05). This is in contrast with both CH4 and N2O emissions, which showed strong differences (p<0.005). The average CH4 emission in agricultural versus intact wetlands was mean = 0.31 ± 9 SE mg CO2-C m-2 h-1 and mean = 10 ± 1 SE mg CO2-C m-2 h-1, respectively, and the N2O mean emission was mean = 41 ± 0.2 µg N m-2 h-1 vs. 9 ± 3 µg N m-2 h-1, respectively. Addition of organic and inorganic fertilizer to the agricultural wetlands showed an increase in NO3-N in the soil and a high correlation with N2O.  High soil moisture levels and organic matter in the intact wetlands was a major contributing factor for the high CH4 emissions while low soil moisture in the converted wetlands led to low CH4 emissions. The soil organic carbon in the recovered wetlands was higher (Mean = 11 ± 0.1 SE Kg C m-2) compared to the converted wetlands (Mean= 8 ± 0.2 SE Kg C m-2) indicating higher carbon storage in the recovered wetlands. Overall, recovered wetlands contribute more to Global Warming Potential GWP (0.84 CO2-equivalents), but these estimates do not take into account losses in soil C storage, which amount to 1043 Kg C m-2 year-1. On-going data analysis and field work will use seasonal variation and take into account historical losses in C storage to refine annual emission estimates.


Presentation preference: Oral, On-site
Billing address: Sharon Gubamwoyo
Gregor-Mendel-Straße 33/ DG34 
Institute of Hydrobiology
1180 Vienna, Austria

How to cite: Gubamwoyo, S., Gettel, G. M., Kisha, D. G., Leitner, S., Weigelhofer, G., and Hein, T.: Greenhouse gas emissions from valley-bottom wetlands in an agricultural tropical highland system, Taita Hills, East Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18445, https://doi.org/10.5194/egusphere-egu24-18445, 2024.

EGU24-19113 | ECS | Posters on site | BG3.35

Reducing Excess Nitrogen Through Sustainable Farming Systems in Danish Agricultural Catchments 

Meshach Ojo Aderele, Jaber Rahimi, and Klaus Butterbach-bahl

Nitrogen pollution from livestock manure has emerged as an escalating global concern. Therefore, it is imperative to evaluate the cropping system that will facilitate the optimal utilization of livestock manure while minimizing the environmental impact. In the quest for sustainable agricultural practices, the incorporation of crop residues into soils and intercropping with catch crops, has been identified as promising strategies. Crop residue incorporation is a carbon farming practice that can have significant implications for both soil organic carbon (SOC) and nitrous oxide (N2O) emissions, while catch crops have been an essential tool for reducing nitrogen leaching.

This study uses the process-based biogeochemical model LandscapeDNDC to assess the environmental performance of different cropping systems in six representative Danish agricultural catchments (LOOPs). Generally, two fertilization strategies were distinguished: 1) fields receiving only a mixture of pig and cattle slurry (O-fields), and 2) fields (C-fields) receiving mineral fertilizer.

We tested eight scenarios of organic or conventional fertilized fields with or without crop residue incorporation and with or without catch crop (C/O ± CR ± CC)

The results revealed that organic fields demonstrated not only lower yield-scaled total emissions compared to conventional fields but also shows benefits in terms of net carbon balance. It therefore indicates that organic farming, especially when combined with crop residue and catch crop may lead to reduced nitrogen-related environmental impact while increasing yield.

How to cite: Aderele, M. O., Rahimi, J., and Butterbach-bahl, K.: Reducing Excess Nitrogen Through Sustainable Farming Systems in Danish Agricultural Catchments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19113, https://doi.org/10.5194/egusphere-egu24-19113, 2024.

EGU24-19925 | ECS | Posters on site | BG3.35

Photoacoustic spectroscopy based nitrous oxide measurement for field applications 

Csilla Gombi, Anna Szabó, Csaba Király, Vineet Srivastava, László Horváth, Edit Mikó, Gábor Szabó, and Zoltán Bozóki

The efficiency of fertilisers used worldwide is around 50%. It is a global environmental and economic problem, and intensive research is being conducted to find a solution. Nitrous oxide (N2O) is one of the nitrogen compounds released from fertilised soils. N2O is also emitted during the storage, treatment, and application of animal manure, in addition to fertilisers.

To reduce emissions, gas concentration and emission monitoring is important for accurate estimation of agricultural losses and to establish regulations for mitigation purposes. Laser spectroscopy-based methods provide in-situ, highly selective measurements with minimal maintenance, therefore they are promising techniques for monitoring N2O. A photoacoustic system based on a quantum cascade laser emitting around 7.72 μm was developed for N2O concentration measurement. Selectivity of the system was tested for water vapour (H2O), carbon dioxide (CO2) and methane (CH4). No cross sensitivity was found for H2O and CO2, nevertheless for CH4 it is not negligible, therefore a two-wavelength method is applied to correct for CH4. The system has a minimum detectable concentration of 8.5 ppb with an averaging time of 10 seconds. The system was calibrated from 0.05 ppm to 10 ppm, the response was found to be highly linear over the calibrated range (R2 = 0.9989).

A feasibility study was performed in a naturally ventilated free-stall dairy barn. Measurements were taken at a total of six measurement points, two of which were outside the barn and four inside the barn where spatial and temporal variations of N2O concentration were measured. Measurements taken outside the barn were considered to be close to the background (333 ppb). There, the measured concentration was 388 ppb ± 11 ppb. The measured mean N2O concentration inside the barn was 499 ppb ± 191 ppb during a three-hour period, and it varied between the near background concentration and 1 ppm. The system has a signal stability allowing for field applications; however, further tests are required to prove its applicability for quantifying biosphere-atmosphere exchanges of N2O. In the future our measuring system will be applicable to monitor N2O emission flux above crop fields and at livestock farms as well.

How to cite: Gombi, C., Szabó, A., Király, C., Srivastava, V., Horváth, L., Mikó, E., Szabó, G., and Bozóki, Z.: Photoacoustic spectroscopy based nitrous oxide measurement for field applications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19925, https://doi.org/10.5194/egusphere-egu24-19925, 2024.

EGU24-20143 | ECS | Orals | BG3.35

Biological amendments reduce soil N2O and CH4 emissions from slurry application under field conditions. 

Priya Pariyar, Mary Harty, and Magdalena Necpalova

Managed grasslands influence global warming by the exchange of the greenhouse gases (GHG) like carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). Application of animal waste, such as slurry, rich in inorganic nitrogen (N), may escalate soil processes and thus soil GHG emissions, particularly in organic systems that rely on input of animal manures without chemical inputs.

The objective of this study was to evaluate GHG mitigation potential of biological amendments that might be relevant to organic systems and their effects on soil N and N leaching over a 2-month period. To achieve this a plot-scale field experiment on a grassland site in Rosemount (Dublin, Ireland) was conducted over a period from May to July 2023. Closed static chamber technique was used to measure soil emissions of N2O, CH4 and CO2 with an increased sampling frequency after the slurry application. The dynamics of soil ammonium, nitrate and dissolved organic N were evaluated weekly in soil surface samples from 0-15 cm and in a 10-day interval in the leachate collected at a 50 cm depth. The grass yield was assessed twice during the course of the experiment. The plots were equally irrigated to stimulate soil processes during the dry periods. The treatments assigned to the plots in a randomised complete block design with 5 replicates included control (CON), cattle slurry (SLU) and slurry mixed with biochar (BIO; added at 2 kg/m2), neem oil high with slurry (NEEM H; added at 100% of N applied) and neem oil low with slurry (NEEM L; added at 20% of N applied). The slurry was applied at 50 kg N ha-1 to all plots apart from CON.

The application of neem oil at both levels of input consistently reduced soil N2O and CH4 daily emissions (p<0.001), while NEEM H at the same time increased soil CO2 daily emissions (p<0.001), compared to the SLU treatment. Biochar reduced soil CH4 daily emissions (p<0.001), but did not influence soil N2O and CO2 daily emissions relative to the SLU treatment.  

These results might be highly relevant for the climate-change policies relevant to organic farming systems and achievements of the national and international climate goals.

How to cite: Pariyar, P., Harty, M., and Necpalova, M.: Biological amendments reduce soil N2O and CH4 emissions from slurry application under field conditions., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20143, https://doi.org/10.5194/egusphere-egu24-20143, 2024.

In recent years, tremendous progress has been made in making the information gathered by sensors located on agricultural fields available almost immediately. Transferring the data directly to the cloud and rapidly presenting it to researchers, decision-makers, and farmers assist in optimally determining the timing, amount, and composition of fertigation. There have been ongoing efforts to reduce the technological and economic barriers to the efficient and reliable use of sensors that continuously monitor the root system’s heterogeneous and dynamic nature. Despite this, there are still many open questions related to determining the structure and installation locations of the sensors, the optimal algorithm with which the scheduling is determined, and how different sensing methods are combined to make optimal decisions.

Sensor development is usually done using in situ experiments. These complex and expensive experiments ultimately result in a long development time. Using numerical models may accelerate the development of sensing methods and the selection of the optimal algorithm for fertigation. Numerical models are used as a research tool for understanding, quantifying, and predicting phenomena and processes in the soil-plant-atmosphere system and for planning and managing water resources and their quality, including irrigation and drainage. Despite their complexity, numerical models are increasingly used thanks to a better understanding of water flow and solute transport processes, the development and improvement of mathematical methods for solving governing equations, and the accelerated development of computers capable of calculating different processes simultaneously in small intervals of time and space.

The presentation will review three sensing methods and present a combination of models that solve the water status and the fertilizer concentration in the root zone. The methods that will be reviewed are a) a tensiometer for measuring soil pressure heads, b) a suction cup for inferring soil solution concentrations, and c) a minirhizotron for evaluating the root system structure.

Determining optimal fertigation undoubtedly requires a multidisciplinary approach that considers the root zone’s physical, chemical, and biological characteristics. The combination of continuous measurements and numerical models may improve decision-making regarding resource application, thus optimizing the use of water and fertilizers while increasing economic profit and reducing environmental impacts.

How to cite: Lazarovitch, N. and Simunek, J.: Improving fertigation scheduling by combining continuous monitoring and numerical modeling of the root zone, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-158, https://doi.org/10.5194/egusphere-egu24-158, 2024.

EGU24-1571 | ECS | Posters on site | SSS9.17

NITRINET: A nitrification predictive model for reclaimed water distribution networks 

Ignacio Gómez Lucena, Emilio Camacho Poyato, and Juan Antonio Rodríguez Díaz

The present work consists of the development of a model (NITRINET) to simulate nitrification processes in reclaimed water distribution networks for agricultural irrigation. Due to water scarcity and climate change scenarios, irrigation with reclaimed water has gained interest worlwide, especially in arid and semi-arid regions, like the Mediterranean Basin. The Tintín Irrigation District distribution network (Montilla, southern Spain) was selected as case study. The importance of this model relies on the fact that the chemical composition of reclaimed water varies spatially along the distribution network. It has been observed that nitrate concentrations increase along the irrigation network in contrast to the reduction observed in the ammoniacal forms. It confirms that nitrification processes are occurring inside the pipes. To carry out precision fertigation strategies (fertilization and irrigation simultaneously) and optimize the amount of fertilizer applied it is necessary to determine the concentration of nutrients present in the water arriving at each farm. The nutrients that reclaimed water already carries must be considered when planning fertilization. This allows for a significant reduction in the amount of fertilizer applied to the soil, which has a positive impact both on the environment and on the farmer’s economy. Simulations performed with NITRINET have shown promising results, predicting water pH and the concentration of ammoniacal nitrogen (NH4+-N) and nitric nitrogen (NO3--N) in irrigation water arriving at farms with a mean absolute error of 0.34, 1.46 mg·L-1 and 1.23 mg·L-1, respectively. The main purpose of NITRINET is that it can be used as a Decision Support System when planning fertilization at irrigation district level. The findings of this work suggest that spatio-temporal variability of water quality must be considered when reclaimed water is used for irrigation, especially in big irrigation districts with long pipe distances. 

How to cite: Gómez Lucena, I., Camacho Poyato, E., and Rodríguez Díaz, J. A.: NITRINET: A nitrification predictive model for reclaimed water distribution networks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1571, https://doi.org/10.5194/egusphere-egu24-1571, 2024.

EGU24-1578 | ECS | Orals | SSS9.17

From sensors to decisions: Data flows to enhance irrigation efficiency for smallholder orchards 

Felix Thomas, Juan Gabriel Pérez Pérez, Luis Bonet Pérez de León, Amparo Martínez-Gimeno, Daniela Vanella, Simona Consoli, Juan Miguel Ramírez Cuesta, Hicham Elomari, Abousrie Farag, and Ulrike Werban

In the Mediterranean area, agriculture is subject to numerous demands caused by the interplay of climate change, population growth, changing food production patterns and the increasing need for nature conservation measures, enforcing an efficient usage of resources and the creation of resilient production systems. To ensure a more sustainable water use, water policies have been adopted in the European Union as well as in Northern Africa countries, such as Morocco and Egypt as irrigation is the largest water user in the Mediterranean region. Small farmers make up to two thirds of the agricultural areas and are therefore an important part of areas agricultural community. Estimates see up 35% possible water savings could be achieved by more efficient irrigation systems. New technologies and practices are currently adopted mostly by large farms. The challenge is therefore to increase the usage of efficient irrigation techniques by small farmers. We present a concept of data handling in a data chain, from the collection in the field towards calculated irrigation recommendations that are provided via mobile application. The idea behind it is to provide an irrigation management tool that aims to overcome barriers in adapting new technologies for smallholders. It is designed to provide irrigation recommendations for orange and olive orchards based on a bottom-up approach. The derived irrigation recommendations are dependent on the available input data based on sensor systems: the FAO-56 approach based on climate data, or a soil water balance model relying on soil moisture data. As the calculation of irrigation recommendations is based on the collected climate and soil moisture data, we are focusing on the possibilities of automated data quality control and the methods and obstacles of the data handling when providing the recommendations. The final product is derived in form of an application for mobile devices that is intuitive and easy to use. The data handling is hereby done using the python programming language and RESTful application programming interfaces, and the transfers are executed periodically using dockerized applications. The main advantage of the proposed workflow is the possibility to integrate data from a variety of sensors and platforms and the access for smallholders can be done via mobile phones. This way, the currently measured data on the agricultural fields and up-to-date irrigation needs are easily accessible. The system is currently under validation. We present the whole framework, starting at measured values by sensors and ending in the irrigation recommendation for the farmers available in the App.

How to cite: Thomas, F., Pérez Pérez, J. G., Bonet Pérez de León, L., Martínez-Gimeno, A., Vanella, D., Consoli, S., Ramírez Cuesta, J. M., Elomari, H., Farag, A., and Werban, U.: From sensors to decisions: Data flows to enhance irrigation efficiency for smallholder orchards, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1578, https://doi.org/10.5194/egusphere-egu24-1578, 2024.

EGU24-1780 | ECS | Posters on site | SSS9.17

A computational framework for irrigation scheduling of a winter wheat – summer maize rotation system 

Xiangyu Fan and Niels Schütze

One of the solutions for the current problem of limited arable land and growing demand for food is the increase of the land use intensity, e.g., by crop rotation. However, it can lead to excessively high agricultural water demand. We evaluate a winter wheat-summer maize crop rotation system, the main cropping system in the North China Plain, and develop a computational framework for optimal irrigation of two consecutive crop growth periods within a single year. The framework considers the impact of climate variability and considers limited agricultural water allocation.  In a case study for a site in the North China Plain, the framework is implemented using Aquacrop-OS that simulates the soil water balance and the interactions between two consecutive cropping seasons. A two-stage optimization ensures the maximum global crop water productivity, considering the food risk and yield stability. The developed framework can be used for optimal irrigation scheduling and as a tool for estimating minimum irrigation water demands and crop productivity for more sustainable water resources management on a regional level.

How to cite: Fan, X. and Schütze, N.: A computational framework for irrigation scheduling of a winter wheat – summer maize rotation system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1780, https://doi.org/10.5194/egusphere-egu24-1780, 2024.

EGU24-4157 | ECS | Orals | SSS9.17

Establishing management zones for irrigation using soil properties and Remote Sensing 

Faten Ksantini, Ana M. Tarquis, Andrés Almeida-Ñauñay, Ernesto Sanz, and Miguel Quemada

Soil texture influences many other soil attributes, including its physical, chemical, and biological characteristics. Soil texture dictates vital factors such as aeration, nutrient, water availability, and heat retention. These aspects collectively impact various aspects of plant life, encompassing growth, development, productivity, and quality. Agricultural soils are commonly classified into several categories based on their texture to facilitate effective agricultural practices like tillage, irrigation, fertilization, and pesticide applications.

A growing call has recently been made for integrating machine learning (ML) techniques to enhance comprehension and insight into soil behaviour. However, it is essential to note that real-world datasets often exhibit inherent imbalances. In such cases, ML models tend to overemphasize the majority classes while simultaneously underestimating the minority ones. This study aimed to investigate the effects of imbalance in training data on the performance of a random forest model (RF).

The original data used in this work was from La Chimenea farm station near Aranjuez (Madrid, Spain). The variables included were Electrical conductivity (EC), EC shape, EC depth, EC ratio, slope, curve, and NDVI derived from Sentinel-2. Clay and sand percentages were obtained with the exact spatial resolution, and the USDA classification was applied based on them. A descriptive statistics analysis was conducted to analyze the data. Then, Pearson's coefficient (r) of linear correlation was calculated to verify possible relations between the different variables. Then, a synthetic resampling approach using the Synthetic Minority Oversampling TEchnique (SMOTE) was employed to make a balanced dataset from the original data.

The imbalance and balance data classification were compared to see SMOTE's benefits in better-classifying soil texture.

Keywords: digital soil mapping; machine learning; soil texture; imbalance classification; data resampling

 

 Acknowledgements

This work has received support from projects PID2021-124041OB-C22 and PID2021-122711NB-C21, funded by the Ministerio de Ciencia e Innovación (Ministry of Science and Innovation).

 

How to cite: Ksantini, F., Tarquis, A. M., Almeida-Ñauñay, A., Sanz, E., and Quemada, M.: Establishing management zones for irrigation using soil properties and Remote Sensing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4157, https://doi.org/10.5194/egusphere-egu24-4157, 2024.

EGU24-4555 | Posters on site | SSS9.17

Nitrogen Cycling and Root Dynamics in an Agroforestry System 

Jhonathan Ephrath, Talli Ilani, Moshe Silberbush, and Pedro Berliner

Primary productivity in arid zones is limited by the lack of water and soil nutrients. Conveying and storing flood water in plots surrounded by embankments allows agricultural activity in areas where there is generally insufficient rainfall to sustain agricultural production. The efficient exploitation of the stored water was achieved by intercropping trees with an annual crop and pruning the former before planting the intercrop. This approach minimized competition for water and solar radiation. However, in order to ensure the long-term viability of such a system nutrients have to be added to the soil in order to compensate for the uptake of the intercrop, Nitrogen being the main element. The composted leaves of a leguminous shrub-like tree incorporated into the soil could satisfy the nitrogen demand of the intercrop. We tested this approach in a simulated runoff agroforestry system with fast-growing acacia (A. saligna) trees as the woody component and maize (Zea mays L.) as intercrop for two consecutive seasons. Ten treatments were applied (radical pruning before intercrop planting, compost application and planting of the intercrop as factors) and  the below- and above-ground effects and interactions examined. Pruning the trees canopies changed the trees’ root spatial and temporal distribution, allowing the annual crop to develop between the trees. Addition of compost significantly increased intercrop yield irrespective of the presence of the woody component while the presence of the intercrop did not affect the productivity of the trees. The highest productivity was obtained for the pruned trees, intercrop and added compost treatment.  A significant increase in the presence of tree roots was observed for the deeper parts of the soil profile for the pruned trees, intercrop and added compost treatment.  The addition of composted leaves from the leguminous woody component to the intercrop resulted in a very high water use efficiency of the water stored in the soil.

How to cite: Ephrath, J., Ilani, T., Silberbush, M., and Berliner, P.: Nitrogen Cycling and Root Dynamics in an Agroforestry System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4555, https://doi.org/10.5194/egusphere-egu24-4555, 2024.

The analysis of a looped water distribution system, usually employed in subsurface drip irrigation (SDI), under pressure and steady-state conditions, can be successfully performed if the topology of the network, the structure pipes, and the discharges at the nodes are known (Wang et al., 2021). Solving these complex networks usually requires an iterative approach. The Hardy Cross method (HCM), which was originally developed in 1936 (Cross, 1936) for manual calculations in civil engineering, can also be applied in lopped drip irrigation systems. This approach relies on the successive addition of flow-rate adjustments in each pipe to achieve the energy balance in each network segment, although limited by the Darcy-Weisbach resistance equation where the discharge exponent is set to 2.

In this work, a reformulated HCM was applied to looped drip irrigation systems, considering both local losses due to emitters’ insertion and the Hazen-Williams resistance equation (discharge exponent = 1.852), which is better suited to describe friction losses in the commonly used polyethylene pipes. The hydraulic performance of closed circuits calculated by HCM was analysed and compared with that of open circuits designed by IRRILAB software application (Baiamonte, 2018).

In particular, the final objective is to assess the energy-saving provided by the closed circuits (cc) in drip irrigation systems with respect to open circuits (oc). The energy-saving amount is expressed as the ratio (hratio < 1), between the inlet pressure head, hin, of the closed circuit and that of the open circuit. A predictive relationship of hratio was calibrated for 3000 simulations carried out for rectangular irrigation units characterized by different geometry, pipe diameters, emitters’ spacing and flow rate, providing relative errors RE < 0.25%. The results show that hratio depends on the pressure head tolerance of the manifold, δM, associated with the open circuits, which IRRILAB requires as an input parameter. This is very reasonable since, for high δM, the discharge circulating in the manifold is also high and closing the circuits provides low hratio (hin cc << hin oc). The vice versa occurs for low δM. Contrarily, the number of drip laterals, Nrows, has only a marginal effect on hratio. Of course, the energy-saving benefit should also consider the higher investment costs of cc than oc. However, this issue is beyond the scope of this study.

Keywords: Hardy-Cross method, Drip irrigation systems, Closed and open circuits, Pressure head tolerance, Energy-saving.

Acknowledgement: This study was funded by Ministero dell’Università e della Ricerca of Italy, project PRIN 2022 "Smart Technologies and Remote Sensing methods to support the sustainable Agriculture WAter Management of Mediterranean woody Crops (SWAM4Crops)" CUP B53D23018040001

References
Baiamonte, G. (2018). Explicit relationships for optimal designing rectangular microirrigation units on uniform slopes: The IRRILAB software application. Computers and Electronics in Agriculture, 153, 151-168.
Cross, H. (1936). Analysis of flow in networks of conduits or conductors. University of Illinois. Engineering Experiment Station, Bulletin; no. 286.
Wang, J., Chen, R., Yang, T., Wei, T., Wang, X. (2021). A computationally-efficient finite element method for the hydraulic analysis and design of subsurface drip irrigation subunits. Journal of Hydrology, 595, 125990.

How to cite: Vaccaro, G., Palermo, S., and Baiamonte, G.: Applying the Hardy Cross method to assess the energy-saving associated with closed circuits in drip irrigation systems compared to open circuits, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7916, https://doi.org/10.5194/egusphere-egu24-7916, 2024.

EGU24-7992 | ECS | Orals | SSS9.17

Spatial determination of ETo supported by weather forecasts and artificial intelligence. 

Juan Manuel Carricondo-Anton, Alberto Garcia-Prats, Hector Macian-Sorribes, Dariana Isamel Avila-Velasquez, Miguel Angel Jimenez-Bello, Esther Lopez-Perez, Juan Manzano-Juarez, and Manuel Pulido-Velazquez

The amount of open data offered by different numerical weather prediction (NWP) systems is growing due to the increase in the capacity of computing systems. This rise has enabled the development of improved and user-tailored forecasting services and products. However, one key variable in agricultural systems not usually provided by the forecasting services is the reference crop evapotranspiration (ETo), which requires ad-hoc computation and proper identification of the factors that condition it.

 

This work develops a spatially-distributed ETo forecast in the Jucar river basin (Eastern Spain), to support crop management in agricultural plots. ETo was determined from forecasted meteorological variables using the Penman-Monteith methodology described in FAO56. Specific ETo value maps at the AP scale were generated considering the spatial variation of the meteorological parameters that drive ETo: daily average, maximum, minimum and dewpoint temperatures, net solar radiation and wind speed at 2 meters. Calculations were downscaled using an interpolation technique based on linear regression from daily weather predictions of temperatures and wind. The procedure was tested using forecasts from the Global Forecast System (GFS) of the National Centers for Environmental Prediction (NCEP) belonging to the U.S. National Oceanic and Atmospheric Administration (NOAA), for the year 2022. Raw GFS forecasts were post-processed against the ERA5 reanalysis data, available through the Copernicus Climate Change Service (CS3), with a spatial resolution of 0.25o; and against observed data from the meteorological stations of the Agroclimatic Information System for Irrigation (SIAR) of Spain. In both cases, post-processing was done using artificial intelligence (AI), in particular Fuzzy Logic. Inputs for interpolation were the geographical characteristics at each GFS location within the Jucar river basin: longitude, latitude, distance to the Mediterranean Sea, mean solar radiation, mean solar radiation at a distance of 2.5, 5 and 25km from each GFS location, elevation, elevation at a distance of 2.5, 5 and 10km from each GFS location, slope, and orientation with respect to the north. Solar radiation is obtained using the Area Solar Radiation module of ArcGIS.

 

Once the forecasts and solar radiation maps were generated, the difference between the interpolated and the predicted values was calculated. This difference generated a cloud of points which, which together with a Digital Elevation Model, allowed for surface interpolation (SI) using the Splines with the Tension methodology integrated in Grass (QGIS). These SI are subtracted from the forecast’s maps obtained by interpolation, already having corrected forecasts with which the ETo is determined using the Penman-Monteith methodology described in the FAO56. The difference between the interpolated ETo and the predicted ETo is also calculated by subtracting this SI from the obtained ETo, generating a corrected ETo. Furthermore, post-processed forecasts and ETo was compared with 41 meteorological stations and evaluated using the Mean Absolute Error (MAE).

 

Acknowledgements:

This study has received funding from the European Union’s Horizon Europe research and innovation programme under the SOS-WATER project (GA no. 101059264); and from the subvencions del Programa per a la promoció de la investigación científica, el desenvolupament tecnològic i la innovació a la Comunitat Valenciana (PROMETEO) under the WATER4CAST project.

How to cite: Carricondo-Anton, J. M., Garcia-Prats, A., Macian-Sorribes, H., Avila-Velasquez, D. I., Jimenez-Bello, M. A., Lopez-Perez, E., Manzano-Juarez, J., and Pulido-Velazquez, M.: Spatial determination of ETo supported by weather forecasts and artificial intelligence., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7992, https://doi.org/10.5194/egusphere-egu24-7992, 2024.

EGU24-8048 | ECS | Orals | SSS9.17

Water footprint and water productivity analysis of an alternative organic mulching technology for irrigated agriculture 

Niccolò Renzi, Tommaso Pacetti, Marco Lompi, Giulio Castelli, Enrica Caporali, Andrea Setti, and Elena Bresci

Agriculture is causing unprecedented pressure on water resources to meet a growing food demand. This determines the necessity of implementing innovative, sustainable, and measurable systems to improve water use efficiency while increasing crop yield. This study tested the use of biodegradable mulching (BM) film for irrigated lettuce and the FAO AquaCrop model was used to simulate a precision irrigation scheme. The trials were conducted in the middle Arno River Valley, Tuscany, in Farm 1 (F1) and Farm 2 (F2) during the cropping seasons 2021 and 2022. In 2021 the BM film was tested in late spring at F1 and mid-summer at F2. In 2022, BM was tested twice at F2, in July and September, and once at F1, in June. The AquaCrop model was used only for the F2 mid-summer lettuce trial. Water Productivity (WPi) and ISO 14046 Water Footprint (WF) were measured, and a correlation analysis was performed. The study's outcome reported larger lettuce plants in the F2 BM July trial (0.806 kg plant-1) and smaller ones in F1 trial (0.100 kg plant-1), where the plant density was higher. The amount of irrigation water required was reduced in all the BM trials, ranging between 8%-50%, with the best performance in the F2 BM September trial where the amount was halved. In general, WF was always reduced in the BM trials and the best performance was with the F2 BM July trial (0.13 m3kg-1). Moreover, F2 indirect WF for the BM film production has a major share of impact on water resources ranging from 0.07 m3kg-1 to 0.17 m3kg-1. The best WP was also reached by F2 BM September trial (40.8 kg m-3). The Pearson coefficient (r) reported a strong negative correlation between WF and WP (-.73, p = .01), while, the determination coefficient ( R2) was 0.545. Hence, is confirmed how the reduction of WF is followed by the rise of WP. However, the low R2 shows how the two indicators are not specular but arrays of different useful information. Finally, AquaCrop simulation measured a fall in irrigation requirement (-86%, - 95%) in both treatments, reflecting an overestimation of the farmer irrigation scheme. The results confirmed the positive effect of BM and how using the WF can help farmers track their hotspots on water resources. The production of the BM films presented has a significant impact on water resources due to limited reuse over multiple crop cycles. Longer lasting films should be tested to investigate the reduction of indirect WF.

This study was carried out within the FEASAR-PSR 2014/2020 GO PEI PSGO 40/2017 ORTI BLU fund and the Agritech National Research Center and received funding from the European Union Next-Generation EU (PIANO NAZIONALE DI RIPRESA E RESILIENZA (PNRR) – MISSIONE 4 COMPONENTE 2, INVESTIMENTO 1.4 – D.D.1032 17/06/2022, CN00000022). This manuscript reflects only the authors’ views and opinions, neither the European Union nor the European Commission can be considered responsible for them.

How to cite: Renzi, N., Pacetti, T., Lompi, M., Castelli, G., Caporali, E., Setti, A., and Bresci, E.: Water footprint and water productivity analysis of an alternative organic mulching technology for irrigated agriculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8048, https://doi.org/10.5194/egusphere-egu24-8048, 2024.

EGU24-8407 | ECS | Orals | SSS9.17

Hydrological parameters modelling in catchments based on a geographical database. 

Andrés Felipe Almeida-Ñauñay, Ernesto Sanz, Ana María Tarquis, Juan José Martín-Sotoca, and Sergio Zubelzu

The water systems management plays a pivotal role in environmental conservation and disaster mitigation. As climate change intensifies, the ecological interactions of our ecosystems are modified, decreasing biodiversity and increasing extreme events. Therefore, accurate hydrological modelling tools are crucial for predicting rainfall-runoff processes. Hydrological processes, in general, are complex due to the interaction between multiple variables and spatial and time scales. Therefore, the development of hydrological models has evolved from simple models with few parameters to complex models aiming to model all notable processes within the study area. However, some researchers affirm that increasing the number of free parameters does not necessarily improve the model performance, and retaining only necessary data can ensure that the model’s components are positively represented. In this work, we show a set of geographical information system-based methodologies to set a limited optimal number of parameters to improve the hydrological modelisation.

To achieve our purpose, we collected terrain information, land use and soil properties data to model the water balance based on historical precipitation and gauging data. The same model was replicated in 47 small watersheds north of the Iberian Peninsula to ensure reliability. The rainfall and water flow data were downloaded from the automatic hydrology information system of the Ebro Water Confederation (SAIHEbro). We obtained a 15-minute rainfall and water flow time series, and each of them started at different years, continuing to current times up to a length of 27 years (more than 35,000 records per year).

As a result, we developed a database including the watershed limits, the most extended stream segment, rainfall and flow for each catchment. Furthermore, elevation, land use, soil classes, bulk density, clay, sand, and silt content (Hengl et al., 2017) at different depths were obtained. All data were transformed to a raster format to homogenise, and then their spatial resolution was harmonised to 2m for all spatial layers. The main shortcomings were found in matching the different spatial scales available in all the studied datasets. The lack of data or gaps in 2m DEM needed to be filled. Therefore, a nearest neighbour interpolation method combined with patching technique was performed by SAGA software and using 5m DEM as an input. Furthermore, differences in land use characterisation among regional and national datasets arose in some of the study catchments.

By processing these datasets, we obtained essential parameters for hydrological modelling. Altogether, the gathered information was useful to simulate the evolution of the water-related processes, paying particular attention to the relationships between precipitation, soil water content and land use.

Acknowledgements: The authors acknowledge the support of the Project “Fusión de modelos de base física y basados en datos para la modelización de fenómenos precipitación-flujo HYDER”, from Universidad Politécnica de Madrid (project number: TED2021-131520B-C21).

References

Hengl, T., De Jesus, J.M., Heuvelink, G.B.M., Gonzalez, M.R., Kilibarda, M., Blagotić, A., Shangguan, W., Wright, M.N., Geng, X., Bauer-Marschallinger, B., Guevara, M.A., Vargas, R., MacMillan, R.A., Batjes, N.H., Leenaars, J.G.B., Ribeiro, E., Wheeler, I., Mantel, S., Kempen, B., 2017. SoilGrids250m: Global gridded soil information based on machine learning, PLoS ONE. https://doi.org/10.1371/journal.pone.0169748

How to cite: Almeida-Ñauñay, A. F., Sanz, E., Tarquis, A. M., Martín-Sotoca, J. J., and Zubelzu, S.: Hydrological parameters modelling in catchments based on a geographical database., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8407, https://doi.org/10.5194/egusphere-egu24-8407, 2024.

EGU24-8757 | Posters on site | SSS9.17

A set of indicators to guide a WEFE transition in irrigated agriculture in the Duero Basin, Spain 

Leonor Rodriguez-Sinobas, Xenia Schneider, Maite Sanchez-Revuelta, Tommaso Pacetti, Mohammad Merheb, and Daniel A. Segovia-Cardozo

The Duero basin is the largest watershed in the Iberian Peninsula, with a surface of 98.073 km2 distributed in Spain and Portugal. The 80% of the surface area is in Spain (78.891 km2), where plays an important role for the country’s energy and food production. However, in the region, droughts are frequent and have increased in the last years stressing water resources and creating competition and friction among water users. Likewise, the energy demand for irrigation has also increased as along with energy and fertilizer prices. The uncertainty on future water resources is critical and it must be managed. Within this context, this paper will show the analysis of the current situation from a Water, Energy, Food and Ecosystems (WEFE) perspective and how it has developed several WEFE indicators and their inter-relations. The results may be used to analyze the effect of future scenarios, which foresee a decrease between 8 to 10% in water availability in the basin by 2039; it is also foreseen an increment in the prices of energy, fertilizers and production inputs. These indicators and their illustrations will help the stakeholders in their decision making and a WEFE-Nexus transition actions to overcome challenges in a resilient and sustainable way.

The work has identified and quantified a set of 12 indicators for the present conditions at two different spatial scales: two Duero sub-basins (Cega-Eresma-Adaja, and Bajo Duero) and three irrigation districts (Río-Adaja, Villalar de los Comuneros and “El Carracillo), each one has different source of water (surface, subsurface and mix). Three indicators for water, two for energy, two for food production and five for ecosystems were proposed and quantified by using information obtained by modelling and literature review. The results were compared both at different scales and in different situations.

How to cite: Rodriguez-Sinobas, L., Schneider, X., Sanchez-Revuelta, M., Pacetti, T., Merheb, M., and Segovia-Cardozo, D. A.: A set of indicators to guide a WEFE transition in irrigated agriculture in the Duero Basin, Spain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8757, https://doi.org/10.5194/egusphere-egu24-8757, 2024.

EGU24-10461 | ECS | Posters virtual | SSS9.17

Physiological, yield and nut quality responses of walnut tree subjected to different irrigation regimes following IRRIFRAME water balance model 

Giulio Demetrio Perulli, Salvatore Luca Gentile, Domenico Solimando, Stefano Anconelli, Elena Baldi, Moreno Toselli, Alexandra Boini, and Luigi Manfrini

In the last years commercial walnut orchards plantation is increasing in Emilia-Romagna, an Italian region renowned for its excellence in fruits cultivation. Despite the expansion of walnut plantations in this region, there is scarcity of studies focusing on the water demand of this crop. This research aims to assess the response of an adult walnut orchard (cv. 'Chandler') to three distinct irrigation treatments (100% ETc, 75% ETc, and 50% ETc). Water supply was managed according to the IRRIFRAME water balance model. Plant water status (stem water potential, SWP), leaf gas exchanges (leaf photosynthesis, A; stomatal conductance, gs), yield, nut quality (e.g., nut weight, shelled yield, kernel colour) and water use efficiency (WUE) were measured for four consecutive seasons (2018-2021). Differences in plant water status were detected only in half of the performed measurements and trees irrigated at 100% ETc generally showed more positive SWP values compared to 75% and 50% ETc trees. Gs and A were less sensitive than SWP to the different water regimes, showing limited differences among treatments only in the first two years. Yield and main nut quality parameters were slightly affected by irrigation treatments mainly in 2018 and 2019, with the 50% ETc showing a reduced productivity compared to 100% and 75% ETc. No differences where registered for shelled yield and kernel colour for all the four consecutive years. On the contrary, irrigation treatments highly affected WUE in all the considered years, with 100% ETc being the less efficient treatment, followed by 75% and 50% ETc.

How to cite: Perulli, G. D., Gentile, S. L., Solimando, D., Anconelli, S., Baldi, E., Toselli, M., Boini, A., and Manfrini, L.: Physiological, yield and nut quality responses of walnut tree subjected to different irrigation regimes following IRRIFRAME water balance model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10461, https://doi.org/10.5194/egusphere-egu24-10461, 2024.

EGU24-10468 | ECS | Posters virtual | SSS9.17

Actinidia chinensis: physiological and productive performances under different irrigation restitutions 

Alexandra Boini, Gianmarco Bortolotti, Giulio Demetrio Perulli, Luca Corelli Grappadelli, and Luigi Manfrini

Yellow flesh kiwi fruit production normally follows protocols based on the green species, A. deliciosa, often resulting in low yields, attributable to small sized fruit, meaning A. chinensis seems more susceptible to water limitations. Understanding the species physiology and fruit vascular flows may help determine this crop’s evapotranspiration needs, to efficiently obtain satisfactory harvests. The presented work results from a 3-year trial (2019-2020-2021), where control irrigation vines were compared with deficit-irrigated and over-irrigated vines. Midday physiology, including plant water relations, leaf gas exchanges and fruit vascular flows were analysed, along with harvest parameters and dry matter content. Irrigation treatments influenced the vines’ responses only when soil water content was below certain levels, reflecting sensitivity of the crop to water changes in the soil. Although no significant differences were found in harvest parameters, dry matter content was higher for the less irrigated fruit. The less irrigated treatment performed less better, than the control and the over-irrigated, especially when water supply did not fulfil fruit transpiration. This occurred during the berry development phase (around 1 month after full bloom), a critical period during which the fruit has very high transpiration rates, which passively call photosynthates (phloem inflow) to provide energy for cell division. Fruit transpiration appears to influence phloem inflow during most of the season, even until 1 month before harvest, however the initial phases of fruit development and growth are pivotal for final yield. Vascular flows allowed to unveil a typical simplasmic behaviour in the early stages of berry development, meaning the microenvironment is intensely influencing fruit behaviour. Irrigation must respond to the needs of young fruit, taking into account soil water content and the phenological phase. The use of sensors, plant based and environmental, is an important technique for determining the necessary water volumes for yellow kiwi fruit.

How to cite: Boini, A., Bortolotti, G., Perulli, G. D., Corelli Grappadelli, L., and Manfrini, L.: Actinidia chinensis: physiological and productive performances under different irrigation restitutions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10468, https://doi.org/10.5194/egusphere-egu24-10468, 2024.

Due to climate change, managing irrigation systems requires adapting existing scheduling strategies based on monitoring meteorological, biophysical, and soil physical variables. For monitoring, there are many combinations of sensors, starting from low-cost IoT-based systems and ranging to scientific high-precision devices that offer a specific quality of measurements at a particular price. By explicitly modeling the value gained by more precise monitoring, the value of information (VOI) theory can determine whether additional information provided by site-specific monitoring setups is worth employing to manage the considered irrigation systems. Different levels of information about meteorological conditions are provided by (i) on-site systems (energy balance station, low-cost climate station, and a spatial grid of low-cost LoRaWAN temperature and humidity sensor), (ii) available public weather data, e.g., from a close climate station of the German weather service (DWD), and (iii) latest reanalysis data from the ERA5-Land product. To estimate the additional VOI of the different site-specific monitoring setups related to the reference defined by the DWD data, evapotranspiration, biomass, and yield data simulated by the Aquacrop model are compared. In addition, adapted scheduling strategies are derived using the Deficit Irrigation Toolbox (DIT).   This contribution presents the application of VOI theory for decision-making in the monitoring design of an irrigated apple farm in Werder (Germany) in 2023 and 2024.

How to cite: Schuetze, N., Kuhnert, L., and Lennartz, F.: Assessing the value of information: a comparative analysis of meteorological observation setups in an irrigated German apple orchard, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11134, https://doi.org/10.5194/egusphere-egu24-11134, 2024.

EGU24-11989 | Orals | SSS9.17

Analysis of the use of actual evapotranspiration calculated with Landsat imagery and climate forecasts, assessed with an agrohydrologic model for irrigation scheduling in fruit crops 

Miguel Angel Jiménez Bello, Juan Manuel Carricondo-Antón, Alberto García-Prats, Esther López-Pérez, Juan Manzano-Juarez, Manuel Pulido-Velazquez, and Fernando Martínez-Alzamora

The evapotranspiration of vegetation (ET) is a key component of the hydrological balance. Various tools and models have been proposed to estimate evapotranspiration in fruit crops. Among them, the most widely used approach is that proposed by the Food and Agriculture Organization (FAO), which considers climatic variables included in reference evapotranspiration (ETo), as well as the type of crop and its characteristics represented by a single crop coefficient (Kc). However, there is evidence that in tall and discontinuous canopies, such as citrus orchards, with a high degree of interaction with the environment, Kc can change depending on local environmental conditions and the amount of vegetation.

Other methods, such as measurements of stem water potential, sap flow sensors, and moisture probes, allow for determining the water status of the crop, but only for a limited number of trees, and uncertainties arise when extrapolating values. Remote sensing fills this gap if spatial and temporal resolutions suit the monitored crop. A successful approach in water management is using models that calculate latent heat as a residue of the surface energy balance (SEB).

This study applied an energy balance to calculate ET in an irrigation district. The study site is located in the Valencia region (Spain; 39º22'43'' N, 0º28'20'' W) with localized irrigation, where most crops are citrus. A total of 182 images from the Landsat satellite constellation for the period 2013-2018 were used to estimate instantaneous ET by extrapolating daily actual ET (ETSEBAL) values using climatic data.

These climatic data correspond to predictions the Global Forecast System (GFS) provides. This way, climatic predictions are used for scheduling instead of the classical methodology that uses past data to estimate evapotranspiration. The study's objective is to analyze the results using a dynamic Kc obtained from the actual state of the crops and climatic predictions for each plot, compared to a generic Kc obtained for standard conditions and past climatic data.

The results suggest that, for the studied plots, the relationship between drained water and the actual volume provided by irrigators would be reduced by 20% to -30 %. A point agrohydrological model calibrated with capacitive moisture probes was used to monitor soil water balance.

In the same way, the methodology allows for determining the stress level of crops and maintaining it within recommended limits.

How to cite: Jiménez Bello, M. A., Carricondo-Antón, J. M., García-Prats, A., López-Pérez, E., Manzano-Juarez, J., Pulido-Velazquez, M., and Martínez-Alzamora, F.: Analysis of the use of actual evapotranspiration calculated with Landsat imagery and climate forecasts, assessed with an agrohydrologic model for irrigation scheduling in fruit crops, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11989, https://doi.org/10.5194/egusphere-egu24-11989, 2024.

EGU24-12251 | Posters on site | SSS9.17

Exploratory modeling of saline irrigation of olive trees using artificially built contrasting soil barriers 

Gonzalo Martinez, José Manuel Martínez-García, Juan Vicente Giráldez, Ana M Laguna, and Tiago Ramos

Salt accumulation in soils is a major threat to the sustainability of irrigated land. However, the availability of fresh water for irrigation is decreasing sharply and alternative sources of water, e.g. saline waters, become more and more necessary to satisfy water requirements of crops, and more specifically of olive trees in southern Spain. Recent advances on the impact of precipitated salts on evaporation processes in porous media opened the venue to further research on the potential of artificially built contrasting soil barriers (CSB) to manage saline irrigation. In this work, the HYDRUS-2D model was used to evaluate different configurations and designs of soil textural barriers in terms of soil properties, distance to the tree trunk, width, and depth of the barrier. The model used weather data and saline irrigation applications as the top boundary condition and the dynamics of soil water potential and salt concentration at several depths (0.30, 0.60, 0.90 and 1.20 m) were evaluated. Global sensitivity analysis using the Morris method was conducted to evaluate the relevance of each of the different variables considered for the CSB design. The simulations showed a relevant effect of the CSB in changing the precipitation/dilution of salts in soil compared to its absence. Less concentration of salts was found in the root zone in the CSB simulations that in simulations without CSB in all the scenarios under study. However, higher accumulations of salts were found in the soil surface when including the CSB. The different configurations of native soil vs soil within the CSB provided different optimum configurations of the CSB depending on soil textural classes combinations. Based on the outcomes of this modeling exercise, a site-specific design depending on the soil texture can be performed and the optimum soil textural barrier chosen to optimize the potential of the system to keep the largest dilution of salts within the root zone and the highest accumulation of salts in the CSB.

How to cite: Martinez, G., Martínez-García, J. M., Giráldez, J. V., Laguna, A. M., and Ramos, T.: Exploratory modeling of saline irrigation of olive trees using artificially built contrasting soil barriers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12251, https://doi.org/10.5194/egusphere-egu24-12251, 2024.

EGU24-12450 | Posters virtual | SSS9.17

A novel insight into spatio-temporal variability of storm events for modelling hydrological processes at catchment scale based on machine learning 

Sergio Zubelzu, Blanca Cuevas, Ernesto Sanz, Andrés Almeida, and Ana Tarquis

Hydrological processes are shaped by complex and distant processes characterised by high spatio-temporal variability. Being the first hydrological process, triggering the remaining ones, precipitation, or more precisely, storm events, have paramount importance on the subsequent evolution of the hydrological system. The spatio-temporal evolution of precipitation has received profound attention from scientists. This topic is commonly addressed in practical hydrological simulation by simple (pseudo) deterministic algorithms as form example Polygons of Thiessen or Krigging methods. In this work we present a novel approach based on two pillars: first by focusing on storm events instead of in aggregated precipitation values and second by spatially analysing the relationships among the recorded values aided by machine learning algorithms. With that aim we have retrieved precipitation records from 6 weather stations in Madrid city with hourly latency from January 2019 and 587 stations with 15 minutes latency from January 2004. We have extracted the observed storm events in any case and analysed the spatio-temporal patterns underlying the storm evolution thus observing the scarce representativity of the traditional methods being machine learning approaches better suited for providing representative data. 

This work is part of the project TED2021-131520B-C21, supported by the MCIN/AEI/10.13039/501100011033 and the European U nion “NextGenerationEU”/PRTR.

How to cite: Zubelzu, S., Cuevas, B., Sanz, E., Almeida, A., and Tarquis, A.: A novel insight into spatio-temporal variability of storm events for modelling hydrological processes at catchment scale based on machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12450, https://doi.org/10.5194/egusphere-egu24-12450, 2024.

Optimizing water use efficiency and crop yield are important objectives of irrigated agriculture. For planning near future irrigation, farmers can rely on weather forecasts, which cover a time horizon of up to two weeks. This information is then used to make decisions about agricultural activities, including irrigation. However, a gap exists between weather forecasting and climate prediction, which poses challenges for decision-making in the medium-term crop season. The sub-seasonal to seasonal (S2S) range, spanning from two weeks to one season, bridges this gap. In this study we investigate if S2S forecasts combined with an agro-hydrological model can extend the time horizon of farmers’ decision decision-making compared to a traditional week-to-week schedule.

A case study was conducted for the Northern German Hamerstorf experimental field, which is operated by the Chamber of Agriculture of Lower Saxony to provide weekly consulting and decision support services for regional farmers in the fields of fertilisation and irrigation. Irrigation is triggered at 35% and 50% of available water capacity and the annual crop yield for these irrigation scenarios is evaluated. In this research a SWAP (soil-water-atmosphere-plant) model was calibrated and validated using observed field data from the experiments. The calibrated model was then coupled with the reforecast S2S ensemble dataset. To evaluate the performance of the S2S/agro-hydrological model, we used the ECMWF (European Centre for Medium-Range Weather Forecasts) S2S ensemble and simulated the future irrigation water demand for the next two, four and six weeks. Simulated crop yield, irrigation water demand and the results of auto-scheduling irrigation over the recent five irrigation seasons (2018-2022) were evaluated and compared with a reanalysis using observed climate and with the experimental field practise.

First results confirm that uncertainty increases with the lead time of the forecast, but a major aspect for irrigation planning is the start and end of dry periods. There, uncertainty is less compared to the uncertainty of future rain, which recommends further exploration of the value of S2S forecasts in agricultural decision support.

How to cite: Fallah-Mehdipour, E. and Dietrich, J.: Evaluating irrigation demand forecasts from S2S/agro-hydrological modelling with field experiments in Northern Germany in the context of farmer decision support, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12705, https://doi.org/10.5194/egusphere-egu24-12705, 2024.

EGU24-13375 | Posters on site | SSS9.17

Integrating remote sensing and climate data for olive grove classification and yield estimation 

Rosa Gutiérrez-Cabrera, Ana María Tarquis, and Javier Borondo

Keywords: Irrigated agriculture, NDVI, Sentinel-2, Dynamic Time Warping, Machine learning

The agricultural sector confronts escalating challenges amid uncertainties associated with water resources, underscoring the imperative for innovative solutions. Hence, a profound comprehension of the production dynamics of forthcoming productions becomes paramount for effective water management and the optimization of irrigation strategies, leveraging algorithms such as Dynamic Time Warping (DTW).

This study delves into forward-thinking methodologies encompassing delineation in both rainfed and irrigated olive groves, furnishing a comprehensive panorama of the cultivation landscape. Utilizing information derived from satellite images, particularly the Normalised Difference Vegetation Index (NDVI), enables the comparison between olive groves dedicated to either irrigated or rainfed production. This comparison helps quantify and comprehend the impact of irrigation on olive groves, correlating it with climatic factors such as rainfall and temperature. Essentially, it could aid in identifying optimal conditions for irrigation and when it may not be necessary.

Simultaneously, it facilitates accurate estimation of olive yields based on the prevailing water conditions. Harnessing vegetation indices such as NDVI from remote sensing allows us to forecast how diverse olive groves react to varying climatic conditions. This monitoring facilitates proactive irrigation to avert water stress affecting production levels deeply.

Moreover, this comparison, anchored in NDVI, lays the groundwork for subsequent analyses incorporating soil and other climate data. Therefore, it enhances the precision of irrigation decisions, contributing to preparedness for droughts and formulating well-informed policies.

In conclusion, this study pushes the boundaries of intelligent irrigation management in olive cultivation, fostering sustainability, cost-effective technology, and optimal resource utilization. The technical insights presented herein constitute a comprehensive resource for any stakeholder seeking solutions in agriculture.

How to cite: Gutiérrez-Cabrera, R., Tarquis, A. M., and Borondo, J.: Integrating remote sensing and climate data for olive grove classification and yield estimation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13375, https://doi.org/10.5194/egusphere-egu24-13375, 2024.

Irrigation is the most significant human water withdrawal globally, playing a pivotal role in ensuring food security. However, the lack of detail irrigation datasets across spatial and temporal dimensions limits our comprehensive understanding of how historical irrigation water supply has responded to demand fluctuations and, consequently, its effect on agricultural yields. In this study, we employed a combination of remote sensing products, meteorological data, and various statistical datasets to estimate gridded monthly irrigation water demand and supply in China at a spatial resolution of 0.1° during the period 2000-2019. The results indicate that the national annual irrigation water demand is 122.23 km3, with rice accounting for the highest share (39.25%), followed by wheat (36%) and maize (24.75%). While the annual irrigation water supply is measured at 317.42 km3, with rice (62%) dominating, trailed by maize (21.13%), and wheat (16.87%) contributing the least. The mismatch in the distribution of irrigation water supply and demand among crops underscores variations in irrigation systems and the availability of water sources for irrigation. Notably, in the downstream of the Yellow River Basin and the Huaihe River Basin, the irrigation water supply falls short of demand when not accounting for irrigation efficiency, primarily attributed to a scarcity of water during the wheat growing season in spring (Mar. to May), indicating a potential water stress on wheat yield in this region. This study enhances our understanding of the intricate relationship between irrigation water supply and demand in China, offering valuable insights to support regional water resources management and allocation strategies.

How to cite: Hou, C.: Response of irrigation water supply to demand in China and its effects on yields, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13904, https://doi.org/10.5194/egusphere-egu24-13904, 2024.

EGU24-14767 * | Posters on site | SSS9.17 | Highlight

Current and future blue water availability for agriculture in the Mediterranean 

Sandra Paola Bianucci, Álvaro Sordo-Ward, and Luis Garrote

The current and future water availability for Mediterranean basins was assessed under different climate and policy scenarios. The high-resolution GIS-based WAPA model (Water Availability and Adaptation Policy Analysis) was used to obtain potential water availability under a set of realistic hypotheses. Diverse data sets were compiled on meteorological variables, water resources, runoff, land cover, and population density to create a geospatial database that covers river basins that drain into the Mediterranean Sea. The model was forced with the results of the global hydrological models H08 and CWatM for ISIMIP (Inter-Sectoral Impact Model Intercomparison Project) scenarios. These two hydrological models were forced with climate drivers for three historical scenarios (obsclim, picontrol, and historical), which define a baseline, and three future scenarios (ssp126, ssp370 and ssp585) provided by the sixth assessment report of IPCC (2023). A high-resolution map of the potential availability of water for irrigation was developed in Mediterranean basins. The allocation of water for irrigation is subordinated to the urban supply (drinking water) and for the conservation of river ecosystems. The results indicate that changes in hydrological regimes across the region are expected to have a significant impact on future water availability. The proposed approach provides a valuable tool for decision makers and stakeholders for the identification of areas vulnerable to changes in water availability. The information generated in this study, high-resolution spatial outputs and detailed water availability estimates, could work as a relevant input for integrated water resource management and climate change adaptation planning. This research offers a robust framework for assessing water resources under changing climate, applicable to other regions facing similar challenges. In summary, our study provides useful information to policymakers and stakeholders, helping them to make informed decisions to develop adaptive measures for sustainable water management under uncertain future climate conditions.

How to cite: Bianucci, S. P., Sordo-Ward, Á., and Garrote, L.: Current and future blue water availability for agriculture in the Mediterranean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14767, https://doi.org/10.5194/egusphere-egu24-14767, 2024.

EGU24-15892 | ECS | Posters on site | SSS9.17

Identifying opportunities and challenges of digitalization in agricultural water management in Austria 

Maximilian Thier, Christian Faller, Heike Brielmann, Helga Lindinger, Christine Stumpp, and Reinhard Nolz

Due to climatic changes and a predicted decline in arable land, a significant increase in water demand for irrigation is expected in Austria. To ensure water supply and food security while promoting the responsible use of available water resources, reliable data and forecasts are essential for decision-making in all areas of water management. Agricultural water management and irrigation practices require up-to-date data and reliable forecasts of water demand and availability for the planning and operation of irrigation systems. Decision-makers need the same information for water management planning, such as the assessment of the regional water availability, as a basis for the approval of irrigation projects. In Austria, a lot of data is collected regularly and is available in analogue or digital form. Digitalization offers the opportunity to collect, link, process and make this data available. As part of a study, funded by the Federal Ministry of Agriculture, Forestry, Regions and Water Management, digital data sources and digital tools relevant to irrigation in Austria were therefore collected, systematically compiled, and evaluated. The basis for the identification and selection was a comprehensive online and literature search. The systematic processing, compilation and evaluation constituted an iterative process in which representatives of the relevant stakeholder groups - water managers, farmers, and researchers - were involved through personal discussions and surveys to gain knowledge about awareness and use of digital tools. Deficits and potentials in connection with the digitalization of irrigation were also identified and discussed, and recommendations relevant to water management were derived. More than 70 digital tools and databases were identified and grouped according to their main characteristics, e.g. hydrology, climate, or soil, as well as according to subject areas based on the interests of the stakeholders. On this basis, information sheets were created to present the objectives that can be achieved with the application, such as promoting productivity or preventing the loss of irrigation water due to deep percolation. The results of this study provide information for a broad audience and identify knowledge and data gaps for future planning and research activities. However, to fully exploit the potential of digitalization in irrigation, efforts need to be made, for instance, to bridge the gap between digital technologies and the desired objectives, to promote inter-institutional cooperation and to improve both the quality and quantity of available data.

How to cite: Thier, M., Faller, C., Brielmann, H., Lindinger, H., Stumpp, C., and Nolz, R.: Identifying opportunities and challenges of digitalization in agricultural water management in Austria, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15892, https://doi.org/10.5194/egusphere-egu24-15892, 2024.

EGU24-16358 | Orals | SSS9.17

Precision soil moisture monitoring: use of a multi-sensor profiling for optimizing yield and fruit quality of yellow fleshed kiwifruit in northern Italy 

Elena Baldi, Maurizio Quartieri, Matteo Golfarelli, Matteo Francia, Josef Giovanelli, Marco Mastroleo, Evalgelos Xilogiannis, and Moreno Toselli

The control of soil moisture is fundamental for optimizing water supply, plant performances and fruit quality. Traditional monitoring systems rely on a single sensor, or several sensors positioned along the soil profile not giving reliable information on soil water availability in the soil volume occupied by roots. In a 3-years field experiment we tested the effectiveness of PLUTO, an original approach able to define soil moisture profiles thanks to a bi- and tri-dimensional grid of sensors. The study was carried out, from 2021 to 2023, in northern Italy, on kiwifruit Zezy002 (A. chinensis var. chinensis) grafted, in 2012, onto micro-propagated Hayward (A. chinensis var. deliciosa) planted at a distance of 4.5 m x 2 m apart. During the experiment a traditional irrigation system (CONTROL) was compared to smart irrigation (PLUTO). Water management in the control treatment was carried out according to the advisory service, only based on daily evapotranspiration. On the other side, according to PLUTO water was applied taking into consideration the soil water content measured by potentiometric probes located according to the grid of sensors. Irrigation started when soil matric potential dropped below -0.1 MPa in more than 50% of the volume of soil explored by the root system and was aimed at returning the same amount of water lost the day before and estimated by evapotranspiration. During the experiment, compared to the CONTROL, PLUTO reduced the volume of water without impairing plant water status and yield. Fruit juice soluble solid concentration and fruit dry matter at harvest was increased by the smart irrigation system with a similar response also after 2 and 4 months of cold storage. PLUTO water management also induced a lower fruit firmness and yellow pulp color (defined by H angle) at harvest. In conclusion, the definition of irrigation volumes and timing according to smart irrigation system were able to reduce water consumption and increase fruit quality. Taking into consideration that the cost of sensors is progressively decreasing, PLUTO provides a cost-effective, operative, and precise solution to monitor soil water availability.

How to cite: Baldi, E., Quartieri, M., Golfarelli, M., Francia, M., Giovanelli, J., Mastroleo, M., Xilogiannis, E., and Toselli, M.: Precision soil moisture monitoring: use of a multi-sensor profiling for optimizing yield and fruit quality of yellow fleshed kiwifruit in northern Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16358, https://doi.org/10.5194/egusphere-egu24-16358, 2024.

EGU24-16726 | Orals | SSS9.17

Analyzing the resilience of complex irrigation systems: the ERASMUS approach 

Alessandro Pagano, Giacomo Ferrarese, Nicola Fontana, Ivan Portoghese, Umberto Fratino, Virginia Rosa Coletta, Nicola Lamaddalena, Stefano Mambretti, and Stefano Malavasi

Irrigated agriculture is a central socio-economic sector in many countries, particularly in the Mediterranean area, but often associated with relevant environmental issues, such as the high demand for natural resources (water, soil, energy). Irrigated agriculture is also increasingly threatened by multiple stresses, which include the rising demand for food, the lack of resources (as a consequence e.g., of climate change) and the conflicting needs and uses of those resources.

The recent scientific literature highlighted the need to support understanding and operationalizing the concept of resilience for irrigated agroecosystems, i.e. the capability of such systems to absorb stresses and adapt to changing conditions. The present work, developed within the ERASMUS project (within the PRIN 2022 call, funded by the European Union, Next Generation EU), mainly focuses on the role of water resources management in irrigated areas, yet considering a ‘Nexus’ approach that highlights the interconnections and interdependencies among resources. The aim is to identify management practices and technological measures that may support irrigated agriculture in the face of a multiplicity of environmental and anthropogenic stresses, ultimately suggesting sustainable development pathways for areas under stress. Particular attention is given to the rational use of water resources and to the role that can be played by the introduction of cutting-edge technologies and network modernization processes to increase the resilience, the long-term sustainability and the performance (in terms of distribution equality and efficiency) of pressurized irrigation systems.

Two main modelling approaches are the backbone of the ERASMUS approach. On the one hand, System Dynamics Modelling tools are used to describe the complexity of irrigated agroecosystems, the interdependencies among sectors (water, energy, land, food, climate) and to characterize their resilience. The main objective is to effectively describe (using also innovative sets of indicators) the system state and potential evolution as an effect of the different modernization strategies of networks along with different models/strategies for better managing water resources. Second, numerical modelling approaches are used to test the potential of innovative devices (mainly smart valves) and management criteria to improve the performance of irrigation networks, ultimately increasing the resilience of the system as a whole. Specific attention will be given to new technological solutions that may guarantee multiple joint benefits, ranging from a reduction of resource consumption (water, energy), while providing an increasing control and management of networks. Such an ambitious objective is being put into practice in two pilot sites located in Southern Italy (i.e., two irrigation consortia located in Puglia and Campania) where two Communities of Innovation are being developed and will support modelling activities throughout the project duration.

How to cite: Pagano, A., Ferrarese, G., Fontana, N., Portoghese, I., Fratino, U., Coletta, V. R., Lamaddalena, N., Mambretti, S., and Malavasi, S.: Analyzing the resilience of complex irrigation systems: the ERASMUS approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16726, https://doi.org/10.5194/egusphere-egu24-16726, 2024.

EGU24-17294 | ECS | Orals | SSS9.17

Thermal and multispectral sensors model for determining the water status in a commercial vineyard in semiarid conditions. 

Luz Karime Atencia Payares, Juan Nowack, Ana Maria Tarquis, Mónica Garcia, and María Gómez del Campo

Spain counts roughly 941.000 hectares of vineyards, of which 41% are grown under irrigation systems. Water status is a relevant parameter in grapevines as it affects yield, fruit composition, and wine quality. Water stress reduces photosynthetic activity and vegetative growth and limits berry ripening. Mapping the crop's water status is essential for adjusting irrigation doses based on the specific water demands of different agroclimatic zones [2]. Thus, maps can be generated based on water status level ranges. Remote sensing through thermal and multispectral sensors onboard Unmanned Aerial Systems (UASs) can provide such maps with sufficient detail and rapidity. This tool allows obtaining high-resolution images that aid in assessing crop heterogeneity [3].

In a commercial vineyard located in the central region of Spain, we developed models to obtain values of stem water potential (SWP) based on canopy temperature estimated from high-resolution aerial images of a thermal sensor (Tc) [1] and multivariable linear regression models based on combinations of multispectral bands [4].

These models were developed using measurements and data from two previous irrigation seasons (2021 and 2022) on experimental vines in different plots with different management practices, irrigation, and climatic conditions. The modelled values of SWP were validated with measurements in the same vines for the 2023 season.

The application of the two developed models allows for spatial and temporal analysis of the water status of vines, aiding in the on-field characterization of water stress. This dynamic spatial mapping improves irrigation management through climatological information and high-resolution sensors.

ACKNOWLEDGEMENTS

The authors thank Bodegas y Viñas Casa del Valle for allowing us to work in their vineyards and the company UTW for supplying the drone images. Comunidad de Madrid provided financial support through calls for grants to complete Doctorado Industrial IND2020/AMB-17341, which was greatly appreciated. M.G. was supported by a "María Zambrano" contract for the Universidad Politécnica de Madrid, financed by the Spanish Ministerio de Universidades and by "European Union NextGenerationEU/PRTR".

 

REFERENCES

[1] Atencia, L. K., del Campo, M. V., Nowack Yruretagoyena, J. C., Tarquis Alfonso, A. M., and Hermoso Peralo, R.: Detection of plant water stress in Merlot vineyard using thermal sensors onboard UAVs , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-16111, https://doi.org/10.5194/egusphere-egu23-16111, 2023.

[2] Atencia Payares LK, Tarquis AM, Hermoso Peralo R, Cano J, Cámara J, Nowack J, Gómez del Campo M. Multispectral and Thermal Sensors Onboard UAVs for Heterogeneity in Merlot Vineyard Detection: Contribution to Zoning Maps. Remote Sensing. 2023; 15(16):4024. https://doi.org/10.3390/rs15164024.

[3] Atencia Payares LK, Tarquis AM, Hermoso Peralo R, Cano J, Cámara J, Nowack J, Gómez del Campo M. Soil vineyard variability evaluated with multispectral sensors on board of UAVs. X International Symposium on Irrigation of Horticultural Crops, Stellenbosch, South Africa, 29th January to 2nd February 2023.

[4] Nowack, J. C., Atencia, L. K., Gómez del Campo, M., and Tarquis, A. M.: Assessing plant water status in Merlot vineyards using Worldview-3 multispectral images in central Spain, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16082, https://doi.org/10.5194/egusphere-egu23-16082, 2023.

 

How to cite: Atencia Payares, L. K., Nowack, J., Tarquis, A. M., Garcia, M., and Gómez del Campo, M.: Thermal and multispectral sensors model for determining the water status in a commercial vineyard in semiarid conditions., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17294, https://doi.org/10.5194/egusphere-egu24-17294, 2024.

EGU24-17455 | Orals | SSS9.17

Monitoring Anthropogenic Irrigation Water Use by assimilating satellite land surface temperature and soil moisture 

Chiara Corbari, Nicola Paciolla, Diego Cezar Dos Santos Araujo, Kamal Labbassi, Justin Sheffield, Sven Berendsen, Ahmad Al Bitar, and Zoltan Szantoi

The agricultural sector is the biggest and least efficient water user, accounting for around 80% of total water use in Northern Africa, which is already strongly impacted by climate change with prolonged drought periods, imposing limitation to irrigation water availability. The objective of this study was to develop a procedure for the monitoring of anthropogenic irrigation water use for the irrigation districts of Doukkala in Morocco, from 2013 to 2022.

The system is based on the energy-water balance model FEST-EWB, which is an agro-hydrologic pixel wise model that computes continuously in time the main processes of the hydrological cycle where evapotranspiration and soil moisture behaviour in agricultural soil layer are modelled solving the energy and water mass balance model (EWB).

Firstly, the model has been calibrated and validated over non-irrigated areas, against satellite land surface temperature from LANDSAT and downscaled Sentinel3 data at 30m of spatial resolution, and evapotranspiration from MOD16, GLEAM and FAOWapor. The model has been run using as input the past observed meteorological forcings (ECMWF ERA5-Land) and vegetation data. From the pixel-by-pixel comparison between modelled and observed LST, a mean absolute difference of 3.5 °C is obtained over the period 2017-2022 for the whole Doukkala area.

The second step refers to the historical estimates of the actual irrigation volumes through the calibrated model implementing three different irrigation strategy, at hourly scale and at 30m of spatial resolution: the FAO approach based on soil moisture (SM) and crop stress thresholds (Allen et al., 1998), the separate and joint assimilation of satellite land surface temperature (downscaled Sentinel3 data) and of satellite soil moisture (1km SMAP-Sentinel1) to update the modeled fluxes and estimates irrigation volume. Overall, the results suggested that the yearly total irrigation volumes modeled with the FAO approach are quite in agreement with the observed water allocations; and similar outcomes are obtained when the joint assimilation of satellite LST and SM is implemented which allows to overcome the problems related to the number of available satellite images, which could lead to missing irrigation events.

How to cite: Corbari, C., Paciolla, N., Dos Santos Araujo, D. C., Labbassi, K., Sheffield, J., Berendsen, S., Al Bitar, A., and Szantoi, Z.: Monitoring Anthropogenic Irrigation Water Use by assimilating satellite land surface temperature and soil moisture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17455, https://doi.org/10.5194/egusphere-egu24-17455, 2024.

EGU24-18792 | ECS | Orals | SSS9.17

How can we support irrigation management in viticulture to preserve grape quality in southern Italy?: the case study of Aglianico grapevine. 

Andrea Vitale, Michela Janni, Maurizio Buonanno, Arturo Erbaggio, Rossella Albrizio, Pasquale Giorio, Veronica De Micco, Chiara Cirillo, Francesca Petracca, Matteo Giaccone, Filippo Vurro, Nadia Palermo, Manuele Bettelli, and Antonello Bonfante

The viticultural sector is one of the agricultural sectors most challenged by Climate change(CC), needing specific adaptation and mitigation actions to make local farming communities and production resilient. In this context, it is important to guarantee not only the achievement of production but also, above all, the achievement of a cultivar-specific grape quality able to support the oenological goal and, thus, the expression of terroir.

In viticulture, the plant's water stress is therefore important, representing, unlike other crops, a necessary condition for achieving the quality and typicality of the wine. This is because the vine water status represents the main regulator of the hormonal balance of grapevines, affecting berries' characteristics such as sugar, anthocyanins, flavonoid concentration, and acidity.

For this reason, under climate change, the introduction of irrigation represents a complex issue. In fact, it is not only important to guarantee water to the plants, but to maintain a specific water stress during the ripening phase of the grapes.

From this perspective, the aim of this contribution is to show the first results of a task of Spoke 3 of the National Research Center for "Agriculture Technologies - Agritech" (NextGenerationEU European program) on the identification of procedures for the optimized management of the water resource in vineyards.

The research adopts multidisciplinary approaches and methods to support irrigation optimization in the vineyard. It has been based on two main steps: (i) the identification of the functional homogeneous zones (fHZs) present in the vineyard through an environmental analysis based on the determination of the soil spatial variability, the micro-morphology of the vineyard (LIDAR) and the spatial variability of the crop response at different resolutions (UAV); (ii) use and test of field sensors to monitor plant and soil water status in the fHZs in order to define the optimal timing and volume of irrigation to achieve the desired field oenological goals while preserving the water resource.

The experiment has been realized in an Aglianico vineyard (2 ha) of Tenuta Donna Elvira winery (Montemiletto – AV), where climate, plant, and soil are monitored through the use of commercial and non-commercial sensors. In particular, two weather stations and seven monitoring nodes (soil TDR probes at three soil depths) have been distributed within the irrigated and non-irrigated long plots. The plants were monitored continuously (hourly time step) by means of a new in vivo sensor developed by IMEM CNR institute, Bioristor, (applied to 16 plants to monitor the plant status) and discontinuously (weekly or two-weekly time step) plant measurements (e.g., UAV multispectral measurements, LWP, yield production, grapes quality,..etc..).

The irrigation supply was realized through an automated irrigation system (MySOLEM) and defined according to the leaf water potential (LWP) measured in the field, maintaining its value between 1.2 and 1.4 bar during the ripening period.

At the end of the first year, the analysis of collected data to develop a vineyard water management model able to support achieving oenological goals and facing climate change has been realized.

How to cite: Vitale, A., Janni, M., Buonanno, M., Erbaggio, A., Albrizio, R., Giorio, P., De Micco, V., Cirillo, C., Petracca, F., Giaccone, M., Vurro, F., Palermo, N., Bettelli, M., and Bonfante, A.: How can we support irrigation management in viticulture to preserve grape quality in southern Italy?: the case study of Aglianico grapevine., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18792, https://doi.org/10.5194/egusphere-egu24-18792, 2024.

EGU24-19498 | ECS | Posters virtual | SSS9.17

Development of a System Dynamics based Irrigation Demand Model 

Aurobrata Das, Bhabagrahi Sahoo, and Sudhindra Nath Panda

Water resources globally are under severe threat due to population growth, intensive socio-economic development, change in climatic condition and increasing level of conflict among multiple water users. Under this context, an accurate and efficient supply-demand management of this critical resource is highly essential to ensure the water security of a region. Agriculture being the major water user, needs to be given primary importance. However, in canal command areas, there is an inefficient management of irrigation system without considering the real-time irrigation demand while supplying the irrigation water from the reservoir. This leads to either surplus or deficit irrigation supply throughout the year affecting both the water sector and the crop yield of the command. The real-time irrigation demand of a command depends upon the type of crops grown, antecedent soil moisture content and meteorological variables along with the social attributes of the stakeholders. Hence, this current study tries to develop a dynamic irrigation demand model comprising of all the afore-mentioned variables under system thinking approach. The causal feedback among the system elements were developed initially through causal loop diagram and the model variables were subsequently transformed into stocks and flows, representing the dynamic state of the system in order to develop the conceptual model. The developed model was tested in the Hirakud canal command located in the eastern part of India simulating the real system effectively. This developed model can be used by the water managers for efficient irrigation planning in a canal command ensuring overall water and food security of the region.

How to cite: Das, A., Sahoo, B., and Panda, S. N.: Development of a System Dynamics based Irrigation Demand Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19498, https://doi.org/10.5194/egusphere-egu24-19498, 2024.

EGU24-19943 | ECS | Orals | SSS9.17

Determination of soil Hydraulic Properties using infiltration models and Hydrus 1D. Application to soils in Semi-Arid Regions 

Sara E. Matendo, Raúl Sánchez, Luis Juana, and Sergio Zubelzu

Arid and semi-arid regions present significant challenges in efficient irrigation management and mitigation of soil salinity. To understand the dynamics of water and solute movement, such as salt transport in soil, software tools like HYDRUS are widely utilized. Hydrus-1D uses linear finite elements to numerically solve the Richards equation for saturated-unsaturated water flow, and has been widely applied in irrigation management to focus on solute and water movement.

This research focuses on estimating the hydraulic properties at field scale level using Kenyan soil data analyzed with soil spectroscopy and infiltration experiments. Saturated hydraulic conductivity (Ks) has been obtained by fitting data to infiltration obtained by the Green-Ampt (GA) model and Hydrus1D in three scenarios: with bounds on Ks and the product of front suction and effective porosity, assigning a uniform value to effective porosity and considering flow preferential paths. The results are compared with others pedotransfer functions (PTFs) and Hydrus-1D.

The Hydrus-1D software was used to study the water retention curve due to different Ks estimations. The findings show significant variations in the Ks estimations, highlighting the impact of salinity and preferential flows in heterogeneous soils. The comparison of the results provides valuable insights into the dynamics of water and salinity, essential for irrigation management in these regions.

This research emphasizes how crucial it is to choose and modify hydrological models for particular salinity situations and how important it is to take into account spatial variability and flow preferential paths when predicting and applying Ks through models. The results have significant implications for improving irrigation management and controlling soil salinity in semi-arid regions.

 

Keywords: Saturated hydraulic conductivity, Green-Ampt, HYDRUS-1D, irrigation management, soil salinity control.

 

"ACKNOWLEDGMENT

This article belongs to PCI2020-120694-2 Project funded by MCIN/AEI/10.13039/ 501100011033 and the European Union “NextGenerationEU”/PRTR.

We would like to thanks to One Planet Fellowship from African Women in Agricultural Research and Development (AWARD) and Agropolis Fondation for funding the analysis. “

How to cite: Matendo, S. E., Sánchez, R., Juana, L., and Zubelzu, S.: Determination of soil Hydraulic Properties using infiltration models and Hydrus 1D. Application to soils in Semi-Arid Regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19943, https://doi.org/10.5194/egusphere-egu24-19943, 2024.

EGU24-22334 | ECS | Orals | SSS9.17

Improvement of irrigation water productivity through water deficit and biostimulation in pepper under greenhouse conditions 

Susana Zapata García, Abdelmalek Temnani, Pablo Berrios, Raúl D. Pérez-López, Claudia Monllor, and Alejandro Pérez-Pastor

The south-east of Spain faces a complex water scarcity scenario. Even though those regions have a high agricultural activity due to the advanced production system that has been developed. As it is important to optimize the use of water, from an economy, environmental and social point of view in these regions, it is needed to combine all available tools, including the technological and agnomical ones. Regulated deficit irrigation (RDI) techniques have been proved to be an efficient method of saving water in woody crops. Our hypothesis is that, as these RDI would cause a higher water stress in horticultural crops, that could be faced by biostimulation, as one of biostimulants claims is to improve the plant tolerance to abiotic stress, leading them to obtain a higher yield. This study aims to evaluate the effect of different strategies that combine the application of seaweed and microbials biostimulants with deficit irrigation programmes on the production parameters and soil quality in pepper (Capsicum annum sp.) under commercial greenhouse conditions.

With this aim two trials were carried out in commercial greenhouses (U & V), each one with two treatments:  i) irrigation according to Farmer criteria and ii) a combined treatment of RDI and the same biostimulation programme, that consisted of two application of Bacillus paralicheniformis after transplant via fertigation and four biweekly applications of Ascophillum nodosum extracts via fertigation and foliar spray. In each greenhouse, RDI was applied in different phenological stages,  from the onset of blooming to harvest in U trial or during the harvest in V trial.

The irrigation was reduced approximately 600 m3 ha-1, implying a 12% savings respect to the Farmer irrigation schedule. The pepper yield had not been negatively affected, increasing the water productivity when RDI is combined with biostimulation. It is worth noting that when a water stress was applied, flowering and fruit setting seems to be promoted in biostimulated treatment, leading to a higher yield that non-biostimulated. Globally, the yield improvement has been due to a higher harvest of 1st quality fruits.

This combined treatment has also improved the soil enzymatic activity in both greenhouses, suggesting that nutrients in the soil will become more available to plants when those are biostimulated.

Thus, the combined action of biostimulation under different strategies of irrigation reduction have been proved to be a useful strategy to improve agricultural sustainability, as it has increased the water productivity of the crop and the microbiological activity in the soil.

How to cite: Zapata García, S., Temnani, A., Berrios, P., Pérez-López, R. D., Monllor, C., and Pérez-Pastor, A.: Improvement of irrigation water productivity through water deficit and biostimulation in pepper under greenhouse conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22334, https://doi.org/10.5194/egusphere-egu24-22334, 2024.

SSS10 – Metric, Informatics, Statistics and Models in Soils

EGU24-740 | Posters on site | SSS10.6

Comparison of advanced multicriteria decision and FAO models for land suitability assessment  

Kamal Nabiollahi, Fereshteh Molani, Ruhollah Taghizadeh-Mehrjardi, Mohammad Hossein Tahari-Mehrjardi, Hadi Shokati, Pegah Khosravani, Ndiye Kebonye, and Thomas Scholten

Land suitability assessment is an important process in modern agricultural management, involving the evaluation of various factors such as soil properties, climate, relief, hydrology, crop varieties and socio-economic considerations. Various methods have been used to assess land suitability, such as the parametric method developed by Sys et al. (1991) and the FAO (1976) approach to land evaluation. Determining the relative weighting of the factors that influence land suitability is a particularly challenging step in the evaluation process. An alternative to these procedures is the use of multi-criteria decision making (MCDM) techniques, which enable land managers and policy makers to make informed decisions about land use and development. Spatial MCDM techniques include complex spatial data and methods such as the Technique of Preference Ordering by Similarity to the Ideal Solution (TOPSIS), which are widely used in the agricultural sector. TOPSIS determines the optimal alternative according to the principle of minimizing the proximity to the ideal solution and maximizing the distance to the negative ideal solution. The aim of this study was to assess the suitability of land for wheat cultivation in western Iran, a country facing the challenge of becoming self-sufficient in wheat. Seventy soil profiles were selected and described on the basis of a geomorphologic map and the content of various soil properties and wheat yield were determined. MCDM (TOPSIS) and FAO models were applied and evaluated according to wheat yield. The Shannon entropy method (SHE) was used to extract the criteria weights. Land suitability assessment was mapped using a Random Forest machine learning model and auxiliary variables. According to the results of the Shannon entropy method, slope, cation exchange capacity (CEC) and calcium carbonate equivalent (CCE) are the most important criteria for wheat cultivation. Furthermore, the results are also confirmed by the spatial autocorrelation between the key criteria and wheat yield. These results also show that the soil suitability values calculated with the TOPSIS model have a higher correlation with wheat yield than the values calculated with the FAO model (0.73 and 0.67, respectively). The spatial distribution of the suitability values for wheat cultivation showed that 30 to 33% of the areas were very suitable, 13-16% moderately suitable and 51% and 57% unsuitable. For the areas with high and medium suitability, the TOPSIS and FAO results were largely in agreement, in contrast to the areas with low suitability. This study provided a comprehensive approach to land suitability for wheat cultivation using advanced MCDM techniques and machine learning, which can be beneficial for sustainable land management and food security in Iran and similar regions.

How to cite: Nabiollahi, K., Molani, F., Taghizadeh-Mehrjardi, R., Tahari-Mehrjardi, M. H., Shokati, H., Khosravani, P., Kebonye, N., and Scholten, T.: Comparison of advanced multicriteria decision and FAO models for land suitability assessment , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-740, https://doi.org/10.5194/egusphere-egu24-740, 2024.

EGU24-1375 | Orals | SSS10.6

Acid sulfate soil mapping in western Finland: How to work with imbalanced datasets and machine learning 

Virginia Estévez, Stefan Mattbäck, Anton Boman, Pauliina Liwata-Kenttälä, Kaj-Mikael Björk, and Peter Österholm

One of the main challenges in digital soil mapping is the imbalanced datasets for soils classification. For these datasets, machine learning techniques use to overestimate the majority classes and underestimate the minority ones. In general, this generates maps with poor precision and unrealistic results. Considering these maps for land use decision-making can have dire consequences. This is the case of acid sulfate (AS) soils, a type of harmful soil that can generate serious environmental damage when drained in agricultural or forestry activities. In the study area, the probability of finding AS soils is very high. Furthermore, some of the most hazardous AS soils in Finland are located there [1]. Therefore, it is necessary to create high-precision maps to avoid environmental damage. Since the dataset for this region is highly imbalanced, the first step in creating accurate maps is to balance the dataset. Although most  soil class datasets in nature are imbalanced, this problem has been hardly studied. In this work, we analyze different techniques to address the problem of imbalanced datasets. The methods considered to balance the dataset are under- and oversampling techniques and the combination of both. For the oversampling of the minority class, we create a kind of artificial samples from the quaternary geological map. The method used for the modeling is Random Forest, one of the best methods for the classification of AS soils [2,3]. Balancing the dataset improves the performance of the model in all the studied cases, where the values of the metrics for both classes are above 80%. Furthermore, we create AS soil probability maps for the four balanced datasets and the imbalanced dataset. A detailed comparison between the maps is made. In addition, the extent of the AS soils obtained in all the cases is compared with the extent of the AS soils in the conventionally produced occurrence map [1]. The modeled probability maps created from the balanced datasets have a high precision. The results of this study confirm the importance of balancing the dataset to improve the prediction and classification of AS soils.

[1] Geological Survey of Finland. Acid Sulfate Soils–map services http://gtkdata.gtk.fi/hasu/index.html 

[2] V. Estévez et al. 2022.  “Machine learning techniques for acid sulfate soil mapping in southeastern Finland”. Geoderma 406, 115446.

[3] V. Estévez et al. 2023. “Improving prediction accuracy for acid sulfate soil mapping by means of variable selection”. Front. Environ. Sci. 11:1213069.  doi: 10.3389/fenvs.2023.1213069

 

 

How to cite: Estévez, V., Mattbäck, S., Boman, A., Liwata-Kenttälä, P., Björk, K.-M., and Österholm, P.: Acid sulfate soil mapping in western Finland: How to work with imbalanced datasets and machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1375, https://doi.org/10.5194/egusphere-egu24-1375, 2024.

EGU24-1659 | ECS | Orals | SSS10.6

Mapping Soil Strength Markers at Field Scale Using Proximal Sensors 

Ameesh Khatkar, Amélie Beucher, Triven Koganti, Lars Juhl Munkholm, and Mathieu Lamandé

The current agricultural system allows farm machinery to operate randomly, thus compacting around 23-33% of the land with critical levels in Europe. To tackle this issue, the European Union (EU) has launched the mission ‘A Soil Deal for Europe’ under the Horizon Europe program, this mission aims to have healthy soil by 2030. Mitigating soil compaction to improve soil structure has been selected as one of the eight objectives of this mission. It is evident from past research that with the increasing size and weight of farm machinery, soil compaction has become a significant threat to top and sub-soil; however, subsoil compaction is even more persistent and cumulative than topsoil. Therefore, within the SOLGRAS project, we emphasize both surface and sub-surface soil compaction. The ability of soil to withstand the soil compaction is governed by its soil strength. This soil strength depends on many soil properties, such as soil water content, bulk density, texture, and organic matter content. We aim to map these soil properties as a first step before predicting soil strength at the field level. Since proximal sensors provide rapid, low-cost, non-destructive measurements, they have significantly enhanced digital soil mapping. In this project, we have used geophysical sensors based on electromagnetic induction and gamma-ray radiometric principles to predict the above-mentioned soil properties at the field level in Denmark. The geophysical survey and collection of soil samples were performed on the same day for each of the three chosen farmer fields. Here, we present our results of predicted soil properties obtained via the proximal sensors and a limited number of laboratory-measured values. Samples of 100 cc undisturbed soil cores and bags were collected from the surface (15-cm depth) and sub-surface (40-cm depth) at 23 sampling sites for each field. Data from these sampling sites are used to train and validate our models for predicting soil properties associated with soil strength. These predicted high-resolution maps produced at the field level will enable us to set up optimum vehicular specifications and routes before entering the field.

How to cite: Khatkar, A., Beucher, A., Koganti, T., Munkholm, L. J., and Lamandé, M.: Mapping Soil Strength Markers at Field Scale Using Proximal Sensors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1659, https://doi.org/10.5194/egusphere-egu24-1659, 2024.

EGU24-1755 | ECS | Orals | SSS10.6

Machine learning based pedotransfer function improves soil bulk density prediction but not for soil organic carbon stock 

Songchao Chen, Zhongxing Chen, Xianglin Zhang, Zhongkui Luo, Calogero Schillaci, Dominique Arrouays, Anne Richer-de-Forges, and Zhou Shi

Being a fundamental indicator of soil health and quality, soil bulk density (BD) plays an important role in plant growth, nutrient availability, and water retention. Due to its limited availability of BD in databases, pedotransfer functions (PTFs) has been widely used in predicting BD, while the impact of PTFs’ accuracy on soil organic carbon (SOC) stock calculation has not been explored. Herein, we proposed a local modeling approach for predicting BD across EU and UK using LUCAS Soil 2018. Our approach involved a combination of neighbor sample search, Forward Recursive Feature Selection (FRFS) and Random Forest (RF) model (local-RFFRFS). The results showed that local-RFFRFS had a good performance in predicting BD (R2 of 0.58, RMSE of 0.19 g cm-3), surpassing the traditional PTFs (R2 of 0.40-0.45, RMSE of 0.22 g cm-3) and global PTFs using RF with and without FRFS (R2 of 0.56-0.57, RMSE of 0.19 g cm-3). Interestingly, we found the best traditional PTF (R2=0.84, RMSE=1.39 kg m-2) performed close to the local-RFFRFS (R2=0.85, RMSE=1.32 kg m-2) in SOC stock calculation using BD predictions. However, the local-RFFRFS still performed better (ΔR2>0.2 and ΔRMSE>0.1 g cm-3) for soil samples with low SOC stock (<3 kg m-2). Therefore, we suggest that the local-RFFRFS is a promising method for BD prediction while traditional PTFs would be more efficient when BD is subsequently utilized for calculating SOC stock.

How to cite: Chen, S., Chen, Z., Zhang, X., Luo, Z., Schillaci, C., Arrouays, D., Richer-de-Forges, A., and Shi, Z.: Machine learning based pedotransfer function improves soil bulk density prediction but not for soil organic carbon stock, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1755, https://doi.org/10.5194/egusphere-egu24-1755, 2024.

EGU24-1764 | ECS | Orals | SSS10.6

Comparison of direct and indirect approaches for mapping soil organic carbon stock 

Zhongxing Chen, Qi Shuai, Zhou Shi, Dominique Arrouays, Anne Richer-de-Forges, and Songchao Chen

Soil organic carbon (SOC) is a critical factor influencing global carbon cycling. Accurate estimates of its spatial distribution are essential for addressing global climate change. Digital soil mapping has demonstrated significant potential in providing precise and high-resolution spatial information about SOC across various scales. We conducted an evaluation of two soil mapping approaches for SOCD estimates in France: the direct approach (calculate-then-model) and the indirect approach (model-then-calculate). Our study utilized 916 topsoil samples (0−20 cm) from the LUCAS Soil 2018 dataset and 24 environmental covariates. We employed a random forest model and forward recursive feature selection to build spatial predictive models of SOCD using both the direct and indirect approaches. The results revealed that, with the random forest model and full covariates, both approaches demonstrated moderate performance (R2 = 0.28−0.32). Through the use of forward recursive feature selection, the number of predictors was reduced from 24 to 9, leading to enhanced model performance for the direct approach (R2 of 0.35), while no improvement was observed for the indirect approach (R2 of 0.28). The mean SOCD of French topsoil was estimated at 5.29 and 6.14 kg m−2 using the direct and indirect approaches, respectively, resulting in SOC stocks of 2.8 and 3.3 Pg, respectively. Notably, the indirect approach exhibited better performance in estimating high SOCD. These findings serve as a valuable reference for SOCD mapping.

How to cite: Chen, Z., Shuai, Q., Shi, Z., Arrouays, D., Richer-de-Forges, A., and Chen, S.: Comparison of direct and indirect approaches for mapping soil organic carbon stock, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1764, https://doi.org/10.5194/egusphere-egu24-1764, 2024.

Digital soil mapping relies on statistical relationships between soil profile observations and environmental covariates at the sample locations. However, inherent limitations of legacy soil profiles, such as inaccurate georeferencing and inconsistent sampling techniques, frequently introduce location errors into these soil profiles that greatly affect the quality of digital soil mapping. To address this challenge, this study focuses on reducing the location error of legacy soil profiles and evaluating the resulting impact on digital soil mapping. We enhanced the consistency between environmental covariates (i.e., elevation, slope and land use) with relative high accuracy and detailed descriptive information of legacy soil profiles to reduce the location error of legacy soil profiles. We constructed quantile regression forest models to predict soil properties and their uncertainty at different depths using soil profiles before and after location error correction. Our results demonstrate that for the majority of soil variables, correcting positional errors in legacy soil profiles significantly enhances the accuracy of the digital soil mapping. The largest improvement was found for soil organic carbon at 5 cm depth, with 21% increase of   R^2. The impact of reduced location error is particularly noteworthy in regions characterized by complex terrain or sparse sampling. In addition, the accuracy and details of the predicted maps are significantly improved, which better represent the spatial variation of soil attributes across China. Besides, we also found that elevation was the primary controlling factor for correcting location error of legacy soil profiles, followed by land use and slope. This research presents a significant step towards producing high-resolution and high-quality spatial soil datasets, which can provide essential support for soil management and ensure future soil security.

How to cite: Shangguan, W. and Shi, G.: Reducing location error of legacy soil profiles leads to significant improvement in digital soil mapping, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2255, https://doi.org/10.5194/egusphere-egu24-2255, 2024.

EGU24-2892 | Posters virtual | SSS10.6

A Role of Remote Sensing Analysis for Archaeological Purposes in Arid Climate Regions 

Lev Eppelbaum, Michal Birkenfeld, and Olga Khabarova

The modern state of Israel is located between 29o and 33o north of the Earth’s equator. It is a small (about 22,000 km2) subtropical region between the temperate and tropical zones, characterized chiefly by semi-arid and arid climates. Such climate causes increased productivity and water-use efficiency due to elevated CO2, which tends to increase ground cover, counteracting the effects of higher temperatures. As a result of this effect, Israel, while small in size, exhibits complex soil formations with variable physical properties, even within small areas. Despite its comparatively diminutive dimensions, Israel has been a focus of human exploitation and settlement since the earliest days of human expansion. More than 27,000 recorded sites form a long record of human presence in the area, starting around 1.5 Mya, presenting one of the densest national archaeological records in the world. While some sites are still clearly visible on the surface, most ancient remains of various ages and origins occur in the subsurface layers at depths of 0.5-8 m (usually in multi-layered archaeological sites). Hundreds, if not thousands, of new sites are discovered yearly due to construction and development activities, and more than 300 salvage excavations are conducted by the Israel Antiquities Authority yearly. Traditional archaeological survey methods are based on covering transects of areas by foot and, while prolific, are by nature highly time-consuming and costly. Moreover, they usually do not supply information on the extent and character of sub-surface remains. Different attempts have been made over the years to apply surface geophysical methods (e.g., GPR, ERT, magnetic, paleomagnetic, subsurface seismics, self-potential, thermal, VLF, induced polarization, piezoelectric, and microgravity) for the identification of archaeological remains as rapid, effective, and noninvasive alternatives for ‘traditional’ archaeological survey methods. However, these attempts have not always been successful, mainly because of the environmental variability and complex physical-archaeological conditions. Remote Sensing (RS) is a low-expensive tool used for detecting and monitoring the physical attributes of objects of interest on or below the Earth’s surface from a considerable distance. RS has been proven instrumental in archaeological investigations and in comprehending historical contexts on a large scale. This is attributed to RS’s rapid data acquisition, expansive coverage, high resolution, and spectral sensitivity to anomalies associated with surface, subsurface, buried, and underwater archaeological features. Archaeologists gain aid in enhanced discoveries and comprehension of archaeological context by utilizing passive and active sensors on drones, satellites, aircraft, and uncrewed aerial vehicles. Active RS (such as radar and LiDAR) offers advantages in detecting buried sites in deserts or concealed archaeological landscapes within forested areas compared to passive RS (encompassing photography and multi-/hyperspectral techniques). The advanced RS application in Israel enabled the unmasking of unknown archaeological targets in the Wadi Asekt (northern Israel) and the Biq’at Sayyarim (southern Israel). Detailed surface geophysical studies (GPR and magnetic) and archaeological investigations will be conducted at the following stage in the selected areas. Information theory approaches and modern wavelet methodologies will be applied to integrate RS data numerically with geophysical (and possibly geochemical) methods.

How to cite: Eppelbaum, L., Birkenfeld, M., and Khabarova, O.: A Role of Remote Sensing Analysis for Archaeological Purposes in Arid Climate Regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2892, https://doi.org/10.5194/egusphere-egu24-2892, 2024.

EGU24-3053 | ECS | Orals | SSS10.6

A Physics-Driven Spectroscopic Approach for Rapid Estimation of the Soil Water Retention Curve 

Sarem Norouzi, Morteza Sadeghi, Markus Tuller, Hamed Ebrahimian, Abdolmajid Liaghat, Scott B. Jones, and Lis W. de Jonge

The knowledge about soil hydraulic properties (i.e., water retention and hydraulic conductivity characteristics) is of relevance for accurate determination of land surface fluxes. Yet, the laborious and time-consuming process of measuring the soil water retention curve (SWRC) with conventional laboratory methods poses a challenge. In addition, the measured soil water content and matric potential pairs obtained with standard methods are often fragmentary and consist of only a limited number of measurements across the desired soil water content range. Proximal and remote sensing methods are rapid and cost-efficient alternatives to quantify soil attributes across different scales. However, past studies that centered around proximal and remote sensing of soil hydraulic functions mainly rely on statistical relationships and a physically-based method is still lacking. In this presentation, we introduce an innovative physics-based laboratory method that allows the direct estimation of the complete SWRC across the entire range from saturated to dry conditions. The inputs to the model include measured data pairs of soil water content and reflectance within the shortwave infrared domain. The fundamental hypothesis behind the new method is that the soil reflectance spectra are a function of both soil water content and the pore scale distribution of capillary and adsorbed soil water. The performance of the proposed model was evaluated for 21 soils that vastly differ in physical and hydraulic properties. The RMSE and R-squared between retrieved and measured water contents at various matric potentials were found to be 0.03 m³ m⁻³ and 0.96, respectively, indicating the good performance of the proposed method. The results suggest that the new method is a rapid and efficient alternative to established laboratory measurement methods.

How to cite: Norouzi, S., Sadeghi, M., Tuller, M., Ebrahimian, H., Liaghat, A., Jones, S. B., and de Jonge, L. W.: A Physics-Driven Spectroscopic Approach for Rapid Estimation of the Soil Water Retention Curve, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3053, https://doi.org/10.5194/egusphere-egu24-3053, 2024.

EGU24-4248 | Orals | SSS10.6

Hyperspectral Remote Sensing of Saline Soils in Arid and Semi-Arid Environments 

Abdelgadir Abuelgasim and Alya Aldhaheri

Remote sensing of saline soils has been an active area of research in the past few decades. This is particularly so as soil salinity is a major environmental geo-hazard in both agricultural lands and arid and semi-arid regions. Saline soil adversely affect soil and play a major role in soil erosion, dispersion and degradation. Furthermore, saline soils in arid and semi-arid regions lead, in certain situations, to land subsidence, and ground upheaval. In agricultural lands saline soils lead to reduced agricultural productivity, interference with plant nutrition and soil erosion.

Mapping saline soils is carried out using various techniques and procedures ranging from direct field observations and sampling to space based remote sensing techniques. Traditional methods of measuring soil salinity are time-consuming and labor intensive, making remote sensing techniques an attractive alternative. Remote sensing provides a less costly procedure due to the large global spatial coverage, continuous repetitive coverage and high-quality earth observations. Most of the remote sensing of saline soils previous research have focused on the broad band remote sensing part with primary focus on the spectral ranges in the near infra-red and the short-wave infra-red. However, higher levels of detection accuracy has not been widely achieved.

In comparison to broad band remote sensing data, hyperspectral remotely sensed data provides an alternative approach that is much more accurate in detection levels of saline soils and their spatial distribution. This research employed a hand-held hyperspectral sensor specifically the SVC-XHR-1024i to collect reflectance data over various samples of soils collected in western United Arab Emirates. The collected data were then processed to derive spectral indices that are sensitive to soil salinity. Laboratory measurements of electrical conductivity (EC) of soil water extracts were carried out for the corresponding soil samples. The study established a statistical relationship between measured soil hyperspectral reflectance and EC salinity values. The study findings indicate that the spectral ranges in the shortwave infrared (SWIR) and near-infrared (NIR) are crucial and optimal in detecting soil salinity, in comparison to any other spectral ranges. An accuracy of 71% in detecting saline soils, including salt flats, was achieved through the use of narrow band hyperspectral data at the SWIR and NIR ranges. This by far exceeds accuracy levels that were previously achieved using broad band remote sensing data. The study also, highlights the potential of hyperspectral remote sensing as a cost-effective and efficient tool for monitoring soil salinity and identifying areas at risk of salinization, which can inform land management strategies for sustainable agriculture and future land development.

How to cite: Abuelgasim, A. and Aldhaheri, A.: Hyperspectral Remote Sensing of Saline Soils in Arid and Semi-Arid Environments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4248, https://doi.org/10.5194/egusphere-egu24-4248, 2024.

EGU24-4622 | ECS | Orals | SSS10.6

A new framework for retrieving bare soil information using multi-temporal Sentinel-2 images across China 

Jie Xue, Xianglin Zhang, Songchao Chen, Ye Su, and Zhou Shi

Detailed soil spatial information is a worldwide need for monitoring soil quality, especially in agricultural region. Remote sensing technology has evolved as a powerful tool for characterizing spectral reflectance of bare soil, which is the perquisite for retrieving soil information. However, existing methodologies were mostly designed to extract bare soil information from single satellite image, which is prone to cloud contamination and phenological variation. Although some composite algorithms based upon multitemporal images were proposed for soil mapping, they were all designed for coarse-resolution satellite dataset; besides, their generalization ability over a large scale (e.g., national) remains poorly explored. To fill the knowledge gap, we proposed a new framework, namely Two-Dimensional Bare Soil Separation (TDBSS), for extracting continuous bare soil information at 10-m spatial resolution based on multi-temporal Sentinel-2 images for cropland across China. The TDBSS used Soil Adjusted Vegetation Index and Green-Red Vegetation Index as two-dimensional indicators. The optimal thresholds for these two indicators were further obtained across two dimensions based upon ecoregion-specific samples. These thresholds were further applied for nine primary agricultural zones in China and subsequently adapted for the entire country. We also compared the framework with three widely used bare soil detecting algorithms (i.e., Geospatial Soil Sensing System (GEOS3), soil composite processor (SCMaP), and Barest Pixel Composite (BPC)) using the spatial accuracy. The TDBSS performed the best with an overall accuracy (OA = 78.28%), while SCMaP showed the lowest OA of 29.25%. The results showed the TDBSS was an effective method for a large-area mapping of bare soil. The resultant bare soil composite map holds great significance for further retrieving soil properties for Chinese cropland. TDBSS is computationally efficient and readily applied for a broad spatial scale, which is practically crucial to the food security, land management, and precision agriculture policymaking.

How to cite: Xue, J., Zhang, X., Chen, S., Su, Y., and Shi, Z.: A new framework for retrieving bare soil information using multi-temporal Sentinel-2 images across China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4622, https://doi.org/10.5194/egusphere-egu24-4622, 2024.

Evaluating the effectiveness of remote sensing-based vegetation indices in estimating the spatio-temporal distribution of Nitrogen rates

One of the main objectives of precision agriculture is to optimize nitrogen fertilizer application management. This study aimed to assess the efficacy of different vegetation indices derived from satellite data in estimating soil ammonium and nitrate values during the corn growing season. To achieve this, multi-temporal Sentinel-2 images and ground data including ammonium and soil nitrate values measured at specific ground stations throughout the corn growing season for Hunter field, Canada, were utilized. Firstly, various vegetation indices including NDVI, EVI, MSAVI, ARVI, GNDVI, and OSAVI were calculated for different dates throughout the crop growing season. Subsequently, the Pearson correlation between these vegetation indices and temporal variations in soil ammonium and nitrate values during the growing season was examined. Moreover, the relationship between vegetation indices at the crop growth peak and the amount of fertilizer applied to the soil during planting was investigated. The findings indicated that the average correlation coefficients between total soil nitrate and ammonium values throughout the growing season and the NDVI, EVI, MSAVI, ARVI, GNDVI, and OSAVI indices were -0.67, -0.72, -0.69, -0.68, -0.73, and -0.70, respectively. Furthermore, the average correlation coefficients between these indices at the growth peak and the cumulative ammonium and nitrate applied at planting were 0.60, 0.60, 0.64, 0.60, 0.68, and 0.64, respectively. The correlation coefficient and root mean square error (RMSE) between the measured and modeled sum of ammonium and nitrate, based on the six vegetation indices in a multivariate form, were 0.89 and 17.3 mg, respectively.

How to cite: Biswas, A., Fathololoumi, S., and Sulik, J.: Evaluating the effectiveness of remote sensing-based vegetation indices in estimating the spatio-temporal distribution of Nitrogen rates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4671, https://doi.org/10.5194/egusphere-egu24-4671, 2024.

EGU24-5803 | ECS | Posters on site | SSS10.6

Soil particle size distribution using the integral suspension pressure method (ISP) and gamma-ray spectrometry techniques for soil texture mapping. 

Brenda Trust, Arsenio Toloza, Jason Mitchell, Matthias Konzett, Hami Said Ahmed, Modou Mbaye, Gerd Dercon, and Peter Strauss

Understanding the role of soil texture in soil-water management amid climate change is crucial for sustainable agriculture as it influences water availability, nutrient dynamics, erosion control, carbon sequestration, and overall soil health. Therefore, having soil texture mapping is an important decision tool for establishing sustainable resource management.

In this study, we present findings from soil sampling conducted in 2023 and a decade earlier from Hydrological Open-Air Laboratory (HOAL) in Petzenkirchen, Lower Austria. The PARIO system was used to analyse soil particle distribution utilising the Integral Suspension Pressure (ISP) method. This method utilizes the stokes’ law to calculate the particle size distribution based on changes in suspension pressure and temperature. The change of suspension pressure as well the temperature is measured at 10- seconds intervals following the chemical and physical dispersion, along with the pretreatment of soil samples involving the removal of organic matter, soluble salts and determination of sample dry weight.

The analysis of soil texture from the 2023 soil sampling, conducted using the PARIO system, revealed a predominant silty clay loam structure, with a particle distribution of 9% sand, 56% silt, and 35% clay, aligning closely with results from a decade prior. Concurrently, we utilized Gamma-Ray Sensor (GRS) technology to measure the spatial activity concentrations (Bq.kg-1) of 40K (potassium), 238U (uranium), and 232Th (thorium) over more 20 points across the fields. The aim was to correlate these radionuclide concentrations with soil texture data using a Python-based correlation model. Preliminary results showed the best correlation between 40K radionuclide concentrations versus clay (R2 = 0.8) and silt (R2 = 0.7) and 238U versus silt (R2= 0.7). Thus, spatial monitoring of 40K and 238U with mobile GRS can be used for spatial determination of clay and silt. Nevertheless, further analysis is essential to compare and validate these results with a more extensive dataset encompassing additional soil texture data.

These preliminary results demonstrate the potential of monitoring 40K and 238U concentrations by a portable gamma sensor for soil texture mapping in agricultural land. Further analysis and validation are required to verify the robustness of this model.

How to cite: Trust, B., Toloza, A., Mitchell, J., Konzett, M., Said Ahmed, H., Mbaye, M., Dercon, G., and Strauss, P.: Soil particle size distribution using the integral suspension pressure method (ISP) and gamma-ray spectrometry techniques for soil texture mapping., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5803, https://doi.org/10.5194/egusphere-egu24-5803, 2024.

EGU24-6005 | ECS | Orals | SSS10.6

Uncertainty in Digital Soil Mapping at broad-scale: A review 

Qianqian Chen, Anne Richer-de-Forges, Songchao Chen, Emmanuelle Vaudour, Antonio Bispo, and Dominique Arrouays

With the needs of efficient acquisition of soil information, Digital Soil Mapping (DSM) has been greatly developed and widely applied for over the past two decades. The spatial estimates of soil properties produced with diverse methods over various study areas, have been often seen as the main output of DSM, as they play an important role in environmental modelling and policy. However, compared with the soil property maps, their prediction uncertainty is still less emphasized, which may potentially lead to mis-uses of results and inappropriate decisions if the uncertainty is not assessed, reported, and taken into account by end-users.
In this communication, we present a preliminary review of the sources of prediction uncertainties in DSM coming from learning soil data (data source, sampling in space and time, measurements), covariates, and models. We also summarize the methods used to estimate the uncertainty, and to assess the reliability of the uncertainty estimates. We also consider the propagation of uncertainties when several soil attributes are combined to derive information and/or used as inputs for modelling. Furthermore, we discuss some strategies for mitigating the uncertainty, challenges, and future perspectives. This review aims to consolidate the understanding of DSM uncertainties and to contribute to reliable DSM practices, facilitating more informed decision-making in soil-related research and management. 

How to cite: Chen, Q., Richer-de-Forges, A., Chen, S., Vaudour, E., Bispo, A., and Arrouays, D.: Uncertainty in Digital Soil Mapping at broad-scale: A review, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6005, https://doi.org/10.5194/egusphere-egu24-6005, 2024.

EGU24-6172 | ECS | Orals | SSS10.6

Hierarchical modelling in digital soil mapping: Advantages for mapping bimodal soil pH 

Madlene Nussbaum, Stephan Zimmermann, Lorenz Walthert, and Andri Baltensweiler

Maps of soil pH are an important tool for making decisions in sustainable forest management. Accurate pH mapping, therefore, is crucial to support decisions by authorities or forest companies. Soil pH values typically exhibit a distinct distribution characterized by two frequently encountered pH ranges, wherein aluminium oxides (Al2O3) and carbonates (CaCO3) act as the primary buffer agents. Soil samples with moderately acid pH values (pH CaCl2 of 4.5-6) are less commonly observed due to their weaker buffering capacity. The different strength of buffer agents results in a distinct bimodal distribution of soil pH values with peaks at pH of around 4 and 7.5. Commonly used approaches for spatial mapping neglect this often observed characteristic of soil pH and predict unimodal distributions with too many moderately acid pH values. For ecological map applications this might result in misleading interpretations.

This study presents a novel approach to produce pH maps that are able to reproduce pedogenic processes. The procedure is suitable for bimodal responses where the response distribution is naturally inherent and needs to be reproduced for the predictions. It is model-agnostic, namely independent from the used statistical prediction method. Calibration data is optimally split into two parts corresponding each to a data culmination, i.e. for soil pH values belonging to the ranges of the two principal buffer agents (Al2O3 and CaCO3). For each subset a separate model is then built. In addition, a binary model is fitted to assign every new prediction location a probability to belong either to Al2O3 or CaCO3 buffer range. Predictions are combined by weighted mean. Weights are derived from probabilities predicted by the binary model. Degree of smoothness is chosen by sigmoid transform which allows for optimal continuous transition of the pH values between Al2O3 and CaCO3 buffer ranges. For each location uncertainty distributions may be combined by using the same weights.

We illustrated application of the new approach to a medium and strong bimodal distributed response (1) pH in 0–5 cm and (2) pH in 60–100 cm of forest soils in Switzerland (2 530 calibration sites). While model performance measured at 354 validation sites slightly dropped compared to a common modelling approach (drop of R2 of 0.02–0.03) distributional properties of the predictions are much more meaningful from a pedogenic point of view. We were able to demonstrate the benefits of considering specific distributional properties of responses within the prediction process and expanded model assessment by comparing observed and predicted distributions.

How to cite: Nussbaum, M., Zimmermann, S., Walthert, L., and Baltensweiler, A.: Hierarchical modelling in digital soil mapping: Advantages for mapping bimodal soil pH, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6172, https://doi.org/10.5194/egusphere-egu24-6172, 2024.

EGU24-7730 | ECS | Posters on site | SSS10.6

Prediction of soil bulk density in agricultural soils using mid-infrared spectroscopy 

Longnan Shi, Sharon O'Rourke, Felipe Bachion de Santana, and Karen Daly

Soil bulk density (BD) is a key physical parameter in soil quality control and in the calculation from soil organic carbon (SOC) mass (g/kg) content to area stock (kg/ha). However, BD laboratory analysis is time-consuming, labour intensive and expensive, especially for a national-scale soil assessment. Hence, how to fill the omissions of BD values for all or some records in soil databases is widely discussed. This study employed different chemometric and machine learning algorithms to estimate BD in Irish soil from 671 horizon-based samples from MIR spectral libraries by partial least square regression (PLSR), random forest, Cubist and support vector machine (SVM). The best performance was observed for the SVM model with a higher ratio of performance to interquartile distance (RPIQ = 3.61) and R2 (0.81) values and lower root mean square error of prediction (RMSEP = 0.132). Moreover, BD highly correlated wavenumber bands were determined by principal components analysis (PCA) and variable importance analysis. Soil organic matter (SOM) was identified as the primary factor in the spectral soil BD model. The generalisation error of predicting unknown samples using a spectral soil bulk density (BD) model was calculated by employing leave-one-out cross-validation (LOO-CV) on SVM. Estimation of BD by the spectral BD model was compared with published traditional pedo-transfer functions (PTFs), results were then compared for the overall models, different horizon types and specific depth categories. The spectral soil BD model is significantly better than traditional PTFs overall, with RMSEP equalling 0.132 g/cm3 and 0.196 g/cm3 respectively. The spectral soil BD model showed a similar accuracy on the A horizon, but considerable performance improvements were found on the other types of horizon. As for different depth categories, there is no significant accuracy difference between shallow (A-Samples: 5-20 cm) and deep (S-Samples: 35-50 cm) topsoil for the spectral soil BD model, which differs from traditional PTFs. The findings suggest that spectral modelling techniques, such as SVM, can provide high accuracy and homogenous performance across different depth layers, making them suitable for national soil surveys and large-scale carbon stock assessments. The best SVM model was then used to estimate BD values for a large archive of samples from the northern half of Ireland (Terra Soil project) and soil BD maps were generated at two different fixed-depth layers respectively. Besides that, all predicted soil BD values will be used for calculating soil carbon stock and assessing carbon deficit and sequestration potential in subsequent stages of the research.

Keywords: Soil; Bulk density; Mid-infrared; Spectroscopy; Chemometrics; Machine learning

 

How to cite: Shi, L., O'Rourke, S., de Santana, F. B., and Daly, K.: Prediction of soil bulk density in agricultural soils using mid-infrared spectroscopy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7730, https://doi.org/10.5194/egusphere-egu24-7730, 2024.

EGU24-9731 | ECS | Orals | SSS10.6

Soil Organic Carbon Retrieval from DESIS Images by CNN 

Xiangyu Zhao, Uta Heiden, Paul Karlshöfer, Zhitong Xiong, and Xiao Xiang Zhu

Imaging spectroscopy is commonly used for many applications like soil, water, and vegetation. Digital soil mapping, especially by space-borne sensors, has become advantageous and promising due to its high efficiency. By using multispectral or hyperspectral images, topsoil properties could be estimated efficiently and accurately on a large area scale. Moreover, deep learning has been explored in the remote sensing community and achieved excellent performances in many remote sensing tasks. In this work, we explore deep learning methods to retrieve Soil Organic Carbon (SOC) value from DESIS hyperspectral images for the whole Bavaria state in Germany. For the hyperspectral data, we use all available DESIS images in Bavaria, which is 560 in total. Regarding the soil data, we combine SOC data from LFU (Bavarian State Environment Agency) and LUCAS 2018 (Land Use and Coverage Area frame Survey). Following a rigorous data selection process, we opted to include 1200 soil samples in our experiments. Starting from the raw hyperspectral images, we conduct a few preprocessing steps such as land cover masking, filtering by NDVI, building temporal composite, and then extracting patches surrounding each soil sample. These preprocessed patches are fed into deep learning models such as 1D CNN and 2D CNN, which are trained to predict the SOC value. To better interpret the model's performance, we also compute the SHAP(Shapley Additive Explanations) value for both frameworks. Specifically, we explore the SHAP value in spectral dimension for 1D CNN and analyze digital elevation features with 2D CNN in spatial dimension. During experiments, we split the whole dataset into train, validation, and test. To evaluate the performance, RMSE, R2, and RPID are computed. For the specific structure of the models, many different parameters are investigated in parameter tuning. For each trial, 5 cross-validation is applied. In the end, we visualize the prediction results by a soil map.  From the results, the best-performed model could get RMSE 0.62 and R2 0.40 on the test set. Moreover, we find that the first-order derivative of the spectrum is the most important feature for predicting SOC, while 1D CNN is capable of extracting useful information from it and achieving excellent regression results with RMSE 0.66 and R2 0.32. Additionally, spectrums between 530 nm - 570 nm and 730 nm - 780 nm are the most informative according to SHAP analysis.

How to cite: Zhao, X., Heiden, U., Karlshöfer, P., Xiong, Z., and Zhu, X. X.: Soil Organic Carbon Retrieval from DESIS Images by CNN, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9731, https://doi.org/10.5194/egusphere-egu24-9731, 2024.

EGU24-9981 | Posters on site | SSS10.6

Validation on the content of clay and organic matter of a digital soil map across Denmark - A median-soil texture perspective 

Alireza Motevalli, Christen Duus Børgesen, Bo Vangsø Iversen, and Charles Pesch

Detailed soil maps are an essential tool for water resource, land management and agricultural planning. However, due to different soil processes and variation in geology, soil textural properties vary in space at different scales challenging the development of accurate soil maps. Despite the advances in sampling and efforts to produce accurate maps, uncertainties remain at many scales. Therefore, by implementing error evaluation methods such as comparing predictions and observations, it is possible to understand the performance of digital soil maps. The aim of this work was to obtain the uncertainties of soil categories from a Danish national soil map (AC map) based on measured contents of soil texture and soil organic matter. The AC maps describes the horizon characteristics (soil texture, soil organic matter, soil horizon depths and bulk density) at three depths corresponding to the A (0-30 cm), B (30-70 cm), and C (70-120 cm) horizon. In addition, it combines information on soil classification (soil texture), geology at a depth of ca. 1.5 meters as well as the national geological region. The map has a spatial resolution of 250 meters in the A and B horizons and 500 meters in the C horizon. The analysis is based on 38,000 textural points for the A horizon, 7,000 points for the B horizon, and almost 1,700 points for the C horizon. Considering mean and medians of the content of clay and organic matter together with the observed data, the AC map was validated. The uncertainties of the AC map, statistical correlation coefficient (R2), root mean square error (RMSE), and the Nash-Sutcliffe efficiency (NSE) were used. The results showed that the AC map has an acceptable performance when predicting the clay content in the A horizon (R2 = 0.97, RMSE = 1.15%, and NSE = 0.91), B horizon (R2 = 0.95, RMSE = 1.85%, and NSE= 0.8), and C horizon (R2 = 0.74, RMSE = 5.32%, and NSE = 0.41, respectively. The performance of the prediction of organic matter content in the A horizon (R2 = 0.84, RMSE = 0.39%, and NSE = 0.65) and B horizon (R2 = 0.66, RMSE = 0.44%, and NSE = 0.32) horizons was acceptable as well. Also, the result of validation showed that the highest residual errors of AC maps for clay content and organic matter content has been related loamy (>15% clay) and peat soils. In conclusion, the AC maps, with its optimal accuracy especially in the A and B horizons, can be a suitable tool for use at variable scales in the analysis of crop growth and nitrate leaching modelling studies.

Keywords: Soil texture, digital soil maps, soil variability, soil organic matter, clay, soil properties

How to cite: Motevalli, A., Børgesen, C. D., Vangsø Iversen, B., and Pesch, C.: Validation on the content of clay and organic matter of a digital soil map across Denmark - A median-soil texture perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9981, https://doi.org/10.5194/egusphere-egu24-9981, 2024.

EGU24-10446 | Posters on site | SSS10.6

Analysis of Soil Hydraulic Parameters effects on soil water modelling based on Danish soil water monitoring systems.  

Maryam Dastranj, Christen Duus Børgesen, and Bo Vangsø Iversen

Accurate soil hydraulic parameters are crucial in effectively modeling agricultural field processes where soil water plays a crucial role (e.g. nitrate leaching processes, crop growth, etc.). Three horizons soil maps, called AC maps, have been developed for Denmark including related standard soil profile descriptions including three soil horizons (A, B and C) with data on soil texture, organic matter and soil hydraulic parameters (SHPs) which have been determined using a Danish developed pedotransfer function (PTF) predicting the vanGenuchten Mualem SHP called P10 . However, the standard soils have not been validated on simulating temporal change in soil water content (SWC). This study aims to evaluate the accuracy of the SHP set up obtained from the P10 and HYPRES (European developed PTF model predicting the predicting vanGenuchten Mualem SHP) as inputs for the Daisy model simulations (Danish soil-water-plant-atmosphere system model based on solving Richards equation in 1-D), by comparing simulations with measured SWC. Soil water content was measured at four different soil depth (25, 60, 90, and 110 cm, respectively) using TDR equipment for three different soil texture classes at three different experimental fields in Denmark for a period of 20 years. Statistical parameters including root mean square error (RMSE) and normalized root mean square error and Nash-Sutcliffe efficiency coefficient (NSE) were used to analysis the precision of the soil water content simulations. The results of the study indicate that the differences between simulated soil water content using the P10 PTF and measured values were not statistically significant. However, it was significant using HYPRES PTFs in Jyndevad (sandy soil). The NRMSE, RMSE (%), and NSE values varied between 0.14-0.38, 4.56-10.8 (%), and 0.78-0.98, respectively. In comparison, simulations using the HYPRES model had NRMSE, RMSE, and NSE values of 0.16-0.69, 4.16-7.39 (%), and 0.09-0.98, respectively. Our results suggest that P10 PTFs provided more accurate simulations of soil water content in Denmark compared to HYPRES. High values of NRMSE are related to the simulations in 60 cm depth for the site where the soil had the highest percentage of clay (ranging from 30-43%). However, high values of NSE indicate that the model successfully simulates the pattern of soil water variation during different days using AC map data. It is important to mention that soils with clay content exceeding 20% are rarely found in Denmark. In conclusion, the SHPs obtained from AC maps (P10 PTFs model) appear to be reliable and suitable for soil water simulations. 

Key words: Soil maps, clay content, soil water content, Daisy model, Hydraulic parameters, Pedotransfer functions. 

How to cite: Dastranj, M., Børgesen, C. D., and Vangsø Iversen, B.: Analysis of Soil Hydraulic Parameters effects on soil water modelling based on Danish soil water monitoring systems. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10446, https://doi.org/10.5194/egusphere-egu24-10446, 2024.

EGU24-11463 | ECS | Orals | SSS10.6

How can we quantify, explain, and apply the uncertainty of complex soil maps predicted with neural networks? 

Kerstin Rau, Katharina Eggensperger, Frank Schneider, Philipp Hennig, and Thomas Scholten

Artificial neural networks (ANNs) have proven to be a useful tool for complex questions that involve large amounts of data, for example, predicting soil classes on various scales. Our use case of predicting soil maps with ANNs is in high demand by government agencies, construction companies, or farmers, given cost and time intensive field work.
However, there are two main challenges when applying ANNs. In their most common form, deep learning algorithms do not provide interpretable predictive uncertainty. This means that properties of an ANN such as the certainty and plausibility of the predicted variables, rely on the interpretation by experts rather than being quantified by evaluation metrics validating the ANNs. This leads to the second challenge: these algorithms have shown a high confidence in their predictions in areas geographically distant from the training area or areas only sparsely covered by training data.

To tackle these challenges, we use the Bayesian deep learning approach “last-layer Laplace approximation”, which is specifically designed to quantify uncertainty into deep networks, in our explorative study on soil classification. It corrects the overconfident areas without reducing the accuracy of the predictions, giving us a more realistic uncertainty expression of the model's prediction.  In our study area in southern Germany we divide the soils into typical soils of valleys, the Swabian Jura and the Black Forest. As a test case, we then explicitly exclude the soil types of Swabian Jura and Black Forest in the training area but include these regions in the prediction. These two regions are characterized by very different soil types compared to the rest of the study area due to their considerably different geology, climate, and terrain.

Our findings emphasize the need to address the issue of overconfidence in ANNs, particularly for distant regions from the training area. Moreover, the insights gained from this research are not only limited to addressing overconfidence in ANNs, but also offer valuable information on the predictability of soil types and identifying knowledge gaps. By analysing regions where the model has limited data support and, consequently, high uncertainty, stakeholders can recognize the areas that require more data collection efforts.

How to cite: Rau, K., Eggensperger, K., Schneider, F., Hennig, P., and Scholten, T.: How can we quantify, explain, and apply the uncertainty of complex soil maps predicted with neural networks?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11463, https://doi.org/10.5194/egusphere-egu24-11463, 2024.

EGU24-11583 | ECS | Posters on site | SSS10.6

Contribution of Sentinel-2 Seedbed Spectra to the Digital Mapping of Soil Organic Carbon 

Fien Vanongeval, Jos Van Orshoven, and Anne Gobin

Soil organic carbon (SOC) plays a pivotal role in the functioning of terrestrial ecosystems, has the potential to mitigate climate change and provides several benefits for soil health. Understanding the spatial distribution of SOC can possibly help formulate sustainable soil management practices. Conventional soil surveys are often limited by their spatio-temporal resolution and high cost, necessitating the development of innovative techniques that can capture the intricate variability of SOC across landscapes. In response to this need, digital soil mapping (DSM) has emerged as a powerful approach that uses advanced geospatial technologies and statistical methods to predict soil properties across large areas. Predictor variables for DSM include climate data, topographical features, geological attributes, legacy soil maps, land management practices, spatial information and remote sensing data. The spectral response of bare soil, measured by multispectral satellite sensors, can be an adequate predictor of SOC and texture at the field scale and in small regions, but its use for the assessment of soil properties at large scale (thousands of km²) has been less explored 1. In this study, bare soil spectra derived from Sentinel-2 were used to estimate SOC and texture across agricultural parcels in Flanders, northern Belgium (n=169-175). Five different machine learning models were tested: generalized linear regression (GLM), partial least squares regression (PLSR), random forest (RF), cubist regression (CR) and gradient boosting machine (GBM). The SOC prediction of a DSM model using bare soil spectra was compared with that of a DSM model using environmental covariates: topography (elevation, slope and compound topographic index), climate (average annual temperature, total annual precipitation, average annual evapotranspiration), texture (sand, silt and clay content), vegetation (proportion of the year the soil is covered by vegetation) and location. The predictive performances of these models were compared to a DSM model that included both the bare soil spectra and the environmental covariates. Soil texture (sand, silt, clay) was adequately predicted using the bare soil spectra from the spring seedbed (R²: 0.53-0.71; RPD: 1.54-2.18; RPIQ: 1.36-2.41), but the predictive performance for SOC was poor (R²: 0.19; RPD: 1.07; RPIQ: 1.45). All three DSM models showed poor predictive performance for SOC, with the best performance for the model including all covariates (R²: 0.26; RPD: 1.25; RPIQ: 1.68). For the DSM model from bare soil spectra (PLSR), all Sentinel-2 spectral bands showed high relative importance except bands 2 (blue) and 3 (green). For the DSM model from environmental covariates (GBM), vegetation cover and topography explained most of the variation in SOC. The DSM model including all variables (GBM) showed a low influence of bare soil spectral bands, but a high influence of previous vegetation cover and topography. These results showed the importance of terrain characteristics and vegetation for assessing large scale SOC distribution. The overall low predictive performance for SOC obtained in this study indicates the complex nature of factors influencing SOC distribution across a large region and highlights the need for more in-depth high resolution studies.

1 https://doi.org/10.3390/rs14122917

How to cite: Vanongeval, F., Van Orshoven, J., and Gobin, A.: Contribution of Sentinel-2 Seedbed Spectra to the Digital Mapping of Soil Organic Carbon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11583, https://doi.org/10.5194/egusphere-egu24-11583, 2024.

EGU24-11606 | Posters on site | SSS10.6

Elaboration of 3D Soil Hydraulic Databases in Hungary 

László Pásztor, Brigitta Szabó, András Makó, Mihály Kocsis, János Mészáros, Annamária Laborczi, Katalin Takács, and Gábor Szatmári

Spatially detailed quantitative data regarding soil hydraulic properties is in high demand for a range of modeling applications. EU-SoilHydroGrids has demonstrated its utility at the European level, contributing to ecological forecasts, geological and hydrological hazard evaluations, and agri-environmental modeling, among other studies. Building on this continental precedent, comparable but larger-scale, 3D soil hydraulic databases have been targeted within the frame of National Laboratory for Water Science and Water Safety to be utilized at national and regional/watershed level in Hungary. First, HU-SoilHydroGrids, has been developed for the whole area of the country at 100 m spatial resolution with several enhancements (compared to EU-SoilHydroGrids) in its elaboration process.

  • Pedotransfer functions (PTFs) were developed using advanced machine learning techniques, both independently and as part of ensemble models.
  • These models were trained using the national soil hydrophysical dataset called MARTHA (acronym for Hungarian Detailed Soil Hydrophysical Database), ensuring the derivation of region-specific PTFs.
  • The set of predictors utilized in the PTFs was augmented by additional environmental variables with comprehensive spatial coverage, including DEM-derived geomorphometric indices, climatic parameters, OE provided surface reflectance and derived data products, LULC.
  • To spatially apply the resulting models, 100 m resolution information on primary soil properties was obtained from DOSoReMI.hu (Digital Optimized Soil Related Maps and Spatial Information in Hungary).
  • Finally, based on a detailed accuracy assessment, the spatial predictions (map products) were complemented with co-layers representing the 5% and 95% quantiles.

HU-SoilHydroGrids provides nationwide information on the most frequently required soil hydraulic properties (water content at saturation, field capacity and wilting point, saturated hydraulic conductivity and van Genuchten parameters for the description of the moisture retention curve) at a spatial resolution of 100 meters, down to 2 meters soil depth for six GSM standard layers. In comparison to EU-SoilHydroGrids, the description of soil moisture retention curves and hydraulic conductivity has significantly reduced squared error in the case of HU-SoilHydroGrids.

A further step toward larger spatial resolution is based on NATASA (Hungarian acronym for Profile-level Database of Hungarian Large-Scale Soil Mapping) initiative for the conservation and digital processing of the still available soil observation legacy data originating from large-scale surveys carried out in Hungary between the 60s and 90s. Digitization of the soil observation records is in progress, firstly concentrating on the watershed of the Lake Balaton. The partly processed area contains already almost 37.000 soil observations in the three counties neighbouring the lake, which will be used in digital mapping of primary soil properties at a scale of 25 meters. These DSM products then will be similarly adapted as the 100 m resolution DOSoReMI.hu products for the derivation of soil hydraulic property predictions down to 2 meters for six standard GSM soil depth layers, thus providing watershed-level, large-scale 3D Soil Hydraulic Databases (LS-HU-SoilHydroGrids).

 

Acknowledgement: This work has been carried out within the framework of the Széchenyi Plan Plus program with the support of the RRF 2.3.1 21 2022 00008 project and the Sustainable Development and Technologies National Programme of the Hungarian Academy of Sciences (FFT NP FTA).

How to cite: Pásztor, L., Szabó, B., Makó, A., Kocsis, M., Mészáros, J., Laborczi, A., Takács, K., and Szatmári, G.: Elaboration of 3D Soil Hydraulic Databases in Hungary, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11606, https://doi.org/10.5194/egusphere-egu24-11606, 2024.

EGU24-11994 | Orals | SSS10.6

 A Deep Learning Approach for Improving Soil Property Prediction with Unannotated Hyperspectral DESIS Imagery 

Thomas Bishop, Kun Hu, Patrick Filippi, and Zhiyong Wang

An increasing number of hyperspectral satellite platforms are becoming available as exemplified by the DESIS platform.  This generates an immense amount of spectral information about the earths surface which is unlabelled.  In this work we use DESIS imagery to compare two deep learning approaches for utilising all of this unlabelled data for predicting topsoil properties. The first is transfer learning from laboratory based spectral libraries.  The second is a novel self-supervise learning approach which employs a transfer-based autoencoder architecture for unsupervised learning, analyzing spectra patterns and cultivating powerful latent representations for the downstream task of soil property analysis. Using a dataset from eastern Australia we show that the self-supervised learning approach gives superior predictions than transfer learning.

How to cite: Bishop, T., Hu, K., Filippi, P., and Wang, Z.:  A Deep Learning Approach for Improving Soil Property Prediction with Unannotated Hyperspectral DESIS Imagery, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11994, https://doi.org/10.5194/egusphere-egu24-11994, 2024.

EGU24-12959 | Orals | SSS10.6

Integrated Digital Soil Assessment across South East Asia and Africa. 

Ronald Corstanje, Bader Oulaid, Joanna Zawadzka, Ben Ingram, Alice Milne, Guy Kirk, and Jack Hannam

Digital Soil Assessment (DSA) methods are increasingly being applied as integrative step in which DSM outputs are incorporated into crop and land management decision support systems, often through the vehicle of process models. The value of the acquisition, interpretation of any soil data, and the additional effort in developing and producing a DSM product resides in its use and utility. The purpose of DSA is the development of the value argument for the conversion of quantitative data on soil properties obtained through DSM to a spatial assessment of the capacity of a soil to fulfil a particular function. Here we present the use of DSM/DSA to i) demonstrate the discovery new soil process knowledge on rice production in Bangladesh and the conditions which can determine heavy metal accumulation; ii) determine and illustrate DSA under data sparce conditions through mapping areas in West Africa under which Fe toxicity in the soil limits agricultural production and iii) integration of DSA in a wider decision support system to support decision making in a semi-arid region in Morocco, illustrating the trade-offs between agricultural production and ecosystem services. Through these case examples, we demonstrate the flexibility of DSA approaches in addressing both the generation of new knowledge around soil processes, in justifying the acquisition of new soil data and in helping landowners to manage their crops and soils sustainably.

How to cite: Corstanje, R., Oulaid, B., Zawadzka, J., Ingram, B., Milne, A., Kirk, G., and Hannam, J.: Integrated Digital Soil Assessment across South East Asia and Africa., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12959, https://doi.org/10.5194/egusphere-egu24-12959, 2024.

EGU24-13365 | ECS | Orals | SSS10.6

Predicting the spatial distribution of SOC using remotely sensed data and vegetation data in southern Queensland’s grasslands  

Sahar Ahmadi, Mark Bonner, Elaine Mitchelle, Peter Grace, and David Rowlings

Soil organic carbon (SOC) plays an important role in sequestering CO2 and assists in reducing atmospheric greenhouse gases in addition plays a critical role in maintaining the sustainability of grasslands. The valuable roles of SOC, make its accurate measurement critical however temporal changes in SOC are small and spatially vary.  Therefore, a large number of samples are required to detect the SOC changes which makes it a complex and costly task. Stratification is capable of improving the efficiency of sampling by reducing the number of samples and increasing the accuracy of SOC measurement. Stratification relies on assessing the relationship between SOC and environmental factors. Vegetation has the potential to be used as a proxy to spatially predict SOC.

This experiment aimed to assess the relationship between SOC and vegetation characteristics as a key factor in small areas with uniform climate and soil type. The three study sites were located in southern Queensland with subtropical climate. Short-term data was collected using the BOTANAL method and biomass harvesting over two years period in different seasons which included biomass, pasture composition, and vegetation type. Long-term data was extracted from various satellite images for up to 30 years which indicate the long-term effect of vegetation on SOC. Remote sensing data contained vegetation and soil indices.

The kriging method was applied to both soil and vegetation data to interpolate unsampled points for the study areas, then K-means clustering was used to cluster the data. Spearman rank-order correlation coefficient was used to assess the correlation between SOC clusters and vegetation factor clusters.

While some of the vegetation parameters have a significant correlation with SOC, the correlation is not consistent between different sites and different seasons. It can be concluded from this study that vegetation factors are not capable of using landscape clustering for SOC sampling on small scale.

How to cite: Ahmadi, S., Bonner, M., Mitchelle, E., Grace, P., and Rowlings, D.: Predicting the spatial distribution of SOC using remotely sensed data and vegetation data in southern Queensland’s grasslands , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13365, https://doi.org/10.5194/egusphere-egu24-13365, 2024.

EGU24-14085 | Posters on site | SSS10.6

Cross- regional Crop Identification Using the Hypothesis Testing Distribution Method 

Wenzhi Zeng, Jie He, Zhipeng Ren, Chang Ao, and Tao Ma

To improve the accuracy of crop classification across temporal and spatial domains. Sentinel-2 satellite images are employed for crop classification training and prediction in select farming areas of Heilongjiang Province by calculating vegetation indices and constructing sequential input feature datasets. The Hunts filtering method was used to mitigate the influence of cloud cover, which increased the stability and completeness of the input feature data across different years. To address the issue of shifts in the input feature values during cross-scale classification, this study proposes the Hypothesis Testing Distribution Method (HTDM). This method balances the distribution of input feature values in the test set even without known crop distribution, thereby enhancing the accuracy of the classification test set. This study utilizes 2019 data on crop planting types from Yushan and Longzhen farms in Heilongjiang Province for model training and data from 10 farms in the province from 2019 to 2022 for model testing. Results indicate that HTDM significantly improves prediction accuracy in cases of substantial image quality variance. After applying HTDM, the recognition accuracy of crop types for the Bawuba Farm in the years 2020 and 2021 reached 95.5% and 96.0%, an increase of 18.2% and 25% compared to before processing, respectively. In 2022, the recognition accuracy for crop types at all farms processed by HTDM was above 87%, showcasing the strong robustness of the HTDM. An analysis of input features using SHAP values revealed that the most impactful features for rice, corn, soybean, and wheat were LSWI in May (LSWI5), LSWI in May (LSWI5), RNDVI in August (RNDVI8), and IRECI in August (IRECI8) respectively.

How to cite: Zeng, W., He, J., Ren, Z., Ao, C., and Ma, T.: Cross- regional Crop Identification Using the Hypothesis Testing Distribution Method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14085, https://doi.org/10.5194/egusphere-egu24-14085, 2024.

EGU24-14259 | Posters on site | SSS10.6

Farming digital data: Even when the cows come home 

John Triantafilis, Feiko Van Zadelhoff, James Ardo, Peter Edwards, Kishor Kumar, Ekanayake Jagath, and Sam McNally

Increasingly, multinational brands, manufacturers, and retail customers want to demonstrate where individual components of their supply chain have come from, and they have been made sustainably using a triple-bottom-line approach (i.e., social well-being, environmental health, and a just economy). One example is the need for farmers to demonstrate they are transforming their operations into climate-smart landscapes, decarbonising their operations (i.e., minimising inputs) and supply chains to contribute to global net zero, while at the same time being financially sustainable. Others include reduction in inputs including but not limited to precision application of fertilisers (e.g., nitrogen and phosphorus), ameliorants to overcome soil acidity (e.g., lime) and water for irrigation. In the first instance, this requires information on various soil ‘conditions’ including the ‘capacity’ of soil to be improved in terms of its soil ‘capability’. In this presentation we demonstrate how we develop digital soil maps (DSM) of soil ‘capacity’ including but not limited to i) physical (mineral surface area [MSA]), ii) biological (carbon [C] and nitrogen [N]), iii) chemical (cation exchange capacity [CEC], and P-sorption [P]), and iv) hydrological (permanent wilting point [PWP], field capacity [FC], plant available water [PAW]), on the Lincoln University Dairy Farm. In this regard, the DSM are developed using digital data collected using either remote (i.e., LiDAR) or proximal sensed (i.e., gamma-ray spectrometry and electromagnetic (EM) induction) data. In this presentation, we show how the individual DSM are stored online (ArcGIS web app) and the rationale for ‘Farming digital data’ described (ArcGIS Story Map). The final DSMs are described in terms of how knowledge of the heterogeneity of different soil ‘capacity’ enables a farmer to understand how the ‘capability’ of soil can be improved, respectively, and in terms of; i) where best to invest in soil organic carbon sequestration initiatives (MSA), ii) how to monitor carbon dioxide/nitrous oxide emissions and microbial population (C:N ratio), iii) more precisely apply fertilisers (e.g., N and P) and ameliorants (e.g., lime and gypsum), and iv) improve water use efficiency with variable rate irrigation (PAW). Brief insights into how these DSMs underpin the development of a Digital Agriculture framework are also presented ‘Even when the cows come home’.

How to cite: Triantafilis, J., Van Zadelhoff, F., Ardo, J., Edwards, P., Kumar, K., Jagath, E., and McNally, S.: Farming digital data: Even when the cows come home, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14259, https://doi.org/10.5194/egusphere-egu24-14259, 2024.

EGU24-15629 | Orals | SSS10.6

Soil moisture effects: integrating physically based models and machine learning for enhanced retrieval and dryification strategies 

Alessia Tricomi, Roberta Bruno, Raffaele Casa, Saham Mirzaei, Simone Pascucci, Stefano Pignatti, Francesco Rossi, and Rocchina Guarini

Soil moisture, despite its crucial role in various agricultural processes, acts as noise in retrieving properties such as texture and soil organic carbon through spaceborne hyperspectral data. High spatiotemporal variability in moisture reduces the capability of soil monitoring. Soil moisture determines a reduction of the reflectance over the entire spectrum, which is not linear and its magnitude varies depending on the spectral region and the soil type. Within the framework of TEHRA project (an Italian Space Agency research initiative), a study was carried out to explore the combined use of MARMIT-2, a multilayer radiative transfer model of soil reflectance to estimate soil water content, and Machine Learning methods to address this challenge. Two local soil spectral libraries (SSLs), including both dry/wet samples and SMC (soil moisture content) values, collected over different locations in Italy between 2021 and 2022 (Maccarese-Pignola-Castelluccio and Jolanda di Savoia, respectively), have been used to investigate two different approaches.

The first one is devoted to the retrieval of soil moisture content. By performing the inversion and the calibration of MARMIT-2 it is possible to increase the dataset by adding further wet spectra (and SMC values) for each sample of the original spectral library. The wet soil reflectance is expressed in terms of dry soil reflectance and three free parameters: the thickness of the water layer L, the surface fraction of the wet soil ε, and the volume fraction of soil particles in the water layer δ. Given a dry sample and the corresponding wet measurement, the Nelder-Mead algorithm is used to minimize a cost function.  The calibration, instead, is performed by fitting a sigmoid function following the soil-by-soil approach. The dataset is generated by varying (L, ε, δ) to simulate wet reflectances and the corresponding SMC is calculated using the sigmoid and the parameters found during the calibration. A Machine Learning Regression Model (a Multilayer Perceptron) has been trained using Maccarese-Pignola-Castelluccio plus additional libraries made available by authors of MARMIT and tested using Jolanda di Savoia. Results are very promising: MAE: 5.088; R2 score: 0.844; RMSE: 6.165. The model has been applied also to different PRISMA images proving to be coherent with respect to the values measured in laboratory included in the SSL.

The second approach is to train a deep convolutional autoencoder capable of extracting the corresponding dry spectrum from a wet one. The dataset is composed by couples of wet and dry reflectances, resampled to PRISMA bands configuration and cleansed of water vapor absorption bands. The autoencoder consists of several blocks of convolutional layers, batch-normalization, and ReLU-activation functions. The downsampling is performed by average pooling and the upsampling with inverse convolutions. The model has been trained on Maccarese-Pignola-Castelluccio SSL, with additional samples added thanks to the inversion of MARMIT-2. Jolanda SSL has been kept aside to be used for testing the model (MAE: 0.04469, MSE: 0.00317, CS: 0.98). The autoencoder has been applied also to PRISMA images; however, further developments need to be carried out given the remarkable difference between simulated and real spaceborne data.

How to cite: Tricomi, A., Bruno, R., Casa, R., Mirzaei, S., Pascucci, S., Pignatti, S., Rossi, F., and Guarini, R.: Soil moisture effects: integrating physically based models and machine learning for enhanced retrieval and dryification strategies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15629, https://doi.org/10.5194/egusphere-egu24-15629, 2024.

EGU24-15806 | ECS | Posters on site | SSS10.6

An Improved Model for Estimating the DielectricConstant of Saline Soil in C-Band 

Leilei Dong and Weizhen Wang

Soil salinization is one of the major forms of land degradation processes from all over the world. The dielectric constant plays an important role in the process of soil salinity retrieval by using microwave remote sensing. The Dobson model has been widely used to simulate the dielectric constant of nonsaline soil, but the estimated result of the Dobson model did not perform well for saline soil. Moreover, the ions’ concentration is related to soil salinity, and the electrical conductance is a critical factor that influences the imaginary part of the dielectric constant. Therefore, the relationship between them needs to further explore. In addition, saturation is neglected in the current dielectric model of saline soil. In this letter, the relationship between the electrical conductance and ions’ concentration was analyzed based on the experimental data. The saturation as a new parameter was introduced into the Dobson model to improve the estimated accuracy of the dielectric constant of saline soil in the C-band. The comparison between the revised model, the Dobson model, the Hu Qingrong (HQR) model, and the Wu Yueru (WYR) model was presented. The results indicate that there is a significant linear relationship between the electrical conductance and ions’ concentration, with R2 of 0.996, a slope of 0.1456, and an intercept of 0.0252. Once the new parameter is implemented, the improved dielectric model based on the C-band reproduces the dielectric constant of saline soil satisfactorily in each soil sample. The simulated results of the improved model are consistent with the laboratory measurement results, with an RMSE of 0.97 and R2 of 0.953. Compared with other commonly used three dielectric models of the saline soil, the improved dielectric model performs well in simulating the imaginary part of the dielectric constant. The improved agreements between the simulations and the measurements indicate that the revised dielectric model is appropriate for simulating the dielectric constant of saline soil. The revised dielectric model of saline soil will provide a scientific foundation for the soil salinity retrieval from the microwave remote sensing technology.

How to cite: Dong, L. and Wang, W.: An Improved Model for Estimating the DielectricConstant of Saline Soil in C-Band, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15806, https://doi.org/10.5194/egusphere-egu24-15806, 2024.

EGU24-16301 | ECS | Posters on site | SSS10.6

Using machine learning to model Soil Aggregate Stability as an indicator for soil erosion susceptibility at the catchment scale 

Deborah Feldmann, Michael Kuhwald, Philipp Saggau, and Rainer Duttmann

Soil aggregate stability (AS) is a key component for numerous soil processes and a significant factor in soil erosion. Despite its significance, the research on AS has been comparatively limited, possibly due to the high monetary, work and time expense needed to gain data. Furthermore, the spatial distribution of aggregate stability is influenced by various topographic and physical factors, such as surface curvature and soil characteristics. It is also affected by non-numerical conditions, for instance land use and crop type. This combination of quantitative and qualitative variables highlights the complexity of AS modeling. Therefore, it is even more important to gain further insight on the spatial distribution and prediction techniques suitable for AS.

The aim of the ESTABLE project is to model the spatial variability and distribution of AS and analyze its relationship to soil erosion processes at the catchment scale. To accomplish this, a total of 500 topsoil samples were collected from the two study sites in Northern Germany (Lamspringe and Ascheberg). All soil samples were analyzed for aggregate stability, soil texture, organic carbon content, pH, and electric conductivity.

To represent the complexity of the relationship of factors influencing AS, various machine learning models, including Boosted Tree and Random Forest, are tested to implement categorical data in addition to the wide range of numerical input variables. These models were evaluated based on their performance, parameterization, and interpretability in comparison to traditional interpolation techniques like multiple linear regression and regression kriging. It has become evident that most machine learning techniques are more effective at capturing the intricate interactions that influence aggregate stability.

The best performing model is then used to verify, that low aggregate stability areas are also prone to erosion. The use of UAVs and field mapping enable a detailed and accurate assessment of the spatial distribution of soil erosion. This model could also serve as a valuable tool for other sites and subsequent studies.

How to cite: Feldmann, D., Kuhwald, M., Saggau, P., and Duttmann, R.: Using machine learning to model Soil Aggregate Stability as an indicator for soil erosion susceptibility at the catchment scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16301, https://doi.org/10.5194/egusphere-egu24-16301, 2024.

EGU24-16425 | ECS | Posters on site | SSS10.6

Assessing the Effect of DEM’s resolution on Model Transferability of soil types: A case study of Lombardy region, Italy 

Odunayo David Adeniyi, Alice Bernini, and Michael Mearker

Mapping soil classes to retrieve information for specific soil management strategies according to capabilities and limitations of soil types is an important and very useful application of Digital Soil Mapping (DSM). DSM harnesses auxiliary data, including Digital Elevation Models (DEMs) and remote sensing information, to establish crucial relationship between soil characteristics and landscape attributes, facilitating the creation of soil maps. DEMs, offering detailed morphometric information about the Earth's surface, provide quantitative measurements of terrain features for GIS-based soil-mapping applications. Derived from DEMs, terrain attributes, including elevation, slope, aspect, and curvature profiles, along with secondary attributes like solar radiation and moisture index, play a pivotal role in characterizing spatial-specific landscape processes essential to soil formation. These morphometric attributes, integral to DSM due to their role in the paedogenetic process, have become indispensable auxiliary variables. The success of DSM depends heavily on the quality of input environmental covariates, with spatial resolution serving as a critical indicator. The spatial resolution of environmental covariates in DSM, often determined by the DEM's subjective spatial distribution, influences the modelling outcomes and processing efficiency. This study investigates the impact of DEM resolution on soil type classification and model transferability, focusing on the Lombardy region, Italy. Utilizing three different DEMs sources with resolutions of 5 m, 10 m, and 25 m, the research employs the Random Forest algorithm, and nested Leave-One-Out Cross-Validation (nested-LOOCV) techniques to assess model performance. The findings reveal a pivotal role for spatial resolution in determining model transferability, with distinct challenges observed during upscaling and downscaling. The study emphasizes the need for a nuanced approach to variable selection based on DEM resolution and provides valuable insights for optimizing soil classification models across diverse landscapes. The research contributes to advancing Digital Soil Mapping methodologies and underscores the significance of careful consideration of spatial resolution in enhancing the applicability of soil classification models.

How to cite: Adeniyi, O. D., Bernini, A., and Mearker, M.: Assessing the Effect of DEM’s resolution on Model Transferability of soil types: A case study of Lombardy region, Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16425, https://doi.org/10.5194/egusphere-egu24-16425, 2024.

EGU24-17128 | Orals | SSS10.6

Useful digital soil mapping products for farmers  

Liv Kellermann, Simon Tanner, Stefan Oechslin, Madlene Nussbaum, and Stéphane Burgos

In large parts of Switzerland, there are up to the present day no soil maps in a more precise scale than 1:25’000. In 2020 the Swiss government adopted a soil strategy to promote soil mapping and the required tools and guidelines. Furthermore, authorities are legally obligated to delineate areas for the high-quality arable land inventory. In the future, soil maps will be available at high resolution for increasingly large areas. However, farmers are not used to work with this type of soil information as it was so far not available and data products are unknown.

In a pilot study of 1’000 ha in the canton of Bern a large number of soil properties have been mapped at high resolution using digital soil mapping techniques based on 1’500 newly surveyed observations. The content of the maps ranges from continuous or classified basic soil properties such as texture or soil organic matter content to aggregated soil properties such as water storage capacity. From these baseline maps certain applications and examples were assessed for specific agricultural use and the corresponding maps were discussed with local farmers. The examples include options for precision farming, proposals for new sampling sites for the legally required soil survey, the generation of more meaningful routine measurements and planning bases for irrigation systems at regional scale. Feedback was diverse and interest in soil maps differs largely according to farm management, specialization and digital affinity. Our study shows the importance of stakeholder involvement and training as well as familiarization of the farmers with digital soil maps.

How to cite: Kellermann, L., Tanner, S., Oechslin, S., Nussbaum, M., and Burgos, S.: Useful digital soil mapping products for farmers , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17128, https://doi.org/10.5194/egusphere-egu24-17128, 2024.

EGU24-17168 | ECS | Posters on site | SSS10.6

Evaluation of EnMAP imagery for predictive modelling of soil salinity in highly saline soils 

Francisco M. Canero, Diego Lopez-Nieta, and Victor Rodriguez-Galiano

Soil salinization is a paramount issue affecting crop yields and soil productivity, specially threatening the soil in arid and semi-arid regions. In Bajo Guadalquivir (southern Spain), one of the main rice production areas of Spain, soil salinity has been reported by local stakeholders as the main ecological stressor affecting rice crops. EnMAP hyperspectral mission might rise promising opportunities to improve the monitoring of soil salinity and other environmental stressors. This mission provides continuous vis-NIR spectral data with a moderate temporal resolution. The aim of this study is to evaluate EnMAP imagery in two different predictive modelling workflows based on Random Forest and Support Vector Machines.

100 samples of electrical conductivity (EC) measures were collected in May-June 2023 in the study area. A EnMAP image was acquired over the study area on 22 March 2023. Vegetated and water surfaces were masked out, resulting in 80 samples of bare soils for the date of Enmap acquisition. Raw bands and soil salinity indices (SSI) were used as predictive features. SSI were based on an iterative procedure calculating normalized indices between all pair of bands, selecting the 1% of indices with higher correlation with EC. Two ML algorithms, Random Forest and Support Vector machine, were used together with a Sequential Feature Selection method built with each modelling algorithm.

The sampling results showed high soil salinity contents, with a median value of 10.96 dSm-1. EnMAP image reached the higher accuracy using RF with R2 = 0.14, RMSE = 3.14, RPIQ = 1.53. SVR performed worse, with a model achieving R2 of -0.37, RMSE of 3.38 and RPIQ = 1.42. Both models selected the same two features, two SSI built with the 756/871 nm and the 972/1234 nm pairs. Given that the features were similar, differences might be derived from modelling algorithms. The results suggested that hyperspectral images are promising data sources, but their processing to get meaningful features is perhaps the most important task to obtain accurate soil salinity products. 

How to cite: Canero, F. M., Lopez-Nieta, D., and Rodriguez-Galiano, V.: Evaluation of EnMAP imagery for predictive modelling of soil salinity in highly saline soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17168, https://doi.org/10.5194/egusphere-egu24-17168, 2024.

EGU24-18218 | ECS | Orals | SSS10.6

Comparison of predicted soil physical property maps based on (i) LUCAS topsoil database and (ii) Hungarian Soil Information and Monitoring System 

András Benő, Gábor Szatmári, Annamária Laborczi, Mihály Kocsis, Zsófia Bakacsi, and László Pásztor

The adaption of our land use and agricultural practices requires more detailed and more reliable spatial soil physical data. The LUCAS topsoil database is an up to date collection of soil physical data, however it is spatially scarce. The soil physical data of the Hungarian Soil Information and Monitoring System (SIMS) is spatially denser and has data from multiple layers from 1992. Harmonizing and combining the two datasets can lead to the creation of better resolution and more accurate maps. Before combining the databases, we must make sure, that the sample points represent the area in the same way. The comparison of the data began with the cleansing of the datasets, followed by the conversion of the many sampling depths of the SIMS data to 0-20 cm using mass preserving splines and the conversion of the particle size limit from FAO/WRB to USDA standard. To make sure, that the sum of the sand, silt and clay fractions was 100% additive log ratio (ALR) transformation was applied on both LUCAS and SIMS. Mapping was carried out using random forest kriging with 10-fold cross-validation on a 100 m * 100 m grid using 28 environmental covariates. The ALR maps were converted back, resulting in the sand, silt and clay maps. Using the three maps, soil texture classes were calculated for both datasets using the USDA soil texture triangle. The soil texture classes were compared to each other pixel-by-pixel using the taxonomical distances of the texture classes. The particle fraction maps were compared to each other also pixel-by-pixel using linear regression. The results let us conclude that the LUCAS and SIMS databases produce very similar maps of both sand, silt a clay. The soil texture class comparison also resulted in a very close match with the majority of the country producing very close or perfect matches.  The two soil monitoring systems produce very similar results when mapping sand, silt, clay and soil texture for the whole country and can safely be combined together for future use and mapping.

How to cite: Benő, A., Szatmári, G., Laborczi, A., Kocsis, M., Bakacsi, Z., and Pásztor, L.: Comparison of predicted soil physical property maps based on (i) LUCAS topsoil database and (ii) Hungarian Soil Information and Monitoring System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18218, https://doi.org/10.5194/egusphere-egu24-18218, 2024.

EGU24-18732 | Posters on site | SSS10.6

Development of a high spatial resolution legacy soil profile database for the Southern Great Hungarian Plain 

Mihály Kocsis, Hilda Hernádi, András Makó, Brigitta Szabó, Piroska Kassai, Gábor Szatmári, Annamária Laborczi, Katalin Takács, Kitti Balog, János Mészáros, András Benő, Zsófia Bakacsi, and László Pásztor

A high spatial resolution soil database is under development in Hungary consisting of legacy soil observation data originating from different soil surveys. The soil data collected for the presented  pilot area situated in the Southern Great Hungarian Plain will be the part of the Profile-level Database of Hungarian Large-Scale Soil Mapping (Hungarian acronym: NATASA). Presently, the NATASA soil database contains data from about 15,000 soil profiles in the sample area. The data from the soil profile records consist of two major parts: field descriptions and results of laboratory investigations. Soil profile locations are being processed using specifically elaborated GIS tools. Digitized profile records are being revised according to the national soil system and expert-based criteria, and the content of the database is being developed according to a uniform nomenclature. Essentially, the NATASA database will form the basis for the production of target soil hydrophysical property maps using environmental auxiliary variables and proper inference methods in standardized DSM approaches providing predictions for specific soil depths.

The results obtained will not only become tangible in the form of different target maps, but will also provide very valuable information on the extent of the vulnerability of the Hungarian Southern Great Plain production areas to inland water and drought caused by weather extremes under the influence of climate change. This could help in the development of a regional drought and water deficit management system, in the establishment of a basis for irrigation investments or in the further development of the methodology of the current inland water vulnerability map. A more detailed knowledge of the hydrophysical properties of soils with spatial data could help to develop natural water retention measures.

Acknowledgement: The work was carried out within the framework of the Széchenyi Plan Plus program with the support of the RRF 2.3.1 21 2022 00008 project and the Sustainable Development and Technologies National Programme of the Hungarian Academy of Sciences (FFT NP FTA).

How to cite: Kocsis, M., Hernádi, H., Makó, A., Szabó, B., Kassai, P., Szatmári, G., Laborczi, A., Takács, K., Balog, K., Mészáros, J., Benő, A., Bakacsi, Z., and Pásztor, L.: Development of a high spatial resolution legacy soil profile database for the Southern Great Hungarian Plain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18732, https://doi.org/10.5194/egusphere-egu24-18732, 2024.

EGU24-19741 | ECS | Posters on site | SSS10.6

Digital soil analysis and mapping using in-situ Vis-NIR spectroscopy – Challenges and future perspectives 

Akos-Etele Csibi, Hans Sanden, Pavel Baykalov, Ruth Pereira, Anabela Cachada, Boris Rewald, and David Perry

The use of Vis-NIR spectroscopy in digital soil mapping is emerging as a fast, viable option to provide 
spatial and temporal information on specific soil parameters that serve as good indicators for soil 
health. While MIR spectroscopy tends to be a much more reliable (high-precision) tool for different 
soil properties estimations, currently only NIR can be adapted for rapid in-situ soil surveys.
The Subterra Green device, developed by “S4 Mobile Laboratories”, equipped with a Visible and an 
FTIR spectrometer can optimally capture spectra until 90 cm underground down to a 1 cm resolution. 
With a carefully selected sampling pattern, a survey of several hectares can be conducted in a matter 
of few days as a single insertion takes about 2-6 minutes.
One scope of the PHENET project is to carry out soil surveys in different locations with varying soil 
types, from the humid continental zones of Austria to the temperate oceanic climate of Portugal. 
This will be done by creating models which are verified with laboratory biochemical analysis of soil 
samples. Previous scientific resource concluded that some soil properties like the soil water content 
or texture can have a major effect on the recorded spectra, so when building up a database for 
machine learning models from different site surveys (with unique spatial and temporal conditions) a 
lot of external factors should be taken into consideration and pre-processing techniques selected, 
like external parameter orthogonalization or calibration spiking for creating an accurately predicting 
model for soil parameters prediction. The aim is to provide estimations of soil organic carbon and 
nitrogen stocks as well as interpolated maps in different soil depths. Being able to do fast and highresolution soil maps using in-situ Vis-NIR soil spectroscopy makes it possible to improve precision 
agriculture and monitor soil properties over space and time.

How to cite: Csibi, A.-E., Sanden, H., Baykalov, P., Pereira, R., Cachada, A., Rewald, B., and Perry, D.: Digital soil analysis and mapping using in-situ Vis-NIR spectroscopy – Challenges and future perspectives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19741, https://doi.org/10.5194/egusphere-egu24-19741, 2024.

Farmers, agricultural decision-makers, and land-use planners require updated, reliable, and accurate assessments of soil characteristics for sustainable management of natural resources. Saline and calcareous soils are a significant threat to crop production and can significantly reduce agricultural productivity, especially in arid and semi-arid regions. The accumulation of salt in the root zone restricts soil processes including nitrification, denitrification, and residue decomposition due to diminishing microorganism activity and soil biodiversity. On the other hand, in calcareous soils, the availability of some nutrients such as P, Fe, and Cu is limited due to the high pH. Given that traditional approaches to monitoring and mapping are costly and time-consuming, a rapid and efficient estimation of soil properties has been given attention by researchers using remote sensing data with field measurements. In this study, we have explored the performance of the PRISMA hyperspectral imagery satellite (prisma.asi.it) for estimating spatial variations of electrical conductivity (EC) and calcium carbonate equivalent (CCE). The study took place in the marginal lands of Sirjan Playa, southeast of Iran (Lat. 55°32′E, Lon. 29°23′N), which are mainly under pistachio cultivation. A total of twelve PRISMA L2D (BOA reflectance) images, acquired from June 2020 to December 2023; co-registered with the closest Sentinel-2 image (of about 0.5 pixel of RMS) and smoothed by the Savitzky-Golay filter (frame size of 7 and 3rd degree polynomial), were used. Field campaigns were performed to collect 250 soil samples from the top 15 cm of surface soil. Furthermore, the EC (min = 1.25%, max = 44.75%, std = 5.65%). and CCE (min = 1.25%, max = 44.75%, std = 5.65%) was measured using HCl. Both gaussian process regression (GPR) and the partial least squares regression (PLSR) algorithms were tested to predict EC and CCE from PRISMA 2D image spectra The results revealed that GPR achieved good prediction for CCE with a R2 of 0.75, a root mean square error (RMSE) of 4.09%, and a ratio of performance to interquartile distance (RPIQ) of 2.75. The PLSR model, instead, showed the highest performance (R2 = 0.63, RMSE = 44.8, RPIQ = 1.5) for predicting EC. These models were validated by the K-fold cross-validation approach (k = 10). The reason for the weaker salinity (EC) prediction by the PLSR could be attributed to the non-linear spectral behavior with respect to the salinity level. Furthermore, it seems that the presence of significant amounts of gypsum in the area could mask the accuracy of the EC prediction. Moreover, salt (i.e., the dominant salt is halite in the study area) diagnostic absorption bands occur in the atmospheric water vapor absorption region of soil spectra. Therefore, hyperspectral remote sensing appears to be a valuable resource for monitoring the spatiotemporal variation of EC (a fair prediction model with an RPIQ of 1.5) and CCE (a very good model with an RPIQ of 2.75). Further analysis should be done to better understand the effect of the external parameter (e.g., gypsum abundance) on the EC prediction.

How to cite: Mirzaei, S., Rasooli, N., and Pignatti, S.: Evaluating the spatial variations of soil salinity and calcium carbonate in marginal lands of Sirjan playa (Iran), using PRISMA hyperspectral imagery, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20310, https://doi.org/10.5194/egusphere-egu24-20310, 2024.

EGU24-20367 | Posters on site | SSS10.6

PRISMA SOC, pH and CCE Soil Properties Retrieval Using GPR algorithm with pre-treated datasets: Italy case studies 

Saham Mirzaei, Raffaele Casa, Rocchina Guarini, Giovanni Laneve, Luca Marrone, Khalil Misbah, Simone Pascucci, Stefano Pignatti, Francesco Rossi, and Alessia Tricomi

Soil organic carbon (SOC), pH and calcium carbonate content have an important role in the availability of nutrients for plants. Estimation of soil pH, calcium carbonate equivalent (CCE) and SOC (in the case of low variation) using satellite multi and hyperspectral data is still a challenging issue. Hyperspectral data acquired by new-generation spaceborne imagers like PRISMA and EnMAP offer new opportunities to accurately quantify soil properties. In this research the capability of Gaussian Process Regression (GPR) algorithm for SOC, pH and CCE retrieval from different pre-treated PRISMA spectra has been evaluated. To cover a wide topsoil variability, three different study areas in Italy were selected: Jolanda di Savoia (Lat. 44.87°N, Lon. 11.97°E), Maccarese (Lat. 41.87°N, Lon. 12.22°E) and Pignola (Lat. 40.56°N, Lon. 5.76°E). Soil samples were collected according to a 30 m squares elementary sample unit scheme and the SOC (n=635, min =0.19%, max=6.4%, std=1.55), CCE (n=518, min=0%, max=15.1, std=4.614) and the pH (n=460, min=5.035, max=8.075, std=0.769) was measured. The pH values of the samples show a -0.57 and 0.55 correlation with SOC and CCE, respectively. An overall total of 46 clear sky PRISMA images, acquired between 2019 and 2023, were used for this study. The L2D images were co-registered by the AROSICS algorithm which uses the Sentinel-2 image acquired at the closest date, to assure the co-registration (of about 0.5pixel of RMS). Noisy spectral bands and those affected by atmospheric water absorption in PRISMA images were removed, leaving a total of 173 spectral bands. The spectra were smoothed using a Savitzky-Golay filter (SG) with a second-order polynomial and a filter length of 7. To minimize the impact of the soil moisture (SM) effects, the spectra of 198 soil samples, at different SM levels, were acquired in our laboratory using a FieldSpec 4 spectroradiometer and then resampled to the PRISMA bands to be used for developing the external parameter orthogonalization (EPO) of the reflectance. A Principal Component Analysis (PCA) was also applied on the pre-treatments of the reflectance dataset (i.e., reflectance, first derivative reflectance, and EPO-projected reflectance). The first 10 PCs were selected and used for training the GPR Machine Learning (ML) models. A k-fold (k=10) cross-validation method was applied for SOC, pH and CCE modelling. The results indicate that optimal performance is achieved for SOC (R2=0.84, RMSE=0.618%) and CCE (R2=0.70, RMSE=2.527%) by employing the first derivative of EPO-projected reflectance. In the case of pH, the use of reflectance yields the most favorable outcomes (R2=0.72, RMSE=0.411). Improving the accuracy in estimating the SOC, pH and CCE soil properties, which are critical components of productive soils, is very important to allow for an efficient allocation of resources, agricultural management, and the maintenance of fertile soils for an optimal crop growth and many other purposes. Future work will include a much wider range of soil types in different soil moisture conditions.

How to cite: Mirzaei, S., Casa, R., Guarini, R., Laneve, G., Marrone, L., Misbah, K., Pascucci, S., Pignatti, S., Rossi, F., and Tricomi, A.: PRISMA SOC, pH and CCE Soil Properties Retrieval Using GPR algorithm with pre-treated datasets: Italy case studies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20367, https://doi.org/10.5194/egusphere-egu24-20367, 2024.

EGU24-1261 | Orals | GM3.1

Machine-learning based 3D point cloud classification and multitemporal change analysis with simulated laser scanning data using open source scientific software 

Bernhard Höfle, Ronald Tabernig, Vivien Zahs, Alberto M. Esmorís Pena, Lukas Winiwarter, and Hannah Weiser

AIM: We will present how virtual laser scanning (VLS), i.e., simulation of realistic LiDAR campaigns, can be key for applying machine/deep learning (ML/DL) approaches to geographic point clouds. Recent results will be shown for semantic classification and change analysis in multitemporal point clouds using exclusively open source scientific software.

MOTIVATION: Laser scanning is able to deliver precise 3D point clouds which have made huge progress in research in geosciences over the last decade. Capturing multitemporal (4D: 3D + time) point clouds enables to observe and quantify Earth surface process activities, their complex interactions and triggers. Due to the large size of 3D/4D datasets that can be captured by modern systems, automatic methods are required for point cloud analysis. Machine learning approaches applied to geographic point clouds, in particular DL, have shown very promising results for many different geoscientific applications [1,2].

METHODS & RESULTS: While new approaches for deep neural networks are rapidly developing [1], the bottleneck of sufficient and appropriate training data (typically annotated point clouds) remains the major obstacle for many applications in geosciences. Those data hungry learning methods depend on proper domain representation by training data, which is challenging for natural surfaces and dynamics, where there is high intra-class variability. Synthetic LiDAR point clouds generated by means of VLS, e.g., with the open-source simulator HELIOS++ [3], can be a possible solution to overcome the lack of training data for a given task. In a virtual 3D/4D scene representing the target surface classes, different LiDAR campaigns can be simulated, with all generated point clouds being automatically annotated. VLS software like HELIOS++ allows to simulate any LiDAR platform and settings for a given scene, which offers high potential for data augmentation and the creation of training samples tailored to specific applications. In recent experiments [1], purely synthetic training data could achieve similar performances to costly labeled training data from real-world acquisitions for semantic scene classification.

Furthermore, surface changes can be introduced to create dynamic VLS scenes (e.g., erosion, accumulation, movement/transport). Combining LiDAR simulation with automatic change analysis, such as offered by the open-source scientific software py4dgeo [5], enables to perform ML for change analysis in multitemporal point clouds [6]. Recent results show that rockfall activity mapping and classification for permanent laser scanning data can be successfully implemented by combining HELIOS++, py4dgeo and the open-source framework VL3D, which can be used for investigating various ML/DL approaches in parallel.

CONCLUSION: Expert domain knowledge (i.e., definition of proper 3D/4D scenes) and the power of AI can be closely coupled in VLS-driven ML/DL approaches to analyze 3D/4D point clouds in the geosciences. Open-source scientific software already offers all required components (HELIOS++, VL3D, py4dgeo). 

REFERENCES:

[1] Esmorís Pena, A. M., et al. (2024): Deep learning with simulated laser scanning data for 3D point cloud classification. ISPRS Journal of Photogrammetry and Remote Sensing. under revision.

[2] Winiwarter, L., et al. (2022): DOI: https://doi.org/10.1016/j.rse.2021.112772 

[3] HELIOS++: https://github.com/3dgeo-heidelberg/helios

[4] VL3D framework: https://github.com/3dgeo-heidelberg/virtualearn3d

[5] py4dgeo: https://github.com/3dgeo-heidelberg/py4dgeo

[6] Zahs, V. et al. (2023): DOI: https://doi.org/10.1016/j.jag.2023.103406

How to cite: Höfle, B., Tabernig, R., Zahs, V., Esmorís Pena, A. M., Winiwarter, L., and Weiser, H.: Machine-learning based 3D point cloud classification and multitemporal change analysis with simulated laser scanning data using open source scientific software, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1261, https://doi.org/10.5194/egusphere-egu24-1261, 2024.

EGU24-1640 | ECS | Posters on site | GM3.1

Automatic Classification of Surface Activity Types from Geographic 4D Monitoring Combining Virtual Laser Scanning, Change Analysis and Machine Learning 

Vivien Zahs, Bernhard Höfle, Maria Federer, Hannah Weiser, Ronald Tabernig, and Katharina Anders

We advance the characterization of landscape dynamics through analysis of point cloud time series by integrating virtual laser scanning, machine learning and innovative open source methods for 4D change analysis. We present a novel approach for automatic identification of different surface activity types in real-world 4D geospatial data using a machine learning model trained exclusively on simulated data.

Our method focuses on classifying surface activity types based on spatiotemporal features. We generate training data using virtual laser scanning of a dynamic coastal scene with artificially induced surface changes. Scenes with surface change are generated using geographic knowledge and the concept of 4D objects-by-change (4D-OBCs) [1, 2], which represent spatiotemporal subsets of the scene that exhibit change with similar properties. A realistic 3D scene modelling is essential for accurately replicating the dynamic nature of coastal landscapes, where morphological changes are driven by both natural processes and anthropogenic activities.

The Earth's landscapes exhibit complex dynamics, spanning large spatiotemporal scales, from high-mountain glaciers to sandy coastlines. The challenge lies in effectively detecting and classifying diverse surface activities with varying magnitudes, spatial extents, velocities, and return frequencies. Effective characterization of these dynamics is crucial for understanding the underlying environmental processes and their interplay with human activities. Supervised machine learning classification of surface activities from point cloud time series is challenging due to the limited availability of comprehensive and diverse real-world datasets for training and validation. Our approach combines virtual laser scanning with machine learning-based classification, enabling the generation of comprehensive training datasets covering the full spectrum of expected change patterns [3].

In our approach, the simulation of LiDAR point clouds is performed in the open-source framework HELIOS++ [4, 5]. HELIOS++ allows the flexible simulation of custom LiDAR campaigns with diverse acquisition modes and settings together with automatic annotations of artificially induced surface changes. We train a supervised machine learning model to classify synthetic 4D-OBCs into typical surface activity types of a sandy beach (e.g. dune erosion/accretion, sediment transport, etc.). Moreover, we investigate descriptors for 4D-OBCs, assessing their suitability for representing general types of surface activity (transferable between use cases) and types specific to particular surface processes.

We evaluate our model for 4D-OBC classification in terms of its capacity to discriminate surface activity types in a real-world dataset of a sandy beach in the Netherlands [6]. 4D-OBCs are extracted, classified into our target classes and validated with manually labelled reference data based on expert evaluation.

Our study showcases the efficacy of coupling virtual laser scanning, innovative open-source 4D change analysis methods, and machine learning for classifying natural surface changes [7]. Our findings not only contribute to advancing the understanding of landscape dynamics but also provide a promising approach to mitigating environmental challenges.

REFERENCES

[1] Anders et al. (2022): DOI: https://doi.org/10.5194/egusphere-egu22-4225

[2] py4dgeo: https://github.com/3dgeo-heidelberg/py4dgeo 

[3] Zahs et al. (2022): DOI: https://doi.org/10.1016/j.jag.2023.103406

[4] HELIOS++: https://github.com/3dgeo-heidelberg/helios

[5] Winiwarter et al. (2022): DOI: https://doi.org/10.1016/j.rse.2021.112772 

[6] Vos et al. (2022): DOI: https://doi.org/10.1038/s41597-022-01291-9

[7] CharAct4D: www.uni-heidelberg.de/charact4d

How to cite: Zahs, V., Höfle, B., Federer, M., Weiser, H., Tabernig, R., and Anders, K.: Automatic Classification of Surface Activity Types from Geographic 4D Monitoring Combining Virtual Laser Scanning, Change Analysis and Machine Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1640, https://doi.org/10.5194/egusphere-egu24-1640, 2024.

The acquisition of aerial photographs for cartographic applications started in the 1930s, and more intensively after World War II. Such old, often panchromatic, imagery offers metre to sub-metre scale spatial resolution over landscapes that have significantly evolved over the decades. Before the appearance of the first digital aerial camera systems at the end of the 20th Century, surveys were performed with analogue metric cameras, with images acquired on films or glass plates and, next, developed on photo papers. In Europe and North America, several institutions hold unique collections of historical aerial photographs having local, national and, in some cases, colonial coverages. They represent invaluable opportunities for environmental studies, allowing the comparison with today’s land use land cover, and the analysis of long-term surface displacements.

Initially, the photogrammetric processing of analogue aerial photographs would require expensive equipment, specialised operators, and significant processing time. Thanks to the digital revolution of the past two decades and the development of modern digital photogrammetric approaches, the processing of this type of image datasets has become less cumbersome, time consuming and expensive, at least in theory. In practice, this is more complex, with digitising and processing issues related to the ageing and quality of conservation of the aerial photographs, the potential distortions created during the digitising process, and the lack of ancillary data, such as, flight plans, and camera calibration reports. The limited overlap between photographs, typically 60 % and 10-20 %, along-track and across-track, respectively, make their processing with Structure-from-Motion Multi-View Stereo (SfM-MVS) photogrammetry poorly reliable to accurately reconstruct the topography and orthorectify the images. Given the fact that some collections reach up to millions of historical aerial photographs, the digitising, pre-processing, and photogrammetric processing of these images remain a challenge that must be properly tackle if we would like to ensure their preservation and large-scale valorisation.

In the present work, we describe the mass-digitising, digital image pre-processing and photogrammetric processing approaches implemented at the Royal Museum for Central Africa (RMCA, Belgium) to preserve and valorise the collection of >320,000 historical aerial photographs conserved in this federal institution. This imagery was acquired between the 1940’s and the 1980’s, over Central Africa, and mostly D.R. Congo, Rwanda and Burundi. For the digitising, a system of parallelized flatbed scanners controlled by a Linux computer and a self-developed software allows speeding-up the scanning of the entire collection in only few years. A series of Python scripts were developed and combined to allow a swift pre-processing that prepare and optimise the digitised images for photogrammetric processing. Finally, a SfM-MVS photogrammetric approach adapted to historical aerial photos is used. Examples of application for geo-hydrological hazards studies in the western branch of the East African Rift are shown.

How to cite: Smets, B., Dille, A., Dewitte, O., and Kervyn, F.: Digitising, pre-processing and photogrammetric processing of historical aerial photographs for the production of high resolution orthomosaics and the study of geohazards, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2356, https://doi.org/10.5194/egusphere-egu24-2356, 2024.

EGU24-4399 | ECS | Posters on site | GM3.1

Evaluating the efficacy of multitemporal TLS and UAS surveys for quantifying wind erosion magnitudes of sand dune topography 

László Bertalan, Gábor Négyesi, Gergely Szabó, Zoltán Túri, and Szilárd Szabó

Wind erosion constitutes a prominent land degradation process in regions of Hungary characterized by low annual precipitation. In these areas, it poses significant challenges to agricultural productivity and adversely impacts soil and environmental quality. Presently, human activities exert a more pronounced influence on the endangered areas of Hungary in comparison to climate-related factors. It is noteworthy that the wind erodibility of Hungarian soils not only poses a soil conservation challenge but also gives rise to economic ramifications, such as nutrient loss, as well as environmental and human health concerns. Within agricultural landscapes, wind erosion contributes to the removal and transportation of the finest and biologically active soil fractions, rich in organic matter and nutrients.

High-resolution topographic surveys have become integral for assessing volumetric changes in sand dune mobility and mapping wind erosion. While Unmanned Aerial Systems (UAS) surveys have been extensively employed for erosion rates exceeding the decimeter scale, Terrestrial Laser Scanning (TLS) surveys have demonstrated efficiency in capturing more extensive negative erosional forms, even in a vertical orientation. To enhance the field of view, a mounting framework can be implemented to elevate the TLS. However, determining centimeter-scale material displacement in flat terrain conditions remains challenging and requires an increased number of scanning positions.

To identify optimal settings for surveying centimeter-scale wind erosion magnitudes, we conducted combined multi-temporal TLS and UAS surveys at the Westsik experimental site near Nyíregyháza during the spring of 2023. This site features dune topography with a height of 6 meters. Our investigations encompassed various UAS image acquisition modes, involving different flight altitudes and camera settings, utilizing a DJI Matrice M210 RTK v2 drone and a Zenmuse X7 24 mm lens. Additionally, we generated diverse point clouds through various scanning scenarios using a Trimble X7 TLS device. In the data processing phase, we explored multiple co-registration algorithms to address the challenge of larger Root Mean Square Error (RMSE) in Digital Terrain Models (DTMs) from UAS Structure from Motion (SfM) compared to the actual wind erosion rates.

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The research is supported by the NKFI K138079 project.

How to cite: Bertalan, L., Négyesi, G., Szabó, G., Túri, Z., and Szabó, S.: Evaluating the efficacy of multitemporal TLS and UAS surveys for quantifying wind erosion magnitudes of sand dune topography, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4399, https://doi.org/10.5194/egusphere-egu24-4399, 2024.

EGU24-5142 | Posters on site | GM3.1 | Highlight

Four nationwide Digital Surface Models from airborne historical stereo-images 

Christian Ginzler, Livia Piermattei, Mauro Marty, and Lars T. Waser

Historical aerial images, captured by film cameras in the previous century, have emerged as valuable resources for quantifying Earth's surface and landscape changes over time. In the post-war period, historical aerial images were often acquired to create topographic maps, resulting in the acquisition of large-scale aerial photographs with stereo coverage. Using photogrammetric techniques on stereo-images enables extracting 3D information to reconstruct Digital Surface Models (DSMs), and orthoimages.

This study presents a highly automated photogrammetric approach for generating nationwide DSMs for Switzerland at 1 m resolution using aerial stereo-images acquired between 1979 and 2006. The 8-bit scanned images, with known exterior and interior orientation, were processed using BAE Systems' SocetSet (v5.6.0) with the "Next-Generation Automatic Terrain Extraction" (NGATE) package for DSM generation. The primary objective of the study is to derive four nationwide DSMs for the epochs 1979-1985, 1985-1991, 1991-1998, and 1998-2006. The study assesses DSM quality in terms of vertical accuracy and completeness of image matching across different land cover types, with a focus on forest dynamics and management research.

The elevation accuracy of the generated DSMs was assessed using two reference datasets. Firstly, the elevation differences between a nationwide reference Digital Terrain Model (DTM - swissAlti3d 2017 by Swisstopo) and the generated DSMs were calculated on points classified as "sealed surface". Secondly, elevation values of the DSMs were compared to approximately 500 independent geodetic points distributed across the country. Six study areas were chosen to assess completeness, and it was calculated as the percentage of successfully matched points to the potential total number of matched points within a predefined area. This assessment was conducted for six land cover classes based on the land cover/land-use statistics dataset from the Federal Office of Statistics.

Across the entire country, the median elevation accuracy of the DSMs on sealed points ranges between 0.28 to 0.53 m, with a Normalized Median Absolute Deviation (NMAD) of around 1 m (maximum 1.41 m) and an RMSE of a maximum of 3.90 m. The elevation differences between geodetic points and DSMs show higher accuracy, with a median value of a maximum of 0.05 m and an NMAD smaller than 1 m. Completeness results reveal mean completeness between 64 % to 98 % for the classes "glacial and perpetual snow" and "sealed surfaces," respectively and 93 % specifically for the “closed forest” class.

This work demonstrates the feasibility of generating accurate DSM time series (spanning four epochs) from historical scanned images for the entire Switzerland in a highly automated manner. The resulting DSMs will be available upon publication, providing an excellent opportunity to detect major surface changes, such as forest dynamics.

How to cite: Ginzler, C., Piermattei, L., Marty, M., and Waser, L. T.: Four nationwide Digital Surface Models from airborne historical stereo-images, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5142, https://doi.org/10.5194/egusphere-egu24-5142, 2024.

EGU24-5670 | ECS | Posters on site | GM3.1

Enhancing 3D Feature-based Landslide Monitoring Efficiency by Integrating Contour Lines in Laser Scanner Point Clouds 

Kourosh Hosseini, Jakob Hummelsberger, Daniel Czerwonka-Schröder, and Christoph Holst

Landslides are a pervasive natural hazard with significant societal and environmental impacts. In addressing the critical need for accurate landslide detection and monitoring, our previous research introduced a feature-based monitoring method enhanced by histogram analyses, straddling a middle ground between point-based and point cloud-based methods. This paper expands upon that foundation, introducing an innovative contour line extraction technique from various epochs to precisely identify areas prone to deformation. This refined focus diverges from conventional methodologies that analyze entire point clouds. By applying on regions where contour lines do not match, indicating potential ground movement, we significantly elevate the efficiency and precision of our feature-based monitoring system.

 

One of the principal challenges of feature-based monitoring is managing a substantial number of outliers. Our prior research tackled this issue effectively by integrating feature tracking with histogram analysis, thereby filtering these outliers from the final results. However, the process of extracting features from each patch and matching them with corresponding patches from different epochs was time-intensive.

 

The incorporation of contour line extraction into our workflow, using high-resolution laser scanner data, allows for a more focused and efficient analysis. We can now identify and analyze areas of landscape alteration with greater accuracy. This approach limits the application of feature tracking and histogram analysis to these critical areas, thus streamlining the process and significantly reducing computational demands. This focused methodology not only accelerates data processing but also enhances the accuracy of landslide predictions.

 

Our findings indicate a substantial improvement in the efficiency of landslide monitoring methods. This methodology represents a promising advancement in geospatial analysis, particularly for environmental monitoring and risk management in regions susceptible to landslides. This research contributes to the ongoing efforts to develop more effective, efficient, and accurate approaches to landslide monitoring, ultimately aiding in better informed and timely decision-making processes for hazard mitigation and risk management.

How to cite: Hosseini, K., Hummelsberger, J., Czerwonka-Schröder, D., and Holst, C.: Enhancing 3D Feature-based Landslide Monitoring Efficiency by Integrating Contour Lines in Laser Scanner Point Clouds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5670, https://doi.org/10.5194/egusphere-egu24-5670, 2024.

EGU24-5674 | ECS | Orals | GM3.1

Piecewise-ICP: Efficient Registration of 4D Point Clouds for Geodetic Monitoring 

Yihui Yang, Daniel Czerwonka-Schröder, and Christoph Holst

The permanent terrestrial laser scanning (PLS) system has opened the possibilities for efficient data acquisition with high-temporal and spatial resolution, thus allowing for improved capture and analyses of complex geomorphological changes on the Earth's surface. Accurate georeferencing of generated four-dimensional point clouds (4DPC) from PLS is the prerequisite of the following change analysis. Due to the massive data volume and potential changes between scans, however, efficient, robust, and automatic georeferencing of 4DPC remains challenging, especially in scenarios lacking signalized and reliable targets. This georeferencing procedure can be typically realized by designating a reference epoch and registering all other scans to this epoch. Addressing the challenges in targetless registration of topographic 4DPC, we propose a simple and efficient registration method called Piecewise-ICP, which first segments point clouds into piecewise patches and aligns them in a piecewise manner.

Assuming the stable areas on monitored surfaces are locally planar, supervoxel-based segmentation is employed to generate small planes from adjacent point clouds. These planes are then refined and classified by comparing defined correspondence distances to a monotonically decreasing distance threshold, thus progressively eliminating unstable planes in an efficient iterative process as well as preventing local minimization in the ICP process. Finally, point-to-plane ICP is performed on the centroids of the remaining stable planes. We introduce the level of detection in change analysis to determine the minimum distance threshold, which mitigates the influence of outliers and deformed areas on registration accuracy. Besides, the spatial distribution of empirical registration uncertainties on registered point clouds is derived based on the variance-covariance propagation law.

Our registration method is demonstrated on two datasets: (1) Synthetic point cloud time series with defined changes and transformation parameters, and (2) a 4DPC dataset from a PLS system installed in the Vals Valley (Tyrol, Austria) for monitoring a rockfall. The experimental results show that the proposed algorithm exhibits higher registration accuracy compared to the existing robust ICP variants. The real-time capability of Piecewise-ICP is significantly improved owing to the centroid-based point-to-plane ICP and the efficient iteration process.

How to cite: Yang, Y., Czerwonka-Schröder, D., and Holst, C.: Piecewise-ICP: Efficient Registration of 4D Point Clouds for Geodetic Monitoring, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5674, https://doi.org/10.5194/egusphere-egu24-5674, 2024.

EGU24-5757 | Posters on site | GM3.1

Arctic puzzle: pioneering a shrimp habitat model in topographically complex Disko Bay (West Greenland) 

Diana Krawczyk, Tobias Vonnahme, Ann-Dorte Burmeister, Sandra Maier, Martin Blicher, Lorenz Meire, and Rasmus Nygaard

Our study focuses on the geologically, topographically, and oceanographically complex region of Disko Bay in West Greenland. Disko Bay is also considered a marine biodiversity hotspot in Greenland. Given the impact of commercial fishing on seafloor integrity in the area, seafloor habitats studies are crucial for sustainable use of marine resources. One of the key fishery resources in Greenland, as well as in the North Atlantic Ocean, is northern shrimp.

In this study we analyzed multiple (1) monitoring datasets from 2010 to 2019, including data from shrimp and fish surveys, commercial shrimp fishery catches, satellite chlorophyll data, and (2) seafloor models, encompassing high-resolution (25 x 25 m) multibeam data with a low-resolution (200 x 200 m) IBCAO grid. Using multivariate regression analysis and spatial linear mixed-effect model we assessed the impact of physical (water depth, bottom water temperature, sediment type), biological (chlorophyll a, Greenland halibut predation), and anthropogenic factors (shrimp fishery catch and effort) on shrimp density in the area. The resulting high-resolution predictive model of northern shrimp distribution in Disko Bay is the first model of this kind developed for an Arctic area.

Our findings reveal that shrimp density is significantly associated with static habitat factors, namely sediment type and water depth, explaining 34% of the variation. The optimal shrimp habitat is characterized by medium-deep water (approximately 150-350 m) and mixed sediments, primarily in the north-eastern, south-eastern, and north-western Disko Bay. This pioneering study highlights the importance of seafloor habitat mapping and modeling, providing fundamental geophysical knowledge necessary for long-term sustainable use of marine resources in Greenland.

The developed high-resolution model contributes to a better understanding of detailed patterns in northern shrimp distribution in the Arctic, offering valuable insights for stock assessments and sustainable fishery management. This novel approach to seafloor habitat mapping supports the broader goal of ensuring the responsible utilization of marine resources, aligning with principles of environmental conservation and fisheries management. Our work serves as a foundation for ongoing efforts to balance economic interests with the preservation of marine ecosystems, fostering a harmonious coexistence between human activities and the fragile Arctic environment.

How to cite: Krawczyk, D., Vonnahme, T., Burmeister, A.-D., Maier, S., Blicher, M., Meire, L., and Nygaard, R.: Arctic puzzle: pioneering a shrimp habitat model in topographically complex Disko Bay (West Greenland), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5757, https://doi.org/10.5194/egusphere-egu24-5757, 2024.

EGU24-10361 | ECS | Orals | GM3.1

A Time-Series Analysis of Rockfall Evolution in a Coastal Region Using Remote Sensing Data 

Aliki Konsolaki, Emmanuel Vassilakis, Evelina Kotsi, Michalis Diakakis, Spyridon Mavroulis, Stelios Petrakis, Christos Filis, and Efthymios Lekkas

The evolution of technology, particularly the integration of Unmanned Aerial Systems (UAS), earth observation datasets, and historical data such as aerial photographs, stand as fundamental tools for comprehending and reconstructing surface evolution and potential environmental changes. In addition, the active geodynamic phenomena in conjunction with climate crisis and the increasing frequency of extreme weather phenomena can cause abrupt events such as rockfalls and landslides, altering completely the morphology on both small and large scales.

This study deals generally with the temporal evolution of landscapes and specifically focuses on the detection and quantification of a significant rockfall event that occurred at Kalamaki Beach on Zakynthos Island, Greece – a very popular summer destination. Utilizing UAS surveys conducted in July 2020 and July 2023, this research revealed a rockfall that has significantly altered the coastal morphology. During this period, two severe natural phenomena occurred, one of which could potentially be the cause of this rockfall event. Initially, the Mediterranean hurricane (‘medicane’) ‘Ianos’ made landfall in September 2020, affecting a large part of the country including the Ionian Islands. The result was severe damage to property and infrastructures, along with human casualties, induced by intense precipitation, flash flooding, strong winds, and wave action. Second, in September of 2022, an ML=5.4 earthquake struck between Cephalonia and Zakynthos Islands in the Ionian Sea, triggering considerable impact in both islands. The study employs satellite images postdating these natural disasters, to detect the source of the rockfall in Kalamaki Beach. Additionally, historical analog aerial images from 1996 and 2010 were used as assets for understanding the surface’s evolution. For the quantitative analysis, we applied 3D semi-automated change detection techniques such as the M3C2 algorithm, to estimate the volume of the rockfall.

The results provide insights into the complex interplay between natural disasters and geological processes, shedding light on the dynamic nature of landscapes and the potential implications for visitor-preferred areas.

This research not only contributes to our understanding of landscape evolution but also underscores the importance of integrating modern and historical datasets to decipher the dynamic processes shaping the Earth's surface. The methodology proposed, serves as a valuable approach for assessing and managing geological hazards in coastal regions affected by both climatic events and geodynamic activities.

How to cite: Konsolaki, A., Vassilakis, E., Kotsi, E., Diakakis, M., Mavroulis, S., Petrakis, S., Filis, C., and Lekkas, E.: A Time-Series Analysis of Rockfall Evolution in a Coastal Region Using Remote Sensing Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10361, https://doi.org/10.5194/egusphere-egu24-10361, 2024.

EGU24-10373 | Orals | GM3.1

A database for ancillary information of three-dimensional soil surface microtopography measurements. 

Kossi Nouwakpo, Anette Eltner, Bernardo Candido, Yingkui Li, Kenneth Wacha, Mary Nichols, and Robert Washington-Allen

Understanding the complex processes occurring at the soil surface is challenging due to the intricate spatial variability and dynamic nature of these processes. An effective tool for elucidating these phenomena is three-dimensional (3D) reconstruction, which employs advanced imaging technologies to create a comprehensive representation of the soil surface at high spatial resolution, often at the mm-scale. Three-dimensional reconstruction techniques are increasingly available to scientists in the fields of soil science, geomorphology, hydrology, and ecology and many studies have employed these novel tools to advance understanding of surface processes. Much of the data being collected in these studies are however not interoperable, i.e., 3D data from one study may not be directly combined with 3D data from other studies thus limiting the ability of researchers to advance process understanding at a broader scope. The limited interoperability of existing data is due in part to the fact that 3D surface reconstruction data are influenced by many factors including experimental conditions, intrinsic soil properties and accuracy and precision limits of the 3D reconstruction technique used. These ancillary data are crucial to any broad-scope efforts that leverage the increasing number of 3D datasets collected by scientists across disciplines, geographic regions, and experimental conditions. We have developed a relational database that archives and serves ancillary data associated with published high-resolution 3D data representing soil surface processes. This presentation introduces the structure of the database with its required and optional variables. We also provide analytics on the currently available records in the database and discuss potential applications of the database and future developments.

How to cite: Nouwakpo, K., Eltner, A., Candido, B., Li, Y., Wacha, K., Nichols, M., and Washington-Allen, R.: A database for ancillary information of three-dimensional soil surface microtopography measurements., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10373, https://doi.org/10.5194/egusphere-egu24-10373, 2024.

EGU24-11949 | ECS | Posters on site | GM3.1

Employng satellite immagery interpretation tools to detect land-use land-change dynamics in Italian historical rural landscapes 

Virginia Chiara Cuccaro, Claudio Di Giovannantonio, Giovanni Pica, Luca Malatesta, and Fabio Attorre

Rural landscapes inherited from the past are marked by a strong interaction between man and nature, a relationship rooted in a long history that testifies to the importance of the landscape as one of the most historically representative expressions of a country's cultural identity.

In this broad context, olive groves markedly characterize the agricultural landscape of many European rural areas, particularly in the Mediterranean region. Along with other rural landscapes, they form a semi-natural environment that can contribute to biodiversity conservation, soil protection and ecosystem resilience.

In addition to the global increase in temperatures, the main threats affecting these agrarian landscapes include the abandonment of traditional practices and the intensification of cultivation through the installation of irregular, intensive and overly dense planting beds.

The Land Cover classification and change-detection can provide useful indications for the restoration, conservation, and enhancement of olive groves

The objective of this work was to identify , rural landscapes in the Lazio region with characteristics of historical interest and determine their level of conservation. In particular, it was investigated the olive landscape of Cures (historic province of Sabina) trough a multi-temporal analysis of literature and cartographic information (e.g. orthophotos from the Italian Aeronautical Group flight of 1954)

The technique concerns the VASA (Historical Environmental Assessment) methodology, which allows the temporal evaluation of a given landscape and can inform on how agricultural practices and land use have changed over time.

Softwares  Collect Earth and Google Earth were employed to manipulate the historical series of high-resolution satellite images and implement photointerpretation. The coverage of identitied land units  was then estimated to address the configuration of the target landscape.

Landscape evolution over time was achieved by overlaying the 1954 and 2022 land use polygons, resulting in a merging database, in which an evolutionary dynamic was associated with each land use change.

The approach generated in-depth insights on the significant elements of the CURES olive landscape and informed on the dynamics of the area in relation to the risk of their disappearance, making it possible to identify what are the "landscape emergencies," i.e., the land uses that have seen the most̀ reduction in their area.

The methodologies employed have proven reliability in improving the knowledge ng target landscapes.  It might be useful to promote  sustainable agricultural practices for better preservation and management of rural environments so that cultural traditions can be preserved as well, and the environmental balance of the agrarian land can be maintained.

How to cite: Cuccaro, V. C., Di Giovannantonio, C., Pica, G., Malatesta, L., and Attorre, F.: Employng satellite immagery interpretation tools to detect land-use land-change dynamics in Italian historical rural landscapes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11949, https://doi.org/10.5194/egusphere-egu24-11949, 2024.

EGU24-12105 | ECS | Orals | GM3.1 | Highlight

Unleashing the archive of aerial photographs of Iceland, 1945-2000. Applications in geosciences  

Joaquín M. C. Belart, Sydney Gunnarson, Etienne Berthier, Amaury Dehecq, Tómas Jóhannesson, Hrafnhildur Hannesdóttir, and Kieran Baxter

The archive of historical aerial photographs of Iceland consists of ~140,000 vertical aerial photographs acquired between the years 1945 and 2000. It contains an invaluable amount of information about human and natural changes in the landscape of Iceland. We have developed a series of automated processing workflows for producing accurate orthomosaics and Digital Elevation Models (DEMs) from these aerial photographs, which we’re making openly available in a data repository and a web map visualization service. The workflow requires two primary inputs: a modern orthomosaic to automatically extract Ground Control Points (GCPs) and an accurate DEM for a fine-scale (sub-meter) alignment of the historical datasets. We evaluated the accuracy of the DEMs by comparing them in unchanged terrain against accurate recent lidar and Pléiades-based DEMs, and we evaluated the accuracy of the orthomosaics by comparing them against Pléiades-based orthomosaics. The data are becoming available at https://loftmyndasja.lmi.is/. To show the potential applications of this repository, we present the following showcases where these data reveal significant changes the landscape in Iceland in the past 80 years: (1) volcanic eruptions (Askja 1961, Heimaey 1973 and the Krafla eruptions, 1975-1984), (2) decadal changes of Múlajökull glacier from 1960-2023, (3) Landslides (Steinsholtsjökull 1967, Tungnakvíslarjökull 1945-present) and (4) coastal erosion (Surtsey island).

How to cite: Belart, J. M. C., Gunnarson, S., Berthier, E., Dehecq, A., Jóhannesson, T., Hannesdóttir, H., and Baxter, K.: Unleashing the archive of aerial photographs of Iceland, 1945-2000. Applications in geosciences , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12105, https://doi.org/10.5194/egusphere-egu24-12105, 2024.

EGU24-14087 | ECS | Posters on site | GM3.1

A point-cloud deep learning model based on RGB-D images: Application of riverbed grain size survey 

Bo Rui Chen and Wei An Chao

The water level and discharge of river are crucial parameters to understand the variance in riverbed scour. The detail behavior of scouring can be studied by the hydraulic simulation. The grain-size distribution of riverbed is also one of crucial parameter for modeling. Thus, how to investigate the grain-size of riverbed efficiently and swiftly is the urgent issue. However, the conventional measurement methods including Wolman counts (particles sampled at a fixed interval) which are a long and laborious task cannot survey the grain-size efficiently in the large area. In recent years, with an advantage of image segmentation and recognition has been applied to the investigation of grain-size, for example, capturing images through UAV and generating orthoimage is one of commonly used image technique. Although above the method can investigate the grain-size in the large area, it does not provide the information in the field immediately. Hence, a recent study developed the low-cost portable scanner to obtain the information of grain-size distribution in the field. However, the calibrating parameters of camera (e.g., height camera capture) are necessary before survey, and the uncertainties in calculation of image resolution will significantly affect the accuracy of grain-size analysis. Therefore, this study provides the additional algorithm to analyze the grain-size by using RGB-D image as inputs. The application of RGB-D can be categorized into two-dimensional (2D) and three-dimensional (3D) spaces. In a case of 2D, it integrates depth information with traditional RGB image processing to separate the grain-size of riverbed from the background (e.g., bottomland). Furthermore, depth information is also applied for grain-size edge detection. In a case of 3D, the collected RGB-D image information is transformed into point cloud data, then extract 3D features of grain particle by Deep learning, specifically PointNet. Our study demonstrates that clustering of 3D features can achieve the automatic identification of particle. The grain-size of particle can also be estimated by fitting 3D ellipsoid geometry. In the end, results show the grain-size distribution curves with the RGB、RGB-D、PointNet recognition, and compare with the true observations. 3D image information provides the cloud points of grain object, leading the possibility of estimating the 3D geometric morphology of the object. Our study successfully overcomes the limitations of conventional RGB-based process, which could only capture size and shape information in 2D planar. RGB-D-based image recognition, is an innovative technique for the hydraulic problem, not only advances survey efficiency but also addresses the intricate steps required for field investigations.

 

Key words: Riverbed grain size, RGB-D image, Point cloud, Deep Learning

How to cite: Chen, B. R. and Chao, W. A.: A point-cloud deep learning model based on RGB-D images: Application of riverbed grain size survey, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14087, https://doi.org/10.5194/egusphere-egu24-14087, 2024.

EGU24-14680 | Orals | GM3.1

Using current 3D point clouds as a tool to infer on past geomorphological processes 

Reuma Arav, Sagi Filin, and Yoav Avni

Examining deposition and erosion dynamics during the late Pleistocene and Holocene is crucial for gaining insights into soil development, erosion, and climate fluctuations. This urgency intensifies as arable lands face escalating degradation rates, particularly in arid and semi-arid environments. Nevertheless, as the destructive nature of erosional processes allows only for short-term studies, long-term processes in these regions are insufficiently investigated. In that respect, the ancient agricultural installations in the arid Southern Levant offer distinctive and undisturbed evidence of long-term land dynamics. Constructed on a late Pleistocene fluvial-loess section during the 3rd-4th CE and abandoned after 600-700 years, these installations record sediment deposition, soil formation, and erosion processes. The challenge is to trace and quantify these processes based on their current state. In this presentation, we demonstrate how the use of 3D point cloud data enables us to follow past geomorphological processes and reconstruct trends and rates. Utilizing data gathered in the immediate vicinity of the UNESCO World Heritage Site of Avdat (Israel), we illustrate how these point clouds comprehensively document the history of soil dynamics in the region. This encompasses the initial erosion phase, subsequent soil aggradation processes resulting from anthropogenic interruption, and the ongoing reinstated erosion. The unique setting, which uncovers the different fluvial sections, together with the detailed 3D documentation of the site, allows us to develop means for the reconstruction of the natural environment in each of the erosion/siltation stages. Therefore, by utilizing the obtained data, we can recreate the site during its developmental stages till the present day. Furthermore, we utilize terrestrial laser scan data sequence acquired in the past decade (2012-2022) to compute current erosion rates. These are then used to determine past rates, enabling inferences about the climatic conditions prevalent in the region over the last millennium. The in-depth examination of these installations provides valuable insights into approaches for soil conservation, sustainable desert living, and strategies to safeguard world-heritage sites subjected to soil erosion. As the global imperative to address soil erosion intensifies, this case study gains heightened relevance.

How to cite: Arav, R., Filin, S., and Avni, Y.: Using current 3D point clouds as a tool to infer on past geomorphological processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14680, https://doi.org/10.5194/egusphere-egu24-14680, 2024.

EGU24-15439 | ECS | Orals | GM3.1 | Highlight

Utilizing historical aerial imagery for change detection in Antarctica 

Felix Dahle, Roderik Lindenbergh, and Bert Wouters

Our research explores the potential of historical images of Antarctica for change detection in 2D and 3D. We
make use of the TMA Archive, a vast collection of over 330,000 black and white photographs of Antarctica taken
between 1940 to 1990. These photographs, available in both nadir and oblique, are systematically captured
from airplanes along flight paths and offer an unprecedented historical snapshot of the Antarctic landscape.
Detecting changes between past and present observations provides a unique insight into the long-term impact
of changing climate conditions on Antarctica’s glaciers, and their dynamical response to ice shelf weakening and
disintegration. Furthermore, it provides essential validation data for ice modelling efforts, thereby contributing
to reducing the uncertainties in future sea level rise scenarios.

In previous work, we applied semantic segmentation to these images [1]. By employing classes derived from this
segmentation, we can focus on features of interest and exclude images with extensive cloud coverage, enhancing
the accuracy of change analyses. In the next step, we geo-referenced the images: We assigned the images to
their actual position, scaled them to their true size, and aligned them with their genuine orientation. This
presents novel opportunities for detecting environmental changes in Antarctica, particularly in the retreat of
glaciers and sea ice.

Furthermore, the combination of these two steps allows for the first time a large scale reconstruction of these
images in 3D through Structure from Motion (SfM) techniques, which enables further multidimensional change
detection by comparing historical 3D models with contemporary ones. Due to the high number of images,
manual processing is impractical. Therefore, we are investigating the possibility of automatizing this process.
We utilize MicMac, an open-source software developed by the French National Geographic Institute for the
creation of the 3D models. Its high modularity allows for necessary customizations to automate the SfM
process effectively. Further adaptions are required due to the poor image quality and monotonous scenery. By
comparing historical 3D models with contemporary ones, we can assess alterations in elevation due to factors
such as glacial isostatic adjustments and glacier retreat.

We have already employed geo-referenced images for detecting changes on the Antarctic peninsula and are in the
process of creating initial 3D models. Our presentation will outline the workflow we developed for this process
and showcase the initial results of the change detection, both in 2D and 3D formats. This approach marks a
significant step in understanding and visualizing the impacts of climate change on the Antarctic landscape.

Acknowledgements
This work was funded by NWO-grant ALWGO.2019.044.

References
[1] F. Dahle, R. Lindenbergh, and B. Wouters. Revisiting the past: A comparative study for semantic segmen-
tation of historical images of Adelaide Island using U-nets. ISPRS Open Journal of Photogrammetry and
Remote Sensing, 11:100056, 2024.

How to cite: Dahle, F., Lindenbergh, R., and Wouters, B.: Utilizing historical aerial imagery for change detection in Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15439, https://doi.org/10.5194/egusphere-egu24-15439, 2024.

EGU24-15896 | Orals | GM3.1

Classification and segmentation of 3D point clouds to survey river dynamics and evolution  

Laure Guerit, Philippe Steer, Paul Leroy, Dimitri Lague, Dobromir Filipov, Jiri Jakubinsky, Ana Petrovic, and Valentina Nikolova

3D data for natural environments are now widely available via open data at large scales (e.g., OpenTopography) and can be easily acquired on the field by terrestrial LiDAR scan (TLS) or by structure-from-motion (SFM) from camera or drone imagery. The 3D description of landscapes gives access to an unprecedented level of details that can significantly change the way we look at, understand, and study natural systems. Point clouds with millimetric resolution even allow to go further and to investigate the properties of riverbed sediments: dedicated algorithms are now able to extract the sediment size distribution or their spatial orientation directly from the point cloud. 

Such data can be real game changers to study for example torrential streams prone to flash floods or debris flows. Such events are usually associated with heavy rainfall events, while conditioned by the geomorphological state of a stream (e.g., channel geometry, vegetation cover). The size and the shape of the grains available in the river also strongly influence river erosion and sediment transport during a flood. 3D data can thus help to design prevention and mitigation measures in streams prone to torrential events. 

However, it is not straightforward to go from data acquisition to river erosion or to grain-size distributions. Indeed, isolating and classifying the areas of interest can be complex and time-consuming. This can be done manually, at the cost of time and absence of reproducibility. We rather take advantage of state-of-the-art classification method (3DMASC) to develop a general classifier for point clouds in fluvial environments designed to identify five classes usually found in such settings: coarse sediments, sand, bedrock, vegetation and human-made structures. We also improved the G3Point sediment segmentation algorithm, developed by our team, to make it more efficient and straightforward to use in the CloudCompare software, which is dedicated to point cloud visualization and analysis. We apply it to the coarse sediments class identified by 3DMASC to provide a more accurate description of grain size and orientation. We also make a profit of the sand class to estimate its relative areal distribution that can then be compared to the coarse sediment class. This provides valuable information about the type of flows which are also important for planning torrential events mitigation measures.

We illustrate this combined approach with two field examples. The first one is based on SFM data acquired along streams prone to torrential events in Bulgaria and in Serbia where we documented sediment size and orientation. The second one is based on TLS data acquired along a bedrock river in France that experienced a major flood which induced dramatic changes in the river morphology. 

This work has been partially funded by PHC Danube n° 49921ZG/ n° KP-06-Danube/5, 14.08.2023 (National Science Fund, Bulgaria) and the H2020 European Research Council (grant no. 803721). 

How to cite: Guerit, L., Steer, P., Leroy, P., Lague, D., Filipov, D., Jakubinsky, J., Petrovic, A., and Nikolova, V.: Classification and segmentation of 3D point clouds to survey river dynamics and evolution , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15896, https://doi.org/10.5194/egusphere-egu24-15896, 2024.

EGU24-16939 | ECS | Posters on site | GM3.1 | Highlight

Integrating structure-from-motion photogrammetry with 3D webGIS for risk assessment, mapping and monitoring of coastal area changes in the Maltese archipelago 

Emanuele Colica, Daniel Fenech, Christopher Gauci, and George Buhagiar

The Maltese coasts extend for approximately 273km, representing a notable resource for the country and of one of its pillar economies, the tourism sector. Natural processes and anthropic interventions continue to threaten Malta's coastal morphology, shaping its landscape and triggering soil erosion phenomena. Therefore, many research projects (Colica et al., 2021, 2022 and 2023) have concentrated their work on the investigation and monitoring of the instability of cliffs and the erosion of pocket beaches. The results of such activities can be widely disseminated and shared with expert and non-expert users through web mapping, which has only been used in a very limited way in collaborative coastal management and monitoring by different entities in Malta. This study describes the performance of a WebGIS designed to disseminate the results of innovative geomatic investigations for monitoring and analyzing erosion risk, performed by the Research and Planning Unit within the Public Works Department of Malta. While aiming to include the entire national coastline, three study areas along the NE and NW regional coasts of the island of Malta have already been implemented as pilot cases. This WebGIS was generated using ArcGIS pro software by ESRI and a user-friendly interactive interface has been programmed to help users view in 2D and 3D, satisfying both multi-temporal and multi-scale perspectives. It is envisaged that through further development and wider dissemination there will be a stronger uptake across different agencies involved in coastal risk assessment, monitoring and management.

References

Colica, E., D’Amico, S., Iannucci, R., Martino, S., Gauci, A., Galone, L., ... & Paciello, A. (2021). Using unmanned aerial vehicle photogrammetry for digital geological surveys: Case study of Selmun promontory, northern of Malta. Environmental Earth Sciences, 80, 1-14.

Colica, E. (2022). Geophysics and geomatics methods for coastal monitoring and hazard evaluation.

Colica, E., Galone, L., D’Amico, S., Gauci, A., Iannucci, R., Martino, S., ... & Valentino, G. (2023). Evaluating Characteristics of an Active Coastal Spreading Area Combining Geophysical Data with Satellite, Aerial, and Unmanned Aerial Vehicles Images. Remote Sensing, 15(5), 1465.

How to cite: Colica, E., Fenech, D., Gauci, C., and Buhagiar, G.: Integrating structure-from-motion photogrammetry with 3D webGIS for risk assessment, mapping and monitoring of coastal area changes in the Maltese archipelago, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16939, https://doi.org/10.5194/egusphere-egu24-16939, 2024.

EGU24-17822 | ECS | Posters on site | GM3.1

Evaluating Ordnance Survey sheets (1890s – 1957) for shoreline change analysis in the Maltese Islands  

Daniel Fenech, Jeremie Tranchant, Christopher Gauci, Daniela Ghirxi, Ines Felix-Martins, Emanuele Colica, and George Buhagiar

 

Jeremie' Tranchant1, Daniel Fenech1, Christopher Gauci1, Daniela Ghirxi1, Ines Felix Martins1, Emanuele Colica1, George Buhagiar1

1  Research and Planning Unit, Ministry for Transport, Infrastructure and Public Works, Project House, Triq Francesco    Buonamici, Floriana, FRN1700, Malta

The assessment of coastal erosion through shoreline change analysis, is an exercise of national utility undertaken in many countries. The Maltese Islands are particularly vulnerable to coastal erosion given the economic value of coastal activities and their high ratio of coast-to-land surface. The integration of historical cartographic material is often used to hindcast shoreline change across long periods of time, as well as to model future erosion rates. The Public Works Department have produced detailed 1:2500 maps of Malta in collaboration with the British Ordnance Survey from the end of the 19th century to 1957, however these maps have never been scientifically assessed. The initial research carried out evaluated the usefulness of the two oldest 25-inches Maltese maps series (early 20th century and 1957) for shoreline change analysis.  The two series were digitised, georeferenced, and compared in a GIS environment to assess their differences. The inaccuracies of the original drawings, absent shoreline indicators, and the absence of a geographic coordinate system (datum and projection) were identified as limitations for their use in evaluating small gradual changes, but were ideal for the identification of stochastic, large-scale historic erosion events using difference maps. This assessment showed that the two series are highly congruous and any changes between the two series are largely attributed to changes in infrastructure. There were, however, minor exceptions and these need to be explored on a case-by-case basis. These methods and the insights garnered from their production will function as scientific steppingstones towards developing a holistic coastal erosion national monitoring program.  

How to cite: Fenech, D., Tranchant, J., Gauci, C., Ghirxi, D., Felix-Martins, I., Colica, E., and Buhagiar, G.: Evaluating Ordnance Survey sheets (1890s – 1957) for shoreline change analysis in the Maltese Islands , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17822, https://doi.org/10.5194/egusphere-egu24-17822, 2024.

EGU24-21396 | ECS | Orals | GM3.1

Automatic detection of river bankfull parameters from high density lidar data 

Alexandre Rétat, Nathalie Thommeret, Frédéric Gob, Thomas Depret, Jean-Stéphane Bailly, Laurent Lespez, and Karl Kreutzenberger

The European Water Framework Directive (WFD), adopted in 2000, set out requirements for a
better understanding of aquatic environments and ecosystems. In 2006, following the transposition of
the WFD into French law (LEMA), France began work on a field protocol for the geomorphological
characterization of watercourses, as part of a partnership between the Centre National de la Recherche
Scientifique (CNRS) and the Office Français de la Biodiversité (OFB). This protocol, known as "Carhyce"
(For « River Hydromorphological Caracterisation »), has been tested, strengthened and approved over
the last 15 years at more than 2500 reaches. It consists of collecting standardised qualitative and
quantitative data in the field, essential for the caracterisation of a watercourse: channel geometry,
substrate, riparian vegetation... However, certain rivers that are difficult to survey (too deep or too
wide) pose problems for data collection.
To address these issues, and to extend the analysis to a wider scale (full river section), using
remote sensing, and in particular LiDAR data, was considered. The major advantages of LiDAR over
passive optical sensors are better geometric accuracy and especially under vegetation. For a long time,
LiDAR data rarely exists at national scale with data density similar to passive imagery. Today, the French
LiDAR HD dataset (10 pulses per meter square) program run by the French mapping agency offers an
unprecedented amount of data at this scale. Thanks to them, a national 3D coverage of the ground can
be used, and numerous geomorphological measurements can be carried out on a more or less large
scale. This is the case for hydromorphological parameters such as water level and width.
The aim of this study is therefore to use this high-density lidar to automatically determine the
hydromorphological parameters sought in the Carhyce protocol. In particular, we have developed a
lidar-based algorithm to reconstruct the topography from point cloud and automatically identify the
bankfull level at reach scale. Designed to be applicable to every French river, the method must be
robust to all river features such as longitudinal slope, width, sinuosity, multi-channel etc... For
validation purposes, the bankfull geometry calculated by the algorithm has been compared with field
measurements at some twenty Carhyce stations across France. To determine the test stations, we
looked for the diversity of situations in terms of river characteristics describe above to observed the
influence of this features on the results.

How to cite: Rétat, A., Thommeret, N., Gob, F., Depret, T., Bailly, J.-S., Lespez, L., and Kreutzenberger, K.: Automatic detection of river bankfull parameters from high density lidar data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21396, https://doi.org/10.5194/egusphere-egu24-21396, 2024.

EGU24-22358 | ECS | Orals | GM3.1 | Highlight

UAV’s to monitor the mass balance of glaciers 

Lander Van Tricht, Harry Zekollari, Matthias Huss, Philippe Huybrechts, and Daniel Farinotti

Uncrewed Aerial Vehicles (UAVs) are increasingly employed for glacier monitoring, particularly for small to medium-sized glaciers. The UAVs are mainly used to generate high-resolution Digital Elevation Models (DEMs), delineate glacier areas, determine surface velocities, and map supraglacial features. In this study, we utilise UAVs across various sites in the Alps and the Tien Shan (Central Asia) to monitor the mass balance of glaciers. We present a workflow for calculating the annual geodetic mass balance and obtaining the surface mass balance using the continuity-equation method. Our results demonstrate generally a close alignment between the determined mass balances and those obtained through traditional glaciological methods involving intensive fieldwork. We show that utilising UAV data reveals significantly more spatial details, such as the influence of debris and collapsing ice caves, which are challenging to capture using conventional methods that strongly rely on interpolation and extrapolation. This underscores the UAV's significance as a valuable add-on tool for quantifying annual glacier mass balance and validating glaciological assessments. Drawing on our experience in on-site UAV glacier surveys, we discuss the methodology's advantages, disadvantages, and potential pitfalls. 

How to cite: Van Tricht, L., Zekollari, H., Huss, M., Huybrechts, P., and Farinotti, D.: UAV’s to monitor the mass balance of glaciers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22358, https://doi.org/10.5194/egusphere-egu24-22358, 2024.

EGU24-338 | ECS | Posters on site | HS7.10

Supplementing rainfall simulator studies with single drop measurements 

Michał Beczek, Magdalena Ryżak, Karolina Gibała, Rafał Mazur, Agata Sochan, Cezary Polakowski, Tomasz Beczek, and Andrzej Bieganowski

Rainfall simulators are essential tools for geoscientific and hydrological research, e.g. water erosion processes, throughfall phenomenon, interception etc. They allow the creation of suitable and reproducible experimental conditions providing a large amount of information. However, in certain situations, e.g. the soil splash phenomenon, other research methods are needed to study the basic processes and mechanisms on a smaller scale, i.e. concerning the interaction of single drops. In such a case, single drop measurements used with raindrop generators can be a good complementary tool for rainfall simulators. They provide complete understanding and description of the investigated phenomenon.

The aim of this study was to present selected measurement methods based on the single drop methodology which are used to investigate splash erosion and surface deformation, interaction of drops with leaves or conifers, and microorganism transportation. These include: a) a set of high-speed cameras with PTV (Particle Tracking Velocimetry) software used to identify, track, and characterize the splashed particles and water droplets; b) splash cup measurements for the determination of the mass ratio of splashed particles during the raindrop splash phenomenon; c) a 3D surface scanner and microtomography for the description of surface deformation after the drop impact; d) a laser diffraction method and light microscopy for the determination of the size of splashed particles; e) IRMS (Isotope-ratio mass spectrometry), i.e., deuterium-labelled water used to the define the origin of the splashed water.

 

This work was partly financed from the National Science Centre, Poland; project no. 2022/45/B/NZ9/00605.

 

References:

Beczek M., Ryżak M., Sochan A., Mazur R., Polakowski C., Hess D., Bieganowski A.: Methodological aspects of using high-speed cameras to quantify soil splash phenomenon. GEODERMA 378, 2020

Mazur R., Ryżak M., Sochan A., Beczek M., Polakowski C., Przysucha B., Bieganowski A.: Soil deformation after one water-drop impact – The effect of texture and soil moisture content. GEODERMA 417, 2022

Ryżak M., Beczek M., Mazur R., Sochan A., Gibała K., Polakowski C., Bieganowski A.: The splash of a single water drop on selected coniferous plants. Forest Ecology and Management 541, 121065, 2023

How to cite: Beczek, M., Ryżak, M., Gibała, K., Mazur, R., Sochan, A., Polakowski, C., Beczek, T., and Bieganowski, A.: Supplementing rainfall simulator studies with single drop measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-338, https://doi.org/10.5194/egusphere-egu24-338, 2024.

EGU24-3431 | Posters virtual | HS7.10

Investigating effects of different vegetation layers on soil erosion with a portable rainfall simulator 

Steffen Seitz, Corinna Gall, Nicolás Riveras-Muñoz, Zhengshan Song, and Thomas Scholten

Small-scale field rainfall simulators provide scientists with a tool to investigate complex interconnections between landcover and soil erosion experimentally. In particular, specific effects of vegetation such as plant structure or traits on sediment translocation are of key interest in erosion studies. A main feature of portable rainfall simulators is the formation of repeatable precipitation patterns with a kinetic energy corresponding to natural rainfall events at different locations in the field. Despite not measuring the whole process chain of water erosion, they assist to shed light on individual influences on sediment transport with an enhanced number of replications and thus adding to field measurements under natural rainfall.

In this context, the Tübingen Rainfall Simulator (TRS, single-nozzle, <1-2 m2) has been used in the last two decades to investigate the effect of plant diversity, individual plant species as well as fauna on soil erosion in different forest and agricultural ecosystems. Results show among others, that higher forest vegetation does often not show an erosion-reducing effect and the kinetic energy of rainfall in young forest plantations can exceed freefall kinetic energy several fold. Impacts on sediment transport are strongly species-specific and depending on individual plant traits such as plant height, height of the first branch, branch angles or leaf sizes and shapes. Therefore, surface-near soil covering vegetation layers and contained mesofauna play a larger role than expected. Important reducing impacts can be initiated by biological soil crusts as a pioneer stage after vegetation disturbances, which also show severe impacts on water fluxes and infiltration in woodlands. Furthermore, these results from forestry are transferable to crop production and agriculture, where a positive impact of modern organic farming systems with short fallow periods and reduced soil-turning techniques on soil erosion control can be underlined.

In summary, portable simulator systems have proven reliable even under difficult operating conditions and could be successfully used to gather data sets with a high number of data points and to supplement large-scale erosion studies. They therefore help answering fundamental questions on the principal effects of vegetation on sediment translocation. For a better comparability of different studies and to further widen existing data sets, a harmonization of different field measurement approaches would be desirable.

How to cite: Seitz, S., Gall, C., Riveras-Muñoz, N., Song, Z., and Scholten, T.: Investigating effects of different vegetation layers on soil erosion with a portable rainfall simulator, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3431, https://doi.org/10.5194/egusphere-egu24-3431, 2024.

EGU24-8198 | Posters on site | HS7.10

Rainfall Microphysics and Instrument Measurement Assessments via Rainfall Simulators 

Firat Y. Testik, Rupayan Saha, and Kalimur Rahman

This study presents investigations on rainfall microphysical processes and ground-based rainfall instrument measurements through laboratory rainfall simulations with careful considerations for in-situ observations and validations.  Controlled laboratory rainfall experimentation has a pivotal role in systematic investigations to deepen our understanding of rainfall microphysical processes and the development, calibration, and assessment of rainfall instruments.  In the rainfall and related investigations in the PI’s laboratory over the past nearly two decades, we have utilized a variety of laboratory rainfall simulation setups, each featuring customized drop generators for the application, that were designed to address the specific aspects and objectives of the targeted research.  Here we will present our select experimental investigations on raindrop morphodynamics (shape and fall speed) and collisions as well as assessments of the OTT Parsivel2 disdrometer and OTT Pluvio2 rain gauge measurements.  Raindrop morphodynamics and collisions are of importance for various applications, including radar rainfall retrievals and hydrological modeling.  Parsivel2 and Pluvio2 are widely used ground-based instruments to monitor various precipitation quantities (e.g. raindrop size distribution, fall speed, and rainfall intensity, amount, and kinetic energy) that are of importance for a variety of rainfall- and water resources-related applications, including ground validation and soil erosion studies.  This material is based upon work supported by the National Science Foundation under Grants No. AGS-1741250 to the first author (FYT).

How to cite: Testik, F. Y., Saha, R., and Rahman, K.: Rainfall Microphysics and Instrument Measurement Assessments via Rainfall Simulators, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8198, https://doi.org/10.5194/egusphere-egu24-8198, 2024.

EGU24-8795 | ECS | Posters on site | HS7.10

An empirical approach to separate camera-based elevation change measurements due to sediment yield from other soil erosion masking processes   

Lea Epple, Oliver Grothum, Anne Bienert, and Anette Eltner

Over the past years studies (e.g., Hänsel et al. 2016 or Yang et al. 2021) have shown the feasibility of camera-based soil erosion assessment. This cost-efficient and non-invasive photogrammetric approach is a valuable tool to meassure soil surface changes (Balaguer-Puig et al., 2018). A challenging aspect nevertheless represents the masking of the sediment yield by surface lowering processes such as soil consolidation and compaction (Ehrhardt et al. 2022). Based on the camera elevation changes and measured field observations, we developed an approach to estimate these masking effects in the beginning of rainfall events and approximate a correction function.

We conducted ten rainfall simulations at plots with 3 m length and 1 m width on agricultural slopes. The runoff and sediment concentration were measured at the plots outlet, while a time-lapse camera system surrounding the plot took images every few seconds. We furthermore collected data on soil bulk density, soil moisture, grain size distribution, total organic carbon, slope steepness, surface cover and surface roughness. To describe the changes of the soil surface at the beginning of the rainfall events, dominated by the masking effects, S-shaped curves were fitted via non-linear regression for each rainfall experiment. We then used the variables of those functions as well as the field observations as input values for an adjustment to estimate masking effects at the beginning of rainfall simulations as functions of soil and plot characteristics.

The best results were achieved using four observations: grain size distribution, slope, bulk density and total carbon content. Our approach shows the potential to disentangle soil surface changes due to erosion and non-erosion processes at the onset of rainfall events. While the model worked well for most of the rainfall simulations, predictions were challenging for those events with strongly varying field observations. Especially difficult were those simulations conducted on freshly tilled soils. They showed high elevation changes at the beginning of the event that had great potential for soil consolidation and thus the mixed signals regarding the different processes were not separable by our approach. Nevertheless our study showed potential to increase the informative value of camera-based soil erosion measurements on agricultural fields.

 

References

Balaguer-Puig, M.; Marqués-Mateu, Á.; Lerma, J.L.; Ibáñez-Asensio, S. Quantifying small-magnitude soil erosion: Geomorphic change detection at plot scale. Land Degrad Dev 2018, 29, 825-834, doi:10.1002/ldr.2826.

Ehrhardt, A.; Deumlich, D.; Gerke, H.H. Soil Surface Micro-Topography by Structure-from-Motion Photogrammetry for Monitoring Density and Erosion Dynamics. Front. Environ. Sci. 2022, 9, doi:10.3389/fenvs.2021.737702.

Hänsel, P.; Schindewolf, M.; Eltner, A.; Kaiser, A.; Schmidt, J. Feasibility of High-Resolution Soil Erosion Measurements by Means of Rainfall Simulations and SfM Photogrammetry. Hydrol 2016, 3, 38, doi:10.3390/hydrology3040038.

Yang, Y.; Shi, Y.; Liang, X.; Huang, T.; Fu, S.; Liu, B. Evaluation of structure from motion (SfM) photogrammetry on the measurement of rill and interrill erosion in a typical loess. Geomorphology 2021, 385, 107734, doi:10.1016/j.geomorph.2021.107734.

How to cite: Epple, L., Grothum, O., Bienert, A., and Eltner, A.: An empirical approach to separate camera-based elevation change measurements due to sediment yield from other soil erosion masking processes  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8795, https://doi.org/10.5194/egusphere-egu24-8795, 2024.

EGU24-11487 | ECS | Posters on site | HS7.10

Laboratory calibration of non-catching rain gauges using a precision raindrop generator 

Enrico Chinchella, Arianna Cauteruccio, and Luca G. Lanza

Non-Catching Gauges (NCGs) are instruments used to measure precipitation without the need to collect the equivalent water volume in a reservoir. They sense each hydrometeor individually, often using a contactless approach, providing measurements of the relevant microphysical properties of precipitation. These gauges offer several advantages over traditional catching gauges, making them an invaluable source of data for numerous research applications. However, NCGs, like catching-type gauges, are susceptible to measurement biases from both instrumental and environmental sources. To assess instrumental biases, rigorous testing and calibration are required, which can be more challenging than for catching gauges. In fact, to provide reference precipitation, it is necessary to carefully reproduce hydrometeor characteristics such as particle size, shape, fall velocity, and density. Calibration is therefore typically delegated to manufacturers, who may use undisclosed procedures that cannot be traced to the international standards (see Lanza et al. 2021 for a review).

In this work, we use an existing precision raindrop generator, as detailed in the work of Baire et al. (2022), to verify the performance of optical NCGs that employ two different measuring principles. During laboratory tests, drops ranging from 0.6 to 5 mm in diameter were released from a height of 1.2 m over the instrument sensing area. At least 50 drops were generated for each combination of drop diameter and gauge tested. The generator independently measured the diameter and fall velocity of each released drop using a photogrammetric approach, providing a traceable reference for the calibration. The percentage errors for both the measured drop size and fall velocity were computed by comparing gauge measurements against the reference drop, either drop by drop (when the gauge provides the raw data) or in terms of Particle Size and Velocity Distribution (PSVD) matrix (for all gauges). Additionally, by assuming a literature Drop Size Distribution (DSD) and integrating measured and reference microphysical properties over the range of drop diameters tested, the percentage error for rainfall intensity measurements was also computed. The gauges tested show significant biases in both microphysical and integral properties, with the latter being larger than what is generally expected from traditional catching gauges.

The development of the precision raindrop generator was funded as part of the activities of the EURAMET project 18NRM03 “INCIPIT Calibration and Accuracy of Non-Catching Instruments to measure liquid/solid atmospheric precipitation”. The project INCIPIT has received funding from the EMPIR programme co-financed by the Participating States and from the European Union’s Horizon 2020 research and innovation programme. Laboratory testing of NCGs was carried out in the framework of the Italian national project PRIN2022MYTKP4 “Fostering innovation in precipitation measurements: from drop size to hydrological and climatic scales”.

References:

Lanza L.G. and co-authors, 2021: Calibration of non-catching precipitation measurement instruments: a review. J. Meteorological Applications, 28.3(2021):e2002.

Baire, Q and co-authors, 2022: Calibration uncertainty of non-catching precipitation gauges. Sensors, 22(17), 6413.

How to cite: Chinchella, E., Cauteruccio, A., and Lanza, L. G.: Laboratory calibration of non-catching rain gauges using a precision raindrop generator, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11487, https://doi.org/10.5194/egusphere-egu24-11487, 2024.

The estimation of sheet flow velocities is crucial to understanding and modelling the dynamics of surface flow processes. When direct flow velocity measurements are not feasible, the use of velocity tracers can be a valuable tool. Recent studies have shown that fluorescent quinine-based tracer can be used to estimate sheet flow surface velocities over various soil and urban surfaces under low luminosity conditions, when exposed to ultraviolet light. In this study, a quinine solution was used to test the applicability of this tracer to estimating the velocity of sheet flow disturbed by rainfall with different intensities. For this purpose, a series of laboratory experiments using a soil flume and a rainfall simulator were conducted to study flows under simulated rainfall. Several hydraulic conditions were explored. The rainfall simulator included a downward-oriented full-cone nozzle from Spraying Systems Co. The nozzle was positioned at an average height of 2.5 m from the geometric centre of the flume’s soil surface, with a spray angle of 90°. The working pressure on the nozzles was kept approximately constant at 50 kPa, producing rainfall at a maximum intensity of 150 mm h-1 just below the nozzle, with average drop sizes of approximately 1.7 mm. Flow velocities were estimated by injecting a quinine solution into the sheet flow. By tracking the leading-edge of the tracer plume and calculating the travel distance of the tracer’s leading edge over a certain time lapse, the surface velocity of the flow was evaluated. The results show that for high rainfall intensities, the disturbance of the water surface by the rainfall drops affected the visibility of the tracer and, thus, the ability to accurately estimate flow velocities using this tracer technique.

How to cite: P. de Lima, I., Zehsaz, S., and L.M.P. de Lima, J.: Testing the use of a fluorescent quinine-based tracer for estimating velocities of sheet flow under simulated rainfall: laboratory experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13300, https://doi.org/10.5194/egusphere-egu24-13300, 2024.

EGU24-13931 | ECS | Posters on site | HS7.10

Water ponding timing, spatial distribution, and connectivity on soil surfaces measured by time-lapse imagery processed with deep learning 

Pedro Zamboni, Jonas Lenz, Thomas Wöhling, and Anette Eltner

Measuring runoff formation on soil surfaces by rainfall simulators predominantly provide lumped values without spatiotemporal information in regard to water dynamics (e.g., water ponding timing and connectivity).  Understating spatial and temporal variations of water storage on soil surface is key to assess hydrological connectivity and runoff generation. Furthermore, it is very relevant for erosion studies. Computer vision and deep learning has presented state-of-the-art results in environmental sciences, for instance to segment water using cameras as gauges or performing flood mapping with remote sensing images. However, automatic mapping of water forming on soil surfaces due to rainfall is very challenging because the water area is considerably smaller and water ponds present complex shapes and similar color characteristics to the soil itself, which is a challenge for deep learning models. The aim of this study is to assess the potential of computer vision and deep learning to estimate water ponding timing, connectivity and runoff formation behavior during rainfall simulations, with emphasis on data imbalance and label uncertainty.

We conducted rainfall simulations at three different soil erosion plots with different soil and tillage caracteristics. Runoff was measured at the plot outlet. We collected time lapse images from the plot surface. And ground control points for model scaling were measured with a total station. To train the deep learning models, we manually labeled a selected set of images from all the plot images to derive binary masks (i.e., water and background). We trained three different convolution neural networks (CNN) and further considered techniques that take class imbalance and label uncertainty into account. Eventually, we assess the performance of ensemble models. We applied the best model on the whole set of time lapse images and measured the water pixel area and pond connectivity in terms of connected components. 

Our findings suggest that considering class imbalance and label uncertainty is key to reach satisfactory segmentation performance, being more important than the model architecture. Furthermore, ensemble models result in better performance when compared to single models. By comparing the measured discharge and the water area derived from the best deep learning model, we can observe different characteristics of the runoff formation related to distinct ponding and intensity of ponding and connectivity. Our approach presents an innovative visual and automatic observation option to quantify the water pond formation and its spatial temporal development. It is a step towards a better understanding of the runoff generation.

How to cite: Zamboni, P., Lenz, J., Wöhling, T., and Eltner, A.: Water ponding timing, spatial distribution, and connectivity on soil surfaces measured by time-lapse imagery processed with deep learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13931, https://doi.org/10.5194/egusphere-egu24-13931, 2024.

EGU24-16564 | ECS | Posters on site | HS7.10

Comparison of Kinetic Energies of Different Spraying Systems 

Martin Neumann, Steffen Seitz, Josef Krasa, Raquel Falcao, and Tomas Dostal

Rainfall simulators have been used for research of soil erosion by water for many years. Scientific teams around the world own a variety of different devices. In the case of comparing the results of several teams, the problem is the rainfall characteristics of different devices and therefore different input parameters. In this contribution, 3 devices were compared: a small rainfall simulator of the CTU, a small rainfall simulator of Tubingen University, and a laboratory rainfall simulator of the CTU. A laser diffractometer (Thies Clima Laser Precipitation Monitor 5.4110) was used to determine the kinetic energy (KE) and rainfall intensity and splash cups filled with sand (Tubingen Splash Cups, designed by Scholten et al., 2011) were used to compare the methods of the kinetic energy measurement. On each device, measurements were made on a plot with area 1 x 1 metre at nine positions with a rainfall intensity set at 60 mm h-1.

Significant differences among the devices were observed using the laser disdrometer. Small rainfall simulator of Tubingen University achieving a KE of approximately 2.5 J m-2 mm-1, small simulator of the CTU a KE of approximately 5.5 J m-2 mm-1, and the laboratory simulator of the CTU a KE of approximately 8 J m-2 mm-1. The kinetic energies obtained by the splash cups did not reach the values produced by the laser diffractometer. During the experiments, local irregularities in rainfall were observed associated with different types of nozzles and different simulator constructions. The splash cups (46 mm in size) allowed one to measure exact locations proving that locally KE can reach much higher values.

The experiments proved that the differences among different simulator constructions can greatly affect the results of the experiments performed, and the method of assessing the rainfall characteristics can help to understand the real functioning of each device.

This research was supported by the research projects QK22010261, Mobility 8J23DE006, and by the Grant Agency of the CTU in Prague SGS23/155/OHK1/3T/11.

How to cite: Neumann, M., Seitz, S., Krasa, J., Falcao, R., and Dostal, T.: Comparison of Kinetic Energies of Different Spraying Systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16564, https://doi.org/10.5194/egusphere-egu24-16564, 2024.

EGU24-20712 | Posters on site | HS7.10

Using Rainfall Simulators to Assess New Soil Protection Technologies 

Josef Krasa, Tomas Dostal, Martin Neumann, and Martin Mistr

Our aim is to compile a methodology for verifying the soil protection effect of various crop cultivation technologies directly in operating conditions and to design and verify such methods of anti erosion protection together with farmers. The methods should be effective, environmentally friendly, and should not endanger the competitiveness of Czech agriculture. The CTU in Prague, together with the Research Institute for Soil and Water Conservation, has been using a rainfall simulator of 8m plot length (16 m2) for soil loss ratio and C-factor estimation since 2015, putting together a database of several hundreds of representative measurements (Stasek et al., 2023).

To be able to test different technologies directly at fields in different field conditions, the simulator construction was modified to portable construction of 1m2 plot size. During 2023 both simulators were compared in the field, especially in cultivated fallow conditions, but also for initial crop stages. Technically to be able to operate in field and use limited amount of water while reaching high enough kinetic energy and rainfall uniformity, the construction uses overflow box capturing and recycling water that would be sprayed outside of the measured plot (Kavka et al., 2018). One of the advantages of the 8m plot length was that several nozzles with overlapping spraying cones still reach higher kinetic energies than a single-nozzle construction. What we investigated is that rill evolution is visible in 8 m long plot in fallow conditions, while for 1 m plot length, mostly only interril erosion is prevailing.  For 1 mm.minute-1 rainfall intensity both constructions reach similar runoff rates after ca 10 minutes of the simulation when starting with fully saturated conditions (0.9 litre per minute for large simulator, 0.85 litre per minute for small simulator using the same nozzle type). On the other hand, the sediment transport values at smaller plot size reach only 63% on average (0.0110 versus 0.0175 kg.minute-1). As expected, the variability of sediment transport is higher in between replications on the smaller plot size, due to the greater influence of small surface irregularities, or due to the greater influence of preferential pathways in both surface runoff and infiltration. The contribution presents ways of standardising smaller rainfall simulator data using previous datasets obtained by larger-scale simulations.

Data were obtained from the NAZV QK22010261, Mobility 8J23DE006, H2020Tudi No 101000224, and by the CTU Grant Agency in Prague No. SGS23/155/OHK1/3T/11.

 

How to cite: Krasa, J., Dostal, T., Neumann, M., and Mistr, M.: Using Rainfall Simulators to Assess New Soil Protection Technologies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20712, https://doi.org/10.5194/egusphere-egu24-20712, 2024.

The Mediterranean region is warming 20% faster than the global average. In addition, climate change is expected to exacerbate this situation in the next decades by increasing potential evapotranspiration, decreasing rainfall and increasing the frequency and intensity of droughts. During the last two years, many irrigated areas of Spain have already suffered from water shortages due to lack of water in reservoirs. In some cases, this has led to impose severe restrictions on water allocations of irrigation districts (ID). Since yield is inextricably linked to the amount of water used by plants, the primary effects of water shortage often appear on crop production. However, water restrictions may vary among irrigation districts, among others, depending on the total available water in the reservoir, land uses, or level of modernization. Thus, any imposition of water restriction has a different impact on crop productivity depending on these parameters. From a decision-making point of view, it would be very useful for watershed policy makers to have a tool capable to simulate the impact of decreases in rainfall and/or water restrictions on crop productivity at irrigation district and/or catchment level. Therefore, this study introduces a novel approach to assess the impact of different climate scenarios and restrictions of irrigation water allocations on crop productivity. The study was conducted in a total of eight irrigation districts located in the north-east Ebro basin (Catalonia, Spain), with different water allocations, which corresponded with a total irrigated area of 150,028 hectares. The following six scenarios were simulated: Control, without water restrictions; Pr25 and Pr50, a reduction in rainfall of 25 and 50%, respectively; Irri25, Irri50, Irri75, a reduction of irrigation water allocation of 25, 50 and 75%, respectively. The crop water productivity functions defined in the literature for multiple crops were used. In addition, actual crop evapotranspiration (ETa) was estimated daily at 20 m resolution using a remote sensing two-source energy balance model with Copernicus-based inputs. Overall, results showed that averaged ETa of all irrigation districts decreased by 14, 19, 29, 50 and 66% respectively for Pr25, Pr50, Irri25, Irri50, Irri75 in comparison to Control. On the other hand, yield losses varied among irrigation districts. Those IDs with higher water allocations showed a significant decrease in yield of around 27% in comparison to Control for scenarios Pr25, Pr50, Irri25 and Irri50, without significant differences among them. On the other hand, yield decreased by 72% in the Irri75. Instead, other irrigation districts with very low water allocations observed an averaged significant decrease in yield of 62% in comparison to Control in all the scenarios. A detailed analysis of the impact of the six simulated scenarios on crop productivity of each irrigation district and crop type is also conducted in this study.

How to cite: Bellvert, J., Casadesus, J., Pamies-Sans, M., and Girona, J.: Assessment of the impact of drought and restrictions on irrigation district water allocations on yield using a remote sensing for evapotranspiration approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1394, https://doi.org/10.5194/egusphere-egu24-1394, 2024.

EGU24-1837 | ECS | Orals | HS6.9

Retrieving the irrigation actually applied at district scale: assimilating high-resolution Sentinel-1-derived soil moisture data into a FAO-56-based model 

Pierre Laluet, Luis Enrique Olivera-Guerra, Víctor Altés, Giovanni Paolini, Nadia Ouaadi, Vincent Rivalland, Wouter Dorigo, Lionel Jarlan, Josep Maria Villar, and Olivier Merlin

Irrigation is the most water consuming activity in the world. Knowing the timing and amount of irrigation that is actually applied is therefore fundamental for water managers. However, this information is rarely available at all scales and is subject to large uncertainties due to the wide variety of existing agricultural practices and associated irrigation regimes (full irrigation, deficit irrigation, or over-irrigation). To fill this gap, we propose a two-step approach based on 15 m resolution Sentinel-1 (S1) surface soil moisture (SSM) data to retrieve the actual irrigation at the weekly scale over an entire irrigation district. In a first step, the S1-derived SSM is assimilated into a FAO-56-based crop water balance model (SAMIR) to retrieve for each crop type both the irrigation amount (Idose) and the soil moisture threshold (SMthreshold) at which irrigation is triggered. To do this, a particle filter method is implemented, with particles reset each month to provide time-varying SMthreshold and Idose. In a second step, the retrieved SMthreshold and Idose values are used as input to SAMIR to estimate the weekly irrigation and its uncertainty. The assimilation approach (SSM-ASSIM) is tested over the 8000 hectare Algerri-Balaguer irrigation district located in northeastern Spain, where in situ irrigation data integrating the whole district are available at the weekly scale during 2019. For evaluation, the performance of SSM-ASSIM is compared with that of the default FAO-56 irrigation module (called FAO56-DEF), which sets the SMthreshold to the critical soil moisture value and systematically fills the soil reservoir for each irrigation event. In 2019, with an observed annual irrigation of 687 mm, SSM-ASSIM (FAO56-DEF) shows a root mean square deviation between retrieved and in situ irrigation of 6.7 (8.8) mm week-1, a bias of +0.3 (-1.4) mm week-1, and a Pearson correlation coefficient of 0.88 (0.78). The SSM-ASSIM approach shows great potential for retrieving the weekly water use over extended areas for any irrigation regime, including over-irrigation.

How to cite: Laluet, P., Olivera-Guerra, L. E., Altés, V., Paolini, G., Ouaadi, N., Rivalland, V., Dorigo, W., Jarlan, L., Villar, J. M., and Merlin, O.: Retrieving the irrigation actually applied at district scale: assimilating high-resolution Sentinel-1-derived soil moisture data into a FAO-56-based model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1837, https://doi.org/10.5194/egusphere-egu24-1837, 2024.

EGU24-3839 | ECS | Posters on site | HS6.9

Assessing Global Climate Datasets for Small-Scale Agricultural Applications: The Case of Nemea, Greece 

Evangelos Dosiadis, Aikaterini Katsogiannou, Evangelos Nikitakis, Eleni Valiantza, Stylianos Gerontidis, Konstantinos Soulis, and Dionissios Kalivas

In recent years, extensive research has been conducted to evaluate various surface-, satellite-, and reanalysis-based gridded datasets of climatic variables on a global scale. However, a noticeable gap exists in understanding their effectiveness and accuracy in agricultural applications, particularly in very small-scale areas. While these datasets have proven valuable for assessing global climate patterns, their translation to on-the-ground impacts, especially in agricultural landscapes, remains a challenge. The complexities of agricultural systems, including irrigation management, farming practices, and responses to extreme weather events, demand a closer examination of the suitability and precision of existing climate datasets for informed decision-making in the agricultural sector.

This study seeks to address this gap by focusing on the wine-making region of Nemea, Greece, providing valuable insights into the utility of global climate datasets in agricultural applications and especially irrigation management to streamline precision irrigation management in regions where data scarcity prevails. The primary objective is to explore the applicability of diverse global climate datasets in small-scale areas, emphasizing the unique challenges posed by the very high spatial variability in regions characterized by complex landscapes, very steep relief, and very small farms. The study delves into the intricacies of irrigation management, and the impact of extreme temperatures on vine stress.

The methodology employed involves leveraging a variety of open-source global climate datasets, which are subsequently evaluated for accuracy through validation against local meteorological stations data. A network of 10 agrometeorological stations located throughout the wine-making region of Nemea will be used. The key variables under scrutiny include the variables related to irrigation and crop management, i.e. precipitation, air temperature, air humidity, wind velocity, and solar radiation. The applied methodology includes the assessment of the characteristics of the available grided datasets; the evaluation of the grided datasets accuracy in general and for specific conditions (e.g. heatwaves, frost days, storms etc.); and the comparison of optimum irrigation schedules compiled using detailed meteorological data obtained by local agrometeorological stations for a five-year period with the corresponding schedules compiled using the gridded datasets under evaluation. The effects of gridded datasets inaccuracies on crops development, crop stress, and crop yield quality and quantity are also evaluated.

The results demonstrate the clear influence of spatial resolution on data accuracy. The study underscores the significance of selecting datasets with an optimal spatial resolution to enhance the precision of climatic variables in large-scale areas. This insight contributes to the broader discourse on the practicality and limitations of employing global climate datasets in small scale agricultural applications in regions characterized by complex landscapes. Insights on relevant downscaling and correction methodologies are provided.  

How to cite: Dosiadis, E., Katsogiannou, A., Nikitakis, E., Valiantza, E., Gerontidis, S., Soulis, K., and Kalivas, D.: Assessing Global Climate Datasets for Small-Scale Agricultural Applications: The Case of Nemea, Greece, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3839, https://doi.org/10.5194/egusphere-egu24-3839, 2024.

EGU24-5126 | ECS | Orals | HS6.9

Synthesizing regional irrigation data using machine learning – towards global upscaling via metamodeling  

Søren Kragh, Raphael Schneider, Simon Stisen, Rasmus Fensholt, and Julian Koch

Knowledge on irrigation is key to sustainable water resource management, but spatio-temporal irrigation data are rarely available. Recent advances are based upon satellite remote sensing data to quantify irrigation at high spatial resolution, and this study utilizes published irrigation datasets at regional scale to develop a metamodel approach to synthesize the available irrigation knowledge. We investigate the potentials and limitations of a Random Forest-based metamodeling approach that predicts irrigation at monthly timescale using only globally available and easily accessible features related to hydroclimatic and vegetation variables. The training dataset consists of three irrigation water use datasets derived from the soil moisture-based inversion framework and covers a variety of climatic conditions and irrigation practices in Spain, Italy, and Australia. Further, the study includes irrigation predictions from three test sites representing major global hot spots for unsustainable irrigation management: the North China Plain, Indus, and Ganges Basins. Our study aims to test the model transferability in space and time based on a series of split-sample experiments. We quantify and outline model transferability based on the area of applicability analysis, showing that although the feature space was mostly well represented, the magnitude of the target variable was equally important for assessing model transferability. A comprehensive feature importance analysis reveals that ranking of the most important input features depends on geographical extent of the training dataset. We find that model transferability was more robust across space than time within the small study areas, mainly because of the small geographical extents of the training datasets. The developed metamodel demonstrates satisfying performance with less than 10% bias and 3 mm/month mean error for a successful model transferability outside the training study areas and predicted spatial patterns of irrigation closely linked to climate and vegetation features. Given the increase in published regional irrigation datasets, we see great potential for further developing metamodel approaches for synthesizing existing knowledge and work towards global upscaling opportunities.

How to cite: Kragh, S., Schneider, R., Stisen, S., Fensholt, R., and Koch, J.: Synthesizing regional irrigation data using machine learning – towards global upscaling via metamodeling , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5126, https://doi.org/10.5194/egusphere-egu24-5126, 2024.

Soil moisture data is highly valuable for irrigation management, however, soil data can often be difficult for farmers to interpret for making  informed irrigation decisions. Subsurface drip irrigation targets the root zone of crops. It is commonly used and highly efficient at minimizing evaporative loss. Factors, such as long irrigation lines and hilly terrain, influence the timing and duration of irrigation events, which makes arrival time and duration of crop irrigation water unpredictable even if there is a well-managed schedule.  Also, deficit irrigation is a practice where high value crops are intentionally water stressed after the fruiting stage to improve their quality and value. 

 

In this study, we propose a new modeling method for predicting soil moisture  that addresses the randomness of one of the primary boundary conditions, the irrigation event.  Through machine learning regression, we aim to predict near surface soil moisture values in a subsurface drip irrigated crop in a silt loam soil texture.  Our model focuses specifically on the dewatering portion of the time series soil moisture data at two depths, the soil textural data,  and the evapotranspiration (ET) as the only boundary condition. By predicting future soil moisture values or stress conditions in the absence of irrigation, our model provides valuable insights for farmers making irrigation management decisions. This presentation serves as a feasibility study and reports the results of the first attempt to apply machine learning regressors to time series soil moisture data to predict future near surface soil moisture values.

 

In our experiment, we placed two HydraProbe Soil Sensors in the root zone  of a blueberry crop located near Wilsonville Oregon in the United States. Soil moisture was logged every five minutes at  depths of   15 and 30 cm. The ET and soil moisture data were aggregated and parameterized into the input features for machine learning regressors. To create a training data set, algorithms were developed to isolate only the dewatering portions of the soil moisture time series data for a single growing season. The machine learning input features include: 1) the sum of ET for a specific duration interval, 2) soil moisture percentage, 3) the sum of the ET for the prior 24 hours, 4) the sum of forward-looking ET and 5) capillary features derived from soil texture pedotransfer functions (PFTs) that are part of the Richard’s Equation. The predicted near future soil moisture values are the output target of the model.

 

Using the Skikitlearn machine learning regressors, we evaluated random forest, support vector machine, ridge, and LASSO regressions. Each regressor underwent regularization through a grid-search of the hyper-parameters using the training data set. To measure potential overfitting of the models, a 15% holdout was examined using r2 and the RMSE (root mean square error). Additionally, a validation data set was created using seasonal low soil moisture values and time intervals not included in the training set.  Among the regressors evaluated, ridge regression performed well with an r2=0.98, RMSE=0.5% on the 15% holdout, and an r2=0.93, RMSE=1.13% on the validation data set.

How to cite: Bellingham, K.: Irrigation Management using Machine Learning Regressors of Aggregated Soil Moisture Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6626, https://doi.org/10.5194/egusphere-egu24-6626, 2024.

Rapid agricultural development in the Ica Valley of Peru has translated to historic and on-going unsustainable use of groundwater.  Decades of ineffective water resources management threatens the future of agricultural production, requiring an overhaul of water management decisions and actions, particularly for groundwater sustainability.  A key measure of robust groundwater management is an accurate estimate of groundwater use, particularly if groundwater use is thought to exceed regulatory abstraction limits.  In this study, remote sensing estimates of evapotranspiration are combined with precipitation and water use permit databases to quantify groundwater use that exceeds regulatory limits, termed illicit use.  We apply two energy balance approaches, METRIC and SEBAL, combined with gridded climate information to robustly quantify agricultural water use.  Our findings document that illicit groundwater use is approximately twice that of regulation abstraction rates, suggesting current management strategies are failing to mitigate unsustainable groundwater use.  The remote sensing workflow can be applied to quantify groundwater use to inform efficacy of future groundwater management decisions and aid to identify regions for future interventions.

How to cite: Thomas, B.: Landsat-based ET to assess illicit groundwater use: The Ica Valley, Peru, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11957, https://doi.org/10.5194/egusphere-egu24-11957, 2024.

EGU24-13738 | Posters on site | HS6.9

Rice Field Detection by Dual Polarization SAR Images  

Kuo-Hsin Tseng and Jui-Han Yang

Paddy rice plays a significant role in Asian agriculture, particularly in Taiwan. However, monitoring parcel-level activities and quantifying potential yield during the two crop cycles present challenges. The application of remote sensing to track paddy phenology emerges as a valuable strategy for improving crop management and ensuring food security. Synthetic Aperture Radar (SAR) satellites, among various spaceborne sensors, provide timely and extensive information unaffected by cloud cover. This study aims to extract time series data on paddy-specific phenology using dual-polarized SAR data and subsequently map paddy rice parcels in Taiwan. The process involves three primary steps: (1) Identifying phenological curves in training sites based on the temporal behavior of SAR backscattering coefficients; (2) Utilizing signal decomposition to analyze periodic patterns; (3) Recognizing rice fields by identifying the start and end of each crop cycle in the time series; (4) Validating the results with in situ data. In our preliminary findings, the accuracy in certain townships in western Taiwan achieves a kappa value of >0.6, with an overall accuracy exceeding 0.8. Additionally, we aim to unveil potential connections among crop cycles, groundwater changes, and land subsidence.

How to cite: Tseng, K.-H. and Yang, J.-H.: Rice Field Detection by Dual Polarization SAR Images , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13738, https://doi.org/10.5194/egusphere-egu24-13738, 2024.

In the context of transboundary water systems, one of the most relevant challenges involves the quantification of water use for large scale activities such as agriculture. Whether due to methodological differences in the consolidation of inventories of agricultural areas, their production calendars, or due to differences in data availability between neighboring countries, the consolidation of detailed information of water use represent a process to be improved for an appropriate allocation of resources in transboundary management. On the other hand, the advantages in the availability and spatiotemporal homogeneity of satellite data, added to the connotation to minimize issues related to neutrality and stakeholder biases involving the use of only local data threatening consensus in a transboundary framework, offers a strategical opportunity to enhance the integrated water management by using satellite data.

Under these considerations, the present study applies Landsat satellite images for the spatial and temporal quantification of agricultural water use in the transboundary region (110 969 km2) of the Titicaca Lake, Desaguadero River, and Poopo Lake System (TDP) located between Bolivia (55%), Chile (1%), and Peru (44%) in South America (Lima-Quispe et al., 2022). Data processing first allows, to define irrigated agricultural areas from those which are not irrigated, through a validation process using the inventory of agricultural areas available in the official repositories of the countries and running an analysis using climate data (precipitation and potential evapotranspiration), second; defines the spatiotemporal pattern of water use through the evaluation and combination of vegetation indices (NDVI, EVI, among others) for the total agricultural area of the TDP water system (Linear Regressions) for the crops with the largest extension and/or use of water (potatoes, bean, quinoa, barley) studied at the local level in a process of calibration and validation (Bretreger et al., 2019). The results, from the analysis make possible to classify divergences attributed to the methodology, and use of the remote sensing data (correlation, BIAS in relation to local data) as well as to identify areas where both at the level of surface extension and temporal pattern, real water use would be exceeding the permitted and feasible values (trend test analysis) and therefore would imply a critical condition of alteration over the water bodies involved, which stakeholders may pay attention whether through increasing monitoring to corroborate or to strength penalties for ecosystem protection.

References:

Lima-Quispe, N., Escobar, M., Wickel, A. J., von Kaenel, M., & Purkey, D. (2021). Untangling the effects of climate variability and irrigation management on water levels in Lakes Titicaca and Poopó. Journal of Hydrology: Regional Studies, 37, 100927.

Bretreger, D., Yeo, I. Y., Quijano, J., Awad, J., Hancock, G., & Willgoose, G. (2019). Monitoring irrigation water use over paddock scales using climate data and landsat observations. Agricultural water management, 221, 175-191.

How to cite: Ayala Ticona, G., Santos, T., Gonzales, C., and Purkey, D.: Application of satellite data for the quantification of agricultural water use in the context of the transboundary water system of Titicaca Lake, Desaguadero River, and Poopo Lake in South America, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14168, https://doi.org/10.5194/egusphere-egu24-14168, 2024.

EGU24-14901 | Posters on site | HS6.9

Exploring satellite soil moisture products for irrigation. A case study: Braila County, Romania 

Zenaida Chitu, Daniela Trifan, Alin Ghiorghe, Cristian Stroia, Nicolae Popescu, Irina Ontel, Claudiu-Valeriu Angearu, Adrian Irasoc, and Giorgiana Luftner

Irrigated agriculture will be impacted by climate change as average temperatures and rainfall variability increase. This trend will continue in the future, according to numerical experiments with climate models, but how it develops will be strongly influenced by the anthropogenic emission levels of greenhouse gases. However, the effects of climate change have not been, and will not be, uniform across regions or over time because human-induced warming is superimposed on natural climate variability (IPCC, 2021).

Recent studies (Caian et al., 2023) focused on the projected changes in extreme agro-climatic indicators reveal that Southern Romania appears as a regional hot-spot of climate change because the projected changes are higher and more accelerated than other regions of the country. In this context farmers will need to improve crop water allocation for sustainable irrigation as a measure of climate change adaptation.

Irrigation is the largest consumer in the agriculture sector and the efficient use of water is crucial in the next decades. Monitoring soil moisture will improve water allocation in space and time in irrigated agriculture. Braila County has the largest irrigated areas in Romania and efficient water allocation will mitigate the environmental issues related to water scarcity and soil degradation by salinization and erosion. According to the Koeppen-Geiger classification, the climate of this area is warm temperate humid with hot summers (Cfa) (Cheval et al., 2023). The mean annual precipitation is 450 mm, while the mean annual potential evapotranspiration exceeds 800 mm. The agro-climatic conditions require the use of irrigation in order to avoid crop losses and to ensure high crop productivity.

In this study, we focus on investigating the feasibility of satellite soil moisture products (AMSR-2, ASCAT, SMOS and SMAP) to derive amount of water applied for irrigation and the applicability of this approach to climatic and irrigation conditions specific to Braila County, Romania. 

This study has received funding from the European Union Agency for the Space Programme under the European Union’s Horizon Europe research and innovation programme under grant agreement No. 101082189 (MAGDA project).

How to cite: Chitu, Z., Trifan, D., Ghiorghe, A., Stroia, C., Popescu, N., Ontel, I., Angearu, C.-V., Irasoc, A., and Luftner, G.: Exploring satellite soil moisture products for irrigation. A case study: Braila County, Romania, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14901, https://doi.org/10.5194/egusphere-egu24-14901, 2024.

EGU24-14960 | Orals | HS6.9

Identifying irrigated areas in the Rhine basin using land surface temperature and hydrological modelling 

Devi Purnamasari, Judith ter Maat, Adriaan Teuling, and Albrecht Weerts

In recent years, the Rhine has experienced summer drought which led to extremely low water availability throughout the basin. Additionally, combination of high temperature and low precipitation may increase irrigation demand, putting even more pressure on water availability. Identifying where irrigation occurs and how it evolves over time offers improved insight water use for sustainable water resources planning and management. However, high-resolution maps of irrigated areas for basin-scale studies on water use are often lacking. Here, as part of the HorizonEurope project STARS4Water, we aim to develop a methodology for identifying irrigated areas in the Rhine basin at a 1 km resolution for the period of 2010-2019. This involves utilizing a combination of the hydrological model wflow_sbm to produce land surface temperature (LSTsim) and thermal observations data (LSTobs) from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. To provide consistent annual irrigation maps, we employed random forest classification model to further identify irrigated areas from the LST difference between LSTsim and LSTobs. In the absence of ground information data, the irrigated maps are evaluated against national agricultural statistics and compared with existing developed irrigated maps. The results can be used to comprehend the interannual variability in the extent and location of irrigated croplands in the Rhine basin and are a start to assess and model agricultural water use in the Rhine basin.

 

How to cite: Purnamasari, D., ter Maat, J., Teuling, A., and Weerts, A.: Identifying irrigated areas in the Rhine basin using land surface temperature and hydrological modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14960, https://doi.org/10.5194/egusphere-egu24-14960, 2024.

EGU24-15215 | Posters on site | HS6.9

SAR imagery and deep learning techniques for reservoir monitoring in Korea 

Wanyub Kim, Doyoung Kim, Yeji Kim, HyunOk Kim, and Minha Choi

Agricultural reservoirs are key structures for water supply on the Korean Peninsula, where the water resources are concentrated seasonally. Monitoring of agricultural reservoirs is essential for efficient management of available water resources. However, in the case of the Korea, there are many unmeasured reservoirs without observation facilities, so it is difficult to monitor available water at a regional scale. Remote sensing-based reservoir monitoring that can observe the water surface in a wide area is essential. In the case of Synthetic Aperture Radar (SAR) image, continuous water body detection is possible regardless of weather conditions. Recently, water body detection research using AI techniques has been actively conducted to improve accuracy. In this study, water body detection was performed on an agricultural reservoir using Sentinel-1 SAR image and AI-based U-net, HR-Net, and Swin-Transformer techniques. The water/non-water binary classification images from the Sentinel-2 satellite were used for validation. In addition, time series validation was performed using in-situ reservoir storage and evaluated the performance of each deep learning techniques. If SAR image with high spatial and temporal resolution can be utilized in the future, it is expected that more efficient management of available water resources will be possible.

Keywords: Sentinel-1, SAR, Deep learning, Water body detection, Reservoir

Acknowlegment: This work was supported by the “Development of Application Technologies and Supporting System for Microsatellite Constellation”project through the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (No. 2021M1A3A4A11032019). This research was supported by the BK21 FOUR (Fostering Outstanding Universities for Research) funded by the Ministry of Education (MOE, Korea) and National Research Foundation of Korea (NRF). This work is financially supported by Korea Ministry of Land, Infrastructure and Transport (MOLIT) as 「Innovative Talent Education Program for Smart City」

How to cite: Kim, W., Kim, D., Kim, Y., Kim, H., and Choi, M.: SAR imagery and deep learning techniques for reservoir monitoring in Korea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15215, https://doi.org/10.5194/egusphere-egu24-15215, 2024.

EGU24-16218 | Orals | HS6.9

Super-resolved Land Surface Temperature for irrigation management  

Lukas Kondmann, Christian Molliére, Julia Gottfriedsen, and Martin Langer

Demographic growth and economic development are putting unprecedented pressure on finite water resources. It is estimated that global water demand will increase by 50% by 2030 resulting in a potentially devastating water shortage [1]. As 70-95% of all water withdrawals are farming-related [2], agriculture plays a key role in this dynamic. 

Inefficient water use in agriculture, often due to the invisibility of crop-specific water requirements, underscores the need for precise irrigation management to optimize water allocation and conservation. Ground sensors and drones can help to tackle this problem but they need to be deployed locally which does not scale. Satellites with instruments in the visible domain such as ESA’s Sentinel-2 reach the necessary spatial resolution but the water needs of crops in the visible spectrum only become apparent once there has been significant damage. Essentially, once a plant is going brown, it is already too late. 

Thermal satellites carry the necessary information to obtain evapotranspiration estimates and observe changes in crop health long before visual signs manifest. Existing thermal missions, however, often do not bring the necessary temporal and spatial resolution for large-scale irrigation management. Recent commercial offerings from the New Space industry, such as OroraTech’s upcoming Forest constellation, are beginning to turn the tide on this. Currently, we have two satellites in orbit with 9 more launches planned this year. With this, we will reach a global sub-daily revisit time for our Land Surface Temperature (LST) product which can serve as a basis for derived evapotranspiration or soil moisture data products, informing smart irrigation management 

At a native resolution of 200m, our LST product faces a trade-off between high temporal and spatial resolution. Exciting breakthroughs in artificial intelligence allow us to artificially enhance the resolution of our product threefold to 70m. With this, we combine the advantages of high spatial and temporal resolution for better irrigation management and crop stress detection. Our super-resolution product is evaluated based on ECOSTRESS data which comes at 70m. First validation comparisons of our super-resolved data with Ecostress look promising and we aim to explore the applicability of our enhanced data for improved irrigation management and related soil & vegetation water content parameters together with the scientific community. 

[1] FAO, 2023. https://www.fao.org/faostories/article/en/c/1185405/#:~:text=Agriculture%20is%20both%20a%20major,water%20there%20is%20no%20exception.

[2] World Economic Forum, 2023. https://www.weforum.org/impact/sustainable-water-management/

How to cite: Kondmann, L., Molliére, C., Gottfriedsen, J., and Langer, M.: Super-resolved Land Surface Temperature for irrigation management , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16218, https://doi.org/10.5194/egusphere-egu24-16218, 2024.

EGU24-17205 | Orals | HS6.9

On the potential of monitoring small water structures with SWOT 

Lionel Zawadzki, Nicolas Gasnier, Roger Fjortoft, Santiago Pena Luque, Damien Desroches, Nicolas Picot, and Thérèse Barroso
Launched in December 2022, the SWOT satellite is a joint mission between NASA, CNES, UKSA, and CSA. It marks a significant breakthrough in the fields of oceanography and hydrology. 
 
Historically, water quantity data derived from satellites relied on a combination of different types of imagery (such as SAR and optical) and nadir altimetry or bathymetry. However, these methods have several limitations, especially when it comes to accurately observing hydrology features without relying on data from Very-High Resolution commercial satellites. 
As an example, Sentinel-2 imagery can detect water in optical images down to 10x10 m2 pixels [Pena-Luque et al, 2021]. As a result, Sentinel-2-derived land-water masks over rivers that are less than 20-m-wide often contain significant gaps. On the other hand, SAR imagery from Sentinel-1 can detect water surfaces larger than its 22 m resolution, but it's challenging to differentiate water from wet areas and roads [Pena-Luque et al, 2021]. Neither of these sensors can retrieve the water elevation. In contrast, conventional  altimetry has limited spatial coverage and is generally considered difficult to use in obtaining accurate water surface elevations in rivers less than 100-m wide [Calmant et al, 2006, 2008, 2016]. However, recent algorithmic advances [Boy et al, 2021, Egido et al, 2016], on the latest generation of nadir sensors (Delay Doppler Altimeters or SAR-altimeters) onboard Sentinel-3 and Sentinel-6 satellites showed that one can retrieve accurate water levels over small freshwater reservoirs. 
 
SWOT observations offer a novel approach to retrieve water quantity data from space. It operates using a near-nadir Ka-band SAR Altimeter based on interferometry to measure the elevation of water pixels with a sampling of 10-60x22 m2. Although its revisit  time is limited to at least twice per 21-day nominal cycle up to 78° latitude and its spatial resolution restricts its applicability for operational water management in irrigation and freshwater storage systems, SWOT presents new opportunities for understanding water management at the basin level. It can be used in combination with high-resolution imagery and real-time in situ measurements, and integrated into hydrological models for more effective water management.
Although the official mission specification designed SWOT for the retrieval of water surface elevation of 100-m wide rivers with 10-cm accuracy over 10-km reaches, a study by Gasnier et al, 2021, showed the potential of SWOT to observe narrow rivers. The first actual observations provided by SWOT in 2023 are publicly available on hydroweb.next and PO.DAAC websites. These confirm its potential to observe small hydrological targets well beyond the mission requirements.
In this study, we will present early results on human-made irrigation and freshwater storage systems, and discuss the current possibilities and limitations of SWOT satellite.

How to cite: Zawadzki, L., Gasnier, N., Fjortoft, R., Pena Luque, S., Desroches, D., Picot, N., and Barroso, T.: On the potential of monitoring small water structures with SWOT, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17205, https://doi.org/10.5194/egusphere-egu24-17205, 2024.

EGU24-17492 | Posters on site | HS6.9

WSN-Based Irrigation Scheduling Model for Sugarcane Crops 

Yogesh Kushwaha, Rajib Panigrahi, and Ashish Pandey

The critical demand for freshwater resources worldwide necessitates their efficient utilization.  The agricultural sector is one of the major consumers of fresh water. However, in traditional irrigation techniques, about 60% of the water is wasted, resulting in low water use irrigation efficiency. Practical sensor-based methods are desperately needed to determine the soil water status for adequate irrigation scheduling. Using cutting-edge solutions to improve irrigation management is essential to water resource conservation. Wireless sensor networks (WSN) are an innovative technology advancing agriculture toward greater efficacy and sustainability. This research focused on developing a WSN-based irrigation system to minimize water losses under actual field conditions. The designed system was integrated with Fr4 capacitive-based soil moisture and DS18B20 soil temperature sensors, specifically evaluated for managing irrigation in loamy soil for sugarcane cultivation. The sensors were strategically installed at depths of 15 cm, 30 cm, and 45 cm below the surface of the soil. Throughout the crop's growth season, these sensors continuously measure the soil parameters (soil moisture content, soil temperature) and wirelessly transfer them to a cloud server through the ZigBee protocol to facilitate remote accessibility. The data was easily accessible online via a web service. An analytical approach utilizing a weighted average method was employed to interpret the soil moisture data collected from the three depths. This technique accurately depicted the soil water condition in the crop's root zone.

Furthermore, by setting a threshold according to the sensor's soil water content, the system may precisely initiate irrigation operations when needed. Overall, the WSN-based irrigation management system aims to improve productivity, reduce water waste, and increase the overall sustainability of agricultural operations. The efficacy of the developed system was field validated in terms of cost, efficiency, and ease of replicating before being delivered for societal use. With cloud-based data analysis and monitoring, users/farmers can access the irrigation system from anywhere and monitor it online. The experimental findings indicate that this irrigation management system utilize less water along with high water use efficiency.

 

Keywords: Wireless Sensor Network (WSN); Soil Moisture Sensors; Irrigation Scheduling.

How to cite: Kushwaha, Y., Panigrahi, R., and Pandey, A.: WSN-Based Irrigation Scheduling Model for Sugarcane Crops, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17492, https://doi.org/10.5194/egusphere-egu24-17492, 2024.

In water-scarce regions, effective water resource management is crucial for sustainable agriculture. Scientists and decision-makers are working to address issues of resource conservation and agricultural productivity, with a growing interest in coupling hydrological and crop models. The current trend of interest seems to be limited to the improvement of crop system performance and environmental impact assessment, but attention also needs to be paid to sustainable crop production and water management concerns. Driven by these needs, in the framework of I4DP-SCIENCE program, the Italian Space Agency (ASI) supports the ambitious collaborative project THETIS (Earth Observation for the Early forecasT of Irrigation needS; Agreement n. 2023-52-HH.0), involving the National Research Council – Institute for Electromagnetic Sensing of the Environment (CNR-IREA), the Council for Agricultural Research and Economics (CREA), the Polytechnic of Bari, the University of Bari, and the Reclamation Consortium of the Capitanata, Foggia, Italy. The project focuses on the early assessment and forecasting of irrigation needs in the “Fortore” irrigation district in the Apulian Tavoliere (Southern Italy).

THETIS aims to develop a Spatial Decision Support System (SDSS) integrating hydrologic and crop growth models with advanced Earth Observation (EO) products, Artificial Intelligence (AI) and a WEBGIS interface to provide basin-scale information for the efficient planning of irrigation resources for three different use cases (i.e., early forecasting, irrigation start and mid-season estimation) for different target crops.

The project architecture significantly relies on the use of EO derived products obtained through the integrated use of Synthetic Aperture Radar (SAR), multispectral and hyperspectral data. They serve the purpose of describing land surface processes and represent crucial parameters for hydrological and crop growth model constraints.

Specifically, the calibration of the hydrological model spans from summer 2021 to autumn 2022. The subsequent phase will include a validation phase (year 2023) and an operational phase to estimate water use for the upcoming irrigation season. The validation of the model outputs includes the comparison of the estimated water demand with the actual irrigation volumes applied by the Consortium.

A primary focus of the proposed architecture lies in generating time-series estimates of root zone soil moisture, essential for defining the initial conditions in the crop growth model AquaCrop which plays a pivotal role in managing the water balance at the field scale in the areas relevant to irrigation needs assessment. To achieve this goal, the project aims to integrate, for the first time, a revised version of the well-known daily basin-scale hydrological model DREAM with the physically based Soil Moisture Accounting and Routing (SMAR) model.

This work concerns data selection and assessment for calibration and validation phases of the basin-scale hydrological model and the SMAR model. They include sparse daily field measurements and satellite data retrievals. Although field monitoring remains essential, preliminary results regarding the use of satellite-derived and downscaled products for a proper model calibration are encouraging. The proposed approach shows promise for providing insights into soil dynamics for operational implementation, supporting advances in sustainable agricultural techniques and rational water resource management in semi-arid environments.

How to cite: Iacobellis, V. and the THETIS: Advancing Water Management in Water-Scarce Regions: A Collaborative Approach for Early Assessment of Irrigation Needs in the Capitanata Consortium (Apulia region). , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18407, https://doi.org/10.5194/egusphere-egu24-18407, 2024.

EGU24-18745 | ECS | Orals | HS6.9

Irrigation Estimation from Soil Water Balance and the Water Cloud Model by leveraging Sentinel-1 and Sentinel-2 observations 

Martina Natali, Sara Modanesi, Domenico De Santis, Luca Brocca, Fabio Mantovani, Andrea Maino, Gabrielle De Lannoy, and Christian Massari

Irrigation plays a pivotal role in the hydrological cycle, representing about 70% of freshwater withdrawals. However, its representation in Earth System models is characterized by significant uncertainties in terms of amount, timing and spatial distribution. Earth Observation data offer a viable way to reduce this uncertainty thanks to their ability to sense the soil and vegetation in its real condition with few-days revisit timing and high spatial resolution (~ 10 m), e.g. with the new Sentinel missions. 

In this contribution, we use remote sensing observations from the Sentinel-1 and Sentinel-2 satellite missions to constrain a simple Soil Water Balance (SWB) model coupled with the semi-empirical Water Cloud Model (WCM) and obtain irrigation estimates via an inverse modelling solution. The WCM, which is a model simulating backscatter observations (σ0) from soil moisture and a vegetation descriptor, is forced by vegetation indexes from Sentinel-2 data and soil moisture simulated by the SWB that includes a sprinkler irrigation scheme. The model outputs are then matched with Sentinel-1 observations to obtain irrigation estimates.

The model is tested over an irrigated field of the Po River valley, one of the most intensively European irrigated areas. Results show that the model can capture the irrigation signal with relatively good accuracy. It also provides an estimate of soil moisture in the field.  Nonetheless the revisit time of the satellite platforms and the simplicity of backscatter model, especially in the representation of the vegetation component, constitute two main limitations of the model. This model is a viable tool that can be easily applied in the context of precision agriculture to optimize irrigation practices and conserve water resources even when in-situ soil moisture and irrigation measurements are not available.

How to cite: Natali, M., Modanesi, S., De Santis, D., Brocca, L., Mantovani, F., Maino, A., De Lannoy, G., and Massari, C.: Irrigation Estimation from Soil Water Balance and the Water Cloud Model by leveraging Sentinel-1 and Sentinel-2 observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18745, https://doi.org/10.5194/egusphere-egu24-18745, 2024.

EGU24-19723 | ECS | Posters on site | HS6.9

Influence of irrigation on soil moisture and evaporation based on Sentinel 1 backscatter observations and an evaporation retrieval model 

Baris Oztas, Oscar Baez Villanueva, Irina Yu. Petrova, Olivier Bonte, Jacopo Dari, Bernhard Raml, Mariette Vreugdenhil, Wolfgang Wagner, and Diego Miralles

Irrigation stands out as a primary driver influencing water dynamics over agricultural regions. Its estimation in time and space is complex, and satellite observations are only indirectly related to irrigation. Conveniently, Sentinel 1 SAR observations are sensitive soil moisture dynamics and irrigation, and can be used to estimate these dynamics at high resolution. The influence of irrigation on transpiration is however even more complicated to unravel from space observations. Current evaporation retrieval models are not designed to represent the influence of irrigation. However, the current availability of Sentinel 1 observations represents an opportunity to fill this gap.
In this presentation, the Global Land Evaporation Amsterdam Model (GLEAM) will be adapted to assimilate Sentinel 1 backscatter, using the Ebro river basin in Spain as a study case. While GLEAM's coarse resolution has to date hindered its application in the context of agricultural management, recent efforts during the Digital Twin Earth ESA initiative have yielded a GLEAM version at 1km resolution over the Mediterranean region that will be used in the context of this study. Here, we aim to leverage the high-resolution (1-km) GLEAM and explore its coupling to the Water Cloud Model to enable the forward data assimilation of Sentinel 1 backscatter. Several data assimilation techniques, such as Ensemble Kalman Filter, will be applied, seeking to find a method to estimate evaporation and soil moisture in irrigated land that can be transferable to basins where irrigation volumes are not available.

How to cite: Oztas, B., Villanueva, O. B., Petrova, I. Yu., Bonte, O., Dari, J., Raml, B., Vreugdenhil, M., Wagner, W., and Miralles, D.: Influence of irrigation on soil moisture and evaporation based on Sentinel 1 backscatter observations and an evaporation retrieval model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19723, https://doi.org/10.5194/egusphere-egu24-19723, 2024.

EGU24-20015 | Posters on site | HS6.9

Evaluation of Crop Water Stress Using Drone Images and Numerical Weather Prediction Model Data 

Jae-Hyun Ryu, Hoyong Ahn, and Kyung-Do Lee

Water conditions in soil are measured with soil moisture sensors such as tensiometer and time-domain reflectometry.  However, installed soil moisture sensors may not fully represent the entire cultivation area due to factors such as topography, meteorological conditions, and irrigation systems.The purpose in this study is to identify spatial variations of crop growth and moisture conditions using drone images and weather data. The drone, equipped with multi-spectral, hyper-spectral, and infrared cameras, captured images, and precipitation information up to 3 days later was automatically collected from numerical weather prediction model. Thermal images of crops and soil responded immediately depending on the presence or absence of irrigation. In irrigated crops, leaf temperature decreased due to transpiration. The hyper-spectral images, including short-wave infrared wavelengths, proved sensitive to soil water conditions. However, reflectance-based water indices showed no immediate differences for crops unless soil moisture fell below the wilting point. There was a difference in crop growth depending on the level of irrigation, which was clearly revealed in the vegetation index. Crop growth was poor in areas where irrigation was low. When soil moisture sensor values decrease and no rainfall is expected in the near future, drone images can be utilized to identify specific areas experiencing crop moisture stress. This suggests the potential for drones to support irrigation decision-making.

Acknowledgments: This research was funded by the Rural Development Administration, grant number RS-2022-RD009999.

How to cite: Ryu, J.-H., Ahn, H., and Lee, K.-D.: Evaluation of Crop Water Stress Using Drone Images and Numerical Weather Prediction Model Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20015, https://doi.org/10.5194/egusphere-egu24-20015, 2024.

EGU24-21860 | ECS | Posters on site | HS6.9

Satellite-based energy models to estimate crop yield. An automatic approach at the regional scale 

Davide Gabrieli, Chiara Corbari, Francesco Pirotti, Samuele Trestini, Pietro Teatini, and Francesco Morari

The recent climate dynamics characterized by unpredictability and a series of extreme events pose challenges to society at various levels, particularly threatening agricultural production. The development of increasingly sophisticated models and computers combined with remote sensing techniques can serve as a means to safeguard the agricultural domain.

The aim of this work is to develop a computational tool, named CROPORBIT, designed to operate at a regional scale for estimating crop yield. The capabilities of this tool have a significant positive impact on water management, crop health monitoring, and quantifying damage from extreme meteorological events, such as high temperatures.

CROPORBIT combined the radiative model METRIC with a Photosynthetically Active Radiation-based model. Essential inputs for the tool include Landsat 8 and 9 satellite imagery and daily meteorological data retrieved from the regional network stations.

The tool performs a multi-temporal analysis of crop growth, involving the interpolation of ET, stress coefficient, and dry biomass accumulation maps, which are then transformed into crop yield maps by applying a harvest index coefficient.

CROPORBIT underwent validation in a series of soybean and corn fields situated in the low-lying plain of the Veneto Region, where crop yield maps were recorded by combine harvesters.

The preliminary results have shown that CROPORBIT can predict the average crop yield with a good approximation while it was less performing in capturing the field yield variability. The main issues have proven to be the scarcity of clear-sky conditions imagery and the estimation of the harvest index variability.

This research establishes the foundation for future investigations, emphasizing the need for improvements in spatial and time resolution. Enhancements in these aspects may lead to improved outcomes in terms of both accuracy and spatial variability.

How to cite: Gabrieli, D., Corbari, C., Pirotti, F., Trestini, S., Teatini, P., and Morari, F.: Satellite-based energy models to estimate crop yield. An automatic approach at the regional scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21860, https://doi.org/10.5194/egusphere-egu24-21860, 2024.

SSS11 – Material and Methods in Soil Sciences

EGU24-579 | ECS | Posters on site | AS2.4

Meteorological and Soil Moisture Measurements in Mount Kenya Region at Various Scales 

Peter K. Musyimi, Balázs Székely, Hellen W. Kamiri, Tom Ouna, and Tamás Weidinger

The optimal solution for solving many uncertainties associated with weather and climate data is accurate field measurement. This enhances various climate services that can be offered to different sectoral case studies and solve societal weather-related challenges by ensuring the obstacles are overcome amicably, for instance, climate adaptation barriers in the face of climate variability. The main goal of our study was to make long-term meteorological measurements in Mount Kenya region rainforest biome at an elevation of 1998 m above sea level (Karatina University weather station) and 3055 m above sea level (Mount Kenya field station) used at various scales from 2022. We are using Temperature-Moisture-Sensor (TMS) burial (1 m) and TMS Long (45 cm) soil sensors as well as temperature/relative humidity data loggers. These devices provide us with crucial data and reshape field measurement campaigns in data-scarce regions of Kenya. The soil moisture sensors also measure soil temperature, surface, and air temperature. The soil moisture data and temperature at various scales is acquired at an interval of 10 minutes while the data logger records data at an interval of 30 minutes.  Another key goal was to acquire soil moisture data at tropical rainforest biome which is scarce as well as relative humidity and temperature. The objectives of the study are to analyze reference evapotranspiration and estimation of real evapotranspiration in humid Mount Kenya climatic region, Nyeri County; compare climate parameters in two different elevations; to understand microclimatic changes associated with varying elevations and ensure data quality control in analysis by checking uncertainties and sensitivities associated with ERA5 reanalysis, synoptic (GFS/ECMWF) and station datasets. Therefore, to narrow the gap between missing data, uncertainties, and quality control of data, meteorological field measurements cannot be misconstrued.

Keywords: data loggers, field measurement, soil moisture, quality control, Kenya,

How to cite: Musyimi, P. K., Székely, B., Kamiri, H. W., Ouna, T., and Weidinger, T.: Meteorological and Soil Moisture Measurements in Mount Kenya Region at Various Scales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-579, https://doi.org/10.5194/egusphere-egu24-579, 2024.

The impact of increasing CO2 on global temperature and strengthening of the greenhouse effect makes the measurements of gas exchange between the Earth’s surface and the atmosphere particularly important. Observational data on greenhouse gases exchange between different types of ecosystem and the atmosphere are crucial in thorough understanding the global climate mechanisms. Fruit tree ecosystems constitute an important kind of land use in Central Europe and apple is very extensively cultivated fruit tree crop in the world. Because intensively used apple orchards have a potential for carbon (C) sequestration and to be an important sink of atmospheric CO2 the continuous measurements of processes of ecosystem-atmosphere exchange are necessary for properly determining of global carbon (C) budget.

This work presents the results of continuous closed-path EC measurements of carbon dioxide (CO2) fluxes in the apple orchard located near Grójec in the Masovian voivodeship on the largest orchard area in Poland. These are the results of the first and the only measurements of the net CO2 fluxes (started in February 2023) carried out in the apple orchard ecosystem in Poland. The main goal of the work is to present variations of CO2 flux at different time scales at different stages of fruit tree growth and during different climatic conditions. The turbulent fluxes of CO2 were calculated on a 30-min basis. The raw data were computed using the EddyPro -7.0.9 software taking into account the necessary corrections and procedures to correct the obtained results. CO2 fluxes were characterized by clear daily variability with negative values during the day (CO2 uptake in the photosynthesis process) and positive at night (CO2 release in plants respiration processes). The most intensive CO2 absorption took place between May and September (phases of flowering and fruit development and ripening) the with a maximum in June. Negative 30 min mean CO2 flux value reached for this month was around 12 µmol ּ m-2 ּ s-1 around noon. In the remaining months the CO2 absorption processes were lower and ranged around a few µmol ּ m-2 ּ s-1

How to cite: Pawlak, I. and Kleniewska, M.: Variability of turbulent carbon dioxide flux netto at different time scales in an apple orchard ecosystem in Central Poland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-592, https://doi.org/10.5194/egusphere-egu24-592, 2024.

EGU24-956 | ECS | Posters on site | AS2.4

Fluxible: an R package to calculate ecosystem gas fluxes in a reproducible and automated workflow. 

Joseph Gaudard, Richard Telford, Vigdis Vandvik, and Aud Helen Halbritter

Measurements of gas fluxes are widely used when assessing the impact of global-change drivers on key aspects of ecosystem dynamics, especially carbon. It shows whether an ecosystem is a source or a sink of atmospheric carbon, and how the storage dynamics could change in the future. Ecosystem gas fluxes are typically calculated from field-measured gas concentrations over time, using a linear or exponential model and manually selecting good quality data. This approach is highly time consuming and prone to potential bias that might be amplified in further steps, as well as having major reproducibility issues. The lack of a reproducible and bias-free approach creates challenges when combining global-change studies to make biome and landscape scale comparisons.

The Fluxible R package aims to fill this critical gap by providing a workflow that removes individual evaluation of each flux, reducing risk of bias, and making it reproducible. Users set specific data quality standards and selection parameters as function arguments that are applied to the entire dataset. The package runs the calculations automatically, without prompting the user to take decisions mid-way, and provides quality flags and graphs at the end of the process for a visual check. This makes it easier to use with large flux datasets and to integrate into a reproducible workflow. Using the Fluxible R package makes the workflow reproducible, increases compatibility across studies, and is more time efficient.

How to cite: Gaudard, J., Telford, R., Vandvik, V., and Halbritter, A. H.: Fluxible: an R package to calculate ecosystem gas fluxes in a reproducible and automated workflow., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-956, https://doi.org/10.5194/egusphere-egu24-956, 2024.

EGU24-1084 | ECS | Orals | AS2.4

Analysis of fog occurrence changes in the Namib Desert across time and space and impacts on natural and artificial fog collection 

Eleonora Forzini, Giulio Castelli, Aida Cuni-Sanchez, and Elena Bresci

In the Namib Desert, along the South-Western African coast, fog represents the main water input for local flora and fauna. During the last years, changes in the timing of fog occurrence and in the quantity of water that can be harvested from it, have been observed in several areas of the world, including the Namib Desert. A deeper insight into fog presence and fog water yield changes can help to understand to what extent Namib Desert’s ecosystem is being and will be affected in future by climate change. This information can also contribute to local environmental protection and carbon dioxide sequestration strategies, as fog water can be used for reforestation and land restoration. An 8-year-long dataset of harvested fog water rates recorded daily in 13 ground stations along the Namib Desert was statistically analysed to inspect advection fog occurrence evolution. The results show a noticeable intra-annual and inter-annual variability in rates and seasonality of harvested fog water. On the other hand, observed trends in collected fog water time series are generally decreasing, but longer time series are required to confirm the trend since El Niño Southern Oscillation (ENSO) phenomenon presence in the analysed period might have had an impact. The main hypothesis is that changes in fog occurrence and its characteristics are due to climate modifications, given that no extensive human activities are present in the area. However, further analyses on fog-related climatic and meteorological factors, possibly including remote sensing or reanalysis datasets aiming to increase the available data timespan, are envisioned to understand to what extent fog collection in the Namib Desert will be affected in future by climate change.

How to cite: Forzini, E., Castelli, G., Cuni-Sanchez, A., and Bresci, E.: Analysis of fog occurrence changes in the Namib Desert across time and space and impacts on natural and artificial fog collection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1084, https://doi.org/10.5194/egusphere-egu24-1084, 2024.

The observed surface wind speed (SWS) over China has declined in the past four decades, and recently, the trend has reversed, which is known as SWS stilling and recovery. The observed SWS is vulnerable to changes in nonclimatic factors, i.e., inhomogeneity. Unfortunately, most of the existing studies on the long-term trend of SWS were based on raw datasets without homogenization. In this study, by means of geostrophic wind speed and penalized maximal T test, we conduct a systematic homogeneity test and exploration of the homogenization impact for SWS at over 2,000 stations in China from 1970 to 2017. The results show that the inhomogeneity in the observed SWS over China is detectable at 59% of national weather stations. The breakpoint years are mainly concentrated in the late 1970s, mid-1990s and early 2000s. Overall, 18% of breakpoints are caused by station relocations, and the remaining breakpoints are likely related to anemometer replacement and measurement environment changes that occurred during the mid-1990s and early 2000s. After homogenization, the decreasing trend in SWS during 1970-2017 decreased from -0.15 m/s decade-1 to -0.05 m/s decade-1. The homogenized SWS recovery period advanced from the early 21st century to the early 1990s, which is consistent with the SWS variations, excluding the impact of urbanization around weather stations. The phase change in the Western Hemisphere warm pool (WHWP) might be one of the causes of homogenized SWS recovery.

How to cite: Zhang, Z.: Homogenization of observed surface wind speed based on geostrophic wind theory over China from 1970 to 2017, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1358, https://doi.org/10.5194/egusphere-egu24-1358, 2024.

EGU24-2642 | Posters on site | AS2.4

Can dry get wetter even if rainfall declines? 

Nurit Agam and Dilia Kool

Drylands are 57% of the terrestrial area of the world, and are disproportionally affected by climate change. This is particularly pertinent in so-called “climate-change hotspots” such as the Mediterranean, where temperature increases at a rate of up to 0.45 oC/decade and precipitation is expected to decline. Given the sparsity of studies in drylands and the consequent lack of understanding of the unique processes in drylands, the degree to which these projections are accurate for drylands is questionable. The fact that drylands, by definition, are classified according to the aridity index, exposes the inherent assumption that desert hydrology is primarily governed by precipitation and potential evapotranspiration (ET0). There is increasing evidence, however, that non-rainfall water inputs (NRWIs; fog, dew, and water vapor adsorption) are a substantial source of water in multiple desert environments. In arid and hyper-arid drylands, water vapor adsorption is not only the least studied of the three NRWIs, but also likely the most common. In the Negev desert, Israel, the projected decrease in rainfall and increase in temperature, and therefore increase in ET0, is expected to result in drier soils. This potentially will increase the amount of water vapor adsorption. Here we present the actual rate of warming and the corresponding changes in ET0 in the Negev desert. We then elucidate, for the first time, the contribution of water vapor adsorption to desert hydrology and how it might be affected by climate change based on changes observed in the last 20 years.

How to cite: Agam, N. and Kool, D.: Can dry get wetter even if rainfall declines?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2642, https://doi.org/10.5194/egusphere-egu24-2642, 2024.

EGU24-3967 | Orals | AS2.4

Impact of Subsurface Thermal Anomalies on Air Temperatures in Idealized Scenarios Using PALM-4U 

Patricia Glocke, Christopher C. Holst, Basit A. Khan, and Susanne A. Benz

The impact of underground heat (or cold) sources such as man-made infrastructures or geothermal systems have been extensively studied in geosciences. Soil temperatures near underground parking garages may be up to 10 K warmer than their surroundings. However, the coupling between these temperature anomalies in the soil and the atmosphere as a bottom-up scheme has been neglected so far. We investigated how this scenario can be modeled in the turbulence and building resolving large eddy simulation urban climate model PALM-4U and assessed the impact of modified soil temperatures on air temperatures in an idealized domain. Hereby, the soil temperatures at 2-meter depth were increased and decreased by 5 K, respectively. Multiple scenarios were considered, differentiating between cyclic and Dirichlet/radiation boundary conditions along the x-axis. Further, we ran the simulations under summer and winter conditions, day and night, and three land cover types which are bare soil, short grass, and tall grass. After three days of simulation time, cyclic boundary conditions induced air temperature anomalies due to changes in the subsurface temperature. However, Dirichlet/radiation boundary conditions did not show alterations. Analyzing the cyclic scenarios, although the absolute air temperature was significantly influenced by the landcover, the magnitude of the air temperature anomaly shows little variation. Daytime and seasonality exerted a greater influence on the magnitude. The greatest positive near-surface air temperature anomaly when increasing the soil temperature was 0.38 K for all land cover types and develops during winter between 09:00 and 10:00 CET. Smallest influence was found during summer at 09:00 CET, where increased soil temperatures resulted in a 0.02 K rise over short- and tall grass, and 0.18 K over bare soil. Conversely, decreasing soil temperatures showed predominantly inverse patterns.

The findings contribute to the general comprehension of the coupling of soil- and atmospheric temperatures, inferring also insights of simulating idealized but reality-oriented scenarios in PALM-4U.

How to cite: Glocke, P., Holst, C. C., Khan, B. A., and Benz, S. A.: Impact of Subsurface Thermal Anomalies on Air Temperatures in Idealized Scenarios Using PALM-4U, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3967, https://doi.org/10.5194/egusphere-egu24-3967, 2024.

EGU24-5207 | Posters on site | AS2.4

Eddy Covariance (EC) measurements in a restored floodplain area at the Morava River in Austria within the EU funded REWET project 

Anna Lindenberger, Magdalena von der Thannen, and Hans Peter Rauch

Although occupying only 7% of the earth's surface, wetlands store 33% of the world's terrestrial carbon. When these ecosystems are drained to be converted into agricultural, forestry or mining exploitations, they release greenhouse gases contributing to climate change. While bringing together 18 partners from 9 countries, the REWET (REstoration of WETlands to minimise emissions and maximise carbon uptake – a strategy for long term climate mitigation) project focuses on determining how the restoration and management of wetlands can be optimised to maximise their carbon uptake while in balance with type-specific natural processes and biodiversity.

The REWET project draws upon a network of seven Open Labs (OLs) located in different geographical areas of Europe and covers different types of terrestrial wetlands: freshwater wetlands, peatlands and floodplains. The heterogeneity of the Open labs allows the application of different restoration methodologies while following the same monitoring plan to provide replicable knowledge.

This paper presents the measurements and the first result of the OL in Austria within the REWET project. The site is a restored and now protected floodplain area at the Morava River. EC measurements are used to calculate the CO2 and CH4 fluxes and the seasonal as well as annual carbon balance of the ecosystem. Furthermore, the effect of floodplain water levels and grazing in this area is investigated. The EC instruments have been set up on a floating platform to allow measurements also during flood events, when understudied, critical transition of GHG fluxes may occur. The CO2/H2O analyser started collecting the first data in the middle of October 2023 whereas the CH4 analyser was added in end of December 2023. Since the CO2 analyser was put on site first flood events occurred end of December, which is the first data to be processed and analysed. Additional to the results the challenges in setting up an EC tower in a floodplain area will be presented.

 

 

 

Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or CINEA. Neither the European Union nor the granting authority can be held responsible for them.

How to cite: Lindenberger, A., von der Thannen, M., and Rauch, H. P.: Eddy Covariance (EC) measurements in a restored floodplain area at the Morava River in Austria within the EU funded REWET project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5207, https://doi.org/10.5194/egusphere-egu24-5207, 2024.

EGU24-5340 | ECS | Posters on site | AS2.4

Uncertainty of eddy covariance-derived net ecosystem CO2 exchange over a mountain forest reduced by multiple nighttime filtering approaches 

Alexander Platter, Katharina Scholz, Albin Hammerle, Mathias W. Rotach, and Georg Wohlfahrt

The assessment of net ecosystem CO2 exchange often relies on eddy covariance systems. However, this method overlooks CO2 advection, even if it is often non-negligible. This is especially the case under stable, low-turbulence nighttime conditions. Hence, there is a need to filter nighttime eddy covariance data for periods when advection can be expected to be non-negligible. This study evaluates both well-established and novel filtering methods at a mountain forest site in Tyrol, Austria (Forest-Atmosphere-Interaction-Research (FAIR) site, AT-Mmg). Established methods, including friction velocity (u*) filtering, its counterpart using the standard deviation of vertical velocity  fluctuations (σw) and an after-sunset flux maxima approach (commonly referred to as van Gorsel method) are applied. Additionally we use a more recent approach with a physically-derived measure of flow decoupling for filtering. With this method also stability information is taken into account, not only a turbulence scale, as in the commonly used u* filtering. As often seen in literature, the uncorrected CO2 flux underestimates the nighttime respiration, as it appears for all the filtering methods. Despite being based on widely differing assumptions, the various filtering approaches yielded relatively similar carbon budget estimates over 14 months of measurements (-252 to -290 g C/m2). in contrast to the uncorrected budget of -521 g C/m2.

Furthermore, we introduce a novel K-means clustering approach that groups flow situations into clusters based on vertical profiles of temperature, σw and wind speed. These clusters need then to be evaluated to determine whether they represent a flow situation in which CO2 advection is expected to be irrelevant. Such scenarios are often Foehn periods or early-night situations with high turbulence and low stability. This approach is relatively straightforward to implement, works with an unlimited number of input variables and has the advantage that the identified periods are easy to interpret. This method results in a 14-month budget of -232 g C/m2 for our study site. 

The universality of the clustering method allows not only for an unlimited number of input variables, it can be also easily extended for the entire day. There is no a priori reason not to filter eddy covariance data during the daytime when low-turbulence situations with persistent in-canopy flows may lead to non-negligible advection, especially in complex terrain. We made an attempt of daytime filtering in this study with the clustering method, but also with some adapted versions of the benchmark methods. All of these daytime filtering methods suggest that there is an underestimation of the CO2 uptake in the morning for the uncorrected measurements. Filtering for both nighttime and daytime leads to a range of 14-month budgets of -451 to -359 g C/m².

Further analysis, incorporating different established sites, direct advection measurements or numerical simulations, could be used in future to explore the full potential of the novel clustering approach, especially with its application to daytime flux data.

How to cite: Platter, A., Scholz, K., Hammerle, A., Rotach, M. W., and Wohlfahrt, G.: Uncertainty of eddy covariance-derived net ecosystem CO2 exchange over a mountain forest reduced by multiple nighttime filtering approaches, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5340, https://doi.org/10.5194/egusphere-egu24-5340, 2024.

EGU24-5597 | ECS | Orals | AS2.4

Investigating forest management's impact on local climate in Fennoscandia through statistical and dynamical modeling 

Bo Huang, Yan Li, Xia Zhang, Chunping Tan, Xiangping Hu, and Francesco Cherubini

The forest plays a crucial role in the land ecosystem, impacting local climates through various biophysical mechanisms. While numerous observational and modeling studies have explored the distinctions between forested and non-forested areas, the impact of forest management on surface temperature has been relatively understudied. This limited attention is attributed to the inherent challenges associated with adapting climate models to effectively account for the complexities of forest structure parameters. Employing a combination of machine learning-based statistical analysis and a regional climate model, along with high-resolution maps detailing various forest compositions and structures, we explore the connection between specific forest management strategies and local temperature variations. The findings reveal a tendency for more developed forests to contribute to higher land surface temperatures compared to younger or less developed ones. Relative to the present state of Fennoscandian forests, an ideal scenario with fully developed forests is found to an annual mean warming of 0.26 ℃ in statistical models, with a range of 0.03 to 0.69 ℃ (5th to 95th percentile). However, the dynamical model indicates an annual average cooling effect of -0.25 °C, ranging from -0.42 to -0.10 °C (5th to 95th percentiles), attributing this difference to the dynamical model's inability to accurately simulate winter warming. Both models project a cooling effect in summer, with statistical and dynamical models showing -0.03 ± 0.22 ℃ and -0.53 ± 0.20 ℃, respectively. Conversely, scenarios involving undeveloped forests result in an annual average cooling of -0.29 ℃ in statistical models, with a range of -0.61 to -0.01 ℃, a slight summer warming of 0.03 ± 0.16 ℃, and a winter cooling of -0.69 ± 0.47 ℃. The dynamical model, however, predicts an annual average warming of 0.28 ± 0.18 °C, a summer warming of 0.53 ± 0.15 °C (mainly driven by increased sensible heat fluxes), and a winter cooling of -0.29 ± 0.25 °C. This study deepens our understanding of how alterations in vegetation impact climate patterns. While our findings shed light on the intricate connections between forest composition and surface temperatures, there's a clear need to refine how regional climate models capture the intricate biophysical mechanisms within forest dynamics. Enhancements in this representation will be crucial for establishing a comprehensive understanding of how forest management practices specifically influence local climate regulation services.

How to cite: Huang, B., Li, Y., Zhang, X., Tan, C., Hu, X., and Cherubini, F.: Investigating forest management's impact on local climate in Fennoscandia through statistical and dynamical modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5597, https://doi.org/10.5194/egusphere-egu24-5597, 2024.

EGU24-6114 | Orals | AS2.4

Reflect sunlight or use it to store carbon? 

Alexander Graf, Georg Wohlfahrt, Ankur Desai, and the FLUXNET ALBEDO team

In considerations about land management and global climate, biophysical effects like those of albedo are known to modify biochemical effects of greenhouse gas release or uptake. In particular, the cooling effect of afforestation via creation of carbon sinks has been shown to be partly offset by the low albedo and snow-masking effect of tree canopies.

In this presentation, we give a global overview on the relationship between albedo and CO2 uptake (net ecosystem productivity NEP and net biome productivity NBP). We focus on a recent study (Graf et al. 2023, https://doi.org/10.1038/s43247-023-00958-4) and the questions:

(i) Do ecosystems sequestering more CO2 have a lower albedo as a rule?

(ii) How close would such a relation be and how much room does it leave for climate-smart land use?

(iii) Given the different immediacy of albedo and NBP based radiative forcing, are there different mitigation policies to be preferred at different points in time?

To empirically investigate these questions with direct in-situ measurements, we identified 176 FLUXNET stations with sufficient coverage of NEP, incoming and outgoing shortwave radiation and ancillary data. A method to fill gaps in outgoing shortwave radiation and identify snow cover periods was developed and validated against available data and PI-provided snow statistics. 

We found a hyperbola-like decrease in maximum achievable effective (flux-weighted) long-term albedo as NEP increases, and vice versa. Apart from this joint limit, which also applied to non-forest and snow-free sites, the relation scattered strongly, indicating some room for climate-smart land use considering both albedo and carbon sequestration.

A conceptual model based on a paired-site permutation approach showed that maximizing each site’s NEP without considering albedo, leads to albedo-based positive radiative forcing (warming) during the first approximately 20 years, before being offset by an even stronger NBP-based cooling. However, the fact that most sites are currently far below their possible maximum albedo-NEP combination also allows for a balanced scenario in which both parameters are improved simultaneously. It avoids warming on all timescales, but provides less cooling than pure NEP maximization in the long term. We discuss how these timelines would interact with current emission reduction policies, the reasons underlying the relationship and real-world examples of joint NEP and albedo change.

How to cite: Graf, A., Wohlfahrt, G., Desai, A., and team, T. F. A.: Reflect sunlight or use it to store carbon?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6114, https://doi.org/10.5194/egusphere-egu24-6114, 2024.

EGU24-6150 | ECS | Posters on site | AS2.4

Investigation of the Vertical Geometry of Low Level Clouds in the Namib Desert 

Deepanshu Malik, Hendrik Andersen, and Jan Cermak

This study comprehensively investigates the vertical geometry of low-level clouds in the Namib desert. Using ceilometer measurements and meteorological station observations, a precise determination of cloud-base height and the separation of low-level stratus and fog is performed.
The Namib Desert, known for hyper-arid conditions and frequent cloudiness, presents an intriguing environment for the study of low-level clouds and their vertical geometry. Fog (ground-touching low-level clouds), a common atmospheric phenomenon in the Namib Desert, is influenced by the interplay of coastal upwelling and spatial temperature differences. Differentiation of fog from other low-level clouds and understanding cloud dynamics are crucial, as fog impacts the water balance in this arid region. Here, ceilometer measurements of cloud base altitude are analyzed and combined with local station measurements with the aim of developing a statistical model to robustly predict cloud base altitude.
Initial results suggest a robust correlation between the cloud base height and surface relative humidity, as well as other meteorological variables. This finding proves beneficial for utilizing meteorological parameters such as the lifted condensation level as a surrogate for cloud-base height. The outcomes of this study hold significance for modeling of satellite-based fog probability product and ecological studies.

How to cite: Malik, D., Andersen, H., and Cermak, J.: Investigation of the Vertical Geometry of Low Level Clouds in the Namib Desert, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6150, https://doi.org/10.5194/egusphere-egu24-6150, 2024.

EGU24-6590 | ECS | Orals | AS2.4

Continuous, long-term monitoring of soil CO2 concentration and CO2 flux using a novel, low-cost CO2 sensor system 

Thi Thuc Nguyen, Ariel Altman, Nadav Bekin, Nurit Agam, and Elad Levintal

Soil respiration (Fs) datasets often exhibit low temporal-spatial resolution and spatial bias, particularly lacking observations in arid/semi-arid regions. This limitation significantly constrains our understanding of the mechanisms governing soil carbon dynamics and hinders the correct estimation of CO2 emissions at regional to global scales. Challenges in Fs estimation arise mainly from logistical constraints in manual data collection and the high costs of commercial measuring devices. To address this, we developed a low-cost, open-source, autonomous soil CO2 sensor system. The system design emphasized easy adoption and customization for non-engineer end-users, enabling the collection of high-frequency, long-term soil CO2 concentration data, and consequently, Fs estimates. A system including six low-cost CO2 sensors distributed at two soil depths (5 and 10cm) was deployed in the Negev Desert since May 2023. Fs estimates were determined from CO2 concentration gradient using Fick's law (FG) and cross-validated with Fs measured by automated chambers (FC). We found a good agreement between FG and FC both in the short term (i.e., sub-daily fluctuation) and long term (i.e., annual net CO2 emission). Our data also revealed daily and seasonal Fs patterns correlating with environmental factors like temperature and precipitation. The results demonstrate that our system, despite costing less than 10% of automated chamber systems, offers equivalent accuracy in Fs estimates, higher temporal resolution, and potential for enhanced spatial resolution if widely adopted.

How to cite: Nguyen, T. T., Altman, A., Bekin, N., Agam, N., and Levintal, E.: Continuous, long-term monitoring of soil CO2 concentration and CO2 flux using a novel, low-cost CO2 sensor system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6590, https://doi.org/10.5194/egusphere-egu24-6590, 2024.

The eddy covariance (EC) method has been widely used to capture the temporal and spatial patterns of nitrous oxide (N2O) emissions from a wide variety of agricultural ecosystems. Technological advancements in the recent years have brought new tunable infrared laser-based closed-path gas analyzers suitable for EC measurements. To achieve high sensitivity and low measurement noise, these analyzers use multi-pass optical cells with long sensing path. A drawback of these cells is the relatively large internal volume requiring high-flow rate, high-power pumps to attain fast response to changes in gas concentration.  Additionally, these cells are prone to contamination and require in-line filters. In this study we evaluate the frequency response of a novel, low-power, field deployable N2O closed-path EC system consisting of: (1) a gas analyzer with a small volume single-pass optical cell, (2) a 3 m sulfonated tetrafluoroethylene ionomer intake tube acting as water vapor permeable membrane to dry the air sample, (3) a cyclone type, non-barrier inertial particle separator (IPS) to mitigate the effects of particulates contamination of the optical sample cell, and (4) a small, low-power pump module with an automatic pressure and flow control. The performance of the new N2O EC system is evaluated in-situ 3 m above a fertilized agricultural wheat field and compared to a co-located fast-response H2O and CO2 open-path gas analyzer and sonic anemometer (IRGASON). Tube delays, determined by cross-covariance of N2O with vertical wind, were consistent over time and varied between 0.2 and 0.5 s. Spectral and co-spectral analysis of vertical wind, temperature, H2O, CO2 and N2O showed good agreement. Ogive functions demonstrated that the new system has adequate frequency response to capture >90% of the N2O fluxes for a wide range of wind speeds and atmospheric stabilities and is suitable for deployment in remote areas.

How to cite: Bogoev, I.: Frequency Response Evaluation of a Low-power Closed-path Eddy Covariance System for Measuring Nitrous Oxide Fluxes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6604, https://doi.org/10.5194/egusphere-egu24-6604, 2024.

EGU24-7308 | ECS | Posters on site | AS2.4

Role of vegetation and soil-induced effects of microclimate on non-rainfall water inputs 

Jannis Groh, Thomas Pütz, Daniel Beysens, Harry Vereecken, and Wulf Amelung

Precipitation (i.e. rain, snow, hail) is the main form of water input to our ecosystem. However, depending on local climatic conditions, a significant amount of water can also be produced by various fractions of non-rainfall water inputs (NRWIs), namely dew, hoar-frost, rime, fog, and adsorption of water vapour in the soil. Such NRWIs are often neglected because they are typically small compared to daily rainfall. However, these NRWIs provide our ecosystems with additional water, which is important for the survival of the fauna and flora in the ecosystem, especially during drier periods.

Although NRWIs are understood in principle, much remains to be learnt about their precise determination at the ecosystem level, their spatial and temporal distribution, and their ecological function for the ecosystem. We present a conceptual measurement setup that allows us to determine each non-rainfall water component for natural and extensive grasslands as well as for agricultural ecosystems. Our results for the experimental site Selhausen (Germany, TERENO-SOILCan) show that i) the main part of NRWI comes from dew formation, ii) the rate and frequency of dew formation differs significantly between vegetation types under similar atmospheric boundary conditions, and iii) the drivers of dew formation during a dry down period differ between ecosystems (grassland and arable land). A better understanding of these vegetation and soil-dependent effects will help us to better predict dew formation processes in our ecosystems in the future.

How to cite: Groh, J., Pütz, T., Beysens, D., Vereecken, H., and Amelung, W.: Role of vegetation and soil-induced effects of microclimate on non-rainfall water inputs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7308, https://doi.org/10.5194/egusphere-egu24-7308, 2024.

EGU24-7892 | Posters on site | AS2.4

Simultaneous trace gas flux monitoring of 10 greenhouse gases and air pollutants with a single instrument 

Morten Hundt, Marco Brunner, Jonas Bruckhuisen, and Oleg Aseev

Monitoring of trace and greenhouse gas fluxes is key to understand the interaction between atmosphere, plants, and soil and therefore to improving our understanding of the climate system in general.

Complex flux systems, in environments where both biogenic and anthropogenic sources and sinks play a role, require measurement of many different inert and reactive trace gases and greenhouse gases simultaneously to obtain a complete budget.

Until recently, however, the monitoring was usually limited to only a few gases per measurement device making the technique complex and expensive but providing only a limited picture. MIRO Analytical has developed a novel multicompound gas analyzer that can monitor up to 10 air pollutants (CO, NO, NO2, O3, SO2 and NH3), greenhouse gases (CO2, N2O, H2O and CH4) and other atmospheric trace gases such as (OCS, HONO, CH2O) simultaneously at ppb level.

The eddy covariance (eddy flux) technique is often used to measure fluxes of trace gases but requires a high time resolution. Our compact instrument, combing several mid-infrared lasers (QCLs), offers 10 Hz sampling rate, outstanding precision, selectivity and accuracy and an automatic water vapor correction, which makes it ideal for eddy covariance flux measurements.

In our contribution, we will introduce the measurement technique and will demonstrate application examples of this all-in-one atmospheric flux monitor. The system will be compared to alternative devices in parallel measurements and results of long-term observations and shorter campaigns will be presented.

How to cite: Hundt, M., Brunner, M., Bruckhuisen, J., and Aseev, O.: Simultaneous trace gas flux monitoring of 10 greenhouse gases and air pollutants with a single instrument, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7892, https://doi.org/10.5194/egusphere-egu24-7892, 2024.

Atmospheric fluxes near the surface are key metrics for understanding the interactions between the biosphere and the atmosphere. There is an increasing demand for highly accurate flux measurements for species where fast-response analytical techniques are not available. This includes, among others, stable isotopes, oxygen, ammonia, nitrogen compounds, and bio-aerosols.

Here we introduce quantized eddy accumulation with error diffusion, a new easy-to-implement, high-accuracy eddy accumulation method that is compatible with slow-response analytical techniques. Similar to relaxed eddy accumulation, this method involves sampling air at a constant flow rate and directing it into one of two containers, depending on the vertical wind velocity. The flux is then calculated based on accumulated concentration averages over the flux averaging interval. However, unlike relaxed eddy accumulation, the new method is a direct method that does not require the empirical coefficient β. These developments were made possible by developing a new representation of conditional sampling at a constant flow rate as a quantization process of vertical wind velocity. Fluxes estimated with relaxed eddy accumulation were found to be biased due to sub-optimal quantization. To account for these errors, an error diffusion algorithm was developed, which made it possible to minimize the biases inherent in the quantization process, thereby allowing for accurate and direct flux estimates.

Quantized eddy accumulation with error diffusion is shown to achieve direct flux measurements with errors smaller than 0.1% of the reference eddy covariance flux. Additionally, this method enables an increase in the concentration difference in accumulated samples between updrafts and downdrafts without compromising accuracy, making it especially suitable for detecting smaller fluxes. It also provides improved accumulation volume dynamics, flexible accumulation intervals, and is less prone to errors from non-zero vertical wind velocities.

These new developments are especially useful for measuring small fluxes of elusive atmospheric constituents, particularly in the presence of measurement challenges such as instrument drift or frequency attenuation. A notable application is the accurate measurement of water stable isotopes, which enables the tracing of biological processes and the accurate partitioning of measured fluxes.

How to cite: Emad, A.: Quantized eddy accumulation with error diffusion: a new direct micrometeorological technique with minimal requirements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8926, https://doi.org/10.5194/egusphere-egu24-8926, 2024.

Automated Solution for Discrete Gas Sample Analyses with
Picarro G2508 and SAM Autosampler
Jan Woźniak1, Joyeeta Bhattacharya2, Magdalena E. G. Hofmann1, Frank Krijnen3, Guillermo Hernandez
Ramirez4
1Picarro B.V., Eindhoven, The Netherlands, 2Picarro Inc., Santa Clara, USA; 3University of Saskatchewan; 4University of Alberta

Abstract
Greenhouse gas research community has witnessed an ever-increasing need for automated
solutions for measuring greenhouse gas concentrations in small discrete gas samples. However,
traditional solutions like gas chromatographs often incur high initial and maintenance costs or are
complicated to deploy and maintain, and almost impossible to work with in the field. There has
been a rising interest in the SAM autosampler (www.openautosampler.com) which so far has
been utilized mostly for isotopic measurements of greenhouse gases (e.g., isotopic CO2/CH4), in
conjunction with low flow Picarro analyzers (<50 mL/min). In this report, we demonstrate the
compatibility, efficiency, and advantages of the SAM autosampler with Picarro Greenhouse Gas
(GHG) Concentration analyzers like the G2508 multi species gas analyzer, with much higher flow
rates (>200 mL/min). The results of our experiments show excellent precision and accuracy for
discrete CH4, CO2 and N2O gas measurements. Also, we have been able to determine linearity in
dilution factors and characterized memory effects and its variability in different gas species (e.g.,
comparing CO2 vs N2O). This report also provides recommendations on the methods and best
practices for discrete gas sample measurements. In summary, the Picarro G2508 (or other GHG
analyzers) in conjunction with SAM Autosampler offers an attractive, cost-effective, and simpler
alternative to gas chromatograph or similar available solutions

How to cite: Wozniak, J.: Automated Solution for Discrete Gas Sample Analyses withPicarro G2508 and SAM Autosampler, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9193, https://doi.org/10.5194/egusphere-egu24-9193, 2024.

EGU24-9231 | ECS | Orals | AS2.4

Constructing a comprehensive numerical experiment to study biospheric-atmospheric feedbacks driving dry season cloud formation over the Amazon Basin  

Vincent de Feiter, Sebastiaan de Haas, Jordi Vilà-Guerau de Arellano, Raquel González Armas, Daniël Rikkers, Guido Haytzmann, Martin Janssens, Oscar Hartogensis, Imme Benedict, Luiz Machado, and Cléo Quaresma

The Amazonian hydrological and carbon cycle are controlled by a complex, interconnected and interdependent myriad of surface and atmospheric processes. Improving our understanding and numerical representation of these cycles under a changing climate requires a deeper exploration of the biospheric-atmospheric coupling and the processes governing the formation and deepening of shallow cumulus clouds. Utilising a comprehensive set of surface and upper-air atmospheric measurements from the CloudRoots-Amazon22 campaign alongside an integrated hierarchy of models, we construct a numerical experiment to systematically study these processes throughout the dry season of 2022. The model hierarchy consists of a large eddy simulation resolving turbulence and shallow cumulus formation, a coupled rainforest-atmosphere mixed-layer model to map the sensitivity to surface and atmospheric observations and a moisture tracking model to identify and quantify moisture sources, sinks, and long-range transport. Individual days of observations were characterised into representative shallow convective and shallow-to-deep convective regimes. We accurately replicated the evolution of radiation and the asymmetrical exchange fluxes of energy, momentum, moisture, and carbon during the shallow convective regime. By analysing the diurnal variability of the state variables, we can determine how turbulent mixing controls the morning transition, from strong gradients to well-mixed conditions above the forest. Ongoing work involves improving the representation of in-canopy processes and simulating the shallow-to-deep convective regime by introducing thermodynamic forcings, such as moist air intrusion or increased wind sheared conditions, on the shallow convective experiment.  

How to cite: de Feiter, V., de Haas, S., Vilà-Guerau de Arellano, J., González Armas, R., Rikkers, D., Haytzmann, G., Janssens, M., Hartogensis, O., Benedict, I., Machado, L., and Quaresma, C.: Constructing a comprehensive numerical experiment to study biospheric-atmospheric feedbacks driving dry season cloud formation over the Amazon Basin , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9231, https://doi.org/10.5194/egusphere-egu24-9231, 2024.

EGU24-9320 | ECS | Orals | AS2.4

Water and Carbon Dioxide Interactions in the most unlikely places: The hidden dynamics of the Sahara Desert soils 

Nadav Bekin, Dennis Ashilenje, Abdelghani Chehbouni, Lhoussaine Bouchaou, Lamfeddal Kouisni, Dilia Kool, and Nurit Agam

Soil CO2 efflux is primarily attributed to the metabolic activity of soil organisms and is a major component of the global carbon balance. The carbon balance of deserts, such as the Sahara Desert, the largest desert on Earth, is considered neutral as low soil moisture inhibits biological activity and reduces the soil CO2 efflux to its lower limit. Studies in the last decades challenge this paradigm, reporting a mysterious nocturnal CO2 uptake by desert soils, which in some cases leads to a net gain of carbon by the soil. While the factors controlling this phenomenon are still under debate, it is clear that the presence of water is essential. How, then, can nocturnal CO2 uptake occur in the driest soil conditions when no apparent water is available to drive the process? We embarked on a field expedition in the Sahara Desert, southwest Morocco, during the summer of 2022 to explore the dynamics of water and carbon in this presumably “stagnant” ecosystem. We discovered nocturnal water vapor adsorption, driven by atmospheric water vapor transported from the Atlantic Ocean and penetrating hundreds of kilometers inland where the vapor is captured in the soil’s top layer. Changes in soil water content were determined from soil relative humidity (measured using a profile of relative humidity sensors) and soil-specific vapor sorption isotherms (measured using a vapor sorption analyzer). With this novel method, we were able to detect a daily increase of 0.3 mm of water even at a distance of 250 km from the Ocean. Concurrent measurements of CO2 fluxes (measured using manual and automatic flux chamber systems), confirmed that small atmosphere-to-soil CO2 fluxes occurred during the night, coinciding with downward water vapor fluxes. This indicates that the atmosphere provides a consistent water source and may initiate soil CO2 uptake. Simultaneous measurements of water vapor and CO2 fluxes at a second site suggested that the quality of the correlation between the two fluxes depends on soil properties. Overall, the daily CO2 cycle was unbalanced (net uptake of 0.08 g m-2) implying that the soil acted as a carbon sink. This sink is small, but considering its occurrence even in inland desert ecosystems and the fact that arid and hyper-arid regions occupy 26% of Earth’s terrestrial surface, the effect of atmospheric water capture by desert soils on CO2 exchange may play a significantly larger role in the global carbon balance than previously thought. 

How to cite: Bekin, N., Ashilenje, D., Chehbouni, A., Bouchaou, L., Kouisni, L., Kool, D., and Agam, N.: Water and Carbon Dioxide Interactions in the most unlikely places: The hidden dynamics of the Sahara Desert soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9320, https://doi.org/10.5194/egusphere-egu24-9320, 2024.

EGU24-9627 | ECS | Orals | AS2.4

Increased spatial replication above heterogeneous agroforestry improves the representativity of eddy covariance measurements 

José Ángel Callejas Rodelas, Alexander Knohl, Ivan Mammarella, Timo Vesala, Olli Peltola, and Christian Markwitz

Eddy covariance (EC) studies typically involve the use of one or maximum two measuring towers, which leads to a low level of spatial replication, compromising the statistical representativity of EC measurements, especially above highly heterogeneous ecosystems, such as agroforestry systems. Lower-cost eddy covariance setups (LC-EC) represent a potential solution to this problem, since their affordability allows for the installation of multiple EC towers to study heterogeneity at the landscape scale. In the last years, several LC-EC setups have been successfully validated against conventional EC setups (CON-EC), with the main difference being the use of slower gas analyzers. These introduce a higher uncertainty due to the enhanced high-frequency spectral attenuation in the turbulent energy spectrum.

In this study, we analyzed turbulent fluxes of CO2 and H2O and turbulence characteristics measured by three flux towers equipped with LC-EC setups above one agroforestry system located in Wendhausen, Germany. The agroforestry system was a Short Rotation Alley Cropping (SRAC) system, consisting of alternating rows of trees and crops. The three flux towers were installed at different North-South aligned tree stripes. Additionally, we compared the results of the three LC-EC setups above the SRAC with another LC-EC setup installed at an adjacent monocropping (MC) field.

The objectives of the study were: (i) to evaluate the spatial variability of EC fluxes from the three flux towers above the SRAC system; (ii) to compare the variability of fluxes within the SRAC to the variability of fluxes between SRAC and MC; (iii) to quantify whether the use of several LC-EC setups counteracts the higher uncertainty associated to LC-EC, due to the increased statistical robustness of the measurement network compared to the hypothetical use of just one EC station.

The highest spatial variability across the SRAC was measured for CO2 fluxes, followed by latent heat (LE) flux, with coefficients of variation, calculated following Oren et al. (2006) (https://doi.org/10.1111/j.1365-2486.2006.01131.x), of 2.3 and 1.4 (dimensionless), respectively. The spatial variability in CO2 and LE fluxes within the SRAC was similar to the variability between MC and SRAC, and was attributed to the different land cover types around the towers. On the other hand, the spatial variability in sensible heat flux (H), momentum flux and turbulence characteristics (such as friction velocity and variance of vertical wind speed), within the SRAC, was smaller than the variability between SRAC and MC, likely explained by the development of an internal boundary layer (IBL) above the SRAC.

Our results show that the heterogeneity of the SRAC, despite not affecting significantly the turbulence characteristics across the site, leads to a large spatial variation in CO2 and LE fluxes. Therefore, a distributed network of several EC systems is necessary to properly quantify patterns and drivers of CO2 and latent heat fluxes above such heterogeneous land-use systems.

How to cite: Callejas Rodelas, J. Á., Knohl, A., Mammarella, I., Vesala, T., Peltola, O., and Markwitz, C.: Increased spatial replication above heterogeneous agroforestry improves the representativity of eddy covariance measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9627, https://doi.org/10.5194/egusphere-egu24-9627, 2024.

EGU24-9790 | ECS | Posters on site | AS2.4

Turbulence generation by unresolved orography 

Shreyas Deshpande and Cedrick Ansorge

Slope flows, resulting from the interplay between buoyancy and gravitational forces, are well-known to govern a plethora of local weather phenomena. In particular, orographic features and the associated surface roughness can induce turbulent mixing in the planetary boundary layer. While orographic drag models have been proposed to understand the effects of turbulence and waves due to orography, numerical simulations locally rely on closures based on the Monin-Obukhov Similarity Theory. The validity of these models and their interaction regarding turbulence production due to orography at unresolved scales is questionable. We study the turbulence generation by small-scale orography under the influence of stable stratification and weak mixing. To bypass the common complications with surface modeling, we use direct numerical simulation featuring a shallow valley to study the problem at a reduced scale. To imitate the intricate boundary conditions, an Immersed Boundary Method is used that features fully resolved three-dimensional roughness elements in the form of a local valley. However, modeling such flows also poses challenges due to the numerous parameters governing the triggering of turbulence. In this presentation, we introduce a scaling framework orographic for the problem and a viable numerical set-up along with the first results from preliminary studies at intermediate scale separation.

* This work is funded by the ERC Starting Grant ”Turbulence-Resolving Approaches of the Intermittently Turbulent Atmospheric Boundary Layer [trainABL]” of the European Research Council (funding ID 851347).

How to cite: Deshpande, S. and Ansorge, C.: Turbulence generation by unresolved orography, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9790, https://doi.org/10.5194/egusphere-egu24-9790, 2024.

Atmospheric flows virtually always occur over rough surfaces, which enhances the drag, mixing and vertical transport of pollutants and moisture in the atmospheric boundary layer (ABL). During nighttime, when the absence of solar radiation leads to surface cooling, a stratified surface layer forms, and turbulence decreases in intensity and spatial extent, giving rise to large-scale intermittency. Roughness is known to counteract the buoyancy-induced reduction of turbulence in the stable regime by an increase of mixing, but the effects are lumped together in surface-layer similarity. To investigate the interaction of surface roughness and stable density stratification in the ABL at the process level, direct numerical simulation (DNS) of rough turbulent Ekman flow at Reynolds numbers well within the turbulent regime and for large domains is performed. Roughness is represented by an array of 56×56 roughness elements with a uniform width and height distribution on the lower wall. This small-scale three-dimensional surface roughness is fully resolved with an immersed boundary method (IBM) and has a packing density of 10%. For neutral stratification, we have obtained data in the transitionally rough regime and at the verge of the fully rough regime. Starting from the roughest neutral case with z0+≈2, stable stratification is gradually increased with a constant-temperature (Dirichlet) boundary condition. The focus of this study is the direct effect of roughness on the stability regime, the rough-wall scaling in the logarithmic layer and the scaling for the roughness parameters z-nought for momentum and temperature, which is crucial for the Monin–Obukhov similarity theory.


* This work is funded by the ERC Starting Grant ”Turbulence-Resolving Approaches of the Intermittently Turbulent Atmospheric Boundary Layer [trainABL]” of the European Research Council (funding ID 851347). Simulations were performed on the resources of the High-Performance Computing Center Stuttgart (HLRS) on the Hawk cluster. The computing time and storage facilities were provided by the project trainABL with the project number 44187.

How to cite: Kostelecky, J. and Ansorge, C.: Simulation and scaling analysis of small-scale roughness in neutrally and stably stratified turbulent Ekman flow, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10016, https://doi.org/10.5194/egusphere-egu24-10016, 2024.

EGU24-10102 | Orals | AS2.4

The Land-Atmosphere Feedback Initiative 

Volker Wulfmeyer and the The LAFI Team

The quality of weather forecasts, seasonal simulations, and climate projections depends critically on the adequate representation of land-atmosphere (L-A) feedbacks. These feedbacks are the result of a highly complex network of processes and variables related to the exchange of momentum, energy, and mass. Significant challenges persist in understanding processes and feedbacks, which this initiative will address.

The Land-Atmosphere Feedback Initiative (LAFI) is an interdisciplinary consortium of researchers from atmospheric, agricultural, and soil sciences as well as from bio-geophysics, hydrology, and neuroinformatics proposing a novel combination of advanced research methods. The overarching goal of LAFI is to understand and quantify L-A feedbacks via unique synergistic observations and model simulations from the micro-gamma (» 2 m) to the meso-gamma (» 2 km) scales across diurnal to seasonal time scales.

LAFI consists of a network of closely intertwined projects addressing six research challenges formulated as objectives and hypotheses on 1) alternative similarity theories, 2) the impact of land-surface heterogeneity, 3) partitioning evapotranspiration, 4) understanding entrainment, 5) synergistic characterization of L-A feedback, and 6) droughts or heatwaves potentially investigated by ad-hoc field observations. Collaboration across the twelve projects will be fostered by three Cross Cutting Working Groups on Deep Learning, Sensor Synergy and Upscaling, as well as the LAFI Multi-model Experiment.

In this presentation, an overview of the LAFI research approach is given with particularly emphasis of the synergy of observations and modeling efforts substantiated by first results from the Land-Atmosphere Feedback Observatory (LAFO) at the University of Hohenheim in Stuttgart, Germany.

How to cite: Wulfmeyer, V. and the The LAFI Team: The Land-Atmosphere Feedback Initiative, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10102, https://doi.org/10.5194/egusphere-egu24-10102, 2024.

EGU24-10295 | ECS | Posters on site | AS2.4

Exploring Nocturnal Canopy Advection in Complex Terrain Through Active Heating Fiber Optics: Unraveling Temperature Dynamics and Airflow Patterns 

Yi Fan Li, Kuo Fong Ma, Chin Jen Lin, Yen Jen Lai, Po Hsiung Lin, and Taro Nakai

Nocturnal advection significantly influences the accurate estimation of net ecosystem exchange (NEE). This phenomenon is prevalent in Taiwan's subtropical montane forests, introducing a potential bias when relying solely on eddy covariance data for carbon budget calculations. From the preliminary analysis, the wind speed can be well estimated through the temperature difference between the heated and unheated fiber optical.The derived five-minute average wind speed exhibits a high coefficient of determination (R^2) of up to 0.94.

In the current study, a fiber observational setup consisting of a 40m vertical section and a 90m horizontal section has been implemented to investigate temperature dynamics and airflow in complex terrain. The wind speed profile can be well reflected from the preliminary data analysis. Insights gained through this approach contribute to a better understanding of the nocturnal canopy advection model, offering valuable corrections to NEE estimates.

How to cite: Li, Y. F., Ma, K. F., Lin, C. J., Lai, Y. J., Lin, P. H., and Nakai, T.: Exploring Nocturnal Canopy Advection in Complex Terrain Through Active Heating Fiber Optics: Unraveling Temperature Dynamics and Airflow Patterns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10295, https://doi.org/10.5194/egusphere-egu24-10295, 2024.

EGU24-11109 | ECS | Orals | AS2.4

Time-scale turbulent transport extraction and high time resolution flux estimation using wavelet analysis 

Gabriel Destouet, Nikola Besic, Emilie Joetzjer, and Matthias Cuntz

Flux estimation from eddy-covariance flux tower measurements faces the problem of integrating fluxes only in the case of fully developed turbulence and in non-stationary environments with advective components. The standard eddy-covariance method operates on fixed-length signals, requiring the knowledge of a maximum correlation time-length as well as post-processing steps assessing the suitability and quality of the data. Statistical tests are carried out to assess if flux estimates were performed during sufficiently developed turbulence and if they were corrupted by advective components. Tests with friction velocity u* or σw, steady-state tests, and flux variance similarity are now standard during and after flux calculations. More elaborate methods such as ogive optimisation are used to deal with advection. An important disadvantage of all these statistical tests is that they discard the whole time interval such as half an hour if they detect failure.

Time-scale (time-frequency) analyses have been used as an alternative to the standard time-analysis approach to estimate ecosystem fluxes. In particular, wavelet analysis, which is well adapted to the study of non-stationary and scale invariant processes such as turbulence, has been used in previous works. It presents the ability of separating the different components of the flux in time-scale space and as such could be an efficient alternative for flux estimation avoiding the above statistical tests.

To address this problem, we propose a general framework for analysing fluxes in time-scale space, and propose a new method for identifying and extracting turbulent transport that avoids advective components and does not need statistical tests after the flux calculations. The new method is based on the analysis in time-scale domain of the amplitude of the vertical component of the Reynold stress tensor and can be seen as a time-scale transposition of standard tests mentioned above. As a direct consequence, we are able to estimate fluxes at high time resolution over times and scales with sufficiently developed turbulence. We show application of the framework at the beech forest site FR-Hes and demonstrate its relation with standard eddy covariance calculations. Our methodology is implemented in the Julia package TurbulenceFlux.jl and is readily available. The proposed framework and its code implementation is fully differentiable and hints to further investigations, such as the study of flux ecosystem response times, or sensitivity analysis against wavelet and averaging window parameters.

How to cite: Destouet, G., Besic, N., Joetzjer, E., and Cuntz, M.: Time-scale turbulent transport extraction and high time resolution flux estimation using wavelet analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11109, https://doi.org/10.5194/egusphere-egu24-11109, 2024.

EGU24-12298 | Posters on site | AS2.4

The dynamics of water vapor  absorption by soils typical of arid lands 

Pedro Berliner, Mercy Ama Boadi Manu, Dillia Kool, and Nurit Agam

Water vapor adsorption (WVA), a non-rainfall water input, is a poorly documented phenomenon despite its role in regulating water and energy fluxes in soils of coastal deserts. Water vapor movement towards the soil surface and its absorption by the soil occurs whenever the atmospheric water potential is higher than that of the air-filled soil pores. The latter is influenced by soil characteristics, in particular the soil surface area and pore connectivity. Thus, it is expected that under similar atmospheric conditions,  absorption of water vapor will be determined by soil characteristics. We carried out a detailed field trial in which we compared two loamy soils with different salt content.

Water vapor absorption was measured using micro-lysimeters (MLs) instrumented with relative humidity (RH) and temperature sensors at depths 0.5cm, 2cm, 5cm, 10cm, and 45cm in both MLs during the 2022 and 2023 summers. Total absorption was determined as the increase in mass from a minimum (obtained during late afternoon) to a peak observed on the next day before sunrise. Concurrent changes in soil water potential at each depth were computed by applying the Kelvin equation.

Relative humidity in both soils was low during the entire season with the average computed water potential values being lower in the high salt content soil. The total daily water vapor absorption was lower in the low salt content soil, and the rate of absorption was different . The temperature and RH distribution patterns with depth also differed consistently throughout the measuring season for both soils. The effect of salt on water vapor absorption will be highlighted.

How to cite: Berliner, P., Boadi Manu, M. A., Kool, D., and Agam, N.: The dynamics of water vapor  absorption by soils typical of arid lands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12298, https://doi.org/10.5194/egusphere-egu24-12298, 2024.

EGU24-13667 | Orals | AS2.4

Deployment of Doppler lidar within forests: Advancing our understanding of canopy-atmospheric boundary layer processes  

Sonia Wharton, Matteo Puccioni, Holly Oldroyd, Matthew Miksch, Matthias Falk, Stephan de Wekker, Robert Arthur, and Jerome Fast

The atmospheric boundary layer above forest canopies is difficult to measure in practice, and our understanding of its flow physics usually is still limited to tall tower measurements which have limited reach above the canopy, or vertically-profiling remote sensing measurements which are usually taken outside of the canopy. We present a recent 5-month study of wind flow measurements taken above a 50-m tall forest in Washington state, USA, using two Doppler lidars. One vertical-profiling lidar was placed directly on top of the 70-m tall Wind River National Ecological Observatory Network (NEON) tower and took measurements of wind velocity, direction and turbulence up to 220 m above ground level. A scanning lidar was placed in a nearby clearing and programmed to scan the wind field over the forest canopy, including overlapping its scans with the profiling lidar on top of the tower. The scanning lidar also captured terrain induced flows across the surrounding mountain-valley terrain. Both lidars captured wind jets and periods of intermittent turbulence over the forest canopy. How and when these mechanically-forced turbulence events penetrate the high leaf area index (LAI) forest canopy are studied using NEON’s eddy covariance flux exchange measurements and the tower profile measurements of air temperature, pressure, moisture, and wind velocity within the forest.

 

Applications of studying wind flow over the forest canopy are broad and vary from a better characterization of the wind profile for wind energy resource assessment to improving our understanding of vertical exchange processes by studying how “top-down” forced turbulence events influence mass and energy fluxes between the forest canopy and atmosphere. Special consideration of how above canopy processes influence canopy coupling/decoupling, including top-down turbulent sweep events, will be presented for the tall Wind River forest. We will also discuss upcoming experiments including 1) the deployment of 3-d sonic anemometers in the Wind River subcanopy (as part of a larger Integrated Carbon Observation System (ICOS) below-canopy study) to advance our understanding of canopy mixing processes and 2) a new campaign planned for the deciduous Mountain Lake Biological Station NEON tower in the mountains of Virginia, USA. The latter study is designed to observe changes in the above-canopy wind profile and its interactions with below-canopy flows and vertical flux exchanges across a summer-to-winter LAI transition.

 

How to cite: Wharton, S., Puccioni, M., Oldroyd, H., Miksch, M., Falk, M., de Wekker, S., Arthur, R., and Fast, J.: Deployment of Doppler lidar within forests: Advancing our understanding of canopy-atmospheric boundary layer processes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13667, https://doi.org/10.5194/egusphere-egu24-13667, 2024.

EGU24-14868 | Orals | AS2.4

Mapping soil moisture uptake by dry soils across Eddy covariance measurement sites 

Sinikka Paulus, Rene Orth, Sung-Ching Lee, Jacob A. Nelson, Anke Hildebrandt, Ngoc Nguyen, Markus Reichstein, and Mirco Migliavacca

Soils take up water vapor from the atmosphere through processes that involve vapor diffusion and water retention. This can theoretically occur in any ecosystem under the preconditions of a humid atmosphere and dry soil pores. It can play a critical role in dry ecosystems because it can provide a substantial proportion of the total water inputs at the daily timescale. However, it remains insufficiently investigated in many regions, partly due to the absence of continuous, dedicated measurements.

In this study, we use a recently developed algorithm to detect and filter Eddy Covariance (EC) derived negative latent heat flux data collected at semi-arid and arid sites to identify soil water vapor adsorption. In a previous study, we successfully used EC data to detect soil water vapor adsorption for a Mediterranean ecosystem. 

Our findings indicate that these negative latent heat fluxes exhibit a correlation with soil water content and relative humidity at various sites suggesting that a part of the negative latent heat flux is related to soil water vapor adsorption. Building on these findings, we demonstrate that soil water vapor adsorption occurs during the dry season in various ecosystems, including woody savannas, grasslands, shrublands, and even some forests. The flux magnitude reaches values comparable to daily evaporation, which is in line with existing literature on the few previously measured ecosystems.

Furthermore, we analyze the drivers of the occurrence and dynamics of soil water vapor across sites. Thereby we study the influence of e.g. soil texture or vegetation height. This way, our study expands our knowledge of the spatial extent and inter-annual dynamics of soil water vapor adsorption in natural ecosystems and, more generally, sheds light on a mostly overlooked aspect of land-atmosphere interaction.

How to cite: Paulus, S., Orth, R., Lee, S.-C., Nelson, J. A., Hildebrandt, A., Nguyen, N., Reichstein, M., and Migliavacca, M.: Mapping soil moisture uptake by dry soils across Eddy covariance measurement sites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14868, https://doi.org/10.5194/egusphere-egu24-14868, 2024.

EGU24-15005 | Posters on site | AS2.4

Climatology of surface parameters for the city of Turin using UTOPIA (Italy) land surface model 

Claudio Cassardo, Valentina Andreoli, Davide Bertoni, Sujeong Lim, Massimiliano Manfrin, and Seon K. Park

While there are several series of daily observations of temperature, precipitation and few other parameters available in many locations in the world, sometimes lasting more than a century, there are much less series of other variables related to the surfae atmospheric layer or underground soil, such as sensible and latent heat fluxes, soil heat flux, soil temperature and moisture in the root layer and below it. This work aims to propose a method to evaluate such parameters at a climatic time scale using a trusted land surface model, taking the variables from the outputs of the simulation and creating a database. In this work, the selected model is the UTOPIA (University of TOrino land surface Process Interaction model in Atmosphere). This technique can be applied in general to each site in which hourly observations of the seven parameters needed for the simulation are available (temperature, humidity, pressure, the two components of the horizontal wind velocity, precipitation and solar radiation or cloudiness). In a preliminary phase, the database will be created on the period 1992-2023, on which we have the availability of hourly measurements carried out at the Department of Physics of the Turin University. In a second phase, we plan to develop a methodology to derive hourly observtions from the existing series of data gathered in the city of Turin, using peculiar methods to interpolate or extrapolate the missing observations of required inputs and to downscale hourly observations from daily observations. This methodology could be tested using the eisting data in the recent climate period.

How to cite: Cassardo, C., Andreoli, V., Bertoni, D., Lim, S., Manfrin, M., and Park, S. K.: Climatology of surface parameters for the city of Turin using UTOPIA (Italy) land surface model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15005, https://doi.org/10.5194/egusphere-egu24-15005, 2024.

EGU24-15582 | ECS | Posters on site | AS2.4

A satellite-based analysis of fog and low stratus life cycle processes in the Po valley, Italy 

Eva Pauli, Jan Cermak, Hendrik Andersen, and Michaela Schütz

A better understanding of fog and low stratus (FLS) life cycle processes can help traffic safety, improve solar power planning and enhance the understanding of ecosystem processes in fog-prone regions. Nevertheless, large-scale analyses of FLS life cycle processes are challenging due to the high spatial variability of FLS and complex interactions between the land surface and the atmosphere.

Here, we use a satellite-based FLS formation and dissipation time data set, as well as reanalysis data to investigate regional variations in the FLS life cycle in the Po valley region in northern Italy. With its large spatial extent, relatively low topographic variability and high FLS occurrence, the Po valley is an ideal area to study FLS life cycle processes in central Europe. In a case study approach, we analyze FLS life cycle processes pertaining to variations in land surface characteristics and atmospheric drivers. First results reveal the importance of the temporal development of temperature, specific humidity and boundary layer height for FLS formation during radiation-driven FLS events. These effects are further modified by the local topography and the synoptic situation.

This analysis provides a basis to set up further process-oriented sensitivity studies using explainable machine learning, which has shown to be an ideal tool to gain a deeper understanding of the effect of non-linear land-atmosphere interactions on the FLS life cycle.

How to cite: Pauli, E., Cermak, J., Andersen, H., and Schütz, M.: A satellite-based analysis of fog and low stratus life cycle processes in the Po valley, Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15582, https://doi.org/10.5194/egusphere-egu24-15582, 2024.

EGU24-16214 | ECS | Orals | AS2.4

Microphysical and Electrical Characteristics of Fog in the United Arab Emirates 

Narendra Reddy Nelli, Diana Francis, Ricardo Fonseca, Olivier Masson, Mamadou Sow, Rachid Abida, and Emmanuel Bosc

Fog is a prevalent weather phenomenon in several arid regions, including the Empty Quarter desert in the United Arab Emirates (UAE), located on the northeastern side of the Arabian Peninsula. Despite being primarily an arid country with desert landscapes dominating its terrain, most events causing visibility to drop below 1 km in the UAE are attributed to condensation processes rather than dust occurrences. We present in-situ measurements of fog microphysics from the Barakah Nuclear Power Plant (BNPP, a coastal site located at 23.968052°N, 52.267309°E) and atmospheric electric field measurements obtained during the Wind-blown Sand Experiment (WISE)-UAE field campaign conducted at Madinat Zayed (23.5761° N, 53.7242° E; elevation: 119 m).

Measurements of fog microphysics were conducted during the winter season of 2021 -2022 at the BNPP, located in the Western coastal region of the United Arab Emirates. Twelve fog events were observed during this period. The primary objective of this study is to detail the microphysical characteristics of these events and refine current visibility parameterization schemes based on in-situ measurements of fog microphysical properties. All observed fog events are found to share a common feature: a bimodal distribution in droplet number concentration (Nc), with modes at 4.5 µm and 23.2 µm . Despite the high proportion of fog smaller droplets associated with the fine mode, the greatest contribution to the liquid water content (LWC) comes essentially from medium to large droplets between 10 µm and 35 µm. The recalibration of existing visibility parameterization schemes revealed that the decrease (increase) in horizontal visibility with increasing (decreasing) LWC (FI, fog index) tends to be more gradual for the studied cases compared to standard visibility parameterization schemes. Additionally, the fog sedimentation velocity, estimated to be at a maximum of 1.85 cm s-1, occurs predominantly in the LWC range of 100 - 200 mg m3, corresponding to a median volume diameter 24.8 µm. Our findings shed new light on the complexity of fog microphysics and its impact on visibility, underscoring their importance in refining weather models for accurate fog forecasting.

For the first time, the changes in the atmospheric electric field (Ez) during foggy conditions is studied in a hyper-arid region; the United Arab Emirates (UAE), using comprehensive measurements during the Wind-blown Sand Experiment (WISE)-UAE. The longer the fog persists, the more variable Ez becomes, primarily due to the fog's ability to absorb and redistribute the charges of the atmospheric small ions. This absorption alters the ion balance, affecting electrical conductivity within the atmosphere, which in turn leads to sustained alterations in Ez. A record high Ez value of 2571 V m-1 was measured during a long-lasting fog event. Ez values returned to normal during the fog dissipation phase. The results of this work can be applied to develop techniques for fog harvesting and to improve fog forecasting by accounting for the effect of the electric field on fog lifetime and characteristics.

How to cite: Nelli, N. R., Francis, D., Fonseca, R., Masson, O., Sow, M., Abida, R., and Bosc, E.: Microphysical and Electrical Characteristics of Fog in the United Arab Emirates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16214, https://doi.org/10.5194/egusphere-egu24-16214, 2024.

EGU24-16368 | ECS | Posters on site | AS2.4

Examining the fog occurrence over the Bucharest Henri Coandă International Airport and its adjacent area 

Alex Vlad, Gabriela Iorga, Nicu Barbu, and Sabina Stefan

Fog forecasting and fog nowcasting events are challenging issues especially when the fog phenomenon appears in the vicinity of airports because the reduced visibility associated with fog represent a high risk for air traffic events. Bucharest Henri Coandă International Airport (OTP, 44.57°N, 26.1°E, 95 m above sea level) is the largest airport in Romania and is located about 16 km north of Bucharest, the capital and most developed city of Romania. Its surroundings are comprised partly of residential and natural protected areas, and partly have agricultural use. Due to its geographic position, the airport is an important air traffic hub on the routes between western and eastern world destinations. In terms of numbers of flights, during the observation period analyzed here, the air traffic at OTP was significantly lowered during the spring of 2020 due to COVID-19 pandemic but soon after the restrictions were lifted and due to redirection of the flights over Ukraine after 2022, the air traffic is significantly increased in present.

Data and analyses reported here cover a period of 2 decades from the beginning of 2003 to the end of 2023. Meteorological data, including fog events, relative humidity, wind speed and direction, were measured by the weather station of Romanian Air Traffic Services Administration ROMATSA R.A. Data about boundary layer and solar radiation was extracted from the public available database from the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5.

Present study reports the analysis of the evolution of the frequency of fog events and the relationships between fog events and speed and direction of the wind, and between fog events and the relative humidity. The correlations between the boundary layer height, solar radiation and the fog events were also investigated. Bivariate polar plots revealed fog appears with higher frequency (about 32%) during cold season, from October to March, and during early morning hours. Overview of the entire data set shows in some years mono-modal distributions of the fog frequency of occurrence with respect to the local time with peaks during the night and in the early morning hours and mono-modal flat distributions in other years. We observed the fog events are correlated with dominant wind directions of east-nord-east (ENE) and west-south-west (WSW). Statistical analysis of the data also showed a prevalence of the radiation fog over the advection fog.

Acknowledgement: AV was supported by the University of Bucharest, PhD research grant. AV acknowledges the partial funding from the NO Grants 2014-2021, under Project contract no. 31/2020, EEA-RO-NO-2019-0423 project. Data regarding boundary layer and solar radiation was extracted from the public available database from the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5. We thank ROMATSA R.A. for access to the database.

How to cite: Vlad, A., Iorga, G., Barbu, N., and Stefan, S.: Examining the fog occurrence over the Bucharest Henri Coandă International Airport and its adjacent area, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16368, https://doi.org/10.5194/egusphere-egu24-16368, 2024.

EGU24-16844 | Posters on site | AS2.4

Leaf thermoregulation and fog wetting dynamics of Erica platycodon in a Macaronesian cloud forest 

Carlos M. Regalado, Omar Garcia-Tejera, and Axel Ritter

Interception of fog droplets in cloud forests leads to wetting of the canopy, hampering transpiration and affecting the energy dynamics of the vegetation due to evaporation of the leaf water lamina and the reduction in the incoming solar radiation. We carried out continuous concurrent measurements of the canopy temperature (through infrared thermometers), artificial leaf wetness (LWS) and the micrometeorology of a cloud forest in the Anaga Biosphere Reserve (Tenerife, Canary Islands) during a 4-month period. Fog presence at the site, characterized by visibility measurements (Ω), was coincidental with variations in LWS and a decline in net solar radiation, Rn, i.e. 62.2 W m-2 during foggy conditions (Ω < 1 km) versus 245.0 W m-2 for fog-free conditions (Ω ≥ 1 km). Infrared readings during foggy conditions of one of the representative species of the cloud forest stand, the perennial tree Erica platycodon, showed that differences between canopy and ambient temperatures were primarily driven by Rn. After a fog event, E. platycodon was estimated to remain wet for at least 30 minutes up to 2.25 hours. This study provides information about the consequences of fog in the wetting/drying dynamics of cloud forests of the Canary Islands and their leaf thermoregulation.

How to cite: Regalado, C. M., Garcia-Tejera, O., and Ritter, A.: Leaf thermoregulation and fog wetting dynamics of Erica platycodon in a Macaronesian cloud forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16844, https://doi.org/10.5194/egusphere-egu24-16844, 2024.

EGU24-16949 | ECS | Posters on site | AS2.4

Measuring Greenhouse Gas Exchange from Paddy Field Using Eddy Covariance Method in Mekong Delta, Vietnam 

Khue Vu Hoang Ngoc, Georg Jocher, Vu Le D. A., Son Le T., An Bui T., Bang Ho Q., and Huong Pham Q.

Agriculture is an important economic sector of Vietnam, the most common is wet rice cultivation. Wet rice cultivation is known as the main contributor to national greenhouse gas emissions. To better understand greenhouse gas exchange in wet rice cultivations and to investigate the factors influencing carbon cycling and sequestration in these types of ecosystems, since 2019, the first eddy covariance station has been installed in a paddy field in Long An province, Mekong Delta, Vietnam. The station is equipped with state-of-the-art equipment for CO2 and CH4 gas exchange and meteorological ancillary measurements. Data from the station are processed following the ICOS recommendations (Integrated Carbon Observation System) for CO2. For CH4, data are separately processed and gap-filled using a random forest model from methane-gap fill-ml, a machine learning package, as there is no standard method for CH4 flux gap-filling yet. Finally, the CO2 equivalent (CO2eq) based on CO2 and CH4 fluxes was estimated. The study area implemented a new water management practice called alternate wetting and drying, which helps to save water and reduce methane emissions. This practice resulted in the minor release of 0.8 kg CH4 per hectare in 2020 and 0.67 kg CH4 per hectare in 2021. However, CO2eq from the rice fields was negative, indicating that the rice fields acted as a sink for CO2eq, with -5.54 kg CO2eq per hectare in 2020 and -7.03 kg CO2eq per hectare in 2021. On a provincial level, rice cultivation activities in Long An, with a total area of 498293 ha, resulted in a CO2eq uptake of 2760 and 3503 tons in 2020 and 2021, respectively. This result is in contrast to the initial hypothesis that rice fields are a source of greenhouse gases. However, N2O was not investigated in this study, which is also known as a strong greenhouse gas.

How to cite: Vu Hoang Ngoc, K., Jocher, G., Le D. A., V., Le T., S., Bui T., A., Ho Q., B., and Pham Q., H.: Measuring Greenhouse Gas Exchange from Paddy Field Using Eddy Covariance Method in Mekong Delta, Vietnam, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16949, https://doi.org/10.5194/egusphere-egu24-16949, 2024.

EGU24-17604 | ECS | Orals | AS2.4

The role of forest canopy-wind interactions on experimental fire behavior using coupled atmosphere-fire modeling 

William Antolin, Mélanie Rochoux, and Patrick Le Moigne

 

Session: AS2.4: Air-Land Interactions

 

Abstract:

Experimental fires provide insights into the behavior of wildland fires and their interactions with the atmosphere. They help modelers build simulations capable of accurately describing fire dynamics, and which can help identify the key processes driving fire development. In particular, the FireFlux I case (a tall grass fire covering 30 hectares) was the first experimental fire to provide in situ measurements of atmospheric dynamics near the fire, highlighting the complexity of fire-induced flows and the importance of fire-induced upward vertical motion (Clements et al. 2007). Despite much theoretical work on forest canopy turbulence, its interactions with fire dynamics are still poorly understood, while they could play an important role (Heilman et al. 2021).

One of the difficulties in wildland fire simulations stems from the disparity between scales. Highly detailed models based on computational fluid dynamics (CFD) tend to represent chemical, radiation, and turbulence processes at the cost of reduced domain size. Conversely, meteorological models tend to provide a better representation of ambient wind over a larger domain size, but this is at the expense of parameterization choices. An intermediate modeling scale is needed to represent the geographical and micrometeorological scales involved in a wildland fire, especially in the development of the fire plume and the induced air entrainment. In recent years, we have therefore worked on designing and validating a coupled atmosphere-fire model, Meso-NH/BLAZE (Costes et al. 2021), where BLAZE represents the fire as a propagating flaming front and Meso-NH is run in large-eddy simulation (LES) mode at high resolution (10-100 m). This preliminary work has highlighted the predominant influence of surface wind on fire behavior and thus the critical need to make it more representative.

In this study, we show that accounting for interactions between forest canopy, surface wind and fire can be done by adding a drag term in the Meso-NH momentum and TKE equations (Aumond et al. 2013), and by running coupled atmosphere-fire simulations at very high resolution (10m and finer). We also assess for the FireFlux I case, the impact of the forest canopy on fire spread through several original data analyses, including wavelet transforms, fire-canopy interaction statistics, and sensitivity to atmospheric turbulence.

 

References

Clements, C. B., et al. (2007) Observing the Dynamics of Wildland Grass Fires: FireFlux – A Field Validation Experiment. Bull. Amer. Meteor. Soc., 88, 1369–1382. doi: 10.1175/BAMS-88-9-1369

 E.Heilman WE, et al. (2021) Observations of Sweep–Ejection Dynamics for Heat and Momentum Fluxes during Wildland Fires in Forested and Grassland Environments. Journal of Applied Meteorology and Climatology 60(2), 185–199. doi:10.1175/jamc-d-20-0086.1

Costes, A., et al. (2021) Subgrid-scale fire front reconstruction for ensemble coupled atmosphere-fire simulations of the FireFlux I experiment. Fire Safety Journal, 126, 103475, doi: 10.1016/j.firesaf.2021.103475

Aumond, P., et al. (2013) Including the drag effects of canopies: Real case large-eddy simulation studies. Boundary-Layer Meteorology, 146, 65–80, doi: 10.1007/s10546-012-9758-x

How to cite: Antolin, W., Rochoux, M., and Le Moigne, P.: The role of forest canopy-wind interactions on experimental fire behavior using coupled atmosphere-fire modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17604, https://doi.org/10.5194/egusphere-egu24-17604, 2024.

EGU24-18634 | ECS | Posters on site | AS2.4

Urban Surface Energy Flux Estimations Utilizing a Thermodynamic Analytical Framework 

Mayank Gupta, Ajinkya Khandare, and Subimal Ghosh

At the local scale, energy exchange shapes microclimates and ecosystems crucial for human health and well-being. For urban areas, the effect, such as Urban Heat Island, is directly manifested in these surface energy fluxes with contrasting responses in values between urban and rural areas. Although progress has been achieved in modeling the land surface energy balance, challenges arise from complex, variable parameterizations linked to surface and climate characteristics, introducing uncertainties. In this work, we utilized the thermodynamic theory that considers the land-atmosphere as a radiative-convective system to analytically estimate total turbulent heat flux and land surface heat storage flux for 20 Urban sites and compared them with Eddy covariance observations. The heat fluxes are determined only from four primary parameters: incoming and outgoing longwave and shortwave radiations at the terrestrial surface. Using the monthly averages derived from the total turbulent flux estimates at the eddy covariance sites, we observed root-mean-square error (RMSE) of 29.16 ± 11.3 Wm−2, a mean bias error (MBE) of -7.09 ± 19.6 Wm−2 and R2 value of 0.82 ± 0.16. We further tested the analytical estimates with land use land cover of Urban sites. Our findings illustrate the distribution of land surface heat storage flux estimates following land use land cover characteristics. The analytical estimates of heat fluxes for urban areas offer several advantages, such as ease of implementation and inexpensive computation, facilitating the evaluation of urban land use feedback for informed urban planning.

How to cite: Gupta, M., Khandare, A., and Ghosh, S.: Urban Surface Energy Flux Estimations Utilizing a Thermodynamic Analytical Framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18634, https://doi.org/10.5194/egusphere-egu24-18634, 2024.

EGU24-20860 | ECS | Posters on site | AS2.4

Laboratory analysis on fog harvesting meshes employing durability tests 

Maria Giovanna Di Bitonto, Carol Monticelli, Salvatore Viscuso, and Alessandra Zanelli

Fog harvesting, an ancient water extraction technique, has gained renewed attention in recent years with the introduction of the Fog Water Collector. Comprising a mesh and supporting structure, this collector has proven effective in extracting water from atmospheric moist air. The Raschel mesh, initially designed for agricultural purposes, has become the predominant choice due to its affordability and widespread availability. Current research endeavors aim to enhance fog water yield by optimizing both collector design and mesh properties.

While Raschel mesh coatings have traditionally been explored to improve efficiency, recent findings suggest that alternative meshes may outperform the conventional Raschel mesh. However, challenges persist in understanding the resistance, lifespan, and maintenance requirements of these newer materials.

Our research takes a systematic approach to address this gap by assessing the durability of various fog harvesting meshes under laboratory conditions. A series of standardized tests are conducted to evaluate their efficiency, providing insights into the intricate relationship between cost, water collection efficiency, duration, and environmental impact. The study aims to inform decision-making processes surrounding fog harvesting mesh selection, considering factors such as initial investment, operational efficiency, and long-term sustainability.

By conducting these analyses in a controlled laboratory environment, we aim to provide valuable insights without the logistical challenges associated with field studies. This approach allows for a thorough examination of fog harvesting mesh performance, contributing to the broader understanding of NRWIs and their potential applications at different scales.

How to cite: Di Bitonto, M. G., Monticelli, C., Viscuso, S., and Zanelli, A.: Laboratory analysis on fog harvesting meshes employing durability tests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20860, https://doi.org/10.5194/egusphere-egu24-20860, 2024.

EGU24-22205 | Posters on site | AS2.4

Quantification of storage change at two contrasting eddy covariance sites 

Anastasia Gorlenko, Konstantinos Kissas, Charlotte Scheutz, and Andreas Ibrom

Eddy covariance (EC) flux measurements are relevant for the study of global change biology when integrated over long-term periods (Baldocchi, 2019). This could lead to researchers being reluctant to adopt state-of-the-art correction methods, especially for sites that have collected continuous data and trends for the last 20 years. The storage change (SC) correction has often been overlooked and simplified and is generally under-investigated in the literature. The present study highlights the dynamics of the storage change term in two different landscapes and proposes a simple correction factor that can be applied backwards to historical data in a forested ecosystem.

The first studied site is a mixed deciduous forest in Denmark (DK-Sor), where a sequential vertical profile system (12 heights) has been installed in 2021 to characterize the vertical component of the storage change more accurately. We compare the often-used 1 point method with the results from the profile system for CO2 and H2O. We study the SC component in terms of its diurnal course, its impact on the annual carbon budget, and its relation to atmospheric stability parameters.

The second site is a Danish rural area (DK-Hove), where four different greenhouse gas fluxes are measured with EC sensors installed at 3 heights on a 200 m tall telecommunication tower. The SC profile system here consists of 5 levels and needs to adapt to the dynamic eddy covariance measurement height of the landscape-scale GHG monitoring system. We present 6 months of SC data from the tall tower for CO2, CH4, N2O and CO, their diurnal courses and relation to meteorological variables.

Overall, this work aims at bringing an additional contribution to shed light on the often-neglected SC term.

 

Reference:

Baldocchi, Dennis D. How eddy covariance flux measurements have contributed to our understanding of Global Change Biology. United Kingdom: N. p., 2019. Web. doi:10.1111/gcb.14807.

How to cite: Gorlenko, A., Kissas, K., Scheutz, C., and Ibrom, A.: Quantification of storage change at two contrasting eddy covariance sites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22205, https://doi.org/10.5194/egusphere-egu24-22205, 2024.

EGU24-22211 | Orals | AS2.4

Optimising the sampling strategy in tall tower eddy covariance flux measurements 

Andreas Ibrom, Konstantinos Kissas, Anastasia Gorlenko, and Charlotte Scheutz

Tall tower eddy covariance (EC) measurements can be used to narrow down the gap between the ecosystem and the continental scale observations by capturing greenhouse gas (GHG) fluxes in a landscape scale (>10 km2). Because of the large footprint, tall tower platforms enable monitoring of greenhouse gas net fluxes, integrating over a multitude of diverse GHG sources and sinks within anthropogenic ecosystems. Yet, the temporal variability of atmospheric stability and atmospheric boundary layer affects the size of the flux footprint and the quality of EC flux estimates, respectively, thereby complicating the interpretation of surface flux estimates. The objective of this study is to determine an optimal sampling scheme alternating between different measuring heights (zm) in order to maximise the number of valid flux measurements as well as mitigating the effect of weather fluctuations on the longitudinal position of the footprint.

We used a six months’ data set of continuous turbulence data measured from a recently deployed prototype flux observation station in a rural area close to the Danish Capital of Copenhagen, Zealand. The system is mounted on a 200 m telecommunication tower equipped with 3D ultrasonic anemometers in three different heights (70m, 90m, 115m) and with a TILDAS GHG analyser capable of switching between three sampling lines corresponding to the specified heights.

We define an optimal sampling strategy based on the peak location of the individual, crosswind-integrated footprints from valid samples. As valid, we characterized those flux measurements, when the zm was within the constant flux layer, as estimated from ceilometer measurement. For each of the half hours, we selected the zm with the footprint’s peak location closest to a target position.

In this presentation, we demonstrate the ability to constrain the flux footprint within a target landscape area by establishing a sampling schedule across the three sampling heights. The results showed that designing a sampling strategy that combines multiple heights has the potential to bring the aggregated footprint for the entire period (footprint climatology) closer to the targeted area. A similar outcome can be attained when sampling from a single height and excluding the instances where the footprint significantly deviates from the target area. Nevertheless, this comes with the trade-off of discarding valid data. Moreover, the weather effect on the variability of the crosswind-integrated footprints was reduced by setting an optimal, multi-height strategy in comparison to the aggregated footprints from the individual heights.

How to cite: Ibrom, A., Kissas, K., Gorlenko, A., and Scheutz, C.: Optimising the sampling strategy in tall tower eddy covariance flux measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22211, https://doi.org/10.5194/egusphere-egu24-22211, 2024.

The Kentucky Mesonet is a great asset for the Commonwealth of Kentucky, from realtime storm monitoring to building a detailed climate record. A detailed climate record is essential as causality between observations and extreme weather can be identified. The climate record being developed at the 80+ Kentucky Mesonet observation stations consists of approximately 75 indices. The indices include frequency, extremes, range, duration, and trends of precipitation, droughts, and temperature. For example, calculations of Warm/Dry days (daily mean temperature > 75th percentile of daily mean temperature and daily mean rainfall < 25th percentile of daily precipitation sum where the percentiles are based on a climatology taken from reanalysis between 1961 and 1990) are done for daily, monthly, seasonal, bi-annual, and annual aggregation periods. Particular attention will given to soil moisture - precipitation feedbacks as Kentucky has a karst geology which generates soil moisture gradients. Soil Moisture-precipitation feedbacks, the beginning and ending of land-atmosphere interactions in general, are highly dependent on the wind flow regime and atmospheric stability, so these relationships will elucidated in the presentation.  Tools will be developed based on interactions with policymakers and stakeholders as they will be making decisions today that impact the region’s main economic sectors (e.g. water, energy, transportation, etc.) as infrastructure erected today will likely be in place when the climate is different than at present. Examples will be provided that sample the different climate zones of the state, relative elevations of site locations, as well as different land cover and land uses.

How to cite: Rappin, E.: Land-Atmosphere Interactions as Observed by a Statewide in-situ Surface Observation Network, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22465, https://doi.org/10.5194/egusphere-egu24-22465, 2024.

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