The paper describes a comprehensive framework for soil organic carbon density (SOCD) (kg/m3) modeling and mapping, based on spatiotemporal Random Forest (RF) and Quantile Regression Forests (QRF). A total of 45,616 SOCD measurements and various feature layers, particularly 30m Landsat-based spectral indices, were used to produce 30m SOCD maps for the EU at four-year intervals (2000--2022) and four soil depth intervals (0--20cm, 20--50cm, 50--100cm, and 100--200cm). Per-pixel 95% probability prediction intervals (PIs) and extrapolation probabilities are also provided. Model evaluation indicates consistent accuracy, with R2 between 0.53--0.67 and CCC 0.68--0.80 across cross-validations and independent tests. Prediction accuracy varies by land cover, depth interval and year of prediction with accuracy the worst for shrubland and deeper soils 100--200cm. PI validation confirmed effective uncertainty estimation, though with reduced accuracy for higher SOCD values. Shapley analysis identified soil depth as the most influential feature, followed by vegetation, long-term bioclimate, and topographic features. While pixel-level uncertainty is substantial, spatial aggregation reduces uncertainty by approximately 66%. Detecting SOCD changes remains challenging but offers a baseline for future improvements. Maps, based primarily on topsoil data from cropland, grassland, and woodland, are best suited for applications related to these land covers and depths. Users should interpret the maps with local knowledge and consider the uncertainty and extrapolation probability layers. All data and code are available under an open license at https://doi.org/10.5281/zenodo.13754343 and https://github.com/AI4SoilHealth/SoilHealthDataCube/.
How to cite: Tian, X., de Bruin, S., Simoes, R., Isik, M. S., Minarik, R., Ho, Y.-F., Şahin, M., Herold, M., Consoli, D., and Hengl, T.: Spatiotemporal modeling and mapping of soil organic carbon density with uncertainty quantification across Europe (2000–2022), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2154, https://doi.org/10.5194/egusphere-egu25-2154, 2025.
Soil Inorganic Carbon (SIC) deposits are more dynamic than previously assumed. Studies have revealed an acceleration of SIC dynamics over just a few decades (Kim et al., 2020) driven by agricultural management of these soils (Plaza-Bonilla et al., 2015).
Most SIC reserves are in the arid and semi-arid regions of the planet, where atmospheric CO2 can be incorporated into the soil as CaCO3 precipitates through photosynthesis and root respiration processes (Monger et al., 2015). In these regions, irrigation is often a critical requirement for agriculture. Changes in the soil water regime due to irrigation can modify carbonate dynamics, affecting their dissolution and (re)precipitation, i.e., the formation of pedogenic carbonates.
If the source of these secondary carbonates is carbonate-rich parent material, this represents merely a redistribution of carbonates within the soil profile. However, if HCO3⁻ originates from the mineralization of soil organic matter (SOM) or root respiration, and Ca²⁺ is derived from the weathering of non-carbonate minerals such as gypsum (CaSO₄·2H₂O) (Laudicina et al., 2021), the soil behaves as a net sink of atmospheric CO2 (Sanderman, 2012).
This study is carried out using a multi-scale approach (“macro” focus at watershed level and “micro” focus at the root level) to quantify the extent of atmospheric C incorporation into carbonates in gypsum-rich irrigated soils.
First, monitoring sulfate and bicarbonate concentrations in a river draining a watershed in the Foral Community of Navarre (Spain) revealed elevated levels of these anions during periods of intensive irrigation. This indicates accelerated dissolution of both carbonates and gypsum, a phenomenon not detected in years prior to the adoption of irrigation.
The second phase examines the effect of gypsum content on pedogenic carbonate formation and root biocalcifications using a controlled pot experiment. Calcareous silt loam soil (30% CaCO3) without gypsum was mixed with varying gypsum concentrations (0%, 5%, 50%, 80%) and planted with three species (Brassica oleracea, Rosmarinus officinalis, and Oxalis sp.). After the growth cycle, root samples were extracted and microscopically analyzed to identify calcified roots and associated carbonate features. The results demonstrated that higher gypsum content significantly increased root calcifications, confirming that gypsum dissolution supplies abundant Ca²⁺ for calcite precipitation within root tissues.
Future analyses, such as δ87/86Sr ratios and Sr²⁺/Ca²⁺ proportions of the carbonates (indicators of Ca²⁺ origin), isotopic characterization of C, and micromorphological and digital quantification of calcitic soil features using thin sections, will provide a deeper understanding of these processes. This could support an innovative strategy for inorganic carbon sequestration in soils of arid and semi-arid regions.
References:
Kim et al. (2020), https://doi.org/10.1111/gcb.15207.
Laudicina et al. (2021), https://doi.org/10.1016/j.geoderma.2021.115115.
Monger et al. (2015), https://doi.org/10.1130/G36449.1.
Plaza-Bonilla et al. (2015), https://doi.org/10.1007/s13593-015-0326-x.
Sanderman (2012), https://doi.org/10.1016/j.agee.2012.04.015.
How to cite: Conte, A. P., Bosch, A. D., Gómez-Reig, P., Poch, R. M., de Soto, I. S., and Virto, I.: Study of carbonates dynamics in gypsum-rich soils after the adoption of irrigation. A multiscale approach., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17025, https://doi.org/10.5194/egusphere-egu25-17025, 2025.
Measurement of changes in soil organic carbon (SOC) under various management practices at the field scale poses significant challenges due to inherent spatial and temporal variability. In comparison ecosystem biogeochemical models offer a robust framework for simulating nutrient cycling, SOC, and greenhouse gas emissions that can be used to identify and evaluate long-term effects and strengths of climate change mitigation strategies. DayCent is a coupled soil-plant dynamic model that has been widely used to simulate long-term ecosystem responses to changes in soil management and climate in the US. Its application to agricultural systems in Ireland requires a calibration and evaluation for common management practices across a range of pedo-climatic conditions. The objective of this study was therefore a) to calibrate the DayCent model with several types of field data and to evaluate its performance in simulating SOC and soil N2O emissions and b) to explore the sensitivity of model parameters to different types of field data. Our aim was to simulate the effects of a long-term application of dairy, pig, and mineral fertilizers on grass yields, SOC and soil organic nitrogen (N) stocks, and soil N2O fluxes in a long-term permanent grassland experiment. To calibrate the model, the data from control and high pig slurry application treatments from 1970 to 2022 were used. The calibration was separated into two steps: a) the first step was a manual calibration for SOC and soil organic N, volumetric soil water content, and grass yield; b) the second step was an automatic calibration for soil temperature, daily N₂O emission, soil NO₃⁻ and NH₄⁺ concentrations with the PEST parameter estimation software. All remaining treatments, that varied in the rate and type of animal slurry application, were used in the independent model evaluation. Using this information the performance of the calibrated model was substantially improved for SOC stock (rRMSE=0.17, r2=0.54, d=0.78, n=102) compared to the default model (rRMSE=0.25, r2=0.29, d=0.45, n=102) across all validation treatments. Similarly, an improvement was found for soil organic N stock in the validation treatments (rRMSE=0.19, r2=0.70, d=0.78, n=102) compared to the default model (rRMSE=0.30, r2=0.64, d=0.53, n=102). Improvements in simulating daily N2O emissions (calibrated model: rRMSE=5.30, r²=0.08, d=0.44, n=186; default model: rRMSE=2.97, r²=0.02, d=0.22, n=186), and soil NO₃⁻ and NH₄⁺ concentrations were still quite uncertain across validation treatments. In conclusion, the calibrated DayCent successfully simulated the long-term dynamics of SOC and soil organic N stocks, grass yields, soil water content, and soil temperature across varying nutrient application rates, although there were some limitations in simulating daily and annual N₂O emissions, and mineral N concentrations. While further testing under various pedo-climatic conditions is necessary, DayCent has the potential to be used as a tool for optimizing nutrient management strategies under Irish conditions.
How to cite: Qi, Z., Holland, J., Osborne, B., Gallego-Lorenzo, L., and Necpalova, M.: DayCent model calibration to assess the long-term impact of the animal slurry application on grassland in Ireland: Performance, sensitivities and scope for improvement, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6593, https://doi.org/10.5194/egusphere-egu25-6593, 2025.
The reclamation of degraded soils, particularly in tropical post mining areas, presents a significant challenge. Organic soil amendments are widely proved to improve soil health by increasing organic carbon accumulation in degraded soils, such as that in a tropical post-tin mining area. Their application also affects soil organic carbon (SOC) quality. However, a process of quality transformation induced by the organic soil amendments is still far from definite. Thus, this study aimed to explore the transformative potential of organic soil amendments in boosting SOC storage and enhancing its quality.
Over a four-year period, we conducted a comprehensive study in an Indonesian post-tin mining soil using a randomized block design with four replications. The treatments included control (no amendment), compost, charcoal, and a combination of charcoal and compost. Our findings revealed that organic amendments not only increased SOC stock but also induced significant changes in SOC quality, as evidenced by chemical composition analysis using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR). Notably, the charcoal treatment showed marked differentiation of SOC chemical composition from the second year onwards. By performing a two-dimensional correlation spectroscopic (2DCOS) analysis, we observed an intensive change in SOC quality transformation. The organic soil amendments facilitated soil microorganism activity and plant growth with the variety of carbon inputs, leading to enhanced lignin and ester accumulation. This study underscores the dual benefits of organic amendments in improving both the quantity and quality of SOC in degraded soils, offering a sustainable solution for soil reclamation.
How to cite: Sae-Tun, O., Maftukhah, R., Ngadisih, N., Murtiningrum, M., Hood-Nowotny, R., Mentler, A., and Keiblinger, K.: Soil Carbon Dynamics in Reclaimed Mining Lands: Insights from Organic Amendment Applications, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4962, https://doi.org/10.5194/egusphere-egu25-4962, 2025.
Accurate estimation of Soil Organic Carbon (SOC) is essential for sustainable soil management and carbon stock assessment. To achieve this, the development of efficient, non-invasive methods for SOC quantification is imperative. This study leverages PRISMA hyperspectral imagery and advanced machine learning techniques to predict SOC in Moroccan cereal-based agricultural soils. To this end, a detailed data processing pipeline was implemented, including denoising, band filtering, and feature engineering techniques such as Principal Component Analysis (PCA) for dimensionality reduction, spectral index calculations (e.g., NDVI, BSI, MSI), and Recursive Feature Elimination (RFE) to identify the most informative spectral features. Additionally, Field data collection was conducted in the Ain Korma commune, Province of Meknes, where 60 soil sampling points were established. At each sampling location, a polygon encompassing four corner points, and a center was defined. Soil samples were extracted using an auger. Individual samples from the five points were combined to create a composite sample, representing the average soil characteristics of the area. The Field samples coordinates are transformed into the image coordinate reference system to enable the extraction of spectral data for corresponding pixels. The modeling process revealed significant improvements in predictive accuracy with the application of preprocessing and feature selection. Initially, the XGBoost model achieved a low coefficient of determination (R²=0.08). We believe this low R2 is most likely due to the high-dimensional hyperspectral data, redundant information, and the presence of strongly correlated spectral bands that hindered the model's ability to generalize. To overcome these limitations, we implemented an advanced preprocessing that combines removing noisy and absorption bands (e.g., water vapor), co-registering the PRISMA imagery with Sentinel-2, performing advanced denoising using Wavelet and Savitzky–Golay filtering, and conducting Principal Component Analysis (PCA) alongside the calculation of spectral indices. Following these preprocessing steps, multiple machine learning algorithms were applied to predict SOC. Among the tested models, Recursive Feature Elimination (RFE) combined with XGBoost achieved the best performance, with a coefficient of determination (R²) of 0.32 and Mean Absolute Error (MAE) of 0.35. Partial Least Squares Regression (PLSR) also performed, which attained an R² of 0.30. R² of 0.30 and an MAE of 0.34. More efforts will be deployed to explore other ways to increase the model performance. These preliminary results underscore the critical role of data preprocessing and feature selection in enhancing model performance for SOM estimation. By addressing the limitations of hyperspectral data.
How to cite: Farah, N., Laamrani, A., and Bouabid, R.: Estimation Soil Organic Carbon Using Hyperspectral Imaging and Machine Learning: A Case Study in Moroccan Agricultural Soils, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20502, https://doi.org/10.5194/egusphere-egu25-20502, 2025.
Mineralised nitrogen (N) from soil organic matter (SOM) is a crucial source of N for both natural ecosystems and agroecosystems. Therefore, accurate estimation of the amount of N available to crops from SOM mineralisation is necessary to correctly manage N addition. For application in an N budget, a field-scale assessment of the main factors affecting SOM mineralisation is required. The objective of this study was to quantify the influence of meteorological conditions and soil properties on N mineralised by SOM in an agroecosystem. The N mineralised from the SOM was calculated as the N uptake of the unfertilised plot minus the N derived from atmospheric deposition and irrigation. This study analysed 29 years of crop, agrometeorological, and soil data from three maize cropping systems (maize for grain, maize for silage, and maize-It. ryegrass double cropping) in a long-term experiment conducted in NW Italy. A Linear Mixed Model (LMM) was developed for the purpose of this study. The average of N derived from SOM mineralisation predicted by the model was 96 kg N ha−1 yr−1, with a root mean square error of 22 kg N ha−1 yr−1. The fixed factors of LMM, which are soil organic carbon (SOC), carbon-to-nitrogen ratio (C/N) and the sum of rainfall and irrigation (R.I.), were responsible for 19 % of the annual variations in mineralised N. SOC and R.I. had a positive effect and greater weight on the process, whereas C/N had a negative effect and lower weight. The explanatory power of the model increased to 52 % when cropping systems and interannual variability were included as random factors. This study highlights the importance of weather conditions and SOC content in determining the amount of N derived from soil mineralisation and can contribute to plant nutrition. In a future climate scenario characterised by increased aridity, N mineralisation could decrease, thus increasing the demand for fertilisers.
How to cite: Chiriac, O., Pittarello, M., Moretti, B., and Zavattaro, L.: Factors influencing nitrogen derived from soil organic matter mineralisation: Results from a long-term experiment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10375, https://doi.org/10.5194/egusphere-egu25-10375, 2025.
Mobilizing plant functional diversity appears as a promising avenue to promote agroecosystems multifunctionality and stability in order to face agriculture challenges in terms of production, limitation of inputs, conservation of soils, and mitigation of greenhouse gases emissions. In natural or semi-natural ecosystems, a high level of plant functional diversity might trigger beneficial plant-soil ecological interactions, leading to several mechanisms of coordination over time between plant nutrient demand and soil offer (i.e., “synchrony”). As perennial prairies can reach a considerable degree of functional diversity within a small area, their implementation with crops can be a precious lever to promote such mechanisms. Among those, a seasonal scale coordination between plants nutrient demand and the relative balance between microbial construction and microbial decomposition of Soil Organic Matter (SOM) was associated with prairies encompassing fast-growing species. This leads to improved plant primary productivity combined with reduced nutrient losses, and increased microbial originated carbon (C) storage in the soil. Moreover, the modulation of nitrogen (N) symbiotic fixation depending on photosynthesis activity by legumes within the prairies allows N enrichment of the agroecosystem.
We conceived an experimental design with new agroecosystems called “agroprairies” which gather perennial diversified prairies and winter wheat (Triticum aestivum) cultivated in alternating bands. Four functionally different prairies were designed to vary across nutrient acquisition strategies and proportion of legumes. The experiment also included plots with each cover grown alone, as well as a perennial crop (Thinopyrum intermedium). We explored the effects of plant functional diversity on soil biogeochemical C and N cycles and soil microbial communities and activities. We conducted measurements of plant production, soil microbial C dynamics (microbial C use efficiency, soil microbial respiration, microbial biomass, microbial growth), five hydrolytic or oxidative exoenzyme activities related to C, N and phosphorus (P) cycles and abundances of the soil microbial communities (bacteria, archaea and fungi). These measurements were performed in January 2024 during winter at a time where plant nutrient demand is low, and in May 2024 at the maximum plant biomass production. We found that soil biogeochemical C and N cycles and abundances and activities of microbial communities strongly varied between January and May, and that some of these variables, as well as the production of wheat differed depending on the functional characteristics of the prairies.
How to cite: Bécu, T., Niboyet, A., Alvarez, G., Besson, L., Gross, N., Barot, S., Cantarel, A., Duchene, O., Le Roux, X., and Fontaine, S.: Combining diversified prairies with wheat to promote beneficial plant-soil ecological interactions and the coupling of carbon and nitrogen biogeochemical cycles in agroecosystems, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11499, https://doi.org/10.5194/egusphere-egu25-11499, 2025.
Increased crop diversification in rotation systems consisting of increased taxonomic and functional crop diversity throughout time and lower intensity of agricultural management might be more sustainable alternatives to conventional practices. Crop-species specific induction of rhizobiomes (bacteria, fungi and protists) are among the reasons for the improved sustainability linked to diversified crop rotation systems. In turn, rhizobiome diversity and composition affect plant performance. However, the cumulative knowledge on crop species impacts on the rhizobiome and the resulting feedback to subsequently grown crops – the basis for more efficient crop rotation practices – remain limited. We aimed to fill this gap by establishing four rotation systems with increasing diversification in a long-term field experiment, followed by a greenhouse experiment to validate how changes in rhizobiomes affected plant performance. Crop diversification in rotation systems altered rhizobiome composition, with increases in plant beneficial microorganisms and a reduction of plant pathogens. These diversification-induced rhizobiomes facilitated plant performance by enhancing the chlorophyll content, leaf area, height and biomass of subsequent plants. As such, manipulating rhizobiomes through crop diversification might contribute to promoted plant performance with less dependency on chemical fertilizers or pesticides.
How to cite: Hu, S., Chen, Y., Kammenga, J., and Geisen, S.: Diversification of crop rotation systems shifts rhizobiomes to facilitate plant performance, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14651, https://doi.org/10.5194/egusphere-egu25-14651, 2025.
The effect of conventional and organic management in agriculture impacts not only economic and food quality aspects but potentially all biological components of the environment where these activities occur, including soil microorganisms. While there is generally positive appreciation for organic agriculture's role in organic matter accumulation, its beneficial effects on soil microbiota are a matter of debate, mostly due to the varying conditions in which the comparisons are made. To minimize the impact of distant locations, soils were sampled from nearby fields managed separately with the same rotation schemes for 18 years with conventional low-impact and organic agriculture methods. Samples from six different crops were compared using metabarcoding and metabolomic fingerprinting. The major differences were found between late summer and spring, whereas the variations between the beginning and the end of the spring were neither large nor significant. Some significant differences were found between the microbiota of organic vs. conventional management, particularly between r- and k-strategist microorganisms. While other studies found very little differences between microbiota of differently managed soils after shorter time periods, this work highlights that nearly two decades of separate management are necessary to induce significant variations in the microbiota. This suggests a strong resilience of soil populations and the need for very long-term strategies in agriculture to effect significant changes in soil quality.
How to cite: Casagrande Pierantoni, D.: Soil microbiota resilience in a two-decade long-term experiment comparing an organic and a conventional cropping system, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6041, https://doi.org/10.5194/egusphere-egu25-6041, 2025.
Grain legumes (GLs) are essential for sustainable agriculture, offering nutritional, agronomic, and ecological benefits. GLs are predominantly grown to full maturity for animal feed in Denmark and across Europe. However, the EAT–Lancet Commission on healthy diets has underscored the necessity of a global dietary shift towards greater direct human consumption of plant protein to improve human health and promote planetary performance. The cultivation of GLs remains limited in Europe, challenged by facts like climatic constraints and nitrogen (N) leaching—driven by mineralization of their N-rich residues. Integrating early-harvested fresh GLs, grown for human consumption, with catch crops presents a promising strategy to overcome these challenges. Compared to late-harvest mature grain legumes for animal feed, such systems potentially reduce disease incidence, improve catch crop establishment and thus reduce N leaching, enhance N fertility for subsequent crops, and increase ecosystem services, such as carbon (C) inputs for soil C sequestration from both main crops and catch crops. However, empirical studies synthesizing these benefits of such systems in comparison to conventional cereals are missing at the crop rotation level. Based on a two-year crop rotation of fresh GLs (faba bean, pea, and the mixture of pea and barley), catch crops and the subsequent cereal crop (barley) in 2022-2023 in Denmark, we evaluated the productivity, N dynamics, and C inputs of GLs systems relative to a cereal crop. The results showed that GLs produced lower aboveground dry matter (DM) compared to the cereal (7-8 vs. 10 Mg DM ha-1), but higher N yield (175-198 vs. 80 kg N ha-1). Among GLs, faba bean fixed the most atmospheric N (166 kg N ha-1) and left the highest residual soil N, which was effectively reduced by catch crops. Subsequent barley yields were, on average, higher following faba bean (4.7-5.3 Mg DM ha-1) compared to the cereal reference (4.0-4.7 Mg DM ha-1). Total C inputs to 1-m soil depth (main crops, from root biomass and plant deposition; catch crops, from shoot, root biomass and plant deposition) was 4.1-4.4 Mg C ha-1 among GLs, which was comparable to the cereal reference (5.2 Mg C ha-1). However, GLs based systems received no N fertilizer as opposed to the cereal reference, which was fertilized with 100 kg N ha-1 (in slurry). This reduces the reliance on external inputs, and might minimize negative environmental impacts including greenhouse gases emissions, which needs future studies. Overall, our findings highlight the ecological and agronomic potential of fresh GLs systems with catch crops for sustainable agricultural production.
How to cite: Liang, Z., Martins, J., Leanne, P., Enggrob, K., and Rasmussen, J.: Fresh grain legume systems with catch crops: promising soil C inputs and enhanced N fertility, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5371, https://doi.org/10.5194/egusphere-egu25-5371, 2025.
Posters on site: Tue, 29 Apr, 10:45–12:30 | Hall X4
Decalcification, especially due to acidity induced by nitrogen (N) fertilization, generates an often-underestimated source of atmospheric CO2 in agroecosystems. Complete soil decalcification intensifies the decomposition of soil organic carbon (SOC) to an extent not yet experimentally demonstrated. Six fertilization management practices including application of urea, urea + superphosphate + potassium chloride, ammonium phosphate, ammonium phosphate + potassium chloride, chicken manure along a control i.e. without fertilization were used to quantify the effects of N fertilization on soil acidification and the contribution of SIC-originated CO2 to total soil CO2 emissions. Gas samples were collected during a 56-day incubation experiment to determine total emitted CO2 and its δ13C value. The presence of soil inorganic carbon (SIC), i.e. carbonates, kept the total CO2 emissions after inorganic fertilization at levels comparable to unfertilized soil and a balanced fertilization reduced carbonate-derived CO2 emissions (15% after NPK vs 35% with N applications) due to better nutrient use efficiency and comparatively less proton generation after nitrification. When inorganic N fertilization led to complete decalcification following the shift is soil pH from circumneutral (pH=7.4) to slightly-moderately acidic pH (pH=6.5 to about 5.8) values, a sudden increase in total CO2 emissions indicated the loss of the protective effects of carbonates, and the extreme decomposition of the indigenous SOC. Complete decalcification activates a negative feedback loop: the more fertilizer is added for more crop production, the more SOC, and soil productivity will be lost. We conclude that balanced fertilization and the use of organic fertilizers not only ensure sustainable productivity, but also significantly reduce CO2 emissions from agroecosystems by preventing soil carbonate loss.
How to cite: Abdollahpour, M., Fan, L., Shao, G., Tao, J., Guggenberger, G., and Zamanian, K.: Balanced fertilization management to protect carbonate stocks and reduce soil CO2 emissions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6185, https://doi.org/10.5194/egusphere-egu25-6185, 2025.
This study investigated the comparative influence of regional difference in agronomic potential (‘Region'), natural drainage (‘Drainage’) and grassland management intensity (‘Manage’) on soil physicochemical variables, microbial community structure and soil enzymatic activity across 37 Irish grassland sites. Of the soil physicochemical variables measured, nested ANOVA models revealed that soil dry matter, total Carbon and Nitrogen, M3-Magnesium and M3-Calcium were significantly influenced by ‘Region’ (p < 0.05), while soil pH and soil organic Carbon were significantly influenced by both ‘Region’ and ‘Manage’, though the former had the stronger influence. No measured variable was significantly influenced by ‘Drainage’. A nested PERMANOVA model revealed that each of the three factors exerted a significant influence on soil microbial community structure (p < 0.05), with the community centroid distance (Euclidian) also revealing that there was a comparative influence between the three factors (distance range = 0.066 – 0.079). The factor ‘Drainage’ did have a stronger influence on the abundance of the fatty acid biomarker for the arbuscular mycorrizal fungi (effect size = 20.54%) than ‘Region’ (effect size = 10.05%), while ‘Manage’ did not display a significant effect. In contrast to soil microbial community structure, individual soil enzymatic activities mostly either did not significantly respond to any factor, or significantly responded to ‘Region’ (p < 0.05, i.e., β-N-acetyl-glucosaminidase and arylsulfatase). The study highlights the value of considering localized environmental drivers in studies relating to soil health at the national level, to support effective, context-specific management strategies for soil health.
How to cite: Fox, A., Barreiro, A., Wall, D., and Bondi, G.: The Influence of Region, Drainage and Management on Soil Physicochemical Properties, Microbial Community, and Enzymatic Activities in Irish Agricultural Grasslands, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-237, https://doi.org/10.5194/egusphere-egu25-237, 2025.
Forests all over the world are endangered by different factors such as fragmentation, landscape change, deforestation, pollution or inadequate management, with the detrimental effects that this cause on biodiversity or even climate change, since these ecosystems are crucial carbon sinks, both above and below-ground, even though the soil section is quite often excluded from the C pools estimations. The soil microbial community plays a key role in the stabilization of organic matter in the forest soil systems and harbours numerous ecosystems services, but can be affected, among other factors, by the different tree species present in the forest canopy. This study is focused on forests located in Galicia (on the north-west of Spain) with a temperate climate, specifically Cbf climate (Köppen classification), with no dry season and mild summers. This climate implies that the forests in this region are very productive, and this has a clear impact in the tree species that grow on then naturally and the species planted with commercial purposes. We analyse soil properties and soil microbial activity in 54 forest plots, both natural and plantations, with different plant cover: birch, chestnut, eucalyptus, walnut, pines, oak and shrublands. Soil samples were collected at 0-20 cm depth in spring-summer 2024 and the soil microbial activity was estimated by the respiration rate (CO2 production) using a gas chromatograph (FID-ECD-TCD).
These forest soils have in general an acid pH (between 4.2 and 5.4) and a high content of organic matter (between 6.3 and 31 %), with C and N concentrations ranging 3.6-17.9% and 0.2-0.9% respectively, but a small amount of phosphorous (between 3.5 and 28.3 mg P kg-1). These properties are mainly related with the climatic conditions of this region, namely the elevated precipitation. Soils under pines had the most acidic conditions and the lower amount of N, meanwhile the soils under walnuts presented the highest amount of C and organic matter and pH values. The soil under a eucalyptus plantation was the driest (7 % of H2O) vs the moistest with a 36% of H2O under a chestnut plantation. The results regarding the microbial activity showed that soil under broadleaf species (birch, chestnut, walnut and oaks) have bigger respiration rates than soil under pines and specially under eucalyptus. These preliminary results show that the forest management in terms of which tree is cultivated have an impact on the soil general properties and the soil microbial activity and should be considered when elaborating forestry exploitation plans, especially in the current scenario of climate change where the C that healthy forest soils will be able to fix becomes crucial.
How to cite: Barreiro, A., Cela-Dablanca, R., Míguez-González, A., Núñez Delgado, A., Fernández Sanjurjo, M. J., and Álvarez Rodríguez, E.: Impact of different tree species on the soil microbial community under temperate-oceanic climate , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7256, https://doi.org/10.5194/egusphere-egu25-7256, 2025.
Developing a Soil Organic Matter Management Tool for Swiss Farmers
Yafei Li1, Jens Leifeld1, Frank Liebisch1, Stéphane Burgos2, Anina Gilgen1, Simon Baumgartner1, Florian Walder1
1Agroecology and Environment, Agroscope, Zürich, Switzerland
2BFH University of Applied Sciences, Zollikofen, Switzerland
Soil Organic Matter (SOM) is a central feature of healthy agricultural soils. The sustainable management of SOM content is, therefore, helping to secure long-term soil health. Measuring the temporal changes in soil organic matter (SOM) content in the field is a time-consuming, resource-intensive, and costly process. Consequently, numerous models and tools have been created to simulate the dynamics of SOM content in soils. In Switzerland, for example, humusbilanz.ch is a tool designed to assist farmers in managing SOM by calculating the carbon inputs and outputs specific to their farms. As our understanding of soil organic carbon processes has deepened considerably in recent years, we aim to leverage established SOM models, such as RothC, DayCent and AMG, to enhance the Swiss SOM management tool. The tool aims to provide Swiss farmers with a reliable means to assess parcel-specific SOM management by estimating long-term SOM dynamics and evaluating the influence of agricultural practices on SOM content. The tool will be particularly designed for practical use, incorporating commonly available data to minimize input requirements for farmers. It should ultimately serve as a critical reference for farmers' intended practices, fostering sustainable soil management and supporting national agricultural goals.
How to cite: Li, Y., Leifeld, J., Liebisch, F., Burgos, S., Gilgen, A., Baumgartner, S., and Walder, F.: Developing a Soil Organic Matter Management Tool for Swiss Farmers, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8049, https://doi.org/10.5194/egusphere-egu25-8049, 2025.
The ReCROP project, funded by the PRIMA-Med programme, focuses on the development of sustainable agricultural production systems through the combined use of biotechnological tools and environmentally friendly agronomic practices to enhance soil functions and health.
As part of this project, a PGP bacterial strain was used as a bioinoculant in a vineyard of the Mencía variety, located within the DO Ribeiro region (Galicia, NW Spain). This study presents the results of bioinoculation performed over two consecutive cropping seasons, 2023 and 2024. At the harvest, soil and grape samples were collected from both non-inoculated and inoculated vines. Soil analysis included general characterization, determination of labile C compounds, C and N mineralization, and the measurement of several enzymatic activities. Must was analyzed for pH, sugar content, and organic acids.
The bioinoculation led to an increase in labile C compounds, enhanced N mineralization, and stimulated several enzymatic activities. Additionally, the must composition was altered by the bioinoculant, which induced increases in citric, succinic, malic, and tartaric acids.
Acknowledgements: The research was funded by the project PRIMA ReCROP Bioinocula and CROPping systems: an integrated biotechnological approach for improving crop yield, biodiversity and REsilience of Mediterranean agro-ecosystems. Ref PCI2021-121981/ AEI /10.13039/501100011033
How to cite: Prieto-Fernández, Á., Pereira, S., Rodríguez-Garrido, B., Sousa, A. S., González-Prieto, S., Castro, P., and Trasar-Cepeda, C.: Application of a PGP Bacterial Bioinoculant in a Vineyard: Impact on Soil Biochemical Properties and Must Composition, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12784, https://doi.org/10.5194/egusphere-egu25-12784, 2025.
Our research team is participating in the ReCROP project, funded by the PRIMA-Med program, which focuses on developing and evaluating sustainable soil management practices. The project aims to reduce reliance on inorganic fertilizers and pesticides, prevent soil erosion, maintain or restore soil organic matter, and support the restoration of soil biodiversity.
The temperate-humid zone of Spain is predominantly focused on livestock production, with forage maize being one of the main crops. An alternative practice proposed for this crop is its rotation with turnips (Brassica rapa L. var. rapa) as green manure. Turnips might offer multiple benefits: i) prevent the soil from remaining bare between harvest and sowing, ii) enrich the soil with minerals and organic matter, and iii) provide biofumigant properties through the release of thioisocyanates during the decomposition of the glucosinolates contained in their biomass.
In 2021, a field experiment was established to assess the impact of turnip green manure on soil functioning and soil health. Six plots were established: three with conventional forage maize cultivation and three with maize planted after turnip green manure incorporation. The traditional crop rotation system of the region, consisting of one year of maize followed by three years of ley grassland, was followed. Soil properties were monitored over three years—during maize cultivation in 2021 and ley grassland in 2022 and 2023. Soil samples (0-10 cm) were collected in late spring each year and analyzed for biochemical, physical, and chemical properties. This study presents the results on hydrolytic enzyme activities (C, N, P, and S cycles), dehydrogenase activity, and hot-water soluble carbon forms (carbohydrates and phenolic compounds).
In the first year, when the soils were under maize cultivation, all biochemical properties showed higher values in the soil under conventional cultivation compared to the soil amended with green manure. Unexpectedly, the same was observed for organic matter content. However, over time, and as the soils transitioned to grassland cultivation, all biochemical properties tended to level out. When activities are expressed per unit of carbon, they initially follow the same pattern, being higher in conventionally managed soil than in soil amended with green manure (except for phosphomonoesterase and cellulase, which exhibit similar values in both soils). However, over time, this trend tends to reverse. This could reflect differences in agricultural practices resulting from the incorporation of green manure and the distinct practices between the maize and grassland cultivation phases, highlighting the sensitivity of the measured parameters to variations in agricultural soil use and management. However, to better understand the underlying causes of these differences, the study will continue into the next phase, when the soils will return to maize cultivation.
Acknowledgements: The research was funded by the project PRIMA ReCROP Bioinocula and CROPping systems: an integrated biotechnological approach for improving crop yield, biodiversity and REsilience of Mediterranean agro-ecosystems. Ref PCI2021-121981/ AEI /10.13039/501100011033
How to cite: Trasar-Cepeda, C., Rodriguez-Garrido, B., González-Prieto, S. J., and Prieto-Fernández, Á.: Use of turnip as green manure in a rainfed forage maize-grass ley rotation system: evolution of several soil biochemical properties, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13205, https://doi.org/10.5194/egusphere-egu25-13205, 2025.
Microplastics can seriously disrupt soil carbon (C) and nitrogen (N) biogeochemical cycling in agroecosystems, strongly influencing crop growth and quality. However, our mechanistic understanding of how microplastics affect these cycles remains poorly understood. Specifically, direct in situ measurements in greenhouse and field settings are often impractical. However, lab-based and ex-situ measurements can train machine learning models to develop mechanistic understanding of microplastic behaviour. Thus, we aim to train and test the gradient boost regression (GBR) model to estimate the effects of key microplastic properties on C and N cycling and subsequently on plant biomass. The role of soil type in controlling the microplastics effects was also estimated. During prediction, datasets from published experiments (n = 52) were divided into a ratio of 80:20 for training and testing the model. GBR prediction showed R2 values ranged between 57% to 99% and MSE values ranged between 0 to 0.09 for the contents of dissolved organic carbon (DOC), soil organic carbon (SOC), soil organic matter (SOM), ammonium (NH4+), and nitrate (NO3-), emissions of CO2 and N2O. Overall, there was distinct effects of microplastic properties on soil C pools. Microplastic size contributed 34% in altering DOC while the maximum CO2 emissions (39%) were altered by microplastics incubation period in soil. However, microplastic shape contributed 47 to 60% to SOC and SOM. Microplastic size strongly altered NH4+ and NO3- by 36 to 51% in microplastic polluted soils resulting in the highest N2O emission. Plant biomass was strongly (76%) affected by microplastic types. Our results conclude that GBR model appeared a powerful machine learning tool for predicting the impacts on C and N cycling as well as plant performance following microplastic pollution. As microplastic pollution is increasing in soils globally, there is an urgent need to implement and strengthen such tools in modern research to tailor sustainable solutions.
How to cite: Iqbal, S.: Predicting microplastic impacts on carbon and nitrogen cycling in agroecosystems using Gradient Boost Regression (GBR) modeling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14027, https://doi.org/10.5194/egusphere-egu25-14027, 2025.
Soil is the largest carbon (C) reservoir in terrestrial ecosystems and soil organic carbon (SOC) is the basis for soil’s biodiversity, health and fertility. So, measurement of SOC becomes necessary for sustainable soil ecosystem management. However, lab based conventional method to measure the SOC is time and energy consuming. Also, there is a health risk because of the hazardous chemicals used in the soil analysis. To overcome such problems, remote sensing (RS) imagery data products have been used to estimate the SOC. Among all the optical RS data sources used in soil studies, Sentinel-2 (S2) Multispectral imagery (MSI) data has been proved to be the best by many of the researchers because of its unique spectral features. However, S2 along with a radar data source such as Sentinel-1(S1) gives more accurate results. Therefore, the main objective of our study was to estimate the SOC using S2 MSI and S1 SAR-C data in the Western catchment of Chilika lagoon, which is one of the first Ramsar sites in India. To achieve this, 167 surface soil samples (0-15cm) was collected from the study area for SOC measurement. We used PLSR and three machine learning models such as RF, Cubist and SVR for the prediction of SOC from the RS data source. Model performance, showed that PLSR using the covariate set containing S1, S2 and topographic attributes performed the best in predicting SOC (RMSE = 0.17 and R2= 0.38) among all other models. While, model accuracy reduced slightly (RMSE = 0.16 and R2= 0.31) with only S2 bands data. This indicates that using the S1 data and topographic attributes along with S2 data results in better SOC predictions. However, model performance was moderate to poor. Therefore, more studies would be needed for accurate estimation of SOC.
Key words: Soil organic carbon; Sentinel-2; Sentinel-1; Machine learning
How to cite: Swain, S. R., Purushothaman, N. K., and Das, B. S.: Soil organic carbon measurement and modelling at regional scale using Sentinel-1/2 data based on machine learning approaches, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16870, https://doi.org/10.5194/egusphere-egu25-16870, 2025.
Soil aggregates are considered the fundamental building blocks of soil structure (Reeves et al., 2019), and their formation is closely tied to the content of soil organic carbon (Bronick and Lal, 2005). As key indicators of soil quality, soil aggregates play a critical role in determining soil health and functionality.
Previous studies have shown that macro-aggregates tend to exhibit higher rates of organic carbon mineralization and microbial respiration compared to micro-aggregates (Rabbi et al., 2014). However, conflicting results have emerged from other research, suggesting that micro-aggregates may harbor higher levels of microbial activity (Zhang et al., 2013). These inconsistencies highlight the need for further investigation into the role of different aggregate fractions in soil microbial dynamics and activity.
The major objectives of the present study were as follows (i) Identification of bacterial composition by analyzing, both taxonomically and functionally, in two distinct soil aggregate sizes (2-4 mm and 1-2 mm), (ii) evaluate the aggregate stability analysis in the 1-2 mm fraction, and (iii) investigate the impact of land-use practices such as tree growth and animal grazing in permanent pastures on soil aggregate properties. Additionally, these characteristics were assessed at two different soil depths: 0-15 cm and 15-30 cm
The analysis was conducted in a silvopastoral system located in Boimorto (A Coruña, Galicia, NW Spain), an area with a mean annual temperature of 12.6 °C and 1898 mm of mean annual precipitation. The study focused on Juglans regia plantations owned by the private company Bosques Naturales S.A., including hybrid walnut trees (Juglans major MJ 209 x Juglans regia) planted at densities of 6 m x 6 m (277 trees ha⁻¹) and 4m x 4m (and 625 trees ha-1). For controlling weeds grow the owner included extensive sheep grazing. Composite soil samples were collected along the tree line, in the open pasture area, and within grazing exclusion chambers across three replicate plots to assess their contribution to reducing soil degradation.
Results on soil aggregate stability, soil enzymatic activities (involved N, C and P cycles) and taxonomic composition of bacterial communities in the different locations sampled and aggregates sizes will be presented.
Acknowledgments: This study was funded by the “Ramón y Cajal” fellowship (ref: RyC 2021-615 033370-I) financed by the “Ministerio de Ciencia Innovacion y Universidades” (Spain) and the Regional Goverment of Galicia (Programa de consolidación de unidades de investigación competitivas del SUG. Proyectos de excelencia ED431F 2024/024 Xunta de Galicia)
References
Bronick, C.J., Lal, R., 2005. Soil structure and management: a review. Geoderma. 124 (1–2), 3–22.
Rabbi, S.F., Wilson, B.R., Lockwood, P.V., Daniel, H., Young, I.M., 2014. Soil organic carbon mineralization rates in aggregates under contrasting land uses. Geoderma. 216, 10–18.
Reeves, S.H., Somasundaram, J., Wang, W.J., Heenan, M.A., Finn, D., Dalal, R.C., 2019. Effect of soil aggregate size and long-term contrasting tillage, stubble and nitrogen management regimes on CO 2 f luxes from a Vertisol. Geoderma. 337, 1086–1096.
Zhang, S., Li, Q., Lü, Y., Zhang, X., Liang, W., 2013. Contributions of soil biota to C sequestration varied with aggregate fractions under different tillage systems. Soil Biol. Biochem. 62, 147–156.
How to cite: Álvarez-López, V., Munetiko, Y., Mosquera-Losada, R., and Figueiredo, T.: Are variations in soil aggregate sizes and soil depth key drivers of soil biological properties?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17949, https://doi.org/10.5194/egusphere-egu25-17949, 2025.
The sustainability of agroecosystems is critical for balancing environmental health with productive crop yields. Sustainable management practices, including crop rotation and organic amendments, have been identified as strategies to enhance soil health, reduce greenhouse gas emissions, and improve long-term agricultural productivity. Carbon cycling plays a pivotal role in maintaining soil fertility and regulating atmospheric CO₂ levels, making it a key component of climate-smart agriculture. Additionally, soil water retention is a crucial factor influencing crop productivity, water use efficiency, and resilience to climate hazards such as drought and extreme rainfall. Practices that influence carbon inputs and outputs in soil systems are essential for mitigating climate change while ensuring resilient crop production. Enhancing soil structure and organic matter content through sustainable practices can improve water holding capacity and reduce vulnerability to climate variability. This study evaluates the effects of different cropping systems (crop rotation vs. monoculture) and different soil amendments (biochar vs. manure vs. control) on soil CO₂ emissions and soil water content in Stagnosols at the Marija Magdalena site in Croatia during 2024. The experimental design consisted of two cropping systems: a maize monoculture (upper block) and a crop rotation system with field pea (lower block). Three amendment treatments were applied in both systems: manure (40 t/ha), biochar (40 t/ha), and a control with no amendments. Each treatment was replicated three times. Soil CO₂ emissions and soil water content were measured monthly, with detailed analyses focusing on three representative dates: March 22, May 18, and August 28. The results demonstrated significant variations in CO₂ emissions and soil water content based on both cropping system and amendment type. In the maize monoculture, manure application led to the highest emissions, while biochar showed a moderating effect compared to the control. Conversely, the crop rotation system exhibited generally lower emissions across all treatments, with biochar further reducing CO₂ fluxes. Seasonal variation was evident, with peak emissions observed during the growing season. The crop rotation system consistently maintained higher soil moisture levels, supporting better water availability throughout the season. Implementing crop rotation and biochar amendments effectively mitigates soil CO₂ emissions and enhances soil water retention in Stagnosols. These findings highlight the dual benefits of sustainable soil management in promoting carbon sequestration and improving drought resilience, contributing to resilient agroecosystems under changing climatic conditions.
Keywords: monoculture, farmyard manure, biochar, soil respiration, sustainable agriculture, carbon cycling, climate change mitigation, water conservation
Acknowledgments: This work was supported by the Partnership for Research and Innovation in the Mediterranean Area (‘the PRIMA Foundation’) through the “Soil Health and Agriculture Resilience through an Integrated Geographical information systems of Mediterranean Drylands” project (grant agreement number 2211) (SHARInG-MeD).
How to cite: Bogunovic, I., Matisic, M., Kisic, I., Kljak, K., and Galic, M.: Cropping systems and amendment management impact on temporal soil carbon emissions and soil water content variability in Croatian croplands, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19169, https://doi.org/10.5194/egusphere-egu25-19169, 2025.
Selected soil health indicators of Chernozem soils under different agricultural land use in a suburban area were studied and compared. In the topsoil (0–40 cm) bulk density (BD), total organic carbon content (TOC), total nitrogen (TN) content, ammonium lactate-extractable P, K, Ca, Mg contents were measured, and microbiological communities were characterized by phospholipide-phatty acid (PLFA) markers. Three study sites were on croplands, with different land use legacies, one in complex cultivation area, one in fallow land, and one grassland was serving as referential site, considered to be in close to natural state. We found significantly higher BD, decreased TOC and TN content in the cropland sites compared to the reference site. P-AL content showed higher values at the natural site, but Ca-AL, Mg-AL and K-AL content of the cultivated and mineral-fertilized agricultural sites were higher, or equal compared to the grassland site. Total microbiological activity correlates significantly positively with TOC and TN content and negatively with the BD. Sites with perennial vegetation cover and higher biodiversity showed higher microbiological activity, and for the arbuscular mycorrhiza fungi, actinobacteria and anaerobe bacteria the differences are significant.
How to cite: Novák, T. J., Béni, Á., Kremper, R., Juhász, E., Sándor, Z., and B. Kovács, A.: The effect of increasing land use intensity on soil health indicators of Chernozem soils in a suburban area of Hajdúság, Eastern Hungary, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20292, https://doi.org/10.5194/egusphere-egu25-20292, 2025.
Understanding the comparative influence of agricultural management intensity and regional-scale geographic factors on the level of soil nutrients and microbial activities in Irish grasslands is a key research gap. To address this, a regional-scale survey was undertaken, spanning two Irish regions (‘Region’), one favourable to agricultural productivity (South-East) and one less-favourable (West). From each region, soil samples were taken from three different grassland management intensities (‘Manage’, n=12); intensive, low-input grassland and extensively-grazed pasture, a total of 72 sites. Statistical differences were tested via nested ANOVA. Potassium (K), sulfur (S) and phosphorus (P), essential macronutrients for plant growth, responded significantly to ‘Manage’ (all p < 0.01), but not to ‘Region’ (p > 0.05). There was a significant effect of ‘Manage’ on K, S and P in the favourable region, with this effect also seen for K and S in the less-favourable region (all p < 0.05). These effects were driven by higher values in intensive grasslands. A significant effect of ‘Manage’ was also seen on the activity of four carbon-cycling enzymes; β-glucosidase, chitinase, cellobiohydrolase, and β-xylosidase (all p < 0.05), with no significant effect of ‘Region’ observed (p > 0.05). The enzymes β-glucosidase and β-xylosidase were significantly influenced by ‘Manage’ in both the favourable and less-favourable regions, with higher activity levels seen in intensive grasslands compared to extensively-grazed pasture in each instance (all p < 0.05). These results highlight the stronger influence that agricultural management intensity has on soil nutrients and microbial activities in Irish grasslands compared to regional-scale geographic factors.
How to cite: Burke, K., Schmalenberger, A., Schulz, S., Luescher, A., Brennan, F., and Fox, A.: Agricultural management intensity a stronger driver of soil nutrients and enzymatic activities than regional-scale geographic factors in Irish grasslands., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1473, https://doi.org/10.5194/egusphere-egu25-1473, 2025.
Soil micro-food webs are essential in maintaining soil health through individual life activities and intra- and interspecific interactions. However, black soils degradation destabilizes soil micro-food webs and causes loss of soil function. Although vegetation restoration is considered the most effective method for sustainable management of soil health and ecosystems, the existing knowledge on black soils - poplar - microfood web interconnections is still limited. In this experiment, we investigated the effects of Populus simonii × P. nigra (P. xiaohei) on soil biomes in different levels of degraded black soils, in particular amplifying the interactions between four biomes's key taxa and differential metabolites. We characterized soil chemical and enzyme activity properties, community composition of soil biomes, and metabolic profiles. We found that poplar could increase the diversity of four soil biomes in degraded black soils and promote soil micro-food web stability. In addition, P. xiaohei induced consistent changes in high trophic level protists and nematode communities in different degrees of degraded black soils. With deeper degradation, the survival strategy of P. xiaohei shifted from acquisition to conservation, and the driving microorganisms shifted from a resource acquisition strategy to a community with high growth potential. Futhermore, P. xiaohei enhanced soil metabolic processes by driving different trophic-level taxa in the soil micro-food web, and similar metabolites were accumulated to ultimately contribute to soil nutrient cycling. These findings provide insights into how poplar affects changes in soil biological and metabolic characteristics in degraded black soils and are critical for developing specific components of vegetation measures to protect the health of degraded black soils.
How to cite: Yang, J. and Gu, H.: Metabolic and Biological Responses of Degraded Black Soils to Poplar Plantation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2987, https://doi.org/10.5194/egusphere-egu25-2987, 2025.
Mining activities significantly disrupt land morphology, soil structure and ecosystem functioning, making effective rehabilitation strategies crucial for ecosystem restoration. In Morocco's phosphate mining regions, understanding the impact of rehabilitation strategies is essential for sustainable land management. This study evaluates the effectiveness of tree plantations in rehabilitating phosphate mining lands in Morocco by examining their impact on key soil properties. We compared soil properties between mined and unmined sites using a sampling design that considered five tree species (Eucalyptus sp., Ceratonia siliqua, Olea europaea, Argania spinosa, and Schinus molle), three proximities to the tree stems (0.5 m, 1.5 m, the intertree zone), and three soil depths (0–10 cm, 10–30 cm, 30–60 cm). Soil samples were also collected from non-planted mined areas and unmined sites as controls.
Our results revealed significant differences between mined and unmined soils, with tree plantations markedly increasing soil organic carbon (SOC) and cation exchange capacity (CEC) compared to controls. SOC displayed a spatial gradient, decreasing with distance from tree stems and increasing in the topsoil compared to deeper layers. Among tree species, olive trees (O. europaea) demonstrated the highest SOC enhancement in disturbed soils, with SOC levels near tree stems of 12.1 g/kg, and of 11.1 g/kg in the intertree zone, representing increases of 83%, and 68%, respectively, compared to control (6.6 g/kg). Similarly, under false pepper plantations (S. molle), SOC in the topsoil layer (0–10 cm: 10.7 g/kg) was significantly higher than deeper layers (8.0-8.2 g/kg). CEC in rehabilitated mined soils improved modestly, with the highest increase of 1.66 meq/100g observed in young false pepper stands compared to controls. Soil pH remained relatively stable, with minor decreases of up to 0.28 units, particularly under mature eucalyptus (Eucalyptus. sp.) and carob (C. siliqua) plantations. However, bulk density remained higher in mined soils (1.91 g/cm³) compared to unmined soils (1.35 g/cm³), reflecting incomplete soil structure recovery. In the other hand, natural soils outperformed rehabilitated mined soils in chemical properties, exhibiting higher SOC levels (12.4 ± 3.0 g/kg) and CEC (10.79 ± 6.40 meq/100g) compared to mined soils (8.5 ± 4.8 g/kg SOC and 4.99 ± 2.11 meq/100g CEC). The study underscores the importance of species selection in mine rehabilitation programs, particularly in semi-arid regions. By demonstrating the superior performance of certain tree species in enhancing soil properties, our results provide evidence-based recommendations for optimizing restoration strategies in post-mining landscapes in Morocco and similar semi-arid environments.
Keywords: Soil rehabilitation, Phosphate mining lands, Tree plantations, Semi-arid regions, Soil organic carbon (SOC)
How to cite: Elkhatri, N., Metougui, M. L., and Chirinda, N.: Evaluating the Impact of Tree Plantations on Soil Rehabilitation in Semi-Arid Phosphate Mining Lands of Morocco, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6195, https://doi.org/10.5194/egusphere-egu25-6195, 2025.
Soil plays a key role in storing organic carbon, which is a critical indicator of soil fertility and overall quality. Understanding the spatial distribution of soil organic carbon stock (SOCS) and its influencing factors is essential for promoting sustainable land management. This study applied four machine learning models such as Random Forest (RF), k-nearest neighbors (kNN), Support Vector Machine (SVM), and Cubist to enhance SOCS prediction in the Srou catchment, part of the Upper Oum Er-Rbia watershed in Morocco. A dataset of 120 samples was collected, with 80% used for model training and 20% for validation. Boruta’s feature selection and multicollinearity tests identified nine key factors influencing SOCS. Spatial maps generated from the models were validated using statistical indicators. The RF model showed the highest predictive accuracy (R² = 0.76, RMSE = 0.52 Mg C/ha), followed by SVM and Cubist, while kNN had the lowest performance (R² = 0.31, RMSE = 0.94 Mg C/ha). Key predictors for SOCS included bulk density, pH, electrical conductivity, and calcium carbonate. The proposed machine learning approach demonstrates significant potential for mapping SOCS in similar semi-arid environments.
How to cite: Mosaid, H., Barakat, A., and John, K.: Using Machine Learning Algorithms for Spatial Prediction of Soil Organic Carbon Based on Environmental Variables and Soil Physicochemical Parameters in the Mediterranean Region, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13262, https://doi.org/10.5194/egusphere-egu25-13262, 2025.
Phosphorus (P) is a critical nutrient for vineyard However, the involvement of roots microbiome in P uptake, especially under deficiency conditions remain poorly understood. This study examined the impact of different P application levels on two table grape cultivars: the early-bearing green cultivar 'Early Sweet' and the late-bearing purple cultivar 'Crimson.' Grapevines were cultivated in 500 L lysimeters containing perlite as a growth medium and subjected to three P fertigation treatments (1, 5, and 15 ppm P) over three years. Results showed that higher P uptake efficiency occurred at 1–5 ppm P compared to 15 ppm P. Phosphorus application levels were also reflected in the P concentrations of diagnostic leaves. Additionally, DNA extracted from the rhizosphere, and full-length 16S microbiome analysis, revealing significant correlations between P concentrations and shifts in microbial community composition at the genus level. These findings enhance our understanding of the interplay between phosphorus fertilization, root microbiomes, and nutrient uptake in table grapes, offering valuable insights for sustainable vineyard management.
How to cite: Dawas, A. and Dag, A.: Long-Term Effect of Phosphorus Availability on Table Grapes' Root Microbiome and Phosphorus Uptake, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20417, https://doi.org/10.5194/egusphere-egu25-20417, 2025.
Preservation and recovery of soil health have become one of the priorities of European environmental policies. In this context, the EU Soil Protection Strategy sets concrete targets to be achieved by 2030, including improving soil quality in those agricultural systems that have been impacted by intensive agricultural practices. Aforestation of agricultural land is usually considered an approach with positive effects in many soil indicators, e.g., soil carbon stocks, since it is usually consider a viable carbon sequestration strategy in carbon stock markets. However, long-term effect of afforestation on soil properties can vary from place to place, according to differences in environmental conditions like soil types or climate. Moreover, an increase of carbon stocks does not necessarily lead to an improvement of other soil health indicators. Typically, soil health indicators are often measured only at the upper 10 - 20 cm, while deeper layers are rarely evaluated. Thus, the objective of the present work was to analyze long-term effects of land use transformations from a grazing pasture to eucalyptus plantations on diverse soil health indicators including C content, enzymatic activity and soil respiration.
The study was conducted in a small catchment located in Galicia (NW of Spain), and covers an area of 10.7 ha. During more than 30 years, some plots were dedicated to cattle grazing, while other were cultivated annually with maize. In 1999, part of the catchment was transformed into a eucalyptus plantation, while other part was dedicated to the annual cultivation of maize for forage using conventional methods. As a result, 4 treatments were identified in the catchment, including the two historical dedications and the two current ones. In 2024, soil samples were collected in 72 locations inside the catchment, at three different depths: 0-30 cm, 30-60 cm and 60-90 cm. Measured soil health indicators included enzymatic enzymatic activities, soil respiration and total soil carbon. These properties were interpolated for the whole catchment using geostatistics, in order to identify their spatial variability and their relation with past and present land uses. Results will provide a deeper understanding of the impact of long-term changes in land use at different depths.
Acknowledgements:
This study was funded by the Ministry of Science, Innovation and Universities of Spain under the project “Gesta Race” (TED2021-130315B-I00) and the “Ramón y Cajal” fellowship (RyC 2021-615 033370-I), and by the Regional Govermnent of Galicia (project ED431F 2024/024 Xunta de Galicia).
How to cite: Lado, M., Munetiko, Y., Royer, A. C., Martínez-Picado, S., García-Tomillo, A., Vidal-Vázquez, E., and Álvarez-López, V.: Spatial distribution of soil health indicators at different depths after 30 years of changes in land use in a small catchment of NW Spain, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21436, https://doi.org/10.5194/egusphere-egu25-21436, 2025.
Posters virtual: Tue, 29 Apr, 14:00–15:45 | vPoster spot 3
EGU25-20998 | Posters virtual | VPS14
Biostimulant and biofertilizer functions of a bacterial consortia in Lolium perenneTue, 29 Apr, 14:00–15:45 (CEST) | vP3.6
The use of bioinoculants was emerging as an effective strategy to increase soil productivity, particularly in degraded areas where nutrient scarcity limits the potential of livestock systems. Inoculation with plant growth-promoting bacteria (PGPB) provides stimulation functions through the synthesis of phytohormones and available nutrients. Among PGPBs, the genus Azospirillum is known for its biostimulant capacity, while the genus Herbaspirillum includes nitrogen-fixing bacteria. Additionally, microorganisms from the genus Trichoderma are recognized for their ability to solubilize phosphorus. This study evaluates the efficacy of a bacterial consortium combining Azospirillum brasilense (A), Herbaspirillum seropedicae (AH), and Trichoderma haziarum (AT) to determine their potential as biostimulants and biofertilizers in Lolium perenne, a forage species with high nutritional value. The methodological set up included a laboratory phase where the microorganisms' ability to synthesize phytohormones was measured (Indole-3-acetic acid (IAA), cytokinins: trans-zeatin (ZT), trans-zeatin riboside (ZTR), and abscisic acid (ABA)). Also the nitrogen-fixing potential of H. seropedicae was evaluated using the acetylene reduction assay (ARA), and the phosphate-solubilizing capacity of T. harziarum was assessed using a semi-quantitative technique to measure solubilization halos. In a second phase, L. perenne seeds were sown in commercial substrate inoculated with A, AH, AT, and a control treatment (C). The following parameters were recorded: weekly longitudinal growth (WLG), at 30 days, total chlorophyll content (TCh), percentage of coverage (PC), dry weight of aerial biomass (ABiom), and root biomass (RBiom). The results showed detectable levels of growth-regulating hormone synthezed for all the microorganisms evaluated. Additionally, H. seropedicae exhibited nitrogen-fixing activity with a value of (8.33 ± 0.9) nmol C2H4 plant⁻¹ h⁻¹, while T. harziarum displayed a pH indicator shift, indicating a positive result for phosphorus solubilization. The growth parameter data demonstrated early seed emergence in inoculated treatments, with greater grass height (WLG) observed in co-inoculated treatments (C: 5; A: 7; AT: 8.5; AH: 8) cm. The consortia also showed higher root biomass development (RBiom: C: 0.76; A: 0.86; AT: 1.10; AH: 0.95) g and percentage of coverage (PC), with the H. seropedicae treatment standing out (C: 45.5%; A: 62.8%; AT: 60%; AH: 71.3%). In aerial biomass (ABiom, C: 0.89; A: 1.15; AT: 1.21; AH: 1.3 g) and total chlorophyll content (TCh, C: 0.68; A: 0.84; AT: 0.73; AH: 0.75 mg/g). Co-inoculated treatments did not show significant differences. Inoculations improved all the growth parameters studied; however, co-inoculations optimized the benefits, likely due to the combined potential to provide regulatory hormones and nutrient availability functions. In this regard, the AH combination stood out in the PC parameter, possibly due to the nitrogen-fixing ability of H. seropedicae. We conclude that joint inoculations should be further studied to optimize strategies for crop management.
How to cite: Cristóbal-Miguez, A. E. J., Galelli, M. E., Paz-Gonzalez, A., Avram, I. L., García Guzmán, E., Alegre, A. B., Curá, A. J., García, A. R., and Sarti, G. C.: Biostimulant and biofertilizer functions of a bacterial consortia in Lolium perenne, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20998, https://doi.org/10.5194/egusphere-egu25-20998, 2025.
