Soil erosion is a global ecological and environmental issue. To improve the accuracy of regional soil erosion estimation, this study investigates the impact of different sampling densities on soil erosion estimation at the watershed scale using the CSLE model, taking the Beiluo River Basin as an example. Based on the CSLE model, the study compares the effects of four sampling densities (0.0625%, 0.25%, 1%, and 4%) on soil erosion estimation in the study area using two methods: full coverage calculation and unit interpolation extrapolation. The differences and main causes of these effects are analyzed to identify the appropriate sampling density and soil erosion estimation method for the watershed. This provides a theoretical basis for the selection of field sampling density and methods in regional soil erosion dynamic monitoring. This study extracted land use and soil and water conservation measure information through remote sensing interpretation of sampling survey units at different densities. Based on the CSLE model, soil erosion rates were calculated for the watershed. The results indicate that both the full-coverage calculation method and the sampling survey method are capable of capturing the macro-scale patterns of soil erosion within the watershed. The full-coverage calculation method provides complete spatial coverage, effectively represents the spatial distribution characteristics of regional soil erosion, and is relatively insensitive to variations in sampling density. However, due to limitations in the accuracy of model input data sources, this method tends to overestimate soil erosion rates. In contrast, the sampling survey method utilizes higher-precision input factors, resulting in more accurate soil erosion assessments. Nevertheless, its estimation results are strongly influenced by sampling density and the choice of interpolation methods. In summary, the sampling survey method better reflects soil erosion variations across different topographic conditions, making it an efficient and practical approach for regional soil erosion investigations.

Keywords：Beiluo River Basin; CSLE model; soil erosion estimation; sampling density; full coverage calculation

How to cite: Wang, M., Zhang, X., Wang, H., Sun, W., Geng, W., and Liu, X.: Soil Erosion Assessment in the Beiluo River Basin Based on the CSLE Model and Sampling Survey Method, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17792, https://doi.org/10.5194/egusphere-egu26-17792, 2026.

Agriculture in semi-arid Mediterranean regions contributes significantly to local food production and rural livelihood.  Nevertheless, it depends strongly on irrigation to sustain crop production and soil fertility. With the terrain complexity present, irrigation can lead to downward and lateral transfer of soil particles and nutrients, thus intensifying and accelerating the complex interplay between leaching and erosion, which in turn, reduce soil productivity and create spatial fertility imbalances. This study addresses the lack of knowledge about these processes to support better soil management in  Bir Bouhouch irrigated perimeter with complex terrain characteristics in northeastern Algeria , which represents a strategic agricultural area mainly producing cereals .The area has been used for intensive agriculture since the expansion of irrigation schemes in recent decades .In This study  the vertical and catenary variability of physicochemical characteristics of soils were examined. Four soil profiles along a toposequence from the summit (P1), to the toeslope (P4) were described and soils samples were collected in different depth to physicochemical characterization (texture, pH and electrical conductivity in water (EC), active lime, organic matter (OM), total nitrogen and extractable phosphorus. All profiles showed alkaline pH (8.10–8.60) with low EC (0.23–0.58 dS/m) that increased progressively from the summit to the teslope as well as with depth. Surface horizons (0- 60 cm) at downslope profiles showed finer textures with transition from silty clay to loamy clay and higher OM contents (up to 17.2 g/kg) compared with the summit (9.00 g/kg), indicating possible downslope colluvial accumulation. Active lime increased but followed a bi-profile sequence along surface (from 55 to 145 g/kg for P1-P2 and from 35 to 105 g/kg for P3-P4) and with depth reflecting a possible carbonate leaching and re-precipitation under alkaline conditions, locally forming caliche horizons. Extractable P concentrations ranged from 0.05 to 0.07 mg/kg and were enriched at lower slope positions at surface horizons. Besides total N (0.8–1.5 g/kg) showed limited vertical and lateral variation. These patterns demonstrate that soil variability along the transect can be mainly controlled by the topography-driven redistribution and carbonate dynamics enhanced by irrigation.

This work was funded by national funds through FCT – Fundação para a Ciência e a Tecnologia, I.P., under the projects UIDB/04129/2020 and UID/04129/2025 (LEAF) and LA/P/0092/2020 (TERRA).

How to cite: Kouider, K., Benhalima, Y., Mazouz, E. H., Santos, E., and Arán, D.: Toposequence-driven variability on soil properties redistribution at irrigated semi-arid landscape, Northeastern Algeria, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14894, https://doi.org/10.5194/egusphere-egu26-14894, 2026.

Soil compaction is commonly viewed by agronomists as an undesirable consequence of intensive agricultural activities arising from heavy machinery or livestock trampling. However, when induced at the bottom of furrows, it might help reduce the water loss during furrow irrigation. As such, understanding of how compaction alters soil hydraulic properties is essential for developing sustainable soil and water management practices. This study aimed to investigate the impact of compaction on soil hydraulic properties of a clay-textured Nitisol. Thirty undisturbed soil samples were collected from a depth of 15 cm in Koga irrigation scheme, Ethiopia, and subjected to five compaction levels: control (0%), 5%, 10%, 15%, and 20% volume reduction, each with six replicates. Saturated hydraulic conductivity was measured using the KSAT® apparatus with the falling head technique, while water retention and unsaturated hydraulic conductivity were measured using the HYPROP® system based on the modified evaporation method. Compaction reduced water retention and hydraulic conductivity, particularly in the wet range up to pF 3. Saturated hydraulic conductivity decreased by 9% to 78% from the lowest to highest compaction level tested. Compaction also increased bulk density (8% – 40%) and relative field capacity (4% – 10%) and decreased total porosity (6% – 33%), macroporosity (28% – 82%), air capacity (25% – 61%), and plant-available water content (8% – 17%). When compared with soil quality thresholds, compaction of 15% or more reduced plant-available water below optimal range (< 0.2 m³ m^-3) and lowered saturated hydraulic conductivity below the threshold (8.64 cm day^-1). While this study was designed to evaluate the efficiency of furrow irrigation subjected to compaction, the findings also emphasize the need for sustainable soil management to improve crop yield and soil resilience.

Keywords: Hydraulic properties, HYPROP2®, KSAT®, Soil compaction, Soil physical quality

How to cite: Yimam, A. Y., Asmamaw, D. K., Chen, M., Tilahun, S. A., Beyene, A. A., Dessie, M., Walraevens, K., Tsegaye, E. A., Frankl, A., and Cornelis, W.: Evaluating the Effect of Compaction on Soil Hydraulic Properties, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-276, https://doi.org/10.5194/egusphere-egu26-276, 2026.

Winter wheat yields are varying by preceding crop as shown for certain preceding crops like wheat itself, winter oilseed rape or different legumes. However, there is hardly any published data on the pre-crop effect of other economically important crops such as sugar beet and silage maize. Further, the mechanisms of the pre-crop effect are partially unknown.

In this study, winter wheat was grown after wheat, winter oilseed rape, sugar beet and silage maize over two winter wheat growing periods (harvest years 2024 and 2025) in a long-term crop rotation trial in Central Germany. Soil mineral nitrogen (SMN) in 0-90 cm soil depth was analyzed at sowing in October, in December, January and February. After the last SMN sampling, plots were split into no (N0) and regular nitrogen fertilization (Nopt). At harvest, grain yield and straw biomass were recorded as well as nitrogen uptake.

Levels of SMN at sowing in October were clearly affected by pre-crop type with higher values after oilseed rape and lowest values after silage maize and sugar beet. In December, SMN levels were similar to October, while in January differences between the pre-crops became smaller and were mostly levelled by February. At N0, in both years, wheat grain yield as well as straw biomass was clearly highest after oilseed rape with up to 100 % more total biomass than after the other pre-crops. Other pre-crops had similar effects on total biomass. At Nopt, differences between the pre-crops were overall much lower, yet highest yields were found after oilseed rape.

December SMN levels correlated with grain yields at N0 over both years, while a similar correlation was even found under Nopt conditions in one of the study years. Thus, it appears nitrogen supply originating from pre-crops affects winter wheat growth. This might be one way pre-crops affect wheat growth beyond regulation of disease pressure.

How to cite: Grunwald, D., Koch, H.-J., and Jacobs, A.: Impact of different pre-crops on soil nitrogen and growth of following winter wheat, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21561, https://doi.org/10.5194/egusphere-egu26-21561, 2026.

Contamination of agricultural soils with heavy metals poses a critical threat to global food security and human health due to their high mobility and long biological half-life. Consequently, there is an urgent need for innovative remediation strategies, such as the development of safe multi-functional soil amendments, that do not disrupt food production. Among various additives, biochar (BC), obtained through the pyrolysis of organic wastes (including agricultural residues), is one of the most extensively studied. BCs can immobilize pollutants due to their developed surface area and abundance of functional groups. Hydrogels (HG) are another type of modifier that can simultaneously immobilize metals and improve the water-holding capacity of soils. Special attention is given to biopolymer-based HGs due to their biocompatibility and biodegradability. Furthermore, nanoparticles (NPs) have been reported to decrease heavy metal toxicity to plants. Thus, in this study, a series of hybrid chitosan-lignin HGs enriched with wheat straw-derived BC and selenium (Se) or copper (Cu) NPs were developed, and their effect on maize germination under water-deficit and cadmium contamination stress was evaluated.

During the study, agricultural soil was modified using 1% (w/w) of the developed HGs: (1) HG filled with BC; (2) HG filled with BC and SeNPs; (3) HG filled with BC and CuNPs; and (4) a combination of HGs (2) and (3). The plant growth experiment was conducted in a growth chamber and included soils contaminated with cadmium (35 mg/kg) and uncontaminated controls. Two weeks after sowing, watering was stopped, to simulate water-deficit conditions, and water evapotranspiration was monitored gravimetrically. After one week, seedlings were collected, and their fresh/dry mass and length were determined.

A decrease in evapotranspiration rates was observed for the soil modified with HGs. For example, the control soil lost 68 g/pot of water during 7 days, while the soils modified with HG/BC and HG/BC/SeNPs lost 59 and 57 g, respectively. Additionally, these HGs demonstrated a stimulatory effect on maize growth. The average shoot height increased from 18.3 cm in the control to 20.9 cm, and dry mass rose from 0.029 g to 0.037 g for the soils modified with HG/BC and HG/BC/SeNPs. The root dry mass also increased in both cases. Moreover, under cadmium contamination, both hydrogels neutralized the negative impact of the heavy metal on shoot growth. In contrast, HG filled with BC and CuNPs had an inhibitory effect on plant biomass growth. The mixture of hydrogels demonstrated a moderated effect on plant germination.

Acknowledgements: The research was funded by the Polish National Agency for Academic Exchanges under the Strategic Partnerships Program (BNI/PST/2023/1/00108) and the National Science Centre (2024/08/X/NZ9/00561).

How to cite: Siryk, O. and Szewczuk-Karpisz, K.: Chitosan-lignin hydrogels enriched with biochar and Se/Cu nanoparticles for the mitigation of cadmium and drought stress in maize, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17043, https://doi.org/10.5194/egusphere-egu26-17043, 2026.

The characterization and monitoring of soils and groundwater affected by non-aqueous phase liquids (NAPLs) remains a challenge due to the difficulty and high costs associated with their spatial delineation through intrusive methods (e.g., core-recovery drilling). The radon deficit technique is a promising screening method that enables the identification of potentially impacted areas based on the ubiquity of this gas, its operational simplicity and capability for rapid in situ measurement, and its preferential partitioning into NAPLs. However, subsurface sampling does not allow discrimination between impacts occurring in the vadose zone and those in the saturated zone. This work proposes the application of machine learning algorithms (Random Forest) as a tool to analyze the spatial variability of radon activity data in contaminated sites, with the aim of quantitatively determining their dependence on information related to contamination processes in both the vadose and saturated zones, as well as evaluating the ability of these algorithms to assess  the potential of the radon deficit technique for monitoring remediation processes in NAPL-impacted sites.
This study uses information collected during sampling campaigns conducted at a NAPL-impacted site at various depths within the vadose and saturated zones. The collected data (radon activity, lithological characteristics, and organic contamination information) were integrated into a machine learning algorithm that enabled the spatial analysis of the joint behavior of the variables, resulting in a predictive model to assess the potential of the radon deficit technique for monitoring remediation processes.
The results suggest that the radon deficit is a useful screening and monitoring method for NAPL-impacted sites, and demonstrate the value of machine learning not only as a predictive tool but also as an analytical resource to interpret complex relationships and validate indirect environmental monitoring techniques.

How to cite: Montalvo Piñeiro, J., Barrio Parra, F., Serrano García, H., Izquierdo Díaz, M., De Miguel García, E., and Lorenzo Fernández, D.: Potential of Radon Deficit as a Monitoring Tool in Organic Soil Remediation: A Machine Learning-Based Predictive Approach, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-294, https://doi.org/10.5194/egusphere-egu26-294, 2026.

The recovery of sulfide mine areas using designed Technosols and vegetation is often evaluated under controlled conditions, whereas field-scale evidence remains scarce. The first pilot (1.5 ha) with designed Technosols, produced from agro-industrial and urban wastes, was installed at the São Domingos mine (Iberian Pyrite Belt, Portugal)in two areas subject to continuous leaching of acid mine drainage, for environmental recovery purpose. An adjacent area without Technosol was used as control. The areas with and without Technosol were sown with a commercial herbaceous mixture including some autochthonous shrub species. After 4.5 years from recovery system (Technosol+vegetation) installation, the physicochemical quality of soil (pH, EC, fertility, nutrients and potentially hazardous elements-PHE availability) and the vegetation status (species composition, % cover, total biomass, seed bank diversity) were evaluated. A total of 25 randomly distributed sampling points were established with both soil and vegetation samples collected at each point (T1-Technosol area: 15, T2-Technosol area 2: 5, control: 5). The aim of the study was to evaluate the chemical quality of soil and vegetation status in the Technosol and control areas at long-term.

The application of the designed Technosol significantly improved the soil quality of the mine area compared to the control, increasing pH (from 4.08 to 7.76) and organic C content (62.49 vs. 2.42 g kg⁻¹). The available fractions of macronutrients were higher in the Technosols areas while available PHE amounts were approximately 73% lower than in the control area. Vegetation reflected soil improvement, with 20 taxa (10 families) registered and higher family richness in the Technosol areas (10 vs. 4) .Technosols areas were dominated by Poaceae and Asteraceae showing almost complete soil cover (~96%). The control area was barely covered (<9%) mainly by Poaceae with Linaceae and Brassicaceae. The soil seed bank showed higher plant diversity in Technosols samples (8 families), while no germination was recorded in the control (assay conducted under controlled conditions for 3 months).

Comparing the two areas with Technosol, no remarkable differences was obtained for pH (7.75–7.78 and low PHE availability but EC EC (500.6 vs. 236.4 µS/cm), available P content (321.7 vs. 191.1 mg kg⁻¹) and CEC (61.1 vs. 46.6) were different. Despite the application of similar Technosol and seeding, the plant communities diverged for the plant diversity (8 families vs. 5) and dominance of grasses. Although the vegetation cover and biomass amounts were similar between the Technosol areas, a differentiation of the carbon stock obtained (948.8 vs. 645.2 g C/m^-2). Seed bank family richness was similar (6 families each) but composition differed Poaceae, Asteraceae, Urticaceae and Apiaceae families were common, while presence of Brassicaceae and Solanaceae or Malvaceae and Amaranthaceae depended on the Technosol area. This field case study provides a practical workflow linking soil improvement, contamination dynamics and vegetation recovery. It highlights the effectiveness of Technosol in environmental recovery of sulfide mine areas at long term and the spatial heterogeneity evolution.

This work was funded by national funds through FCT—Fundação para a Ciência e a Tecnologia under the projects UID/04129/2025 (LEAF) and LA/P/0092/2020 (TERRA).

How to cite: Estrada, A., Benhalima, Y., Santos, E., and Arán, D.: Soil and vegetation diversity responses to designed Technosol applied in a sulfide mine under semi-arid conditions: field evidence at long term, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18654, https://doi.org/10.5194/egusphere-egu26-18654, 2026.

Abandoned mining sites are a major source of long-term soil contamination by potentially toxic elements. This study assessed the environmental risk of metal-contaminated soils from the Sidi Kamber mine (northeastern Algeria). Mining residues are spread into the surrounding areas and the Oued Es-Souk, a river that supplies the Guenitra dam.This dam is the main drinking water reserve in the Skikda region..

This study is based on the geochemical and ecotoxicological analysis of 16 soil samples, from four stations distributed along the Oued Es-Souk until the dam. Samples were taken at two depths (0–25 cm and 25–50 cm) during both the dry and wet seasons. in Metal availability was evaluated through simulated leachate analyses, while soil properties (pH, fertility and pseudo-total elemental concentrations) were determined using conventional methods. Ecotoxicological bioassays were conducted to assess the biological effects of both soils and leachates in two plant species (Allium cepa and Lactuca sativa), focusing on seed germination, root elongation, and total biomass production as sensitive indicators of phytotoxicity.  Soil pollution indices, including the Igeo-Geoaccumulation Index and the CF-Contamination Factor were calculated to quantify contamination levels and identify the most critical elements.

The soils showed a very variable conductivity (510–3460 μS/cm) and a pH ranging from neutral to slight acid (5.15–7.54), with a tendency towards acidification during dry season. The leachates, less saline, were systematically acid (pH ~5). The organic carbon and some available nutrients contents were relatively low confirming low soil fertility.

The upstream location had the lowest Zn, Mn, Cu, and Pb concentrations in pseudo-total fraction recorded in wet season (194, 480, 16.5, and 88 mg/kg, respectively).  Despite being the lowest on the site, these levels exceeded benchmarks reported by Dutch Target Values or AFNOR standards. The highest concentrations are located at the surface of the soils and at specific points, reflecting a localized accumulation.  Mobility Index (MI = Av/PT) ranked metals in descending order of mobility: Cd>Zn>Ni>Cu>Pb>Cr>Fe. Contamination Factors confirm a significant polluting heritage: the pseudo-total contents of Zn, Pb and Cd are considerably enriched (CF>10 in many cases) compared to local natural levels. The geoaccumulation index classifies metals into three categories: strong to extreme contamination for Cd and Pb (Igeo>3); moderate accumulation for Zn and S (1<Igeo<2); and low to natural levels for Fe, Mn, Cr and Ni (Igeo=0).

Inhibition index specially on  Lactuca, shows that root growth is much more sensitive than germination. If it is very little affected (indices from -0.06 to +0.01), the length of the roots varies greatly, from a marked inhibition (-33.5% for the most toxic sample) to a significant stimulation (+46.5%). Among all the relationships studied, it is between pH and germination that the negative correlation is the most marked..

Overall, this integrated approach provides a comprehensive framework for assessing the environmental risks associated with abandoned mining.

This work was funded by national funds through FCT – Fundação para a Ciência e a Tecnologia, I.P., under the projects UIDB/04129/2020 and UID/04129/2025 (LEAF) and LA/P/0092/2020 (TERRA).

How to cite: Cedah, S., Fekrache, F., Aran, D., and Santos, E.: Integrated environmental Assessment of  multielement Contamination in Mining-Impacted Soils and Leachates: A Case Study from Northeastern Algeria, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19058, https://doi.org/10.5194/egusphere-egu26-19058, 2026.

Abandoned ore processing plants represent critical, long-term sources of environmental contamination and therefore constitute an important field of research for the subsequent rehabilitation of the area.  

The objective of this study was the evaluation of the level and spreading of soil contamination by trace metal elements in the vicinity of an abandoned ore processing plant in northeastern Algeria. Superficial soil samples were collected from 8 sampling stations located upstream, downstream, and directly at the abandoned ore processing plant during the wet and dry seasons.  An environmental assessment of soil samples was conducted through the analysis of physicochemical characteristics: pH, electrical conductivity, and concentration of nutrients and potentially toxic elements in the available and total fractions.

Soil samples showed marked spatial variability in pH values and electrical conductivities although, in general, soils collected in the both seasons showed an acid pH (3.66-4.19) and low-moderate EC (250-446 µS/cm)The total concentrations of S, Fe, Cr, As, Cu, Pb and Zn were elevated in all soil samples, exceeding the maximum values permitted for industrial land use according to soil legislation in several countries (e.g. Canada). For Ni and Cd, only some soil samples exceeded the maximum allowed values. The variation in the elements' availability revealed clear spatial heterogeneity between locations upstream and downstream of the abandoned ore processing plant. However, values remained consistently high near the plant regardless of position, which confirmed its role as the primary contamination source through multidirectional dispersion via runoff and wind.

This work was funded by national funds through FCT – Fundação para a Ciência e a Tecnologia, I.P., under the projects UIDB/04129/2020 and UID/04129/2025 of LEAF-Linking Landscape, Environment, Agriculture and Food, Research Unit and LA/P/0092/2020 of Associate Laboratory TERRA

How to cite: Djemli, M., Boudeffa, K., Fekrache, F., Arán, D., and Santos, E.: Evaluation of soil contamination surrounding an abandoned ore processing plant in Northeastern Algeria: spatial variability and seasonality effect, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19259, https://doi.org/10.5194/egusphere-egu26-19259, 2026.

Arsenic (As) contamination in soils and waters is a critical challenge to human health, agricultural productivity, and ecological integrity. In soil-water systems, As can modify microbial community structure and physicochemical properties; therefore, indicators that integrate As availability and biological stress across heterogeneous matrices are needed. This study evaluated whether phenotypic As resistance patterns in environmental bacteria can be used as bioindicators and whether native, As-tolerant Bacillus and Pseudomonas stains could support recovery-oriented assessments.

Soil/sediment and water samples were collected at six sites across three high-Andean areas in southern Perú: Desaguadero (Puno; deep well and spring), Sicuani (Cusco; two springs), and Espinar (Cusco; Salado River). Solid matrices included riverbed sediments, saturated solids at spring outlets, and excavated well soils (drill cuttings/spoil around the wellhead). In soil/sediment, pseudo-total As was determined by aqua regia digestion. In waters, dissolved As, was quantified alter filtration (0.45 µm) and acidification (HNO₃ (pH < 2).

Tolerance assays were performed on nutrient agar amended with 100, 1000, 1500, and 2000 mg L^-1 As (III) at 30°C for 24-72 h to estimate the minimum inhibitory concentration (MIC). The minimum bactericidal concentration (MBC) was then determined by subculture in As-free broth (triplicate; OD₆₀₀). A total of 59 isolates were obtained: Bacillus (n = 40, water = 12, solid matrix = 28) and Pseudomonas (n = 19, water = 3, solid matrix = 16). Biochemical profiling assigned Bacillus to the B. cereus complex (cereus/thuringiensis), B. subtilis group, and Bacillus spp.; Pseudomonas to P. aeruginosa, P. stutzeri, P. mendocina and Pseudomonas spp.

Bacillus showed higher resistance than Pseudomonas: with growth observed in 37/40, 28/40, 20/40 and 4/40 isolates at 1000, 1500 and 2000 mg L^-1, respectively, and higher tolerance enriched in solid matrix isolates (1500 mg L^-1: 17/28 vs 3/12; 2000 mg L^-1: 4/28 vs 0/12). In Pseudomonas, growth occurred in 16/19, 9/19 3/19 and 0/19 isolates at the same concentrations. The most tolerant isolates were B2539 (Bacillus sp.; MBC = 2200 mg L^-1) and P2501 (P. aeruginosa), with an MBC = 1400 mg L^-1). These results support MIC/MBC “resistance fingerprints” as quantitative bioindicators to compare sites and matrices in As-affected environments.

Keywords: arsenic; microbial bioindicators; riverbed sediment; springs, soil; Bacillus; Psedomonas; souther Perú. 

How to cite: Cjuno Huanca, O. L., Valderrama Negrón, A. C., Quino Favero, J. M., and Silva Santos, E.: MIC/MBC resistance fingerprints to As(III) in Bacillus and Pseudomonas as bioindicators across water and solid matrices in southern Perú, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14632, https://doi.org/10.5194/egusphere-egu26-14632, 2026.

Soil provides 95% of our food and provides other essential ecosystem services, such as water purification, biodiversity, and climate regulation. Unfortunately, numerous agroecological functions of soil are increasingly threatened by the intensifying, primarily anthropogenic, processes of soil degradation. This deteriorates the surface, sorption, and buffering properties of soils, the spread of pollutants into watercourses and groundwater, and adverse changes in porosity, organic matter composition and content, wettability, aggregation, and microbial community, resulting in soil partially or completely losing its ability to function properly. Therefore, it is so important to develop new soil conditioners that can reduce the effects of anthropogenic pressure and make soils more resistant to negative phenomena.

The main aim of this study was to estimate the impact of newly developed biochars and activated carbons from orange peels as well as water-soluble polymers (exopolysaccharide of bacterial origin (Rhizobium leguminosarum bv. trifolii), ionic polyacrylamides) on the structure and sorption capacity of the selected soil. Haplic Luvisol, the most common Polish soil, was collected from 0–20 cm depth of arable land in Poland (Parchatka, Lublin Upland, N 51°22′54″ E 21°59′54″). It was derived from loess parent material. It was modified with 1 wt.% of solid modifier (biochar, or activated carbon) by mixing. Macromolecular compounds (of initial concentration 100 mg/L) were added in the form of solutions. The following parameters: pH, ash content, total organic carbon content, porosity, variable surface charge of the soil were measured before and after modification to estimate effectiveness of the performed treatment. The soil sorption capacity was examined towards copper (Cu) and cadmium (Cd) using a batch adsorption method. The metal concentration was determined using a atomic absorption spectrometer working in the graphite cuvette technique (ContrAA 800, Analytik Jena, Germany). Porosity of the soils was examined using a mercury porosimetry (autopore IV 9500, Micrometrics INC, USA).

It was observed that all modifications using carbonaceous materials improved total pore area, average pore diameter, and total porosity of the soil, which was mainly associated with highly porous structure and relatively large specific surface area of the applied solids. The modification with activated carbon and cationic polyacrylamide resulted in the highest increase in total pore area. Carbon-rich materials could not only increase specific surface area and porosity of the soil, but also form organo-mineral connections, improving the number of active centers. Consequently, they increase soil sorption capacity towards Cu and Cd. The activated carbon application improved their 3- and 1.9-fold adsorption, respectively. The presence of polymers further increased their adsorption on the soil.

The research was founded by National Science Centre, Poland (2021/41/B/NZ9/03059).

How to cite: Kukowska, S., Grygorczuk-Płaneta, K., and Szewczuk-Karpisz, K.: Changes in soil structure and sorption capacity after mixed treatment with macromolecular compounds and orange peels-derived activated carbons , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19332, https://doi.org/10.5194/egusphere-egu26-19332, 2026.

The implementation of irrigation is a key management practice in arid and semi-arid regions to sustain agricultural productivity. Irrigation modifies the soil carbon cycle [1], [2] but its effects on soil inorganic carbon (SIC) have received far less attention than those on soil organic carbon. However, SIC constitutes most of the soil carbon stock in calcareous soils of these regions. Understanding how irrigation interacts with SIC dynamics, governed by carbonate dissolution and precipitation processes, is crucial to assess soil carbon stability and its response to management changes.

This study compares two contrasting management scenarios, rainfed maize and irrigated maize, and evaluated how irrigation affected the dynamics of the SIC in an experimental plot in Navarra (northern Spain) historically cultivated with rainfed wheat. We quantified SIC and SOC contents in bulk soil and in coarse (>50 µm) and fine (<50 µm) fractions of the tilled layer (0–30 cm) of a calcareous soil (⁓40% CaCO₃), together with the isotopic signatures of SOC (δ¹³C-SOC) and SIC (δ¹³C-SIC) along the first 7 years of the trial, as direct assessment of SIC isotopic signatures provides a more reliable estimate of pedogenic carbonate contributions than commonly used mixing equations, avoiding biases associated with C3–C4 crop changes [3].

After 7 years, it was found that the accumulated SOC inputs were higher in irrigated maize (24.0 Mg C ha⁻¹) than in rainfed maize (14.8 Mg C ha⁻¹).  Therefore, irrigated maize showed an increase in SOC stocks of +7.1% [4]. With regard to total SIC, ⁓24% of soil carbonates were found in the coarse fraction and ⁓16% in the fine fraction. No differences were observed between treatments, either in total SIC or in the coarse fraction, but there were differences in the fine fraction of irrigated maize compared to rainfed maize (-1%).

Clear differences in δ¹³C-SIC were however observed between treatments. In bulk soil, δ¹³C-SIC decreased from −3.80‰ under rainfed maize to −4.14‰ under irrigated maize. In the coarse fraction, the shift was more pronounced, from −3.70‰ to −4.95‰, while intermediate changes were observed in the fine fraction (from −3.94‰ to −4.20‰). These isotopic shifts indicate that irrigation, together with increased organic matter inputs, activated carbonate dissolution–precipitation cycles, thereby increasing the relative contribution of pedogenic carbonates.

Furthermore, the preferential accumulation of SIC in the coarse fraction may be related to the formation of pseudo-sands driven by carbonate cementation within aggregates [5], highlighting the need to adjust ultrasonic energy during particle-size fractionation.

Overall, our results demonstrate that irrigation triggers SIC dynamics in calcareous agricultural soils, promoting carbonate dissolution and precipitation processes even in the absence of significant changes in total SIC content, and emphasize the importance of jointly considering SOC and SIC to accurately interpret pedogenic carbonate formation under contrasting agricultural management regimes.

References

[1] Ball et al. (2023), https://doi.org/10.1016/j.soilbio.2023.109189

[2] de Soto et al. (2017), https://doi.org/10.1016/j.geoderma.2017.03.005

[3] de Soto et al. (2024), https://doi.org/10.1016/j.catena.2024.108362

[4] Antón et al. (2022), https://doi.org/10.3389/fsoil.2022.831775

[5] Rowley et al. (2018), https://doi.org/10.1007/s10533-017-0410-1

How to cite: Conte, A. P., Antón, R., Enrique, A., de Soto, I. S., and Virto, I.: Irrigation activates soil inorganic carbon dynamics in a calcareous mediterranean agroecosystem, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20534, https://doi.org/10.5194/egusphere-egu26-20534, 2026.