Soil Systems doi: 10.3390/soilsystems10050058

Authors: Zerihun Asrat Mekbib Fekadu Zerihun Woldu Sebsebe Demissew Betelhem Mekonnen Lars Opgenoorth Georg Miehe Wolfgang Zech

Soil organic matter (SOM) dynamics in tropical montane ecosystems remain poorly understood, particularly regarding the relative importance of particulate versus mineral-associated fractions under varying disturbance regimes. This study investigated SOM fraction distribution across the Ericaceous and Afroalpine belts of Bale Mountains National Park, Ethiopia, an Andosol-dominated landscape subject to recurrent fire. Using a stratified sampling design (n = 30 plots) across four vegetation classes (Ericaceous belt, fragmented Ericaceous belt, herbaceous and heathland, and giant Lobelia areas), three fire history categories (<10, 10–25, and >25 years since fire), and three topographic positions (northern slopes, southern slopes, and central plateau), we quantified coarse particulate organic matter (cPOM: 149–2000 μm), fine particulate organic matter (fPOM: 53–149 μm), and mineral-associated organic matter (MAOM: <53 μm). Particulate fractions dominated the SOM pool, with cPOM and fPOM together accounting for >99% of measured organic carbon. Multivariate ordination revealed a primary gradient (PC1, 61.7%) contrasting particulate-dominated soils in less disturbed areas with relatively MAOM-enriched soils in fire-impacted and fragmented zones. A global comparison reveals a profound stability gap: the Bale Mountains utilize <2% of the mineral stabilization potential of comparable Andosols, demonstrating that extreme fire frequency (<25 yr return interval) overrides even the most reactive mineralogy. We critically evaluate whether standard size-based fractionation adequately captures mineral-associated carbon in volcanic soils and discuss methodological limitations. These results provide baseline data for conservation planning in this biodiversity hotspot and underscore the need for fire management strategies that balance ecological integrity with carbon storage objectives.

Soil Systems doi: 10.3390/soilsystems10050057

Authors: Cuilan Wei Shun Li Bingshuai Cao Songjuan Gao Hao Liang

Co-utilization of milk vetch as green manure (GM) and rice straw is an effective practice for reducing nitrogen (N) input while maintaining crop productivity in rice-based agroecosystems in southern China. The effects of soil carbon (C) and N pools and their fractions under green manuring and rice straw return, combined with reduced N fertilization remain to be clarified. A four-year field experiment was carried out to explore the effects of synergistic utilization of GM and rice straw (GMS) on rice yield, soil C and N fractions, and their contributions to rice productivity. The study demonstrated that compared with winter fallow (WF), GMS increased rice yield by 20.3% under 40% reduction in N fertilization (N60). GM application increased soil total N content by 16.5% and 18.0% significantly relative to WF under N0 and N60, respectively. GMS treatment demonstrated improvements in the soil organic C pool and enhanced soil N activity. Compared with WF, soil organic C, mineral-associated organic C and particulate organic C under GMS increased by 11.1% and 24.9%, 31.3% and 13.8%, 13.1% and 47.3% at N0 and N60 levels, respectively. Under N60, GMS increased heavy-fraction organic C content by 42.6% while reducing light-fraction organic C content by 28.0% compared to WF, thereby enhancing soil C pool stability. Regarding soil N fractions, GMS increased particulate organic N content by 60.8% and 79.3%, and mineral-associated organic N content by 89.7% and 43.4% at N0 and N60 levels, respectively. Under N60, GMS reduced heavy-fraction organic N content while increasing light-fraction organic N content, thereby enhancing soil N availability. Based on the results of Mantel tests and random forest prediction, our analysis found that N and particulate organic C served as the key factors affecting rice yield. In conclusion, GMS combined with 60% of the conventional N rate enhanced rice yield by mediating soil C sequestration and N availability, proving to be an effective strategy for improving soil fertility and ensuring food security in the rice-growing region of southern Jiangsu, China.

Soil Systems doi: 10.3390/soilsystems10050056

Authors: Angélica Vázquez-Ortega Matthew Franks Katarina Kieffer

Conventional tillage, a soil preparation practice used to produce a fine seedbed, can disturb the soil profile by promoting soil compaction and soil organic matter (SOM) degradation. In contrast, conservation tillage, such as no-till, has the potential to sustain or increase SOM. This study aimed to (1) quantify soil organic carbon (SOC) content under conservation tillage and conventional tillage practices, (2) describe the degree of aromaticity of bioavailable SOC using fluorescence spectroscopy, and (3) correlate SOC quantity with nitrogen and phosphorus retention in soils. Fluorescence spectroscopy is a sensitive and non-destructive tool that allows for the assessment of bioavailable SOC quality related to the molecular structure, degree of aromaticity (cyclic molecules with carbon double bonds), and recalcitrance (difficulty of decomposition) of organic compounds. This study employed fluorescence excitation–emission matrices combined with parallel factor analysis (EEM-PARAFAC) to identify humic-like, fulvic-like, and protein-like substances. Data on agricultural management practices were collected from spring 2014 until fall 2017. We obtained soil samples (fall 2017) from farms in the Western Lake Erie Basin, Ohio, and performed geochemical characterization in the bulk soil and aqueous extraction. Our results showed that no-till and minimal tillage fields consistently had greater SOC and fluorescence intensity in the humic-like acids region when compared to conventional tilled fields (no-till: 34,000 mg TOC kg−1; tilled six times: 16,000 mg TOC kg−1). No-till enhanced SOC stabilization. In addition, conservation tillage practices retained the largest total nitrogen (no-till: 2800 mg TN kg−1; tilled six times: 1350 mg TN kg−1) and total phosphorus (no-till: 470 mg TP kg−1; tilled six times: 250 mg TP kg−1) concentrations at all studied depths (0–30 cm) when compared to conventional tilled fields. Conservation tillage promotes the accumulation of highly aromatic organic compounds favoring high cation exchange capacity, and NO3− and PO43− retention and plant bioavailability.

Soil Systems doi: 10.3390/soilsystems10050055

Authors: Paula Alejandra Gómez-Palomo Daniela Monserrat Sánchez-Pérez Erika Flores-Loyola José Juan Torres-Martínez Javier Ulises Hernández-Beltrán Jorge Alejandro Aguirre-Joya Nathiely Ramírez-Guzmán David Francisco Lafuente-Rincón

Soil–Forage–Livestock systems (SFL-systems) integration is fundamental for sustainable land management in arid lands, where conventional crop production is often unfeasible. Aridisols dominate dryland agroecosystems and their edaphic constraints, together with climatic limitations, constitute a major bottleneck for fertility and productivity in key arid regions worldwide. This narrative review provides a taxonomic and edaphic framework to guide sustainable SFL-systems and integrates current approaches and technological applications for forage production in arid environments, focusing on an edaphic-digital scheme that combines organic and inorganic soil amendments with AI-based decision support to improve Aridisols productivity and resilience. Searches of the literature (ScienceDirect, EBSCOhost, Clarivate Web of Science; English, 2021–2025) screened 309 records and selected 169 references; seminal older works were consulted for context. Representative quantitative outcomes from the reviewed literature include SOC increases of ~15–30% after multi-year organic inputs; forage biomass gains of ~10–25% following amendments that correct sodicity; and water-productivity improvements up to ~30% with hydrogels or biochar. AI tools can improve soil diagnostics and amendment selection (diagnostic accuracy improvements of ~15–30% in recent studies) and generate predictive models of amendment–response that facilitate optimization of application rates and water use. The novel contribution of this review is the explicit linkage of SFL-systems and amendment-based soil restoration with AI-driven diagnostics and decision support, providing actionable metrics and research priorities to translate digital diagnostics into measurable forage gains in arid and semi-arid regions. Overall, the evidence suggests that targeted soil restoration, reinforced by AI-based support systems, is a feasible strategy to increase forage availability and ecosystem service provision in drylands.

Soil Systems doi: 10.3390/soilsystems10050054

Authors: Veneramaria Urso William Trenti Mauro De Feudis Gloria Falsone Livia Vittori Antisari Gianluca Bianchini

Vegetation strongly influences soil formation, yet its effect on Rare Earth Element (REE) distribution and fractionation across treeline ecotones remains insufficiently constrained. The present study investigated how contrasting plant communities, Vaccinium myrtillus heathlands and Picea abies forests, affect pedogenetic pathways and REE behavior in sandstone-derived soils of the Northern Apennines (Italy). Six soil profiles were characterized for bulk geochemistry, selective Fe–Al extractions, particle-size distribution, and REE concentrations. Principal component analysis and hierarchical clustering identified pedogenetic drivers and horizon groupings. Under Vaccinium myrtillus, thick acidic organic horizons promoted organo-metal complexation and incipient podzolization, whereas Picea abies soils showed thinner organic layers and enhanced mineral weathering, leading to Bw development with higher silt–clay contents and elevated Al/N ratios. These pathways were captured by Fe–Al indicators and the Spodic Index. REE distributions showed vegetation-related differences in surface horizons and Eu–Ce anomalies, but they did not reproduce Fe–Al pedogenetic clusters, reflecting strong parent-material control. The coexistence of podzolic and cambic pathways at the treeline highlights pronounced spatial heterogeneity and vegetation effects. Plant composition may redirect pedogenesis, influencing nutrient cycling and metal mobility. Additionally, these findings emphasize the need to integrate multivariate statistics with established pedogenetic indicators when evaluating geochemical properties in mountain soils.

Soil Systems doi: 10.3390/soilsystems10050053

Authors: Laura Sanchez-Martin Jhoeel Uvidia Gabriel Gascó Ana María Mendez Mark R. Theobald Patricia Almendros

This study is the first to investigate volcanic ash (VA) as a soil amendment to mitigate nitrous oxide (N2O) emissions, a potent greenhouse gas mainly produced through nitrification and denitrification processes in agricultural soils. The experiment assessed the effects of VA mixed with soil and combined with mineral (NH4NO3, N) or organic (poultry manure, O) fertilizer on N2O emissions, soil mineral nitrogen (NO3− and NH4+), trace metals (Zn, Cu, Mn), and crop yield in a 4-month pot experiment including treatments with and without VA. Results showed that VA reduced N2O emissions by 55% in mineral fertilizer treatments and 71% in organic fertilizer treatments compared to soils without VA. This reduction was associated with significant changes in nitrogen availability. In mineral fertilizer treatments with VA, soil NO3− concentrations remained high, potentially limiting denitrifier activity, while in organic treatments VA appeared to inhibit nitrogen mineralization. Additionally, VA increased soil concentrations of Zn, Cu, and Mn, which were negatively correlated with N2O emissions, suggesting an influence on microbial processes. Importantly, crop yields were not affected by VA application. Although promising, these preliminary findings highlight the need for further research to optimize application rates and evaluate long-term effects across soil types and management systems.

Soil Systems doi: 10.3390/soilsystems10050052

Authors: Tongyao Wu Jihong Qin Shuangchao Wang Hui Sun Xinyue Hu Kaiyan Li

Reactive oxygen species (ROS) are a class of molecules or free radicals with strong oxidizing properties. They have attracted increasing attention in soil research in recent years because of their perceived importance in many soil biochemical processes. Previous reviews of ROS in soil mainly focused on their impacts on carbon emissions and organic pollutant remediation, with few descriptions of the mechanisms responsible for ROS generation, and a comprehensive understanding of their environmental effects is still lacking. Therefore, the present review provides details on the sources and underlying generation mechanisms of ROS in soil. These mechanisms include inputs via atmospheric deposition, metal–mineral reactions, root exudation, microbial metabolism, enzymatic reactions and various organic matter transformations. In contrast to previous reviews, we also discuss mutual conversion between different types of ROS in soil. The impacts of ROS on the soil environment are further explored, such as element cycling, pollutant degradation, and the growth and reproduction of plants and microorganisms, in order to provide a systematic understanding of the various processes involving ROS in soil, thereby guiding better soil management decisions. Finally, we highlight future research trends, suggesting that the advancement of in situ detection methods is crucial for establishing the precise contribution of abiotic ROS processes to global soil carbon and nutrient models.

Soil Systems doi: 10.3390/soilsystems10050051

Authors: Fatma Karaouli Mongi Ben Zaied Nadia Khelif Zaineb Ali Fethi Abdelli Houda Besser Latifa Dhaouedi Mohamed Ouessar

Soil erosion is a significant environmental concern in arid regions, particularly in dam-regulated watersheds, where intermittent flows from sprinkler irrigation can exacerbate land degradation. This study assesses soil erosion susceptibility in the Sidi Aich watershed using a combined approach of the Revised Universal Soil Loss Equation (RUSLE) and the Analytic Hierarchy Process (AHP), enabling the integration of both regional characteristics and expert-driven weighting. The RUSLE model accounts for natural and human-induced factors, whereas AHP provides a hierarchical weighting system that highlights rainfall erosivity and the local impacts of dam-regulated discharges. Results show that 26.12% of the area falls into the very high susceptibility category, 25.45% into high, 23.91% into moderate, and 24.51% into low susceptibility. Model validation demonstrates satisfactory predictive performance, with Area Under the Curve (AUC) values of 0.85 for AHP and 0.78 for RUSLE. Overall, the findings emphasize the critical role of dam-controlled releases in increasing soil vulnerability, a factor that may not be fully captured when using RUSLE alone. By combining RUSLE and AHP, this research provides a more realistic and regionally tailored assessment of erosion risk, offering valuable guidance for watershed management and erosion mitigation strategies in arid environments.

Soil Systems doi: 10.3390/soilsystems10050050

Authors: Talita Dantas Pedrosa Rafael Oliveira Batista Solange Aparecida Goularte Dombroski José Francismar de Medeiros Stefeson Bezerra de Melo Rafael Rodolfo de Melo

Aquaculture effluent appears as an alternative for reuse, given its significant generation. However, its use must be reasonable to avoid damage to the environmental quality of the soil. In this context, the objective was to evaluate the chemical changes in Ultisol cultivated with small prickly pear cactus and irrigated with different dilutions of aquaculture effluent in the supply water. The experiment was conducted at the Water Reuse Experimental Unit, located in the Brazilian semi-arid region, Mossoró, RN, Brazil. Planting was carried out in a randomized block design with five treatments and five replications. A small prickly pear cactus was irrigated weekly for 365 days, with the gross water depth determined based on the crop’s evapotranspiration. During the experimental period, the physical-chemical characterization of the effluent dilutions was conducted every 60 days, with initial and final descriptions of the soil in the 0.0–0.20 m and 0.20–0.40 m layers. Additionally, cation exchange capacity and the exchangeable sodium percentage were determined. Multivariate statistical analysis was applied to understand chemical changes in the soil. The dilutions containing a higher proportion of aquaculture effluent in the supply water, primarily consisting of 100% effluent, exhibited the chemical changes in the soil. Using a dilution containing 25% aquaculture effluent in 75% supply water may be the most viable alternative for water supply in prickly pear cactus irrigation, with non-relevant changes in soil chemical characteristics.

Soil Systems doi: 10.3390/soilsystems10040049

Authors: Hamisi J. Tindwa Bal Ram Singh

Soil contamination in Sub-Saharan Africa (SSA) is increasingly driven by rapid industrialization, intensive agriculture, mining activities, and urban expansion, posing significant risks to food safety, ecosystem services, and human livelihoods. Despite the growing scale of the problem, low-cost, locally adaptable remediation technologies are widely available and technically feasible within the region. Organic waste and waste-derived products—such as compost, manure, biochar, vermicompost, digestate, and agro-industrial residues—have emerged as sustainable and cost-effective amendments for the remediation of contaminated soils. These materials can immobilize heavy metals, enhance the microbial degradation of organic pollutants, and improve soil health, making them especially suitable for resource-constrained settings. This review synthesizes the current knowledge on the use of organic waste-based remediation approaches in SSA, highlighting technologies already applied at the laboratory, pilot, and field scales, as well as their effectiveness across different contaminant types. However, despite their demonstrated potential, their widespread adoption remains limited. The primary challenge is not the absence of affordable solutions, but rather the systemic constraints characteristic of many SSA countries, including limited technical capacity, weak policy and regulatory frameworks, low stakeholder awareness, and insufficient financial and institutional support for large-scale implementation. To enable broader uptake, there is a need to strengthen waste segregation and treatment systems, standardize composting and pyrolysis processes, and develop robust regulatory guidelines and certification schemes. Investments in monitoring infrastructure, practitioner training, and knowledge transfer mechanisms will also be critical to translating scientific advances into scalable, field-ready solutions for sustainable soil remediation in SSA.

Soil Systems doi: 10.3390/soilsystems10040048

Authors: Marina Quiroga Julia L. Bazzani Roberto S. Martínez Anahí Domínguez José C. Bedano

Earthworms are ecosystem engineers that are sensitive to land-use intensification and edaphic conditions, yet their ecology remains poorly understood in transformed semi-arid landscapes. We hypothesized that, in recently colonized agroecosystems, land-use intensity and physicochemical soil conditions jointly filter the earthworm assembly. In the recently irrigated Lower Valley of the Negro River, Patagonia, Argentina, we sampled earthworms and soils across five land uses—riparian reference sites, fruit orchards, pastures, cereal crops, and horticulture plots—in landscapes dominated by Natrargid Ustolls and Fluventic Haplocambids. We found five species, all of which were exotic Lumbricidae, including the first Argentine record for Murchieona minuscula, indicating a recent colonization following human-mediated niche construction that created an ecological island. The earthworm abundance and biomass were highest in permanent and semi-permanent uses and were driven primarily by soil moisture, pH, and particulate organic matter. Crucially, our results reveal that land-use intensity filters communities by restricting the initial colonization rather than through local extinctions. These findings confirm that soil properties mediate the impact of land use on earthworm assemblages. The inclusion of pastures and fruit orchards in the rotations favors the earthworm populations that, despite low diversity, enhance soil functioning and contribute to agricultural sustainability in semi-arid irrigated agroecosystems.

Soil Systems doi: 10.3390/soilsystems10040047

Authors: Ebrahim Jahanshiri Eranga M. Wimalasiri Yinan Yu Ranjith B. Mapa

High-resolution soil depth maps are valuable for environmental modelling, yet reliable data remains scarce in the tropics. This study evaluates the feasibility of mapping depth to bedrock (DTB) in Sri Lanka using a legacy dataset (n = 88) and global environmental covariates (n = 247). A robust machine learning workflow was employed—including feature selection, hyperparameter tuning, and a stacked ensemble of four algorithms (Random Forest, XGBoost, Cubist, SVM)—to test the limits of global data for local mapping. Despite rigorous optimization, the final ensemble model achieved a performance of R2 = 0.197 (RMSE = 35.4 cm) under spatial cross-validation. While still modest, this result significantly outperforms existing global products and quantifies the “prediction gap” inherent in using ~1 km resolution global covariates to model micro-scale soil variability. An initial exploration involved log-transforming the target variable; however, following rigorous testing, the untransformed depth was modelled directly to avoid bias in back-transformation. A robustness experiment was further conducted, reducing predictors from 24 to 12, which degraded performance, confirming that the model captures complex, physically meaningful climatic interactions rather than fitting noise. The study concludes that while global covariates can capture regional meso-scale trends (explaining ~20% of variance), they are insufficient for resolving local micro-relief (<50 m). The resulting map and uncertainty products provide a critical “baseline” for national planning, but effectively demonstrate that future improvements will require investment in higher-resolution local covariates (e.g., LiDAR) rather than more complex algorithms.

Soil Systems doi: 10.3390/soilsystems10040046

Authors: Ana Carolina De Mattos E. Avila Jackson Adriano Albuquerque Johannes Biala Yash Dang Gunnar Kirchhof

Compost is widely used to improve soil fertility and structure, yet its effects on soil physical properties in Vertosols remain insufficiently documented. This study evaluated the effects of repeat compost application on soil carbon and nitrogen contents and selected soil physical properties in Vertosols from three farms in Queensland, Australia (Roma, Dalby, and Goovigen). Compost had been applied at rates between 5 and 22 Mg ha−1 yr−1 for periods ranging from 3 to 11 years, depending on the site. Intact and disturbed soil samples from the top 0–8 cm were analyzed for bulk density, water retention, hydraulic properties, aggregate stability, and water repellence. Aggregate stability was assessed using laser diffraction before and after ultrasonic dispersion. Compost application significantly increased total carbon and nitrogen contents at all sites (p ≤ 0.01), although effects on soil physical properties varied by site. In Dalby, compost improved water retention and aggregate stability; in Goovigen, it resulted in lower Disaggregation Ratios. Compost did not induce soil water repellence at any site. The results indicate that compost amendments improve soil carbon and nitrogen concentrations and can modify soil physical properties in Vertosols, although responses depend on site conditions and management history.

Soil Systems doi: 10.3390/soilsystems10040045

Authors: Kendall Mackin Sarah L. Strauss Yang Lin Diego Arruda Huggins de Sá Leitão Marcio R. Nunes Gabriel Maltais-Landry

Soil enzyme activities are sensitive biochemical indicators that could benefit soil health assessments, especially in coarse-textured soils. Current protocols are inconsistent for fluorimetric assays and an optimized assay would facilitate comparisons of activities across climates and soils. A factorial experiment was conducted to evaluate how assay conditions affect the activity of three enzymes (acid phosphatase, β-glucosidase, and N-acetyl-β-glucosaminidase) across seven Florida mineral soils (>89% sand) by crossing two temperatures, four pH values, and two reaction termination reagents. Results between microplate fluorimetry and benchtop colorimetry and between air-dried and frozen (−80 °C) soils were also compared. For these soils, a pH of 4.5 with sodium hydroxide termination and a temperature of 25 °C were deemed “optimal” for maximizing activities and maintaining consistent trends. Activities measured with benchtop colorimetry and microplate fluorimetry were related for each enzyme (R2 range: 0.58–0.83) and activities from air-dried soils were 50–90% of those from frozen soils (R2 range: 0.75–0.91). Enzyme activities were positively correlated with other indicators (total C, nutrients), supporting their use in soil health assessments. As the rankings of soil samples by highest enzyme activities were similar regardless of protocol variations, this suggests that inherent soil properties were the dominant drivers of enzymatic activity.

Soil Systems doi: 10.3390/soilsystems10030044

Authors: Miguel Ángel Sánchez-Sánchez Alfonso Albacete

Climate change brings about changes in precipitation and temperatures, significantly increasing aridity in many areas. The southeast of the Iberian Peninsula is affected by climate change and increased aridity, which, together with anthropogenic factors, has increased the area affected by erosion. It is interesting to learn about aspects of aridity, desertification, and erosion in the southeast of the Iberian Peninsula. A literature review was conducted on issues related to climate change, aridity, desertification, and erosion, focusing on the southeast of the peninsula. In addition, field visits were made to verify some of the situations described in the literature. The results highlight the relationships among climate change, aridity, desertification, and erosion, and illustrate their impacts on the landscape and territory of the southeastern Iberian Peninsula. Furthermore, the results indicated a clear anthropogenic influence on the aridity–desertification–erosion loop. There has been a notable and rapid increase in erosion and aridification. Aridity is closely linked to erosion, and its harmful effects on soils in the southeastern Iberian Peninsula have intensified significantly.

Soil Systems doi: 10.3390/soilsystems10030043

Authors: Roberta Pastorelli Alessandra Lagomarsino Chiara Ferronato Arturo Fabiani Sara Del Duca Stefano Mocali Livia Vittori Antisari Gilmo Vianello

In permanently submerged coastal wetlands, interactions between biogeochemical processes and microbial communities strongly influence greenhouse gas (GHG) fluxes. To improve our understanding of how redox-driven processes shape GHG dynamics in these ecosystems, we investigated the relationships among iron (Fe) pools, microbial dynamics, and the potential GHG production in subaqueous soils from an interdunal wetland in San Vitale Park (Italy), permanently submerged and affected by seasonal oscillations of the saline water table. Two subaqueous soil columns (WAS-2 and WAS-4), collected from similar settings, were analyzed. Surface layers of WAS-4 showed higher salinity and carbonate content, whereas WAS-2 was characterized by overall higher Fe concentrations. Distinct vertical distributions of organic matter and sulfur (S) were shown along depth. Laboratory incubations revealed that nitrous oxide (N2O) production was up to ten times higher in WAS-2 than in WAS-4, with peaks in the top 13–14 cm, consistent with more active nitrification-denitrification in surface layers. Methane (CH4) and carbon dioxide (CO2) fluxes decreased with depth, reflecting reduced availability of labile carbon. Methanomicrobiales dominated CH4-producing layers, indicating hydrogenotrophic methanogenesis, while amoA-carrying Nitrosomonadales and Thaumarchaeota, occurred in shallow, organic-rich layers where ammonia supported nitrification and denitrification. Denitrifiers mainly belonged to α- and β-Proteobacteria, consistent with their direct contribution to N2O peaks. Spearman’s correlations showed N2O positively correlated to sulfur and labile carbon (C), supporting denitrification under moderately reducing conditions. CH4 and CO2 positively correlated with organic C (Corg), total nitrogen (TN), and reactive Fe forms, reflecting redox-mediated microbial respiration and methanogenesis. Trace elements (B, Cr, Cu, Ni) acted as micronutrients or inhibitors depending on concentration. Canonical correspondence analysis indicated depth-structured links among gas fluxes, soil chemistry (Corg, TN, S/C, CaCO3, P), and microbial distributions: surface layers, rich in labile C and nutrients, supported active bacteria and archaea involved in decomposition, nitrification, and denitrification, whereas deeper layers hosted oligotrophic archaea adapted to inorganic substrates. Overall, Fe pools appeared to be associated with soil processes relevant to GHG dynamics, although the extent of their regulatory role remains uncertain due to potential alterations of redox-sensitive Fe fractions during sample handling. These results contribute to broader efforts to predict GHG emissions in submerged wetland soils by linking redox stratification, inorganic chemistry, and microbial functional groups.

Soil Systems doi: 10.3390/soilsystems10030042

Authors: Ana Méndez Patricia Almendros Jorge Paz-Ferreiro Gabriel Gascó

Micronutrient addition to soil is crucial for improving crop yield. Within the framework of the circular economy, it is necessary to seek more efficient fertilizers. This would reduce fertilizer consumption while serving as a strategy to mitigate the negative effects of climate change. This study proposes the combined use of a traditional source of a Zn fertilizer (ZnSO4) together with wood biochar to improve lettuce (Lactuca sativa L.) crop yield. An experiment was designed in which a dose of 8 mg Zn kg−1 as ZnSO4·7H2O was added to Cambisol soil, mixed with or without biochar (5%), for lettuce growth. Among other soil properties, Zn bioavailability, microbial biomass, and available water were monitored in the soil, while photosynthetic pigments, Zn content, and biomass production were determined in plants. All treatments increased plant biomass production. Biochar treatments (biochar and biochar/ZnSO4) increased fresh biomass by 324%, while ZnSO4 addition resulted in a 158% increase in lettuce yield. This can be due to several factors, such as biochar being a C source, the improvement of soil water content after biochar addition, and the increase in Zn leaf content in all treatments with respect to the control soil. All of these likely had a positive effect on photosynthesis. This is corroborated by the increase in total chlorophyll, chlorophyll, and carotenoids in the treatments with ZnSO4, biochar/ZnSO4, and biochar. The application of biochar alone increased this property by more than 168%, with a positive impact on soil quality. Our research demonstrates that it is possible, in some cases, to prepare fertilizers combining ZnSO4 and biochar, leading to increased plant Zn uptake and improved crop yield.

Soil Systems doi: 10.3390/soilsystems10030041

Authors: Rômulo José Alencar Sobrinho José Odair da Silva Lívia da Silva Santos Fabrício do Carmo Farias Alessandra Noelly Reis Lima Nelson Ken Narusawa Nakakoji Daniel De Bortoli Teixeira Rose Luiza Moraes Tavares Gener Tadeu Pereira Daniel Pereira Pinheiro João Fernandes da Silva-Júnior

Predictive Digital Soil Mapping (PDSM) in Eastern Amazonia faces challenges due to its environmental complexity, difficult access, and scarce legacy data. While legacy soil maps contain valuable tacit knowledge, updating them requires methods that can handle uncertainty. This study evaluates the integration of old soil maps with machine learning to update soil information in Tracuateua, Pará, with a specific focus on the performance of ensemble learning and the explicit incorporation of uncertainty metrics in soil mapping units under hydromorphic influence, which, in addition to being difficult to access, are influenced by complex pedogenetic processes. We combined 270 sampling points, equivalent to the total pixels that captured the variability of soil mapping units, with environmental covariates and historical data. Several algorithms were tested, including an ensemble approach, to predict mapping units and quantify uncertainty through entropy and confusion indices. The ensemble model demonstrated improved stability and reduced classification uncertainty compared to single models, particularly in challenging hydromorphic environments. Although accuracy gains were modest, the models captured soil–environment relationships, with climate as: Annual Mean Temperature 22,000 years ago (Tmean_22k), relief: Channel Network Base Level (CNBL and altitude) and organism variables: Land Surface Temperature (LST) emerging as the main predictors. Spatialized uncertainty estimates, expressed through entropy and the confusion index, provide a practical decision-support tool for guiding field surveys and identifying areas of low mapping reliability. By explicitly transferring the pedologist’s mental model—encoded as tacit knowledge in legacy soil maps—into ensemble learning, this study presents a robust and transferable framework for updating soil maps in data-scarce tropical regions, balancing predictive performance, spatial consistency, and uncertainty-aware interpretation.

Soil Systems doi: 10.3390/soilsystems10030040

Authors: Payton B. Davis Dara M. Park Brook T. Russell Debabrata Sahoo

Integrating cover crops (CCs) into crop rotations has gained interest in the Southeastern United States due to the benefits that CCs offer, which improve soil health for agricultural production. However, more information is needed on how CCs may affect the development of soil water repellency (SWR), which can negatively impact soil hydrology. The development of SWR threatens crop yields, food security, and farmer livelihoods. To address this knowledge gap, a field experiment measured the water repellency (WR) of four common CC species and a fallow treatment. CC samples were oven-dried, ground, and analyzed for WR using the water drop penetration time (WDPT) test. The mean WDPTs of the CC residues collected at termination and four weeks post-termination ranged from 49 to 4174 and 8 to 2627 s, respectively. Large WDPTs (>5 s) indicate that CC residues can potentially influence the development of SWR. All CC residues exhibited WR. The results suggest that farmers may need to consider alternative CC species depending on when they plant their cash crops in relation to CC termination. Considering the effects of CCs on SWR will enable farmers to make informed management decisions to mitigate SWR development and maintain soil health in a changing climate.

Soil Systems doi: 10.3390/soilsystems10030039

Authors: Qi Liu Guodong Fang Naichi Zhang Chenhao Pei Song Wu Min Yang Jie Shen Kai Yu Xuezheng Shi Weixia Sun Jie Liu Cun Liu Yujun Wang

Comprehensive soil surveys necessitate the integration of multidimensional pedological information, ranging from the morphological delineation of horizons and the taxonomic identification of soil groups to the quantitative assessment of soil organic matter (SOM). These attributes collectively constitute the basis for interpreting pedogenesis and guiding sustainable soil management. However, conventional methods are limited by the subjectivity of expert judgment for horizon and soil group identification, and the time-consuming nature of laboratory analyses for SOM quantification. We developed a novel multimodal deep learning framework based on an improved Mask R-CNN architecture that integrates soil profile images with auxiliary soil property data to concurrently delineate soil horizons, classify soil groups, and quantify SOM. The model was trained on high-resolution soil profile images from 451 soil survey sampling sites spanning ten soil groups across Anhui Province, China. Data augmentation and transfer learning with pre-training on large general image datasets were employed to address the dataset size limitations and improve model generalization. In addition to accurately delineating master horizons, we evaluated three schemes for classifying transitional horizons, which are often ambiguously determined by expert assessments: (i) assigning the transitional horizon to one adjacent master horizon; (ii) assigning it to both neighboring master horizons as an overlapping section; and (iii) treating the transitional horizon as an independent layer. Scheme (iii) achieved the best overall performance, e.g., horizon delineation with accuracy = 0.925, recall = 0.933, F1-score = 0.929, and segmentation mean average precision (seg-mAP) = 0.918, soil group classification accuracy = 0.717 and prediction of SOM with R2 = 0.565. These results demonstrate that treating transitional horizons as independent layers yields superior segmentation. Consequently, this integrated framework provides a robust, automated solution for high-throughput soil resource assessment.

Soil Systems doi: 10.3390/soilsystems10030038

Authors: Fatma Mekki Nissaf Karbout Habib Lamourou Houda Oueriemmi Ali Bennour Mohamed Moussa Mohamed Ouessar

Climate change and soil degradation threaten agricultural sustainability in arid oases, where water and nutrient limitations constrain crop production. In Tunisia, date palm residues are abundant but frequently burned despite their potential as soil amendme. This study assessed the effects of date palm waste biochar (B; 10 t ha−1), mineral fertilizers (NPK), and their combination as enriched biochar (BNPK) on soil fertility, including total organic carbon (TOC) and total nitrogen (TN), as well as barley (Hordeum vulgare L.) yield over two consecutive cropping seasons (2023–2024) using a randomized complete block design with three replications. During 2024, B increased TOC to 0.5% (control: 0.18%), while NPK enhanced TN to 0.037% in 2023; however, in 2024, nitrogen levels returned to values comparable to the control condition (0.017%). BNPK combined these beneficial improvements, maintained them in 2024, and resulted in a C/N ratio of 16.7 (control: 9.6), reflecting the most favorable balance between soil carbon accumulation and nitrogen retention. Grain yield increased by 21% (B), 80% (NPK), and 79% (BNPK) relative to the control (3.12 t ha−1), while BNPK reduced soluble sugars in grains (fructose 100%), glucose 86% (control: 0.09, 0.014) and increased grain nitrogen content to 1.80% (control: 0.74). Principal component analysis revealed a clear separation among treatments, with BNPK strongly associated with improved soil fertility, grain yield, and grain quality. These results demonstrate that integrating biochar with nutrient management enhances soil fertility and supports sustainable agriculture in arid oasis agroecosystems.

Soil Systems doi: 10.3390/soilsystems10030037

Authors: Mohammad Wasif Amin Naveedullah Sediqui Shafiqullah Aryan Safiullah Habibi Khalid Joya Atsushi Sanada Shinji Suzuki Irie Kenji Machito Mihara

Drought reduces soil moisture and impairs root function, posing a significant threat to rice production in arid regions. The influence of soil amendments on early rice root development under semi-dry cultivation remains insufficiently characterized, especially when assessed using non-destructive rhizotron techniques. This study employed a scanner-based rhizotron system to evaluate early root responses of rice seedlings to six amendments under semi-dry irrigation: vermicompost and peat moss, spirulina powder, gypsum, rice husk biochar, zeolite, and an unamended control. The vermicompost plus peat moss (VC+PM) treatment demonstrated the highest water-holding capacity (26%), root projected area (9.60 cm2 plant−1), and root surface area (84.79 cm2 plant−1). VC+PM also promoted extensive lateral branching (233 secondary and 1709 tertiary roots) and the greatest total lateral root length (363.09 cm plant−1), resulting in superior biomass (shoot: 140.00 mg plant−1; root: 56.70 mg plant−1) and the lowest root-to-shoot ratio (0.90). These improvements are attributed to the enhanced moisture retention of peat moss and the nutrient and phytohormone contributions of vermicompost. In contrast, rice husk biochar exhibited the lowest water-holding capacity (14%), while other amendments produced moderate or limited effects. The results establish a direct relationship between improved soil water retention and early-stage drought-avoidant root development. The combination of VC and PM emerges as a promising approach to enhance root plasticity and seedling establishment in water-saving rice systems. As this study was conducted under controlled rhizotron conditions and limited to the seedling stage (20 days after sowing), future research should prioritize multi-season field trials to assess yield translation and economic feasibility assessments to support farmer adoption.

Soil Systems doi: 10.3390/soilsystems10030036

Authors: Julián Ramos Nestor Bonomo Claudio García Andrés Quincke

Agricultural systems are under growing pressure, as soil degradation threatens food security and sustainable land use. Early detection through soil monitoring and precision agriculture is vital to prevent irreversible damage and enable timely conservation. This study evaluates a combined procedure based on electrical resistivity tomography and frequency-domain electromagnetic induction measurements, together with discrete soil sampling, to electrically characterize the soil, identify layers, and map the A horizon depth in a non-disturbing way. This work includes the design and implementation of a mounting electrode system, which reduces the installation time of electrical resistivity tomography surveys by 60% while maintaining data quality. The data were acquired in the oldest long-term agronomic experiment in South America, comprising seven rotation systems with three replicates each, totaling 21 rainfed plots, and representing contrasting management scenarios. Soil A horizon thickness maps of the entire experiment were obtained through two procedures. A comparison between mapping inputs, including all plots and only bare-soil plots, revealed minimal differences in unvegetated areas but notable discrepancies under plant cover, where vegetation increased fluctuations and noise. The present study provides a methodology for accurately assessing the spatial variability of the A horizon thickness by means of proximal sensing techniques. This contributes to the challenge of gathering fundamental soil information in a fast and cost-effective manner, critical for precision agricultura.

Soil Systems doi: 10.3390/soilsystems10030035

Authors: Sara Mavsar Helena Grčman Rok Mihelič

Soil texture-dependent responses and time-scales of soil quality change, especially soil carbon, remain poorly understood. We addressed this gap using a dual time-scale design of long-term field experiments: 11 years of minimum (MT) versus ploughing tillage (CT), both followed by 5-year transitions to no-till (NT) in contrasting textures (loamy vs. silty clay) in NE Slovenia. In loamy soils, reduced tillage in the 0–10 cm layer increased soil organic carbon by 40–48%, dissolved organic carbon by 36–64%, permanganate oxidizable carbon by 67–84%, particulate organic carbon by 76–95%, and mineral-associated organic carbon (MAOC < 50 μm) by 28–34%. In silty clay soils, high clay content masked tillage effects, though labile pools showed stratification. MAOC < 20 μm remained stable across treatments and textures (2.0–2.5%), except under CT in loamy soil (1.73%), indicating enhanced decomposition. In loamy soils CT increased by 0.5–1 and 1–2 mm and decreased >20 mm and in silty clay soils increased <0.5, 1–2 and 2–4 mm aggregate formations. The MWD, GMD, Dm indices correlated strongly with C fractions, confirming physical protection mechanisms. Our dual time-scale approach reveals labile C pools and aggregate recovery respond within 5 years of NT, while texture modulates response magnitude and detectability.

Soil Systems doi: 10.3390/soilsystems10020034

Authors: Suah Yekeh Ashaki A. Rouff

Soils in seven urban parks in Newark, New Jersey (NJ), United States, were evaluated for arsenic (As) and lead (Pb) by field and laboratory methods. Surface (S1, 0–3 cm) and near-surface (S2, 4–7 cm) soils in high-contact areas of the parks were analyzed by portable X-ray fluorescence (XRF) spectroscopy. Median concentrations of As and Pb in S1 profiles were higher than median concentrations in NJ Urban soils. In S1 and S2 profiles, 39–50% of As and 56–58% of Pb concentrations exceeded the NJ Department of Environmental Protection limits for residential soils, with most hotspots located in two of the seven parks. The contamination factor (CFAs = 1.5–4.3; CFPb = 1.7–9.8), enrichment factor (EFAs = 1.7–4.6; EFPb = 2.0–10.4), and geoaccumulation index (Igeo As = −0.1–1.5; Igeo Pb = 0.1–2.7), calculated relative to NJ Rural soil concentrations, confirmed the contamination of park soils with As and Pb, with higher contamination and enrichment indices for Pb. Tessier sequential extraction indicated the metals were mostly in the reducible fraction, with median values of 80% As and 65% Pb bound to iron and manganese oxides. The fractionation suggests limited environmental mobility of the metals under current soil conditions. However, human exposure to As and Pb remains a concern as the soils are located in high-contact recreational areas.

Soil Systems doi: 10.3390/soilsystems10020033

Authors: Evanna McGuinness Abraham J. Gibson Joanne Oakes Mark Farrell Naomi S. Wells

Subsoil (30–100 cm) soil organic carbon (SOC) is a poorly constrained but potentially significant component of terrestrial carbon budgets. While controls on subsoil SOC are likely to differ from those affecting topsoil, few studies have quantified them. This study quantified subsoil (30–100 cm) SOC stocks and identified the controls on its spatial distribution across perennial grazing systems in northeast New South Wales, Australia. SOC was measured to 1 m depth across 54 long-term perennial pasture grazing paddocks on nine farms. A Random Forest regression model was then used to determine the relationship between subsoil SOC and drivers represented by the scorpan model of soil formation. Subsoil SOC contributed ~50% of total SOC stocks in the top metre of soil, with a median of 65.8 t ha−1 stored in subsoil. Our study found that drivers of SOC input and turnover (subsoil total nitrogen, 10–30 cm SOC content, and climate), as well as pedogenic processes influencing SOC stabilisation (weathering index), were the most important factors in the determination of subsoil SOC content. This contrasts with previous findings where abiotic factors linked to parent material and soil properties were the major controls on subsoil SOC distribution and highlights links between both input and stabilisation in perennial grazing systems.

Soil Systems doi: 10.3390/soilsystems10020032

Authors: Fujun Liu Hangyu Zhang Jianhui Zeng Zhonglu Guo

Soil erosion and deposition processes act as key drivers of soil resources distribution across landscapes, affecting soil quality and functionality. However, the impacts of long-term soil erosion on soil quality and degradation in the black soil region remain unclear. Here, we assessed soil quality and degradation as a consequence of historical erosion and soil redistribution in an agricultural catchment in Northeast China. Soil quality indices (SQI) were calculated using both linear and non-linear scoring function methods, along with soil indicator selection approaches, including Total Data Set (TDS) and Minimum Data Set (MDS). Soil degradation indices (SDI), resistance indices (SRI), and the change of SQI (CSQI) were computed and compared. The mean SDI for bulk density (BD) and sand was greater than 0. When BD and sand were excluded, the mean SDI and SRI for the 0–10 cm and 10–20 cm soil layers were −29.8% and −21.9%, and 0.57 and 0.65, respectively. Surface soil (0–10 cm) organic matter (SOM), available potassium (AK), structure stability index (SSI), and total nitrogen (TN) in eroding sites, as well as AK, SSI, SOM, TN, and available phosphorus (AP) in depositional sites, are particularly sensitive to long-term erosion. Field capacity, sand, AK, and SSI were selected to develop the SQI, with the non-linear method utilizing MDS outperforming other SQIs. Most SQIs in eroding sites were lower than those in depositional sites and increased with higher soil redistribution rates. The assessment of soil degradation using SDI, SRI, and CSQI revealed that long-term erosion markedly diminished soil quality, although deposition somewhat alleviated this impact. The lower SQI in the 10–20 cm compared to the 0–10 cm soil layer was primarily attributed to decreased FC, while long-term erosion degraded soil quality by negatively affecting AK and sand content. These findings enhance our comprehension of soil degradation caused by erosion in the Mollisol region of Northeast China.

Soil Systems doi: 10.3390/soilsystems10020031

Authors: Dmitry S. Volkov Olga B. Rogova Svetlana T. Ovseyenko Mikhail A. Proskurnin

The distribution of water-soluble organic matter (or dissolved organic matter DOM) in narrow (nano-and micrometer) fractions of chernozem was studied by sequential filtration on track-etched membranes. Multimodal (IR and fluorescence) two-dimensional correlation (2D-COS) spectroscopy was used. Protocols for attenuated total reflectance (ATR) FTIR of DOM were proposed. ATR-FTIR 2D-COS provides a larger volume of information on characteristic bands compared to traditional FTIR, especially in C–H ranges (3000–2800 and 1450–1300 cm−1). The fluorescence excitation–emission matrix 2D-COS showed that the indexes and ratios of humic- to protein-like compounds are reproducible, and exhibit significant variation among size fractions, with maximum amounts of saturated humic-like compounds in the largest (2–10 μm) and finest fractions (0.01–0.03 μm), while medium fractions (0.05–1 μm) are dominated by fulvic acids and fresh organic matter. Heterospectral fluorescence–IR 2D-COS enhanced the accuracy of identification and assessment of DOM group composition and showed that C–H IR band intensities correlate with tyrosine-like EEM bands and biogenic fluorescence indexes, while carboxylic components have humate-like bands and humification fluorescence indexes. Element profiles in DOM fractions correlate with fluorescence indexes; humification indexes with P, S, Cr, Mg, Ca, Cu, and Zn; biogenic with Mg, P, Cr, Cd, K, S, and Ca.

Soil Systems doi: 10.3390/soilsystems10020030

Authors: Hongbiao Cui Zhanlong Liu Binglu Bao Lijun Zhou Shiwen Zhang Jun Zhou

Soil cadmium (Cd) pollution poses a significant threat to rice production and food safety. Although lime amendment is known to reduce Cd bioavailability in soils, the optimal growth stage for its application remains unclear. This study employed pot experiments with the rice cultivar Wuyouhuazhan as the test material to investigate the effects of lime (Ca(OH)2) application during four critical rice growth stages, namely seedling (LS), tillering (LT), booting (LB), and filling (LF), on Cd availability, soil properties, and Cd accumulation in rice. Results showed that lime application at all stages significantly reduced soil-available Cd by 53–63%, primarily by promoting the transformation of exchangeable Cd into more stable residual forms. Lime also increased biomass across rice tissues by 1–153%, with the most pronounced effects observed when applied at the seedling stage. Following lime application at different stages, Cd concentrations in all rice tissues showed a decreasing trend. Compared to CK (without lime application), Cd concentrations decreased by 2–26% in roots, 33–80% in stems, and 8–62% in grains. Among the treatments, LS was the most effective in reducing Cd levels, while LT, LB, and LF exhibited progressively weaker reductions. Structural equation modeling indicated that soil pH and stem Cd concentrations were key factors influencing grain Cd accumulation. These findings demonstrate that lime application at the early seedling stage is most effective in mitigating Cd uptake by rice, providing a practical strategy for safe rice production in Cd-contaminated soils.

Soil Systems doi: 10.3390/soilsystems10020029

Authors: Gabriele Buttafuoco Carmela Riefolo Massimo Conforti Annamaria Castrignanò

This study aimed to evaluate the effectiveness of spectral absorption-feature indices, derived from soil hyperspectral diffuse reflectance spectroscopy, as covariates within a multivariate geostatistical framework to enhance the digital mapping of soil organic carbon (SOC). The approach also incorporated exhaustively measured auxiliary variables derived from topographic and textural attributes. The research was conducted in a 1.39-km2 forested catchment, where 135 topsoil samples (0–0.20 m depth) were collected from soils classified as Typic Xerumbrepts and Ultic Haploxeralfs. All samples were analyzed for SOC concentration, soil texture, and diffuse reflectance spectra across the VIS–NIR–SWIR region (350–2500 nm). The continuum-removal technique was applied to compute radiometric indices associated with absorption features in the visible region and at 1400, 1900, and 2200 nm. Results demonstrated that these indices effectively captured the SOC spatial variability when combined with silt fraction and topographic attributes, which, among the other covariates, actually exhibited the strongest spatial relationships with SOC. Compared to univariate ordinary kriging, the multivariate geostatistical approach yielded improved prediction accuracy in cross-validation, mostly due to the use of hyperspectral indices as auxiliary variables. Moreover, the geostatistical analysis revealed that the multivariate frame of spatial association was characterized by two distinct spatial scales. The findings of this work then support the use of hyperspectral indices as valuable covariates for digital modelling of SOC distribution even in landscapes characterized by heterogeneous topography and pedology.

Soil Systems doi: 10.3390/soilsystems10020028

Authors: Masoud M. Ardestani Kateřina Čápová Filip Křivohlavý Adnan Mustafa Zdeněk Nesvadba Jan Frouz

While the effect of domestication on various aspects of plant ecophysiology has been studied, less is known about its effect on plant–soil interaction. Here, we studied three botanical species of barley in comparison with four old cultivars and four contemporary cultivars with bare soils and two perennial grasses. Aboveground and belowground biomass decreased from botanical species to old cultivars and contemporary cultivars. Aboveground biomass of all barley cultivars was about one third lower in mineral fertilizer compared to the organic one, and this difference was similar in all barley cultivars. Biomass of perennial grasses was up to one third of barley biomass, but grass biomass did not differ significantly between fertilization treatments. Belowground biomass of botanical barley is significantly higher than that of modern cultivars; this discrepancy is even more pronounced under mineral fertilizer where belowground biomass of botanical barley significantly increased, and that of modern cultivars significantly decreased in comparison with organic fertilizer treatment, which means that modern barley cultivar in combination with mineral fertilizers provides less belowground litter to soil. This in the long term can potentially, together with other factors, contribute to the depletion of cultivated soil for organic matter. Microbial respiration in soil did not differ between treatments supplied by organic fertilizer, while in mineral fertilizer treatments old cultivars had lower respiration than other treatments. Microbial biomass did not differ between treatments supplied by mineral fertilizer, but in treatments supported by organic fertilizer, perennial grasses supported more microbial biomass than all barley treatments. The same pattern was observed in C content in soil. Carbon distribution in individual soil fractions did not differ between perennial grasses and barley treatments. In general, when hotspots of organic matter were provided, plants transferred this organic matter to soil, and this activity was more pronounced in perennial grasses than in barley treatments.

Soil Systems doi: 10.3390/soilsystems10020027

Authors: Shimbahri Mesfin Mitiku Haile Girmay Gebresamuel Amanuel Zenebe Abera Gebre Okubay Giday Adhanom Lars Olav Eik Bal Ram Singh

Improving crop productivity largely depends on understanding soil fertility constraints and the effects of nutrient management on yield performance. Accurate determination of existing soil nutrient status and targeted application of limiting nutrients are essential for enhancing wheat (Triticum spp.) productivity. However, the specific effects of omitting one of the macronutrients such as nitrogen (N), phosphorus (P), or potassium (K) on wheat yield have not been investigated in the target area. This study employed the Quantitative Evaluation of the Fertility of Tropical Soils (QUEFTS) model to estimate the N, P, and K fertilizer requirements needed to achieve a predefined wheat yield target. The objectives were to: (i) evaluate yield responses to complete versus nutrient omission (N, P, or K) fertilization treatments, and (ii) analyze corresponding nutrient uptake and use efficiency dynamics. The experimental treatments included: (1) full NPK fertilization, (2) NP only (K omitted), (3) NK only (P omitted), (4) PK only (N omitted), and (5) an unfertilized control. Topsoil samples were analyzed and used as inputs for the QUEFTS model. Yield and agronomic data, as well as nutrient uptake and use efficiency, were measured. Model performance was validated using standard statistical metrics. Results showed that full NPK application significantly (p < 0.05) improved yield, yield components, and nutrient uptake compared to omission treatments and the control. The strong agreement between QUEFTS-predicted and observed yields highlights the model’s potential as a reliable, cost-effective decision-support tool for optimizing site-specific fertilizer recommendations. These findings demonstrate that balanced NPK fertilization markedly boosts wheat yield and nutrient uptake, while the QUEFTS model provides a powerful, reliable tool for tailoring fertilizer management to local soil conditions.

Soil Systems doi: 10.3390/soilsystems10020026

Authors: Zainulabdeen Kh. Al-Musawi Agampodi Gihan S. D. De Silva Jabir Ali Abdinoor László Bede Dávid Stencinger Bálint Horváth Sándor Zsebő Áron Licskai Gergő Hegedüs Viktória Vona Gyula Pinke Bahar Makbule Temeltürk Emőke Ruzsics István Mihály Kulmány

Agriculture must balance productivity with greenhouse gas emissions, biodiversity, and resource concerns. This study examined how tillage (conventional, CT; minimum, MT), nitrogen fertilisation (0–221 kg N ha−1), and herbicide rates (0–100%) interactively affected soil CO2 emissions, vegetation vigour, and weed diversity in maize production during 2022. A factorial experiment was conducted on a 1 ha with 40 plots monitored soil temperature, moisture, penetration resistance, normalised difference vegetation index (NDVI), weed diversity (Simpson’s Index), and CO2 emissions (closed-chamber method). Minimum tillage increased soil water retention (9.3 ± 6.5% vs. 5.4 ± 4.3%), soil temperature (28.0 ± 1.5), and compaction (0.6 ± 0.3 vs. 0.1 ± 0.0 MPa), while enhancing weed diversity (0.53–0.80 vs. 0.38–0.67). MT produced higher CO2 emissions than CT, especially at 147 kg N ha−1 (49.9 ± 15.7 vs. 29.1 ± 11.6 μmol m−2 s−1), peaking under MT-147 kg N ha−1-H75 (79.4 ± 1.2 μmol m−2 s−1). NDVI responses varied between tillage systems; under CT, vegetation vigour peaked at 75% herbicide application, while under MT vegetation was more responsive to nitrogen and more sensitive to herbicide, highlighting nitrogen × herbicide interaction trade-offs. Overall, MT enhanced water conservation and weed diversity but increased short-term CO2 emissions. This study reports first-year, site-specific results from an ongoing multi-year field experiment; therefore, the findings were interpreted as short-term, season-specific responses. This highlights the need for site-specific, climate-smart management that integrates emissions, soil health, biodiversity, and productivity.

Soil Systems doi: 10.3390/soilsystems10020025

Authors: Olga B. Rogova Dmitry S. Volkov Mikhail A. Proskurnin

FTIR spectroscopy, attenuated total reflection (ATR), and diffuse reflectance (DRIFT) modalities, along with ICP–AES spectroscopy and correlation analysis, including two-dimensional correlation spectroscopy (2DCOS), were used for the detailed analysis of Kastanozem (chestnut) soils. Microaggregates (20–200 μm) and macroaggregates (200–1000 μm) of characteristic horizons of uncultivated (fallow) and cultivated (arable land) chestnut soils of the same origin were physically fractionated by wet sieving. The combination of these molecular and atomic spectroscopy techniques in combination with correlation analysis was able to find direct correlations between matrix-forming anions and soil organic matter (SOM) of Kastanozems. Humic substances were separated from the corresponding soil samples to reveal SOM contributions more explicitly. Microaggregates of the size fractions of 20–40 μm and 40–60 μm bore the most comprehensive information for both techniques used. Most significant differences between land-use Kastanozem samples were observed in topsoil horizons (arable P versus light-colored humic AJ horizon), and for the next pair of horizons along the profile xerometamorphic BMK horizon to structural metamorphic BM horizon. These differences included carbonate matrix and SOM amounts and composition. Topsoil arable land showed significantly smaller amounts of total organic carbon and a decrease in the share of long-chain hydrocarbons compared to fallow, which has a more distinctive character compared to similar land-use samples of Chernozem. An increase in carbonate contents with soil depth was found for both land-use samples, while the amounts and composition of the silicate matrix remained largely unchanged within the depth profile. The heterospectral 2DCOS comparison of FTIR (between horizons and land-use samples), ICP–AES (between land-use samples), and FTIR–AES (for the same sample) showed the possibility of a more reliable attribution of FTIR absorption bands and revealed the differences in the macro- and micro-aggregate elemental and SOM composition of Kastanozems.

Soil Systems doi: 10.3390/soilsystems10020024

Authors: Viacheslav Vasenev Robin van Velthuijsen Marcel R. Hoosbeek Yury Dvornikov Maria V. Korneykova

The development of urban green infrastructures (UGI) is considered among the main nature-based solutions for climate mitigation in cities; however, the role of soils in the carbon (C) balance of UGI ecosystems remains largely overlooked. Urban green spaces are typically dominated by constructed Technosols, created by adding organic materials on top of former natural or agricultural subsoils. The combined effects of land-use history and current UGI management result in a high spatial variation of soil organic carbon (SOC) stocks and soil CO2 emissions. Our study aimed to explore this variation for the case of Wageningen University campus. Developed on a former agricultural land, the campus area includes green spaces dominated by trees, shrubs, lawns, and herbs, with well-documented management practices for each vegetation type. Across the campus area (~32 ha), a random stratified topsoil sampling (n = 90) was conducted to map the spatial variation of topsoil (0–10 cm) SOC stocks. At the key sites (n = 8), representing different vegetation types and time of development (old, intermediate, and recent), SOC profile distribution was analyzed including SOC fractionation in surface and subsequent horizons, as well as the dynamics in soil CO2 emissions, temperature, and moisture. Topsoil SOC contents on campus ranged from 1.1 to 5.5% (95% confidence interval). On average, SOC stocks under trees and shrubs were 10–15% higher than those under lawns and herbs. The highest CO2 emissions were observed from soil under lawns and coincided with a high proportion of labile SOC fraction. Temporal dynamics in soil CO2 emissions were mainly driven by soil temperature, with the strongest relation (R2 = 0.71–0.88) observed for lawns. Extrapolating this relationship to the calendar year and across the campus area using high-resolution remote sensing data on surface temperatures resulted in a map of the CO2 emissions/SOC stocks ratio, used as a spatial proxy for C turnover. Areas dominated by recent and intermediate lawns emerged as hotspots of rapid C turnover, highlighting important differences in the role of various UGI types in the C balance of urban green spaces.

Soil Systems doi: 10.3390/soilsystems10020023

Authors: Yiyi Sulaeman Nana Sutrisna Joko Pramono Lilia Fauziah Ahmad Suriadi Heppy Suci Wulanningtyas Eni Maftu’ah Endang Gati Lestari Anny Mulyani

Sorghum is a strategic crop for food, feed, and bioenergy. However, information on its cultivation area and agronomic profile in Indonesia remains limited. Therefore, this study aimed to identify, characterize, and evaluate sorghum cultivation in different agroecosystems and pedoagroclimatic settings in Indonesia. We surveyed published articles, newspapers, and other digital resources, collating a dataset that contained pedoagroclimatic characteristics. We then conducted a field survey to gather data on sorghum farming practices. The results show that sorghum is planted in 11 agroclimatic zones, mainly in D3, B1, and E4, and in seven soil types, mainly in Inceptisols, Mollisols, Vertisols, and Andisols. The cultivated varieties cover Bioguma 1, Bioguma 2, Bioguma 3, Numbu, Kawali, UPCA-S1, Suri 3 Agritan, Soper 9, and local varieties. Under smallholder farmers’ management, the average sorghum yield ranges from 3.6 to 7.5 Mg ha−1. The 15–68% of the yield gap can be closed by implementing site-specific technologies, including high-yielding varieties and soil management. These findings provide a baseline for supporting efforts to increase sorghum production and develop robust sorghum cultivation technologies.

Soil Systems doi: 10.3390/soilsystems10020022

Authors: Bernard Gagnon Noura Ziadi

The application of forest byproducts to cropland provides significant benefits, mitigating soil degradation, supplying essential nutrients, and increasing yields. Their impact is well known in the first years, but few studies have examined the effects several years after an application. A field study was initiated in Québec, QC, Canada, to assess the effects of wood ash (10 and 20 Mg dry wt. ha−1), pine biochar (10 Mg dry wt. ha−1), paper mill sludge (PS) (12 Mg dry wt. ha−1), and a combination of wood ash and PS, relative to an untreated control and a mineral treatment, on crop yield and soil properties three to seven years after application in a temperate circumneutral loamy soil. The site was cropped to a maize (Zea mays L.)–soybean [Glycine max (L.) Merr.]–spring wheat (Triticum aestivum L.) rotation. Each crop received supplemental N and P from mineral fertilizers, when needed, according to local agronomic recommendations. Applying wood ash increased wheat yield by 0.25–0.44 Mg ha−1 three years after the addition, but no effect was detected in other cases and for the other amendments. Wood ash also resulted in the largest increases (p < 0.05) in soil pH and Mehlich-3 P, K, Ca, Mg, Zn, and Cd, alone or in combination with PS. Pine biochar promoted soil C sequestration after seven years, but did not affect other soil properties owing to its high stability and low nutrient content. This study revealed that wood ash was more advantageous than pine biochar for improving soil quality and crop productivity.

Soil Systems doi: 10.3390/soilsystems10020021

Authors: Md Abdul Halim Md Rezaul Karim Nigel V. Gale Sean C. Thomas

Tea (Camellia sinensis) cultivation is a major global industry that faces sustainability challenges due to soil degradation and greenhouse gas (GHG) emissions from intensive management. Biochar—charcoal designed and used as a soil amendment—has emerged as a potential tool to improve soil health, enhance carbon sequestration, and mitigate GHG fluxes in agroecosystems. However, field-scale evidence of its effects on GHG dynamics in woody crops like tea remains limited, particularly regarding methane (CH4). Here, we present, to our knowledge, the first field assessment of biochar impacts on CO2, CH4, and H2O vapour fluxes in a subtropical tea agroforestry system with and without shade trees in northeastern Bangladesh. Using a closed dynamic chamber and real-time gas analysis, we found that biochar application (at 7.5 t·ha−1) significantly enhanced average soil methane (CH4) uptake by 84%, while soil respiration (CO2 efflux) rose modestly (+18%) and water-vapour fluxes showed a marginal increase. Canopy conditions modulated these effects: biochar strongly enhanced CH4 uptake under both shaded and open canopies, whereas biochar effects on water-vapour flux were detectable only when biochar was combined with a shade-tree canopy. Structural equation modelling suggests that CH4 flux was primarily governed by biochar-induced changes in soil pH, moisture, nutrient status, and temperature, while CO2 and H2O fluxes were shaped by organic matter availability, temperature, and phosphorus dynamics. These findings demonstrate that biochar can promote CH4 uptake and alter soil carbon–water interactions during the dry season in tea plantation systems and support operational biochar use in combination with shade-tree agroforestry.

Soil Systems doi: 10.3390/soilsystems10010020

Authors: Matthias Filipiak Katrin Kuka

Chemical soil properties contribute to the resilience of soil ecosystems. Healthy soils with optimal nutrient levels, balanced pH and good organic matter content are better able to withstand environmental stresses, such as drought, disease or pests. When comparing the chemical soil properties of temperate grassland and arable land, several differences can be observed due to differences in soil cover and management. Grasslands typically sequester more carbon, limit nitrogen leaching, and have lower nitrous oxide emissions and losses of phosphorus due to less soil disturbance and a more closed nutrient cycle. In contrast, arable land has higher nutrient losses through harvest, leaching, gaseous emissions and erosion due to regular tillage, frequent bare phases, and sequesters less carbon, typically due to higher mineralisation rates and lower nutrient returns. Monitoring and managing chemical soil properties, appropriate nutrient management, addition of organic matter such as organic fertilisers, inclusion of grassland phases and catch crops in crop rotations, incorporation of crop residues into the topsoil after harvest and further sustainable agricultural practices are essential to promote soil health. By optimising chemical soil properties, farmers and land managers can improve productivity, conserve natural resources and support the long-term sustainability of the soil ecosystem.

Soil Systems doi: 10.3390/soilsystems10010019

Authors: Marco Aurélio Barbosa Alves Daniela Roberta Borella Frederico Terra de Almeida Adilson Pacheco de Souza Daniel Fonseca de Carvalho

The conversion of native forests into agricultural areas without conservation practices can expose tons of soil organic carbon (SOC) to the atmosphere. This study aimed to evaluate the effect of land use and cover (LULC) on C in regions of the Caiabi (SBC) and Renato (SBR) River sub-basins, located in the Brazilian Cerrado–Amazon transition. Data on physical attributes and SOC were obtained by region (upper, middle, and lower), LULC (cropland, pasture, and native forest), and depth (0–10, 10–20, and 20–40 cm), with five replicates for each variable. The highest SOC values were found in areas with higher clay contents or in areas of native forest or crop residues. In the SBC, there was a negative correlation of SOC with sand and particle density (PD) and a positive correlation with silt. In the SBR, there was a positive correlation between SOC and microporosity and total porosity, and a negative correlation with sand, soil bulk density, and PD. The highest SOC values were found in the SBC upper region, in native forest (107 Mg ha−1), cropland (69 Mg ha−1), and pasture (49 Mg ha−1). In the SBR upper region, the values were highest in pasture and cropland (93 and 58 Mg ha−1), and in the lower region, the values were highest in native forest (48 Mg ha−1). SOC varied in relation to the SBC and SBR regions, the LULC, depth, and physical attributes, especially soil texture.

Soil Systems doi: 10.3390/soilsystems10010018

Authors: Jan Adriaan Reijneveld Nico Rodenburg Marius Heinen Johan Bouma

A recent report on the future of agriculture by the European Commission emphasizes the need for sustainable development on a farm level to be characterized by measuring ecosystem services with indicators and corresponding thresholds. This case study raises the question whether or not operational methods are currently available to allow such measurements under practical field conditions. To broaden the scope of this case study to the international policy arena, the measurement of ecosystem services was linked to selected UN Sustainable Development Goals (SDGs). The case study showed that operational methods are currently available to measure and judge ecosystem services related to the following: the production of healthy food, water quality, greenhouse gas emissions, biodiversity, and soil health. This conclusion was, however, only possible when applying innovative sensing and laboratory techniques to measure pesticide and heavy metal contents and soil microbiology. Soil health is not only important as an ecosystem service, as such, but also plays a major role in realizing the other ecosystem services. Once all ecosystem services are satisfied on a particular farm, a farmer is free to follow his own unique management practices free from top-down governmental rules and regulations that focus now on required management measures. Each farmer can pursue the goals in a way that best aligns with his own vision, context, and creativity.

Soil Systems doi: 10.3390/soilsystems10010017

Authors: Yacine Benhalima Erika S. Santos Diego Arán

This study examined long-term changes in soil carbon stock dynamics 11 and 19 years after fire under different severities at 0–5 and 0–25 cm depths with a digital soil mapping approach. Linear (MLR) and non-linear models (RF, SVR, XGBoost) combined with feature selection methods (r < 0.8, FFS, Boruta) were used to predict bulk density (BD), total C, and C stock. Distributional biases were evaluated with Kolmogorov–Smirnov statistics and corrected by Quantile Mapping (QM). RF-FFS performed best for BD and total C at 0–5, while RF-SVR outperformed for C stock and all properties at 0–25. Total C was 49% higher at 0–5, whereas C stock was 7.57 times greater at 0–25. Both models underestimated variability, especially for C stock. At 0–25, bulk density decreased after fire, particularly under conditions of medium severity, while total C increased following the same tendency. The results showed that fire’s legacy is still present in the ecosystem after one and two decades. This is particularly evident at greater depths, where long-term C stock is lower.

Soil Systems doi: 10.3390/soilsystems10010016

Authors: Lei Song Peifeng Xu Xiaorong Zhang Zongqiang Gong

The surface chemistry of biochar plays a pivotal role in the adsorption and stabilization of soil organic carbon (SOC); however, sorption-mediated mechanisms remain insufficiently understood for biochars derived from invasive plants. In this study, Solanum rostratum biomass, an aggressive invasive weed in northern China, was pyrolyzed at 400–600 °C in 2023 to produce biochars with varying surface functionalities and structural features. FTIR, Raman, XPS, and SEM analyses revealed that increasing pyrolysis temperature led to decreased oxygen-containing functional groups and enhanced aromatic condensation, reflecting a transition from hydrogen bonding to π–π and hydrophobic sorption mechanisms. Soil incubation experiments using sandy loam soil showed that biochar produced at 500 °C significantly increased the stable carbon pool (SCP) to 52.4%, compared to 30.6% in unamended soils. It also reduced cumulative CO2 release from 1.74 mg g−1 to 1.21 mg g−1 soil, indicating improved carbon retention. Bacterial 16S rRNA gene sequencing revealed that biochar amendments significantly altered community composition and increased deterministic assembly, particularly under 500 °C biochar, suggesting a sorption-driven niche filtering effect. These findings demonstrate that S. rostratum-derived biochar, especially at intermediate pyrolysis temperatures, enhances both carbon sequestration and microbial habitat structure. This has direct implications for improving degraded soils in arid farming regions, offering a dual strategy for invasive biomass management and climate-resilient agriculture.

Soil Systems doi: 10.3390/soilsystems10010015

Authors: Zhizhong Li Madjid Hadioui Kevin J. Wilkinson

In soils, it is key to not simply determine the behavior of the major elements but also understand the fate of trace and ultra-trace elements that can often have disproportionate effects on these complex systems. Soils, including agricultural soils, constitute a reservoir of nanoparticles and natural colloids of multiple origins. Nonetheless, only limited information is available on the concentrations and fate of nanoparticles in soils, due largely to the difficulty of distinguishing anthropogenically generated particles from the complex soil matrices in which they are found. Bulk measurements are often unable to quantify the key contributions of trace pollutants (i.e., needle in a haystack); however, single particle techniques have recently become available for studying complex agricultural systems, including soils. For example, the characterization of engineered nanoparticles or incidentally generated particulate pollutants within a natural soil or sediment is now possible using techniques such as single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). Nonetheless, in order to exploit the single particle techniques, it is first necessary to representatively sample the soils. The approach presented here has been designed to help better understand the impact of incidental and engineered nanoparticles on agricultural soils. In this study, we examine two approaches for extracting colloidal particles (CP) from soils in order to facilitate their characterization by single particle inductively coupled plasma mass spectrometry using a sector field- (SP-ICP-SF-MS) and time-of-flight- (SP-ICP-ToF-MS) based instruments. A novel sampling methodology consisting of an ultrasound-assisted continuous-flow extraction (USCFE) was developed and compared to a commonly used batch extraction procedure. Metal containing colloidal particles (M–CP) were quantified and characterized following their extraction in ultrapure water and tetrasodium pyrophosphate (TSPP). At least five successive extraction cycles of 18 h each were required to optimally extract Si–CP (ca. 6 × 1015 kg−1) using the batch extraction approach, whereas similarly high numbers of CP could be extracted by USCFE in about 3 h. The combined use of continuous flow, ultrasound and TSPP improved the sampling of colloidal particles and nanoparticles from an agricultural soil. Due to its higher sensitivity, SP-ICP-SF-MS was used to measure the smallest detectable M–CP in the soil extracts. SP-ICP-ToF-MS was used to determine the multi-elemental composition of the extracted colloidal particles.

Soil Systems doi: 10.3390/soilsystems10010014

Authors: Evgeny Lodygin

The issue of formulating scientifically sound standards for mercury (Hg) content in Arctic soils is becoming increasingly pertinent in view of the rising human impact and climate change, which serve to augment the mobility of Hg compounds and their involvement in biogeochemical processes. In the absence of uniform criteria for regulating Hg concentrations, it is particularly important to determine its geochemical baseline values and the factors that determine the spatial and vertical distribution of the element in the soil profile. The study conducted a comprehensive investigation of Hg content and patterns of its distribution in various types of tundra soils in the European North-East of Russia. The mass fraction of total Hg was determined by atomic absorption spectrometry, and the spatial features of accumulation were analysed using geoinformation technologies. The distribution of Hg in the soils of the tundra zone was found to be distinctly mosaic in nature, determined by the combined influence of organic matter, granulometric composition, and hydrothermal conditions. It has been established that the complex influence of the physicochemical properties of soils determines the spatial heterogeneity of Hg distribution in the soils of the tundra zone. The most effective Hg accumulators are peat and gley horizons enriched with organic matter and physical clay fraction, while in Podzols, vertical migration of Hg is observed in the presence of a leaching water regime. In order to standardise geochemical baseline Hg values, a 95% upper confidence limit (UCL95%) is proposed. This approach enables the consideration of natural background fluctuations and the exclusion of extreme values. The results obtained provide a scientific basis for the establishment of standards for Hg content in background soils of the Arctic.

Soil Systems doi: 10.3390/soilsystems10010013

Authors: Mohamed El Hassan Bouchari Abdelilah Meddich Abderrahim Boutasknit Redouane Ouhaddou Boujemaa Fassih Lahoucine Ech-Chatir Mohamed Anli Abdelmajid Haddioui

In the context of climate change, alterations to the physico-chemical properties of soils, particularly in Mediterranean regions, are a growing source of preoccupation. This study analyzes the ecological plasticity and biochemical adaptability of Thymus saturejoides to changes in soil physico-chemical properties in four contrasting environments in Morocco’s western High Atlas (TM: Tidili msfioua, SF: Sti fadma, TA: Taouss, TN: Tisi ntast). It highlights the influence of edaphic characteristics on the physiology and metabolic composition of the species, revealing marked soil heterogeneity between sites. The results for the physico-chemical characteristics of the soil revealed marked heterogeneity between sites. Tisi ntast and Taouss soils had the highest values in terms of electrical conductivity (TN: 0.25 dS/m, TA: 0.18 dS/m), available phosphorus (TN: 18.58 ppm and TA: 26.06 ppm) and total nitrogen (TN: 0.27% and TA: 0.14%), associated with a silty texture, suggesting higher fertility. Conversely, the soil at the TM site was characterized by low total nitrogen content (0.09%), a high C/N ratio (24.4) and a sandy-silty texture, indicating more constraining conditions for plant growth. From a physiological standpoint, plants from the TA site had the lowest chlorophyll levels (17.10 mg g−1FW), while those from the TN site showed the highest levels (31.08 mg g−1FW), accompanied by increased protein content and reduced polyphenol oxidase and peroxidase. In contrast, TM plants showed significant accumulation of total soluble sugars (30 mg g−1FW), proline (22.53 µmol g−1FW), hydrogen peroxide (1.33 nmol g−1FW) and malondialdehyde (62.97 nmol g−1FW), reflecting strong activation of oxidative stress responses. On the other hand, plants from the TA site displayed significantly lower levels of these stress markers compared to other sites, suggesting greater physiological resilience. These results highlight the pivotal role of interactions between edaphic and environmental conditions in modulating plant physiological and biochemical responses, shedding light on the ecological adaptation mechanisms of plant species to the contrasting ecosystems of the Western High Atlas.

Soil Systems doi: 10.3390/soilsystems10010012

Authors: María del Pilar Fernandez-Murillo Erasmo Cifuentes Antonia Beggs Marlene Manzano Ignacio Gutiérrez-Cortés Constanza Vargas Camilo del Río Fernando D. Alfaro

Marine fog is a key non-rainfall water source that sustains microbial activity and transports dissolved nutrients inland, influencing early soil development in hyperarid ecosystems. However, the mechanisms through which sustained fog inputs drive soil surface modification and biocrust formation remain poorly understood. This study evaluated the effects of long-term fog augmentation on soil surface development, biocrust dynamics, and associated microbial communities in the Atacama Desert. We implemented a four-year fog addition field experiment with three sampling times (T0, T24, T48) to assess changes in soil physicochemical properties, biocrust composition, and the integrated multi-diversity of archaea, bacteria, fungi and protist. Sustained fog input transformed bare soils into biological soil crusts, particularly lichen- and moss-dominated stages. This transition was accompanied by increases in soil nitrogen, variations in organic matter accumulation, a shift from alkaline to near-neutral pH, and improvements in soil stability and water retention. Multi-diversity increased over time and was positively associated with ecosystem variables linked to water availability, structural stabilization, and decomposition. These functions, integrated into an ecosystem multifunctionality index, also increased under prolonged fog input, revealing a positive relationship between multifunctionality and multi-diversity. Overall, the results demonstrate that sustained fog input strongly enhances early soil surface development and biocrust establishment, highlighting the ecological importance of marine fog in shaping biodiversity and ecosystem functioning in hyperarid landscapes.

Soil Systems doi: 10.3390/soilsystems10010011

Authors: Azamat Suleymanov Mikhail Komissarov Ruslan Suleymanov Ilyusya Gabbasova

Soil structure is one of the key soil water-physical properties that determine the water–air regime and ultimately affect soil fertility. This study aimed to test different machine learning (ML) methods in combination with environmental variables (soil and climate) and remote sensing data derived from Landsat 8 for prediction of key structure parameters of topsoil (0–25 cm) in semi-arid areas (Trans-Ural steppe zone, Republic of Bashkortostan, Russia). The all studied soil types (Chernozems (n = 24), Solonchaks (n = 9)) and Solonetzes (n = 12)) characterized by “excellent” aggregate state (the average structural coefficient (Ks) was 6.52, 11.23 and 5.70) and “good” resistance of aggregates to destruction by water (soil aggregate stability coefficient (Ksas)—0.67, 0.65 and 0.70, respectively). The soils had a high proportion of agronomically valuable aggregates (0.25–10 mm, mesoaggregates (MEA)), and a low proportion of blocky/lumpy (>10 mm, macroaggregates (MAA)) and fine/dusty (<0.25 mm, microaggregates (MIA)) ones. In particular, the average share of MIA, MEA, and MAA in Chernozem was 7.63, 83.20, and 11.73%, and in Solonchak, 4.24, 87.91, and 9.74%, respectively. After wet sifting, the water-resistant macroaggregates (WSMAA) were not identified (they were destroyed by water) in all studied soils; the proportion of water-stable mesoaggregates (WSMEA) in Chernozems was 65.92 and microaggregates (WSMIA)—39.67; Solonchaks—74.95 and 22.54; Solonetz soil—66.77 and 33.22%; respectively. Under the ML framework, the best model was achieved for Ksas predictions (R2 = 0.50 and RMSE 0.17), where spectral indices (NDWI, EVI, SAVI, and NDVI) were the main predictors. Other ML techniques explained 22-30% variance of the remaining properties. The findings of this study can be valuable in further endeavors for soil water-physical mapping and accelerate the adoption of measures for land management/reclamation planning for landscapes with similar (arid and semi-arid) natural climatic conditions.

Soil Systems doi: 10.3390/soilsystems10010010

Authors: Patrícia da Silva Gomes Assunção Andrade de Barcelos João Batista Pereira Cabral Fernanda Luisa Ramalho Hudson Moraes Rocha Valter Antonio Becegato Alexandre Tadeu Paulino

This study aimed to quantify and assess the spatial distribution of 238U, 232Th, and 40K in the soils of the Espora Hydroelectric Power Plant (Espora HPP) and Queixada Small Hydroelectric Power Plant (Queixada SHPP) watershed (model hydraulic development areas) and their relationship with the geological, chemical, physical, and biological aspects of the soil. The study areas are located in the Corrente River drainage basin, in the southwestern portion of the state of Goiás, Brazil. Radionuclides were quantified using a PGIS-2 portable gamma spectrometer, with measurements taken at 21 sampling points. Soil samples were collected from the surface layer (0–20 cm) for particle-size and chemical analyses. The results indicated that the average radionuclide contents in the soils were 64.49 Bq/kg for 40K, 45.44 Bq/kg for 238U, and 4.53 Bq/kg for 232Th. When comparing these values with the global average established by UNSCEAR, it was observed that 232Th and 40K concentrations were below the global reference, whereas 238U concentration exceeded the world average of 33 Bq/kg. Particle-size characterization revealed significant variability in soil texture, with sand content ranging from 51.46 to 90.91%, clay content from 7.45 to 30.64%, and silt content from 1.64 to 17.90%. Organic matter content had an average of 10.09 g/kg, while soil pH ranged from 4.67 to 6.54. The results of this study have demonstrated the relevance of integrating radiometric and geochemical data for assessing environmental safety in hydroelectric development areas. The approach adopted can support monitoring programs and decision-making processes related to soil management and land-use planning in regions influenced by hydraulic infrastructures.

Soil Systems doi: 10.3390/soilsystems10010009

Authors: Marwa Zouari Mohamed Hachicha Ewald Schnug

In arid regions, irrigation is essential for sustaining crop production, but irrigation water often contains high levels of salts that may reduce yields. This study aimed to evaluate crop responses to irrigation water with salinity levels exceeding 4 g/L (≈6.25 dS/m). A large-scale field survey was conducted across several Tunisian governorates, covering a wide range of crops and production systems. Irrigation water salinity and corresponding crop yields were recorded and analyzed to determine tolerance patterns under real farming conditions. Results indicate that, even under high salinity conditions, several cropssuch as carrot (Daucus carota), barley (Hordeum vulgare), and tomato (Solanum lycpersicum), can maintain high yields, highlighting their potential for saline irrigation in arid regions. These findings provide valuable insights for irrigation management, crop selection, and the development of sustainable agricultural practices in arid environments.

Soil Systems doi: 10.3390/soilsystems10010008

Authors: Mohamed Rajhi Tamas Deak Endre Dobos

Accurate prediction of soil texture is essential for effective soil management, precision agriculture, and hydrological modeling. This study proposes a novel, data-driven approach for estimating soil texture without the need for laboratory-based analysis. High-frequency in situ soil moisture measurements from EnviroSCAN (Sentek Technologies, Stepney, Australia) sensors and satellite-derived vegetation indices (NDVI) from Sentinel-2 were collected across 25 sites in Hungary. Temporal soil moisture dynamics were encoded using a Long Short-Term Memory (LSTM) neural network, designed to capture soil-specific hydrological response behavior from time-series data. The resulting latent embeddings were subsequently used within an ordinal regression framework to predict ordered soil texture classes, explicitly enforcing physical consistency between classes. Model performance was evaluated using leave-one-soil-out cross-validation, achieving an overall classification accuracy of 0.54 and a mean absolute error (MAE) of 0.50, indicating predominantly adjacent-class errors. The proposed approach demonstrates that soil texture can be inferred from dynamic environmental responses alone, offering a transferable alternative to fraction-based regression models and supporting scalable sensor calibration and digital soil mapping in data-scarce regions.

Soil Systems doi: 10.3390/soilsystems10010007

Authors: Ledemar Carlos Vahl Roberto Carlos Doring Wolter Antônio Costa de Oliveira Filipe Selau Carlos Robson Bosa dos Reis Rogério Oliveira de Sousa

In flooded soils, the concentrations of exchangeable Mn2+ and, especially, Fe2+ can be high and must be considered when determining the cation exchange capacity (CEC) of the soil under flooded conditions. However, these reduced forms of Mn and Fe are oxidized and precipitated during the extraction process used in traditional CEC methods. This procedure underestimates the exchangeable portion of these cations and, consequently, the CEC value of the flooded soil. We introduce a pH-gradient-based model to predict ECEC and exchangeable Fe2+ in flooded soils, circumventing oxidation artifacts inherent in conventional methods. The objective of this study is to propose an alternative to estimate the exchangeable Fe2+ and the effective CEC (ECEC) of flooded soils. To achieve this goal, 21 surface samples (0–20 cm) of soil from rice fields were collected and distributed in the cultivation regions of southern Brazil. The soils were flooded for 50 days. The soil solution was collected on the first day and after 50 days of flooding and pH, Na, K, Ca, Mg, Fe and Mn were determined. In these samples, exchangeable cations (K, Na, Ca, Mg, Mn, Al and H + Al) were determined to calculate ECEC and CEC at pH 7 of unflooded soil and after 50 days of flooding. There was a wide range of variation in the exchangeable cation contents among the soil samples. The K contents ranged from 0.12 to 0.54 cmolc kg−1, the Na contents from 0.00 to 1.18 cmolc kg−1, the Ca contents from 0.48 to 37.31 cmolc kg−1, the Mg contents from 0.10 to 15.53 cmolc kg−1, the Mn contents from 0.01 to 0.36 cmolc kg−1, the Al contents from 0.10 to 1.74 cmolc kg−1 and the H + Al contents from 2.01 to 8.42 cmolc kg−1. The results were used to develop models to predict ECEC and exchangeable Fe content after 50 days of flooding. Estimating the ECEC after flooding using the pH gradient before and after flooding yielded values closer to CEC pH 7.0, correcting for the possible underestimation of the ECEC during flooding. The amount of exchangeable Fe estimated was higher than the exchangeable Fe determined, correcting the possible underestimation of these quantities determined during flooding. It is concluded that the estimations of ECEC after flooding through the equation ECECafter=ECEC+pHsol.after− pHsol.before × (CECpH7− ECEC)(7− pHsol.before), where pHsol.before is pre-flooding soil pH, pHsol.after is after flooding pH, ECECafter is effective CEC after flooding and the exchangeable Fe2+ after flooding through the equation Feexc.after.estimated=ECECafter− Ca+Mg+K+Na+Mn where Feexc.after.estimated is estimated exchangeable Fe2+ after flooding corrected the problem of underestimating the values of these variables by analytical methods, demonstrating its viability for use in flood-prone soils.

Soil Systems doi: 10.3390/soilsystems10010006

Authors: Yu Fan Pengrui Ai Fengxiu Li Tong Heng Yan Xu Zhifeng Wang Zhenghu Ma Yingjie Ma

Freshwater scarcity in arid regions is driving increased use of saline irrigation, yet salinity severely degrades soil structure and suppresses enzymatic function. To address this critical challenge for sustainable soil management, this study systematically evaluated magnetized saline water (MSW) across three salinity levels (1, 3, and 6 g L−1) and four magnetic field strengths (0, 0.2, 0.4, and 0.6 T), confirming the magnetic field intensity (C) × salinity (S) interaction. The comprehensive analysis integrated data on aggregate stability, key ion concentrations (Ca2+, Mg2+, Cl−), and major enzyme activities. Structural Equation Modeling (SEM) was utilized to quantify the underlying mechanisms, demonstrating that structural improvement is primarily driven by strong indirect pathways, mediated by optimized ion dynamics and increased enzyme-mediated organic matter turnover. The moderate-salinity (3 g L−1), moderate-magnetic-field (0.4 T) regime emerged as the optimal balanced strategy for overall soil health. These findings offer a scalable approach, guiding future field-scale research toward long-term agricultural sustainability.

Soil Systems doi: 10.3390/soilsystems10010005

Authors: Pinchas Fine Arie Bosak Anna Beriozkin Dorit Shargil Uri Mingelgrin Yephet Ben-Yephet Daniel Kurtzman Ido Nitzan Shahar Baram Ami Gips Tali Kolokovski Amos Ovadia Efraim Zipilevish Uri Zig Oren Buchshtab

Application of CFA-treated biosolids (NVS) offers multiple benefits to agricultural soils, including fertilizer replacement, soil rehabilitation, and disinfection. It also poses a heavy metal(loid)s threat to the agro-environment. NVS (and CFA to some extent) was tested in lysimeter and field trials, using soils differing in physicochemical properties and a large selection of crops. Consistently, As, Pb, and Cd concentrations in leachate were at or below detection limit, and these and other heavy metal(loid)s (and P) were within the permitted range in plant tissue. Foliage Mo (occasionally also Se, P) concentrations often increased significantly, especially in crops (legumes, potatoes) grown on marginal soils, which also displayed significantly higher yields. CFA and NVS reduced lettuce and legumes foliage Mn (and occasionally Zn) concentrations, which remained, however, adequate. NVS (214 and 642 mT ha−1), digested sewage sludge (ADS) and its compost (24 and 72 mT ha−1), temporarily increased the DTPA-extractability of some elements (NVS: B, Cr; ADS: Cu, Ni, Zn; Compost: Zn) 10–30-fold. The extractabilities of Fe and P increased by up to six times. These increases vanished soon after additive application, supporting the hypothesis of ‘self-attenuation’ by applied biosolids. Our data indicate that long-term application of NVS (and CFA) to calcareous soils poses no heavy metal(loid)s-related threat to the agro-environment.

Soil Systems doi: 10.3390/soilsystems10010004

Authors: Sergey N. Gorbov Nadezhda V. Salnik Suleiman S. Tagiverdiev Marina V. Slukovskaya Margarita V. Kochkina Svetlana A. Tishchenko Elena V. Gershelis Vyacheslav V. Kremenetskiy Alexander V. Olchev

This study is one of the first comprehensive assessments of soil carbon dynamics on the Black Sea coast of Russia, focusing on the role of soils in the terrestrial carbon cycle and the greenhouse gas balance of sub-Mediterranean ecosystems. Our integrated approach combined soil classification with the analysis of the distribution of organic and inorganic carbon, as well as the measurement of microbial biomass and respiration. Soil respiration components, including substrate-induced respiration (SIR) and basal respiration (BR), as well as greenhouse gas (carbon dioxide (CO2) and methane (CH4)) dynamics, were evaluated using a combination of laboratory and field measurements. Our results revealed significant differences between natural Rendzic Leptosols and terraced Skeletic Rendzic Leptosols (Technic and Transportic types). The latter contained higher organic carbon stocks (up to 25 kg m−2) associated with buried humus horizons, whereas the former were dominated by inorganic carbon accumulation. Microbial biomass carbon (MBC) ranged from 113 to 1119 µg C g−1 of soil and decreased with depth. Basal respiration averaged 0.39 ± 0.30 µg C–CO2 g−1 h−1. CO2 emissions were strongly correlated with soil temperature (r = 0.65, p < 0.05) and negatively correlated with soil moisture, reflecting the predominant influence of abiotic factors. Seasonal chamber observations confirmed that these soils consistently function as CH4 sinks, with negative CH4 fluxes recorded across all seasons. Thus, Rendzic Leptosols on the Black Sea coast serve as significant CO2 sources and stable CH4 sinks simultaneously, and anthropogenic terracing enhances their potential for organic carbon sequestration. These findings refine our understanding of the carbon balance in sub-Mediterranean forest soils and highlight their dual role in greenhouse gas dynamics under changing climate conditions.

Soil Systems doi: 10.3390/soilsystems10010003

Authors: Hartina Tidarat Monkham Worachart Wisawapipat Patma Vityakon Tanabhat-Sakorn Sukitprapanon

Managing phosphorus (P) in acidic paddy soils is crucial for sustaining rice yields. However, the effects of combined humic acid (HA) and flue gas desulfurization gypsum (FG), a by-product of coal-fired power plants, on P forms remain poorly understood. This study examined P forms using a sequential extraction procedure and XANES spectroscopy following the application of HA, FG, and HA + FG. HA increased organic labile P, while FG and HA + FG promoted HCl-extractable Pi and humic Po, respectively. XANES data revealed that P associated with aluminum (Al) (hydr)oxides was dominant in acidic paddy soils. Brushite (CaHPO4·2(H2O)) accounted for 25% and 19% of total P in the FG- and HA + FG-treated soil, respectively. Iron (Fe)-bound P was absent in control and FG-treated soils but was present as strengite (FePO4·2H2O) in HA- and HA + FG-treated soils (23% and 30% of the total P, respectively). Inositol hexakisphosphate (IHP), a non-labile Po, was in HA- and HA + FG-treated soil (12% and 31% of the total P, respectively). Archerite (KH2PO4) was 40% and 20% of the total P in HA- and HA + FG-treated soil, respectively. HA alone is an effective soil amendment that enhances P cycling and availability by increasing organic P mineralization, boosting rice yield in acidic paddy soil.

Soil Systems doi: 10.3390/soilsystems10010002

Authors: Aaron Ohene Boanor Rose Nimoh Serwaa Jin Hee Park Jwakyung Sung

Long-term exposure of plastics to the environment causes them to disintegrate, resulting in the formation of micro/nanoplastics as well as the release of additives and chemicals into the soil. The micro/nanoplastics are able to readily migrate into the soil, destabilize the soil microbiota, and finally enter crop plants. Endocytosis, apoplastic transport, root adsorption, transpiration pull, stomatal entry, and crack-entry mode are well-known pathways by which microplastics enter into plants. Roots of vegetable crops were able to transfer 0.2 µm–1.0 µm of microplastics through root adsorption and by transpiration pull to the xylem and then further transported them to the plant tissues through apoplastic pathways. Beads of 1000 nm size were also engulfed by BY-2 protoplast cells through endocytosis. Micro and nanoplastics that enter crops affected the physiological and biochemical activities of the plants. Aquaporins were needed to aid the symplastic pathway which made the symplastic pathway difficult for MPs/NPs transport. Microplastics block seed capsules and roots of seedlings, thereby negatively affecting the uptake and efficient use of nutrients supplied. Photosynthesis of plants was affected due to the reduction in chlorophyll contents. Exposing soils to MPs/NPs drastically affected the pH, EC, and bulk density of the soil. This review focused on bridging the knowledge gap with understanding how microplastics prevent nutrient uptake and nutrient use efficiency in plants. This understanding is essential for assessing the broader ecological impacts of plastic contamination and for developing effective mitigation strategies. Further research is needed on microorganisms capable of degrading plastics, as well as on developing analytical methods for detecting plastics in soil and plant tissues. Also, further research on how to replace plastic mulching and still provide the same benefits as plastic mulch is needed.

Soil Systems doi: 10.3390/soilsystems10010001

Authors: Zuhair Masri Francis Turkelboom Chi-Hua Huang Thomas E. Schumacher Venkataramani Govindan

Steep olive orchards in northwest Syria are experiencing severe land degradation as a result of unsustainable uphill–downhill tillage, which accelerates erosion and reduces productivity. To address this problem, three tillage systems, no-till natural vegetation strips (NVSs), contour tillage, and uphill–downhill tillage, were evaluated at two research sites, Yakhour and Tel-Hadya, NW Syria. The adoption of no-till NVSs significantly increased soil organic matter (SOM) at both sites, outperforming uphill–downhill tillage. While contour tillage resulted in lower SOM levels than NVSs, it still performed better than the conventional uphill–downhill practice. Contour soil flux (CSF) was lower in Yakhour, where mule-drawn tillage on steep slopes (31–35%) was practiced, compared to higher CSF values in Tel-Hadya, where tractor tillage was applied on gentler slopes (11–13%), which highlights the influence of slope steepness on soil fluxes. Over four years, net soil flux (NSF) indicated greater soil loss under tractor tillage, confirming that mule-drawn tillage is less disruptive. Olive trees with no-till NVSs benefited from protected root systems, improved soil structure through SOM accumulation, reduced erosion risk, and improved surface runoff buffering, which resulted in increased water infiltration and soil water retention. This study was carried out using a participatory technology development (PTD) framework, which guided the entire research process, from diagnosing problems to co-designing, field testing, and refining soil conservation practices. In Yakhour, farmers actively identified the challenges of degradation. They collaboratively chose no-till natural vegetation strips (NVSs) and contour tillage as key interventions, valuing NVSs for their ability to conserve moisture, suppress weeds and pests, and increase olive productivity. The farmer–scientist co-learning network positioned PTD not only as an outreach tool but also as a core research method, enabling locally relevant and scalable strategies to restore soil functions and combat land degradation in northwest Syria’s hilly olive orchards.

Soil Systems doi: 10.3390/soilsystems9040138

Authors: Yulian Farkhodov Natalia Danchenko Igor Danilin Irina Grigoreva Natalia Matveeva Aliia Ziganshina Nikita Ermolaev Sergey Yudin Ivan Nadutkin Sergey Kambulov Vladimir Kholodov

Soil conservation technologies are widely studied for their effects on soil organic carbon (SOC) preservation, yet their impact on the composition of soil organic matter (SOM) remains underinvestigated. This study evaluated the effects of two non-inversion tillage systems, MP and NT, on agro-physical and chemical properties and SOM composition (including water-extractable matter) in Haplic Chernozem Pachic. After 12 years, non-inversion tillage showed no significant differences in SOC, WEOC, and soil structure condition compared to MP. Only NT treatment distinctly enhanced the coefficient of soil structuring (Kstr) and mean diameter of water-stable aggregates (MWDWSA), by 1.5 and 2 times, respectively. Differences in SOM composition were clearly pronounced between treatments in the 0–10 cm layer. Non-inversion tillage favored microbial-derived stable SOM, whereas NT enriched SOM with fresh plant material. Our findings revealed that non-inversion tillage shifts the composition of SOM toward recalcitrant components even more than MP due to limited fresh OM input and enhanced mineralization of unprotected SOM during tillage. This poses carbon loss risks. Periodic moldboard plowing may be a way to improve carbon retention in non-inversion tillage, as it allows plant residues to be incorporated into the soil profile and replenish organic matter.

Soil Systems doi: 10.3390/soilsystems9040137

Authors: Pavlos Tziourrou Evangelia E. Golia

The increasing presence of microplastics (MPs) in terrestrial ecosystems, particularly when combined with organic pollutants and heavy metals, presents a considerable environmental challenge. This review examines the intricate interactions between MPs, co-contaminants (both organic and inorganic), and plants involved in phytoremediation processes. A literature search was performed across the databases Scopus, ScienceDirect, and Google Scholar, covering the timeframe from 2015 to 2025. The studies selected specifically addressed the synergistic and antagonistic effects of microplastics in conjunction with heavy metals or organic pollutants (such as PAHs and pesticides) within plant–soil systems. The findings reveal that MPs influence pollutant mobility, bioavailability, and toxicity through adsorption and desorption mechanisms, leading to varied implications for plant growth, microbial communities, and contaminant uptake. Depending on the physicochemical characteristics of MPs and co-pollutants, the effects can range from increased phytotoxicity to diminished contaminant accumulation in plants. Additionally, physiological and molecular disruptions, including oxidative stress, hormonal imbalances, and impaired enzymatic activity, were frequently noted in co-contamination scenarios. Recent developments, such as the creation of genetically modified hyperaccumulator plants and the use of nanotechnology and microbial consortia, demonstrate potential to enhance phytoremediation efficiency in complex polluted soils. This review underscores the pressing need for integrated, multidisciplinary strategies to overcome the limitations of existing phytoremediation methods in co-contaminated environments. Future research should focus on standardized methodologies, a mechanistic understanding, and the safe implementation of emerging biotechnologies for sustainable soil remediation.

Soil Systems doi: 10.3390/soilsystems9040136

Authors: Afia Sultana Qingyue Wang Miho Suzuki Christian Ebere Enyoh Md. Sohel Rana Yugo Isobe Weiqian Wang

Heavy metal contamination in agricultural soils poses serious threats to food safety, ecosystem integrity, and public health. This study investigates the concentrations, ecological risks, and human health impacts of nine heavy metals Cr, Mn, Co, Ni, Cu, Zn, Pb, As, and V in homestead agricultural soils collected from two depths, surface (0–20 cm) and subsurface (21–50 cm), across industrial and non-industrial regions of Bangladesh, using inductively coupled plasma mass spectrometry (ICP-MS). Results revealed that surface soils from industrial areas exhibited the highest metal concentrations in order of Mn > Zn > Cr > Pb > V > Ni > Cu > As > Co. However, maximum As levels were detected in non-industrial areas, suggesting combined influences of local geology, intensive pesticide application, and prolonged irrigation with As-contaminated groundwater. Elevated concentrations in surface soils indicate recent contamination with limited downward migration. Multivariate statistical analyses indicated that industrial and urban activities are the major sources of contamination, whereas Mn remains primarily geogenic, controlled by natural soil forming processes. Contamination factor (CF) and pollution load index (PLI) analyses identified Pb and As as the principal pollutants, with hotspots in Nairadi, Majhipara (Savar), Gazipur sadar, and Chorkhai (Mymensingh). Ecological risk (ER) assessment highlighted As and Pb as the dominant environmental stressors, though overall risk remained low. Human health risk analysis showed that ingestion is the primary exposure pathway, with children being more susceptible than adults. Although the hazard index (HI) values were within the acceptable safety limits, the estimated carcinogenic risks for As and Cr exceeded the USEPA thresholds, indicating potential long term health concerns. Therefore, the cumulative carcinogenic risk (CCR) results demonstrate that As is the primary driver of lifetime carcinogenic risk in homestead soils, followed by Cr, while contributions from other metals are minimal. These findings emphasize the urgent need for continuous monitoring, improved industrial waste management, and targeted mitigation strategies to ensure safe food production, a cleaner environment, and better public health.

Soil Systems doi: 10.3390/soilsystems9040135

Authors: María Teresa Salazar-Ramírez Rubén Palacio-Rodríguez Jesús Josafath Quezada-Rivera Tania Elizabeth Velásquez-Chávez Gisela Muro-Pérez Hortencia Ivone Ortega-Reyes Jorge Arnaldo Orozco-Vidal Antonio Gerardo Yescas-Coronado Gerardo Antonio Verástegui-Hernández Jorge Sáenz-Mata

Soil salinity imposes a critical constraint on plant productivity, highlighting the need for sustainable biological strategies to enhance stress tolerance. This study assessed the effects of volatile organic compounds (VOCs) emitted by ten plant-growth-promoting rhizobacteria (PGPR) isolated from the rhizosphere of Euphorbia antisyphilitica on the growth of Arabidopsis thaliana seedlings exposed to 0, 50, and 100 mM NaCl. A divided Petri dish system was used to quantify biomass, root architecture, proline accumulation, sodium content, and chlorophyll concentration. Three strains—Siccibacter colletis CASEcto12, Enterobacter quasihormaechei NFbEcto18, and Bacillus wiedmannii NFbEndo12—significantly enhanced seedling development under saline and non-saline conditions (p ≤ 0.05). At 50 mM NaCl, S. colletis CASEcto12 increased primary root length from 40.25 to 64.81 mm and fresh weight from 45.05 to 133.33 mg, while E. quasihormaechei NFbEcto18 elevated lateral root number from 10 to 24, compared to the uninoculated control. Under 100 mM NaCl, E. quasihormaechei NFbEcto18 increased proline accumulation (0.564–1.378 mmol g−1 FW) and reduced Na+ content (0.146–0.084 mmol g−1 FW), indicating improved osmotic and ionic regulation. VOC profiling using SPME-GC-MS revealed aldehydes, ketones, and alcohols as predominant classes. Overall, these findings demonstrate the potential of candelilla-associated PGPR VOCs as promising biostimulants for enhancing plant performance in salt-affected soils.

Soil Systems doi: 10.3390/soilsystems9040134

Authors: Giambattista Maria Altieri Josefina Garrido Salustiano Mato Benedicto Soto Vito Santarcangelo Giuseppe Bari Eustachio Tarasco

Soil biodiversity is crucial for maintaining biological soil resilience, understood as a temporal property and as the ability of soils to uphold or recover their ecological functions under stress thanks to the diversity and complementarity of their biological communities. To evaluate this property, we developed the Biological Soil Resilience Index (BSR), conceived as an evolution of the QBS-ar approach by integrating additional key bioindicators—entomopathogenic nematodes, entomopathogenic fungi, and earthworms—together with microarthropod eco-morphological adaptation scores. This multi-taxon framework provides a more comprehensive assessment of soil biological conditions than single-group indices and is specifically designed to be applied repeatedly over time to detect resilience trajectories. The Biodiversity Soil Resilience (BSR) Index was applied across nine sites subject to low, medium, and high anthropogenic disturbance, spanning urban, industrial, and airport environments. Results revealed not a resilience gradient but a clear disturbance gradient: low-impact sites achieved the highest BSR values (52–59), reflecting diverse and functionally complementary assemblages; medium-impact sites maintained moderate BSR value (27–42), but displayed imbalances among faunal groups; and high-impact sites showed the lowest values, including a critically low score at C_HI (17.86), where entomopathogens were absent and earthworm populations reduced. Entomopathogenic organisms proved particularly sensitive, disappearing entirely under severe disturbance. The BSR was sensitive to environmental gradients and effective in distinguishing ecologically meaningful differences among soil communities. Because it can be repeatedly applied over time, BSR provides the basis for monitoring long-term resilience dynamics, detecting early warning signals, and support timely mitigation or restoration measures. Overall, the study highlights the pivotal role of biodiversity in sustaining soil resilience and supports the BSR Index as a simple yet integrative tool for soil health assessment and for future resilience monitoring in disturbed landscapes.

Soil Systems doi: 10.3390/soilsystems9040133

Authors: Stylianos Gerontidis Konstantinos X. Soulis Alexandros Stavropoulos Evangelos Nikitakis Dionissios P. Kalivas Orestis Kairis Dimitrios Kopanelis Xenofon K. Soulis Stergia Palli-Gravani

Soil maps are essential for managing Earth’s resources, but the accuracy of widely used global and pan-European digital soil maps in heterogeneous landscapes remains a critical concern. This study provides a comprehensive evaluation of two prominent datasets, ISRIC-SoilGrids and the European Soil Data Centre (ESDAC), by comparing their soil texture predictions against the detailed Greek National Soil Map, which is based on over 10,000 field samples. The results from statistical and spatial analyses reveal significant discrepancies and weak correlations, with a very low overall accuracy for soil texture class prediction (19–21%) and high Root Mean Square Error (RMSE) values ranging from 13% to 19%. The global models failed to capture local variability, showing very low explanatory power (R2 < 0.2) and systematically underrepresenting soils with extreme textures. Furthermore, these prediction errors are not entirely random but are significantly clustered in hot spots linked to distinct parent materials and geomorphological features. Our findings demonstrate that while invaluable for large-scale assessments, the direct application of global soil databases for regional policy or precision agriculture in a geologically complex country like Greece is subject to considerable uncertainty, highlighting the critical need for local calibration and the integration of national datasets to improve the reliability of soil information.

Soil Systems doi: 10.3390/soilsystems9040132

Authors: Fatima Zohra Batoul Touati Abdelbasset Boumadda Fouzi Benbrahim Abderraouf Benslama Jose Navarro-Pedreño

In arid regions, the soil degradation from salinization, low organic matter content, and compaction severely limits agricultural productivity. Leguminous perennials such as alfalfa (Medicago sativa L.) have the potential to restore soil quality, but their long-term effects remain underexplored in North African drylands. This study aimed to evaluate the impacts of long-term (7–8 years) alfalfa cultivation on soil fertility and salinity in the Ziban region of Algeria. Ninety topsoil samples (0–30 cm) from cultivated and adjacent uncultivated plots were collected and analyzed, determining organic matter (OM), soil organic carbon (SOC), soil nitrogen stock (SNS), electrical conductivity (EC), sodium adsorption ratio (SAR), pH, major cations (Ca2+, Mg2+, Na+), sulfate (SO42−), bulk density (BD), and texture. Compared with uncultivated soils, alfalfa cultivation increased OM by 82.26%, SOC by 78.38%, and SNS by 102.99%, while reducing EC by 40.36%, SAR by 28.94% and BD by 6.16% (p < 0.05), indicating significant improvements in fertility, structure and reductions in sodicity. PCA revealed distinct gradients separating fertility–salinity parameters from compaction–sodicity in cultivated and uncultivated soils. These results confirm that alfalfa systems enhance nutrient cycling, reduce salt stress, and improve structural stability in arid agroecosystems through reduced bulk density and increased organic matter in arid agroecosystems. Integrating alfalfa into land management strategies could promote sustainable restoration of degraded soils in drylands. Further research should optimize irrigation and organic inputs to maximize these benefits under climate-stress conditions.

Soil Systems doi: 10.3390/soilsystems9040131

Authors: Gustavo R. Alonso Javier Casalí Miguel Ángel Campo-Bescós Jorge Díaz

Accelerated water erosion is a major soil degradation process that affects soil and water quality. In Cuba, specifically, more than 40% of agricultural lands are affected by severe erosion problems. Estimating accurate erodibility values is a crucial step for the calibration and proper application of erosion models. Several equations have been developed to estimate erodibility from soil properties; however, these are often soil- or site-specific, limiting their application. This study aims to (1) identify soil properties governing the erodibility of tropical soils from western Cuba, (2) find suitable regression models to estimate erodibility from these properties, and (3) test widely applied erodibility equations. To achieve these goals, rainfall simulation experiments were conducted on runoff plots, and erosion-related physical, chemical, and mechanical soil properties were determined for 19 different soils. The main results indicated that good correlations between erodibility and certain soil properties were achieved after clustering soils based on their cation exchange capacity (CEC) values and clay content. Soils characterized by more than 30% of clay and 40 cmol+ kg−1 of CEC were excluded from the main analysis. Generally, clay content controls the erodibility of these tropical soils, exhibiting an inverse relationship. However, in the excluded soils, the clay fraction showed a positive relationship with erodibility. Soil water retention at the lowest matric potentials demonstrated the strongest correlation with soil erodibility, as this variable encompasses compound information related to clay, mineralogy, and organic matter. A new regression model to estimate erodibility based solely on the volumetric water content at 1500 kPa is presented. The optimal fitted logarithmic model accounts for 64% of the predictand variability in the studied soils. When testing known erodibility models, the nomograph was found to best mimic the erodibility trend of these soils, although it exhibited marked uncertainty and underestimation biases.

Soil Systems doi: 10.3390/soilsystems9040130

Authors: Ioana Monica Sur Vasile Calin Prodan Valer Micle Mircea Nasui Andreea Hegyi Veronica Simona Pop Liviu Iacob Scurtu

Soil contamination by heavy metals poses serious risks to human health and the environment. This study investigates the removal of Pb, Cu, Zn, Cd, and Cr from heavily contaminated slightly acidic to neutral soil (pH 6.5) using organic washing agents (humus, malic acid, and gluconic acid) at concentrations of 1% and 3% and a solid-to-liquid ratio (S/L) of 1:8. The results reveal that metal mobilization depends strongly on the type and concentration of the extraction agent, the target metal, and soil properties. Cd was highly mobilized, reaching more than 90% with 3% gluconic acid, whereas Cu and Pb remained largely immobile (<3%), and Cr (40–78%) and Zn (8–26%) showed intermediate extraction. This study establishes a clear hierarchy of metal mobility (Cd > Cr > Zn > Cu ≈ Pb) and demonstrates that metal speciation, soil chemistry, pH, and S/L ratio critically govern extraction efficiency. These findings provide mechanistic insights into metal–ligand interactions and practical guidance for optimizing soil remediation strategies using organic acids.

Soil Systems doi: 10.3390/soilsystems9040129

Authors: Laura Canonica Grazia Cecchi Sebastiano Comba Simone Di Piazza Fedra Gianoglio Pietro Marescotti Samuele Voyron Mirca Zotti

Serpentinite soils represent extreme environments characterized by deficiencies in essential nutrients (Ca, K, P, N), an unfavorable Ca/Mg ratio, low water retention, and elevated concentrations of several geogenic potentially toxic elements (PTEs). In particular, the study site, located in Sassello (Liguria, Italy) within the serpentinites of the High-Pressure–Low-Temperature (HP–LT) metaophiolites of the Voltri Massif, exhibited concentrations of chromium, nickel and cobalt exceeding Italian legal thresholds by up to one order of magnitude. This study aimed to assess fungal diversity and to isolate culturable strains naturally adapted to these challenging conditions for potential use in bioremediation. Culturable-dependent analyses allowed for the isolation of viable fungal strains, with Penicillium (52%), Umbelopsis (17.9%), and Aspergillus (11.6%) found as dominant genera. Additionally, metabarcoding analyses provided a broader view of fungal community composition, revealing the presence and distribution of both culturable and non-culturable taxa. The combined approach highlighted the richness of the serpentinite soil mycobiota and its role as a reservoir of PTE-resistant organisms. These findings offer new insights into the ecology of metal-rich soils and identify promising candidates for sustainable remediation strategies in PTE-contaminated environments.

Soil Systems doi: 10.3390/soilsystems9040128

Authors: Gaia Mascetti Roberto Comolli Francesca Pittino Isabella Gandolfi Chiara Ferré

De-sealing, or depaving, is increasingly adopted to restore soil permeability and support green infrastructure, yet its potential to recover soil functions remains insufficiently understood. This study reports one year of soil monitoring following the de-sealing of a brownfield site in Milan (Italy). It compares the evolution of pedoclimatic parameters in sealed and de-sealed soils and assesses the suitability of recycled aggregates (RAs) from demolition waste as a soil-forming material. Buried sensors continuously recorded pedoclimatic parameters, temperature, water content, and oxygen concentration, while periodic sampling was carried out to analyse soil chemical properties, bacterial community composition, and the quality of percolation water (heavy metal content). De-sealing immediately improved pedoclimatic conditions, enhancing soil aeration, water regulation, and heat exchange capacity. No significant variation was detected in soil chemical properties, apart from pH fluctuations linked to the leaching of alkaline ions from concrete-based RAs. The presence of RAs caused no adverse effects on either soil or percolation water. Bacterial community composition was strongly associated with soil organic carbon, C:N ratio, and soil water content, without showing clear temporal trends. Overall, the study demonstrates that de-sealing rapidly triggers soil functional recovery and that, when properly characterised for composition and contamination risk, RAs pose no evident threat to the surrounding environment.

Soil Systems doi: 10.3390/soilsystems9040127

Authors: Anna N. Berlina Anatoly V. Zherdev Boris B. Dzantiev

Acetochlor is a selective herbicide affecting weeds of cereal plants. Its analysis in soils allows accessing their suitability for crops and risks of contamination of agricultural products. The aim of this study was to develop a microplate enzyme immunoassay for the determination of acetochlor in soil extracts. For the development, rabbit antibodies specific to acetochlor were obtained by immunization with a conjugate of carrier protein with a derivative of acetochlor with mercaptopropionic acid. Another derivative with mercaptosuccinic acid was applied for immobilization on the solid phase. In the study, organic extracts have been obtained from soil varying solvents and their ratios, and using QuEChERS protocol. The extracts have been tested to estimate residual influences of the sample matrix. Optimal conditions for the immunoassay were selected, appropriate sample preparation techniques, and the composition of the medium for competitive immune interaction. The most effective approach involved dichloromethane extraction, followed by careful evaporation and subsequent reconstitution of the dry residue in a 10 mM phosphate-buffer solution supplemented with 0.1% gelatin. The resulting analytical system exhibited a detection limit of 59.4 ng/mL for acetochlor, with a working range spanning from 112 to 965 ng/mL. Taking into account the soil sample preparation, the LOD was estimated as 0.3 µg/g with the working range from 0.66 to 5.7 µg/g of soil. Analysis of prepared extracts from gray forest soil demonstrated a revealing of acetochlor between 74% and 124%.

Soil Systems doi: 10.3390/soilsystems9040126

Authors: Zhuohuai Guan Tao Jiang Haitong Li Min Zhang Mei Jin Dong Jiang

The risk of soil compaction by agricultural machinery threatens the structure and productivity of tilled soils. However, a quantitative understanding of how specific compaction loads alter the three-dimensional (3D) macropore architecture of tilled soil is still limited. This study employed X-ray computed tomography (CT) to quantitatively characterize the evolution of the 3D macropore network in clay soil under a series of controlled compaction pressures (0, 30, 60, 90, and 120 kPa). Our results revealed a non-monotonic response of macropore number to compaction, which initially increased due to the fragmentation of large pores before declining, peaking at 90 kPa. Most critically, we identified 90 kPa as a critical threshold, beyond which macroporosity and the volume of elongated beneficial pores underwent drastic reductions of 64.8% and 46.6%, respectively. Compaction significantly reduced pore connectivity and surface area, with larger macropores (>1000 μm) proving most vulnerable. The study establishes a quantitative link between applied pressure and specific pore-scale damage, providing a scientific basis for designing agricultural machinery with ground pressures below this critical threshold to preserve soil structure and function after tillage.

Soil Systems doi: 10.3390/soilsystems9040125

Authors: Francisco González-Breijo Antonio Fidel Santos-Hernández Alejandra Sahagún-García Luis Antonio Hernández-Pedraza Juan Fernando Gallardo-Lancho Joel Pérez-Nieto

Sustainable soil management is crucial for balancing agricultural productivity and soil health in Mollisols under long-term tillage systems. This study evaluated the effects of no-tillage (NT), minimum conservation tillage (MCT), and conventional tillage (CT) on soil properties and maize yield in an irrigated Mollisol in Chapingo, Mexico, over 9, 22, and 25 yr, using a Latin square design with three replications. MCT significantly enhanced soil organic carbon (SOC), total nitrogen (TN), available phosphorus (AP), and exchangeable potassium (EK) compared to NT and CT, achieving the highest maize grain yield (7.21 t ha−1). NT exhibited the greatest SOC and EK in the surface layer. Physical properties, such as bulk density and porosity, remained stable across systems, reflecting Mollisol resilience. Although MCT optimized fertility and productivity, nutrient declines from 2021 to 2024 highlight the need for adaptive management strategies to sustain long-term productivity, supporting global soil conservation and sustainable agriculture goals.

Soil Systems doi: 10.3390/soilsystems9040124

Authors: Gustavo Vieira Veloso Danilo César de Mello Heitor Paiva Palma Murilo Ferre Mello Lucas Vieira Silva Elpídio Inácio Fernandes-Filho Márcio Rocha Francelino Tiago Osório Ferreira José Cola Zanuncio Davi Feital Gjorup Roney Berti de Oliveira Marcos Rafael Nanni Renan Falcioni José A. M. Demattê

Understanding soil variability supports improved land use and soil security. This study aimed to generate uniform geophysical classes by integrating data from three proximal geophysical sensors with synthetic soil and satellite images using machine learning, proposing a soil survey protocol. Geophysical data—natural gamma-ray emissions (eU, eTh, K40), magnetic susceptibility (κ), and apparent electrical conductivity (ECa)—were collected in Piracicaba, Brazil, and clustered into homogeneous geophysical-isoparameter classes. These classes were modeled alongside Synthetic Soil Images (SYSIs), Sentinel-2 (0.45–2.29 μm), Landsat (0.43–12.51 μm) imagery, and morphometric variables. Empirical validation compared the resulting geophysical-isoparameter map with conventional pedological and lithological maps. The Support Vector Machine (SVM) algorithm exhibited the best classification performance. Results demonstrated that geophysical sensors quantitatively and qualitatively capture soil attributes linked to formation processes and types. The geophysical-isoparameter map correlated well with pedological and lithological patterns. The proposed protocol offers soil scientists a practical tool to delineate soil and lithological units using combined sensor data. Promoting collaboration among pedologists, pedometric mappers, and remote sensing experts, this approach presents a novel framework to enhance soil survey accuracy and efficiency.

Soil Systems doi: 10.3390/soilsystems9040123

Authors: Jun Hong Hang Zhang Manli Xiao Xiaoli Duan Minmin Zhang Li Yang Hao Fan Bo Liu

Current research predominantly focuses on the microbial-driven processes of soil organic nitrogen mineralization, often overlooking the significant contributions of abiotic pathways mediated by reactive minerals. While manganese oxides are known to promote the abiotic mineralization of organic nitrogen, the influence of key environmental factors on this process remains poorly understood. This study established a simulated system to investigate the effects of dissolved oxygen and pH on the γ-MnO2-mediated abiotic nitrogen mineralization of peptone. The results showed that under an air atmosphere at pH 5.0–8.0, the rate of nitrogen mineralization from peptone catalyzed by γ-MnO2 initially increased and then subsequently decreased. Dissolved oxygen was identified as a major electron acceptor in the peptone nitrogen mineralization process, playing a critical role in its rate and extent. Direct oxidation by Mn (IV) and Mn (III) within γ-MnO2 accounted for 72.5% of the peptone nitrogen mineralization, and reactive oxygen species generated on the mineral surface accounted for 27.5% through a catalytic oxidation mechanism. This study provides a preliminary analysis of how key environmental factors influence the abiotic mineralization of protein-derived organic nitrogen, which is expected to deepen the understanding of soil organic nitrogen mineralization mechanisms, enrich the knowledge of nitrogen cycling in agricultural ecosystems, and provide a theoretical basis for efficient nitrogen management in farmland.

Soil Systems doi: 10.3390/soilsystems9040122

Authors: Jarosław Zawadzki

Variograms are a cornerstone of spatial analysis in geostatistics, traditionally applied to real-valued variables under the intrinsic hypothesis. Many soil properties, particularly when integrating magnetic and geochemical measurements, can be expressed as complex-valued variables that capture both magnitude and phase information. In the case of magnetic susceptibility, the imaginary component reflects energy losses associated with viscous magnetization, which in soils can indicate the presence of pedogenic ferrimagnetic minerals, while its relative increase may also reveal anthropogenic magnetite contamination. This study examines the formulation and application of variograms for such complex-valued variables in the context of soil research. Two complementary definitions are considered: an intrinsic-based approach, which directly estimates the variogram from increments and is applicable under the intrinsic hypothesis, and a covariance-based approach, which requires stronger second-order stationarity. Simulated complex-valued soil property data with controlled spatial structures were used to compare the behaviour of these formulations with their real-valued counterparts. The findings indicate that complex-valued variograms preserve additional spatial information, particularly related to local phase shifts, while maintaining compatibility with conventional variographic modelling.

Soil Systems doi: 10.3390/soilsystems9040121

Authors: Amir Ali Khoddamzadeh Bárbara Nogueira Souza Costa Milagros Ninoska Munoz-Salas

Optimizing fertilizer management is essential for reducing salinity-related risks and improving nutrient efficiency in ornamental plant production. Fertilization enhances plant performance; however, excessive nutrient inputs can disrupt substrate chemistry, elevate salinity, and promote nitrogen leaching—particularly in containerized systems with limited rooting volume. This study evaluated the growth, physiological performance, and soil–plant nutrient dynamics of Sabal palmetto (cabbage palm) cultivated under six fertilization regimes over 180 days in a subtropical shade-house environment. Treatments ranged from a single baseline application of 15 g per plant (T0) to a cumulative 75 g (T5) using granular slow-release fertilizer. Morphological traits (plant height: 26–70 cm; leaf number: 4–18) and physiological indices (atLEAF+: 34.3–66.4; NDVI: 0.26–0.77) were monitored every 30 days. Substrate nitrogen and carbon concentrations increased from 0.57% and 41.78% at baseline to 1.24% and 42.94% at 180 days, while foliar nitrogen ranged from 1.46% to 2.57%. Fertilization significantly influenced all parameters (p < 0.05). Higher fertilization levels elevated electrical conductivity, salinity, and nitrogen leaching, with principal component analysis revealing strong positive associations among total nitrogen, electrical conductivity, and salinity. Moderate fertilization (T2 = 45 g) maintained favorable substrate chemistry, high foliar nitrogen, and balanced canopy growth with minimal nutrient losses. Sensor-based chlorophyll indices (atLEAF+ and NDVI) correlated strongly (r = 0.71, p < 0.001), confirming their reliability as non-destructive diagnostics for nitrogen management. These findings demonstrate that integrating optical monitoring with adaptive fertilization mitigates substrate salinization, sustains ornamental quality, and promotes the sustainable cultivation of Sabal palmetto in urban horticultural systems.

Soil Systems doi: 10.3390/soilsystems9040120

Authors: Antonio Martínez Cortizas Mohamed Traoré Olalla López-Costas Géraldine Sarret Stéphane Guédron

Peatlands are natural reservoirs of organobromine compounds. Important advances have been made in unraveling the mechanisms involved in bromine (Br) retention in the peat but, to our knowledge, the temporal and spatial variation of the peat organic matter (OM) bromination has not been fully researched. Here, we present the study of 12 short cores (c. 30 cm, c. 150–200 years of peat accumulation) sampled from a small (c. 1 ha) area of an oceanic blanket peatland from northwestern Spain. We combine Br concentrations, spectroscopic analysis (FTIR–ATR), and structural equation statistical modelling (SEM). Our results show that Br is significantly correlated to proxies of peat aerobic decomposition, with concentrations increasing with depth in all cores (×2–10 times). Strong spatial heterogeneity was observed, with some cores showing much higher Br maximum concentrations and larger increases with depth. SEM modelling indicated that various OM functionalities contribute to Br accumulation and that their effects change with depth/age, with aromatics becoming dominant after 20–90 years. Thus, changes in organic matter molecular composition, linked to early peat diagenesis, and the geochemical conditions governing it exerted a strong control on Br accumulation in the studied peatland. Bromine wet deposition was not found to be a limiting factor.

Soil Systems doi: 10.3390/soilsystems9040119

Authors: Anastasia Brikmans Olga Nesterova Andrei Egorin Mariia Bovsun Viktoriia Semal Nikolay Sakara

Heavy-textured soils in monsoon-affected regions face challenges related to waterlogging and structural degradation, yet the long-term efficacy of biochar as a physical soil amendment under such conditions remains inadequately understood. This two-year field study (2018–2019) therefore evaluated the transient impacts of birch-derived biochar (360–380 °C pyrolysis; 0, 1, 3 kg/m2), subsurface drainage systems, and fertilizer regimes on key physical properties of Endoargic Anthrosols (clay loam) in coastal Primorsky Krai, Russia. Granulometric composition remained stable (silt loam: sand 42–48%, silt 38–44%, clay 12–16%), though drainage significantly increased the silt fraction by >7.5% (p < 0.05). Biochar induced short-term reductions in bulk density (ρb; max −12% at 3 kg/m2, 2018) and aggregate density (ρa; max −9.3%, 2018), but these effects dissipated by 2019 due to tillage redistribution and monsoonal fragmentation, as verified by SEM. Total porosity fluctuated seasonally (0.50–0.65 cm3/cm3), peaking post-tillage but declining under monsoon saturation, with no significant sustained biochar contribution. Crucially, intra-aggregate pore architecture (2–50 nm) resisted amendment-induced changes; N2 adsorption showed treatment-invariant mesopore dominance (65–75% volume; mean pore diameter 17–21 nm), attributable to biochar’s physical exclusion (>1 µm particles from sub-0.5 µm pores) and inert fragmentation. Drainage dominated structural dynamics, modulating pore volume seasonally (−15% in 2018; +18% in 2019), while organic fertilizer enhanced porosity through polysaccharide-stabilized microaggregation (+22%, 2019). We conclude that biochar’s physical benefits in clay loams under monsoon climates are transient and dose-dependent, operating primarily through inter-aggregate macroporosity rather than intra-aggregate modification, necessitating reapplication for sustained improvements.

Soil Systems doi: 10.3390/soilsystems9040118

Authors: Giovanni Marchese Juan E. Herranz-Luque Sohail Anwar Valentina Vaglia Chiara Toffanin Ana Moreno-Delafuente Blanca Sastre María José Marqués Pérez

In Mediterranean semi-arid regions, rainfed olive groves are increasingly being abandoned due to drought, low profitability, and rural depopulation. The long-term impact of abandonment on soil conditions is debated, as it may promote vegetation recovery or lead to degradation. In contrast, some farmers are adopting low-disturbance management practices that allow spontaneous vegetation to establish. These contrasting scenarios offer valuable opportunities for comparison. This study aims to develop a framework to assess the impact of different management regimes on soil health and to investigate (1) the impact of spontaneous vegetation cover (SVC) and tillage regimes on soil organic carbon (SOC), and (2) the long-term ecological dynamics of abandoned groves, through a combination of field surveys, remote sensing, and object detection. SOC was assessed using both ground-based and remote sensing-derived indicators. Vegetation cover was quantified via a grid point intercept method. Field data were integrated with a land-use monitoring framework that includes abandonment assessment through historical orthophotos and a deep learning model (YOLOv12) to detect active and abandoned olive groves. Results show that abandoned zones are richer in SOC than active ones. In particular, the active groves with SVC exhibit a mean SOC of 1%, which is higher than that of tilled groves, where SOC is 0.45%, with no apparent moisture loss. Abandoned groves can be reliably identified from aerial imagery, achieving a recall of 0.833 for abandoned patches. Our results demonstrate the potential of YOLOv12 as an innovative and accessible tool for detecting zones undergoing ecological regeneration or degradation. The study underscores the ecological and agronomic potential of spontaneous vegetation in olive agroecosystems.

Soil Systems doi: 10.3390/soilsystems9040117

Authors: Shohnazar Hazratqulov Georgina von Ahlefeldt Rui Liu Holger Bessler Hernán Almuina-Villar Alba Dieguez-Alonso Christof Engels

In the original article [...]

Soil Systems doi: 10.3390/soilsystems9040116

Authors: Roderic Gilles Claret Diabankana Ernest Nailevich Komissarov Daniel Mawuena Afordoanyi Bakhtiyar Islamov Artemiy Yurievich Sukhanov Elena Shulga Maria Nikolaevna Filimonova Keremli Saparmyradov Natalia V. Trachtmann Shamil Z. Validov

Microorganisms are fundamental drivers of soil productivity, mediating nutrient cycling and pathogen suppression. In this study, we evaluated changes in the fungal community in the soil of barley (Hordeum vulgare L.) in a field experiment involving the application of a consortium of Paenibacillus pabuli, Priestia megaterium, Pseudomonas koreensis, and Pseudomonas orientalis. Seed pretreatment and seed pretreatment followed by rhizosphere drenching at different growth stages were implemented. Regarding fungal communities in bulk soil, the rhizospheres of untreated and treated plants were characterized based on full-length ribosomal RNA gene (18S-5.8S-28S) metabarcoding sequencing. Despite the compositional shifts, no statistical differences were observed among the alpha diversity metrics. Seed treatment resulted in long-term, targeted suppression of Fusarium graminearum, Fusarium fujikuroi, Fusarium musae, and Fusarium verticillioides from the booting through flowering and dough development stages, outperforming seed pretreatment followed by rhizosphere drenching. A low-modularity network was observed in the rhizosphere of untreated plants. Seed treatment fostered a highly interconnected and uniform network with low hub-betweenness scores. Rhizosphere drenching of pretreated seeds shifted the network topology toward higher hub-betweenness scores, reducing their connectivity by up to 10% in the rhizosphere and bulk soil. These findings provide a framework for optimizing the soil ecosystem for sustainable agriculture.

Soil Systems doi: 10.3390/soilsystems9040115

Authors: Daniel F. Petticord Benjamin T. Uveges Elizabeth H. Boughton Brian D. Strahm Jed P. Sparks

Phosphorus (P) is essential to life yet constrained by finite reserves, heterogeneous distribution, and strong chemical binding to soil minerals. Pedogenesis progressively alters the availability of P: in ‘young’ soils, P associated with Ca and Mg is relatively labile, while in ‘old’ soils, acidification and leaching deplete base cations, shifting P into organic matter and recalcitrant Al- and Fe-bound pools. Podzolized soils (Spodosols) provide a unique lens for studying this transition because podzolization vertically segregates these dynamics into distinct horizons. Organic cycling dominates the surface horizon, while downward translocation of Al, Fe, and humus creates a spodic horizon that immobilizes P through sorption and co-precipitation in amorphous organometal complexes. This spatial separation establishes two contrasting P pools—biologically dynamic surface P and mineral-stabilized deep P—that may be variably accessible to plants and microbes depending on depth, chemistry, and hydrology. We synthesize mechanisms of spodic P retention and liberation, including redox oscillations, ligand exchange, root exudation, and physical disturbance, and contrast these with strictly mineral-driven or biologically dominated systems. We further propose that podzols serve as natural experimental models for ecosystem aging, allowing researchers to explore how P cycling reorganizes as soils develop, how vertical stratification structures biotic strategies for nutrient acquisition, and how deep legacy P pools may be remobilized under environmental change. By framing podzols as a spatial analogue of long-term weathering, this paper identifies them as critical systems for advancing our understanding of nutrient limitation, biogeochemical cycling, and sustainable management of P in diverse ecosystems.

Soil Systems doi: 10.3390/soilsystems9040114

Authors: Abilzhan Khussainov Anara Sarsenova Anar Ayapbergenova Gulmira Kyzdarbekova Ekaterina Bazilevskaya

Phosphorus deficiency and declining organic matter limit crop productivity in Northern Kazakhstan’s chernozem soils. This study evaluates whether the combined application of phosphorus fertilizer and an ash-carbon amendment from industrial by-products can improve soil fertility and barley yield. In a three-year field experiment (2018–2020), four P rates (1/10, 1/5, 1/2, and the full recommended dose, Prec) were tested with 100 kg ha−1 of ash–carbon product (“Agrobionov”). Across growth stages, we measured cellulolytic microbial activity, water-stable soil aggregates (%WSA), and grain yield. Relative to the control, P + ash–carbon increased microbial activity by up to 57.6% and %WSA by up to 76%. The highest yield (1.32 t ha−1) occurred with Agrobionov + ½ Prec, a 51.7% increase over the control. These results indicate that pairing moderate P rates with an ash–carbon amendment enhances soil biological and physical properties and improves yield in P-deficient chernozems, supporting the sustainable use of industrial by-products as cost-effective soil amendments. Future work should assess long-term effects on C sequestration, nutrient cycling, and economic feasibility.

Soil Systems doi: 10.3390/soilsystems9040113

Authors: Isaiah E. Jaramillo Carine Cocco James Jihoon Kang Chu-Lin Cheng Engil Pereira

The Aloe vera industry discards large amounts of outer leaf tissue (“shavings”), creating an opportunity to repurpose this byproduct as a sustainable fertilizer. This study evaluated whether aloe shavings can serve as a plant-based alternative to compost in organic Aloe vera production. A field trial in the Lower Rio Grande Valley of Texas tested three treatments: aloe shavings (applied to supply 39 kg N ha−1), organic compost (39 kg N ha−1), and a non-fertilized control. Laboratory incubations further assessed nitrogen mineralization and microbial respiration. Aloe shavings significantly enhanced vegetative growth: leaf number increased from 5.7 to 12.3 leaves per plant (+115% over the season), and leaf length rose from 20 to 32 cm, with the greatest gains in September and March (p < 0.05). At harvest, plants receiving aloe shavings produced 456 g total leaf weight and 151 g gel weight per plant, compared to 375 g and 108 g in the control. Incubations showed initial nitrogen immobilization (negative mineralization) but subsequent slow release, while microbial respiration was higher in compost (2.3 mg CO2-C kg−1 day−1) than aloe shavings (1.4 mg CO2-C kg−1 day−1). These results highlight aloe shavings as a low-cost, slow-release organic amendment that reduces waste, supports circular economy practices, and enhances Aloe vera growth without mineral nitrogen addition.

Soil Systems doi: 10.3390/soilsystems9040112

Authors: Sunshine A. De Caires Sabine Reinsch Duraisamy Saravanakumar Chaney St. Martin Mark N. Wuddivira Bernie J. Zebarth Fuat Kaya Mengying Liu Durga P. M. Chinthalapudi Shankar Ganapathi Shanmugam Bobbi Helgason

Soil bacterial communities are vital for ecosystem functioning in the humid tropics, yet their response to land-use change remains poorly understood. This knowledge gap is exacerbated by the lack of long-term studies. We employed a space-for-time substitution approach to assess the effects of land-use intensification on soil bacterial communities across a gradient of anthropogenic disturbance in Trinidad. Three sub-watersheds (Arouca = pristine, Maracas = intermediate, Tacarigua = intensive) were selected, each containing adjacent forest, grassland, and agricultural land uses. We combined geophysical soil apparent electrical conductivity (ECa-directed) sampling with 16S rDNA gene amplicon sequencing to characterize bacterial communities and their relationships with soil and landscape properties. Soil properties were the primary determinant of bacterial community structure, explaining 56% of the variation (p < 0.001), with pH, clay content, hygroscopic water, and nutrient availability as key drivers. Bacterial α-diversity differed significantly among sub-watersheds (p < 0.01), with Tacarigua exhibiting lower richness and diversity compared to Arouca and Maracas, but not across land uses. While a core microbiome of ten bacterial families was ubiquitous across land uses, indicating a stable foundational community, land-use intensification significantly altered β-diversity (p < 0.01 among sub-watersheds). Agricultural soils showed the greatest divergence from forest soils (p < 0.05), with a marked decline in key Proteobacterial families (e.g., Xanthomonadaceae, Pseudomonadaceae) involved in nutrient cycling and plant growth promotion. Although inherent soil properties shape the core microbiome, land-use intensification acts as a strong secondary filter, shifting soil bacterial communities toward more stress-resistant Firmicutes with potentially less diverse functions. Our findings demonstrate the utility of integrating space-for-time substitution with molecular profiling to predict long-term microbial responses to environmental change in vulnerable tropical ecosystems.

Soil Systems doi: 10.3390/soilsystems9040111

Authors: Yasaman Raeofy Vera Samburova Markus Berli Eden Furtak-Cole Brad Sion Sally Houseman Kristine Lu William Curtiss Andrew J. Andrade Bianca Martinez Andrey Y. Khlystov Hans Moosmüller

This study aims to understand the effects of wildfires in sagebrush ecosystem on soil properties by examining connections between Soil Water Repellency (SWR), reflectance, and chemistry. Ash and burned soil samples were collected after performing laboratory burns of three common sagebrush plants: sagebrush, rabbitbrush, and bitterbrush. The collected samples were analyzed for their physical properties, including SWR measured by Water Drop Penetration Time (WDPT) and Apparent Contact Angle (ACA), and solar spectral reflectance in the wavelength range of 350 to 2500 nm. Chemical functional groups of the samples were analyzed using Fourier-Transform Infrared (FTIR) spectroscopy. WDPT and ACA values were in the range of 1 to 600 s and ~10° to 88°, respectively, for all three tested fuels. The FTIR analysis showed a decrease (~2 to 4 times) in the ratio of COO−/C=C signals for the burned soil samples compared to the unburned soil samples. Overall, increase in temperature and ACA levels for the samples of burned and burned soil from a 2 cm depth led to increased formation of non-polar compounds with C=C functional groups, and decarboxylation.

Soil Systems doi: 10.3390/soilsystems9040110

Authors: Thomas P. McCarthy John B. Murphy Patrick J. Forrestal

Potassium (K) is essential for grassland productivity, but soil K leaching can reduce fertiliser use efficiency, increasing environmental losses. International evidence suggests soil type and K fertiliser timing influence K leaching, yet limited data exist for Ireland’s diverse soil types. This study investigated the effects of K fertiliser timing (autumn, winter, and spring) and soil type on K leaching using a controlled lysimeter facility with five representative Irish soils sown with perennial ryegrass. Potassium fertiliser (125 kg K ha−1) was applied in October, December, or February, with leachate collected from October to April. Soil type affected cumulative K leaching (1.4–9.8 kg ha−1; p ≤ 0.001), with the greatest losses observed in sandy soils. Potassium and nitrogen uptake in spring-harvested grass were also influenced by soil type (p ≤ 0.05), with strong positive correlation between the two nutrients (R2 = 0.78; p ≤ 0.001). Temporally, significant interactions (p ≤ 0.05) between K application timing and sampling date were found for K leachate in three of the five soils tested. Autumn and winter applications tended to increase cumulative leaching risk, especially on coarser-textured soils such as the Oakpark soil (p ≤ 0.05). The study indicates that applying K in early spring will tend to reduce leaching K losses, particularly on sandy soils.

Soil Systems doi: 10.3390/soilsystems9040109

Authors: Mariano A. Córdoba Susana B. Hang Catalina Bozzer Carolina Alvarez Lautaro Faule Esteban Kowaljow María V. Vaieretti Marcos D. Bongiovanni Mónica G. Balzarini

Understanding the temporal dynamics and spatial distribution of key soil properties is essential for sustainable land management and informed decision-making. This study assessed the spatial variability and decadal changes (2013–2023) of topsoil properties in Córdoba, central Argentina, using digital soil mapping (DSM) and machine learning (ML) algorithms. Three ML methods—Quantile Regression Forest (QRF), Cubist, and Support Vector Machine (SVM)—were compared to predict soil organic matter (SOM), extractable phosphorus (P), and pH at 0–20 cm depth, based on environmental covariates related to site climate, vegetation, and topography. QRF consistently outperformed the other models in prediction accuracy and uncertainty, confirming its suitability for DSM in heterogeneous landscapes. Prediction uncertainty was higher in marginal mountainous areas than in intensively managed plains. Over ten years, SOM, P, and pH exhibited changes across land-use classes (cropland, pasture, and forest). Extractable P declined by 15–35%, with the sharpest reduction in croplands (−35.4%). SOM decreased in croplands (−6.7%) and pastures (−3.1%) but remained stable in forests. pH trends varied, with slight decreases in croplands and forests and a small increase in pastures. By integrating high-resolution mapping and temporal assessment, this study advances DSM applications and supports regional soil monitoring and sustainable land-use planning.

Soil Systems doi: 10.3390/soilsystems9040108

Authors: Valeria Valenzuela Ruiz Errikka Patricia Cervantes Enriquez María Fernanda Vázquez Ramírez María de los Ángeles Bivian Hernández Marcela Cárdenas-Manríquez Fannie Isela Parra Cota Sergio de los Santos Villalobos

Biological control with beneficial bacteria offers a sustainable alternative to synthetic agrochemicals for managing plant pathogens and enhancing plant health. However, bacterial biocontrol agents (BCAs) remain underexploited due to regulatory hurdles (such as complex registration timelines and extensive dossier requirements) and limited strain characterization. Recent advances in omics technologies (genomics, transcriptomics, proteomics, and metabolomics) have strengthened the bioprospecting pipeline by uncovering key microbial traits involved in biocontrol. Genomics enables the identification of biosynthetic gene clusters, antimicrobial pathways, and accurate taxonomy, while comparative genomics reveals genes relevant to plant–microbe interactions. Metagenomics uncovers unculturable microbes and their functional roles, especially in the rhizosphere and extreme environments. Transcriptomics (e.g., RNA-Seq) sheds light on gene regulation during plant-pathogen-bacteria interactions, revealing stress-related and biocontrol pathways. Metabolomics, using tools like Liquid Chromatography–Mass Spectrometry (LC-MS) and Nuclear Magnetic Resonance spectroscopy (NMR), identifies bioactive compounds such as lipopeptides, Volatile Organic Compounds (VOCs), and polyketides. Co-culture experiments and synthetic microbial communities (SynComs) have shown enhanced biocontrol through metabolic synergy. This review highlights how integrating omics tools accelerates the discovery and functional validation of new BCAs. Such strategies support the development of effective microbial products, promoting sustainable agriculture by improving crop resilience, reducing chemical inputs, and enhancing soil health. Looking ahead, the successful application of omics-driven bioprospection of BCAs will require addressing challenges of large-scale production, regulatory harmonization, and their integration into real-world agricultural systems to ensure reliable, sustainable solutions.

Soil Systems doi: 10.3390/soilsystems9040107

Authors: Qaiser Javed Mohammed Bouhadi Igor Palčić Dominik Anđelini Danko Cvitan Nikola Major Marina Lukić Smiljana Goreta Ban Dean Ban David Heath Tomaž Rijavec Aleš Lapanje Marko Černe

Olive pomace (OP) contains phytotoxic compounds that can impair plant growth and soil quality. Composting provides an effective method for detoxifying olive pomace (OP) and improving its suitability for agricultural use. Therefore, this study investigated the phytotoxic effects of raw olive pomace filtrate (OPF) on seed germination in radish (Raphanus sativus L.) and barley (Hordeum vulgare L.), as well as the impact of composted olive pomace (COP) on their growth. Seeds were exposed to OPF at concentrations of 0% (control), 1%, 3%, 5%, 10%, 20%, and 100%. Additionally, three composting treatments were evaluated: R1 (control: OP + barley straw), R2 (OP + barley straw + urea), and R3 (OP + barley straw + sheep litter). Results showed that OPF at concentrations of 10%, 20%, and 100% significantly reduced seed germination, with complete inhibition at concentrations > 10%. The COP treatments showed different physicochemical properties, such as R2 exhibiting better nutrient availability (C/N = 19, oil content = 0.04%). R3 had the highest concentrations of K (40,430.2 mg/kg) and P (6022.68 mg/kg). Results also indicated that R1 significantly reduced radish dry biomass production compared to barley, although R2 performed slightly better than R1 and R3. The findings highlight the need for proper compost stabilization to minimize the phytotoxicity and improve the agricultural potential of COP for improving soil health.

Soil Systems doi: 10.3390/soilsystems9040106

Authors: Diego Arán Maria Manuela Abreu Luisa Louro Martins Miguel Pedro Mourato Erika S. Santos

Rice is one of the world’s most consumed foods, and the cereal that most efficiently uptakes and accumulates As, contributing to human health risk. Flooded rice fields alter Eh-pH conditions and, consequently, the proportion of As(III)/As(V), favoring their accumulation in the crop. The use of algae in paddy soils can improve fertility and C-stock and affect chemical conditions and As availability. This study aimed to evaluate the effect of algae application on: As adsorption capacity in paddy soils from Sado, Portugal, changes in pH-Eh conditions in the soil–water environment, and consequent As speciation. Batch-based As adsorption assays were performed with different solid–solution ratios and Chlorella minutissima algae application, and fitted to the Freundlich and Langmuir linear models. In semi-continuous column assays, simulating rice field conditions, the effect of algae on the pH-Eh of soil pore water was evaluated. The soil quality assessment showed pseudo-total contents of As and other elements higher than Portuguese agriculture limits (11 mg As kg−1), but their availability was low, posing no environmental risk. The studied soils had great As adsorption, which increased with algae application (1.07 mg g−1). Algae application favored oxygenation, increasing Eh values, and maintaining As(V) species. This indicated a potential approach to reducing As(III) mobility.

Soil Systems doi: 10.3390/soilsystems9030105

Authors: Oumayma Hmidi Feyda Srarfi Nadhem Brahim Carmelo Dazzi Giuseppe Lo Papa

Assessing soil and water quality in irrigated farming is vital for sustainable agriculture management. Low-quality irrigation water, particularly in semi-arid regions, poses environmental challenges and leads to soil salinization. This study was conducted in the Jedaida district, Manouba province, NE Tunisia. Forty-three soil and water samples were collected to develop indices for assessing soil quality. Sixteen indicators were selected using principal component analysis (PCA) for the minimum soil data set (MSD), including electrical conductivity, sand, organic soil carbon, and pH. The linear method shows a correlation with physical and chemical properties, classifying Jedaida soils into three quality metrics: good, moderate, and poor. The non-linear method displays the lowest indicator contribution in Zahira soils, followed by Mansoura soils (high and moderate). MSD combined with linear scoring is the most acceptable method of assessing the soil quality index (SQI). Water quality indices (WQIs) identify the suitability of irrigation. The results show a Kelly’s ratio > 1, a sodium adsorption ratio (SAR) > 10, and a sodium soluble percentage (SSP) varying from 40 to 60%. This highlights the negative effects of long-term irrigation with poor-quality water on soil health. Accordingly, groundwater was found to be unsuitable for irrigating surface soils. This finding emphasizes the importance of selecting suitable irrigation water to ensure soil quality.

Soil Systems doi: 10.3390/soilsystems9030104

Authors: Tajamul Hussain Charassri Nualsri Muhammad Fraz Ali Saowapa Duangpan

Effective residue management is crucial for maintaining soil organic carbon (SOC) in upland rice systems, particularly under diverse fertilization and planting management practices. This study investigates the impacts of residue management in upland rice fields using the CQESTR model through simulation of SOC dynamics over a 20-year period. The first 10 years served as a spin-up period for carbon pool stabilization in the model, followed by simulations under varying nitrogen (N) application rates and planting date management strategies. Experiments for various N application rates and planting times were conducted during 2018–2019 and 2019–2020. In 2019, 30% and in 2020, 100% of the residue was returned, and these data were used for evaluating model performance. Subsequently, we modeled predictions for residue retention levels of 100%, 70%, 50%, and 30% to assess their effects on SOC. The results indicated a good agreement between the simulated and observed data for model performance evaluation with an MSD value of 9.13. Lack of correlation (0.44) accounted for 5% of MSD, indicating a good agreement between the simulated and observed SOC values. The highest change in SOC was observed at 100% residue return under moderately delayed planting, potentially due to higher crop productivity and residue retention, and moderate climatic conditions. Reduced residue retention gradually declined the SOC stocks, especially under low N input. Delays in planting exacerbated negative impacts, possibly due to low crop productivity and reduced residue return. Despite the limited number of years of data and inconsistent management practices, the overall trends highlight the importance of residue retention under different N fertilization and planting management strategies. This research serves as a preliminary study for sustainable management practices to enhance long-term soil carbon sequestration in upland rice systems in southern Thailand. Long-term evaluations are necessary using the observed data and the CQESTR model application for applicable recommendations.

Soil Systems doi: 10.3390/soilsystems9030103

Authors: Fatihu Kabir Sadiq Ojone Anyebe Fatima Tanko Aisha Abdulkadir Bonface O. Manono Tiroyaone Albertinah Matsika Fahad Abubakar Suleiman Kehinde Bello

Conservation agriculture (CA) is widely recognized as the cornerstone of sustainable agriculture. It prioritizes minimizing soil disturbance, maintaining permanent soil cover, and diversifying crop species to restore soil health and ecosystem resilience. This review synthesizes the effects of CA on the soil’s physical–chemical and biological properties. It demonstrates its effectiveness in improving soil structure, enhancing organic carbon sequestration, promoting microbial activity, increasing water-use efficiency, and reducing erosion and nutrient losses. The paper then highlights the broad environmental, economic, and social benefits of CA. These include biodiversity conservation, reduced greenhouse gas emissions, improved yields, and increased food system resilience. The review explores the synergistic role of technological innovations such as precision agriculture, remote sensing, and digital tools in scaling CA for higher productivity and sustainability. The review then examines how socioeconomic conditions, institutional frameworks, and policy interventions shape CA adoption and impact. Despite its growing adoption, CA’s successful implementation will require strategies adapted for local needs, capacity-building, and supportive, inclusive policies. Finally, the review identifies key CA research gaps and future directions. This provides a comprehensive foundation to advance CA as a climate-smart, resilient, and sustainable pathway to ensure global food security and environmental stewardship.

Soil Systems doi: 10.3390/soilsystems9030102

Authors: Paulo Roger Lopes Alves German Andres Estrada-Bonilla Antonio Marcos Miranda Silva Thiago Gumiere Ademir Durrer Bigaton Daniel Bini Cristiane Alcantara dos Santos Elke Jurandy Bran Nogueira Cardoso

This study explored how different sugarcane vinasses influence the structure and composition of soil bacterial communities in two tropical Oxisols with contrasting textures. In a controlled microcosm experiment with sugarcane seedlings, two concentrations of three vinasse types were applied, and bacterial communities were monitored over 10, 30, and 60 days using T-RFLP and 16S rRNA gene sequencing. Across all treatments, vinasse application led to clear changes in bacterial community structure in both soils, regardless of the time point. Certain bacterial groups, such as Sphingobacteriia, Alphaproteobacteria, and Gammaproteobacteria, became more abundant—likely responding to increased carbon availability, higher pH, and greater soil moisture. At the same time, other groups declined, possibly due to excess nutrients like potassium and sulfur. Notably, these shifts occurred even when standard biochemical indicators suggested no major impact, highlighting the sensitivity of microbial community-level responses. These findings point to the importance of looking beyond traditional soil quality metrics when assessing the environmental effects of organic residue applications. Incorporating microbial indicators can offer a more nuanced understanding of how practices like vinasse reuse affect soil functioning in tropical agroecosystems.

Soil Systems doi: 10.3390/soilsystems9030101

Authors: Arianis Ibeth Santos-Nicolella Kleve Freddy Ferreira Canteral Wanderson Benerval De Lucena Maria Elisa Vicentini Alan Rodrigo Panosso Kurt Spokas Glauco de Souza Rolim Thaís Rayane Gomes da Silva Newton La Scala

Soil CO2 emissions, driven primarily by microbial respiration, represent a major component of terrestrial carbon flux and play a crucial role in global climate change. Although several soil physicochemical factors regulating microbial activity are well known, the role of soil solution viscosity remains largely unexplored. This study evaluated how polyethylene glycol (PEG6000)-induced increases in soil solution viscosity affect microbial activity-derived CO2 emissions in a Rhodic Ferralsol (eutric). Three concentrations of PEG6000 (50, 75, and 100 g L−1), corresponding to viscosities of 1.93, 2.76, and 3.88 cP, respectively, were compared to a water-based control (1.11 cP). Soil CO2 emissions, soil O2 capture, temperature, and water content were measured over a 60-day period using standard methods. Results showed significant reductions in cumulative CO2 emissions of 20%, 25%, and 12% for PEG6000 treatments, respectively, compared to the control. Decreased O2 capture at viscosities of 1.93 and 2.76 cP (50 and 75 g L−1, respectively) indicated reduced microbial activity. These findings reveal a previously underappreciated biophysical mechanism regulating soil carbon emissions. Understanding and managing soil solution viscosity could offer a novel strategy to mitigate CO2 emissions in tropical soils, thus contributing to climate change mitigation and sustainable soil management, particularly in highly weathered tropical ecosystems.

Soil Systems doi: 10.3390/soilsystems9030100

Authors: Ilaria Battisti Anna Rita Trentin Andrea Sabia Antonio Masi Giancarlo Renella

Environmental pollution by poly- and perfluoroalkyl substances (PFAS) can impact human health through drinking water and the ingestion of contaminated agri-food. Plants can take up PFAS from polluted soils or irrigation waters, and soil amended with biochar has been proposed as a practical and sustainable option to effectively reduce the PFAS transfer from soils to plants. We evaluated the potential of biochar, the byproduct of biomass pyrolysis, to reduce or prevent PFAS uptake from contaminated soil and water in a field trial conducted in a PFAS-contaminated area, where tomato and red chicory plants were grown in succession. The PFAS content in irrigation water, soil, and tomato and red chicory plants was determined by liquid chromatography coupled to mass spectrometry before and after each cultivation trial. Compared to those grown in unamended soil, tomato plants grown in the biochar-amended soil showed a significantly lower uptake of perfluorobutane sulfonic acid (PFBS), perfluoroheptanoic acid (PFHpA), and perfluorooctanoic acid (PFOA) in the leaves (−70%, −45%, and −84%, respectively), and significantly less (−61%) perfluorobutanoic acid (PFBA) in the fruits. Compared to unamended soils, leaves of red chicory plants grown in biochar-amended soil accumulated less PFBS (−74%) in the early growth stage and less PFBA (−34%) at plant maturity. The presented results confirmed previous reports on the potential soil amendment with biochar as a sustainable and effective measure for reducing PFAS uptake by horticultural crops cultivated in PFAS-polluted areas and PFAS concentration in their edible parts. Implications of this approach are also discussed.

Soil Systems doi: 10.3390/soilsystems9030099

Authors: Yadunath Bajgai Ameeta Adhikari Rattan Lal Tashi Wangdi

Soil health and fertility are essential components of sustainable land management. In Bhutan, where agricultural practices range from organic to conventional systems, and natural vegetation areas persist across varied elevations. Understanding how these factors influence soil properties is essential for advancing sustainable agriculture and fostering environmental stewardship. Thus, the objectives of this study were to evaluate some soil chemical properties across land use practices and their relationship to soil texture. Soil organic carbon (SOC) and macro-nutrients in three land use types (organic fields—OrgF; conventional fields—ConF; and natural vegetation—NatV) were studied across high-, mid-, and low-altitude sites in the Wangdue Phodrang, Chhukha, and Dagana districts of Bhutan. The effects of land use practices on soil properties varied with altitude. While available P responded significantly at both high- and mid-altitude locations (p < 0.01), SOC content was influenced only at high altitude (p < 0.001). In contrast, soil pH (p < 0.01) and available K (p < 0.001) showed clear sensitivity to land use at low altitude but were unaffected at higher elevations. Total N content and C:N ratios remained relatively stable across management practices within each altitude category. Silt and clay content had positive relationship with SOC (R2 ≥ 0.13), whereas sand content had a significant negative relationship (R2 = 0.23, p < 0.001). These findings are pertinent to providing guidelines for sustainable land management, improving agricultural practices, and shaping policies to protect and restore soil health across varied agro-ecological zones.

Soil Systems doi: 10.3390/soilsystems9030098

Authors: Jinxi Chen Yuanbo Jiang Wenjing Yu Guangping Qi Yanxia Kang Minhua Yin Yanlin Ma Yayu Wang Jiapeng Zhu Yanbiao Wang Boda Li

Soil moisture plays a critical role in the global water cycle, the exchange of matter and energy within ecosystems, and the movement of water in plants. Accurate monitoring of soil moisture is essential for drought early warning systems, irrigation decision-making, and crop growth assessment. The use of drone-based multispectral remote sensing technology for estimating the soil moisture content offers advantages such as wide coverage, high accuracy, and efficiency. However, the soil background can often interfere with the accuracy of these estimations. In specific environments, such as areas with strong winds, removing soil background noise may not necessarily enhance the precision of estimates. This study utilizes unmanned aerial vehicle (UAV) multispectral imagery and employs a vegetation index threshold method to remove soil background noise. It systematically analyzes the response relationship between spectral reflectance, spectral indices, and the soil moisture content in the top 0–10 cm layer of alfalfa; constructs K-Nearest Neighbors (KNN), Random Forest Regression (RFR), ridge regression (RR), and XG-Boost inversion models; and comprehensively evaluates model performance. The results indicate the following: (1) The XG-Boost model validation set had the highest R2 value (0.812) when spectral reflectance was used as the input variable, which was significantly better than the other models (R2 = 0.465 to 0.770), and the RFR model validation set had the highest R2 value when the spectral index was used as the input variable (0.632), which was significantly better than the other models (R2 = 0.366 to 0.535). (2) After removing soil background noise, the accuracy of the soil moisture estimates for each model did not show significant changes; specifically, the R2 value for the XG-Boost model decreased to 0.803 when using spectral reflectance as the input, and the R2 value for the RFR model dropped to 0.628 when using spectral indices. (3) Before and after removing the soil background noise, the spectral reflectance can provide more accurate data support for the inversion of the soil moisture content than the spectral index, and the XG-Boost model is the most effective in the inversion of the soil moisture content when using the spectral reflectance as the input variable. The research findings provide both theoretical and technical support for the retrieval of the surface soil moisture content in alfalfa using drone-based multispectral remote sensing. Additionally, they offer evidence that validates large-scale soil moisture remote sensing monitoring.

Soil Systems doi: 10.3390/soilsystems9030097

Authors: Zsolt Zoltán Fehér Tamás Magyar Florence Alexandra Tóth Péter Tamás Nagy

Monitoring the concentration of heavy metals in urban soils is of a paramount importance for several reasons. These inorganic pollutants can pose a significant health risk to living organisms, as they are toxic even at low concentrations and can be present in the soil for a long period of time. This study assesses the spatial distribution, concentration levels, and potential anthropogenic and natural sources of eight typical heavy metals (As, Cd, Co, Cr, Cu, Ni, Pb and Zn) occurring in urban surface soils across Debrecen, Hungary. A total of 295 topsoil samples were collected; heavy metal concentrations were determined by energy-dispersive X-ray fluorescence (EDXRF) spectrometry. The results were interpreted using descriptive statistics, correlation analysis, hierarchical clustering, factor analysis, ordinary kriging interpolation, and spatial-discriminant analysis. The dual origin of the metal contaminants was revealed: As, Co, Pb, and Zn showed strong anthropogenic signatures associated with traffic, urban waste, and construction materials, whereas Cr and Ni were associated with natural geogenic sources. Cd reflected both lithogenic and point-source urban pollution. The current evaluation incorporated Hungarian and Dutch regulatory benchmarks to identify exceedances of environmental quality thresholds. It was found that only Cd and Cr exceeded the Hungarian target values, on average. Linear discriminant analysis based on pollution maps highlighted contamination hotspots around traffic corridors and newly industrialized zones. The importance of high-resolution soil monitoring in the rapidly urbanizing city is highlighted. Given its anticipated industrial and transportation developments, accumulations of heavy metals are probably going to be further exacerbated; therefore, the results provide a critical baseline for future environmental assessments and long-term monitoring.