Environmental and Earth Sciences

Abstract: The biological nitrogen fixation of black locust (Robinia pseudoacacia L.) is an important factor that allows the trees to survive under adverse environmental and nutrient-poor soil conditions. Due to the open-cast mining activities, large areas in the Lusatian region in eastern Germany were left unproductive with a very nutrient-poor soil with a low amount of nitrogen (N), phosphorous (P) and no organic matter. The symbiotic N₂ fixation of Robinia pseudoacacia L. has been investigated using the natural ¹⁵N abundance method. Moreover, the C:N:P ratio of soil and plants was determined. In addition, the impact of low soil P nutrition on nitrogen fixation was investigated. The N and P increased with the age of the tree plantation, but no relation was found between the carbon content and the age of the trees. Previous studies have seen an increase in soil N and P with the age of Robinia pseudoacacia L. The desorption of P was higher in the oldest plantation site, which is related to the plant availability of P. Results from the NdfA% show that about 98% and 88% of N were derived from the air by the plants planted in the reference zero site and the oldest plantation site, respectively. This slight difference in nitrogen fixation indicates that P has less impact on the nitrogen fixation of Robinia pseudoacacia L. Hence, more long-term research is required to examine the P uptake of plants from low P soil and how plants manage the biological N fixation with low soil P.

Abstract: Soil microorganisms are essential for nutrient cycling, plant productivity, and soil health, yet the relative importance of land use and soil depth in shaping agricultural microbiomes remains poorly understood. This study investigated soil microbial com-munities across uncultivated land, alfalfa fields, crop systems (feed corn and sweet corn), and orchard systems (walnut and quince) in the Hajdúnánás region of Hungary using shotgun metagenomic sequencing and soil physicochemical analyses. Microbial alpha diversity varied little among land-use systems but declined signifi-cantly with soil depth. Community composition was primarily structured by depth (R² = 0.233, p = 0.001), while land-use effects were stronger for fungal communities (p = 0.001) than for bacterial communities (p = 0.012). Crop soils contained the highest numbers of unique bacterial and fungal taxa. Functional analyses revealed significant differences in nutrient cycling, plant-growth-related, decomposition, and environ-mental adaptation functions among land-use systems. In crop soils, topsoil communi-ties were enriched in oxidative stress-related pathways involved in ROS detoxification, redox homeostasis, and stress regulation, whereas subsoil communities showed a greater representation of antioxidant metabolite production functions. Co-occurrence network analyses indicated greater connectivity in perennial systems, particularly al-falfa soils. Pathogen analyses identified stable bacterial and fungal pathogen cores across agricultural systems, with soil pH emerging as the strongest environmental factor associated with pathogen abundance. Overall, soil depth was the primary driver of microbial community assembly, whereas land use mainly influenced microbial composition, ecological functions, interaction networks, and pathogen distribution.

Abstract: Integrated organo-mineral fertilization is considered an effective strategy for im-proving soil quality, nutrient use efficiency, and productivity in acidic orchard systems. This study evaluated the effects of compost (30 t ha⁻¹ combined with P₁₅₀K₁₂₀) and nitrogen fertilizers (urea or ammonium nitrate applied at 0, 90, 120, and 150 kg ha⁻¹) on soil quality, nutrient dynamics, yield, fruit quality, and nu-trient use efficiency (NUE) of kiwifruit grown on acidic Luvisols in the humid subtropical Lankaran–Astara region of Azerbaijan during a two-year field ex-periment. Integrated fertilization significantly increased soil organic carbon (SOC), water-stable aggregates (WSA), and nutrient availability (NH₄⁺–N, NO₃⁻–N, P₂O₅, and K₂O) in both non-degraded and moderately degraded soils. Results showed strong positive relationships between soil organic carbon (SOC) and soil fertility parameters, particularly NH₄⁺–N (R² = 0.92), NO₃⁻–N (R² = 0.84), P₂O₅ (R² = 0.82), and water-stable aggregates (WSA; R² = 0.76), highlighting the crucial role of SOC in enhancing soil fertility, promoting nutrient availability, and improving soil structural stability. Stepwise regression analysis showed that NO₃⁻–N (~73%), P₂O₅, SOC, and K₂O together explained 93% of the variation in kiwifruit yield (R² = 0.93, P < 0.001). Fertilization significantly improved kiwifruit productivity and fruit quality. In non-degraded soil, yield increased from 7004 to 20,139 kg ha⁻¹ under Base + N150treatment; however, the increase over Base + N120 was small and non-significant. Urea generally resulted in higher yield, better fruit quality, and greater NUE than ammonium nitrate, particularly under non-degraded soil conditions. The highest NUE was observed under the urea N120 treatment (0.99), whereas NUE declined at higher nitrogen application rates. Integrated fertilization also reduced the productivity gap between degraded and non-degraded soils, demonstrating its restorative potential for degraded acidic Luvisols. The combi-nation of compost (30 t ha⁻¹) and a moderate nitrogen application rate (N120), particularly in urea form, represented the most effective strategy for improving soil fertility, enhancing kiwifruit yield and quality, increasing economic return, and reducing possible environmental risks under humid subtropical conditions.

Abstract: Desertification represents a critical environmental challenge in arid and semi-arid regions, driven by the synergistic impacts of climate change and unsustainable landuse practices. This review presents a comparative assessment of desertification dynamics, mitigation strategies, and ecological restoration approaches in the Ningxia Hui Autonomous Region (China) and Egypt. Both regions are characterized by severe water scarcity, increasing climatic variability, and fragile ecosystems; however, they differ in ecological conditions, institutional frameworks, and dominant land degradation processes. The study synthesizes major drivers of desertification, including rising temperatures, precipitation variability, recurrent droughts, soil salinization, overgrazing, wind erosion, and unsustainable agricultural expansion. It further evaluates key control measures implemented in both regions, such as afforestation and ecological engineering, sand dune stabilization, water-efficient irrigation systems, soil rehabilitation practices, and the integration of remote sensing and GIS-based monitoring technologies. The analysis highlights China’s large-scale, long-term ecological restoration programs, which have significantly improved vegetation cover and reduced land degradation, compared to Egypt’s focus on irrigation efficiency, land reclamation, and salinity management under extreme aridity constraints. The comparative synthesis demonstrates that effective desertification control requires integrated strategies combining ecological restoration, sustainable water resource management, technological innovation, and strong policy support. Despite contextual differences, both regions offer complementary lessons for dryland management. The study emphasizes the potential for enhanced China–Egypt cooperation in climate-smart agriculture, digital environmental monitoring, and nature-based solutions to advance sustainable land restoration under future climate change scenarios.

Abstract: We present a global metadata comprising results from studies investigating the effects of cover crops (CCs) on six key soil hydraulic properties, namely total porosity, infiltration rate, saturated hydraulic conductivity, water retention at field capacity and permanent wilting points, and available water holding capacity. This data repository is the result of a global meta-analysis entitled “Cover crop performance and functional groups regulate improvements in Soil Hydrology: A Global Meta-analysis". Globally, numerous studies have investigated the role of CCs on soil hydraulic properties, but the results have varied across sites and years. Hence, the objective of the meta-analysis was to synthesize existing knowledge base to assess overall effects of CCs on these soil hydraulic properties and evaluate how environmental and management factors moderate these overall CC responses. We searched for peer-reviewed research articles published through 5th October 2024 in the ISI Web of Science database and reference checking following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 146 relevant articles were identified from which data on CC responses were extracted. The metadata consists of 1007 pairwise observations comparing CC vs no-CC controls across diverse geographic regions worldwide. Moreover, we collected associated metadata for each pairwise comparison that includes a broad set of bibliographic, geographic, soil, climate, and management variables. Categorical variables were grouped into pre-defined factor levels or classes. Missing soil and climate data were filled using publicly available data-products. Our data repository can be a valuable resource for the field and modeling community to identify knowledge gaps and guide future research.

Abstract: In the UK, contaminated land risk assessments using the Contaminated Land Exposure Assessment (CLEA) model rely on soil organic matter (SOM) values to determine acceptable thresholds for contamination caused by anthropogenic pollution for human health. Soil organic carbon (SOC), total organic carbon (TOC) or loss on ignition (LOI) are routinely used as a proxy for SOM in the industry, both by contaminated land consultants and laboratories who rely on conversions such as the Van Bemmelen factor. Many standard laboratory methods for measuring SOC or TOC do not differentiate between natural organic carbon and petroleum hydrocarbons. This study investigates the interference of total petroleum hydrocarbons (TPH) on SOC measurements by analysing 2,375 brownfield soil samples. A positive correlation was observed between the two variables; an addition of 1,000 mg/kg of TPH inflates reported SOC by 0.46 percentage points. When converted to SOM for risk assessment purposes using the Van Bemmelen factor, this artificial increase rises to 0.79 percentage points calculated SOM per 1000mg/kg TPH. This can push soils into higher assessment bands, generating less stringent Generic Assessment Criteria (GAC). The study finds that relying on SOC as a proxy for SOM in hydrocarbon-impacted soils masks the absence of the natural organic matter required to sorb contaminants, leading to an underestimation of human health risks in contaminated land risk assessments.

Abstract: Mangrove ecosystems are significant blue carbon sinks but can also act as sources of greenhouse gases, particularly carbon dioxide (CO₂) and methane (CH₄), due to complex sediment biogeochemical processes. This study quantified the influence of seasonal and tidal variability on soil–atmosphere CO₂ and CH₄ fluxes in mangrove ecosystems of the Lamu Archipelago, Kenya. Field measurements were conducted across wet and dry seasons and varying tidal heights, alongside key environmental parameters including temperature and humidity. Non-parametric statistical analyses revealed that CH₄ fluxes were significantly influenced by temperature variability (p < 0.05), whereas CO₂ fluxes were significantly associated with humidity (p < 0.05). Both gases exhibited significant seasonal variation (p < 0.05), with elevated CO₂ emissions during the dry season and higher CH₄ emissions during the wet season, reflecting shifts between aerobic and anaerobic sediment conditions. Tidal height exerted a significant effect on both CO₂ and CH₄ fluxes (p < 0.05), underscoring the role of tidal inundation in regulating redox dynamics and gas exchange processes. These findings demonstrate the strong coupling between climatic and meteorological parameters in controlling mangrove GHG fluxes and highlight the importance of incorporating temporal variability into blue carbon assessments. The study provides empirical data to refine greenhouse gas inventories and improve the representation of tropical coastal wetlands in climate models and mitigation frameworks.

Abstract: The cycling of greenhouse gases (GHGs) in soils is fundamentally regulated by molecular oxygen, and trees restructure the local O₂ landscape through root macropore networks, rhizosphere oxygen demand, and canopy-mediated moisture redistribution, generating spatially structured redox transitions that govern CO₂, N₂O, and CH₄ fluxes across distances of just a few meters from the stem. Despite this inherent spatial heterogeneity, most studies measuring soil GHG emissions in tree-based systems report fluxes from single locations without documenting distance from trees, effectively assuming spatial homogeneity where none exists. We introduce triproximity, a conceptual framework that considers tree–soil GHG interactions across three spatial dimensions: (i) horizontal distance from tree stems, (ii) vertical soil profile depth, and (iii) structural position relative to tree components, including the stem itself as a gas conduit. Following PRISMA guidelines, we systematically reviewed 107 field-based studies published between 2010 and 2025 spanning shelterbelts, agroforestry, orchards, silvopastoral systems, and riparian buffers across temperate, subtropical, and arid climates. Only 37.4% of studies explicitly reported measurement distance from trees, a proportion that has not improved despite a near four-fold increase in publication volume since 2020. Methane uptake showed the most consistent spatial response, with higher oxidation rates in the near-tree zone across diverse system types, most plausibly reflecting root-mediated improvements in soil aeration and methanotrophic activity. Nitrous oxide responses were context-dependent, governed by competing substrate availability and moisture controls that the triproximity dimensions help disentangle. Carbon dioxide fluxes showed no universal spatial pattern, yet were responsive to specific proximity dimensions once the dominant source term was identified. Stem-level gas transport was virtually unmeasured across the dataset, likely biasing ecosystem GHG budgets toward underestimation. We propose a minimum triproximity-based sampling protocol specifying horizontal distances, vertical depths, structural positions, and replicate requirements for five major tree-based system types, and call for journals to adopt spatial reporting as a minimum submission standard for GHG studies in tree-based agricultural systems.

Abstract: Fruit and vegetable wastes are important organic resources that can be recycled into value-added agricultural products through microbial fermentation. However, the characteristics of fermentation broths (FBs) derived from different fruit and vegetable substrates and their effects on soil ecological processes remain insufficiently understood. In this study, FBs were produced from 14 common fruit and vegetable wastes through anaerobic fermentation, whose characteristics were systematically analyzed in terms of nutrient composition, enzyme activities, and microbial community structure. Five representative FBs derived from garlic, tomato, sweet potato, apple, and lettuce were selected for pot experiments to evaluate their effects on soil properties and the growth of Brassica chinensis. The results showed significant differences among the FBs in nutrient contents, enzyme activities, and microbial community composition. The application of garlic FB exhibited the highest concentrations of ammonium nitrogen (309.81 mg/L), total phosphorus (327.73 mg/L), total potassium (1365.8 mg/L), and organic matter (28.99 g/L) in the pot soil, together with significantly higher activities of acid phosphatase, urease, protease, and catalase in the soil than the other treatments (P < 0.05). Metagenomic analysis revealed that the soil treated with garlic FB was dominated by lactic acid bacteria, with Lactiplantibacillus, Lentilactobacillus, and Levilactobacillus accounting for approximately 79% of the microbial community. The application of FBs significantly improved the availability of soil nutrients and the activities of enzymes. Among all the treatments, the application of garlic FB showed the strongest effects, increasing the activities of catalase, urease, acid phosphatase, and β-glucosidase in the soil by 83.34%, 180.72%, 112.34%, and 21.95%, respectively. Furthermore, the application of FBs reduced the incidence of pests and diseases, and promoted the growth of Brassica chinensis. Compared with the other treatments, the garlic FB treatment produced the highest vegetable biomass. It was concluded that the application of the FBs manufactured from fruit and vegetable wastes enhanced soil fertility and crop performance through the regulation of microbial communities, stimulation of soil enzyme activities, and promotion of nutrient cycling. For comparison, the application of Garlic FB exhibited the greatest potential as a sustainable biofertilizer for vegetable production and organic waste recycling.

Abstract: This study proposes a Gaussian Process Regression (GPR) method for estimating the compressive strength of soil mixtures containing bentonite and basalt fibers. GPR is a preferred probabilistic machine learning approach, especially for limited datasets, due to its high generalization ability and its ability to directly calculate prediction uncertainty. In this study, experimentally obtained bentonite and basalt fiber ratio values were used as input parameters of the model, and unconfined compressive strength (q_u) was determined as the output variable. Model performance was evaluated using the Leave-One-Out Cross Validation (LOOCV) method. The performance of the proposed GPR model was evaluated with various metrics. Accordingly, the values of the MAE, RMSE, and R² metrics of the model were calculated as 3.6%, 5.2%, and 0.955, respectively. The results show that the GPR model provides high prediction accuracy and is a reliable prediction tool for small datasets. Furthermore, the prediction surfaces and uncertainty analyses obtained by the model contributed to a better understanding of the effect of mixture parameters on compressive strength.

Abstract: This study investigated the role of soil chemical attributes in explaining yield variability in a commercial flooded rice system in southern Brazil during the 2024/2025 growing season. We hypothesized that spatial variability in rice yield is primarily controlled by soil fertility gradients and redox-induced accumulation of Fe and Mn under flooding conditions. The study was conducted in a 45-ha field, where 44 soil samples (0–20 cm) were analyzed for chemical attributes and irrigation water depth. Grain yield data were collected using a combine harvester equipped with a yield monitor and used to generate thematic and relative yield maps. Data were evaluated through descriptive statistics, Pearson correlation, and principal component analysis (PCA). Average grain yield was 10.35 t ha⁻¹, with a spatial variability range of 4.5 t ha⁻¹. PCA explained 76.4% of the total variance, with the first component representing a fertility gradient characterized by higher Ca, Mg, organic matter, and Si contents positively associated with yield, whereas Fe and Mn showed negative associations. High-yield zones exhibited greater cation saturation and lower Fe and Mn concentrations. These findings demonstrate that yield heterogeneity is driven by the interaction between soil fertility and redox-mediated micronutrient dynamics, highlighting the importance of site-specific nutrient and water management.

Abstract: Groundwater depth is a key control on soil salinization in arid irrigation districts, but seasonal groundwater-depth thresholds for different salinization risks remain poorly constrained. Here, we examined the Yichang irrigation area of the Hetao Irrigation District using groundwater-depth observations and 0-60 cm soil-salinity samples collected before spring irrigation and during the crop-growing season. Indicator Kriging was used to map threshold-based probability zones for groundwater depth and soil salinity, and high-probability matching rates were used to identify critical groundwater depths for light and moderate salinization. Groundwater depth showed moderate spatial variability in both seasons, whereas soil salt content showed strong spatial variability. The critical groundwater depths for light and moderate salinization were 2.6 and 2.2 m before spring irrigation, and 2.2 and 1.8 m during the growing season, respectively. Soil salt content in the 0-20, 20-40, 40-60 and 0-60 cm layers decreased with increasing groundwater depth, with the 0-60 cm layer well described by an exponential response function. These findings provide a spatially explicit basis for seasonal groundwater regulation, salinization-risk zoning and field-scale water-salt management in arid irrigation districts.

Abstract: Solonetz and Solonetzic rangelands are widespread in arid regions of Central Kazakhstan, where pasture degradation is often difficult to assess because surface vegetation patterns do not always reflect subsurface soil constraints. This study aimed to evaluate degradation mechanisms in Solonetz pasture ecosystems of the Ulytau region by integrating field soil-profile descriptions, laboratory analyses, vegetation observations, forage productivity data and Sentinel-2A-derived MSAVI. Ten monitoring soil profiles were examined for particle-size distribution, soluble salts, ionic composition, exchangeable cations, available N, P and K, vegetation cover and forage yield. USDA textural classification, salt-distribution analysis, Pearson correlation, PCA, RDA and MSAVI-based mapping were used to link soil-profile properties with vegetation and spectral response. The results showed strong profile heterogeneity, with clay enrichment, subsurface salt accumulation, alkalinity and Na- or Mg-related exchange-complex imbalance forming several degradation pathways. Surface horizons were often weakly saline, whereas deeper layers contained stronger chemical and physical limitations. MSAVI values were low across the monitoring sites and reflected vegetation–soil surface conditions rather than salinity or sodicity directly. Combining soil-profile diagnostics with Sentinel-2A MSAVI improved the interpretation of degradation patterns and provides a practical framework for monitoring spatially heterogeneous Solonetz rangelands in arid pasture systems.

Abstract: Soil microorganisms and plant residue decomposition are critical drivers of soil nutrient cycling and multifunctionality, yet their regulatory mechanisms in saline-alkali soils are not fully understood. This study selected bare land and forestland (shrub and tree stands) in Daqing, Heilongjiang, to investigate the effects of plant residue input on forest soil properties, microbial communities, keystone taxa, and multifunctionality using high-throughput sequencing and multivariate analysis. Results showed that plant residue cover significantly improved soil nutrients (SOC, TN, TP, TK, AN), enhanced alkaline phosphatase activity, and increased soil multifunctionality compared with bare land. Plant residues also increased bacterial α-diversity and shifted community composition, with elevated relative abundances of Proteobacteria, Bacteroidota, Planctomycetota, Patescibacteria, and key genera (Mycobacterium, Pseudonocardia, Bryobacter, Steroidobacter). NMDS and correlation analysis revealed microbial communities and keystone taxa were closely correlated with soil nutrients and multifunctionality. Overall, plant residues enhance forest soil multifunctionality by improving soil organic matter, optimizing microbial community structure, and stimulating keystone taxa, providing a scientific basis for understanding microbial-driven nutrient cycling and vegetation restoration in degraded saline-alkali soils.

Abstract: Soil samples obtained during an archaeological investigation accompanying renovation works on the village church of Golmsdorf were analyzed for the composition of soil bacterial communities using 16S rRNA sequencing. The bacterial composition of an early middleage settlement pit discovered at depth beneath the floor of the nave proved to be particularly noteworthy in relation to the archaeological context. The composition of DNA coding for 16S rRNA from this settlement pit reflects the incorporation of plant material, most likely mixed with ruminant manure and possibly additional animal remains. Archaeologically, this can be interpreted as evidence for human use of the immediate su-roundings of the pit during its backfilling, together with livestock keeping. This finding clearly demonstrates the ecological “memory” of soil bacteria with respect to the prehistoric past and the human impact on the soil at that time. In contrast, bacterial taxa associated with organic material and livestock are scarcely present—or absent altogether—in soil samples taken immediately beneath the church floor. Instead, these samples show a high proportion of salt-tolerant and halophilic bacteria, which corresponds well with the ob-served high electrical conductivity values of this material. This pattern is interpreted as a consequence of the incorporation of construction material residues into the soil during building activity at the church in the late middleage or 17th century construction phases. The results overall demonstrate that NGS-based analyses of soil bacterial communities can provide valuable insights into human influence on soil material in both historical and prehistoric contexts, offering important additional information for archaeological interpretation.

Abstract: The formation and development of gullies is a pervasive driver of hillslope degradation, yet forecasting where and at what elevation gullies begin remains challenging. This study proposes a morphometric–energetic framework to anticipate gully initiation zones in catchments developed on low-permeability lithologies and limited tectonic control, across contrasting climatic and geomorphic settings. Using GIS analyses and morphometric parameters, some of these derived from hypsometric curves, our objective is to link basin-scale morphology and energy distribution to the propensity for linear incision, thereby defining an altitudinal belt and stream network positions most susceptible to gully initiation. The framework is designed to be quantitative, transferable among landscapes, and parsimonious in data requirements. By prioritizing diagnostics that can be computed from standard topographic datasets, the approach aims to support land-use planning and sediment-risk mitigation, offering a practical pathway for early identification and management of areas vulnerable to gullying.

Abstract: Water erosion is a critical degradation process that reduces fertility and agricultural sustainability, especially in semi-arid regions. The Universal Soil Loss Equation (USLE) allows for the quantification of this phenomenon using factors such as rainfall erosivity (R) and topography (length-slope, LS). In this study, both factors were estimated and analyzed in the Cañitas sub-basin, located in the semi-desert area of the state of Zaca-tecas, Mexico, characterized by irregular precipitation and limited data availability. The objective of this study is to estimate and analyze the R factor and LS factor to evaluate their influence on soil water erosion processes. Records from five meteorological stations (1986–2022) were used, along with the Modified Fournier Index (MFI) and Geographic Information Systems (GIS) tools, generating spatial maps of rainfall erosivity and to-pography. An average R factor of 240.608 MJ∙mm/ha∙h∙year was estimated, consistent with the values obtained using the MFI. The LS factor shows that the northwestern area of the study zone has the most extensive and steepest slopes (up to 20.78). This study provides useful information for understanding soil erosion processes, which can serve as a reference for planning conservation actions and managing watersheds in semi-arid areas with high climatic variability.

Abstract: The long-term relationship between climate change, vegetation change and soil development, is a highly complex process. Findings of multiproxy (sedimentological, MS, geochemical (AAS, XRD), micromorphological, anthracological, phytolith and malacological) studies from a loess/paleosol sequence in northeastern Hungary highlighted the transformation of a reddish-brown fossil soil layer (cambisol) to a podzolic soil with signs of iterative wildfires during the terminal part of MIS3. According to our findings, a Scots pine (Pinus sylvestris) dominated open parkland emerged on the northern slopes during the second phase of MIS3 hosted by a special reddish-brown soil. Then the last phase of MIS3 was marked by the development of spruce (Picea) dominated open parkland. Results further suggest that vegetation change passed a critical threshold leading to an unusually rapid expansion of spruce (within ca. 100 yr). This rapid expansion of spruce, changing the geochemistry of the litter to a more acidic state likely caused the initiation of podzolization and the transformation of the original soil. The opening of MIS2 marked not only intensive dust accumulation but a steady decline of arboreal elements as well leading to the emergence of a cold tundra on top of the podosol with charcoal remains.

Abstract: The dynamics of organic matter, nitrogen status, and biological activity in soils in southern Kazakhstan under various land-use systems were studied. A key feature of the research is the comprehensive comparison of humus status, nitrogen state, and biological activity of virgin and arable dark Kastanozem, Gleyic Calcisol, and Haplic Calcisol, as well as identification of their correlation with signs of functional depletion of organic component. The assessment was conducted using set of agrochemical and biological methods, including determination of humus content, available nitrogen forms, C/N ratio, microbial population, and enzymatic activity. It has been determined that the highest humus content is typical for dark chestnut soils under natural vegetation, while plowing of them is accompanied by decrease in humus content due to increased mineralization processes. Gleyic Calcisol - are characterized by more stable humus state, in some cases with increased organic matter content under arable conditions. Minimum humus values were found in Haplic Calcisol, due to arid conditions and limited supply of organic residues. It is shown that arable soils are characterized by a decreased C/N ratio and increased rates of organic matter transformation. Soil biological activity is linked to mineralization processes, as confirmed by microbial population dynamics and enzymatic activity. Additional assessment using digital tools reveals signs of functional depletion of organic component in agrocenoses. The obtained results indicate the need to consider biological indicators when assessing soil conditions and developing sustainable land management systems in arid climates.

Abstract: This study characterized standard biochars produced at 300, 400, and 500 °C alongside a locally made biochar (LBC, drum kiln method with newly devised method of Bababe) to assess fertilizer value and toxicity against IBI thresholds. Pyrolysis temperature strongly influenced properties: electrical conductivity and salt content increased with tempera-ture (BC300 and BC500 highest; LBC lowest). All standard biochars were highly alkaline (pH 10.26–10.57), while LBC was near-neutral (7.84). Maximum carbon content occurred at 300–400 °C (56.8–56.9 %). At 10 kg ha⁻¹, standard biochars supplied 308–331 kg ha⁻¹ K, with BC400 providing the highest Ca and Mg. LBC had the highest volatile micronu-trients (B, Cu, Fe, Mn), which decreased with rising temperature. It can be particularly well suited to fertilizer coating or blending systems, especially for salt-sensitive soils where application rates are kept low (< 10 t ha⁻¹), thereby limiting agronomic risks such as Mo contaminant loading. Nevertheless, molybdenum levels in all biochars were 5–8 times above IBI safe limits (5–75 mg kg⁻¹), posing toxicity risk at 10 t ha⁻¹ application. Cd was undetectable, reduced Pb by 90 % at 400–500 °C, and kept Ni and Pd within limits. SEM revealed BC400 had optimal honeycomb porosity and homogeneous mineral dis-tribution. BC400 is most suitable for agricultural fertilizer value, BC500 for carbon se-questration, BC300 for potassium supply, and LBC as a low-cost, low-salinity material. However, excessive molybdenum across all biochars relates feedstock composition as the paramount safety factor. The weakness and limitation of this studies lies in the resource constraints from use of one feedstock, absence of direct measurement of surface area and phosphorus, and absence of measurement of biochar stability.