Search Results (225)

This study presents the results of long-term field experiments investigating the effects of subsurface heating and irrigation with discharged warm water (28–35 °C) on the hydrothermal, redox, biological, and salt regimes of Haplic Chernozem (Loamic, Endocalcaric) in the central Forest-Steppe zone of Ukraine. The experiments were conducted under contrasting hydro-meteorological conditions, allowing assessment of thermo-reclamation practices across a wide range of temperature and soil moisture regimes. Subsurface heating increased soil temperature by 7.3–11.1 °C at the depth of heating pipe installation, while the thermal effect gradually decreased with increasing distance from the heat source. Combined heating and irrigation created a more uniform temperature distribution within the root zone, reduced the depth and duration of soil freezing, and improved hydrothermal conditions throughout the growing season. The studied soils maintained predominantly oxidative conditions under all treatments. However, the combined application of heating and irrigation promoted a more homogeneous distribution and seasonal stabilization of soil redox potential throughout the profile. Soil heating also enhanced microbiological activity, thereby increasing cellulolytic activity, particularly during cold and dry periods when soil temperature and moisture limited microbial processes. Irrigation with slightly mineralized warm wastewater did not cause significant overall soil salinization but resulted in the redistribution of calcium and sodium within the soil profile. Subsurface heating intensified the seasonal dynamics of readily soluble salts, promoting their temporary accumulation near the heating pipes, whereas combined heating and irrigation facilitated subsequent leaching of excess salts into deeper horizons. The integrated application of subsurface heating and irrigation produced the highest and most stable perennial grass productivity, increasing biomass yield by 87–163% compared with the control, irrespective of meteorological conditions. These findings demonstrate that the integrated use of industrial waste heat for subsurface heating combined with irrigation represents a promising and environmentally sustainable thermo-reclamation technology capable of improving soil functioning and agricultural productivity, provided that long-term monitoring of soil water–salt regimes is maintained. Full article

As a vital grain production base in China, soil health and crop productivity in Northeast China are critical to national food security. Straw return is a key practice for improving soil fertility and crop yield, yet its effectiveness is subject to complex regulation by regional environmental and management factors. In this study, a meta-analysis was conducted to systematically evaluate the effects of straw return on soil organic carbon (SOC) stocks and maize yield in croplands of Northeast China, and to quantify the moderating roles of climatic conditions, soil properties, fertilization management, and straw return techniques. The results showed that straw return increased topsoil (0–20 cm) SOC stocks by an average of 10.1–18.1%. Among the evaluated categories, comparatively greater mean SOC responses were observed under low temperature (mean annual temperature < 5 °C), low precipitation (annual precipitation of 300–400 mm), low initial SOC concentration (20–30 g kg⁻¹), and Chernozems. For maize yield, comparatively high mean responses were observed under a mean annual temperature of 5–10 °C, annual precipitation of 600–700 mm, moderate initial SOC concentration, and brown soils. Regarding fertilization management, N application at 200–250 kg ha⁻¹ was associated with a comparatively greater mean maize-yield response in the subgroup analysis, whereas SOC responses varied among N, P, and K application rates and fertilization methods. Therefore, the identified environmental and management ranges represent category-specific associations within the available dataset rather than causal or universally applicable optima. In terms of straw return practices, a duration of 5–10 years, incorporation of chopped straw, and full straw return were associated with relatively favorable responses among the evaluated categories. Structural equation modeling revealed that the direct path from SOC stock to maize yield was not significant (path coefficient = 0.07), being masked primarily by the fertilization effect (path coefficient = 0.67) and the carbon saturation mechanism (negative contribution of initial SOC, −0.83). This study uncovers a complex relationship between SOC stocks and crop yield. In practice, agricultural producers should select straw-return methods and amounts according to local climatic and soil conditions, consider chopped-straw incorporation under suitable local conditions, and coordinate straw inputs with soil-test-based, balanced N, P, and K fertilization and field monitoring rather than applying a single universal recommendation. Full article

Heavy metal (HM) contamination near mining operations in Kazakhstan poses a serious threat to the environment. However, data on the state of chernozem soils in this region is limited. This study assessed the bioaccumulation of HMs and translocation within the soil–sunflower (Helianthus annuus L.) system in a southern Calcic Chernozem in the Kostanay region (Northern Kazakhstan), which is located 50 km from the nearest mining facility. The content of seven HMs (Cd, Co, Cr, Cu, Ni, Pb, and Zn) and arsenic (As), as well as five macroelements (K, Ca, S, Mg, and P), was determined in 18 soil samples from the complete soil pedon (0–150 cm) and in eight anatomical parts of six sunflower plants at physiological maturity. Most metals exhibited a deficiency relative to upper continental crustal Clarke values (Clarke of Concentration (CC) < 1 for Cr, Cu, Ni, Pb, and Zn), with a moderate lithogenic anomaly for Cd (CC = 1.65–3.57) and a localized Co anomaly in the Bk horizon (56.26 mg kg⁻¹), indicating no pronounced HM contamination at the investigated agricultural site. Metal distribution exhibited strong organ specificity in sunflower plants. Cd, Cu, and Zn accumulated preferentially in the leaves, whereas Ni and Co were more concentrated in the seeds and stems, respectively. Only cadmium exceeded the threshold values for both BCF > 1 (1.01) and TF > 1 (1.47), confirming the status of sunflower as a cadmium accumulator. These results provide a preliminary reference dataset of the organ-specific distribution of heavy metals in H. annuus L. plants, which can serve as a local baseline for sunflower growth in uncontaminated southern Chernozems. This information can contribute to future environmental monitoring purposes in the region, acting as an exploratory benchmark. Full article

This study evaluated the rehabilitation of salt-affected ordinary chernozem in Ukraine using a combination of deep plowing (75 cm) and green manure application (100 t/ha), a highly effective and sustainable technique for reclaiming salt-affected ordinary chernozem (a process termed self-amelioration). Calcium salts were mobilized from deeper soil layers to the surface using the integrated strategy, a process known as “self-amelioration”. This increased the humus horizon from 50 to 75 cm and significantly improved water-related physical characteristics and soil structure. The carbonate concentration increased to 8.7%, while the soil bulk density (SBD) dropped from 1.2 to 0.98 g/cm³. Higher calcium levels (8.3–8.7%) and the improved calcium saturation of the soil-absorbing complex decreased alkalization, increasing the soil’s buffer capacity. “The percentages of absorbed sodium, potassium, and other exchangeable cations decreased from 6.6–7.0% to 4.3–5.2% of all exchangeable cations”. In addition to increasing soil organic carbon (SOC) and total NPK levels, the addition of green manure significantly reduced the amount of salt in the soil. However, effectiveness depends on local conditions, such as soil salinity, precipitation, and temperature, with the greatest soil organic carbon improvements observed in moderately saline, dry environments. Crop yields increased by 21–38% under this treatment. The results suggest that integrating deep plowing with green manure use is an effective and sustainable approach for restoring salt-affected soils. Full article

Modeling crop development under different agrotechnologies is important not only for assessing the factors that affect their yields but also because of the role of vegetation in regulation of the hydrology regime. For this reason, interest in the plant module in the semi-distributed hydrological model SWAT is increasing. The model has to be supplied with a lot of information for running and testing, which can be achieved with ground-based, statistical and satellite data. The aim of the study is to determine the accuracy of the SWAT model to predict crop development by using ground-based and satellite data for LAI in the case of a 5-year field experiment. Two staple crops in rotation were monitored—winter wheat and maize—under different erosion control technologies (up-and-down conventional tillage, conventional contour tillage, and minimum contour tillage with inclusion of cover crop before maize) on sloping terrain on moderately eroded Epicalcic Chernozem in the region of Ruse, north Bulgaria. The remote sensing data from the Copernicus Sentinel-2 mission were used for estimation of LAI of both crops and verified against ground-based data in two ways—via a custom LAI script available through the Sentinel Hub cloud platform and as input to a machine learning quantile regression forests (QRF) model. The calibrated satellite-derived LAI, ground-based soil moisture and yields data were used to calibrate several SWAT model parameters (EPCO, ESCO, CN2, LAImax, HU, HI) and assess the model performance regarding these variables. Although a good temporal fit of the SWAT-modeled LAI data with the satellite data was achieved, the accuracy of predicted LAI is moderately high only in the last two years of the rotation (R² = 60.4%). The accuracy of calibrated yields (R² = 55.5%) is acceptable in four of the years. On average for the period, the applied erosion control agrotechnologies did not cause significantly different yields, but they are 14% higher compared to the up-and-down conventional tillage. The most sensitive SWAT parameters accounting for this effect are EPCO and ESCO. Full article

This study characterizes AP-20-A, a lytic podovirus infecting Sinorhizobium meliloti, isolated from agricultural chernozem. Its 49.4 kbp genome shows negligible intergenomic similarity with known rhizobiophages (<2%). Core structural proteins—the major capsid protein (MCP) and terminase large subunit (TerL)—show closest homology to podoviruses infecting Paenibacillus, rather than to alphaproteobacterial viruses, suggesting cross-phylum horizontal gene transfer. This exchange is ecologically plausible, as Paenibacillus and Sinorhizobium co-exist in the rhizosphere. Over 63% of predicted proteins are functionally uncharacterized, with structural homologs detected in bacteria, archaea, and eukaryotes. We report the first identification in a rhizobiophage of a Tad2-like domain, predicted to block the bacterial Thoeris type II anti-phage defense. AP-20-A infected 56% of native S. meliloti strains; agrocenose isolates showed higher resistance than phytocenose isolates, evidence of local co-evolution. Among susceptible strains, 60% entered putative pseudolysogeny (with one strain exhibiting growth stimulation), whereas a symbiotically elite inoculant strain was completely lysed within hours. Some host strains carry additional AbiE systems; whether these independent defense–counterdefense layers interact during infection remains unknown. We conclude that resident phages represent a selective force that can disrupt inoculant establishment, underscoring the need to integrate soil virome assessment into agricultural microbiome management. Full article

In this work, we present the Chernozem Soil Aggregates Micromorphometrical Parameters Dataset for specific areas located in the Central Russian Upland that can be utilized for the development of a digital twin of Chernozem. The present dataset represents a collection of soil aggregates’ micromorphometrical parameters (aggregate total area, minimal and maximal Feret diameters, form factor, elongation, unevenness, orientation) obtained through segmentation of soil thin sections’ digital images. Also, the dataset represents the data on physical and chemical properties of the studied soils (organic carbon content, inorganic carbon content, clay, silt, and sand fractions content, mean weight diameter of aggregates). Soil excavation and sampling were conducted in two stages: 24–25 April 2023 and 4 June 2024. Soil sampling sites were selected to provide a comparison of virgin Chernozem soils with plowed, non-eroded, and severely eroded ones. Soil sections were excavated at 9 key points. Laboratory analysis yielded 60 sets of data on physical and chemical properties and over 51,000 micromorphometric values for soil aggregates. Full article

Humus substances are an important part of stable soil organic matter, which is also influenced by the soil tillage system, particularly indirectly through the mechanisms of stabilisation. This study evaluated relationships within the humus substances–cations–soil texture system and differences between invasive and non-invasive tillage systems in four soils. The influence of exchangeable cations (K⁺, Na⁺, Ca²⁺, Mg²⁺, Fe³⁺, Al³⁺) and particle size distribution (sand, silt, clay) on quantity (humic and fulvic acids) and quality (ratio of HA/FA, degree of humification, colour coefficients) of humus substances was studied. In reduced tillage, the humus substances interacted mainly with iron and aluminium. Higher humus substance contents were associated with higher K⁺; the influence of Ca²⁺ was greater in coarse-grain soils (Haplic Chernozem, Eutric Regosol); and Al³⁺ was positively correlated with humic acids and negatively with fulvic acids. The statistical associations indicate that in conventional tillage, humus substances interacted mainly with Ca²⁺. Higher humic acid contents indicate an association pattern with higher Na⁺ contents; the relationship of Ca²⁺ appears more pronounced in fine-grained soils (Mollic Fluvisol, Haplic Luvisol); and Al³⁺ was positively correlated with fulvic acids and negatively with humic acids. The soil tillage system influenced the humus substances indirectly by a combination of factors—cation composition and soil texture in different ways. In reduced tillage, clay and silt were statistically associated with iron and aluminium; in conventional tillage, there were two branches: clay with divalent cations and silt with trivalent cations. The soil tillage system can modify the impact of carbonates on humus substances and thus indirectly change the character of transformation processes in the soil. Depth is very important in evaluating the influence of the soil tillage system. Full article

This study presents a dataset of meteorological and soil-hydrological instrumental observations collected at three agrometeorological stations in the East Kazakhstan Region during the growing seasons of 2022–2025. The dataset includes time series from automatic weather stations: WS “OCES-1” (Solnechnoe village) provides hourly data over four years (2022–2025; 14,614 records; 65 variables), while WS “OCES-2” (Lugovoe village; 203,279 records) and WS “Altyn Kazan” (Sulusary village; 207,115 records) provide minute-resolution data for 2025 (49 variables each). Measured parameters at 200 cm height include air temperature and humidity, atmospheric pressure, precipitation, wind speed and direction; soil measurements down to 100 cm depth include temperature and moisture. Also, field-based express measurements of volumetric soil moisture within a 1 m profile (every 10 cm) were collected during three campaigns (May–August 2025), resulting in a total of 253 measurements. The stations are located across steppe and forest-steppe landscapes of the transboundary Altai–Sayan mountain region on active agricultural lands under diverse soil–climatic conditions. Climate types correspond to Dfb and Dfa per the Köppen–Geiger classification. Soils are classified under WRB as Chernozems and Calcic Chernozems. The dataset is published in CSV format on Zenodo under a CC-BY 4.0 license. Full article

Microplastic pollution threatens soil health by disrupting chemical and microbial balances and impairing nutrient cycling, with effects that vary depending on soil properties. The objective of this study is to determine the effects of contamination with three types of microplastics (<5 mm)—polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET)—on the microbiological and chemical parameters of four soil types in Bulgaria: Calcic Chernozem, Vertisol, Luvisol, and Fluvisol. A controlled 180-day laboratory incubation experiment was performed, where each soil type was contaminated with microplastics at three concentrations to monitor changes in key microbiological and chemical properties. It was established that microplastics contamination suppressed abundance of key microbial groups and limited nutrient availability, inducing a state of biological and chemical imbalance in the soil. PET exerted the strongest impact on soil chemical properties, with the agrochemical properties of Fluvisol being the most sensitive to MP contamination. PE and PET had the greatest influence on microbial communities, with Vertisol and Luvisol being the most affected in this regard. PP contamination altered key metabolic processes, with the specific impact being highly dependent on soil type and most pronounced in Chernozem. Furthermore, the concentration influenced the measured parameters, with the effects varying depending on the soil type and the microplastic type. Among the factors influencing soil responses to microplastic contamination, soil type appears to be the most decisive, followed by the type of microplastic. Full article

The increase in CO₂ concentration in the atmosphere can be attributed to various anthropogenic activities. Soils play a significant role in climate regulation, particularly through the storage of atmospheric carbon in soil organic matter. The main aim of the study was to examine the effects of site conditions on soil CO₂ flux in middle-aged stands of pedunculate oak (Quercus robur L.). A three-year study was conducted in three middle-aged stands within different subtypes of Chernozem. One of these stands is a windbreak (RŠ), while the other two stands (VN and DE) belong to larger forest complexes. Air samples were collected using the closed-chamber technique and analyzed using gas chromatography. The linear mixed-effects model (LMM) revealed that soil temperature, soil moisture, and location had significant effects on soil CO₂ flux (p < 0.05), whereas the effect of year was not significant (p > 0.05). The results showed that there was a higher temperature sensitivity of soil respiration (Q₁₀) in the windbreak (RŠ) compared to the other two stands (VN and DE). The mean annual carbon loss through soil respiration for all stands was assessed to be approximately 3.24 ± 0.12 t C ha⁻¹ yr⁻¹. These findings suggest that lower soil CO₂ flux in stands growing under optimal site conditions may indicate a more favorable carbon balance compared to stands growing outside their ecological optimum. Full article

Inland water management is increasingly important under climate change due to the need for landscape-scale water retention, but in situ studies are limited by fluctuating, shallow, and intermittent water cover. This study simulated prolonged waterlogging under controlled laboratory conditions. Four agricultural soils (Calcisol, Arenosol, Chernozem, and Solonetz) were flooded for 40 days using identical 1:5 soil-to-water ratios at two temperature regimes, at 4 and 22 °C. Given that periodic water cover may conflict with agricultural production, particular attention was paid to crop-relevant indicators, including pH, water-soluble salts, and N, P, K. The laboratory simulation revealed significant differences among soil types and between temperature treatments. Elevated Mg concentrations limited the irrigation suitability of leachate derived from Calcisol, with Mg% values ranging from 57 to 64%, exceeding the 50% guideline threshold. Soil buffering capacity controlled phosphorus and potassium dynamics, resulting in stable or slightly increasing AL-soluble nutrient levels, except in low-buffering sandy soils where up to 3–4-fold variability was observed. Reductive conditions developed early in the Calcisol samples, supported by dissolved oxygen saturation values below 20% during the first days of the experiment. Oxygen saturation increased later, only exceeding 60% twice in the cooled Calcisol treatment, while nitrate–ammonium dynamics reflected changing redox conditions. Temperature significantly affected solubility and nutrient mobility, partly through its influence on microbial activity. These findings improve our understanding of inland water–soil interactions and support the development of sustainable, water-retentive land management strategies. Full article

The increasing use of silver nanoparticles (AgNPs) as nanoagrochemicals raises important environmental and toxicological considerations of their usage. AgNPs influence soil microbiome functioning, which regulates essential nutrient availability. However, their effects on key chemical soil health indicators remain unclear, with existing studies limited to concentrations ≥10-fold above predicted environmental levels. The aim of the work was to evaluate the effect of AgNPs at a realistic concentration of 10 μg/kg on the principal chemical soil health indicators, including acidity, redox potential, electrical conductivity, contents of NPK, and soil organic carbon (SOC). In addition, dissolved organic carbon and nitrogen (DOC and DON) and water-extractable elements (Al, Ca, Fe, K, Mg, Na, P, S, and Si) were also examined. The laboratory experiment was carried out for 3 months on Retisol, Chernozem, and Solonetz. AgNPs stabilised with carboxymethylcellulose (AgNP-CMC) or polyvinylpyrrolidone (AgNP-PVP) were used. AgNP-induced changes exhibited non-monotonic patterns, peaking at 2–3 months of incubation. A statistically significant effect observed across all soils following AgNPs application included only increased water-extractable Fe. In addition, AgNPs increased nitrate content 1.1–1.4-fold in Retisol and Chernozem, while available phosphorus increased 1.4-fold in Solonetz. However, changes were transient, indicating no pronounced long-term impact on soil properties. Partial Least Square (PLS) analysis revealed that chemical soil health indicators and water-extractable elements do not reliably discriminate between control soils and soils amended with AgNPs. Although our study shows that AgNPs had neither markedly negative nor positive effects on chemical soil health indicators or water-extractable element contents, future research should prioritise field trials. Model experiments under optimised microbial activity conditions limit direct extrapolation to field scenarios. Full article

Organic farming can increase the sustainability of farming and support biodiversity and soil health. The aim of this work was to conduct a meta-analysis to evaluate the effects of organic farming on selected soil biotic and abiotic properties in Central Europe and to quantify the possible influences of sampling characteristics, soil type and crop husbandry on these effects. Overall, we integrated data from 59 peer-reviewed studies into our analysis, including 1365 pairwise comparisons (log-response ratios; LRR) that covered carbon and nutrient contents, soil organic matter (SOM), soil microbiology and physicochemical properties. Organic farming increased the levels of microbial activity and this effect decreased with soil depth, whereas generally positive but less robust effects on microbial biomass quantity and soil pH were observed across analyses. In addition, a decrease in cation exchange capacity was observed, but this result should be interpreted with caution due to the limited number of studies. The LRR for the bulk density was affected by the sampling season, while soil type influenced the LRR for the nitrogen contents (with negative values for Chernozems). Tillage modified the LRR for pH and bulk density, as did animal fertilizer for microbial biomass quantity. These differences can be attributed to the differences in pairwise comparisons in these moderators rather than to the use of different farming systems themselves. The lack of effects of organic farming for some categories (SOM, carbon, phosphorus, other macroelements and microbial biomass quality) could be attributed to opposing input–decomposition processes, high variability in site conditions across studies or large scatter in the data. Our results highlight the importance of considering soil characteristics and moderators related to crop husbandry when evaluating the effects of farming systems on soil health. Full article

Cropping systems and agronomic practices play a critical role in regulating soil organic matter dynamics and carbon dioxide (CO₂) emissions, which are key components of the global carbon cycle and climate change mitigation. However, the combined effects of tillage practices and seasonal climatic variability on CO₂ fluxes in chernozem soils (chernozems, WRB classification; highly fertile, humus-rich soils typical of steppe regions) of Northern Kazakhstan remain insufficiently understood. The aim of this study was to quantify soil CO₂ emissions under conventional tillage, no-till, and bare fallow systems during spring wheat cultivation on ordinary chernozems. Field experiments were conducted between 2023 and 2025 in the Kostanay Region (Kazakhstan). Soil CO₂ fluxes were measured using a chamber-based method, while soil temperature, moisture, and microbial community structure were monitored simultaneously. The results revealed pronounced seasonal and interannual variability in CO₂ emissions, ranging from 2 to 27 g CO₂·m⁻²·day⁻¹. Conventional tillage resulted in higher peak emissions due to increased soil aeration and accelerated organic matter mineralization, whereas no-till systems exhibited a more stable seasonal pattern and lower temperature sensitivity of soil respiration (Q₁₀ = 2.40 for no-till and 3.25 for conventional tillage). The application of machine learning techniques (Random Forest) significantly improved the prediction accuracy of CO₂ fluxes (R² = 0.67; RMSE = 3.37 g CO₂·m⁻²·day⁻¹) compared to linear models. These findings provide a scientific basis for the development of climate-smart agricultural practices aimed at improving carbon management in semi-arid steppe agroecosystems. Full article