The legend of the Soil Map of the RSFSR at a scale of 1 : 2.5 million (SMRF) presents five units of meadow soils. Their small areas are located in many regions of Russia. The search for correlations between the meadow soils of the original legend of the SMRF and soils in the Classification System of Russian Soils (CSRS) was carried out on the basis of a comparative analysis of soil-forming factors, morphological and analytical characteristics of meadow soil profiles in publications, where soil pit locations coincide with their areas on the map. According to publications, the meadow differentiated soils of the Khanka-Ussuri and Middle-Amur Plains correspond to five different soils that differ in soil formation conditions, properties and classification position (Ivanov, 1976). Thus, meadow-brown bleached (meadow podbels podzolyzed according to the classification of soils of the USSR) and meadow-gley bleached soils of the Khanka-Ussuri Plain correspond in the CSRS to dark-humus gleyic cryometamorphosed podbels and dark-humus humus-cryometamorphosed gley podbels. Meadow-gley podzolyzed and meadow-gley solodiс soils, formed under hydromorphic conditions on the young terraces of the Khanka-Ussuri Plain, correlate in the CSRS with humus-soddy-gley podzolyzed and dark-humus-gley solodiс carbonate-segregationary soils. Meadow-brown gley-bleached soils (meadow podzolyzed-gley soils according to the USSR soil classification system, 1977) of the Middle-Amur Plain, proposed in the CSRS (2008) as analogues of dark-humus-gley podzolyzed soils, can be defined as mucky-humus-gley podzolyzed dark-tonguic soils based on a combination of diagnostic properties. Meadow undifferentiated soils of the SMRF legend belong to two orders of the CSRS: organo-accumulative and gley soils. Their humus horizons are diverse: dark-humus, mucky-dark-humus (AUh), soddy (AY), mucky-humus (AH). Soils of large alases of Yakutia are characterized by unique carbonate peat-dark-humus upper horizons, they have also gleyic and solonetzic features, sometimes salinity in the profile.

The soils on the eluvium of dense rocks of different ages, genesis and composition were studied in Transbaikalia. The ecological niches of the soils and their classification position were determined. Under humid conditions, in the permafrost zone under the larch taiga on the rubble-loamy derivatives of metamorphic effusive rocks, limestones, shales, and sandstones of the Cambrian, the profile of cryometamorphic coarse-humus podzolized soils are formed with a thickness of more than 1 m. The main pedogenic processes are claying, aggregation, coarse humus forming, podzolization and illimerization. Under the conditions of a semi-arid climate, deep and prolonged freezing, within the belt of dry pine forests, on the products of weathering of biotite granites, granodiorites, syenites of the early Paleozoic intrusions of the Vitimkan complex, the soil profile has a thickness of less than 0.2 m. The processes of sandification, siltization, inhibited humification with the formation of a brownish-gray horizon AY are developed in the soil. These factors and processes lead to the gray-humus lithozems forming. Under the arid climate conditions, deep and prolonged freezing within the cryoarid steppe belt, cryohumus lithozems are formed on the products of weathering of trachybasalts, subalkaline basalts and plagiobasalts of the Jurassic period, with the processes of siltization, sandification, denudation, humification, and the formation of a chestnut horizon AK of the reddish tone.

Agrochemical surveys of arable soils are laborious, costly and time-consuming. The introduction of modern remote sensing and digital technologies has great potential to overcome these disadvantages, but requires additional scientific research. The article presents the results of a comparison of the efficiency of using different types of remote sensing data for spatial modeling the main agrochemical properties of soils by the example of a test site in the Tver region. The spectral reflectance of the soil surface was determined in the field, its simultaneous measurement by an unmanned aerial vehicle (UAV) with a standard camera, and additionally the test plot was analyzed on Sentinel-2 satellite images. Regression analysis showed that the most accurate predictive models of soil agrochemical properties can be obtained from field spectrometry, lower quality models are obtained from UAV data, and the lowest quality models are obtained from satellite data. The main reason for this seems to be the spatial variation of soil agrochemical parameters and the generalized representation of their open surface on UAV data and satellite images.

Studies of soils and soil cover were conducted in the territory of mining complexes for the extraction of granite, sand and sand-gravel mixture, clay and peat mining. The development of mineral deposits leads to cardinal changes in soils and soil cover (SC), to the appearance of new soil varieties and soil cover structures (SCS) that have no analogues in natural landscapes. The areas of anthropogenically transformed soils, non-soil formations and newly formed soil combinations in such areas often have a geometrically regular shape. In places where natural SC has been completely destroyed (quarry excavation), a water body or new non-contrasting SCS are formed, which are closest to natural tachets and whose components are underdeveloped soils. Along the access roads to the quarries, depending on the extracted minerals, different forms of new anthropogenic SCS are formed. The access road to the sand pit does not have high shoulders fixed by vegetation cover, which allows the formation of a two-way relationship, manifested in the transfer of sandy material from the road surface to the shoulders (stratified soils) and in the opposite direction. Peat mining is characterized by regular-cellular rectangular forms of soil combinations due to peat extraction technology. On the territory of the clay quarry, SCS close to natural mosaics are formed. The identified SCS formed on the territory of mining-industrial complexes in most cases have no analogues among natural ones, and for the purposes of mapping these territories, as well as assessing changes in the ecological functions of soils of anthropogenically transformed territories, further development of the typology of anthropogenic SCS is required.

Agriculture in the Tver Region, and the Kalininsky Municipal District, in particular, have suffered greatly from the withdrawal of lands from agriculture use and depopulation. The sown area has decreased by 8 times from the late 1960s to 2023. In this regard, the Government of the Russian Federation adopted the “State Program for the Effective Involvement of Agricultural Lands in Circulation...”, within the framework of which it is necessary to assess the area and quality of fallow lands. This paper assesses the quality of agricultural land in the Kalinin District based on both large-scale land management materials from the Soviet period and using digital soil mapping methods. The compiled map of agroecological land groups made it possible to assess the quality of the municipal district lands and determine the feasibility of crop growing on them. It was determined that the weakly semihydromorphic-lithogenic, lithogenic land and upland groups have the highest agroecological value. The total area of deposits within these groups is 33.5 thousand ha or slightly more than 15% of the total area of agricultural land in the Kalininsky District. Putting hydromorphic lands into agricultural use in the Region is not advisable. To assess the role of landscape and positional factors in land abandonment, an inventory of the areas and condition of agricultural lands was conducted, and the distances from important infrastructure and natural objects were calculated. It was found that the greatest impact on the withdrawal of follow lands from agriculture use was the distance from hard-surface roads, and the landscape factor took the second place, and it is almost 3 times less significant according to the F-criterion of discriminant model. The remaining positional factors (distances from wetlands and watercourses) turned out to be secondary.

The aim of the present research was to study the actual, exchangeable and hydrolytic acidity of the soils of agricultural lands of the Donetsk People's Republic. The model sites were selected on lands of various degradation degrees, laid in the eastern and western parts of the Shakhtyorsk district of the Donetsk People's Republic and covered by low- and medium-humus chernozems with low and medium erosion degrees. The site with steppe vegetation (medium humus chernozem) was chosen as the control one. When studying the actual acidity index in the soils of agrocenoses of model sites, a variation in the pH values from medium acidic to medium alkaline was established. The studying of exchangeable acidity fluctuations in various sites showed a significant excess of indicators in the slope areas under wheat (3.6– 6.4 times) compared to the values of plakor soil. To the least extent, degradation processes affected the values of the exchangeable acidity of fallow sites, as well as under vegetable crops, where the excess of indicators ranged from 1.1 to 1.5 times. Hydrolytic acidity values in the areas under crops were significantly higher than hydrolytic acidity values in the control site (4–10 times). The values of hydrolytic acidity in the soils of agrocenoses under tomatoes, fallow, onions (subsurface horizon) were not reliably distinguished from the control ones, which is a positive factor for the successful cultivation of a wide range of crops.

Microbial biomass carbon (C_mic) is a biologically active pool of soil organic matter and a sensitive indicator that responds to changes in land use much earlier than total organic carbon content and other pools within it. The luminescent microscopy method allows assessing not only the total content of C_mic but also the structure of microbial biomass: the number of spores and the length of fungal mycelium, as well as the number of bacterial cells and actinomycete hyphae. The aim of the study was to determine the structure of the microbial carbon pool in the profiles of chernozem and sod-podzolic soils depending on the type of agricultural use (hayfield, abandoned land, arable land, pasture) using the luminescent microscopy method. The microbial carbon pool in the surface layer of sod-podzolic soil ranged from 260 to 450 µg/g soil depending on the type of land use, in chernozem – 450 µg/g for abandoned land and 190 µg/g for arable land. Down to the depth of 30 cm, C_mic in chernozem under abandoned land was 1.5–3 times higher compared to arable land. In deeper horizons, differences between various land use types became less pronounced but persisted for a number of microbiological indicators. The fungal component, predominantly represented by mycelium, completely dominated (97–99%) the microbial carbon pool in both soils. The length of fungal mycelium in sod-podzolic soil and chernozem decreased by an order of magnitude with depth from hundreds of m/g to tens of m/g soil. Most indicators of the structure of the microbial carbon pool (fungal abundance, mycelium length of fungi and actinomycetes, prokaryotic biomass) were higher in chernozem under abandoned land compared to arable land; however, these patterns were not observed for sod-podzolic soil. Prokaryotic biomass and share, as well as mycelium length, were noted as the only indicators of the microbial carbon pool structure determined by the luminescent microscopy method that were associated with different types of land use for both considered soils. Very high fungi/bacteria ratios are likely due to the underestimation of bacterial cell biomass by the method used. Despite the identified limitations of the method, luminescent microscopy can be used as a supplement to more accurate methods for assessing the microbial carbon pool, allowing the determination of the size and structure of fungal biomass in soils of different types of agricultural land use.

The aim of this study was to assess the change in enzyme activity (catalase, urease, and invertase) in soddy-eluvozem and dark humus soil under simulated contamination with Cd, Cu, Zn, and Pb. Enzyme activity serves as one of the indicators of metal toxicity in soils. Appropriate levels of pollution were established in preserved media using solutions of acetic acid salts of Cd, Cu, Zn, and Pb with concentrations of 0 (control), 2.5, 5, 10, 25, 50, 100, 250, 500, 1000, and 1500 mg/kg. Based on genetic properties, dark humus soils exhibit greater resistance to pollutants compared to soddy-eluvozem. The average organic matter content in dark humus soil reaches 7.0%, with nearly neutral pH, while the granulometric composition varies from heavy loamy to medium clayey, and sod-eluvozem is characterized by light loamy texture, acidity, and a lower humus content. The assessment of the critical pollution threshold, indicated by the activity levels of catalase, urease, and invertase, demonstrates the enhanced stability of dark humus soil. Among the indicators studied, the urease activity emerged as the most sensitive indicator of heavy metal pollution in both types of soil; it decreased in sod-eluvozem with the introduction of Cd and Cu starting at 100 mg/kg and higher, while in dark humus soil, the decline occurred with the introduction of Cd starting at 100 mg/kg and higher and Cu starting at 1000 mg/kg and higher. The negative impact of Pb was observed only in dark humus soil, where urease activity decreased under pollution levels of 250 mg/kg and greater. The enzyme activity remained consistent when the soil was contaminated with Zn, with a decrease in the indicator observed only at elevated doses (1500 mg/kg). A notable feature of catalase and invertase activity in both soils was their increase under higher levels of contamination, which is presumably due to a decrease in microbial activity. When analyzing the comparative toxicity of metals, it was found that Cu, despite its biogenic significance, exhibited a greater ecotoxicological effect when compared to Zn and Cd; the introduction of Pb had the minimal effect on enzyme activity.

Peat is a key component of substrates in greenhouse cultivation, and enhancing its properties through the addition of organic components is a common practice. This study compares highly porous biochars derived from pine nut shells, produced under slow pyrolysis and high-temperature conditions with subsequent activation, as additives partially replacing peat in substrates. The carbon content and degree of organic matter decomposition were determined in peat mixtures with biochars of different concentrations (10% and 20% by volume) and forms (ground and unground). It was found that 20% ground biochar leads to the greatest increase in the C/N ratio, typically observed in undrained or deeper peat layers, indicating a higher intensity of humification that optimally stimulates microbial activity, yet suggesting a possible reduction in nitrogen availability for plants. The concentrations of macro- and micronutrients in mixed peat substrates were determined. The results showed that the addition of ground activated biochar (10–20% by volume) significantly increases the concentration of key macronutrients in the substrate, such as phosphorus, potassium, and calcium by factors of 4.9–5.9, 3.3–3.9, and 1.7–1.8, respectively, demonstrating the promising potential of activated biochar for improving the nutrient properties of peat substrates. Particular attention was paid to analyzing the impact of biochars on the content of heavy metals and non-metals, confirming their potential effectiveness and environmental safety. The data obtained suggest the possibility of partially replacing peat with highly porous biochars, especially in ground form, which may contribute to increased crop yields and enhanced plant resistance to stress conditions.

The problems of environmental regulation of oil contaminants in soils are considered. A methodology for developing soil quality standards for the content of contaminants is presented. The analysis of the regulatory framework for environmental regulation of contaminants in soils has been carried out. It is shown that there is a lack of methodological documents for meeting the requirements regarding land reclamation. A model for setting soil quality standards in terms of the content of contaminants is proposed using the example of oil pollution. The justification for the establishment of soil quality standards is based on the ecological functions performed by the soil. Based on the grouping of soil horizons in the framework of ongoing scientific research, the values of quality standards are differentiated for soil horizons of the selected types and subtypes of soils by groups. The environmental standards of soil quality for the content of petroleum products are parameters set at the maximum permissible level of values obtained as a result of laboratory tests – absolute normative values, taking into account the natural background ones, which refers to the soil condition determined by the natural features of the territories and caused by natural environmental processes. To determine the soil quality standards for the content of pollutants, simulation modeling is proposed using various indicators of harmfulness, reflecting 1) the probability of migration of pollutants, for example, oil and products of its transformation from soil to adjacent media (components of the natural environment) into surface and groundwater (migratory aquatic hazard index); 2) the conditions of biota functioning (bioindicators), reflecting the ability of the soil to perform the ecological functions of soils. The indicators for assessing the ecological condition of oil-affected soils are soil characteristics that reflect the ability of the soil to perform ecological functions. Acceptable values of these indicators are established when studying the relationship “state – effect”, “dose – effect”, and assessing the intake of oil or petroleum product components into adjacent environments in quantities that cause toxic effects on biota. The threshold value for studying the relationship “state – impact”, “dose – effect” is the point of qualitative changes in the state of soils and adjacent environment on the graph.