Том 52, № 7 (2019)

The climate of the 1950s–1990s in the center of the Russian Plain was characterized by the alternation of cool–wet and warm–dry periods, which is confirmed by hydrothermal coefficients. The studies in the south of the forest-steppe of the Central Russian Upland (Belgorod oblast) based on the geoinformation analysis of different-time soil maps have revealed regular changes in the boundaries of soil areas of automorphic chernozems (Chernozems) related to these intra-century climatic cycles. The transformed chernozems area was 125 790 ha (38.5%). In general, 61.5% (328 885 ha) of soil areas in the studied region remained unchanged. The response of the soil cover was indicated by behavior of carbonates and leaching. It has been revealed that with increase of hydrothermal coefficient by more than 0.2, the effervescence line in chernozems is oscillating, which results in a change in the taxonomic position of soils at the subtype level.

The descriptive ability of two integral biotic indices obtained from laboratory experimental data focused on estimating the effects of humic products (HPs) on the microbiota under conditions of copper contamination in a model soil substrate is evaluated. The “Standard Soil” prepared from sand, kaolin, and peat (ISO 11268-1) as recommended for the assessment of biological effects was used. To summarize the results of ecotoxicological studies of Cu-polluted samples (660 mg Cu/kg) and to provide the integral estimation of HPs impact on the microbiota, two statistical models were used: the Harrington’s desirability function D and the integrated parameter of the soil microbial system sustainability G (ratio of biodiversity to instability) using multisubstrate testing. The indices obtained based on two sets of multidimensional data were compared in their descriptive ability when estimating the detoxifying efficiency of HPs. It was found that HPs mainly stimulate multispecies bacterial complexes, while the test cultures representing higher plants and algae are less sensitive to their impact. Three of the five studied HPs showed a pronounced detoxifying effect and improved the state of the studied system. Both integral biotic indices—the generalized Harrington desirability function D and the General sustainability parameter of the system G—demonstrated a similar effect vector. For the purpose of environmental regulation, the use of the integrated approach based on a generalized desirability function could be recommended due to its higher completeness and reliability of the system of biotic indicators.

A comparative assessment of the carbon stock in loamy soils (Albic Retisols) of coniferous–broadleaved forests on the Moskvoretsko-Oksky Plain and sandy soils (Albic Podzols) in the Bryansk region is given. The carbon accumulation in soils is related to the texture of their mineral horizons and biotic factors, such as the quality of litter and activity of earthworms. The forests on sandy soils were characterized by a high carbon stock in the plant litter, which is explained by the low biomass of earthworms. The carbon content was significantly higher in the mineral horizons of loamy soils owing to high share of fine particles. The carbon stock in the litter and mineral horizons of loamy and sandy soils turned out to be comparable, except for the sandy soils of mixed forests due to higher clay content. In the course of succession of the coniferous-deciduous forests on the loamy soil, the carbon accumulation in the litter was high only at the late stage due to the high input of spruce needles. The carbon stock in the humus horizons of the loamy soils varied due to changes in their density, which was regulated by earthworms. When comparing different succession stages/types of the forests on sandy soils, it was found that the carbon stock in the litter of the pine forests at the early stage of succession was significantly higher than that of the mixed and broadleaved forests. Trends of carbon accumulation in the mineral horizons of sandy soils were mainly explained by their thickness, which was related to the amount of percolating precipitation regulated by woody plants.

Knowledge on P release characteristics and availability of different forms of soil phosphorus can be useful for crop production. Kinetics of P release and distribution of inorganic P from in calcareous soils at summit, shoulder, back slope, foot slope and toe slope of three soil toposequences (Fars province southern Iran) were determined and the relationship between P release and soil properties with phosphorus form was investigated. The kinetics of P release in the soils was determined by successive extraction with 0.01 M CaCl₂ over a period of 72 hours. The kinetics of P release followed Elovich, power function and first order kinetic models. The results demonstrated that the pattern of P desorption was similar in all topographic units of the three regions at all times. The highest amount of P release was observed in the lower part of the slope specially in Eghlid and Abadeh (xeric and aridic regimes). Generally, the average content of cumulative phosphorus release and most forms of phosphorous and physical and chemical characteristics in Eghlid soils were greater than other studied soils. Different P forms were determined by sequential extraction; the fractionated inorganic P forms namely apatite type and dicalcium phosphate possessed the highest and the lowest amounts of P reserve in the soils, respectively. As a result, P release and various P forms distribution within the soil profiles along toposequences varied in different topographic units and increased down the slope with an irregular trend. Due to such variability, P fertilizers are recommended by consideration of the physiographic units.

The aim of this work is to determine viscoelastic behavior parameters of soil pastes and micromonoliths of natric and vertic horizons in the profile of Vertic Solonetz from the Kamennaya Steppe (Voronezh oblast, Russia) and to use rheological properties to explain the formation of three irregular alteration structures with different wavelengths and deformation patterns of the soil mass. The rheological parameters of six soil horizons were determined by the amplitude sweep tests using an MCR-302 rheometer with parallel plates. The general features of viscoelastic behavior of soil pastes and micromonoliths, the correlation between the storage modulus G'_LVR in the linear range of viscoelastic behavior of pastes and micromonoliths with their moisture, the distribution of rheological properties in the soil profile, and the relationship between the content of exchangeable sodium and the integral I_z used for the evaluation of structural stiffness are discussed. Rheological properties of Vertic Solonetz are compared with published data on Vertisols from Brazil, Russia, and USA and on saline clay alluvial soil from Spain. A hypothesis of formation of the profile of Vertic Solonetz with the gilgai microtopography as dependent on the rheological characteristics of the viscoelastic behavior of the studied soil horizons is proposed.

A hypothesis about an increase in the area of waterlogged soils on arable lands of Tambov oblast in the recent decades was tested by the methods of retrospective monitoring of the soil and land cover. The period of retrospection was 50 years (2018–1968) according to remote sensing data and more than 60 years according to archival materials. It was found that waterlogging of rainfed soils has a periodic character without definite trend for an increase in their area, i.e., the area of waterlogged soils has not changed over the past 50–60 years. The area of periodic influence of overmoistening on land use of arable land was estimated at 181 000 ha, or 8.5% of the arable land area. It was also shown that official statistical data significantly underestimate the area of waterlogged soils, as these soils on arable land are not taken into account. The total area of soil waterlogging reached about 16% of the agricultural land in Tambov oblast, including about 6% of waterlogged soils within the arable land. It was also found that the decrease in the area of arable during that period because of the economic reasons significantly exceeded the influence of natural factors.

An analysis of existing legislation shows that legal norms are established mainly for soils belonging to the category of agricultural land. The orientation of land legislation to the category of land does not take into account the specific features of the soil as an essential component of the environment. It performs the most important set of ecological functions in both natural and anthropogenic ecosystems. At present, even a few references to soil in the system of regulatory acts are actively supplanted by the category of land. In its legal essence, the category of land is primarily a socio-economic category. The existing in scientific literature and regulatory acts formulations reflect the modern scientific ideas of soil as an independent natural body; however, from the legal point of view, they are extremely vague, uncertain, and do not meet understanding among legislators. In the legal definition of the category of soil, it is reasonable to limit it to several of the most important soil characteristics, among which the humus content and the bulk density should play the major role. Naturally, the restriction of the category of soil to a narrow set of characteristic features will narrow it in some cases and unjustifiably expand the number of natural or human-made objects related to the soil in other cases, but this will move the project of the Federal Law On Soil Protection (no. 83334-3) from the stalemate.