Počvovedenie

The new approach for the updation of the traditional paper soil maps was provided. It is based on the imitation modeling of the traditional expert-based approaches for soil mapping. The result of the probe of our approach for soil mapping on the example of test site in the center of european part of Russia was given. The open-source script program IMSOIL was developed for soil maps updation on the R programming language. In the comparison to the others in our approach the expert-based knowledge of soil geography are also incorporated with the results of statistical data analysis. The updated soil map had much better consistency with the up-to-date soil forming factors data than the traditional paper soil map. The suggested approach of the imitation of soil mapping in geoinformational system includes using the good quality soil geography data and quantitative rules for soil mapping. The models in the form of decision trees can be analyzed by an expert, and the improvements to the covariates and obtained models can be made by him. The form of the decision trees of the soil mapping rules allowed to save up traditional qualitative description of the soil geography in the formalised representation and to integrate it with the unambiguous quantitative rules for soil mapping. They are based on the satellite data and thematic maps. Such a method allows automatically extracting relationships of the soils with the soil forming factors. The updation of the soil maps is accompanied by the probability map.

The study examines soil changes in the permafrost regions of the northern part of Western Siberia and the East European Plain (from tundra to sub-taiga), occurring in response to climatic fluctuations during the late glacial period and the Holocene (the last 15,000 years). The main focus is on the impact of temperature regime changes, which limit biological cycles and determine the influence of the thermal-physical properties of soils on pedogenesis processes. Soils are viewed as natural bodies recording changes in climate and landscapes. The study summarizes information on climate changes in northern Eurasia during the late glacial period and the Holocene, addressing the following issues: data on soil evolution under different climate change scenarios; major stages of sedimentation and pedogenesis in northern Western Siberia under hydromorphic and drained landscapes; the gradient of peat formation onset in Western Siberia, from Arctic tundra to sub-taiga; stages of pedogenesis on the Russian Plain and in Western Siberia associated with climate warmings and coolings; the history of the formation of hortic horizons in the southern forest zone of Western Siberia and their fate in connection with recent climate warming. The research is based on the study of natural archives such as peat and gley horizons, the content and composition of organic matter and the mineral part of the soil; cryogenic structures; relict horizons in modern soils; soils buried under natural sediments and archaeological structures. Geographic differences in soil response to climate changes and their relationship to the history of pedogenesis are discussed, with specific examples from various regions provided.

The conversion of land use is a crucial factor in the dynamics of soil carbon stocks. The widespread abandonment of cropland that began in Russia during the 1990s resulted in vegetation and soil restoration. This led to changes in soil properties and carbon fluxes within the plant-soil-atmosphere system. The aim of the study was to investigate the effects of post-agricultural soil restoration on the rate of change in soil properties, specifically organic carbon (C_org) and total nitrogen (N_total) contents, microbial respiration rate, and activity of hydrolytic enzymes. A post-agricultural chronosequence formed on Haplic Luvisols, including current cropland, 7- and 25-year-old post-agricultural abandoned land and grassland was studied. The rate of change in soil properties during post-agricultural restoration was evaluated based on their sensitivity to land use changes, with a comparison of changes in soil organic carbon content. The least sensitive properties to land use change were found to be C_org and N_total in the mineral-associated organic matter fraction, and pH value. The content of water-soluble nitrogen, C_org and N_total in the free and occluded organic matter fractions, as well as β-glucosidase and chitinase activity, were the most sensitive to land use changes. Therefore, the recovery of sensitive soil properties in the upper 10 cm is complete within the first decade after tillage is stopped. In contrast, the restoration of less sensitive properties requires more than 20 years.

The paper provides a detailed analysis of the soil permanganate-oxidized carbon (POХС) method. The purpose of this work was to describe the range of POXC values in the humus horizons of soils of different land uses of the European territory of Russia and to assess the possibility of using it as an indicator of the state of soil organic matter. The work objectives included: a) the selection of the corresponding soil mass for the analysis; and b) determination of the range of POXC values in soddy-podzolic soils (Retisols), gray soils (Greyzemic Phaeozems), and chernozems (Haplic Chernozems) of different land uses of the European territory of Russia. For soils with the carbon content from 1.6 to 4.7% a negative nonlinear relationship between the POXC values and the sample mass was established: with an increase in the sample mass in the range of 0.5–7.0 g, the average POXC decreases by 1.5–3.0 times for both natural and agricultural soils. The most suitable mass for determining POXC is 2.5 g, since it allows determining POXС for soils with the greatest variation in the total carbon content. The absolute values of POХС for three types of soils in the European Russia were from 358 to 1040 mg/kg, relative content varies from 1.2 to 4.4%. The considered permanganate-oxidizable carbon method makes it possible to assess the pool of TOC, probably most easily metabolized by soil microbiota. Low analytical variability, sensitivity of the observed values of permanganate-oxidizable carbon (POC) to soil type and land use allows us to consider this parameter as a promising indicator of soil health assessment.

An assessment of the enzymatic activity of chernozem and sod-podzolic soils contaminated with oil was carried out across a wide range of activity of 20 enzymes. The objects of the study are ordinary chernozem and sod-podzolic soil. To simulate hydrocarbon contamination, oil was added to the soil (1, 5 and 10%). To assess the enzymatic activity of soils, the activity of 20 enzymes of the oxidoreductase and hydrolase classes participating in the biogeochemical cycles of C, N, O, P and S was determined. Cellulase and cysteine reductase were the most sensitive to oil pollution of ordinary chernozem, and adenosine triphosphatase and nitrate reductase were the most sensitive to oil pollution of sod-podzolic soil. All the studied enzymes (except for protease and β-glucosidase in ordinary chernozem) showed high information content – a close correlation with the oil content in the soil (r > 0.65). The integral index of enzymatic activity (IIEA), geometric mean (GM_EА) and integral pollution index (AР) were calculated. Of the integrated indicators, IIEA (r = –0.97…–0.98) and GM_EA (r = –0.98…–0.99) showed high information content, while indicator AР showed low information content in sod-podzolic soil (r = –0.46). It is recommended to use IIEA and GM_EA for enzymatic diagnostics of the ecological state of soil after oil pollution. When soils are contaminated with oil, the N, P and C cycles are disrupted to a greater extent, and S and O cycles to a lesser extent. When contaminated with oil, the enzymes of the C cycle (invertase, polyphenoloxidase, dehydrogenases), N cycle (urease), P cycle (acid and alkaline phosphatases) and O cycle (catalase and peroxidases) have the highest average score of enzyme applicability for soil health diagnostics. The use of enzymatic diagnostics is very effective and appropriate for assessing the ecological state of soils contaminated with petroleum hydrocarbons.