The article considers the logic and periods of V.V. Dokuchaev Soil Science Institute development as well as the driving forces during the mentioned periods and the most important outcomes and tasks for the near future. One can distinguish four main periods in the history of the Institute, they are: organization, sustainable development, survival, revival. Some factors like scientific and organizational structure of the Institute, its contribution to the development of theoretical and applied soil science are considered as the indicators typical of each period. Firstly, the Institute structure during the initial organization period shows the priority of fundamental soil research in the leading areas: soil physics, soil chemistry, soil genesis, biology, etc. Advanced development of theoretical research allowed scientists to promptly respond to actual needs of the developing country: search for soil resources for cultivation of technical crops, development of new territories, land reclamation and hydrotechnical construction. By the 1970s a kind of sustainable scientific and organizational structure had finally formed in the Institute. In the early 90s, the Soil Science Institute entered a critical phase of development. The second decade of the XXI century became a turning point in its fate. A new strategy in the development of scientific activities of the Institute was sorely needed. The new strategy consisted of three interrelated elements. The first one was modernization of the material and technical basis for researches; the second one was strengthening of the human resources potential through attraction of motivated young researchers; and the third one was in establishing unilateral and multilateral interactions between the partners – users of scientific knowledge. The main areas of interaction were the topical issues: food security, global climate change and their implications for the country. It has been shown that society can recognize and support the scientific research only if a constant flow of information, obtained by means of different tools and methods, is provided. The significance of soil science as a fundamental discipline in the socio-economic development of the country was confirmed by the Government Resolution (2022) on the celebration of the 100-th anniversary of the V.V. Dokuchaev Soil Science Institute. The modern noosphere paradigm in soil research poses new challenges to the science, at the forefront of which is V.V. Dokuchaev Soil Science Institute.

By the example of arable horizon samples taken from three soil types (sod-podzolic, gray forest, and leached chernozem) the peculiarities of electromagnetic waves reflection from their different particle size fractions were studied. The extraction of fractions by dry sieving was carried out using Retsch AS 200 BASIC equipment. As a result, 14 fractions ranging in size from less than 20 microns to more than 5,000 microns were isolated. Spectral reflectance was determined for each fraction and for the soil sample before sieving in the electromagnetic wave range from 350 to 2,500 nm using a SR-6500 field spectroradiometer (Spectral Evolution, USA). Analysis of similarities and differences in the obtained spectral reflectance curves of individual fractions was carried out using their visual analysis, the method of similarity dendrogram construction, as well as regression analysis between light reflectance and fraction particle size. It was confirmed that at a more detailed level of analysis compared to the one carried out by other researchers earlier, the general patterns of light reflectance of the samples do not change. A higher reflection of waves by thinner fractions and a lower reflection by more coarse fractions are observed. At the same time, spectral reflection curves for individual fractions are out of the general pattern, the level of intensity of local extremes of the curves’ changes. This confirms the difference of the material composition, which forms the color of soils, of these fractions from others. The color of the mixed sample is a spectral mixture of colors of its separate fractions. Presumably, this is the main reason for such a phenomenon as change of spectral reflectivity of open surface of soils under the influence of atmospheric precipitation.

The analysis of the biological and enzymatic properties of soils is an important aspect of soil ecology, but the results of studies can be strongly influenced by the storage conditions of the samples. Variation in storage methods and duration studies reduces the ability to accurately interpret data and compare results. This work presents a study of the influence of various storage conditions and time on the results of the activity of enzymes of hydrolase class (urease, phosphatase), and oxidoreductases class (catalase, peroxidase and polyphenoloxidase) of meadow chernozem-like soil of the Zeya-Bureya plain. For the research, a laboratory experiment was performed, in which naturally moist and air-dry samples were taken and stored under various conditions: room temperature (+23 – +25 °С), low positive temperature (refrigerator, +10 °C), negative temperature (freezer, –10 °С) within 7, 28, 90 and 365 days. As a result, we found that drying soil samples immediately after sampling increases the activity of urease, phosphatase, peroxidase and polyphenoloxidase. Storage conditions do not significantly affect the activity of enzymes. To assess the actual enzymatic activity, we recommend using naturally moist soil samples immediatel y after sampling; to assess potential enzymatic activity, drying the soil and storing it for no more than 7 days are recommended. The results of this study provide useful information on the impact of sample storage conditions for researchers of enzyme activity in similar climates and contribute to further consideration and discussion of the implications of sample storage.

An analysis of the soil cover of Russia as presented on the soil map on a scale of 1 : 2.5 M with the use of a new substantive-genetic soil classification system has been performed at the level of soil orders. The high level of classification-based generalization makes it possible to assess the most general patterns of soil geography and soil resources and to identify changes that have occurred as a result of renaming of each polygon on the map with the use of the new classification. The areas occupied by soil orders have been calculated. In total, there are 24 soil orders on the new map, including 21 orders of natural soils and 3 orders (agrozems, turfzems, stratozems) of anthropogenically transformed soils. Soils of the orders of agro-abrazems, chernozems, and turbozems are not presented on the map. As on most small-scale soil maps of Russia, the zonal regularities of the soil cover in the East European Plain and high lithogenic mosaicity in Central and Eastern Siberia are clearly seen. The new map includes soil orders that were absent on the initial map: cryozems, cryometamorphic and hydrometamorphic soils, lithozems, cryoabrazems, cryoturbozems, urbostratozems, and organo-accumulative soils. Soils characteristic of humid conditions predominate: Al-Fe-humus soils (Podzols) (319.2 M ha, or 19% of the land fund of Russia), gley soils (Gleysols) (223.9 M ha, 13%), texture-differentiated soils (Luvisols and Regosols) (190.8 M ha, 11%), and peat soils (Histosols) (143.5 M ha, 8%) and occupy more than a half of the territory of Russia. The area of humus-accumulative soils most suitable for arable use is 103.6 M ha (6%). Considerable areas are occupied by soils of the orders of cryozems (Turbic Cryosols) (111.4 M ha), iron-metamorphic soils (Chromic Cambisols) (92.7 M ha), structure-metamorphic soils (Cambisols) (47.3 M ha), pale-metamorphic soils (Cambic Cryosols) (12.8 M ha), hydrometamorphic soils (Calcic Gleysols) (4.3 M ha), and cryometamorphic soils (Cambisols Gelic) (3.4 M ha), which corresponds to the vast continental territory of Russia with balanced moisture conditions. Separate place belongs to the soils with strict limitations for use (lithosols (Leptosols), weakly developed soils (Regosols, Nudilithic Leptosols)) but playing important biospheric functions and requiring special protection.

Water-extractable organic matter is the most active and mobile form of soil carbon. The other active fraction and extremely biolabile is the carbon constituent of microorganisms. Both of these fractions play an essential role in agrocenoses and in the global carbon cycle on our planet. The aim of the work was to estimate the carbon content of water-extractable organic matter as well as that of microbial origin in typical chernozems (Protocalcic Chernozems) of different land-use types. Protocalcic Chernozem samples taken from the fields of long-term experiments with different types of land use were investigated: a permanent bare fallow for 55 years (since 1964); conventional tillage – four-field crop rotation, first rotation; direct seeding – crop rotation similar to direct seeding, first rotation; a 21-year fallow (since 1998) after 34 years of bare fallow (since 1964). We determined the carbon content of water-extractable organic matter and the carbon content of microbial origin. In the studied series of variants, the proportion of carbon of water-extractable organic matter in the total amount of organic matter in the upper horizon (0–15 cm) was 0.69, 0.85, 1.01, and 0.98%, respectively, while that of carbon of microbial origin was 0.27, 0.55, 0.53, and 1.52%. It was noted that against the background of increasing the content of total organic carbon in direct seeding variant, compared with the traditional soil treatment, the microbial biomass in this variant does not increase. The fallow variant, unlike all other types of land use, is characterized by a higher proportion of microbial carbon, in contrast to the carbon of water-extractable organic matter.

The key feature of the no-till technology is the preservation of crop residues on the soil surface. Crop residues quantitative assessment is an important task when introducing technology into production. On the basis of field and remote sensing data, different approaches to this assessment are considered. The research was carried out in the Budennovsky district of the Stavropol Territory in the fields of farms using both traditional technology (TT) and no-till (ПП). Images of the Sentinel-2 system were used as remote sensing data, on the basis of which the spectral indices NDTI and NDVI were calculated. Three methods were used to estimate the projective cover by plant residues: 1) weight accounting of plant residues per unit area; 2) field determination of the projective cover by the method of line transects; 3) desk analysis of photographs of the soil surface. Based on the obtained results, models of the linear dependence of NDTI values on the projective cover of the soil surface with plant residues were constructed. The possibility of quantitative accounting of plant residues only on the basis of remote sensing data was also analyzed. The highest coefficient of determination (R² = 0.97) with the smallest square root of the standard error (RMSE = 7.93) was obtained by modeling based on the analysis of photographs of the soil surface covered with plant residues. Based on the model of the dependence of NDTI values on the projective cover of plant residues obtained as a result of the analysis of photographs based on Sentinel -2 satellite data for the growing season 2020–2021, data were obtained on the dynamics of soil coverage with plant residues (CRC) on the scale of a single field an d different tillage technologies. As an approbation of the approach and an assessment of its use for solving production problems, the dynamics of the projective cover with plant residues was analyzed under different crops and different relief conditions. An analysis of the dynamics of CRC values made it possible to distinguish between different stages of crop cultivation under traditional technology (TT) and no-till (ПП), and also on the scale of an individual field revealed the heterogeneity of the projective soil cover with plant residues associated with the features of the mesorelief.

The article presents the dynamics of soil freezing and thawing in the agroforestry landscape of the dry-steppe zone. These processes in winters with unstable snow cover have their own characteristics. The purpose of this study was to investigate the character of soil freezing and thawing in the agroforestry landscape under conditions of low snowfall winters. Observations were carried out in the winter period of 2020–2021 at the existing runoff-erosion research station in Volgograd. The dynamics of soil freezing and thawing was studied using Danilin freeze-thaw meters installed in the field and in the center of a four-row forest belt. Simultaneously, snow cover height was measured in triplicate with a snow measuring rod. The weather conditions were characterized by alternating thaws, which promoted snow cover melt, and frosts, which increased the depth of soil freezing. The formation of a 10-15 cm snow cover did not affect soil freezing. In the absence of snow on the background of a brief thaw, the lower boundary of the frozen layer in the field decreased by 11 cm compared to the forest belt, which even in the leafless state affected the inflow of solar thermal energy. Average freezing at the end of winter was 85 cm in the field and 67 cm in the forest belt. Thawing in the field was faster. During the first two weeks, the rate of soil thawing averaged 2.3 cm/day in the field and 1.3 cm/day in the forest belt. After that, the depth of freezing in the whole agroforestry landscape became equal. During the next two weeks, the thawing rate doubled. After complete soil thawing in the field in the forest belt, the thickness of the frozen layer averaged 32 cm.