The article deals with the features of soil-agrochemical inspection of the nursery area with the use of geoinformation technologies. The purpose of this work was to conduct a soil survey of arable sod-podzolic medium - or light-loamy soils of the territory of the forest nursery, as well as estimation of production area contamination with weeds. The peculiarity of this study was the fact that the process of collection, systematization and processing of all compiled information was focused on the use of modern geographic information systems. Survey points were chosen in coordination with the administration of the nursery and were precised according to the actual space images. Geographical reference of testing points was carried out using global positioning technologies (GPS, GLONASS) based on the NextGIS mobile application (Android OS). Photofixation of nursery fields was performed by means of geotagging technologies, which allow implementation of the obtained graphic information directly into the geographic information system (GIS). The soil samples collected in the field were analyzed in the soil laboratory in order to determine the main indicators of soil fertility. On the basis of the received data the cartograms were developed by means of GIS, which provide information on the main nutrients content in the soil of nursery fields as well as on the most important indicators characterizing the soil absorbing complex (soil acidity, degree of base saturation, etc.). The study of weed infestation allowed developing the thematic map representing the weeds propagation on the nursery fields. All collected information was combined into a comprehensive geographic information system developed on the basis of Quantum GIS shell. As a result, the developed GIS will contribute to operational monitoring of soil fertility and ensure informational support for agricultural machinery applied in the nursery for growing planting material.

The methods of digital mapping are promising for creating soil maps on difficultly accessible territories. This study was aimed at searching of optimal approaches for digital mapping of the soil cover in poorly studied western part of the Bol’shezemel’skaya tundra on different scales. Medium-scale (1 : 200 000) and small-scale (1 : 1 M) soil maps served as the source of initial information about soils of this region; actual information of the state of the territory was obtained from remote sensing data (Landsat 8 scenes, Aug. 14, 2013) and digital elevation model ASTER GDEM v.2. After extraction of information and the choice of predictors, the analysis of digital soil cover models obtained with the use of different algorithms – Random Forest (RF), Multinomial Logistic Regression (MLR) and Linear Discriminant Analysis (LDA) – was performed. The coefficient of agreement between the newly developed digital models and the initial paper-based soil maps (kappa) was calculated. This test demonstrated that the RF algorithm ensures the best results, so the final digital maps were obtained using it. Averaged kappa values for the compared small- and medium-scale models were as follows: RF – 0.39 and 0.36; MLR – 0.31 and 0.31; and LDA – 0.28 and 0.18, respectively. After the preliminary correction of the initial medium-scale map, the kappa values somewhat increased (RF – 0.39, MLR – 0.35, LDA – 0.30). At the stage of evaluation of digital soil maps obtained with the use of RF algorithm, these maps and the initial soil maps were compared with independent point-size terrain data. The degree of agreement between these data and the new digital soil maps proved to be no less than that for the initial maps. For the initial and digital small-scale maps, it reached 24 and 26 %, respectively; for the initial and digital medium-scale maps, 54 and 43 %, respectively. After the preliminary correction of the initial medium-scale map, the degree of agreement between the digital model and terrain data improved considerably and reached 61 %. This method of digital soil mapping on the basis of analogous data seems to be optimal.

The agents that determine the soil salinity of the key plots “Chervlenoe” and “Duboovrazhniy” of the Svetloyarsk irrigation system (Volgograd region) are studied. We carried out a multifactor analysis of the toxic salts amount variance depending on the following agents: relief, vegetation, parent material and irrigation method, the water extract (1 : 5) being used. It was found that the factors determining the degree of soil salinity in terms of the amount of toxic salts in both cases is parent material. Its contribution into the total variance was more than 80 % for both studied plots. On the plot “Duboovrazhniy” relief also turned out to be a significant factor. Anthropogenic factor – the method of irrigation – was insignificant. The graphs of cumulative frequencies of the occurrence of salinity levels were constructed for soil layers of 0–30 cm, 30–100 cm, 100–150 cm, 150–200 cm. The top soil layer of 0–30 cm is almost non-saline in both areas. On the “Chervlenoe” plot there are strong and very strong degrees of soil salinization; in general, this site is characterized by higher toxic salts amount compared to the “Duboovrazhniy” plot.

The results of the study of the morphological properties of underwater soils in the deltas of the Volga, Don and Kuban rivers are shown. This paper is based on field descriptions of profiles of underwater soils found in deltas. Genetic horizons have been identified, their basic properties (pH, Eh, electrical conductivity, grain size composition, organic carbon content) have been studied and the main types of soils, which are formed under different types of sedimentation and under different types of aquatic vegetation, have been described. Names of horizons and types of soils are given due to the classification of underwater soils (aquazems) of the Volga delta, that had been proposed previously. The diversity of underwater soils of three deltas has been studied, and the properties of the same soil types formed in different deltas have been compared. The features of underwater soils formation are described; the difference between the factors of underwater and terrestrial soil formation is discussed. It is shown that the number of occurring soil types depends on the diversity of the emerging types of aquatic landscapes and the contrast of the conditions of migration and accumulation of matter. Necessary conditions for the forming of underwater soils and the possibility of relating bottom sediments to soil formations are discussed. Our results are indicative of the need of studying bottom sediments with soil-like profile from the standpoint of soil science and the inclusion of aquazems into the modern Russian soil classification.

The assessement of PEARL model adequateness was carried out on the basis of temperature and percolate data obtained by means of MSU Large Lysimeters. Lysimeters are used in experimental soil science mostly for investigating water balance and substance or ions transport from observed horizons or full soil profile. PEARL 4 model, the water prediction block of which is built on the basis of classical SWAP model, uses preferential water flow describing mechanism. Systematical observation of experimental soils in MSU Large lysimeters allowed obtaining extensive data on temperature and soil moisture dynamics, as well as percolate from bottom border. Thеsе measurements are unique and can become the basis for adaptation, verification and setting of mass and energy transfer models. It was shown, that mathematical parametric model requires adjustment for reaching reliable values of percolate from bottom border, moisture and temperature profiles. It can be achieved by selection of water retention curve (WTC) approximation parameters. It was noticed that the error for all predicted parameters increases in winter period. Thereby, the use of such matter transfer models in soil are problematic for long-term prognosis. For example, due to the annual error accumulation before the spring season such models cannot be applied for estimation of the risk of ground water pollution with agrochemicals.

The changes in the physical and microbiological properties of the coprolites of earthworms Aporrectodea caliginosa and Lumbricus rubellus were evaluated in laboratory experiments using the arable horizon of migratory-mycelial chernozem. In coprolites the following physical parameters were determined: particle size distribution, specific surface area, calculated by the effective particle diameter; microbiological parameters: the total number of cultured bacteria and the enzymatic kinetics of lipases according to the Michaelis –Menten model with the calculation of the maximum reaction rate (V_m) and Michaelis constant (K_m). The model experiment included two stages: the first stage – earthworms of two species were kept together, in the second – separately. The control was the source soil and the soil with litter. Coprolites and the soil in which earthworms lived were analyzed and compared with the control. Two types of earthworms give a non-additive effect on physical and microbiological properties. Depending on the species composition, the nature of the change is different. For the two species contained together a decrease in the specific surface area in coprolites was noted, as well as an increase in the fraction of the fine sand due to the reduction of the fractions of silt, fine and medium dust. For A. caliginosa kept separately it was found, that the specific surface of coprolites increases compared to the control, the silt and fine, medium, coarse dust, fractions rise due to a significant reduction of the fine sand fraction. For L. rubellus coprolites a decrease in the specific surface area, an increase in the fractions of medium, fine sand and coarse dust, due to the reduction of silt, fine and medium dust fractions, are shown. The number of cultured heterotrophic bacteria is higher in coprolites compared to the control. The greatest increase is observed in the variant where two species are kept together. The lipase activity (V_m) of the soil also increases when two species are kept together compared with the control and with A. caliginosa kept separately. Under the influence of L. rubellus the lipase activity decreases. Coprolites differ in all the investigated properties from the control (soil and soil with litter), as well as from the soil where earthworms lived.

In this study we examined the effects of conventional agricultural treatment with plowing and no-till treatment on the physical, chemical and microbiological properties of agro-transformed sod-podzolic loamy soil. Soil was sampled in eightfold spatial replication from the arable layers (0–10, 10– 20, 20–30 cm) of field No. 2 of the long-term field experiment of the Center for Precision Agriculture of the Russian State Agrarian University in June, 2018. The crop type on the field No. 2 was vetch and oat mix. Moisture content, water holding capacity, pH, percentage of carbon and nitrogen were determined. The NDVI vegetation index was measured using GreenSeeker HandHeld and used to estimate the plant development intensity. Microbiological properties were assessed by selective plate counts. The abundance and activity were estimated for the next ecological and trophic groups of microorganisms: heterotrophic ammonifiers, aerobic and anaerobic nitrogen-fixing agents, denitrifiers, oligotrophs, cellulolytics. The vegetation index NDVI was higher for plants growing on the plowed part of the field. The differences in microbiological properties when comparing soil samples under no-till and under plowing were insignificant (by t-test for the independent groups comparison). In no-till samples a greater number of micromycetes, including cellulolytic and phytopathogenic, was observed compared to conventional treatment. Profile distributions of bacterial and fungal gene abundances were similar for both treatments according to the paired comparison of samples from different layers. The similarity in microbiological properties was found in the condition of a higher moisture content of the arable layer of the soil and a higher percentage of nitrogen were revealed in the soil under no-till compared with the soil treated by plowing.

The article deals with the fertility of red ferralitic soils in the Republic of Chad. The studies were carried out in the period between 2016 and 2018 in the southern part of the province of Moundou on the red ferralitic soils (Haplic Ferralsol)of the Cotton-Chad farm, which cultivates cotton first of its formation. Haplic Ferralsols are characterized by significant reservoir thickness and are not rich in nutrients. The aim of our research was to study the composition and properties of the Haplic Ferralsols of the fields abandoned for five years for their use under cotton export culture. We have evaluated the morphological structure of the soil on neglected fields and its description by genetic horizons, studied the particle size distribution of the soil profile, its gross composition, cation exchange capacity, the content of exchangeable cations, and also considered the agrochemical and agrophysical properties of soil horizons. It has been established that Haplic Ferralsols have their own characteristics: red color, thick soil profile and a gradual transition between genetic horizons, and lightweight granulometric composition in the upper part of the profile. The basis of the gross chemical composition of Haplic Ferralsols is SiO₂, Fe₂O₃ and Al₂O₃, the content of which varies depending on the depth of the soil profile within the ranges of 61.83–82.73 %, 3.50–6.40 % and 11.46–29.25 % correspondingly. Haplic Ferralsols are characterized by a high cation exchange capacity (6.6–11.1 сmol (eq)/kg). Among the exchangeable cations, calcium (Ca²⁺) is the most essential. Haplic Ferralsols are moderately provided with humus. In the upper soil layers (up to 42 cm), its content varied within 1.53–1.66 %. Soils are characterized by acidic reactions – from moderately acidic in the upper horizons to very strongly acidic in the lower horizon. The content of mobile compounds of phosphorus and potassium in the profile is low and very low, respectively, 0.76–1.09 mg/100 g and 0.05–1.48 mg/100 g. According to its agrophysical properties, the soil may be used for cotton growing. In the upper soil layer (0–42 cm) the bulk density is 1.36–1.45 g/cm³, the total porosity is 45.9–48.9 % and the field water-holding capacity is 22.4–25.7 %.