No 8 (2024)

The aim of the work is to reveal the correlations between the spectral characteristics of the open soil surface in the Pleiades image (04/25/2020) and soils in a key plot with a complex soil cover pattern in the southern part of the Volga upland (Volga-Don irrigation system, Volgograd oblast). The territory is characterized by high lithological heterogeneity: Paleogene and Neogene sands and loams are overlain by a cover of Quaternary brown loams of variable thickness from 1–2 m to complete wedging. The soil cover is represented by light chestnut solonetzic complexes complicated by a mosaic of lithological variants and erosion-accumulative combinations. Basing on digital methods of processing the spectral characteristics of the satellite image and the use of ground-based soil information, eight soil groups were separated and a map of their distribution was created for a key plot of 343 ha. Soil groups differ in general features of the soil surface due to the presence and amount of rubble and stones, the texture of the surface horizon (from sand to medium loam), the presence of brightened crusts on the surface, the presence or absence of HCl effervescence from the surface, depending on the thickness of the first lithological layer. Within individual groups, soils with different profile structures (agro chestnut, agrozems, agrosolonetzes) are combined. Soils of the same type and sometimes subtype fall into different groups according to spectral characteristics. This is due to the incomplete correspondence of the properties of the soil surface, which affect the spectral characteristics, and the internal structure of the soil profile as a whole.

The soils of the sea coasts function on the contact of terrigenous runoff and the effects of seawater, which provides a unique geochemical environment. In part, the processes of migration and accumulation of elements can be provided by the processes of formation and oxidation of iron sulfides. The content and spatial distribution of trace elements in the soils of the marshes of the Pomor coast of the White Sea were studied. The work was carried out near the village of Kolezhma, Belomorsky district, Republic of Karelia. The study showed that the studied soils are characterized by an increased content of trace elements such as As and Se, which are usually associated with the presence of metal sulfides in marine sediments. The content of Fe was up to 27 300 ppm and Mn – up to 1500 ppm, which is generally typical for taiga landscapes. At the same time, the geochemical fate of Fe and Mn in coastal soils diverges, probably partly due to the participation of Fe in mineral transitions from sulfides to sulfates. Ni and Cr were present in soils in concentrations comparable to the zonal soils of the region. Only As and Se might be potentially toxic in the case of the use of the tombolo as hayfield.

The paper analyses the soil nematode communities of typical tundra of southern Chukotka. We have examined five types of shrub and grass-shrub biotopes formed on the Cryosol, Fluvisol, Histosol, Gleysol and Cambisol. The animals were extracted from the soil by the Baermann technique with subsequent determination of taxonomic diversity, total and relative numbers, and trophic groups. The highest number (7044 individuals/100 g of soil) and biomass (12.15 mg) of nematodes were found in the histosol, and the minimum number (1000 individuals/100 g of soil; 1.96 mg) of nematodes in the Cryosol. Bacterivorous nematodes dominated in all soil types. The maximum percentage of bacterivorous nematodes (94%) were found in the Cambisol. Their percentages of fungivorous nematodes in the studied soils ranged from 1 to 42%. Predatory and omnivorous nematodes were present in all soils except for the litter of the Cambisol. Their percentage ranged from 2 to 32%. Phytonematodes were few, their highest number was found in the Gleisol (18%). The nematode fauna of the soils under analysis differed significantly. The greatest diversity of nematodes was found in the turf horizon of the Fluvisol, and the smallest diversity of nematodes was in the litter of the Cambisol. The values of Sigma Maturity Index ranged between 2 and 3. The Enrichment Index had low and middle (1.40–41.02) values, and the Structure Index had high values (59.51–84.07). The genera of Eudorylaimus and Plectus were eudominants in all soil types. The soil food webs formed in the biocenoses under consideration can be characterized as stable and structured except for the alder biocenose.

The effect of long-term use of mineral fertilizers on changes in the content of total phosphorus, its organic, mineral and mobile compounds in soddy-podzolic heavy loamy soil (Albiс Retisol (Abruptic, Aric, Loamic)) was studied. The studies were carried out in a long-term stationary experiment established in the Perm region in 1978. Options – 0 (without fertilizers), N90, P90, K90, N90P90, N90K90, P90K90, N90P90K90, N30P30K30, N60P60K60, N120P120K120, N150P150K1 50. Ammonium nitrate or urea, double or simple superphosphate and potassium chloride were used in the experiment. It was established that long-term use of superphosphate during five rotations of a field eight-field crop rotation (P90, P90K90, N90P90, N90P90K90) led to a significant increase in the total content of phosphorus in the arable soil layer (0–20 cm), its mineral part by 1.3–1.8 times, mobile connections by 1.9–2.7 times. The use of nitrogen fertilizers (N90, N90K90, N90Р90 N90Р90K90) influenced the accumulation of organic phosphorus compounds in the soil. A significant increase in the soil content and reserves of both mineral and organic phosphorus compounds was observed only when using complete mineral fertilizer N90P90K90. Different combinations of superphosphate with nitrogen fertilizers and potassium chloride, as well as the dose of fertilizers, influenced the intensity of accumulation of mobile phosphorus compounds in the soil by rotation and changes in its amount along the profile. The application of low doses (NPK) 30–60 led to an increase in mobile phosphorus compounds mainly in the arable soil layer; when higher doses (NPK) 90–150 were used, changes were noted in the 0–80 cm layer. Long-term use of nitrogen and potassium fertilizers over time led to an increase in mobile phosphorus compounds in the arable soil layer.

In urban conditions, the soil is exposed to a number of adverse effects that have a great impact on its hydrophobic and hydrophilic properties. The water-repellent properties of urban dust and soil samples were determined using a WDPT test, the process of hydrophobization of Albeluvisols in the conditions of a megalopolis was modeled and its speed was estimated. The study used three dust samples with different values of the WDPT test from 420 to 850 seconds. According to the results of the model experiment it is shown that with an increase in the amount of solid atmospheric precipitation in the Retisols material, the level of its hydrophobicity also increases. The rate of increase depends on the water-repellent properties of the dust sample. When polluted with the most hydrophobic dust, the maximum hydrophobization of the humus-accumulative soil horizon is achieved at a 70-year load. For other dust samples, an increase in the time of absorption of a drop was observed up to the maximum period of aerial soil contamination within the model experiment (200 years). Values of the WDPT test for the studied soil horizons ranged from 2.4 s for background soil, to 1493.5 s for urban soil formed near a major highway for 90 years. In the soil of residential buildings of 40 years of age, the value was 237.1 s. The correspondence of the levels of hydrophobicity, the degree of anthropogenic load and the residence time of sites in the urban environment in the model experiment and in samples of real urban soils at the study sites indicates that solid atmospheric fallouts is a component of humus-accumulative horizons of urban soils and has a significant impact on their water-repellent properties.