No 4 (2023)

Based on the profile-genetic approach, we made the diagnosis and the classification position of previously little-studied soils of larch woodlands, mountain tundras and a belt of cold glacial deserts of the Polar Urals, formed in different landscape-geomorphological conditions. We studied morphological, physico-chemical and chemical characteristics of the soil profiles formed on rocks of basic and ultrabasic composition. We revealed that the main background of the soil cover under the larch forests are sub-burs (podzolic and illuvial-humus). Both soils are Entic Podzol (Skeletic) according to WRB-2015. In the mountain tundras, gleyzems of humus oxidized gley or Reductaquic Gleysol (Thixotropic) and gray-humus soils or Skeletic Phaeozem are formed. In the extreme soil formation conditions of the cold glacial desert belt (900–1033 m a.s.l.), different subtypes of gleyzems (Reductaquic Gleysol and Turbic Gleysol (Abruptic) occupy local areas. We also found that the surface, predominantly ground-depositional input of plant litter and its slow mineralisation resulted in coarse-humus and peaty upper horizons with a wide C/N molecular ratio.

Using the thermal method and IR spectroscopy, a typical chernozem (Haplic Chernozem (Loamic, Pachic)) of various land uses was studied. According to the data obtained, the organic matter of the chernozem mainly consists of weakly thermally stable aliphatic compounds such as polysaccharides. This is evidenced by the mass loss in the low-temperature region, which varies within 68.15–71.54%, and the intense absorption band at 1083 cm^-1, which determines the shape of the IR spectra of the chernozem. Under the influence of extensive agricultural use, the mineralization of labile aliphatic compounds and an increase in stable cyclic structures in the composition of the organic matter of chernozem occurred. This is indicated by a decrease in the Chernikov–Konchits Z coefficient from 3.16 to 2.47–2.73 and the intensity of most absorption bands in the IR spectra. The most noticeable negative impact on the organic matter of a typical chernozem was caused by bare fallow.

The thermal diffusivity of screened quarry sand with a predominance of a fraction of 0.05–0.25 mm, lowland packed peat, and their mixtures was studied. Sand was mixed with peat in various proportions; the content of peat in mixtures ranged from 1 to 80% by dry weight. Metal cylinders 10 cm high and 3.8 cm in diameter were filled with sand, peat, and peat-sand mixtures. The thermal diffusivity was measured in the laboratory using the unsteady-state method with a working temperature range of 20–26°C. The heating rate of the packed samples was measured after the samples were placed in a liquid thermostat with a constant water temperature. For each sample, a series of measurements was carried out with a step-by-step change in water content from the maximum one after capillary saturation of the sample to the minimum one, corresponding to the air-dry state. The thermal diffusivity vs. water content dependence was almost linear for peat, and for sand it was a curve with a maximum. The lowest thermal diffusivity was obtained for peat and mixtures with low sand contents; the highest one – for pure sand. Within the studied range of water contents, the thermal diffusivity of different samples changed by a factor of 1.3–2.8. The non-linear character of the thermal diffusivity vs. peat content dependence was discovered. Small additions of peat to sand resulted in a noticeable decrease in the thermal diffusivity of the mixture; small additions of sand to peat had practically no effect on thermal diffusivity. The thermal diffusivity of the studied substrates increased with increasing sample bulk density and sand content; decreased with increasing organic matter content.

The study of the dynamics of mycobiota during composting of cow manure and wheat straw using DNA barcoding and culture method was carried out. Using DNA barcoding, fungi of phylla Ascomycota, Basidiomycota, Mortierellomycota, Chytridiomycota, Rozellomycota, Aphelidiomycota were found. Cultural method (plating) identified Ascomycota, Basidiomycota, Mucoromycota. All the orders of fungi established by the plating method, with the exception of Saccharomycetales in Ascomycota and Mucorales in Mucoromycota, were also discovered using DNA barcoding, but many others were the latter. The coincidence of the species detected by both methods was very rare. Changes in the number of colony-forming and operational-taxonomic units of taxa of different levels during the transformation of manure with straw into compost were traced. DNA barcoding made more fully identify changes in the taxonomic and ecological-trophic structure of the fungal community during composting of manure and straw. They are expressed in a significant increase in the representation of basidiomycetes, especially Coprinus spp., Coprinellus spp., in compost, capable of transformation of lignin, complex organic substances of manure, and a decrease in the proportion of abundantly spore-bearing, “sugar” and cellulolytic ascomycetes dominating in the initial substrates: Sordariomycetes in manure and Dothideomycetes in straw. During composting, significant rearrangements occurred in the composition of coprophilic, epiphytic and phytopathogenic fungi. The importance of toxin-forming, allergenic and thermophilic species of fungi that pose a danger to human health, and the possibility of assessing the readiness of compost for application to the soil as a biofertilizer, taking into account data on mycobiota, are discussed.

Soil organic matter (SOM) is proposed to subdivide into structural and process pools. Structural pools include particulate organic matter (C_POM) and mineral-associated organic matter (C_MAOM), and process pools include microbial biomass (C_mic) and potentially mineralizable organic matter (C₀). The studies were carried out in a long-term microfield experiment on gray forest soil (Luvic Retic Greyzemic Phaeozems (Loamic)). Mineral (N 90–360, P2O₅ 75–300 and K₂O 100–400 kg/ha) and organic (fresh cattle manure from 25 to 100 t/ha) fertilizers in increasing doses were applied annually for 9 years. The increasing in soil organic carbon (C_org) stocks from NPK and manure was 5–10 and 38–83%, respectively. The application of extreme doses of manure (700 to 900 tons/ha in 9 years) led to saturation of the soil with organic carbon. SOM pools sizes decreased in the sequence C_MAOM > C_POM > C₀ > C_mic, amounting to 7.91–12 g/kg (50–84% of C_org), 0.76–12 g/kg (8–50%), 0.32–1.71 g/kg (2.8-13.7%) and 0.09-0.56 g/kg (0.8-3.7%), respectively. C_POM pool size depended mainly on the dose of mineral and organic fertilizers, and C_MAOM depended on the duration of fertilizer application. Both C_mic and C₀ pools increased with the manure dose and decreased with the NPK dose. The long-term manuring did not produce a cumulative accumulation of C₀ in the soil. It is emphasized that the separation of structural and process pools can be used for monitoring of SOM quality and functions.

In the Tula region, to analyze the fractionation of Mn in the soils effected by acid sulfate water, at 11 points (a total of 57 samples), we studied electrical conductivity of the water extract, the granulometric composition, pH, the concentration of total organic carbon and the three mobile fractions (exchangeable, complexed, and specifically sorbed) the metal. Technosols of a waste heap with a predominantly very acidic medium often have sulfate salinity. Acid sulfate water and solid-phase matter from the waste heap form talus, which bury highly productive Chernozems and Phaeozems. In terms of the fractionation of Mn, bared Regosols (Phytotoxic) at the talus are close to the toxic substrates of the waste heap, and plant-covered Regosols are close to the background Chernozems. In the transported material of plant-covered Regosols, the content of Mn mobile compounds increases. The input of acid sulfate water into the A-horizon of Chernozems increases the content of water-soluble \({\text{SO}}_{4}^{{2 - }}\) and Ca²⁺ and decreases the content of mobile compounds and the total content of Mn.