Nº 10 (2025)

The effect of nitrogen and potash fertilizers on the annual and seasonal dynamics of mobile and water-soluble forms of potassium in the soil and the yield of cherry trees was studied. The experiment was conducted in 2018–2022. The experimental site is located in the forest-steppe zone of the Central Russian Upland (Oryol region). on agrograin medium loamy soils. Urea and potassium sulfate in doses from N30K40 to N120K160 were administered annually in early spring. Soil samples were taken from depths of 0–20, 20–40, and 40–60 cm from May to September. The content of mobile and water-soluble forms of potassium in a layer of 0–60 cm of non-fertilized soil was stable for 5 years. The annual application of fertilizers led to a significant accumulation of various forms of potassium in the upper layer of 0–20 cm of soil and seasonal changes in the content of the element. When the mobile potassium content reached >200 mg/kg, its vertical migration along the soil profile took place. The weather conditions of a particular growing season, plant needs, and fertilizer doses determined the seasonal dynamics of potash compounds. Fertilizers had no significant effect on the total yield of trees. Thus, the natural reserves of mobile potassium in the agro-gray soil in the amount of 100–200 mg/kg were sufficient to meet the needs of cherry trees in the early years of fruiting.

In 2020–2023, the effect of foliar top dressing in the tillering phase with Amino Start organomineral fertilizer and carbamide-ammonia CAS-28, and Alfastim growth regulator in earing on yields, grain quality indicators and susceptibility to diseases of Novichok, Pamyati Rodinoi, and Rodnik Prikamye barley varieties were studied in field experience. The hydrothermal coefficient (HTC) value during the germination–full ripeness period varied by year: 2020 – 1.60, 2021 – 1.30, 2022 – 2.10, 2023 – 2.00. The high responsiveness of the varieties Rodnik Prikamye and Novichok to the use of fertilizers has been established. The use of CAS-28 provided mainly reliable yield increases (at P ≥ 0.95). This variant has the lowest yield variability in the experiment, which increases the prospects of its use in different climatic conditions. Treatment of crops with Amino Start and Alfastim preparations increased yields in both varieties both in conditions of lack of moisture (2021) and its excess (2023). With excessive moisture (2022 and 2023), Amino Start and Alfastim preparations increased the starch and fat content in Novichok grain. In the relatively favorable growing conditions of 2020, the Novichok and Rodnik Prikamye varieties had an increased starch content in all variants, while the Pamyati Rodinoi variety had an increased fat content. Agrochemicals had no significant effect on the crude protein content in the grain. With a low level of helminthosporiasis infection, agrochemicals reduced the degree of damage to plants by reticular spotting and root rot.

The effect of non-inversion tillage methods on the activity of the enzymes of polyphenol oxidase (PFOA) and peroxidase (PO) was studied. The effect of pedoecological conditions on the level of polyphenol oxidase and peroxidase activity of agrochernozem was assessed and their contribution to the formation of mobile humic substances was revealed. The enzyme activity was studied using the Galstyan photocolorimetric method. No significant patterns of the dynamics of polyphenol oxidase activity of agrochernozem were found. In the first 2–3 years of observations, there was a tendency to increase the activity of PFOA when using non-inversion tillage. Under the conditions of inversion tillage, the dynamics of PFOA activity was determined by the level of moisture and catalase activity of agrochernozem. When using non-inversion tillage technologies, the dependence of PFOA activity on the direction of transformations of the mobile organic matter of the soil (MOM) was revealed. The variances of soil PO activity were associated with the variability of PFOA activity. During the study period, peroxidase activity was higher during non-inversion tillage. The specifics of the conditions that developed during flat-cutting tillage determined the role of peroxidase activity not only as a catalyst stimulating mineralization processes, but also as a factor contributing to the transformation of newly formed humic substances into more complex humus components. The dynamics of peroxidase activity in the soil of all variants was determined by the rhythm of transformations of water-soluble organic compounds. The use of flat-cut cultivators increased the proportion of catalase and organic compounds extracted by decinormal alkaline extraction (C_0.1NaOH).

Based on the results of high-throughput DNA sequencing using ILLUMINA technology, the taxonomic composition and ecological profile of fungal communities of potato leaves (Solanum tuberosum L.) of healthy plants and artificially infected with phytopathogenic fungi Phytophthora infestans (late blight) and Colletotrichum coccoides (anthracnose) were evaluated. Treatment of potatoes with compounds with antifungal activity – neutral components of spruce woody green extract E1, acidic components of pine woody green extract E2, synthetic meroterpenoids 1,2-dihydroxy-3-isobornyl-5-methylbenzene F1 and C-terpenylanilines A1 – affected the formation of mycobiota associated with the leaf and tuberous productivity of plants in various ways. Differences in the taxonomic composition of fungal communities were found both between communities characteristic of plants grown on different infectious backgrounds and those treated with various drugs. A significant increase in the number of fungal taxa detected in leaves compared with the control (48 phylotypes) was facilitated by A1 (95 phylotypes) and F1 (86 phylotypes) applied against the background of late blight, and A1 (89 phylotypes) – against the background of anthracnose development. Among the taxa identified during the study were fungi belonging to such ecologically significant categories (guilds) as saprotrophs, symbiotrophs, pathotrophs and forms with multiple functions in various combinations. When comparing the data of the metagenomic analysis of the mycobiota of potato leaves with its tuberous productivity, a positive relationship was found between the indicators of the taxonomic richness of the mycobiota and the mass of tubers from the plant. In the mycobiota, in variants with higher tuber productivity compared to the control (98 g) (treatment of F1 (168 g) and A1 (130 g) against late blight and E2 (134 g) against anthracnose), the representation of fungi belonging to the saprotrophe-symbiotrophe, saprotrophe pathotrophe-saprotrophe-symbiotrophe and pathotrophe-saprotrophe guilds increased. An increase in taxonomic diversity and a change in the ecological profile of fungal communities may be due to the membranotropic effect of some terpene components, which facilitates the penetration of phylloplane inhabitants into plant tissues. It is concluded that the treatment of potatoes with the studied compounds leads to a change in the taxonomic composition and ecological profile of the mycobiota of phylloplana, which affects the tuberous productivity of potatoes.

The study showed that soil pollution by lead, oil, and gasoline had a significant impact on the ecological functions of soils. Soil contamination with lead and petroleum hydrocarbons, even in relatively small doses, led to disruption of the soil cover structure and caused an almost complete depression of the functional activity of plants and soil organisms. Phytotoxicity indicators were a sensitive indicator of violations of physical, biochemical and microbiological parameters in the soil. The phytotoxicity of soils in different climatic zones was assessed when contaminated with lead (Pb), oil, and gasoline. We studied 11 types of soils in 3 climatic zones: real steppes, semi-deserts and forests. After 30 days from the start of the experiment, radish was sown to analyze the phytotoxicity of the soil. The soil phytotoxicity index (SPTI) was reduced to the greatest extent in semi-desert soils with gasoline and Pb pollution, and in forest soils with oil pollution. The results of the study can be used in assessing the phytotoxicity of soils of real steppes, semi-deserts and forests.