№ 3 (2023)

It was found that the soil of the agrocenosis with a long-term deficit balance of potassium and magnesium recorded 60-70% of potassium introduced with fertilizer and 20-30% of magnesium. With a positive balance of these elements in the agrocenosis, the fixation of potassium by the soil decreased to 40, and magnesium - to 6-10%. The introduction of increasing doses of potassium fertilizer did not affect the soil level of the content of exchangeable magnesium, the use of magnesium fertilizers did not change the content of exchangeable potassium in the soil. The combined use of moderate doses of potassium and magnesium fertilizers contributed to a decrease in potassium fixation by 10-16% compared with its separate application, while the intensity of magnesium fixation did not change. With increased doses of potassium, its fixation by the soil did not depend on the additional addition of magnesium, and magnesium fixation significantly decreased.

It was found that due to the low humus content and low biological activity of virgin chestnut soils of Western Transbaikalia, the gross amount of sulfur is low. The distribution of sulfur along the profile is gradually decreasing with some accumulation of it in the carbonate horizon. Prolonged irrigation due to an increase in humus content and biological activity contributed to an increase in the amount of sulfur, which practically increases with the depth of the profile. When irrigated in a layer of 0-20 cm, the stock of mobile sulfates was 3 times larger than in virgin soil (7.3 and 2.4 kg/ha, respectively); in the 0-50 cm layer - 1.3 times, in the 0100 cm layer - 2.9 times. According to the content and reserves of mobile sulfur, chestnut soils in a layer of 0-20 cm are classified as low-income. After 3 years of using increasing doses of sulfur fertilizers (against the background of NPK) for irrigated potatoes, the content of all forms of sulfur in the soil increased depending on the dose size. The following pattern was revealed: with an increase in the dose, the amount of S_org in the soil and the enrichment of humus with it increased, the ratio C : S_org narrowed. A negative sulfur balance was established in the control and in the background version. The introduction of the lowest dose of S15 has already formed a positive balance, but given that chestnut soils are depleted of mobile sulfur, it is necessary to apply a dose of S30 (against the background of NPK) in compliance with irrigation standards.

In a long-term field experiment, laid down in 1968, an assessment of the effectiveness of the use of organic, mineral and organo-mineral fertilizer systems on sod-podzolic heavy loamy soil was carried out. It was found that in the climatic conditions of the Urals, the organic fertilizer system was inferior to the mineral and organo-mineral fertilizer systems in terms of its effect on crop yields. In some rotations of crop rotations, the organo-mineral fertilizer system was more effective, in others - the mineral fertilizer system. The effectiveness of the use of fertilizers depending on the conditions of humidification of the growing season is considered. The balance of organic carbon and basic nutrients in the soil is calculated. Long-term cultivation of agricultural crops without the use of fertilizers led to the loss of >10 tons of organic carbon, ~2300 kg of nitrogen, 780 kg of phosphorus and 2700 kg of potassium from the soil. High negative balances of basic nutrients in the control variant led to a deterioration in soil fertility indicators. It is shown that the use of all fertilizer systems provided an increase in the content of mobile phosphorus and potassium compounds in the soil relative to the initial level by 1.2-3.0 times. When using organic and organo-mineral fertilizer systems, the maintenance of organic carbon content at the initial level (1.3%) was noted. When using a mineral fertilizer system, the maintenance of the organic carbon content at the initial level was noted only at a higher saturation of the arable land with NPK. The mineral fertilizer system has led to acidification of the soil.

In a field long-term experiment on sod-podzolic soil, the effectiveness of the complex application of fertilizers and their effect on soil fertility and productivity of annual grasses in the feed 6-pole crop rotation was determined. It is shown that the combined use of fertilizers most effectively affected the increase in the fertility of sod-podzolic soil and the productivity of the vico-oat mixture. The amount of humus increased by 0.3—0.8%, mobile phosphorus - by 60-140 mg/kg, the exchange and hydrolytic acidity and the content of exchangeable potassium in the soil decreased. The complex application of fertilizers in high doses significantly increased the yield and quality of annual grasses.

In field experiments at the VNIISS experimental field, various combinations of herbicides were tested against juvenile dicotyledonous weeds in the sugar beet crop in 2018-2020, including preparations: Betanal maksPro (BMP), Betanal Expert OF (BEOF), Betanal 22, Mitron, Caribou. The effectiveness of chemical weeding has been investigated depending on the age of weeds and the rate of consumption of drugs. It is shown that the highest efficiency of chemical weeding (98-100%) in combination with low phytotoxicity for sugar beet was provided when processing the lowest (of the recommended) consumption rates of drugs in the early phases of weed development: cotyledons-the 1st pair of true leaves. The delay in herbicide treatment increased the heterogeneity of weeds in the development phase and reduced the effectiveness of chemical weeding. Sugar beet, especially in the early stages of development, experienced stress after the introduction of herbicides for 6 to 14 days. The duration of stress depended on the dose of herbicide, environmental conditions, and the phase of sugar beet development. With excessive application of herbicides, sugar beet plants were subject to a longer depression. The formation of productive indicators of sugar beet depends on weather conditions, the effectiveness of a combination of herbicides on weeds and their toxicological load on crop plants. The use of maximally permissible and increased herbicide consumption rates for overgrown weeds at all stages of chemical weeding created prerequisites for reducing the productive indicators of sugar beet. In experiments where relatively “rigid” herbicide schemes were used, the calculated sugar harvest decreased by 0.64-1.01 t/ha.

The chemical composition of the soils of the Republic of Tyva has been studied and evaluated from an ecological standpoint. This is important both from a scientific and practical point of view. Halogens play a significant role in the vital activity of living organisms. They, like other macro- and microelements, are involved in the process of forming the food chain: atmosphere - soil - natural waters - plants - animals - man. When assessing the biogeochemical value of a particular halogen, it is important to know not only its gross content, but also the concentration of its mobile forms capable of migration and participation in the dynamic equilibrium between the solid phase of the soil and the soil solution. This is due to the fact that plants are supplied with nutrients due to the mobile forms of various elements. At the present stage, the study of halogens is clearly insufficient, fluorine is among the most studied, iodine is less, and bromine is very poorly studied.

Inoculation of crop seeds with selective strains of growth-stimulating bacteria is an environmentally friendly, low-cost way to increase their yield, but may depend on some biotechnological factors affecting their physiological activity. These include the conditions for the cultivation of bacteria and the dose of the drug. The work analyzed the effectiveness of inoculation of Bashkir spring wheat with 28 different preparations of the Bacillus subtilis strain 10-4: 1 - an aqueous suspension of bacterial cells washed off potato-glucose agar (PGA), 2 - a liquid culture containing cells with exometabolites obtained by cultivating bacteria in potato- glucose broth (PGB), 3 - liquid culture of bacterial cells grown in legume-glucose broth (LGB). At the same time, the growth-stimulating effect of applying a high dose (10⁸ cells/ml) and a low dose (104-105 cells/ml) of bacteria in the inoculum was evaluated. When comparing the preparations obtained from potato-glucose medium, it was revealed that the positive growth effect (an increase in the number of wheat plant roots) was caused only by a high dose of the drug cells in the PGA and both doses of the drug in the PGB, but a high dose of the drug in the PGB inhibited seed germination up to 74% (in the control 100%). When comparing the preparations obtained during the cultivation of bacteria in PGB and LGB, it was revealed that the best growth effect (total root length and shoot height) was greater than control in plants inoculated with a small dose of the drug in PGB and a large dose of the drug in LGB. The stimulating effect of a small dose of the drug in LGB was less and extended only to the root system. The results of laboratory experiments coincided with the effectiveness of the studied drugs in the field. The use of a drug obtained in BGO and administered at a dose of 10⁸ cells / ml, and a drug obtained in PGB and administered at a dose of 105 cells/ml, increased grain yield by 1.6-1.7 times with a decrease in the intensity of leaf-stem diseases by 32 and 11% compared with the untreated control. The drug obtained in LGB and introduced in a small dose did not provide either an increase in yield or a protective effect compared to the control. Possible causes of the action of B. subtilis 10-4 strain preparations related to the production of phytohormones by it, depending on the composition of the medium, and with different adaptive capacity of bacteria when cultured on nitrogen-rich and less nitrogen-rich media are discussed.