Nº 5 (2024)

The influence of dump and non-dump tillage techniques on the transformation of mobile organic compounds of carbon and nitrogen in the conditions of the forest-steppe zone of the Krasnoyarsk Territory has been studied. The influence of the ratio of the content of easily mineralized carbon and nitrogen on this process is estimated. The value of the C : N ratio in the soil of the studied variants indicated an average level of nitrogen enrichment of humus. The C : N values for mobile forms of carbon and nitrogen had a broader relationship in the soil treated with the use of waste-free technologies. Strong correlations were found between C_0.1 NaOH and the C : N ratio in the soil. Under the conditions of application of dump processing technology, an increase in the provision of soil with active organic matter made it possible to stimulate the nitrogen mineralizing ability with the accumulation of ammonium nitrogen compounds. When using non-waste treatments, similar dependencies were found with the content of nitrate nitrogen compounds. The values of С_mb in С_org (%) indicated a weak biogenicity of the studied soil. There was no differentiation between the layers in terms of the rate of carbon dioxide emission.

In the field experiment, the effect of binary sideral mixtures with sunflower on the content of humus, mobile phosphorus and exchangeable potassium in arable and sub-arable horizons of typical heavy loamy chernozem was studied. It is shown that the use of mixed agricultural communities for sideration can be one of the sources of reproduction of potential and effective fertility of chernozems in the Central Сhernozem District. It was found that the influence of the agrocenotic effect in binary mixtures of sunflower with soy, payza, buckwheat of the Krylataya variety and buckwheat of the Demeter variety led to a significant increase in the content of humus, mobile phosphorus and exchangeable potassium in the arable and sub-arable horizons of chernozems under these agricultural communities. It was shown that the effect of the agrocenotic effect on the increase in humus content was equivalent to the introduction of litter manure into the arable horizon of 15.4–25.3 t/ha, in the sub–arable – 13.6–23.0 t/ha. This led to a significant improvement in the quality of the studied soils. An increase in the content of mobile phosphorus under the influence of the mixing factor could be achieved by introducing 88–200 and 88– 138 kg of P₂O₅/ha into the layers of 0–25 and 25–40 cm of soil, respectively. An increase in the content of exchangeable potassium under sideral mixtures in a layer of 0–25 cm of soil by 1.0–2.4 and in a layer of 40–50 cm by 1.7–2.0 mg/100 g of soil would correspond to doses of 300–720 and 510–600 kg K₂O/ha.

The behavior of propineb and propylentiourea (PTU) in apples was studied in dynamics after treatment with Anthracol, water-dispersible granules (WDG) in 3 regions. The determination of pesticide residues was carried out according to developed and optimized methods. It was found that after 3-fold treatment with the fungicide propineb and PTU decompose quickly and evenly in fruits in various regions of cultivation. 28 days after the last treatment, the content of the active substance of the drug and its metabolite are at a level below the corresponding of the maximum allowable level (MAL). At the time of harvesting, the studied substances in apples were not found in any of the climatic zones, as well as they were absent in the juice. Based on the data obtained on the decomposition of propineb in apple fruits, the nature of dissipation was established. The half-life ranged from 3 to 8 days.

Long-term monitoring of the colonization of winter wheat grain by fungal mold pathogens that negatively affect the quality of grain during storage, reducing the quality of seed material, food grains and forage, showed that a high level of occurrence on the grain of Rostov winter wheat samples for the period 2014–2021 was manifested by mold fungi Mucor spp., Aspergillus niger, Aspergillus glaucus, Aspergillus flavus, species of the genus Penicillium. Relatively low occurrence was observed in Rhizopus nigricans and Cladosporium herbarum species. Mold pathogens are producers of the most dangerous mycotoxins: ochratoxin A (species of Penicillium, Aspergillus niger, A. glaucus), aflotoxin B1 (A. flavus), rhizonins (Rhizopus spp.), etc. In the regions of Southern Russia, with severe drought in the soil and on the lower parts of plants, the accumulation of the fungus Penicillium purpureogenum is often noted, for some time it could become dominant. When restoring the level of moisture supply, a decrease in the occurrence of P. purpureogenum was observed, often to zero, and an increase in the occurrence of mucor fungi (Fusarium solani, F. semitectum), non-circulating Mycelia sterilia fungi, etc., a noticeable increase in the total density of fungal colonies. The highest level of external infection of grain was due to colonization of grain by fungi from the Penicillium group, as well as A. glaucus and A. niger, the highest level of internal infection was caused by the Penicillium group, Rhizopus nigricans, A. niger. The dominance of external infection over internal infection was observed during colonization by penicilli and aspergillus, the dominance of internal over external infection by rhizopus and cladosporium.

CO₂-Emissions from agrochernozems of dispersed carbonate Tugnui basin and agrochernozems of quasi-clay Yeravninsky basin of western Transbaikalia were studied. To compare CO₂-emissions from soils, the virgin land variants of the same name are taken. The aim of the study is to quantify and comparatively evaluate the production of carbon dioxide from arable chernozems with contrasting temperature and moisture conditions. The measurement of CO₂ fluxes from the soil was carried out by a closed chamber method with a portable infrared CO₂ gas analyzer AZ 7752 (AZ Instrument Corp., Taiwan). CO₂-emissions were largely dependent on hydrothermal conditions. Its minimum at the beginning of the growing season was associated with the effect of low soil temperatures, the maximum was more often noted after precipitation. The peaks of CO₂-emissions coincided with an increase in temperature and humidity from June to early August, in conditions of a lack of readily available moisture, and were also associated with a humidification regime. The limiting factor of the CO₂ flux for quasi-clay chernozems was the soil temperature, for dispersed carbonate chernozems – humidity. It has been established that the total CO₂-emission in arable soils is significantly less than in virgin soils, this is explained by the peculiarities of the agrogenic environment. Arable soils are warmer in summer, and they cool down more and deeper in winter. The transformation of the water regime occurs in the direction of reducing moisture and increasing its contrast during the warm period. The total carbon loss index varies in a series: dispersed-carbonate chernozem → quasi-clay chernozem, virgin soil → arable land.

The influence of a microbial consortium consisting of the nodule bacterium Rhizobium leguminosarum bv. viciae strain CIAM1079, the associative rhizobacterium Variovorax paradoxus strain 5C-2 and the arbuscular fungus Glomus sp. 1Fo was studied. on the biomass of roots and the formation of mycorrhizal infection in various genotypes of peas grown on fallow sod-podzolic soil contaminated with heavy metals. It was shown that artificial inoculation of plants on average contributed to an increase in mycorrhization parameters by about 4 times. At the same time, in most cases, this practically did not affect the intensity of growth of the root system of plants against the background of soil contamination with toxicants. The use of the neural network data analysis method showed that morphometric indicators were not a reliable criterion for assessing the degree of mycorrhization of a macrosymbiont. The calculation of cognitive significance indices provided a prerequisite for the creation of a program for assessing the ecochemical processes underlying the integral interaction of symbiotic partners in conditions of multiple symbiosis and the stressful influence of environmental factors.

A method for the determination of dithionite iron for soil samples and fractions of the order of 20–25 mg with a spectrophotometric termination has been developed and optimized. Unlike the previously described methods, phenanthroline was used as a chromogen, which made it possible to simplify the analysis by eliminating the combustion stage. The procedure for processing samples with citrate-bicarbonate-dithionite extractant has been optimized. The repeatability and intra-laboratory reproducibility of the technique are investigated. Verification of the proposed methodology by comparison with the standard one showed good convergence of the results.

The review provides literature data on soil bacteria that fix atmospheric nitrogen, solubilize phosphates and synthesize siderophores, thereby stimulating plant growth. The prospects of creating bacterial consortia for application to the soil in order to increase crop productivity and reduce the doses of fertilizers are considered. The use of rhizospheric bacteria capable of fixing atmospheric nitrogen, mineralizing inorganic and organic phosphates, increasing the bioavailability of insoluble iron, as well as their consortia, meets the objectives of sustainable agriculture, increases soil fertility and increases crop yields. The combined use of bacteria that stimulate plant growth with mineral fertilizers makes it possible to reduce the amount of fertilizers applied, which is an undoubted trend in sustainable agriculture. Research on the possibility of using various preparations of soil bacteria that stimulate plant growth has been widely carried out abroad in recent years, these studies are relevant for Russian agriculture, have prospects for import substitution and are necessary to achieve technological sovereignty in this area.