Agrohimiâ

Based on the results of many years of field experience, an agronomic and economic assessment of the effects of the use of chemicals for spring wheat is given in order to determine the attractiveness for farmers of the transition to growing crops using intensive technology. For the analysis, the prices of chemicals and spring wheat grain that are currently relevant for the Siberian region were taken. It is shown that under the influence of a complex of chemicalization agents (fertilizers, herbicides, fungicide), the average annual yield of wheat in a 4-full grain-pair crop rotation increased 1.8 times, reaching 3.8 tons of grain/ha. The increase in yield by 13% was due to the use of herbicides, 18% – fungicides and 69% – mineral fertilizers with a payback of 1 kg active substance 12.4 kg of grain. When calculating the average per year, the means of chemicalization provided income already at the minimum (from the accepted for analysis) grain price of 10 000 rubles/t. Income increased sharply in a number of field experience options: herbicides, herbicides + fertilizers, herbicides + fertilizers + fungicide. However, when assessing the annual effects, income from chemicals in this series was obtained, respectively, only in 42, 75 and 92% of the years. The probability of losses decreased significantly with an increase in the price of grain. But even at prices of 13.000 and 16.000 rubles/ton, the use of the entire complex of chemicals was unprofitable in 8% of the years due to the severe aridity of the growing season. At current prices for fertilizers and pesticides, the minimum sufficient price of grain can be considered 13.000 rubles/ton, which, however, does not exclude losses in severely dry years.

The study was conducted in the Voronezh FASC “Kamennaya Steppe” in 2020–2022. The assessment of the state of the structure of microbial cenosis in meadow soils with the use of various chemical meliorants is given. Options for reclamation included the introduction of gypsum and defecate at a dose of 5 t/ha and a combination of their half doses. The number of ecological and trophic groups of microorganisms was determined by seeding on solid nutrient media. Accounting for organisms assimilating organic forms of nitrogen – by sowing on meat-peptone agar (MPA), accounting for organisms assimilating mineral forms of nitrogen – by sowing on starch-ammonium medium (SAM), accounting for organisms mineralizing humus – by sowing on nitrate agar, accounting for fungi – on Chapek medium, accounting for the amount of nitrogen – on soil plates, accounting for nitrifiers – on hungry agar, accounting for organisms that decompose fiber – on Vinogradsky’s medium. As a result of chemical reclamation of meadow soils with the use of gypsum and defecate as meliorants, patterns of changes in the activity of soil microorganisms were established. It was possible to identify a fairly clear dependence of the increase in the number of microorganisms that utilize organic forms of nitrogen on the use of meliorants in meadow soil of a hollow-shaped depression. Mineralization processes of organic matter were maximally expressed in meadow-chernozem soil on a plain rise when gypsum was used as a meliorant at a dose of 5 t/ha, while the use of gypsum and defecate at a dose of 2.5 + 2.5 t/ha had a greater effect on the content of nitrifiers in this soil. In the chernozem-meadow soil of a hollow-like decrease, the use of defecate at a dose of 5 t/ha led to an increase in the content of actinomycetes. In the chernozem-meadow soil of the plain depression, the use of all meliorants had an impact on the increase in the number of humus mineralizers, fungi, as well as nitrifiers compared with the control. It was not possible to identify any significant pattern associated with the use of meliorants on these soils for the maintenance of azotobacter colonies. In soils with different degrees of soil moisture, the use of meliorants had an ambiguous effect on the number of cellulolytics: an increase in soil hydromorphism in combination with the use of defecate at a dose of 5 t/ha led to a maximum increase in cellular microorganisms in the chernozem-meadow soil of a hollow-like decrease.

The results of the vegetative experiment on the establishment of the joint effect of the biological preparation Rhizotorphin and N-fertilizer (doses N_0.05, N_0.10, N_0.15, N_0.20, N_0.25) on the formation of vegetative mass and the yield of seed pea grain when cultivated on weakly and medium cultivated sod-podzolic soil are presented. With an increase in the dose of N-fertilizer from N_0.05 to N_0.25, an increase in the yield of green mass of peas was observed by 3.4–22.2 g/vessel (on poorly cultivated) and by 10.3–35.5 g/vessel (on medium cultivated soil). The increase in grain yield from the use of Rhizotorphin on average in the experiment was 1.31 g/vessel on weakly and 1.66 g/vessel on medium cultivated soil. The application of N-fertilizer in medium cultivated soil conditions increased the responsiveness of seeded peas to inoculation to 1.70–1.87 g/vessel. When using Rhizotorphin and applying N-fertilizer, the accumulation of N in pea grain increased by 0.22 and 0.18% in accordance with the degree of cultivation of the soil. When using Rhizotorphin, N was accumulated in the roots, which positively affected the preservation of their activity and functioning at later stages of development, the intake and accumulation of N in the forming grain. The biological preparation Rhizotorphin influenced the accumulation and distribution of consumed N between the main and by-products of pea plants. Due to this, in the budding phase – the beginning of flowering, the dose increased to 0.83–0.88, and 38.0–65.5 mg N/vessel was additionally accumulated in the pea grain. With an increase in the dose of N-fertilizer over 0.05 g/kg on weakly and 0.20 g/kg on medium cultivated soil, the process of forming a symbiotic apparatus on the root system of peas was completely suppressed.

Experimental data on the accumulation and loss of organic carbon in sod-podzolic soil over 6 rotations of a long stationary experiment are presented. It was found that during the growing season during photosynthesis, spring barley plants were bound into organic compounds 2.84–3.25 t/ha from the atmosphere (10.3–11.6 t CO₂/ha) during the growing season, meadow clover of the second year of use – 4.23–5.19 t C/ha (15.1–18.6 t CO₂/ha) depending on the experience options. During the rotation of the 8‑field crop rotation, cultivated crops were sequestered from the atmosphere 82.28–99.31 tons of CO₂/ha or 22.4–27.1 tons C/ha, depending on the soil fertilization system. Long-term use of arable land without fertilizers led to a decrease in the carbon content in the soil by 13.5% relative to the initial level. The soil of the stationary experiment was characterized by the maximum content and reserves of organic carbon when the arable land was saturated with manure at a dose of 20 t/ha and an equivalent amount of NPK. The carbon content for 6 rotations of crop rotation increased in the 0–20 cm layer by 15% of the initial one, carbon reserves in this layer increased by 5 t/ha, in the 0–100 cm layer – by 32.0 t/ha. The average value of the carbon-protective capacity of the studied soil varied from 29 to 31 g/kg in a layer of 0–20 cm of soil and did not depend on the applied fertilizer systems. The quantity and qualitative composition of biomass entering the soil with its various fertilizers had a significant impact on the accumulation of organic carbon.

The effect of lead on the amino acid composition of annual fodder grasses was studied. It was found that in response to soil pollution in plants, the content of nitrogen and amino acids in the composition of proteins increased. Significant changes in the content of nitrogen and most amino acids in the legume plant occurred at a content of mobile lead from 2.2 to 10.0 mg/kg. The contamination caused an increase in the relative content of proline and aspartic acid and a decrease in the proportion of glutamic acid in pea proteins. In the biomass of oats, the relative content of aspartic and glutamic acids has increased, the proportion of proline has decreased. Starting from the concentration of lead in the soil of 5.5 mg/kg, the proportion of essential amino acids in the proteins of the legume plant decreased.

The possibilities of optical emission spectrometry with inductively coupled plasma (OES-ICP analysis) (in radial plasma observation) of humic preparations (HP) are evaluated, the proposed technique allows quantifying up to 24 elements (As, Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, Si, S, Sr, Ti, V and Zn). The list of these elements will allow determining the value of such preparations for soil nutrition, and will also help to avoid danger if the content of toxic impurities in them goes beyond their maximum permissible concentrations. In the absence of standard samples with certified contents of the elements to be determined, the correctness of the analysis for the macrocomponent composition is confirmed by comparing the results of gravimetric determination of the ash content of the studied objects with the calculated data obtained when processing the results of OES-ICP analysis. Systematic errors in the determination of trace impurities were minimized by using the method of adding standard solutions (from matrix influences), as well as 6 parallel measurements of samples prepared independently of each other. The correctness of the methodology was also evaluated by using model solutions close to the possible micro-impurity mineral composition of HP using the Student’s t-test. The results obtained for the isolated fraction of humic acids are compared with the literature data.

The review considers the application of agrogeochemical technologies aimed at restoring agrogeochemical cycles in agricultural ecosystems, primarily in the microbial link regulating CO₂ flows. The factors of management of this microbial link in the application of both mineral and organic fertilizers are shown. The processes of mineralization of soil organic substances and methods of regulation of the conjugate carbon- and nitrogen-mineralizing ability of soils are considered. Changes in the productivity of agricultural ecosystems under conditions of increasing the concentration of carbon dioxide in the atmosphere and in the soil air are considered. Various agrotechnological techniques are shown, including the use of zero tillage, organic fertilizers of various nature, as well as various meliorants, including phosphogypsum. Based on numerous data, it is concluded that agroecosystems in most cases are a pure source of CO₂, and sequestration occurs only when agricultural land is transferred to fallow lands. Methods aimed at reducing CO₂ fluxes when using fertilizers in the “production–application” cycle are evaluated. It is shown that the existing practice of introducing agricultural low carbon technologies (agricultural low carbon technologies – ALCT) cannot yet indicate their applicability to ensure both food and environmental safety.