Agrohimiâ

In a long-term field experiment on the gray forest soils of the Vladimir opole, the influence of mineral fertilizers and the aftereffect of cattle manure, their interaction on the yield of oats going 2nd crop after the occupied steam, and the dynamics of mobile nitrogen forms under various weather conditions were studied. The determining role of ammonium nitrate nitrogen in the composition of NPK and the aftereffect of cattle manure in increasing the yield of oats has been established. The results of the study indicated that the culture was fed mainly with the nitrate form of nitrogen. A high degree of correlation was revealed between the reserves of N-NO₃ in the soil layer of 0–40 cm, formed as a result of the transformation of soil nitrogen and fertilizers to oat seedlings, and its yield (0.981 > R² > 0.787). The influence of fertilizers and weather conditions on the formation of nitrate nitrogen reserves in the phases of growth and development of oats and their dynamics, ensuring the achievement of high grain yield and quality, are determined. Depending on weather conditions and fertilizer systems, the coefficients of using N-NO₃ formed during the growing season of oats for nitrogen removal by grain (40.7–66.6%), grain and straw (58.3–75.0%), grain, straw and crop-root residues (71.2–88.6%) are calculated. In nitrogen-fertilized variants, on average, at 4 levels of manure aftereffect (0, 40, 60 and 80 t/ha), they were highest when using a single dose of N40P40K40, when using a double dose of N80P80K80, they significantly decreased. On average, at 4 levels of mineral fertilizer application (0, P40K40, N40P40K40 and N80P80K80), the utilization coefficients of N-NO₃ formed during the growing season with the aftereffect of manure of 60 t/ha were maximum. When N80P80K80 is combined with the aftereffect of organic fertilizers of 80 t/ha, the highest losses of N-NO₃ due to denitrification and leaching are possible.

The possibility of accelerating the reaction of meliorant-freshly calcified soil in a solution of 1 n. KCl is shown. Changes in the pH value during 20 days of soil-solution interaction were traced. Differences in the reaction rate have been established when using ameliorants of various chemical nature for liming. It was revealed that the reclamation effect when using silicate materials in the experiment was less than that of carbonate. According to the effect achieved as a result of liming, all meliorants used in the experiment can be arranged in the following descending order: dolomite flour (DF), crushed stone screening (CSS) > > conversion chalk (CC), dolomitized limestone flour (DLF) > blast furnace slag (BFS) > shale ash (SA). Empirical models of changes in the pH_KCl value over the entire experimental interval have been developed for all lime fertilizers. Clustering of individual variants of the experiment, produced by various meliorants, according to their effect on the pH_KCl index over the entire period of study was carried out.

We conducted a comparative study of the effect of mineral and organic fertilizers on the yield and quality of 5 medium-ripened domestic onion varieties in an annual crop on the alluvial meadow soil of the Moscow region. Laboratory and field experiments were carried out by the Department of Agriculture and Agrochemistry of the VNIIO branch of the FNCO in 2020–2022 on sufficiently cultivated medium-loamy alluvial meadow soils of the central part of the Moskvoretsky floodplain. In the experiment with the 5th varieties and the 3rd variants of the mineral fertilizer system, the commercial yield of onions was 53.0 t/ha, whereas with the use of an organic fertilizer system – 58.4 t/ha. Accordingly, the increase in yield relative to the control without fertilizers in the first case was equal to 106, in the second – 117%, marketability – 93 and 95%. It has been established that when determining the need of plants for nutrients during the growing season, it is preferable to use methods of leaf diagnostics. On average, for 5 varieties of onion, the yield increase, according to the results of plant diagnostics, turned out to be 13% more than in variants with NPK doses calculated according to soil diagnostics. Biochemical quality indicators for all onion varieties and all fertilizer variants did not differ statistically significantly from the control. The quality of onion products practically did not depend on the applied fertilizer systems. The organic fertilizer system provided the best supply of nutrients to onions in the phase of the beginning of bulb formation, which was crucial for obtaining the greatest yield in an annual crop. On average, for 3 variants of the organic system, the soil contained 2.34 mg/100 g of mineral nitrogen in the phase of the beginning of bulb formation, whereas with the use of the mineral system – 1.65 mg/100 g, or 42% less.

In 2022, under the conditions of the growing experience of the IHR of the Academy of Sciences of the Republic of Uzbekistan on plants Astragalus babatagi and Astragalus xanthomeloides, optimal sowing dates and options for seed treatment with plant growth regulators and organo-mineral fertilizer were studied. The positive effect of pre-sowing seed treatment was revealed, which significantly affected the increase in seed productivity and plant phytomass. It was found that pre-sowing treatment of Astragalus babatagi seeds with Uchkun plus, Floroxan and potassium Humate Prompter preparations contributed to an increase in seed yield from one bed by 1.0, 0.98 and 0.8 g relative to scarified seeds and an increase in phytomass yield by 189, 197 and 186 g, respectively. The increase in the yield of Astragalus xanthomeloides seeds from one bed in experimental versions using Uchkun plus, Floroxan and potassium Humate Prompter increased by 0.92, 1.05 and 0.62 g, respectively, compared with the “scarification” option, and compared with the control by 1.82, 1.95 and 1.52 g, respectively. The yield of phytomass increased by 53.7, 61.2 and 30.7 g relative to the variant of scarified seeds, whereas in relation to the control these indicators increased by 103, 110 and 79.8 g, respectively.

The features of the structure of mycocenoses of spring barley Gonar in the alienated territories of the Novozybkovsky district of the Bryansk region, contaminated with radionuclides as a result of the Chernobyl accident, have been studied. The study was carried out in 1991–1998 (pollution density ¹³⁷Cs ~1.8 MBq/m2) using traditional field methods of observation and laboratory analyses to identify fungal species and determine their activity. 7 years after the accident, the epiphytic microbiota of barley seeds was characterized by increased activity of fungi from the genus Fusarium with the dominance of the causative agent of snow mold F. nivale Ces. (Microdochium nivale) and the mycotoxic fungus F. sporotrichiella Bilai. (sin. F. sporotrichioides). For comparison, at the same time, the microbiota of barley seeds in the fields of the Ramenskoye district of the Moscow region differed not only in the species composition of fungi, but also in their properties: the absence of such species of fungi as Nigrospora oryzae and Ulocladium con-sortiala, quite numerous in the Bryansk fields, and the presence of micro-roorganisms of the fungus F. sambucinum Fuckel, not found on polluted ¹³⁷Cs and fields removed from economic turnover. There is also a noticeable presence of fungi from the genus Fusarium in the structure of the intra-seed infection of barley. The properties of metabolites of fungi from the genus Penicillium were determined: suspensions of fungal spores P. expansum and P. cyclopium used for processing barley seeds caused depression – a significant decrease in seed germination and morphophysiological characteristics of the development of seedlings. Isolates of 26 species of fungi were screened for their effect on the survival of paramecia and their rating was compiled. It is shown that in the absence of planned management of crop production by regional technologies and the use of plant protection products against diseases for 7 years after the accident, there was a shift in the structure of fungal species present on the roots and stems of barley of the Gonar variety towards an increase in the proportion of phytopathogenic fungi. With a large number of micromycete species on barley plants on radionuclide-contaminated fields of the Bryansk region and “clean” lands of the Moscow region (22 species versus 21, respectively), 9 species of phytopathogens (41% of the total number of species) and 7 species (33%) were isolated in technogenic territories. At the same time, the total activity of phytopathogens in the alienated radioactively contaminated territories was 18 points, in the “clean” ones – 13. Ratio of Phytopathogens/Saprophytes, calculated by the total activity of these groups of fungi, in the Bryansk region was 37.5% more than in the Moscow region, and by the ratio of Phytopath-genes/Antagonists – 2.2 times more. At the same time, the tendency of phytopathogens to prevail over other types of fungi in radioactively contaminated areas was natural, which was confirmed by the results of earlier studies.

It has been experimentally established that when soils are polluted with heavy metals, the boundary concentrations of metals above which signs of ecotoxicity are detected are different for the microbial community. Inhibition of respiration of the studied soils was observed at lower doses of Pb, Zn and Cd than enzymatic cellulase activity. Cd compounds and polyelement contamination conditions are the most toxic for microorganisms. Concentrations of heavy metals have been identified that can have a significant negative impact on the soil microbial community at different levels of contamination of sod-podzolic, gray forest, leached chernozem and chestnut soils. In descending order of resistance to TM, the studied soils can be arranged in the following row: leached chernozem (Luvic Chernozem) > grey forest (Eutric Retisol (Ochric)) > chestnut (Haplic Kastanozem) ≥ sod-podzolic (Eutric Albic Retisol (Ochric)).

A review of publications devoted to the study of the effect of mineral fertilizers on the yield of various varieties of grain crops on various soils is presented. At the same time, special attention is paid to the assessment of the equity participation of various factors in the formation of their productivity. It was found that the greatest contribution to the formation of yield falls on soil fertility, which on sod-podzolic highly cultivated soils amounted to 68–90%, depending on nitrogen doses and varieties, and the share of nitrogen fertilizers varied from 10 to 32%. The coefficient of variation between varieties in terms of yield was in the range of 16–20%. The increase in winter wheat yield from nitrogen application in comparison with the standard Zarya variety ranged from 64 to 146%. In the experiment of VNIPTIHIM, where 33 varieties of winter wheat and 17 varieties of spring barley were tested, the share of the soil fertility factor in the formation of the winter wheat harvest was 81–82, spring barley – 83–89%, the contribution of the variety, respectively, was 6, 13 and 6%.

On ordinary chernozem, its participation in the formation of winter wheat yields slightly exceeded the indicators of sod-podzolic soils, as well as the contribution of fertilizers, despite the introduction of higher doses of mineral fertilizers. The variation in yield depending on the variety was 5–6%. In the experiment on leached chernozem, which was characterized by average agrochemical cultivation, the most productive variety of winter wheat showed a yield 2 times less than that of the previously considered varieties.