1. SOIL RESOURCES AND THEIR RATIONAL USE 
Grain crops reduce yields on sod-podzolic slightly washed soils by an average of 5–7 % compared to non-eroded soils, on medium- and heavily washed soils by 10–11 and 18–20 %, respectively. The yield deficiencies of rapes on weakly and mediumwashed soils are the same as for grain crops, and on strongly washed soils on average 26 %, in some years up to 30 %. Leguminous crops react most significantly to soil erosion. Their productivity on weakly, medium and strongly washed soils is 10–30 % and up to 40 % lower than on non-eroded soils. On sod-podzolic soils on loess-like loams, the effect of soil erosion on crop yield is less pronounced than on sod-podzolic soils on moraine loams. On the slopes of the northern expositions, the yield of agricultural crops on washed-out soils in relation to unwashed soils decreases more significantly than on the slopes of the southern expositions. The differences are on average 4–5 %.
The article presents the characteristics of the granulometric composition of soils of arable lands in Belarus as one of the main factors of soil fertility, shows the relative fertility of soils of different granulometric composition according to the modern scale of soil assessment points, analyzes the dynamics of the granulometric composition of soils based on the materials of various rounds of large-scale soil survey (I–III round) and cadastral assessment (I–II round), both in the context of regions, and in the country as a whole, and identified trends and reasons for its change.
Screening of zonal isolates Pseudomonas sр. by cultivation on solid and liquid nutrient media with different sources of carbon and phosphorus at background of increasing concentrations of glyphosate resulted in the determination of perspective target objects, which are capable of metabolization herbicide glyphosate as a sole P-source. Screening showed that phosphorus solubilizing rhizobacteria Pseudomonas sр. virtually not capable of glyphosate utilization as sole carbon source for metabolism.
2. SOIL FERTILITY AND FERTILIZATION
The article presents an analysis of the dynamics of organic matter in soils and the distribution of soils of arable and meadow lands by humus content groups according to the latest data of the large-scale agrochemical survey of soils of the republic (2015– 2018). In order to increase the reserves of organic matter, optimal ratios of row crops and perennial grasses in the structure of sown areas are proposed, the need for organic fertilizers is determined and the calculation of possible volumes of production of organic fertilizers and other sources to ensure a deficiency-free balance of humus in the soils of arable lands is given. In the process of applying organic fertilizers, technological aspects of increasing the efficiency of their use are presented.
The article presents the data on the effectiveness of dolomite meal and raw-ground dolomite used in the shift of crops (2019–2021) on sod-podzolic mellow Sandy loam soils (Minsk region), on tilth sod-podzolic light loam and on sandy loam soils andlight loam soils used for pastures (Vitebsk region). The influence of limestone ameliorants on crop yields of crop rotations, their efficiency, the content of nutrients in the principal product, the shift of soil acidity from 1 ton of CaCO3 in 1 year of action and in 1–2 years of their aftereffect is shown. The economic effictiveness (Fertilizer profit) of the use of dolomite meal and raw-ground dolomite in the crop rotation millet (2019)–ats (2020)–barley (2021) on sod-podzolic mellow sandy loam soil has been calculated.
Agroeconomical efficiency of mineral and organomineral systems of winter wheat fertilization with the use of cattle manure and straw is analyzed in the field technological experience. The most optimal for winter wheat on medium-cultivated sod-podzolic sandy loam soil was a fertilizer system, including the application of N70+40+40P65K115 on straw with a compensating dose of nitrogen, which provided a grain yield of 64.1 c/ha with a crude protein content of 14,24 %, gluten – 28,94 %, coefficients of compensation for the removal of nutrients by harvest: N – 1,4, P2O5 – 1,2, K2O – 2,5, conditional net income provided grain is sold as food – 455 USD/ha, the profitability of the use of fertilizers – 195 %, when used for fodder – 71 USD/ha and 31 %, respectively.
The positive effect of complex fertilizers, microfertilizers, growth regulators and complex microfertilizers with growth regulators on the dynamics of biomass accumulation, leaf area, photosynthetic activity and yield of spring wheat has been established. The maximum leaf surface area was noted in the variant with the use of MicroStim-Copper L against the background of N60+30+30P70P120 – 50,1 thousand m2/ha, and the greatest accumulation of dry matter (1488,3 and 1495,2 g/100 plants) was in variants with the introduction of MicroStim-Copper L and Nutrivant plus against the background of N60+30+30P70P120. The values of photosynthetic potential and net productivity were 0,66–0,64 million m2 day/ha and 2,7–2,9 g/m2 day.
Foliar feeding of wheat with micronutrient fertilizers Adob Copper and MicroStim- Copper L against the background of N60+30P60P90 increased grain yield by 4,3 and 5,8 c/ha of grain. Treatment of crops with complex fertilizers Nutrivant plus, Crystalon and Adobe Profit in the tillering phase against the background of N60+30P60P90 gave an increase in the yield of wheat grain of the Bombona variety 6,8, 4,4 and 5,3 c/ha. The use of a new complex fertilizer for spring grain crops NPP grade 16-12-20 with 0,20 % Cu and 0,10 % Mn compared to the variant where used urea, ammoniated superphosphate and potassium chloride were used in an equivalent dose (N60+30P60P90), increased wheat yield by 8,4 c/ha.
The highest yield of spring wheat grain (69,7 and 70,3 c/ha) was obtained with foliar feeding with MicroStim-Copper L micronutrient fertilizer and Nutrivant plus complex fertilizer against the background of N60+30+30P70P120.
In stationary field experiment on sod-podzolic sandy loam soil, the application of increasing rates of potassium fertilizers had a significant effect on reducing the intake of 137Cs in winter triticale grain. The application of N90P60K60 in comparison with the control variant reduced the transfer of 137Cs in triticale grain by 51 % and N90P60K120 by 55 %. The minimum specific activity of grain for 137Cs – 2,29 Bq/kg was registered when N90P60K180 was applied. Route field studies have established a fairly close negative relationship between the content of mobile potassium in the soil and the accumulation of 137Cs by grains of various crops. The content of mobile potassium, at which the minimum accumulation of 137Cs by spring wheat is noted, is 419 mg/kg, barley 413 mg/kg, corn 432 mg/kg and peas 350 mg/kg of soil.
No significant effect of the type of legume component in the legume-cereal grasses on the accumulation of 137Cs in hay has been established. On peat-gley soil, phosphoric and potash fertilizers in rates of R60K180, reduce the activity of 137Cs in the hay of the first mowing by 28–37 %, in the hay of the second mowing – by 23–34 %. Nitrogen fertilizers in a rate of N30 and together with microelements (Si, B, Mo) contribute to a decrease in the concentration of 137Cs in herbs by up to 2 times.
The placement of legume-cereal grasses on peat-gley soils has limitations when using hay for meat livestock. When receiving hay of the second mowing without the use of fertilizers, the permissible density of soil contamination does not exceed 7–9 Ki/km2, when applying only phosphorus and potassium in rates of P60K180 – 8–13 Ki/km2. When using N30-60P60K180 with microelements, it is possible to produce normatively pure grass hay with the participation of lyadvenets at a soil contamination density of 137Cs up to 23–27 Ki/km2, grass hay with the participation of clover – up to 18–20 Ki/km2 and grass hay with the participation of galega – up to 16–19 Ki/km2.
The highest productivity was provided by legume-cereal grass mixture with eastern galega, which amounted to 144,4 c/ha of hay or 75,1 c/ha of fodder units and the payback of mineral fertilizers of 13,9 feed units when N60P60K180 + microelements were applied.
The article presents data on the influence of new forms of complex fertilizers on the productivity (main and by-products), the content of nutrients and the accumulation of 137Cs in spring cereals (barley, oats) in the conditions of 2020–2021 on radionuclidecontaminated sod-podzolic cohesive sandy soil. The promising forms of complex fertilizers with modifying additives have been identified that have a positive effect on the productivity of spring grain crops, with the accumulation of radionuclides below the republican permissible levels.
Corn is one of the most important agricultural crops in the world. A significant accumulation of dry matter, an increase in the productivity of photosynthesis is facilitated by the use of fertilizers, which in turn has a positive effect on increasing the yield of corn.
The experiments also investigated the removal of nutrients by the resulting crop of green corn mass, its quality and chemical composition.
The use of an organomineral fertilizer system contributed to obtaining the highest yield of the green mass of corn, the dry matter content, as well as the highest content of nitrogen and crude protein in it among all the fertilizer systems used. When applying 60 tons of manure + N90+30P70K120 and 60 tons/ha of manure + N90+30P70K120 + MicroStim- Zinc, the yield of green mass was 697 and 737 kg/ha. The maximum amount of dry matter was obtained in the variant using manure +N90+30P70K120+microstim zinc (the sweeping phase is 126.33 c/ha, the milky-wax ripeness phase is 204,66 c/ha), which ensured the maximum yield of the green mass. The maximum content of nitrogen (1,79 %) and crude protein (11,23 %) was in the variant with the use of manure against the background of N90P70K120 + N30. The specific nitrogen removal was maximal in the variants of the manure-mineral fertilizer system (Manure 60 t/ha + N90P70K120 + N30 and Manure 60 t/ha + N90P70K120 + N30 + MicroStim-Zinc (75 g/ha Zn) and amounted to 4,5 and 4,7 kg/10 с.
The specific removal of nitrogen, phosphorus and potassium was lower in the version without the use of fertilizers. For phosphorus, the specific removal in the fertilized variants was quite stable and fluctuated within insignificant limits. The maximum specific removal of copper and zinc was in the variant with the use of foliar fertilization with micro-fertilization of MicroStim-Zinc, Copper and amounted to 4,7 and 25,4 g/10 c, respectively.
The article presents the results of studies for an average of three years with oilseed flax of the Brestsky variety, conducted in the north-eastern part of Belarus on sodpodzolic light loamy soil. In field experiments, the influence of the integrated use of mineral fertilizers, plant growth regulators and biological products on the yield and quality of flax products was studied.
The most effective was the use of brassinosteroids (epin and homobrassinolide) in two doses: with seeds during their encrustation and spraying of crops in the «herringbone» phase against the background of a full mineral fertilizer at a dose of N45P60K90. At the same time, the yield of seeds was 16,7–17,2 c/ha with an oil content of 49,7–50,1%; the yield of straw was 41,7–42,3 c/ha with an average number of 0,5– 1,0 units. The high efficiency of flax seed inoculation with binary microbial preparation Biolinum against the background of complete mineral nutrition (N45P30K90) was noted. At this level of nutrition in the experiments, an average of 17,6 c/ha of seeds with a fat content of 50,8 % and 42,2 c/ha of straw with an average number of 0,75–1,00 units were obtained over three years.
The most effective level of application of organic and mineral fertilizers (60 t/he of manure + N120P80K160) ensures the formation of optimal indicators of the production process of valerian plants (biological mass, leaf surface area, chlorophyll content) causes the formation of the maximum yield of roots and rhizomes within 38,8– 61,6 c/he, the increase in the extractivity of raw materials in 1,21–1,46 times more than the standard, the increase in ash content and the amount of nitrates does not exceed the maximum permissible parameters.
