Today Ukraine is one of the largest producers and suppliers to the foreign market of sunflower oil and seeds. This culture is in constant demand among processing companies and exporters, has a high purchase price and level of profitability. Due to this, the area of sunflower crops has significantly expanded on the territory of Ukraine. Among farmers there is a need to use this crop as a precursor for cereals. An important measure in improving the yield and grain quality of winter wheat is the application of mineral fertilizers. Only by providing the plant with a sufficient amount of nutrients during the growing season can you get a significant harvest with good technological properties of grain. Therefore, when developing the technology of growing field crops, special attention should be paid to the system of their fertilization. The nutritional value of winter wheat and the quality of bread ultimately depend on the content of gluten and protein in the grain, the main structural element of which is nitrogen, so for the formation of high quality grain plants need this nutrient Lack of nitrogen during the period of intensive plant growth disrupts the entire course of physiological processes. Nitrogen may be sufficient to maintain active photosynthesis and carbohydrate formation, but not enough to form good quality grain. Particular attention should be paid to plant nutrition when caring for crops. Many years of research and practice of advanced farms have shown that early spring fertilization of winter crops with nitrogen fertilizers is one of the most effective methods of managing the growth and development of plants, improving yields and grain quality. Such fertilization stimulates growth processes and increases grain yield by 7-9 c / ha and more. Many years of research by scientists in different soil and climatic zones of Ukraine have shown that about half of the increase in grain yields can be obtained through the efficient use of mineral fertilizers by plants, and to improve the quality of winter wheat grain is extremely important nitrogen fertilizers. According to the three-year data of IOC NAAS, the best results of winter wheat yield in Antonivka variety (3,37 and 3,52 t / ha) were obtained when growing it on sunflower, when against the background of N40R40K40 nitrogen was additionally applied on frozen soil in the dose of N60 and N90. Field experiments were conducted in 2016–2020 in the crop rotation of the Laboratory of Agricultural Engineering of Grain Crops of the Institute of Oilseeds of NAAS. Predecessor - sunflower. Repetition - four times, the size of the test area is 24 m2 (16x1,5). Plant protection measures - taking into account the ecological threshold of harmfulness. The research was guided by the method of research of B.O. Dospekhov and methodical advice of the Research Institute of Maize for field experiments with cereals, legumes and fodder crops. They sowed a variety of winter soft wheat Gurt. Sowing was carried out on September 25 with a selection seeder SKS-6-10 with a sowing rate of 4,5 million / ha of similar seeds. Seed wrapping depth 5–6 cm. Sowing method - continuous row. Mineral fertilizers were applied according to the experimental scheme: without fertilizers; N40Р40К40 (nitroammophoska) - background (for pre-sowing cultivation); background + N30 on permafrost soil; background + N60 on permafrost soil; background + N90 on permafrost soil. The aim of the research was to study the influence of nitrogen mineral fertilizers on winter wheat crops according to the predecessor of sunflower in the conditions of the southern steppe of Ukraine. According to the results of research, the winter wheat variety Gurt formed the highest yield (3,57 t / ha) in areas against pre-sowing application N40R40K40 with subsequent fertilization of crops with nitrogen (N90) in early spring on permafrost soil. In general, the yield formed by winter wheat in areas with the use of fertilizers by 0,42 – 1,23 t / ha is higher than in areas where nitrogen fertilization was not carried out. The obtained experimental data show that the grain quality of winter wheat during the research period significantly depended on the use of nitrogen fertilizers. The highest content of protein 11,0 – 11,3 % and gluten 19,3 – 20,3 % in the grain of winter wheat was obtained in areas on the background of pre-sowing application N40P40K40 followed by fertilization N60 and N90 on frozen-thawed soil, while the grain was formed III class of quality. With a decrease in the dose of mineral fertilizer to N30, the protein content in the grain decreased to 10,4 %, and the amount of gluten - up to 17,3 %. Without the use of fertilizers, these indicators were the lowest and amounted to 9,2 – 9,3 % and 14,9 – 15,4 %, respectively. Analyzing the economic indicators in the cultivation of winter wheat on the predecessor of sunflower, it should be noted that mineral fertilizers were the main factor that most significantly affected the level of productivity of this crop, and hence the economic and energy efficiency of its production. Production costs per 1 hectare of sowing varieties of winter wheat, depending on the level of mineral nutrition were: from 9508 to 14194 UAH. The greatest economic indicators in the cultivation of winter wheat after sunflower provided sowing in variants on the background of pre-sowing application N40P40K40, followed by fertilization N60 and N90 on frozen-thawed soil. Under sowing under these conditions received the highest profitability, which was in the variety Group 58,5 – 59,4 %. The profit was 7955,0 – 8297,0 UAH. in accordance. The minimum value of the level of profitability of grain production (22,1 %) was in the variants where mineral fertilizers in the dose (N40P40K40) were applied in the background without fertilization. Studies have shown that the lack of nitrogen in the soil can be compensated by scientifically sound use of mineral fertilizers, which leads to increased yields and improved many indicators of wheat grain quality.
