Soybeans are a leguminous and oilseed crop, the seeds of which contain 32 to 52 % of protein and 16 to 27 % of oil. The increase in acreage is due to the constant demand for this crop as a source of protein of high quality in terms of amino acid composition, used for food, fodder and technological purposes [1, 2].

In the Kursk Region, the planting area of soybeans in 2019 increased to 221.8 thousand hectares, which is 7.6 % higher compared to the previous year. The gross harvest of soybeans in 2020 in the Kursk Region amounted to 496.3 thousand tons, which is 11.7 % higher than the level of the previous year. Obtaining such high rates requires the introduction of modern resource-saving technologies for soybean cultivation. The most important elements of such technologies are the use of highly productive varieties, the introduction of modern plant protection systems, the application of fertilizers, soil cultivation.

One of the most effective measures to increase the yield of soybeans is the application of mineral fertilizers. The effectiveness of their application depends on the timing of application, the type and fertility of the soil, the conditions of moisture supply. In the initial phases of growth and development, soybean plants require fewer nutrients and starting from the flowering phase, especially during the period of pod formation and seed filling, their need for fertilizers increases. During this period, soybean plants consume the maximum amount of nutrients. Soybeans assimilate the highest amount of nitrogen from the budding phase to flowering, when the vegetative mass grows intensively. Phosphorus promotes the establishment of more generative organs and the development of nodules, resulting in improved nitrogen supply. Plants use the greatest amount of potassium in the phase of pod formation and filling of beans [3].

The effectiveness of the fertilizers used for soybeans is determined primarily by the presence of nutrients in the soil, its moisture, and its cultivation. A good return on fertilizers is possible only with their correct application, that is, with the establishment of the optimal rates and ratio of components, the timing of application. It is necessary to apply a mineral fertilizer under soybeans, and in combination with lime on acidic soils. The application of mineral fertilizers at a full rate gives the best effect when it is applied with an optimal ratio of the main macronutrients [4].