EFFICIENCY OF USE OF MACRONUTRIENTS BY SPRING RAPESEED PLANTS

The relevance of this study is determined by the need to optimize the production process of agrocenoses of spring rapeseed and establish the regularities of the dynamics of macroelements in the soil under the influence of different rates of mineral fertilisers. In this regard, the purpose of this paper was to cover the regularities of changes in the content of macroelements in typical low-humus chernozems at different stages of spring rapeseed culture development in the conditions of the Right Bank Forest Steppe of Ukraine. Field, laboratory, analytical, and statistical research methods were used in the study. It was established that the highest content of macroelements in the soil at all levels of mineral fertiliser is in the phase of leaf rosette formation by spring rapeseed plants (BBCH 15-18). As plants grow through the phases, it decreases and reaches minimum values in the ripening phase (BBCH 85-88). The highest content of nitrogen mineral compounds was noted in BBCH 15-18: 52.0-60.2 mg/kg of soil depending on the fertiliser variant, the content in the variant without fertiliser application – 49.8 mg/kg of soil. It was found that the maximum content of mobile phosphorus compounds in the soil was recorded in the first half of the growing season. It was found that the content of mobile potassium in the soil is dictated by the amount of applied mineral fertilisers. The highest content was noted at the beginning of the vegetation of spring rapeseed, with a gradual decrease until the seed ripening phase (BBCH 85-88). A close correlation was established between the accumulation of dry matter in the BBCH 55-58 period and the yield level (r=0.91). The materials of this paper are of practical value for the improvement of processes related to the development of the productivity of spring rapeseed crops in the conditions of the Forest Steppe of Ukraine, as well as the rational use of mineral fertilisers on typical low-humus chernozems