Restoration of soil fertility and improvement of phytosanitary condition of soil in short rotation of crops in Polissia of Ukraine

With the intensification of agricultural land use and changes in natural conditions, soil quality in Ukraine is deteriorating, with a decrease in humus content, the average annual loss of which is about 0.6 t/ha. Therefore, its reproduction is now becoming increasingly important through the use of organic raw materials and the introduction of legumes into the crop rotation, which leads to a partial replacement of nitrogen from mineral fertilisers with biological nitrogen. The purpose of this study was to find ways to provide the topsoil with organic residues, develop soil microflora, and improve the activity of nitrogen-fixing bacteria in a short grain legume crop rotation. The study was conducted in 2019-2023 using the following methods: visual – to determine the stages of organogenesis; field – to determine the interaction of abiotic factors; physiological – to determine the symbiotic fixation of atmospheric nitrogen. It was found that due to mineralisation of organic residues of legume crop rotation, the amount of macro- and microelements in the soil layers 0-10 cm, 10-20 cm, and 20-30 cm increased by 45.1-46.9-43.1 mg/kg, respectively. It was found that saturation of short crop rotation by 50% with legumes, straw residues, and green manure contributed to the reduction of pathogenic microorganisms and the growth of suppressive ones. It was found that in a short rotation of crops, 10.3 t/ha of organic matter in the form of stubble and root residues, straw and green manure enters the soil, which contributed to the cultivation of environmentally friendly agricultural products with the restoration of soil fertility. The biological activity of the soil during the growing season in the layer of 10-20 cm reached 47.4%, and the content of alkaline hydrolysed nitrogen in the rhizosphere of the root system increased by 43.9 mg/kg. The value of the study lies in the fact that the introduction of short organic crop rotations in farms of various forms of ownership is an innovative approach to providing light grey soils with organic raw materials, restoring and maintaining their fertility, improving their phytosanitary condition, promoting biodiversity, achieving environmental sustainability and high yields