Crop rotation productivity depending on the applied fertilization systems and their payback on ordinary carbonate chernozems of the Central Ciscaucasia

Modern environmental problems that have arisen as a result of anthropogenic overload and irrational use of natural resources have undoubtedly affected the state of the soil cover. As a result of improper land use, there is a change in chemical properties that determine the availability of nutrients. Water and wind erosion, dehumification, changes in acidity, liming of soils, waterlogging and eutrophication, excessive and improper use of pesticides, chemical, biological and organic fertilizers have led to a deterioration in the quality of the land and, accordingly, a decrease in fertility, and this, in turn, leads to land degradation. The significant degradation of chernozems and other soils in recent years, caused by the intensive use of arable land and increased mineralization, requires the improvement of farming systems aimed at preserving soil fertility. Solving the issues of reproduction of soil fertility and its rational use in agriculture is the primary task of agricultural science. In the problem of regulating soil fertility, the main role belongs to scientifically grounded crop rotations, which are the basis for the effective use of soil cultivation systems, fertilizers, plant protection and other measures. Crop rotations make it possible to increase the efficiency of soil fertility, regulate food, water and air regimes of the soil, suppress weeds, pathogens and plant pests, without requiring additional material costs, which is very important for obtaining environmentally friendly plant products and reducing its cost. In this regard, increasing the efficiency of the application of fertilization systems in crop rotations, which are able not only to replenish and maintain the achieved level of humus in the soil, but also to increase the yield of crops and, accordingly, the productivity of 1 hectare of the crop rotation area, is relevant. It depends on the yield of crops, their varietal characteristics, as well as weather conditions. This paper examines the research results for 2018-2020 on the change in the productivity of crop rotation and its payback depending on the applied fertilization systems on dry land and during irrigation.