Evaluation of the degree of degradation of chernozem soils of the Central Chernozem region and justification of selection of optimal methods of main soil treatment

The goal of the conducted research was to upgrade the scale of degradation of chernozem soils and determine threshold parameters of the complex of agrophysical indicators of fertility in the context of minimizing main soil treatment. The object of the study was leached and ordinary chernozem. The studies were conducted in short-term and long-term stationary experiments according to standard techniques. Analysis of soils and vegetation samples were carried out according to conventional methods of agrophysical, biological and agrochemical research. In long-term experiments the authors determined basic agrophysical indicators of fertility used for the evaluation of the degree of soil exhaustion: soil density (g/cm3), soil hardness (kg/cm2), the content of aggregates of more than 10 mm (%). Due to attained results the authors propose a rating scale of the degree of chernozem soil exhaustion and the adaptability of soils for minimizing main soil treatment. The authors estimated values of the degree of soil exhaustion (Š) depending on agrophysical indicators of fertility, cultivated agricultural crops, field fertility differentiation, substantiated systems of main soil treatment in crop rotation, proposed to consider several levels of the coefficients of agrophysical indicators of fertility (а1, а2, а3) depending on the degree of soil exhaustion, concrete agricultural crop and individual characteristics of each field or even its parts. On medium (Š=0.80-0.97) and heavy (Š=0.98-1.50) plowed chernozem soils the following systems of main soil treatment in crop rotation are recommended: moldboard plowing, boardless plowing, intended for different depth combined with maximum application of biologization methods in crop rotation (green-manured fallow, stubble crops, perennial grasses, trash cover farming, manurial treatment and application of defecate) in combination with recommended doses of mineral fertilizers.