Normatives of changes in the physical properties of chernozems in the forest-steppe zone of European Russia under conditions of their intensive agricultural use

Normatives of changes in the physical properties of plowed typical and leached heavy loamy and light clayey chernozems under their intensive agricultural use are developed for two major provinces of the forest-steppe zone of European Russia. The limits of the optimal, permissible, and critical values of the physical properties of the plow layer for crop growth are determined. It is shown that the variation in the physical properties of the plow layer of chernozems is determined not only by the zonal-provincial features but also by the period and type of their use and the farming standards. In the plow layer, the natural differences in the physical properties of chernozems at the subtype level are significantly leveled by agrotechnical measures and the similar requirements of cultivated crops. Upon high farming standards, the physical properties of plowed chernozems on fields with high and moderate fertility levels remain close to the optimum or permissible values. The technogenic compaction of the plow layer of chernozems of different textures in the forest-steppe zone and the corresponding decrease in the yield of cereals are predicted on the basis of known models. The developed normatives of changes in the physical properties of cultivated chernozems can be applied to assess the modern state of the physical conditions of these soils and the tendencies of their alteration; they can serve as a basis for improving regional systems of land use.