The article presents the results of studying the dynamics of the formation of the root and above-ground mass of spring soft wheat, virgin and fallow cenoses under the conditions of 2012 and 2018. The dynamics of the placement of the root system of cultivated plants in the grain-pair crop rotation over the vegetation phases was revealed. It was shown that spring wheat forms the secondary root system during the growing season only in favorable meteorological conditions, mainly within the 0–50 cm layer (74%). In the absence of significant precipitation in the period from May to July, the drying out of the upper layer of soil causes the oppression and death of the spring wheat even in the presence of sufficient moisture and nutrients in the lower horizons. The deposit tends to the virgin soil on the uniformity of the development of the soil profile roots. For virgin lands, the ratio of the mass of roots to the mass of the above-ground part is from 1.71 for a meter-thick layer of soil to 1.78 for a 1.5-meter-thick layer, for a deposit it is 0.96–1.03. For grain crops, the ratio of the mass of roots to the mass of the above-ground part is narrow – in the range of 0.22–0.27, which makes them extremely dependent on the ecological conditions of growth.