The purpose of the research was to establish the reason for the decrease in the productivity of crops grown in the experiments under replacing the main processing of moldboard plowing with flat-cut loosening to appropriate depths based on a review of the literature and our own experiments conducted on podzolized chernozem in a fve-feld crop rotation of soybeans – spring rape – spring wheat – oil flax – spring barley. According to the research data, the average yield of 15 crops decreased by 9.0 % due to such replacement. In our experience, the average yield of spring crops decreased by the same amount. Such a decrease in the yield of crops cultivated in different experiments against the background of flat-cut cultivation instead of plowing could not be caused by a deterioration in the physical condition of the soil due to the absence of the latter, sinse in 15 experiments, according to the literature data, the density of the addition of the arable layer of different soils changed only by 0.7 % and the content of agronomically valuable structures – only by 0.1 %, and in our experience – respectively by 2.1 and 1.4 % (towards improvement). The total soil permeability in the arable layer also decreased by 1.9 % in our study due to the use of flatcut tillage instead of fall plowing, while remaining within the acceptable range. Changes in the water regime related to the change in the method of basic soil cultivation could not negatively manifest at the level of productivity of crops cultivated in different experiments. In addition, only in fve publications out of 15 the reserves of available moisture in the root layer decreased due to replacing moldboard cultivation with non-moldboard loosening, and in the rest 10 ones they remained unchanged or they increased signifcantly. Therefore, the reserves of soil moisture available against the background of flat-cut loosening were 1.7 % higher in comparison with plowing. In the experiment, the advantage of flat-cut cultivation over plowing in terms of available moisture reserves in a meter layer of soil at the middle and end of the growing season of spring crops increased to 6.1 and 6.4 %, respectively. The average productivity of crops cultivated in crop rotation against the background of flat-cut cultivation was signifcantly (by 9.0 %) lower in comparison with plowing. The reason for this could be almost a third (by 27–31 %) higher infestation of crops after the moldboard-free main autumn tillage.

Key words: fve-feld crop rotation, physical condition of the soil, reserves of available moisture, crops weediness, crop yield.