Aim. To study the influence of the main factors of agriculture on the fertility of typical chernozem, productivity and economic efficiency of 5 fallow crop rotations in conditions of unstable moisture in the central part of the Left-Bank Forest-Steppe of Ukraine. Methods. The field, agrochemical (sampling and determination of total humus), statistical and computational (to substantiate the reliability of the results and develop statistical models of interrelationships), the study was conducted at the Drabivske experimental field in a stationary experiment, which was established in 1976, where the comparative effectiveness of different methods of cultivation of typical chernozem in 5 different types of arable crop rotations is studied. Results. The long-term use of moldboardless and surface tillage in a 5-field grain-tilled crop rotation did not lead to compaction of the cultivated soil layer to critical values (>1.35 g/cm3) when the total porosity decreases beyond 50%, which did not worsen the conditions of crop growth and agrophysical conditions of typical chernozem fertility. Under the influence of the main tillage, the redistribution of by-products within 0-30 cm of the soil occurs: under ploughing, by-products are evenly distributed throughout the arable layer, and under no-till tillage, 68-69% of the total mass of by-products is incorporated in the 0−10 cm soil layer, which is 1.72 times more than under ploughing. The total weight of by-products under no-till cultivation was 1.9−2.3 t/ha higher. The type of crop rotation contributed to an increase in the yield of by-products by an average of 1.37 times. In the spring, regardless of the method of cultivation, the same stock of productive moisture in the one-metre thickness (142−145 mm) is accumulated in the 5-field crop rotation, and the moisture content corresponded to the optimal moisture content. Conclusions. On typical low-humus chernozem of the Forest-Steppe of Ukraine, the yield of grain crops depended on a complex of main factors (tillage, fertilizers, predecessors, weather conditions) and amounted to: winter wheat 5.79-6.08 t/ha, corn for grain 9.14−9.39 t/ha, peas 3.42 t/ha, barley 3.48 t/ha. High grain and fodder yields of 4.55 and 9.55 t/ha/ha, respectively, in a crop rotation with 80% grain, including 40% corn, which is 18.3% and 22.5% higher than in a crop rotation with 60% grain saturation. The highest net profit is in the crop rotation with 80% grain saturation, including 40% corn for grain − 14.6 thousand UAH/ha, which is higher than the crop rotation with 60% grain saturation by 5.3 thousand UAH, or 36.3%, with a profitability of 95−68%.
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