In the long residential field experiments revealed the dynamics of total long-humus black soil, depending on the recruitment and placement of crop rotation, tillage, fertilizer type and its dosage. Given the forecast changes to humus content in typical black soil humus under different farming systems main components by 2050. Done age excursion into the past and look to the future in the age cycle. The level of humus accumulation during the execution of various processing systems is most significantly changed in the first years after the beginning of the experiment, then the humus content is stabilized and changes very slowly with time as a result of the transition of humus formation to a quasi-equilibrium state with degradation phenomena. The use of various methods for treating chernozem of typical low-humus for 42 years only led to a delay in the processes of dehumification and to some extent stabilized the mineralization of humus, but did not contribute to its preservation and extended reproduction to the initial level at the time of the experiment. The increase in humus content occurs with respect to plowing and a control option without fertilizers. The increase in the content of total humus for simple and extended reproduction of humus in the secular cycle is equivalent to 20-25 tons per 1 ha and 30-33 tons per 1ha, respectively. To ensure established increases in humus, it is necessary to annually introduce manure 10-12 tons per 1 ha for simple and 14-15 tons per 1 ha of extended reproduction of the total humus content annually.

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Тhe article presents the questions of the relevance of recycling organic matter and biogenic elements that enter the soil as a non-commodity part of the crop (by-products and root residues) depending on the yield of the main crop and crop rotation saturated with cereals, legumes and industrial crops. The share of participation of each culture in the formation of articles of the balance of plant biomass has been established. It was revealed that the recycling of nutrients occurs due to the receipt of leaf-stem mass and roots of corn, the return of nutrients was from the total input in the soil of nitrogen 55, phosphorus 50 and potassium 46%. The optimal crop rotation was calculated with 80% saturation with grain crops (including 20% corn for grain) and 20% technical (sunflower): biomass yield as well as its quantity returned to the soil with plant residues, including root crops 57%, while the share of the removed is the smallest among the studied crop rotations – 43%.

The purpose. To sum up results of long-term investigation in productivity of crops depending on weather conditions during a year, fertilizing and place in different crop rotations. Methods. General scientific and special: field-for determination of effect of technological provisions on soil characteristics, quantity indicators of productivity of different crop rotations; laboratory-determination of quantitative and qualitative indicators of subjects of inquiry using physical and chemical methods; mathematical-and-statistical-for determination of reliability of the gained results. Results. Dependence of high efficiency of some crops on growing after the best precursors is fixed at keeping normative of crop rotation and length of rotation of experimental crop rotations. Conclusions. In conditions of unreliable moistening of Left-bank Forest-steppe for typical black earth the productivity of crops largely depended on weather conditions of a year, place in different crop rotations (3-10field), fertilizing and optimum structure of sown area. With decrease of length of rotation, especially in simplified 2-3-field ones, productivity dropped.