Agrogenesis of regraded chernozem and the performance of grain crops under organic system of fertilization

Aim. To conduct complex agrophysical, physical-chemical substantiation of the effi ciency of the organic fer- tilization system in terms of nitrogen balance and organic carbon in the agroecosystem of a fi ve-fi eld grain- growing and weeding crop rotation fi lled with cereals and legumes up to 40 % and the use of by-products for fertility restoration and improvement of the agrogenesis of regraded chernozem in the central part of the Forest-Steppe of Ukraine. Methods. Laboratory-analytical, experimental fi eld, computational, statistical. Results. The systematic application of the organic system of fertilization in a short grain-growing and weeding crop rotation with the use of by-products as organic fertilizers promotes the increase in the points of exchange neutrality and the decrease in the unsaturation of regraded chernozem with the alkali of the tilled layer, while the increase in microaggregation and structure-building is conditioned by the approximation of potential acid- ity to the isoelectric state of soil colloids which is a feature of the process of biologization and simulation of natural soil formation in agroecosystems of the central part of the Forest-Steppe of Ukraine. Under the organic fertilization system the decrease in the agroecosystem performance is related to the decrease in the volume of nitrogen balance which testifi es to the decrease in the intensity of its circulation in agroecosystem: the processes of enhancing the humifi cation of by-products and the formation of prohumus substances prevail, ac- companied with the intensifi cation of atmospheric CO 2 involvement in the formation of the total phytomass of the harvest, and the agroecosystem transforms into a stock system, which may be characterized as a basic sys- tem for organic production of plant cultivation. Conclusions. The elaborated system of organic fertilization of crops in a fi ve-fi eld grain-growing and weeding crop rotation allows avoiding the use of organic fertilizers and perennial grasses and using by-products of plant cultivation instead to saturate the crop rotation with legumes up to 30–40 %, the application of nitrogen-fi xing and phosphate-mobilizing preparations allows ensuring the production of organically pure products with simultaneous restoration of both fertility and the natural model of the chernozem agrogenesis of the central part of the Forest-Steppe of Ukraine.