Fertilization of field crops and maintenance of soil fertility by mineral fertilization only do not secure a positive balance and ratio of nutrients and humus in arable farming. In 2009-2018, a long-term field experiment of four-crop rotation system (winter oilseed rape – winter wheat – grain maize – spring barley) determined the efficiency of using phytomass residues (including the application of N10 ammonium nitrate per 1 ton of the previous crop straw). The experiment was conducted on dark-grey podzolic soil (Luvic Greyic Phaeozem – WRB (2015) with a 1.9% share of humus, 99 mg kg-1 of alkaline hydrolyzable nitrogen (by Cornfield), 105 and 71 mg kg-1 of mobile phosphorus and exchangeable potassium (by the Kirsanov method), respectively. The work demonstrates agro-chemical and physical-chemical transformations in soil and determines changes in the yield of crops grown in a crop rotation system. The use of a non-marketable component of the yield of winter wheat, grain maize, spring barley and winter oilseed rape (phytomass residues) for fertilization secured replenishment of the soil with  46.0 kg ha‑1 of nitrogen, 7.9 kg ha-1 of phosphorus and 75.5 kg ha-1 of potassium per 1 ha of crop rotation that accounted for 15.9; 15.9 and 37.0% of their total loss, respectively. With the combination of mineral fertilizers and by-products, a positive balance of nitrogen, phosphorus and potassium was achieved with amounts of 24.4 15.1 and 42.7 kg ha-1 of the nutrients, respectively. Supplementing the mineral system of fertilization with phytomass residues as a fertilizer secured an increase of the amount of alkaline hydrolysable nitrogen by 5.1%, mobile phosphorus – by 4.6, and exchangeable potassium – by 103.5%, as compared to the pure mineral system of fertilization. However, it is necessary to control physical and chemical properties of the soil, and to maintain the reaction of soil solution within the optimal limits.   

26.2.2021