Main criteria for evaluation of efciency and contradictions in the process of crop rotation implementation

Abstract

The nature of subjective positioning on the role of crop rotations in agriculture from many points of view, namely – agrochemical, biological, geological and energetic. This leads to the belief that crop rotation arose as a need for reasonable human interaction with nature, a careful attitude to it. However, a comprehensive ecological and biosphere approach to understanding the essence of crop rotation requires the resolution of certain contradictions that arise in the implementation of modern farming systems. Based on the data of long-term feld experiments, the main indicators of the biological cycle of humus carbon in black soil are calculated. The calculation is based on the balance of humus as the difference between the fnal and initial content and reserves in the soil under different crop rotations. We found that the joint application of organic and mineral fertilizers had a positive effect on the balance of humus and nitrogen in the soil and, ultimately, on crop yields and crop rotation productivity. Against this background, a positive balance of humus (+1.29 t/ha) and total nitrogen (+80 kg/ha) in the soil is observed. Strengthening the organic fertilizer system by using, in addition to manure, by-products of crops – cereal straw, peas, corn stalks contributed to the formation of a positive balance of humus and nitrogen in the soil: the annual accumulation of humus was 0.28 t/ha, nitrogen 14 kg/ha. Due to the humifcation of crop residues of cereals, peas and perennial legumes during the 7-year study period in the soil of control crop rotation 1 formed humus 2.85 t/ha, in crop rotation 14 with grasses – 7.0, the rest of crop rotations – from 3.4 up to 4.0 t/ha. In general, 5.5 % of the initial stock of humus or 8.9 t/ha was mineralized in the crop rotation without fertilizers during the specifed period. If we add to this about 3 t/ha of humus, the decomposition of which in the process of mineralization was compensated by plant residues, then during this period decomposed about 12 t/ha of humus. This value of mineralization characterizes the parameters of the biological cycle of humus in the control crop rotation. Key words: soil, fertilizers, crop rotations, crop yield, crop rotation productivity, plant residues, humifcation, humus, humus mineralization, humus balance.