The purpose of paper is to study the effect of long-term (more than 10 years) application of organic and mineral fertilizers on humus content, its fraction-group composition in ordinary chernozem, and crops productivity of grain-fallow row crops rotation. The research was carried out in the Don Zonal Research Institute of Agriculture. To solve the given problem, the humus content was analyzed by the following parameters: total humus and its fraction-group composition, carbon balance, crop yields of ten-field grain-fallow row crops rotation under the influence of organic and mineral fertilizers in doses of 7.0 tons of manure N43P30K24 on 1 ha (option 2) and 11.2 tons of manure + N64P42K42 (option 3) were determined. During the crop rotation period, the loss of humus (C) in unfavorable soil was 0.05 %. The ratio of humic and fulvic acid (from 2.0 to 2.1) has widened, the degree of organic matter humification has decreased from 41 to 40 %. The amount of insoluble residue increased from 0.91 to 0.94 %. The fraction of humic acid had no significant changes, the fulvic acids content and the 1a, 1, and 3 fractions of their composition decreased, the second fraction increased. The dose of 7 tons of manure + N43P30K24 increased the carbon content by 0.03 %. The ratio of humic and fulvic acid has increased to 2.1, the degree of humification has risen up to 42 %. The improved system increased the carbon content by 0.09 %, including humic acids – by 0.10 % due to the 2nd fraction; fulvic acids – by 0.03 %. The ratio of humic and fulvic acid became 2.2, the degree of humification became 44 %. The amount of insoluble residue decreased insignificantly. Crop yields varied depending on their biological characteristics, doses and fertilizer systems. On a natural background, the carbon balance under all crops is negative, with the exception of winter rye (+96 kg/ha). The average fertilizer system did not give positive carbon balance, the improved one brought the balance to the deficit-free. The largest energy income is 1105 GJ/ha in the variant with the increased doses of fertilizers.
Keywords: ecological state, humus, mineral, organic fertilizers, humus balance, humic acids, fulvic acids, crop yields, bioenergetic efficiency.
