Condition of humus in leached chernozem and aftereffect of fertilizers for their long-term use in crop rotation chains

Abstract

Purpose. To investigate the humus condition and the effective fertility of leached black soil in the aftereffect of crop cultivation for more than 40 years applying organic and mineral fertilizers in grain crop rotation chains.Methods. Long-term field and analytical.Results. The results of studies on the effect of 40-year organic and mineral fertilizers application on the status of humus of leached black soil and the productivity of crops in cereal chains of crop rotations grown in the aftereffect of fertilizers. Under application of traditional and alternative organic-mineral fertilizer systems, the humus content in arable 0–30 cm and subsoil 30–40 cm soil layers were determined. Close links have been established between the status of the leached black soil humus, crop yields and the fertilizer application system.Conclusions. The highest intensity of humus formation processes in the leached soil was achieved during the 40-year fertilizer application (N43P43K43 + 8.3 tons of manure per 1 ha of crop rotation) in crop-changing rotation: humus content in the 0–30 cm layer of 3.52 %, 30–40 cm of 3.28 % with excess to control without fertilizers by 0.36 % and 0.22 %. In the grain-hoed crop rotation, the specified fertilizer system was accompanied by a decrease in the humus content in the arable layer by 0.07 %, and the subsurface one by 0.02 %. The decrease in the intensity of humus formation was observed with an alternative organic-mineral fertilizer system (N43P43K43 + by-products). Compared to traditional manure-based fertilization, a content of the humus in 0–30 cm layer was decreased by 0.10 %, in 30–40 cm by 0.02 % with its absolute content value, respectively 3.42 % and 3.26 %. In the crop-changing crop rotation, growing clover and spring barley in the aftereffect of organic and mineral fertilizers was accompanied by a significant increase in the yield of both crops by 14.7–16.0 and 0.82–1.04 t/ha, respectively, whereas in the grain-hoed crop rotation only by an increase in the yield of spring barley by 0.98–1.00 t/ha. Spring vetch in grain-hoed crop rotation did not respond to the aftereffects of fertilizers. The highest yields of clover and spring barley were obtained after the application of N43P43K43 + 8.3 tons of manure per 1 ha of crop rotation area and amounted to 33 and 3.45–3.56 t/ha, respectively.