THE ROLE OF ORGANIC FERTILIZERS (STRAW, GREEN MANURE, CROP-ROOT REMAINS) IN HUMUS REPRODUCTION AND PRESERVATION IN THE SOIL

The paper presents results of thestudies on assessment of the role of organic substances created in crop rotation agrocenoses and used as fertilizer for agricultural crops (straw, green manure, crop- root residues). The studies were carried out in a five-field grain crop rotation with alternation: vetch-oat mixture as a green manure crop - winter wheat - millet - spring wheat - barley. The scheme of the experiment consisted of six variants with application of organic, organo-mineral and mineral fertilizers: 1. Control (green manure); 2. Straw of the forecrop; 3.Straw of the forecrop+ 10 kg of nitrogen (urea) per 1 ton of straw; 4.Straw of the forecrop+ Biocomposite-correctbiological preparation; 5.Biocomposite-correctbiopreparation; 6. NPK (doses of fertilizers for the planned yield of winter wheat 4.5 t/ha, millet 4.0 t/ha, spring wheat 4.0 t/ha, barley 4.0 t/ha). It was found that usage of straw as an organic fertilizer contributes to an increase of crop yields in the first year of application. Its effectiveness is greatly increased in combination with a nitrogen supplement and a biological product: the increase of grain yield was (depending on crops) from 0.19 to 0.51 t/ha. The amount of organic matter entering the soil per 1 hectare of crop rotation area in case of combined usage of green manure, straw and crop-root residues was 2 times higher than the control variant (green manure). Complete reproduction and preservation of humus content is possible in case of combined usage of green manure, straw, crop- root residues and biological preparations as organic fertilizers in order to improve the conditions of their decomposition.