Above-ground residues of sunflower as a source of stocking with an organic matter and nutrients of typical chernozem

The stocking of above-ground vegetative mass of sunflower four varieties and two hybrids depending on the methods of a mineral fertilizer application: at planting, foliar fertilizing and combinations of these two techniques, was studied on typical chernozem in 2008-2011. The results showed that applied fertilizers promoted the increase of air-dry above-ground vegetative mass of plants, compared to control (7.70 t/ha), on 0.25-0.82 t/ha. Using a normative rate of humification of sunflower plant residues, there was calculated that only by availability of such residues, without roots, 1.11-of 1.41 t/ha of humus with compensation of its mineralization under the crops 47.9-48.3 % can be formed in the soil. It is calculated that return to the soil of 7.7 to 9.0 t/ha of air-dry mass of above-ground plant residues brings in 61.8-73.4 kg/ha of nitrogen, 23.1-27.2 kg/ha of phosphorus and 216.7-251.2 kg/ha potassium. Compensation for a carry-over of nutrients is as following: nitrogen up to 79.5-85.3 %, phosphorus up to 75.7-83.0 and potassium up to 748.0-860.5 %.