Usage of after-harvesting plant residues of soybean to compensate utilization of humus, nitrogen, phosphorus, potassium with seeds yield
Accumulation of dry overhead biomass by soybean plants, consumption of nitrogen, phosphorus and potassium by seeds and vegetative mass under application of mineral fertilizers were studied crop rotation soybean - winter wheat on leached chernozem in 2015-2016. Applied fertilizers caused increase of plants vegetative mass accumulation compare to control variant without fertilization by 0.31-0.37 t per ha. Usage normative coefficient of humification of leguminous plant residues allowed calculating extra humus formation at the rate about 0.88-0.95 t per ha after application of chopped residues into soil and compensation of its consumption under soybean 42.4-43.1%. Return into soil of 4.32-4.95 t per ha of dry soybean plant residues gives 49.3-56.0 kg per ha of nitrogen, 9.5-11.9 of phosphorus and 36.3-40.9 kg per ha of potassium under winter wheat. Compensation of nutrients utilization with soybean seeds yield reached up to: nitrogen - 33.9-35.3%, phosphorus - 35.3-37.7 and potassium - 91.1-95.8%. To form a ton of seeds it is necessary on average: 86.9 kg of nitrogen (including symbiotic nitrogen fixation), 16.7 of phosphorus and 33.9 kg of potassium at nutrients ratio in consumption N : P : K = 1 : 0.19 : 0.38.