Efficiency of a crop rotation and change of soil fertility depending on doses and ratios of mineral fertilizers
Change of agrochemical parameters of soil and yield of crops of the unit of field crop rotation: spring barley - oats - pure fallow - winter wheat depending on the doses and ratios of fertilizers was studied in field stationary experiment on leached Chernozem. The experimental scheme consisted of 16 variants where nitrogen, phosphorus, and potassium were added at the ratio: 000, 111, 220, 331, 202, 313, 022, 133, 333, 222, 113, 002, 131, 020, 311, and 200 (first digit is N, second - P <sub>2</sub>O <sub>5</sub>, third - K <sub>2</sub>O), where 0 - no fertilizer, 1, 2, 3 - single, double and triple dose. Doses of nitrogen in the experiment were: 1 - 45, 2 - 90, 3 - 135, phosphorus and potassium: 1 - 30, 2 - 60, 3 - 90 kg of acting matter/ha. It is found out that the average annual productivity of the studied crop was higher in variants with a triple dose of nitrogen fertilization (N135) and made 2.57…2.78 t of grain units/ha. The defining element in receiving of maximal yield of field cultures was nitrogen. With increase of its dose of application up to 135 kg of acting matter/ha productivity of plants and respectively general efficiency of a unit of crop rotation increased by 44…48%. The ratio of phosphorus and potassium in fertilizer didn''t influence productivity of field cultures. Application of phosphoric and potash fertilizers by 60 and 90 kg of acting matter/ha in the unit of a field crop rotation didn''t lead to decrease in K <sub>2</sub>O and P <sub>2</sub>O <sub>5</sub> in soil arable horizon. Application of N135 irrespective on a ratio with phosphorus and potassium kept its concentration at the initial level.