Korotenko I. Optimization of mineral nutrition of winter wheat on leached chernozem of the Right-Bank Forest-Steppe of Ukraine

Scientific novelty of the obtained results. For the first time in the conditions of the Right-Bank Forest-Steppe of Ukraine, the regularities of the formation of the nutritional regime of leached chernozem under the cultivation of winter wheat in the grain chains of the crop rotation after different predecessors were established. It has been proven that the predecessor of peas and the three-time application of nitrogen fertilizers in the spring created the most favorable conditions for nitrogen nutrition of plants and ensured the highest biological productivity. It was improved the system of winter wheat fertilization by optimizing the doses, forms and methods of applying nitrogen fertilizers in the spring. It was further developed the issues of the effectiveness of the predecessor of peas and the three-time application of nitrogen fertilizers in the spring in achieving high yield and grain quality of winter wheat; issues of predecessor and nitrogen nutrition in improving the moisture supply of plants and forming a balanced balance of nutrients in the soil. The practical significance of the obtained results. Based on the results of stationary and temporary field experiments, the optimal predecessor was determined and an effective system of fertilization of winter wheat was formed in the grain chains of the crop rotation under cultivation in the conditions of the Right-Bank Forest-Steppe of Ukraine. A system of effective application of nitrogen fertilizers for winter wheat in spring has been developed, which ensures a grain yield of 6.8 t/ha with a profit of 4670 UAH/ha. The main results of research. It was established that the content of humus in the leached chernozem was determined by the use of the organic-mineral fertilization and slightly depended on the crop rotation chain. The maximum content of humus in the soil was observed when in a chain with peas the N50P20K30 + green manure + by-products per 1 ha of crop rotation was applied: in the 0-30 cm layer – 4.06%, 30-40 cm layer – 3.86%, exceeding the control without fertilizers – by 0.13% and 0.02%, respectively. As a result of research, it was established that in the spring after the predecessor of peas the reserves of mineral nitrogen in the soil were 15-23 kg/ha higher than in the chain with fescue. The best conditions of nitrogen regime in the leached chernozem were formed by the three-time application of nitrogen fertilizers in the spring with a total dose of 110 kg/ha, when applying 60 kg/ha of ammonium sulfate (II stage) + 30 kg/ha of ammonium nitrate (IV stage) + 20 kg/ha of urea for foliar (VIII stage of organogenesis): the content of nitrate nitrogen in the layer 0-30 cm – 22.5 mg/kg, ammonium nitrogen – 15.2; in the layer 30-60 cm – 11.8 and 8.8 mg/kg of the soil. The spring application of nitrogen fertilizers increased the reserves of mineral nitrogen in the 0-60 cm layer compared to the control without fertilizers – by 42 kg/ha for an absolute value of 175 kg/ha. At the end of the growing season, mineral nitrogen reserves in the soil decreased in 1.5-1.7 times. It was investigated that the formation of funds of mobile phosphorus and potassium in leached chernozem depended on the dose of their application as part of fertilizers. The highest content of mobile phosphorus and potassium in the soil was observed under the organic-mineral fertilization with the application of N50P20K30 + green manure + by-products per 1 ha of crop rotation: the content of mobile phosphorus in the 0-30 cm layer – 138 mg/kg, mobile potassium – 98 mg/kg with an excess of the control without fertilizers – by 18 and 20 mg/kg of soil, respectively. Crop rotation did not significantly affect the phosphorus and potassium regimes of the leached chernozem. The results of the research established that better conditions to use moisture from the soil by winter wheat were created in the chain with peas and when nitrogen fertilizers were applied in spring. Winter wheat used soil moisture most effectively from the soil when applying 60 kg/ha of ammonium sulfate (II stage) + 30 kg/ha of ammonium nitrate (IV stage) + 20 kg/ha of urea for foliar (VIII stage of organogenesis): moisture consumption for the formation of one ton of biological yield – 380 m3/t with a decrease compared to the control without fertilizers by 105 m3/t. It was investigated that the leguminous predecessor and the spring application of nitrogen fertilizers contributed to the formation of components of the winter wheat crop. For the predecessor of peas, the number of productive stalks compared to the predecessor of fescue increased – by 26-44 pcs./m2, the weight of 1000 grains – by 2.6-2.9 g. The highest indicators of the productivity components of winter wheat were observed after the three-time application of nitrogen fertilizers in the spring with a total dose 110 kg/ha: number of productive stems – 512 pcs./m2, weight of 1000 grains – 42.2 g.