For the first time, the influence of 50-year application of fertilizers and the structure of crop rotations on the fertility of leached chernozem and the yield of agricultural crops under conditions of unstable moisture in the Right Bank Forest Steppe of Ukraine was established. It was found that the use of by-products and mineral fertilizers in the conditions of crop rotation forms a stable basis of production and is slightly inferior in efficiency to the traditional manure-based fertilization system.
It was improved a winter wheat fertilization system by applying nitrogen fertilizers three times in the spring in combination with foliar fertilizing with manganese and silicon.
It was further developed the issue of alternative fertilization of agricultural crops in short-rotation crop rotations; the issue of optimization of forms, doses and methods of applying nitrogen fertilizers to winter wheat in conditions of unstable moisture.
It was found that the use of N53,2P41,7K41,7 + 6.6 tons of manure in a crop rotation on 1 ha of arable land for 50 years increased the humus content in leached black soil compared to the control without fertilizers by 0.37% and formed its highest content in the soil - 3.44%. The application of N53,2P41,7K41,7 and by-products was slightly inferior to traditional fertilizer: the humus content was 3.30%, which was higher than in the control without fertilizers - by 0.23%. In grain-rowed and rowed crop rotations, the application of organic fertilizers together with mineral fertilizers reduced the humus content compared to the grass-grain crop rotation by 0.14-0.37%. The use of only mineral fertilizers increased the mineralization of humus and reduced its content to the control without fertilizers by 0.05-0.09%.
It was established that mineral and organic-mineral fertilization systems with applying phosphorus fertilizers at a dose of more than 42 kg/ha of arable land caused a significant accumulation of mobile phosphates in the leached chernozem and formed a high availability of mobile phosphorus in the soil. The same dose of potash fertilizers maintained the average soil supply with mobile potassium at a content of 80-96 mg/kg of soil.
It was studied that in the grass-grain crop rotation, organic-mineral fertilizer systems created the best conditions for the accumulation of moisture in the soil and its use by winter wheat. The reserves of productive moisture in the 1.5 m layer of soil in the grass-grain crop rotation were higher compared to the grain-rowed crop rotation - by 15-25 mm, to the row-row crop rotation - by 9-19 mm.
It was found that the use of N53,2P41,7K41,7 + 6.6 tons of manure per 1 ha of arable land in a crop rotation ensured the highest productivity of sugar beet: yield - 46.9 t/ha, sugar content - 16.5%, sugar yield - 7.73 t/ha. Growing winter wheat in a grass-grain crop rotation was significantly more productive than in a grain-rowed and row-row crop rotation. The highest yield of winter wheat was achieved in a grass-grain crop rotation with the application of N53,2P41,7K41,7 + 6.6 t of manure per 1 hectare of arable land - 7.67 t/ha.
It was studied that three-time nitrogen fertilization of winter wheat in spring with a total dose of 110 kg/ha, in particular ammonium sulfate N60 on frozen soil, foliar urea in the phase of emergence into the tube and earing (N30 + N20) combined with microfertilizers the manganese and silicon provided the highest efficiency: grain yield – 6.67 t/ha, protein content – 12.5%, which was higher compared to the control without fertilizers by 1.99 t/ha and 1.2%.
According to the results of the research, it was found that the use of a traditional manure-based organic-mineral fertilization system in a grass-grain crop rotation formed the highest forage productivity - 9.2 t fodder units per one ha.
It was investigated that in grass-grain crop rotation and row-row crop rotations, organic-mineral fertilization systems formed a balanced nitrogen balance - respectively - 94-95% and 100-103% intensity; in grain-row crop rotation, the nitrogen balance was negative - intensity of 82-84%. The application of mineral fertilizers together with organic fertilizers formed a positive phosphorus balance in crop rotations - intensity of 103-115%. The potassium balance in the soil under all fertilization systems was negative. The application of mineral fertilizers together with by-products formed the best potassium balance in crop rotations with a deficit of its balance of 33-41 kg/ha of crop rotation and a balance intensity of 73-78%.
