Formation of soil fertility for different fertilizer systems in field crop rotation

The neсessity of systematic study of the indicatrors of fertility parameters is determined by the changes in the soil, because under the influence of intensification, they can be within the limits of the favorable interval or beyond its limits. More objective data on this issue can be obtained in stationary experiments in the crop rotation. It was established, that prolonged (50 years) application of mineral, organic and organo-mineral fertilizer systems in the field crop rotation in the conditions of right-bank forest-steppe led to change of all agrochemical properties of chernozem of podzolized heavy clayey loam. In accordance with mineral fertilizer system, pHkcl decreased by 0.9‒1.4 units in comparison with the initial values (pH 6.2), for organo-mineral ‒ by 1.0‒1.1, while the organic fertilizer system showed the slightest acidification effect ‒ by 0.9‒0.8 units. In the variant without fertilizers an exchange acidity decreased by 13%. The hydrolytic acidity also changed under the influence of fertilizer. In the crop rotation, it was enlarged to 2.7‒4.6 g/kg of soil, indicating the necessity for carrying out of liming. The return to soils large amount of calcium with farmyard manure restrains the process of acidification of the soil. The application of fertilizers also changed the nutrient regime of the soil. In the variant without fertilizers the nitrogen content of alkali ‒ hydrolyzed compounds was 101 mg/kg of soil, at application of mineral fertilizers it increased by 10‒24 mg/kg soil, farmyard manure – 6‒25, and for their combination – 11‒25 mg/kg of soil. Phosphate regime of chernozem of podzolized heavy clayey loam was well regulated. The content of mobile compounds of phosphorus and potassium was the best at organo-mineral and mineral fertilizer systems, in which there was an increase in their content, respectively, by 39‒152 and 46‒162 mg/kg of soil, depending on the dose of fertilizers. The cultures of field crop rotation reacted differently to both doses of fertilizers and fertilizer systems. Average yield increase of peas from application of fertilizers was insignificant ‒ 0.5‒0.8 t/ha. The yield of the clover hay was slightly influenced by the application of fertilizer systems. Yield of clover hay was higher as a result of application of organic fertilizers. In the analysis of yields of the main crop rotations ‒ winter wheat, sugar beet and maize ‒ the advantage of organo-mineral fertilizer system was identified. Depending on the placement of these crops in crop rotation, compared to the control where no fertilizers were applied , the average yield increases of winter wheat, irrespective of their predecessors, were 0.84‒1.61 t/ha, sugar beet ‒ 8.7‒15.7, maize ‒ 1.11‒2.34 t/ha. Consequently, the application of the organo-mineral fertilizer system improves the nutrient regime of the soil and contributes to increasing the productivity of the cultures of crop rotation.