Indicators of soil fertility of typical chernozem after prolonged use of various fertilizer systems

The research was carried out in order to study the effect and aftereffect of various fertilizer systems on the main indicators of fertility of typical chernozem. The work was carried out in a long-term field experience in the grain crop rotation in the conditions of the Belgorod region. The soil of the experimental site is typical medium–sized low-humus heavy loam chernozem on loess-like loam. The scheme of the experiment provided for the study of the effect of mineral fertilizers, in doses of N₆₄P₆₄K₆₄ and N₁₂₈P₁₂₈K₁₂₈; organic fertilizers with crop rotation saturation of 8 and 16 t/ha of the crop area (s. p.) and combinations of organic and mineral fertilizers. Three methods of basic tillage were analyzed: plowing, non-tillage and minimal tillage. During six rotations of the five-field crop rotation, without the use of fertilizers, humus losses amounted to 0.06…0.27 %, with an actual content of 4.96…5.15 %; the content of mobile phosphorus decreased by 2.8…9.2 mg/kg, and was at the level of 47.6…51.2 mg/kg; and mobile potassium remained almost at the same level (108.4…116.2 mg/kg). To obtain the optimal content of the main nutrients in the soil, it is necessary to use an organomineral fertilizer system. In particular: the use of mineral fertilizers in doses of N₆₄P₆₄K₆₄ or N₁₂₈P₁₂₈K₁₂₈ for a background of 8 t/ha of bovine manure (cattle). At the same time, the humus content in these variants reached the maximum value and amounted to 5.30…5.64 %, mobile phosphorus 222.6 …255.1 mg/kg and mobile potassium 156.6…173.5 mg/kg. Or long-term use of cattle manure with a crop rotation saturation of 16 t/ha. At this level of fertilization, the humus content was 5.34 % (on average according to the method of basic tillage), phosphorus and potassium 122.0 and 143.3 mg/kg, respectively.