Indicators of Soil Fertility of the Typical Chernozem after Long-Term Application of Various Fertilizer Systems

The objective of the research was to study the effect and aftereffect of various fertilizer- and soil-treatment systems on the main fertility indices of typical chernozem. The work was carried out in a long-term field experiment in a grain crop rotation under conditions of Belgorod oblast. The soil of the experimental plot is typical chernozem, medium-deep, low-humus, heavy loamy on loess-like loam. The experimental design included studying the effect of mineral fertilizers in doses of N64P64K64 and N128P128K128, organic fertilizers with a crop rotation saturation of 8 and 16 t/ha of the cattle’s manure crop rotation area, and combinations of organic and mineral fertilizers. Fertilizers were applied against the background of three methods of primary soil treatment: plowing, chisel plowing, and minimum tillage. For six rotations of a 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 to 47.6–51.2 mg/kg, and mobile potassium remained almost at the original level of 108.4–116.2 mg/kg. The best content of basic nutrients in the soil is provided by the use of an organomineral system with the introduction of mineral fertilizers in doses of N64P64K64 and N128P128K128 against the background of 8 t/ha crop rotation area of manure. At the same time, the humus content reaches 5.30–5.64%, mobile phosphorus 222.6–255.1 mg/kg, and mobile potassium 156.6–173.5 mg/kg. With long-term use of manure with a crop rotation saturation of 16 t/ha, the humus content was 5.34% (on average for the method of primary soil cultivation) and phosphorus and potassium were 122.0 and 143.3 mg/kg, respectively.