METHODS OF APPLICATION OF PHOSPHORUS FERTILIZER: IN STOCK OR ANNUALLY?

Optimization of the use of limited raw materials for the production of phosphorous fertilizers is recognized as the most important problem of our time. Substantiation of the dose and method of application of phosphorus fertilizer (PF), correction of the technology of its application are one of the ways to solve this problem. The effectiveness of the annual and reserve methods of applying PF to soils with different phosphate stocks was compared. The soil is old–arable leached medium-acre chernozem. The soil was sampled in the Central forest-steppe of the Novosibirsk region. on 2 sites, which differed in the composition of the soil-forming rocks and, accordingly, in the amount of phosphate stock. In soil 1, the total phosphorus content was 1.4 times higher than in soil 2, and the Ca-P_III fraction was about 2 times higher with lower Ca-P_II fraction values. The soils are highly humic, with a content of exchangeable potassium up to 140 mg/kg, mobile phosphorus (according to Chirikov) – up to 215 mg/kg. In the vegetation experiment, 5 cycles of spring wheat cultivation were carried out before the earing phase in the KKR-001 artificial climate chamber. Experience options: N₅₀K₅₀ (background), N₅₀K₅₀ + P₄₀ (single use), N₅₀K₅₀ + P_40+40+40 (annual deposit), N₅₀K₅₀ + +P₁₂₀ (stock deposit). The biomass of wheat during the application of P_40+40+40 in cycle 3 was about 20% higher than that of P₁₂₀, so the phosphorus deposited in the reserve was immobilized by the soil. Phosphorus removal in cycles 1 and 2, when adding P₁₂₀ to the reserve, exceeded the other options by about 50%, in cycle 3 it was 30% less than the option P_40+40+40, so the potential for adding phosphorus to the reserve by the end of cycle 3 was exhausted. In cycles 4 and 5, with a significant decrease in the removal of the element, the differences between the variants were leveled. The utilization rate of phosphorus fertilizer was maximal in cycle 1 and decreased significantly (by 2–3 times) in subsequent cycles, regardless of the method of its application and the soil. When studying the effect of fertilizers (1–3 growing cycles), an increase in the phosphorus content in the mobile fractions of the soil was observed, an increase in the number of CFU phosphatemobilizing microorganisms with suppression of phosphatase activity. It was concluded that, regardless of the soil properties, in order to increase the economic efficiency of agrocenosis, it is advisable to apply РF annually (to provide plants with phosphorus), to increase the soil’s phosphorus supply, the studied methods of applying fertilizers were equivalent and ineffective.