PHOSPHORUS BALANCE IN THE SOIL AND THE EFFECTIVENESS OF PHOSPHORUS DEFICIENCY SYSTEM OF FERTILIZATION

Abstract

The study, held on podzolic black heavy loam soil of the Right-Bank Forest-Steppe of Ukraine, reveals the influence of long-term application of phosphorus deficient fertilization system in field crop rotation (winter wheat, corn, spring barley, soybeans) on phosphorus content in plants, its costs for the formation of the unit of yield, the phosphorus balance. In addition, the efficiency index of different doses of phosphorus fertilizers were calculated. It was found that the content of phosphorus in grains and seeds of agricultural crops under the influence of phosphorus fertilizers varies by 12– 50%, and in straw and stalks ‒ by 13–37%, depending on the variant of the experiment. It is shown that the non-grain part of the crop contains a small part of phosphorus ‒ 24-54% of economic application depending on the crop. It is estimated that if it is left in the field for fertilizer with an average annual application of N110P60K80, it compensates for the cost of phosphorus for crop formation by only 33%. The utilization rate of phosphorus from mineral fertilizers applied in crop rotation for eight years at a dose of і N110P30 ‒P60K80 per 1 ha of crop rotation area is 36-46%. With the introduction of P30 and P60 on the background of N110K80 and leaving the non-commodity part of the crop in the field for fertilizer, the balance of phosphorus in the soil is formed with an intensity of 67 and 117%, respectively. According to the index of integrated assessment, which takes into account seven indicators (payback of 1 kg of mineral fertilizers; additionally notional net profit; net energy profit; humus balance and intensity of nitrogen, phosphorus and potassium balance), the best variant of the experiment is to apply N110P60K80 fertilizer per 1 ha of field crop rotation area. This indicates the inexpediency of even a temporary reduction in the dose of phosphorus fertilizers in field crop rotation on podzolic black heavy loam soil in the Right Bank Forest-Steppe of Ukraine. Reducing it to 30 kg / ha led to a decrease in the complex assessment index from 1.38 to 1.25.