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

The influence of long-term application of potassium-deficient fertilizer system in the field crop rotation (winter wheat, corn, spring barley, soybeans) on podzolic heavy loam black earth of the Right-Bank Forest-Steppe of Ukraine on potassium content in plants, its costs for formation of one unit of the harvest was determined; potassium balance was calculated and the effectiveness of different doses of potassium fertilizers was comprehensively assessed. It was found that the potassium content in grains and seeds of agricultural crops under the influence of potassium fertilizers varies by no more than 8%, while in straw and stalks - by 10-24% depending on the variant of the experiment. It is shown that the non-grain part of the crop contains a significant part of potassium - 50-80% of economic removal depending on the crop. It is calculated that if it is left in the field for fertilizer in the variant of the experiment Basis + K80, it compensates for the consumption of potassium by 71%. By applying K40 and K80on the basis of applying N110P60 and leaving the non-commodity part of the crop in the field for fertilizer, the balance of potassium in the soil is formed positive with intensity of 111 and 212%, respectively. According to the index of complex assessment, which takes into account seven indicators: payback of 1 kg of mineral fertilizers; additionally conditionally net profit; net energy profit; humus balance and intensity of nitrogen, phosphorus and potassium balance, the best variant of the experiment is application of N110P60K40 per 1 ha of field crop rotation area. This indicates the possibility of a temporary reduction in the dose of potassium fertilizers in field crop rotation on podzolic heavyloam black earth in the Right-Bank Forest-Steppe of Ukraine.