TRANSFORMATION OF QUALITY AND QUANTITATIVE COMPOSITION OF MINERAL PHOSPHATES IN LIGHT CHESTNUT SOIL DURING LONG-TERM APPLICATION OF PHOSPHOROUS FERTILIZERS IN CROP RATOTAION AND PERMENANT SUGAR BEET SOWING

The article presents the results of studies on the influence of long-term application of phosphoric fertilizers on sugar beet crops unchallenged for more than 50 years on the transformation of phosphate forms on light chestnut soil and its productivity in comparison with the identical options in the rotation. Despite the large amount of practical material, the effect of the duration of application of phosphorus fertilizers on irrigated soils in Kazakhstan has not been sufficiently studied. The available isolated data on the influence of the duration of fertilizer application relate to the aspect of assessing their impact on the yield and quality of the crop and, partly, on the phosphate regime of soils. Most of the studies were carried out within the framework of short-term field experiments, which are designed, first of all, to establish specific doses of fertilizers on the productivity of agricultural crops. These field studies were carried out on a fairly narrow background and time frame of variation in soil fertility characteristics, which did not allow us to establish the qualitative and quantitative composition of phosphates and their functional relationship between the level of potential and effective fertility.