USE OF NEUTRALIZED PHOSPHOGYPSUM AS A MULTICOMPONENT FERTILIZER FOR RICE CROPS. MESSAGE 1
Over the past 15 years due to removal with crops of rice crop rotation, as well as with field waste and seepage water content of mobile forms of boron in soils of rice irrigation systems in the Krasnodar region decreased by 10 %, cobalt by 14 %, manganese by 10 %, copper by 7 %, molybdenum by 15 % zinc by 6 %. Impoverishment of soil with calcium and sulfur is observable. Need of using micronutrients for this crop is also determined by lowering mobility of most microelements in flooded soils. Partly this problem can be solved by use of neutralized phosphogypsum - waste product of wet-process phosphoric acid. With its application in dose of 1 t/ha, field receives 265 kg of Ca, 215 kg of S (general) 20 kg of P2O5 and 9.8 kg of SiO2, so it compensates for the loss of calcium from the rice soil, as well as solves the problem of sulfur, silicon and partly phosphorus fertilizers. Data showing possibility of use of neutralized phosphogypsum as multicomponent fertilizer for rice crops are given. Phosphogypsum reduces sparseness of rice plants in ontogeny, thus forming a dense agrocenosis: plant density is 24-25 pcs./m2 that is higher than on application of N120P80K60. Plants with such agricultural background by their height and leaf area did not differ from control ones (N120P80K60), and their dry weight was higher by 2-6 %. With fertilizer system N120P80K60 application of 4 t/ha of phosphogypsum during main fertilizer treatment provides the same level of phosphorus content in the soil and plants, as application of 100 kg/ha of ammophos. Rice yield increases by 0,57 t/ha or 8,98 %. Yield growth is the result of increasing survival capacity of plants, seed setting of panicle and weight of grain per plant