SCIENTIFIC BASES OF USING NEUTRALIZED PHOSPHOGYPSUM AS A POLYCOMPONENT FERTILIZER IN RICE CROP ROTATION
Inclusion of phosphogypsum into rice fertilizer system positively affects the physico-chemical properties of soil and the dynamics of con- tent of mobile phosphorus in it. Replacement of phosphorus fertilizer with neutralized phosphogypsum does not cause a decrease in yield when applied directly under the rice and when its aftereffect is used. Phosphogypsum is applied in an amount of 4 t/ha in combination with nitrogen and potassium fertilizer at the rate of N<sub>18+55,2+46</sub>K<sub>60</sub>. Its inclusion into rice fertilizer system is economically justified. Each kilogram of active substance of nitrogen-potassium fertilizer, introduced in combination with phosphogypsum, pays back 8.72 kg of yield increase with direct action and 8.50 kg - with its aftereffect.