FIELD: agriculture. SUBSTANCE: phosphate ore is acidified by nitric acid, calcium salts being removed. Thus obtained solution is neutralized by ammonium and thus prepared NP solution is evaporated. Then potassium chloride or potassium sulfate are added simultaneously with 0.6-1.6 mass % of magnesium oxide. The process is followed by hardening thus obtained molten salts with the help of spraying or they are granulated. Mentioned above magnesium oxide is preliminary calcined, size of its particles is 0.2-0.3 mm. EFFECT: improves quality of fertilizer. 2 cl, 3 tbl
