QUICK-ACTING AND SLOW-RELEASE FERTILIZER AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To effectively prevent the caking due to the insolubilization of the phosphatic component and moisture absorption and to obtain a phosphatic fertilizer excellent in quick-acting and slow-release fertilizing effect by composting the fertilizer mainly of a water-soluble phosphate and a citric-soluble phosphate and covering the phosphatic component with a silica gel. SOLUTION: The phosphatic material is decomposed by phosphoric acid into a slurry. Light-burned magnesia is added as a viscosity control agent to adjust the viscosity of the slurry to 2000-5000cP, preferably 2700-4000cP, (80 deg.C) and the acidity to 1.4-1.8, a powdery silicate material is added, and the admixture is granulated by a granulator into the grain having 2-4mm diameter. A granulated quick-acting and slow-release phosphatic fertilizer with the phosphatic component covered with the formed silica gel, contg. =20wt.% phosphoric acid and 4.5-12wt.% silica gel and with the citric-solubilization ratio of phosphoric acid controlled to =95% and the water solubilization ratio to 35-65% is obtained in this way.