PREPARATION AND CHARERIZATION OF SLOW – RELEASE FERTILIZER WITHIN POLYMER COVER LAYER AND ADDITIVES ORIGINATING NATURE

Abstract

A slow- release urea fertilizer was prepared by coating polyurethane onto urea granular fertilizer. Granular ureas have been synthesized from conventional urea, bentonite and starch. Paraffine wax played as an additives role during formation of polyurethane skin layers. The structure and nutrient release characteristics of the polyurethane skin layers were investigated by FTIR, SEM and TGA. Its nutrient release characteristics in water were studied to compare with the European Standardization Committee (CEN) Task Force on slow-release fertilizers. The sample with ratio of mass of ure: Bentonite: starch is 90: 7.5: 2.5, thickness of polyurethane cover layer is about 24.8-31.5µm, release 82.86% N after 21 days in water (at 25⁰C). Paraffine wax played an important role in inhibiting water to penetrate into the polyurethane skin layer.