Abstract:

To explore the physical and chemical properties and slow-release properties of compound coating-agent for slow-release fertilizer (KSFF-2), the viscosity, forming film property, forming film time, film tenacity, coating off rates of coating agent, and the nutrient initial-release ratios, nutrient micro-release ratios and nutrient accumulation-release curves of coating slow-release fertilizer were determined. Results showed that the viscosity of the compound coating-agent was 44.5 MPa/s, forming film property was better, forming film time was 7 min, film stretch ratio was 2.8 times, coating off rates was less than 5%. The initial release ratio of N, P, K in the coated fertilizer was less than 15%, the micro release ratio was less than 2%, which was consistent with the slow-release fertilizer standard GB/T23348-2009 constituted by China. The initial dissolution rate of P was less than those of N and K, and the micro release ratio of N, P, K was almost the same. The nutrient accumulation-release curves were S-shape, which was consistent with the nutrient demand of crops. These results indicated the physical and chemical properties of compound coating-agent for slow-release fertilizer were good, and it could effectively control the slow-release of nutrients of general compound fertilizer.