The effect of coated materials and its structure on the release properties of controlled release fertilizers

: The method dissolution rate in water was used to study the release properties of controlled release fertilizers. Nutrients release rate and release duration were used to assess the effect of coated materials and its structure on the release properties of controlled release fertilizers. The results suggests, coated materials M2 was better than coated materials M1 in controlling nutrients release rate. The nutrients cumulative release rate curve of controlled release fertilizers coated by material M1 was logarithm, otherwise the nutrients cumulative release rate curve of controlled release fertilizers coated by material M2 was straight line. With RWA (ratio of coated materials weights and fertilizers area) increasing in the range of 20-80g/m2, the nutrients preliminary solubility decreased and the release duration was longer. The fertilizers with different release duration could be made through adjusting coated materials and RWA.