USE OF BIOBLEND POLYSTYRENE-POLY (3-HYDROXYBUTYRATE) AS THE COATING MATERIAL OF THE NPK SLOW RELEASE FERTILIZER

Abstract

Conventional Nitrogen-Phosphorus-Potassium (NPK) fertilizer granules is absorbed by plants inefficiently. A certain proportion of the fertilizer is released into the environment. The aim of this research was to formulate NPK slow release fertilizer granules using polystyrene - poly 3-hydroxybutyrate polymers. NPK fertilizer granules were coated by spray coating method using polystyrene-polyhydroxybutyrate bioblend. NPK slow release granules obtained were evaluated in term of SEM and FTIR analysis; percentage of coating and released of P2O5; dissolution efficiency and rate of release of P2O5; and the order of release kinetics. FTIR analysis of slow release NPK fertilizer showed no chemical interaction between NPK fertilizer granules and coating polymer materials. The percentage of release of P2O5 from uncoated and coated NPK granules after 48 hours were 94.17 ± 7.88, and 46.45

± 0.77%, respectively (p <0.05). The rate of release of P2O5 from uncoated and coated NPK fertilizer granules, was 1.90 ± 0.06, and 0.98 ± 0.01 %.h^-1 respectively, (p <0.05). Kinetics release of slow release NPK fertilizer followed the Langenbucher kinetics (R = 0.993). The release efficiency of P2O5 from uncoated and coated NPK fertilizer granules were 65.67 and 33.66% (p <0.05), respectively. It can be concluded that coating of NPK fertilizer granule using poly-hydroxy butyrate could influence the rate and release efficiency of P2O5 (p<0.05).