Controlled release fertilizer based on starch chitosan encapsulation

Abstract

Abstract Phosphor is the main component in a triple super phosphate (TSP) fertilizer which is needed by plants. However, phosphorus is very soluble in the water and makes it easily removed from the soil flowing into the river, and causing algae bloom problems. The solution for the problem is by using the fertilizer coated with starch-chitosan based material. The coated hydrogel bead fertilizer was expected to have a phosphorus controlled-released behaviour and retain the phosphor to be able to stay for a longer time in the soil. This research dealt with studying phosphorus releasing behaviour of starch-chitosan based fertilizer, water uptaking characteristic (swelling), and the morphology of the materials. The commercial granular fertilizer TSP was coated using starch-chitosan suspension. The coatings were conducted by spraying technique. The chitosan-starch mass ratio used were 100:0, 30:70, and 70:30, otherwise the starch percentages were made of 1%, 2%, and 3%. After coated by starch-chitosan suspension, the fertilizers were dried and used on the soil media. The soil which contained coated fertilizer was regularly watered and the phosphorus content was analyzed. The study showed that the water uptaking of the coated fertilizer was higher than that of the conventional uncoated fertilizer. The optimum condition of the chitosan-starch based coating was 30:70 and 2% of starch percentage. Furthermore, the higher chitosan content yielded the higher water uptaking capacity. This phenomenon is supported by the Scanning Electron Microscope (SEM) result. The coating fertilizer with higher chitosan content (ratio of 70:30, 2% starch) had more pores than that of lower chitosan content (ratio of 30:70, 1% starch).