The Controlled-release Phosphorus Fertilizer with Silica from Rice Husk

Abstract

The preparation of phosphorus-adsorbed silica from rice husk for application in controlled-release fertilizer has the objective to study the adsorption process of silica from rice husk, study the phosphorus content before and after its adsorption in silica, prepare the phosphorus fertilizer pellets, and study the release of phosphorus. It has been observed that rice husk calcined at 900 °C for 6 h got 12% of the porous silica, which qualified as absorbent material by the XRD and FT-IR techniques. The porous silica has the phosphorus contents at 500 ppm at the raw material; after soaking with 20 ppm P₂O₅, the phosphorus was increased to 1270 ppm. The pellet fertilizers from silica were prepared by compressing the mixing of silica and binder, which can be maintained as the fertilizer granules for up to 60 days. The phosphorus in fertilizer powder were maximum relates at 36.41% after soaking in water for 18 h, while in tablets they release at 33.16% for 216 h. The phosphorus fertilizer formulation and powder form were excellent fertilizer efficiency, high phosphorus content and slow release, indicating that the mesoporous silica from the rice husk are one alternative application to prepare the controlled-release fertilizer.