PRODUCTION AND USING ORIENTATION OF CONTROLLED RELEASE UREA FERTILIZER FOR WET-RICE CULTIVATION IN VIETNAM

Abstract

Controlled-release fertilizers (CRFs) are a promising way to develop sustainable and modern agriculture. CRFs have lower production costs, save resources, enhance crop yield and quality, and prevent environmental damage. This study aimed to develop and produce controlled-release urea fertilizer (CRUF) and design formulation for wet-rice growth in Vietnam. The coating particle technology with a biodegradable polymer mixture, which was synthesized from distarch phosphate, poly(vinyl alcohol), and poly(acrylic acid), was used to produce CRUF. The CRUF characteristics were measured using optical microscopy, scanning electron microscopy, and image analysis methods. The obtained product was also compared with commercial urea products. The study also established the mechanism and mathematical model for the urea release process of CRUF. The calculated diffusion coefficient of water and urea through the membrane is 1.47 ×10^-6 m²/h and 2.2×10^-8 m²/h, lag period of 1.5 hours, period of linear release of 13.73 hours and steady release rate of 0.548. These results were used to calculate and evaluate the suitablity between the amount of urea released and the needs of wet rice which can design and apply them in the production of the Mekong Delta's wet rice.