RESEARCH ON USING PHU THO KAOLINITE AS AN ADDITIVE FOR MANUFACTURING UREA-KAOLINITE SLOW-RELEASE FERTILIZER

Abstract

Currently, urea fertilizer used in agriculture accounts for about 55% of the total fertilizer in the world but most of it is lost due to evaporation and leaching, causing environmental pollution. Using slow-release fertilizers is a modern effective solution to protect the environment as well as to improve nutrient use efficiency. In this study, an urea slow-release fertilizer was manufactured using a mechanochemical method, using Phu Tho, Vietnam kaolinite as a binding and nutrient carrier additive. The results of IR, XRD, EDX, and TGA analysis show that the mechanochemical process helped urea molecules incorporate into the structure of kaolinite. The presence of kaolinite in the product increased the durability of fertilizer pellets and reduced the nutrient release rate of urea-kaolinite fertilizer samples. The results showed that the manufactured urea-kaolin fertilizer sample containing kaolin content ≥ 60% met the slow-release fertilizer standards of the European Standardization Committee. The urea-kaolin fertilizer sample contained 60% kaolin by weight, releasing 56.32% N in water after 96 hours (at 25 ^OC), meeting the standards for slow-release fertilizers. The results of this research are the basis for manufacturing and applying slow-release fertilizers in agricultural production using environmentally friendly kaolinite additives, available in Vietnam.