Effect of starch adhesive on nutrient release of organic compound granulated fertilizer

A mineral binder Na₂SiO₃ and two starch adhesives synthesized by the method of chemical engineering were used as granulation binders of organic compound fertilizer, which was made up of waste compost and chemical fertilizers. Last, three different organic compound granulated fertilizers were obtained by way of disc granulation. Their granulars of resistance forces to crushing all reached the require of China National Standards (≥6 Newton). After 24 hours′ wet steep, the granular disintegration rate of mineral binder (C) was 6.1%; whereas the granule of starch adhesives (A and B) remained sound and their granular disintegration rates were 0. Through 168 hours′ nutrient release test, the result showed that the organic adhesive A and B were able to distinctly slow the release of nutritive elements in granule fertilizer. Especially the starch adhesive B modified with PVA (Polyvinyl Alcohol) was able to distinctly delay the release speed of NH⁺₄-N, total nitrogen, total phosphorus and total kalium in granule fertilizer. Adhesive B was the best in the three granulation binders to delay promptly soluble nutrient release, A was the second and the last was C. The experiment results also showed that the modified starch adhesive was able to control promptly soluble inorganic nutrient release synchronously. This method provides a reference and new thought to develop new non-envelope controlled release fertilizer.