Synthesis of a starch derivative and its application in fertilizer for slow nutrient release and water-holding

With the increasing public concern toward human health, environmental protection, and natural resource sustainability, there is a shift toward the development of environmentally friendly fertilizers based on biomass. In this study, a coated fertilizer system based on starch acetate (SA) and weakly cross-linked carboxymethyl starch/xanthan gum (CMS/XG) was developed to improve biomass utilization efficiency and reduce environmental pollution. The coated fertilizer with a diameter in the range of 2.5–3.0 mm possesses low moisture content and high mechanical hardness. Nutrient nitrogen reached a steady state of releasing equilibrium within 20 days and the release behaviour depended on the coating thickness and the plasticizer content of the SA film. Soil water-holding capacity determination showed that soil/coated fertilizer mixtures retained more water than the control soil, and the water content increased with increasing amount of the coated fertilizer in the soil. The experimental data indicated that the products based on starch derivatives as coating materials have preferable slow-release performance and the introduction of the natural polymers can improve biomass utilization efficiency, reduce nutrient loss and improve water use efficiency.