Nutrient controlled release performance of bio-based coated fertilizer enhanced by synergistic effects of liquefied starch and siloxane

The porous structure and hydrophilicity of coating shells affect the nutrient controlled-release performance of castor oil-based (CO) coated fertilizers. In order to solve these problems, in this study, the castor oil-based polyurethane (PCU) coating material was modified with liquefied starch polyol (LS) and siloxane, and a new coating material with cross-linked network structure and hydrophobic surface was synthesized, and used it to prepare the coated controlled-release urea (SSPCU). The results demonstrated that the cross-linked network formed by LS and CO improved the density and reduced the pores on the surface of the coating shells. The siloxane was grafted on the surface of coating shells to improve its hydrophobicity and thus delayed water entry. The nitrogen release experiment indicated that the synergistic effects of LS and siloxane improved the nitrogen controlled-release performance of bio-based coated fertilizers. Nutrient released longevity of SSPCU with 7 % coating percentage reached >63 days. Moreover, the nutrient release mechanism of coated fertilizer was further revealed by the analysis of the release kinetics analysis. Therefore, the results of this study provide a new idea and technical support for development of efficient and environment-friendly bio-based coated controlled-release fertilizers.

Automated summary

In this study, a new coating material with cross-linked network structure and hydrophobic surface was synthesized to improve the nutrient controlled-release performance of coated fertilizers. The modified material showed improved density and reduced pores on the coating shells, and the introduction of siloxane improved its hydrophobicity and delayed water entry. The synergistic effects of the modified material improved the nitrogen controlled-release performance of bio-based coated fertilizers, with the nutrient release longevity reaching over 63 days.