Enhancing slow-release performance of biochar-based fertilizers with kaolinite-infused polyvinyl alcohol/starch coating: From fertilizer development to field application.

Conventional biochar-based fertilizers, which typically consist of a mixture of biochar, chemical fertilizers, and additives, offer benefits but often exhibit rapid nutrient release, limiting their long-term effectiveness. Herein, we explored the enhancement of slow-release performance in biochar-based compound fertilizers by incorporating a kaolinite-infused polyvinyl alcohol/starch (K-PVA/ST) coating, resulting in a new formulation denoted as K-PVA/ST-BCF. The results demonstrated that, compared to traditional NPK fertilizers, nitrogen leaching from K-PVA/ST-BCF in soil column leaching tests was reduced to 19.