Optimizing fabrication of coated fertilizers integrated with biochar for enhanced slow-release properties: Mechanisms and cost-effectiveness analysis
Cheng Yang, Mengqiao Wu, Jiawei Lu, Yan Zhang, Ruohui Lu, Yongfu Li, Yanjiang Cai, Hai Xiang, Zechao Zhuang, Zhen Qiu, Bing Yu
Abstract
The growing need for environmentally friendly fertilizers that sustain agricultural productivity has spurred research into biochar-based fertilizers. This study optimized biochar-based fertilizers by incorporating biochar into PVA/starch-coated fertilizers at different locations: within the coating (BC mid /PVA/ST-SRF), on the outer surface (BC out /PVA/ST-SRF), and within the capsule (BC in /PVA/ST-SRF). BC in /PVA/ST-SRF showed the best slow-release performance, significantly reducing N and P leaching (N: 71.54 %, P: 44.19 %) compared to BC mid /PVA/ST-SRF (N: 77.70 %, P: 51.66 %) and BC out /PVA/ST-SRF (N: 78.59 %, P: 54.51 %), and outperforming commercial fertilizers. Mechanistic studies indicated Fickian diffusion governed nutrient release from BCin/PVA/ST-SRF, where biochar acted as an initial barrier within the PVA/ST film. Additionally, the superior swelling and mechanical properties of the PVA/ST film contribute to the excellent slow-release performance of BC in /PVA/ST-SRF. Pot trials with bok choy demonstrated enhanced growth and nutrient utilization (N: 84.91 %, P: 13.40 %) with BC in /PVA/ST-SRF, and improved nutritional indices. Economic analysis highlighted the scalability and commercial viability of BC in /PVA/ST-SRF production.