Zinc oxide nanoparticles coupled biochar-based slow-release fertilizer for enhanced nutrient efficiency and sustainable agriculture
Man Li, Xu Zhao, Cheng Yang, Mengqiao Wu, Chang‐Zhi Dong, Hai Xiang, Yongfu Li, Yanjiang Cai, Zuyong Zhang, Bing Yu
Abstract
The excessive use of synthetic fertilizers has resulted in environmental degradation and inefficient nutrient utilization. Biochar-based slow-release fertilizers offer a sustainable alternative by enhancing nutrient retention and reducing environmental impact, but their nutrient slow-release performance can still be improved for better efficiency. In this study, a new zinc oxide nanoparticles coupled biochar-based slow-release fertilizer using polyvinyl alcohol/starch encapsulation is developed. The resulting PVA/ST-Zn-BSRF exhibits slower nutrient release than traditional NPK fertilizer and PVA/ST-NPK without ZnO/biochar incorporation. After 7 hours, it releases 145.15 mg of nitrogen and 23.25 mg of phosphorus in water, compared to 181.47 mg and 53.23 mg for NPK, and 168.08 mg and 34.27 mg for PVA/ST-NPK, respectively. In soil, PVA/ST-Zn-BSRF releases 5.82 mg of nitrogen and 1.22 mg of phosphorus over 29 days. The slow-release mechanism of PVA/ST-Zn-BSRF for nitrogen and phosphorus is attributed to the combined effects of Zn-BC adsorption and the physical diffusion barrier provided by the PVA/ST membrane. Field trials reveal that PVA/ST-Zn-BSRF boosts wheat yield by up to 87.5 % and significantly improves soil organic matter, with levels 25 % higher than those achieved with NPK treatment at grain maturity. Economic analysis reveals that, despite a higher fertilization cost, PVA/ST-Zn-BSRF leads to higher wheat yields and additional profit of $615.89/ha, demonstrating its potential for improving both agricultural productivity and sustainability.