Iron Tailings-Based Layered Double Hydroxide-Silica Hybrid for Slow-Release Nutrient Delivery and Enhanced Crop Growth in Sustainable Agriculture

The application of chemical fertilizers has significantly contributed to alleviating global hunger. However, excessive application of traditional chemical fertilizers (TCF) has led to significant environmental degradation due to their low nutrient utilization efficiency. Herein, a layered double hydroxides-silica hybrid material (HTS) derived from iron tailings is developed for sustainable nutrient delivery to enhance nutrient utilization efficiency. The iron tailing is successfully transformed into HTS through the structural reorganization, resulting in a hierarchical nanostructure with a specific surface area of 245.46 m 2 /g. Due to interlayer intercalation and interfacial interactions, HTS-based slow-release compound fertilizer (SRF) exhibits controlled nutrient release profiles in sand column leaching tests, achieving cumulative releases of 81.36% (N), 78.78% (K), 44.34% (P), and 71.89% (Se) over a 30-day period. Field experiments show SRF enhances fresh biomass of Sonchus oleraceus and Pepper by 100% and 31.93%, respectively. Concurrently, SRF improved soil cation exchange capacity by 18.18% and enhanced nitrate retention by 9.43-fold. Furthermore, the preliminary analysis indicated that the cost for the analysis and the reagents for SRF synthesis are economical. This strategy provides a scalable, cost-effective approach to repurpose mining waste into efficient fertilizers, promoting resource conservation and sustainable agriculture.