Talc-Derived silica-supported layered double oxide composite for sustainable multi-nutrient delivery in agricultural application

Water-soluble fertilizers (WF) exhibit delivery inefficiencies that limit the productivity of agricultural products and contribute to environmental pollution. Herein, a silica-supported layered double oxide composite (LDO@Si) was synthesized to load urea, KH 2 PO 4 , and Na 2 SeO 3 forming a compound slow-release fertilizer (CSRF). SEMand TEM demonstrated that LDO@Si is a nano hybrid material with a core-shell structure. Nutrients are bound to LDO@Si via chemical bonding, electrostatic interactions, and weak nitrogen-mediated interactions. In a quartz sand column experiment, CSRF exhibited excellent slow-release performance: the long-term release period of urea reached 22 days for nitrogen (N), while those of P, K, and Se exceeded 53 days. The Korsmeyer-Peppas model indicates that CSRF possess a complex release mechanism. Additionally, in 30-day pot experiments, CSRF increased fresh biomass by ∼11.92 % and the uptake of N, P, K, and Se by ∼6.67 %, ∼17.72 %, ∼15.74 %, and ∼419.44 %, respectively, compared with WF. Furthermore, CSRF significantly improved the properties of acidic soils and their nutrient retention capabilities. Compared with WF, the content of slow-release K (SRK) increased by 42.05 %, available P (AP) by 45.91 %, and available Se (ASe) by 32.23 %. This study is expected to provide insights for the design and application of mineral materials in the field of sustainable agriculture.