Optimizing nitrogen delivery: Controlled release of fertilizer using mesoporous silica for sustainable agriculture

This study investigates the potential of mesoporous silica as a controlled-release medium for nitrogen fertilizers. Mesoporous silica was synthesized using the sol-gel method with cetyltrimethylammonium bromide (CTAB) as a template, followed by surface modification and calcination to obtain silica gel, surface-coated silica, and calcined silica. Structural analysis using FTIR confirmed that calcined silica exhibited a highly condensed network with minimal surface hydroxylation, while surface-coated samples retained organic groups. Nitrogen adsorption–desorption studies revealed that silica gel had the highest adsorption capacity (35%) but also a relatively high desorption rate (1.75%), leading to faster nutrient release. Surface-coated silicas exhibited lower adsorption efficiencies (20% and 25%) with desorption rates of 2% and 1.5%, respectively. Calcined silica had the lowest adsorption (15%) but also the lowest desorption (<1%), indicating a more controlled release. Nitrogen release testing confirmed this trend, with calcined silica showing the slowest release rate, reaching only 396.8 ppm by Day 6. These findings highlight calcined mesoporous silica as a promising material for enhancing nitrogen use efficiency in agriculture while minimizing environmental losses.