Mesoporous Silica Doped Porous Biocarbon as a Slow-Release Nitrogen and Silica Fertilizer

High Resolution Image Download MS PowerPoint Slide Conventional fertilizers cannot deliver beneficial elements such as silicon (Si) and nitrogen (N) efficiently, which contribute to overall plant health and stress tolerance. In this work, mesoporous silica-doped porous biocarbon was developed as a multifunctional carrier to enable simultaneous delivery of N and plant-available Si. Activated porous biocarbon (APB) produced from sugarcane trash via KOH activation served as a porous scaffold for four mesoporous silica variants (SBA-15, KIT-6, FDU-12, and MSNs) with fixed 5 wt % loading. The hybrids were infused with urea at a 1:4 hybrid:urea ratio, and the mixtures were pelletized with a 10 wt % molasses binder. In the column leaching test, commercial urea exhibited a fast, immediate-release N profile, with most N lost in the first 12 h, whereas silica-doped biocarbon pellets exhibited controlled release, retaining (12–18%) of N in the solid scaffold after 72 h. Glasshouse ryegrass trials demonstrated shoot and root development comparable to urea and slightly higher biomass with the synthesized slow-release fertilizers. Post-harvest soil extracts contained substantially lower extractable N (90–105 mg kg −1 ) than urea (250 mg kg −1 ), while extractable Si increased from a low baseline to 3.5–5.5 mg kg −1 for the silica-doped pellets. Overall, the MSNs doped porous biocarbon provides a promising, sustainable route to design dual-function fertilizers.