OICC Press International Journal of Recycling of Organic Waste in Agriculture 2251-7715 15 2 2026 06 30 Yield and Profit Improvement of Maize Utilizing Optimal Planting Density and Rice-Husk Waste as Effective Silicon Fertilizer 10.57647/ijrowa.2026.18325 EN Slameto Slameto Research Center for Behavioral and Circular Economics. Governance, Economics, and Community Welfare Research Organization, National Research and Innovation Agency, Jl. Gatot Subroto 10, Jakarta 12710, Indonesia https://orcid.org/0000-0002-2254-5234 Erythrina Erythrina Research Center for Food Crops. Agricultural and Food Research Organization, National Research and Innovation Agency, Jl. Raya Jakarta-Bogor KM 46, Cibinong 16911, Indonesia https://orcid.org/0000-0002-5665-5095 Endriani Endriani Research Center for Food Crops. Agricultural and Food Research Organization, National Research and Innovation Agency, Jl. Raya Jakarta-Bogor KM 46, Cibinong 16911, Indonesia https://orcid.org/0000-0002-4161-8312 Valeriana Darwis Research Center for Behavioral and Circular Economics. Governance, Economics, and Community Welfare Research Organization, National Research and Innovation Agency, Jl. Gatot Subroto 10, Jakarta 12710, Indonesia https://orcid.org/0000-0001-5704-8927 Journal Article 2026 06 30 Purpose: Using silicon fertilizer from rice husk waste and double-narrow row (DNR) plant spacing can increase maize yield. Therefore, the study aimed to improve farmers' productivity and profitability by applying biosilica fertilizer with DNR plant spacing and closing the maize yield gap. Method: The field experiment was set up in a completely randomized design with three replications in a 2 × 6 × 2 factorial arrangement consisting of two plant spatial arrangements:  DNR and conventional row (CR) plant spacing; six maize cultivars: Pioneer-27, Bisi-18, NK-22, JH-37, RK-457, and RK-57; and two levels of biosilica fertilizer application in the form of Si-nanoparticles: with and without biosilica fertilizer. We observed the correlation among yield and yield components, yield increase, profitability, and yield gap analysis. Results: The number of seeds per row and the number of leaves per plant both showed the highest estimates of positive correlation and positive direct effect as the dominant characteristic that directly affected the variation of maize grain yield. Application of biosilica fertilizer with DNR plant spacing indicated a significant increase in maize productivity of 0.96 t ha–1 or 9.90% and additional net return gains of USD 183.49 ha–1 compared to CR plant spacing without application of silicon fertilizer. This represents an exploitable yield gap of 21.35% Conclusion: The DNR planting system and the application of biosilica fertilizer from rice husks were consistently more effective than CR spacing without biosilica fertilizer, demonstrating their reliability and potential for increasing maize yields, improving net income, and narrowing the yield gap. Highlights ·        Double-narrow-row (DNR) was compared to conventional row (CR) plant spacing ·        Maize yield was 10% higher with DNR plus biosilica fertilizer ·        Farmers get additional net return gains of USD 183 ha–1 per cycle ·        There is room for increasing maize productivity by closing exploitable yield gaps ·        DNR with biosilica fertilizer as an innovative approach to sustainable agriculture