Valorization of Kitchen Waste and Complementary Organic Biomass into a Liquid Fertilizer: Characterization and Agronomic Validation in Capsicum chinense

Purpose This study developed a multi-component liquid fertilizer by valorizing household kitchen residues together with complementary organic biomass and evaluated its agronomic functionality as a complementary input to mineral fertilizer. Methods Banana peels, eggshells, onion peels, fresh Azolla pinnata , and cattle manure were processed through a 21-day staged aerobic preparation. The undiluted stock was characterized for pH, electrical conductivity, and nutrient composition. Agronomic validation used container-grown Capsicum chinense in a completely randomized design with eight fertilizer treatments and five replications under shade-net conditions. Results The stock had a pH of 5.16, an electrical conductivity of 3.57 mS cm⁻¹, and contained total N (0.02%), available P (0.035%), ammonium acetate-extractable K (0.43%), and Ca (0.57%). The liquid fertilizer alone produced no marketable fruits. In contrast, several integrated liquid-fertilizer–mineral-fertilizer treatments produced vegetative growth and fruit yields that were not significantly different from full mineral fertilization. The highest numerical yield was 201 g plant⁻¹ with 25% liquid fertilizer + 75% mineral fertilizer. Conclusion The developed fertilizer was inadequate as a sole nutrient source but, when combined with mineral fertilizer, supported Capsicum chinense yields that were not significantly different from those of full mineral fertilization, indicating its potential as a complementary input at reduced mineral-fertilizer application rates.