The accumulation of agricultural waste poses significant agronomic and environmental challenges in tropical smallholder farming systems where organic wastes remain underutilized. This study evaluated the effectiveness of vermicomposting with Eisenia fetida in enhancing nutrient recovery and improving the quality of organic fertilizers produced from agricultural waste. Four substrate treatments—poultry manure and vegetable waste (T1), cow dung, chicken manure, and vegetable waste (T2), cow dung and vegetable waste (T3), and a control without earthworms (T4)—were assessed over a period of 60 days. Key physicochemical properties evaluated included bulk density, pH, electrical conductivity, organic carbon, total nitrogen, available phosphorus and potassium, and the C:N ratio. Vermicomposting significantly improved nutrient composition, with the C:N ratio decreasing from 26.43 in the control treatment to 12.23, indicating enhanced compost maturity. Treatment T2 recorded the highest concentrations of total nitrogen (2.63%), phosphorus (1.21%), and potassium (1.45%). A significant reduction in organic carbon also indicated enhanced mineralization during the decomposition process. Compared with traditional composting, vermicomposting improved nutrient availability, compost maturity, and overall compost quality. These findings demonstrate that vermicomposting is an effective resource recovery strategy for converting agricultural waste into nutrient-rich organic fertilizer while supporting sustainable and climate-resilient agricultural systems.
Mbuku et al. (Thu,) studied this question.