Biotransformation of rice husk into organic fertilizer through vermicomposting

Abstract Rice husk (RH) is an abundant agricultural solid waste as a result of rice-milling process. The present study investigated the potential of converting RH amended with market refused fruit (market refused banana (B), honeydew (H) or papaya (P)) into vermicompost using Eudrilus eugeniae . RH was mixed with market refused fruit in an equal ratio to produce three different treatments (1B:1RH, 1H:1RH and 1P:1RH) for laboratory screening of solid wastes. Generally, the application of E. eugeniae permitted an increase in calcium (6.9–99.0%), potassium (15.0–121.4%), phosphorus (2.4–49.5%) and carbon (6.5–69.0%) in final vermicompost after 9 weeks of vermicomposting. However, decreases in magnesium (3.7–45.7%) and nitrogen (6.9–23.7%) were also observed in final vermicomposts. Among all the RH treatments, RH which was mixed with market refused papaya (1P:1RH) showed better quality vermicompost with higher nutritional status. It was also found that RH which was amended by market refused fruit (1B:1RH, 1H:1RH or 1P:1RH), especially market refused papaya, encouraged the growth of earthworm as compared to the treatment with RH alone. The present data reveal that vermicomposting is a feasible technology for bio-transforming RH into value-added material, namely vermicompost.