The potential reuse of soybean husk as feedstock of Eudrilus eugeniae in vermicomposting

BACKGROUND: Soybean (Glycine max L.) is one the most commonly consumed legumes worldwide, with 200 million metric tons produced per year. However, the inedible soy husk would usually be removed during the process and the continuous generation of soybean husk may represent a major disposal problem for soybean processing industries. Thus, the main aim of the present study was to investigate the possibility to convert soybean husk (S) amended with market-rejected papaya (P) into vermicompost using Eudrilus eugeniae. RESULTS: Soybean husk was mixed with market-rejected papaya in different ratios to produce five different treatments (1P:1S, 2P:1S, 1P:2S, S only and P only) for laboratory screening of solid wastes. Generally, the application of E. eugeniae permitted a significant increase in Ca (42.3-91.6%), K (93.8-235%), Mg (25.4-84.6%) and P (37.1-129%) but a decrease in the C:N ratio (21.4-52.8%) after 9 weeks of vermicomposting. Among all the treatments investigated, soybean husk which was mixed with an equal amount of market-rejected papaya (1P:1S) showed superior quality vermicompost. Waste mixtures also encouraged the growth of E. eugeniae except the treatments with soybean husk alone as well as soybean husk which was mixed with market-rejected papaya in 1P:2S ratio. CONCLUSION: Vermicomposting could be used as an efficient technology to convert soybean husk into nutrient-rich organic fertiliser if it was mixed with market-rejected papaya in appropriate ratio. (C) 2011 Society of Chemical Industry