Precomposting and green manure amendment for effective vermitransformation of hazardous coir industrial waste into enriched vermicompost

[Display omitted] •Hazardous coir pith can be converted into benign vermicompost with Sesbania sesban.•The fertilizing index of vermicompost was improved in the green manure amendment.•Nutrient recovery rate was higher in 30% green manure added coir pith vermicompost.•C/N ratio and seed germination index confirmed the vermicompost maturity.•Green manure and cow dung addition supported growth and fecundity of earthworms. Vermitransformation of coir pith (CP) into enriched vermifertilizer has been achieved by amending a green-manure plant, Sesbania sesban (SS) for the first time, and cow dung (CD) in five different combinations: T1(1:0:1), T2(4:3:3), T3(5:3:2), T4(5:4:1) and T5(1:1:0). The substrates were 28 days precomposted with Pleurotus sajor-caju followed by 50 days vermicomposting with Eisenia fetida and Eudrilus eugeniae. Results showed a significant reduction in cellulose, lignin, organic carbon, C/N ratio, C/P ratio and an increase in plant nutrients compared to control. The fertilization index and efficiency of nutrient recovery rate were higher in SS and CD amended CP vermicompost, with a maximum in T2(4:3:3) for E. fetida and T3(5:3:2) for E. eugeniae. The activity of dehydrogenase, urease and cellulase, and phytotoxicity assays further revealed vermicompost stability. The study concludes that T2(4:3:3) and T3(5:3:2) combinations respectively for E. fetida and E. eugeniae is suitable for vermitransformation of CP into enriched vermicompost.