Bioconversion of Residue Biomass from a Tropical Homestead Agro-Ecosystem to Value Added Vermicompost by Eudrilus Species of Earthworm

Abstract

Homestead farming systems generate in addition to the economic produce, huge quantities of diverse agro-wastes, which are resources containing significant levels of plant nutrients and organic carbon. This biomass resource is either grossly underutilized or completely unutilized, posing disposal or environmental problems. To utilize these organic wastes effectively, a study was undertaken on bioconversion of residue biomass with different characteristics to value added vermicompost for use in crop production. Physico-chemical characteristics of residue biomass were determined. Vermicomposting experiment was carried out with residue biomass from 14 crops/trees taken individually and cow dung in the ratio of 10:1 using an indigenous epigeic earthworm belonging to Eudrilus species. Quality and maturity parameters of vermicompost obtained were assessed. The bioconversion efficiency and the earthworm multiplication varied significantly among the residue biomass of different crops/trees. The biomass materials from banana, arecanut palm, coconut palm, rubber, teak, and cassava plants as well as weeds were vermicomposted with a conversion efficiency of > 60%. During the vermi-stabilization process, carbon loss was 50% from residues of teak, banana, wild jack fruit tree, coconut palm and cocoa. Bioconversion resulted in an increase in pH, electrical conductivity and major plant nutrients (N, P) while C:N and C:P ratios decreased in all crop residues. Significant relationship between major plant nutrients in crop residues with maturity parameters of vermicompost was demonstrated. Vermi-stabilization holds promise as a biological tool for management of residues of crops/trees in homestead farming system. However, certain residues were not efficiently converted to vermicompost and might require pretreatments or mixing of residues to achieve higher efficiency of bioconversion.