Vermiconversion of biogas plant slurry and parthenium weed mixture to manure

Purpose Parthenium hysterophorus is one among the most troublesome weeds at the global level. It is mainly con- trolled by chemical methods. The scientific community is in search of new but non-destructive approaches for its management. Vermicomposting is one among the promis- ing technologies for the management of organic fraction of solid wastes. This study was undertaken to assess the vermicomposting of parthenium weed mixed with biogas plant slurry under laboratory conditions. Method Six different combinations of biogas plant slurry and parthenium were fed to worms in vermibins under controlled laboratory conditions for 60 days. Various physico-chemical parameters before and after vermicom- posting were evaluated. Worm biomass production was also monitored periodically during the experimentation period. Results The EC, TCa and NPK content increased signifi- cantly after vermicomposting, accompanied by substantial reduction in organic carbon content. C: N ratio was reduced to less than 20. Heavy metals (Fe, Zn, Ni, Cu, Cr and Pb) concentration was higher in vermicompost than in initial waste mixtures. Parthenium weed addition to worm feed was not supportive to the worm growth and fecundity. It was inferred from the results that vermicomposting may be an efficient biological approach to convert parthenium- spiked biogas plant slurry into nutrient-rich manure.