Vermicomposting of vegetable-market solid waste using Eisenia fetida: Impact of bulking material on earthworm growth and decomposition rate

Vegetable-market solid waste is produced in millions of tones in urban areas and creates a problem of safe disposal. The aim of this study was to convert vegetable solid waste (VW) amended with wheat straw (WS), cow dung (CD), and biogas slurry (BGS) into vermicompost using earthworm Eisenia fetida. VW was mixed in bulky materials (WS, CD, and BGS) in different ratios to produce eight different combinations for laboratory screening of wastes for 15 weeks. The vermicomposting caused a decrease in organic C (12.7–28%) and C:N ratio (42.4–57.8%), while increase in total N (50.6–75.8%), available P (42.5–110.4%), and exchangeable K (36.0–78.4%) contents. Waste mineralization and humification rates were higher in bedding those containing easy digestible bulky agents, i.e., BGS and CD. Worm-processed material obtained from BGS:VW (1:2) vermibed showed the higher total N (31.3 g kg−1), available P (8.7 g kg−1) and exchangeable K (20.7 g kg−1) contents. The nutrient-rich vermicompost with acceptable C:N ratio ranges (≥1:20) indicates its agronomic potentials. Waste mixtures also supported the earthworm growth and reproduction rates in vermibeds. The results indicated that vermicomposting can be an efficient technology to convert negligible vegetable-market solid wastes into nutrient-rich biofertilizer if mixed with bulking materials in appropriate ratios.