Vermicomposting treatment of vegetable waste and its greenhouse gas emissions

Vermicomposting is a new effective method in disposing organic waste these years. In order to investigate the effect and greenhouse gas emission rules of vermicomposting, an experiment of vermicomposting used cow dung and fresh tomato stems as raw material was carried out in earthworm culturing farm, taken conventional-composting as control treatment. The changes of maturity indexes and greenhouse gas emission rules were compared and studied. Results showed that the temperature of vermicomposting was lower than that of conventional-composting, which could not reach the harmless standard (the temperature should be above 50-55℃ and lasts for 5-7 days), but the low temperature was beneficial to earthworm, so the earthworms of earthworm increased from (14.6-20.8) ×103 /m3 in 0-10 d to 90.2×103/m3 in the final period. According to the maturity indexes of pH, electric conductivity, C/N ratio and germination index, vermicomposting can shorten the composting cycle and had a higher degree of maturity. Compared with conventional-composting, N losses was reduced by 30.8%, greenhouse gas emissions reduced by 35.9%, CH4, N2O and NH3 by 14.7%, 17.4% and 46.1% respectively for vermicomposting. Therefore, vermicomposting can reduce N losses and greenhouse gas emissions during composting. This study can provide a new approach and reference to organic solid waste recycling and reduction of greenhouse gas emissions.