The contribution of earthworms to carbon mineralization during vermicomposting of maize stover and cow dung.

Vermicomposting is an eco-friendly way to manage agricultural wastes. Maize stover and cow dung were used as the substrates. Earthworm ingestion and respiration models were employed to quantify earthworm contributions to carbon mineralization. Decreased substrate C/N and slightly increased earthworm tissue C/N were observed. Earthworm biomass carbon first increased and then decreased. Bacterial biomass carbon decreased, while fungi increased and maintained a steady level until the end of the experiment. Bacteria dominated throughout the process. The earthworm feeding rate showed a decreasing trend. In the early, middle and later stages, earthworms directly led to carbon mineralization rates of 0.030, 0.032 and 0.023 g C m month, and indirectly led to 0.197, 0.211 and 0.153 g C m month, respectively. It indicated that the driving force exerted by earthworms on microbes was more important. This study provides some new insights into the quantification of earthworm contributions to carbon mineralization during vermicomposting.