Synergistic effects of bamboo biochar and ammonia oxidizing bacteria on nitrogen transformation and microbial dynamics during vermicomposting of green waste and chicken manure

This study aims to explore the impact of bamboo biochar or/and ammonia-oxidizing bacteria on the nitrogen transformation and microbial dynamic factors during green waste and chicken manure co-vermicomposting. The results revealed that the addition of bamboo biochar combined with microbial agents significantly improved the overall quality and maturity of vermicompost by enhancing organic matter degradation, humus formation, humic-fulvic acid ratio, carbon-to-nitrogen ratios and germination index. The combined addition led to a substantial reduction in ammonia emissions (67.96 %) along with a notable increase in nitrate nitrogen (79.01 %) and total nitrogen (22.49 %) accumulation. Moreover, jointly adding bamboo biochar and microbial agents enriched the level of ammonifying bacteria Nitrosospira and Nitrosomonas and increased the activities of ammonia monooxygenase, hydroxylamine oxidase, and nitrate oxidoreductase. Furthermore, the combined addition enriched the beneficial bacteria, such as Cellvibrio, Pseudomonas, Nonomuraea, Pseudoxanthomonas, etc., which are involved in organic matter degradation and phosphorus transformation, while inhibiting denitrifying bacteria. Therefore, this study recommends the co-addition of bamboo biochar and microbial agents as an effective approach to improve vermicompost quality and inhibit nitrogen loss during green waste and chicken manure vermicomposting.