Sulfur and nitrogen co-metabolism during composting: A role of sodium sulfide in regulating microbial communities and functional genes

Aerobic composting is an effective method for treating livestock and poultry manure. However, traditional aerobic composting often results in nitrogen loss and excessive N 2 O gas pollution in the atmosphere. In this study, metagenomics technology was used to investigate the co-metabolism of sulfur and nitrogen in composting with Na 2 S as an additive. The results showed that the content of nitrate and sulfate in the experimental group (T) was 19% and 34% higher, respectively, than that in the control group (CK) after composting maturation. The denitrification genes ( narG, narH, nirK, and norB ) and sulfur reduction gene ( sat ) in T were significantly inhibited, particularly on the fourth day. Actinobacteria and Proteobacteria were the dominant bacteria involved in sulfur and nitrogen co-metabolism. These findings indicated that the addition of Na 2 S effectively inhibits denitrification in composting, reducing N 2 O emissions and nitrogen loss, while increasing sulfate content and improving the quality of composting.