Metagenomic and q-PCR analysis reveals the effect of powder bamboo biochar on nitrous oxide and ammonia emissions during aerobic composting

To investigate the emission mechanism of ammonia (NH3) and nitrous oxide (N2O) during aerobic composting and the influence of powder bamboo biochar (PBB) on this process, this paper conducted a systematic study on the nitrogen-transforming functional microbial community, including functional genes, microbial structure and metabolism pathways. PBB reduced N2O and NH3 emissions by 1.25%–8.72% and 10.4%–11.8%, respectively. The quantitative PCR results indicated that the reduced N2O emission by PBB were mainly related to denitrifying genes (nirS, nirK, nosZ, and narG). The metagenome results demonstrated that Nitrosococcus was the main genus that could oxidize ammonia to nitrite decreased by PBB. The PBB significantly affected the nitrogen metabolism pathway, reduced the activity of glutamate dehydrogenase to inhibit the formation of NH4+ to reduce NH3 emission. The higher N2O emission in the control group was also related to the higher relative contents of hydroxylamine reductase and nitrite reductase.