Microbial driving mechanism of biochar and bean dregs on NH3 and N2O emissions during composting

In this study, the effect of biochar (BC) and bean dregs (BD) on nitrifiers and denitrifiers as well as the contributions to the NH3 and N2O emissions were investigated. Compared with the BD treatment, the maximum value of NH3 and N2O emission was decreased by 32.92% and 46.61% in the BD + BC treatment, respectively. The production of NH3 and N2O was closely associated with the abundance and structure of nitrogen functional genes. BD + BC increased the abundance of AOB amoA gene to decrease the NH3 emission. The abundance of nirS was more closely associated with N2O. The abundance of nirS in the BD + BC was lowered by 18.93% compared with the BD treatment, thereby decreasing the N2O emission after composting. Besides, the nosZ-type gene was the more functional denitrification bacterial communities to effect the N2O emissions.