Biochar amendment stimulates nitrous oxide emission from tobacco-planting soil by regulating the microbial community composition. Biochar amendment stimulates nitrous oxide emission from tobacco-planting soil by regulating the microbial community composition

BC application increased soil N2O emission during the tobacco growing season. Compared to control (B0), cumulative N2O emissions significantly increased by 1.96-, 4.16-, 2.67-, and 4.18-fold in the BC1, BC2, BC3, and BC4 treatments, respectively, mainly due to enhanced soil substrate availability by N-rich tobacco BC. Shifts of bacterial community structure due to the BC amendment could occur at the phylum level, while for the fungi, the changes could be demonstrated at the genus level. Abundance of denitrifying bacteria (e.g. Bradyrhizobium, and Pseudomonas) and denitrifying fungi (e.g. Trichocladium, and Trichoderma) was significantly increased with BC amendments, contributing to the stimulated N2O emissions by affecting the aerobic denitrification of microbes. This study broadens our understanding of the specific field conditions under which BC could have stimulating effects on N2O emission. Mitigation potential of BC application should be reconsidered if N-rich BC were amended to aerobic soils.