Data for opposing effects of maize straw and its biochar on soil N2O emissions by mediating microbial nitrification and denitrification in a subtropical Moso bamboo forest

Application of straw and biochar has been shown to significantly affect greenhouse gas emissions from soil. However, microbial mechanisms underlying the effects on soil N2O effluxes within subtropical Moso bamboo forests remain elusive. This study aimed to assess the contrasting influences of maize straw and its derived biochar on soil N2O emissions by meditating key functional microbial genes and communities involved in soil nitrification and denitrification within a subtropical Moso bamboo forest. Straw amendment (5 t C ha−1) stimulated N2O emission by 16–27% (P −1) reduced available N, i.e., 11.1–13.9% for NH4+, 11.0–14.8% for NO3− and 13.8–16.6% WSON, and decreased the abundances of nitrification/denitrification genes (39.0–44.6% for AOB amoA, 29.5–35.5% for nirK, 24.4–31.8% for nirS) and associated genera Nitrosospira, Mesorhizobium, Bradyrhizobium, Rhizobium, Pseudomonas, and Cupriavidus. Biochar also decreased the activities of enzymes related to organic N hydrolysis (protease and urease) and denitrification (nitrate reductase and nitrite reductase); and thus decreased N2O emissions by 17–20% (P nosZ gene (39.9–45.9%) and its dominant genera (Mesorhizobium, Bradyrhizobium, and Azospirillum), which facilitated N2O reduction. In contrast, straw inhibited growth of these dominant genera and lowered the abundance of nosZ gene (24.4–38.3%); thereby increasing N2O emissions. These results highlight the varied responses of nitrification and denitrification processes and hence N2O emission to the application of straw and biochar in soils of a subtropical Moso bamboo forest.