Effects of phosphorus modified nZVI-biochar composite on emission of greenhouse gases and changes of microbial community in soil

The effect of modified biochar on the greenhouse gas emission in soil is not clear until now. In this study, biochar (BC) was modified by phosphoric acid (P) and further combined with nano-zero-valent iron (nZVI) to form nZVI-P-BC composite. The P modified biochar could significantly increase the available phosphorus in soil. The release of CO2 and N2O in soil was inhibited during the initial stage of the experiment, with inhibition becoming more obvious over time. On the contrary, CH4 and N2O emission in soil was enhanced by nZVI-P-BC composite. The proportion of Sphingomonas and Gemmatimonas were the most abundant bacterial species, which were related to the metabolism and transformation of nitrogen. The community structure of the fungus was also affected by nZVI-P-BC composite with Fusarium as the main species. PCoA analysis result suggested that bacterial community was more affected by the incubation time while fungal community was more related to the addition of different biochar and modified biochars. [Display omitted] •P modified biochar and nZVI biochar composite was developed.•P modified biochar can increase the available P in soil.•The CO2 and N2O emission were mitigated by P modified biochar.•The CH4 emission was enhanced by nZVI-BC composite in soil.•Microbial community was affected by both incubation time and biochar addition. Capsule: P modification of biochar enhanced the stability and further developed nZVI-P-BC composite inhibited greenhouse gas emission in soil.