Biochar-induced changes in the soil diazotroph community abundance and structure in a peanut field trial

Abstract Biological nitrogen fixation (BNF) can help replenish available (N) in cropland and reduce the use of chemical N fertilizers, with diazotrophs playing an important role. However, response diazotroph community BNF activity biochar amendment soil, especially deep soil horizon, are poorly understood. In this study, samples were collected from topsoil (0–20 cm) subsoil (20–40 field experiment (established 2013) comprising treatments no fertilizer (CK), (NPK), (BC), plus fertilizers (BNPK). Here, we investigated using real-time PCR high-throughput sequencing nifH gene, assessed 2 rate (R Nfix ) acetylene reduction assay (ARA). Results showed that topsoil, significantly increased gene copies R , which was consistent organic matter (SOM), total carbon-to-nitrogen ratio (C/N), dissolved carbon (DOC) pH. subsoil, applying (NPK) strongly decreased but had effect on abundance; contrast, application (BC) suppressed growth bacteria while increasing abundance Rhizobiales order. Diazotroph bacterial positively correlated both top- sub-soil, they mainly influenced by SOM (TN). addition, nitrate (NO 3 − –N) major factor shaping vertical stratification structure. Although structure equation modeling (SEM) highest correlation between . Hence, suggested sources key factors changes pattern abundance. Biochar induced dominant succession content pH, contributed to activity. Changes driven variation