Low-pyrolysis-temperature biochar promoted free-living N2-fixation in calcareous purple soil by affecting diazotrophic composition

Abstract Free-living nitrogen fixation (FNF) is an important input of nitrogen to minimise the use of inorganic nitrogen fertiliser in agricultural ecosystems, but knowledge regarding response of FNF to biochar amendment is still limited. A microcosm study was performed to investigate changes in soil nitrogen content and FNF efficiency for calcareous purple soil applied with biochars prepared at 300 °C (CB300) and 600 °C (CB600). After 56 d of incubation, both CB300 and CB600 applied at any rates significantly (P