Organic manure rather than phosphorus fertilization primarily determined asymbiotic nitrogen fixation rate and the stability of diazotrophic community in an upland red soil

Biological nitrogen fixation (BNF) plays a vital role in supply agricultural ecosystem but is generally impaired by fertilization. Understanding the trade-off between fertilization and BNF, underlying mechanisms are essential to optimize management for sustainable agriculture production. In this study, we examined potential rate of asymbiotic N2 fixation, nifH gene abundance, composition co-occurrence network diazotrophic community an acidic red soil received different organic inorganic regimes more than 40 years. Our results showed that long-term chemical fertilizer application drastically decreased microbial biomass, nitrogenase activity abundance comparison unfertilized control. Organic manure significantly positive effect on crop yield via regulating pH key ecological cluster (module #2 which was mainly represented Bradyrhizobium, Pseudacidovorax Azospirillum), while phosphorus no obvious promotion effect. amendment increased diversity diazotrophs enriched some taxa, particularly Rhodopseudomonas were likely responsible high N2-fixation potential. The control treatments possessed complex stable did, greatly facilitated resistance environmental stress thus sustained Together, our study demonstrated can effectively alleviate inhibitory property shaping network.