To investigate the effects of fertilization regimes on nitrogen-transforming functional guilds in the rapeseed rhizosphere，real-time fluorescence quantitative PCR was employed to systematically evaluate the differences in the abundances of nitrogen-transforming microbial guilds between rhizosphere and bulk soils under various long-term fertilization treatments:no fertilization control(CK)，inorganic fertilizer alone(NPK)，organic fertilizer alone(M)，combined organic-inorganic fertilization(MNPK)，inorganic N-K fertilizer(NK)，and inorganic N-P fertilizer(NP).The results demonstrated that the shift trends in the abundances of nitrogen-transforming guilds in the rhizosphere and bulk soils were generally consistent across the fertilization treatments.Inorganic fertilization significantly increased the abundances of ammonia-oxidizing bacteria，Nitrobacter，and nirKC1-type denitrifiers.In contrast，the M and MNPK treatments，particularly the latter，markedly enhanced the abundance of diverse nitrogen-transforming guilds，including complete ammonia oxidizers(Comammox)clades A and B，Nitrospira，napA-type nitrate reducers，nirSC1- and nirSC2-type denitrifiers，nosZI-type N2O reducers，and dissimilatory nitrate reduction to ammonium bacteria.Fertilization regimes showed no significant effects on the abundance of Geobacter or nitrogen-fixing bacteria in bulk soil.Only ten functional groups (including nitrogen-fixers，ammonia-oxidizing archaea，Comammox clades A and B，and nirKC1-type denitrifiers)exhibited significant differences in abundance between the rhizosphere and bulk soils under specific fertilization treatments.Redundancy analysis revealed that application of organic fertilizer was the dominant factor driving community-level variations innitrogen-transforming guilds.Correlation network analysis demonstrated significant interconnections among most nitrogen-transforming guilds in the rhizosphere and bulk soil，thereby forming tightly linked networks.Random forest analysis indicated that soil properties，particularly available phosphorus，served as primary predictors for abundance variations in some microbial groups，while changes in the abundances of other guilds predominantly explained variations in the majority of nitrogen-transforming groups.In conclusion，combination of organic and inorganic fertilizer significantly increased the abundance of nitrogen-transforming functional guilds in the rapeseed rhizosphere，improved nitrogen turnover activity，and consequently promoted an efficient nitrogen supply for crop growth while enhancing nitrogen uptake and productivity.These findings could provide a theoretical basis for promoting the combination of organic and inorganic fertilizers in agricultural production.