Relay maize after tobacco enhances rapeseed growth and nutrition by reshaping soil microbial communities in an annual...

Multiple cropping systems are increasingly being adopted worldwide to improve land-use efficiency and promote sustainable agriculture. To optimize the traditional post-tobacco fallow period, we evaluated a novel tobacco-maize-rapeseed (T_M_R) triple-cropping system. Using field experiments and high-throughput amplicon sequencing, we investigated the effects of the preceding tobacco crop and the additional maize season on rapeseed performance and soil microbial ecology. The addition of a maize season enhanced early growth vigor of rapeseed and improved key yield components, resulting in a theoretical yield of 5388.48 kg/ha. Rapeseed nitrogen uptake significantly increased compared with the conventional rotation (P < 0.05), and was positively associated with soil alkali-hydrolyzable nitrogen and major yield components. Different cropping systems significantly reshaped the β-diversity of soil microbial communities in the root-zone soil of rapeseed. Under the maize addition treatment, bacterial co-occurrence networks exhibited greater connectivity and complexity. Chujaibacter, Sporosarcina, and Epicoccum were enriched and identified as discriminative taxa using random forest analysis. In conclusion, the tobacco-maize-rapeseed triple-cropping system enhances nitrogen nutrition and reshapes soil microbial communities, providing a sustainable strategy for improving crop performance and agroecosystem functioning.