Cropping system has stronger effect on Tobacco soil bacterial community than fertilization

Abstract Purpose Soil microorganisms are involved in many key processes in the soil ecosystem, including nutrition cycling, organic matter turnover, and soil structure maintenance. However, their responses to fertilization and different tillage systems in tobacco soils remain poorly understood. Methods In this study, we conducted a 19-year-long field experiment on rice-tobacco rotation cropping (R) and continuous tobacco cropping (C) with three treatments, i.e., no fertilizer (NF), chemical NPK fertilizer (NPK), and compost pig manure (OM). The composition, co-occurrence patterns, nitrogen cycle process of the bacterial communities and the soil properties were analyzed in the soils after tobacco was harvested. Results The pH and AK in the group R soil were markedly lower than those in group C, the α-diversity index, and number of N-cycling genes were opposite. The phyla Chloroflexi , Desulfobacterota , MBNT15 , and Nitrospinota , as well as number of low-abundancegenera, were significantly enriched in the rotation system. PICRUSt2 showed that the functional amino acid biosynthesis pathway, tricarboxylic acid cycle, and nucleic acid metabolism were significantly higher in group R than in group C. The application of OM in group C significantly increased the contents of soil nutrients and N-cycling genes, further changing the structure of the soil bacterial community. PERMANOVA suggested that variations in the bacterial communities and functions were more attributed to tillage systems than to fertilization practices. Conclusion After 19 years of cultivation, the effect of tillage on bacterial communities in tobacco soil was greater than that of fertilization. Together, these findings increase our understanding of the importance of land management and fertilization in shaping the soil bacterial of tobacco.