Abstract: We investigated the impacts of long-term rice-crayfish rotation on physicochemical properties and bacterial community structure in paddy soils. Chemical analysis methods and high-throughput sequencing of 16S rRNA amplicons were employed to examine the soil physicochemical properties and bacteria community structures in rice monoculture and rice-crayfish rotation systems with durations of 4, 8, and 21 years. Results showed that ricecrayfish rotation significantly increased total phosphorus content by 37.01%-54.33% (P<0.05), but decreased available phosphorus content by 60.21%-61.10% (P<0.05) compared to rice monoculture. Results of principal coordinate analysis and multivariate analysis of variance showed significant differences in soil bacteria community structure across systems with different rotation years (P=0.004). Long-term rice-crayfish rotation increased the relative abundance of Aminicenantia (family, order, class, genus) and Sva0485 (family, order, class, genus) in paddy soil. Redundancy analysis (RDA) results identified organic matter and available nitrogen as key factors influencing bacterial community structure. Overall, rice-crayfish rotation affected soil phosphorus levels and altered the abundance of bacterial phyla, without impacting community diversity in soil bacteria. Our results provide valuable insights into the impact of rice-crayfish rotation on paddy soil bacterial communities.

Key words: rice-crayfish rotation, rotation year, bacterial community, soil physicochemical property