The influence of soil properties on the size and structure of bacterial and fungal communities along a paddy soil chronosequence

• We explore the bacterial and fungal communities in a paddy soil chronosequence.
• The Illumina MiSeq was applied to the microbial community structure studies.
• Soil microbial PLFAs were higher under paddy management than arable cropping.
• Bacterial succession of paddy and arable soil were similar.
• Orderly succession of soil bacterial and fungal communities occurred.

In agroecosystems, soil bacterial and fungal communities are crucial for soil and plant health because of their diverse metabolic functions. However, little is known about the effect of long term paddy management on microbial communities. This study was conducted to assess the responses of the soil bacterial and fungal communities to cultivation history along a paddy soil chronosequence by using phospholipid fatty acid (PLFA) profiling and Illumina HiSeq sequencing. Soil samples were collected from the paddy fields (50, 100, 300, 1000, and 2000 years of paddy use; P50-P2000-), the adjacent arable chronosequence (50, 100 and 300 years of land use; NP50-NP300) and mudflat (estuarine sediment, representing the parent material for paddy and arable soil reclamation). The results showed that soil microbial biomass PLFAs increased significantly with increasing soil organic C which accumulated more under paddy than arable management. Bacterial taxonomic groups assigned to Proteobacteria and Acidobacteria changed relatively in the transition from tidal wetland to agricultural land. The relative abundances of dominant bacterial phyla in paddy soil orderly changes with cultivation time. The dominant fungal phyla in all samples were Ascomycota, Chytridiomycota, Basidiomycota, Glomeromycota and Zygomycota, representing 18.50%, 18.46%, 10.02%, 7.34%, and 7.19%, respectively. The succession of fungal community structure was mainly associated with changes in Ascomycota. Correlation analysis showed that higher soil total carbon and nitrogen related to long-term cultivation were associated with lower Proteobacteria and Ascomycota, but higher Verrucomicrobia. Furthermore, different land use type differed significantly in their fungal composition, but likely had similar effects on the succession of bacterial composition, mainly the Proteobacteria and Acidobacteria. Our results indicate that orderly succession of soil bacterial and fungal communities occurred along the long-term development of paddy soil, which in turn was associated with changes in soil physicochemical properties over time.