Microbial responses in a cold waterlogged paddy field to different distances from a drainage ditch
ABSTRACT Cold waterlogged paddy field is a type of low-yield paddy soil, and opening a drainage ditch has been suggested to improve waterlogged paddy soil and to increase the rice yield. However, little has been done on the role of a drainage ditch in ameliorating waterlogged soil. In the present study, rice (Oryza sativa L.) yield, soil physicochemical properties, microbial abundances and community structures in the surface soil of a cold waterlogged paddy field, which has three treatments with different distances from a drainage ditch including 5, 15 and 25 m were investigated. The results showed that opening a drainage ditch had a significant effect on the rice yield and soil physicochemical properties. Sampling sites near the drainage ditch such as 5 m-site had higher yield and soil nutrients, however, 25 m-site had lower values. Bacterial 16S rRNA gene did not exhibit a regular pattern but fungal abundance decreased sharply with increasing distance from the drainage ditch. The most abundant bacterial phyla across all soil samples were Proteobacteria, Acidobacteria, Planctomycetes and Chloroflexi. Abundant fungal phyla were Ascomycota, Zygomycota and Basidiomycota. Three treatments had similar microbial community compositions but with different relative abundances. The Bray-Curtis distance demonstrated that microbial community structures were divided into two major groups, samples of 5 m- and 15 m-site clustered into one group and samples of 25 m-site was another group. Moreover, redundancy analysis revealed that soil redox potential and total reducing substances were significant factors in shaping microbial community structures. The abundant aerobic bacteria were observed at the 5 m- and 15 m-site, in contrast, abundant anaerobic bacteria were observed at the 25 m-site. In conclusion, opening a drainage ditch in cold waterlogged paddy fields affects rice yield, soil nutrients, microbial abundances and community structures.