Effects of Straw Returning on Soil Chemical Properties and Microbial Community Diversity under the Rice-Crayfish Integrated System

This study presents an investigation of soil chemical properties and microbial community diversity by Biolog ECO analysis in a seven-year field experiment using winter flooded fallow + no straw returning (W), winter flooded fallow + straw returning (WS), and winter flooded fallow + straw returning + crayfish farming (WSC) at soil depths of 0-10 cm and 10-20 cm. Compared with the WS treatment, the WSC treatment had significantly higher total organic carbon (TOC) content in the 0-10 cm layer as well as greater available nitrogen (AN) and total nitrogen (TN) contents and acid phosphatase and sucrase activities in the 10-20 cm layer, while the pH value, total reducing substances, and Fe2+ content in the 0-20 cm layer were considerably lower. The WSC treatment improved the microbial species abundance in the 10-20 cm layer and the utilization rate of carbon sources in the 0-20 cm layer compared with the WS treatment. The soil microbial species abundance, microbial community diversity, and utilization rate of carbon sources in all of the layers examined were significantly higher in the WSC treatment than in the W treatment. The results indicate that straw returning under the rice-crayfish integrated system improves the contents of TOC, TN, and AN, decreases reducing substances properties, increases acid phosphatase and sucrase activities, and improves microbial community functional diversity, thereby contributing to the improvement of soil quality and the long-term sustainable development of the rice-crayfish integrated system.