Abstract:

To investigate the effects of direct straw return on soil properties under a facility−based paddy upland rotation system, this study set up five treatments: control (CK), 2y tomato straw return (TS2), 5y tomato straw return (TS5), one year maize straw return (MS1) and 4y maize straw return (MS4). Soil nutrients, enzyme activity and microbial community diversity were analyzed. Results showed that direct straw return significantly reduced the soil organic matter content and pH, with the decrease becoming more pronounced with increasing return years. Meanwhile, the return of straw significantly increased soil available potassium and phosphorus in the soil but decreased the nitrate nitrogen content. Soil bacterial richness and diversity decreased with increasing return years. Additionally, straw return increased the soil phosphatase, cellulase and urease activities, but decreased sucrase and nitrate reductase activities. Correlation analysis indicated that straw return reduced soil bacterial diversity, altered the community composition, making Rhodanobacteraceae and Gemmatimonadaceae the dominant groups and lead to changes in soil enzyme activities and ultimately resulting in alterations in soil physicochemical properties. This study demonstrates that direct straw return under a facility−based paddy−upland rotation system has significant impact on soil properties, providing a scientific basis for optimizing straw return techniques. 

Key words: Straw returning, Facility paddy?upland rotation, Soil nutrients, Microbial community diversity