Responses of Corn Yield to Soil Microorganisms, Labile Organic Carbon Fractions Under Integrated Straw Return and Tillage Practices in Black Soil

Straw return is a crucial strategy for enhancing soil organic matter (SOM). However, the mechanism of combing straw return with different tillage methods on black soil microbial community structure, soil organic carbon (SOC) fractions remained unclear. A field experiment was conducted in black soil using four tillage treatments: conventional tillage without straw return (CK), no-tillage with straw incorporation (NTS), rotary tillage with straw incorporation (RTS) and deep tillage with straw incorporation (PTS). Corn yield, the contents and fractions of SOC were measured, whereas the microbial structure at different soil depths was assessed by high-throughput sequencing technology. Meanwhile, the correlations between microbial diversity, changes in SOC fractions, and corn yield was analyzed. As results, the return straw treatments significantly increased the contents of SOC in the 0-20 cm soil layer (up to 19.82 g kg-1 under RTS) and its labile fractions, enhanced soil microbial diversity (with an 7.03%-25.14% promoting in Bacterial Chao1 index) and optimized of microbial community structure. Fungal diversity under PTS was the most prominent in the 20-40 cm depth. Correlation analysis indicated that the active SOC fractions and microbial diversity jointly explain the yield variation. The findings of this study provide theoretical for optimizing of the supporting tillage technology for straw return to field, and has important practical guiding value for the conservation of black soil and the coordinated improvement of production capacity.