Impact of Corn Stover Mulch Quantity on Microbial Carbon Metabolic Activities and Diversity of Black Soil

  Objective  Aiming to propose support for solving soil degradation caused by long-term intensive tillage in Northeast China, this study was carried out to explore the impact of corn stover mulch quantity on soil microbial carbon metabolism characteristics and its driving factors.

  Method  Combining with soil carbon and nitrogen contents and other physicochemical properties, MicroResp^TM method was used to determine soil microbial carbon metabolic activity and its influencing factors. Software including Past v2.16 and Canoco5.0 were used to analyze the microbial carbon metabolic diversity and structure variations, as well as their correlations with soil physicochemical properties.

  Result  The results showed that microbial metabolic activities of carboxylic acids and amino acids were significantly reduced by corn stover mulch, but microbial carbon metabolic diversity indices were significantly increased. Moreover, 67% and 100% corn stover mulch significantly changed microbial carbon metabolic structure, and the latter significantly increased the relative metabolic activities of aromatic acid carbon sources. Microbial metabolic activities of carbon sources were mainly related to soil carbon and nitrogen contents. Soil dissolved organic carbon and alkaline hydrolysable nitrogen were the main physicochemical factors affecting microbial carbon metabolic diversity and structure, respectively.

  Conclusion  Long-term corn stover mulch could improve soil microbial carbon metabolic functions by reducing microbial metabolic demand for readily available carbon sources and increasing microbial carbon metabolic diversities. This study will provide microbial references for optimizing conservation tillage management model and promoting sustainable agricultural development in Northeast China.