玉米秸秆覆盖还田量对黑土微生物碳代谢活性与多样性的影响

  目的  针对东北黑土区长期集约化耕作导致的土壤退化问题，开展不同秸秆覆盖还田量对土壤微生物碳代谢特征的影响及其驱动因素的研究。  方法  采用MicroRespTM方法结合土壤碳氮含量等理化性质，测定土壤微生物碳代谢能力及其影响因素，使用Past v2.16、Canoco 5.0等软件对微生物群落功能多样性、结构差异以及土壤理化性质和微生物群落碳代谢特征间的关系进行分析。  结果  秸秆连续覆盖还田14年后，土壤微生物对羧酸类与氨基酸类碳源的代谢活性显著降低，但对外源碳底物的代谢多样性显著增强。67%和100%秸秆还田显著改变了土壤微生物群落碳源代谢结构，100%秸秆还田下微生物对芳香酸类碳源的相对代谢活性提高。土壤微生物对碳源的代谢活性主要与土壤碳氮含量显著相关，土壤可溶性碳与碱解氮含量分别是影响土壤微生物碳源代谢多样性和结构的主要理化因子。  结论  长期秸秆还田可以通过降低土壤微生物对易利用碳源的代谢需求、提高对碳源的代谢多样性而改善免耕土壤微生物碳代谢功能。本研究可为优化东北黑土区保护性耕作管理模式、促进该地区农业可持续发展提供微生物学参考。

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, MicroRespTM 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.