蚯蚓堆制秸秆过程中碳氮分解代谢及温室气体生成机制

Crop residues returning is beneficial for improving soil fertility and carbon sequestration. Returning pretreated crop residues has some advantages over untreated crop residues. Traditional composting produces a significant amount of greenhouse gases. In view of this, vermicomposting will be utilized to treat crop residues in this proposed research project. The contribution of earthworms, microbes and the interaction of them to the degradation of organic carbon and nitrogen, the shift of the microbial community structure, the temporal dynamics of the activity of key enzymes for degradation of organic carbon and nitrogen, the abundance of GH and denitrifying genes and the emission of greenhouse gases will be investigated. The aims of this research are (1) to quantify the contribution of earthworms, microbes and their interaction on the degradation of organic carbon and nitrogen during vermicomposting; (2) to compare the difference in the emission of greenhouse gases in vermicomposting and composting system; (3) to elucidate the relationship of the emission of greenhouse gases and the abundance of GH and denitrifying genes from molecular level. The innovativeness of this research is that (1) it is the first time to quantify accurately the contribution of earthworms, microbes and their interaction on the degradation of carbon and nitrogen; and (2) it will elucidate the relationship of the emission of greenhouse gases and the abundance of GH and denitrifying genes from molecular level.

农作物秸秆还田利于培肥地力，改善土壤碳蓄积。秸秆处理后还田与直接还田相比，具有明显优势。传统堆肥处理秸秆容易产生大量温室气体。鉴于此，采用蚯蚓堆制处理秸秆，研究内容包括蚯蚓、微生物及其相互作用对秸秆堆制过程中碳氮分解代谢贡献量，微生物群落结构及其演替规律，分解碳氮关键酶活力变化，关键酶基因表达丰度变化和温室气体排放量动态变化。目标是：(1) 阐明蚯蚓、微生物及其相互作用在堆制秸秆过程中，对碳、氮分解代谢贡献量；(2) 揭示蚯蚓堆制与传统堆肥在CO2、CH4、N2O排放量差异及原因；(3) 从分子水平阐明碳氮代谢关键酶基因表达丰度与温室气体排放量关系。本项目创新之处在于：(1) 首次准确量化堆制秸秆过程中，蚯蚓、微生物及二者相互作用对底物碳、氮分解代谢贡献量；(2) 从分子水平揭示蚯蚓堆制处理秸秆过程中，温室气体排放与碳氮代谢关键酶基因表达丰度之间的关系。

农作物秸秆还田利于培肥地力，改善土壤碳固持。与秸秆直接还田相比，处理后还田具有明显优势。传统堆肥处理秸秆进程较慢，并且容易产生大量温室气体。鉴于此，本研究采用蚯蚓堆制处理秸秆。本项目以农业废弃物-秸秆和牛粪为底物材料，采用添加蚯蚓堆制处理方法，底物秸秆与牛粪设置4个混合比例，蚯蚓接种率设置为4个，探究添加蚯蚓堆制过程中底物碳氮代谢规律。主要研究内容包括：蚯蚓堆制秸秆过程中温室气体排放量分析，蚯蚓、微生物及其相互作用对秸秆堆制过程中碳氮分解代谢贡献量，微生物群落结构及其演替规律，蚯蚓堆制处理秸秆过程中底物碳氮代谢关键酶及其基因表达变化。研究结果表明，与传统堆肥相比，添加蚯蚓加速堆制进程，蚯蚓组CO2排放量高于传统堆肥组，但是其N2O排放量远低于传统堆肥组，表明添加蚯蚓堆肥在温室气体减排方面具有明显优势。底物构成与蚯蚓密度均会影响酶活力、基因丰度、微生物群落结构。在蚯蚓堆肥组，脱氢酶、降解纤维素酶及氨单加氧酶活力高于传统堆肥组，硝酸盐还原酶活力则是在传统堆肥组较高。接种蚯蚓促进糖苷水解酶家族基因表达，抑制nosZ基因表达。在蚯蚓组，堆制初期和中期，Cellulosimicrobium、Nitrosospira和ammonia_oxidising_bacteria相对丰度较高。通过开展本项研究工作，阐明了添加蚯蚓加速堆肥进程的机制，建立了量化蚯蚓对底物有机碳分解直接作用与间接作用的新方法，阐明了蚯蚓堆肥过程中碳氮代谢相关微生物的演替规律，从分子水平揭示了蚯蚓堆肥过程中温室气体排放规律。本项目较为系统地研究了蚯蚓堆制处理秸秆类农业废弃物的碳氮分解代谢规律，为秸秆生物质资源化利用提供了一定的理论与技术支持，项目研究成果可为农业废弃物的绿色高值化利用提供一定科学依据。项目的部分研究结果已经整理发表在国内外本研究领域权威学术期刊，已发表学术论6篇，SCI检索论文4篇，EI检索论文2篇。其中2篇发表在本领域顶级学术期刊Bioresource Technology。