寒地玉米秸秆还田对土壤有机碳组分的影响及其生物学机制

straw amendment has an important role in maintaining soil fertility and improving the ecological environment of farmland, which has become an important content of ecological agriculture and sustainable agriculture. Straw amendment not only changes the quantity of soil organic carbon, but also has an important influence on the distribution of various components of soil organic carbon. Using maize field in northeast cold region of china as the research object and from the physical, chemical and biological soil organic carbon group, the organic carbon composition and the change of soil microbial diversity of black soil were studied under the condition of maize straw and biochar amendment by setting the field location experiment of straw mulching, straw and straw carbonization turning over combined with the indoor cultivation test. The differences of soil organic carbon composition and microbial community structure were analyzed to clear the mutual relationship between soil microbial diversity and soil organic carbon components and to clarity the specific migration between soil organic carbon composition and its response and feedback of straw returned in order to provide theoretical and technical guidance to optimization of maize straw returned of cold field.

秸秆还田与土壤肥力、环境保护、农田生态环境平衡等密切联系，已成为生态农业和持续农业的重要内容；秸秆还田不仅会改变土壤有机碳数量，同时对土壤有机碳各种组分的分配状况产生重要影响。本研究重点解决寒地不同玉米秸秆还田后对土壤有机碳的影响，从土壤有机碳物理、化学及生物学分组入手，以我国东北寒地玉米为研究对象，在连续玉米秸秆还田、施用生物炭的基础上，通过定位试验及室内培养试验相结合的方式，研究玉米秸秆及生物炭还田条件下黑土农田有机碳组分、土壤微生物多样性的变化。通过分析土壤有机碳组分和微生物群落结构的差异，解析有机碳组分与土壤微生物多样性的相互作用关系，明确土壤有机碳组分之间具体的迁移转化及其对秸秆还田的响应和反馈，对寒地黑土农田合理秸秆还田方式的确定具有重要的指导意义。

秸秆还田不仅会改变土壤有机碳数量，同时对土壤有机碳各种组分的分配状况和微生物群落产生重要影响，本试验以低肥力黑土农田为研究对象，通过小区定位试验，研究了玉米秸秆及生物炭还田对低肥力农田土壤养分、温室气体、有机碳组分和微生物群落的影响，共设置了5个试验处理，分别为秸秆地表覆盖还田（NTS）、秸秆混拌还田（CTS）、生物炭低量还田（BC1）、生物炭高量还田（BC2）、不还田（CT）。试验结果表明生物炭和秸秆还田均显著提高了土壤有机质含量，生物炭还田提高了土壤全氮及全钾含量。CTS显著提高了MBC含量、BC2提高了LOC、LFOC和POC含量。生物炭和秸秆还田均显著提高了土壤CO2排放总量。秸秆还田明显改变了微生物丰度和多样性，Proteobacteria、Unidentified_Bacteria、Acidobacteria、hloroflexi的相对丰度在所有处理中占优势，其中Proteobacteria在所有处理中相对丰度最高，DOC、TOC、土壤全氮、土壤速效氮对微生物群落影响较大。本项目的研究结果为了解东北黑土区不同类型外源碳投入对低肥力农田土壤有机碳组分和微生物群落组成提供了线索，为解析中国东北玉米连作区秸秆还田后土壤有机碳的供应提供参考。