保护性耕作对黑土耕层土壤微生物分布影响研究

The black soil region in Northeast China is facing soil fertility degradation and soil erosion problems, soil microorganisms can promote nutrient cycling between soil and crop, and also is a main indicator of soil fertility, while, soil microorganisms can be affected easily by the alter of environment. It is known that conservation tillage can increase crop yield, improve soil fertility, and in favor of soil and water conservation, but there are few studies about the effects of conservation tillage on soil microbial distribution and function, and also very few study is about the effects of conservation tillage on soil microbial distribution in a vertical profile. In this study, crop rotation and straw mulching these two conservation tillage are taking as the research subject, pyrosequencing、q-PCR and other methods are adopted to determine the variation of microbial biomass、respiration、composition and abundance in the soil tillage layers(0-40cm), and the microbe responding mechanisms to the different tillage system is analyzed, the effects of conservation tillage on the microbial distribution in the vertical profile of black soil is measured, further the effects of conservation tillage and the tradition tillage on soil microbial distribution is compared. This study will be a solid theoretical foundation of the study of microorganism responding mechanism to the different tillage systems in black soil area, and it is of great significance for improving the black soil tillage methods and the protection of black soil resources.

东北黑土区面临土壤肥力减退、水土流失等问题，土壤中微生物能够促进土壤-作物营养物质循环，是反映土壤肥力的主要指标，并受环境变化影响明显。目前保护性耕作对于增加农作物产量，改善土壤肥力，蓄水保土的功能都有一定的研究，但是关于保护性耕作对于土壤中微生物的分布以及其功能性质影响的研究却较少，关于保护性耕作对于土壤垂直剖面上微生物分布影响的研究相对更少，本研究以东北黑土区轮作及秸秆覆盖两种保护性耕作为研究对象，采用高通量测序、qPCR等技术测定土壤耕层（0-40cm）微生物量、呼吸、种群结构、丰富度等变化情况，解析黑土土壤微生物对于不同耕作方式的响应机制，以及保护性耕作对于土壤耕层垂直剖面微生物分布的影响，并进一步明确保护性耕作与传统性耕作相比土壤耕层微生物分布的变化情况。该项目将为黑土区微生物对于耕作方式应变机制研究奠定坚实的理论基础，对于改善黑土耕作方式、保护黑土资源具有重要意义。

通过对东北黑土区轮作和秸秆覆盖两种保护性耕作方式下土壤微生物特性研究，结果表明，轮作及秸秆覆盖这两种保护性耕作方式显著提高了黑土土壤细菌的丰富度及群落多样性，改善了土壤质量，特别是秸秆覆盖处理显著提高了土壤细菌丰富度及多样性，然而与秸秆覆盖相比，细菌群落结构变化对于轮作处理方式更敏感。秸秆覆盖量的多少对于土壤细菌群落变化的影响也不同，并不呈正相关关系，少量秸秆覆盖可以显著提高细菌多样性。不同农作物轮作顺序对于土壤细菌群落多样性的影响不同，研究表明大豆-大豆-玉米-玉米轮作方式显著提高了土壤细菌丰富度和群落多样性，对于东北地区黑土地如何进行轮作方式选择可以在提高作物产量的同时不损害土壤，保育或提高土壤质量还需要进一步的研究与讨论。