生物水保措施下红壤坡耕地团聚体的微生物稳定机制

Soil aggregate is the basic unit of soil structure, and its composition and stabilization has significant effect on runoff and soil loss of red soil slope farmland. Soil orgnic carbon (SOC) and microorganism play critical role in the formation and stabilization of soil aggregate. However, it is lacked the comprehensive study of the microbial mechanism of soil aggregate stabilization under biological soil and water conservation measures in red soil slope farmland. It is urgent to study the microbial mechanisms of soil aggregate stabilization involved in the complex relationship between SOM and microorganism.Here, based on a field soil and water conservation measures experiment (Since 2009), we will analyze the distribution of aggregate size and microbial community structure and function, physical fraction properties of SOC, and then we systematic review the character of SOC and microbial and its relationships within particle size fractions of soil under biological soil and water conservation measures. On this basis, we mainly studies the mechanism of microbial regulating stabilization of Soil aggregate by displacementing experiment of microbial community. The expected result will elucidate the effect of microorganism on the relative stability of Soil aggregate under biological measures of Soil and water conservation. Besides contributing to understand the micarobial mechanism of soil aggregate stabilization under biological soil and water conservation measures in red soil slope farmland, it will also guide the establishment of reasonable soil and water conservation measures and reconstructive of good fertilization eroded soil in red slop farmland soil in southern of China.

土壤团聚体作为土壤结构的基本单位，其稳定性对红壤坡耕地的径流和侵蚀强度有重要影响，而土壤有机碳和微生物对土壤团聚结构的形成和稳定性具有决定性作用，但是在生物水保措施下，以有机碳为基础的土壤团聚体微生物稳定机制研究相对薄弱。本研究拟依托始于2009年的红壤坡耕地生物水保措施水保效果野外试验，通过系统分析土壤团聚体组成以及不同粒级团聚体上有机碳组成、微生物群落结构和功能多样性，阐明土壤微生物、有机碳及其相互作用与土壤团聚体组成的关系，并在室内调控体系下，重点研究微生物群落对土壤团聚体稳定性的贡献。预期研究结果可阐明生物水保措施下微生物群落结构和活性对土壤团聚体稳定的作用机制，对制定合理的南方红壤坡耕地水土流失生物治理措施以及创建和培育结构良好的土壤肥力具有重要的理论和实践意义。

土壤水稳性团聚体的稳定对红壤坡耕地的径流和侵蚀强度有重要影响，而土壤有机碳和微生物对土壤团聚结构的形成和稳定性具有决定性作用。基于红壤坡耕地生物水保措施水保效果野外试验，研究常规等高种植(CK)、植物篱(H)、稻草覆盖(M)和植物篱+稻草覆盖(HM)下团聚体组成及不同粒级团聚体上有机碳组成、微生物群落变化和参与碳、氮循环的土壤酶活性，阐明土壤微生物、有机碳及其相互作用与土壤团聚体组成的关系，揭示生物水保措施下土壤团聚体微生物稳定机制。研究表明：.(1) 与CK相比，不同水保措施均增加了土壤微生物量碳含量，平均提高总有机碳含量0.20~2.44g/kg。稻草覆盖是增加土壤可溶性有机碳的主要因素； .(2) H、M和HM处理分别较CK增加了>2mm团聚体的含量10.6%、9.1%和50.1%；稻草覆盖和香根草篱均降低 < 0.25mm团聚体碳含量且二者配施后具有叠加效应。M和H主要增加了 > 2mm、1-2 mm和1-0.25 mm团聚体内有机碳含量，降低了< 0.25mm团聚体内有机碳含量，稻草覆盖是影响团聚体碳含量的主要因素；.(3) 不同水保措施对土壤酶活性的影响因酶类型的不同而存在差异。稻草覆盖是影响土壤中酶活性的主要因素。H处理对>2mm和<0.25mm团聚体内参与碳循环酶(NCE)的促进程度显著高于M处理，M处理对 >2mm和1-0.25mm团聚体内NNE酶的促进程度高于H处理；.(4) 与CK相比，H、M和HM处理均改变了土壤和团聚体内细菌和真菌的结构组成；冗余分析结果表明，M和HM处理团聚体组成相近，主要与>2mm、1-2mm团聚体以及平均重量直经(MWD)显著正相关。土壤团聚体组成结构与土壤MBC、TOC、土壤总酶活性、NCE和XYL、AG、CB、 NAG的酶活性，真菌F_Basidiomycota F_Zygomycota、细菌B_Acidobacteria呈显著正相关； .(5) 不同水保措施下，不同粒径团聚体内的微生物与土壤环境因子的响应关系不同。TOC和土壤酶活性相互作用影响细菌B_Verrucomicrobia和真菌F_Zygomycota等微生物在H、M和HM处理>0.25mm团聚体内的分布比例，而TOC是影响CK处理<0.25mm团聚体内土壤微生物群落结构组成的主要因素。本研究初步研究结果对制定合理的南方红壤坡耕地水土流失生物治理措施及培