Study On The Black Soil Nitrogen Fixation Via Microbial Regulation In Northeast Region

China's northeastern region has been one of the most important grain production bases. However, for a long time, excess utilizing and unreasonable application of nitrogen caused the serious soil degradation. Moreover; the soil quality has changed evidently. Nitrogen loss has become one of the important limiting factors to efficient and sustainable development of high-yielding agriculture in northeast region. Therefore, how to refresh soi quality of black soil is one of the hot points, which has important significance to both the theory and the reality. By simulative experiments in lab, black soil was target using methods of traditional biochemistry, molecular biology (PCR-DGGE) and microbial biomarker (PLFA, soil amino sugar) to lay out research about microbial transformation and fixation on nitrogen of black soil. Initial conclusion by an analysis as followed:1. Urea+Straw treatments led to increasement of microbiomass nitrogen obviously and maintained a long time compared with Urea and Urea+Grucose; Though Urea+Grucose treatments could also enrich microbiomass nitrogen, the effect lasted briefly. For Urea, increasement of microbiomass nitrogen showed unconspicuously.2. Urea+Straw treatments could improve activity of Polyphenol oxidase, Urease,β-Glucosaminidase, but to Sucrase, the impact was slowly. Urea+Grucose treatments activated four enzymes notably. Urea treatments restrained four enzymes above.3. Analysis of composition of PLFA showed that Urea+Straw treatments developed microbial population diversity in short time and kept for a long time, at the same time, gram negative bacteria increased remarkably; Urea+Grucose treatments only caused a little impacts to microbial population diversity and ehriched some special microbes; The influences of Urea treatments was the least to Microbial population diversity.4. Urea, Urea+Grucose, Urea+Straw treatments all accumulated the soil amino sugars. To Urea+Straw treatments, the increasement of amino sugars exceeded 40% compared with control, which beyond other treatments. The conclusions were that Straw could cause increasement of soil amino sugars residues obviously. Moreover, the contribution of fungi was more in evidence than bacteria to soil amino sugars.