Study On The Soil Organic Carbon Fraction With Yariable After Different Grazing Strength And Terrain

In this paper, taking the Stipa breviflora desert steppe as the research object, under the common interference of environmental factors such as different terrain (bottom of slope, middle of slope, top of slope) and different grazing region (lightly grazed, moderately grazed, heavily grazed and no grazing region), has carried out on the exploration research about the components of soil organic carbon and physical properties change.The results are as follows:The effect to soil properties of terrain1. As the slope rises, soil humic acid and fulvic acid all have downtrend, soil HA/FA value have the trend of reducing. With the gradient increasing, the correlation between each composition of humic acid and organic matter is increasing.The order of size of crude organic carbon content is, the bottom of the slope> the top of the slope> the middle of the slope, and the order of size of organic carbon content in the young is the top of the slope> the middle of the slope> the bottom of the slope, and in soil0-10cm and0-20cm, the size order of stability of organic carbon is the bottom of the slope> the top of the slope> the middle of the slope. While solid in20-30cm is the bottom of the slope> the middle of the slope> the top of the slope. Organic content of grade size1mm significantly higher than other grade size organic content (p<0.001). There is no difference grade size between0.5mm and0.25mm of the organic content (p>0.5), and content is the least.2. With the rising slope, the soil microbial biomass carbon reduced, showing the content in the top of hill is lower than its base and the hillslope, with the soil depth increasing, the microbial biomass carbon was significantly reduced. Terrain impact on soil organic carbon mineralization, with the terrain rises, which gradually reduce the amount of organic carbon mineralization. Between organic carbon and carbon mineralization has significant positive linear correlation.The effect to soil properties of grazing intensity1. As grazing intensity was enhanced, the content of soil humic acid and fulvic acid declined obviously. The grazing intensity affected value of soil HA/FA, and the heavy grazing intensity affected them evidently. As grazing intensity was enhanced, the correlation of all component of the humus acid with soil organic matter declined. In0-30cm depth of soil. the coarse soil organic carbon of control and light grazing intensity plots were more than middle and heavy grazing intensity plots. In20-30cm depth of soil, the content of young soil organic carbon of control plot has obvious difference from other grazing intensity plots. In0-30cm depth of soil, the sequence of content of stable soil organic carbon was CK>LG>MG>HG. By the research of soil organic carbon of soil aggregate with all size fraction, we found that, in0-30cm depth of all grazing plots, the content of soil organic carbon with lmm size fraction was obviously higher than that with any other size fraction. The content of soil organic matter of0.5mm and0.25mm size fraction had no obvious difference (P>0.05), and their content were small.2. As grazing intensity was enhanced, the soil microbial biomass carbon reduced. Heavy grazing causes soil microbial biomass carbon and organic matter significantly reduced, but the control and light grazing, middle grazing didn’t change them significantly. There was obvious positive correlation between organic carbon and mineralized carbon. The mineralization of organic carbon was reduced along with the grazing intensity strengthening.