Study On Relationships Between Soil Microorganism And Fertilities Under Different Grazing Intensities In Meadow Steppe Of Inner Mongolia

This thesis pursues a course of study on soil that in pasturing areas with different grazing intensities in Xiligol of Inner Mongolia. After testing soil microorganisms, soil microbial biomass (carbon, nitrogen), the soil enzymatic activities, respiration intensity and soil physical-chemical factors, it analysis their seasonal dynamic diversification, pertinence and various grazing intensities'impact on them. The thesis wants to provide microorganic proof for soil fertility quality evaluation. The results showed that.1.The relationship among the numbers of the soil microorganisms is bacteria> nitrogen fixing bacteria> actinomycetes > fungi. The total number of microorganism in control area is 4.7 times more than heavy grazing, and the number of the soil microorganisms in heavy grazing is less than control area. The peak value of soil bacteria, fungi and nitrogen fixing bacteria appears in August. actinomycetes are higher in May and August.2. The soil microbial biomass and soil respiration intensity are gradually reducing along with aggrandizement of pasturing intensity. The soil microbial biomass and soil respiration intensity in heave grazing are all under the figure in control area. The soil microbial biomass Carbon and nitrogen are higher in August and October, while the peak value of soil respiration intensity is in August.3. Soil urease, incerfase, saccharose enzyme and protease activity are the lowest in heavy grazing, while polyphenol oxidation enzyme is the lowest in control area. Urease, incerfase and saccharose enzyme are higher in August. Polyphenol oxidation enzyme is higher in May. Protease activity is higher in March and August. 4. Along with accretion of grazing intensity, soil moisture, soil organic maffer content, total-N, total-P, alkaline-N depresses, but soil pH rises and available-P changes unconspicuous.5. Correlation analysis indicates that the numbers of the soil microorganisms, soil microbial biomass, respiration intensity, urease, incertase, saccharose enzyme, protease activity and soil main nutrient appear remarkable pertinency. It means that it is feasible to evaluate soil fertility by colligating soil microorganisms and bioactivity, such as soil enzyme and soil respiration intensity.6. Grazing intensity has obvious impact on soil fertility. The soil fertility in control area and light grazing is higher than heavy grazing. Soil fertility is common in moderate grazing, but depressed in heavy grazing distinctly. Continuously grazing must destroy the grassland ecosystem. Enclosure and light grazing are effective approaches for grassland continuable utilization.