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

The paper studies on the typical steppe inside Dalinuoer National Nature Reserve, west of Keshenketeng County in ChiFeng Inner Mongolian. The typical grassland shall be divided into four parts with different grazing intensities; this study analyses the seasonal change , inter-relationship and over-grazing impacts on the specimen quantity of main soil microorganism, soil microbial biomass of microorganism, activity of soil enzyme and soil physical-chemical factors etc in grassland ecosystem. Its aim is to provide the scientific basis in microorganism respect for the grassland soil fertility scientific assessment.1. The quantity of various microorganism varies to some extent in the Inner Mongolia steppe, their quantity relationship ranks as bacteriaï¹¥ammonifierï¹¥nitrogen fixating bacteriaï¹¥actinomycesï¹¥Denitrifying bacteriaï¹¥fungiï¹¥nitrobacteria; The total quantity of soil microorganism in control area, light grazing, and heavy grazing is more than that of heavy grazing area; the total quantity of soil microorganism ranks as August(Summer)>October(Autumn)>May(Spring)>March(Winter).2. The soil microbial biomass has the distinct reaction under the impact of grazing intensity and seasonal change. The soil microbial biomass in light grazing area has higher percentage of soil microbial biomass carbon and soil microbial biomass nitrogen than that in other areas. The percentage of soil microbial biomass carbon and soil microbial biomass nitrogen is relatively high in August (summer) and October (winter).3. The soil enzymatic activities are diverse under the comprehensive impacts of grazing intensity and seasonal change. The control area and light grazing area is with low activity of oil polyphenol oxidase and high activity of soil urease, catalase, and protease. However, heavy grazing area is with increased polyphenol oxidase activity and drastically reduced soil urease, catalase, and protease. 4. Under different grazing intensity, soil respiration intensity represents the trend of decreasing as the increase of grazing intensity; in addition, the change is obvious.5. With the increase of grazing intensity, the water percentage in soil will decrease with corresponding increasing of PH and decreasing of soil organic matter content and alkaline-N.6. The relative analysis shows that under different grazing intensity, the total quantity of soil microorganism, the quantity of various microorganisms has obvious and much obvious relationship with soil microbial biomass carbon and soil microbial biomass nitrogen respectively. Moreover, soil microorganism and soil enzyme in soil ecosystem is inter-independent and interact ional.