Effect Of Grazing Intensity On Soil Net Nitrogen Mineralization In Typical Steppe Of Inner Mongolia

To study the effect of grazing on nitrogen mineralization in the typical steppe of Inner Mongolia, soils were sampled random from traditional system of flat, mixed system of flat site, traditional system of slop and mixed system of slope respectively with different grazing intensities, including control sample, light grazing 1.5 sheep/hm~2 and 3.0sheep/hm~2, moderate grazing 4.5 sheep/hm~2 and 6.0 sheep /hm~2, heavy grazing 7.5 sheep/hm~2 and 9.0sheep/hm~2. Dynamics of soil net nitrogen mineralization and physical and chemical character were analyzed respectively with different grazing intensities, of soils were measured, and the diversity of the accumulated net nitrogen mineralization were compared respectively with different topography and grazing intensities, and nitrogen mineralization potential(N0) and nitrogen mineralization rate constant (k) were calculated with application of model based on sampled random and cultured in door during 2009 to 2010. The main results were as follows:In different systems, the soil organic and the soil total nitrogen were higher in light grazing. The soil pH, soil bulk density and soil total phosphorus had no change.The soil accumulated net nitrogen mineralization were higher in light grazing and moderate grazing than heavy grazing and were higher in the slope sites than the flat sites, and were higher in the tradition system than the mixed system.N0 were higher in light grazing and moderate grazing than heavy grazing and were higher in the slope than the flat sites, and were higher in the traditional system than the mixed system.k in the flat sites were higher in heavy grazing, in the slope sites were higher in moderate and light grazing.