Effects of grazing on soil organic carbon and total nitrogen in typical steppe

The contents of soil organic carbon(SOC) and total nitrogen(TN) under different grazing intensity(light grazing,LG;moderate grazing,MG;heavy grazing,HG;zero grazing and fence,CK) and system in the Leymus chinensis typical steppe near the Xilin River in Inner Mongolia were studied.The result showed that 1)the SOC content of the continuous grazing land was significantly higher than the mixed grazing pasture and the order in continuous grazing pasture was LGHGMGCK.In the mixed utilization pasture,except LG+hay and MG+hay within 20 to 30 cm,the differences between different grazing intensity were not significant.The content decreased with the increase of soil depth.2) In continuous grazing pasture,the variation pattern of soil TN was similar to SOC,i.e.,LGHGMGCK.In the mixed grazing pasture,the pattern was more complex,and the TN content was lower than that in continuous grazing pasture.The TN content decreased with the increase of soil depth.The result indicated that the SOC level in HG was higher than MG which might be caused by more C4 plants with the increasing of grazing intensity.