Response Of Soil Nutritents Characteristics Of Alpine Meadow To Grazing Density In The Northeastern Edge Of Qinghai-tibetan Plateau

As an important pastoral, the northeastern edge region of the Qinghai-Tibet Plateau connects the Loess Plateau, Ordos and Alashan. However, most of the grassland is subject to unsustainable grazing pressure which has resulted in a degraded condition. At the simplest level, degradation of the grassland ecosystems is caused by unbalanced nutrient inputs and outputs. Therefore, repairing the degraded grassland necessitates maintaining nutrient balance, which requires identifying the impact of grazing intensity on grassland and features of the main elements of the process. In this study, short-term grazing and long-term monitoring were used. Soil organic carbon, total nitrogen, total phosphorus available nitrogen, available phosphorus and microbial biomass carbon and nitrogen responses to grazing intensity alpine meadow were analyzed. Measurement of soil stoichiometry under different stocking rates was made clear. Soil organic carbon, total nitrogen, microbial biomass carbon and nitrogen under grazing and fenced utilization were compared. The following results were obtained.1Soil organic carbon and total nitrogen were different in response to grazing intensity, while different grazing intensity had no significant effect on total phosphorus. Light grazing respectively increased the content of soil organic carbon and total nitrogen in0-20cm layer from1.02%to6.81%and1.65%-1.70. Heavy grazing had no significant effect on total nitrogen but reduced the content of soil organic carbon.2Available soil nutrient response to grazing intensity manifested some differences. Moderate grazing caused the content of nitrate nitrogen to increase by17.94%. Heavy grazing not only reduced the content of ammonium nitrogen in0-10cm by23.92%, but also reduced the content of available phosphorus in0-10,10-20,20-30cm by the rate25.74%,19.04%and29.45%.3The impact of grazing on soil microbial biomass carbon and nitrogen content differed. Light grazing caused the content of microbial biomass nitrogen in the0-10,10-20and20-30cm soil layers to increase by135.72%,25.23%and46.91respectively. Moderate grazing caused the content of nitrate carbon to increase by12.21%,25.40%and26.44%respectively in the0-10,10-20and20-30cm soil layers.4Grazing intensity had no significant effect on soil C/N and N/P, but C/P ratio was affected. Light grazing significant increased C/P at0-10cm by8.89%, and moderate grazing increased C/P in20-30cm by6.09%.5Long-term fencing did not significantly increase the content of soil organic carbon and total nitrogen, but reduced the content of organic carbon and total nitrogen in the deep layer. At the same time, fencing resulted in a significant increase in the content of microbial biomass carbon and nitrogen in0-10cm by68.53%and68.41%respectively.In conclusion, it was found that moderate grazing intensity or less (1.0cattle units/hm2) was conducive to the northeast edge of the Tibetan Plateau alpine meadow soils accumulate positive elements and could made the input and output in the soil consistent. Long-term fencing was not conducive to the accumulation of soil carbon and nitrogen.