Influences of Grazing Intensity on Contents of Total nitrogen,Phosphorus and Po Tassium in Alpine-cold Mixed-sown Artificial Grassland

The results of grazing trial of gaks for three grazing seasons in mixed-sown grassland for Elymus natans/Puccinellia tenuflora showed:①With the increasing of grazing intensity,contents of total nitrogen and potassium in every soil depth appeared changing trend of the "low-high-low",and contents of total phosphorus in 0～10cm depths were contrary with the changing trend of total nitrogen and potassium,and then the changing trend of total phosphorus in 10～20cm and 20～30cm depths was similar with the changing trend of total nitrogen and potassium;②Influence of grazing intensity on contents of phosphorus,nitrogen and potassium in every soil depths were not significant(P0.05),significant(P0.05)and extremely significant(P0.01),respectively.