Basic Soil Properties under Different Grassland Use Types in Haibei State of Qinghai Province

Five grassland use patterns: enclosed native Kobresia humilis meadow,native shrub meadow,degraded Kobresia humilis meadow,degraded shrub meadow,artificial grassland and farmland,were selected to study the effects of land use patterns on soil basic properties in the Northern of Tibetan Plateau,Qinghai province.Results showed that grassland degradation mainly led the soil bulk density of 0~10 cm layer to increase significantly,and had no significant influence on lower depth soil bulk capacity.Soil bulk density of 0~10 cm layer was higher than that of 10~20 cm layer in two degraded land use patterns.There was significant difference between degraded shrub meadow and native shrub meadow.Both planting and reclamation did not lead to the variation of soil bulk density in 0~20 cm soil depth.Grassland degradation and reclamation led soil organic carbon and total nitrogen content to decrease.Grassland degradation also decreased soil total phosphorus content,but reclamation had little influence on soil total phosphorus content.Grassland degradation and reclamation led the variation of soil organic carbon,total nitrogen and total phosphorus content to disappear with soil depth increasing.Degradation was making grassland into farmland.Grassland degradation led the soil organic carbon,total nitrogen and total phosphorus of surface soil to lose severely,but had little effect on that of 10~20 cm soil.Grassland degradation,reclamation-and farm,especially grassland reclamation and agricultural utilization led to decline the soil available nitrogen of surface soil.The effects of land use patterns on soil available phosphorus was more complicated,and with no consistent regularity