Analysis Of Soil Physicochemical Characteristicsof Land Utilization Types In The South Slope Of Qilian Mountains

Soil’s physicochemical property was the essential attribute,which reflected the conditions of soil fertility,soil texture,construction,breathability and water retention.The findings showed that land utilization types were the general,direct and profound factors that effected the variation of physical and chemical properties of soil.In this thesis,such methods as field sampling,laboratory test and data analysis were adopted to analyze the physical and chemical properties of soil and water storage property in seven different land utilization types in the south slope of Qilian Mountains,which provided the scientific proofs to enhance ecological environmental protection and water conservation in the south slope of Qilian Mountains.The main findings were as follows:(1)The soil texture of seven kinds of land utilization types was mainly silt.The soil texture of wetland was the finest,and then was mountain steppe.The soil coarsening of degraded grassland was serious.The proportion size of clay sands ranked as wetland>mountain steppe>alpine grassland>desert steppe>alpine meadow>swamp meadow>degraded grassland.(2)The soil moisture content generally decreased with the depth of soil layer.The higher soil moisture contents were swamp meadow,wetland and alpine grassland.The soil moisture contents of degraded grassland and desert steppe were minimum.(3)Except degraded grassland and desert steppe,soil bulk density of the other land-use types totally enlarge with the depth of soil layer.The sizes of integral soil bulk density ranked as degraded grassland>alpine meadow>desert steppe>alpine grassland>mountain steppe>swamp meadow>wetland.(4)The size of soil porosity was related to soil bulk density.When soil bulk density became too small,soil texture also became loosen and the porosity became large.Otherwise,soil porosity would become small.The size of soil porosity ranked as wetland>mountain steppe>swamp meadow>alpine grassland>desert steppe>alpine meadow>degraded grassland.(5)The soil pH value of seven land-use types distributed from 7.67 to 8.46,and it absolutely belonged to alkalinity.Among these,the pH values of desert steppe and degraded grassland were the highest,which indicated that the soil development was incomplete and had the salinization tendency.(6)The soil organic contents of such 7 land-use types totally acted as that the upper layer was larger than the sub-layer with the limitation of 30 cm.The sizes of organic contents ranked as wetland>alpine grassland>swamp meadow>mountain steppe>alpine meadow>desert steppe>degraded grassland.(7)The size composition of seven land-use types on the whole presented the extremely outstanding correlativity(p<0.01)or normally outstanding correlativity(p<0.05).The correlativity of pH contents and size composition was not outstanding,while the correlativity of soil physicochemical properties of land-use types of each index of soil physicochemical properties was outstanding.(8)The largest soil impoundage decreased with the depth of layers on the whole,and the sizes of the largest soil impoundage within the scope of 0-50 cm ranked as wetland>mountain steppe>swamp meadow>alpine grassland>desert steppe>alpine meadow>degraded grassland.As for the whole layers or each layer,the impounding property of swamp meadow,wetland and mountain steppe was of first-rate,while superior of desert steppe and degraded grassland was poor.As a whole,soil’s physicochemical properties of wetland,mountain steppe and swamp meadow of different land-use types in the study area were fair and the water-holding capacity was superior,while that of degraded grassland and desert steppe was poor.