Study On Composition Of Soil Organic Carbon And Humus In Lhasa Of Tibet

In this paper,we selected the central and southern parts of the city of Lhasa(91 ° 06 ',latitude 29 ° 36'),the study areas include the Dazi County,Linzhou County,Heilong County and Qushui County.40 samples were used to analyze the relation of soil Ph,soil organic carbon and soil humus composition under different latitude,longitude,altitude and crops.In those areas were studied,which provided the basis for further study of soil chemical properties and carbon immobilization potential in Lhasa area.The results are as follows:(1)The soil pH of the plow layer in the Lhasa area ranged from 4.75 to 8.50 and the mean value was 7.35 ± 0.89.Soil pH did not change with the longitude,latitude and altitude.The order of soil pH between different crops is: barley> wheat> rape> cucumber> potatoes.(2)The soil SOC in the Lhasa area is in the range of 3.81 ~ 32.20g/ kg,the average is 13.9 ± 5.8 g/kg,and most of the soil is mineral soil(below 20%).There was no obvious regular change in soil SOC with the increase of latitude,latitude and altitude.Soil SOC between different crops is above 10g/kg.The order of soil pH is: rape> cucumber> wheat> potato> barley.(3)WSS,FA,HA,HM and PQ in the soils of the Lhasa area were irregularly changed with the longitude,latitude and altitude.The order of soil WSS,FA,HA,HM and PQ is: cucumber> rape> barley> wheat> potato;rape> cucumber> barley> wheat> potato;cucumber> rape> wheat> potato> barley;wheat> potato> barley> cucumber > rape;potato>barley> wheat> cucumber> rape,planting the same crop variety at different locations has an effect on soil humus components.(4)The absolute correlation of soil pH,SOC,HA,FA,HM,pH and WSS was studied.The soil pH was correlated with SOC,WSS,HE,HA,FA,HM There was a significant positive correlation between soil SOC,HE,HM,FA,HA and WSS,but the correlation degree was different.