Characteristics of soil salinity in Hi River Valley, Western Tianshan Mountains.

The characteristics of soil salinity in the Ili River Valley,Western Tianshan Mountains,China,were studied based on correlation analysis and principal component analysis methods.Results of the study indicated that:53.68% of soil samples from the root zone soil layer(3-(20 cm)) were non-salinized,while 18.38% were slightly salinized,13.97% were moderately salinized,8.82% were strongly salinized and 5.51% were saline soils.The types of soil salinization were mainly sulphate saline soils,occupying 68.41%.Anions were mainly SO_4~(2-) and Cl~ while cations were mainly Na~+ and Ca~(2+).Soil salinity showed significantly positive correlation with the concentration of Cl~-and SO_4~(2-),indicating that the degree of soil salinity depends on the concentration of Cl~-and SO_4~(2-) of soil to a certain extent.The salinity of the surface soil layer(0-(3 cm)) occupied 60.19% of the salinity of the 0-60 cm soil layer,indicating that the soil salinity was distributed mainly at the top soil layer.Results of principal component analysis indicated that the salinity,Cl~-,SO_4~(2-),Mg~(2+) and Ca~(2+) concentrations could be the characteristic factors for expressing soil salinization in the study area.The abundance of salinity of the root zone soil layer for different land use types was in the following order:grasslandglebe fieldpaddy fieldforest land.Under different irrigation conditions,the salinity of the root zone soil layer of farmlands irrigated with groundwater and surface water was(1.12 gkg) and(0.73 gkg) respectively.However,the salinity of the root zone soil layer of farmlands irrigated with surface water was(0.39 gkg) lower than farmlands irrigated with groundwater.The abundance of salinity of the root zone soil layer for different periods was in the following order:non-irrigated periodsummer irrigation periodautumn irrigation period.