Abstract: Soil salinization is one of the important factors impacting the stability of oasis and sustainable agriculture.The dynamic monitoring and analysis of soil salinity are the prerequisite to manage and utilize the salinized land scientifically.This study aims to investigate the spatial variation and driving mechanism of soil salinization under the action ofclimate change and human activities in the Weigan River Oasis,Xinjiang,China.In October 2012,based on the soil type map and the land use type mapof the Weigan River Oasis,we collected 35 soil profiles covering four land use types (i.e.cultivated land,forest,grassland,and saline-alkali land) using GPS positioning technology.Based on the GIS technology and Geostatistics methods,this study analyzed the distribution of soil salinization and the soil salinity variation under different land use types.The results indicated that the soil salt ion content in general is decreased as the soil gets deeper with CO^2-₃ and HCO₃^- being exceptional and the values of soil salt ions were listed in a descending order as follows:Na⁺+K⁺>Ca²⁺>Mg²⁺,SO^2-₄>Cl^->HCO₃^->CO^2-₃ for all the soil profiles.Generally,the variation coefficient of soil salt ion content was sitting in the range between 25% and 200%,indicating that the soil salinity in the region had a moderate to strong variability.The vertical distributions of soil salinity presented a significant difference for different land use types.For the cultivated land type,its soil salinity was a constant at different depth of the soil.For the grassland and saline-alkali land (wasteland),their soil salinity was accumulated in topsoil while for the forest,the soil salinity was accumulated at the bottom.In addition,the salinities in the surface soil (0-40 cm) for the four typical land use types were listed in an descending order as follows:wasteland (38.42 g·kg^-1)>grassland (16.30 g·kg^-1)>cultivated land (5.37 g·kg^-1)>forest 4.62 (g·kg^-1).Overall,the soil in the Weigan River Oasis is heavily salinized,which was caused by the combination of nature and human factors.On the one hand,the natural factors including the ratio of evaporation to rainfall and groundwater fluctuationare the forming conditions of soil salinization.On the other hand,human disturbances,such as land use,irrigation,and fertilization,aggravate the soil salinization.In order to improve the deteriorating ecological environment and soil salinization to ensure asustainable oasis agriculture,we should strictly control the scale of reclamation,improve the construction of water conservancy,and strengthen water-saving irrigation agriculture in the process of land exploitation and utilization in the Weigan River Oasis.Furthermore,rational exploitation of the groundwater resources in alleviating the shortage of surface water resources is also needed to solve the problem of uncoordinated irrigation and drainage to avoid secondary salinization.

Key words: soil salinity, spatial variability, salinization, Weigan River Oasis