Study on the Spatial Variability of Soil Salt Content Fore-and-aft Freezing in the Farmland of Qitai County

In order to clarify the effect of freezing process on soil salinity distribution,the paper analyzed comparatively the spatial variability of salinity before and after freezing on the farmland in Qitai by taking samples in the open field and researching in the lab.The results show that before the freezing,soil salt content(0.11%) of surface layer(0-20 cm) is minimum,soil salt content tends to increase with soil depth while the complexity distribution of soil salt content tends to decrease.After the freezing,soil salt content(0.14%) of surface layer is maximum,which indicates that soil salt accumulation rate(30.0%) at the surface layer is significant in spring while soil salt desalination rate is obviously in fall with decreasing 8.16% of salt content in profile(over 100 cm depth),soil salt desalination depth is beyond 100 cm.In addition,variability of salt content of every soil layers remains unchanged,but the variation coefficient increases(except for 40-60 cm).Theoretic model of soil salt content on the upper profile varied from Index model to Gauss model with obvious increase,but the bottom section is from Gauss model to Bartlett model with little change.