Abstract:Through soil column simulation test, the effect of phosphogypsum and its combined application with acidic materials on soil water and salt transport in alkalize solonchaks of Ningxia was studied under leaching with different quality water. In this study, the Yellow River water, low-salinity farmland backwater, and high-salinity farmland backwater were used as leaching water sources, and humic acid, furfural residue and aluminum sulfate were used as acidic materials. The results showed that: (1) Under the leaching with different quality water, there was a linear relationship between the depth of vertical wetting front or cumulative infiltration and the square root of infiltration time. Under the leaching of the Yellow River water, the "phosphogypsum+furfural residue+aluminum sulfate" treatment was the best, while under the leaching of high-salinity farmland backwater, the single application of phosphogypsum was the best.(2) The application of amendments reduced the electrical conductivity of 0—50 cm soil layer under the leaching of the Yellow River water and low-salinity farmland backwater. Under the leaching of the Yellow River water, the "phosphogypsum+aluminum sulfate" treatment had the lowest soil electrical conductivity. Under the leaching of high-salinity farmland backwater, the "phosphogypsum+furfural residue+aluminum sulfate" treatment had the lowest soil electrical conductivity. (3) With the increase of leaching water salinity, the pH value of soil increased. The application of amendments reduced the pH value of 0—30 cm soil layer. Under the leaching of the Yellow River water, the "phosphogypsum+aluminum sulfate" treatment was the best. Under the leaching of low-salinity farmland backwater, the "phosphogypsum+ furfural residue+aluminum sulfate" treatment was the best. Under the leaching of high-salinity farmland backwater, the "phosphogypsum+ furfural residue" treatment was the best. (4) Under the leaching of the Yellow River water, the application of amendments increased the soil water content at different depths. Under the leaching of different quality water, the application of amendments increased the water content of 0—70 cm soil layer, and there was not large difference among the treatments. For the improvement of alkalize solonchaks, it was suggested that under the leaching of the Yellow River water and high-salinity farmland backwater, a combination of "phosphorgypsum+aluminum sulfate" should be used to improve the soil, while under the leaching of low-salinity farmland backwater, the combined measures of "phosphogypsum + furfural residue + aluminum sulfate" should be used.