Simulation and evaluation of soil salt movement under different irrigation and drainage conditions

One-dimensional water-salt movement under different conditions of irrigation and drainage was simulated by using HYDRUS-1D model.The effects on the reclamation of saline-alkali soil of conventional irrigation,water-saving irrigation,pipe drainage,and drainless condition were compared and evaluated.The results reveal that the annual salinity variations in plough layer under water-saving irrigation are similar to those under conventional irrigation,and cutting down 14.36 percent of irrigation water may not obviously reduce the salt-leaching efficiency.The salinity in plough layer is reducing year by year under continuous water-saving irrigation or conventional irrigation,and the salinity difference between the two irrigation modes is not significant.Under the pipe drainage and drainless condition,the salt leached from aeration zone into groundwater can not be drained timely and accumulate beneath the root zone eventually.Compared with the drainless condition,the salt accumulation zone in soil profile is narrower and deeper,and the peak salt concentration is smaller under the pipe drainage condition.The research results not only demonstrate the feasibility of carrying out the water-saving irrigation and the necessity of strengthening the horizontal and vertical drainage from the perspective of soil salinity but also provide a reference for the planning of water-saving and drainage engineering and the reclamation of saline-alkali soil in the Yinbei irrigation district of Ningxia.