| Based on the review of national and international research results of soil solute transport and saline water use, both theoretical analysis and laboratory experiments were conducted to study infiltration of water and solute transport in layered soils, automatic measurement of soil water and solute transport parameters , and safe use of slightly saline water. Major findings are as follows:1. For sand interbedded with a loamy layer, or loamy soil interbedded with a sand layer, when the wetting front reached the interface, the nonlinear relationship of cumulative infiltration changed into a linear process, but the mechanism was different. When the sand was inter-layer, the infiltration decrement with particle size.2. With CDE model and CXTFIT program, transport parameter of four soils'were obtained according to BTC measurement. The results showed that the dispersivity of soil with a loam inter-layer is connected with the dispersivity of uniform soil. The values of D andλfor a sand inter-layer of 2-5mm were bigger than that for a sand inter-layer of 1-2mm. When WeiHe sandy soil interbedded with a loamy layer, the solute breakthrough curve of soil with 1-2mm sand inter-layer fallen behind the soil with WeiHe sandy inter layer.3. With a"instrument of soil water and solute parameter measured", the relationship of wetting front and infiltration time were accurately measured, the soil water parameters were then calculated with different models. The change of solute front with time were also measured by the instrument, the solute transport parameters obtained from boundary layer theory method were close to breakthrough curve fitting. So the boundary layer theory method is feasible.4. When saline water infiltrated, cumulative infiltration, wetting front and infiltration rate of alkaline soil increased with the concentration of infiltration solution. The salt content of the profile increased with the concentration of infiltration solution, but the desalting rate decreased, the degree of decrement was large. The value of SAR also influenced the infiltration. When SAR was 14, the average salt content of soil is minimum; When SAR was 5, the average salt content is maximum. The desalting depth is same for the solution of SAR is 5 or 14. The pattern of the soil solutionconcentration and salt content change was similar. Leaching alkaline soil with saline water of different concentration showed that salt content and the concentration of ion in same volume of outflow increased with the concentration of saline water. When SAR of leaching solution was different, the salt content of outflow was not significantly different, salt content decreased with cumulative infiltration. The average desalting rate decreased with concentration of saline water. When the SAR and concentration of saline water remained unchanged, the salt of outflow was connected with cumulative infiltration but was not affected by initial water content.5. When saline water infiltrated, cumulative infiltration, wetting front and infiltration rate of saline soil increased with the concentration of infiltration solution. When the concentration was 2.5g/l, infiltration decreased with increasing salinity of infiltration water. The salt content and soil salt concentration increased with soil depth, but salt content and soil salt concentration weren't related with the concentration of infiltration solution. For solution concentration of 2g/l, cumulative infiltration, wetting front and infiltration rate had no connection with SAR. The concentration of ion in wetting front decreased with increasing SAR. Salt content in same volume of outflow changed little with different concentration and SAR of saline water. There is an exponential relationship between salt content, ion concentration and volume of outflow. When SAR of Leaching solution is 5, the salt content of outflow is highest in same volume outflow. Leaching saline soil with slightly saline water decreased the salt content sharply and the leaching effect was better than Leaching alkaline soil with saline water.
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