Soil Salinity Resistance Effect on Evaporation

Resumo

Soil salinity is an increasing threat to agriculture and is a major factor in reducing plant productivity in arid and semi-arid regions. Knowledge of the transport process of mass and energy in subsurface soil is vital for understanding the environmental and economic impact of agricultural practices in these areas. A finite difference model, WASH_1D, was applied to evaluate various transport mechanisms associated with temporal variations in soil water content and soil salinity in 5 cm sandy soil columns. Experiment was conducted in a laboratory with fixed temperature and relative humidity. Soil columns were initially saturated with distilled water or 3000 ppm NaCl solution. The accuracy of the model was evaluated using measured soil water content and soil salinity at seven depths 0.2, 0.6, 1.2, 1.7, 2.4, 3.4 and 4.4 cm at the end of the experiment. Simulated cumulative evaporation was compared with the data measured with an electronic balance. Results showed that the liquid flux of distilled water treatment was sharply declined sooner than NaCl solution treatment which was associated with decreasing in moisture diffusivity. The contribution of the water vapor flux to the total moisture flux was 0.01 and 0.2% for distilled water and solution treatments, respectively. The RMSE values between simulated and measured cumulative evaporation lines were 0.77 and 1.08 (g) for the distilled water and solution treatments, respectively. It was observed that the solution treatment significantly reduced total cumulative evaporation up to 11% as compared to the distilled water treatment. Simulated results demonstrated that the model predicted soil water content and salinity with adequate accuracy.