Using HYDRUS to simulate the dynamic changes of Ca2+ and Na+ in sodic soils reclaimed by gypsum
Soil and Water Research
Wang J., Bai Z., Yang P. (2016): Using HYDRUS to simulate the dynamic changes of Ca 2+ and Na + in sodic soils reclaimed by gypsum. Soil & Water Res., 11: 1-10. Sodic soils are characterized by the occurrence of excess sodium to levels that can adversely affect soil structure. In recent years, with the advent of alternatives for reclaiming sodic soils, such as the addition of by-products of flue gas desulfurization, fly ash, phosphogypsum, etc., using CaSO 4 to reclaim sodic soil has again
... soil has again become a hot topic. In this study, cation exchange batch experiments and column leaching experiments were conducted to analyze the adsorption-exchange and dynamic changes of Ca 2+ and Na + during the reclamation of sodic soils with CaSO 4 . The HYDRUS-1D software was subsequently used to simulate and predict dynamic changes in Ca 2+ and Na + . The cation exchange batch experiments consisted of six treatments with six CaSO 4 rates (0, 0.25, 0.5, 1, 1.5, and 2 g/l), and the column leaching experiments consisted of two treatments with two CaSO 4 concentrations (0.5 and 1.5 g/l). The results of the static cation exchange batch experiments indicated that the ion adsorption-exchange coefficients K Ca-Na , K Ca-Mg , and K Ca-K were 1.9, 0.8, and 1.1, respectively. Applying CaSO 4 and leaching are efficient methods to reclaim sodic soil. The pH and electrical conductivity of the soil solution gradually decreased with longer leaching time in all of the treatments. HYDRUS-1D successfully simulated both the dynamic changes of the Ca 2+ and Na + concentrations at different soil depths under different treatments and leaching time, and the effects of soil hydraulic conductivity and soil pH on the transport of Ca 2+ and Na + . The correspondence between the observed and simulated variables was remarkable.