Abstract:

The effects of soil salt crusts on the soil hydrological process have gained considerable attention. Soil salt crusts have an important effect on the soil hydrological process. The formation process of salt crusts treated with different initial salt concentrations is substantially different, resulting in the difference of soil evaporation. However, the influence of salt crust formation on soil evaporation under different initial salt concentrations is not well understood. Therefore, this study theoretically and experimentally monitored and analyzed the changes in salt crust formation, evaporation, and soil surface temperature of sandy soil under irrigation water treatment with different initial salt concentrations to clarify the soil salt crust formation process of irrigation water treatment with different initial salt concentrations and its influence mechanism on soil evaporation. Results show that with the increase in initial salt concentrations, the salt crust quickly formed on the soil surface, the coverage of salt crust on the soil surface increased, the increase in the soil surface temperature slowed, and the evaporation decreased under the same light intensity and exposure time. The relationship between the initial salt concentrations and cumulative evaporation could be expressed by a logarithmic function (R²>0.90). With the increase in the initial salt concentrations, the inhibition efficiency of salt crust on soil evaporation increased from 24.14% (10 g·L^-1) to 71.99% (250 g·L^-1). The initial salt concentrations could significantly affect the formation process of salt crusts, thereby leading to a considerable difference in soil evaporation by changing the soil surface temperature.

Key words: initial salt concentration, salt crust, formation and development, soil surface temperature, soil evaporation