Changes in the soil drainage properties in different salinization treatments

抄録

Soil sodification is a soil degradation process that commonly occurs in the irrigated soils of arid and semi-arid lands, resulting in a significant decrease in productivity. Assessing the impacts of different types of water (irrigation water, groundwater, and rainfall) on soil drainage is important for achieving sustainable land management of irrigated areas. We investigated the changes in soil saturated hydraulic conductivity (HC) under different salt treatments by separating the effects of swelling and dispersion. The salt treatments were conducted at different salt compositions (SAR∞, SAR10, SAR0; SAR=Na/(Ca/2)^1/2 (cations: mol_c L^–1)) and concentrations (0.05, 0.01, 0.001 N) on Indian soil (sandy clay loam). The soil columns were continuously leached with each treatment solution and changes in the HC were plotted against the cumulative amount of leaching solution. Furthermore, the effects of swelling and dispersion by Na on the drainage properties were observed separately. Our results support the existing findings that dispersion is triggered at concentrations below the critical coagulation concentration (CCC), which further varies with the degree of sodification in a single mineralogy. The distinct manner of HC reduction between SAR10- and SAR∞-treated soils could imply different behaviors of the dispersed particles, which form a soil crust or cause soil erosion. Finally, we present the preliminary results of our experiments and discuss future research on the CCC reset mechanisms.