Investigation of the Wetting Front Distribution in Vertically Layered Arid Soils under Drip Irrigation

Soil wetting front depends on various factors, including soil texture, emitter flow rate, land slope, and volume of irrigation water. Accurate estimation of the curved shape of the wetting front distribution helps to know how much advanced water and liquid fertilizers have transported in porous media. A cube-shaped physical model was built, and the experiments were performed at emitter flow rates of ۲, ۴, and ۸ L/h and slopes of ۰, ۱۰, and ۲۰% on ۴ soil samples. Samples ۱ and ۲ were homogeneous soils, and samples ۳ and ۴ were vertically layered soils. The homogeneous soil samples had light, loamy sand (L) and heavy, clay (H) textures. The vertically layered soil samples included three layers. The results showed that the change in soil texture from L to LHL increased the average maximum wetting front radius downstream of the emitter (R_۰^-) At the mentioned flow rates by ۱۸, ۲۴ and ۳۵%, respectively. The change in soil texture from L to LHL decreased the mean depth of the wetting front (D) by ۱۶%, ۲۸%, and ۴۰%, respectively. With changing from H to HLH, the mean R_۰^- The mentioned flow rates decreased by ۲۷, ۳۲, and ۴۱%, respectively, and the mean D increased by ۲۲, ۳۵, and ۵۳%, respectively. Based on statistical analysis, results indicated that there were significant differences (p<۰.۰۵) between the layered and homogenous soils. Changing the soil texture around the emitter from L to H, especially on sloping lands, increases the wetting front radius and decreases its depth. Whereas changing the texture from H to L decreases the wetting front radius and increases its depth, thus reducing water loss.

کلیدواژه ها:

Arid Land ، Layered soil ، Sloping Land ، Soil Texture ، Wetting front