Saturated Hydraulic Conductivity of Semiarid Soils: Combined Effects of Salinity, Sodicity, and Rate of Wetting

Abstract

Combined effects of soil conditions (wetting rate), soil sodicity, and salinity on soil saturated hydraulic conductivity (HC) have not been studied systematically and were the objective of our study. We examined the effects of (i) exchangeable sodium percentage (ESP, 1–20) and fast wetting (50 mm h −1 ) and leaching with distilled water on the HC of 60 Israeli soils (7–70% clay); and (ii) wetting rate (2 or 50 mm h −1 ), ESP and water salinity (distilled water or saline water, 2 dS m −1 ) on the HC of 16 selected samples. Results of the first experiment showed that (i) steady state HC of medium‐ and fine‐textured soils was lower than 2 cm h −1 already for nonsodic soils, and (ii) the adverse impact of sodicity on the HC strongly depended on soil texture. The second experiment revealed that in the loamy sand rate of wetting had no effect on the HC beyond that of sodicity and salinity. In the loam, sandy clay and clay soils a significant triple interaction among water quality, wetting rate and ESP in their effect on HC existed. In the absence of electrolytes, the impact of fast wetting (slaking) and swelling on the HC was most notable, mainly at the intermediate sodicity levels (ESP = 5–10). Use of saline water significantly reduced the impact of fast wetting and swelling on the HC. Our results suggested that combined effects of salinity, wetting rate, and sodicity on the HC were complex and should thus be considered simultaneously when estimating soil HC.