Volume 31, Issue 2 (March 2008)
Estimation of Osmotic Suction from Electrical Conductivity and Water Content Measurements in Unsaturated Soils
Salt-affected soils are a common feature of an arid-zone landscape. Osmotic suction arises from the salt content in the soil pore fluid. In this research osmotic potential was obtained by measuring total and matric suction via the filter paper technique. The filter paper technique has been widely adopted for measuring soil water potential in the recent years and now is a U.S. standard.
One thousand and twenty samples of clay, silty clay loam, sandy clay loam, and loam having different levels of soil water content, between the field capacity (F.C.) and permanent wilting point (P.W.P.) defined as the soil water content below which plants wilt permanently, and ten levels of soil salinity were tested. The measuring tests were repeated three times and aimed at measuring the osmotic suction. By stepwise multiple regression analysis, four new empirical relations were obtained to estimate the osmotic suction as a function of soil water content and the electrical conductivity of saturation extracts (ECe).The results also indicate that the estimation of osmotic suction using the filter paper technique is inexpensive, relatively simple, and applicable to wide ranges of soil salinity.