Water retention characteristics of soils over the whole moisture range: a comparison of laboratory methods

摘要

The exact characterization of soil hydraulic properties is essential for various purposes, such as agricultural and groundwater management. Various laboratory methods for the determination of soil water retention characteristics are frequently applied. Standard methods comprise: (i) the hanging-water column and (ii) the simplified evaporation method (HYPROP (c)) for wet to moderate moisture ranges; and (iii) the pressure plate and (iv) the dew point method (WP4C PotentiaMeter (R)) for moderate to dry moisture ranges. These four methods were evaluated and compared, with the aim of demonstrating their compatibility. The hanging-water column method and the evaporation method provided comparable retention data in the wet to moderate moisture range. The dew point method provided corresponding results over the dry range, while retention data obtained from the pressure plate method sometimes had a tendency to over-estimate water contents. Hysteresis was observed for retention data in the dry range when applying the dew point method to previously wetted or dried samples.