The determination of soil-water desorption curves for soil cores

TLDR: In this paper, an improved technique for measuring soil water desorption curves of a large number of soil cores was tested, which resulted in rapid extraction of water from 7.6 cm cores at pressure heads from 0 to −500 cm of water.

Abstract: An improved technique for measuring soil water desorption curves of a large number of soil cores was tested. A procedure for improving contact between the soil and a "tension medium" resulted in rapid extraction of water from 7.6 × 7.6-cm cores at pressure heads from 0 to −500 cm of water. The data for clay and sandy loam cores showed that equilibrium was reached in less than 200 h at all pressure heads. The "tension medium," used essentially as a large porous plate, was carefully chosen with a narrow pore size distribution. This provided a high hydraulic conductivity and high air-entry values, both necessary for efficient desorption over the pressure head range 0 to −500 cm of water. A tensiometer-pressure transducer combination for establishing equilibration time proved more reliable than the traditional weight-loss criterion. The consistency and reproducibility of desorption curves was demonstrated using data for hysteretic loops as well as standard deviations of water contents at each pressure head on...