73 Soil Water Potential Measurement
Part 6. Soils
Published Online: 15 APR 2006
Copyright © 2005 John Wiley & Sons, Ltd
Encyclopedia of Hydrological Sciences
How to Cite
Durner, W. and Or, D. 2006. Soil Water Potential Measurement. Encyclopedia of Hydrological Sciences. 6:73.
- Published Online: 15 APR 2006
Soil water potential controls the dynamics of water in soils. This article describes methods to measure soil water potential. Available methods differ with respect to the moisture range where they are applicable. In the moist range, the pore water pressure of the soil is directly measured with tensiometers. In the intermediate moisture range, reference porous media are suitable, where the water saturation changes with water potential. Gypsum blocks, granular matrix sensors, heat dissipation matric potential sensors, and filter paper are used. If embedded in the soil and in hydraulic equilibrium with it, soil water potential is obtained by a calibration relationship from a water content dependent measurement in the reference porous medium. In relatively dry soils, water potential is derived from vapor pressure measurements by thermocouple psychrometry. This article presents the theoretical background of the various measurement techniques and illustrates the construction principles of measuring instruments. Problems and pitfalls of water potential measurements, in particular with tensiometers, are discussed. A list of manufacturers of water potential measurement instruments is given at the end of the article and a reference list provides material for further background information.
- soil hydrology;
- vadose zone;
- hydraulic properties measurement;
- heat dissipation sensors;
- thermocouple psychrometer;
- reference porous media