IMPROVED THERMOCOUPLE PSYCHROMETERS FOR MEASUREMENT OF SOIL-WATER POTENTIAL IN A TEMPERATURE-GRADIENT

The improved psychrometer is constructed from high-thermal-conductivity materials to minimise temperature gradients within it. To minimise errors from condensation on the psychrometer, it is symmetrically constructed with respect to the porous windows where moisture exchange with the soil occurs. Zero offset of the new units is reduced by more than an order of magnitude compared with previous versions and measurement errors due to temperature gradients are less than one-third the value for the best designs previously available.