Abstract
The relative pressure of water vapor at the air-water interface in soil indicates the energy status of water in the liquid film adsorbed on the surface of the solid phase of the soil. Thermocouple psychrometers now available make it possible, under favorable conditions, to measure the relative pressure of water vapor in wet soil with an accuracy of one or two parts per one hundred thousand (4). Useful information about mechanisms responsible for water binding in the adsorbed phase of water in soil can be obtained by comparing the effect of temperature on the relative pressure of soil water with the change of relative pressure of water solutions in bulk. Precise temperature control is required for such measurements and this in turn requires a sensitive method for measuring temperature change. This paper reports preliminary psychrometric measurements of soil water in the temperature range from 5° to 40°C, along with a brief description of the apparatus that was used for temperature control and measurement. © Williams & Wilkins 1962. All Rights Reserved.