EVALUATION OF THE FILTER PAPER METHOD FOR ESTIMATING SOIL WATER POTENTIAL

Abstract

The filter paper method for measuring soil water potential was evaluated. The method was calibrated using salt solutions, thermocouple psychrometer, pressure plates, and soil columns at equilibrium. The predicted water potential was influenced by the type of contact of the soil with the filter paper. It is suggested that one filter paper be placed beneath the soil (good contact for liquid flow and vapor flow) and one filter paper be placed above the soil not in physical contact (allowing vapor flow only). It was found that the absolute temperature was not too important but temperature variations had a large effect on the predicted soil water potential. The filter paper method for measuring soil water potential was evaluated. The method was calibrated using salt solutions, thermocouple psychrometer, pressure plates, and soil columns at equilibrium. The predicted water potential was influenced by the type of contact of the soil with the filter paper. It is suggested that one filter paper be placed beneath the soil (good contact for liquid flow and vapor flow) and one filter paper be placed above the soil not in physical contact (allowing vapor flow only). It was found that the absolute temperature was not too important but temperature variations had a large effect on the predicted soil water potential. © Williams & Wilkins 1974. All Rights Reserved.