Tensiometer modification for diminishing errors due to the fluctuating inner water column

The fluctuation of the height of the water column inside tensiometers constitutes a source of systematic error in the measurement of soil water potential. The influence of the fluctuating water column can be strongly reduced by measuring pressure in a confined air space close to the tensiometer tip. A simple technique of inserting a lower air space connected to the pressure sensor is presented. Successful laboratory tests were performed on a tensiometer of 1-m length with an applied pressure range from 0 to 80 kPa.