When installed in soil, water must pass freely from the tensiometer through the ceramic tip into the soil, creating a vacuum in the tensiometer that equals the soil water tension. Proper instal- lation of the tensiometer achieves good contact between the ceramic tip and the soil.

What is a tensiometer and how does it work?

A tensiometer is a closed, water-filled tube with a porous ceramic tip at one end and a vacuum gauge at the other, which acts like an artificial plant root. As the soil dries out, it exerts suction on the water in the tensiometer and this is measured on the gauge.

At what pressure tensiometer is used?

The tensiometer range is limited to suctions (absolute values of the matric potential) of less than 100 kPa, i.e., 1 bar, 10 m head of water, or ∼1 atmosphere. Therefore other means are needed for matric potential measurement under drier conditions.