What is a tensiometer?

What is a tensiometer?

A tensiometer is used to measure the force required to obtain water from soil: known as soil moisture tension, soil water suction, or soil matric potential.

A porous ceramic cup or tube is buried in the soil at the depth of interest. This ceramic cup is connected to a water-filled reservoir (or a column of water) via a hollow tube or a flexible tube. The tension or suction of the soil moisture at the depth of the ceramic cup will cause water to move from the cup into the soil through the porous ceramic material.

As the soil moisture tension increases (indicating drier soil), it exerts a stronger suction on the water in the ceramic cup, causing water to move from the cup into the soil. Tensiometers typically measure soil moisture tension in units of centibars (cb) or kilopascals (kPa).