Tensiometers are used for continuous measurement of soil moisture based on suction tension. The tensiometer measures suction tension from 0 to approximately -600 mbar. In dry conditions, the clay cell of the tensiometer transports water from the inside to the outside through its capillarity, creating a negative pressure in the closed tube. This negative pressure is an indicator of moisture. Suction tension is the force with which water is held in the soil or made available. This force must be exerted by plant roots to absorb water. Intense substrate contact is essential for a quick tensiometer response and for measuring typical values of certain soil and substrate types.