HIM tensiometer sensors for determining soil moisture


Tensiometers are used for continuous measurement of soil moisture based on suction tension. The drier a soil is, the greater the potential of the adsorption and capillary forces that bind the water in the soil. Due to their design, tensiometers can measure suction tensions from 0 to approx. -850 hPa.

Soil moisture is measured via the suction tension, i.e. the drying out of a soil. The measurement is carried out by means of a water-filled, airtight, porous ceramic cell ("ceramic candle") (1) with maximum pore diameters of approx. 1 µm, which is placed in the soil. A transparent plastic tube (2) is used to check the filling level. Degassed water is used for filling, which can also be coloured if necessary.

When the soil around the ceramic cell dries out, so much water is "drawn" out of the ceramic cell until an equilibrium with the surrounding soil water is reached. The resulting negative pressure is indicated with a manometer or can be processed electronically by means of a pressure sensor (4).

Tensiometers are used for continuous measurement of soil moisture based on suction tension. The drier a soil is, the greater the potential of the adsorption and capillary forces that bind the... read more »
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HIM tensiometer sensors for determining soil moisture


Tensiometers are used for continuous measurement of soil moisture based on suction tension. The drier a soil is, the greater the potential of the adsorption and capillary forces that bind the water in the soil. Due to their design, tensiometers can measure suction tensions from 0 to approx. -850 hPa.

Soil moisture is measured via the suction tension, i.e. the drying out of a soil. The measurement is carried out by means of a water-filled, airtight, porous ceramic cell ("ceramic candle") (1) with maximum pore diameters of approx. 1 µm, which is placed in the soil. A transparent plastic tube (2) is used to check the filling level. Degassed water is used for filling, which can also be coloured if necessary.

When the soil around the ceramic cell dries out, so much water is "drawn" out of the ceramic cell until an equilibrium with the surrounding soil water is reached. The resulting negative pressure is indicated with a manometer or can be processed electronically by means of a pressure sensor (4).

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