1 - ceramic finely porous candle
2 — a tube filled with water,
3 — sealed cover
4 — device for measuring pressure.
A tensiometer is a device for determining the capillary (matrix) component of the soil moisture potential . In the simplest case, it consists of a ceramic finely porous plate (candle) filled with water in a plastic or glass tube and a vacuum gauge . The entire system must be airtight and free of air. Often the vacuum gauge is installed on a separate elbow of the tube, the other end of which is closed by a conventional plug, which is necessary to remove air and add water.
The device can operate in the pressure range from 0 to −600 ... -700 cm of water column . To calculate the capillary-sorption pressure from the readings of the vacuum gauge, it is necessary to subtract the pressure of the suspended liquid column in the device (from the candle to the vacuum gauge).
The tensiometer is used both in scientific research and in production. For example, it can be used to continuously monitor soil moisture and, as soon as it is below the permissible level, watering starts. Full automation of this process is possible.
The first tensiometers were proposed to be used by American Barton E. Livingston in 1908 to automate the irrigation of seedlings in closed ground. However, back in 1848, another American J. Babinet reported on a device based on a ceramic candle for automatic watering of plants, perhaps this was the first tensiometer. The spread of tensiometers received since the 1920s.
Tensiometer Examples
- Tensiometer du nui
Tensiometric Station
The tensiometers are installed in the station at 2. The first station is shallow 30 cm and the second deep 60 cm.