Umwelt-Geräte-Technik GmbH
| Eberswalder Str. 58 | D-15374 Müncheberg | phone: +49 (0) 33 43 2 - 89 575 |
2.
General Information
2.1.
What are Tensiometers? / What is Tension?
Tensiometers are measurement devices for determining the soil water tension. The soil water tension
describes all influences exerted on the water by the soil matrix and is also called the matrix potential (or
simply pressure head). The tension is defined as a negative pressure and therefore is signed positive if
the applied pressure is negative. A pressure of -50 kPa in the pore water accords a tension of 50 kPa.
The tension is closely linked to the water content of a soil. The dryer a soil, the higher is the tension. At
the groundwater surface, the tension is zero. The relationship between water content and soil tension
is soil specific and depends highly on the soil properties.
PWP
= permanent wilting point
FC
= field capacity
)
figure 2 Exemplary retention curves of different soil types
