Useful notes
6.2 Maximum measuring range and data
interpretation
The measuring range of Tensiometers is limited by the boiling point
of water. At a temperature of 20°C the boiling point is at 2,3 kPa over
vacuum. So with 20°C and an atmospheric pressure of 95 kPa the
Tensiometer cannot measure a tension below -92,7 kPa, even if the
soils gets drier than that. The readings remain at a constant value
(fig. 7.1, between day 10 and 16).
Interpretation Messwerte bis über 15 bar nahe der
Bodenoberfläche
1
10
100
1000
10000
100000
0246810121416182
Zeit
Wasserspannung
0
Bodenwasserspannung
Tensiometermesswert
Interpretation of readings to -2 bars
Soil water tension
Tensiometer reading
Matrix potential negative (hPa)
Time
Fig. 7.1: Tensiometer readings with tensions to -2 bar
If the soil will get even drier and reaches -2 bar, the ceramic’s bubble
point is reached. The cup water will run out quickly and the reading
of the air filled cup will go to zero (fig. 7.1, day 16-19)
36/48
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