38
Useful notes
SWT4 User Manual v3.1
Interpretation Messwerte unter 10 bar in tieferen
Bodenschichten
1
10
100
1000
10000
0
5
10
15
20
25
30
35
Zeit
W
a
s
s
e
rs
pa
nn
un
g
Bodenwasserspannung
Tensiometermesswert
If it rains before the soils reaches -15,000 hPa, the Tensiometer cup
will suck up the soil water. However, the soil water includes dissolved
gasses which will degas as soon as the soil dries again, increasing the
tension. This will result in a poor response, the signal curve will get
flatter and readings will only slowly adapt to the actual soil water
tension. Depending on the size of the developed bubble, readings will
get less close to the maximum (Fig 6.2, after day 20).
Fig. 6.2 Tensiometer readings with tensions to -10, 000 hPa
Other problems that can be recognized by checking the data:
Soil water tension normally change only slowly. An erratic signal curve
with many discontinuities could indicate, for example loose contacts,
moisture in defective cables or plugs, poor power supply or a data
logger malfunction.
With SWT4R Tensiometers, unsteady signals can also be caused by
solar radiation on the refilling tubes. To prevent this fit thermal
insulation - see page 16.
Soil
wa
ter t
en
sio
n (
hPa)
Interpretation of readings below -10,000 hPa
Soil water tension
Tensiometer reading
Day
