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Additional notes
10.2 Vapour pressure influence on pF/WC
If the temperature of a soil with a constant water content rises from
20°C to 25°C the soil water tension is reduced by about 0,85 kPa
due to the increased vapour pressure which antagonizes the water
tension.
Temperature
4
in °C
Pressure
change per
0,6
Kelvin in [hPa]
10.3 Osmotic effect
The ceramic has a pore size of r = 0,3 m and therefore cannot block
ions. Thus, an influence of osmosis on the measurements is
negligible because ion concentration differences are equalized
quickly. If the T5 cup is dipped into a saturated NaCl solution the
reading will be 1 kPa for a short moment, then it will drop to 0 kPa
again.
10
16
20
0,9
1,2
1,5
77/92
25
30
50
1,9
2,5
7,2
70
14
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