Appendix
⚫
67
Laboratory calibration for clay soils
This technique is adapted to avoid the difficulty of inserting the WET150 into
completely dry clay soil. It requires taking measurements at 2 significantly
different, but still damp, moisture levels.
Equipment you will need:
•
WET150 and WET150 Meter with the
Soil type
set to “RAW”.
•
Soil corer
•
Heat-resistant beaker (
1.0 litre)
•
Weighing balance (accurate to < 1g)
•
Temperature controlled oven
Process
Notes and example
Collect a wet sample of the clay soil: 25 to 30%
water content would be ideal.
This sample needs to be unchanged from its in-situ
density, to be ~1.0 litre, to have the correct
dimensions to fit the beaker, and to be generally
uniform in water content.
This is most easily done with soil-corer.
Measure the volume occupied by the sample.
L
s
= 960ml
Weigh the wet sample, including the beaker.
W
w
= 1693g
Insert WET150 into the sample, press [Read] on
the meter and record the permittivity reading (
ε’
).
ε
w
= 15.90, I.e.
√
ε
w
= 3.99
1693.0
