15
ing without allowing soil to spill or leak out. Drilling the
holes at a slight downward angle will minimize spillage.
2. Measure the mass of the empty container and the sensor
or sensors being used in the calibration.
3. Determine the volume of the container. This can be
done geometrically or by measuring the volume of sand
needed to completely fill the container.
4. Fill the container with air-dry, sieved soil.
5. Take a reading of the sensor in air, install the sensor in
the dry soil, and take the air-dry reading.
6. Place the container (with sensor installed) in a larger
receptacle and add distilled water around the OUTSIDE of
the container until the water level reaches the top of the
container. Allow the container to completely saturate.
Take a sensor reading.
7. Transfer the container to the scale and measure the
mass. It is advisable to have a tray to hold the container to
keep water from spilling on the bench. Be sure to zero out
the tare weight of the tray.
At this point, the procedure is to simply allow the con-
tainer to dry while periodically taking simultaneous
weight and sensor readings. Initially, the container will
dry rapidly and 2 or 3 readings per day may be appropri-
ate. As the container gets dryer, it will dry more slowly
and the frequency of measurements will decrease. When
the container returns to its air-dry value, the soil should be
removed, oven-dried at 105 ºC for 24 to 48 hours and al-
lowed to cool in a sealed container before measuring the
oven dry weight (ODWt).
Summary of Contents for WaterScout SMEC 300
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