CS650 and CS655 Water Content Reflectometers
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calibration. However, intentionally changing water content in soil profiles is
difficult.
Soil hydraulic properties are spatially variable. Obtaining measurements that
are representative of the soil on a large scale requires multiple readings and
sampling. The average of several core samples should be used to calculate
volumetric water content. Likewise, the CS650 should be inserted at least three
times into the soil recording the permittivities following each insertion and
using the average.
The following is the procedure for obtaining samples.
1.
Use a shovel to form a vertical face of soil.
2.
If using the CS650 within about 0.5 meters of the surface, insert the sensor
into the face.
3.
Add water to the surface using percolation.
4.
Frequently observe the CS650 permittivity output, waiting for the
permittivity to be constant. This indicates equilibration.
5.
Record the CS650 permittivity.
6.
Repeat steps 2 through 5 at least three times.
7.
Remove the CS650.
8.
Take core samples of the soil using this process:
a.
Evenly push copper tubing into the soil surface.
b.
Remove the tube containing the sample and gently trim the ends of
excess soil.
c.
Remove excess soil from outside of tube.
d.
Transfer the soil from the tube to the oven or microwave safe
container.
If samples must be stored prior to weighing, seal the container
with tape or inside a plastic bag to prevent water loss and store
away from direct sunlight.
e.
Weigh the container holding the wet soil, and subtract the container
weight from this value to get the wet soil mass.
f.
Record the wet soil mass.
g.
Remove water from the sample by heating using an oven or
microwave. Oven drying requires 24 hours at 105 °C. Microwave
drying typically takes 20 minutes depending on microwave power
and sample water content. ASTM Method D4643-93 requires heating
NOTE
