Campbell Scientific CS650 and CS655 Water Content Reflectometers - Manual (Page 41)

CS650 and CS655 Water Content Reflectometers
The volumetric water content is the product of the gravimetric water content
and the bulk density
θ θ ρ
v g bulk
= *
The average water content for the replicates and the recorded CS650 period are
one datum pair to be used for the calibration curve fit.
8.5 Calculations
The empty cylinders used for core sampling should be clean and both empty
mass and volume are measured and recorded. For a cylinder, the volume is
volume
d
h =

 

π * *
2
2
where d is the inside diameter of the cylinder and h is the height of the
cylinder.
During soil sampling it is important that the cores be completely filled with soil
but not extend beyond the ends of the cylinder.
Once soil core samples are obtained, place the soil-filled cylinder in a small
tray of known empty mass. This tray will hold the core sample during drying in
an oven.
To obtain m
wet
, subtract the cylinder empty mass and the container empty mass
from the mass of the soil filled cylinder in the tray. Remove all the soil from
the cylinder and place this soil in the tray. Dry the samples using oven or
microwave methods as described above.
To obtain m
dry
, weigh the tray containing the soil after drying. Subtract tray
mass for m
dry
. Calculate gravimetric water content, θ
g
, using
θ
g
wet dry
dry
m m
m
=
−
.
To obtain soil bulk density, use
ρ
bulk
dry
cylinder
m
volume
=
Volumetric water content is calculated using
θ θ ρ
v g bulk
= * .
9. Maintenance
The CS650 does not require periodic maintenance.
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