EC-20, EC-10 and EC-5 User’s Manual
4. Collecting Data
17
to 8 dS/m. Its calibration equations are shown below for
mineral soil, potting soil, and rockwool growing media:
Dielectric Permittivity
Dielectric permittivity can be used to determine volu-
metric water content using external published equations
such as the Topp equation. Dielectric permittivity is
given by
= 1/(1.
x 10
-9
Raw
3
x 10
-6
Raw
2
x 10
-3
Raw
where RAW is the output from the Decagon data logger
using 3V excitation. If you are using a non-Decagon
data logger, dielectric permittivity is given by
= 1/(
x 10
-9
mV
3
x 10
-6
mV
2
x 10
-3
mV
Mineral Soils
According to our tests, a single calibration equation will
generally suffice for all mineral soil types with electrical
conductivities from 0.1 dS/m to 10 dS/m. Volumetric
water content (ø) is given by
ø = 8.5 * 10
-4
* Raw - 0.48 (1)
where
Raw
is the output from the Decagon data logger
using 3V excitation. If you are using a non-Decagon
data logger, VWC is given by
