Decagon Devices EC-5, Руководство пользователя

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EC-5 User’s Manual
4. Collecting Data
15
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
ø = 11.9 * 10
-4
* mV - 0.401
(2)
where mV is the output of the sensor when excited at
2500 mV. Please note that the equation will reach a
maximum at ~60% volumetric water content (VWC) in
pure water. To display data on a scale from 0 to 100%,
VWC should be modeled with a quadratic equation
(which would result in a 100% VWC in water), but a
linear equation fits the mineral soil VWC range as well
as the quadratic, and linear equations are easier to deal
with, especially since mineral soil typically saturates at
~40 - 50% VWC.
Potting soil
The following equations can be used to convert EC-5
output to water content in potting soil. We tested several
types of potting soil (Sunshine mix, Miracle Grow Pot-
ting Mix, and Custom Nursery soil) at several salinities
and found that VWC is given by
ø = 1.3 * 10
-3
* RAW - 0.696 (3)
for a Decagon data logger or
ø = 2.11 * 10
-3
* mV - 0.675
(4)
for a data logger with 2500mV excitation.