Delta-T HH2, User Manual

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SM200 and ThetaProbes
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17
SM200 and ThetaProbes
Contents:
About SM200 and ThetaProbes
Navigation Map
Quick Start
Options
ThetaProbes Options Summary
Reading the ThetaProbe
About SM200 and ThetaProbes
SM200 and ThetaProbes e.g. ML2x measure volumetric soil moisture content, θ
v, by
responding to changes in the apparent dielectric constant of moist soil. These
changes are converted into a dc voltage in mV, which is then converted to soil
moisture content in the HH2 using a linearisation table and soil type parameters.
Volumetric soil moisture content is the ratio between the volume of water present and
the total volume of the sample. This is a dimensionless parameter, expressed either
as a percentage (%vol), or a ratio (m
3
.m
-3
).
If you tell the HH2 the Root-Depth and Field Capacity for a given soil it can also
display water deficit in mm (see "Water Deficit Explained" on page 103).