Delta-T HH2, User Manual

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Navigating Options and Readings
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11
Using the Options Menu
Select your Device option first - the other options depend on which device has been
selected.
Note: before you can select a WET sensor device you must install the WET sensor
calibration file using HH2Read ( see Install WET Sensor Calibration on page 41).
You may specify any Plot ID (A - Z), Device ID (0 - 255) and Sample ID (1 - 2000) for
any reading. These are just labels.
You may choose which engineering
units to display result.
For soil moisture you must select a soil type unless you only want mV readings.
(Equitensiometers readings are only available in mV.)
The default soil type is Mineral.
Advanced users, able to calibrate their own soils, may install their own soil specific
calibration coefficients called a0 & a1 under Soil Set-Up . (b0 & b1 for WET sensors).
Other users should use the Mineral and Organic soils already defined in the Moisture
Meter.
WET users have a choice of standard soil types and, if purchased pre-installed in the
HH2, custom calibrations for specific commercial artificial soils such as stone wool.
If you want
mm deficit you MUST define the Field Capacity and Root Depth for
each soil type. We provide a table in the back of this manual for mineral soils. Organic
soils are so variable you have to determine the field capacity experimentally, before it
makes any sense to take mm Deficit readings.
The default for Field Capacity is pre-set to the 38% corresponding to a silty clay loam.
The default Root Depth, set to zero, forces the calculated default value for mm Deficit
to be zero. See Calculating Field Capacity on page 108.
Some crop consultants recommend 700 mm as the default Root Depth.
For ease of graphing data it is good to always measure your sensors in the same
order each visit.
Some experts recommending having three sensors, or access tubes, at each
location, and taking three readings from each, to average out random sampling errors
later on your PC.