Campbell Hydrosense, Instruction Manual

Page: 12 / 27

HydroSense
8
WC 33 Site1
Deficit 34 20
MENU
SELECT
Site
Exit
MENU
SELECT
MENU
SELECT
READ
ENTER
Site
1
Site
2..5
READ
ENTER
Cal
Exit
MENU
SELECT
Cal
0
Cal
100
MENU
SELECT
READ
ENTER
Press Select
until desired
Site is
selected
Press Enter
to select Site
Note : To enter reference values for a site, the site must be selected once to enter a
Cal 0 value and again to enter a Cal 100 value.
Press ENTER to store Cal 0 or Cal 100
readings or to exit the selection routine.
FIGURE 5-2. Selecting the site, lower (0) and upper (100) reference levels
When using the Water Deficit Mode, the same rod length
must be used for measurement as was used during
calibration of the reference levels.
5.4 A Water Deficit Mode Example
Consider an application where the HydroSense is used to help make irrigation
decisions for a crop. It is known that unacceptable plant stress occurs at water
contents less than 15% and excessive water drains from the plant root zone
when water content is greater than 30%. The 15% is chosen for the lower
reference level and the 30% for the upper reference level. The actual water
content values may be less important than the agronomist’s knowledge of soil
water conditions for a particular crop.
With the water content at the lower reference level, a measurement is taken
with the HydroSense after the site number is selected and while the CAL 0
CAUTION