DAVIS Soil Moisture Sensor & Temperature Probe User manual

Product # 6440, 6470
SOIL MOISTURE SENSOR &
MULTI-PURPOSE TEMPERATURE
PROBE
INSTALLATION INSTRUCTIONS
FOR USE WITH VANTAGE PRO WIRELESS LEAF & SOIL
MOISTURE/TEMPERATURE STATIONS
The WATERMARK Soil Moisture Sensor and the Multi-Purpose Temperature
Probe are for use with the Vantage Pro Wireless Leaf & Soil Moisture/Tempera-
ture Station, #6343. Please refer to your Wireless Leaf & Soil Moisture/Tempera-
ture Station Installation Manual for complete details on how to install and use
the sensors.
Note: These sensors are also compatible with the Soil Moisture/Temperature Station, #6361.
Connecting the Sensors
1. Run the sensor cables up through the grommets on the bottom of the station
housing.
2. Connect the temperature probes to the TEMP connectors.
3. Connect soil moisture probes to the SOIL connectors
4. Each matched temperature probe and soil moisture pair must use the match-
ing connectors. If a temperature probe is not used, the soil moisture reading
can be off as much as 1% for every 1°F (0.5°C) error in the soil temperature.
Note: If no soil temperature probe is used, the console will use a default temperature of
75ºF (24ºC) to compensate the soil moisture sensor readings.
Grommets
Sensor Cables Run through Grommets
Connecting Sensor Cables to the
Terminal Block

Page 2 Soil Moisture Sensor & Multi-Purpose Tempera-
5. Secure sensor cables to the cable
tie mounts located next to the
grommets.
Installation Procedure
1. Soak the soil moisture sensors
overnight in water.
• Always “plant” a wet soil
moisture sensor.
• If time permits, wet the soil
moisture sensor for 30 min-
utes in the morning and let
dry until evening, wet for 30
minutes and let dry over-
night, wet again for 30 min-
utes the next morningand let
dry again until evening. Soak over the next night and install wet. This
will improve sensor response during the first few irrigations or water-
ings.
2. Make sensor access holes to the depth required with a 7/8” diameter rod.
• Make a hole for the soil moisture sensor and
a separate adjacent hole for the temperature
probe.
• For very coarse or gravely soils, an oversize
hole of 1” to 1 1/4” may be needed to pre-
vent abrasion damage to the soil moisture
sensor membrane. In this case, you will need
to “grout in” the sensor with a slurry made
from the sample soil to get a snug fit in the
soil.
3. Always install sensors in the active root system
of the crop with a snug fit in the soil.
CAUTION:In gravelly soils and with deeper sensors, carefully
install the sensor to prevent damaging the membrane.
• Lack of a snug fit is the biggest problem in
obtaining good soil moisture sensor read-
ings.
• The ideal method of making the access hole
is to have a stepped tool. This makes an
oversize hole for the upper portion and an exact sized hole at the bottom
where the sensor is located.
Cable Tie
Cable Tie
Mount
When tightening
cable tie, make sure
cables are on top of
cable tie mount.
Securing Sensor Cables
2-1/2" (64 mm)
7/8" (22.5 mm)
Cold rolled steel,
round rod
1-1/4" (32 mm)
approximate
diameter
Overall length
variable
Stepped Sensor
Installation Tool

Page 3
4. After installing the soil moisture sensor, the hole needs to be carefully back-
filled and tamped down to prevent air pockets which could allow water to
channel down to the sensor.
• Fill the hole with water and push
the sensor down into the hole so it
bottoms out.
A length of 1/2” Class 315 PVC
tubing fits snugly over the sensor
collar and can be used to push the
sensor. A good snug fit in the soil
is important.
• Carefully backfill the access hole
with soil to eliminate any air
pockets.
5. You can solvent weld the 1/2” Class
315 PVC tubing to the sensor collar
for easier installation and removal.
• Use a PVC/ABS cement (IPS
Weld-on #794 or equivalent).
6. After you have installed the soil
moisture sensors, the sensors will
need one or two irrigation cycles to
“break-in” and acclimate to the soil
conditions and provide better accu-
racy.
Installation Procedure for Turf/Lawns
1. Cut a slight “V” shaped trench about 5” wide at the top and about 6” deep
into the turf--about 6” long.
2. Lift out the turf plug piece you just cut.
3. Press the sensors into the soil at about a 45 degree angle into the side of the
trench to set the sensors about 3”-5” below the soil surface. Make sure they
are good and snug in the soil.
4. Set the plug removed from the trench and compact it back into place. It will
repair itself in short order.
5. Run the wires to the Soil Moisture Station and connect them as described in
“Connecting the Sensors” on page 1.
6. If you withhold irrigation for several days and allow the soil to dry down a
bit, you should see the soil moisture readings start to creep upward.
7. Usually, you will not need to water the turf until the reading is in the 25-40
area at the recommended 3”-5” depth.
Sensor
Wires
Tape
1/2" PVC Pipe
Pipe welded to
sensor collar with
PVC/ABS cement
Soil Moisture
Sensor
PVC Pipe Welded to Soil Moisture
Sensor Collar

Product Numbers: 6440, 6470
Davis Instruments Part Number: 7395.158
Soil Moisture Sensor & Multi-Purpose Temperature Probe Installation Manual
Rev A Manual (5/22/02)
Copyright ©2002 Davis Instruments Corp. All rights reserved.
3465 Diablo Avenue, Hayward, CA 94545-2778 U.S.A.
510-732-9229 • Fax: [phone]
E-mail: [email protected] • www.davisnet.com
Removing the Sensors
1. When removing sensors prior to harvest in annual crops, it’s a good idea to
do this just after the last irrigation when the soil is moist.
2. Do not pull the sensor out by the wires. You may have to dig out, at least
partially, any sensors more than 12” deep or any sensors in dry soil. Careful
removal prevents sensor and sensor membrane damage.
3. When sensors are removed for winter storage, clean the sensors, dry them,
and place them in a clean, dry location.
Wiring Sensors
The soil moisture sensor and the temperature probe both come with a 15’
(4.6 m) cable.
• If additional wiring is required, up to 1000’ (300 m) of additional wire
can be spliced onto the sensor wire.
• The additional wire must be fully waterproof.
• We recommend using #18 gauge wire with UF insulation, and using a
3M Scotchpak or Duraseal heat shrink splice connector.
Note: Avoid long wire runs near power cables. The transient currents can affect the
small current used to read the sensors.
Contacting Davis Instruments
[phone] Technical Support, Monday – Friday, 7:00 a.m. – 5:30 p.m. Pacific
Time.
[phone] Fax to Customer Service or Tech Support.
www.davisnet.com Copies of User Manuals, Spec Sheets, and Application
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