DAVIS Soil Moisture Sensor & Temperature Probe, Soil Moisture Temperature Prob Installation Instructions Manual

SOIL MOISTURE SENSOR &
MULTI-PURPOSE TEMPERATURE
PROBE

INSTALLATION INSTRUCTIONS

FOR USE WITH VANTAGE PRO WIRELESS LEAF & SOIL
M

OISTURE/TEMPERATURE STATIONS

The WATERMARK Soil Moisture Sensor and the Multi-Purpose Temperature
Probe are for use with the Vantage Pro Wireless Leaf & Soil Moisture/Tempera­ture Station, #63 43. Please refer to your Wireless Leaf & Soil Moisture/Tempera­ture Station Installat ion Manual for complete details on how to install and use
the sensors.

Note: These sensors ar e also compatible with the Soil Moisture/T emperature 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 pr obe and soil moisture pair must use the match­ing 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.

Grommets

Conne cti ng S ensor Cabl e s t o th e

Terminal Block

Note: If no soil temperature pr obe is used, the console will use a default temperature of

75ºF (24ºC) to compensate the soil moisture sensor readings.

Sensor Cables Run through Grommets

Product # 6440, 6470

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 senso r fo r 30 min­utes in the morning and let
dry until evening, wet for 30
minutes and let dry over­night, wet again for 30 min­utes the next mo rning and let
dry again until evening. Soak over the next night and install wet. This
will improve sensor response during the first few irrigations or water­ings.

When tightening
cable tie, make sure
cables are on top of
cable tie mount.

Securing Sensor Cables

Cable Tie

Cable Tie
Mount

2. Make sensor access holes to the depth required with a 7/8” diamet er rod.

• Make a hole for the soil moisture sensor and
a separate adjacent hole for the temperature
probe.

• For very co ars e or gravely soil s , an oversize
hole of 1” to 1 1/4” may be needed to pre­vent abrasion damage to the soil moisture
sensor membrane. In this case, you will need

Cold rolled steel,
round rod

1-1/4" (32 mm)
approximate
diameter

to “grout in” the sen s or wit h a slur r y mad e
from the sample soil to get a snug fit in the
soil.

Overall length
variable

3. Always install sensors in the active root system
of the crop with a snug fit in the soil.

CAUTION:In gravel ly so ils an d with de eper sen sor s, car e fu lly

install the sens or to prevent damaging the mem brane.

2-1/2" (64 mm)

• Lack of a snug fit is the biggest problem in
obtaining good soil moisture sensor rea d­ings.

7/8" (22.5 mm)

Stepped Sensor

Installation T ool

• The ideal method of making the access hol e
is to have a stepped tool. This makes an
oversize ho le for the upper porti on and an exact si zed hole at the bott om
where the sensor is located.

Page 2 Soil Moisture Sensor & Multi-Purpose Tempera-

4. After installing the soil moisture sensor, the hole needs to be carefully back­filled and tamped down to prevent air pockets which could allow water to
channel down to the se nsor.

• 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 t he 1/2” Class
315 PVC tubing to the sensor collar
for easier installation and remo val.

• 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
“bre ak-in” and acclimate to the soil
conditio ns and provide bet ter accu­racy.

Tape

Sensor
Wires

1/2" PVC Pipe

Pipe welded to
sensor collar with
PVC/ABS cement

Soil Moisture
Sensor

PVC Pipe Welded to Soil Moisture

Sensor Collar

Installation Procedure for Turf/Lawns

1. Cut a slig ht “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 senso r s into th e soil at abo ut a 45 degree ang l e into th e 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 Soi l Moist ure Statio n and con nec t the m as descri b ed 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 upwar d.

7. Usually, you will not need to water the turf until the reading is in the 25-40
area at the recommended 3”-5” dep th .

Page 3

Removing the Sensors

1. When removing sensors prior to harv e st 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 pr ev ents sensor and sensor membrane damage.

3. When sensors are removed for winter stora ge, cl ean 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 additi onal 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 shri nk splice connec tor.

Note: Avoid long wire runs near power cables. The transient currents can affect the

small current used to read the sensors.

Contacting Davis Instrumen ts

[phone] Technical Support , Monday – Friday, 7:00 a.m. – 5:30 p.m. Paci fic
Time.

[phone] Fax to Customer Service or Tech Support.
www.davisnet.com Copies of User Manuals, Spec Sheets, and Application

Notes are available on the “Support” page. Watch for FAQs and other updates.
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[e-mail] E-mail to Technical Support.

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.

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