How to Read a Watermark Sensor

Installation

• 1

  Soak the sensor in in the morning for 30 minutes, then let it dry all day. Re-soak it for 30 minutes at night, then let it dry all night. Soak the sensor for 30 minutes the next morning, let it dry all day, then soak it all night.

• 2

  Dig a sensor hole to the desired depth the next morning while the sensor is still wet. Use an Irrometer sensor installation tool or a 7/8-inch O.D. metal rod.

• 3

  Fill the hole with water. Place the sensor into the hole and tamp it down to the bottom with a length of PVC pipe. Make sure the two sensor leads are routed out of the hole properly. Remove the pipe and backfill the hole with soil. Label the sensor wires to indicate the depth at which the sensor is buried.

Programming the Temperature

• 4

  Set the soil temperature reading in the meter once at the beginning of each season by taking the soil temperature with a soil thermometer.

• 5

  Press and hold the "Read" button on the meter. Press "Temp" to toggle the scale between Fahrenheit and Celsius. Release the "Read" button.

• 6

  Press and hold "Temp," then press "Read" to begin scrolling temperatures on the LCD screen. Release the "Temp" button when the desired temperature appears on the screen.

Reading the Sensors

• 7

  Connect the meter leads to the sensor leads with alligator clips. Make sure the leads do not short together.

• 8

  Press the "Read" button on the sensor. The meter's LCD screen will display " --". Press "Read" again and the meter's LCD screen will display the moisture reading in centibars.

• 9

  Evaluate the readings. A reading of 0 to 10 centibars indicates fully saturated soil; 10 to 30 centibars indicates that the soil is acceptably wet. A reading of 30 to 60 centibars is the normal range at which to begin irrigation in most soils; 60 to 100 centibars is the normal range at which to begin irrigation in heavy clay soils. 100 to 200 centibars indicates that the soil is becoming dangerously dry and production may be adversely affected.