How does the Chameleon sensor work?

The Chameleon is a resistance-type sensor that is calibrated to give the soil water tension or suction.  It is different from a 'Gypsum Block' sensor.  The Gypsum Block is not sensitive in the 'wetter part' of the soil moisture range (colours blue and green on the Chameleon) and therefore not suitable for monitoring most irrigated crops.  The Chameleon sensor is comprised of an inner core of highly absorbent material that releases a lot of water in the 10 to 50 kPa suction range. This material effectively amplifies the soil water signal, so we get high resolution in the part of the soil moisture range most critical for irrigators. This inner core is coated with gypsum to provide buffering of electrical conductivity. The resistance reading is also corrected for changes in soil temperature.  

Why do we measure soil suction?

Each soil type has a unique relationship between the soil water content (the amount of water in a given volume of soil) and the soil water suction (the water stress experienced by the plant).  If you measure soil water content, there is a different 'number' for which you must irrigate each soil.  If you measure soil water suction with a Chameleon sensor, the blue, green and red colours mean the same from the perspective of the plant stress, regardless of soil type. In other words, soil water suction sensors do not need to be calibrated for soil type. 

What is the relationship between colour and soil suction?

Our aims is as follows: Blue 0-20 kPa (wet), Green 20 to 50 kPa (moist) and Red > 50 kPa (dry).  

It is very difficult to make every sensor change exactly at those suction values, and for practical irrigation purposes, it is not necessary either.

Every sensor we build is individually tested to check the colours change in the correct range (that is why your sensor may look 'used'). 

What does the colour dot mean on the sensor package?

Each sensor array is colour coded on the package after testing based on the blue to green switch point.

A yellow dot means the colour changed between 20 and 22 kPa.

An orange dot means the colour changed between 18 and 20 kPa.

A purple/pink dot means the colour changed between 22 and 24 kPa.

How long does the sensor last in the soil?

The expected lifespan of this sensor in the ground is 2 to 4 years, with the shorter time occurring in very wet, acidic or salty soils. The more recent designs are more durable for those who need to dig up and move sensors to other sites. As part of our research, we are modifying the design to increase accuracy and longevity.  

Why are my new sensors not reading any colour?

The sensors are very dry when packaged for shipment and too dry for the reader to detect them.

When you try and read them straight out of the packet you may see the message on the reader screen "Check connections". This is because the reader can only detect the temperature sensor and not the soil water sensors.

Before you can read the sensors you must soak them in a bucket of water until they turn blue. See the sensor installation instructions here https://via.farm/chameleon-sensor-installation-instructions/ 

What does the grey colour represent on the Visualisation?

The grey colour indicates the sensor is disconnected.

When a sensor cable is disconnected (open circuit) the reader sees it as a very high resistance. On the Visualisation, anything about 4000 kOhms is assumed to be an open circuit and is colour grey to alert you to the fault. Please check your wiring, particularly at the green terminal block where it may have come loose. You will need the small flat screwdriver supplied with your reader to fix the problem.

Sometimes the soil gets so dry (end of the red zone) that it goes beyond the accuracy of our Chameleon reader. this also shows up as grey on the visualisation and the colour will return when the soil is wetted again.  

How do I obtain a login for via.farm?

If you buy Chameleon equipment from our online shop https://viashop.csiro.au/ you will be issued account details and a farm will be created for you within a few days of completing payment.

If you are using Chameleon equipment supplied via an ACIAR funded project then you should have been issued account details.

If you have not received your account details then please contact us via the https://via.farm/contact-us/ page.

Please provide this following and request a login:

  • First name
  • Surname
  • Email address
  • Farm name (existing or new)
  • Your role in the project

How do I export sensor data to Excel?

You may want to export the sensor data into Excel or another program to analyse the data. You can do this following this method:

  1. Display the visualisation from the Visualise Farm, Visualise Crop, or Visualise Sensor Array pages.
  2. Click: Chameleon Data
  3. Press; Ctrl-A (to Select All)
  4. Press: Ctrl-C (to Copy)
  5. Paste into Excel
  6. Change the font colour of the heading (first row above the data) from white to black (so they can be seen).
  7. Deleted the extra rows at the top that you don't need

How to find your current geolocation without Internet access on your phone

Option 1:  App - Google Maps

  1. While you have Internet access run Google Maps, menu, Offline Maps, follow the on-screen instructions to download the maps for where you will be going that has no Internet access.
  2. Later, with no Intenet coverage, run Google Maps
  3. Wait for your phone to find the satellites (this may around take 5 minutes). You will know when it is ready when your map position changes to your current location.
  4. To find your geolocation, hold your finger on your current location and the coordinates will display in degrees, minutes and seconds.
  5. Click 'More info" and the coordinates will display in decimal (The decimal format is needed for entry into via.farm).
  6. Record the coordinates or click 'Share places' and message or email them to yourself.

Option 2:  App - My GPS Coordinates

  1. While you have Internet access, install the free App "My GPS Coordinates" from the Google Play store or Apple App store.
  2. Later, with no Intenet coverage run "My GPS Coordinates"
  3. Wait for the GPS satellites to be found.
  4. Record your decimal coordinates displayed.