FAQ

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').  Our test criteria are that the sensor must change from blue to green in the 18-24 kPa range and from green to red in the 45 to 60 kPa range.   As we improve our manufacturing techniques we are consistently getting close to the 20 and 50 kPa switch points 

How long does the sensor last in the soil?

The expected lifespan of this sensor in the ground is 2 to 5 years, with the shorter time occurring in acidic or salty soils. We are regularly modifying the design to increase accuracy.  We do dig up and retest sensors, but this version of the sensor is just 18 months old (and the calibrations have not shifted).      

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 moisture 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/ 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