Chameleon Card System

The Chameleon Card System has to be the simplest way to measure soil water. Touch the two sensor wires on the card and the LED lights up. The light will turn blue (wet), green (moist) or red (dry) to show the soil water status.

The sensors are the same as we use with the Chameleon Wi-Fi Reader. They are the product of many years of research and will give you reliable readings.

Not everyone needs to have an online record of soil water status. Often a quick check is all you need. If you want to collect and organise the data from your Chameleon Card System, and have an Android device, you can use our App which is available to download from the Play Store. This will also create a record of your farm and sensor readings on our website.

For more detailed or frequent data logging please refer to the Chameleon Wi-Fi System.

Install

    Sensors can be installed at a single depth in several locations. Install a sensor in the middle of the root zone. Alternatively, sensors can be installed at different depths in the same hole. This allows you to see the progression of roots down into the soil through the growing season, as the colours turn from blue to green to red. Multiple depths also let you to see how deeply the water has penetrated after irrigation.

    If you are using the App, now is the perfect time to add a sensor set to your farm. For best results make sure you accurately record sensor depth, location and crop.

    Sensors can be left in place for the next crop or removed at the end of the season and reinstalled.

  1. Soak the sensor in water for a few minutes before installation.
  2. Sensors can be installed:
    • individually in the active rootzone Depth suggestion: 20 cm
    • at several depths in the same hole Depth suggestion: 10, 20 and 40 cm
  3. Create a hole using
    • a trowel or auger
    • a 20 mm pipe (metal or PVC)
  4. Use a metal rod or wooden dowel to compact the soil down the hole and around the sensor, ensuring there is good contact between the sensor and soil.

Use

  1. Hold down the button (yellow flashing)
  1. While holding down the button, place the two bare wires into the slots
  1. The LED will display blue, green or red
  1. Enter data into the App or record manually

The Chameleon Card can be used on its own or in conjunction with the other VIA monitoring systems.

When used together with the WFD solute monitoring system, you have a simple way of measuring soil water, nitrate and salt. Records can be kept in a notebook or using coloured beads.

The Card can also be used in conjunction with the Chameleon Wi-Fi reader. For large farms, the Wi-Fi Reader can log in one place and the Card Reader used for spot checks in different locations.

On smallholder irrigation schemes, a proportion of farmer can use the Wi-Fi system while the rest use Cards. This ensures the maximum number of farmers can benefit, while still collecting on-line data for further analysis and learning.

LED colour Meaning
Blue Wet soil
Green Moist soil
Red Dry soil
Flashing purple High salt warning
Flashing yellow Sensor wire is not connected or very dry
Flashing red Battery needs replacing

Maintenance

If the sensor reads red with no wire connected, remove from the cover, clean and dry the gold leaves with a tissue on both sides.

Battery life

The battery should last for 1000 readings. When the LED flashes red, the battery needs to be replaced.
Battery: Disposable CR2032 watch battery

Caution

The sensors slowly degrade over time with products harmless in soil. If the sensor is broken, avoid breathing dust from the sensing material from the inner core.

VIA Phone App

The VIA phone app helps you store and visualise data collected from Chameleon Card sensors.

To download the App from your phone click VIA App download or open Google Play Store and search for "Chameleon Card System by VIA"

For details on using the App, visit VIA App - Getting Start Guide

Learn

All crops do not have the same sensitivity to water stress, but there are robust principles for interpreting the colours.

The blue LED means that the soil is wet. Irrigating when the LED is blue wastes water and leaches nutrients. There are some exceptions, such as plants in pots with restricted rootzones may need to be kept blue, as well as leafy vegetable on hot days.

The majority of the horticultural crops should be watered in the green zone. Be aware that the green zone does not last for long! A soil may have been blue for many days and then move from blue to red in just a day or two of hot weather.

Most horticultural crops will lose yield in the red zone. This is particularly the case for leafy crops or if the red colour coincides with flowering and fruit set of other crops.

Responding to the colours does depend on how deep the roots are compared to where the sensor is located. A fruit tree with a red sensor at 20 cm depth will likely be happy enough if there is water below.

If LED flashes purple, then the colours need to be interpreted differently. Due to the presence of excess salt, the plant is under more stress in the green than normal. Irrigation may be necessary in the blue zone and definitely in the green zone.

FAQ

Sensors are designed to operate at the following switch points:

  • Blue 0-22 kPa (wet soil)
  • Green 22 to 50 kPa (moist soil)
  • Red > 50 kPa (dry soil)

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

The sensors are dry when packaged for shipment and too dry for the reader to detect them. Before use, soak sensors in water until they turn blue.

Sensors can be placed at three depths in the same hole, e.g. at 20 cm, 40 cm and 60 cm. Alternatively, they can be installed at one depth at several different locations. For shallow-rooted crops, a single sensor may be placed at 10 to 20 cm depth. For deeper rooted crops, a single sensor may be placed at 20 to 30 cm depth. These depths represent the part of the root zone where most of the water is extracted.

Although irrigation systems are designed to give a uniform distribution of water, there is always variability. For example, flood irrigated fields can be wetter at the end of the furrow than in the middle. Try to pick locations that are representative of a field. Multiple measuring points can be used to help achieve more uniform water delivery across an entire field.

It is worthwhile to do an irrigation uniformity test before installing sensors. Sensors located in dry or wet patches will not be representative of the entire field. This is particularly important for sprinklers. For drip irrigation, sensors should be placed half-way between the emitter and the edge of the wetting pattern. Locating the sensors directly under the drip emitter will shorten their lifespan.

Sensors should give accurate readings for two to four years, depending on soil conditions. The lifespan can be shorter in very wet or salty conditions and where sensors are placed at shallow depth directly under drip emitters. If your sensor no longer turns blue after irrigation, it is time to replace it.

The sensors slowly degrade over time with products harmless in soil. If the sensor is broken, avoid breathing dust from the sensing material from the inner core.

The gypsum coating around the sensor buffers against changing salt levels in the soil. However, when salt levels exceed 4 dS/m or more, the calibrating shifts. Sensor will read blue for a longer period (when they should have turned green). In other words, high salt levels cause the colour changes at greater suctions.

Do not allow the Chameleon Card to get wet.

If the sensor reads red with no wire connected, remove from the cover, clean and dry the gold leaves with a tissue on both sides.

The battery should last for 1000 readings. When the LED flashes red, the battery needs to be replaced. Battery: Disposable CR2032 watch battery.

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