A balanced delivery

Remote sensing and cell phone technology deliver water management information

Richard Soppe

Irrisat-SMS combines satellite data, information from local weather stations and feedback from farmers to deliver daily, detailed irrigation scheduling advice via SMS.

Irrisat SMS is an irrigation water management service that uses high-level technology to deliver information to farmers. Developed in New South Wales, Australia, by CSIRO Land and Water, the system converts data from satellite images and weather stations, and sends this information as an SMS to farmers’ cell phones. This tells them exactly how long they should run their water pump in order to replenish the water delivered to the crops by their irrigation system.

The service sends one SMS per day to each subscribed farmer. As part of the subscription, farmers are asked to send back information to the system, including the actual time their irrigation system has been running that day, and data about any rainfall on their farm. A central computer keeps track of each specific farm’s water use.

The system collects satellite images throughout the season to monitor crop development on the farms that have signed up for the service. The light reflected from the vegetation and land is captured by sensors on board the satellites and converted using remote-sensing software to show crop vigour. This can indicate the rate of evapotranspiration from a crop.

Weather stations in the farmers’ region collect data on temperature, wind speed, solar radiation and relative humidity, and automatically deliver the data to the central Irrisat-SMS database. The weather information, combined with the evapotranspiration data, determines the conditions for actual water consumption by the crops on a particular farm.

The daily water consumption of a crop is usually expressed in millimetres (or inches) of water, but that does not mean that farmers know immediately how much water they need to apply to their fields. To provide farmers with precise, customised information, Irrisat-SMS researchers must visit and evaluate each farmer’s irrigation systems.

For drip irrigation, which is extensively used in the service’s test area in New South Wales, researchers used catch-cans and stopwatches to measure the actual water-flow rate through a number of drip emitters randomly selected in a field. The catch-can collects all the water that flows out of the drip emitter for a specified length of time. These data provide the farmers with information about the uniformity of water flow through their drip system, and tells them if the system needs maintenance or replacement. The data also inform farmers about the actual application rate of their irrigation system, i.e. how much water is delivered to the plants. The application rate is entered into the Irrisat-SMS database, and is then used to calculate the time that the pump needs to run to apply exactly the right amount of water consumed by the crop. It is this information that is sent daily to the farmers via SMS.

Adaptable tool

Irrisat-SMS has already delivered irrigation advice to farmers growing many different types of crops in a wide variety of conditions. Some crops and situations require extra work to gather the right information to ensure that farmers receive the maximum benefits from the service. The database has, therefore, been developed to be flexible and take special considerations into account.
In the Griffith area of New South Wales, for example, the farmers growing grapes for red wine have different irrigation needs to those growing grapes for white wine. White grape growers try to maximise their production, while the red grape growers manage their irrigation system to optimise quality as well. The red grape growers use ‘managed stress-induction’ techniques in the second part of the growing season.

The Irrisat-SMS database contains information on the target crop, and provides adjusted crop water requirement information when possible. Adjustments were also needed for periods early in the season, when the canopy cover of the grape leaves was low, and ground cover of grasses, weeds or inter-row crops affected the crop-vigour indications from the satellite data.

Cotton growers in Australia used the system for several different fields in the same farming enterprise. Each field requires separate irrigation information, so to avoid an excessive amount of messages sent to a cell phone, the developers produced a system to deliver the same information on the web – Irrisat-Web. In this version, the farmer is presented with a graphic visualisation of their fields, the water balance information, and the cumulative run-time required to replenish the water used by the irrigation system.

The web version is available to all farmers signed up to Irrisat-SMS, but many do not use it; internet access is very limited in some rural areas of Australia, while cell phone coverage tends to be better. Farmers in another of the service’s test areas, close to Sydney, preferred to use Irrisat-Web. These users had better access to the internet, but many were also hobby farmers with small fields. They wanted to access the information at a time that suited them, rather than have an automatically scheduled SMS delivered to their phone early every morning.

The main challenge for this group of farmers was in the farming system, which often included a large variety of non-native vegetables, growing intermixed and in different stages of crop development. Most of the vegetables were shallow rooted, thus having a limited soil-water storage capacity, which also required a high frequency in irrigation. Since a water-balance approach – replenishing the water used for irrigation on the previous day – would require a lot of feedback from the farmers, a slightly different approach was necessary.

The effort involved to send all this data back to the system would probably outweigh the benefits, so Irrisat-SMS was adjusted to send farmers an SMS with a maximum daily water requirement for the specific crop area.

Personal connection

Throughout the development process, the Irrisat team collected detailed survey data from all the subscribed farmers. Most farmers reported several benefits in the delivery of irrigation advice via SMS. Several long-time growers see the service as a confirmation of their irrigation scheduling based on years of experience. Others, especially growers that have recently changed technology or farming approach (from furrow to drip irrigation or from vineyards to orchards) use the information as a guide and follow the advice as closely as possible. A third group use the information as a benchmarking tool, as Irrisat-Web offers anonymous comparison with other growers in the same sector.

It is well known that the total available seasonal water and crop yield are related; a lack of water usually results in lower yields. However, irrigation is only one aspect of any farming enterprise and other factors must be considered, including crop establishment, pest and disease management, the availability of farm equipment or labour at the right time in the season, and crop commodity prices.

Water is, therefore, not always the determining factor in crop yield. Not all growers followed the advice provided through the Irrisat-SMS service. Some deliberately under-produced due to low crop prices or a lack of guaranteed contracts for the crop, while others were not able to follow the advice due to a limited water supply on the farm (for example, farms irrigating from a farm dam, which is wholly dependent on rainwater collection during the season).

The Irrisat-SMS service has, so far, only been applied in irrigated areas in Australia, although there are plans to introduce it in some Asian countries. The use of cell phones to deliver irrigation information is especially suitable for ACP countries too, where cell phones are widely used. Cell phones have developed into a highly accessible tool worldwide, and provide the gateway between online systems and offline farms.

The satellite input used in the Irrisat service, combined with automated weather station information, allows regular, remote monitoring of rural areas. Contact and feedback from the user appear to strengthen the tool, and provide farmers with a flexible irrigation management system tailored to their precise needs. Experience after several years of trials indicates that simple phone messages, based on information from high-tech sources, have a great potential for farm and water extension services throughout the world.

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Richard Soppe is an irrigation scientist with CSIRO Land and Water ( www.clw.csiro.au)

30 August 2010

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