New line in irrigation making the Grand Final on The New Inventors

18 August 2011

A remarkable irrigation system that uses salt water and the natural energy produced by plants made the Grand Final of last night's episode ofThe New Inventors.

It was the brainchild of Bruce Sutton, Honorary Professor in the University of Sydney's Faculty of Agriculture, Food and Natural Resources, and colleague Greg Leslie, Associate Professor at the School of Chemical Sciences and Engineering at the University of New South Wales.

The Rosdi irrigation system lets plants draw water through salt filters in irrigation pipes at their roots, using the tiny amounts of energy naturally created by evaporation at their leaves.

The system is "a buried irrigation line, similar to existing sub-surface irrigation lines, but made out of a reverse osmosis membrane," explains Professor Sutton, who is also a former Chair of the Academic Boardat the University of Sydney.

In The New Inventors episode aired last night on the ABC, Associate Professor Leslie explains why the system only requires a constant low flow of water.

"A conventional membrane would use a big pump that would push the water across, in this application the evaporation of water through the plant leaf creates a suction," he says.
Professor Sutton adds: "The plants draw from the irrigation just what they need and no more. It's an ideal technology for small holder peasant farmers in developing countries."

The system will allow farmers to use saline water, including brackish water, not only during protracted droughts, but also as an alternative to increasingly scarce fresh water supplies. At the same time the Rosdi system counteracts the adverse impacts of salt accumulation in the soil.

The irrigation tube's diameter is large enough - between two to five centimeters - to allow water to flow without the usual problems of internal fouling of the membrane by silts, clays and suspended solids that are common in conventional reverse osmosis systems.

Because the plants only draw from the water source the exact amount of water they need, the system will be highly efficient, "using up to 90 percent less water than existing systems", Professor Sutton says. It can also be manufactured for a similar price range to currently available drip irrigation systems.

Professor Sutton and Associate Professor Leslie were the recipients of the 2010 Eureka Prize for Water Research and Innovation.

Contact: Ms Katynna Gill

Phone: 02 9351 6997

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