CSIRO’s next big thing – a spray-on membrane to stop soil moisture loss

Successful research trials in NSW’s Murrumbidgee Irrigation Area near Griffith are about to be scaled up for commercial evaluation in paddocks growing melon and processing tomato crops at Finley and Mildura on the Victoria-NSW border.

Current research on the biodegradable polymer membrane is focused on refining a product applied direct to the soil to limit evaporation as crops are planted, and lasting up to four months.

Other variations on the same theme are being considered to cover paddocks for a year or more during fallow or production phases.

Researchers also want to explore options to use a much hardier version of the sprayed-on membrane to line irrigation water channels and storages prone to seepage losses.

For crop use, the polymer is coloured black to restrict sunlight penetrating the membrane and promoting weed growth between planted rows.

Project leader and internationally recognised soil physicist, Keith Bristow at CSIRO in Townsville said the membrane effectively worked as a weed mat and moisture retainer, not unlike a sheet of black plastic spread on the ground, but with a far shorter lifespan.

He said said the aim was to provide a temporary barrier to improving the amount of soil water available for plant growth until a dense leaf canopy grows to shade the ground and naturally reduce evaporation and weed activity.

The opportunities for better crop water use efficiency, crop yields and farm profitability were exciting.

“We’ve got people queuing up with ideas about all sorts of potential applications,” he said.

Talks were also underway with a range of potential partners.

“We’d like to think it could be ready for the market in 18 months to two years, depending on how our next stage of trials progress,” he said.

Applying the polymer was expected to be no more difficult than using a conventional agricultural spray rig for herbicide or fungicide applications.

The past past four years’ trials had satisfactorily used portable hand-held spray kits bought from farm supplies and hardware stores.

Dr Bristow said the spray process did not completely seal the paddock surface with the membrane, particularly where clods of earth, sticks or wheel tracks could create gaps.

“But that’s not bothering us,” he said.

“Holes allow oxygen to enter the soil – we are very conscious of protecting soil microbiology.”

While likely to be used in numerous broadacre cropping situations, the CSIRO was deliberately fine tuning its “scaling up” trials in high value field crops next month, to ensure the relatively expensive input costs involved at this point were covered by improved yields and crop returns.

Various climate zones will be tested to assess how quickly the polymer degrades in different  soil, temperature and rainfall conditions, while the impact of any fine residue eaten by livestock is also being studied.

Perth-based science director with CSIRO’s agriculture and food division, Michael Robertson, told last week’s National Farmers Federation Congress the industrial-based polymer product could potentially contain herbicide as a weed control option or beneficial nutrients and enzymes.

The new development was one of several “next big things” offering significant productivity improvement or value-added potential now emerging from CSIRO, which spends $350 million about half its total annual budget on food and agricultural research (including climate and biosecurity).

Among the fruits of research projects now hitting commercial release stage, or close to it, was the world’s first gluten-free beer, brewed in Germany using malt derived from a CSIRO-bred gluten-free barley grown in Australia.

“Gluten-free is an active food research opportunity for us service because a surprising number of people around the world now avoid gluten in their diet, even if they are not gluten intolerant,” he said.

Also in the cropping space, a new genetically modified canola variety high in beneficial omega-3 fatty acids, but low in potentially undesirable fats, was set to make a huge impact on human nutrition and the aquaculture sector, which currently relies on fish meal to build omega-3 levels in fish diets.

CSIRO teamed up with seed breeder Nuseed and the Grains Research and Development Corporation in 2011 to develop the same quality long chain omega-3 oils in canola as are found in fish, and at commercially viable levels.

The partnership is close to releasing a variety to be grown commercially.

Other crop research wins include fixing the yield gains achieved with hybrid vigour when plant varieties are crossed so future lines permanently retain the crossbred plant’s vigorous yield characteristics.

Initial fixed vigour developments with corn varieties had focused on helping yields in developing Africa.

In the livestock field CSIRO has patented a “virtual fence” which keeps real cattle within an unfenced area by emitting a mild electric shock once they cross an unseen line in the paddock.

Stock wearing CSIRO’s electronic hardware learn to avoid pushing beyond the virtual fence line because an audio alarm activates warning them.

“They’ve quickly learnt the audio cue is associated with the prospect of an electric shock,” Dr Robertson said.