Many cotton farmers are considering the switch from siphons to bankless channel irrigation systems in an effort to be more water efficient, but some are still questioning the effectiveness of these new systems.
This is a question that the cotton industry's extension program, CottonInfo, is hoping to unpack through an extensive on-farm trial at Craig Saunders' property, Thuraggi Overflow, St George.
The trial is funded by the Cotton Research and Development Corporation and Smarter Irrigation for Profit Phase 2 (through the Australian Government Rural R&D for Profit Program), and supported by Padman Stops, CottonInfo Team, Gwydir Valley Irrigators, NSW DPI, University of Southern Queensland and Glenn Lyons.
The property is one of many operations where growers have adjusted their irrigation systems to address the challenges of labour resourcing, energy use, management efficiency and water use efficiency.
Grower Craig Saunders said the journey began when he saw shocking data from a basic furrow irrigation evaluation in 2005.
"I was a siphon irrigator who thought he was doing a good job, but that wasn't the case," Mr Saunders said.
"We realised that although we have clay soils, deep percolation resulted in significant water losses, so we went on to try cane fluming, pivots and pipes through the bank to improve water and labour efficiencies.
"The journey was long and arduous. We've had a lot of failures on the way, until in 2017 when we tried the GL (Glenn Lyons) bay design in our longest, flattest field.
"It was transformed into our highest yielding and most water efficient field."
There has been limited research into the irrigation performance of these designs, but the irrigators who are using them have seen improvement in water use efficiency.
The system at Thuraggi Overflow is an example of the tailwater backup siphonless design developed by consultant Glenn Lyons: a concept that minimises the amount of soil needed to be moved and uses existing supply and tailwater systems.
The collection of data on soil water use, water applied, rainfall and irrigation uniformity will enable the team to calculate the irrigation water use efficiency and more importantly, the gross production water use index.
CottonInfo Technical Lead for Irrigation Ben Crawley said the trial would also investigate the potential to apply surface irrigation technologies, such as SISCO, to the tailwater backup siphonless design to improve irrigation optimisation.
"This information will help determine where there have been water savings and identify where further savings may be possible," Mr Crawley said.
"The results from the trial are expected to help growers make decisions around implementing and operating a siphonless backup system.
"The trial will also look to build on other trials and grower experience that already exists by applying a robust and independent scientific method and measurement of a siphonless system's performance and optimisation."
The equipment has all been installed despite Covid outbreaks and border closures, with data collection underway.
Also read: St George cotton farmers on a mission
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