AUTONOMOUS irrigation tech developed by a University of Southern Queensland (UniSQ) agricultural engineering team is reducing water use by up to 15 per cent for each irrigation in cotton.
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Better still, it can now be operated remotely, with scheduling recommendations sent by text message to a grower who can accept them by tapping on a hyperlink.
But it's the data about water use efficiency and infiltration that most excites Andrew Greste, operations manager at Waverley, west of Wee Waa, who has been involved with the research along with Waverley owner Steve Carolan since 2015.
"I see some real benefits from this work," Mr Greste said.
UniSQ Associate Professor Joseph Foley said the research, with Dr Malcolm Gillies and Dr Alison McCarthy, in surface irrigation optimisation - ensuring water was applied to the right place, at the right depth, and at the right time - had been ongoing since 1999 in various forms.
They launched IrriMATE, which measures water on and off fields and evaluates irrigation efficiency, and carried out more than 800 surface irrigation assessments on farms, mostly in cotton.
By 2015 they were ready for a reset, looking to move beyond decision support systems towards autonomously controlled or autonomously optimised irrigation systems.
"Rather than analysing an irrigation event that just occurred, and then making recommendations about what you might do next time, we embarked on this program of activity to have sensors in the field interact directly with a server-based system for the model, called SISCOweb," Prof Foley said.
"One of the things that had occurred in that period between 2011 and 2015 was the ready availability of remote controlled irrigation gates that could be actuated from smart phones or by a timer. We wanted to incorporate our optimisation technology with that new hardware in a cloud-based system to provide real time optimisation."
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Under the Smarter Irrigation for Profit program, a 108ha trial using small pipe through bank was set up at Waverley in 2015, and by 2018 another 2100ha had been converted from manual siphon irrigation.
Prof Foley said testing of SISCOweb and the crop modelling tool VARIwise at Waverley and other sites had achieved a 10-15pc water saving by reducing deep percolation and minimising tail water.
Under the system, a series of advance sensors sends information to the server about how quickly water moves along the furrow. It calculates the timing of gate closure and sends an SMS to the grower with estimates of the best cut-off time.
In some scenarios, the recommended run time was two hours shorter than usual, while in about 20pc of cases the intense monitoring had shown standard practice was causing under-irrigation when soil infiltration characteristics had changed during the season.
The SMS can now include a link which the grower taps on their phone and the system automatically reprograms the gate closing time, which has a cascade effect so when one gate closes, the next one is opened.
Prof Foley said the systems weren't prohibitively expensive, since most of the cost was from earthworks associated with installing a small pipe through the bank system.
Autonomous systems cost less than $800/ha, compared to about $500/ha for a manual system that uses a winch to open and close one gate replacing up to 170 siphons, he said.
Mr Greste said they had already reduced the labour associated with irrigating by converting to small pipe through the bank and he was keen to see the tech commercialised so more growers can access it.
"A lot of the remote monitoring has been hugely beneficial in terms of labour efficiency, as well, you haven't got three or four fellas running around just checking levels," he said.
"One person can be operating a machine somewhere on a tractor and monitoring irrigation at the same time. But being able to get more objective about irrigation timing and amount of water, getting more specific about the flow rates that are required to meet our targets, that's probably more important for me than being able to do the irrigation change remotely."
Mr Greste said one of the most eye opening findings from the research was the changes in infiltration characteristics during the season - infiltration generally slowed during the season, but not always.
"On our grey cracking clays typically, they used to tell us that the quicker you can get water from one end of the field to the other and push it out the tail drain, you'll reduce your waterlogging, and you'll save a lot of water," he said.
"You can do that, but it also has a big impact on your crop yield. Where we were doing that we were seeing reduced yield because the water needed time in-furrow for it to actually infiltrate into the profile. I wouldn't say our water use has declined, but our bales per megalitre have got better."
Mr Greste was careful to point out that what suited the 3600ha of irrigated crops at Waverley might not suit all farmers or all irrigation systems.
"Whenever I get a visit, or we host a field day, I make sure that people are aware that this is what we've decided, and this suits our circumstances," he said.
"Every farmer's different, everyone's layout, soil types, the slope across their farm is different. So what suits us, you can't always directly transfer that and have it work in someone else's system."
Prof Foley said preliminary trials had started to see if the optimisation process could also be used in bankless surface irrigation systems.
The Cotton Research and Development Corporation (CRDC) and UniSQ started the commercialisation process in April 2020, but it has been held up by the pandemic.
The project was supported by funding from the CRDC, Dairy Australia, UniSQ and the Australian Government as part of the Rural R&D for Profit program.
