Farm trials show way forward for smarter irrigation

A three-year project called ‘Smarter Irrigation for Profit’, led by the Tasmanian Institute of Agriculture (TIA), has demonstrated how major improvements in irrigation efficiency can be achieved with relatively minor tweaks.

Project leader at TIA, Dr James Hills, said the main aim was to use less energy and water, and grow more pasture, for each megalitre of irrigation water applied.

“Our objective was to increase on-farm profits and sustainability in the Tasmanian dairy industry,” Dr Hills said.

“We monitored current practices and built on previous research about automation and precision in cropping industries like cotton, rice and sugar, to transfer those learnings to dairy in Tasmania.”

Over three irrigation seasons from 2015 to 2018, the project collected data on water usage, energy consumption and pasture production from five commercial pivot irrigated sites on different soil types across northern Tasmania, at Cressy, Montana, South Riana, Sisters Creek, and Rocky Cape.

Using the data, the project team worked with the farmers involved to make improvements to their irrigation practices, and then monitored each site to measure the effect of those changes.

Dairy farmer Rob Bradley (pictured above) was more than happy to host one of the trial sites in the Smarter Irrigation for Profit project.

“Did TIA twist my arm? No, I was always keen,” Mr Bradley told a recent field day at his farm near Cressy.

“We’ve had an enormous amount of research done on our farm, which has been enormously valuable to us and hopefully to others as well.”

“We’ve had people here measuring pastures every week through the growing season, soil moisture monitors put in over the farm, a whole electromagnetic soil-water map done, and drainage maps done, all for the project, which was fantastic.”

Dr Hills said that irrigation was often not scheduled at a frequency to keep available water in the pasture root zone.

The result is known as the ‘green drought’, where pastures stay green due to irrigation, but growth rates are significantly less than they could be.

“Scheduling irrigation to keep adequate water in the soil’s root zone is really important to achieve maximum growth rates,” he said.

Rob Bradley said that changing the way his irrigation was scheduled led to a significant increase in pasture production of more than 200 tonnes under his 117 hectare pivot, which also led to major savings on feed costs.

“We’re putting the water where it needs to go, we’re using less power to do it, and we’re growing more grass,” he said.

Mr Bradley runs several centre pivots over undulating land with various soil types, so variable rate irrigation (VRI) technology was a potentially useful option to try.

Across two of the trial sites, the introduction of VRI technology led to a reduction in water use of between 29 and 34 percent.

Information from the project also enabled farmers to save thousands of dollars in annual energy costs by replacing their pumps and motors with ones better matched to their irrigation requirements.

Testing of automation showed potential for computerised systems to adapt in real-time to weather changes, without growers having to manually take measurements of pasture or update irrigation maps.

Dr Hills said that now the project has concluded, he hoped the work could continue through a series of demonstration farms linked to local groups of farmers and service providers.

“Over the last three years, our project has showed we need to boost our understanding of what is required for irrigation systems to work well, from the appropriate hardware through to soil and crop constraints,” he said.

The ‘Smarter Irrigation for Profit’ project is supported by funding from Dairy Australia, TIA, and the Federal Government's Dept of Agriculture and Water Resources as part of its Rural Research and Development for Profit program.

This article appeared in Tasmanian Country on 8 June 2018.

Published on: 08 Jun 2018 5:12pm