Losses of $600/ha through faulty irrigators

By Rick Bayne

South Australian farmers could save money and improve productivity by fixing or replacing outdated irrigation equipment and making sure they have a good start to the season.

A catch can survey of farmers in south-east South Australia has shown that systems not irrigating well face a production loss of $150 – $600 per hectare per year.

With the state’s power prices the highest in the nation, a field day conducted by DairySA in October has highlighted how technology can cut the costs.

The catch can survey found most farmers are operating with less than optimal equipment.

The Smarter Irrigation for Profit field day held at Donovan’s Dairy near Mt Gambier showed that measurement is the key to improving irrigation performance.

Tim Powell from Integrated Irrigation told the field day that a catch can test on pivots found most were underperforming, resulting in significant potential losses of pasture productivity.

In some cases of overwatering, potential water and energy savings could be made by improving the pivot. On the other hand, in instances where the pivot is under watering, extra water and energy may be needed to irrigate effectively to achieve additional pasture.

The tests involved arranging hundreds of rain gauges lined up under the pivot to see how much comes from every sprinkler.

Mr Powell said tests on newer pivots verified that sprinkler and pumping systems were very good and producing even watering.

However, most farms don’t have newer pivots.

“Older pivots show up quite a few different things; over time sprinklers wear out and need to be replaced,” he said.

“We found a lot that need to be upgraded. In the Limestone Coast area there would be a good few hundred that need to be upgraded,”

The testing process included a cost analysis to calculate what poor irrigation patterns cost in productivity.

“For systems not irrigating particularly well it shows a production loss anywhere between $150 to $600 per hectare per year,” Mr Powell said.

Facing the prospect of less production, most farmers want to do something about it. “No-one wants to lose productivity,” Mr Powell said, “but most of the time it comes down to what it costs to fix it and how quickly you can get that into your budget.”

Mr Powell said the payback period varied depending on what’s wrong with the system. “The most common thing they need to do is replace sprinklers and regulators and that would be a payback within 12 months.”

He urged farmers to have tests done before replacing pumping equipment and to regularly measure soil moisture levels.

Mr Powell said farmers could use the data of soil moisture tests

“With power costs you don’t want to be wasting anything. Soil moisture tests help because you can see what your soil is doing and whether you can hang out for the cheaper power.”

The field day heard from researchers and presenters from the commercial sector showcasing a range of technologies.

John Hunt, Allendale East, James Mann, Wye and Tim Powell, Integrated Irrigation.

Senior Research Fellow from the University of Southern Queensland’s National Centre for Engineering in Agriculture, Dr Joseph Foley and Nigel Fleming from SARDI, along with Phillip Marks from Balanced Ag Consulting showed a range of soil moisture monitoring technology and introduced the technologies that would be used to measure biomass at this year’s focus pivot, Pivot 6 at Donovan’s Farm, for further research.

Dr Foley stressed that monitoring both water meters and pivot pressures can assist farmers to identify irrigation performance issues to ensure irrigation is optimised.

“Through using these technologies farmers will have the ability to better match irrigation applications to the crops’ needs,” he said.

Dr Foley said it was important that farmers objectively measure rather than rely on gut instinct and encouraged farmers to select a measurement tool that’s suitable for their farm and then to learn how to properly use it.

He said that getting irrigation right at the start of the season was essential. “We want farmers to understand there’s production loss if they’re not irrigating appropriately, and that often occurs at the start-up after rainfall or wet periods.”

The National Centre for Engineering in Agriculture is installing VARIwise cameras on the focus pivot which provide estimations of pasture growth rates. They provide the capability to report back the pasture dry matter per hectare from the machine itself. The cameras are suspended on the centre pivot and the images are analysed robotically through vision analysis software.

Farmer James Mann has found that start-up at his property ‘Donovans’ has been better matched to pasture needs as a result. With pasture yield penalties in the order of 105 kg/DM/ha/day of delay in starting irrigation, it is hoped that this improvement will be reflected in productivity at the site over the season.

Nigel Fleming, Research Scientist, Soil Fertility and Nutrient Movement, SARDI, and Dr Joseph Foley, Senior Research Fellow (Water Engineering & Irrigation), National Centre for Engineering in Agriculture.