Dry or apply

What irrigation option works best in the Macalister Irrigation District over summer?

by Robyn McLean, GippsDairy and Sarah Collier, GippsDairy

Background

Drying off or continuing to irrigate over summer has been one focus at the Cobains Dairy Optimisation Site (Oakdale Park) of the Smarter Irrigation for Profit Phase 2 (SIP2) project. With decreased confidence in the reliability of water allocations, and the need to be more efficient when irrigating, the project responded to local dairy businesses wanting to learn more about the possible opportunities and impacts of drying or applying over summer.

Is it more profitable to use allocations in spring and autumn, and what are the flow-on effects of drying or partially drying over summer to pasture production in the autumn? Both questions are currently being investigated more closely this irrigation season.

Trial

With the SIP2 project now in its third and final year, a trial has been implemented on the Dairy Optimisation Site (2.5ha divided into 3 equal bays) to investigate how well the pasture responds to being dried off completely, partially, or not dried off at all. Bay 1 was dried off in mid-December, bay 2 in mid-January, and bay 3 will continue to be irrigated through the season. Impact to dry matter across the three irrigation treatments is being monitored using pre and post grazing plate meter readings and pasture cuts, as well as satellite NDVI technology (Pasture. io) to determine growth rate (kgDM/ha/day). At the end of the irrigation season, measurements will continue so that the project can determine the pasture response of each bay irrigation treatment after autumn rain. A cumulative comparison analysis of growth rate versus water use/cost across the three will be prepared.

Cobains Site

Garry Cook and Colleen Laws, who manage Oakdale Park, came on board in 2018 and have been part of the SIP2 project since they started. Garry believes in innovative farming practices and being proactive rather than reactive. “Water is going to get tight, and you have to have alternatives. We catch one hundred percent of our water, but we can only re-use it over twenty percent of the farm,” he said.

They have seen great success in drying off areas of the farm in previous years and were one of the only farms drying off in the MID when they began in 2018. Garry is looking forward to potentially seeing data that supports his innovative thinking at the end of this project.

There have been bonuses too during the project. This season has undoubtedly been a favourable one, with Garry only needing to irrigate once leading up to Christmas. “This season has been fantastic, last season we were irrigating the farm between five and nine days. It is going to be interesting to see how the rest of the season pans out,” he said.

Improving pasture quality has been a high priority for Garry since moving to the farm in 2018. Heavily topping pastures, spreading effluent across the farm and applying fertiliser have been his focus. “Due to increased fertiliser prices and unpredictable weather, alternative solutions may need to be considered, which is one of the reasons I’ve enjoyed being involved in the project,” he said.

The Pasture.io tool has helped Garry monitor pasture performance during the project by determining pasture cover and growth rates from satellite technology. Ground-based measurements have helped to validate this technology and provides greater detail on how his irrigation decisions are impacting production outcomes. “I’m more assured about how I’m tracking with the data at hand,” he said.

Garry likes to make sure every little bit counts when it comes to irrigation. He routinely checks the soil moisture status of the bays before irrigating using the separate moisture probes and the IrriPasture webapp, introduced to him through the project. Trialling different methods to see which one is most effective has paid off. “It’s been a fantastic year to do it,” he said. “Data from IrriPasture and the moisture probes were particularly useful in deciding when to irrigate.” These tools have helped to take the guesswork out of knowing when to irrigate.

If you would like to know more about the project, the SIP2 site coordinators are:

Billy Marshall
Agriculture Victoria
Phone: 0418 718 527
Email: billy.marshall@agriculture.vic.gov.au

Robyn McLean
GippsDairy
Phone: 0447 379 173
Email: robyn.mclean@gippsdairy.com.au

The Smarter Irrigation for Profit project (SIP2) is supported by funding from the Australian Government Department of Agriculture Water and the Environment as part of its Rural R&D for Profit program, and Dairy Australia.

To find out more about the project, and find the tools and resources that will help you get the most out of your irrigation, visit Smarter Irrigation for Profit.