Dr Ian Goodwin is a researcher at the Tatura SmartFarm. His project is exploring how farmers can optimise their water use during times of drought.
Photo by
Nicholas Spandler
For decades, Goulburn Valley orchardists have looked to the soil or the sky to judge when their crops need a drink.
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But in the face of increasingly harsh droughts and tightening water supplies, that kind of guesswork has become a high-stakes gamble.
Growers are often forced into tough decisions: continue irrigating and risk financial strain, or cut back and risk long-term damage to their trees?
A new research project led by Dr Ian Goodwin is aiming to remove that uncertainty.
Funded through the Federal Government’s Future Drought Fund and Agriculture Victoria, the project ‘survival signatures’ is focused on identifying exactly how much stress fruit trees can handle before their productivity is compromised.
The goal is to give growers the tools to keep trees alive through drought, even if it means sacrificing the season’s crop.
“At some point, if a tree becomes too stressed, you won’t recover production the following year,” Dr Goodwin said.
“What we’re trying to do is find that tipping point.”
Blush pears at the Tatura SmartFarm’s pear orchard. Dr Goodwin said the water-stressed plants rushed to produce fruit after the rains in march, resulting in these poor-quality pears.
Photo by
Nicholas Spandler
In extreme conditions, that decision can mean deliberately letting go of a harvest to protect future seasons.
“Can you basically park your trees for this year, give up on your yield … but recover them next year with the absolute minimum amount of water?” he said.
Rather than relying on indirect indicators like soil moisture, the project is measuring stress directly within the tree itself.
“We’ve gone right to the source of the stress … directly measuring how stressed the tree is,” Dr Goodwin said.
To do this, researchers are testing two types of sensors: dendrometers and microtensiometers.
Dendrometers are attached to the outside of the trunk and measure tiny changes in tree diameter as it shrinks during the day and expands overnight.
These daily patterns provide a clear picture of how a tree is coping.
Healthy trees recover each night, but stressed trees begin to show a gradual decline.
“As the tree gets stressed, it starts to go backward and doesn’t recover,” Dr Goodwin said.
Microtensiometers, on the other hand, are inserted into the tree to measure water tension, essentially how hard the tree is working to draw water through its system.
“The more stress it gets, the harder it is to pull that water through … it’s like the tree’s working harder,” he said.
The Tatura SmartFarm is a hub for Agriculture Victoria’s research in Victoria.
Early findings suggest dendrometers may offer the most practical solution for growers.
They are relatively inexpensive, simple to install, and remain reliable even under extreme stress, unlike microtensiometers, which can struggle once conditions become too severe.
The research is about a year into a five-year program and is being carried out across nectarine, pear and almond orchards at Tatura and Mildura.
The project also involves collaboration with another study being done by the University of Melbourne’s drought hub, using aerial monitoring.
Using aircraft fitted with specialised cameras, researchers are exploring alternative methods to assess tree stress across entire orchards from above.
The study used dendrometers, the metal brace used to measure the tree diameter, and microtensiometers, the small wire plug that is drilled into the tree to measure internal water tension.
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Contributed
Ultimately, the team hopes to map a clear relationship between stress levels and future yield.
The expectation is that productivity will hold steady up to a certain point, before dropping sharply once that threshold is crossed.
Pinpointing that moment could be a game-changer, allowing growers to apply just enough water to preserve next year’s crop.
The research comes at a critical time. Climate models suggest droughts are becoming more frequent and unpredictable, while water availability is tightening.
For growers, the outcome could provide a new level of confidence in decision-making during tough seasons.
Instead of relying on instinct, orchardists may soon have clear, science-backed thresholds to guide them.
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