Landcare's Kerri Robson and Damien Gerrans listen to Dale Grey explain the intricacies of climate and weather modelling.
Two leading scientists have updated farmers on the current improvements in soil moisture data collecting and weather and climate modelling.
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Agriculture Victoria agronomists Dale Grey and Dale Boyd spoke at the Gecko Community Landcare Network (Gecko CLaN) on Thursday, November 30 at the Benalla Showgrounds.
The two agronomists often team up to travel in regional areas to keep farming communities up to date.
Mr Grey told the audience of more than 30 that farm decisions should not be based only on autumn predictions of El Niño.
He said such predictions of El Niño did not eventuate in 2014, 2017 and 2019, but did only in 2015 and 2023.
“That decision-making is fraught with danger as sometimes El Niños happen and sometimes they don’t,” Mr Grey said.
“Decisions in autumn should be made on the things you know and can measure such as soil moisture, whether you have had a break and feed and water supplies.”
Mr Boyd researches the effectiveness of soil moisture monitors across the state and is helping AgVic collate a statewide long-term moisture database.
“We ask what are the ‘known’ knowns so that soil moisture level can be monitored, measured and modelled,” he said.
“And a farmer’s own soil sample is the best possible reference point, and we need to make others the reference points for the state for long term data.”
Mr Boyd said the dataset was useful for modelling crop growth in response to various rainfall patterns.
“When you look at the carryover moisture from last year, because (the rain) continued to come through October and November, it was surplus to crop demands, as was that for this year’s winter crop.
“And with moisture being low decile (moisture scale to 10) through this August and part of September, that’s when the crops want to grow and use a lot of water.
“They had to rely on those deeper moisture levels just to continue.”
Mr Grey told Country News that the current El Niño oscillation in the south Pacific Ocean would most likely last only one year and explained that El Niños were typically one-year events.
“It’s easy to get multiple La Niñas in history but very difficult to get doubled-up El Niño.
“El Niño is a reverse of the normal system in the Pacific, whereas La Niña is an accentuation of the normal system.
“It is much easier to keep something accentuated longer than reversing it.”
Mr Grey said climate and weather models varied in accuracy during different times of the year and relied on mathematical probabilities.
“To read the climate models and how they work, understand that it is (based on) probability.
“The models don’t tell you what will happen, and during different times of the year they have varying accuracy.
“Generally, their accuracy in autumn is no good or not as good as in the middle of winter or spring.”
Mr Grey said the sophistication of the models meant they were not designed on past data.
“They use mathematics and physics, and they will then get tested on past data, but the model itself is not.
“That’s how they are tested for their accuracy, to check it against what actually happened and then do that for a heap of months and other years and then you think well this model is good for predicting for spring but not for summer, or vice versa.
Gecko CLaN executive officer Kerri Robson said the two presentations were another offering for any community members to attend.
“Whatever we do is open to anyone; it’s not just within our local network,” Mrs Robson said.
“The more we can share, the more the Landcare community can build.
“And community is not just your local Landcare group, it could be the CFA who have members there.
“But Landcare is just another option to come together and learn from each other.
“Sharing knowledge is the thing.”
The statewide, long-term soil moisture map being developed by AgVic.
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