Changing weather in the western wheatbelt
GroundCover™ Issue: 101 | Author: Sarah Cole
Managing climate risk is an ever-changing strategy. This report looks at how the past three years have changed two Western Australian Climate Champion grain growers’ tactics. We also introduce the GRDC’s newest Climate Champion participant, Peter Horwood from Mingenew, Western Australia.
Farm: ‘Riverside Ajana’
Region: Ajana, north-east agricultural region, WA (110km north of Geraldton)
Commodities: wheat and lupins
Farming area: 12,000 hectares (8000 cropping)
Average annual rainfall: 308mm
Since droughts in 2006 and 2007, and a plentiful crop in 2008, Fleur Grieve’s family property has had a run of average years since 2009.
In 2011, despite patchy outcomes for the rest of the state, “we got rain at the right time and the crop ended up being good,” Fleur says. She adds that the season breaks have been later and winter storms have become more extreme.
Management practices such as no-till, retaining stubble and tramlining have continued to benefit their cropping enterprise, and dry-seeding remains the norm. Their yield of one to two tonnes per hectare has also stayed steady.
Fleur has seen more chemical fallowing in her area, which is used as another way to extend crop rotations. After a canola/wheat rotation, which can accumulate diseases or weeds, croppers use a chemical fallow year to prepare a paddock for the following year.
“You’ve got the input cost of paying for the chemicals, but the benefits are that the following year you generally get a cleaner crop. It also hasn’t had a crop on it, so sometimes the production is better in terms of fertiliser uptake the following year,” Fleur says.
Those benefits, she says, can make up for the production lost in the chemical fallow year and cost of spraying. “It works and is useful for us.”
The Bureau of Meteorology (BoM) is still the main source of forecast information. However, for Fleur’s region, most growers consider long-term forecasts too unreliable to base major cropping decisions on.
“From my perspective, I don’t see farmers having enough comfort with any long-term forecasting yet to change decisions about dry seeding, for instance,” Fleur says.
She also believes that although many growers are using the internet more, the myriad sources available are sometimes conflicting and confusing.
Region: near Badgingarra, WA (200km north of Perth)
Commodities: wheat, barley, canola, lambs and hay
Farming area: 3200 hectares
Average annual rainfall: 300 to 650mm
With an annual rainfall of 300 to 650 millimetres, John says the upper range of rainfall is dropping, and temperatures are getting warmer in the West Midlands.
“The past five years have been pretty dramatically dry in general. We rely on north-west cloud band events, but the fronts just aren’t making it up.” John says.
“The whole wheatbelt [in WA] is seeing the same thing: less rainfall, higher spring temperatures and more frosts.”
He is already seeing hotter days earlier in spring. And although frost is relatively rare on his property, because of high-pressure systems and constant easterly winds for six weeks before rain, John’s property has already had more than 15 frosts to August this year. A GRDC and Managing Climate Variability research project, through the Department of Agriculture and Food, WA (DAFWA), is investigating these frost occurrences and impacts.
Although John is running the same rotations of sheep, canola, wheat and barley, he and other farmers in the area are checking and adjusting their inputs using the Yield Prophet® program.
“As soil types in this area are so variable, you have to plug the right soil type into Yield Prophet® before using it.”
The non-wetting soils on John’s property have responded well to a combination of claying and spading. “We have also done some mouldboard ploughing this year and will probably look at doing a bit more of that,” John says.
The spray-on product John was trialling on his non-wetting soils three years ago works well on some areas of his property. “It’s fairly costly, so we’re looking at whether we get a second and third-year response to its application.”
John is looking into shorter-season crops and delayed planting because of the later season starts and earlier finishes.
For the first time, John sowed 75 per cent of his crops dry this year. “We hadn’t had much rain until 10 June. We already sowed canola dry, started sowing our wheat dry and were two-thirds through our barley program before opening rain came.”
John has moved to short to mid-season wheat varieties, mid-season canola and mid-season barley to deal with the later starts.
Forecasting has not changed much for John. He says he has worked out which models do well for his area. John looks at BoM four-day predictions, consensus forecasts, WX Maps and the DAFWA predictions.
Although forecasts can change quickly for the West Midlands, over the past few years John has seen more accuracy. “It’s not something you put a lot of stock in, but they are in the back of your mind when you’re making fertiliser or stocking decisions,” he says.
Farm: ‘Lockier River’
Region: Mingenew, central-west WA
Commodities: wheat, lupins and Merino sheep
Farming area: 3400 hectares
Average annual rainfall: 400mm
Although the Mingenew shire is reliable for rainfall, the yearly average is trending downwards from a 100-year average of 420mm to 400mm.
“That is typical of this part of WA, unfortunately,” Peter says. “The only positive is that, according to information from DAFWA, we have lost that rainfall from our peak rainfall period of June and July when it was too wet for the crops.”
It is a ‘true’ Mediterranean climate – summer drought, winter rainfall.
Since the 1980s, when Peter arrived in Mingenew, farming systems in the area have moved to mostly cropping as climate variability has increased.
“Today there are a lot more no-till, one-pass operations. There’s less burning and machinery can handle the stubble,” Peter says.
Because of strong north-west winds, Peter leaves stubble to protect new, fragile lupin crops, which also helps with managing disease.
Peter sows seed into furrows, which can help turn a small rain event into something more useful. “At germination periods, it can give us just enough water to start germination.” However, this year the very dry start to the season meant Peter sowed his lupins and most of his wheat dry.
“We make our cropping program decisions about what we’re going to do, but then it’s the weather that dictates how we go about them and how we refine them,” he says.
For instance, applying nitrogen after the wheat is sown is where Peter “plays with the season”.
“It’s purely rainfall-based,” he says. “By the middle of June we start estimating what we think the rainfall will be for the year. We keep monitoring because you can still go out to about the middle of July putting nitrogen on to get a yield response.”
Peter is careful to emphasise how these decisions fit together. “Over the last few years I’d like to think we’ve got smarter with the whole farming system. I don’t think you can pin it down and say, ‘That’s what did it’.”
Peter says he does not know anyone in his area who uses long-term forecasting systems. Although he checks DAFWA and BoM forecasts, Peter prefers to make decisions as the climate outlook unfolds. GRDC and Managing Climate Variability research is focused on providing two to four-week forecasts.
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