Drier seasons in the Mallee not just a climate blip
GroundCover™ Issue: 94 | 17 Aug 2011
David Smith has farmed in the southern Mallee, Victoria, since 1972, working in partnership with his brother Ian, growing mostly cereals and hay and running about 900 first-cross ewes.
Historically, the region would receive 340 millimetres of rainfall a year – 250mm of that falling in the growing season between the beginning of April and the end of October. But in the past 10 years, average growing season rainfall has been below 200mm.
As David notes, “a significant drop off … and even after 300mm of summer rain this year our crops are now hanging out for a drink”. For a time he put it down to a “blip” in the cycle, but has since become certain his region’s climate has changed and become drier. “I think what we’re experiencing is some climate variability and some climate change,” David says.
“Between 1996 and 2010, we didn’t record a single season with above-average rainfall.” He used to assume that a dry year would give better ‘odds’ of a wetter season the next year. “We kept on with our legume rotations, saying, it’s going to get wet again. But the dry years kept coming.”
The sustained decrease in rainfall has prompted David and Ian to change their enterprise mix, season to season. Their first step in responding to climate risk has been to remove legumes and canola as routine components of the rotation, concentrating on wheat and barley, and vetch and oats for hay.
Harvesting hay has been a successful shift in business for the Smith family. Four years ago they cut their canola crops for hay when it started looking dry and achieved a good return. The following year cereals were cut with the same positive result.
They now sow a mixture of vetch and oats for grazing or hay production. “That’s something we typically hadn’t done, but it has worked out very well.”
David says they now grow ‘opportunity crops’ when they think it will be wetter or when they have enough stored subsoil moisture. This year they reintroduced canola to take advantage of the saturated soil.
Shorter growing seasons and less rainfall mean the Smiths have to be more adaptable and versatile. “We’ve simply got to be able to change,” David says. “Ten years ago we worked out a rotation we wanted to stick with … now we try to work with the seasons and be more flexible.”
David and Ian make five-year, annual and monthly budgets and plans. “We might not get through the five-year rotation – by the third or fourth year the technology, weather, rain and crop mix has changed. But you still have to plan for the longer term because we’re not just farming for one year.”
These plans take into account the season, soil testing, markets and prices. David and Ian then adjust plans as they go, using in particular the decision-making program Yield Prophet® to determine the probability of a good return on potential crop choices.
“If Yield Prophet® shows that the chances of getting a return from growing one crop aren’t as good as another, and it broadly fits our long-term rotation, we’ll change to the more profitable option.”
Yield Prophet® uses data on soil type, soil water, soil nutrient content, current and historical rainfall, crop details and fertiliser application.
David says using a scientific model like this has changed sowing dates and the cropping mix. “It has given us the confidence to manipulate our inputs if the model says the chance of a big crop is high that year,” he says.
“Sometimes gut feel doesn’t work out … spending money on urea and nitrogen inputs in case of a fluke rain event is more risk than we like to take.”
In the past five years, David has moved away from cultivating paddocks and is certain of the benefits.
“Minimum-till and direct-drilling is the way to go for us because it reduces soil loss through wind erosion, is better for the soil structure and it conserves moisture.”
Now David will not work the soil unless there is an exceptional reason, a stark contrast, he notes, to his father’s time, when crop paddocks were cultivated as many as seven times.
Last year the Smiths direct-drilled all their barley and half their wheat crop. This year, because of flooding and nitrogen leaching, they have direct-drilled only 25 per cent of their wheat, but all of the barley.
“It’s been slow progress,” he says. “The year before (2009), we direct-drilled 10 per cent of our wheat and about 70 per cent of our barley. The year before that (2008) we wouldn’t direct drill any wheat. We didn’t think you could on our (heavy) soil type.”
With time, David and Ian have learnt to manage direct-drilling in their heavy soils and expect to eventually implementing full direct-drill.
David and Ian are long-term members and supporters of BCG (formerly the Birchip Cropping Group). Twelve years ago when BCG’s main trial site was on their farm, David cultivated his paddock carefully, alongside the direct-drilled BCG trial plots.
“I thought, ‘They’ll never grow crop that way’. But their crop grew just as well as ours, so I thought we could try it too.”
David is a participant in the Climate Champion program.
- By Sarah Cole
GRDC Project Code ECO00003
Region South, North, West
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