Climate change driving practice change
GroundCover™ Issue: 116 | Author: Rebecca Thyer
Merredin growers Mick and Kate Caughey have seen annual rainfall across their three farms drop between
10 and 20 per cent in the past 10 years against long-term averages.
Today as little as 100 millimetres can fall during the winter grain-growing season.
With end-of-season temperatures also warming, the Caugheys have been gradually changing their on-farm practices to help better manage the new climatic challenges of less moisture and greater heat stress.
This includes retaining stubble and spraying summer weeds (to conserve stored soil moisture) and using precision-farming principles to better care for the soil.
As a third-generation Western Australian grower who has managed the farm for 25 years, Mick says he does believe the climate is changing. “I also believe in the region’s inherent climatic variability. We have dry years and we can still have wet years.”
This year, as part of his philosophy to reduce risk, he plans to begin using variable-rate (VR) technology for applying fertiliser.
Mick says he expects the same fertiliser bill, but the nutrients will be more efficiently targeted.
The Caugheys farm 5000 hectares of wheat and barley at Merredin. Legumes are no longer grown because of the changing conditions. Using a new John Deere aircart, Mick is basing his granular fertiliser application on yield data from the past few years.
He has also started “playing” with EM38 (electromagnetic) maps and gamma-ray spectrometry to better understand the farm’s soil properties. He has started taking one-metre-deep soil cores across paddocks.
“It’s not necessarily because of worries about subsoil constraints,” Mick says. “It’s because I would like to know what’s going on underneath. It’s all part of learning more about our soils.”
He hopes that better information about his soils will allow inputs to be better targeted “so that we are spending money strategically”.
Soil testing on the Caugheys’ home farm has already found sodicity, while he suspects other paddocks are likely to have low-pH problems.
“Coring has also shown us how far the roots go down. It will be interesting to learn why and what it means.”
Other on-farm changes to deal with a changing climate include a timely approach to spraying summer weeds using a contract sprayer.
This maximises stored soil moisture (if there has been any summer rain) for the following winter cereal crop and has shown potential to deliver a significant yield lift.