Wheat and weather
Recent CSIRO research has found that Australia’s yield potential, particularly in the wheat-growing zone, has experienced a decline of 27 per cent over the last 25 years.
The team found that wheat was particularly affected by an average rainfall decline of 2.8mm – or 28 per cent – per cropping season, and a maximum daily temperature increase of around 1C from 1990 to 2015.
This poses a risk to Australia’s more than $5 billion per annum wheat industry, which contributes around 12 per cent of the total wheat traded worldwide.
CSIRO senior principal research scientist Dr Zvi Hochman says the observations are consistent with the higher end of future climate change projections for the wheat zone over the coming 26 years.
“Our results are a serious concern to the future livelihood of wheat farmers in marginal growing areas and to the Australian economy, as well as future global food security,” Hochman says.
“Wheat farmers are making the most of developments in farming technology and adapting them to their needs.
“However, their best efforts are merely enabling them to keep pace with the impacts of a changing climate.”
He says the difference between actual yield and potential yield is closing as farmers are managing to maintain yields at 1990 levels of around 1.74 tonnes per hectare.
According to Hochman, “1990 was a watershed year for Australia’s wheat industry, with a continued decline trend in yield potential since that year”.
The study analysed 50 weather stations with the most complete records across Australia’s wheat growing regions, spanning five states from the east to the west coast.
“We found that the loss of yield potential is not evenly distributed across Australia’s wheat zone.
“While some areas have not suffered any decline, others have reduced yield potential by up to 100kg per hectare per year.
“The closing of the gap is driven by both technological advances including better wheat varieties and better practices.
“So to find out what has happened to yield potential we were keen to work with high-quality weather stations.
“They had to be located in an area which was a significant wheat growing area,” Hochman says. “They also had to be at least 20km away from each other so that each one was telling us something different.
“We then found that they were also representative of 10 of the agro-ecological zones, and that meant that they represented more than 95 per cent of the area and that they also did a good job of representing the different soil types that are relevant to wheat production.”
Hochman says that other crops are just as likely to be affected by the snowballing drop in potential yield, though adverse effects on the wheat industry would be particularly devastating.
“Wheat is Australia’s most important grain crop, but other important grain crops like barley, canola, and various pulse crops that we grow all are likely to be similarly affected because they will respond to the same climatic variables in a similar way.”
As well as being particularly important in Australia, a steady supply of food is also a worldwide concern as increasing populations and climate change continue to cause food shortages in developing nations.
Hochman says that even though a stronger production of food in needed, climate change could lead to a significant drop in wheat growth.
“By 2041, especially those in areas in which the [yield potential] decline has been higher, there will be quite a few farmers who will find it too marginal to keep growing wheat,” he says.
“The World Food Organisation has calculated that, to meet the demand of growing populations and of a more affluent world, by 2050 the world is going to have to produce 60 per cent more food than it currently produces.”
CSIRO senior principal research scientist Dr Zvi Hochman