Australia’s average wheat yields, which had more than tripled due to technological advances between 1900 and 1990, did not increase from 1990 to 2015, according to the CSIRO.
Recent research by CSIRO scientists, published in the journal Global Change Biology, found Australia’s yield potential (determined by the climate and soil type, managed using best-practice and current technology) declined by 27 per cent over the past quarter of a century.
CSIRO team leader Zvi Hochman said the study found Australia’s wheat-growing zone had experienced an average rainfall decline of 2.8mm or 28 per cent per cropping season, and a maximum daily temperature increase of around 1°C from 1990 to 2015.
‘‘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,’’ Dr Hochman said.
‘‘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.’’
Dr Hochman said despite the adverse trend in growing conditions, farmers had so far managed to maintain yields at 1990 levels of around 1.74tonnes/ha.
He said 1990 was a watershed year for Australia’s wheat industry, with a continued decline trend in yield potential since then.
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,’’ Dr Hochman said.
‘‘While some areas have not suffered any decline, others have reduced yield potential by up to 100kg per ha per year.’’
However, the probability of seeing the trends shown by this study across 50 weather stations over 26 years, through random seasonal variability, is less than one in 100billion.
‘‘Assuming the climate trends we have observed over the past 26 years continue at the same rate, even if farmers continue to improve their practices, it is likely the national wheat yield will fall,’’ Dr Hochman said.
‘‘We estimate that the recent average yield of 1.74tonnes per ha will fall to 1.55tonnes per ha by 2041.’’
The CSIRO predicts the 2016 season will result in a bumper crop, however, preliminary estimates show that yield potential in 2016 was about the same as in 2010.
‘‘So, yield potential was high, but not exceptional. The anticipated record yield is consistent with the trend of farmers closing the yield gap,’’ Dr Hochman said.
Although the study focused on wheat, the findings would be broadly applicable to other cereal grains, pulses and oilseed crops, which grow in the same regions and same season as wheat, he said.