Western Australia
December 11, 2007
Source:
GRDC's The Crop Doctor
While rain-fed agriculture is
likely to remain a feature of Western Australia broadscale
enterprises, the nature and stability of future climate has
implications for the grains industry long term.
Winter rainfall in the past 30 years has substantially declined
in south-western Western Australia and this is consistent with
global climate change models, making WA a logical region for
climate change studies.
A GRDC-funded research project has generated and tested daily
climate files for current conditions and for the middle of the
21st century.
Principal researchers, Dr Imma Farre and Dr Ian Foster of DAFWA,
used the data to identify changes in wheat production, or
quality, from current to future climate.
Dr Foster indicated that seasonal risk statistics, such as the
timing and occurrence of frost events, were derived from daily
temperature extremes.
Eight locations represented the range of rainfall zones (high,
medium, low) and agricultural regions (north, central and
south). Three typical soil types – sandy, duplex and clay, with
59, 86 and 116mm of plant-available water, respectively, were
chosen.
Simulated climate data demonstrated that for the mid 21st
century in southern Western Australia, temperature and carbon
dioxide concentrations would increase and growing season
rainfall decrease.
Total annual rainfall reductions tended to be higher in the
high-rainfall locations. The highest seasonal rainfall reduction
was predicted for April - June, resulting in later sowing
opportunities and decreasing expected yields.
Yield consistently declined in the low rainfall zones and
increased in some high rainfall locations and waterlogging-prone
soils. Heavier soil types, such as clay, were more vulnerable to
climate change than lighter soils.
In most locations, the positive effect of elevated carbon
dioxide on crop yields was more than offset by the negative
effect of increased temperatures and lower rainfall. Increasing
atmospheric concentration of carbon dioxide would also lower
grain protein levels, if no changes to fertiliser management
were considered.
Dr Farre indicated that adjusting farm management practices,
such as fertiliser management and cultivar choice, may be
necessary to counteract some of the negative impacts of climate
change.
She also suggested that future improvements to climate models
should add confidence to regional climate projections. Data
obtained in the GRDC study forms an objective basis for a range
of future impact and adaption studies.
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The Crop Doctor is
GRDC Managing Director,
Peter Reading |
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