Impact on broadacre
From the December 2007 edition of Agriculture Today.
While there will be major impacts on irrigated cropping through reduced runoff into dams, most broadacre crop producers who adapt their farming practices to a hotter, drier climate should be able to manage the impact of projected climate changes.
Southern Farming Systems research leader with NSW Department of Primary Industries, Dr Alison Bowman, says dryland broadacre croppers have always had significant seasonal variability.
"Farming systems already incorporate a range of factors to reduce the risk associated with this variability," Dr Bowman said.
"While broadacre farmers may be exposed to the greater seasonal variability associated with climate change, I believe they also have the capacity and experience to allow them to adapt their systems relatively quickly."
One of the more likely climate change scenarios for NSW by 2030 is the annual average temperature will rise by 1.5 per cent, with an increase in the average number of hot days over 35 degrees of between five and 25 days.
Meanwhile, annual average rainfall is projected to drop by about 10pc by 2030, with the biggest reductions in winter and spring.
Dr Bowman said perhaps the greatest risk for dryland croppers from this so-called "hot dry" scenario is the seasonal break could become even more variable in southern Australia and be combined with unreliable spring finishes.
"The reduced possibility of an early autumn break will restrict the range of crops that can be grown," she said.
"For instance, some farmers could take canola out of the rotation completely, because of its requirement for an early break.
"The danger here is that farmers may revert to easy to grow cereal on cereal rotations, which results in reduced soil fertility, disease and weed build up."
Dr Bowman said some farmers had already taken this direction in the last five years with the continuing drought in southern NSW.
Frosts could also become more unpredictable and affect crops at flowering and in the early stages of grain filling.
"In terms of the total cost to the grains industry, the value of production lost due to frost is small," she said.
"However, for an individual grower the cost can be devastating."
Another anticipated impact is the emergence of weeds and diseases that are not currently a major problem.
An example in southern NSW is the emergence of deep rooted summer perennial weeds, such as nightshade.
One factor that will help farmers adapt is the experience of those already farming in more marginal areas.
However, for those farmers already at the margins, adaptation may not be feasible.
Dr Bowman said some redistribution of the grains industries could be expected.
"There is expected to be a contraction from the more marginal environments where livestock production could displace cropping," she said.
For further information on projected climate change causes and impacts, see www.dpi.nsw.gov.au/research/topics/climate-change
Contact Alison Bowman, Wagga Wagga, (02) 6938 1628, alison.bowman@dpi.nsw.gov.au
