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Silver lining to the dark clouds of climate change

By Peter Cornish - posted Friday, 19 November 2010

With the prospect of climate change, Australian farmers without irrigation appear to face a bleak future, and the outlook for irrigation in much of the Murray-Darling Basin looks pretty bleak as well. All the forecasts seem to point to falling rainfall in most of our traditional grain growing areas. The present good rainfall in eastern Australia does not mean a "return to normal".

Some would say that climate change has already started to bite, with Australian average wheat yield fluctuating between 0.6 and 2.2 tonnes per hectare over the past 20 years, wider fluctuations than ever before in our history. Individual farmers and the industry at large have both had to contend with monumental cash flow problems and debt, and with servicing valued markets.

These fluctuations are set to get worse. This is partly because of climate change and, paradoxically, partly because Australian dryland farmers are getting better at farming water. So is increasing yield variability necessarily such a bad thing? We need to first look into the past to answer this, and then to the future.


The first sign of climate change is increasing climate variability, but Australian farmers are no stranger to that. They have had to contend with variable rainfall, droughts and floods since settlement. Practices were introduced to iron out the fluctuations and bring some stability to production and farm cash flows. Yields were low by world standards, but relatively stable.

Only in the 1980s did we figure out that low crop yields in Australia at that time were mostly the result of management decisions, not our low and variable rainfall. We discovered that farmers were managing the risks of drought pretty well, but they weren't so good at capturing the opportunities in better years. There were good historical and technical reasons for this, but this was set to change.

Since the mid 1980's Australia's dryland grain producers have increased water productivity by an average of 50%, and many individual farmers have done much better than that. This means that, for a given amount of rainfall in any year, 50% more grain is being produced from the same area of land.

Few other sectors of the Australian economy can boast such strong growth in productivity, and this is just the water-productivity. The growth in "total factor productivity" that economists measure would be the envy of any sector of our economy, although farmers share in the profit has continued to slide.

This growth in productivity is the happy outcome of a number of technologies coming together, the centre-piece being conservation farming (or no-till farming) that improves infiltration of rainfall and the water holding capacity of soils. Others include the introduction of break crops such as lupin and high-yielding, high quality Canola. Break crops are broadleaf crops that are not hosts to cereal diseases. They reduce the impact of soil-borne diseases on cereals, setting them up to respond more to the fertility built up under pastures or to fertilisers.

Farmers have embraced crop benchmarking that enables them to identify under-performing paddocks and work out measures to lift performance. Many are starting to move away from fixed patterns of cropping to become more responsive to emerging opportunities each year, depending on water in the soil and expected rainfall.


Not only has no-till been central to increasing crop yields, but it allowed more intensive cropping without increasing soil loss. This allowed farmers to capitalise on the relative profitability of cropping over the past 30 years or so. On top of that, no-till has reduced soil erosion which, in the 1970's, was by far the nation's biggest environmental issue.

As farmers start to use rainfall more efficiently, in this regard they are starting to mimic natural ecosystems. This means that production must vary in line with rainfall. What's more, whereas once some of the unused rainfall bypassed crop and pasture roots and found it's way to groundwater, only to drive dryland salinity, so now this "leakage" must be less. Wins all round.

So, whilst wild fluctuations in yield are a nightmare for farmers, they are a sign the system is being managed better. That gives a hint of a silver lining to the cloud of climate variability.

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About the Author

Professor Peter Cornish from the School of Natural Sciences at the University of Western Sydney is the CM Donald Medalist for Agronomy.

Creative Commons LicenseThis work is licensed under a Creative Commons License.

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