Business implications of a changing climate in the Tamworth region
Author: David Stephens | Date: 08 Sep 2016
Take home messages
• Summer rainfall has been steadily increasing, but since 2000 winter rain has dropped.• Wheat yield variability has increased with wheat seeding and spring rainfall decreasing.
• Early and late summer rain has increased providing more soil moisture for winter crops, but also more opportunities for summer crops in rotations.
• The rate of yield increase in sorghum yields was much higher than that for wheat yields.
Background
To assist the GRDC in defining new sub-regions and understanding what climate changes were occurring, an analysis was made by the Australian Export Grains Innovation Centre (AEGIC) of rainfall changes since 2000. This complimented spatial maps of wheat and sorghum yield trends carried out in a previous GRDC project (Stephens et al., 2011) which was updated with recent data.Methodology
Changes in mean fortnightly rainfall were graphed for key rainfall stations while yield trends, yield variability and water use efficiencies were determined with crop water balance models.Results and discussion
Since 2000 the rainfall was drier at Gunnedah in the winter growing season between April-October (Figure 1). The largest decrease in rainfall was found in the wheat seeding time and in early August. Conversely, the early and late summer rainfall increased considerably, though January was drier (Figure 1). The wetter summers appear to go hand in hand with higher sorghum yield trends, while lower winter rainfall has coincided with lower wheat yield trends (Table 1, Stephens et al., 2011).Figure 1: Average fortnightly rainfall for Gunnedah in the last 90 years of the 20th century compared to the first 15 years of the 21st century.
Table 1: Changes in climate and yields for the northern statistical division, NSW.
Crop | Rainfall Change | Yield change since 1990 |
---|---|---|
Wheat | -10% to -30% (May-October) | 1-2% per annum |
Sorghum | 0 to 30% increase (Nov-Apr) | 3-6% per annum |
Conclusion
A southward shift in rainfall zones and rising mean temperatures means that the climate experienced now in central NSW is more like that experienced previously by regions further north; i.e. more summer rain, less winter rain. Increased summer rain, combined with larger technological advances in yields of crops like sorghum means that the mix of summer crops in rotations needs to be reconsidered. Ways of increasing WUE in wheat without increasing financial risk should also be pursued in a more water limiting environment.
Useful resources
GRDC Ground Cover May-June 2016, New Climate Zones.
Stephens, D.J., Potgieter, A.P., Walcott, J. And Nunweek, M. (2011) GRDC strategic planning for investment based on agro-ecological zones – second phase. Final Report to GRDC, Department of Agriculture and Food, Western Australia, Perth, 156p.
Acknowledgements
The research undertaken as part of this project is made possible by the significant contributions of growers through their support of the GRDC, the author would like to thank them for their continued support.
Contact details
David Stephens
3 Baron Hay Court, South Perth, WA 6108
0403001318
david.stephens@agromet.com.au
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