Climate change adaptation in Australian wheat farm systems upscaled from farm to national scale

Abstract

Wheat is one of the main grains produced across the globe and wheat yields are highly sensitive to changes in climate. Australia is one of the main exporters of wheat, and variations in its national production can affect global markets. We evaluated the effect of climate change in 2030 compared to a baseline period (1980-1999) when farm scale results were upscaled to the national scale. We assessed opportunities for increase in wheat yield under projected climates using current technology and management practices including adjustments to planting date, nitrogen fertilizer, and cultivar. On upscaling over the wheat belt, the potential adapted yield (tonne/ha) and gross margin ($/ha) for 1980- 1999 climate were estimated to be 17% and 33% higher than the baseline, respectively. In 2030 these potentials are 19% and 35% respectively, due to a 1% decline in yield and gross margin (national scale) without enhancement in efficiency of the current systems. At the enhanced systems (fully adapted) of 2030, yield increased by 1% and gross margin by 0.3% compared to the fully adapted baseline. Full adaption of current farm systems under current climate is not expected, and this will remain as a future challenge. However, in 2030 there will be more opportunity to increase the overall water use efficiency of the Australian wheat belt, mostly resulting from elevated atmospheric CO2 concentrations.