Contrasting trends in wheat production exist across Australia in response to climate

Context The wheat dominated dryland cropping zone in Australia occupies over 50 million hectares. Climate change has impacted production but reports on the scale and magnitude vary. Objective This study defines the spatial extent of production trends in potential wheat yield from 1990 to 2023 across Australia and discuss the innovations required to adapt to a changing climate. Methods Here, we simulate wheat production. 30,482 simulations of potential wheat yield were run using climate grids, crop simulation models and national soils grids to evaluate the production trends across Australia from 1990 to 2023. Simulation output is summarised, and features related to production trends in wheat potential yield, and mean levels of production, incrop rainfall, fallow rainfall, soil water at sowing, frost and heat damage and season length were created from the simulation output. Cluster analysis of these features generated 6 distinct agro-ecological zones (AEZ) of production across Australia. Results and conclusions On average, potential yield declined at a rate of 12.5 kg/ha/yr or by 12 % over 33 years. The trends varied from a 40 % increase for 1.7 million hectares in the North zone, to a 33 % decline across 4.7 million hectares in the Far East zone of Central and Eastern NSW. The frequency of drought cycles also ranged from 6.8 years for the Interior Edge and South-Central zones to 11.3 years for the Southern zone. Notably, every AEZ experienced an increase in fallow rainfall, and a moderate decline of incrop rainfall. The magnitude of these increases and decreases, combined with changes in frost and heat stress, influenced the scale of the change in potential yield over time. Significance Innovations must concentrate on effectively utilising fallow rainfall to enhance water and nutrient use efficiency and seek to mitigate the effects of frost and heat stress at the end of the growing season. The type and magnitude of the intervention required to address climate change impacts on wheat yield vary markedly between the 6 zones.