Different response of soil and crop sequences to climate change in Western Australian mixed farm systems

Western Australia is a major producer and exporter of crops and much of the production comes from mixed crop-livestock farms. Climate drives the productivity and profitability of these farms. Therefore, the effects of likely climate change on farm performance need to be understood. Here, the effects of climate change at 2030 were evaluated compared to a baseline period (1980-1999) on mixed farming systems for different soil types and rotation systems using the coupled APSIM and GRAZPLAN biophysical simulation models. Different crops’ yields under historical and projected climates were assessed using current technology and management practices, including interactions with livestock. Representative mixed-farm systems were selected along a climate transect. Compared to the baseline, in 2030 crop yields had different responses to changes in climate in soil x current rotations, except for lupins. Under the hotter and drier potential climate of 2030, the greatest positive effect on wheat and barley yield was 20% (Katanning, Shallow sandy duplex, rotation: AAAWC) and 37% (Cunderdin, Deep loamy duplex, rotation: WPWCB), while there was no increase projected for canola and lupin. The greatest decline of wheat and barley yield was 20% (Mullewa, Coloured sands, rotation: WLWC) and 16% (Cunderdin, Shallow sandy duplex, rotation: AAWCB, Katanning, Grey sandy duplex, rotation: AAB). Overall, current long term average productivity of rotation systems × soil type may change in near future depending on degree of changes in climate, suggesting requirement for optimizing current rotation systems to obtain maximised production and profitability