Resilience Revisited – What Next for Australian Mixed Cropping Systems?.

Australia’s broad-acre cropping has traditionally occurred in mixed crop-livestock enterprises with phases of wheat-based cropping sequences rotated with legume-based pastures grazed by sheep.  The biophysical and economic elements of such “ley-farming” systems have meant that historically, they been considered some of the most resilient worldwide. However, the recent evolution of the farming system has included a 50% reduction in sheep numbers and a decline in pasture area, and an intensification of cropping under no-till farming systems, with the inclusion of oilseed (canola) and grain legume break crops.  Changes in climate are already evident with drier autumn planting periods, more variable rainfall and warmer temperatures and changes in the occurrence and severity of damaging frosts.  How resilient are these modern intensive cropping systems?  No-till cropping, while protecting the soil, does not match pasture phases in building and maintaining soil C levels.  Herbicide tolerant weeds develop rapidly in intensive no-till cereals and can limit yield and crop choices.  Nitrogen supply to cereal crops, once predominately supplied by legume pasture residues increasingly relies on costly N fertilizers.  Recent national research initiatives on whole-farm water-use efficiency, integration of dual-purpose (grain-graze) crops, strategic tillage, increased adoption of break crops, inclusion of perennial plants and consideration of intercropping have all addressed aspects of system resilience.  Features of the research that improve the likelihood of adoption include the use of crop and whole-farm simulation in the analysis of risk, and the close interaction between growers and researchers in local field-based research to embed social and economic imperatives from the outset. We discuss recent research highlights and whole-of-system synergies that generate significant improvements in resource-use efficiency and resilience in the face of this farming system evolution and a changing climate.