Cropping on yellow earth soils in the eastern wheatbelt of Western Australia can be restricted by subsoil acidity. There are approximately one million hectares of yellow earth soils in Western Australia, some of which are extremely unproductive due to acidity and high concentrations of available aluminum. The best crop rotation on yellow earth soils includes wheat and narrow-leafed lupins, but this is not economically viable on those soils with high aluminum concentrations. It is known that the yellow lupin (Lupinus luteus) is more tolerant to toxic levels of subsoil aluminum than the narrow-leafed lupin (Lupinus engustifolius). Research has shown that the yellow lupin has a very high level of resistance to Pleiochaeta root rot and brown leaf spot (Pleiochaeta setosa) compared to the narrow-leafed lupin. Evidence from field trials has shown that the advantage of the yellow lupin over the narrow-leafed lupin is the greatest on the soils with a high level of extractable aluminum. The potential role of yellow lupins in the Western Australian eastern wheatbelt farming system is assessed using the whole farm bio-economical model, MIDAS (Model of an Integrated Dryland Agricultural System).