ABSTRACT
The south-western part of Australia is characterised by a Mediterranean-type climate with warm-to-hot, dry summers and mild, wet winters. Southern Australia differs from the eastern Mediterranean in terms of signifi cant (but unpredictable) summer rainfall as monsoonal troughs occasionally descend from the tropics, bringing summer storms (di Castri 1981). The soils in this region are predominantly old, highly weathered and infertile. The mixed crop and livestock agro-ecological zone covers approximately 20 million ha and rainfall varies from 300 to 650 mm annually. Crops, predominantly wheat, barley and canola, are the most profi table enterprises although many farmers maintain sheep within their system. The sheep fl ock is primarily based on Merino ewes for wool production although rams of other breeds are used to produce lambs for domestic slaughter and live export. Arable land is rarely planted to perennial pastures they struggle to persist through the hot dry summers and they reduce fl exibility in the cropping enterprise. Perennials are often planted on areas that are unsuited to cropping, including saline, waterlogged, acidic, sandy, stony and otherwise unproductive land (Lawes et al. 2014).
