Integrating dual-purpose wheat and canola into high-rainfall livestock systems in south-eastern Australia. 3. An extrapolation to whole-farm grazing potential, productivity and profitability

Dual-purpose crops can provide valuable winter forage in livestock production systems and increase subsequent pasture availability. Using experimental measurements of sheep grazing on pasture only or dual-purpose crops of wheat, canola, and wheat and canola in combination, and their associated effects on subsequent pasture grazing, we estimated for two different years the whole-farm changes in whole-farm sheep grazing days (SGD), relative farm production and farm economic impact. The increased winter feed supply and higher grazing intensity on dual-purpose crops allowed 2-3 times the area of pasture to be spelled, which together enabled increases in potential year-round pasture stocking rate. Up to 20% of farm area could be allocated to dual-purpose crops while still obtaining the same number of SGD per farm ha with additional grain production (5.0-5.4 t wheat ha(-1) and 1.9-3.6 t canola ha(-1)) adding significantly to farm profitability and production. Allocating 10-20% of the farm to a combination of dual-purpose wheat and canola grazed in sequence could increase whole-farm SGD by 10-15%, increase farm output by >25% and increase estimated farm profit margin by >AU$ 150 farm ha(-1) compared with pasture-only livestock systems. The long crop-grazing period from wheat and canola in combination providing a large pasture-spelling benefit was a key factor enabling these economic and productivity increases. Introducing wheat or canola alone on up to 30% of the farm is likely to reduce SGD per farm ha, but still significantly increase whole-farm productivity (10-20%) and estimated profit margin ($50-100 farm ha(-1)). Over the two very different experimental growing seasons, the estimated relative changes in whole-farm productivity and estimated profit margin were similar, indicating that these benefits are likely to be consistent over a range of years. Together, these findings suggest that once whole-farm livestock feed-base effects are considered, large economic and productivity benefits can be attributed to dual-purpose crops when integrated into livestock production systems in Australia's southern high-rainfall zone.