No abstract

During the past decade, Australian and New Zealand dairy farmers have been increasingly exposed to volatility in milk prices, declining terms of trade, climate variability, changing regulation, and increasing consumer demand to demonstrate their ‘social licence to farm’. In response to the varying challenges, it is not surprising that we see significant diversity in dairy-farm systems in Australia and New Zealand. Despite much research effort to address these challenges at both the component and farm-system level, the evidence of adoption and dairy farming-system change over the past 5 years has been inconclusive. The present review explores how farmers and systems research have been affected and are responding, and whether systems research is developing research in the appropriate direction, proactively researching dairy-farming systems that are resilient, profitable and sustainable into the future, notwithstanding the increased volatility that dairy farms are experiencing. While much farm systems research in Australia and New Zealand has addressed the challenges associated with improving productivity and profitability, and the known challenges such as climate variability and improving environmental outcomes, there is need to fore-sight future risk, challenges and opportunities for dairy systems. It is also important that the system researchers explore alternative approaches such as working collaboratively with the known system experts, the dairy farmer, in a participatory environment to increase rate of knowledge transfer and adoption of positive research outcome.

The irrigated dairy industry in southern Australia has experienced significant restrictions in irrigation water allocations since 2005, consistent with climate change impact predictions for the region. Simulation models of pasture growth (DairyMod), crop yield (Agricultural Production Systems Simulator, APSIM), and dairy system management and production (UDDER) were used in combination to investigate a range of forage options that may be capable of sustaining dairy business profitability under restricted water-allocation scenarios in northern Victoria, Australia. A total of 23 scenarios were simulated and compared with a base farm system (100% of historical water allocations, grazed perennial ryegrass pasture with supplements; estimated operating surplus $A2,615/ha at a milk price of $A4.14/kg of milk solids). Nine simulations explored the response of the base farm to changes in stocking rate or the implementation of a double cropping rotation on 30% of farm area, or both. Five simulations explored the extreme scenario of dairying without any irrigation water. Two general responses to water restrictions were investigated in a further 9 simulations. Annual ryegrass grazed pasture, complemented by a double cropping rotation (maize grown in summer for silage, followed by either brassica forage crop and annual ryegrass for silage in winter and spring) on 30% of farm area, led to an estimated operating surplus of $A1746/ha at the same stocking rate as the base farm when calving was moved to autumn (instead of late winter, as in the base system). Estimated total irrigation water use was 2.7ML/ha compared with 5.4ML/ha for the base system. Summer-dormant perennial grass plus double cropping (30% of farm area) lifted operating surplus by a further $A100/ha if associated with autumn calving (estimated total irrigation water use 3.1ML/ha). Large shifts in the forage base of dairy farms could sustain profitability in the face of lower, and fluctuating, water allocations. However, changes in other strategic management policies, notably calving date and stocking rate, would be required, and these systems would be more complex to manage. The adaptation scenarios that resulted in the highest estimated operating surplus were those where at least 10 t of pasture or crop DM was grazed directly by cows per hectare per year, resulting in grazed pasture intake of at least 2 t of DM/cow, and at least 60% of all homegrown feed that was consumed was grazed directly.