Wheat is Australia’s most valuable crop, representing $5 billion per year, and Australia is one of the world’s largest wheat exporters, accounting for 10 per cent of global wheat exports. In the first 90 years of the 20th century, our wheat yields more than trebled but growth has plateaued since 1990, some of which is due to reduced rainfall and increasing temperatures in line with global climate change. Decreasing profit margins and increasing input costs are key issues for growers.
For more than a century, wheat in Australia has been established on rains that fall in April and May and it grows over winter to flower in an optimal period between September and October, depending on the geographical location. Grains Research and Development Corporation (GRDC) research has highlighted that wheat yield declined at 35kg/ha for each day sowing was delayed beyond the end of the first week of May, using a fast-developing spring variety.
Sowing date is a key agronomic management decision and is crucial to growing a successful crop. If wheat is sown too early, then it may suffer poor establishment, and the risk of frost is increased. If it is sown late, there can be insufficient growth before flowering to achieve high yield and the risk of terminal drought and heat stress during grain filling. The optimum sowing date strikes a balance between these factors.
A series of GRDC-funded CSIRO projects delivered a broad and comprehensive adoption program to encourage growers to establish crops at a time that leads to flowering during the optimal period in their environment. In water-limited environments, the time at which wheat flowers is a critical determinant of yield.
Modelling, farmer interviews and field trials demonstrated that adoption of dry and early sowing practices has the potential to furnish wheat yield benefits of 170–500 kg/ha without an increase in the likelihood of production risk, especially in a Mediterranean environment. This represents the potential of an additional 7.1 Mt annually for Australia, despite climate change challenges.
In Western Australia, approximately 16 per cent of grain growers are sowing the wheat dry, and a 2017 survey showed that 24 per cent of growers from 14 shires across WA started their sowing programs before 26 April. Yield gains of 0.077 t/ha have been achieved in Western Australia and South Australia, using mid-developing spring cultivars plus early sowing.
The Western Australian wheat industry increased production by 219,000 tonnes or 81,000 tonne per year from 2010–11. This additional wheat production was valued at $26 million per year. Early sowing has contributed 10 per cent of this value or 21.9 million tonnes worth approximately $5.7 million to the wheat industry.
This outcome is reflective of the contribution of research to improve the ability of Australian grain producers to manage dry conditions, with ABARES identifying that during the 1-in-20-year drought of 1979–80, average productivity for broadacre cropping farms was reduced by 37 per cent. By the 1-in-20-year drought of 2013–14, the adoption of climate-adjusted productivity improvements saw a smaller decline against average productivity of 26 per cent.