Diversifying Intensive Dryland Cereal Production Systems in Australia.

Australia’s dry-land cropping zone comprises mixed livestock-cropping enterprises growing staple annual cereal crops, mainly wheat (Triticum aestivum) in rotation with legume-based pastures grazed by sheep. Cropping has intensified at the expense of pastures over the last 30 years, but despite the diversity of pulse and oilseed crops available in Australia and their demonstrated benefits to cereals in the crop sequence, cereals still comprise 80 to 84% of the cropped area. Cereals are attractive due to wide adaptation, ease of management and marketing, and lower risk due to reduced set-up cost and more reliable performance in difficult seasons. The 2002 to 2010 “Millennium Drought” further intensified the cereal system and exacerbated an emerging issue of multiple herbicide-resistant grass weeds in cereals, which increasingly dictate management options. A national initiative to investigate profitable integration of oilseeds and pulses commenced in 2009, recognising that profit and risk were major influences of farmer decision-making. Models were used to complement experimental data to assess long-term trends and financial outcomes. To date, the project has demonstrated that cumulative gross margins over 2-4 years were highest in sequences that included at least one break crop. On crop-only farms, low-input legume cover crops such as vetch or field pea terminated early (spring) can provide an economic alternatives to high-input break crops by simultaneously providing control of intractable weeds, breaking disease cycles, fixing high levels of N and storing water for subsequent crops. Current economics in Australia favours the tactical use of annual oilseed and legume break-crops in intensive cereal systems to manage intractable weed and disease issues, restore soil N levels or capture higher oilseed and pulse prices, rather than in regular fixed rotations. The challenge is to identify the “trigger-points” of weed, disease, water and N levels that would signal the highest likelihood of benefits from the inclusion of non-cereal break crops in the crop sequence. .