Dr Lindsay Bell1, Dr Maartje Sevenster2, Ms Brook Burrett1, Ms Heidi Horan1, Dr Aaron Simmons3
1CSIRO, Toowoomba, Australia, 2CSIRO, Canberra, Australia, 3NSW DPI, Orange, Australia
Biography:
Lindsay Bell has a PhD from University of Western Australia and has worked as a farming systems scientist with CSIRO. He applies both experimental and modelling approaches to examine the productivity, sustainability and resilience of a range of farming practices and systems.
Abstract:
While single year GHG accounting is often used to benchmark emissions nationally at particular times, this is problematic in Australian grain systems, where large variations in climate can induce large year-on-year variation in production and GHG emissions. Using APSIM we simulated for a 30 year period (1990-2019) current and alternative crop rotations, and current and alternative N management practices at 50 locations that equally represent the cropping area across the country. We calculated overall emissions and emissions intensity nationally and these modelled estimates matched closely national level static accounting approaches. Modelling results show that it is possible to increase overall production without significantly increasing overall on-farm emissions, by choosing locally productive and profitable rotations with low GHG emission intensity and optimizing nitrogen management. If nitrogen fertiliser could be supplied in such a way as to better match crop demand, total fertiliser use is modelled to increase 3-fold, but net on-farm emissions would slightly decrease because extra emissions are balanced by increased carbon sequestration in soils. Overall, a reduction of GHG intensity (i.e. GHG emissions per tonne of grain) of around 15% may be feasible with improved agronomic management. Unless dramatically higher carbon prices were offered it was optimal in almost all situations to select rotations that generated highest income rather than reducing GHG emissions. Optimising N management is likely to be a critical pathway to further improve the GHG footprint of Australia's grain industry.