Dr John Kirkegaard1, Dr Jeremy Whish1, Dr Xiaoxi Li1, Mr Tony Swan1, Mr Mathew Dunn2, Dr Mehrshad Barary2
1CSIRO Agriculture and Food, Canberra, Australia, 2NSW Department of Primary Industry, Orange, New South Wales
Biography:
Dr John Kirkegaard is a farming systems agronomist whose research teams have worked for 34 years to improve the productivity and sustainability of dryland mixed farming systems. His focus has been to develop and integrate combinations of novel innovations that synergise in the farming system to improve the efficiency of water and input use while improving productivity and resilience. He is the recipient of numerous awards and is a regular invitee to national and international meetings and advisory committees on sustainable agriculture and food security.
Abstract:
Australian scientists and farmers have been keen adopters of productivity benchmarks such as WUE targets for individual crops but know less about the efficiency of the cropping system. Previous studies suggested gaps in system efficiency were significant despite good agronomy of individual crops. Strategies to improve system efficiency by increasing crop diversity, sowing earlier and improved N management had been explored separately and showed potential for improvement, but no studies had explored the potential to lift system-level efficiency and profit with interactions of crop sequence, sowing date and N management.
Field experiments were established at four sites across southern NSW in 2017 following consultations with ~ 300 growers and advisers to establish baseline and improved systems for the study. The phased and replicated experiments compared the baseline system (canola-wheat-barley sequence, sown in May, with conservative decile 2 N strategy) with systems involving (i) more (legume integration) or less diversity (continuous wheat, canola-wheat); (ii) earlier sowing (March for grazed crops, April ungrazed) and (iii) more robust N management (decile 7 target). The two full phases completed in 2023 comprised some of the driest and wettest seasons on record.
In the drier Phase 1, at all sites, diverse systems involving legumes sown timely with decile 2 N were more profitable, less risky and less variable than the baseline. After the wetter Phase 2, baseline and intense canola-wheat systems with higher N were more profitable at two sites, but with higher risk and variability. Impacts on soil water, N dynamics, weeds, diseases, soil C and GHG emissions were also monitored and will be discussed in the context of system profitability and resilience.