Water use efficiency wins a science 'Oscar'
GroundCover™ Issue: 113
The five-year, $17.6-million initiative was established in 2008 to lift the water use efficiency (WUE) of grain-based production systems by 10 per cent across Australia’s southern and western cropping regions.
Crop simulation modelling suggested that a combination of management strategies could potentially lift grain yield by up to 40 or 50 per cent, and the five-year program of on-farm experiments demonstrated that such gains were indeed possible.
“The Water Use Efficiency team certainly overachieved,” said Kim McKay, CEO and director of Australian Museum, which runs the Eureka Awards. “From an initial aim of increasing WUE by 10 per cent they are helping growers achieve yield increases of up to 50 per cent. The implications for farming in a country with periodic shortages are obvious.”
The initiative, overseen by the GRDC’s Stuart Kearns and CSIRO’s Dr John Kirkegaard and Dr James Hunt, established on-farm projects on multiple research sites across southern and western growing regions with the help of 16 research groups in high and low-rainfall areas.
Key findings included:
- sowing a legume break crop could increase wheat yield by 16 to 83 per cent (average one tonne per hectare);
- sowing a legume break crop could increase wheat yield by 60 per cent, and earlier sowing of slower-maturing wheat could provide a further 22 per cent gain; and
- whole-farm wheat yield could be increased by nine to 17 per cent by shifting to an earlier sowing program.
The central message is the importance of managing the pre-crop period when more than two-thirds of a farming system’s WUE is generated. It is these months before a crop that sets the potential for soil to capture, store and retain water. In-crop practices such as sowing date and nitrogen management are responsible for the remaining WUE of the system.
The initiative found summer fallow management is a major WUE driver, particularly in cropping systems that rely on out-of-season rainfall to grow winter crops. Conserving this resource via effective weed control, stubble retention and minimum tillage could determine whether a winter crop was profitable or not.
In South Australia, research highlighted the WUE and yield benefits of matching fertiliser inputs to soil type. Increasing nitrogen inputs on sandy soils in the Mallee while lowering those on heavier soils led to significant increases in crop yield and returns.
In the western region, impressive improvements in WUE from gypsum application were achieved on southern coast soils, while whole-farm benchmarking proved valuable in assessing soils most likely to generate a cropping return from amelioration and fertiliser inputs.
The Australian Museum Eureka Prizes are the country’s most comprehensive national science awards; “the ‘Oscars of Australian science’,” said Australian Department of Agriculture Chief Scientist Dr Kim Ritman, who presented the award. Dr Ritman said it was critical that scarce research dollars were invested in projects that directly benefit growers: And this joint CSIRO and GRDC project did just that.The Water Use Efficiency Ground Cover Supplement is available at: grdc.com.au/GCS103
Region South, West