Combined effort takes on efficiency challenge

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Small, sparse crowd in a field

The GRDC Water Use Efficiency Initiative has shown
that significant improvements in grain productivity and
WUE are possible across Australia. Pictured are
growers discussing the results from one of 16 WUE
research sites set up as part of the Initiative across
the southern and western grain regions.

PHOTO: John Kirkegaard, CSIRO.

The five-year, $17.6 million Water Use Efficiency Initiative was established in 2008 to challenge growers and researchers to lift the water use efficiency (WUE) of grain-based production systems by 10 per cent across Australia’s southern and western cropping regions.

Sixteen research groups submitted proposals they believed would achieve the required lift in productivity and WUE. Research sites established across the southern and western GRDC growing regions covered high and low-rainfall areas in all states. The projects, coordinated by CSIRO, included an annual forum at which participants shared research updates and developed practical on-farm recommendations.

This supplement reports on the main findings of the five-year initiative.

Summer fallow management has emerged as a major driver of WUE, particularly in cropping systems that increasingly rely on out-of-season rainfall to grow winter grain crops. CSIRO research indicates the 10 per cent improvement in WUE to be achievable – with fallow summer rain contributing an average of 33 per cent of grain yield in some seasons.

Conserving this valuable resource via effective weed control, stubble retention and minimum tillage can mean the difference between a profitable and unprofitable winter crop.

In other research, early sowing of slow-maturing wheat varieties into stored soil moisture generated impressive yield gains of between one and two tonnes per hectare in some seasons. Used as part of a mix with faster-maturing varieties, these slow-maturing wheats can help extend the sowing window and reduce production risks by as much as 40 per cent.

South Australian research has 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 has led to significant increases in crop yields and returns.

In the western region, impressive improvements in WUE from gypsum application have been achieved on southern coast soils, while whole-farm benchmarking has proved valuable in assessing the soils most likely to generate a cropping return from amelioration and fertiliser inputs.

A central message from the WUE Initiative has been the importance of tending to the pre-crop period to lift the WUE of farming systems. It is this period – months to years before a crop – that sets the potential for a soil to capture, store and retain water for a subsequent crop. More than two-thirds of the WUE of a farming system is generated by management practices during the pre-crop period, with a further third attributed to in-crop management practices such as sowing date and nitrogen management.

When combined with the correct wheat variety, the pre-crop and in-crop management practices work in synergy to lift WUE beyond what is possible from any of the variety choices or practices implemented in isolation. New genotypes, such as the long coleoptile wheat variety and those with other WUE traits being developed by CSIRO as part of their pre-breeding research program, have the potential to provide further increases in productivity and WUE by facilitating early sowing into stored summer fallow soil moisture.

Reflecting the work within the Water Use Efficiency Initiative, the articles presented in this Ground Cover supplement have been organised into pre-crop and in-crop themes. Combined, these improved pre-crop and in-crop management practices can easily achieve the goal of a 10 per cent lift in the WUE and yield of Australian cropping systems.

More information:

Dr Darren Hughes, GRDC regional program manager – west,
02 6166 4500,
darren.hughes@grdc.com.au

Next: Short and long-term focus needed to lift WUE

GRDC Project Code CSP00111

Region South, West, National