Strategies to raise crop yields, often combined with extra grazing to deliver big gains in farm profitability was highlighted in Dr John Kirkegaard’s Farrer Memorial Oration delivered in November last year. Dr Kirkegaard was the 2017 winner of the prestigious Farrer Memorial Medal and is a senior well-respected CSIRO scientist.
John Kirkegaard and his colleague’s research, often conducted in partnership with farmer groups and other researchers has a strong emphasis on combining aspects of earlier sowing including appropriate variety selection (in cereals and canola) with improved crop management both pre-crop (fallow management) and in-crop (nitrogen management and disease control).
Water use efficiency (productivity per mm of rainfall) is a clear focus of Dr Kirkegaard and his research teams with strong appreciation for the interaction between the many aspects of agronomy and variety selection.
Ongoing research suggests earlier sowing of appropriate slower maturing or/and winter habit varieties of both cereals and canola develop deeper roots due to a longer vegetative phase. Deeper roots better utilise soil water and nutrients, with the end result higher yield potential, often combined with valuable grazing opportunities.
In lower rainfall areas, or on shallow soils, yield benefits from earlier sowing are less related to deeper roots as subsoil profiles often do not re-fill from season to season. However in medium/higher rainfall areas on deeper soil there appears to be great scope to use early sowing to capture and use water that is otherwise evaporated in summer and early autumn, or drains during winter.
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Capitalising on the potential for higher yield from early sowing Dr Kirkegaard stresses it requires appropriate agronomy.
For example in a long-term experiment at Harden, early sowing of an appropriate maturity wheat variety (April verses May) may result in wheat yield improving from 4.7 to 5.5 t/ha but when combined with 50 kg/ha extra nitrogen to satisfy the higher yield potential yield can increase to 6.0 t/ha.
Canola production in Australia has increased 10-fold since 1993 from 0.3 to 4.0 Mt and it is now Australia’s third most important food crop after wheat and barley. Like wheat, a lot of effort is being devoted to appropriate plant types to suit earlier sowing with the same findings as for cereals indicating significant yield gains are possible.
- Bob Freebairn is an agricultural consultant based at Coonabarabran. Email firstname.lastname@example.org or contact (0428) 752 149.