WANTFA pushes to maximise dry sowing potential

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Two men and a woman at a conference

(From left) David Minkey, Lauren Celenza and Matthew McNee worked on the Western Australian No-Tillage Farmers Association dry sowing project.

PHOTO: Cox Inall Communications

Dry sowing with full crop or pasture residue retention continues to be a popular practice across the Western Australian grainbelt, especially in low-rainfall zones, because of the potential to maximise water use and operational efficiencies.

The main risks associated with dry sowing are weed management, crop establishment and frost.

The factors contributing to these risks and potential opportunities from dry sowing have been investigated by the Western Australian No-Tillage Farmers Association (WANTFA) during a three-year project funded by the GRDC.

WANTFA surveys and analysis of Planfarm benchmarking data from 2011 and 2012 indicate about half of WA’s low-rainfall growers undertake some dry sowing and the average area is about 32 per cent of their cropping program.

In medium and high-rainfall zones, 43 and 26 per cent respectively of growers surveyed by WANTFA said they carried out some dry sowing. The average extent was 23 and 30 per cent of their cropped area.

WANTFA executive director Dr David Minkey says the bulk of surveyed growers who used dry sowing were confident it had increased farm profitability over time.

Dry sowing can boost crop yields, increase sown area and reduce the risks of end-of-season heat-stress events.

Dr Minkey says 2011 Planfarm benchmarking data showed a 0.5-tonne-per-hectare wheat yield benefit in the low-rainfall zone when growers doubled dry-sown area from 10 to 20 per cent.

“When there was more than 150 millimetres of growing-season rainfall, growers in all zones who sowed more than 40 per cent of their wheat crop dry achieved higher overall crop yields than growers wet-sowing crops,” he says.

Agricultural Production Systems sIMulator (APSIM) modelling work found the average yield difference between a farm with up to 100 per cent dry seeding and a farm with no dry seeding ranged from a 0.5t/ha increase to a 0.2t/ha loss.

Yield increases were higher where zero to 33 per cent of the total crop was dry sown, on heavier soils and in lower-rainfall areas.

Dr Minkey says dry sowing reduced risks of heat stress during grain filling across seven focus sites.

“For example, at Mullewa on a heavy soil across 6000ha, the average proportion of the crop that was heat stressed almost halved from 31.3 per cent with no dry sowing to 16.7 per cent with up to 100 per cent dry sowing,” he says.

Dry-sowing risks

Growers surveyed by WANTFA indicated the biggest risk of sowing crops early was germination of weeds alongside the crop. This increased reliance on in-crop selective herbicides and the potential for evolution of herbicide resistance.
Dr Minkey says dry sowing is best done when weed seedbanks are low to reduce the risk of yield loss from weed competition.

Early sown crops that flower during frosts are another risk of dry sowing.

However, APSIM modelling found increasing the level of dry sowing in a cropping program led to only minor increases in the average proportion of the crop frosted during flowering.

Dr Minkey says in most cases – depending on location – the potential yield advantages from dry sowing outweigh the increases in area frosted.

He says variety selection allows growers to manipulate the spread of flowering dates for dry-sown crops to help mitigate frost risks.

Management strategies

Growers surveyed by WANTFA said a low weed seedbank was the most important management strategy when dry sowing, followed by stubble retention and use of no-till.

Dr Minkey says pre-emergent herbicide is also a vital aspect of dry sowing wheat.

He says crop residue retention after harvest is also integral to success when dry sowing with no-tillage fallow systems because of the beneficial effects on soil-water availability for crops.

More information:

David Minkey
08 6488 1647
david.minkey@wantfa.com.au

A fact sheet on Time of Sowing is available at: www.grdc.com.au/GRDC-FS-TimeOfSowingWest

End of Ground Cover #110 (Western region edition):

Read the accompanying Ground Cover Supplement: Ground Cover Supplement 110: Cereal foliar fungal diseases

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