WA farmers beat weeds at harvest

By: Anna Game-Lopata

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Wheat farmers in the Albany Port Zone of Western Australia are innovating to manage weeds with chaff carts and windrow burning

WA farmers beat weeds at harvest
Wheat farmers use alternative methods like modifying chaff carts to eliminate weeds

A new booklet produced by Western Australia’s Department of Agriculture and Food (DAFWA) shows how growers can reduce the use of herbicides.

Released to coincide with this year’s harvest, the booklet reveals how the use of alternative methods for weed management is reducing costs and increasing productivity for growers in Western Australia’s southern wheat belt.

An initiative of the Regional Cropping Solutions Network (RCSN) and the Grains Research and Development Corporation (GRDC), The Effectiveness of on-farm methods of weed seed collection at harvest time highlights the operations of seven wheat growers in the state’s Albany Port Zone.

The booklet shows how each of the growers adapt chaff carts and modify straw spreading toenable weed seeds to be burned or baled more easily.

DAFWA Project Officer Alexandra Douglas says weed management is costing farmers across Australia in excess of one billion dollars a year.

"In combination with inputs like fuel, fertiliser and spraying time, controlling weeds could represent a third of growers’ input into their crop," Douglas says.

Douglas says the booklet, available online, is directed at growers around Australia considering starting out in harvestweed seed management.

While there are slight differences across regions, she says the information in the booklet is easily applicable.

"The seven case studies in the booklet include information about the crops growers are producing, annual rainfall and soil conditions so growers outside WA can compare their own operations more accurately," Douglas says.

Chaff carts, in most cases bought from manufacturers, are towed behind the header, with chaff and fines taken up using a blower or a modified conveyor arrangement which prevents chaff and seed losses.

When the cart is full, an alarm sounds allowing its contents to be dumped.  Chaff dumps are then left to be burned in autumn or used as feed for stock.

"Many growers utilising this method no longer need to purchase supplementary feed," Douglas says.

The narrow windrow method, also detailed in the booklet, requires the replacement of spreaders with flaps growers have easily hinged or fixed to the back of their header. The windrow can then be baled or burned.

"If you can reduce the size of the windrow to about 50 cm or as narrow as possible, fuel can be concentrated into a denser area which produces a longer, hotter longer burn."

"This kills more weed seeds and a wider range of weed species," she says.

Douglas says one grower in South Kukerin, who has been narrow windrow burning for many years, has devised a method to separate chaff fraction from the bulk of the straw.

The farmer, who modified his header with pieces of tyre and carpet, lays chaff on top of the bed of stubble which ensures all the weed seeds are burned.

 If the stubble is baled, this method facilitates collection of all the chaff and weed seeds without losses.

"It’s basically a funeral pyre for weed seeds," Douglas says. 

The booklet also contains information contributed by DAFWA partner the Australian Herbicide Resistance Initiative (AHRI) based at the University of WA.

AHRI, a national research and support system for herbicide resistance management researched and compared the costs per hectare and effectiveness of each weed control outlined in the booklet.

"This includes the use of new and second hand chaff carts, windrow burning and the Harrington Seed Destructor," Douglas says.

But she adds the booklet shows farmers utilising chaff carts and windrow burning or baling are successfully controlling weed seeds before they get into the soil.

"While achieving a low seed bank won’t just happen straight away, the weed seed control methods growers in southern wheatbelt of WA are using during harvest have a flow on effect over several years," she says.

"Once you have a lower seed bank and a smaller weed population, you have the option of dry sowing and you can reduce your reliance on in-crops herbicides."

Download the booklet

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