Australian chaff decks show promise

From Down Under: a chemical-free tool to help manage post-harvest weeds

Chaff decks attached to the back of the combine direct weeds into confined rows, which will either compost in the pile or compete for water and nutrients with other weeds in the spring. 

A new weed management tool that’s taking Australia by storm could be a good fit for Canadian farmers as well. Chaff lining, or the practice of concentrating the weed seed-bearing chaff material in confined rows behind the harvester, has helped Australian farmers to better control weeds. While it’s too early to tell if the system is a fit for the Canadian Prairies, investment costs are minimal and maintenance is relatively simple, making it an attractive new option to some.

Rising concerns about resistant weeds have led Australian farmers to look for new means of control. Developed by a south Australian farmer, the chaff lining system has been widely adopted by Australian farmers over the last few years. Its quick and wide adoption can be attributed to the fact that it is simple, cost effective and efficient, said Tristan Freind, director of Westoz Boilermaking, a manufacturer of chaff decks located in Dowerin, West Australia.

Once attached to the back of the harvester, chaff decks concentrate weeds into confined rows, which either compost in the pile or compete for water and nutrients with other weeds come spring, explained Freind.

Benefits and challenges

Initially, Australian farmers say they are drawn to chaff lining because of its minimal start-up and maintenance costs. There are other benefits of adopting the system, said Freind. Chaff lining does not draw power from the combine and does not affect fuel consumption. Nor does chaff lining impact harvest capacity. Kits can be removed relatively easily, allowing the operator to swap back to normal harvesting without too much downtime.

“Even when kits are installed machines can be accessed easily for repairs and maintenance,” said Freind. “Other harvest weed seed control methods can restrict the ability to easily access the back of the harvester, making repairs and maintenance difficult.”

In fact, Freind hasn’t heard a single negative report from farmers thus far. With that said, the system isn’t easy to design.

“The biggest challenge that we face as manufacturers is designing an effective internal baffle system that works in all harvest conditions and crop types,” Freind explained. “Sometimes it takes three or four changes before a design is successful.”

Chaff lining kits can be attached to the back of the combine. photo: Westoz Boilermaking

Once installed, chaff lining requires discipline, he added, as headers have to run on the same tracks each year. “If the chaff line is not dropped in the same spot year after year, chaff lining is inefficient,” he said. “The fact that weed seeds are still in the paddock is a negative to some farmers.”

Jordan Bruce and his family farm 7,500 acres in south Australia, mostly wheat, barley and lentils. The main challenge he’s noticed so far is optimizing the system to allow for the maximum amount of weed seeds to enter the harvester. “Weed species that shed seed prior to harvest is an issue, and also weeds that are below the height of the header,” he said.

Bruce says the system has been successful on their farm. “We’ve had success with retaining some broadleaf weeds and certain grass weed species,” he said. “Results have definitely been visible.”

Bruce offers advice to those who are thinking about implementing the new system. Place the chaff lines on the same lines each year to concentrate the weed seeds. This will force competition, he said. Look up chaff lining examples for your specific combine, he said, as there are photos online of growers who have trialed and succeeded at fitting a chaff liner to their combines. “Persist with the design of your chaff lining chute,” he added. “It may not work perfectly at first, but once it does it will be noticeable in the next year’s crop.”

For optimal results, the chaff line should be directed to the same area of the field, year after year. photo: Westoz Boilermaking

A good fit for Canada?

Timik Farms from Camrose, Alberta had a chaff deck installed on one of their combines in August of last year. It was used on about 500 acres before they removed it in early September.

“This system didn’t work in crop yielding more than 50 bushels,” said manager Fred Niehoff. “We had it on a Case 8240 combine. It was built in Australia where they don’t have DEF systems on their equipment, which made the installation of a separation roller more complicated. It would have taken too much time out of harvest to modify.”

With a little patience, Niehoff thinks it might work, but at the time he was frustrated and couldn’t afford to leave the combine parked.

Agriculture and Agri-Food Canada research scientist and weed specialist Breanne Tidemann is also skeptical about whether or not the system will fit in Canada.

“My biggest concern is whether or not we would see a composting effect,” she said. “We have such different weather conditions than Australia after harvest.”

Tidemann, however, does see its value in terms of limiting the spread of weed seed. “You could deploy area-specific weed control, something like spraying a herbicide specifically on the chaff line and reduce the amount of herbicide applied,” she said.

She’s also drawn to the cost-effectiveness of the new weed control method. Producers might be able to start using this strategy quickly with minimal costs.

“Chaff lining — as with all harvest weed seed control methods — will be limited to controlling weeds that have retained their seeds, so weeds such as wild oat may be challenging to control with this methodology,” she added. “Overall, I think it’s a promising technique, and one I definitely want to spend some time doing some research on to better understand how well it could work here.”

About the author


Melanie Epp

Melanie Epp is a freelance farm writer.



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