Chaff deck designed to capture and control weed seeds in combine wheel tracks


Every year at harvest, weed seeds are spread across the field through the back of most combines, setting the stage for weed competition across the entire field.

A company in Western Australia has developed a tool to confine those weed seeds to the combine’s wheel tracks.

The EMAR Chaff Deck replaces the chaff spreader on the back of a combine, collecting the chaff coming off the sieve, and dropping it in the already-compacted wheel tracks via two hydraulically-driven conveyor belts. The straw is still chopped and spread by the spreaders. (The company says over 95 percent of weed seeds are in the chaff.)

The idea was developed after Karl Raszyk, a farmer in Western Australia, acquired a field infested with resistant ryegrass in 2008. Raszyk discussed the problem with custom harvester James Buttle, who created a prototype chaff deck system.

An EMAR Chaff Deck on display at Canada’s Farm Progress Show in Regina.

“We needed to stop spreading the weeds over the paddock, so we figured if we could clean up the bulk of the field and bring the weeds into the wheel track, we might end up with a bit cleaner field,” explains Buttle, in the video below, filmed at Canada’s Farm Progress Show in Regina last week.

“It’s gone from something that a lot of people sat on the fence and watched, to quite a few units out there — somewhere around 350 units (in Australia),” he says. Several units have also been sold in the UK.

In a wet year, the chaff and weed seeds will rot or compost in the tramline. In a dry year, there’s usually just enough moisture retained by the windrow for the weed seeds to germinate and choke each other out, says Buttle.

The concept works best in a system where combines follow the same path or A-B line every year, including, but not necessarily a controlled traffic farming system.

“After one year we could see we’d moved the chaff into the lines. Second year, you could see you’re slightly cleaning it, and third year, you could see numbers were dropping,” he says. (continues below)

Some producers have also set up their sprayers with nozzle control to target the weed seed windrows in the wheel tracks, which Buttle says account for around seven per cent of field area.

“They’ll just spot spray along the wheel tracks, if you find an area where it has blown out or you haven’t got it right, you just flick a switch, turn the whole sprayer on — just using a lot less chemical and getting a lot more hectares on a tank-full,” he explains.

Anecdotally, potential side benefits from the weed windrow system is that it also reduces dust during spraying and wind erosion in dry conditions, he says.

Buttle says they’re going to be testing a unit in Western Canada this fall. EMAR is working with Redekop Manufacturing on distribution in North America.

An EMAR Chaff Deck in action:

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