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Study suggests ways to reduce soybean harvest losses

Going slow and using an air reel are two important techniques

Soybean growers can avoid major seed losses at harvest time by using air reels and driving combines no faster than four miles per hour, a new study says.

Air reels significantly decrease header losses, and between two and four miles an hour is the optimal ground speed for harvesting soybeans, says the study by the Prairie Agricultural Machinery Institute.

Of the two, ground speed is the more important, said Harvey Chorney, PAMI’s vice-president for Manitoba operations.

“If you go too fast, you miss too much,” Chorney said.

“You get a slight improvement with air reel versus no air reel. But the biggest factor that can affect what you’re leaving behind is your ground speed.”

Chorney spoke about the PAMI study during a recent tour at the Canada-Manitoba Crop Diversification Centre sponsored by Manitoba Pulse and Soybean Growers.

The PAMI study estimates harvest losses in soybeans average around 10 per cent and can run as high as 15 to 20 per cent.

According to the study, 80 per cent of soybean losses during harvest occur at the header. Soybeans are much lower on the stem than other crops and require slow speeds with flexible cutter bars and automatic header height control for reducing losses.

An auger header with no air reel can result in losses of 2.27 bushels an acre. Running the combine at five m.p.h. instead of four m.p.h. can produce header losses of 2.18 bushels per acre.

With spot prices for soybeans currently running above $10 per bushel, farmers can lose a lot of money at the combine header, according to the study.

“This represents a significant profit loss and creates a large volunteer seedbed and additional management costs the following year,” it reads.

“Any effort to decrease the number of beans left behind in the field can make a substantial difference on the economic gain of the operation.”

The PAMI study says an air reel on a header can reduce seed losses by 1.25 bushels an acre, producing a saving of roughly $12.50 per acre when compared to an auger header without an air reel.

“This indicates that an auger header equipped with an air reel can provide substantial benefit in reducing losses and increasing profitability,” the study says.

As for ground speed, Chorney said the study found little difference between two, three and four m.p.h., although four m.p.h. was the “sweet spot” for minimizing seed losses.

But when ground speed exceeds four m.p..h, that’s where the difference happens, he said.

“You’re trying to get the pods over the knife into the back of the header. When you’re going up to four miles an hour, I like to use the analogy of scooping. You’re catching the pods with some velocity inside the header, which aids it crossing the knife. That effect is good until four miles per hour. Once you get past four, what you start doing is stripping the pods off because you’re not cutting them cleanly.”

It’s also possible to lose seeds by going too slowly. Chorney said operating below two m.p.h. means you don’t have enough speed to get seeds caught within the header.

But maintaining ground speed at a certain level has to be balanced against practical matters, Chorney acknowledged.

He said he spoke with a grower who harvested soybeans last year at seven m.p.h. because he was in a rush and didn’t have time to go slower.

“I told him, do you realize what you’ve left behind?”

But the grower said he would have needed a million dollars for a second combine and couldn’t afford it.

“He realized he was leaving beans behind,” Chorney said. “But in order to get the crop off in the time window he had, he would have had to purchase a second combine. He needed 20 per cent more combine to get the beans off properly. But he was at that threshold where he would have needed two combines instead of one.

“I couldn’t argue with that.”

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