Do you combine acres or bushels per hour?

Your grain loss monitor is a valuable tool, but it must be calibrated to ensure good data is driving decisions

BRANDON — When discussing combines, farmers typically compare acres of ground covered per hour. Isn’t it more logical to discuss performance in terms of bushels of grain per hour in the tank?

Talking about acres per hour is misleading. It distracts from the real issue of how many bushels your combine can harvest in one hour, said Joel McDonald in his keynote presentation to the Combine College in March.

After a decade as an engineer at the Prairie Agricultural Machinery Institute working with growers on their combines, McDonald is convinced that bushels per hour is the most significant factor.

“I tell farmers I don’t want to hear about miles per hour ground speed or how many acres per hour they can cover because that’s a meaningless number if I don’t know how many bushels they put in the tank in that one hour,” McDonald said.

“The guts of your combine don’t care how fast or how big the header. The guts of the combine only care about how many pounds per hour it has to process. That’s what determines combine efficiency. For a farmer, thinking in terms of bushels harvested per hour is a far more reliable metric.

“For example, this year we had canola running 60 bu. per acre. The year before canola was 40 bu. to the acre. This year, we have 50 percent more material going through the combine. So, it’s realistic to reduce your ground speed by 50 percent to achieve the same seed loss. Sometimes in canola, 600 bu. per hour is all you’re going to do. Other times, you might go as high as 1,000 bu. per hour.”

McDonald said a grain loss monitor is a great tool for tuning combine settings. The operator can sit in the cab and see the effect of each change.

However, it must be calibrated.

“If you just take your combine straight from the factory and take it to the field, and it’s in the green, good to go, you still don’t know how many bushels per hour. And bushels are what you get paid for. You don’t get paid for acres.

“Use the loss monitor to indicate relative increase or decrease as you change settings, but you still need to start with a base line. You should do a drop pan check while watching your loss monitor.

“On my farm, I’ll do the check in high-yielding and low-yielding areas. And I’ll do checks in ideal afternoon conditions and in tougher morning and night conditions. All that helps you put more grain in the bin, and that’s what we get paid for.”

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