What a combine loss monitor can (and can’t) tell you

August 17, 2018

Combine loss monitors are useful for understanding whether the amount of grain being thrown out the back of a combine is increasing or decreasing, but they’re not a great tool for quantifying those losses, according to research conducted by PAMI (Prairie Agricultural Machinery Institute).

The recent project focused on understanding the accuracy of combine loss monitors, and whether it’s possible to measure actual losses in real-time, explains PAMI’s Joel McDonald:

“Rather than a unit-less bar graph or funnels or a needle gauge with just tick marks (as shown above), can we put bushels per acre with that? Can we put it in dollars per hour — something that’s going to mean more to the combine operator to help them manage their harvest loss?”

They compared actual losses behind different machines in canola, wheat, and peas versus the combines’ loss monitor readings.

“In most cases, the monitors told you when loss is increasing, but the catch is, it wasn’t a direct relationship. Sometimes as the combine loss really went up, getting into 3, 4, 5 bushels, which all combines can do, the loss monitor said losses were going up, but it didn’t say that much,” he explains, in the Canola School video below.

While sensor technology is advancing quickly with increasing automation in combines, McDonald notes manufacturers probably don’t feel it’s in their interest to tell operators how much grain they’re losing.

“Nobody wants to be first to implement this, so that’s why the public research funding is there to help push this envelope,” he says. “The end goal is, hopefully, someone will pick up this research and put on an aftermarket kit, an iPad in the combine that’s giving you more resolution, more detail on your combine loss.”

Meanwhile, the quality of the information coming from a harvest loss monitor will always depend on whether it is calibrated.

“The power of your loss monitor is when you go out there, ground-truth it and check your loss. Don’t ever rely solely on the loss monitor from last year’s calibration or a calibration from a different crop,” notes McDonald. “Get out there and check, and adjust your monitors.”


Canola School videos are produced by Real Agriculture.

You can watch all the canola school videos on this website and on Real Agriculture's Canola School page

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