Checking Yield Monitors

Yield monitors on the combine provide data that can help you make management decisions on the farm. But to make good decisions, you need accurate data.

Dennis Pennington is an Extension wheat specialist at Michigan State University. He says the mass flow sensor is the most important part of the combine to be calibrated for accurate yield data. To do this, harvest 3,000-5,000 pounds of grain, and then weigh it. As you go across the field harvesting, there are high and low-yielding areas where the flow of grain is high, average, or low. You need to calibrate these points.

"To get them, they recommend either pick your normal ground speed and then go half of that ground speed and then increase that ground speed by half again. Or, cut the number of rows that you’re harvesting," he says. "So, in the normal, you would harvest your regular header width at a normal speed, for the low yield you would basically take half the header width and harvest those until you get your 3,000-5,000 pounds of grain."

The moisture sensor must also be calibrated. Even if the mass flow sensor is accurate, you can still get erroneous yields if the moisture sensor is off.

"The best way to do that is to run some grain through there, take it to a grain elevator or someplace where they’ve got a quality moisture tester, and then run a sample," says Pennington. "There’s a calibration function within each of the monitors, doesn’t matter what brand you’re running, they all can calibrate for that."

Your owner’s manual will tell you how to calibrate the sensors, how often it should be done, and for what crops.