Several years ago I rode with a farmer and his yields on the monitor as he was shelling corn seemed off.
"Yeah it's probably off 20 bushels per acre," he finally said. "I at least get an idea of how one area does relative to another. I don't want to take time to calibrate it."
Off 20 bushels per acre? Why have the monitor in the cab? I'll leave it to the engineers to determine if a monitor is off that fair, if it's reflecting differences in the field at the same percentage all over the field or not.
David Phegley took a few minutes one afternoon last week to work with his seed dealer and calibrate his combine for soybeans. The dealer brought a weigh wagon, and Phegley would combine a short section, then weigh it in the weigh wagon. Then the pair would compare the two weights to see if his monitor was still on target. He typically calibrates twice each season, once for corn and once for soybeans. Having a weigh wagon in the field makes it much easier to calibrate than having to run a small amount, haul it in on a truck and either weigh it over the farm scales or take it to an elevator to weigh it.
Some experts say that if test weight varies in corn a considerable amount, say from 52 pounds per bushel to 62 pounds per bushel for another hybrid, it might be worth recalibrating the monitor. The sensor that records flow past the device can't account for differences in test weight in most cases. Heavier corn might suffer a yield penalty vs. chaffy corn if the yield monitor is simply measuring volume flowing through and is not corrected or recalibrated for test weight. Calibration is usually a relatively short process.
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