A yield monitor must be calibrated to provide accurate yield data. Calibration must be performed for each type of grain harvested at the beginning of the harvest season. Accuracy usually improves when several loads are used to perform the calibration. Re-calibration should be performed as necessary, especially later in the season as average moisture content drops or when there is a significant change in crop conditions. The accuracy of a yield monitor depends not only on its design, but on how carefully the calibration procedure is followed.
Some companies offer a training session or video tapes to teach calibration.
These procedures vary considerably among manufacturers, but all require carefully recording the weight of grain, which can become a logistical problem on some farms. Operating a combine equipped with a yield monitor The final appearance of a yield map depends on how the combine is operated. Frequent stopping or sudden changes in speed can cause erratic yield data due to the delay and smoothing phenomena associated with the combine separating system. The combine must be operated on a uniform swath width to ensure accurate yield data. The width of the header must be manually entered into the monitor to accurately calculate yield.