Combine yield monitors need care and calibration to provide accurate crop information. Many combines are equipped with yield monitors that are linked with global positioning systems (GPS) to collect site-specific yield data for use in future management decisions.

""However, yield monitors have mass-flow, temperature, moisture and speed sensors that require regular inspection and calibration, plus the operating system needs user-supplied input information to ensure the yield data is accurate and usable,"" says John Nowatzki, North Dakota State University Extension Service agricultural machine systems specialist. ""During harvest time, it can be time-consuming to calibrate yield monitors, but improperly calibrated yield monitors generate useless or difficult-to-interpret data. Taking the time to properly calibrate a yield monitor will be appreciated later when using the data to make future management decisions."

The first step in using yield monitors is for the operator to become familiar with the equipment and the information provided by the manufacturer, such as user manuals and training videos. Check with your dealer for this information and additional tips on calibration. Each yield monitor has a specific way to be calibrated that is outlined in the manufacturer's operator manual.

Check the yield monitor memory device to make sure it is working properly. The data generally is stored on a removable memory card or compact flash card. Remove the card and insert it into a computer card reader to check whether data can be copied to and from the card.

During the harvesting season, copy the data regularly to a computer and make backup copies to ensure the data is not inadvertently lost. Another technique is to have a supply of extra memory cards to regularly exchange in the monitor and then mark each card with the date and fields as it is removed from the monitor.

Make sure your memory card is properly installed in the yield monitor and check for proper communication between the card and the display monitor. Usually, an error message will appear on the display if there is no communication with the card.

Inspect the mass-flow sensor. Usually, it is mounted on the top of the clean grain elevator coming into the grain storage tank on the combine. Look for wear on the grain elevator and missing or worn paddles. Check to make sure that the spacing between the paddles and the top of the elevator meets the manufacturer’s requirements. Look for wear on the flow sensor’s impact or deflector plate.

Raise and lower the header to make sure the stop height switch operates. It may be necessary to adjust the header height switch to accommodate the preferences of different operators during harvest. Set the row width or the number of rows for a row-crop header.

Set the appropriate width of a cutting platform header or swather width for windrowed grain. Check to ensure that the ground speed indicator is working. Compare moisture readings from the yield monitor with other moisture testers. Also, compare the yield monitor ground speed sensor with the combine speedometer and the GPS-monitored speed.

Common methods of calibrating yield monitors include using weigh wagons in the field or by transferring a given amount to a truck and weighing it at a commercial scale or grain elevator. Harvest calibration loads should be done at different areas of the field to take into account varying crop yields. Avoid starting calibration loads on the edges of fields, in weed patches or areas of major topography changes in the field. Hillsides and rolling ground can impact calibration data because of how the grain impacts the flow sensor.

""Calibrate for each type of grain every year because the combine operation can change from wear,"" Nowatzki says. ""Yield monitors may require separate calibration for different moisture levels in grain. For example, corn that is harvested at 20 percent moisture, compared with 16 percent moisture."

During the harvest, yield monitoring accuracy can be influenced by the combine operator as well as harvesting conditions. For example, operating the combine with the harvesting system engaged, but without crop flowing through the combine, inaccurately will reduce the recorded yield.

Operators need to turn the monitor off at corners or at the ends of rows.

The impact plate in the monitor will be less accurate if sap and dirt build up on the impact plate, so operators need to periodically check and clean the plate if necessary. Operators need to regularly check to make sure the GPS is operating and receiving data from the GPS satellites and that the monitor is turned on.

NDSU Agriculture Communication