Calibration and Operation to Obtain Good Yield Monitor Data

Ronald T. Schuler

Extension Agricultural Engineer

September 21, 2006

Yield data from combine monitors are not very useful unless the monitoring system is properly calibrated and the combine is operated in manner to minimize incorrect data. Calibration involves not only the weight calibration but also the speed/distance and moisture calibrations. Incorrect and inaccurate data occur primarily when the monitor is collecting the data where the combine=s forward motion is stopped or where the combine is moving forward and not harvesting the full width of the combine header.

Weight calibration is best completed by harvesting a full bin or a truck load of the crop, recording the monitor weight, obtaining a weight of the harvested crop from a truck scale and comparing the two weights. Correct the monitor if necessary.  Also check the yield monitor manual for the manufacturer=s suggested procedure. As harvesting continues, truck loads of the grain should be compared to yield monitor data to ensure the monitor remains calibrated. This calibration procedure is recommended when switching to fields or changing the harvested crop.

Most yield monitors have moisture calibration data for numerous crops. The operator should be sure the proper crop is selected. Also grain samples can be collected for moisture content determination using an accurate moisture meter to insure the proper moisture calibration of the monitor.

The forward speed or distance must also be calibrated. This procedure may require traveling a measured distance such as 200 feet and comparing that value to the monitor distance. Again, check the operator=s manual for the manufacturer=s recommended procedure. This calibration should be done under field conditions and not on a paved surface.

The yield monitor is turned on and off by a switch that is usually activated by raising and lowering the combine header. The operator should be familiar with the header position where the switch is activated to ensure the monitor is turned on and off at the proper times. This position can be adjusted for most monitors.

Some suggestions for minimizing inaccurate data during harvest:

1. minimize stopping due to machine malfunction while harvesting through good maintenance practices,

2. adjust the header width for the correct number of rows or width,

3. change the header width on the monitor as it changes during the harvesting operation,

4. raise the header immediately when the yield displayed on the monitor declines as the combine enters the headland,

5. lower the combine header just as the machine enters the crop and leaves the headland,

6. raise the combine header when stopped for unloading or stopped for any other reason and

7. properly adjust the monitor system time delay. 

The most useful yield data are obtained when the combine monitor is properly calibrated and the combine operated to minimize incorrect data. If excessive quantities of the yield data do not correctly represent the yield in the field, extremely low values near the headlands, steps can be taken to clean the data collected by eliminating yield data where yields are below reasonable values. The operator=s manual should be checked for additional information which may be unique to your monitor.