Grain Yield Monitor Calibration in North Dakota and Northern Minnesota

Yield monitors and related equipment should be calibrated prior to harvest. Properly calibrated grain yield monitors can provide a more accurate crop yield estimate by product and by location in a field. Recalibration is necessary for each type of grain harvested and may be necessary as crop and environmental conditions change.

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Hardware Inspection

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  • Re-read user manuals for yield monitor and combine prior to harvest.
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  • Mass flow sensors and moisture sensors should be checked for dust buildup and debris. Periodic cleaning during the harvest season may be necessary. Debris can affect the accuracy of the yield readings.
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  • All mechanical linkages should be functional.
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  • Impact/wear plates, paddles, pads, grain elevator chain, GPS receiver, and other components should be inspected for wear and performance. If any of these components have been replaced or removed, a full calibration will be necessary, since these changes can change the flow of grain through the measuring devices.
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  • Electrical connections and cables should be inspected for wear.
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  • Yield data from last season should be downloaded to a computer or remote drive and the data deleted from the data card to make room for new data this season.
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Software Updates

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Check for software updates for both the yield monitor console and the computer. Troubleshooting from the combine cab or office can be easier when the latest software version is installed.

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Updates for software can allow for optimal yield monitor function. Updates are necessary for optimum data collection and for downloading data to a computer. Consider backing up data onto a computer or data storage device frequently throughout the harvest season.

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Obtaining Accurate Yield Data

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Figure 1

Figure 1. Without proper calibration, yield monitor data does not provide a reliable picture of crop yield.

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Calibration at the beginning of harvest is critical to obtaining accurate yield data. Recalibration is necessary for each type of grain harvested, or if significant moisture content changes occur throughout the season. Loads should be collected in representative areas of each field. Weighing several loads and testing grain moisture content are usually the main steps in calibration; however, be sure to check with the yield monitor’s manufacturer for steps specific to your system.

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Mass Flow Sensor

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The mass flow sensor or impact sensor must be calibrated to help achieve a more accurate grain weight. Proper calibration requires harvesting three to five separate calibration loads. Each load should represent different flow rates. This can be achieved by harvesting at different speeds. Different flow rates represent different yield levels to the yield monitor. Calibration loads should be between 3,000 and 6,000 pounds, or 50 to 60 bushels. Weigh each load with a weigh wagon or other accurate scales. If significant changes are made to elevator chain, paddles, or flow sensor during harvest, it will be necessary to recalibrate. If grain test weight changes, recalibration may be necessary.

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Moisture Sensor

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While harvesting calibration loads, test the grain moisture content with a hand-held moisture meter or with a moisture meter at the grain elevator. Some growers prefer to use an average moisture reading from at least five loads. Others calibrate their moisture sensor for corn below 22% moisture and recalibrate for corn above 22% moisture. Corn at 25% moisture moves through a combine much differently than corn at 17% moisture.

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Ground Speed and Distance

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Accurate ground speed and distance traveled are necessary to accurately record yield per acre. The ground speed indicator should be working. The distance calibration should be checked against a known distance to help ensure correct distance is recorded.