Grain Yield Monitor Calibration

Harvest season has begun for some of you while others are getting combines out from under the shed hoping to begin in the next few weeks. Since we are on the prefaces of what could be a great harvest season for you, I would like to take a little time and give you some information on the importance of yield monitor calibration. For those of you are engaged in precision agriculture techniques on your farm or you consult for/with those who do, a yield monitor is an important tool for evaluating production practices such as precision soil sampling, variety evaluation, variable-rate seeding, variable-rate nitrogen, etc. In addition to measuring yield, these systems allow for the recording of crop moisture, elevation, variety, and a number of other harvest variables. Maps depicting yield variations across fields can be developed and used to provide farm management decisions to improve crop productivity. However, for the information produced from yield monitors to be accurate and reliable, calibration is the most important step whether you are collecting data for yield maps and management or are just interested in seeing the instantaneous yield as you move across the field.

Pre-Season Checklist

  • Clean Grain Elevator Chain: It is very important to check the tension of the elevator chain. Look for wore paddles, loose links, and wore sprockets. All of these can cause erroneous data resulting from the way the grain impacts the yield sensor at the top of the elevator.
  • Moisture Sensor: Make sure there is not any debris from previous crops obstructing the moisture sensor channel. If so clean the sensor before starting. Also if you begin harvesting in high moisture corn like most are starting to do, some of the plant resins can obscure the moisture readings. So just be aware you may want to check the sensor during the first few days of harvest.
  • Header Height Sensor: While most people don’t pay much attention to this sensor it is important to check and make sure it is working correctly. This sensor engages and disengages the logging mechanism for the yield monitor. Incorrect acreage leads to incorrect yield estimates.
  • Distance Calibration: Very minor but it is a good idea to recalibrate or verify it is working correctly. Again incorrect acreage estimates lead to incorrect yield estimates.
  • Vibration Calibration: Make sure that before you get started harvesting you do a vibration calibration. This will correct the system for the vibration of the machine especially when the header is engaged. It is recommended this be done each time you change the header on the combine.


Calibration is the most important step in collecting accurate data.

  • Mass Flow Sensor: Harvest 5 individual loads around 100 bushels each. Weigh each individual load using a weigh wagon or truck scale. Record each weight. Once completed enter each load into the yield monitor for calibration. Note: John Deere yield monitor requires you to enter each harvest load after each weight. For AgLeader or CIH you enter the weights at the end of the 5 harvested loads.
  • Moisture Sensor: While collecting the harvest weight loads collect a moisture sample with either a handheld moisture tester or at an elevator. Most yield monitors only want one moisture reading to calibrate, so either take an average of the 5 reading or select one that is most representative of the group. I like an average.

Once these 2 steps are done you should be ready to go. One word of caution, as the season progresses and the crops get dryer it is important to do a calibration check periodically. Grain test weight and moisture will affect the accuracy of the data.

As we get closer to cotton harvest time I will send you some information regarding cotton yield monitors. We are getting an increase in cotton yield monitors in the state with growers buying modulating pickers. So to help with this Edisto REC, with the help from Clemson Extension administration, made a commitment in the last few months to purchase a portable scale to calibrate these systems.

If you have any questions or need help with calibration please feel free to give me a call or send me an email.

Thanks and good luck harvesting,

Contact Info:

Office: 803-284-3343 ext. 244

Mobile: 803-300-1031


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