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Yield Monitor Calibration for Fall Harvest

September 24, 2019

Harvest has not yet started here in Ohio, but it is good to remember to make sure your yield monitor is setup and calibrated properly. Geo-referenced yield data (i.e. yield maps) are being used to provide precision agriculture insights and recommendations at the field level. Yield maps not only help growers understand end-of-year performance within fields, but also can be used to characterize in-field variation. Information about this variation is often used by service providers to deliver prescriptions, recommendations, or other information back to the farmer. Because yield maps continue to be an important data layer to learn from and help drive changes or decisions at a field level, proper management of the yield monitor is critical to generate accurate and reliable yield data. Grain moisture and test weight, along with grain flow through the combine, will vary within passes and across fields. Therefore, the flow and moisture sensors on combines must be calibrated to these expected conditions in order to log accurate data.

Why calibrate your yield monitor?

  • It helps collect accurate yield estimates so yield variability across the field is accurately represented by the yield map; especially this growing season considering the expected field variability.
  • It can be used to generate accurate prescriptions (Rx’s) and profit maps based on your yield maps. The generation of variable-rate fertility and seeding maps are frequently based on yield maps with few services creating profit maps to evaluate areas of profit and loss.
  • Yield maps have become a baseline data layer to assess management risks and the allocation of inputs. Precision agriculture practices have shown to provide feedback to improve profitability and helping confirm the best practices and input selections for a farm operation.

Yield monitor best practices to use pre-harvest and during harvest

  • Be sure to update firmware and/or software for the yield monitoring systems. If necessary, contact your equipment or technology service provider about available firmware updates and where they can be downloaded.
  • Most yield monitors use a mass flow sensor at the top of the clean grain elevator. Due to the grain impact, the plate will wear to the point of developing a hole if it isn’t replaced soon enough. The wear that occurs changes the reading from the mass flow sensor. Be sure to replace the plate if wear is evident. Don’t neglect to recalibrate after replacing yield monitor components. This recalibration is necessary to ensure accuracy of the yield monitor. A more simple explanation is that a worn impact plate can result in an incorrect yield reading on your display. It is important to not overlook the yield mapping system as a worn component will throw off yield readings.
  • Update and/or configure DGPS. Software related to auto-steer, yield monitors and other GPS-based systems require separate attention. Licenses must be renewed. Calibrations and parameters must be updated or confirmed — especially if the display in the combine cab was used for planting or spraying earlier in the year. It’s necessary to meticulously switch every setting and value, from machine dimensions to type of crop and operation, so they are relevant to harvest operations.
  • Check auto-steer operations and that previously used AB/guidance lines are available within the display. Remember, you may have to adjust sensitivity settings.
  • It is also important to calibrate yield monitors for every crop, each season to ensure that all data being collected is as accurate as possible. The yield monitor needs to “be taught” how to convert the readings from the mass flow sensor into yield; therefore, it is necessary to show the yield monitor the range of yield conditions it will encounter throughout the season.
  • It is wise to periodically check the calibration throughout the season to be sure the data being collected is still accurate.
  • Grain moisture and density can vary between crop fields and, at times, vary significantly within a field. Accounting for changes in grain moisture and density improves the accuracy of yield estimates.
  • Remember to recalibrate if harvest conditions change. For example, if: yield monitor components are replaced or adjusted; grain moistures increase or decrease by over 6% to 8%; or after a rain shower but still dry enough to harvest.
  • The use of grain carts to calibrate yield monitors can be acceptable as long as it weighs accurately compared to certified scales. One should make sure the weigh wagon is on level ground (less than 2% slope) and stationary for a few seconds before documenting the weight.
  • Bring along your field notes so you can review them during harvest as crop conditions vary or issues are observed.
  • While harvest is a busy time, taking notes and images during harvest (especially if conducting on-farm research) can be valuable data when finally sitting down for post-harvest analysis and summary. We all forget, so notes and images can help document important information.

For more information on calibrating yield monitors, check out the Ohio State Precision Ag website at plus read the Extension Publication “Tips for Calibrating Grain Yield Monitors — Maximizing Value of Your Yield Data” at

Source: Ohio State University