In-Field Tips for Collecting Accurate Yield Monitor Data for Harvest 2016

In-Field Tips for Collecting Accurate Yield Monitor Data for Harvest 2016

Graph showing 2 methods for yield monitor calibration
Figure 1: Two methods for varying clean grain elevator flow for yield monitor calibration: method 1 (in green) uses constant speed with varying cut-width; method 2 (in blue) uses constant cut-width with varying speed. Either method can be used to generate calibration loads (points in red) for your yield monitor.

It’s that time of the year again, and many folks are already hitting the field for harvest 2016. For those who collect yield monitor data, the first few days of the harvest season are a good time to ensure that you’re collecting accurate information. The first item on the yearly checklist should be verifying that firmware is up to date on the in-cab monitor and your GPS system. This may require a check with your dealership or a visit to the company website. System software needs to be checked every year to make sure you’re running a current version.

Perhaps the most critical need is to calibrate the yield monitor as it affects yield estimates across all of your fields. While some operators use calibrations stored in the display from previous years (always double check to see how well previous calibrations are performing), most will need to perform new calibrations. For each calibration, try to conduct separate loads that span the variability (high to low) that you may expect to see when harvesting fields. Generally you can change combine speed or header cut width to vary crop flow through the machine to create this variation while calibrating. Figure 1 shows an example of how different calibration load points (in red) could be created by changing speed or cut-width to vary the flow rate through the machine.

In general only 3,000 lb to 6,000 lb of grain are needed for each of these calibration loads. Harvesting a full semi-load of grain per calibration load point won’t necessarily improve calibration accuracy. Some yield monitors may only allow a two-point calibration, so it’s best to try and calibrate for a point of high flow, then one for a lower flow rate through the machine.

Remember that separate calibrations are needed for different crops (e.g., corn or soybeans) and accuracy will generally improve when calibrating for significant moisture variability for a crop (e.g., high and low moisture corn). If you’ve adopted a more recently commercialized optical yield monitor system (such as available from CLAAS, Trimble, and Raven, for example), test weight measurements become even more crucial when you change between different hybrids and crops.

In the end, remember that most well calibrated yield monitors should be able to estimate yields within 1% to 3% on a full-field basis. When looking at the sub-field scale, you’re likely to see errors exceeding 3%.

Further Resources

If you are interested in reading about these issues in slightly more detail, see the Nebraska Extension publication, Precision Agriculture: Best Management Practices for Collecting Accurate Yield Data and Avoiding Errors During Harvest.

If you want to read more about how these errors can impact yield maps or to view post-processing techniques for removing errorsm see another Nebraska Extension publication, Improving Yield Map Quality by Reducing Errors through Yield Data File Post Processing.

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