Sept. 12, 2014

We're quickly approaching harvest time and for those collecting yield monitor data, it's a good time to review practices for collecting quality data. If you're just getting started with yield monitors, recognize that developing good habits and maintaining those habits over the years will ensure that you've got good data for comparisons. We've put together a short publication on methods for improving data quality in Best Management Practices for Collecting Accurate Yield Data and Avoiding Errors during Harvest (EC 2004). This basic overview covers how to minimize errors during harvest operations.

A primary example is yield monitor calibration. Remember that a separate calibration needs to be conducted for each crop you harvest (corn, soybeans, and wheat, for example). If you're harvesting high moisture corn at the beginning of the season, create a calibration in the yield monitor for this situation. If you return to corn harvest later in the season after the crop has dried down, conduct a new calibration for the corn at lower moisture. This will help to improve your yield estimates.

Creating a calibration (high moisture corn, for instance) by harvesting small loads, weighing them, then entering that information into the in-cab display can take a bit of time. Many systems will allow you to collect four to six loads per calibration to represent the yield variation during harvest operations. Two methods are available to capture this variation: harvesting at a full header width and varying speed, or harvesting at a constant speed while varying the header cut width. Either option will achieve the same goal if performed properly, essentially varying the grain flow through the clean grain elevator. Double check the manufacturer recommendations on how to perform the calibration.

Operators also should ensure that the header position sensor is functioning properly. When the header is lowered into the harvest position, the in-cab display should show that data logging is occuring. Once the header is raised above a set position, the yield data point logging should stop. If this doesn't occur (or the header isn't raised high enough during turning in headlands), yield data points will be collected with little or no yield (Figure 1).  If these points are not removed from the yield data, yield estimates in the final yield map may be much lower than what was actually seen in the field.

Errors in yield data are unavoidable; however, proper operation of the system during harvest can help to minimize those errors. In many cases, post-processing yield data files can help to remove errors and greatly improve overall map quality. If you need help with your current yield monitoring system or are trying to collect harvest data for the first time and need assistance, please feel free to email me at jluck2@unl.edu or call 402-472-1488.

Joe Luck
Extension Precision Agricultural Engineer