There are few things more exciting than watching the numbers climb on your yield monitor—or disappointing if yields aren’t so good. How can you be sure those numbers are right, though?
“Start by making sure the yield monitor is properly calibrated on the combine,” says John Fulton, Ohio State University Department of Food, Agricultural and Biological Engineering associate professor. “It might have been calibrated the previous season, but we recommend calibrating annually for individual crops such as corn and soybeans.”
One of the easiest ways to ground truth your yield monitor is to compare accumulated grain weight on scale tickets with the monitor. If they’re similar or within a 2% margin of error, you’re good to go, Fulton says. If you’re outside that range of error, take the time to recalibrate.
It’s also key to ensure the mass flow and moisture sensors are in working order, he adds. When you visit the elevator, compare your average moisture with the elevator estimate.
You can also check yield monitor accuracy by pulling yield maps weekly during harvest. Identify any glaring abnormalities and then determine their cause.
“Look at end rows and point rows on the maps, for example. Did logging stop and start where it needed to?” Fulton says.
Operator error, such as not lifting the header high enough while turning, can log information when you’re not harvesting anything. You will be able to recognize these errors—such as readings in grass waterways, buffers and wet spots, he says.
Another common error that can skew yield map data is abrupt changes in ground speed causing incorrect area calculations for yield estimates.
Errors can make your overall field average high or low, but if you remove the non-representative data, the map will be a more spatially accurate representation. Most software packages allow you to remove erroneous data, but catching it early means you might be able to avoid that hassle by adjusting settings on the front end.
In addition to tracking bushels, yield maps spatially reflect yield variations across a field. “Growers and consultants use yield maps to identify production issues, to create management zones for seeding, fertilizer and nutrients [crop removal], for on-farm research and to create profit maps,” Fulton says.
For example, yield maps can be used to estimate nutrient removal, which supplements soil sampling information in years when samples aren’t pulled. You can use that data to determine fertility rates to maintain optimum levels. Yield maps can also be paired with input or production practices to provide feedback on research. And finally, profit maps can show which acres are profitable, which ones are losing money and even which ones aren’t worth planting.
Pair yield map data with scouting notes and planting information to make informed decisions for next year. Fulton has seen farmers pull unproductive land out of use, taking them from a $10 to $70 per acre loss to a profitable margin. In addition, he says varying fertilizer rates can save an average 7% on costs compared with a fixed rate over time.
“Yield maps set the end bookmark—what you ultimately get paid on,” Fulton says. “There are a lot of things between planting and harvest that impact yield. The key is documenting what happened and its response to improve future decisions.”