There are few things more exciting for a farmer than watching the numbers climb on the yield monitor. Let’s not talk about the disappointment if yields aren’t so good. How can you be sure those numbers are right, though?
“You need to 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 last year 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 with a scale—compare accumulated grain weight on scale tickets with what the monitor indicates. 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 important to ensure the mass flow sensor and moisture sensor are all in good working order, he adds. You can double check moisture when you visit the elevator by comparing your overall average with the elevator estimate.
Pull yield maps weekly during harvest to check for glaring abnormalities caused by the combine or a poorly calibrated monitor.
“Use this information to identify issues and adjust settings on the monitor to improve data quality,” Fulton says. “Look at end row and point rows on the maps, for example. Did logging stop and start where it needed to?”
Operator error, such as not lifting the header high enough while turning, can also log information when you’re not harvesting anything. You will be able to recognize these errors—such as, readings within grassed waterways, buffers, wet spots, etc., he says. Other common errors that can skew yield map data include abrupt changes in ground speed causing incorrect area calculation for yield estimates.
Errors could make your overall field average high or low, but if you remove that non-representative data, the map can become more accurate representation spatially. Most ag software packages allows you to remove erroneous data, but catching it early means you might be able to save that hassle by adjusting settings on the yield monitor or worse, not having quality data for post-harvest analyis.
Take advantage of accurate yield maps. “Yield maps are a verification of yield and spatially reflecting how yield varied across a field,” Fulton says. “I see growers and consultants use them for several reasons: identify production issues, management zone creation for seeding and fertilizer, nutrient management (crop removal), on-farm research and profit mapping.”
Maps can be used to estimate the nutrients removed from a field helping to supplement soil sampling information in years one doesn’t sample. You can use that data to determine fertilizer rates to apply in the future to maintain optimum soil fertility levels. Farmers who perform on-farm research can see yield response to aspects like seed population or production practices and learn what works best for them. And finally, profit maps can show what acres are profitable and those that are losing money. In some cases, the decision might be to not plant areas that consistently lose money.
Pair what you see on yield maps with scouting notes and planting information to make decisions next year. Fulton has seen farmers take unproductive land out of use, taking them from a $10 to $70 per acre loss to a profitable margin. In addition, he says variable rate fertilizer can save you an average of 7% on costs compared to fixed rate over time, for example.
“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 what response it caused to improve future decisions.”