Ferrie: Combine Monitors Show Strong Yields But Aren’t Reality

10:44AM Oct 04, 2019
Boots in Field
Boots in the Field Report with Ken Ferrie
( Crop-Tech Consulting )

Corn growers in Illinois are seeing a repeating theme in fields this fall: big numbers on their combine monitors but whole-field yield averages that aren’t adding up to what they expect.

“Farmers are telling me, ‘I can’t wait to see the yield maps, so I know where all this corn went.’ We’re seeing too high of numbers on monitors for the yield averages,” notes Ken Ferrie, Farm Journal Field Agronomist and owner of Crop-Tech, Inc., near Heyworth, Ill.

If you’re experiencing similar issues, Ferrie says to pull out your drone pictures and see how those fields looked between emergence and knee-high growth. That will help explain why things don’t match up now.

As a result, Ferrie is shifting his 2019 corn yield projections downward.

“My expectation now is that this year’s corn crop could be more like 40-bu. to 45-bu. behind last year if these crop reports don’t pick up soon,” he notes.

Soybean yields also show a marked decrease in performance from the April through late-May plantings.

“We had some April beans coming in at the 80-plus mark, early May beans are coming in at the low 70s, and later May beans are dropping down into the low to mid-50s,” Ferrie says.

He adds that the extreme corn and soybean yield fluctuations have many farmers just wanting to put this year behind them as soon as possible and set their sights on 2020.

“A grower told me the other day ‘I don’t think I’ll learn anything from this year’s yield maps, because this year has been so out of the normal. Is it really worth the time to calibrate my yield monitor—can’t I just use last year’s calibrations and be done with it?’”

The short answer, Ferrie says, is no.

“This year’s crop is not the same as last year’s in test weight, flowability and harvestability. You’ll need a higher flow range to catch these wide yield ranges,” he explains.

Furthermore, he says, tough production years provide the best yield maps.

“They’re what I call the money maps. They help you learn more about the characteristics in your field and develop a good plan of attack in fields moving forward,” Ferrie notes.

Still, he acknowledges that this year is one of the toughest today’s farmers have experienced, and that a tough harvest remains for this fall. Harvest has been further complicated in the past week by rain—as much as 5” to 7” in parts of Illinois.

Ferrie says the current combination of saturated soils and warm temperatures doesn’t bode well for corn yields, especially in the early May planted crop.


“We’ll have rapid development of crown rot and stalk diseases,” he says. “In about two weeks you’ll have two types of corn: down corn and corn that’s going down.”


The only bright spot in that dismal prediction contains considerable irony: Heavy rains last spring meant that many farmers were unable to plant in May.

However, if you do have May-planted corn, listen to Ferrie’s Boots In The Field podcast for his insights and harvest-management recommendations:

Tools to Help with High Moisture Harvest

Ferrie: Don’t Bin Corn Contaminated By These Two Ear Rots

This Year's Prevent Plant, Next Year's Problem Fields