Farmers who leaned hard on anhydrous ammonia last fall could be in for an unwelcome surprise this spring. Despite having enough N on the books, many fields of corn across the Midwest are likely to struggle soon after planting—thanks not to how much nitrogen was applied, but where it is located now in soils.
Ken Ferrie says the current situation came about as a result of prices and product choices that drove many growers to change their N programs last fall.
“Due to price, some guys cut out or pulled back on their MAP and DAP and AMS,” says Ferrie, Farm Journal Field Agronomist. “Many farmers put on their N—all their N—as anhydrous ammonia last fall due to that price difference between liquid and smoke.”
Those choices made financial sense at the time, but they also resulted in more nitrogen being placed deeper in the soil as NH3 — away from where young corn plants can access it this spring.
“If we dropped the dry last fall and put all of our N needs on as anhydrous ammonia, we have nothing to fight the carbon penalty stage,” Ferrie says. “The NH3 band is too deep. It’s below where the ‘fence post rots off.’ Corn roots will have to grow to it to pick it up.”
That creates a Catch-22 situation.
“The challenge is, roots will need to grow to find the nitrogen, but the carbon penalty will have them stalled out,” Ferrie explains.
Ferrie shares the example of one grower he works with who normally applies 220 pounds of nitrogen per acre, split between dry fertilizer and anhydrous. This year, that grower dropped the dry program and instead applied 250 pounds of nitrogen as fall anhydrous.
“His question: Will he still need to worry about the carbon penalty with the extra 30 pounds of nitrogen he has on? The answer is, yes. His corn will stall out for a period this spring,” Ferrie says.
How Big Is the Yield Risk?
In Ferrie’s field research, the yield impact from corn crops stalling out early in the season is clear.
“With corn on soybeans, it’s not uncommon to see a 15- to 20-bushel loss per acre,” he says. “With the G and L1 hybrids, it could get to be 15 to 30 bushels. And it gets a lot worse in corn-on-corn.”
Despite those potential yield losses, he says some growers still downplay the issue.
“This grower says his neighbor told him he has corn turn yellow every year, and he says it never affects yield,” Ferrie recounts. “Well, if you don’t check it, you’ll never know. Ignorance is bliss.”
If yellow corn in the spring has become part of your farm’s “normal,” Ferrie offers a pointed warning on hybrid choice. “If yellow corn in the spring is your MO—you just don’t feel right without having some yellow corn—I would not plant G or L1 hybrids—those that flex in girth and early length,” he says.
Inches That Matter: Banding and Carbon Penalty Rates
Ferrie’s field studies in central Illinois help quantify the amount of nitrogen needed near the surface to pay the carbon penalty.
“Our studies here show us that it takes about 60 pounds of N, minimum, placed where the fence post rots off, for bean stubble to pay this carbon penalty, and a minimum of 100 pounds worth when we’re in corn-on-corn,” he says.
One common approach growers use to build that total amount is with surface-applied fertilizer.
“Typically, we take what was surface applied as our fall fertilizer—let’s say 30, 40 pounds—and then add more surface-applied spring nitrogen to it to get to that minimum for our crop rotation,” Ferrie explains.
Another option is strategically banding nutrients near the row with the planter or a row freshener. “When it comes to keeping small plants happy, inches matter,” Ferrie notes.
He emphasizes how close the bands need to be.
“Staying within 2” to 3” of the row makes a big difference, so those crown roots can find this N in that band before the carbon penalty kicks in,” Ferrie says. “Banding some N with the planter or row freshener allows you to cut these minimums in half.”
By putting nitrogen where young roots can reach it early—near the surface and close to the row—growers can help corn push through the ugly phase instead of being stuck and languishing in it.
Don’t Let The Neighbor Decide When You Roll
Nitrogen isn’t the only factor that will shape how well corn roots perform this year. Ferrie warns that spring tillage timing and traffic decisions will also have lasting consequences.
“As our thoughts turn to spring tillage, getting the seedbed ready, remember, 80% of the compaction calls I will go on this next summer will be caused by the first pass in the spring,” he says. “Yes, the one you’re getting ready to make.”
He cautions against letting social pressure dictate when to roll.
“Don’t let the coffee shop or your neighbor set when you go to the field,” Ferrie says. “Make the decision based on your own field conditions.”
You can listen to Ferrie’s complete recommendations on spring nitrogen use in his current Boots In The Field podcast, available at the link below:
