Ferrie: Beat The Carbon Penalty While Using Less Nitrogen

( Darrell Smith )

Can you cut your total nitrogen (N) rate if you put some on with the planter? The short answer—maybe but be careful.

“Any amount applied with the planter in a band has the same horsepower as twice that amount in a broadcast application,” says Ken Ferrie, Farm Journal Field Agronomist in his Boots in the Field podcast. “In that context though, I’m talking about the carbon penalty.”

His research in Illinois shows it takes 60 pounds of N for corn after beans and 100 pounds of N for corn after corn to keep the corn crop from slowing down during the carbon penalty stage. During that time, you need to provide 60 to 100 pounds of N near the ground surface, where the plan roots can readily access the nutrient.

Getting caught in the carbon penalty in corn after soybeans typically just means the plant slows growth and is a lighter color. In corn after corn, there is a more drastic change in color and growth patterns that Ferrie calls the ugly corn phase.

“Any band with the planter has a two-times effect when it comes to paying the carbon penalty,” Ferrie says. “So, if you put 30 pounds on with the planter that would have the horsepower of 60 pounds broadcast.”

However, that doesn’t mean you can cut your nitrogen application by 30 pounds, he continues. The efficiency comes in getting you through the carbon penalty but not enough to cut total rates by 30 pounds. Broadcast applications aren’t lost, they’re mineralized back in periods of net mineralization.

If you band nitrogen, Ferrie says you will improve overall efficiency, but it’s usually only around 10%.

“So, if you were to band 30 pounds with the planter and 120 pounds side-dress, that 150 pounds would act like 165 pounds—so, yes, you could cut your rate by 15 pounds in this case and end up as good or better than broadcasting 165 pounds in the spring,” Ferrie explains.

Not all fields are equal

“For guys bringing prevented plant acres back to corn, the carbon penalty will differ depending on how those acres were treated,” he says.

Here are a few tips for managing the carbon penalty on these acres:

  • Cover crop and overwintering covers: Treat like corn on corn.
  • Clean of weeds and cover crops: Carbon penalty will be less than corn on beans, but you’ll have to manage for fallow fields, which means a focus on phosphate. He also recommends adding sulfur.

Bottom line. Remember that nitrogen is the gas that makes corn grow. Don’t step over a dollar to pick up a dime—feed the crop what it needs, and make sure you’re not confusing the efficiency you’ve gained with banded N.

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