Last fall, a number of farmers in central Illinois told Ken Ferrie they were thinking about shifting acres to corn on corn for 2025, because the crop penciled out better than soybeans. Back then, only five or six months ago, it was mainly talk.
“But now growers are asking us to change their spread maps,” says Ferrie, Farm Journal Field Agronomist and owner of Crop-Tech Consulting, Heyworth, Ill. “When we start changing spread maps and shifting bean MAP to corn, we know growers are actually shifting acres to corn on corn.”
He adds that as farmers make the shift to follow the money they hope will be in corn, they need to be cautious. “Don’t make the shift on today’s market without protecting yourself,” Ferrie advises.
That’s sound advice and timely. If the window of opportunity to take crop insurance is still available, now is the time to consider it.
Here are some of Ferrie’s agronomic recommendations to help those farmers new to corn on corn create success for this season:
1. Use realistic yield goals. As a rule of thumb, plan on a 10-bushel reduction to your corn on corn yields over rotated corn.
“I know the experienced guys say their corn on corn out-yields their corn on beans, but that’s when we’ve got four or five years of corn on corn rolling nutrients forward,” Ferrie says.
If you aren’t experienced with corn on corn, that is unlikely to be your result. “The first year of corn on corn (the second year of corn) tends to be the roughest,” he says.
2. Plan on more insects and disease pressure. With insects, the main challenge is corn rootworm.
“If you’ve been using crop rotation to control your rootworm, you’ll need to add a trait or an insecticide,” Ferrie advises.
In addition, disease pressure will be higher in corn-on-corn acres, as well. This problem can usually be managed by hybrid selection and/or fungicide use.
“I would recommend not using the same hybrid in the field that you used there last year,” Ferrie says. “Stacking the same hybrid back-to-back in fields ups the chance of expressing the weakness of that hybrid.”
3. Be ready for the carbon penalty. Ferrie says paying the carbon penalty is something that gets new corn on corn growers in trouble most often.
Last year’s carbon left in the field will need to be decomposed to recycle the nutrients in it. This is done by the soil biology. To do this, it will consume phosphor, sulfur, nitrogen out of your soil.
Your corn plants cannot compete with the massive amount of biology out there, Ferrie notes. If the carbon penalty is not paid, your crop will stall out – sometimes for weeks – causing yellowing and stunting in the corn. How severe the carbon penalty is depends on a number of things.
Ferrie says to help you determine the potential severity, answer these four questions: How much residue needs to be decomposed? How much did the residue break down last fall or this winter? Where is the residue located? Is it on top of the field, or is it buried?
“This residue will cause a biological explosion when the soil temperatures get above 65 degrees Fahrenheit,” he says. “Corn can be green on Sunday, and yellow and crappy looking by Wednesday. You cannot stop the carbon penalty. You can only try to keep the corn plant happy while it’s taking place.”
4. Evaluate how much carbon needs to be decomposed. Ferrie offers several scenarios to get an idea of what to expect:
If you’ve chopped silage off the farm and brought back pit manure, the carbon penalty is less, more like corn on soybeans.
If you build corn stalks for bedding, the carbon penalty will be less. Corn stalks that you can see on top of the ground are not part of the carbon penalty, but the corn root system is, Ferrie says.
If you chiseled the corn stalks last fall, the carbon penalty will be much higher than it would be in a no-till corn on corn cornfield. “You chiseled the carbon into where the biology is, and it will be very aggressive,” he says. “If the fall was long and warm, some of the decomposing would have happened in the fall and early spring.”
Spring chiseling will deliver the highest carbon penalty, because you’re burying the residue right in front of the growing season.
Ferrie says some farmers’ fields were set up last fall to go to soybeans this spring and have cover crop rye growing in them.
“The carbon penalty will be a factor of both last year’s corn stalks and the rye that needs to be decomposed,” he says. “The trick is keeping the corn plant happy while this carbon penalty is consuming all the available nutrients.”
This will take implementing the four Rs of nutrients, most often in one of two ways. Ferrie explains:
A. One option is to flood the zone with nutrients, putting on a high enough rate of sulfur and nitrogen broadcast to the surface to get the corn through it. “This would probably take about two-thirds of your nitrogen and sulfur program,” Ferrie estimates.
Problem here is, if you receive heavy rains after application, it could push the nitrogen deeper into the soil, leaving behind some yellow corn until the root system is caught up with it at the depth that the nitrogen moved to.
Fall anhydrous is not good at paying the carbon penalty because of where it’s placed, Ferrie notes. “The carbon penalty happens at the surface, right there where the fence post rots off. Corn has to grow roots down to the anhydrous to be able to pick that N up and it may be caught in the carbon penalty before it gets there,” he says.
B. Option two, the second method, is using timing and the placement parts of the 4Rs. “Applying nitrogen and sulfur with the planter or the strip freshener is the most efficient way to pay the carbon penalty,” Ferrie says. “In most cases, that entails putting on 60 to 90 pounds of N with the planter, then following that up with the sidedress pass. You’re using timing and placement to overcome the carbon penalty. While the carbon penalty is raging all around the corn plant, it has a band of nutrients that it can pull from.”
5. Keep in mind that a picket-fence stand still matters. A corn-on-corn crop demands the same good stand to maximize yield as does corn after soybeans.
Trash pinning – when surface crop residue is pushed into the seed furrow by the planter coulters, potentially hindering seed-to-soil contact and germination – is a big problem with stand establishment in corn on corn. This is a much bigger issue if you chisel corn stalks where the residue is buried, and a row cleaner can’t sweep it away.
“Putting a kernel next to last year’s corn trash will bring in a lot of seedling blights and a lot of emergence issues,” Ferrie says. Soybeans aren’t bothered by this issue like corn is. Row cleaners in strip-till and no-till handle this issue fairly well.
Be aware that spring chiseling can create some very tough seed beds, full of clods, if they get dried out.
“When you’re spring chiseling, these fields need to be fitted down in a matter of hours,” Ferrie says. “Now, you may be able to chisel through the night and fit the field the next day, but don’t let these clods dry out before you level that field, or you’ll fight them the rest of the season.”
Spring strip-tilling of no-till stalks with a coulter and a row cleaner combination works well. “You put the row between last year’s row, right down the middle,” Ferrie says.
Spring strip-tilling with anhydrous and a mole knife brings the most risk. “You need a couple inches of rain to settle the strip and get all the air pockets out, as well as tame down the anhydrous core. I’ve seen February anhydrous burn corn in strip till, if we don’t get enough rain. Waiting for it to rain so you can plant your spring strip till could cause planting delays,” he says.
6. Look ahead to harvest. Ferrie says to consider whether you have the capabilities to handle a bigger corn crop. You may want to break up your harvest by widening your hybrid maturity selection.
Also, remember that when last year’s corn crop decomposes, it gives off a toxin corn doesn’t like. This toxin is water soluble and will keep flushing away with timely rains. But if you have a drought this summer, you cannot protect yourself in corn on corn. The toxin will tap yields.
“When I remind growers of this, the typical response is, ‘I can insure against that better than I can insure against low bean prices,’” he says.
Listen to Ferrie’s complete comments on how to create a successful season with corn on corn in this week’s Boots In The Field podcast, posted below:
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