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Diagnose fertilizer burn in corn

Corn Commentary: Watch out for these symptoms and take precautions in the future.

Tom J. Bechman, Midwest Crops Editor

May 28, 2024

3 Min Read
Fertilizer burn injury on roots of a corn plant
TOO HOT: These corn roots ran into too high a concentration of fertilizer. These symptoms are typical of fertilizer burn injury. Dan Quinn

Applying fertilizer correctly is a balancing act akin to balancing a bar while walking a tightrope. You want to place fertilizer where plants will find it fast and where it won’t be lost. At the same time, you don’t want to risk burning roots or injuring plants. For an individual plant, that could be as disastrous as someone losing their balance and falling off the tightrope.

“There are at least three situations where we run into cases of fertilizer injury this time of year,” says Dan Quinn, Purdue Extension corn specialist. “Know how much actual product you are applying, and take steps to place it properly to help stay out of these situations.”

Here are three scenarios that could result in injury symptoms on corn plants:

Too much starter in the row. “You can literally burn roots, especially on seedlings, if they contact too high of a concentration of fertilizer,” Quinn explains. “Roots may just stop growing, or they may appear stubbed off. If seedlings are stunted or dying, dig up a few. If it’s fertilizer burn, symptoms should be obvious.”

The most common situation resulting in seedling injury from starter fertilizer occurs when product with too high of a salt index is applied in-furrow, Quinn says.

“The limit in-furrow is 10 pounds of actual nitrogen plus potassium per acre,” he explains. “If you’re applying 100 pounds of nitrogen, for example, you can only apply a maximum of 10% of that total within the row.”

Related:Expect uniform corn emergence in 2024

Preplant anhydrous ammonia burn. Every year, Quinn fields calls from someone noticing corn seedlings stunted or discolored compared to their neighbors. The cause traces back to injecting anhydrous ammonia before planting. Symptoms below the surface will resemble when too much starter nitrogen plus potassium is applied.

“It doesn’t always show up, but sometimes people see it,” he says. “If you can get at least two weeks between application and planting, it helps reduce the risk. Apply on an angle so an entire corn row doesn’t wind up below a knife pass.”

Sidedress burn. This time, symptoms are burnt leaves — either sections of leaves or splotches on leaves. An anhydrous ammonia applicator that isn’t sealing well around injection knives or a liquid N applicator with leaks can produce these symptoms.

“Normally, corn grows out of it, but it’s not desirable,” Quinn notes. “You’re not applying the product properly.”

Across the rows

To say it has been a tricky spring planting season to navigate would be an understatement. Here are reports that bear this out:

In Michigan. While some fields look really dry on top, Jim Zook, executive director of the Michigan Corn Growers Association and Michigan Corn Marketing Program, says they are wet deep down, but also in the middle, which is wet and mushy. “Some think it’s because we didn’t have a hard frost this year, but those are the planting conditions. Fortunately, we really haven’t heard of anyone getting majorly stuck, although it remains a possibility.” — Jennifer Kiel, American Agriculturalist editor

In Michigan and Ohio. Seed corn maggot is on the radar in Michigan and Ohio, especially in soybeans and particularly in fields with tillage, freshly decaying green stuff and slow emergence. Fields planted in April with seeds planted too deep are most at risk. The first round of damage is over, but now growers are on the lookout for the first generation of adults to emerge. In cool, wet seasons, a repeat infestation cycle could occur in later-planted fields. — Chris DiFonzo, Michigan State University Department of Entomology

In Missouri. Corn planting was 76% complete as of May 19, but only advanced from 72% in a week, due to rain delays. The five-year average is 81%. Percent of corn emerged equals the five-year average at 61%. Some stand loss and replanting is possible due to recent wet conditions. — USDA National Agricultural Statistics Service

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Fertilizer

About the Author(s)

Tom J. Bechman

Midwest Crops Editor, Farm Progress

Tom J. Bechman became the Midwest Crops editor at Farm Progress in 2024 after serving as editor of Indiana Prairie Farmer for 23 years. He joined Farm Progress in 1981 as a field editor, first writing stories to help farmers adjust to a difficult harvest after a tough weather year. His goal today is the same — writing stories that help farmers adjust to a changing environment in a profitable manner.

Bechman knows about Indiana agriculture because he grew up on a small dairy farm and worked with young farmers as a vocational agriculture teacher and FFA advisor before joining Farm Progress. He works closely with Purdue University specialists, Indiana Farm Bureau and commodity groups to cover cutting-edge issues affecting farmers. He specializes in writing crop stories with a focus on obtaining the highest and most economical yields possible.

Tom and his wife, Carla, have four children: Allison, Ashley, Daniel and Kayla, plus eight grandchildren. They raise produce for the food pantry and house 4-H animals for the grandkids on their small acreage near Franklin, Ind.

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