Midseason Corn Conditions: Signs Nitrogen Went With the Flow
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As growers scout cornfields for signs of pests and disease, another yield-limiting factor may be apparent: nitrogen deficiency.
“I expect to see a lot of nitrogen-deficient corn this summer,” says Taylor Ferguson, Corteva Agriscience nitrogen stabilizers strategic account manager covering Ohio, Michigan, Kentucky, and the Northeast. “Rains delayed planting in Ohio, Kentucky, and Michigan. Those rains also likely moved nitrogen down in the soil profile where corn roots may not be able to reach it.”
Brad Allen, Corteva Agriscience market development specialist, says the growers he works with south of Interstate 64 in Illinois and across southern Indiana also dealt with excessive rainfall and delayed planting.
“When mid-June approached and the farmers south of I-64 couldn’t get a break from the rain, concern was high on getting the crop in the ground,” Allen says.
The excessive rainfall not only delayed planting for many but also created challenges with nitrogen management and application. The best nitrogen management programs offer an initial level of nitrogen to encourage germination and early growth, and they provide the bulk of the nitrogen from V6 to R1 or silking to finish plant growth, pollination, and ear development. During this stretch, studies indicate newer hybrids require as much as 8 pounds of nitrogen per acre per day to reach maximum yield potential.
“For the growers who use anhydrous but didn’t include a stabilizer when applying it last fall or early this spring, 30% to 50% could have been long gone because of leaching or denitrification,” Allen explains. “To make up the difference, there was a lot of sidedress liquid nitrogen applied in my area.”
Ferguson also saw growers throughout Ohio and Michigan rely heavily on sidedress and increase the amount of nitrogen in their applications even though most of the anhydrous was applied as planned. Even with those later nitrogen applications he recommends a proven nitrogen stabilizer be included in the tank to help ensure the nitrogen is available through the critical grain development period. He points out that a 2023 research trial in Illinois found that fall applied N-Serve® nitrogen stabilizer combined with a spring sidedress application of Instinct NXTGEN® nitrogen stabilizer offers increased yields of 9 bu./A compared to fields with nonstabilized nitrogen. There’s a common misconception that you no longer need a stabilizer after corn is planted, but the data reflects a strong ROI through sidedress.
Leaching is not the only culprit in nitrogen loss
“Nitrogen leaching is a phenomenon farmers understand, but sometimes we forget leaching isn’t the only cause of nitrogen loss,” Ferguson says.
If the soil is saturated for several days, nitrogen loss can occur from denitrification. When the soil temperatures are 70°F, it only takes about nine days for ammonium to fully convert into nitrate. Warm, wet conditions speed up soil bacteria that turn ammonium into nitrate, which can then be lost to the atmosphere if soils stay saturated and anaerobic for several days. For example, a University of Nebraska study demonstrated that soil saturated for about 5 days lost 10% nitrogen at 55-60°F but lost 60% nitrogen at 75-80°F1.
Symptoms of nitrogen deficiency
Ferguson shares a list of symptoms to look for when scouting corn this summer, especially if you suspect issues with nitrogen deficiency:
- Leaves display a yellow V pattern. The yellowing begins at the leaf tip and runs down the midrib.
- Older leaves show symptoms first. Nitrogen is mobile in the plant. When the plant is stressed, nitrogen is reallocated to new growth, so symptoms appear on the lower, older leaves first.
- Leaves appear pale yellowish-green. In contrast to the deep, dark green leaves of corn plants with plentiful nitrogen, those that are deficient usually have a dull, pale-green or yellow-green color, especially if the deficiency is prolonged.
- Lower leaves experience firing. The yellow color will turn brown, and then the lower leaves die. This is known as firing. Firing caused by drought is typically more general, starting at the leaf tip and edges and then moving inward.
If you’re concerned about nitrogen loss on your farm, contact your local Corteva Agriscience representative for more information, visit NitrogenStabilizers.com or use the Nitrogen Loss Calculator. It considers local weather data, application timing and nitrogen source to predict nitrogen loss.
1University of Nebraska-Lincoln CROPWATCH. 2008. https://cropwatch.unl.edu/assessing-nitrogen-loss-due-saturated-soils/
Instinct NXTGEN® is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Do not fall-apply anhydrous ammonia south of Highway 16 in the state of Illinois. Always read and follow label directions.