As Aaron Gingerich walked across jade-green fields of newly emerged corn plants this spring, he had a hunch about the crop that stand evaluations would soon validate: his 2025 crop was off to a winning start.
Mindful of high input costs and low commodity prices, Gingerich pondered his next decision in late May – whether to keep the yield goals he had penciled out for the crop last winter or move them higher, based on what he was seeing in the field. He opted for the latter, bumping his overall yield goal by 12% and making a corresponding increase in his nitrogen program to support the decision.
The plan-then-verify approach to setting yield goals and supporting them with adequate nitrogen (N) in-season has been Gingerich’s go-to strategy in recent years to build incremental yield increases – an annual chess match with Mother Nature that he wins more times than not come harvest.
“The goal is to make sure the crop gets enough nitrogen from day one and through the entire season but to do it as efficiently and sustainably as possible in the process,” says Gingerich, who farms near Lovington, Ill. “It’s been a journey of learning for the past 15 years, and we’re still learning.”
Strategic N Decisions Based On Corn Yield Goals
Gingrich aims to achieve between a 0.85 and a 0.9 nitrogen use efficiency ratio per bushel of corn.
The past few years he has been able to achieve that with a nitrogen program that includes fall-applied DAP, followed in the spring with a banded application of 20% of his total nitrogen, made with a strip-till freshener just prior to planting on the strip. The modest amount of N applied then fuels a strong start in the crop at emergence (VE) and also helps address the carbon penalty, in which a large volume of old crop residue stimulates microorganism populations and causes soil nitrogen to become tied up and unavailable until later in the season.
Next up, Gingerich plans his sidedress applications by pulling nitrate samples to evaluate N availability and whether any leaching issues have occurred. Based on the test results, he makes sidedress applications with the remaining 75% to 80% of his N, paired with a nitrogen inhibitor.
Ken Ferrie calls the process of evaluating nitrate test results and then fine-tuning nitrogen applications at sidedress time and beyond balancing the nitrogen checkbook.
Implementing the practice is important to use for a variety of reasons and is always geared to helping farmers fuel their corn adequately to reach target yield goals at harvest, says Ferrie, Farm Journal Field Agronomist.
“There are things we can’t control, like the weather, but we can make agronomic decisions to mitigate risks and give the crop its best chance to perform up to its potential,” he says.
A common scenario is like the one Gingerich gladly faced this spring – when young corn stands are better than anticipated, and a boost to N rates is needed to reach higher yield goals.
“Say you had a 220-bu. yield goal originally and you decided to go for 260 bushels after corn stand evaluations, the nitrogen needs to be adjusted for that,” Ferrie says.
Another scenario Ferrie has seen play out this year is where farmers opted out of N use last fall, because of budget constraints, but then made no adjustments to their nitrogen program this spring.
“If a year ago we wrote the grower a fertilizer recommendation and it had 48 pounds of N in the dry application but he decided to not put it on due to budget, that 48 pounds has to come back into the picture now, and sometimes farmers forget,” he explains.
Weather conditions always play a role in nitrogen use. In areas where farmers have dealt with too much water this season, Ferrie says pulling nitrate samples for testing – which provides a snapshot in time – works like a nitrogen inventory checker.
“Here locally, I’m feeling good about our N program. For the guys that have been held up by rain and are fighting that, I know that statement may not be true at all, unfortunately,” he says.
Decisions Based On The 4Rs Improves Yield Outcomes, ROI
Ferrie says he sees growers increasingly tuned into using the 4Rs – right product, right rate, right place, right time.
“Farmers are learning to walk that tightrope better, while still making sure corn never has a bad day,” he says. “With our nitrogen recommendation, it pertains to yield goal, hybrid type, population, soil type, organic matter, and we can do what’s called an estimated nitrogen release test to kind of put that all together.”
The way a nitrogen program works is lighter soils need the most applied N. Heavier soils take less N per bushel of corn because the soil supplies that balance.
“When you get into your lighter timber soils, they take more applied N per bushel because the soil can’t supply it. So somebody who’s on a light timber soil and gets nervous and pulls his N rate back, he’s going to get hurt harder than somebody who’s in some heavy black soil that has a lot of built-in horsepower.”
With the 4Rs in mind, Gingerich has tweaked his application timing several times over the years. “We used to fall-apply anhydrous, and then we went to split applications, and we’ve kept adjusting. Now, because we do have heavy soils, I can apply those higher rates of N at sidedress, knowing it’ll be there when the crop needs it at tassel, ear fill and beyond,” he says.
Never Let Corn Have A Bad Day
The right-time aspect of the 4Rs requires understanding how much nitrogen (per day, week or month) corn plants take up at each stage of growth. “Fortunately, there’s a wealth of published information farmers can use for guidance,” Ferrie says. “Using computer models, we can input our planting date and weather data and the model can predict when plants will reach various growth stages and how much nitrogen must be taken aboard each day.”
To reach a specific yield goal, growers need to know about a hybrid’s season-long uptake and N timing needs along the way. For instance, a 200-bu. per acre corn crop will consume between 330 lb. to 350 lb. of nitrogen per acre, on average.
“On many soils, we only need to apply about 200 lb. of nitrogen, or less, because the soil provides the rest of the nitrogen,” Ferrie explains. “Our challenge is to make sure sufficient nitrogen is present when the plant needs it throughout the growing season. That requirement is small at the beginning and becomes very large later in the season. And it varies by hybrid.”
Right after emergence, corn takes up only a very small amount of nitrogen. By the time a plant reaches the V5 growth stage (five leaf collars showing), it might contain only 8 to 10 grams of dry matter in its leaves, stalks and roots, and that dry matter is only 1.5% to 2% nitrogen. So, at 36,000 plants per acre, 1 acre of corn takes up only about 1.2 lb. of nitrogen through the V5 stage.
Although N uptake is low from emergence to V5, it can’t be neglected. “Poor placement, one of the 4Rs, can restrict plants from finding even 1 lb. of nitrogen,” Ferrie says. “If you applied anhydrous ammonia 7" to 8" deep the previous fall, the N might still be there, but it will be out of reach for the plant.”
During the V5 through V8 growth stages, sufficient nitrogen is critical because that’s when many hybrids begin adjusting their potential ear size. “If a plant suffers serious nitrogen deficiency between the V5 and V8 growth stages, it might cut back from 18 rows of kernels to 14 or 16,” Ferrie says. “Once a plant scales back its ear girth, we can’t get it back.”
Nitrogen Requirements Through Corn Reproductive Stages
From V12 to R3, plants store nitrogen in their stalks. If at any time a plant can’t meet its nitrogen needs, it translocates nitrogen from its stalk to the grain.
At V12, growth becomes so rapid that, as farmers often say, you can hear the corn grow. “At this stage, the nitrogen uptake rate is steep, and the supply is critical,” Ferrie says. “This is the crucial period in which maximum ear length still is being negotiated inside the plant. It continues all the way to grain fill.
After V12, if we stress the plant very long, without enough nitrogen, it might start to abort kernels.
Kernel abortion can continue into the dough stage, and, once it happens, you can’t get those kernels back.
“Our studies have shown, by the time we see lighter green color in nitrogen-deficient strips, we usually have given up some yield. We can turn those plants green again by applying nitrogen—and we have to, to avoid losing much more yield—but we can’t make up the lost yield potential.
Generally, a plant accumulates about 70% of the total N it will need before silking and accumulates about 30% during reproductive growth, according to Purdue University Extension.
At about R3, the plant begins heavy translocation of nitrogen from the stalk to the grain, as plants work on filling kernel depth. Through R4 and R5, entering the dent stage, the plant continues to translocate nitrogen from the stalk into the grain. “If the stalk is empty of nitrogen at this time, it will affect grain fill,” Ferrie says.
Gingerich says, so far, his sidedress applications are keeping his corn adequately fueled through harvest, though he has contemplated applying N with a Y-drop application. “So far we haven’t seen an economic benefit to it, but we might in the future,” he says. “With these newer hybrids using more nutrients to stay greener and healthier longer, I can see how making an adjustment at some point could provide more ROI.”
Talk With Your Seed Supplier
Seed companies are starting to provide farmers with information about corn hybrid response patterns to nitrogen.
“Some can tell you whether the hybrid needs N up front, at the back end or broken up with split applications,” Ferrie says. “If this information is not available for your hybrids, you can incorporate nitrogen timing into a hybrid test plot and observe the response.”
Ferrie offers a final caution for farmers who believe corn needs to turn yellow before nitrogen deficiencies limit yield. That’s a theory that can cause significant yield losses.
“You can have a 20-bu. loss in yield from a lack of adequate nitrogen and not be able to see that from the pickup,” he says. “When we are dealing with nutrients that affect yield, nitrogen is the big dog. And when you run out, yields will drop. Missing P and K will change soil test values, but missing out on nitrogen reduces yields,” he adds.
Darrell Smith contributed information on nitrogen application timing to this article.
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