Corn, like most humans, doesn't like stress. The key to growing healthy corn is to reduce its stress, especially during key periods such as pollination. But the healthiest corn receives adequate nitrogen all along the way, so that its growth never slows.
By Rhonda Brooks
If you want to harvest a bumper corn crop this fall, one of the best things you can do is to keep corn happy during the growing season, advises Ken Ferrie, Farm Journal Field Agronomist. He says one of the best ways to accomplish that is to feed the crop adequate nitrogen along the way as part of an overall Systems Approach to management.
"You want to keep enough nitrogen available during all corn growth stages so crop growth never slows down," Ferrie explains.
He says nitrogen works in corn like gasoline in a vehicle, fueling crop growth from emergence through maturity. A lack of nitrogen at any point along the way can cause the crop to sputter or stall.
"Corn that’s nitrogen deficient at the beginning of the growing season gives up yield potential," Ferrie says. "Nitrogen-deficient corn in the late reproductive stages costs actual yield."
Iowa State University Extension research indicates the maximum nitrogen uptake in corn occurs in periods of maximum growth, roughly in the V9 to V18 growth stages.
Management puzzle. Figuring out how much nitrogen your corn crop needs, what type it needs and when it needs the nutrient differs from farm to farm and year to year. A set of agronomic practices that Ferrie calls the Systems Approach is designed to help you minimize risks and capitalize on the opportunity for high corn yields in any given season.
While the Systems Approach comprises several factors, it is based on one guiding principle: Every management practice you use is intrinsically linked and ultimately impacts yield.
The first consideration when addressing nitrogen use is the farm environment. Ferrie says this includes weather conditions as well as the farmer’s tillage practices and crop rotation.
The environment sets the stage for nitrogen timing. The timing, in turn, sets the stage for placement—where you place the nitrogen to make sure it reaches the corn.
Placement then sets the stage for the nitrogen source.
"For instance, fall ammonia might be the easiest and most economical nitrogen source, but it may not fit certain scenarios that we want to address, such as helping us manage the carbon penalty," Ferrie notes.
He tells farmers to always think through how each piece of a crop’s management puzzle fits together, especially if they decide to make a change in any area.
"Say a corn grower decides to change his crop rotation or add a cover mix; he doesn’t realize that this one change creates a chain reaction that affects how he needs to manage nitrogen throughout the season," Ferrie says. "When you make one change, try to think about how many possible things that will affect."
Along with that advice, here are six additional nuggets of information Ferrie provides to help you plan your nitrogen program in corn.
-- Assess the environment for every field; that is crucial in building a nitrogen program. Know your risk of nitrogen loss from leaching, denitrification and/or volatility.
-- Pick the right nitrogen sources, timing and placement. Doing those three things is much more important than trying to pick the right rate.
-- Assess the carbon penalty potential based on the amount and type of carbon left from your previous crop. Don’t forget to assess a carbon penalty for grass cover crops.
-- Consider that split applications and nitrogen inhibitors might be part of the balance of your nitrogen plan.
-- If corn greens up right after a sidedress application, it is telling you that the crop was waiting for the nitrogen and it was giving up yield potential during the process.
-- Season-long scouting is the only way to get a handle on nitrogen needs and management. Knowing when you run short is more important than knowing how much you ran short. As Ferrie emphasizes, "Scout, scout, scout and then make a plan."