Menu

Nitrogen Timing Critical in Wet Years

The worse corn looks now, the more it needs nitrogen fertilizer to boost yields, says a University of Missouri plant scientist.

Saturated cornfields across northern Missouri show pale green or yellow leaves, especially in low-lying areas. But they green up quickly when farmers apply nitrogen, says extension nutrient management specialist Peter Scharf.

Scharf’s research shows that Missouri springs are becoming wetter, making the case for spring application of nitrogen. “The size of the wet area in the central U.S. has doubled since 1980,” he says.

The wet spring in 2013 covered a larger area than any recorded since 1900. Rainfall in the past 30 days echoes this trend, especially in northwestern and northeastern Missouri.

Scharf’s rules of thumb: nitrogen loss occurs when 12 or more inches of rain fall on poorly drained soils during May and June, or 16 or more inches fall on well-drained soils from April through June. Northwestern Missouri hit this mark in early June, according to the Midwestern Regional Climate Center. Other areas are not far behind.

“As of mid-June, more than half of the state is in the danger zone for N loss on poorly drained soils where much of our corn is grown,” Scharf says.

MU Extension nutrient management specialist John Lory agrees. “It’s a classic time for large nitrogen losses.”

May 2015 goes down as the 13th wettest on record in Missouri history, says MU Extension climatologist Pat Guinan. He predicts above normal precipitation through August.

Apply nitrogen up to two weeks after tasseling to boost yields, Scharf says, but don’t wait for corn to tassel. “No one knows how late you can apply and get a good response. Don’t try to find out. Get it done before tasseling.”

Aerial photos of cornfields show losses the best. It is hard to see trouble spots from the edges of a field.

Scharf recommends hiring a pilot to scout fields. Most airports, even small ones, have pilots for hire at reasonable rates to fly farmers, and you can take your camera, Scharf said. Some pilots also offer photos.

Once you find trouble spots, decide if it pays to apply nitrogen to those areas, Scharf says. Large areas merit it; small ones may not. Apply only where needed.

Not all forms of nitrogen are created equal. Anhydrous ammonia fares better than other forms applied before planting in wet years. “But neither anhydrous nor Environmentally Safe
Nitrogen (ESN) are bulletproof in a wet year,” Scharf says. ESN resists loss when applied early, but releases too slowly to do well on corn over a foot tall.

Yields increased when nitrogen was applied in spring trials at Bradford Research Center, Columbia. Plots in Scharf’s test produced 254 bushels more per acre over eight years than the best preplant when nitrogen was applied to knee-high corn. And they did it with 164 pounds less nitrogen.

That includes the 2012 drought and 2011, when hail destroyed the crop.

“Proper application translates into more yield and less money,” he says.

There are now computer models to calculate nitrogen loss and need for rescue nitrogen. Scharf’s newly released NVisionAg program (http://nvisionag.com) uses aerial photos of cornfields to predict how much yield will be lost due to N deficiency, and how much nitrogen to apply to fix it. A variable-rate map is produced, because nitrogen loss is usually patchy. “No need to replace it where it wasn’t lost,” he says.

When fields dry, Scharf advises farmers to plant remaining crops first. Nitrogen can be applied after crops are planted, but farmers should have a plan in place for application.

Source: Peter C. Sharf, University of Missouri

Recent News

Fall-applied Herbicides-What Goes Around Comes Around
9/22/2020

Fall herbicide treatments have fallen off over the past several years for a couple of reasons, among them the effectiveness of new soybean trait systems for managing marestail, some generally crappy weather in late fall, and efforts to reduce input costs.  We are seeing a resurgence in some weeds, such as dandelion, which respond well […]

New Round of Farm Aid for COVID Losses Announced, and Causes Snag in Congressional Spending Bill
9/22/2020

Andrew Restuccia and Jesse Newman reported in Friday’s Wall Street Journal that, “President Trump unveiled $13 billion in new aid to farmers facing economic harm from the coronavirus pandemic as he aimed to boost support among rural voters at a campaign rally. ‘I’m proud to announce that I’m doing even more to support Wisconsin farmers,’ said Mr. Trump, speaking outside […]

Corn Silage Needs Adequate Moisture to Ferment
9/18/2020

Early season frost is challenging for corn silage producers, according to Karl Hoppe, Extension livestock systems specialist at NDSU’s Carrington Research Extension Center. Frost makes an abrupt end to the corn-growing season. This begins the dry-down period for the corn plants. “Good corn silage fermentation requires adequate moisture to reduce dry-matter loss and spoilage,” Hoppe […]

Your browser is out-of-date!

Update your browser to view this website correctly. Update my browser now