The Fall Versus Spring Nitrogen Debate

nitrogen management

Nitrogen management is critical for growing healthy corn and farmers are sensitive to their role in helping build a more sustainable world. They are faced with the often-daunting question of whether fertilizer applications can be both profitable and sustainable. Often, the delicate balancing act begins with the decision of whether to apply N in fall or hold off until spring.

BMPs and the 4Rs

Corn producers understand there is no blanket practice. There is, however, a disciplined application approach that has long proven effective.

“When we talk about sustainability in agriculture, specifically as it relates to nutrient management, it really goes back to a foundation of best management practices (BMPs) in conjunction with the Fertilizer Institute’s 4R Program,” says Eric Scherder, field scientist, Ph.D., Dow AgroSciences, from Huxley, Iowa. “We can address some of the challenges we’re facing with nitrogen leaching and surface application runoff more effectively using this approach.”

As most growers are aware, the 4R program is a concept to help them select the right fertilizer source at the right rate, at the right time, with the right placement. While source, rate and placement are important, often the most scrutinized decision — both from an economic and sustainability standpoint — is timing.

Fall versus spring

Each year, farmers consider many factors when deciding when N should be applied. Complicating the decision are those who call into question research data documenting the effectiveness of fall applications.

“There are a number of reasons why we do fall fertilizer applications,” Scherder says. “One consideration is infrastructure. If every farmer was forced to apply in the spring, we wouldn’t have the equipment or product available to meet the demand. Time and weather are also big factors since the number of days fit for fieldwork in the spring are usually limited.”

Environmental concerns resulting from nitrate leaching and denitrification — regardless of whether fall- or spring-applied — also complicate the equation. Because all N sources are, by nature, very mobile and susceptible to loss, there are inherent risks.

As farmers look ahead and try to anticipate what’s coming for the next six months, they’ll be weighing several factors that will ultimately lead them back to BMPs and the 4Rs. It’s not a perfect science, and there will always be variables.

Regardless of whether Mother Nature shines favorably on fall application or decides to halt things until spring, the fine line of maximizing profit by minimizing N loss and promoting sustainability should always be top of mind.

Using N-Serve® and Instinct® nitrogen stabilizers with fall-applied N can have both economic and environmental advantages.

Studies show the active ingredient in Instinct and N-Serve increased N retention by 28 percent and N leaching decreased by almost 16 percent.1 N-Serve and Instinct also have been proven to provide an average revenue increase of $21 per acre.*

A solution for every acre

“When considering fall fertilizer applications, there are certain nitrogen sources like liquid UAN that are probably not the right source for the time,” Scherder says. “A fall anhydrous application is more common, although risks still remain. Regardless of the form of nitrogen, we recommend farmers use N-Serve or Instinct with fall nitrogen applications.”

Farmers planning fall urea applications should make sure it’s protected so it’s available to crops in spring when they need it most. Instinct maximizes N by extending N availability for up to eight weeks so it’s available during critical growth stages, so crops deliver the maximum yield at harvest. When applied with urea, Instinct can blend easily in a blender for simplified application.

The advantages of using Instinct with fall-applied swine manure are no different; however, farmers who use liquid manure to fertilize corn crops can now mix Instinct® nitrogen maximizer in their pit for easy application to protect applied N.

Field studies conducted by Dow AgroSciences and several Midwestern universities show notable corn and silage yield increases when manure is applied with Instinct.

Research from the University of Minnesota shows Instinct, applied with fall swine manure, provided a per-acre yield increase of 10 to 12 bushels and reduced grain moisture of approximately 1.3 percentage points at harvest.2

“If you look at the economics alone, if nitrogen is leaching, growers are literally just washing dollars down the soil,” Scherder says. “With denitrification, nitrogen is escaping in the air. Both have an adverse economic impact, but growers are also concerned about the environment and sustainability. When growers are applying fertilizer with N-Serve or Instinct, they are negating both economic losses and adverse environmental impact.”

For more information about protecting fall-applied N, visit

*Based on 452 Dow AgroSciences field trials from 2010-16, resulting in an average increase of 8.9 bu./A at $3.50/bu.

1Meta-analysis published 2004. “Wolt.”

2Vetsch, J., and J. Lamb. 2011. Applying Instinct as a nitrogen stabilizer for fall applied manure.

Original Source: Leaders of In-Furrow Technology, West Central

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