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Corn+Soybean Digest

The Quest For N Efficiency

Nitrogen is one of the most expensive agronomic tools for today's farmer. So says James Camberato, an associate professor of soil fertility at Purdue University in West Lafayette, IN.

Some farmers have trimmed back on the amount of nitrogen (N) they apply and are working towards more efficient applications and timing in the wake of rising fertilizer costs, experts say.

But they caution against cutting back on N too much. If farmers apply too little N, any cost savings will be lost due to yield decreases.

One thing is for sure: Managing an efficient N application is eating up a lot more time for farmers than it used to.

David Emmert, a Montgomery County, IN, farmer, says he, his father and his uncle are taking a lot more time to evaluate N applications on the family's 2,800-acre corn and soybean farm.

“Everyone in our family put a pencil to it to really figure out if we're using nitrogen in the right way or just putting on how much everyone else is,” Emmert says.

The family is continuously re-evaluating N applications and haven't settled on a system yet. In fact, the application could change every year, Emmert says.

Camberato says that farmers haven't been wasteful in their N application, but they weren't penalized financially for sometimes applying more than necessary.

One challenge is that predicting the right rate of N fertilization is not an exact science in all geographies, says George Rehm, University of Minnesota Nutrient Management Specialist. “This is especially true for the eastern Corn Belt,” he says. “The soil nitrate test is appropriate for the western Corn Belt in situations where corn follows a crop other than alfalfa or soybeans. So, soil testing for nitrogen to predict rates is really not a widespread management tool.”

Some farmers are becoming more efficient in their application by switching from fall application to late spring. In sandy soils, there's a benefit to applying some N at planting and the bulk within four to six weeks of planting, Camberato says.

John Kretzmeier and his wife Kristi have started doing a lot more trials and research on N application on their 4,000-acre farm in Fowler, IN.

Before 2006, the Kretzmeiers applied all the N preplant. Last year, half was applied up front, and the rest when the crop reached shoulder-height.

He reduced his rates by applying N later because he was applying it in the time of maximum need and wasn't worried about losing as much through ponding and water.

Kretzmeier is studying how rates can be reduced without affecting yield. “I don't want to run the risk of leaving any bushels on the table because of the cost of nitrogen,” he says.

“We like to produce bushels but we need to do it as efficiently as we can,” Kretzmeier says.

Nitrogen is crucial. It has the largest impact of any nutrient on the yield, affecting the size of the plant and its ability to capture sunlight.

The key is to use N effectively for economic and environmental stewardship reasons, Kretzmeier says.

“So many farmers spend so much of their time trying to cut their costs of production. Rather than try to save a penny, I'd rather make a dime,” he says.

Anhydrous is the cheapest form of nitrogen, but other forms areappealing because they can be shipped more easily and less expensively and they are less hazardous, Camberato says.

Those are some of the factors that Matt Marlin, a farmer near Hope, IN, considered when he made the switch to liquid N.

Marlin, who farms 500 acres of corn and soybeans, avoided using anhydrous for a decade. He tried other ways to get N to his crop, but could not get the yields he desired.

He had sold his anhydrous equipment and rented equipment for a while. Then he had a decision to make: Buy new anhydrous equipment or switch to liquid N.

He chose the more expensive liquid form because its other advantages outweigh the costs.

Among the advantages are that he can shop around for prices because he isn't restricted on hauling the N, there's no worry about thieves stealing anhydrous to use in methamphetamine labs, it's safer and takes a lot less fuel to apply because he doesn't have to pull a knife through the ground, Marlin says.

More and more farmers will begin considering making the switch to UAN, and they will want to know how to do it effectively, Camberato says.

He says surface applications of UAN can lose up to 15% of the N in no-till applications. Farmers should try to incorporate it into the soil or place it below the surface to reduce the loss.

One Farmer's View

Here's how Indiana farmer Matt Marlin weighs in on choosing liquid nitrogen (N) rather than anhydrous ammonia:

  • More options on where to purchase liquid N.
  • Takes less fuel to apply.
  • Better control over product used per acre.
  • Can vary the rate as it's applied.
  • Can set it up to shut off part at toolbar.
  • No ground disturbance.
  • Easier to store product on farm.
  • Leaks are less dramatic.
  • Can buy in the off-season or at the end of the season and store until needed.
  • No threat of theft for use in methamphetamine labs.


  • Uses more material. (Can mitigate by using larger tanks on applicator, being more precise with the amount used and vary the rate per acre.)

  • More expensive per unit N. (Can mitigate by shopping around, buyingin off-season and storing on farm.)

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