By Mike Surbrugg

msurbrugg@joplinglobe.com

MOUNT VERNON, Mo. — “Nitrogen is a tricky, slippery thing to work with.”

That was the assessment from Peter Scharf, a University of Missouri plant scientist, during a recent meeting held in Mount Vernon where he talked about different sources of nitrogen fertilizer.

He focused of using urea or ammonium nitrate sources.

There is potential for nitrogen loss from any source, he said.

A lot of fertilizer in Missouri is broadcast on the surface of pastures and hay fields. “Grass is king in Southwest Missouri,” he said.

A lot of broadcast urea can be lost through volatilization, he said. The loss is greatly reduced when the urea can be knifed into the soil or by tilling it into the soil within four days of application.

In grass-covered fields, an answer to the loss has been to pay a higher price to get more results by broadcasting ammonium nitrate that is less volatile, he said.

Missouri, Oklahoma and Texas are the states where farmers use the most ammonium nitrate because these states have a lot of grass and cattle, he said.

A major concern is that ammonium nitrate is also used to make bombs. National security requires constant armed guards when any of this product is stored near any navigable waterway.

Agrium is among corporations no longer making ammonium nitrate. It had been the largest manufacturer of ammonium nitrate in North America, he said. Some plants are shutting down in face of high natural gas prices and in the face of restrictions.

It is not practical to blend urea and ammonium nitrate in a fertilizer spreader, he said.

The gap left by less ammonium nitrate production means the United States is importing more urea. More urea plants are being constructed worldwide because the world wants fertilizer, Scharf said.

More farmers are using less or no tillage to reduce erosion and lower production costs. An average 25 percent of nitrogen is lost into the air as a gas when urea is spread on the ground.