With government air regulations coming to agriculture, it’s clear that many large-scale livestock operations — managed as they are now — could exceed Environmental Protection Agency (EPA) limits for ammonia discharges.

However, one thing that speakers made clear during the course of the Mid-Atlantic Agricultural Ammonia Forum in Gettysburg is that ammonia emissions are just one part of the big picture when it comes to nutrient management.

The fact that ammonia is not even addressed in Pennsylvania’s newly amended Nutrient Management Act highlights the added burden air quality regulations could bring to livestock producers. Like other nutrient management practices, controlling ammonia comes with a price.

Robert Graves of Penn State’s Agricultural and Biological Engineering Department moderated the forum, which featured speakers from the University of Maryland, University of Delaware, USDA, and Penn State. They covered topics from defining ammonia to government regulations to best management practices for farmers to curb emissions.

“Everything has to be somewhere,” Graves said of the challenge in managing nutrients, specifically ammonia and other nitrogen-containing compounds.

The three “shells” on earth where nutrients can be found are air, water, and soil.

“Oftentimes we play ‘shell games,’ moving things around from one shell to another,” Graves said.

Dave Hansen of the University of Delaware led off the forum by defining ammonia and some of its potential impacts.

Ammonia is a nitrogen-containing gas. Animal manures are a major source. While ammonia from poultry manure has been the most intensely studied, manure from swine, cattle, and other livestock also produce ammonia.

Ammonia is highly reactive and “smelly,” Hansen said. It is the only “base” gas in the atmosphere. In chemistry terms, a base is the opposite of an acid, tending to take up positively charged hydrogen atoms rather than shedding them as an acid does.

Hansen outlined potential problems caused by ammonia, including impacts on human and animal health and on the environment.

Ammonia can quickly be converted to other types of nitrogen, such as ammonium and ammonium compounds (ammonium sulfate and ammonium nitrate are examples.) These compounds form solid particles (particulates) in the air, which can enter human or animal lungs and cause health problems.

Furthermore, these particulates eventually return from the atmosphere to the earth’s surface, where they are converted to nitrates and other nitrogen compounds. This nitrogen in the soil or water can become a problem of its own by adding to the overabundance of nutrients entering waterways and bodies such as the Chesapeake Bay.

“(The nitrogen compounds) will generally come down in some form someplace,” Hansen said.

Even though ammonia is a base, it can ultimately be a factor in soil acidification and acid rain. That’s because the ammonium form tends to release charged hydrogen atoms which acidify soil or water.

Because it’s a nitrogen compound, though, ammonia is far from being all bad. One reason to keep ammonia in the manure instead of letting it escape into the atmosphere is so its nitrogen can be applied to crop production.

According to Hansen, the portion of nitrogen recovered by crops from land application of manure is usually 50 percent or less — and the best recovery is about 66 percent.

“You can lose huge amounts of nitrogen,” Hansen said. This loss can be worsened by the method and timing of application. Hansen showed a picture of a farmer broadcast spraying liquid manure on a field during a hot summer day as an example of exactly the wrong way to do it.

“If you were looking for a way to get rid of nitrogen, this would be it,” he said.

Specific techniques for reducing ammonia loss, such as incorporating manure as soon as possible after application, were discussed in depth later in the forum.

The tendency for ammonia to volatilize rapidly into the atmosphere and then return to the earth in another form can contribute significantly to nitrogen loading in water bodies such as the Chesapeake and Delaware bays.

“There is an important link between ammonia in the atmosphere and nitrogen in the water,” Hansen said. For that reason, “we need to be talking about ‘airsheds,’” he said, rather than just watersheds.

Hansen pointed out that atmospheric ammonia levels have increased more than 60 percent in areas of Delaware in the past 20 years, a figure that correlates with the growth of the poultry industry in the state.

Tom Simpson, from the University of Maryland’s College of Agriculture and Natural Resources and coordinator of the forum, spoke specifically about the impact of ammonia on water quality.

“What goes up must come down,” Simpson said, noting that about 50 percent of ammonia emissions come down in the local area where they were generated. The rest is deposited “somewhere,” he said.

A general agreement among water quality groups and government agencies to eliminate nutrient impairment to the Chesapeake Bay by 2010 is not attainable, according to Simpson.

While politicians may imply that the goal can be reached by 2010, Simpson said, “I can tell you we don’t have the capacity to do it by 2010.”

Simpson commended the nutrient management efforts of farmers and others, but said the steps taken so far are not enough.

“We have been doing the easy things,” he said. “To those doing it, it seemed hard. But we have a lot more to do.”

John Becker, Penn State professor of agricultural economics and law, outlined regulations surrounding air emissions. He referred to the regulatory climate for air quality as “a solution in search of a problem.”

Laws with a possible bearing on air emissions include the Federal Clean Air Act and Pennsylvania’s Pollution Control Act and Right to Farm Act. On the local level, zoning and land use planning could come in to play.

One key question surrounding the issue is whether or not federal or state laws can preempt local laws. That question isn’t always answered in the same way, Becker noted.

At this point in Pennsylvania, agriculture is exempt from the Pennsylvania Pollution Control Act except in cases where the Federal Clean Air Act applies.

As the Clean Air Act turns more and more toward regulating agricultural air quality, Pennsylvania will likely become involved, according to Becker.

As of now, court cases in at least two other states are involved in determining liability for air emission violations on large-scale animal operations.

“Citizen suits are driving air quality issues,” Becker said. “It’s still early in the game. We may see, over the next 10 years, that answers won’t always be clear.”

Editor’s note: Part 2 of this series will focus on monitoring and methods for controlling ammonia emissions on the farm. blog comments powered by Disqus