Nitrogen: Too Much of a Good Thing?

[imgcontainer] [img:TOLEDO-master675-v2.jpg] [source]Photo by Joshua Lott for The New York Times[/source]

Lake Erie’s algae bloom washed ashore at Maumee Bay State Park near Toledo, Ohio.

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Growing up, one of the events we looked forward to was the church pot luck dinner.

There were so many delicious choices as we worked out way down the table. It was easy to overfill the plate, and the desserts were still ahead.

It took more than one pot luck dinner to finally come to the conclusion (well, mothers and a stomach ache or two helped) that it was possible to have too much of a good thing.

The Lake Erie algae bloom that shut down the public water system of Toledo, Ohio, from August 2-4, forces us to face the problems caused by too much of a good—and necessary—thing: excess phosphorus, some of which came from agricultural production, which fed the algae bloom.

A United States Department of Agriculture (USDA) Economic Brief, “Nitrogen Management on U.S. Corn Acres,” points out that while nitrogen is an important input that allows farmers to “produce high yields profitably,” excessive application can lead to problems. They note that “nitrogen compounds released into the environment can also be a source of environmental problems, including eutrophication and hypoxia in aquatic ecosystems, visibility-impairing haze, and the loss of biodiversity.”

(When we we talk about how to manage the application of nitrogen, we’re also talking about how to control phosphorous and potassium, because the chemicals are often applied as part of a compound.)

Most of the reactive nitrogen emissions in the United States comes from agriculture, according to another USDA publication. Agriculture is responsible for 73% of nitrous oxide emissions, 84% of ammonia emissions and 54% of nitrate emissions.

Despite all that we know about the problems created by crop nutrients that make their way into the environment, about two thirds of the cropland producing eight major field crops did not follow best management practices for nitrogen, according to USDA.

The same source found that most cropland rotations (from 82 to 96%, depending on region) needed improvements in nitrogen management.

The problem that farmers face is that they do not know what the weather will be like in a given year. So they apply the amount of nitrogen that would be necessary for a year with optimum growing weather. The problem is that most years, by definition, aren’t optimum. So farmers over-fertilize and apply too much nitrogen.

While giving farmers the best shot at high yields to maximize income in an optimum weather year, over-fertilization shifts costs to others. USDA estimates that “consumers spend over $800 million each year on bottled water due to nutrient-related taste and odor problems.” The USDA Economic Research Service also estimates that drinking-water utilities spend $4.8 billion a year to remove excess nitrates. ERS estimates that about $1.7 billion of that is spent on nitrates that came from agriculture.

”Most costs are borne by the large utilities, due to the volume of water treated,” says the ERS.

The farming practices for reducing nitrogen are generally well known among producers. Farmers need to watch the rate, timing and method of application. But the practice of these basic principles apparently has a long way to go.

Without significant progress in adopting all three practices, societal pressure will likely force stricter enforcement of existing conservation compliance rules on producers participating in farm programs or subsidized crop/revenue insurance programs. The next step could the introduction of far more onerous rules.

Daryll E. Ray holds the Blasingame Chair of Excellence in Agricultural Policy, Institute of Agriculture, University of Tennessee, and is the Director of UT’s Agricultural Policy Analysis Center (APAC). Harwood D. Schaffer is a research assistant professor at APAC.

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