Scientist Russ Brinsfield holds wheat seed

Scientist Russ Brinsfield holds wheat seed he'll plant as a cover crop near Vienna, on the Eastern Shore, to keep nitrogen from running into the Chesapeake Bay. (Sun photo by Perry Thorsvik)

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To cut back on the flow of lethal nitrogen pollution to the world's waters, Iowa corn grower Roy Bardole would need to let go of the idea that the best farmer is the one with the biggest crop. He'd have to use less fertilizer or set aside some land as a natural pollution filter -- yet still earn enough to support four generations on his 1,000 acres.

Chinese fish farmer Li Zuohui would have to surrender some of the quick profits that have transformed his life. He'd have to thin out the cramped, cloudy pens where he raises grouper by the thousands and spend a big chunk of his income on nonpolluting fish food, instead of on Western-style appliances and other talismans of the good life.

And millions of Americans would have to give up some of their favorite things, too, trading in their sport utility vehicles for less-polluting cars and cutting back on steaks in favor of beans, greens and grains.

There is no one source, and no one solution, for the worldwide glut of nitrogen that is overdosing Earth's living things with twice as much fertilizer as nature intended.

And it isn't a problem that will resolve itself without action. Population growth and prosperity are on track to send nitrogen pollution soaring, especially in Asia.

The United Nations projects that -- with world population increasing by almost 50 percent in the next 50 years and with the growing worldwide preference for a North American-style meat-based diet -- the world's farmers will have to grow twice as much grain as they do now.

University of Minnesota ecologist David Tilman estimates that to double global food production would take almost three times as much nitrogen fertilizer as the world is using now.

Add other expanding sources, such as the burning of oil, coal and gas and the planting of crops that capture nitrogen from the air, and Earth will be absorbing roughly four times as much as nature intended, Tilman estimates.

The mounting problems could be brought under control with a combination of techniques. But it would take a worldwide commitment -- and the nations of the world are far from unified.

In Europe, where the unintended consequences of nitrogen excess are obvious, many governments acknowledged the problem years ago and are trying, with limited success, to impose solutions.

In the United States, by contrast, nitrogen's damage to the Chesapeake Bay might worry Marylanders, and Louisianians might fear for the future of the Gulf of Mexico, but the rest of the country doesn't see many effects of nitrogen pollution. So there's no consensus on taking action.

And such developing countries as China simply have more pressing priorities. The Chinese government knows the nation's fisheries are at risk from excess nutrients. But the need to feed its people and industrialize takes precedence.

The split among nations on this issue is not so different from the international debate over global warming, a debate in which developing nations have long been suspicious of their more prosperous neighbors' push for environmental controls.

Most experts who have pondered the nitrogen dilemma believe it's unlikely that governments, big businesses and ordinary folks would join forces around the globe to halt the spread of nitrogen pollution.

"It's like global warming. You're probably never going to be able to say with absolute certainty, 'This is the bottom line,' " says Dennis Keeney, former director of the University of Iowa's Leopold Center for Sustainable Agriculture. "It's hard to convince people that the impact several hundred miles away is important. Maybe someday that will happen, but I doubt it."

But unexpected events -- such as the toxic Pfiesteria outbreak that hit the Chesapeake Bay in 1997 -- can sometimes change people's minds in a hurry.

Ten years ago, it seemed downright impossible that Maryland poultry growers would team up with a maverick agricultural researcher, Russ Brinsfield, in a quest to cut the flow of nitrogen into the Chesapeake Bay. In the mid-1980s, the University of Maryland scientist earned the industry's ire by insisting that nitrogen in fertilizer and chicken manure was polluting the bay. He urged farmers to try a simple technique for controlling the contamination.

Then came frightening outbreaks of the toxic algae, Pfiesteria, that seem to be fueled by the excess nutrients in agricultural runoff. The scary microorganism has killed fish, made people sick and threatened to knock the bottom out of two important Maryland industries: seafood and tourism.