Overfed from farmland, Chesapeake needs a diet

ON THE BAY

October 17, 1992|By TOM HORTON

Like many a middle-aged desk jockey whose knees no longer tolerate pickup basketball games, a few years ago I began to get fat. A counselor at the local YMCA suggested, among other things, cutting my fat intake.

It proved eye-opening. When you focus on the source of every calorie you eat, you realize we live in a world awash in fat.

Government guidelines say: Limit fats to 30 percent of your total calories. Many respected nutrition experts think 20 percent is a far healthier maximum.

It is easy to surpass those limits. A large cheeseburger washed down with whole milk, along with a plate of fries, or a couple slabs of my favorite fried scrapple -- forty percent fat-free, goes the joke -- can leave you teetering on the brink of adipose overdose.

Throughout most of our evolution, we ate what we could gather -- berries, beans, roots, fruits -- and wild meat and fish only occasionally. Fat was relatively scarce. Survival put a premium on bodies that could efficiently store that precious commodity, that excellent energy source -- fat.

Only in the last moment or two of our time on the planet have agriculture, animal husbandry and personal affluence conjoined to make large excesses of fat available to great masses of people.

Just as we now nourish ourselves all too well, so have we also created a "fat" and unhealthy Chesapeake Bay. That is not exactly how Dr. Les Lanyon, a professor of agronomy at Pennsylvania State University, would put it, but listening to him talk about the history of fertilizers recently reminded me of the fat counselor back at the Y.

When Dr. Lanyon looks at a farm whose lands drain toward the bay, he sees it as the focal point of a great and far-flung web of "nutrient streams" -- rivers of nitrogen and phosphorus and other essential ingredients of plant and animal growth, flowing in the form of imported fertilizers, animal feeds, even peanut hulls for livestock bedding.

Until several decades ago, the soil of the average farm was relatively poor in nutrients. Then an industrial process to capture nitrogen from the earth's atmosphere was perfected and widely deployed for making explosives in World War II.

After the war, nitrogen-fixing technology was turned over to enhancing agriculture. New plant varieties were developed to take advantage of a fertilizer source vaster and richer than anything known before.

The leap in nitrogen was accompanied by availability of more phosphorus, the other main essential for higher crop yields. Prehistoric deposits in the earth were discovered and mined from Florida to Morocco.

In the 35 years after World War II, fertilizer use nationally and around the Chesapeake Bay increased 10 times over. "We changed the world, and we wonder why things won't stay the same," says Dr. Lanyon.

With so many nutrients suddenly sloshing around the bay's drainage basin, a good deal of the stuff reached the water. Washed into streams by rain, phosphorus moved into the Chesapeake by the millions of pounds. Nitrogen followed a different path -- infiltrating ground water, which also seeps into the bay.

The huge new supplies of nutrients were foreign to the bay.

And just as humans now have trouble handling all the fat in our diet, the bay, with an ecosystem marvelously adapted to making the most of a nutrient-scarce world, fared poorly when almost overnight its lifeblood, the rivers and the ground water, became nutrient-rich.

The stuff overwhelmed the Chesapeake's huge meadows of underwater grasses, and it depleted oxygen in as much as two-thirds of the estuary's 18 trillion gallons.

To reverse the process, scientists have devised diet goals for the bay. By the end of the century, nitrogen and phosphorus from both sewage treatment plants and agricultural lands are to be cut 40 percent.

Those are the two major sources of the bay's over-enrichment.

With sewage, progress is largely a matter of proven technology and expenses that can be spread over millions of users. The goals for eight years from now seem within reach.

Agriculture is proving a lot tougher. We're dealing with changing the ways we grow crops and animals across 10 million acres of land, putting much of the burden on a small fraction of the population, which is all farmers amount to these days.

Here is where Dr. Lanyon thinks we need to look at the bigger picture, to consider the farm in the context of the system of food production we've created. For example, take a modern Pennsylvania dairy farm, which produces tons of white, foamy milk from one end, and from the other, even more tons of polluting nitrogen and phosphorus in the form of manure.

A single cow daily produces more than 80 pounds of manure, which retains up to 75 percent of the nutrients from the grain it is fed.

Nowadays many dairy farms have far more cows than they have land on which to use the manure's nutrients. And the trend is to increase the size of herds.

Such a system, Dr. Lanyon says, makes for plentiful, cheap milk. But it increases the amount of nutrient residue. He suggests splitting the cleanup cost among everyone tied to the nutrient stream -- feed companies, fertilizer dealers, even consumers of chocolate bars. (Hershey purchases 25 percent of southeastern Pennsylvania's milk.)

It's a good idea. And maybe we need to make other connections between our diets and our bay. The dairy farms that are over-enriching the Chesapeake are producing precisely the high-fat products we are being told to limit for our own health.

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