Dec. 18, 2008 -- America's taste for meat is a well-known enemy of the environment; growing feed for livestock guzzles far more oil and water, and pumps out far more nitrogen-laced runoff, than if we were all vegetarians.
Now new research shows how the leftover fertilizer is contributing to an oxygen-starved dead zone where the Mississippi River drains into the Gulf of Mexico. Last summer, the zone was nearly the size of Massachusetts.
Gidon Eshel of Bard College at Simon's Rock in Massachusetts and Pamela Martin of the University of Chicago calculate that if Americans kicked their meat habit, it would prevent seven million tons of nitrogen from spilling into the gulf -- a reduction of nearly 90 percent.
"When we did the calculations, it was astonishing," Eshel said. "The main reason is we're feeding so much corn to livestock. It takes 4.5 times more cropland to do that than if you feed people a plant diet, and corn is so nitrogen-intensive."
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Cutting down on nitrogen run-off is a big deal, because if it continues unchecked it could threaten shrimp and fishing industries in the gulf, said William Battaglin of the United States Geological Survey.
"Conditions have not been catastrophic to fisheries yet," he said. "The concern is that if this keeps up, you could turn the whole place into the Black Sea, with everything dead."
As it is, the dead zone has grown steadily since its discovery in the 1970s, mostly because of corn-related agriculture. Of the 81.5 million acres of corn grown in the United States today, 53 percent of it winds up on your plate as chicken breasts, pork chops and burgers.
On average, farmers spread 150 to 200 pounds of nitrogen on each acre of their corn fields to boost yields, more than almost any other crop by far. Most of it runs off into the Gulf of Mexico.
Plankton gobble up the sudden glut in nutrients and excrete organic matter into the water and sediment. As the matter decays, it sucks oxygen out of the water en masse, suffocating any animals that stick around.
If the country switched to a vegan diet, it would drastically reduce the gulf's building dead zone, Eshel said. But he recognizes that's not going to happen anytime soon.
"What we need is to treat cheese, dairy, and meat as condiments, to be used rarely instead of at every meal." He said. "And we need policies in place that require spatially distributed farms, instead of ultra-efficient, huge farms that encourage the use of so much nitrogen."
However, Battaglin says, America appears just as addicted to its massive farms as it is to meat.
"Honestly, even if a large portion of food grown for livestock were not grown for livestock, I think it'd still be grown. Farmers would find a different market for their product," he said. "I don't see farmers saying 'oh well, I'm not going to grow corn anymore; I'll grow oak trees or apples instead'."
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