The Omnivore's Dilemma - Michael Pollan [25]
Ecologically this is a fabulously expensive way to produce food—but “ecologically” is no longer the operative standard. As long as fossil fuel energy is so cheap and available, it makes good economic sense to produce corn this way. The old way of growing corn—using fertility drawn from the sun—may have been the biological equivalent of a free lunch, but the service was much slower and the portions were much skimpier. In the factory time is money, and yield is everything.
One problem with factories, as compared to biological systems, is that they tend to pollute. Hungry for fossil fuel as hybrid corn is, farmers still feed it far more than it can possibly eat, wasting most of the fertilizer they buy. Maybe it’s applied at the wrong time of year; maybe it runs off the fields in the rain; maybe the farmer puts down extra just to play it safe. “They say you only need a hundred pounds per acre. I don’t know. I’m putting on closer to one hundred eighty. You don’t want to err on the side of too little,” Naylor explained to me, a bit sheepishly. “It’s a form of yield insurance.”
But what happens to the one hundred pounds of synthetic nitrogen that Naylor’s corn plants don’t take up? Some of it evaporates into the air, where it acidifies the rain and contributes to global warming. (Ammonium nitrate is transformed into nitrous oxide, an important greenhouse gas.) Some seeps down to the water table. When I went to pour myself a glass of water in the Naylors’ kitchen, Peggy made sure I drew it from a special faucet connected to a reverse-osmosis filtration system in the basement. As for the rest of the excess nitrogen, the spring rains wash it off Naylor’s fields, carrying it into drainage ditches that eventually spill into the Raccoon River. From there it flows into the Des Moines River, down to the city of Des Moines—which drinks from the Des Moines River. In spring, when nitrogen runoff is at its heaviest, the city issues “blue baby alerts,” warning parents it’s unsafe to give children water from the tap. The nitrates in the water convert to nitrite, which binds to hemoglobin, compromising the blood’s ability to carry oxygen to the brain. So I guess I was wrong to suggest we don’t sip fossil fuels directly; sometimes we do.
It has been less than a century since Fritz Haber’s invention, yet already it has changed the earth’s ecology. More than half of the world’s supply of usable nitrogen is now man-made. (Unless you grew up on organic food, most of the kilo or so of nitrogen in your body was fixed by the Haber-Bosch process.) “We have perturbed the global nitrogen cycle,” Smil wrote, “more than any other, even carbon.” The effects may be harder to predict than the effects of the global warming caused by our disturbance of the carbon cycle, but they may be no less momentous. The flood of synthetic nitrogen has fertilized not just the farm fields but the forests and the oceans too, to the benefit of some species (corn and algae being two of the biggest beneficiaries), and to the detriment of countless others. The ultimate fate of the nitrates that George Naylor spreads on his cornfield in Iowa is to flow down the Mississippi into the Gulf of Mexico, where their deadly fertility poisons the marine ecosystem. The nitrogen tide stimulates the wild growth of algae, and the algae smother the fish, creating a “hypoxic,” or dead, zone as big as the state of New Jersey—and still growing. By fertilizing the world, we alter the planet’s composition of species and shrink its biodiversity.
5. A PLAGUE OF CHEAP CORN
The day after George Naylor and I finished planting his corn, the rains came, so we spent most of it around