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 fertilizer 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.

--Michael Pollan, The Omnivore's Dilemma