If you’ve been paying attention in class, you’ll recall dead zones, the patches of low-oxygen water that snuff out almost all sea life. They’re expanding along U.S. coasts, but the most significant, the deadest of the dead zones, has always been in the Gulf of Mexico, where the fertilizers from America’s farmland are flushed (basically, more nitrogen creates more algae, which eats up all the oxygen as it decays).

This year, because of vast corn plantings and the massive Midwestern floods, the Gulf’s dead zone is predicted to reach record size—specifically, the size of New Jersey. That’s a stunning 27 percent larger than the previous record, and it should raise the volume on the already deafening biofuel debate.

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