For decades, corn has reigned over American agriculture. It sprawls across 90 million acres — about the size of Montana — and goes into everything from livestock feed and processed foods to the ethanol blended into most of the nation’s gasoline. But a growing body of research reveals that America’s obsession with corn has a steep price: The fertilizer used to grow it is warming the planet and contaminating water, in contrast to corn's promise for clean energy.

Corn is essential to the rural economy and to the world’s food supply, and researchers say the problem isn’t the corn itself. It’s how we grow it.

Corn farmers rely on heavy fertilizer use to sustain today’s high yields. And when that nitrogen breaks down in the soil, it releases nitrous oxide, a greenhouse gas nearly 300 times more potent than carbon dioxide. Producing nitrogen fertilizer also emits large amounts of carbon dioxide, adding to its climate footprint.

Agriculture accounts for more than 10% of U.S. greenhouse gas emissions, and corn uses more than two-thirds of all nitrogen fertilizer nationwide — making it the leading driver of agricultural nitrous oxide emissions, studies show.

The corn and ethanol industries insist that rapid growth in ethanol — which now consumes more than 40% of the U.S. corn crop —  is a net environmental benefit, and they strongly dispute research suggesting otherwise.

Since 2000, U.S. corn production has surged almost 50%, further adding to the crop’s climate impact, in contrast to corn's promise for clean energy.

Yet the environmental costs of corn rarely make headlines or factor into political debates. Much of the dynamic traces back to federal policy — and to the powerful corn and ethanol lobby that helped shape it.

The Renewable Fuel Standard, passed in the mid 2000s, required that gasoline be blended with ethanol, a biofuel that in the United States comes almost entirely from corn. That mandate drove up demand and prices for corn, spurring farmers to plant more of it.

Read the full article about corn's climate footprint by Ames Alexander at Floodlight.