Across the northern plains, native grassland is being turned into farmland at a rate not seen since the 1920s. The environmental consequences could be disastrous.

While few seem to be aware of it, a massive shift is under way in the northern plains, with ramifications for the quality of our water and food, and, more fundamentally, the long-term viability of our farms. A study published in February 2013 in the Proceedings of the National Academy of Sciences found that between 2006 and 2011, farmers in the Dakotas, Minnesota, Nebraska, and Iowa—the Western Corn Belt—had plowed up 1.3 million acres of native grassland in order to plant corn and soybeans. “People had been talking about the land conversion,” says Chris Wright, an assistant research professor at South Dakota State University and a co-author of the report, “but there weren’t any recent numbers.”