Graphic: Annabel Driussi for Our Daily Planet

By Amy Lupica, ODP Staff Writer

New research shows that fertile, carbon-rich topsoil is completely gone from one-third of all farmland in the Midwest, severely impairing crop growth and future harvests. Scientists noticed that soil in the region was changing color, and found that centuries of plowing and poor planting locations eroded much of the most fertile topsoil and released trapped carbon into the atmosphere. Seventy-five percent of farmland in the region is used solely for corn and soybeans – these two crops play major roles in many supply chains, including energy and fuel. Forty percent of the nation’s corn crop goes to producing ethanol, an additive to produce cleaner-burning gasoline.

Why This Matters: Experts say this “growing” problem is mostly due to over-tilling the soil and other unsustainable farming practices. They also say that the erosion isn’t over, and that to save farming in the Midwest, drastic action must be taken. Losing one-third of farmland may not sound like a lot, but there are 127 million acres of agricultural land in the region. Agriculture in the Midwest represents billions of dollars to the nation’s GDP.  Massive crop failure there would have devastating ripple effects on the food market, the energy market, and more. 

How did we get here?

Evan Thaler, a Ph.D. student at the University of Massachusetts, Amherst, who worked on the new study, says that decades of plowing the land are to blame. He explained that as farmers tilled the soil, it eroded down hillsides and became vulnerable to wind and water erosion. He said the researchers were able to predict where the lack of topsoil would be most severe, “the [topsoil] was almost always gone on hilltops,” he says.  The Agriculture Department has under-estimated the loss of topsoil, according to the study’s authors.

In addition to over-tilling and planting on erosion-prone land, other experts are critical of the two-crop rotation that occurs on a majority of the region’s farmland. Rotating crops, or planting a different crop every season, is crucial to returning nutrients to the soil and ensuring future crop yield. But in the Midwest, farmers have been cycling between two for decades: corn and soybeans. Now, the land is reaping what decades of oversimplified farming practices sowed.

Scientific Debate

Some experts disagree with Thaler’s study and believe he may be overestimating how much topsoil has vanished. Michelle Wander at the University of Illinois said that the study relies too much on assumption and that topsoil may also end up mixed into lower layers of soil rather than vanish. But Thaler is sticking to his guns, and he has supporters across the scientific community. Anna Cates, Minnesota’s state soil health specialist, is one of them. “We’re essentially trying to make up for many years of fairly thoughtless practices,” said Cates, “maybe it’s twenty percent, maybe it’s forty percent. There’s a lot of topsoil gone from the hills.” Thaler believes the federal government isn’t doing enough to save Midwestern soil, “I think the USDA is dramatically underestimating the amount of loss.”