Agricultural Lands Are Losing Topsoil—Here’s How Bad It Could Get
By Nathaniel Scharping, Eos/AGU.
Excerpt: Good topsoil does not accumulate quickly. Less than a tenth of a millimeter of soil forms per year in some places, though the amount can vary depending on the environment. Compare that to the rate of topsoil erosion in agricultural regions of the United States: around half a millimeter per year, or 5 times as much, according to a recent study in the journal Catena. That imbalance is imperiling our ability to grow food in large swaths of America’s breadbasket. ...Croplands see far higher rates of soil erosion than other places, often because tilling leaves soil exposed. It’s in croplands that erosion is most impactful, however. Past studies estimated that erosion costs the United States about $8 billion each year and that globally, it reduces agricultural food production by 33.7 million metric tons per year. Rates of soil erosion have likely worsened over the past decade, and climate change will probably make that trend worse. ...Researchers have suggested potential strategies for reducing soil loss. Increasing the use of cover crops, which Basso said act as “an umbrella” for soil by reducing the impact of raindrops, is one. Alley cropping, or planting rows of trees and shrubs in fields to shield soil and hold it in place, is another strategy....