How To Save Earth's Disappearing Topsoil & Store Carbon Too

| Wed Aug. 8, 2007 2:40 PM EDT

Ploughs and a rapidly growing world population are combining to deplete the Earth's soil supply. A new study from the University of Washington finds that long-established farm practices appear to increase soil erosion 10 to 100 more than the rate at which soil is created. The good news is there is a solution. No-till agriculture eliminates ploughing, instead mixing the crop stubble with the top layer of soil using a method called disking. Study author David Montgomery notes that as oil becomes more expensive and less available, preserving soil fertility through no-till farming becomes even more important, since it requires less fertilizer and many fewer passes with a tractor. No-till farming could also prove a major benefit in a warming climate by increasing organic matter in soil, and as much as tripling its carbon content in less than 15 years. More carbon in the ground means less in the air.

"If all farms on the planet were converted to no-till, the range of estimates for sequestered carbon runs from 10 percent of current carbon emissions to about half," says Montgomery. In his book, "Dirt: The Erosion of Civilizations," Montgomery links the demise of history's major civilizations to how long it took them to deplete their soil supply. . . That's why that organic cheese and tomato sandwich on whole organic wheat bread you're munching is only good for you (in the short term) and not for the planet unless the components are also sustainably farmed. JULIA WHITTY

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