In a discovery that has repercussions for everything from domestic agricultural policy to global food security and the plans to mitigate climate change, researchers at the University of Massachusetts recently announced that the rate of soil erosion in the Midwestern US is 10 to 1,000 times greater than pre-agricultural erosion rates. These newly discovered pre-agricultural rates, which reflect the rate at which soils form, are orders of magnitude lower than the upper allowable limit of erosion set by the U.S. Department of Agriculture (USDA).
The study, which appears in the journal Geology, makes use of a rare element, beryllium-10, or 10Be, that occurs when stars in the Milky Way explode and send high-energy particles, called cosmic rays, rocketing toward Earth. When this galactic shrapnel slams into the Earth’s crust, it splits oxygen in the soil apart, leaving tiny trace amounts of 10Be, which can be used to precisely determine average erosion rates over the span of thousands to millions of years.
“We went to fourteen small patches of remnant native prairie that still exist in Iowa, Minnesota, South Dakota, Nebraska and Kansas, and used a hand auger to collect deep soil cores, in material that dates back to the last Ice Age,” says Isaac Larsen, professor of geosciences at UMass Amherst and the paper’s senior author. “We brought this soil back to our lab at UMass, sifted it to isolate individual sand grains, removed everything that wasn’t quartz, and then ran these few spoonfuls through a chemical purification process to separate out the 10Be —which was just enough to fit on the head of a pin.”
Read more at: University of Massachusetts - Amherst
Caroline Quarrier (r) and Brendon Quirk preparing to extract a soil sample from Stinson Prairie, Iowa. (Photo Credit: Isaac Larsen)