Soil erosion occurs 100 times faster on hillsides that are cleared of trees and converted to farmland, based on studies of 10 large river basins in the U.S. Southeast, says research led by a University of Vermont geologist. The university says that knowing the natural rate of erosion is important when setting environmental regulations. “The scientists made a startling discovery: rates of hillslope erosion before European settlement were about an inch every 2500 years, while during the period of peak land disturbance in the late 1800s and early 1900s, rates spiked to an inch every 25 years,” it said.
To calculate erosion rates, the researchers examined river sediment for presence of an isotope of beryllium that is created by cosmic rays and appears in highest concentrations in soil was was near the surface of the earth for the longest time. The scientist say only 6 percent of the eroded soil was washed away in rivers. The bulk of it lies at the base of hills and along valley bottoms. The researchers say their work should help in setting soil conservation strategies for the future. Voluntary soil and water conservation has been a central part of U.S. farm policy for decades.