Guno צְבִי
We fight, We win, Am Yisrael Chai
Dust bowl coming to parts of the mid west
https://www.npr.org/2021/02/24/9673...deMi7ut6llQRrshg1xV5YeNxF1TwnPchL5Mdqo0798kFAFarming has destroyed a lot of the rich soil of America's Midwestern prairie. A team of scientists just came up with a staggering new estimate for just how much has disappeared.
The new study emerged from a simple observation, one that people flying over Midwestern farms can confirm for themselves. The color of bare soil varies, and that variation is related to soil quality.
The soil that's darkest in color is widely known as topsoil. Soil scientists call this layer the "A-horizon." It's the "black, organic, rich soil that's really good for growing crops," says Evan Thaler, a Ph.D. student at the University of Massachusetts, Amherst.
It's full of living microorganisms and decaying plant roots, also called organic carbon. When settlers first arrived in the Midwest, it was everywhere, created from centuries of accumulated prairie grass. Plowing, though, released much of the trapped carbon, and topsoil was also lost to wind and water erosion. The soil that remains is often much lighter in color.
Thaler and his colleagues compared that color, as seen from satellites, with direct measurements of soil quality that the U.S. Department of Agriculture has carried out, and found that light brown soil contained so little organic carbon, it really wasn't A-horizon soil at all. The topsoil layer was gone. What's more, Thaler found that this was consistently the case on particular parts of the landscape. "The A-horizon was almost always gone on hilltops," he says.
Even the study's critics, though, agree that topsoil is endangered. "To me, it's not important whether it's exactly a third," says Anna Cates, Minnesota's state soil health specialist. "Maybe it's twenty percent, maybe it's forty percent. There's a lot of topsoil gone from the hills."