New Evidence Shows Fertile Soil Gone From Midwestern Farms
Farming has destroyed a lot of the rich soil of america's midwestern prairie. Some scientists have come up with an estimate of how much soil and it is staggering. Here's npr's dan charles. If you fly over the midwest in spring and look down at the bare ground you can see slight differences in color. There's a lot of dark earth. What people call topsoil scientists. Evan thaler a phd student at the university of massachusetts. Amherst call it the a horizon black organic rich soil. That's really good for growing crops. And it's a storehouse of carbon in the form of living microorganisms and decaying plant roots. When settlers first arrived in the mid west it was everywhere in the roots in the prego down. Six to eight feet sometimes creating this really deep dark soils but plowing destroyed. A lot of releasing huge amounts of carbon dioxide contributing to climate change erosion also carried it away and now you'll also see areas that are a different color light. Brown thaler started comparing that color as seen from satellites with direct to soil measurements. And he found that the light brown soil had so little organic material. You really couldn't call it. A horizon soil that topsoil layer was gone consistently on particular parts of the landscape. The a horizon is almost always gone on hilltops finishes most of it just gradually fell down. The hillside as farmers tilled the soil year after year so he estimated topsoil loss across much of the other midwest based on. How much crop land is located on these erosion prone hills and just published the result in the journal peony s. He says a third of all the cropland in this whole area has completely lost. Its layer of topsoil that's way more than official estimates from the department of agriculture. I think the usda is dramatically underestimating. The amount of oss some soil scientists in the midwest are not convinced this method. They say relies on a lot of assumptions. But they agree. That soil loss is a big problem. And a case for instance. Who's minnesota's state soil health specialist to me. It's not important whether it's exactly a third. Maybe it's twenty percent. Maybe it's forty percent. There's a lot of topsoil gone from the helps. Farmers know that those eroded hilltops are less productive. She says and many of them are looking for solutions or essentially trying to make up for many years of fairly thoughtless practices. There's no quick fix. She says but there are ways to farm and also rebuild title starting with. Don't keep telling those fields. Maybe even grow grass their harvest. Hey instead of corn. Dan charles npr news.