Let's Talk Dirt
When I was a child I went to visit my grandfather's farm outside Leamington. The fields that would soon deliver an abundance of tomatoes for Heinz or sweet corn and peas for Green Giant were freshly tilled revealing the rich, black soil that was the key to their productivity.
I didn't think of soil very much until recently when I took a few online courses in global food security. That's when I learned how, in our quest to feed eight billion people, we have resorted to excessive industrial agriculture.
Yale360 reviews a report on the decline of that once rich farmland across the American midwest.You hear many different numbers regarding that black Iowa soil. It’s often repeated that the topsoil — the nutrient-rich A horizon — was some 14 to 16 inches deep when the prairie was first broken, a fantastic depth of fertility rivaled only by some regions in the Ukraine. By the mid-1970s — roughly a century after the prairie was broken — it was reported that, in places, half of that topsoil had already been lost to erosion from wind and runoff.
In late February, three geoscientists from the University of Massachusetts — Evan Thaler, Isaac Larsen, and Qian Yu — published a paper called, “The extent of soil loss across the U.S. Corn Belt.” ...The number they arrived at is shocking. “We predict,” they wrote, “[that] the A-horizon has been completely removed from 35±11% of the cultivated area of the Corn Belt.” Plus or minus 11 percent is a large range of uncertainty. But its meaning is plain. At best, 24 percent of the topsoil in the Corn Belt has been completely removed by farming. At worst, 46 percent has been lost.
It’s worth being clear here. The authors aren’t talking about reduced soil fertility or loss of mineral nutrients. They’re talking about the complete removal of the medium in which crops are grown — the utter bankruptcy of the organic richness that lay for centuries under the tallgrass prairie. The authors argue, in a sense, that we’ve been farming in the dark, though they’re never quite that blunt.