Is Peak Soil the New Peak Oil?

image from consumingspokane.typepad.com
Earlier this week I came across the catchy phrase "Peak Soil" in the headline of a Grist article. It plays off the concept of peak oil, which asserts that we are at or quickly approaching the point of maximum extraction of oil on earth, after which point we will enter a phase of terminal decline and constraints on the supply of oil. Peak oil has captured the imagination of the general public and has spawned any number of apocalyptic warnings.

The phrase "peak soil" plays off the same concept of depleting natural resources and the terminal decline of production, only the resource in this case is top-soil and the product is food. I reported previously on the book, "Dirt" by David Montgomery

I ventured up to Peone Prarie last week to take some pictures and they just happened to be harvesting the wheat. The dust was flying and I couldn’t help but think about the book I’m reading titled, “Dirt: The Erosion of Civilizations” by David Montgomery. In the book he looks at history through the lens of soil fertility, erosion and depletion concluding that the rise and fall of civilizations can often be traced to the exploitation and depletion of soils.

It is a fascinating read and I highly recommend it. Soil, or the thin brown line as Montgomery calls it, is much more complex than I thought. One example from the book describes a WSU study done in the mid ‘80’s comparing two dry land wheat farms near Spokane. Both farms were first plowed in 1908, one never using commercial fertilizers and the other using commercial fertilizers since 1948. Both farms boasted the same income, one leaving the field fallow every third year for a cover crop and the other harvesting continuously but paying big bucks for fertilizers and pesticides. They harvested more wheat but had much higher expenses that canceled out any economic advantage. Most importantly the researchers found that the organic farm was building soil while the conventional farm had shed 6 inches of topsoil between 1948 and 1985.

Montgomery sums up the study by saying, “With fifty more years of conventional farming, the region’s topsoil will be gone. Harvests from the region are projected to drop by half once topsoil erosion leaves conventional farmers plowing the clayey subsoil.” I’m assuming that the whitish soil I see peaking through at the top of the rolling ridges of freshly plowed palouse is the clayey subsoil peaking through.

Last night I was up on the prairie again and the topsoil was once again floating away into the atmosphere as farmers dug in their fields. I didn't have a catchy phrase for the problem last year, but I do now. Go here for another post on Montgomery's book. Go here for a post about what local grain co-op Shepherd's Grain is doing to address the issue of erosion of topsoil on the Palouse.