In the third of the Seattle Arts & Lectures series on the culture and politics of sustenance, UW geologist and Macarthur Fellow David Montgomery walked us through a few millenia of catastrophes caused by people abusing dirt. And in fact, he says, if we don’t knock it off, we stand to run out of fertile topsoil in only one or two more centuries.
First, the science. Basically, Mother Nature sees her job as moving all these mountains right here down there into the ocean, so that she can make room for her new mountains. Here’s how it happens. Rock thrusts up from the mantle of the globe, and heat, cold, water, plant roots, chemical processes and other forces break it up and grind it down. Plants and animals die on it, and worms fold their remains into the mix. Then rain and wind carry it downhill. This is nature’s long slow tumble of creation and destruction. David says that it can take about 500 years to produce an inch of topsoil; the covering of topsoil around the globe is only about one to three feet thick. Comparing the earth to the human body, soil is a “much thinner and more fragile layer than human skin.”
At the same time, the “fundamental condition for sustaining a civilization is sustaining soil and fertility.” Over and over again, civilizations from Neolithic Europe to the Easter Islands to the American Dustbowl have radically suffered or even disappeared as they have exhausted their soil. Remember that it can take 500 years to produce an inch of topsoil? Right now, the rate of erosion is one inch every 60 years.
David calls soil degradation an “under-appreciated crisis, a secret silent environmental disaster.” This was not news to the people living through it; Plato, for instance, comments that “the rich soft soil has all run away, leaving the land nothing but skin and bone.” And (skipping ahead a few years) our own George Washington observed that the situation could be turned around if farmers “were taught how to improve the old, instead of going in pursuit of new and productive soils.”
George had it right–the real cause is not THAT we farm, but HOW we farm. David traces the growing crisis all the way back to the invention of the plow; the plow, he says, fundamentally altered the balance between soil production and erosion, dramatically increasing erosion by breaking up the ground cover that knits the soil in place. (We won’t even discuss the modern “512 disk ripper” plow for ridding your fields of “soil compaction.”) In short, we practice self-destructive agriculture. As FDR had it, “a nation that destroys its soils, destroys itself.”
But if we change our agricultural practices, we can turn the situation around. And we actually already know how to do this! (–And have for centuries.) For instance, we could cut subsidies for erosive agricultural practices, and we could support no-till ag, terracing, and other soil-preserving strategies. To rebuild soil, you need to apply just two things, David says: organic matter and labor. Small labor-intensive organic farms are in fact the most productive in the world. But to get there from here, we need to alter our whole socio-economic model of food production: we need to stop treating soil as a commodity and start treating it as the fragile ecosystem that it is.
Great talk!–I can’t do justice to it in just these few paragraphs. Get the book! (David R. Montgomery, University of California Press, 2007)