Stripping away the Earth's skin in "Dirt"

One of the first things I learned in my introduction to geology class in college was that the brown stuff on the ground where plants grow was not dirt; it was soil and like the plants, it was alive. (Dirt was the stuff that accumulated on the floor in my dorm room.) The soil itself was not alive, in the sense of a plant, but it teemed with a vast community of organisms that helped work and rework the soil, making it a critical part of an ecosystem.

Good soil should be dark, crumbly, and rich in organic matter, some of which you can see, such as insect larvae, but more you cannot, such as the nematodes, microscopic tubeworms that reach densities of several hundred per teaspoon. Soil should feel cool and perhaps a bit moist. It should smell fresh and earthy. If not, the soil may suffer from a problem that has affected civilizations since humans first started to farm, that of soil abuse.

Soil abuse, or the degradation and accelerated erosion of soil, led to the demise of societies from the Middle East to the Amazon. It fostered slavery in Southern states and helped initiate the Civil War. Since the end of World War II, misuse of soil has degraded an area of land the size of China and India combined, land that could feed billions of people. Although we know how to stem soil erosion and reduce degradation, and have known for thousands of years, soil abuse is still a major problem worldwide and one that could be catastrophic as the world's population continues to expand and we run out of places to farm.

In the words of University of Washington geologist David R. Montgomery, "Soil is our most underappreciated, least valued, and yet essential natural resource." Montgomery's new book, "Dirt: The Erosion of Civilizations" (University of California Press, 285 pp., $24.95), explores the vital role of soil in the survival of humanity, and the lessons we can and must learn from our past misuse of what he calls "the skin of the earth — the frontier between geology and biology."

Soil abuse occurs in many ways. Farmers plant only a single crop year after year, which can rapidly deplete the soil of nutrients. After harvesting their crop, farmers plow under the residue instead of letting it remain on the ground as protective mulch. They plant on steep hillsides and don't create terraces. They fail to return nutrients via a mulch of manure.

Historically, soil abuse was less of a worldwide problem because farmers could usually move to new land when they had worn out their fields. In modern times, however, that option no longer exists. We are getting to the point where we have farmed all the land we can.

Montgomery offers many solutions, none of which he notes are new. Instead of plowing up the land, he advocates using disks to mix organic debris into the soil, and pushing seeds through organic matter with narrow, scythe-like tools called chisel plows. Promote small farms. Use terraces on steep slopes. Return manure to the fields. Apply fewer pesticides. "It requires farming by locally adapted knowledge — farming with brains rather than by habit or convenience," he writes.

Author appearance


David R. Montgomery will read from "Dirt: The Erosion of Civilizations" at 7 p.m. Thursday at Kane Hall on the University of Washington campus. Sponsored by University Book Store and University of Washington Program on the Environment; free (206-634-3400 or www.ubookstore.com).

In contrast to Montgomery's last book, "King of Fish: The Thousand-Year Run of Salmon," which admirably wove together history, science, and story, "Dirt" is more appropriate to academics, with fact piled upon fact. Gone are the connective tissues and transitions that made "King of Fish" so readable to non-academics.

Soil erosion and degradation are clearly major problems around the globe and ones which technology cannot fix; we have already passed through that phase. As with many environmental challenges humanity now faces, we need to rethink our relationship with the land. Perhaps the simplest one is the premise on which Montgomery ends his book: We need to think of soil as something other than dirt.