Review: Dirt by David Montgomery

As the soil goes, the civilization goes. That is David Montgomery’s argument in Dirt: The Erosion of Civilizations. He explains how numerous civilizations, from ancient times to the present, committed slow suicide by depleting their soil and other natural resources.

What happened to those first farmers, the Sumerians? They exhausted their soil, which in turn starved the army, which let rivals take over.

The overstretch and fall of the Roman Empire? Brought to you in part by the constant need to go further afield for farmland, as the soil closer to home eroded under intense cultivation.

Migration of Europeans to the New World? If you look at the waves of immigrants, they largely came according to when their own countries were running out of usable farm land.

Every time, the pattern is similar. When humans farm the land without regard to the soil, erosion becomes a problem. However, because the soil erodes gradually, over decades or centuries, no one deals with it. Instead, when it gets bad enough, the farmers just move somewhere else. At some point, it becomes impractical to continue moving or to acquire more land. Then things get ugly.

The ultimate case study is Easter Island, where the inhabitants depleted their key natural resources far below sustainability for the population, withering the local civilization.

Those aware of Jared Diamond’s Collapse will remember that story, and Dirt indeed shares much in common with Collapse. Both authors make the point that despite a popular view to the contrary, the golden age when all people lived in harmony with the land never existed. Modern and ancient civilizations alike have trashed their environments. However, not all have done so. There are examples of ancient and modern civilizations that practiced sustainable agriculture, using techniques like manuring and crop rotation.

Therein lies the hope of both books: that today’s civilizations can learn from the failures, and occasional successes, of past civilizations’ environmental approaches. In Dirt, Montgomery is upbeat about the rise of organic farming, at least in its original spirit of rotating diversified crops and using natural forms of fertilizer and pest control. However, he cautions, “California’s newly industrialized organic factory farms are not necessarily conserving soil. When demand for organic produce began to skyrocket in the 1990s, industrial farms began planting monocultural strands of lettuce that retained the flaws of conventional agriculture—just without the pesticides.”

Moreover...

...[the United States] government subsidizes conventional farming practices, whereas the market places a premium on organic produce....Over the past decade American farm subsidies averaged more than $10 billion annually. Although subsidy programs were originally intended to support struggling family farms and ensure a stable food supply, by the 1960s farm subsidies actively encouraged larger farms and more intensive methods of crop production focused on growing single crops. U.S. commodity programs that favor wheat, corn, and cotton create incentives for farmers to buy up more land and plant only those crops. In the 1970s and 1980s, subsidies represented almost a third of U.S. farm income. A tenth of the agricultural producers (coincidentally, the largest farms) now receive two-thirds of the subsidies.

Although Montgomery does not raise the issue, I wonder whether government subsidies could target “soil neutral” farming, similar to how incentives are emerging for “carbon neutral” businesses. The goal would be to channel innovation away from the farm as a factory that consumes its inputs (including soil) to the farm as a productive system that supports and is supported by its local ecology. Historically, market forces have not driven innovation in this direction because the return on investment is distant in time. But when you put things in terms of how we want to the leave the earth for our grandchildren—and how so many civilizations have unintentionally failed on this account—it’s worth asking how we can do better.

That is what Dirt is about. I’m not qualified to judge Montgomery’s historical analyses or his prescriptions for what to do, but he is making an important case. However, as a consciousness-raising exercise, the book can be a challenge because it wavers between textbook-like scientific detail and more accessible narrative. For those who want a seminar along with a story, that may be just right. Otherwise, Collapse may be the better bet. Either way, their subject matter is worth knowing about.