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Professor David Montgomery: Our Disappearing Dirt

by Anna Soref

Global warming, polluted water and air, vanishing rainforests and animal species—our plates are full of worry for the environment. Yet a growing movement wants our attention, concern and action focused on something right under our feet—dirt. Why? We’ve lost about one-third of the world’s topsoil and most of that loss has taken place in the last 50 years.

dirtpageModern agriculture’s rampant use of pesticides and plows is destroying the quality, and quantity, of the planet’s soil. The bottom line: without fertile soil, we cannot produce the food necessary to live. The scary number: we could be out of fertile soil in the next 100 years.

If you look back through history, from Mesopotamia to the Dust Bowl, when a civilization didn’t take care of its soil, it proved unable to take care of its people. The fate of a society as directly tied to how its people treat the land is the premise of Dirt: The Erosion of Civilizations (University of California Press, 2007), written by geology professor David Montgomery, at the University of Washington.

Do the Math

Apparently dirt should be on the endangered species list—and just as with animals, its dwindling numbers are cause for alarm. “You don’t have to completely run out of soil to have it adversely affect a society,” Montgomery says. “We know that the global population is expected to rise substantially by 2050. If we are degrading our agricultural land at the same time that we are growing our population, somewhere those curves are going to intersect—that’s not a good thing. The areas that are most at risk in the next half-century are the semiarid lands, which is where about one-third of humanity lives. And if we continue to degrade soils as we are, then it’s no exaggeration that civilization is at stake.”

What could we possibly be doing to consume and lose so much dirt? A primary culprit is that seemingly benign fundamental piece of farming equipment the plow. “The very thing it’s designed to do, turn the earth, leaves the soil vulnerable and bare,” remarks Montgomery. Contrast conventional farmland with other natural landscapes such as forests or mountains, where you don’t see a lot of bare ground. “Most of the surface of the earth outside the arid areas is covered with plants. For hundreds of millions of years the leaves and needles have provided protection, reducing erosion by holding soil in place,” he explains.

In addition to the plow, what are now called “conventional” farming methods, but are really a recent departure from agricultural traditions, involve pesticide application that degrades soil nutrition. Monocrop farming, a cornerstone of industrial agriculture, leaves the ground bare and exposed for months at a time. So these methods result in weak, exposed soil that is very susceptible to fast rates of erosion in, say, a rainstorm, according to Montgomery.

This troubling news about the plow and high-yield farming begs the question, How can we possibly farm and produce the rising amounts of food necessary without them? Organic and no-till farming are the answers, claims Montgomery. Organic farming methods help maintain the fertility of the land, increasingly important in light of a growing body of research showing that the soil’s nutrients, such as calcium, magnesium and iron, have dropped between 15 and 30 percent during the past 70 years due to industrial farming methods.

“The whole idea of cycling nutrients and bringing matter back to the land, and supporting life in the soil that mediates the transfer of nutrients from earth to plants is the very essence of organic farming,” Montgomery says. “Instead of synthetic pesticides and fertilizers, organic farming uses animal manure, compost, natural pest control, and crop rotation to invest in the soil. Organic farming keeps matter in the soil that helps retain moisture, improves soil structure, helps liberate nutrients, and is itself a source of plant nutrients.”

Increasingly, farmers are opting for no-till farming techniques. These rely on farm tools that rotate less of the soil, and utilization of cover crops—vegetation planted in between growth seasons that holds the soil in place and provides other benefits.

Soil Sustainability

The key to long-term soil sustainability is twofold, Montgomery points out. First is just keeping the soil in place by eradicating the plow; second is maintaining the fertility of the soil that’s there. But if the soil erodes much faster than it’s produced, you can have a very fertile soil that will disappear; so we need to get both right. For example, large-scale organic farms that are plow-intensive might have more fertile, robust soil than “conventional” farms, but they may still erode the earth more quickly than new soil can be produced.

Many are skeptical that organic, no-till farming can feed the world, but Montgomery assures us it can. “If you look at farming, there is a very counterintuitive effect in terms of productivity. Large-scale farms aren’t necessarily more productive than small farms. In fact, if you look at the gross output of total amount of food per hectare instead of the productivity of an individual crop per hectare—which is the relevant way for feeding our soon-to-be post-oil world—then the most productive farms are small-scale labor-intensive farms, not large-scale industrial agriculture. Therefore, if you really take the challenge of how will we feed the world later this century, the idea that we would do it with large-scale industrial agriculture actually flies in the face of the reality,” he says.

The Dirt on GMOs

Amid the growing revelation that industrial farming methods are rendering our soil infertile and promoting staggering rates of erosion, the added effects of genetically modified organisms loom large. Thus far, potential health concerns posed by GMOs have centered on our food supply, not the soil. But considering that GM plant material will eventually wind up in the soil, questions about possible adverse long-term effects arise.

“What soil ecologists have learned in the past couple of decades about how the life below ground is so finely tuned to the life above ground is simply amazing,” Montgomery reflects. “For instance, the way plants exude sugar that is tailored to grow the microbes that actually assist the plant with nutrient transfer from the soil into the plant and serve as a shield against pest and disease organisms. So, if we start introducing new organisms designed to do particular things—GMOs—how are they going to interact with a system that has evolved over a much longer time cycle? There is a great chance for unintended consequences. And all of this is for a promise of increased yields from GMO production that has not been met yet. There’s not a lot of evidence that yields have gone up with GMO crops.”

Essentially, as with most GMO concerns, how they will ultimately affect the soil is a wait-and-see proposition. But Montgomery asserts an even bigger problem with GMOs. If the goal of this technology is to actually feed the undernourished and truly destitute, you are never going to feed these people who don’t have money by selling them proprietary technology, he warns. “They don’t have any money. So the idea that you can feed the hungry with seeds that have to be purchased each year from a company is ludicrous.”

Foundation of Our World

We don’t give dirt a whole lot of credit; we spend more time maligning it than singing its praises. Even the term dirt is synonymous with grime, filth and muck. But consider that there are 10 billion microorganisms in a handful of fertile soil. That’s more than the population of our planet—in one handful of dirt. Soil is truly a complex and little-known entity when you think how much life it holds, and gives. “Our world is built upon a world that we take for granted, that we don’t notice, that we are barely aware of, and yet it’s foundational for our world,” Montgomery says. “Ninety-seven percent of our food comes from the soil. It’s the one resource we can’t afford to undercut because it really is the foundation of our world.

“We’ve been remodeling many ecosystems into agro-ecosystems to feed ourselves, and we’re doing it with a philosophy of adding fertilizers and poisoning the life in the ground that we don’t understand and don’t like. The problem with pest killing like that is it’s not the beneficial organisms that come back first after we apply biocides; it’s the pest organisms. Consequently a biocide-based agriculture is essentially a recipe for addiction.” Again, Montgomery states the answer for sustainability lies in organic farming methods that work with this complex, bio-rich soil, which is far from muck, grime or filth.

Getting people to somehow relate to dirt, to care about soil, is vital to reverse the current destructive systems in place. “Soil is the most underappreciated and devalued natural resource,” Montgomery continues. “Whales are these beautiful charismatic, majestic creatures, and it’s easier to rally people to save the animals that we can relate to in the megafauna than the bugs and things that people don’t really like. Can you imagine rallying people to save the worms? That would be on Stephen Colbert in a minute!”

As passionate as he is about the plight of dirt in the face of erosion, Montgomery concedes he doesn’t exactly get excited when he sees the stuff. “If I go to the ocean and see a whale breach, it’s an incredible emotionally positive experience; it’s inspiring. And I have to admit, if I look at a landscape covered by fertile soil I am not particularly inspired. Yet when I see land that has been so degraded it can no longer support farming and life—and I’m thinking of places in the Amazon I’ve been to that have been stripped of forest and intensely harvested and now are a barren wasteland—that hits me in the gut; there’s a real intense emotional reaction in terms of how people could so abuse the land that it wouldn’t be able to take care of them in the future. So, if I go to a well-run farm and stick my hands in fertile soil, I’m impressed; but it doesn’t strike me with the same emotional impact as on the negative side. And that, I think, is one of the problems with soil—it’s not as sexy or exhilarating as a whale breaching. Even so, in the big picture of things, it’s far more important.”

As an undergrad, Montgomery loved the field of geology because he could read the history of the earth through the rocks that compose it. While he was learning all about the importance of rocks, a book he discovered in a bargain bin at a local bookshop altered his course of study. It was an out-of-print work, written immediately after the Dust Bowl, about soil degradation. It changed the way he viewed soil. Montgomery’s years of teaching and fieldwork made him realize that there’s a communication or education gap between people like himself who spend decades studying these ideas and those who never give them a thought. He wrote Dirt to offer readers a look at soil through the lens of history, because it takes the politics off the table.

Certainly awareness about the importance of soil fertility and even erosion is gaining ground. Urban farmers, Community Supported Agricultural programs, and media such as the film Food, Inc. all exist, in part, to turn the tide on soil degradation. “Today I’ve seen a big attitudinal shift on the part of students,” Montgomery notes. “They are thinking and talking about sustainability, whereas five years ago they weren’t.”

The Next Step

Heartening news about soil degradation is that human behavior can actually restore soil much quicker than nature can build it. “I’ve seen farms turned around from poor soil to adequate soil to producing higher yields in a decade or two,” says Montgomery. “To a farmer, that might be too long, but the idea that you can reinvest in the soil and have it return in that time scale is amazing.”

Although it’s easy to leave it up to farmers to adopt methods to protect soil, there’s a lot an individual can do. Consider composting. “My wife is an organic gardener and she has literally transformed our yard over 10 years,” relates Montgomery. “She did it with mulching and composting mostly, and it’s had an incredible effect on the life of the soil and the productivity of the yard. Composting is a great way to revitalize soil.”

He also suggests thinking about any of the spaces to which you have access, such as your lawn, the soil around the trees on the street, or the planting bed in an apartment window. How one treats the soil can have a tremendous impact on what it produces, whether you’re growing food, flowers or trees.

Of course, buying organic produce and foods is an excellent means of supporting healthy soil, Montgomery concludes. “Although right now there’s no way to ascertain if the farmers you buy from are using methods that support the soil, most of the organic farmers I know are very sensitized to the issue of erosion and are managing their land pretty darn well.”

To find out more about ways you can prevent soil erosion and contribute to soil fertility, visit Remineralize the Earth at and the Bionutrient Food Association at