Dishing Dirt with David Montgomery

'Dirt', on Amazon

David Montgomery is professor of Earth and Space Sciences at the University of Washington. His new book, “Dirt; The Erosion of Civilizations”, is a very readable geologic history of agriculture and soil erosion that includes warnings of our own over use of soil and prescriptions for better soil stewardship. We caught up about his book, agribusiness, our prospects as a civilization, peak soil and the movies.

Leslie Berliant: We have heard that climate change, peak oil, peak water, disease have all been the greatest movers in history or will be in our future. You say it’s really soil. Why?

David Montgomery: One of the things that became very clear in doing the research for the book is that if you look at the things that influence human societies, you can break them into two parts. There are long wave length trends in history, and the way we treat soil is one of those. Then there’s the high frequency noise; wars, climate change, disease -- the things we think of as changing history. You can’t predict the timing, they’re very random. With soil it’s very predictable, it just happens over long time periods. We really need three things to survive on this planet; clean air, fresh water and fertile, productive soil to build food. We can’t afford to build a society that doesn’t take care of all three over the long run. There’s lots of awareness of the very important role climate will play in the next century, a lot of people have an idea that fresh water is limited. It’s much less appreciated as to the fundamental importance of soil and the care of soil, soil stewardship. That’s just as important to the future of humanity as climate change, fresh water and population, but there is very little discussion of it. That’s why I wrote the book. The good news on the soil end is that it’s a trackable problem. We can look at the history of civilizations and think we’re doomed, but we know how to take care of soil. It’s just that we're not doing it. With changes to the way we farm, we can not only build an agricultural system that sustains soil, but we can help combat global warming if we get ahead of the curve on the next big crisis which will be the soil problem. When I started writing the book, I had no idea how much carbon could be sequestered if we reinvested in soil fertility as a society. We can truly consider it an intergenerational investment, but it’s one that can pay dividends now.

LB: You talk about a change in the 1970’s that reduced farmland, what happened?

David Montgomery

DM: One of the things that happened was that there was a reduction in soil conservation practices that led to a decrease in farmland. Part of it was paving over farmland, which is still happening now. But primarily, in the era when the Soviets needed so much wheat, we started trying to produce lots of wheat to meet those needs, so soil conservation practices started to be short changed. Then the pendulum swung back in the late 80’s and 90’s with advances in reducing soil loss in the United States. But in the last year, the rush to bio fuels, and particularly conventionally grown corn, may undo a lot of good work in soil conservation in the rush to solve the oil problem. We need to be very careful in how we go about the potential to solve the fuel crisis with bio fuels. If we grow corn in a way that is very erosive, we may trade a system that mines oil for one that mines soil and if we do that, we haven’t solved the problem, we’ve just handed a different problem to the next generation.

LB: If wheat, rice, barley and maize weren’t historically dominant crops, what were and why did these non-dominant crops ascend to the top?

DM: They weren’t historically dominant plants. In their native ecosystems, they are minor players but they provided a source of food you could store, therefore people started growing them and favoring them. You see the great variety of dogs from wolves due to selective breeding. I mean, how did a Pug come from a wolf? Grains are the same way. They’re pretty different from the native plants. They are essentially symbionts. We’ve taken those plants out of their native environments and made them into dominant plants which they never would have done on their own. You could ask whose using who? They have become very successful plants because they were useful to people. And our numbers have multiplied greatly because they were of such great value to us.

LB: I recently read Devil in the White City, which is about the Chicago World's Fair. Much of it is about engineers conquering the soil to build great feats of architecture. What role does vanity play in reaching peak soil?

DM: Well you could argue whether it's vanity or hubris. I would argue its more hubris than vanity. The history of agriculture is one in which people are attempting to impose particular technologies on the land. We’re trying to bend the land to our will. We have a technology, plowing, and all the modern agricultural technology which we impose on the land regardless of the soil. One of the biggest challenges of the 21st century is figuring out how we adapt; how we farm to local soil instead of bending soil to our technology. If we do the same thing everywhere, it sort of invites the kind of large scale erosion that’s been happening, albeit slowly. We need to redefine the fundamental ethos underlying agriculture, sort of like the Hippocratic Oath of do no harm in medicine, we need an oath that says preserve the soil fertility. Growing large amounts of crops in a way that decreases our ability to do so in the future invites disaster. One of the things I was not aware of when I started writing but became convinced of is that the arguments that organic agriculture can’t feed the world are false. Some of the highest crop yields on the planet are from organic, no till farms. We know how to farm in ways that will preserve the soil, it's not like it’s a big mystery. It’s all about how we farm and the key thing that structures how we farm are the incentives. Many of the subsidies and agricultural incentives promote soil degradation. Where’s the wisdom in that? You can trust the ability of the market place to guide people in ways of what makes sense to them to buy, but if the government is setting up a system that short changes agriculture in the long run, what sense is that?

LB: What can individuals do to help prevent soil erosion?

DM: That’s a really good question. The most obvious thing is to bug their legislators about the farm bill. One of the awkward truths about the soil erosion problem is that there’s no labeling for no till fields like there is for organic. It’s very hard to know if the food you’re getting was grown in a way that protects the soil, Generally, organic farms are managed in a way that takes care of the soil. The whole local food movement also actively helps because you know your food source. Odds are if you’re getting food from large corporate farms, there’s a much higher chance that they’re not taking care of the soil in the long run, but there’s not much in the way of labeling or feedback. It’s an awkward problem. With climate change can walk more, drive less, use less energy. There’s an obvious connection between putting gas in the car and climate. I started walking to work a couple of years ago, a mile and a half each way, for example, There’s much clearer things one can do as an individual regarding climate. The tools a consumer has for addressing the soil problem is being careful about where you buy your food. By eating organic and buying more local based foods, odds are that you will help with the soil problem, as well.

LB: You talk about civilizations lasting about 1,000 years before they collapse, is that because that is how long it takes to exhaust soil?

DM: Yeah. One of the things I didn’t put in the book was a lot of data but I published a paper with the Proceedings of the National Academy of Sciences where I compiled data from erosion rates from agriculture around the world. They lose a millimeter to a couple of millimeters per year. Given that the average soil thickness is a half a meter and you’re losing a millimeter per year, in 500 years, you lose half of it. It’s on an order of magnitude to the time line you see for many civilizations. Is it coincidence or historical? You get as much data as you can and try to figure out the story that makes sense. One of the reasons I compiled all that data was I didn’t want to put out a book I couldn’t back up with numbers, but I think it pencils out as a very reasonable hypothesis. One we should worry about paying attention to. The classic exception was the Nile because they were farming 5,000 – 7,000 years continuously. That’s because it’s a flood plain. But that lasted up until the point they built the Aswan Dam and it cut off the natural fertilizer they were getting from the river. Now the farmers on the Nile are some of the biggest users of artificial fertilizer on the planet, yet they live in the breadbasket of humanity. There are places where you can sustain agriculture indefinitely if you do it right. Even erosive agriculture. The soil in Ethiopia got stripped off in ancient times and ended up further down the Nile fertilizing Egypt’s fields!

LB: You talk about Rome not as much collapsing as consuming itself. That really struck me. Are we consuming ourselves?

DM: Well you know, if we put aside the questions about consumer culture and think just in terms of soil, given that we are eroding soil on an order of magnitude that's faster than it’s being created -- that is, modern agricultural soil erosion rates are as many as 10 – 100 times faster than soil creation -- a minority of farms are a net soil source, but very few, so we are consuming ourselves to death. It’s like a bank account. If you spend money 10 times faster than you make it, you go broke. Soil is no different. You produce it, you use it and then it’s lost. If erosion is faster then production, we’re running out. The question is how fast and that’s where the good news lies because the rate is so slow, a millimeter or two a year, we actually have the opportunity to turn it around but it requires farming practices that are different than what we’ve done traditionally and conventionally. If we look at the adoption of no till data, we can show like I did in the PAS paper, you can get agriculture back to the no erosion rate. You can produce food without eroding soil. When I was born in the early 60’s, no till agriculture did not exist in the US, just a few cranky farmers were doing it. Today 1/3 of crop land is farmed with no till methods. The United States is one of the world’s leaders in trying to address soil erosion. How many other environmental problems today can you point to that the United States is a world leader in addressing? And that’s where the worry about what we do in response to biofuels is a big issue because the trend in the US in terms of soil erosion has been really good in the last few decades. We’re still losing soil but nowhere near as fast as what we used to in this country and in Canada. So we face a really big policy question over the next few decades; whether we will continue trends to make soil more sustainable or if we will repeat errors of past generations by adopting methods that will undo the progress we made. That’s where the biofuels comment comes in. How we set up agricultural incentives will shape what farmers do, naturally. So in my view, it would be a horribly lost opportunity if we did not prioritize the interests of future generations in regenerating soil fertility, in maintaining soil fertility and the soil itself.

LB: You also write about companies turning toxic waste into fertilizer. That also really struck me. Why do we care so much less about our health than we do about money? It seems we are willing to trade our health for a dollar.

DM: That’s a good question. Usually, it’s because it's not the person making the dollar whose health is at risk. That seems to be the root of the problem right there. I was just shocked when I learned about that stuff.

LB: You should see Michael Clayton, it’s all about that.

DM: I have to admit, between the research for this book and my previous book “King of Fish; the Thousand Year Run of Salmon”, I’ve had no time for any other books or movies, but I’ll make a point of seeing it.

LB: You write about how in the Amazon, forest clearing is creating catastrophic soil loss, yet human behavior isn’t changing in reaction to that. What do you think it will take for people to change their behavior?

DM: Oh boy. It’s not just awareness, because like with the Amazon example, the reason people are clearing the forest is that they don’t have a choice, that’s what they need to do to survive this year. We need to provide subsistence farmers with opportunities to sustainably farm. Also, we need to be giving people the chance to change in the industrialized world, it's economic incentives on the farming end of it. In the third world we need land reform and in the first world we need agricultural incentives reform. Will those be adequate? I don’t know. I wish I knew the answer. As a geologist, I might be the wrong guy to ask. I know how hard it is to change some of my own behaviors. Like I said, I started walking to work a year and a half ago. I hadn’t done that in 10 years. Finally I realized it would be good for me and good for the planet. Then once I started doing it and I felt better, my health improved and I could feel good about being less a part of the climate change problem, then the behavior stuck. Realistically, I wish I knew the answer. It’s a problem we all should be worried about.

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  • Posted on Feb. 14, 2008. Listed in:

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