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The Leading Voices in Food

E179: Investing in Soil Regeneration for Human Health & Environmental Health

Hosted by: Kelly Brownell
August 31, 2022

Today, we’re speaking with geologist David Montgomery, co-author with Anne Bikle, of a new book called “What Your Food Ate.” Very interesting title. David is professor in the College of the Environment at the University of Washington and earlier had been awarded a MacArthur fellowship. You may already be familiar with him through his acclaimed book called “Dirt: The Erosion of Civilizations.” Dr. Montgomery has long argued that the root of good health begins with dirt, a factor that we ignore at our peril.

David R. Montgomery is a Professor of Earth and Space Sciences at the University of Washington. He studies the evolution of topography and the influence of geomorphological processes on ecological systems and human societies. He received his B.S. in geology at Stanford University (1984) and his Ph.D. in geomorphology from UC Berkeley (1991). Current research includes field projects in the Philippines, eastern Tibet, and the Pacific Northwest of North America. In 2008 Montgomery received a MacArthur Fellowship. His books, Dirt: The Erosion of Civilizations, King of Fish, and The Rocks Don’t Lie have all won the Washington State Book Award in General Nonfiction. Montgomery’s Growing a Revolution: Bringing Our Soil Back to Life, was a finalist for the PEN/E.O. Wilson award for Literary Science Writing. His latest work with W. W. Norton, What Your Food Ate: How to Heal Our Land and Reclaim our Health, published in 2022.

Interview Summary

Well, I really admire your work, and this work in this area is so important. We’ve recorded a number of episodes around the issue of regenerative agriculture, and it’s been impressive how much interest there is in this topic, which I think, only a few years ago, wasn’t very well known to most people but now is becoming more part of the general discussion, which I see as a very positive development. Let’s begin with your interest in dirt. So what is the condition of the Earth’s dirt?

Well, sad to say, not very good in terms of our agricultural soils in particular. That’s something as a geologist, that’s what got me interested in soils is looking at the long history of human interaction with our landscapes and soils and ended up writing a history of farming about how it had degraded farmland around the world over the course of centuries. The short answer is that we have degraded something between about ¼ to 1/3, probably, of the world’s potentially viable agricultural land to the point where it’s not terribly useful for agriculture. The UN’s 2015 Global State of the Soil report concluded we are losing about a third of a percent a year of our ability to grow food on this planet due to ongoing soil loss and degradation. So the physical erosion of the soil and the degradation of its fertility as manifests through the loss of soil organic matter. And, that 0.3% a year number doesn’t sound like a big deal on a year to year basis. But think about that over the rest of this century, and it adds up to almost another 1/3 of the world’s farmland taken out of production at a time when we really need all hands on deck or all acres on deck, as it may be, to feed the world as our population keeps growing. So, we face a fundamental challenge this century of how to sustain agriculture on a degrading resource base. Our other choice is to think about trying to improve, enhance and restore the soil. That is where regenerative agriculture comes in and where my interest has really grown beyond just looking at the sad experience of past civilizations that degraded their land. And to thinking about possible solutions that will allow humanity to continue intensive agriculture to feed the world well into the future.

So what are some of the factors that have driven the erosion and the degradation?

One of the biggest factors that contributed to the loss of topsoil in societies around the world was tillage, the act of plowing. That seems a little odd to hear at first because isn’t that something that farmers do? It helps to provide weed control. It helps to prepare a seed bed for planting, but it also leaves the ground bear and vulnerable to erosion by water and wind until the next plants come in, whether it’s a crop or whether it’s weeds. If you leave the ground bare and vulnerable, you get the erosional situation like we saw in the Dust Bowl where great clouds of dust blew off the American Midwest when we plowed up the plains when the next drought came in. The same kind of thing happened in slower motion in societies in the past, mostly in response to rain rather than wind, but erosion that proceeded faster than the rebuilding of the soil gradually stripped off the top soil from regions around the world that people depended on to grow their food. And in the modern world, we can actually degrade soil faster with the combination of tillage, the over application of synthetic nitrogen fertilizers, which also contribute to decline in soil organic matter, and the concentration on monocultures can also reduce the release of exudates that plants produce and drip into the soils to feed microbes around their roots. That combination is all resulted in degradation of soil organic matter and the loss of topsoil, soil erosion in many parts of the world. So the very foundation, if you will, of modern conventional agriculture, intensive tillage, lots of agrichemical use, and monocultures has helped to undermine the native fertility of the farmland that future generations globally are going to depend on for their food. So one of the questions I’ve been wrestling with and how I got into looking at regenerative agriculture was how could that process be turned around? How could we actually sustain intensive farming and not degrade the land? Is it possible to actually engage in intensive farming that could improve the health of the world’s soils? That started to turn me into an optimist when I ran into farmers, interviewed farmers, and studied their farms where they had indeed done that.

It is impressive to hear those stories. We’ve had a number of such farmers doing podcasts, and it’s very inspiring to talk to them. So let’s just take one piece of what you said, the use of tillage. You hear the term no-till farming. What does that mean? What does that look like?

Yeah, so that would be farming without plowing, and so the challenge is how do you get the seeds into the ground? How do you prepare a field for planting if you still have the remains of last year’s crop on it, the so-called crop residue? Over the last century, people have invented new and different farm implements and machines, and there are no-till planters that can actually put seeds down into the soil in narrow little trenches that get good contact between the seed and the seed bed but don’t require essentially inverting the soil. They don’t rip it all up. They just disturb a little narrow slot to actually get seeds in the ground. What that also allows is keeping the residue from a prior crop as essentially a mulch. If you knock it down, if you kill any weeds that were there physically and knock them down, crimp their stems, you can convert them into mulch that can help keep moisture in the soil, but it also protects the soil from erosion. No-till farming is a way of farming that minimizes the physical disturbance of the soil, and you need different equipment to do it and a different mindset to do it, but it’s very feasible to do, and there’s lots of different ways to do it. Some farmers use a lot of herbicides to control their weeds in no till. That is the conventional way to do it, but there’s others who are pioneering different techniques that don’t require the use of a lot of herbicides to do no till. The basic idea of no till is to minimize the disturbance of the soil, and why is that important? Because it enhances the beneficial aspects of soil biology. It allows the natural soil ecology that really evolved in the last 450 million years since plants colonized the continents to work. Soil microbes have these partnerships that evolved between plants and life and the soil that are mutually beneficial. And if you disturb the soil physically, you disturb a lot of the fungal partners that crops are trying to invest in with some of their early growth.

I know the regenerative agriculture approach wasn’t called this going back hundreds of years but been used by populations around the world, including Native Americans, but if we fast forward today, do you think that this holds promise for being done on a broad enough scale to really make a social difference?

Yes, I really do. What is different today is that in the past, these practices of crop rotations and of planting legumes in and amongst crops to get nitrogen into the soil, those are not new ideas. They have been traditional ideas in many societies around the world because they worked to help sustain the fertility of the soil. But, what I think we really have the opportunity to do now is to combine some of that ancient wisdom with the modern technology that allows us to do no till at scale. And, to minimize our use of not only physical disturbance from adopting no till but also to minimize the chemical disturbance that comes with the overuse of synthetic nitrogen fertilizers and pesticides. Combining the modern technology with ancient wisdom can allow us to basically expand the realm of regenerative practices to very large-scale farming because unless we all want to become farmers, we’re not going to be able to do small-scale regenerative farming and feed the world. Even though most of the world’s population is fed by small-scale farmers, those of us in the westernized world relying on very few people to feed very many of us. I’ve been on regenerative farms that are up to 20,000 acres in the US; big, large mechanized farms that have done an amazing job at rebuilding the fertility of their land. I’ve also been on very small-scale subsistence farms in equatorial West Africa that are regenerative that have done an amazing job at rebuilding the fertility of their land. Those three general principles of minimizing disturbance, growing cover crop, always keeping living roots in the ground to provide exudates to feed the microbes, and to grow a diversity of plants. That recipe is a combination of principles that different kinds of practices would need to be used on large farms or small farms or high tech farms and manual labor subsistence farms, but the general underlying philosophy of cultivating the beneficial life in the soil underpins all those. And that’s how I tend to look at what I would call regenerative agriculture, are farming practices that are tailored to the size of the farm, the environment, the climate, the crops that farmers want to grow, the technology they have access to, but that prioritizes building the health of the soil as the foundation for the farm.

It’s nice to hear such a positive outlook on this. You are painting the picture saying that it can be done. Do you think it can be done in a way that can compete cost wise with traditional approaches to farming?

Absolutely, and that was a big focus of what I wrote about in “Growing a Revolution.” If you could tell a farmer that you could cut their fertilizer costs, cut their diesel costs, cut their pesticide costs as much as in half, they all start looking at you like going, “Yeah, tell me more. How would you do that?” That’s one of the key attractions, I think, of regenerative agriculture. Once the soil is restored to a healthier state, you don’t need as much fertilizer. You don’t need as many pesticides, and you don’t drive tractors around as much if you’re doing no till. What are three of the biggest costs on modern farms in north America? Well, fertilizer, diesel, and pesticide. And so if you can teach farmers a different way of farming that starts with a different way of looking at the soil and adopting a different series of practices that allows them to harvest as much while spending less to do it, it’s a recipe for a more profitable farm. And for what I’ve seen in the experience of the pioneering regenerative farmers that I’ve interviewed, once they’ve restored fertility to their land, their yields are comparable to, if not better than, their conventional neighbors, and their expenses are less. That’s what started turning me into an optimist on this is I’ve seen a lot of growing interest in farming communities simply because farmers are pushed to the wall and looking for ways to cut costs.

That’s so exciting to hear that, and then, of course, at some point government could subsidize these sort of approaches to make it even more cost effective because of the environmental benefits.

There are all kinds of add-ons in terms of benefits, less offsite nitrogen pollution, greater on-farm biodiversity, enhancements to rural economies, and also differences in what gets into the food that we grow that could potentially benefit human health.

I have a million questions to ask you. We’ve talked about the vitality and health of the soil. Let’s talk about the vitality and health of what’s being grown in the soil, that is the nutrient quality of the foods. In the book, you note that produces significantly less nutrient dense than in the past. How much is this true, and how less dense is it?

Yes. That’s a great question. So one of the things we really delved into in “What Your Food Ate” because it is a central question to thinking about, well, does soil health mattered to human health? And the conclusion we came away with in diving into the peer reviewed literature and doing some of food testing of our own, was that there’s three key areas where the nutrient density, shall we say, of food has suffered over the last half century. And that’s in terms of mineral micronutrients, phytochemicals, and the fat profiles of our meat and dairy. So how does that work? Well, in terms of mineral micronutrients, a lot of plants partner with fungal communities in the soil to actually trade sugars and fats and proteins. Plants will drip those out of their roots to feed microbes in the soil in exchange for those microbes, particularly fungi, giving back things like zinc or copper or iron mined from the soil. It’s literally an underground economy but where both partners benefit from the exchanges, and conventional agricultural practices disturb those relationships. We’re not talking so much about the major nutrient composition of foods as much as the micronutrients. Plants have different gene pathways where if they’re grown in very nitrogen-rich environments, they shut down their exudate production. So they stop feeding their microbial partners. Their microbial partners aren’t on the job to give them the mineral micronutrients that they need and that turn out to be very important for our health, too, when we eat them. Plants also make what are known as phytochemicals in response greatly to environmental stimuli, some of which are microbes in the soil. And so the communities of life around their roots are actually key partners in terms of making things that we don’t often consider nutrients in the nutritional sciences, but they’re important for maintaining human health, things like antioxidants, anti-inflammatories. Those are examples of the functions phytochemicals can serve in our bodies, and our farming practices have disrupted them. How much they have disrupted them? There are studies that show differences on the orders of 50 to 100%, others that are more like 20%. Most of the studies and the testing that we did as well make it look like it’s more like around 20%-ish. It’s modest but very real differences in these compounds that the medical sciences have shown are fairly beneficial to promoting human health in our diets.

So can I assume from what you’re saying that there’s research now showing that if you use better soil practices a la regenerative agriculture, that the nutrient quality improves?

Yes, it’s a nontrivial difference. And the other difference, even bigger, is looking at the ratio of the composition of fats in meat and dairy in terms of the omega-6 and omega-3 fats. To make a very simple generalization, omega-6 fats in our bodies are instrumental in initiating inflammation whereas omega-3 fats are instrumental in quelling or reducing inflammation. It turns out that what we get in terms of the fat composition in our meat and dairy products very much depends on what the cows ate that produce that meat and dairy. Cows that grazed leafy green plants, actually grazing out in a pasture, they eat a lot of omega-3s because that’s what’s in the leaves of plants because omega-3s are central to photosynthesis. Omega-6s are a very rich in seed sources. They serve different purposes in seeds. Cattle that are on a feed lot diet of seed-derived feeds are rich in omega-6s, and our diet has gone from having just a few more omega-6s than omega-3s in our diet 100 years ago. Now we’re awash in omega-6s from that change in our meat and dairy and also the addition of seed oils to processed foods. That trade we write about in the book that translates through, we think, to essentially how so many of us are dealing with chronic maladies that are rooted in chronic inflammation.

Another way to really move this along might be for consumers to begin requesting products that are grown in such a way, and so I’m wondering about your opinion on whether a poll from consumers might help here. Do you think there could come a time when that would be the case?

I absolutely do, in fact. I just noticed in Anne and my own buying habits. So we started doing this research and learning what it was we did along the way, our buying habits have changed. So we’re buying 100% grass fed meat and dairy when we can. We’ve tried to connect with farmers whose practices we really like in terms of the produce we can buy at farmer’s markets here in Seattle where we live. Now the average consumer faces a challenge today in terms of what’s labeled as what in a grocery store, but it’s our hope that people will start thinking more about these connections, start asking questions, ask the produce manager at your store, “What are the farms doing that you’re getting the produce from?” I could definitely see a world in the not too distant future where consumers may be armed with the ability to know what the analyses of different batches of produce coming in.

And I wonder if the first movement here might not be from institutions, that a school system or a hospital or the procurement part of a city or county government, if they made purchasing decisions based on nutrient quality and, of course, the practices used to grow the food could make a big difference.

I think that is a tremendous idea that I think could be very impactful, and I think you’re right, that that could be where you might see some of the biggest pieces of movement. There is also been some corporations that have been interested in trying to move towards adopting and advertising that they have adopted regenerative sourcing in some of their ingredients. I really see three areas that need attention in terms of advancing regenerative agriculture. Consumer demand is one, as we have been discussing. The inherent farmers’ incentives in terms of economics that we discussed earlier is another. The third is in terms of rethinking our agricultural subsidies and policies to actually reward farmers who are rebuilding the health and fertility of their land. Those who are reinvesting in the future of America, quite literally, instead of continuing to subsidize conventional practices that frankly degrade the fertility of the land and the ability of future generations to feed themselves. If we could get all three of those areas lined up working towards the same goal of making what we call regenerative agriculture today the conventional agriculture of tomorrow, that could literally change the world in the coming decades. It’s not going to happen fast, but I think it’s something that could be done over the course of two or three decades at a time when we really need the change.

Well, especially if the right research got done at the right time. For example, I could imagine going back to school systems. Let’s say that a school system changes its buying practices and ends up buying more nutrient-dense foods and then proves that there are beneficial outcomes for the kids, like better performance in school and more attention and things like that. Then you could see a lot of adopters coming pretty quickly.

Yes, I would love to see a lot more research along those lines done. We tried to connect the dots in “What Your Food Ate” from soil health to crop health to animal health to human health, but there’s a lot of space between those dots and a lot of work that needs to be done, but it’s a very promising area and a new way to think about those connections.

Could we talk about livestock for another minute? You mentioned this earlier, and it sounds like there’s a lot of promise using these techniques for livestock production. Most people think of plant production here, but livestock are really important as context as well. Are there places where livestock and plant-based agriculture are interacting with each other in this context?

Yes, some of the farmers I visited were reintegrating animal husbandry into their cropping operations and having their cattle graze off their cover crops and then manure their fields. I came from a position where I had long thought of cattle in particular as harmful to the land through gully formation and erosion from overgrazing. The farmers that I visited who have used cattle to rebuild the fertility of their soils were really grazing in a very different manner, in a different style that enhanced the fertility of their land as a result of reintegrating them. I think one of the big inadvertent mistakes of 20th century agriculture was essentially separating animal husbandry from cropping and encouraging farmers to specialize in one or the other. Now we have the perverse situation where we grow a whole lot of corn using practices that degrade the fertility of the land to feed cattle and feed lots who then are full of omega-6s that degrade our health when we eat them. It makes no sense in terms of large-scale agricultural policy unless you are thinking with the mid-20th century mindset of maximizing efficiency and industrializing and separating those corners of agriculture. What we inadvertently did is we broke some of the biological and ecological connections that helped keep the land fertile and that were result of the integration of animal husbandry and cropping practices. That’s another example, I think, of the value of potentially reintegrating some elements of ancient wisdom with modern science to think about doing things a little differently.

Let me end with this question, and I want to see if I’m reading you right. It sounds like if you look at the world’s situation with dirt agriculture, it is a pretty dire picture, getting worse quickly, and it could go really badly if nothing is done, but it also sounds like you’re very optimistic. There is a lot we know about what can be done, a lot of it is being done, and the signs for the future are positive. Am I reading that right?

I am optimistic about this. I struggle with how much of that optimism is a choice rather than a logical extension of what I know. But I think we know enough now about techniques that can rebuild fertility of the land and restore it that it’s feasible to see a path forward where we could do that at scale with very positive results that could also put a lot of carbon back in the world’s agricultural soils, which would have ancillary climate benefits. It’s not going to solve the climate problem. That’s a fossil fuel issue primarily, but it could help. Back when I wrote “Dirt” in 2007, I think it was, there was hardly anybody talking about soil health and the long-term importance of reinvesting in the world’s agricultural soils to rebuild their fertility, and now almost every farming conference I go to or get invited to speak at, that’s one of the big topics of discussion among farmers. And there’s now discussion at policy level in terms of the new Farm Bill that climate activists are interested in. There’s a lot of very broad, I think, public support and interest coalescing around the idea that one of the smartest things we could do for the future of our own species and for the health of the planet is to reinvest in the health and the fertility of our agricultural soils.


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