How Soil Could Save The Planet

17:26 minutes

a White man kneeling on the ground on a farm with long rows of cabbages. he's examining a tablet
Credit: Shutterstock

There’s a scene in the 2014 film Interstellar that imagines the hypothetical impact of climate change on Earth’s food system. The film takes place in a dystopian future where a global crop blight is slowly rendering the planet uninhabitable. Corn is the last viable crop and dust storms threaten humanity’s survival

But it’s not just science fiction. Scientists are warning that if we don’t adopt more sustainable farming practices we’ll deplete the soil of vital nutrients and actually accelerate climate change. 

The Earth’s soils contain about 2,500 gigatons of carbon—that’s more than three times the amount of carbon in the atmosphere and four times the amount stored in all living plants and animals. And the soil—in union with the plants that grow on and in it—may have an unlimited capacity to suck CO2 out of the air and store it underground. 

Tom Newmark, founder of The Carbon Underground, joins Ira to discuss the potential of carbon sequestration through a farming technique called “regenerative agriculture.” And Diana Wall, professor of biology at Colorado State University, discusses the role microbes play in the carbon cycle. 

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Segment Guests

Tom Newmark

Tom Newmark is co-founder & chair of The Carbon Underground.

Diana Wall

Diana Wall is a Professor of Biology and Director of the School of Global Environmental Sustainability at Colorado State University. She is based in Fort Collins, Colorado.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. Perhaps you recall a chilling scene in the movie Interstellar. The film takes place in a dystopian future, where a global crop light is slowly rendering the planet uninhabitable. Corn is the last viable crop. Dust storms like the one depicted in the film threaten humanity’s survival.

SPEAKER 1: All right. It’s a doozy. Ah, gang, let’s mask up.

IRA FLATOW: The scary part is, it’s not just science fiction. Scientists are warning that if we don’t adopt more sustainable farming practices, we’ll deplete the soil of vital nutrients, and actually accelerate climate change. But there is hope, because the soil can help save the planet.

The Earth’s soil contains about 2,500 gigatons of carbon. That’s more than three times the amount of carbon in the atmosphere, and four times the amount stored in all living plants and animals. And the soil, in union with the plants that grow on and in it, may have an unlimited capacity to suck CO2 out of the air and store it underground, carbon sequestration through a farming technique called regenerative agriculture.

That’s what we’re going to talk about. How does the Earth under our feet become the world’s largest carbon sink? And can it really help us combat climate change?

Here to dig into some soil science with us are my guests, Tom Newmark, co-founder and Chair of the Carbon Underground, Dr. Diana Wall, Professor of Biology in the School of Global Environmental Sustainability at Colorado State University. Welcome both of you to Science Friday.

DIANA WALL: Thank you.

TOM NEWMARK: Pleasure to be with you.

IRA FLATOW: Nice to have you. Tom, let me begin with you. Research published by the Rodale Institute, of which you collaborated, says that if farmers around the world adopt regenerative practices, the soil could sequester, well, 100% or more of carbon emissions of CO2 made by people. Is this soil able to store so much carbon?

TOM NEWMARK: I think the time will tell. It’s very clear, with 5 billion hectares of land that we can work with, both crop land and grassland, using regenerative agriculture at a scale of that dimension, sciences are already demonstrating that we can sequester or resequester the CO2 that right now is a legacy that afflicts us in the atmosphere, and put it back to work for us in living soil. So the science is developing, and it’s very encouraging that we will be able to meet the challenge of the climate crisis by invoking the power of regenerative agriculture.

IRA FLATOW: Well, you’ve raised that. Now we have to get into it a bit to understand it. Can you explain the process involving photosynthesis?

I understand that you’re talking about pulling CO2 from the air. You turn it into liquid carbon, so to speak, send that juice into the roots. What happens then, under the soil?

TOM NEWMARK: There’s this ballet, this incredibly complex choreography between the exudates, the sugars that the plant creates via photosynthesis, as it nourishes both the plant and the entire soil food web. All of the microbes, the protists, the archaea, the nematodes, the bacteria, the fungi, that live in the soil are hungry for that liquid sugar, for the solar energy that is packaged in that sweet form and delivered through the roots. In exchange for that liquid sugar, the soil food web, that microbial community, will deliver to the plants at their roots, biologically available nutrients such as nitrogen, and phosphorus, and potassium, and other minerals that the soil food web has the unique ability to render biologically available.

So it’s that underground commodity exchange whereby the soil food web gives to the plant those nutrients. And the plant gives to the soil food web the liquid carbon produced via photosynthesis that transfers the carbon from the atmosphere into the soil food web. And then, of course, the soil food web, the microbial community, it lives, it flourishes, it dies, it has a life cycle. And as that community of life in the soil, frankly, excretes and then expires, it creates what is called necromass. Which in combination with mineral particles in the soil, ultimately creates what is called soil organic matter.

In other words, plants, in collaboration with the underground microbial community, actually creates the soil. It’s not so much that the soil absorbs the carbon, as the carbon is actually creating new soil via the mechanisms of the lifeforms that live in it and on it.

IRA FLATOW: That is fascinating. Diana, I know that you studied the organisms that make up the soil microbiome. We know what it takes to make a healthy gut microbiome. So what goes into making a healthy soil microbiome.

DIANA WALL: It’s quite amazing that we have so many different types of animals and microbes below ground that have contributed to this. And what they need is what was just talked about. They need some carbon.

And so that is the basis of the food webs in soils. But there’s so many different types of animals and microbes in there, and they all have different jobs. They have multiple functions, I guess I would say.

They have three jobs a day that they’re doing. And these include things like making air spaces through the soil so that they can travel, and the roots can move. Or they also are doing things like gluing pieces of carbon in different forms throughout the soil. And so it’s a very intricate process of how all this life below ground transforms, say, a leaf that falls on the soil, into different types of carbon and nutrients that are used by plants. I guess I would just say that it’s a little factory going on with these many different organisms. And they’re not all the same everywhere.

IRA FLATOW: Do we know which organisms, which soil organisms, are best for storing carbon, Diana?

DIANA WALL: No. I don’t think there’s any one group. I think now scientists are thinking more of that it’s kind of a consortium, or a big network of interactions below your feet. And so when we start breaking these connections with pollution or some type of disturbance, pouring concrete over it for a parking lot, we break these connections of the biota below ground. And they’re not able to perform the services below ground or to support the biodiversity above ground.

IRA FLATOW: OK. So Tom, soils play an important role in drawing down carbon from the atmosphere, but they can also release carbon, right? I mean the IPCC report estimates that something like 25% to 30% of global emissions comes from agricultural industry. What are farmers doing incorrectly that releases all this CO2?

TOM NEWMARK: Frankly, there’s been a long and regrettable commission of agricultural malpractice. If you think of the soil as living tissue, and as Dr. Wall so beautifully explained just now, it’s this collaborative community of microorganisms that create the tissue of the soil. To pass a steel blade, a plow, through that living tissue is a violent disruption of the integrity of the soil. In addition, pumping synthetic nitrogen, different pesticides, into that living tissue, it disrupts and distorts the healthy activity of that community of life.

So frankly, everything that we have been celebrating and glorifying in the industrial agricultural system that we now have, is in some ways responsible for the destruction of that living community. And not only is the IPCC, of course, correct in looking at modern agriculture as a source of CO2 contamination, but historically, somewhere between 20% to 40% of all of the legacy CO2 in the atmosphere has somehow been transferred from damaged soil back into the atmosphere. So that is the challenge. But now, using regenerative agriculture, we can reverse that and put that toxic CO2 back to work for us as a tonic by reinvigorating, by reviving, the living soil tissue.

IRA FLATOW: And how can they do this? I was fascinated by reading the report where you talk about when farmers adopt regenerative farming, even degraded soils, even sandy soils in the desert can be turned very quickly to fertile fields by planting something called green manure. And green manure is not some kind of fertilizer from animals, right?

TOM NEWMARK: No, it is not. A green manure and green manure cover crops are living plants that in some way are nourishing or revitalizing the soil. And there are many cases, in fact, there are millions of cases of farmers around the world, even in the most degraded, sandy, desert-like soils using regenerative agriculture and being able to recreate, every year, 2 centimeters or more of new topsoil.

So this is the misunderstanding. There’s this common idea that it takes a century to recreate 1 centimeter of soil. And that’s the case where there’s no concerted activity of the soil food web at work. But where you’re using plants effectively and regeneratively, we can add an inch of topsoil every two years, even in the most degraded desert-like environments. And that’s just not my observation, that’s the observation of agronomists, food scientists, smallholder farmers, by the tens of millions around the world.

IRA FLATOW: Diana, you agree?

DIANA WALL: It seems to me that there’s been a paradigm shift. That we now realize, and of course, the people working the soil, the growers, the farmers who know this, that we need to put back into soil if we’re going to have a sustainable soil for the future. And we also have a lot of studies that are showing that it’s not just putting back the carbon and expecting that the living organisms below ground are going to immediately respond, and we have the community we had before it was degraded. That does take time to build some of the connections up.

I think of it as, like if you have a circle and you put as many dots as you can inside that circle with your pencil, and then they’re all connected. That’s the way the soil was before it was degraded. And as we degrade it, those connections are broken. So then we come and we try to regenerate the soil, to put more carbon back into it, to do it in a more natural way. What we see is these connections over time start to rebuild among the different biota that are there.

IRA FLATOW: This is Science Friday from WNYC Studios, talking with Tom Newmark and Dr. Diana wall about soil and soil health. Now both of you say that the farmers are smart enough, and the farmers I met are really very smart about what they know about what’s going on in the soil. But there’s also the economic side. Is there not, Tom? How do we get farmers to change their habits, and yet give them the yields and the profits that they want to make?

TOM NEWMARK: Well Ira, if there’s no soil, there will be no yields, and there will be no profitability. So we have to look at this realistically. We’re losing about 24 billion tons of topsoil every year because of agricultural malfeasance. The FAO estimates that at present rates of soil degradation, there’ll be no soil left to grow anything in perhaps only 60 years.

So if you’re looking at this economically, there frankly is no choice but to proceed regeneratively. Because without soil, there will be no agricultural opportunity whatsoever. So when I look at this, and when others in the regenerative community look at this, we see regenerative agriculture as the great economic engine that promises to deliver a future for farmers and for food consumers.

But it’s more than that. Whether you’re in the business of growing corn– if you’re a smallholder farmer, and there are, frankly, billions of smallholder farmers around the world– what we know is that using green manure cover crops and other regenerative practices, your crops will increase. Your yields will increase. Your input costs will go down. You will be more profitable.

It takes a few years for the living systems to revive, for the biology to revive. But once the biology is reestablished in the soil, then this is a recipe for greater yields and profitability for farmers.

IRA FLATOW: Dr. Wall, are you optimistic about the future?

DIANA WALL: I am optimistic, and I’ll give you a couple of reasons why. One, I think there’s a greater awareness, not only at the level of growers, but at the scientific level and higher at the UN level. I think that we’re seeing desertifications, so we’ve got the policies, or the UN Commission to Combat Desertification. You’ve got Convention on Biological Diversity that is concerned about what are we losing in our soils, and will the soils continue to give us the benefits, the human benefits, things like nutrient cycling, and regulation of climate, and cleaning water as it goes through the soils.

So there’s a number of different types of environmental agencies that are now looking from the top down about how do we manage our soils better, not just in agriculture, but all soils, whether they’re in forest, whether they’re the deserts we’ve already mentioned, or the tundra, or in both polar regions. I think this is coming from a lot of different fronts, and all of a sudden soils and their biodiversity are at the center of it.

IRA FLATOW: Well, we’ve run out of time. So much to talk about as usual, and so important a topic. I’d like to thank my guests, Tom Newmark, co-founder and chair of the Carbon Underground, a nonprofit that educates governments, business leaders, and the public on the impact of regenerative agriculture on climate change. Dr. Diana Wall, professor of biology at the School of Global Environmental Sustainability, Colorado State University. Thank you for taking time to be with us today.

TOM NEWMARK: Really a pleasure. Thank you.

DIANA WALL: Thank you.

IRA FLATOW: One last thing before we go. We lost an anchor and a pioneer in our science journalism community last Saturday. Sharon Begley’s long career covered four decades of science writing.

She was one of the few journalists whose byline carried as much weight as her story. If Sharon was writing it, you took notice. Her views were always thoughtful, like the time she discussed on this program how writing a book changed her life.

SHARON BEGLEY: It has made me even more convinced that hard wiring is just empirically incorrect. And this has shown me yet other studies, more research, a whole field of science that disproves this idea that you don’t have any power over who you are or what you become. Which I find, yes, personally appealing. I mean it’s more– I mean, Lord knows it’s more optimistic than the idea that the brain you enter the ripe old age of three with is the brain you’re going to be stuck with forever.

IRA FLATOW: Sharon Begley passed away at the age of 64. Condolences to all friends and family.

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