This is a transcript of the Gastropod episode, To Fight Climate Change, Bank on Soil, first released on February 25. It is provided as a courtesy and may contain errors.
CHANT NEWSREEL: Stop denying the earth is dying! Stop denying the earth is dying!
ACTIVIST 1 NEWSREEL: We stand united. Youth across the world and across the country are coming together.
ACTIVIST 2 NEWSREEL: The climate crisis should not have to be put on my generation’s shoulders to fight.
BBC NEWSREEL: “Some of the official predictions made about climate change sounded Biblical in scale. More drought, more famine, more flooding, more of the most powerful tropical cyclones, and, of course, the seas rising.
CNN NEWSREEL: If we don’t figure out how to do something about this and pretty quickly, we’re going to hit a catastrophic tipping point.”
GRETA THUNBERG NEWSREEL: I wanted to act as if the house was on fire. Because it is.
CYNTHIA GRABER: As you just heard, young people all over the world have been protesting lately because they’re worried they’ll be left with a planet that’s not liveable because of climate change.
NICOLA TWILLEY: And they’re 100% correct to be worried. I am too. But you’re listening to Gastropod, the podcast that looks at food through the lens of science and history. And the podcast that is not a gigantic downer. So this episode, we’ve got a story about a pretty exciting climate change solution: soil.
GRABER: That’s right, this episode, we’re going to be talking about why soil is cool. Kind of literally. I’m Cynthia Graber—
TWILLEY: And I’m Nicola Twilley. And this is a story that starts at a rather boring and technical sounding press conference in Paris, just a few years ago, in 2015.
STEPHANE LE FOLL: French press conference audio
GRABER: This is Stephane le Foll, he’s the former minister of agriculture in France.
STEPHANE LE FOLL: French press conference audio
GRABER: He’s talking about the start of a new initiative to help save the planet. It’s called 4 per mil, or four per thousand. And the goal is to put 0.4 percent more carbon in the soil every year.
TWILLEY: What he goes on to say in this whole long speech is actually pretty exciting. His point is, there’s two to three times more carbon in the world’s soil than in its atmosphere. And the soil has room for more. So if we could stuff just a tiny bit more carbon in the soil, the implications are completely ginormous.
BERHE: And imagine the reduction in CO2 concentration in the atmosphere that comes with that and the resultant implications for addressing global warming and all issues related with climate change. Huge implications.
GRABER: This episode of Gastropod, can soil save us? There’s a lot here, so let’s get going and get our feet dirty.
TWILLEY: Dear God Cynthia you are really rolling with the dad jokes this episode. That’s normally my job. But seriously—you hear about Meatless Mondays and going vegan, you hear about eating local—but does the solution to climate change actually lie in the soil beneath our feet?
BERHE: I got into soil as an undergraduate student at the University of Asmara.
TWILLEY: This is Asmeret Berhe. She is a professor of Soil biogeochemistry at the University of California in Merced, where we went to visit her. But her lifelong love affair with soil began in Eritrea.
BERHE: So when I started I was an 18 year old student at the university. I didn’t know really anything about soil. And I took an introduction to soil science course and I was blown away at how that opened my world and my eyes. I was hooked. I’m still learning about soil.
GRABER: Asmeret fell in love with something that just seems like this everyday brown thing we might occasionally get stuck to our shoes. But really, what is it? What is soil?
BERHE: It’s a product of breakdown of rocks and also it incorporates residues of dead plants and animals that used to live in the land before. But the mixture of this breakdown products of rocks and residues of organic matter that lived creates this incredibly rich resource that we then, every living thing on the face of the earth depends on for our life, for our livelihood, for our food fiber needs and everything else you can imagine.
TWILLEY: There’s only about six foot of this magical rock and residue mix covering the earth’s surface, on average.
BERHE: And so it’s not very deep when you think about it. In reality it’s that thin veil that represents the difference between life and lifelessness in the Earth’s system.
GRABER: All this is beautiful and obviously incredibly fundamental to life on earth. And there’s plenty we could and probably will say in the future about soil and food. But this episode, we’re focusing specifically on the carbon in soil.
BERHE: And carbon is continuously being exchanged between the soil and the atmosphere because when plants photosynthesize they take up carbon dioxide from the atmosphere and then they use it to build their bodies and upon death the bodies and the bodies of every living things that consume the plants enters the soil and gets stored there as soil carbon.
TWILLEY: Basically, carbon gets into the soil through two main paths—there’s the plant matter itself, when it dies. But also, while the plant is alive, its roots push out carbon-based sugars into the soil to feed microbes.
GRABER: Those microbes are also of course made of carbon, so that’s more carbon in the soil. But, like Asmeret said, this is a cycle. Plants take up soil carbon and use it for food. And some of the carbon escapes back into the atmosphere. Some carbon just cycles through soil really quickly, it doesn’t stay in the soil.
TWILLEY: But some of it does. There are particular microbes that can help soil carbon get stuck together into clumps, so it can’t be consumed or escape to the atmosphere. And there are particular soil minerals that react with soil carbon, and form chemical bonds that also keep it from being consumed and released.
GRABER: Scientists call these clumps aggregates. Basically they’re like little vaults—some carbon might leak out of those vaults, but most of it stays there for decades, some of it stays for centuries.
BERHE: So in a way you can think about the soil serving as a bank for carbon. Right. Carbon comes in. Carbon comes out. Just like we deposit money in our bank and then withdraw over time. But if you deposit more than you withdraw then your bank account grows. And the soil carbon over time basically grew because the Earth system as a whole we were depositing more into the soil carbon bank than we were withdrawing. But right now we’re doing the opposite.
TWILLEY: In the past, our soil carbon bank account was in good shape. We’re talking geological time here, but over billions of years, more carbon got deposited than was released. That’s what made places like the Midwestern prairies—the world’s great agricultural soils—so fertile.
GRABER: But here’s the thing—in the past two hundred years, we’ve released a lot of carbon from soil.
TWILLEY: Scientists disagree about the exact amount. But everyone agrees it’s a lot. Billions and billions of tons.
GRABER: So how exactly did we lose all that carbon from our soil bank account? What have we been doing?
1950S AUDIO: Since the war, the farmer has nearly doubled his production, until today, he is feeding himself and 17 others. What made this greater increase possible? Power. Power made available through the farm tractor which meant greater efficiency.
GRABER: Yep, modern agriculture and especially tractors. Any time you break up soil and expose it, those clumps we talked about release their carbon.
TWILLEY: In the past, farming was more small scale and not mechanized. So it caused less disturbance in the soil, and so it released less carbon.
GRABER: But that’s not how things work today. Tractors rolling over fields and breaking them up so they can be easily planted, that releases a lot of carbon quickly over a much larger area.
TWILLEY: Plus all these machines mean we can farm a lot more land, more quickly—which means we release its carbon too. The amount of land used for farming around the world has grown exponentially, especially since World War II.
GRABER: Of course there are other things that expose and break up soil—deforestation, draining wetlands—but agriculture is huge.
TIM CREWS: A profound drop in soil organic matter has happened virtually everywhere we’ve farmed. No one contests this. Somewhere between 30 and 70 percent of the soil organic matter is gone from agricultural fields after several decades once you start farming.
GRABER: Tim Crews is the director of research at the Land Institute in Salina, Kansas. And he says soil that has lost that much carbon is considered degraded.
BERHE: So there was a recent report released by the U.N. that stated that close to about half of the world’s soils are now considered degraded.
TWILLEY: Which is obviously not good. So why don’t we stop with all the tractors and the ploughing?
GRABER: To understand why we need tractors in our current system, why we tear up the soil for all our crops, the critical thing to understand is that nearly all of our crops are annual plants—annuals have to be planted each year, and at the end of the season they die.
TWILLEY: Most plants in the world are not annual plants—they’re what’s called perennials. They just grow. And then one day, after a decade or hundreds of years, in the case of trees, they die.
CREWS: It’s interesting to note that there’s almost no natural ecosystems that are dominated by annual plants in the world. It just does not exist. Prairies, forests, savannas, deserts, tundra, and rainforests—all of these ecosystems are overwhelmingly dominated by perennial species. And it’s the roots of those species that developed the soils of the world.
GRABER: So most plants are perennials, there are of course some annuals in nature as well. But if most plants are perennials, why are nearly all the plants we use for food annuals?
TWILLEY: To answer that, we have to go back thousands of years, to before the start of agriculture.
LEE DEHAAN: So when you start looking for grains to eat, annual wild plants tend to have relatively large seed and relatively large amounts of them. Perennials, wild perennials tend to have lower seed yield. So if you’re looking for something to eat, usually you’re gonna be attracted to that wild annual plant.
GRABER: Lee DeHaan is a plant breeder who works with Tim at the Land Institute.
TWILLEY: And he says that our ancestors would have found these large-seeded annual grasses springing up in disturbed areas—maybe like an animal wallow. Because that’s the ecosystem that annuals are adapted to—they thrive on freshly churned up land.
GRABER: But annuals turned out to have an even bigger benefit for our ancestors than just their grain size. Now, of course, thousands of years ago, they didn’t know anything about genetics or breeding, but they would have planted seeds of those annuals, and then each year they chose their favorites to eat and replant. Annuals were perfect for this process.
DEHAAN: You can get rapid cycles of selection happening unintentionally, because every year it’s going to have to come from a seed. If you had perennials growing out there, it would be very hard to just accidentally improve them, improve their seed size because you just keep going back to the same old plants and harvesting them and they would never change.
TWILLEY: So there was some sense to choosing annuals for our food crops. But that choice locked us into tearing up the soil each year, to make the kind of environment our food plants prefer.
DEHAAN: So with agriculture, what we have to do is mimic disturbance. So when I give a presentation, I’d like to show a picture of a volcano, because that’s kind of what we do every year in agriculture is we, we level everything. We wipe out all aboveground plant life and reseed our annual grain crop. So you’re starting from kind of biological, ecological ground zero every year.
GRABER: We do eat some perennials—mostly fruits and nuts that grow on trees. There are some wild grains like wild rice, that’s a perennial. But 80 percent of all our crops are annuals.
TIM CREWS: And we locked into that way of growing food at the beginning. And we’ve lived this legacy.
TWILLEY: When farmers plough their fields before sowing their seeds each spring, that triggers a big withdrawal from the soil carbon bank—because it busts open those aggregates that were guarding carbon safely in the soil.
CREWS: And when you break it open with—with tillage, a plow, a disc, microbes have access to that stored carbon. And they have a heyday. They just start to chow down and they eat up that soil organic matter and they breathe out carbon dioxide in the process.
GRABER: Yes, drink.
TWILLEY: And honestly, a drink might not be a bad idea at this point, because the impact of tilling the soil like this is pretty bad. First of all, like we said, disturbing the soil releases a bunch of carbon into the atmosphere. And then of course that carbon isn’t available in the soil for the plants to use as food.
GRABER: Soil carbon is also critical for water storage, because those clumps help soil hold onto water. When the clumps break up, the structure of the soil changes, it doesn’t hold water as well. Water runs off the fields instead of sinking in, and the soil runs off, too—erosion becomes a bigger problem.
BERHE: So carbon storage in soil is good for many many reasons beyond climate change mitigation.
TWILLEY: But, also, soil carbon is really important in terms of climate change mitigation.
BERHE: Because there’s so much carbon in soil compared to the atmosphere a small change in the amount of carbon stores in soil can dramatically change the concentration of greenhouse gases in the Earth’s atmosphere and hence the atmospheric temperature.
TWILLEY: And because so much of the Earth is farmland—a third of the entire planet’s ice-free surfaces is farmland—that means that changing the amount of carbon in agricultural soils would have an outsized impact.
GRABER: Carbon in soil is great for plants and great for the environment, and so people have been working on ways to get more carbon into soil for a while. But this focus on climate change is a new one. Because it’s becoming clearer and clearer each year that we have to do something, anything, about our carbon emissions.
TWILLEY: So what do we do? How do we build soil carbon back up?
CREWS: I mean, the only way to get it back totally is to reverse the process totally and go back to how that organic matter was accumulated in the first place, which involved perennial species and not disturbing the soil.
GRABER: Okay, that makes sense. But nearly all our crops are annuals that we churn up the earth to plant each year. Could we grow that same food without all the tractors and all the tilling?
ALEX CARPENTER: This is our little oasis in the woods. We grow on about eight-tenths of an acre. And this is our second season and it’s all no-till. So we never turn over our soil. And we’re really focused on soil health and keeping the soil biology happy and healthy. Because that’s what grows our food.
TWILLEY: Alex Carpenter and Yoko Takemura were showing us around their tiny farm in Connecticut. It’s called Assawaga.
GRABER: I met Alex originally because he sells their delicious veggies at my local farmers market, and I started chatting with him and learned that he and Yoko are unusual. Not many farms are fully no-till.
YOKO TAKEMURA: I think no-till captures it pretty well. We really try not to disturb the soil at all. So, you know, we try to move the soil very, very little.
TWILLEY: Literally pulling up a carrot to harvest it is as destructive as they get. And the other thing Yoko and Alex do is they try to keep the ground covered, so the soil doesn’t erode and carbon doesn’t escape that way.
TAKEMURA: You don’t really ever want it to be bare soil. So even between plantings, you want that to be as short as possible. So that’s one thing. And then another is to have a diversity of vegetables. So my plan for next year, I’m trying to have in each bed at least two different vegetables. So instead of having a bed of carrots, you can intercrop carrots and scallions or something like that.
GRABER: This multi-vegetable farming plan, Yoko called it intercropping. And it’s great for a number of reasons. First, the diversity of plants helps keep away weeds and pests because there aren’t any huge beds of just one type of plant. Alex and Yoko don’t want to spend all their time weeding and disturbing the soil, and they also don’t want to be applying pesticides and herbicides. Intercropping helps with all that.
TWILLEY: Also, having a diversity of crops means you harvest them at different times. So intercropping means that even if you’re pulling up one crop, the other is still there to help keep the ground covered.
GRABER: Plus the roots of one crop stay in the ground even when you pull up the other crop, and so they keep pushing carbon into the soil and feeding the microbes and forming those great carbon-storing clumps.
CARPENTER: You know, when do you see bare ground in nature? It’s only after a natural disaster, usually. So when you’re tilling, you’re basically creating a series of natural disasters over and over and over.
TWILLEY: Assawaga is the polar opposite of a natural disaster. The farm is in a little clearing in the forest, and it is really beautiful. It’s full of life—when we visited there were birds, and frogs, and a little caterpillar turning into a butterfly.
GRABER: We walked carefully on paths between the beds, so that of course we wouldn’t disturb the soil, and we got to snack on some Chinese broccoli, right off the stalk.
TWILLEY: Mmm, mmm.
GRABER: Oh, my god. [TASTES] This, it’s so sweet. Oh, my god.
TWILLEY: Yum! At this point, I was getting serious vegetable envy. When I sow my veggies at home in my little container garden, I dig a hole for the seeds or the seedlings. But that disturbs the soil, obviously. So how do Alex and Yoko get their seedlings in the ground?
GRABER: Alex showed us this cool tool they have, it’s a paper pot transplanter.
CARPENTER: Instead of growing in a plastic tray, starting the seeds in it, we start them in a—it’s like an accordion paper cell. So then you start them, they grow. And then when it’s time to transplant, you put them on this. And you walk backwards and you pull this and it unwinds the paper chain. And puts it in the ground for you.
GRABER: The paper pot transplanter carves out a narrow space in the soil and just lays the seedlings right in there. But wouldn’t the ground be covered with all those great living intercropped plants? Where is there space for the new crops?
TAKEMURA: That’s the tricky part of no-till. [LAUGHTER]
TWILLEY: But there’s a few ways around this problem. Yoko told us that some of the plants they put in as cover crops get killed naturally by frost, and just turn into mulch.
TAKEMURA: So that’s great for if we need to put a plant in early in the season next year because it’s gonna be dead already. There’s no need to kill it. The rye that we’re sowing now, that’s not going to winter kill. And by May, it’s just gonna be super tall. So what farmers do is they crimp it down. I mean, it’s just as simple as just pushing it down.
GRABER: Alex and Yoko have a tool that does that crimping and just pushes the plants down, and then there’s space for the new crop.
TWILLEY: Some farms that are low or no till just kill the cover crops using herbicides.
GRABER: Which seems to not be the greatest solution. Alex and Yoko don’t do that.
TWILLEY: Still, there are clearly ways to farm without disturbing the soil. But here’s my question: Isn’t the whole point of our whole system of agriculture that annuals need disturbed soil? Or at least really prefer it?
TAKEMURA: I don’t know if they necessarily prefer it as much as they are very opportunistic. And when there is, you know, disturbed ground, they kind of like leap on it. And they’re like, I’m the first one there.
GRABER: Yoko says annual plants might take advantage of disturbed soils, but they do fine in undisturbed soils, too. And anyway, annual plants like broccoli and tomatoes and peppers do love good, nutritious soil, and carbon-rich soil certainly is that.
TWILLEY: OK, at this point I was about to sign up for the cult of no till. Alex and Yoko were making it sound so sensible and so simple.
GRABER: But Tim and Asmeret told us it wasn’t quite as easy as all that.
CREWS: It is among the most sophisticated and challenging and, and dicey in some ways methods of agriculture, because a lot of things have to line up. In terms of the weather, in terms of getting out there to do the work so that you don’t miss a window that’s critical in organic no-till. The implementation of it is, is very challenging.
BERHE: Yeah no it’s definitely intensive in terms of labor and management that has to go in. Not just intensive but also you require knowledge, right, of how to manage soils in these sustainable ways. And so it’s definitely not necessarily as easy as intensive production systems. But I think the number of farmers that—the number of farmers that are practicing regenerative agriculture keeps growing and that’s a demonstration that it’s doable.
CARPENTER: It’s probably more labor intensive. Well, it’s a different intensity. You know, it’s a totally different way of thinking about it. And I think for a lot of farms that have learned conventionally, it’s not easy to switch the entire way that you think about a system. So is it more work? I don’t know if it is. I think that over time it gets to be less work, actually. Our inputs become less. We’re not working the soil. We weed in June.
TAKEMURA: We weed very minimally.
CARPENTER: Very minimally.
TWILLEY: And Alex and Yoko told us they take off each winter—they go away, often to Japan where Yoko is from. So that’s pretty nice.
GRABER: Of course the rest of the year is kind of full on, non-stop work. It’s just the two of them on the farm, and they do literally everything. And they both say it’s not easy.
TWILLEY: Or maybe even possible on a bigger farm.
TAKEMURA: You know, I think there’s a big benefit for, you know, us having a small farm, because when I just explained to you my crop plan for next year, having intercropping, almost every vegetable, that’s really hard to manage. It—I don’t even know how we’re going to manage it next year.
CARPENTER: It’s also hard on a large scale, I think. I don’t know what the scalability is.
TAKEMURA: But it, it would be amazing if there could be a lot of small farms rather than very handful of large farms.
GRABER: Of course, if Yoko’s dream of lots of small farms were to become a reality, that would mean we’d need a lot more farmers than we have right now, and there are all sorts of challenges and roadblocks to making that happen.
TWILLEY: The other thing is that Yoko and Alex are growing veggies at Assawaga, and veggies are something we could all use to eat more of. But really, our diet is built on a few commodity crops. Big fields of wheat and corn and soy. So can no-till work for those crops too?
CREWS: There are a pretty amazing group of, of growers in the Midwest especially who are practicing no-till but with a, a great deal of cover crop implementation, cover crop cocktails and only periodically using an herbicide.
CREWS: So they’re not what—you—nozzle heads where they’re just spraying, spraying, spraying. Their judiciously hitting a crop just to break a cycle after maybe two years even and then resowing. And in my mind that, in terms of managing a broad landscape, is very attractive.
GRABER: Tim’s excited about what these farmers are doing with what he calls partial no-till, semi-till? But he’s even more excited about something else—a project that he and Lee have been working on in Kansas.
TWILLEY: So here’s the deal: like we said, early farmers in the Middle East locked us into the whole annual crop thing ten thousand years ago.
CREWS: And once we were into it, we were into it for good because lo and behold, the annuals did respond. They stopped dropping their seed at the end of the growing season. They started to ripen at the same time. All logical outcomes of simply gathering a harvest and resowing it.
CREWS: Anyway, you can see where I’m going with this. It had nothing to do with a juxtaposition of potential yield of a perennial and an annual. And now ten thousand years in, we’re asking the question: could it have worked?
GRABER: Could agriculture have gone down the perennial path instead of the annuals, could we grow as much food as we do today and use plants that stick around for years and whose roots keep building up that carbon bank in the soil?
TWILLEY: We went to visit Tim and Lee in Salina, Kansas, to find out.
TWILLEY: Yeah, you came in bearing, bearing gifts. What is that?
DEHAAN: Kernza bread. Yes—
GRABER:It’s gorgeous. Did you make this?
DEHAAN: Yeah. I baked it last night. I can save it for later, or…
GRABER: I kinda want to try it.
TWILLEY: Let’s try it!
GRABER: I like getting welcomed with bread. This is great.
TWILLEY: It’s such a beautiful loaf.
GRABER: Kernza. This is the reason Nicky and I were in Kansas. Kernza is a special grain that Lee and his colleagues have been breeding to see if they can come up with a perennial substitute for wheat.
DEHAAN: Kernza is a domestication program. So we’re not crossing with another species. We’re just working, always taking the best plants and crossing them together. Basically the same process that our ancestors would have gone through with developing our annual grain crops. Just an accelerated way. Hopefully not taking 1000 years this time around.
TWILLEY: This is a dream that some plant breeders have had for a long time—that somehow we could turn back the clock of agriculture and start over with perennial crops, rather than annuals. Of course, in the past people weren’t trying to do this for climate change reasons, they figured perennials would help with soil fertility and also save money on seeds and labor.
DEHAAN: Yeah. So at least to the 1930s in Russia, there was a perennial wheat breeding program. And it was worked on for quite a long time. At that point, we didn’t even know about chromosomes and DNA. And—so they were working pretty blindly and it’s fairly amazing how much progress they did make. Unfortunately, it never got to the point of having varieties that were yielding as much as annual wheats.
GRABER: Eventually the Russia perennial project was dropped, and then the Land Institute was founded in 1976 in Kansas. And the researchers there were interested in building back up the depleted agricultural soils of the midwestern prairie, and they wanted to do that with perennial plants that could be also used for food.
DEHAAN: So the Land Institute first started working early on native prairie plants. Looking at: can we use them and using them as maybe analogs of what could become the perennial grain crop someday?
TWILLEY: The Land Institute team screened about a hundred different grasses, looking at their seed yield and seed size and seed quality. First they looked at native grasses—things like Illinois bundle flower or eastern gamba grass, which is a relative of corn. But those didn’t seem super promising. So they decided to try a grass from Europe and Western Asia, the part of the world where wheat is originally from.
Lee: Eventually, they decided—settled on this plant called intermediate wheat grass or thinopyrum intermedium.
TWILLEY: Neither of which is a particular catchy name for a new grain.
DEHAAN: So a couple of employees, myself and a few others, started sitting around with a blackboard and writing up ideas. We were looking for something that was sound grainy. So we had a lot of root word “kern” in there, because that’s kind of the root of kernel and that sounds grainy to us. And then we ended up kind of combining kern with the ZA of kanza, the Native American word, the origin of Kansas. So combining those two things, we kind of have grain from Kansas.
GRABER: Kernza, the perennial grain domesticated in Kansas. Which is what we tasted in the bread Lee baked for us.
DEHAAN: Yeah. So it’s not a hundred percent. This is about 25, 30 percent, 30 percent Kernza flour, the rest as normal wheat flour. So it does really well up to 30 percent and even 50 percent is OK. But as we go to 100 percent, you’re going to get a very dense loaf. More like a German rye. Kind of a dense, heavy, heavy loaf, which is also good. But it’s not what everyone prefers.
TWILLEY: Honestly, this was a magazine cover worthy loaf. Lee had scored the crust into perfect diamonds and it was a deep toasty warm brown—a little more terracotta toned than whole wheat, I’d say.
TWILLEY: Can I sniff it though first?
GRABER: It smells really good. I could smell it all the way over there.
GRABER: It smells incredible. It’s um—it does have its own smell. It’s a little maltier somehow or something? Sweeter.
DEHAAN: When you bake it, to me, it smells a little bit like honey or molasses. I don’t taste that as much when I actually eat it, but it really has a unique scent that comes out when you bake it.
SLICING BREAD, EATING
GRABER: I mean, that’s kind of like—I just, to me tastes just like really good bread.
DEHAAN: You know, with grains as a staple in your diet, you don’t necessarily want it overwhelming. A lot of issues with new grains has been they’re a little bit too flavorful. So I think it’s been a good fit that way for us.
TWILLEY: Lee also has experimented with kernza flour in pancakes and in waffles, which he says is really good. And in cookies and cakes too.
GRABER: The way we just told you about kernza, you might think—wow, this is great, and so easy! You can breed a new grain, and it’s a perennial, and it’s delicious, and this whole project is going to solve our problems!
TWILLEY: But actually Lee and before him other Land Institute breeders have been working on making this spindly yellow grass with tiny little seeds into what is now kernza for a couple of decades already. Trying to compress the whole process of domestication into twenty years is a lot of work.
GRABER: Lee and his predecessors have had to plant tens of thousands of plants, and know which one is which. They have to grow those plants out. They cut the heads that have the seeds in them, get the seeds out through threshing, and then study them thoroughly. Like Nicky said, this all is just a shocking amount of work.
DEHAAN: People often say, boy, being a plant breeder, you must be very, very patient. I say, no, you don’t want a patient plant reader. You want an impatient plant breeder that’s always just trying to find some way to speed it up. Because that’s the deal is we can’t have this take one hundred years. It has to—we have to go faster.
TWILLEY: In the past, Lee used to plant 20,000 little kernza babies each year. But nowadays they’ve sequenced the kernza genome, which means he can work much faster—he can predict how a seedling will grow over the next five years without having to wait five years. And it’s also just a lot less work in the field.
DEHAAN: With the transition now to this genetic approach, we’re doing much fewer plants. We’re doing 3,000 plants a year instead of 20,000.
GRABER: All of that work over the past two decades has led to a plant that produces grains that can be ground up and used in baking. It really is kind of amazing. And Lee says it actually happened faster than he thought it would.
TWILLEY: That’s because of some very lucky mutations. One year, Lee basically won the plant breeder lottery and found a kernza baby with what he called naked grain—its seeds were much more like modern wheat, because they didn’t have a protective hull or shell around them. Naked grains are much easier to harvest and process.
GRABER: And that same plant held onto its grains instead of dropping them onto the ground like most wild wheatgrasses do.
TWILLEY: Lee incorporated those mutations into his next generation kernza, whose grains are now naked, firmly attached to the stalk, and twice the size of its wild ancestor.
GRABER: And now Lee has rows of Kernza planted in the fields around the Land Institute.
TWILLEY: So we went to say hi to the kernza.
GETTING IN CAR.
TWILLEY: It was a sunny day but the ground was a little muddy from some recent rain. Fortunately Lee drives a big truck. Still, there was a moment or two when we thought we were going to be pushing it.
CREWS: Woohoo! LAUGHTER
GRABER: Feel like Dukes of Hazzard.
DUKES OF HAZZARD THEME SONG
TWILLEY: Excuse us for a moment, we’re flashing back to the 80s.
GRABER: Okay. to head back to the future, or Kansas: We were out in the field, and above ground, kernza really doesn’t look much different from other wheat. It’s just like a field of tall grass.
TWILLEY: Where things get more interesting is underground.
CREWS: Alright. So now this is a soil pit that has been there for a little while and it hasn’t been cleaned up. Are you good to venture down?
GRABER: Yep. Yep.
TWILLEY: This is why we didn’t wear our heels. LAUGHTER
GRABER: Okay. Here we are climbing down into the soil pit.
CREWS: So we’re just seeing a dark colored soil. This is a classic grasslands soil. And so this is what you would find under grasslands all across the Great Plains and upper Midwest. And we’ll have a lot of roots. There’s a lot of kernza roots. And they go down, they go down two and a half meters here.
GRABER: We couldn’t see all the roots of those kernza plants as we poked around in the soil in the open pit, but translating into feet, Tim says the roots were probably about seven feet long. In comparison, wheat roots are only about three feet long.
TWILLEY: But also the kernza roots were like a thatch—there were so many tiny roots all woven together. It was like the beard of Father Time or something.
GRABER: And this is a really important point. This is why perennials are so amazing. They have so much longer and more dense roots with countless tiny little rootlets shooting off than annuals do, and little bits of those roots are always dying and putting more carbon into the soil.
TWILLEY: And of course while they’re alive, all those roots and rootlets are pumping out sugar, so you get more microbes, and more microbes means more dead microbes eventually, and that’s all adding carbon too.
GRABER: Tim says these root systems put far, far more carbon into the soil than dying plants on top of the soil do. But that gets to what we really wanted to see standing out there in the soil pit—something slightly more elusive, and that’s the soil carbon itself. Luckily, it was actually visible!
CREWS: What you also see though here are these aggregates, these kind of blocks. It’s as though there’s dominoes stacked on top of each other going all the way up the profile here.
TWILLEY: Remember Asmeret’s soil carbon bank account analogy? These clumpy aggregates are the vaults—they contain the minerals that keep carbon locked away, safe from microbes and water, so it stays in the ground.
CREWS: And you can see it really well developed here. And you can imagine that if you till and you till and you till, you don’t have anything like this blocky structure.
GRABER: All of this looks and sounds great. In theory, if they grew kernza, not only would farmers lock more carbon into the soil, but the soil would hold onto more water, and farmers wouldn’t have to use as much fertilizer, and they wouldn’t have to use tractors as frequently or weed as much as in the past—
TWILLEY: But as usual I would like to be the voice of doom and say there is no such thing as a free lunch. There must be some downsides to growing kernza.
CREWS: I guess, you know, we, we can imagine some tradeoffs without question. One would be that perennial grains lock your land into certain crops and you can’t pivot based on economics on an annual basis to, you know, change whatever it is you want to grow. SO that would be one problem. And, and there’s certainly concerns in perennial cropping systems about the accumulation of pathogens, herbivorous insects. We have to rethink how we approach pest management when it comes to longer term perennial stands. No question.
GRABER: But of course the greatest downside of all, at least right now, is that kernza yields so far are pretty crappy.
DEHAAN: If things go really well for you as a farmer, we hope that you can get something like 600 pounds per acre. And that’s a, a fair bit less than Kansas wheat yields, which would be more like 3,000 or 2,500. So, you know, 10 or 15 percent the yields of, of wheat. So we have a long ways to go in yields.
TWILLEY: Yeah that’s quite a bit less. And some people think that perennial grains like kernza will never achieve the same yield as wheat.
GRABER: But Tim and Lee think that they might be able to, a few years down the line. We’ve been domesticating annual grains far, far longer than perennials. Just because they have low yield now, they might not forever.
DEHAAN: I have calculated that I still think it’s going to take in order to equal the yield of wheat. It’s going to take us at least another, let’s see, 25 years or so.
TWILLEY: 25 years! We don’t have 25 years! The climate crisis is now.
GRABER: But kernza is actually pretty useful now, which is fortunate. Lee says some local farmers he’s working with like it because when conditions are great, they can harvest the grain, and if the yield is not so great, it grows anyway and they can use it as forage grass for animals. Two in one.
TWILLEY: The other thing that Lee reminded us is that kernza doesn’t have to replace wheat altogether to have a huge impact on soil carbon. If you just replaced 2 percent of the wheat in wheat products with kernza instead, that would mean a lot of land would get switched to a perennial grain.
GRABER: And that would have a big impact for the soil. Also it would be pretty easy for companies to do. It wouldn’t be hard to substitute just a few percent kernza flour into bread, cereal, cookies, whatever without changing the flavor or the texture.
TWILLEY: And some companies are already trying to do just that. In fact, General Mills wanted to roll out a new breakfast cereal that incorporated kernza last year, but they couldn’t because the yields weren’t good enough.
GRABER: Cascadian Farms did manage to put out a very limited release—6000 boxes of Honey Toasted Kernza Cereal.
TWILLEY: Lee says a lot of independent restaurants and bakeries and breweries have been experimenting with kernza too. And Patagonia has put out a kernza-based Long Root Ale and a Long Root Wit beer, which have apparently been pretty successful.
GRABER: And we of course needed to try some beer. One of the local breweries is Salina, Kansas is using kernza in their beer, and so we went over and had a drink.
GRABER: Good, a little sweet, nice and bitter.
TWILLEY: This is a perfectly delicious IPA, it doesn’t taste very much… there’s nothing in it that I would be like, that’s the kernza. I mean, I don’t know. It tastes like beer.
GRABER: Exactly, okay, enjoy!
TWILLEY: I did! Kernza beer is good, and kernza bread is good, and the kernza pie crust I baked with the flour I took home from Salina was also good. And kernza seems like one day it will be a really good option for farmers who want to grow grain and don’t want to tear up their soil and let loose all its carbon. But as Lee and Tim kept pointing out, yes, they’re domesticating a new crop way faster than our ancestors did, but they’re not quite there yet.
GRABER: So we wanted to understand more about this super cool breeding program and about no-till agriculture because they can add carbon back into the soil.
TWILLEY: And the goal, remember, is to add more carbon to the soil to help mitigate climate change. So these techniques are exciting.
GRABER: Asmeret told us there are other tricks to add carbon, too, like adding compost or something called biochar to the soil. A lot of farmers around the world are involved in a variety of projects to try some version of these techniques.
TWILLEY: Asmeret and Yoko and Alex and Lee and Tim—they were all happy to tell us how these techniques would make a difference to soil carbon. What they wouldn’t say is how much of a difference.
CREWS: The estimations range from uh—well, I’m not—I won’t put out any numbers out there actually right now.
GRABER: Tim won’t put it in any numbers because he can’t. Nobody knows exactly. Asmeret is working on measuring carbon in soil, Tim is working on measuring carbon that escapes from soil, everyone’s trying to figure out just how much carbon could be stuffed into soil to help deal with climate change.
TWILLEY: Part of the problem is that different soils are very different in terms of how much carbon they can store. And scientists think there is a maximum of how much carbon can be stored, although that’s hard to pin down too. And the shenanigans scientists have to get up to to try to get a measurement of soil carbon are bananas—we’ve saved those stories for our special supporters newsletter.
GRABER: It was just too much for this episode—there’s so much to cover! Climate change, domestication? These are not small topics.
TWILLEY: But the point is, we don’t really know much carbon can be stored in the soil. But scientists do agree it’s substantial. So my next question is, how soon can we do this? Because the planet is already on fire!
BERHE: So this is a long-term commitment. It’s not something you’re going to change in one year or two years or even five years in any significant way. So to give you an idea, I’ll give you the reverse example right. So if you started out say from a soil that had 5 percent carbon that was under a forest. And you put it under intensive cultivation system. In about 30 years or so of intensive production you can lose half of it. So as you can imagine then building back up is going to have even slower slope. So we’re talking about you know decadal commitments here.
GRABER: Decades? We need solutions now!
TWILLEY: And just to pile on with the bad news, everyone agrees that soil carbon storage is not actually enough to solve climate change on its own.
CREWS: It’s just not. And so it’s a hard thing to message. It’s hard thing to get people excited about at just the right level because it is really exciting.
TWILLEY: There’s a lot of hype about soil carbon banking and even companies investing a ton of money in it. Some states, like California, where I live, have launched big soil carbon farming initiatives of their own. And then there’s also a lot of cynical headlines saying that these numbers are overblown and soil carbon banking can’t make much of a difference.
GRABER: But it can make some difference—and so we do have to do it. But it’s just one of the many things we have to do to try to address climate change. Of course we have to switch away from fossil fuels and stop emitting carbon dioxide, but we also have to pull carbon out of the atmosphere. And putting it in soil is one of the ways we can do it.
TWILLEY: Putting carbon back in the soil with no-till agriculture and compost and perennial grains is never going to be as sexy as some of the big ideas floating around, like a giant machine that sucks carbon from the sky. But we already know it works, and we know a lot about how to do it. So I actually think the soil solution is pretty sexy.
GRABER: So what can all of us non farmers do about this? Well, if you know your farmers, you can ask them about tilling and cover crops, that could lead to an interesting discussion. That’s how I found out that Assawaga was no-till, I just chatted with them and was curious about their farm.
TWILLEY: You can also look out for the Patagonia products that have kernza in them—their long root pale ale is a mighty refreshing beverage and a fun way to support research into perennials.
GRABER: And Asmeret told there are folks at the USDA working on a label that’s like organic but for healthy soils.
TWILLEY: Which would be helpful for those of us who want to choose foods that help reach that goal of adding more carbon to the soil to help get it out of the atmosphere.
BERHE: But even if we don’t succeed all the way in that goal we still end up with soils that have more carbon than we started out with, are hence healthier and can produce more of the food that we want and can mitigate against climate change even better.
GRABER: Thanks again to the Alfred P. Sloan Foundation program for the Public Understanding of science, technology, and economics for their support of Gastropod and of this episode.
TWILLEY: Thanks also to Asmeret Berhe at UC Merced—we have a link to her webpage and her recent TED talk on our website, gastropod dot com.
GRABER: Thanks also to Yoko Takemura and Alex Carpenter of Assawaga Farm—you can find their veggies at a couple of Boston-area farmers markets. And to Lee DeHaan and Tim Crews of The Land Institute. We’ve got links to much more of their work on kernza and perennial grains at gastropod dot com.
TWILLEY: We’ll be back next week with the marmite of the confectionary world: licorice. You probably already know whether you love it or hate it, but its science and history will blow your mind!
GRABER: Don’t forget to apply for our summer fellowship. If you’re interested, go to gastropod.com slash fellow for more information.