Can we sequester our carbon and eat it too?

For the first time in 4 seasons, we're discussing natural climate solutions, and in particular, regenerative agriculture. Joining us is agrologist and fellow podcaster, Scott Gillespie (of Plants Dig Soil) to get into the nitty gritty of farming for soil carbon — its promise, possibility and feasibility.

———

Support Future Ecologies (pay what you can >$1/month) @ futureecologies.net/patrons 🌱 — Get access to our delightful discord server, early episode releases, an exclusive podcast feed for bonus content, and more:

Find a full list of citations, and a transcript for this episode: futureecologies.net/listen/fe-4-8-ground-truthing

You are listening to season four of

Future Ecologies.

Okay, let's do it.

Okay. I'm Adam.

Mendel.

And this is future ecologies. And I'm here because

Mendel invited me to be here to talk about natural climate

solutions.

That's right.

Which, which are...?

Which are, you know, a whole bunch of different

things. But they're basically all the ways that we can harness

natural ecosystems or natural processes to mitigate the

impacts of climate change.

Yeah, basically non-technological solutions to

sucking greenhouse gases out of the atmosphere.

Right.

And this topic is all of the rage right now in

climate circles, because well, because it's hopeful. And it

promises to provide a way for us to restore ecosystems and to

protect biodiversity and have benefits for human communities

as well. All while sequestering lots of carbon.

Yeah, natural climate solutions are usually

pitched as this big win-win-win. And, you know, conveniently,

that pitch usually skips the part where governments or

industry have to reduce their own emissions.

Yeah, it's always easier to promote and invest in

something that doesn't require the powerful to make sacrifices.

Yeah. Although, you know, ideally, those

solutions are implemented in tandem with reductions in

greenhouse gases from human sources. It can't be either/or,

it's definitely a yes/and kind of situation.

Yeah, we have to do all of it. And even though we

did a whole set of seven episodes on the climate crisis a

couple of years back —

— right, yeah. That's Scales of Change, for

newer listeners —

we actually didn't talk much at all about natural

climate solutions in that series. Did we even did we

mention it?

No, I mean, it was supposed to be a series

about climate inaction. You know, and of course, we had to

sneak some action in there, too. But no, you're right. We really

didn't cover natural climate solutions. So we're here today

to redeem ourselves, and maybe generate some hate mail.

Wait, wait, really?

Yeah.

We don't want to do that.

No. You know, I just think that this is honestly

going to be one of the most controversial episodes we've

ever made.

God, I hope not. I'm I'm actually really jazzed

about natural climate solutions. And I'm so excited that I did a

bunch of background research. I hope that's okay.

You're incorrigible. You're supposed to

be the blank slate for this one.

It's hard for me to pretend to be the blank slate

on the subject that I spent most of my time working on. Can I can

I share with you what I found?

Sure.

Okay, here we go. natural climate solutions tend

to focus on enhancing the ability of natural processes to

capture and store carbon in living biomass and in the soil.

And also occasionally in rock, which we actually did talk a

little bit about on Scales of Change. Anyway, we can sequester

all this carbon by planting forests in places where they

used to be, or where they could be — that's afforestation or

reforestation. We could also protect and restore wetland

ecosystems, and especially peatlands because they are so

carbon rich.

Yeah.

And finally, we can improve agricultural

practices to store more carbon in crop and pasture lands.

Hey, guess what.

What?

Today's episode is about that last one, storing

more carbon in agricultural soils.

Nice. Okay. Well, in that case, one thing I

learned about that is that there is huge potential for the

agricultural approach. Like globally, but also in Canada

specifically, I read a major study recently that was

published earlier this year, and found that Canada currently

stores about 20% of all global soil carbon.

Well, that's, that's actually more than I

expected. I mean, it is a huge country, but like a bunch of

that is in wetlands, right?

Yeah, about a third of Canada's soil carbon is

stored just in peatlands, which only cover about 12% of the land

surface here. But you know, are a huge carbon sink. About half

of that soil carbon is also in permafrost, you know,

permanently frozen soils, which, as we've learned are a giant

ticking climate time bomb.

Let's not go there.

Let's not go there. But the rest is stored in

other ecosystems. And just to put all of this in perspective,

this is do that already estimated that over 20 gigatons

of carbon are stored in living biomass in Canada,

Right, so like trees and shrubs and roots and

animals.

Yep.

And by 20 gigatons you mean 20 billion

metric tons of carbon?

Yeah, a gigaton is a billion tons, or about 10 to

the 15th power of grams. A petagram, actually!

And that's a lot.

Yeah, one gigaton of carbon is a lot. 20 bigatons

is inconceivable. But um, you want to know how much is stored

in the soil?

Hit me.

Apparently, over 300 gigatons are stored in the

top one meter of soil alone, here in Canada. And as much as

260 more gigatons in the next meter down. So you know, 20

gigatons in all of the living biomass in Canada, and over 15

times that amount in the top one meter of soil alone.

Well, I have a statistic for you: the carbon

that used to be in the soil, and was lost due to agriculture over

the past 200 plus years.

Oh, yeah? Lay it on me.

So this one is also an estimate, as are all

huge numbers. But worldwide, agriculture has released over

116 gigatons from the soil.

Yeah... so there's lots of soil carbon in Canada.

Yeah. And lots of agricultural land in Canada.

And it would follow then that this country

probably accounts for a big chunk of those global soil

losses.

Yeah. I mean, the areas that have been farmed

and grazed intensively in the past often have organic carbon

levels that are way, way below their ancient capacity. And you

can look all around the world, the places with the most intense

history of cultivation, are now the ones with the most degraded

soils

And the least soil carbon.

Yeah. So today, we're not just talking about

keeping it in the ground, we're talking about putting it back.

From Future Ecologies, this is Ground Truthing.

Broadcasting from the unseeded shared and

asserted territories of the Musqueam, Squamish and

Tsleil-Waututh, this is Future Ecologies: exploring the shape

of our world, through ecology, design and sound.

Okay, so to sift through the story, I brought in

some help.

Hello!

Scott. Adam. Adam, Scott Gillespie.

Hey, Scott, thanks for joining us.

Glad to be here.

So Scott is a professional agronomist in

southern Alberta, which is the traditional and present day home

of the people of the Blackfoot Confederacy.

Yeah.

I've been to southern Alberta, but I don't

think Future Ecologies has. Scott, would you help situate

us?

Well as our local country singer, Corb Lund,

we're East of the Rockies, and we're West of the

rest. Right at the edge of what we call the prairies in Canada,

or the plains in the United States: the great grasslands of

North America.

Well, for those of us who are even West-er, maybe

you could tell us what it's like to be out there.

Yeah, well, as you can probably picture, trees

don't grow here naturally. It can be a place of intense winds

and extreme temperatures. Historically, it would have been

a pasture of huge herds of bison. And now it's been

converted to mostly agriculture in one form or another. So in my

area, which is in the south of the province, we live in what

the farmers here call the brown soil region.

I love that. I love that you use the color of

the soil to describe the character of the place that you

live. What is it that makes the soils there Brown?

It's basically the fact that it's so dry here.

Over geological periods, we just don't get a lot of rain. So, not

a lot accumulates in the soil. As you go further north through

the province, you get more rainfall. And then you get into

what they call the dark brown soil, and then eventually you

get to the black soils, which are these beautiful rich soils —

that are full of organic material.

Do I detect a bit of soil envy there in your

voice, Scott?

Maybe a bit.

So Scott, maybe you should tell us what an

Agrologist is?

Okay. Well, the easiest way to think of it is if

you think of what a veterinarian does for animals, an Agrologist

does for plants and soils.

And you have your own podcast.

Yeah, Plants Dig Soil.

Where you help farmers practice something

called regenerative agriculture.

That's right.

And you know, I think we'll get into exactly

what that means later. But first, let's cover some basics.

Climate change is here. And it's happening faster and stronger

than almost anyone predicted. And as we all know, the main

molecular malefactor is of course...

Carbon dioxide.

Yeah. And ultimately, the carbon causing

all these problems came from under our feet. The source of

the carbon that we hear the most about, and for good reason, is

fossil fuels. But it's not the only one. As you mentioned in

the intro, a significant chunk of human caused emissions came

from the soil itself.

Right, yeah, living in the age of

agriculture, we took — what... what was it, Mendel, 116?

Yes.

116 gigatons of carbon out of the soil. And that all went

straight to the atmosphere.

Well, not quite, because it's not totally

clear how much of the carbon went back into the ocean, either

as dissolved carbon dioxide or unfortunately as dust from

topsoil erosion.

Right... Yeah, erosion and ocean acidification.

Neither of those are are good either.

No. But you know, together, we quantify

those losses and call them the "soil carbon debt": the carbon

that we owe back to the soil. You could basically say that we

cashed out millennia of carbon to grow our crops as quickly and

easily as we could.

Yeah. And there was even a belief among the

European colonists that with proper tillage, there was an

inexhaustible supply of plant nutrients — flowing up from the

deep. And because of a fluke of the climate, they happened to be

establishing these farms during a wet cycle, leading them to

think that plowing fields caused more rainfall.

Wait, are you serious?

I'm serious.

Does plowing cause rainfall?

No, it doesn't. But it all ended when the dry

cycle returned in the 1930s. So you might heard of the Dust

the topsoil was so depleted, it just simply blew

off the land.

So here we are. And we're looking back at all of

the damage caused by intensive agriculture and all of the

carbon that's been released. And of course, the obvious question

is, why don't we just put it back? Right? If if there's room

in the ground for billions more tons of carbon, then

theoretically, we could solve climate change and repay our

weary soils at the same time. It's the obvious fix.

And that, plus the little wrinkle of feeding

the world —

Right that, yeah, too

That's the dream of regenerative agriculture.

So regenerative agriculture means different things to

different people, at least in terms of what it looks like in

practice. But I think everyone would agree that the goal is

growing food, while simultaneously enriching, and

you know, that is returning carbon to the soil.

Well, let's dig in. How does the carbon get into

the soil? And how can we help?

Well, this is where things get more

complicated than we could ever cover in a single episode. So

let's just break it down to what we can understand at a couple

different levels.

Sure. Yeah, that's par for the course for Future

Ecologies.

So the first level is that there's only one

way to increase soil organic carbon: living growing plants.

So you could say, plants dig soil.

Ya' could.

If you think about it, ultimately, the only

new carbon going into the soil is from the plants,

Right. Primary production — classic ecology

here. As opposed to animals and fungi, plants famously

photosynthesize, and they use the sun's energy to turn carbon

dioxide in the air into their own bodies. A thing, which, when

I first learned, it, absolutely blew my mind because I thought

they were building their bodies directly out of the soil. And it

turns out, almost all of that is from the atmosphere. Totally

freaking incredible.

And it's important to remember that those

bodies aren't just above ground where we can see them.

Generally, about a third of the mass of a plant, which is almost

all carbon is in its roots. So grasslands put more into their

roots, forests put more into the woody structures. But generally

30% is a good rule of thumb. So in a food system, there's a

portion that is harvested and exported off the land. Some of

that carbon will be eaten, and most of that will return to the

atmosphere with every human breath.

But some of that harvest that you're talking

about is is not going to make it into people's bodies and onto

their tables. Because it's stuff like leaves and stems and husks

and roots — stuff that we don't tend to eat as people, right?

You have to grow a lot of plant material to get an ear of corn,

Right, and that carbon will get eaten by

something else. The first step is usually for grazing animals,

earthworms, or any other large critters of the soil to eat it.

And they break it down to a more manageable size for the main

fungi and bacteria.

So you have the portion of the plant that we eat

and respire, and you have the portion that, you know, passes

through our bodies, of course. But everything else should be

going back to the field that it was grown on, right?

So in theory, yes, but practically no. Most

food travels 1000s of kilometers, sometimes across

oceans. No one wants that back. If crop waste, food waste, or

humanure gets buried in landfill, you'll get a lot of

methaneÚ a greenhouse gas, it's 84 times worse than CO2. If

instead it gets composted, you'll still lose some of the

carbon to the air as those microbes eat and breathe. But

you can put a lot of it back onto the field.

Yeah, the problem is still that you need

to get it to a field, maybe not the original field that it grew

on. But any field nearby can benefit from this far better

than just putting it into a landfill. But the real trick is

getting that carbon to stay there.

Okay, then let's go to level two.

Level two!

The way the carbon from these plants

actually becomes part of the soil. As the plant grows, as

much as 25% of the carbon formed by photosynthesis is released as

a liquid by its roots. These liquids called root exudates —

Yeah, because they're exuding — roots exude

Yes. And these liquids feed the fungi and

exudates.

bacteria that live in the soil. Now, when I was in school, 20

years ago, it was thought that the roots were just leaky. Now

we know that they tune exactly what molecules they release:

they're trying to attract the fungi and bacteria that they

want hanging around the roots.

That's so wild.

Now some of this liquid carbon will go right

back off as CO2 as the microbes use it for energy. But through a

complex series of symbiosis, this microbial ecosystem locks

in the carbon into clumps of solidified soil grains called

aggregates.

Got it.

Now how long that carbon stays in the soil

depends on the stability of those aggregates, which may get

disturbed by earthworms, new roots moving through the soil,

tilling, droughts or floods.

Now how much carbon gets into soil depends on a huge number of

the amount of rain, the proportion of sand to clay, the

slope, the health and the diversity of all those microbes.

But the most important by far is simply the amount of

photosynthesis happening in the first place. The more green

growing plants, the better.

Well, so far, none of this sounds particularly

controversial to me.

I would say we're still on firm ground.

That's all pretty settled, if over-simplified soil science.

But the debate really starts to heat up when you wade into the

question of "what should we do about it?"

People arguing about climate policy? I can't

believe it.

This isn't the classic case of climate deniers

versus the world.

No?

No. And you know, wouldn't bother making

this episode, if it were. The people on both sides of this

debate really just want the same thing. And that's carbon

drawdown and food security. Where their opinions differ is

whether we can count on soil carbon sequestration to get us

there.

Ss in, should we pay farmers for adding carbon

to their soils?

Oh, okay. So now we're talking, I think, about

carbon credits. Which are, you know, market solutions for

market problems. Am I right?

Yeah. Well, I'm actually still on the fence

about it. Because farming at scale is really expensive, and

the margins can be razor thin. You know, for a farmer, any

little change in behavior can mean tens of thousands of

dollars up front, without any guarantee of success at the end

of the season. So if we want to make our food system less

destructive, we need to find a way to help farmers make the

leap. But then again, if we're going to pay for that carbon, we

better be damn sure it's real.

And that's the root of the debate. Selling

carbon credits can lock farmers into complicated contracts that

may or may not make financial sense to them. It might give

polluters the excuse to continue their business as usual,

canceling out the climate benefits, or even worse, the

soil carbon backing those credits might not be there at

all.

Wait, what do you — what do you mean?

Scott? Are you ready?

Yep.

Ring the bell, cuz we've got a list.

Did I miss something? Like, do we have a

segment called "Ring the bell, read a list"?

Just go with it.

Okay, so there's four things that are

good carbon credit has to represent: additionality,

non-reversal, lack of leakage, and permanence.

Additionality means that we want the carbon to be sequestered

because of the credit incentive. That is, it's additional to our

baseline.

Right, the business as usual scenario. So

for it to have any benefit to the climate, it has to go above

and beyond the status quo.

Exactly. And then there's non-reversal, which

means that those credits also have to contend with that

temperamental flux that is soil carbon, either by a change in

farming practices or, you know, uncontrollable factors, like a

change in the climate.

Can you imagine?

Right? It could cause that carbon to go from

being locked up in soil aggregates, to right back up in

the atmosphere.

Yeah now, farmers aren't generally on the

hook for reversals outside of their control. But it does raise

questions about what happens down the line. In Canada and the

United States, approximately one half of farmers rent the land

they farm on. They can't guarantee how the next tenant

will treat the soil.

No. And landlords and owner operators

might also feel conflicted about signing contracts. What if an

opportunity for a lucrative cash crop comes along, you know, five

or 10 years later, but the practices of farming it go

against the sequestering of carbon?

Right, I'm starting to get a sense of how

this could be complicated.

Well, then meet leakage. leakage is when a

climate positive action in one place causes a climate negative

effect somewhere else.

Say for instance, if (and this is a

contentious if) regenerative farming practices results in

lower food yields, than the market would put pressure on

other farmers to convert yet more land, perhaps by clearing a

productive forest or prairie.

Yeah, nobody wants leakage. Now, not only would

that be outside of the carbon farmers control, they might not

even know about it, right? Like you're talking about a systemic

pressure because of the price of food or or land.

Yeah, you've got it. And finally, there's

permanence.

So permanence is kind of related to reversal, but

it's about the time horizon. We've been talking about how

carbon naturally cycles through plants, the soil, the air. But

if our concern is reducing greenhouse gases, we really want

that carbon locked away for as long as possible. Ideally, on

geological timescales, like the fossil fuels it mostly came

from. In the world of carbon credits, that target is usually

set somewhat arbitrarily, at 100 years.

And outside of places like bogs —

We love a bog

— it's just really hard to know where that

carbon will be in a century. Think about the land around you,

and what it looked like 100 years ago. I bet its quite a bit

different than what it looks like today.

Yeah, so that's a lot that any legitimate soil

carbon credit would have to account for.

Yeah, no kidding.

So how do we actually do that? Like, how...

how do you prove that any of that is working? That you have,

let me see hold on... additional carbon, that is not reversing

itself back into the atmosphere, and isn't leaking out somewhere,

because it's permanent.

We'll get to that... after the break.

Hey, me again — here to tell you that this episode is sponsored

by... you.

You make Future Ecologies possible by sharing it with the

people that need to hear it, and encouraging them to support it

on Patreon. So far this season, we've had the help of three

guest producers and 20 musicians, not even including

Adam and myself. I'm so proud that we can pay all of those

people for their work. And we can do so because of our

supporters on Patreon. Plus, I can usually make rent and get

groceries.

If you like this show, it's because we spend an incredible

amount of time and effort on every episode. At least months,

sometimes years. You don't get to hear all the drafts and

revisions that go into each one, and hopefully you don't even

notice that they're there. We just want you to come with us on

a journey into an idea — and to let sound help tell the story,

not get in the way.

And so I wanted to remind you that it's just us. No parent

company, no corporate sponsors, no one to answer to. Except for

you, our audience. We are a proudly independent podcast, and

every single supporter makes a huge difference. Help us make

this show so that the world can hear it, and get early episode

releases, an exclusive podcast feed for bonus content,

stickers, patches, and access to one of the most delightful

discord servers out there. Support the show for as little

as $1 each month, and join our community at

futureecologies.net/patrons. We really appreciate it.

Okay, I'm Mendel. That's Adam.

Hey.

We're joined by Scott.

Hello.

And today on Future Ecologies, we're talking

about the promise of soil carbon sequestration, or how we could

use food-producing land to fight climate change.

Well, I wouldn't say the promise, but

rather the possibility. And in practice, that might be a whole

lot different from the feasibility.

Right. I mean, basically, I came here, super

stoked to talk about natural climate solutions, and you guys

are just raining on my parade.

Yes.

So to recap, we know in theory that the soil

could hold as much carbon, at least, as we've taken out of it

since the agricultural revolution, which was how much

again?

116 gigatons.

Yeah, that's a lot. But because that carbon

doesn't like to sit still — it likes to flow through plants and

microbes, and then back up into the air, and it might even leak

out somewhere else because of pressures on land use —

actually, keeping it in the ground is a lot easier said than

done.

Exactly. But that's not to say we can't do

it. Regenerative ag as it's practiced today is really just a

repackaging of different traditional agricultural

techniques from all around the world: Cover cropping,

composting, no till or low till, biochar, agroforestry matrix

planting, silvopasture... none of these are new ideas. And

they're all known to build soil and turn it dark and rich,

basically packed with organic carbon.

That's true. But proving it, and selling it

by the ton? That's another story. And it brings us into the

realm of MRV.

We love a good acronym. What is MRV?

Measurement, reporting and verification.

Basically, accounting and auditing in the world of carbon

sequestration.

Please tell me this didn't turn into an episode

about accounting.

How about we just focus on that one key

measurement. To know how much carbon any intervention

helped add to the soil, first, you have to measure how much

carbon is there already.

Sure, yeah.

And that's not easy, or cheap.

Because so carbon is not a simple compound

to measure, like, say CO2. Organic chemistry is an entire

scientific discipline studying all the compounds that carbon

can make.

Can I just say that was the best summary of

organic chemistry that I've ever heard? Even after studying it

for a couple years.

Well, thanks. So because carbon can take all

those different forms. And because soil is really variable,

and heterogeneous, on a landscape scale, carbon can be

incredibly patchy. So you need to sample enough points to get

good data. Sample too few, and you might be getting the wrong

picture. Sample too many, and you're just wasting time and

money.

And by sample, we mean physically going into

the field and getting a soil core. That is, like, drilling

out a tube of dirt, and then shipping it off to a lab to be

analyzed. Every single core is at least a few minutes of work.

Provided you don't hit a rock.

Yeah. Plus all the logistics and expenses

around the lab analysis.

I mean, I've done soil sampling before and it's

it's not that hard. But I've also only done it on like small

areas of land.

Well consider that the Canadian Prairies alone

have 77 million acres of farmland. Most city blocks are

just a few acres in size.

Yeah, it really all adds up.

Well, that's not great. Is that really the best

option that we have?

There are a few promising new technologies. But

right now, none of them are ready for primetime. Some folks

are aiming to use satellites, you know, so called remote

sensing to measure soil carbon en mass. Some are using these

meteorological stations that are called eddy towers to calculate

the carbon flux at this landscape level. And then

there's others who are developing tools that can

measure the carbon right there in the field, instead of a soil

core — using a probe that basically detects the color of

the dirt.

Right like brown, dark brown and black.

Exactly. Color can be a decent proxy for the

amount of organic carbon in the soil. And all of these tools

will be used to improve computational models so that we

can better predict what's happening to the carbon, and

then use the magic of statistics. So we don't need to

take as many physical samples.

Yeah, real magic. They've got incantations,

like regionalised variables and conditioned Latin Hypercube

sample design.

That's real Arcana. It's almost like you

want to explain a thing?

I don't.

Okay, so you're saying that these techniques are

good enough for the kinds of large estimates we've been

throwing around in this episode so far, but not necessarily good

enough to be sure that we are selling a certain amount of

carbon when we're making carbon credits.

No. And there might be one more problem.

And it's a big one.

So the way soil carbon is measured, now, those samples are

usually taken from the top 30 centimeters —

That's one foot for those of you who think like

me.

And you know, that's because the deeper you

go, the more expensive and challenging it gets. Try pushing

a probe into the soil, you know, like you said, the top is kind

of easy. But the deeper you go, the more pressure it takes,

almost exponentially.

I've done a lot of soil sampling over the years.

And I can definitely attest to that. Soil sampling is typically

done with hydraulic probes mounted to pickup trucks, and

the force is enough to lift the truck or bend the probe if

you're not careful.

Wow, okay. But why go deeper? Isn't the top foot of

the soil where most of the roots and microbes are anyway?

That's mostly true, but some roots go two or

three times that deep. In the case of prairie grasses, 10

times or more. And of course, in other places, the subsoils can

and will be a completely different situation.

And there's a growing body of evidence that

when we only measure carbon sequestration in the topsoil,

we're only getting a little slice of the whole picture,

Right — those estimates that we covered at the

beginning of the episode, were all about how the deep soils are

a big part of the carbon stocks for Canada.

But those were just estimates, not field by

field measurements. What Mendel is talking about is a particular

study that looked at how soil organic carbon accumulated with

and without cover cropping, and a variety of inputs like

chemical fertilizers and compost. What was important

about this study is that it was long term, most studies only

last the length of a grad student's degree, which is about

two to four years,

Not exactly the timescale of soil formation.

That would be a PhD.

No, but we can do a little better. In this

study, soil samples had been taken over 19 years. And various

combinations of cover crops, irrigation, synthetic

fertilization, and compost were kept consistent over that time.

Unlike your typical 30-centimeter cores, these ones

went two meters down, with five sample points over that depth.

That's uh... that's hardcore? Hard... deep

core? Anyway, deep cores, long duration, different field

variables, I'm with you.

So when no inputs were added to the system,

and no cover crops were planted, carbon in the topsoil is

decreased. Exporting food off the land meant that the microbes

needed to break apart their savings of long term carbon for

nutrients.

As you'd expect.

Now, you remember how we talked about

that to build organic matter, we need more plants growing. Cover

crops are a way to achieve this in a farming system by growing

something in the shoulder season. Before and after the

cash crop. It's one of the key practices in regenerative

systems, because it helps to build the soil.

Right. Yeah, I do this in my garden, too.

Yeah, so when winter cover crops were added to

the conventional system — as in a system that uses synthetic

fertilizers and pesticides — in this particular study, the top

soil saw a statistically significant increase in soil

organic carbon.

So far, so good.

But the rest of the soil down to meters had a

statistically significant decrease in carbon. When looking

across the whole profile. They saw not only less sequestration,

but net positive emissions on the fields with cover crops.

Wait, what?

Scary, right? That means what we typically

perceive as carbon sequestration might actually just be carbon

concentration in the top layer of the soil. And because of how

much more massive the subsoil is, there may still be

significant net carbon losses overall.

So what you're saying is that when we're just

measuring the first foot or so of the soil, we might fool

ourselves into thinking that we're sequestering carbon, when

in reality, it could be the exact opposite.

You got it. But just to be clear, having this

carbon concentrated near the surface isn't bad. That

particular crop system was doing this naturally. And so there's

probably a reason why it wants to carbon there. After all,

that's where most of the roots are. That's where the moisture

is. And that's where the microbes live. So it's good for

the farmer, just not so good if you think you're sequestering

carbon.

What about adding compost? Like to the study,

consider what happens if you're adding compost to the fields.

In that case, the carbon did increase overall.

But zooming out, that's essentially the result of

leakage from somewhere else. If that compost didn't go back to

the field that produced it, you've just transferred carbon

from one area to the other.

Basically more like carbon import, rather than

carbon sequestration.

Yeah, that's a pretty sobering study. Thank you

for, you know, hitting me with it three quarters of the way to

this episode. So I guess, you know, what that makes me think

is that when we're talking about, you know, trying to sell

that carbon or allowing it to be used as an offset for big

industrial emitters, there's a real risk here that that's a

wasted investment, or it can actually actively make things

worse.

Yeah. What it really means is that we still

have so much left to learn about the dynamics of deep soil. And

then we need to factor that into our models. And so this is

really where the problem lies. There's, there's a lot of hype,

because of models that show big changes. But you dig a little

deeper, and you see that most of them only go down 30

centimeters, and sometimes less. As of right now, they can't say

what happened in the subsoil. They can only say what happened

near the surface.

Yeah. And maybe eventually we'll develop an

understanding of how to lock huge climate shifting amounts of

carbon down into those deep soils, and find them at the same

time. And do it on a timescale that is much faster than how

long it took for those soils to form. But for now, we really

can't count on it.

Well, thanks, you two, for a hopeful and uplifting

episode. There's nothing I love more than pouring cold water on

a natural climate solution. That's what I'm here for.

Yeah, yeah, I would say it's our pleasure.

But, you know...

So, um, I guess to ask, you know, the obvious

question, what now? We're, as a society, kind of banking on the

soil being a part of our climate solution, and especially

agricultural lands. Does this mean that we just give up on

that dream? Do we give up on regenerative agriculture?

No, no, I don't think we should. Regenerative ag

can do a whole world of good — especially now, especially

during climate disruption. But, you know, in order to realize

that, we, I think we have to expand our focus right? Out from

just carbon and from carbon markets.

Yeah, if all we care about is carbon, we're

gonna miss the forest for the trees.

It's funny you saying that coming from a place

with no trees at all.

Okay, then how about missing the prairie for

the grasses?

or the roots for the exudates?

That's acceptable.

Anyhow, one thing is indisputable,

regenerative farming is still a good thing. All those

regenerative practices can make a soil system more resilient to

climate extremes, helping water filter in slowly to manage big

rains, holding on to it longer to last through droughts, and

just generally increasing resistance to pests and erosion.

What farmer wouldn't want that?

I mean, I want that I want that on my land.

And there's a bunch of other natural climate solutions for

agricultural lands that I think do have a more guaranteed

delivery in terms of carbon sequestration. I'm talking about

planting more trees on agricultural lands as riparian

buffers, or as hedgerows, or as silvopasture, or agroforestry,

right? Getting that woody biomass in there. That's going

to do a world of good in some places, in other places, just

doing leguminous cover crops to help reduce the amount of

nitrogen fertilizer that's applied to the land is a huge

benefit. Because a bunch of the nitrogen fertilizer that people

apply ends up in the atmosphere as nitrous oxide, which is a

greenhouse gas that's 300 times as potent as carbon dioxide. So

there is a whole suite of practices that are still

beneficial for the soil and for the farmer and for the climate.

Yeah, yeah, I think all of these things add up

to huge benefits in water quality and ecosystem health in

general. And, you know, hopefully still, food

production. And, you know, practically speaking some of

those regenerative practices —they might feel more within

reach, like winter cover cropping or reducing tillage to

the minimum. Others would mean a pretty complete reimagining of

how we plant and harvest at scale, and what those fields

look like, like what you just described. But with agricultural

systems and practices so deeply ingrained, you know, I really

think that farmers need help to try something new,

And podcasters of the world are here to provide

it.

Yeah, I mean, podcasters, and governments and

people who eat food, right?

Yeah, I am a podcast. I'm not a government.

But I am a person who eats food, I think we are all people who

eat. And so we all play some part in our food systems. One

thing I have learned farming is that every farm is different.

And so I guess the regenerative practices that are going to make

sense in one place will be different, depending on the

farm. What do you think the farmers in your area need,

Scott, in order to be able to embrace regenerative practices?

What are you seeing?

To me, I think the most critical thing is that

there has to be some type of economic reason to do it.

Like a carbon credit?

Well, I had hopes in the carbon credit...

until I did so much research on this, that it doesn't look like

that's going to be a viable solution. So it needs to be

something else. Even just incentives to start to get over

that initial hump in adoption would be a critical thing.

Realistically, it's going to have to be something that's

going to make economic sense to the farm. And as an example, in

the United States, where cover crops have really taken off is

where they had weeds that were resistant to the herbicides and

their costs were just getting out of control. When they were

able to integrate the cover crops in they're able to bring

their cost down. So whether you're farming at a small scale,

like a market garden, or up to thousands and thousands of

acres, it comes down to economics.

Yeah. And that's something that doesn't have to

come from the potentially greenwashing and, you know,

supposedly outcome based world of carbon offsets.

Yeah, there's things like crop insurance, low

interest loan programs, or just straight up cash incentives for

regenerative practices — that can help farmers close the gap

between doing good for their soil, making a living, and

putting food on all our tables. And I'm happy to say there's all

sorts of these programs starting to crop up.

You made a pun, Scott. That's delightful. That's

usually my job here. What kinds of regenerative practices are

you seeing being implemented in the prairies where you live?

Well, the huge shift over the last quite a few

decades has been going to no till or at least minimum

tillage. So plowing is very rare in the prairies. And very

similar to cover crops, it is showing similar patterns of

in that we do get more carbon in the upper

levels, but not as much in the deeper levels. However, just

because that happens, doesn't mean that it's not a good

practice for the farmer. They're seeing a lot of benefits from

it.

Yeah. So some incentivization is important.

Like stepping back from this question about carbon credits,

what occurs to me is that this whole question of how much

carbon is being sequestered, and how do we measure that, and how

permanent is that... it's a lot of complexity and noise that

we've kind of, like, shoved into what could otherwise be a very

simple conversation. Which is that we know that as a society,

we are emitting too much carbon. We should be making the people

that are emitting all that carbon pay. And then we should

be taking that money and incentivizing the practices that

we want to see on farms and elsewhere. And we don't

necessarily have to quantify that as stringently as we are,

if we're not counting on the slimmest of margins for climate

recovery. If we aren't trying to, you know, finely balance the

amount that we're emitting versus the amount that we're

sequestering, right? If the general idea is "emit less,

sequester more", then we need to reduce emission, which we we

definitely know how to do that. And then incentivize practices

that we know will eventually sequester carbon, even if we

don't know exactly how much or over what kind of timespan

that's going to happen. Do you know what I mean?

Yeah, I mean, you're saying like, not on a

gram by gram, or or ton by ton basis, but just to tax polluters

and use that to subsidize regenerative agriculture or

agriculture in general.

Yeah, I mean, farming is already heavily

subsidized. It's a question of shifting those subsidies to

actually support the kinds of practices that we want to see as

as a society, I think.

Totally. And, you know, while we do that, I

think we just need to get comfortable with the fact that

we're still learning. We're learning that there's a lot more

left to learn — about soil especially.

Yeah.

We know now that plowing doesn't make it rain,

that soil nutrients don't just spontaneously appear, and that

plants build their bodies from the air and not the ground.

Yeah.

But despite how far we've come, we're really

still just at the beginning of a soil science revolution. And

we're overturning notions that have been in place for decades,

you could say some recalcitrant ideas. At some level, we know

it's possible to put a lot of carbon back in the soil, because

it was there once. But now we also know that there's a lot of

work to be done before soil carbon can be the silver bullet

we've been hoping for.

But that doesn't mean we just wait around in the meantime. We

already have the tools we need to change how we farm and how we

eat, to rebuild the soil in the places where it's the most

degraded, and to do whatever we can to regrow a livable planet.

Okay, so if I understand you to correctly, the

regenerative practices that we've been discussing this whole

episode are good for the soil, they're good for farmers, and

they're very likely good for the climate, at least in the long

term. But we don't yet have the deep understanding of soil

processes required for us to confidently predict and quantify

those benefits, at least, enough to think that we can start

selling them to each other or to people who are going to use them

as an excuse to pollute, maybe. Is that right?

Yeah, that's about it.

And to close things out, I just wanted to

paraphrase a paper on overcoming the barriers to adoption of

cover cropping, since I think it also applies to all sorts of

regenerative practices. It's easy for individual farmers to

feel powerless to do what they think is right. But the

decisions of farmers are a form of embedded agency. One farmer

alone may not be able to do much, but just by doing it, they

will help another farmer to see a different way. Farm by farm,

field by field, those decisions aggregate — like grains of soil

— into watershed scale effects.

Future Ecologies is an independent production. In

this episode, you heard Scott Gillespie, Adam Huggins, and

myself, Mendel Skulski,

But we had lots and lots of help on the

background. From Kimberly Cornish, Nicole Tautges, Stephen

Shafer, Emily Oldfield, and Sean Smukler. Thanks.

Mix and sound design was by me, with music by

Patricia Wolf, Erik Tuttle, Thumbug, and Sunfish Moon Light.

A full list of credits and citations can be

found at futureecologies.net

where you'll also find the rest of our

episodes and a way to get in touch. We always love hearing

from you.

Even if it's hate mail?

I guess we'll find out. Thanks as ever to all

of our supporting listeners on Patreon. This show simply

wouldn't be possible without you. To be a part of our

incredible community, head to futureecologies.net/patrons

Thanks to the Sitka foundation for helping to

support our fourth season. And to everybody else, if you can't

help the show out with your money, you can still definitely

help out with your words. Share your favorite episode with

somebody you love, or just the next person that you meet — who

you might also find that you eventually love. We really

appreciate it.

Is that it?

That's it. Thanks for listening