Oh Yes, How Soil Works

There is maybe nothing that sounds more boring than hearing two people talk about soil, but friend, prepare to be amazed at the details of what makes this amazing substance the life blood of Earth itself!

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Episode Transcript

Speaker 1 (00:00):
Hey, everybody, it's Josh and Chuck your friends, and we
are here to tell you about our upcoming book that's
coming out this fall, the first ever Stuff you Should
Know book, Chuck. That's right. What's the cool, super cool
title we came up with. It's Stuff you Should Know colon,
an incomplete compendium of mostly interesting things. That's right, and

(00:20):
it's coming along so great. We're super excited, you guys.
The illustrations are amazing, and there's the look of the book.
It's all just it's exactly what we hoped it would be.
And we cannot wait for you to get your hands
on it. Yes, we can't. Um, and you don't have
to wait. Actually, well you do have to wait, but
you don't have to wait to order. You can go
preorder the book right now everywhere you get books, and

(00:42):
you will eventually get a special gift for preordering, which
we're working on right now. That's right, So check it
out soon coming this fall. Welcome to Stuff you Should Know,
a production of My Heart Radios How Stuff Works. Hey,
and welcome to the podcast. I'm Josh Clark and there's

(01:05):
Charles W. Chuck Brian over there, and this is Stuff
you Should know, the Dirty Dirt edition the best I
could come up with. And I even had days to
think of that, and that was it. Chuck, I'm sorry. Yeah,
this is a cool one. You know, we're into gardening,
so it's always nice to talk earth biology. Yes, agreed, Agreed,

(01:30):
And like I had a pretty I guess I thought
a dcent idea about this, but wait, did this article
open my eyes? Yeah? And this, you know, we covered sand,
and we covered compost, permaculture, perma culture, like we sort
of danced around soil. We danced in soil. Yea, our
toes are all dirty. But yeah, this is good to

(01:53):
finally check this one off the old list. Agreed. So
people are probably like, I don't know about this one.
I would hope that it's been, you know, long enough.
We've been at it long enough to just trust us
that if it sounds boring, we're gonna find something interesting
in it. And I dare say that that is going
to be the case with this one too, Chuck, I hope.
So to understand soil, we have to understand what soil is,

(02:18):
where it comes from, and soil is basically just worn
down rock, just like sand is. Right, I think we
talked about and like, are are we running out of sand?
Episode that like, rocks get weathered and kind of taken
down stream all the way to the sea and they
get gently um broken down over time into this very

(02:39):
nice little beach sand and washed up on shore, and
that's where sand comes from. Well, basically that is also
part of the same process for producing dirt as well.
It's just weathered rock that's broken down into different um
sizes that that are that that basically make up different
types of so oil. That's one the main structure of

(03:02):
it is basically just weathered rock of various sizes. Yeah,
so you can you know, wind can do that over time.
Water and obviously the combination of all these is where
you really get your money money's worth. You've got your win,
you've got your your water um. When you get weather
going on in your seasons, you get the freeze law cycle,

(03:23):
which is a really kind of speedier way. Once that
water gets in those little tiny fractures in the rock
and freezes and unfreezes and cracks, that will really speed
things up. And then you get a little help from
our our little tiny critters under under our feet. Yeah,

(03:43):
tiny critters of all shapes and sizes from like microbes
like bacteria and fun guy all the way up to
like prairie dogs and gophers. They're basically taking all this
stuff and mixing it together. But the stuff that they're
mixing together is so you've got the structure of the
soil from broken down rocks. But that's just one big component.

(04:03):
You have to have life living among it or else
it's not gonna do anything. It's just it's just dead.
There's nothing to it. So um part of the process
of forming soil is taking those little gritty pieces of
weathered rock and adding decomposing organic matter to them. And
that's where we finally start to get to what we

(04:25):
understand is soil. Yeah, because once you have that, it
can hold a little bit of moisture, and then that
means little plants can grow. Those little plants grow, they
eventually die. It's very sad for the plant and the
plant's family, but it happens to all of us. And
then those little plants that die, they decompose and they're

(04:46):
holding all that carbon dioxide and their little skinny stems
and leaves and body, and that carbon dioxide stays behind
and it's dissolved by water, and then that forms carbonic acid,
which isn't you know, if you want to throw a
body in a barrel, you don't want to use carbonic acid.
Now you're gonna get caught. Still, you're gonna get caught.

(05:08):
So it's not super strong, but it is strong enough
to help break down all those little rocks and everything
even more, and before you know it, you've got soil. Baby, Yeah,
you've got so So those decomposing all that decomposing organic
matter is full of like nutrients that kept the thing
alive while it was living. And then all those little

(05:29):
tiny animals and microbes that eat that stuff break it
down even further, which unlocks all of the nutrients and within,
and that means that plants can start to take them
up in its roots and use those nutrients to grow.
And so that's a big part of what soil is.
It's like a nice little substrate of medium for holding nutrients,

(05:53):
and then the whole thing is actually held together itself
even further by the roots that the plants that grow
in the soil spread out in stabilized too. So I
think one of the things we've just hit upon. One
of the reasons I love soil so much. It's harmonious
and um symbiotic, Like everything living in the soil almost

(06:15):
is involved in keeping everything else going and alive. It's
like part of a really beautiful, complete system. Yeah, and
that's why, you know, we always make a big deal
and science makes a big deal out of the disruption
of this and not just this process, but all earth processes.
One little tiny thing will lead to another little tiny thing,

(06:36):
and before you know it, you got you got issues
on your hands. Yeah, you do, for sure. You can't
let it get out of whack. Luckily, from what I found,
I started to get into um into like long care
and stuff like that happen at some point and it's
fun to me years ago and I was like, you
just wait, Yeah, it's true. It's true. And I've learned

(06:57):
not to flood my lawn with a quarter inch of
um of water. But um, the best fertilizer and aeration
that I found is just basically feeding microbes to your lawn.
Like you don't need to like go dig holes and
core plugs in your lawn, just if you add the
right kind of microbes to your lawn and all of

(07:18):
that will just kind of turn it into this healthy
soil beneath it on its own, which I just love
because it's just springing microbes onto the ground. What's more
beautiful than that. Well, we've got the opposite. We have
zero grass now. Basically, oh, I know, I know, you
just love to my face and that. But still no,
it just kept going more and more and it got

(07:38):
smaller and smaller, to the point where I was like,
why am I holding onto this tiny little patch of grass?
Why do I even have a weed whacker? At this point,
I know I've used a weed whaker in two years.
It's great, that's awesome. I got a big old honking
gas powered lawnmower even too. So I'm basically going the
exact toposite direction, is you do you have a writer now? No? No, No,

(08:00):
it's not that big. It's not that big. Yeah, it
runs on like the tier of baby deer. That's what
John Dear means. So, um, if you're talking soil, you
need to talk soil horizons, and you know, we'll get
to sort of the list of the different horizons here

(08:21):
in a few minutes. But soil horizons are these horizontal levels,
these striations that you know, if you look at like
if you go to any science center, they'll probably have
some kind of cool um piece of glass with a frame,
and you have soil in there, and they have little
lines drawn to mark these different soil horizons, because soil

(08:43):
is not all the same. From the the very top
of the top soil down three feet, it gets very different.
And you want space in there, you want air in there. Uh,
you want to have water to be able to travel
through there. I think they say if you want, like
really good soil should be about fifty just fifty percent
soil and then fifty just space for air and water. Yeah, exactly,

(09:08):
And then you want about half of those spaces to
be filled with water. So you've got about soil air pockets,
water filled pores. That's ideal for sure. And that's yeah.
And that the reason the way that you get those
those pores in those pockets and everything is because there's
different types of soil. There's different shapes of soil um,

(09:31):
and there's different sizes of soil. Like we said, you know,
there's sand, but there's also silt, and there's also and
get ready for your socks to be not clean off
your feet. There's also clay, which clay Whenever I think
of clay, it's like a big hunk of something that
I'm like having to dig through to plant a plant,
and it's enormous. But it turns out that clay is
actually the finest, uh smallest type of soil, and it's

(09:56):
so fine that it compacts together into these large aggregate
pieces of clay that we think of when we think
of clay, But that's actually huge, enormous chunks of extraordinarily
tiny pieces of dirt of soil that are so small
you can only see them with an electron microscope if
you want to look at them individually. Yeah, and clay

(10:17):
is important. It's all part of the mix that we'll
talk about here in a minute. But you know, if
you start off with just a barren rock landscape. There's
a very smart lady who who did this one? Was this?
I think that Grabster helps us out with this. This
is the Grabster um. He must have been interviewed doctor

(10:37):
Caitlin Hicks Priests, who's an assistant professor of biological sciences
at Dartmouth, and she said, you know, if you start
off We've seen it happen if you start off with
just bedrock in about a hundred years, you could probably
grow a tree there in the soil that you would
get seen it happen a million times hundred years. That's

(10:58):
all you need, right, And well, reason why it can
happen so fast is because some plants are early colonizers
and they can grow and just a little bit of
you know, soil, just a little bit of fine rock um,
and as long as there's like nutrients and water coming
to it, it's it's fine. It doesn't need a big
thing of like top soil or potting soil. It can

(11:19):
make do like that. And then once those plants start
to die, they start to decompose, and then it really
kicks off. So yeah, you can have like soil, a
couple of horizons of soil in a hundred years if
you're really boogian. Al Right, should we boogie on down
and take a break. Yeah, let's let's get her hands
dirty and we'll come back and we'll talk about these
horizons right after this, okay, chuck. Horizons. And speaking of horizons,

(12:10):
I think there was a Disney World ride or at
Epcot Center ride called Horizons or something like that, and
there was this group of people who infiltrated it they
figured out how to get basically behind the scenes and
would hang out there for like entire weekends and like
high during the regular hours and then just hang out
like they were part of the set um after hours.

(12:32):
After no it was about future life, like what life
was going to be like in the future. It's really cool.
But the upshot of all this is that they documented
the whole thing with pictures and it's somewhere on the internet.
I can't remember where, but I'm pretty sure it was
called Horizons. But it's a closed down Epcot ride where
a bunch of people documented it in the early nineties,

(12:52):
just with cool pictures of it. So check it out,
and that's probably why they closed it down. I don't
remember why they closed it down and what it became,
but think it's not nearly as cool. I never got
to write it, but seeing those pictures, maybe I wish
I'd been able to go. So here are a bunch
of the horizons. When if you're talking about pedology, which
is a study of soil, it's a bit of an

(13:13):
unfortunate name. Um, but we're gonna talk about horizons, not
the event horizon, not the Gateway to Hell itself, No
chaos and disorder of unparalleled horrible nous. Did you see that?
I loved it? Yeah, Yeah, it's pretty good. Huh. Yeah,
when's the last time you saw it? But when it
came out, I don't think I ever repeated that one.

(13:33):
I saw in the last couple of years, and it
holds up. I've been several times since it came out,
and it's it's a really genuinely good horror movie. Yeah.
I agree. I also saw Solaris too recently, and that's
a really great movie too. The Russian version of these,
I've still never seen the Russian version. I've seen the
Soderberg version. Yeah, it was good. I would recommend the Tarkovsky.

(13:54):
It's a bit of a grind, but worth it. Sure,
his movies are all worth it, but they're just you know,
they're tough. You don't if you're sleepy, don't try it. Okay, Okay,
it's like The Irishman, but Russian and in space and
good okay. Um. So the o horizon, these are some
of the different horizons. The horizon is that's like not

(14:18):
even top soil yet. It's the leaves that blow off
of trees and are sitting sort of on top that
counts as the horizon. They're basically the things that are
in the initial state of decomposition right on top of
the dirt. Yeah. Exactly underneath that then is the A horizon.
So this makes zero sense already because we went from
oh to A. None of this makes sense. The A

(14:39):
horizon um is what we would consider like top soil um.
It has most of the organic matter that's really begun
to decompose and break down into smaller and smaller bits,
and it's usually kind of dark in color. This is
where the highest concentration of minerals are and this is
also where you're going to find them the roots of
plants to because they really like those those minerals and nutrients. Yeah.

(15:03):
And by the way, when I said this makes no sense,
I'm sure and our scientists is gonna say, guys, it
makes perfect sense. And and here's why. Uh, you have
the E horizon next, which stands for alluviated horizon, and
that's where you've got this water draining down and those
minerals that you were talking about in the A horizon,

(15:24):
it's leaching those minerals and all that stuff out, and
you've got sort of this light colored soil in its wake. Right, Um,
that is not a common or I shouldn't say common,
it's you're not going to find that in every UM
soil sample that you take. Right. It's usually a product
of say, like um, a patch on like a hilltop

(15:47):
where it's it's like the dirt's in place, but all
the nutrients have been leached out over time. So anytime
you just dig with the shovel into some dirt, you're
not necessarily going to find an E horizon. Yeah, and
we should say that for all this stuff, it's all
going to vary according to where you are and what
kind of rain and flooding and uh and drainage that
you have and stuff like that. What's next, You got

(16:10):
the B horizon that's the subsoil, and this is where
you finally get down to some of the finer uh particles,
and you've got like a lot of silt, a lot
of clay. Uh. It's it's you're starting to get down
to the good stuff at this point. And all this
makes sense too if you think about it, like, um,
when the water, when rain water trickles down through the

(16:31):
soil and percolates, it's far easier for it to bring
with it smaller and smaller particles. So the further it travels,
the further or the smaller the particles you're gonna find
going down with it. So you've got your bigger particles,
your looser, coarse or bigger top soil. Then you've got
the subsoil, which is a little tighter together, and then

(16:53):
in that um in the b horizon, in the subsoil,
you've got compacted. That's where you're gonna hit like your
lay layer, because again, clay's made up of those tiniest
little particles that have been brought all the way down
as far as it can go with the water that's percolated.
That's right, And it's much more stable than top soil
as well. For sure, sometimes it's too stable and like

(17:15):
water and roots can't really penetrate it. Yes, or shovels
it can be. It can be a problem child as
far as soiled soil horizons. You know my story when
I was trying to dig my fence post holes for
my privacy fence years ago, was I rented a two
man auger, a two person auger, and it just spun,

(17:38):
it just it compacted the clay even more. It did
not break it up at all. It's spun it like
a potter's wheel. Nice, did you go give me some clay?
Oh wait, that was bad? Did you get it? That
was a pottery joke, but it tied into your problem.
That was maybe the smartest joke I've ever made in
my life. Well, no, wonder I didn't get it. Uh

(18:00):
And and I think I mentioned this on the show before.
If you if you do have that kind of problem,
if you're going to plant and you have really tough
clay that you're trying to get through, or rock for
that matter, get a San Angelo tool, which is that
big heavy spike um that you see at the hardware
store that's, oh yeah, six ft long, has a pointy

(18:22):
end on one side and a flathead on the other
in ways like you know, twenty pounds or something. Yeah,
I never knew what they were called. They look like
sharp pointing lightning rods basically, right. Yeah, I mean you
just it's backbreaking. But if you voice that thing into
the ground as hard as you can and just wiggle
it back and forth a million times, and then you're
gonna be able to well, you're gonna be able to
break up anything. Basically, and then you hit it with

(18:44):
the auger or post hole diggers. Uh no, I mean
the augur was useless at that point. You just loosen
and use a shovel. Did you get your money back
and say this augur is worth nothing? No, because they
would say welcome to Georgia. Thing. That's the slogan, and
not all over Georgia, but particularly where we are, like

(19:04):
up in the mountains and stuff it can get it can.
The soil is very rich and very uh a pliable. Yeah, yeah,
for good stuff as long as you don't hit the
granite underneath, which can happen. Yeah, as a matter of fact,
because those those pieces of granite that you hit as
you get closer and closer to the Appalachians further north
and Georgia, that's bedrock that's like the outermost rock of

(19:28):
the Earth's crust, right, so you're actually touching the earth.
It's almost like the soil that builds up on top
of the bedrock is I don't know, dander maybe, And
the bedrock is really the Earth's outer skin. So you're
touching the Earth's skin when you're touching bedrock, which can
which can poke through the ground every once in a
while is what we call rock outcroppings. Yeah, and so

(19:51):
as far as the horizon levels go just above the bedrock,
I don't think we mentioned the sea horizon that is
also rock. But that's rock that um his weather down
some but didn't quite make it to soil level, right,
because remember, some plants can come in and colonize that
rock and pretty quickly start building up soil. And if

(20:11):
that's that rock beneath isn't exposed to that weathering process
from wind and freeze, thaw and all that stuff, it's
never gonna get broken down, right, It's just gonna be
hard on the old auger uh, and then the bedrock.
And then you've got what's called hard pan and these
are mineral deposits that I mean, this stuff, I don't know.

(20:33):
I guess it's harder than bedrock. It just sounds like
nothing will will grow and there's no chance for anything
to permeate it. Yeah, and hard pan the is not
under bedrock bedrocks as low as it gets before you
like that's the Earth's crust. Hard pan is just kind
of I think he's just kind of tossed that on
where it's like this is this is another. It's like
an e horizon, like an alluviated horizon. You're not gonna

(20:54):
find it everywhere. When you do, you'll know it because
it's very hard to dig through and there can be
streaks of it within another you know, soil system um
of different horizon layers, uh, and you just don't want
anything to do with that. Neither do plants either. It's
basically impermeable as far as water and roots and shovels
go no good. Another term that I think is really

(21:18):
just cute is parent material, And that doesn't mean whether
or not you would be a good papa or a
good mama to a human child. Parent material is the
type of rock that you started out with, the type
of mineral that you started out with millions of years
ago that was weathered down there to create what kind

(21:39):
of soil you've got, And depending on where you live
and what was there hundreds of thousands or millions of
years before you, you're gonna have much different kind of
soil than uh, maybe another place in the world. Yeah,
Like if it started out as igneous rock from a
lava flow, that's going to be different kind of it's
going to produce a different soil from you know, sedimentary

(22:00):
that was weathered down from a granite outcropping by a river.
It's just different soil. But it can also come about
in different ways, like like that rock outcropping that was
worn down by a river and just kind of sunk
further and further into the ground and was built up
a top of it. Soil layers were that would be
called residual, where it's developed in place. There's also transported

(22:21):
where it could be moved by like ice, like a
glacier pushing soil from one place to another. Um and
then there's also cumulose, which is basically like peat, where
organic materials basically suspended in in suspended animation by water.
It's it's prevented from full decomposition. That's right. Those are

(22:41):
the kinds of parents that soil can have. So let's
talk about the soil texture triangle. Okay, this is where
it gets pretty cool because if you're talking soil and
and I think people should start using the word soil
more than dirt because I just think it's more evocative
of what you're really talking about. I think it's kind

(23:04):
of reductive. I saw a dude who is like a
soil sciences professor explain that to him, at least dirt
is like dead soil. Soil is like living, breathing, you know,
it's almost like a It's a symbiotic organism formed by
the by all these different other bits of life working together,

(23:25):
whereas dirts is like dead stuff that maybe will become
soil one day if it behaves itself right, if it
if it plays his cards right. So this texture triangle,
if you're talking soil is a mixture, and this is
all soil of uh, sand, silt and clay sand. Well,
it's a really good podcast episode on it. I think

(23:45):
we did um that is the most course, which is
funny to think about because sand seems super super fine,
but when compared to silt, I think sand is two
to point zero five millimeters in diameter compared to silt,
which is point o five to point o two. And then,
like you mentioned earlier, it's hard to wrap your head around,

(24:07):
but clay is a really really fine kind of soil
point o o two millimeters in diameter. And you've got
to get that microscope out if you want to take
a look at it. Yeah, and because the different sizes
when they're put up against one another. If you've got
a bunch of sand, the pores in between the grains
of sand are going to be really big, which is

(24:27):
why beaches don't have a lot of plant life growing
on because water just drains right through them and it's
very difficult to keep organic matter suspended within it. Right silt,
it gets a little easier, a lot easier because the
from what I saw, the pores in between silts are
basically ideal. They're just big enough that they drain really well,

(24:48):
but they also can hold some water. And then clay
because the pieces are so close together, the pores between
them are so small that they hold a lot of
water and they they basically sealed off the waters escape.
So clay can either prevent water from coming in or
it can hold it in and and drown things. Either way,
it's not necessarily very good for roots. Super compacted clay. Yeah,

(25:12):
you want a nice mix, and it doesn't all have
to you know, it depends on what you want to
do and what you're working with, But it doesn't have
to be the exact same mix either. Um. I'm sure
there are ideal versions, but uh, depending on where you are,
you can only do so much with your soil, Like,
you can't make an entire farm uh something that it's not.
You can augment it and help it out, but you're

(25:33):
kind of working with what you got to a certain degree. Um.
I think one of the cool things from this research
was that you know, if you see a farmer in
a movie bend down, and that the scene that's in
every movie about a farmer when they grab that soil
in their hand and they look at it and twist
it between their fingers and then let it fall gently
out of their hand onto the ground. Not only does

(25:56):
that make for a nice movie moment, but that's real
deal stuff. If you're a pro farmer or a soil scientist,
you can tell exactly what's going on with that soil
by how it clumps in your hand, how it moves
in your hand, how it holds together, what shape it is. Uh.
So it's not just a sort of a BS thing
you see in movies. No, you can also run a

(26:17):
lab test to figure out what the ratios are. Right. Yeah, hey,
college boy, you need to get yourself a farmer um
with hands either way? Right, But if you if you, um,
you there is an ideal combination between it depending on
what you're trying to do. For sure, Um, you don't
want it to clay, you don't want it too sandy,

(26:39):
you don't want it although I don't know, I think
you do kind of want everything to be kind of silty.
But um, where they interact is going to going to
describe what kind of dirt you're dealing with. And there
are things you can do too. There's a reason for
understanding that because you can say, oh, if I add this,
if I if I bury a bunch of grass clippings,
is going to turn this clay into more silt um

(27:01):
and everything's going to just jump for joy from that
point on. Yeah, And if you're a home gardener, uh,
you can certainly manipulate your yard or any potted soil
that you have. You can amend all that stuff until
you get exactly what you need. Um. And then once
you have it in a good place, there's upkeep. But
it's it's not like you just have to do it once,

(27:23):
but you have to do it once really really well
and then just sort of keep that good mix going. Yeah,
and then you can just go get one of these
things that you you hook onto the end of your
hose and spray it once in a while with some
microbes and sit back and watch everything that's exactly right
made out of deer hide. O. God, it doesn't It

(27:47):
doesn't burn very well and it's kind of noxious smelling,
but it really makes a point, you know. I know
we mentioned regularly and I want to say terraforming and
other episodes mm, but this Sometimes people say this as
a word for soil, but it's really much more than that.

(28:07):
It's kind of like anything on top of the bedrock
basically can be called regular, and that's not And we
mentioned terraforming because if you talk about the Moon or Mars,
you talk about regular as well, and whether or not
we could grow stuff there, which apparently we could, right. Um, yeah,
if we added the right nutrients and water, it would

(28:30):
it would hold, which is essentially all it is. At
that point, It's like what that that soil science? This
guy was saying that it's um, it's a it's it's dirt,
not soil. It's dirt because it doesn't have anything living.
But you can add that stuff to it as needed, right,
make Mars great again? Oh God? So you want to

(28:52):
talk about the carbon cycle? Yeah, what is I mean?
Does carbon have anything to do with the Earth. No,
has nothing at all to do with it. Um. But
actually it has quite a bit to do with it, right,
So so um carbon is essentially the building block for life,
and there's a big cycle of carbon moving through the environment.

(29:14):
There's a lot of it in the atmosphere in the
form of c O two, and the atmosphere itself forms
what's known as a carbon sink, which, if you haven't
been paying attention in the last few decades, one of
the reasons that climate change is happening is because we've
been um overwhelming that carbon sink in the atmosphere by
burning fossil fuels and releasing a lot of carbon dioxide

(29:36):
that have been sequestered in the ground, which leads us
to this point that plants and soil help lock carbon in,
so that in addition to the atmosphere being a carbon sink,
soil is also a really major carbon sink too. Yeah,
and you're thinking about agreeing with that or not. No, no, no,

(29:56):
I totally agree with it. But I mean it's kind
of like when you know, Amazon rainforest caught on fire. Uh,
that's it's almost like you're getting a double whammy there,
Like even just cutting the Amazon down to to grow
crops there too. Like you're you're, you're creating quite a
bit of harm even without burning it down, because all

(30:19):
those trees are really good at sequestering carbon dioxide from
the air and creating a carbon sink in the ground.
But then also it will find out later when you
till the ground, a lot of that carbon that's been
trapped under there, and we'll stay that way for a
thousand or so years, is suddenly released just by tilling it.
So there's basically the main point I would like everybody

(30:42):
to take away from this entire episode, maybe our entire podcast, Chuck,
is leave the rainforests alone. Just stop messing with the rainforest,
because it's really screwing things up in ways that we
are yet to fully realize. Yeah, agreed, that was my soapbox.
That's you and Don Henley Man arm in arm Yes,

(31:05):
he's a big rainforest guy. You know. Well we're always
chatting it up about the rainforest. I got a lot
of my ideas from him, you know, thanks to stuff
you should know. Listener Clayton Jaynes, who was a guitar Well,
I'm not gonna say exactly what he does, but he
he worked on this last tour for the Eagles and
invited Emily and I down before the show. I got

(31:28):
to like touch Don Henley's drum kit and Joe Walsh's guitars.
I remember you saying that, and Joe amazing because he
happened to be standing next to his guitars at the
same time. It's pretty cool man. And you're like, I'm sorry,
I'm sorry. He's like, it's okay. Life's been good to
me so far. Uh, something's wrong with me today, man,
something's bad wrong, all right. So let's talk about carbon dioxide,

(31:52):
um for a second here, because plants draw that in
from the atmosphere and then eventually they're going to break
that down because as uh think, you know, photosynthesis happens
and they use that carbon to build up that plant.
We're talking about the roots, the leaves, the stems. Carbon
plays a big part in that. But eventually, like I
said earlier, that plant is gonna die or leaves just

(32:14):
fall from a tree or whatever, and that carbon is
locked inside that leaf or that dead plant on the
ground that you stepped on right exactly. So, Um, what's
great about this is that plant used that carbon and
when it died, it died with that carbon and it
was locked in like you said, but it's able to
be used by other plants that come along, which is

(32:36):
part of that whole like beautiful system that just works
so intricately well because to unlock that carbon you have,
that's where all that life that lives in the soil
comes along and uh becomes extra extremely important because they
break that stuff down and decompose it. Depending on whether
you're talking about bugs that chew up leaf litter um

(32:59):
into smaller, smaller pieces, which makes it easier for microbes
to break down more quickly. Um, the microbes themselves get eaten,
and that carbon that was locked in the plant is
suddenly unlocked and available in the soil for other plants
to take up through their roots and build their own
structures and use for photosynthesis too. It's it's the circle

(33:20):
of life, right, or it doesn't use at all, and
some of that carbon is then released back into the atmosphere. Uh,
then we get to the humus. And I think we
might have talked about this. Surely we did in composting, Yes,
we definitely, maybe we did. One of earthworms, right, yea,
they talked about in earthworms. We talked about um in permaculture.

(33:44):
I believe we may have also talked about it in
desertification and droughts. Right, that was a good one. That
was good. So humist is that? Um, it's basically, if
you'd compost something years later, you're gonna finally get down

(34:05):
to humus. It's what's left over after all that snacking
is done. Uh. And it's you know, if you have
a home composter, I don't think that you have humus
after a couple of months of doing a really good
job composting, because it takes like many years to become humans. Yeah. Um,
And like it's just a very small percentage of the

(34:26):
stuff you compost will break down into humus because apparently
the precursor of humans is proteins, and most compost is
made up of carbohydrates, plant materials, or carbs, right, Um, yeah,
that's right. Um. So when it breaks down, this humus
is it's almost like a Some soil scienists apparently consider

(34:46):
humus a third state of life where it's not just dead,
it's very dead. Decomposition is not really happening anymore. But
there's a lot of minerals kind of locked in their
inorganic materials. UM. But the thing is you want humus.
The more humis you have, the more lively in life,
affirming your soil is UM. It's like eat, prey and

(35:08):
love down there, you know, because humis forms an ideal
house for all that other life to live in. It's like,
exactly what is needed for the other organisms that make
soil alive in this um symbiotic network. That's what they want,
is humist and and it's it's extraordinarily important stuff. But

(35:31):
we don't fully understand why it doesn't necessarily keep breaking
down after a point. Yeah, it's it's very dark, it's
like black. Basically, it's very spongy. UM. It has great
water retention. It can hold nine of its weight and water. Uh.
And it's sort of like the bond. It's like the
cement that helps. You know, when you clump that soil

(35:52):
together in your hand and it stays together, you can
thank humus for that. Yeah, as a matter of fact,
you should thank humans out loud when you can. When
you squeeze soil in your hand, you totally should thank
you humus. So it's like you said, like humust holds
the stuff together, but it also creates those air pockets

(36:13):
or those gaps that are so important in um in
healthy soil, right, it keeps things from getting sticking too
close together. Yet it also keeps it in aggregations or aggregates, right,
So it's really weird if you really stop and think
about it. It holds things together, but not too much together.
It kind of holds them together at just the right
distance so that you have that ideal mixture of soil

(36:37):
um gaps. And then those gaps are you know, can
hold water moisture. Yeah, and you've got to have that
that right mix, because too much sand is not able
to hold any water. Like you mentioned, if you go
to the beach, you can just see this in action. Um,
you've got to have some of that clay though, because
that's the smallest one and it's uh those little micropores.

(37:02):
They're gonna as what's called capillary action. That's uh adhesion
and surface tension mixed together in a bag basically, and
that's super super strong. And if you have clay in
your soil, it's gonna hold that water and it'll even
draw water up from the water table and say here
you go go out and feed. Yeah, I saw yet
another soil sciences professor talk about capillary action, and he

(37:26):
surprised me because he showed that um sand has the
least amount of capillary action. There's some you know how
like when you're digging into the sand, right before you
get to the to the water beneath it, it's wet.
That's because the sand has still been wicking some water
up through those gaps. Um And But rather than clay

(37:46):
being the the strongest with capillary action or the best
for soil, I should say, um, it's actually silt. He
had like three tubes silt, sand and clay, all next
to each other, and the silt one just rocked the
other two for how far it had wicked water up
this tube. So apparently that's the ideal. Silt is just
as good as it gets. Is from what I can tell,

(38:08):
it's your own team silt. I am super team silt
from now and forever. All right, I think we should
take another break perhaps, and we'll talk about what all's
living down there in that soil and what this all
has to do with climate change right after this, all right,

(38:51):
So we talked about early on things living in the soil. UM.
I know it's It's easy to think about um, little
mike robes and bacteria and things in soil because we
know it's just rife with that stuff. But you can't
ignore the big things too. There are little moles that
live in the soil, their prairie dogs, their lizards, there
are snakes, um, all this stuff. Every like kind of

(39:15):
larger animal disrupts the soil. But that's a good word
in this case. You want that soil disrupted because it's
redistributing nutrients. It's you know, you want them peeing and
pooping in that stuff and mixing all that stuff in.
And you've got this sort of larger, small to larger
animal system acting as a little composters along the way. Yeah,

(39:37):
and and they're actually also mechanically mixing the soil. Like,
you don't want your soil just be big, medium small.
You want it to be fairly mixed together, because big
is just to the the the gaps between are too
big and small the gaps between or two small, you
want them mixed well. And so like an earthworm burrowing
actually is mixing the the earth together. Gophers apparent mixed

(40:00):
together something like eighteen hundred cubic meters per square kilometer
every year. That's a tremendous amount of soil mixing in there.
It's they're doing it for free, basically. Yeah, and that's
when they're getting along. Like you want to really mix
up some soil, you get a gopher rumble, Sure happening.
You can get ugly, but your soil is gonna be

(40:22):
super mixed afterwards. Oh man, it's gonna be fantastic. Plus
you can roll cigars out of their hides, the hide
of the loser. Oh boy, you've also got spiders. You've
got a little scorpions. Um, you've got centipedes, you got millipedes,
you got termites, you have uh roaches. Unfortunately, I think

(40:43):
right here it says in a sample of one square
foot of two inch soil in the forest, two hundred
species of mites alone. Yeah, that pretty impressive. I've got
one even better than that. Right, let's go down in
order a magnitude or so. Oh, I know where you're headed. So,
the microbes in the soil are so abundant and so prevalent.

(41:04):
Apparently a teaspoon of soil has more microobs in it.
Microbes is another pronunciation, um than there are than there
are people on Earth and one teaspoon of soil, right,
and all these little microbes, their bacteria, there's viruses, there's um,
there's fungi. All these my all this microbial life are

(41:27):
like the last the last layer of decomposition. But they
do even a lot more than just decompose dying things. Um.
There's there's a function of fungus that we're just now
starting to wrap our heads around called um micro riz a,
which is a symbiotic relationship. So so soil itself is

(41:50):
a symbiotic relationship. This is a symbiotic relationship within the
symbiotic relationship where fungus basically says, hey, roots, I like
what you're doing there above me. Um, I'm gonna hang
out around you and maybe grow my own system of
roots out of fungus me that connects to your roots
but also goes through the ground and connects to other

(42:10):
roots too. And I'm going to take up, you know,
nutrients from the soil and help you accept them into
your roots, maybe bring you some water here there, and
I'm gonna let you communicate with other plants through your roots,
through me to the roots of the other plant too.
So it's like if you look at um. A micro
is a if you pull up like a plant, it

(42:33):
has like this thin, almost long like film around it.
That's the fungus. That's it's like a root system around
the roots system made up of fungus. And we're just
starting to understand this and it's just beautiful to know
that it exists like that. It's the fungus amongus. It is,
And there's actually humongous fungus amongus, isn't there. Yeah, so, um,

(42:55):
what you were talking about is a mutualist. They're kind
of three kinds of fungus. And I love that they
call it a mutualist. It's a great name for that. Uh,
the symbiotic relationship. There's the name for like a neo folk. Sure, yeah,
why not get it? Get a tweed vest and a
jaw harp and have have a good time. I just

(43:16):
got a jaw harp in the mail. By the way,
is that the one that has the shoulder mountains? No,
the jaw harp is the twangy thing you put in
your mouth. It's like to have it here. If you
want me to go get it, I would love you
to go get it. I think we'll wait. The fungus
that eats decaying matter is called a sacrifice. Then you've
got your mutualist, and then you've got an actual parasitic fungus.

(43:38):
Those are the jerks of the of the forest world.
But you were talking about humongus fungus. I know, I
feel like we've talked about this at some point. Pando.
Was it in Pando? Okay? I thought it might be
um in mal Here National Forest. Um there is something
called Janet D and a big network of fung i

(44:00):
is a genet and Janet D is the humongous fungus
is considered the largest living individual on Earth two thousand
acres worth. Apparently it's all connected. Yeah, and it was not.
It's the biggest by area. I think in Panda is
the biggest by mass. Like if you wade Pando, it
would weigh more like this one was still covers a

(44:22):
lot bigger area, but it's just one big, single organism
and it is it's underground and it sucks onto um
onto roots. And actually they found it because there was
a bunch of dead trees and they're like, what's going
on here? And they discovered that it was this one
a m A stoy a fungus that um was killing
off trees because it can be one of those jerk kinds.

(44:45):
The parasitic fungus, what are they called, just parasitic fungus.
There's not a great name for them. Uh, No, parasitic fungus.
But the ones that so they live in the soil.
No one likes them. They're they're they're considered jerks, like
you said, um, the ones that everybody likes. So the
mutualists are the sacrifices which eat decaying matter and then

(45:06):
sometimes they eat one another and all this stuff just
the I don't want to say the point of it,
because who knows if there even is a point. But
if there is a point, it is that UM that
nutrients that get used by living things and locked into
the living things when they die get unlocked so that
other things can use them. All right, So do you

(45:28):
want to talk about the nitrogen cycle? Yeah, because I
mean that's another thing they can get locked and unlocked
thanks to these organisms in their symbiosis. UM nitrogen is
extremely important to plants. They used to make chlorophyll, They
use it to make some of their UM proteins and structures. UM.
But it's and there's it's super abundant in the atmosphere,

(45:49):
in the air. But now plants are really good at
unlocking it um actually, which is right, which is why
you need some plants called nitrogen fixers to come along.
And I think legums are a really good example of
this in like alf alpha peanuts, you know those things
um and they can take it out of the air

(46:10):
and turn it into a usable form. And they actually
do that, I saw, not on their own accord. They
have to become infected by a bacteria called rhizobium, And
it's actually the infection from ryriezobium that alters the plant
to make it so that it can take nitrogen out
of the air and deposited in its roots for storage. Yeah,

(46:30):
most plants can't do that. They have to draw it
from the soil around them. And you know, we we
mentioned the balance and nature that we always are seeking
that homeostasis, which you would like is a balance between
these nitrogen fixers and dead plants adding nitrogen into the
soil and then also those plants that are drawing that
soil out, like you want that all to sort of

(46:52):
balance out together, right exactly, And again it's because there's
help from bacteria helping fix nitrogen and nodules on the
on the roots that other plants can come along and use,
and to fix what's called a fixed form, so it's
fixed nitrogen. Like you can have, UM, say a glass
of sea water, and you're really thirsty, but you can't
drink it because it's not in a usable form, even

(47:14):
though it's still water. But if you run it through
a reverse osmosis filter and desalinate it, now it's usable water.
So you can think of nitrogen fixing is like the
Earth's version of reverse osmosis for nitrogen converting into a
usable form for plants. The thing is that we kind
of talked about it before UM and you just hit

(47:35):
upon it. There's like a natural cycle and natural process
to all this, which things like agriculture, especially UM has
really kind of disrupted. And even after the research that's
been produced over time, we're still we're either being like
willfully ignorant or still figuring it out, or people are

(47:57):
still trying to get the word out. I don't know
what the issue is UM. If it's just too expensive
to do it right, I don't know. I'll have to
go back and listen to our permaculture episode again. But
one of the ways, like you said, that we we
disrupt this natural cycle, or the nitrogen cycle in particular,
is by not um planting things like cover plants that
are nitrogen fixers to replenish the soil. Instead, we use

(48:20):
factory made fertilizer, which is just fixed nitrogen itself UM
to replenish the soil, which is much harsher and can
have um all sorts of uh cascading negative effects on
the surrounding environment as well. Yeah, because if you're doing
a major agriculture job and you're pulling that nitrogen out,

(48:41):
you've got to artificially put it back in. And that's
all fertilizer is, because you're feeding that manure or whatever
fertilizer you're using. Manure has a lot of nitrogen, so
that's why it's used as a fertilizer, but you're just
pumping it back into the soil. Uh. There's a great
documentary that's called I Think Big Little Farm maybe not

(49:04):
about this couple who you know, dropped out and started
their own farm, but started a farm that they wanted
to do right and to be and balance like naturally
with itself. It's really good and daunting and inspiring all
at once. It's it's cool. It sounds a bit like um,
the movie All of Me, where Lily Tomlin takes over

(49:27):
Steve Martin's body and they have to learn to coexist
together kind of harmoniously. And I think they do at
the end if I remember correctly. It's not big little farm,
Biggest The biggest little farm is what it is in Texas.
Uh No, that's a Burt Reynolds movie, right, Okay, And
you said this is a documentary Biggest Little Farm. It's
really good. You should check it out. Okay, Um, well,

(49:50):
people should check out All of Me too, if you
ask me. Um. The thing is, Chuck is when you're
talking about nitrogen fixing and say like, okay, well, farmers
should just grow alfalfa and then whatever, say, if you
harvest corn or something like that, you till it into
the grass. Whatever is left over after you've harvested the corn,
you till it into the ground. I mean, and that

(50:10):
buried stuff actually provides a lot of food for all
of those microbial life and um, earthworms and all that stuff.
So they actually leave the roots of your plants alone.
That's great, but even doing that requires more care than
you would think, because if we go back to humus, remember,
humus is a really great way to lock in carbon
for hundreds or thousands of years. But we're finding that

(50:34):
it can be fairly easily disturbed by agricultural practices like tilling,
and that once you disturb it, all of a sudden,
it's like, oh, yeah, well I'm done, I'm out. If
you're not gonna appreciate me, I'm not gonna hold onto
your carbon anymore, and it starts to release it. So
we're finding that agricultural practices like um tilling are actually
having a contribution and impact to climate change as well. Yeah,

(50:57):
and it's not uh and I think this came from
the same interview with the professor assistant professor Um. She's saying,
it's not like it's the same as the burning of
fossil fuels. UM. There was an estimate is that soils
have lost a hundred and twenty uh pg. What does
that stand for pedigrams of carbon since we've been since

(51:21):
the dawn of agriculture basically, and that since seventeen fifty one,
uh fossil fuel burning has had a cumulative total over
four hundred pedigram so it's not on par but it is,
you know, something to think about, and especially when you're
talking about perma frost, and you know that's why we

(51:43):
talk about when UH climate change is sort of like
this vicious cycle where things are heating up and then
UH ice caps are melting, and when that stuff melts,
that's releasing this perma frost. Soil that has been stored
you know, stored carbon for thousands and thousands of years,
all of a sudden released back up into the atmosphere. Yeah. Yeah,

(52:05):
because humus is most stable as a carbon sink when
it's cold. So if it's so cold that it's been
frozen for years, um, it's very stable. But yeah, as
climate change warms it up, that starts to get released,
and that is a problem. I mean, yes, a hundred
and twenty pedigrams over the last years. It doesn't seem

(52:27):
like much, but we're getting to the point now where
every little bit counts, and I think as part of
the Paris Climate Agreement, you can um count your carbon sinks,
like the kind of soil you have against your output
to to show whatever reduction you're working on. So it
does count, it is taken into account. It's just nothing
like fossil fuels, but it is an important component, it

(52:49):
seems like. Yeah, So basically, you know, that's what they
did in the biggest Little farm is get back to
basics of the dawn of agriculture when they practice really
sound soil management. Um for the most part, tilling you know,
only what needs to be tilled. Don't go super deeper,
super wide if you don't need to that ground cover

(53:11):
that you were talking about, shades that soil, and don't burn.
And this is one of the big problems with Big
agg is burning plant waste. Yeah, you don't want to
do that. You want to bury that stuff and put
it back into the earth. Put it back into the earth, everybody,
because the life down there wants It's right. That's the
slogan for this one. Okay, agreed. So get out there

(53:33):
and get your hands dirty and go feel the soil
and remember to say thank you Humus as you let
it move through your fingers. Okay, okay, everybody. And in
the meantime, I think, chuck, it's a listener mail. Yeah,
this is uh from a teacher. I think is this
a teacher? Yes, biology teacher. Appropriately, Hey, guys, just listen

(53:58):
to the episode of arcolepsy. Thought it would clear up
a confusion about the difference between a disease and a disorder.
As a high school biology teacher, I had to explain
the difference every year. The difference is subtle, but there
is a simple way to remember. A disease is caused
by a path pathogen like a virus or bacteria. A
disorder is a malfuncttion malfunction due to genetics, trauma, chemical toxicity,

(54:22):
or other non living factor. The lines can become blurred
a bit because the disorder can be triggered by a disease.
Some cancers are triggered by viruses. May be a clearer example,
as HIV AIDS. A person can be HIV positive and
if the viral disease is discovered in time and treated,
they may never succumb to the disorder that is AIDS,
which sets in when the infected person's immune system has

(54:45):
been effectively eliminated. Hope this helps the issue. Thanks again,
keep up the good work. And that is from Rich
Brusk from Manhattan, Kansas. That's a man of hat A, Kansas.
That's right. That is a world class biolo g teacher.
Chuck totally what was his last name, Brusque with a B. Sure,

(55:08):
Thanks Mr Brusk from Manahatta, Kansas, UM. We appreciate that,
and we appreciate you being a biology teacher in a
world class one at that. If you want to show
off what a world class person you are, you can
get in touch with this too, like Mr Bruss did. Uh,
you can send us an email send it off to
Stuff podcast at iHeart radio dot com. Stuff you Should

(55:31):
Know is a production of iHeart Radios How Stuff Works.
For more podcasts for my heart Radio, visit the iHeart
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