October 22, 2025 • 11 mins
We break down soil orders like a field guide, linking what you see in a soil profile to how soils behave and how to manage them. From prairie-black mollisols to red-dirt ultisols, we share traits, regions, and practical tips growers can use today.
• soil taxonomy as a practical framework
• mollisols and their dark, organic-rich surface
• vertisols with shrink–swell clays and timing risks
• spodosols in conifer forests with leached E horizons
• alfisols, clay accumulation, and hardpan concerns
• histosols in peat bogs with high organic matter
• ultisols in the South, iron oxides, and low-activity clays
• regional patterns across the Upper Midwest to the Southeast
• field tips for digging, observing, and managing horizons
Tune in next time for a Tiny Byte of knowledge from GK Technology, where we have a map and an app for that!
https://gktechinc.com/
https://gktechinc.com/
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Jodi (00:00):
And now it's time for a Tiny Byte of knowledge.
Sarah (00:13):
Hey Jodi do you remember?
Oh, sometime last year we did atiny bite episode on what a
soil series is.
Remember how when you read whata soil series is, you can read
all about the characteristics ofthat soil and everything that's
in that.
I think it's important for usto realize that there is a
definite classification system.
(00:34):
And one of the things withinthat system has to do with the
broad base brush stroke of howwe group together different
soils and what theircharacteristics are that make
them act similarly to eachother.
Jodi (00:49):
Are you saying that there is a way of breaking down soils
at a larger, more general waythan just soil series?
Sarah (01:00):
Absolutely.
There's a whole taxonomy systemthat we've got in the United
States of America to help usthink about the ways that soil
are similar to each other anddifferent from each other and
different ways that we classifythem.
So just like we think aboutgrouping together animals and
(01:20):
animal taxonomy, we also canthink about soils in that manner
as well.
So let me let me help you putthis frame of reference
together.
So when you think aboutanimals, you might think about
animals being mammals orreptiles or amphibians or birds.
They're all animals, butthey're very different from each
(01:42):
other.
And I think we all know,especially in agriculture, that
soil is all soil, but it can bevery different.
You know, we've got soil outthere that's extremely sandy,
we've got soil out there that'sextremely clay, we've got soil
that's in the desert, we've gotsoil that's in the Arctic.
And we actually have a way ofclassifying those from a broad
(02:04):
standpoint into what we callsoil orders.
Well, let's go through and namethem all and let's see if we
get them.
Here we go.
Ready?
Entisols and septosols,vertisols, mollusols, olifosols,
aridosols, spotosols, altosols,oxisols, histosols, andosols,
(02:25):
and gelosols.
Woo! That's a lot.
That's a lot of cells.
They all have differentmeanings behind them.
And we can all we can thinkabout like what these things are
most common.
So, for example, a mollusol.
Jodi, what's a mollusol?
Jodi (02:45):
Mollusol is your basic prairie soil.
It is a soil that when the waythat you think about them is
that they have a really darksoil or like a really dark color
at the top.
That is an artifact of havinggrown up under grass-like
vegetation for a very longperiod of time.
That black is organic matter.
And typically they are grown inclimates that are, you know,
(03:07):
kind of more moderate.
They're not arid, they're notreally humid, but they're kind
of in the areas between forestedareas and arid desert areas.
So, like for us in the UnitedStates, the Great Plain region,
and also the Midwest regionwhere there were grasslands.
Those would be areas that havethese soils that are mollusols.
Sarah (03:27):
And in North Dakota and Western Minnesota, we've got a
lot of mollusols.
So make up about 7% of theworld's ice-free land.
So if it's all right, I'm gonnatalk about my favorite soil
order, which is vertasols.
Vertisols have high con havehigh clay content of highly
(03:52):
reactive clays, which meansthere's a lot of shrink and
swell to them.
Um they crack open.
So think about like when youget a drought and you lose your
wrench down the crack in thesoil.
That's that's that type ofsoil.
Okay.
It's a vertisol.
So in North Dakota, um,Minnesota, up here, we've got a
(04:13):
lot of Fargo Hegney clays, butthere's a lot of other places in
the world that have them too.
Only about 2% of the world'sice-free land surface is
vertasols.
Jodi (04:26):
One other common one, and I think the two other common
ones that I think are veryimportant for us to talk about
in the Midwest region would bespotosols and alpha sols.
These are both forest soils.
And spotasols, think about thatas being like your northern
Minnesota, your boreal forestareas, northern Wisconsin, that
kind of thing.
What makes these reallycharacteristic are they kind of
(04:48):
have these e-horizons or thesehorizons that are stripped of um
organic matter from the secondhorizon down.
And they're typically formed inareas, again, that are grown
under spruce and pine trees.
They're typically found inareas that have coarser textured
deposits.
And so the question is like,did they form because of the
(05:10):
trees or did the trees growthere because of the soil?
It's kind of a chicken and anegg thing.
But the point is that spotosolsare what we will find in
coniferous forest areas, andwe'll find those areas that
e-horizon, that kind of whitelayer underneath that top
organic matter layer.
Sarah (05:29):
And alpha sols are also have a history of being in the
forested area.
We actually do farm a number ofalpha sols.
Today they've been cleared ofthe trees.
Alpha cells kind of result froma weathering process that leach
clays and minerals and otherconstituents out of the surface
layer and into the subsoil.
(05:50):
Okay.
Now, alpha cells make up about10% of the world's ice-free land
surface.
Spotosols make up about 4% ofthe world's ice-free surfaces.
So if you go over intoMinnesota, for example, in
northwest Minnesota, and youstart heading east, there's a
lot of alpha cells as you moveinto that neck of the woods.
(06:13):
As you move further east,getting up towards uh like uh
Duluth and the North Shore andall that, that's where we run
into spotasols.
And one of my personal dreamsis to be in a root pit of a
spotasol, because oftentimesthey're really high in iron
content as well, and maybe alittle bit more acidic.
(06:33):
So you get those bright redcolors kind of going through
there, along with that E horizonthat Jody was talking about,
and they're really colorful tolook at.
So one of my lifelong dreams isto be in a in a root pit of a
spotasol.
Wanna go with me?
Vacation?
Jodi (06:50):
Absolutely, please.
Those alpha cells, like thatarea where all those clays leach
into, like that's what wetypically think of.
Like when we have like a clayhard pan, like you start talking
about places like Missouri thathave these hard pans that
they're dealing with, and thatis typically an artifact of the
alpha-sol soil order, whereyou've got that zone where that
(07:11):
clay accumulates, and you havethat, it can be in some cases a
restrictive layer where it'shard for water to move down.
That's kind of a distinguishingcharacteristic and kind of a
feature of the alphasol soilorder.
Sarah (07:25):
Absolutely.
For one second, I think it'sreally important for us to talk
about histosols because in GKTechnology's backyard of the
home area, um, we actually havesome histosols.
You have to get up to northwestMinnesota into the peat bogs.
Histosols are known for havinga lot of organic matter and no
(07:47):
permafrost.
Um, because there's anothersoil order that allows for
permafrost.
But these are usuallysaturated, very high in organic
matter.
So really think about like whatthat peat is.
Histosols make up only about 1%of the world's ice-free land
surface.
(08:07):
With that, I think it'simportant to note that there's a
bunch of other soil orders thatexist.
A lot of them are um, oh, thereis one that's also really
important for agriculture.
Ultasols, not around theMidwest, but when you move to
the southern United States,there's a lot of ultasols when
you get down there.
Usually it's a little bit morehumid.
(08:28):
A lot of times they'redominated by a more one-to-one
clay, which is very interestingfrom a standpoint that our clays
that are on vertasols, knownfor that shrinking and swelling
that we consider to be reallyreactive.
One-to-one clays are not thatreactive.
They have a very low cationexchange capacity and they do
(08:49):
not shrink and swell.
So compaction can actually getto be a bigger issue uh in that
soil.
But there is definitely somefarming that happens down there
on these types of ultasols.
Think like your Alabama'sMississippi's kind of that area.
There's definitely someultasols in that neck of the
woods.
Ultasols make up about 8% ofthe world's ice-free land
(09:12):
surface.
Jodi (09:13):
They also have they also tend to have a lot of iron
oxides.
And for this is for young Jodywho listened to a lot of country
music growing up and alwayswondered about red dirt roads
and always thought they werereferring to like scoria um in
western North Dakota.
No, they were not referring toscoria.
They were referring to the ironoxides found inside of their
clays in their altasolic soil.
(09:37):
So breaking Jodi's dreams ofrelevance in country music as a
child, the red dirt roads, thatred dirt country that all comes
from the fact that they've got adifferent order of soils down
in the south than we do up here.
So even though we haven'tcovered all, or even though we
haven't gone in depth in all 12of the different soil orders,
(09:58):
what am what's important to knowis that soils vary a lot, just
like we talked about and how weclassify different animals or
different types of life fromlike bacteria and between
reptiles and mammals and birds,those are big differences, just
like there are big differencesin the different soil orders.
And so as you travel indifferent climates to different
(10:19):
um types of parent materialwhere soil is formed, you're
gonna find different differentsoils and you're gonna find
different characteristicsassociated with those two.
So be curious, grab a shovel,maybe even a Montana
sharpshooter, dig some holes andsee what's below your feet.
Sarah (10:34):
It's a lot of fun to check it out.
Jodi (10:37):
Tune in next time for a Tiny Byte of knowledge from GK
Technology, where we have a mapand an app for that.
And now it's time for a Tiny Byte of knowledge.
Sarah (00:13):
Hey Jodi do you remember?
Oh, sometime last year we did atiny bite episode on what a
soil series is.
Remember how when you read whata soil series is, you can read
all about the characteristics ofthat soil and everything that's
in that.
I think it's important for usto realize that there is a
definite classification system.
(00:34):
And one of the things withinthat system has to do with the
broad base brush stroke of howwe group together different
soils and what theircharacteristics are that make
them act similarly to eachother.
Jodi (00:49):
Are you saying that there is a way of breaking down soils
at a larger, more general waythan just soil series?
Sarah (01:00):
Absolutely.
There's a whole taxonomy systemthat we've got in the United
States of America to help usthink about the ways that soil
are similar to each other anddifferent from each other and
different ways that we classifythem.
So just like we think aboutgrouping together animals and
(01:20):
animal taxonomy, we also canthink about soils in that manner
as well.
So let me let me help you putthis frame of reference
together.
So when you think aboutanimals, you might think about
animals being mammals orreptiles or amphibians or birds.
They're all animals, butthey're very different from each
(01:42):
other.
And I think we all know,especially in agriculture, that
soil is all soil, but it can bevery different.
You know, we've got soil outthere that's extremely sandy,
we've got soil out there that'sextremely clay, we've got soil
that's in the desert, we've gotsoil that's in the Arctic.
And we actually have a way ofclassifying those from a broad
(02:04):
standpoint into what we callsoil orders.
Well, let's go through and namethem all and let's see if we
get them.
Here we go.
Ready?
Entisols and septosols,vertisols, mollusols, olifosols,
aridosols, spotosols, altosols,oxisols, histosols, andosols,
(02:25):
and gelosols.
Woo! That's a lot.
That's a lot of cells.
They all have differentmeanings behind them.
And we can all we can thinkabout like what these things are
most common.
So, for example, a mollusol.
Jodi, what's a mollusol?
Jodi (02:45):
Mollusol is your basic prairie soil.
It is a soil that when the waythat you think about them is
that they have a really darksoil or like a really dark color
at the top.
That is an artifact of havinggrown up under grass-like
vegetation for a very longperiod of time.
That black is organic matter.
And typically they are grown inclimates that are, you know,
(03:07):
kind of more moderate.
They're not arid, they're notreally humid, but they're kind
of in the areas between forestedareas and arid desert areas.
So, like for us in the UnitedStates, the Great Plain region,
and also the Midwest regionwhere there were grasslands.
Those would be areas that havethese soils that are mollusols.
Sarah (03:27):
And in North Dakota and Western Minnesota, we've got a
lot of mollusols.
So make up about 7% of theworld's ice-free land.
So if it's all right, I'm gonnatalk about my favorite soil
order, which is vertasols.
Vertisols have high con havehigh clay content of highly
(03:52):
reactive clays, which meansthere's a lot of shrink and
swell to them.
Um they crack open.
So think about like when youget a drought and you lose your
wrench down the crack in thesoil.
That's that's that type ofsoil.
Okay.
It's a vertisol.
So in North Dakota, um,Minnesota, up here, we've got a
(04:13):
lot of Fargo Hegney clays, butthere's a lot of other places in
the world that have them too.
Only about 2% of the world'sice-free land surface is
vertasols.
Jodi (04:26):
One other common one, and I think the two other common
ones that I think are veryimportant for us to talk about
in the Midwest region would bespotosols and alpha sols.
These are both forest soils.
And spotasols, think about thatas being like your northern
Minnesota, your boreal forestareas, northern Wisconsin, that
kind of thing.
What makes these reallycharacteristic are they kind of
(04:48):
have these e-horizons or thesehorizons that are stripped of um
organic matter from the secondhorizon down.
And they're typically formed inareas, again, that are grown
under spruce and pine trees.
They're typically found inareas that have coarser textured
deposits.
And so the question is like,did they form because of the
(05:10):
trees or did the trees growthere because of the soil?
It's kind of a chicken and anegg thing.
But the point is that spotosolsare what we will find in
coniferous forest areas, andwe'll find those areas that
e-horizon, that kind of whitelayer underneath that top
organic matter layer.
Sarah (05:29):
And alpha sols are also have a history of being in the
forested area.
We actually do farm a number ofalpha sols.
Today they've been cleared ofthe trees.
Alpha cells kind of result froma weathering process that leach
clays and minerals and otherconstituents out of the surface
layer and into the subsoil.
(05:50):
Okay.
Now, alpha cells make up about10% of the world's ice-free land
surface.
Spotosols make up about 4% ofthe world's ice-free surfaces.
So if you go over intoMinnesota, for example, in
northwest Minnesota, and youstart heading east, there's a
lot of alpha cells as you moveinto that neck of the woods.
(06:13):
As you move further east,getting up towards uh like uh
Duluth and the North Shore andall that, that's where we run
into spotasols.
And one of my personal dreamsis to be in a root pit of a
spotasol, because oftentimesthey're really high in iron
content as well, and maybe alittle bit more acidic.
(06:33):
So you get those bright redcolors kind of going through
there, along with that E horizonthat Jody was talking about,
and they're really colorful tolook at.
So one of my lifelong dreams isto be in a in a root pit of a
spotasol.
Wanna go with me?
Vacation?
Jodi (06:50):
Absolutely, please.
Those alpha cells, like thatarea where all those clays leach
into, like that's what wetypically think of.
Like when we have like a clayhard pan, like you start talking
about places like Missouri thathave these hard pans that
they're dealing with, and thatis typically an artifact of the
alpha-sol soil order, whereyou've got that zone where that
(07:11):
clay accumulates, and you havethat, it can be in some cases a
restrictive layer where it'shard for water to move down.
That's kind of a distinguishingcharacteristic and kind of a
feature of the alphasol soilorder.
Sarah (07:25):
Absolutely.
For one second, I think it'sreally important for us to talk
about histosols because in GKTechnology's backyard of the
home area, um, we actually havesome histosols.
You have to get up to northwestMinnesota into the peat bogs.
Histosols are known for havinga lot of organic matter and no
(07:47):
permafrost.
Um, because there's anothersoil order that allows for
permafrost.
But these are usuallysaturated, very high in organic
matter.
So really think about like whatthat peat is.
Histosols make up only about 1%of the world's ice-free land
surface.
(08:07):
With that, I think it'simportant to note that there's a
bunch of other soil orders thatexist.
A lot of them are um, oh, thereis one that's also really
important for agriculture.
Ultasols, not around theMidwest, but when you move to
the southern United States,there's a lot of ultasols when
you get down there.
Usually it's a little bit morehumid.
(08:28):
A lot of times they'redominated by a more one-to-one
clay, which is very interestingfrom a standpoint that our clays
that are on vertasols, knownfor that shrinking and swelling
that we consider to be reallyreactive.
One-to-one clays are not thatreactive.
They have a very low cationexchange capacity and they do
(08:49):
not shrink and swell.
So compaction can actually getto be a bigger issue uh in that
soil.
But there is definitely somefarming that happens down there
on these types of ultasols.
Think like your Alabama'sMississippi's kind of that area.
There's definitely someultasols in that neck of the
woods.
Ultasols make up about 8% ofthe world's ice-free land
(09:12):
surface.
Jodi (09:13):
They also have they also tend to have a lot of iron
oxides.
And for this is for young Jodywho listened to a lot of country
music growing up and alwayswondered about red dirt roads
and always thought they werereferring to like scoria um in
western North Dakota.
No, they were not referring toscoria.
They were referring to the ironoxides found inside of their
clays in their altasolic soil.
(09:37):
So breaking Jodi's dreams ofrelevance in country music as a
child, the red dirt roads, thatred dirt country that all comes
from the fact that they've got adifferent order of soils down
in the south than we do up here.
So even though we haven'tcovered all, or even though we
haven't gone in depth in all 12of the different soil orders,
(09:58):
what am what's important to knowis that soils vary a lot, just
like we talked about and how weclassify different animals or
different types of life fromlike bacteria and between
reptiles and mammals and birds,those are big differences, just
like there are big differencesin the different soil orders.
And so as you travel indifferent climates to different
(10:19):
um types of parent materialwhere soil is formed, you're
gonna find different differentsoils and you're gonna find
different characteristicsassociated with those two.
So be curious, grab a shovel,maybe even a Montana
sharpshooter, dig some holes andsee what's below your feet.
Sarah (10:34):
It's a lot of fun to check it out.
Jodi (10:37):
Tune in next time for a Tiny Byte of knowledge from GK
Technology, where we have a mapand an app for that.
Popular Podcasts
Dateline NBC
Current and classic episodes, featuring compelling true-crime mysteries, powerful documentaries and in-depth investigations. Follow now to get the latest episodes of Dateline NBC completely free, or subscribe to Dateline Premium for ad-free listening and exclusive bonus content: DatelinePremium.com
Stuff You Should Know
If you've ever wanted to know about champagne, satanism, the Stonewall Uprising, chaos theory, LSD, El Nino, true crime and Rosa Parks, then look no further. Josh and Chuck have you covered.
The Bobby Bones Show
Listen to 'The Bobby Bones Show' by downloading the daily full replay.