November 20, 2024 • 40 mins
Unearth the secrets of soil science with our insightful guest, Tom DeSutter, as we navigate the fascinating landscape of soil classification and its vital role in agriculture. Discover how the unique vertisol soils of North Dakota's Red River Valley challenge and inspire local farmers, and learn why understanding soil taxonomy is akin to mastering the Latin naming system for plants and animals. Gain a deeper appreciation for the impact of soil composition on farming decisions, and how the presence of clays like smectite can shape agricultural practices.
Journey with us as we address the challenges of managing soil pH and salinity, particularly in arid climates. Explore the delicate balance of hydrogen ions and nutrient availability, and why substances like calcium carbonate are essential in neutralizing acidity, while gypsum isn't the magic fix for pH woes. Unravel common misconceptions about soil salinity in areas such as the Northern Great Plains, and understand the practical strategies farmers employ to maintain productive, healthy soils despite the presence of diverse salts.
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Sarah (00:00):
And now it's time for Ag Geek Speak with GK Technology's,
Sarah and Jodi, friends and Ican't wait to get in the fields
again.
No, I can't wait to get in thefields again.
(00:32):
Welcome back to Ag Geek Speak.
We are having just a very funconversation today, continuing
on from last week where we'revisiting with the great Tom
DeSutter.
Last week we visited aboutTom's background a little bit.
We visited about the five soilforming factors and just a
number of things.
If you haven't had a chance tohear that episode, I encourage
(00:54):
you to go back and check it outbecause it really does set the
stage for today quite well.
But let's jump into it.
One of the things that we hadtalked about a little bit at the
end of the conversation was howthe landscape really determines
how things are different indifferent places, and one of the
things that we did not get achance to talk about last time
(01:14):
was really that concept of soiltype and how soils change.
One of the things that inconversations I've had with a
number of different people is Idon't think people generally
understand that soils have aclassification system and just
how different soils are when westart thinking about, you know,
(01:35):
some of the different soilorders that actually exist.
There are 12 soil orders thatexist in soil taxonomy and they
all mean something verydifferently.
That exist in soil taxonomy andthey all mean something very
differently, and the reason I'meven bringing this up is because
in North Dakota we have a fewdifferent soil types, but
generally when we think of NorthDakota we think of prairies and
that's all we think about andit's just going to be the parent
(01:56):
material of prairies.
But especially on the east sideof the state, in the Red River
Valley, we've got what's calleda vertisol type soil, which is a
very well, some people call ita heavy clay.
I think Dr DeSutter might sayhow heavy is that clay?
Which is fair, but let's justbe real.
It's a very unique soil typethat we've got in the Red River
(02:17):
Valley of North Dakota.
Dr. Tom DeSutter (02:19):
So, Jodi and Sarah, thank you again for
bringing up the conversation.
Jodi and Sarah, thank you againfor bringing up the
conversation.
You know, because it was lastweek, I guess on the recording,
one of the things I've noted toboth these two fine students,
former students is that everyyear my class is new, and partly
because I don't remember what Italked about the year before.
And so what we talked aboutlast week was a little bit about
(02:40):
reading the landscape Right,that's the word I remember, and
so what we talked about lastweek was a little bit about
reading the landscape right,that's the word I remember, and
so.
But one of the things that youknow we talk about or think
about is like how does soilsform?
Why do they form, and then whatare the resulting properties
due to that formation?
And so what Sarah is alludingto is that you know we do have
(03:05):
in the Red River Valley acrossNorth Dakota, you know we have
different soil orders, mollisolsand vertisols and entisols, and
these all stem from what'scalled soil taxonomy.
And soil taxonomy was developed, not unlike the Latin system,
(03:26):
for identifying insects andplants and everything else.
So a lot of these terms thatare used in soil taxonomy have
their roots in Latin or Greek,and so if you think about the
fine loamy mix superactivehapludol, that doesn't mean a
lot to a lot of people.
Sarah (03:45):
It sounds like that sounds greek it's like actually
a lot of it is because there's alot of greek terminology in
that, so you can actually saythat and it actually.
Dr. Tom DeSutter (03:52):
It's actually true, but that's how we identify
these soils then helps peoplelike Sarah and others think
about the properties and thinkabout whether or not those
properties are going to beconducive for crop production or
not.
And so the vertisols, as anexample, has a.
We think about these as likehaving a.
(04:13):
So we have different types ofclays too, and that gets all
complicated right and it's likeoh, I thought this was easy.
It's like, well, it sort of is,but part of it is you have to
have a base knowledge of likewhat these terms mean.
And so things like you knowsmectite, you know we think
about smectite and chloride andkaolinite and things that these
(04:40):
are the clays, but these are theclays that actually drive the
soil properties.
And so smectite, as an example,is a shrink-swell clay.
And so those of you that havesoils and you've seen it time
and time again when you get intoAugust, oftentimes the soils
form this big crack and that'sthe clays.
(05:01):
Dehydrating.
That means most all the timethe soils are hydrated in some
way, but as that water leaves,the clays tend to contract and
when they contract, theycontract along fault lines, and
when they contract along faultlines, you get these big cracks,
and that's when you seevertisols, meaning invert.
That means soil falls down intothose cracks, it hydrates back
(05:24):
up again and it closes back upand then five years later it
opens up again because ofdrought and things fall back
down again, and so on and soforth.
And so vertisol, meaning invert, is an example of what we'd
describe as a high clay soilwith a shrink swell of
characteristics.
But most of these soils thatwe're talking about are very
(05:47):
highly productive.
And they're highly productivebecause plant productivity over
the course of thousands of yearshas put a lot of organic matter
into these soils, and that'swhere a lot of our productivity
will come from.
Sarah (06:01):
I think it's really interesting to bring that up.
One of our conversations fromlast week was talking about how
farmers interact with theirdifferent landscapes and the
decisions that they have to makebased on what their locations
are, and in a lot of thesevertisol type soils in North
Dakota, for example, are rightin the Red River Valley.
My favorite soil type I'm justgoing to say this point of
(06:24):
personal privilege here it's theFargo clay and I'm sure that
there's a ton of farmers outthere that are going really that
loon poop what are you thinking?
Because it's also a verydifficult soil to work with as a
farmer, but it is the soilthat's right in my backyard and
I will say that to a certainpoint, I think farmers that are
(06:47):
farming in that soil typethey've got a very different way
of thinking about planting thatfarmers who have never
experienced that soil typebefore.
Because when you, if you dotillage on that soil at the
wrong time, you create a lot ofextra dirt lumps in that field
(07:07):
and that becomes verychallenging to make good seed
beds out of.
So it's interesting because Ihave seen it many times right
here in my backyard where thefarmers to the west of the
valley might be going up on theridge where we have the
non-vertisol type soils, and yetwhen you come down into the
(07:28):
Fargo clays the farmers aren'tgoing, because they know that if
they go out and start workingwith that soil at that point in
time they're going to make areally big mess and it's going
to cost them a lot of yield atthe end of the day.
But to have that patience toknow that, even though it looks
like you could do something,that they'll sit back and
(07:49):
they'll wait when theirneighbors out west are out
working the ground and makingthings happen, it's just really
an interesting thing to see.
Honestly, it's been one of thethings that I've always thought
was really interesting aboutagronomy, when you're trying to
work with farmers in differentplaces and different landscapes
(08:09):
on different soils.
Dr. Tom DeSutter (08:10):
You know, sarah, you bring up a good point
.
It's almost like atrafficability map and it's
based on soil series or types ofsoils, right, and so when it's
too wet, it's too sticky, it's,you know, your traffic ability
just goes down.
But if it's too dry, like wetalked about, and you bring up
you know, and the soil is justtoo hard, the traffic ability is
(08:33):
just fine.
But the cultivation, thecultivability of that soil is is
is shearing, a lot of bolts,and so it's just an interesting
problem that is not unique toNorth Dakota, but it's not
uncommon in areas that havevertisols, that have these
high-strength swells somevertisol type soils in South
(08:55):
Dakota, and certainly we have aclientele down in South Dakota
as well.
Sarah (09:06):
Can you talk about where some of these vertisols might be
occurring in South Dakota aswell?
Dr. Tom DeSutter (09:13):
I'll use maybe an example.
So the Red River Valley ofTexas and Oklahoma, right, so
we're talking about lower lyingareas that may have, you know,
not necessarily annual flooding,but maybe there was some
depositional things when thesoils were formed or created.
So not unlike the bottom ofLake Agassiz, you know, things
(09:37):
settled out over time and thelast things to settle down were
the clays and the silts, and sothat's where you tend to have in
some ways a higherconcentration of clay in these
areas that were old lake beds ormaybe riverian areas that are
older, but that's, you knowwhere they are.
(09:59):
Maybe along the Big Sioux Riverbasin, you know things of that
nature, which I actually grew upalong the Big Sioux River in
Iowa, but we had more of the.
You know more of the, the loss,the windblown deposits in that
area and so very highlyproductive soils.
You know Iowa is has beenblessed by very good soil, very
(10:22):
good soils and and rainfallwhich is why it's.
You know, it does really well inagriculture.
Jodi (10:29):
I forget what order are that.
Is that also a mollisol?
Or is there another order thatthe windblown deposits are?
Dr. Tom DeSutter (10:38):
Yeah, it would be classified as a parent
material.
I don't think it necessarilyhas to have an order to it.
Paramaterial I don't think itnecessarily has to have an order
to it.
But, as a fun fact, if you wentto Puerto Rico those of you
that are thinking aboutvacationing Puerto Rico, the
island you know, out in themiddle of the Caribbean it has
10 of the 12 soil orders and soif you can find yourself on a
(11:01):
tour, a soils tour, you canvisit everything but gelisols,
which are the cold ones, whichpeople from Puerto Rico would
probably move to North Dakota ifthat was their soil order.
Sarah (11:16):
Permafrost is a gelisol, yeah.
Dr. Tom DeSutter (11:18):
And then so the andisols, which are the
volcanic and so.
But you know, you can go downto Linton, North Dakota, and you
can find all the volcanic ashyou want, right, I mean there's
a huge deposits of volcanic ash.
Sarah (11:31):
I did not know that.
Dr. Tom DeSutter (11:33):
I can.
I can hold some up.
You know that we actually wentand collected a bunch to see
what kind of, because oftentimesthese oxides in these, like
iron oxide as an example, has areally high retentive for
phosphorus, and so we have readthat this volcanic ash also can
(11:54):
retain phosphorus.
We did a bunch of studies hererecently and the volcanic stuff,
even though it does have someiron oxide in it it's mostly
silica oxide and other things.
Aluminum oxide doesn't have alot of good retentive properties
for phosphorus, but we got abunch of this mining ore
(12:18):
byproduct and it's about 30%iron oxide, percent iron oxide,
and so when you're thinkingabout also about parent
materials and where soils comefrom, understanding a little bit
about these properties helpsyou manage your fertilizer too
right.
If you have a high calcareoussoil in a field, your phosphorus
retention creating calciumphosphates, the odds of that are
(12:41):
much greater than they would ifyou don't have that free
calcium in those systems.
So not only do the work we dois related to environmental work
, but it's also applicable tothese landscapes and how you
manage these fertilizers.
Jodi (12:57):
Can we talk a little bit about that too?
And maybe pH that is the drumthat I will constantly beat, but
I think it's important to talkabout because it also discusses
some of these other like soiltypes and things that affect pH.
And sure, like for the mostpart, in a mollisol soil on a
typical prairie profile, right,we have a lot of that calcium
carbonate, probably not going tohave to worry about acidic
(13:19):
soils, but we have these acidsoil issues and I'm curious, you
know, what types of areas wouldwe typically see, or what kind
of landscapes or parent materialwould we expect to see a higher
incidence of acidic soils, orwhich ones are more prone to
become acidified over time in acropping system here in the
(13:39):
Northern Great Plains?
Dr. Tom DeSutter (13:41):
Yeah, you know , I certainly think the ones
that have plenty of calcium inthem, like lime.
The odds of seeing acid soilsin Walsh County or Grand Forks
County have got to be prettysmall right.
Jodi (13:54):
Right, and Sarah works at a farm just north of my house
and I live on an old Agassizbeach line in western Grand
Forks County.
But Sarah does have a farm Ifound some you did.
Sarah (14:07):
And I've got some that are two miles off of I-29 by
Hillsboro small percentage ofoverall Grand Forks and Traill
County.
But I mean you have to gridsample to find them are they in
the?
Dr. Tom DeSutter (14:19):
are they in the fives or are they in the
four fives?
Okay, yeah, I mean I've seensome stuff south of Dickinson
that we sampled that were like4.5.
But we kind of looked for thealuminum.
So as you get lower in pH, youhave more exchangeable aluminum
and then more hydrogen, becausehydrogen is really.
(14:42):
pH is a term called the power ofhydrogen, but it's also the
negative log of hydrogen isreally what pH is, a term called
the power of hydrogen right,but it's also the negative log
of hydrogen is really whatyou're after.
And so even a concentration oftiny concentration, one times 10
to the minus seventh moles perliter which we won't worry about
the units at this point that'sa pH of seven.
And so a pH of five is onetimes 10 to the minus fifth, and
(15:05):
so that's a pH of five.
And so, as you alter thathydrogen concentration, that's
what drives the pH.
That driving of the pH is whatdrives nutrient availability and
sort of like.
The availability of phosphorusis the main one we talk about,
right, and then the toxicitythat aluminum, aluminum 3 plus
(15:34):
would have on roots themselves.
And so managing these acidsoils is and will be complicated
right by the fact that you havearid environments.
The most common thing you do isapply lime, which is calcium
carbonate.
If we think about thesolubilities of salts, if you
think about gypsum, which iscommonly talked about as being a
liming agent, which it isn't,do not apply a gypsum if you, if
(15:59):
you think you're going tochange your pH.
Sarah (16:01):
Can I just reemphasize that, tom?
Yeah, if you guys did not hearthat, do not apply gypsum to
change your pH.
There you go.
Dr. Tom DeSutter (16:11):
There set Right, we got it set Anyway.
But the solubility of gypsum islike one US penny in a liter of
water.
So two bottles of water thatyou buy at the, you know those
500, those plastic bottles ofwater you buy by the case, two
of those and so.
But the solubility of calciumcarbonate is like 35 times less
(16:32):
than that.
So that's almost like takingthe face off of Lincoln off the
penny, and that's what willdissolve in that much water.
And so that's the complicationof in the Western part of the
state is you don't have enoughwater to actually dissolve, to
make the to, to dissolve thatsalt into calcium and carbonate.
The calcium is used to helpremove the aluminum and the
(16:56):
hydrogen off the soil exchangesites.
The carbonate is whatneutralizes, then that hydrogen
creates water and eventuallycreates water and carbon dioxide
.
And so if you don't have water,as we talked about before,
water is the great equalizer.
And so how do you manage waterand keep water and get more
water into the profile?
That's the biggest challenge,especially in arid and semi-arid
(17:19):
environments.
Jodi (17:20):
Okay, Another question I had kind of related to that.
We talked a lot in the lastepisode about just salty soils
in general and why here in theNorthern Great Plains we've got
more of them in other places.
I'm curious.
We've talked about calciumcarbonate, lime.
We've talked about gypsum,another salt, calcium sulfate.
Can you talk more about whatare the other common salts that
(17:42):
we have here?
Because I think when peoplethink salt they think table salt
, right, so sodium and chloride.
And a person might think, oh,if we're talking about salts in
the landscape, we're probablytalking about sodium chloride,
so we're going to have sodicityin that field.
But that's not the case.
Can you tell us more about whatour common salts are here in
the state?
Dr. Tom DeSutter (18:02):
Okay, so we go back to the point of what a
salt is, and a salt is an anionand a cation, and so in
non-aqueous, non-waterconditions, a salt is a crystal,
right?
Not the crystal, the big, youknow, wedding ring sort of
crystals that you can buy now,that are manufactured, but these
(18:24):
are crystals that formnaturally.
And so back to the maybe aconversation of on your.
You know, it's a hot day,you've been sweating all day and
you take off your hat and it'swet, and then you let it dry,
that's the salt that iscrystallizing on your hat, and
so that's what we have in thesoil.
And so we have salts that aremagnesium sulfate, calcium
(18:47):
sulfate, sodium sulfate, somesodium chloride, calcium
carbonate, of course, which is avery sparingly soluble, but
those would be kind of like themain ones that we would consider
to be the ones that are mostinfluential in crop production.
And so, as we think about howimpactful they are, there's a
lot of really good cropproduction.
And so, as we think about, like, how impactful they are, you
(19:07):
know there's a lot of reallygood crop production that is, in
calcareous soils, you can seethe line, but there's a lot, man
.
It is like good production.
Right and so, but the problemthe reason is, is those that
when it's wet, that calcium andcarbonate isn't negatively
impacting the plant.
Right and so.
If you have things likemagnesium sulfate, which it
(19:30):
takes almost, you know, like ahandful in a liter of water and
that's how much will dissolvewhere you can actually don't see
any particles in that water,well, that's a lot different
concentration in the soil,that's that's uh solubilized
than it is for calcium carbonate, and that's why the solubility
(19:51):
of uh, of salts, is what impactseventually crop production.
And so, like calcium sulfate,which is gypsum again, it was
that one penny size and a literof water you can farm in calcium
sulfate enriched soils.
Not a problem, right?
I mean it's you have calciumand you have sulfate and they're
both like necessary plantnutrients, and but they only
(20:13):
because its solubility is so lowit doesn't negatively impact,
you know, plant production.
Jodi (20:20):
So that's such a good, that's such a great point, cause
you know we talk about calciumcarbonate as being a salt, but
we never.
We really shouldn't worry abouthaving too much of it, besides
maybe having to apply morephosphorus because it can tie up
phosphorus at the higher pHs.
But, like you said, like evenin like my garden in Grand Forks
County, I can see that freelime in the surface of the soil,
(20:43):
but it's not negativelyaffecting my, my vegetable
production, because it's notsoluble in the soil, it's not
breaking down and it's notcausing salt damage to the
plants that I'm growing there.
Same thing with the crops andsame in the same area too.
Dr. Tom DeSutter (20:57):
Yeah, I mean, if you were, you know back to
you know back in the days of thecivil war when they salted
fields.
I mean the reason was to addsalt to decrease crop production
, right, and that was a way ofcontrolling the food supply.
But in the southwest part of theUnited States you also get 50
(21:18):
to 60 inches of rainfall a yearand so that washed through, and
then, I'm sure, after a coupleof years, it was fine, back to
its normal productivity, and sothe problem that we have is that
, as we, as we stated, notenough water to leach things
down, and if you do leach itdown, the atmosphere demands a
lot of water, so everythingmoves back up again, and so
(21:40):
that's that's a challenge thatyou, as agronomists, have to
recommend.
Sarah (21:45):
So I think that was a really great conversation about
salts, but so often we hear thisidea of what sodic soils are.
So really, what is thedifference between a sodic soil
and a salty soil?
Dr. Tom DeSutter (21:58):
Okay, so we use.
I had a conversation with JohnLee, the great John Lee from
AGVISE.
I had a conversation with JohnLee, the great John Lee from
AGVISE.
He had someone call one timeand said that his soil was sour.
Perfectly fine, a regional term, right.
But it took John a half hour tofigure out if his soil was what
(22:22):
we would consider to be sodicor saline, because sour was the
actual term.
And so if you look at a soiltest report and you have done on
that soil test report, solublesalts or electrical conductivity
, whichever lab you're using,and have them run a test for a
(22:45):
base saturation, and so what wewould normally see is that if a
soil has a percent sodium inthat base saturation that's
greater than five, and if thatsoil has an EC or a soluble salt
of less than one, we mightconsider that soil to be getting
(23:07):
close to the fact of of beingsort of in that sodic sort of
range.
And what that means is that youhave a lot more sodium in
comparison to calcium, magnesium, potassium, and so what?
What the problem with sodium isthat it likes to be hydrated,
it likes to be, it likes to besurrounded by water, right, it's
(23:28):
kind of like a it's kind oflike a rock star that has a lot
of people around them all thetime, right, they like to be
hydrated with people, and so,whereas calcium tends to be a
little more of an introvert butlikes to be coordinated with
just a couple of people, tendsto be a little more of an
introvert but likes to becoordinated with just a couple
people, and so that calcium onthe exchange sites coordinates
(23:50):
with the internal matrix of theclay and holds it together, and
so it's a flocculant, whereassodium likes to be hydrated and
it can't hold that clay sheetstogether very well, and so the
clay sheets tend to repel eachother, and then that's when you
get sort of like the swelling ordispersion.
And so that's why but it'slargely, largely regulated by
(24:13):
the overall electricalconductivity of the soil or the
soluble salt content.
You can have a soil with like areally high concentration of
sodium, but if the electricalconductivity is high, not a
problem.
The sodium isn't the problem,it's the high electrical
conductivity.
But that's what helps keep theclay sheets together is just the
(24:35):
chemical potential, if you will, of the inside of the clay
sheets and the outside.
And so when you see, when youhave what Sarah is describing as
a sodic soil you will haveoftentimes see the soil
particles, the clay particles,repel each other, and when they
repel each other they kind ofbreak apart and then they'll
(24:56):
kind of move down through thesoil profile over time and
that's oftentimes what you'llsee is what we call is a zone of
accumulation of clay and sodium, and so they're a lot easier to
sort of think about from thestandpoint of being separate
from saline soils, because theydevelop differently, but
(25:19):
unfortunately they get kind oflumped together into sour or
sick or something like that, andthen it becomes a little more
complicated to just kind oftease out what they are.
In Grand Forks County, walshCounty, most all of those soils
are probably what we would callboth saline and sodic.
They have a high concentrationof sodium but they also have a
high concentration of salt, andso we just kind of lump them
(25:42):
into that term.
Jodi (25:43):
So say, if somebody has a combination sodic and saline
soil, how should they approachmanaging that?
What should they tackle first?
Dr. Tom DeSutter (25:51):
Yeah, so the first thing is to manage the
water, and so likely those soilsthat have those conditions also
have a high water table, or,historically, have had a high
water table over time, whichallows that water to wick up
into the root zone, and then,when the water evaporatesick up
into the root zone, and then,when the water evaporates, the
salts are left behind, and sothe first thing to do would be
to manage the water, becausewhen you manage the water,
(26:14):
you'll manage the soluble salts,and when you manage the soluble
salts after that, that's whenyou can start to manage the
sodium, and so you may have toadd things like gypsum, which is
a sparingly soluble salt, butit's actually fairly effective.
It's one of the it is the mostcommon amendment to use for
(26:37):
sodic soils.
Do not add gypsum to a salinesoil, because you're not going
to do anything.
Sarah (26:43):
So I think this is a really important point, because
people get confused as to wheregypsum is appropriate and what
it's appropriate for.
If you have a low pH situation,adding gypsum is not going to
help you.
If you've got a sodic soilsituation, gypsum is going to be
the amendment that is going tohelp you to manage that sodic
(27:06):
soil situation.
Dr. Tom DeSutter (27:08):
Correct, correct.
And I have heard people tryingto use beet lime and things of
that nature and the solubilityof lime is just so low that
you're basically just adding abunch of particles, if you will,
to that soil and it might helpwith the traffic ability or the
(27:29):
tilth of how well you can tillthat soil, but at the end of the
day it's not the preferredamendment at all for sodic soil.
Jodi (27:39):
When I think about the solubility of because I used to
struggle with that too likethinking about solubility.
I remember talking about thatin class but I never really
thought about why it wasimportant or what was applicable
about it.
But, like, when I think aboutand describe to people lime
versus like gypsum, I thinkabout lime that's formed from,
like the crushing of all theseclamshells and ocean mollusks at
(28:01):
the bottom of an ocean, right,and then, over time, as millions
and millions of years push themtogether, you get this
limestone.
But, like you think about it,if lime is made out of the
shells of these ocean critters,they're going to be made out of
something that isn't very watersoluble, or like it doesn't
dissolve in water becausethey're living in these things,
(28:21):
right.
So that's how I always rememberabout like why, why lime is so
insoluble versus something likegypsum that is, is relatively
more soluble.
Dr. Tom DeSutter (28:31):
Yeah, I mean it's relatively more soluble not
, you know, very soluble, but itis.
But it is more soluble.
And so you know, where do weget gypsum?
North Dakota is blessed withenergy resources, right?
I mean, we have our coal, wehave our natural gas, we have
oil, we have wind.
We haven't seen any solar farmscome in.
(28:52):
That can be a topic for a sideconversation.
But in 1990, when the Clean AirAct was brought into play, the
coal facilities had to scrub outthe sulfur from the burning of
our coal, because we have toremember that all this work to
(29:13):
get coal is to basicallyevaporate water to drive a
turbine, and so we have toremember that that's why we get
the coal.
It's not just because they'reburning coal, but it's to
evaporate water to move aturbine right and so.
And so they had to scrub outthat air, and what they do is
they use what's called forcedwet oxidation.
Basically they put calciumcarbonate, again using calcium
(29:36):
carbonate, and they wouldactually use that to then pull
the sulfur and the mercurymercury in a way out of the
stack, and then they're leftwith a product that they have to
do something with, and so theLeland Olds plant in North
Dakota has converted thatcalcium sulfite to calcium
sulfate which is now used for inour agricultural production.
Jodi (30:00):
And that's kind of the same process of like beet too.
So for anybody here in thevalley that uses sugar beet lime
to control a phantom isis ormaybe increase tilth, or if
you're using it to haul back toan area with low pHs to amend
the soil, just like the calciumoxide is used, or like the lime
is used to scrub sulfur from thesmokestacks, the sugar beet
(30:22):
processing plant use thatcalcium carbonate, that lime, to
refine the sugar, and thenwe're left with a byproduct at
the end that we can then use outin fields.
So it's kind of the same thingbut a little bit more intense in
the energy process, coming outwith gypsum at the end.
Sarah (30:39):
It would be remiss of us to overlook drain tile when
we're talking about sodic andsaline sodic soils.
Right, you know, D.
r DeSutter, you were talkingabout managing the water and
really needing to manage thatwater if we're going to manage
salts.
So drain tile as we previouslydiscussed in the previous
episode, that is an excellentway of trying to manage water
(31:01):
coming into the surface.
In areas where water isactively rising to the surface,
well, in sodic soils, that cancertainly create some challenges
where, if you've leached all ofthe other salts besides the
sodium out of the system, youcan be left with that sodic soil
which, in essence, can end upsealing up to itself if we're
not going to try to remediatethat some way.
(31:22):
So how do we manage that?
Dr. Tom DeSutter (31:26):
I would say the first thing to manage that
is to monitor through soiltesting, and so that's the main
way that we identify some ofthese, lump them into this
category of problem soils,whether it's acid, whether it's
saline, whether it's sodic orwhatever.
But yeah, soil testing.
Annually.
Soil testing in the same spot.
(31:46):
Now, of course, if you went tothe same spot and there's a hole
, move over a little bit andsample that, right.
But yeah, the annually sample.
And I think you know some of ourlongest term data is actually
collected by AGVISE.
They had a very strongforesight in trying to figure
out if tile drainage was working, and so and it has over time,
(32:08):
but it's taken years, right andso, but yeah, annually soil
sampling.
Speaking with your agronomistsor speaking with your soil
testing lab knowledgeable peopleabout the topic, you can call
us we have two new extensionfaculty that are coming on board
, Dr.
Carlos Perez and Dr.
Brady Gottel, and so they willalso be available to answer any
(32:31):
of these questions.
But yeah, annually soilsampling.
Monitor over time.
If, in fact, when that ratio ofyour base saturation, percent
sodium becomes out of line withyour electrical conductivity of
your soil, that's when you wouldhave to consult.
Jodi (32:50):
And I would want to say too, when we talked about soil
testing for tile drainage when Iwas working at AGVISE, one of
the things that we try to conveyto folks too is that it's
important to sample to the depthof tile as well, not because,
like if you're doing a one footsample and figuring out what the
sodicity and the salinity ofthat one foot is, it's good to
(33:10):
know and it may be indicative ofwhat's below, but most of the
time we're putting in tile linemuch deeper than a foot, and so
it's going to be important toknow, if you've got any sodicity
problems farther down, wherethat tie line is going to be and
where that water is going to beflowing to as well.
Dr. Tom DeSutter (33:24):
Yeah, you know , I think on an annual basis
maybe you could just stick withyour you know zero to six, six
to 12, or you know six to 24,but periodically, maybe every
three or five years, make sureyou get to depth right to
monitor that.
And certainly you know, we know, that with gravitational water,
that means the water that'sgoing to move down through the
(33:46):
force of gravity, that's goingto carry salts with it and it's
probably going to increase theconcentration of salts to depth
at some point, leaving the toppart maybe less salty, if you
will.
And so that's the area that youwant to make sure that you can
handle.
It's really really difficultover time to manage things you
(34:07):
can't see right, and so takingcare of what you can sample
regularly is key.
Sarah (34:15):
So when you were talking about that soil testing level,
where we really need to makesure that we're in consultation
again, that's that 5% sodium onthe base saturation.
Dr. Tom DeSutter (34:25):
Correct, yeah.
And so I'm just visuallylooking at the AGVISE soil test
report and on the lowerright-hand corner you have
what's the percent basesaturation on that.
And so, just by happenstanceprobably, Mr.
Deutsch put zero to 5% on thatsodium and actually through our
(34:47):
research, through actually agood friend of Sarah's who did a
lot of the work, Kathy, wedetermined that 5% was really
kind of the limiting factor, andso anything greater than 5%
should be paid attention to,greater than anything less than
5%.
Sarah (35:06):
And I also.
Before we end this conversation,I also want to make sure that
I'm bringing us back to thatstudy that you were talking
about that John Lee was doingwith egg vice for all those
years, because I followed thatstudy for a number of years as
an agronomist, constantlygetting continuing education.
There was a field not so faraway from Northwood the soil
(35:28):
sampling lab that John wasassociated with with AGVISE and
there was a part in that fieldthat was saline- sodic and then
there was also areas in thatfield that were saline- sodic
and then there was also areas inthat field that were saline and
they drain tiled that and theydid remediate or or apply gypsum
in conjunction with that draintile at that point in time and
(35:50):
the crop production on that wasokay at that point in time but
it was watched very carefullyand it was soil sampled very
carefully.
So from a real standpoint, ifyou are in a situation where you
have a saline sodic soil, youcan manage that effectively and
actually drain tile.
But you need to be careful thatyou're being very diligent
about how that's being handled.
Dr. Tom DeSutter (36:13):
Yeah, and you know we always our phone lines
are always open.
We, you know, we hope thatpeople utilize us.
We are here we are part of theland grant mission to bring
education out to ourstakeholders and to answer those
questions just the same.
But we have an exceptionallyhigh number of very, very, very
(36:37):
good crop advisors in this state, and so I think that's the one
thing that we're blessed withtoo is like we have an
exceptional group of cropadvisors in this state, and so
if you have questions, pleaseconsult your crop advisor, if
you have one.
Jodi (36:52):
And I think that goes back to having a lot of the crop
consultants in the state went toNDSU and they were able to take
classes like soils and land usefrom professors like you.
Again, we appreciate so muchthe time you took with us today,
the pedagogy and the teachingthat you give to students at
NDSU.
Sarah (37:11):
And thanks for putting up with us in your class.
I really appreciate that.
You know, when Tom startedteaching our class, he began
saying oh good, this is whereyou're all sitting.
Once I get you memorized whereyou're all sitting in this room,
you'll, you'll, you'll besitting in here forever.
So near the end of thatsemester, I walked in before
everybody before Tom was thereand I said okay, everybody,
(37:33):
let's switch spots today.
And it was the day that he hadto hand out papers.
It was great that he had tohand out papers.
Dr. Tom DeSutter (37:38):
It was great.
So that was.
I remember that vividly, so Ijoke ha, ha that the only reason
I give homework is so I canfigure out their names, and so
now everything's online in asense, so it's not as much fun.
But yeah, I never really gradedthem, I just wanted to hand
them back to see what your nameswere.
Jodi (38:00):
All of you aspiring teachers take note.
Dr. Tom DeSutter (38:04):
So I don't always remember students' names
per se, but I know where theysat and so that's you know.
That's how I sort of relate myexperiences.
A little bit is like the visual, the memorization of, like what
was happening during that timeand you know, it goes back to
you know, we know exactly wherewe were when 9-11 happened,
(38:25):
right, I mean, you know exactly.
And so I try to bring that intothe classroom, just so I
remember, try to remembereveryone, because sooner or
later a student's going to comeup and say, oh, do you remember
me?
And most of the time you know Ican say honestly, yes.
And so oh, yeah, you sat back inthe left-hand corner by the
window.
I remember where Jodi sat.
(38:45):
I remember where Sarah sat.
Sarah (38:48):
Well, thank you so much for joining us today.
This would end the previousepisode as well.
It was a great conversation.
It's always fun geeking outwith you about soils a little
bit and just how we seelandscapes and everything.
So thank you.
Dr. Tom DeSutter (39:03):
My pleasure and I hope everyone has a safe
cropping and harvest season inthe future.
Jodi (39:10):
Thank you so much, tom.
And with that, remember, withGK Technology we have a map and
an app for that.
And now it's time for Ag Geek Speak with GK Technology's,
Sarah and Jodi, friends and Ican't wait to get in the fields
again.
No, I can't wait to get in thefields again.
(00:32):
Welcome back to Ag Geek Speak.
We are having just a very funconversation today, continuing
on from last week where we'revisiting with the great Tom
DeSutter.
Last week we visited aboutTom's background a little bit.
We visited about the five soilforming factors and just a
number of things.
If you haven't had a chance tohear that episode, I encourage
(00:54):
you to go back and check it outbecause it really does set the
stage for today quite well.
But let's jump into it.
One of the things that we hadtalked about a little bit at the
end of the conversation was howthe landscape really determines
how things are different indifferent places, and one of the
things that we did not get achance to talk about last time
(01:14):
was really that concept of soiltype and how soils change.
One of the things that inconversations I've had with a
number of different people is Idon't think people generally
understand that soils have aclassification system and just
how different soils are when westart thinking about, you know,
(01:35):
some of the different soilorders that actually exist.
There are 12 soil orders thatexist in soil taxonomy and they
all mean something verydifferently.
That exist in soil taxonomy andthey all mean something very
differently, and the reason I'meven bringing this up is because
in North Dakota we have a fewdifferent soil types, but
generally when we think of NorthDakota we think of prairies and
that's all we think about andit's just going to be the parent
(01:56):
material of prairies.
But especially on the east sideof the state, in the Red River
Valley, we've got what's calleda vertisol type soil, which is a
very well, some people call ita heavy clay.
I think Dr DeSutter might sayhow heavy is that clay?
Which is fair, but let's justbe real.
It's a very unique soil typethat we've got in the Red River
(02:17):
Valley of North Dakota.
Dr. Tom DeSutter (02:19):
So, Jodi and Sarah, thank you again for
bringing up the conversation.
Jodi and Sarah, thank you againfor bringing up the
conversation.
You know, because it was lastweek, I guess on the recording,
one of the things I've noted toboth these two fine students,
former students is that everyyear my class is new, and partly
because I don't remember what Italked about the year before.
And so what we talked aboutlast week was a little bit about
(02:40):
reading the landscape Right,that's the word I remember, and
so what we talked about lastweek was a little bit about
reading the landscape right,that's the word I remember, and
so.
But one of the things that youknow we talk about or think
about is like how does soilsform?
Why do they form, and then whatare the resulting properties
due to that formation?
And so what Sarah is alludingto is that you know we do have
(03:05):
in the Red River Valley acrossNorth Dakota, you know we have
different soil orders, mollisolsand vertisols and entisols, and
these all stem from what'scalled soil taxonomy.
And soil taxonomy was developed, not unlike the Latin system,
(03:26):
for identifying insects andplants and everything else.
So a lot of these terms thatare used in soil taxonomy have
their roots in Latin or Greek,and so if you think about the
fine loamy mix superactivehapludol, that doesn't mean a
lot to a lot of people.
Sarah (03:45):
It sounds like that sounds greek it's like actually
a lot of it is because there's alot of greek terminology in
that, so you can actually saythat and it actually.
Dr. Tom DeSutter (03:52):
It's actually true, but that's how we identify
these soils then helps peoplelike Sarah and others think
about the properties and thinkabout whether or not those
properties are going to beconducive for crop production or
not.
And so the vertisols, as anexample, has a.
We think about these as likehaving a.
(04:13):
So we have different types ofclays too, and that gets all
complicated right and it's likeoh, I thought this was easy.
It's like, well, it sort of is,but part of it is you have to
have a base knowledge of likewhat these terms mean.
And so things like you knowsmectite, you know we think
about smectite and chloride andkaolinite and things that these
(04:40):
are the clays, but these are theclays that actually drive the
soil properties.
And so smectite, as an example,is a shrink-swell clay.
And so those of you that havesoils and you've seen it time
and time again when you get intoAugust, oftentimes the soils
form this big crack and that'sthe clays.
(05:01):
Dehydrating.
That means most all the timethe soils are hydrated in some
way, but as that water leaves,the clays tend to contract and
when they contract, theycontract along fault lines, and
when they contract along faultlines, you get these big cracks,
and that's when you seevertisols, meaning invert.
That means soil falls down intothose cracks, it hydrates back
(05:24):
up again and it closes back upand then five years later it
opens up again because ofdrought and things fall back
down again, and so on and soforth.
And so vertisol, meaning invert, is an example of what we'd
describe as a high clay soilwith a shrink swell of
characteristics.
But most of these soils thatwe're talking about are very
(05:47):
highly productive.
And they're highly productivebecause plant productivity over
the course of thousands of yearshas put a lot of organic matter
into these soils, and that'swhere a lot of our productivity
will come from.
Sarah (06:01):
I think it's really interesting to bring that up.
One of our conversations fromlast week was talking about how
farmers interact with theirdifferent landscapes and the
decisions that they have to makebased on what their locations
are, and in a lot of thesevertisol type soils in North
Dakota, for example, are rightin the Red River Valley.
My favorite soil type I'm justgoing to say this point of
(06:24):
personal privilege here it's theFargo clay and I'm sure that
there's a ton of farmers outthere that are going really that
loon poop what are you thinking?
Because it's also a verydifficult soil to work with as a
farmer, but it is the soilthat's right in my backyard and
I will say that to a certainpoint, I think farmers that are
(06:47):
farming in that soil typethey've got a very different way
of thinking about planting thatfarmers who have never
experienced that soil typebefore.
Because when you, if you dotillage on that soil at the
wrong time, you create a lot ofextra dirt lumps in that field
(07:07):
and that becomes verychallenging to make good seed
beds out of.
So it's interesting because Ihave seen it many times right
here in my backyard where thefarmers to the west of the
valley might be going up on theridge where we have the
non-vertisol type soils, and yetwhen you come down into the
(07:28):
Fargo clays the farmers aren'tgoing, because they know that if
they go out and start workingwith that soil at that point in
time they're going to make areally big mess and it's going
to cost them a lot of yield atthe end of the day.
But to have that patience toknow that, even though it looks
like you could do something,that they'll sit back and
(07:49):
they'll wait when theirneighbors out west are out
working the ground and makingthings happen, it's just really
an interesting thing to see.
Honestly, it's been one of thethings that I've always thought
was really interesting aboutagronomy, when you're trying to
work with farmers in differentplaces and different landscapes
(08:09):
on different soils.
Dr. Tom DeSutter (08:10):
You know, sarah, you bring up a good point
.
It's almost like atrafficability map and it's
based on soil series or types ofsoils, right, and so when it's
too wet, it's too sticky, it's,you know, your traffic ability
just goes down.
But if it's too dry, like wetalked about, and you bring up
you know, and the soil is justtoo hard, the traffic ability is
(08:33):
just fine.
But the cultivation, thecultivability of that soil is is
is shearing, a lot of bolts,and so it's just an interesting
problem that is not unique toNorth Dakota, but it's not
uncommon in areas that havevertisols, that have these
high-strength swells somevertisol type soils in South
(08:55):
Dakota, and certainly we have aclientele down in South Dakota
as well.
Sarah (09:06):
Can you talk about where some of these vertisols might be
occurring in South Dakota aswell?
Dr. Tom DeSutter (09:13):
I'll use maybe an example.
So the Red River Valley ofTexas and Oklahoma, right, so
we're talking about lower lyingareas that may have, you know,
not necessarily annual flooding,but maybe there was some
depositional things when thesoils were formed or created.
So not unlike the bottom ofLake Agassiz, you know, things
(09:37):
settled out over time and thelast things to settle down were
the clays and the silts, and sothat's where you tend to have in
some ways a higherconcentration of clay in these
areas that were old lake beds ormaybe riverian areas that are
older, but that's, you knowwhere they are.
(09:59):
Maybe along the Big Sioux Riverbasin, you know things of that
nature, which I actually grew upalong the Big Sioux River in
Iowa, but we had more of the.
You know more of the, the loss,the windblown deposits in that
area and so very highlyproductive soils.
You know Iowa is has beenblessed by very good soil, very
(10:22):
good soils and and rainfallwhich is why it's.
You know, it does really well inagriculture.
Jodi (10:29):
I forget what order are that.
Is that also a mollisol?
Or is there another order thatthe windblown deposits are?
Dr. Tom DeSutter (10:38):
Yeah, it would be classified as a parent
material.
I don't think it necessarilyhas to have an order to it.
Paramaterial I don't think itnecessarily has to have an order
to it.
But, as a fun fact, if you wentto Puerto Rico those of you
that are thinking aboutvacationing Puerto Rico, the
island you know, out in themiddle of the Caribbean it has
10 of the 12 soil orders and soif you can find yourself on a
(11:01):
tour, a soils tour, you canvisit everything but gelisols,
which are the cold ones, whichpeople from Puerto Rico would
probably move to North Dakota ifthat was their soil order.
Sarah (11:16):
Permafrost is a gelisol, yeah.
Dr. Tom DeSutter (11:18):
And then so the andisols, which are the
volcanic and so.
But you know, you can go downto Linton, North Dakota, and you
can find all the volcanic ashyou want, right, I mean there's
a huge deposits of volcanic ash.
Sarah (11:31):
I did not know that.
Dr. Tom DeSutter (11:33):
I can.
I can hold some up.
You know that we actually wentand collected a bunch to see
what kind of, because oftentimesthese oxides in these, like
iron oxide as an example, has areally high retentive for
phosphorus, and so we have readthat this volcanic ash also can
(11:54):
retain phosphorus.
We did a bunch of studies hererecently and the volcanic stuff,
even though it does have someiron oxide in it it's mostly
silica oxide and other things.
Aluminum oxide doesn't have alot of good retentive properties
for phosphorus, but we got abunch of this mining ore
(12:18):
byproduct and it's about 30%iron oxide, percent iron oxide,
and so when you're thinkingabout also about parent
materials and where soils comefrom, understanding a little bit
about these properties helpsyou manage your fertilizer too
right.
If you have a high calcareoussoil in a field, your phosphorus
retention creating calciumphosphates, the odds of that are
(12:41):
much greater than they would ifyou don't have that free
calcium in those systems.
So not only do the work we dois related to environmental work
, but it's also applicable tothese landscapes and how you
manage these fertilizers.
Jodi (12:57):
Can we talk a little bit about that too?
And maybe pH that is the drumthat I will constantly beat, but
I think it's important to talkabout because it also discusses
some of these other like soiltypes and things that affect pH.
And sure, like for the mostpart, in a mollisol soil on a
typical prairie profile, right,we have a lot of that calcium
carbonate, probably not going tohave to worry about acidic
(13:19):
soils, but we have these acidsoil issues and I'm curious, you
know, what types of areas wouldwe typically see, or what kind
of landscapes or parent materialwould we expect to see a higher
incidence of acidic soils, orwhich ones are more prone to
become acidified over time in acropping system here in the
(13:39):
Northern Great Plains?
Dr. Tom DeSutter (13:41):
Yeah, you know , I certainly think the ones
that have plenty of calcium inthem, like lime.
The odds of seeing acid soilsin Walsh County or Grand Forks
County have got to be prettysmall right.
Jodi (13:54):
Right, and Sarah works at a farm just north of my house
and I live on an old Agassizbeach line in western Grand
Forks County.
But Sarah does have a farm Ifound some you did.
Sarah (14:07):
And I've got some that are two miles off of I-29 by
Hillsboro small percentage ofoverall Grand Forks and Traill
County.
But I mean you have to gridsample to find them are they in
the?
Dr. Tom DeSutter (14:19):
are they in the fives or are they in the
four fives?
Okay, yeah, I mean I've seensome stuff south of Dickinson
that we sampled that were like4.5.
But we kind of looked for thealuminum.
So as you get lower in pH, youhave more exchangeable aluminum
and then more hydrogen, becausehydrogen is really.
(14:42):
pH is a term called the power ofhydrogen, but it's also the
negative log of hydrogen isreally what pH is, a term called
the power of hydrogen right,but it's also the negative log
of hydrogen is really whatyou're after.
And so even a concentration oftiny concentration, one times 10
to the minus seventh moles perliter which we won't worry about
the units at this point that'sa pH of seven.
And so a pH of five is onetimes 10 to the minus fifth, and
(15:05):
so that's a pH of five.
And so, as you alter thathydrogen concentration, that's
what drives the pH.
That driving of the pH is whatdrives nutrient availability and
sort of like.
The availability of phosphorusis the main one we talk about,
right, and then the toxicitythat aluminum, aluminum 3 plus
(15:34):
would have on roots themselves.
And so managing these acidsoils is and will be complicated
right by the fact that you havearid environments.
The most common thing you do isapply lime, which is calcium
carbonate.
If we think about thesolubilities of salts, if you
think about gypsum, which iscommonly talked about as being a
liming agent, which it isn't,do not apply a gypsum if you, if
(15:59):
you think you're going tochange your pH.
Sarah (16:01):
Can I just reemphasize that, tom?
Yeah, if you guys did not hearthat, do not apply gypsum to
change your pH.
There you go.
Dr. Tom DeSutter (16:11):
There set Right, we got it set Anyway.
But the solubility of gypsum islike one US penny in a liter of
water.
So two bottles of water thatyou buy at the, you know those
500, those plastic bottles ofwater you buy by the case, two
of those and so.
But the solubility of calciumcarbonate is like 35 times less
(16:32):
than that.
So that's almost like takingthe face off of Lincoln off the
penny, and that's what willdissolve in that much water.
And so that's the complicationof in the Western part of the
state is you don't have enoughwater to actually dissolve, to
make the to, to dissolve thatsalt into calcium and carbonate.
The calcium is used to helpremove the aluminum and the
(16:56):
hydrogen off the soil exchangesites.
The carbonate is whatneutralizes, then that hydrogen
creates water and eventuallycreates water and carbon dioxide
.
And so if you don't have water,as we talked about before,
water is the great equalizer.
And so how do you manage waterand keep water and get more
water into the profile?
That's the biggest challenge,especially in arid and semi-arid
(17:19):
environments.
Jodi (17:20):
Okay, Another question I had kind of related to that.
We talked a lot in the lastepisode about just salty soils
in general and why here in theNorthern Great Plains we've got
more of them in other places.
I'm curious.
We've talked about calciumcarbonate, lime.
We've talked about gypsum,another salt, calcium sulfate.
Can you talk more about whatare the other common salts that
(17:42):
we have here?
Because I think when peoplethink salt they think table salt
, right, so sodium and chloride.
And a person might think, oh,if we're talking about salts in
the landscape, we're probablytalking about sodium chloride,
so we're going to have sodicityin that field.
But that's not the case.
Can you tell us more about whatour common salts are here in
the state?
Dr. Tom DeSutter (18:02):
Okay, so we go back to the point of what a
salt is, and a salt is an anionand a cation, and so in
non-aqueous, non-waterconditions, a salt is a crystal,
right?
Not the crystal, the big, youknow, wedding ring sort of
crystals that you can buy now,that are manufactured, but these
(18:24):
are crystals that formnaturally.
And so back to the maybe aconversation of on your.
You know, it's a hot day,you've been sweating all day and
you take off your hat and it'swet, and then you let it dry,
that's the salt that iscrystallizing on your hat, and
so that's what we have in thesoil.
And so we have salts that aremagnesium sulfate, calcium
(18:47):
sulfate, sodium sulfate, somesodium chloride, calcium
carbonate, of course, which is avery sparingly soluble, but
those would be kind of like themain ones that we would consider
to be the ones that are mostinfluential in crop production.
And so, as we think about howimpactful they are, there's a
lot of really good cropproduction.
And so, as we think about, like, how impactful they are, you
(19:07):
know there's a lot of reallygood crop production that is, in
calcareous soils, you can seethe line, but there's a lot, man
.
It is like good production.
Right and so, but the problemthe reason is, is those that
when it's wet, that calcium andcarbonate isn't negatively
impacting the plant.
Right and so.
If you have things likemagnesium sulfate, which it
(19:30):
takes almost, you know, like ahandful in a liter of water and
that's how much will dissolvewhere you can actually don't see
any particles in that water,well, that's a lot different
concentration in the soil,that's that's uh solubilized
than it is for calcium carbonate, and that's why the solubility
(19:51):
of uh, of salts, is what impactseventually crop production.
And so, like calcium sulfate,which is gypsum again, it was
that one penny size and a literof water you can farm in calcium
sulfate enriched soils.
Not a problem, right?
I mean it's you have calciumand you have sulfate and they're
both like necessary plantnutrients, and but they only
(20:13):
because its solubility is so lowit doesn't negatively impact,
you know, plant production.
Jodi (20:20):
So that's such a good, that's such a great point, cause
you know we talk about calciumcarbonate as being a salt, but
we never.
We really shouldn't worry abouthaving too much of it, besides
maybe having to apply morephosphorus because it can tie up
phosphorus at the higher pHs.
But, like you said, like evenin like my garden in Grand Forks
County, I can see that freelime in the surface of the soil,
(20:43):
but it's not negativelyaffecting my, my vegetable
production, because it's notsoluble in the soil, it's not
breaking down and it's notcausing salt damage to the
plants that I'm growing there.
Same thing with the crops andsame in the same area too.
Dr. Tom DeSutter (20:57):
Yeah, I mean, if you were, you know back to
you know back in the days of thecivil war when they salted
fields.
I mean the reason was to addsalt to decrease crop production
, right, and that was a way ofcontrolling the food supply.
But in the southwest part of theUnited States you also get 50
(21:18):
to 60 inches of rainfall a yearand so that washed through, and
then, I'm sure, after a coupleof years, it was fine, back to
its normal productivity, and sothe problem that we have is that
, as we, as we stated, notenough water to leach things
down, and if you do leach itdown, the atmosphere demands a
lot of water, so everythingmoves back up again, and so
(21:40):
that's that's a challenge thatyou, as agronomists, have to
recommend.
Sarah (21:45):
So I think that was a really great conversation about
salts, but so often we hear thisidea of what sodic soils are.
So really, what is thedifference between a sodic soil
and a salty soil?
Dr. Tom DeSutter (21:58):
Okay, so we use.
I had a conversation with JohnLee, the great John Lee from
AGVISE.
I had a conversation with JohnLee, the great John Lee from
AGVISE.
He had someone call one timeand said that his soil was sour.
Perfectly fine, a regional term, right.
But it took John a half hour tofigure out if his soil was what
(22:22):
we would consider to be sodicor saline, because sour was the
actual term.
And so if you look at a soiltest report and you have done on
that soil test report, solublesalts or electrical conductivity
, whichever lab you're using,and have them run a test for a
(22:45):
base saturation, and so what wewould normally see is that if a
soil has a percent sodium inthat base saturation that's
greater than five, and if thatsoil has an EC or a soluble salt
of less than one, we mightconsider that soil to be getting
(23:07):
close to the fact of of beingsort of in that sodic sort of
range.
And what that means is that youhave a lot more sodium in
comparison to calcium, magnesium, potassium, and so what?
What the problem with sodium isthat it likes to be hydrated,
it likes to be, it likes to besurrounded by water, right, it's
(23:28):
kind of like a it's kind oflike a rock star that has a lot
of people around them all thetime, right, they like to be
hydrated with people, and so,whereas calcium tends to be a
little more of an introvert butlikes to be coordinated with
just a couple of people, tendsto be a little more of an
introvert but likes to becoordinated with just a couple
people, and so that calcium onthe exchange sites coordinates
(23:50):
with the internal matrix of theclay and holds it together, and
so it's a flocculant, whereassodium likes to be hydrated and
it can't hold that clay sheetstogether very well, and so the
clay sheets tend to repel eachother, and then that's when you
get sort of like the swelling ordispersion.
And so that's why but it'slargely, largely regulated by
(24:13):
the overall electricalconductivity of the soil or the
soluble salt content.
You can have a soil with like areally high concentration of
sodium, but if the electricalconductivity is high, not a
problem.
The sodium isn't the problem,it's the high electrical
conductivity.
But that's what helps keep theclay sheets together is just the
(24:35):
chemical potential, if you will, of the inside of the clay
sheets and the outside.
And so when you see, when youhave what Sarah is describing as
a sodic soil you will haveoftentimes see the soil
particles, the clay particles,repel each other, and when they
repel each other they kind ofbreak apart and then they'll
(24:56):
kind of move down through thesoil profile over time and
that's oftentimes what you'llsee is what we call is a zone of
accumulation of clay and sodium, and so they're a lot easier to
sort of think about from thestandpoint of being separate
from saline soils, because theydevelop differently, but
(25:19):
unfortunately they get kind oflumped together into sour or
sick or something like that, andthen it becomes a little more
complicated to just kind oftease out what they are.
In Grand Forks County, walshCounty, most all of those soils
are probably what we would callboth saline and sodic.
They have a high concentrationof sodium but they also have a
high concentration of salt, andso we just kind of lump them
(25:42):
into that term.
Jodi (25:43):
So say, if somebody has a combination sodic and saline
soil, how should they approachmanaging that?
What should they tackle first?
Dr. Tom DeSutter (25:51):
Yeah, so the first thing is to manage the
water, and so likely those soilsthat have those conditions also
have a high water table, or,historically, have had a high
water table over time, whichallows that water to wick up
into the root zone, and then,when the water evaporatesick up
into the root zone, and then,when the water evaporates, the
salts are left behind, and sothe first thing to do would be
to manage the water, becausewhen you manage the water,
(26:14):
you'll manage the soluble salts,and when you manage the soluble
salts after that, that's whenyou can start to manage the
sodium, and so you may have toadd things like gypsum, which is
a sparingly soluble salt, butit's actually fairly effective.
It's one of the it is the mostcommon amendment to use for
(26:37):
sodic soils.
Do not add gypsum to a salinesoil, because you're not going
to do anything.
Sarah (26:43):
So I think this is a really important point, because
people get confused as to wheregypsum is appropriate and what
it's appropriate for.
If you have a low pH situation,adding gypsum is not going to
help you.
If you've got a sodic soilsituation, gypsum is going to be
the amendment that is going tohelp you to manage that sodic
(27:06):
soil situation.
Dr. Tom DeSutter (27:08):
Correct, correct.
And I have heard people tryingto use beet lime and things of
that nature and the solubilityof lime is just so low that
you're basically just adding abunch of particles, if you will,
to that soil and it might helpwith the traffic ability or the
(27:29):
tilth of how well you can tillthat soil, but at the end of the
day it's not the preferredamendment at all for sodic soil.
Jodi (27:39):
When I think about the solubility of because I used to
struggle with that too likethinking about solubility.
I remember talking about thatin class but I never really
thought about why it wasimportant or what was applicable
about it.
But, like, when I think aboutand describe to people lime
versus like gypsum, I thinkabout lime that's formed from,
like the crushing of all theseclamshells and ocean mollusks at
(28:01):
the bottom of an ocean, right,and then, over time, as millions
and millions of years push themtogether, you get this
limestone.
But, like you think about it,if lime is made out of the
shells of these ocean critters,they're going to be made out of
something that isn't very watersoluble, or like it doesn't
dissolve in water becausethey're living in these things,
(28:21):
right.
So that's how I always rememberabout like why, why lime is so
insoluble versus something likegypsum that is, is relatively
more soluble.
Dr. Tom DeSutter (28:31):
Yeah, I mean it's relatively more soluble not
, you know, very soluble, but itis.
But it is more soluble.
And so you know, where do weget gypsum?
North Dakota is blessed withenergy resources, right?
I mean, we have our coal, wehave our natural gas, we have
oil, we have wind.
We haven't seen any solar farmscome in.
(28:52):
That can be a topic for a sideconversation.
But in 1990, when the Clean AirAct was brought into play, the
coal facilities had to scrub outthe sulfur from the burning of
our coal, because we have toremember that all this work to
(29:13):
get coal is to basicallyevaporate water to drive a
turbine, and so we have toremember that that's why we get
the coal.
It's not just because they'reburning coal, but it's to
evaporate water to move aturbine right and so.
And so they had to scrub outthat air, and what they do is
they use what's called forcedwet oxidation.
Basically they put calciumcarbonate, again using calcium
(29:36):
carbonate, and they wouldactually use that to then pull
the sulfur and the mercurymercury in a way out of the
stack, and then they're leftwith a product that they have to
do something with, and so theLeland Olds plant in North
Dakota has converted thatcalcium sulfite to calcium
sulfate which is now used for inour agricultural production.
Jodi (30:00):
And that's kind of the same process of like beet too.
So for anybody here in thevalley that uses sugar beet lime
to control a phantom isis ormaybe increase tilth, or if
you're using it to haul back toan area with low pHs to amend
the soil, just like the calciumoxide is used, or like the lime
is used to scrub sulfur from thesmokestacks, the sugar beet
(30:22):
processing plant use thatcalcium carbonate, that lime, to
refine the sugar, and thenwe're left with a byproduct at
the end that we can then use outin fields.
So it's kind of the same thingbut a little bit more intense in
the energy process, coming outwith gypsum at the end.
Sarah (30:39):
It would be remiss of us to overlook drain tile when
we're talking about sodic andsaline sodic soils.
Right, you know, D.
r DeSutter, you were talkingabout managing the water and
really needing to manage thatwater if we're going to manage
salts.
So drain tile as we previouslydiscussed in the previous
episode, that is an excellentway of trying to manage water
(31:01):
coming into the surface.
In areas where water isactively rising to the surface,
well, in sodic soils, that cancertainly create some challenges
where, if you've leached all ofthe other salts besides the
sodium out of the system, youcan be left with that sodic soil
which, in essence, can end upsealing up to itself if we're
not going to try to remediatethat some way.
(31:22):
So how do we manage that?
Dr. Tom DeSutter (31:26):
I would say the first thing to manage that
is to monitor through soiltesting, and so that's the main
way that we identify some ofthese, lump them into this
category of problem soils,whether it's acid, whether it's
saline, whether it's sodic orwhatever.
But yeah, soil testing.
Annually.
Soil testing in the same spot.
(31:46):
Now, of course, if you went tothe same spot and there's a hole
, move over a little bit andsample that, right.
But yeah, the annually sample.
And I think you know some of ourlongest term data is actually
collected by AGVISE.
They had a very strongforesight in trying to figure
out if tile drainage was working, and so and it has over time,
(32:08):
but it's taken years, right andso, but yeah, annually soil
sampling.
Speaking with your agronomistsor speaking with your soil
testing lab knowledgeable peopleabout the topic, you can call
us we have two new extensionfaculty that are coming on board
, Dr.
Carlos Perez and Dr.
Brady Gottel, and so they willalso be available to answer any
(32:31):
of these questions.
But yeah, annually soilsampling.
Monitor over time.
If, in fact, when that ratio ofyour base saturation, percent
sodium becomes out of line withyour electrical conductivity of
your soil, that's when you wouldhave to consult.
Jodi (32:50):
And I would want to say too, when we talked about soil
testing for tile drainage when Iwas working at AGVISE, one of
the things that we try to conveyto folks too is that it's
important to sample to the depthof tile as well, not because,
like if you're doing a one footsample and figuring out what the
sodicity and the salinity ofthat one foot is, it's good to
(33:10):
know and it may be indicative ofwhat's below, but most of the
time we're putting in tile linemuch deeper than a foot, and so
it's going to be important toknow, if you've got any sodicity
problems farther down, wherethat tie line is going to be and
where that water is going to beflowing to as well.
Dr. Tom DeSutter (33:24):
Yeah, you know , I think on an annual basis
maybe you could just stick withyour you know zero to six, six
to 12, or you know six to 24,but periodically, maybe every
three or five years, make sureyou get to depth right to
monitor that.
And certainly you know, we know, that with gravitational water,
that means the water that'sgoing to move down through the
(33:46):
force of gravity, that's goingto carry salts with it and it's
probably going to increase theconcentration of salts to depth
at some point, leaving the toppart maybe less salty, if you
will.
And so that's the area that youwant to make sure that you can
handle.
It's really really difficultover time to manage things you
(34:07):
can't see right, and so takingcare of what you can sample
regularly is key.
Sarah (34:15):
So when you were talking about that soil testing level,
where we really need to makesure that we're in consultation
again, that's that 5% sodium onthe base saturation.
Dr. Tom DeSutter (34:25):
Correct, yeah.
And so I'm just visuallylooking at the AGVISE soil test
report and on the lowerright-hand corner you have
what's the percent basesaturation on that.
And so, just by happenstanceprobably, Mr.
Deutsch put zero to 5% on thatsodium and actually through our
(34:47):
research, through actually agood friend of Sarah's who did a
lot of the work, Kathy, wedetermined that 5% was really
kind of the limiting factor, andso anything greater than 5%
should be paid attention to,greater than anything less than
5%.
Sarah (35:06):
And I also.
Before we end this conversation,I also want to make sure that
I'm bringing us back to thatstudy that you were talking
about that John Lee was doingwith egg vice for all those
years, because I followed thatstudy for a number of years as
an agronomist, constantlygetting continuing education.
There was a field not so faraway from Northwood the soil
(35:28):
sampling lab that John wasassociated with with AGVISE and
there was a part in that fieldthat was saline- sodic and then
there was also areas in thatfield that were saline- sodic
and then there was also areas inthat field that were saline and
they drain tiled that and theydid remediate or or apply gypsum
in conjunction with that draintile at that point in time and
(35:50):
the crop production on that wasokay at that point in time but
it was watched very carefullyand it was soil sampled very
carefully.
So from a real standpoint, ifyou are in a situation where you
have a saline sodic soil, youcan manage that effectively and
actually drain tile.
But you need to be careful thatyou're being very diligent
about how that's being handled.
Dr. Tom DeSutter (36:13):
Yeah, and you know we always our phone lines
are always open.
We, you know, we hope thatpeople utilize us.
We are here we are part of theland grant mission to bring
education out to ourstakeholders and to answer those
questions just the same.
But we have an exceptionallyhigh number of very, very, very
(36:37):
good crop advisors in this state, and so I think that's the one
thing that we're blessed withtoo is like we have an
exceptional group of cropadvisors in this state, and so
if you have questions, pleaseconsult your crop advisor, if
you have one.
Jodi (36:52):
And I think that goes back to having a lot of the crop
consultants in the state went toNDSU and they were able to take
classes like soils and land usefrom professors like you.
Again, we appreciate so muchthe time you took with us today,
the pedagogy and the teachingthat you give to students at
NDSU.
Sarah (37:11):
And thanks for putting up with us in your class.
I really appreciate that.
You know, when Tom startedteaching our class, he began
saying oh good, this is whereyou're all sitting.
Once I get you memorized whereyou're all sitting in this room,
you'll, you'll, you'll besitting in here forever.
So near the end of thatsemester, I walked in before
everybody before Tom was thereand I said okay, everybody,
(37:33):
let's switch spots today.
And it was the day that he hadto hand out papers.
It was great that he had tohand out papers.
Dr. Tom DeSutter (37:38):
It was great.
So that was.
I remember that vividly, so Ijoke ha, ha that the only reason
I give homework is so I canfigure out their names, and so
now everything's online in asense, so it's not as much fun.
But yeah, I never really gradedthem, I just wanted to hand
them back to see what your nameswere.
Jodi (38:00):
All of you aspiring teachers take note.
Dr. Tom DeSutter (38:04):
So I don't always remember students' names
per se, but I know where theysat and so that's you know.
That's how I sort of relate myexperiences.
A little bit is like the visual, the memorization of, like what
was happening during that timeand you know, it goes back to
you know, we know exactly wherewe were when 9-11 happened,
(38:25):
right, I mean, you know exactly.
And so I try to bring that intothe classroom, just so I
remember, try to remembereveryone, because sooner or
later a student's going to comeup and say, oh, do you remember
me?
And most of the time you know Ican say honestly, yes.
And so oh, yeah, you sat back inthe left-hand corner by the
window.
I remember where Jodi sat.
(38:45):
I remember where Sarah sat.
Sarah (38:48):
Well, thank you so much for joining us today.
This would end the previousepisode as well.
It was a great conversation.
It's always fun geeking outwith you about soils a little
bit and just how we seelandscapes and everything.
So thank you.
Dr. Tom DeSutter (39:03):
My pleasure and I hope everyone has a safe
cropping and harvest season inthe future.
Jodi (39:10):
Thank you so much, tom.
And with that, remember, withGK Technology we have a map and
an app for that.
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