17.5 Cracking The Code Of Salty Soils

We break down what “salty soil” really means and why salinity and sodicity demand different fixes. We share how to properly diagnose a soil as saline, sodic, or saline/sodic through soil sampling and testing, to avoid turning a manageable patch into concrete.

We also discuss....
• defining normal, saline, sodic, saline-sodic with soil test EC and sodium results
• why salinity causes drought-like stress without wrecking structure
• how sodicity drives clay dispersion and pore collapse
• when salts keep clays flocculated in saline-sodic soils
• risks of leaching or tiling without a sodicity management plan
• sampling depths: 0–6, 6–12, 12–18 inches for diagnosis
• using pH as a supporting clue for sodicity
• prioritizing amendment before drainage to prevent sodic blowups

More information on management of salty soils here: https://www.ndsu.edu/agriculture/extension/publications/managing-saline-soils-north-dakota

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/

Episode Transcript

Sarah (00:00):
And now it's time for a Tiny Byte of knowledge.

Jodi (00:13):
Gumbo.
White spot.
Krusty.
Alkali.
Gumbo.
Saline.
Kosha patch.
These are all terms I've heardpeople call areas and fields
that are salt-affected, but theyaren't all created equally.

(00:34):
There are some differenceshere, and we're going to talk
about those on thesesalt-affected areas of our
fields.

Sarah (00:40):
That's right, Jodi.
There are three major types ofsalt-affected soils that we can
really talk about and thinkabout.
We're going to break that alldown in this episode of Tiny
Bites.
First of all, I think it'simportant for everybody to know
that if you want to try to, bythe numbers, identify and define
a salty soil, you have to soilsample with that in mind.

(01:03):
And it's important that youpull soil samples zero to six,
six to twenty four, sample.
You can even go down andpartitions and take a look at
soil cores and six-inchincrements and have these
parameters analyzed.
But make sure that you'regetting those soils tested for

(01:24):
electrical conductivity on aone-to-one basis, as well as the
extractable sodium percentage.
You need to have those twoparameters.
pH can also be a helpfulindicator in some instances.

Jodi (01:37):
Getting these soil test numbers are crucial for
diagnosing and determiningwhat's actually going on and
what the best plan of attack formanagement is going to be.
That's right.

Sarah (01:49):
And just backing up a little bit, there are three
major types of salt-affectedsoils.
There are saline soils, sodicsoils, and saline sodic soils.
We also have another categorythat we'll lump into there that
we can call normal.
In other words, anon-salt-affected soil.

(02:12):
So let's just break that down.
What is a normal soil?

Jodi (02:17):
Yeah, so just using like routine soil test data number.
So a routine soil test backthat's got EC, it's got percent
sodium.
Um, what you're gonna look foris it's gonna be considered a
normal soil if the EC levels areless than one and the percent
sodium number is less than fivepercent.
We start to move into thatsaline category once we get over

(02:41):
E or once we get ECs over one,and then a sodium percentage
less than five percent.
And then on the sodi side,we're looking at soils that have
an EC less than one, a percentsodium number greater than five.
And then we have the thirdcategory, which is a combination
of both, when we have both highsalts or ECs over one, and high

(03:04):
percent sodiums with percentsodiums of five or greater.

Sarah (03:09):
So that is definitely the breakdown of those three
categories.
And again, a saline soil is asoil that, by the
characteristics and how thatacts, Jodi just went through the
numbers.
That is a soil that is highlyaffected by salts.
And what that means is in thatscenario, it's going to be hard

(03:30):
for a plant.
It's going to be difficult fora plant to actually take up the
soil solution.
Salt-affected fields actuallysometimes act as if they're
almost in a drought situationbecause it's just so hard for
that plant to take up moistureand the soil solution in that
scenario.
However, the actual physicalproperties of the soil don't

(03:51):
change that much.
So you can still have somewhataggregation.
Usually they do tend to be abit more saturated, just again,
because plants aren't able totake up that much moisture in
that scenario.
So they might be a little bitwetter.
But generally speaking, thesoil physical parameters don't

(04:12):
change a whole lot.
Now, in a sodic soil, somethingthat's very interesting is that
often we might even see soilpHs greater than 8.5 in that
sodic soil scenario.
Also, sodium-affected soilstend to have some very
interesting soil physicalproperties that go along with

(04:35):
them.
Sodic affected soil has what'scalled clay dispersion occurring
in the soil.
What that means is that theindividual clay particles
actually disperse or break awayfrom the main aggregate.
Now, clay particles areactually really small.
You can only see clay particleswith a micron microscope.

(04:57):
So they're very tiny.
So when you have those actuallydispersing and breaking away
from the main aggregate, thesoil solution tends to look very
cloudy.
And what happens then is thatwhen that soil dries out, after
those clay particles havedispersed, those clay particles

(05:18):
will collapse on top of eachother without aggregating or
flocculating back togetheragain.
And then all of the pore spacebecomes clogged in that soil and
water is not able to infiltratethrough.
So in this instance, that sodaaffected soil, after it dries
out again like that, actuallyalmost becomes as hard as

(05:39):
concrete.
And it's very indicativesometimes when you see that
soil, that sodium affected soilout there.
The whole field might be dryfor a long time.
But that one place that hadthat change in the physical
properties of the soil, theremight just be a little bit of
water sitting there because itabsolutely cannot infiltrate

(06:01):
through.
So the soil physical propertiescan be greatly affected by a
purely sodic soil.
Saline sodic soil is veryinteresting because it has both
the saline component as well asthe soda component.
What's interesting is that inthis scenario, those clays are

(06:23):
not able to disperse as theywould in a purely sodic
situation.
And so what happens is thephysical properties of that soil
maintain and water can actuallystill infiltrate through
because it's the salts from thestaline component that keep
those clay particles, what wecall flocculated or maintained

(06:45):
together in the littleaggregates.
If you have a scenario, thenon-sodium salts are able to
leach through the system, thenyou get left behind with just
the sodium, at which point intime that can take over as a
sodium-affected soil.
And the soil physicalproperties again can change to

(07:06):
have that dispersion issue.
And again, where the clays cancollapse upon themselves and not
allow for water to infiltratethrough.

Jodi (07:14):
That is such a great way to describe that third category,
the saline sodic.
It took a long time for me towrap my head around that concept
that when you have bothsalinity and sodicity, you might
only see the salinity showingitself.
But yeah, if you leach away allthat groundwater that has those
salts in it, those salts kindof buffer and help that

(07:34):
dispersion to not be there.
And that's why it's soimportant to get your soil
tested so that you don't end up,you know, putting tile in
place, leaching those, thosesalts, salts that are helping to
flocculate or keep that sodicsoil together, leaching those
away and just having thesadicity left behind.
So it's so important to havethose numbers to help you figure

(07:55):
out, you know, what order can Ido?
What, how can I address thesituation and avoid ending up
with just a sodic soil in theend, which is very hard to
manage.
Okay, what we think of as thethree major types of
salt-affected soil are going tobe our saline soils, our sodic
soils, and our saline-soticsoils.
Again, saline, that's going tobe high ECs and not a high

(08:19):
percentage of sodium.
Sodic soils, high percentage ofsodium, but not a high EC.
And then, of course, oursaline-sodix, which are a mix of
both.
So if you think you've got oneof these areas, go out, take a
soil sample.
Like Sarah said, zero to six.
Um, it's even helpful to dozero to six, six to twelve,
twelve to eighteen to figure outwhere these levels are.

Sarah (08:42):
Well, with that, I don't have a lot more to say about
salts.
Maybe it's time for us todisperse.
Tune in next time for a tinybite of knowledge from GK
Technology, where we have a mapand an app for that.