A Soil Profile


ANDY: So are the organic matter
horizons really thick here? JUSTIN: They’re very
thick organic horizons, which allows for the
development of spodosols. ANDY: Great. Will we get to see some
sandy leached E horizons? JUSTIN: Hopefully we should. These are very sandy soils, and they
allow for the movement of water. ANDY: All right. So Justin, I was wondering. You never really told me, but how
did you get interested in soils? What got you interested? JUSTIN: Soils are the connection between
the non-living and the living world. So we have the rocks and minerals that
provide the nutrients for the plants, and then we have plants
and other organisms that live in the soil as a home. So it’s this interaction between
the biota and rocks and minerals that makes it a very
fun medium to study. ANDY: And you’re from California. Are the soils very different in
California than in the Northeastern US? JUSTIN: So growing up
in Southern California, we have very different soils. We have soils that lack
a lot of the horizons. They have maybe an A
horizon, a B horizon, but here, we actually get to see
horizons like the organic horizon, and we see the E horizon, and
very, very red B horizons. So that makes it very
special– something that you don’t see in the
rest of the United States. ANDY: Wow. That’s great. So you’ve been to the site. I haven’t. What are we going to see? What are we going to see here? JUSTIN: So we should see some
very beautiful spodosols here. These soils haven’t been disturbed, so
they have very deep organic horizons. We should have very deep E horizons
and very, very red B horizons. So they’re very
characteristic, very colorful, and some of the most beautiful
soils you’ll see in America. ANDY: So the path is
just up the road here? Let’s go take a look. JUSTIN: So right now we’re
the Mascoma Highlands. We’re just on the foothills of
the White Mountain National Forest here in New Hampshire, which is
along the Appalachian Mountains. And we’re going to be digging here just
north of some of these wetter areas so that we have the climates and
the conditions for these spodosols. Well, we have deciduous
and coniferous vegetation, and it’s well drained so
these soils aren’t soggy. They hold onto water long enough for
the development of the spodosols. But they are not so well drained that
we don’t have horizon development. ANDY: OK. JUSTIN: So it’s a nice mix. ANDY: So they’re oxidized cells. They’re aerobic. JUSTIN: They’re aerobic. ANDY: Decomposition going on. JUSTIN: Yes. ANDY: OK. Great. All right. Should we go in and take a look? Dig some holes? JUSTIN: Absolutely. ANDY: Sounds good. JUSTIN: So this area looks,
actually, very flat, undisturbed. It doesn’t look like it’s wet. ANDY: So like you were saying
before, pretty well drained? JUSTIN: Yes. ANDY: Let’s take a look
around and find a place. JUSTIN: Yeah. ANDY: Do we want to pull that? Now that we’re not protecting that
face, we can pull it closer, yeah? JUSTIN: Yeah. Thanks. ANDY: So typically,
when you look at a soil, you have an A, a B,
and a C horizon– the A being the topsoil, the B
being the mineral soil, and the C being the unaltered material,
much like the parent material. This is a very different soil. So Justin, tell us about this soil. JUSTIN: So here we have
the typical spodosol, which is the state soil of
Vermont and New Hampshire. It’s characterized by
this deep organic horizon. So how we characterize soil horizons
is by the material that they’re made of and what’s been changing
in each horizon. So here from the top, we have
these leaves, so this is the– ANDY: Undecomposed leaves, essentially. JUSTIN: Next, we have the accumulation
of different types of organic matter. So here we can see some material
that looks like decomposed wood, and we know that it’s
dominated by organic matter by actually feeling
it and looking at it. So if you take a piece, it actually
has a very greasy feel to it. Below that, we have the mineral soil. This leached, this white E
horizon, E standing for eluviation. So whereas iron, organic matter, and
aluminum is then leaching out of. So that leaves it with a
ghost, very white color. ANDY: OK. JUSTIN: Below that, we have the
accumulation of organic matter. But this is no longer organic matter
input directly from the leaves. We actually have decomposition, and
then translocation of organic matter from the organic horizon into the E
horizon, and then into the Bh horizon. ANDY: OK. So O, E, Bh, and then? JUSTIN: So below this Bh horizon,
we have this orangey-red horizon. So that’s the accumulation and
precipitation of aluminum and iron oxides that gives it its
red and orange color. So below this, we then
lose the orange color and reddish colors to just a
brown, a light tan, an olive color. And that’s from the
unweathered parent material. So it hasn’t had accumulations of
any organic matter or iron oxides to give it any color. ANDY: OK. So we’ve got an O, an E, a Bh a
Bs, and then lower B horizons. Is this your favorite soil? JUSTIN: So this is a
very beautiful soil, and it is absolutely my
favorite type of soil. ANDY: The spodosol– Northeastern,
North Central United States. JUSTIN: Yes, absolutely. ANDY: OK. So we said that soils
are typically A, B, and C horizons– A being the
top soil, B being subsoil, and C being closer to parent
material or the original material from which the soil formed. But here, we’re in a
forest and we’re seeing this spectacular spodosol, which
is characterized by a very thick O horizon coming from the organic
material– needles, leaves, and twigs. Below that is an E horizon,
or an eluviated horizon. Below that is a series of B horizons–
Bh for humus, Bs for sequioxides, and then grading into
the parent material. That’s what we talked about today. Spodosols indicate a very long
period of time of soil formation, and they’re a fascinating
and beautiful soil.

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