Discussion of Lab
Activities
Lab Activity #1
Objective of Laboratory Activity #1
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This exercise allows you to familiarize
yourselves with studying soil profiles and
designating soil horizons/layers.
How to complete Lab Activity #1
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Separate each profile into 3 major horizons on
the basis of color.
Find the depth and thickness of each of the
three horizons in the series description
Describe the color or colors of each horizon.
Use colors such as red, yellow, brown, black,
and gray.
Lab Activity #1 – Cecil Soil Series
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First, let’s look at the
soil profile of the Cecil
soil series.
Do we see differences in
color?
Try to separate out 3
horizons or layers.
Cecil Soil Series
Horizon Depths & Letter
Designations
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Now that we’ve separated
out the 3 horizons, let’s put
a depth to each layer.
Sometimes this is difficult
because we may have a
wavy boundary between
horizons, such as with the
Cecil soil series.
Therefore, we record the
depths by using the tape as a
guide.
Cecil Soil Series
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The first layer goes
from 0-6 inches.
The second layer goes
from 6-14 inches.
The third layer goes
from 14-64+ inches.
1st layer
2nd layer
3rd layer
Horizon Designations
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Using your knowledge
of master horizon
designations, label the 3
horizons.
The top layer is a dark
brown color and would
appropriately be
designated as the A
horizon.
Horizon Designations
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The second horizon is a
whiter color than the top
and bottom horizons
and looks “leached”.
Therefore, we would
call the second layer an
E horizon.
The third horizon looks
to be accumulating
material, so we would
designate this as a B
horizon.
Cecil Soil Series
A
E
B
Soil Series
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Let’s go to the official soil series description and
double-check our horizon designations.
Here are the horizon designations from the soil series:
Ap--0 to 8 inches; dark yellowish brown (10YR 4/4) sandy loam; weak medium granular structure; very
friable; slightly acid; abrupt smooth boundary. (2 to 8 inches thick)
Bt1--8 to 26 inches; red (10R 4/8) clay; moderate medium subangular blocky structure; firm; sticky, plastic;
common clay films on faces of peds; few fine flakes of mica; strongly acid; gradual wavy boundary.
Bt2--26 to 42 inches; red (10R 4/8) clay; few fine prominent yellowish red (5YR 5/8) mottles; moderate
medium subangular blocky structure; firm; sticky, plastic; common clay films on faces of peds; few fine
flakes of mica; very strongly acid; gradual wavy boundary. (Combined thickness of the Bt horizon is 24 to
50 inches)
BC--42 to 50 inches; red (2.5YR 4/8) clay loam; few distinct yellowish red (5YR 5/8) mottles; weak
medium subangular blocky structure; friable; few fine flakes of mica; very strongly acid; gradual wavy
boundary. (0 to 10 inches thick)
C--50 to 80 inches; red (2.5YR 4/8) loam saprolite; common medium distinct pale yellow (2.5Y 7/4) and
common distinct brown (7.5YR 5/4) mottles; massive; very friable; few fine flakes of mica; very strongly
acid.
Soil Horizons
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Although the official soil series description
does not show an “E” horizon, we can tell
from the picture that we do, in fact, have a
leached layer.
Color
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Now look at the colors of the 3 layers and fill out the
table in your lab.
It should look like this:
Horizon
Depth
Color
1. A
0-6”
Dark brown
2. E
6-14”
White
3. B
14-64+”
Reddish brown
Lab Activity #2
Objective of Laboratory Activity #2
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This exercise allows you to use your
knowledge of the 5 soil forming factors to
determine differences between soils.
How to complete Lab Activity #2
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Use the official series description to compare
differences in soil forming factors among the given
series.
In the tables, the soil forming factors are listed in the
left column.
For each factor, decide whether differences occur
between the listed soil series.
If no differences occur, write “no differences" in the
middle column.
In the right hand column, identify how the differences
in each soil forming factor affected the properties of
the two soil series.
Lab Activity #2
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Let’s first
visually
compare the 2
soils that we
are studying.
Norfolk
Cecil
Parent Material
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If we go to the official soil series descriptions
for both soils, we see that Norfolk soils occur
in “marine deposits or fluviomarine deposits”
(listed next to Parent Material) and Cecil soils
“formed in residuum weathered from felsic,
igneous and high-grade metamorphic rocks of
the Piedmont uplands” (in the first paragraph
of the description).
There is a difference between the parent
materials.
Parent Material
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We can see that
there is a color
difference but
there is also a
difference in
texture due to the
different parent
materials (read
through the rest
of the soil series
description).
Norfolk
Cecil
Climate
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Norfolk Soil Series:
Mean Annual Air
Temperature (type
location): 62 degrees F.
Mean Annual
Precipitation (type
location): 49 inches
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Cecil Soil Series:
Mean annual
precipitation is 48
inches and mean annual
temperature is 59
degrees F near the type
location.
Is there a difference? No, not really.
Biotic Activity
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Biotic activity is not specifically discussed in
the soil series descriptions, therefore, we must
look at the “big picture”.
The climates for the soils are relatively similar
so will we have similar biotic activity?
Most likely, yes.
Topography - Slope
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Norfolk Soil Series:
Slope: 0 to 10 percent
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Cecil Soil Series:
Slopes range from 0 to
25 percent.
Is there a difference? Yes, slightly.
What is the difference? Let’s look.
Topography - Slope
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We can see that
there is a color
and difference in
thickness in the A
horizon.
The A horizon of
the Norfolk
(slope 0-10) is
more welldeveloped than
the Cecil soil
(slope 0-25).
Norfolk
Cecil
Topography – Landscape Position
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Norfolk Soil Series:
Landscape: Lower, middle,
or upper coastal plain.
Landform: Uplands or
marine terraces
Geomorphic Component:
Interfluve, side slopes
Hillslope Profile Position:
Summits, shoulders,
backslopes
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Cecil Soil Series:
The Cecil series consists of
very deep, well drained
moderately permeable soils
on ridges and side slopes
of the Piedmont uplands.
Is there a difference? No, not really,
both occur on the side slopes.
Time
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Time is not explicitly discussed, so we must
look at all of the clues given.
Norfolk occurs in the lower, middle, or upper
coastal plain.
Cecil soils occur in the Piedmont uplands.
Which is older? Soils near the coast or soils in
the Piedmont region?
Soils in the coast are younger and soils in the
Piedmont are older.
Time
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We can see that
there is a color
difference
between the soils
and the Cecil soil
series (older) has
more layers,
including a
leached E
horizon.
Norfolk
Cecil
Soil Forming
Factor
Differences
Norfolk/Cecil
Observable
Difference
Parent Material
marine sediments/
residual rock
Climate
62°&49”/59°&48”
No Difference
Sandy/clayey
color
N/A
Biotic Activity
Similar climates
No Difference
0-10%/0-25%
Slope
Landscape Position
Side Slopes
No Difference
Time
Coastal
Plain/Piedmont
Younger/older
N/A
Depths and colors of
A horizons
N/A
Less development in
Norfolk (color &
horizons)
Now, you can try the rest.
Good Luck!!