Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons Notes
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Soil Horizons: Why advocate?
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons Notes
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Subordinate Divisions: Horizon Boundary:
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.1
Horizon Matching Cards
Horizon O • “Organic”
• Does not have to be
100% organic matter
material
• thin O horizons
• Do not occur in
cultivated areas
• Destroyed by plowing
Horizon A
• Mineral soil
• Dark color formed by
additional humus
• Granular or fine blocky
structure
• Can be easily crushed
• Thickness ranges from a
few inches to more than 30
inches
• Every cultivated
agricultural soil has an A
horizon
• Important in maintaining
soil fertility and favorable
environment for root
growth
• Needs to be protected from
erosion and compaction .
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.1
Horizon E
• Grayish brown to white
color
• Not present in all
Missouri soils
• Occurs beneath an O or
A horizon
• Light in color because
nearly all iron and
organic matter have
been removed
• E for “eluviation”
• Found in most forested
soils and several prairie
soils
• Has noticeably less clay
than the B horizon
found beneath it
Horizon B
• Layer that shows the
most variation because
of soil forming
processes that
influence the soil
• Can be bright
yellowish-brown,
reddish-brown, or red
in color
• Blocky or prismatic
structure
• Has more clay than
other horizons
• Clay films may be
visible .
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.1
Horizon C • Weathered
• Unconsolidated
geological material
below A or B horizon
• Can dig with a spade
• Not changed very
much by soil-forming
processes
Horizon R • Stands for “bedrock”
• Cannot easily dig with
spade
• Occur directly beneath
any of the other
master horizons
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.1
Horizon AB
• Occurs between A and
B horizons
• Dominated by
properties of A, but
some B properties are
still evident
• Dark colors associated
with organic matter
are fading because
organic matter is
decreasing
• Structure may change
from granular to
subangular blocky
Horizon BA • Occurs between A and
B horizons
• More characteristics
of B horizon than A
• Structure is same type
as B, but less strongly
expressed
• Color is a little darker
than B or clay content
may be less
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.1
Horizon BC • From B to C horizon
• B properties are
dominant, but some
evidence of C is
present
• Clay content may be
less than maximum in
B, but more than in C
• C is structureless, but
C has structure
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.2
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.2
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.2
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.2
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.3
Horizon
Boundary
Abrupt
Clear
Gradual
Diffuse
Smooth
Wavy
Irregular
Broken
Transitional
Boundaries
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.3
AB horizon
BA horizon
BC horizon
Subordinate
Divisions of
Horizons
Oi horizon
Ap horizon
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.4
Soil Horizon Story Evaluation
Create a story about soil horizons. Each master horizon (O, A, E, B, C, R) will be personified and assigned
a character role. To personify the horizon means to attribute human characteristics to something
nonhuman. Be sure each horizon’s name and human characteristics embody “who” the soil horizon would
be if it were a person.
Complete the table below to help create the story. Remember, a story has a beginning, middle, and end.
This story needs to be at least 5 paragraphs and include all six horizons.
Here are story themes to help spark ideas—western, romantic comedy, fantasy, science fiction, mystery,
poetry, historical fiction, crime fiction, and satire.
Soil
Horizon Description of Horizon Name
Human
Characteristics
Role in the
Story
O
A
E
B
C
R
AB
BA
BC
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.4
Story Title: ____________________________
Expectations:
Description of each soil horizon completed accurately
______/15
A name is given to each horizon that embodies the horizon description
______/12
At least 3 human characteristics are listed for each horizon.
______/18
A story line is clearly developed and each character has an identified role in the story
______/18
The story has a beginning, middle, and end. Is at least 5 paragraphs in length
______/15
Strong and descriptive words are used
______/6
Correct grammar, punctuation, and spelling are used
______/10
Clearly and creatively applies elements of personification with success
______/6
Total ______/100
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.5
Soil Horizons Evaluation
Matching:
_____ 1. Gradual changes from one master horizon to
another
_____ 2. The smallest volume that can be called soil
_____ 3. Removal of soluble minerals from the soil by
movement of water through the soil over long
periods of time
_____ 4. A layer of soil that is approximately parallel to
the earth’s surface
_____ 5. The changing of rocks into soils
_____ 6. The sum of all plant and animal material, living
or dead, that is mixed into the soil
_____ 7. When all the pores of a soil are full of water
_____ 8. A vertical section of soil that allows you to see
all the horizons that are present
_____ 9. The original geologic material from which the horizons of a soil are formed
_____ 10. Loss of valuable topsoil by the action of wind or water
11. _________
12. _________
13. _________
14. _________
15. _________
16. _________
a. Pedon
b. Profile
c. Horizon
d. Organic matter
e. Transitional horizon
f. Parent material
g. Weathering
h. Erosion
i. Leaching
j. Saturated
a. R horizon
b. O horizon
c. C horizon
d. A horizon
e. B horizon
f. E horizon
Basic Soil Science BSS4 Soil Horizons
Basic Soil Science: Soil Horizons BSS4.5 KEY
Soil Horizons Evaluation
Matching:
E 1. Gradual changes from one master horizon to
another
A 2. The smallest volume that can be called soil
I 3. Removal of soluble minerals from the soil by
movement of water through the soil over long
periods of time
C 4. A layer of soil that is approximately parallel to
the earth’s surface
G 5. The changing of rocks into soils
D 6. The sum of all plant and animal material, living
or dead, that is mixed into the soil
J 7. When all the pores of a soil are full of water
B 8. A vertical section of soil that allows you to see
all the horizons that are present
F 9. The original geologic material from which the horizons of a soil are formed
H 10. Loss of valuable topsoil by the action of wind or water
11. B
12. D
13. F
14. E
15. C
16. A
a. Pedon
b. Profile
c. Horizon
d. Organic matter
e. Transitional horizon
f. Parent material
g. Weathering
h. Erosion
i. Leaching
j. Saturated
a. R horizon
b. O horizon
c. C horizon
d. A horizon
e. B horizon
f. E horizon