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Basic Soil Science BSS4 Soil Horizons

Basic Soil Science: Soil Horizons Notes

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Soil Horizons: Why advocate?


Basic Soil Science: Soil Horizons Notes

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Subordinate Divisions: Horizon Boundary:


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 .



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 .



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



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



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



Horizon

Boundary

Abrupt

Clear

Gradual

Diffuse

Smooth

Wavy

Irregular

Broken

Transitional

Boundaries



AB horizon

BA horizon

BC horizon

Subordinate

Divisions of

Horizons

Oi horizon

Ap horizon



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



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



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: 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

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