Basic Soil Science: Soil Horizons Notes

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Basic Soil Science  BSS4  Soil Horizons

Basic Soil Science: Soil Horizons Notes

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Basic Soil Science  BSS4  Soil Horizons

Basic Soil Science: Soil Horizons BSS4.1

Horizon Matching Cards

• “Organic”

Horizon O • Does not have to be 100% organic matter material • thin O horizons • Do not occur in

cultivated areas • Destroyed by plowing

• Mineral soil

• Dark color formed by Horizon A 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

• Grayish brown to white color Horizon E • 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

• Layer that shows the most variation because

Horizon B 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

• Weathered

Horizon C • Unconsolidated geological material below A or B horizon • Can dig with a spade • Not changed very

much by soil-forming processes

• Stands for “bedrock”

Horizon R • 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

• Occurs between A and Horizon AB 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

• Occurs between A and Horizon BA 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

• From B to C horizon

Horizon BC • 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 Smooth Boundary

Abrupt Wavy

Clear Irregular

Gradual Broken

Diffuse Transitional Boundaries

Basic Soil Science  BSS4  Soil Horizons

Basic Soil Science: Soil Horizons BSS4.3

Subordinate AB horizon Divisions of Horizons

BA horizon Oi horizon

BC 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 Human Role in the Description of Horizon Name Horizon Characteristics Story

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 a. Pedon another b. Profile

_____ 2. The smallest volume that can be called soil c. Horizon d. Organic matter _____ 3. Removal of soluble minerals from the soil by e. Transitional horizon movement of water through the soil over long f. Parent material periods of time g. Weathering _____ 4. A layer of soil that is approximately parallel to h. Erosion the earth’s surface i. Leaching j. Saturated _____ 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

a. R horizon

11. ______b. O horizon 12. ______c. C horizon 13. ______d. A horizon

14. ______e. B horizon

f. E horizon 15. ______

16. ______

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 a. Pedon another b. Profile

A 2. The smallest volume that can be called soil c. Horizon d. Organic matter I 3. Removal of soluble minerals from the soil by e. Transitional horizon movement of water through the soil over long f. Parent material periods of time g. Weathering C 4. A layer of soil that is approximately parallel to h. Erosion the earth’s surface i. Leaching j. Saturated 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

a. R horizon 11. B b. O horizon 12. D

13. F c. C horizon

14. E d. A horizon

15. C e. B horizon

16. A f. E horizon

Basic Soil Science  BSS4  Soil Horizons