1. Soil Origin and Development
INTRO TO SOILS – CH 2
Soil Origin and Development

2. THE SOIL BODY Pedon – smallest body which can be called a soil
Three-dimensional
Typically extends down to depth of plant root

3. THE SOIL BODY Polypedon – two or more contiguous pedons
Form a Soil Series
Soil Series are the lowest official category in the soil taxonomy

4. THE SOIL BODY Weathering of rocks and minerals forms pedons
Two types of weathering:
Physical weathering
Chemical weathering
Eventually, a layer of young soil develops

5. THE SOIL BODY
Three types of rock:
Igneous
Sedimentary
Metamorphic

6. THE SOIL BODY Five (5) Soil Forming Factors Parent Material Climate
Living Organisms (plant and animal)
Topography
Time

7. THE SOIL PROFILE Soils change in response to their environment
Four processes of change:
Additions
Losses
Translocations
Transformations

8. THE SOIL PROFILE
As a soil ages these changes lead to formation of horizontal layers known as:
Soil Horizons
These horizons may be exposed when digging into the soil revealing the:
Soil Profile

9. THE SOIL PROFILE Master Horizons: A, B, C O, A, E, B, C, R
Coded layers of horizon with distinct characteristics
Not all horizons will always be present!

10. THE SOIL PROFILE
Subdivisions and Suffixes may further define the master horizons
e.g. AB, Ap, Bt, Bky
See Appendix 3 for suffix explanations