1. Soils

2. Soils
Soil is the loose covering of broken rock particles and decaying organic matter
Soil is the end result of physical and chemical weathering.
Soil forms as rock is broken down be weathering and mixes with other material on the surface.
The longer a soil has been forming, the thicker it is.
Climate has a great affect on soil formation. Temperature and precipitation play an important role.

3. How is soil created? Decaying organic matter is called humus.
It is often leaf litter that is broken down by decomposers.
Ex. Are ants, worms, etc.

4. Soil Formation
During its development, soil forms in layers vertically.
Solid bedrock from which weathered pieces of rock first break off is known as the parent rock.
The weathered material then rests on top of the parent rock.

5. Residual vs. Transported
Residual soil is soil that comes from the bedrock that it sits upon.
A transported soil is soil that has been moved from a different location

6. Soil Profile A soil profile is a vertical sequence of soil layers.
A distinct layer is called a soil horizon
The three major layers are: A, B, C

7. Soil Horizons
A Horizon- Topsoil- Soil rich in humus and usually dark colored
B Horizon- Subsoil-Rich in clay minerals
C Horizon- Weathered bedrock (parent rock).

8. Texture Size of soil particles is soil texture.
Particles are classified according to size.
In order from largest to smallest they are:
Gravel
Sand is the largest mm
Silt is the middle mm
Clay is smallest >.002 mm

9. Fertility and Color
Soil Fertility is the measure of how well a soil can support plant growth.
A soils’composition and climate are main factors in determining its color.
Red/Yellow= Fe oxidation
Dark Colored= Humus
Gray/Blue= low O2

10. Loam A loam is a soil that is equal parts of clay, sand and silt.
It is the best for growing plants!

11. Soil Types
Climactic conditions are the main influences on soil development.
Polar Soil
Temperate Soil
Desert Soil
Tropical Soil