1. Soil – NOT a dirty word! Soil Formula
Soil = inorganic material + organic material + air + water
TIME

2. Soil Texture 4 basic types
Sand – feels gritty; packs together when wet but cannot hold shape on its own
Silt – feels like talcum powder; flows when wet
Clay – feels slick; becomes malleable when wet – can hold any shape
Loam – a mixture of all three of the above.

3. Soil Triangle

4. Why is Soil Texture important?
Determines soil fertility, suitability for construction, etc.

5. Controls of Soil Formation
Parent Material
Time
Climate
Biological Factors
Slope

6. Soil Formation in action – the Soil Profile
Definition – a cross–section of soil from the surface to the parent material
Since soil-forming processes operate top down, a layering effect eventually develops.
Layers in the soil profile are called horizons.

7. Soil Horizons - TOPSOIL
O – (for Organic) includes the organic, or humus layer.
A – contains mostly mineral material with some organic material

8. Soil Horizons - SUBSOIL
E – (for Eluviation) – leaching occurs here
B – leached material accumulates here, can form a claypan.
C – unaltered parent material

9. Soil Taxonomy