1. Soil

3. Characteristics
Regolith - The layer of rock and mineral fragments that cover almost all land as a result of weathering.
Soil is the part that supports the growth of plants.

4. Soil Composition Mineral matter (broken-down rock)
Organic matter (humus)
Air
Water
Good soil = at least 50% mineral and organic matter!

5. Make sure you know how to read this soil chart!!
Texture
Soil has different particle sizes.
Texture supports ability for plant life.
Loam (in the center) is best because it holds water
Make sure you know how to read this soil chart!!

6. Soil Chart
What type of soil is made up of 20% clay, 40% silt and 40% sand?
Medium Loam
What type of soil is made up of 40% clay, 40% silt and 20% sand?
Clay
What type of soil is made up of 30% clay, 10% silt and 60% sand?
Sandy Clay Loam

7. Soil Formation Factors
Parent material- the source of the mineral matter.
Time- the longer it forms, the thicker it gets.
*Climate*- has the greatest effect. ● Similar soils can be made in the same climate, even if they have different parent material!

8. Soil Formation Factors
Organisms- aid fertility
-plants- main source of organic matter
-microorganisms-decomposition
-burrowing animals mix things up!

9. Soil Formation Factors
Slope - Steep or flat?
flat areas = little erosion & drainage
steep slopes = greater erosion

10. Soil Profiles
Soil Profiles- show the characteristics from the surface down.
Soil Horizons- each individual zone

11. 3 Main Horizons A Horizon – called topsoil B Horizon – called subsoil
Consists mostly of organic matter, lots of insects, fungi and microorganisms – where most decomposition takes place
B Horizon – called subsoil
Consists of clay particles washed out of A horizon
C Horizon –
Consists of weathered parent material (rock)

12. Water is a big factor…it causes the most soil erosion!
But so are WE…
Human activities remove the vegetation that covers soil!
Without cover, the soil is EASILY eroded!