1. Warmup
List three things you might find in soil

2. Soil
Soil- The loose covering of particles covering the Earth’s bedrock. It is made primarily of particles of rocks, minerals, and humus – decaying organic matter.
Horizons- The layers of soil. Horizons are defined in by obvious physical features, such as color and texture.

3. Residual soil - Soil formed from the rock material beneath the soil.
Transported soil - Soil that has been moved from its place of origin.

4. Soil Horizons
Topsoil- (A horizon) the top layer of mature soil containing organic matter and the most weathered rock.
Subsoil - (B horizon) the layer below the topsoil made of partly weathered rock, clay sized particles, and very little organic matter.
Bedrock- (C horizon) rock layer underneath useable soil
Parent Material

5. Not all horizons may be present!
Humus- (O horizon) dead material on top of the soil column. Rich in nutrients.
Not all horizons may be present!

6. Leaching- minerals and nutrients transported away by water

7. Soil Profile: The vertical sequence of soil layers.
Soil is the result of weathering and biological activities. Humus “improves” the soil texture and helps it to hold water. Can take 100 years for 1 cm of soil to form!

8. Soil Texture:
Sand- any rock particle less than 2 mm but more than 0.05 mm
Silt - any rock particle less than 0.05 mm but more than .002 mm
Clay- any rock particle smaller than mm

9. Soil Texture classified according to % of the various sized grains: clay, silt, and sand.

11. Using the soil triangle, what type of soil would you have if your sample was composed of: 30% Clay 50% Sand 20% Silt

12. 30% Clay
20% Silt
50% Sand

13. Soil Type:
Sandy clay loam

14. Soil Textural Triangle

15. Soil structure
Soil Structure- the arrangement on soil particles

18. Soil Types Often classified based on climate: polar temperate desert
tropical
other
Climatic conditions are the main influence on soil development