1. The Soil Profile

2. The 6 Soil Roles A Soil’s role includes: Serving as a foundation
Emitting and absorbing gases
Providing habitat
Interacting with water
Recycling nutrients
Supporting human settlements

3. The 5 Factors of Formation
Soil is formed by…
Parent Material: the original “Mom & Pop” soil transported from elsewhere, usually by wind or water, at different speeds
Climate: the amount, intensity, timing, and kind of precipitation that breaks down parts of ecosystem (i.e. rocks, trees) into soil
Topography: Slope and Aspect affect the angle of the land and position toward/away from the sun that soil will be exposed to
Biological: Plants, animals, microscopic organisms, and humans interact with soil in different ways
Time: the amount of time it takes for the four factors (above) to interact with each other

4. What is a Soil Profile?
A Soil Profile is a vertical cross-section of layers of soil found in a given area. Below are two examples of soil profiles.

5. What is a Soil Horizon?
Soil horizons are the layers in a soil profile used to classify soil types.
Horizons based on color, texture, roots, structure, rock fragments, and any unique characteristic worth noting.
Master Soil Horizons are depicted by a capital letter in the order (from top down): O, A, E, B, C, and R

6. O-Horizon The “Organic Matter” Horizon
Surface-layer, at depths of 0-2 feet
Dark in color, soft in texture
Humus - rich organic material of plant and animal origin in a stage of decomposition
Leaf litter – leaves, needles, twigs, moss, lichens that are not decomposing
Several O-layers can occur in some soils, consisting only of O-horizons

7. A-Horizon “Topsoil” or “Biomantle” Horizon
Topmost layer of mineral soil, at depths of 2-10 feet
Some humus present, darker in color than layers below
Biomantle - most biological productive layer; earthworms, fungi, and bacteria live this layer
Smallest and finest soil particles

8. E-Horizon The “Leaching Layer” Horizon
Small layer between A & B horizons
At depths of feet
Light in color, mainly sand & silt
Poor mineral and clay content due to leaching – the loss of water-retaining plant nutrients to the water table
Soil particles larger than in A horizon but smaller than in B horizon

9. B-Horizon The “Subsoil” Horizon At depths of 10-30 feet
Rich in clay and minerals like Fe & Al
Some organic material may reach here through leaching
Plant roots can extend into this layer
Red/brown in color due to oxides of Fe & clay

10. C-Horizon The “Regolith” Horizon At depths of 30-48 feet
Made up of large rocks or lumps of partially broken bedrock
Least affected by weathering and have changed the least since their origin
Devoid of organic matter due to it being so far down in the soil profile

11. R-Horizon The “Bedrock” Horizon At depths of 48+ feet
Deepest soil horizon in the soil profile
No rocks or boulders, only a continuous mass of bedrock
Colors are those of the original rock of the area

12. How to Make a Soil Profile
Ingredients List
Directions
3-4 copies of Master Soil Horizons Worksheet
30 sticky notes per group (7 per person)
3-4 pairs of gloves
1 large glass bowl
1 one-cup measuring cup
1 whisk
1 spatula
3.5 cups skim milk
2 packages vanilla Instant Jell-o pudding mix
1 tiny Ziploc bag Coconut w/green food coloring + raisins
1 small Ziploc bag crushed chocolate graham crackers & frosting
1 medium Ziploc bag Chocolate chip & Vanilla wafers & gummy worms
1 small Ziploc bag crushed Vanilla wafers only
1 medium Ziploc bag crushed graham crackers
1 large Ziploc bag crushed Oreo cookies
1 large Ziploc bag crushed chocolate chips
In large glass bowl, whisk 3.5 cups milk with 2 pkgs. vanilla Instant Jell-o pudding mix until smooth. Let stand 5 minutes.
While waiting, refer to your version of “The Soil Profile” powerpoint to review order that horizons should be. You have A, E, B, R, O, C, and vegetation as horizons. It’s up to you to order it!
After 5 minutes, use spatula to scoop pudding in middle of bowl, allowing for the “dry ingredients” (the bags of various crushed up cookies) to encircle the pudding along the sides of the glass bowl. This creates a vertical cross-section of soil layers visible to you.
Use sticky notes to label each horizon on outside of bowl.
Fill out Master Soil Horizons Worksheet using observations of Soil Profile Dessert.
Turn in worksheet to teacher. Only until you and your team members turn in their worksheet can you enjoy the delicious snack. You’re finished!