Perhaps you have made a “cup of dirt” from pudding. But you can turn this simple snack into a tasty science activity by creating a soil horizons parfait!
For this activity, you will make a parfait with 6 layers to represent the 6 horizons. This is an entertaining and tasty way to teach your students about soil horizons during a gardening, soil science, or agriculture unit in your classroom.
Background Information: Layers in Soils
Did you know soils have layers? If you viewed a vertical cross section of soil, you would see up to six main layers. Each layer looks different and is made of a unique mixture of sediments and organic matter.
We call the layers “soil horizons”. Each of the six soil horizons is given a letter: O, A, E, B, C, and R. The upper two horizons, O and A, are called topsoil. Topsoil is rich in organic matter compared to the lower layers. Topsoil is where plants grow, so it is important in agriculture and ecology! A healthy topsoil promotes healthy plant life.
What are the main soil horizons?
Here are the 6 main horizons, from top to bottom:
- O Horizon: Decaying organic matter at the soil’s surface
- A Horizon: Soil rich in both organic matter and coarse sediments
- E Horizon: Coarse soils, which lost their clay and soluble minerals to downward leaching
- B Horizon: The “subsoil”; clay and dissolved minerals build up in this layer
- C Horizon: “Parent material” of soil: pieces of partially weathered rock
- R Horizon: Hard bedrock beneath the soil
Activity: create your own soil horizons parfait!
Materials
- Tall, clear cups or glasses
- Spoons
- Graham crackers
- Yogurt
- Jam
- Fresh Cut Fruit
- Granola
- Paper towels
Directions
Build your own model of soil horizons by making a parfait. Each layer represents a different horizon. Students should add these layers to a tall glass or clear plastic cup.
- R horizon: pieces of whole graham cracker, to represent bedrock.
- C horizon: crumbled gram crackers to represent the soil’s parent material made from partially weathered rock in this horizon.
- B horizon: yogurt, which is smooth and creamy like the fine-grained clay and soluble minerals found in this horizon.
- E horizon: jam, because gritty seeds in jam represent the coarser sands and silts found in this horizon.
- A horizon: fresh fruit, because this horizon is rich in organic matter.
- O horizon: granola, to represent decomposing organic matter like crunchy leaves on the surface of the soil.
Soil Science with Wild Earth Lab
This soil horizons parfait activity comes from my complete Soil Science Unit. The unit is full of many activities like this one for teaching students all about soils.
Explore curriculum from Wild Earth Lab:
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