Lab Introduction
This activity will help you visualize some of the physical properties of soils. Specifically, you will investigate:
- Texture: Texture relates the amounts of sand, silt, and clay-sized particles in a soil sample. Sandy soils are coarse-textured, and they feel gritty between your fingers. A soil made mostly of silt is medium-textured; it feels smooth like flour between your fingers. A clayey soil is fine-textured and it will feel sticky between your fingers. Most soils are a mixture of sand, silt, and clay and are a type of loam. Depending on where you live and the environmental conditions around you, your local soil may be sandy, silty, clayey, or loamy.
- Color: Color is usually a result of the soil’s parent material, though it can also derive from local environmental conditions. Red, yellow and orange colors in a soil usually indicate the presence of iron. Grey colors are sometimes associated with soils that are water-saturated for much of the year. Soils very high in organic matter are usually dark brown or black.
- Porosity and Permeability: Porosity describes the number of open spaces, or pores, between individual soil particles. Permeability describes how connected those pores are and how well water can move downward through the soil. A soil that drains water very quickly must have high porosity and permeability. On the other hand, a soil with very slow drainage (meaning that water has a hard time moving downward through it) will have low porosity and/or permeability.
You will use a flowchart to identify which of the 11 texture classes is represented for each of your dirt samples.
Describe your process of using the flowchart to find the texture class for each sample.
In the flowchart the textures are repesented by the rounded boxes. You will need the following as you work through this lab:
