Earth Science, Chapter 10, Section 3

Soil Lab

Earth Science, Chapter 10, Section 3

Summary: Students will learn about the qualities for different soil types through experimentation.

Background: Students should be familiar with the text, Chapter 10, Sections 1-3.

Objectives:

·  To instruct students on different soil textures and their qualities.

·  To demonstrate the different levels of infiltration for different types of soil.

·  To have students interact with soils in an experiential way by following a “texture by feel” method of soil identification.

·  To demonstrate how soils separate based on the components.

Materials:

·  Five 100 ml graduated cylinders

·  4 funnels

·  Filter paper or coffee filters

·  4 stopwatches

·  Plastic wrap

·  Rubber band

·  Base soil samples: sand, silt, clay

·  Potting soil

·  Local soil samples (or ask students to bring soil from home)

·  Prepared soil samples for texture experiment

·  Trays or beakers for soil samples.

·  Handouts: Soil triangle, soil texturing worksheet

Preparation:

Before the lab, prepare soil samples to be used by students in the “texture by feel” segment. Using the soil triangle as your guide, create one sample per group for testing. Label each sample with a letter and record the compositions. Some “recipes” are below.

Procedure:

Infiltration Demonstration

1. In the front of the room, place funnels in beakers and add filter to the funnel.
2. Add a small amount, approx. 2-3 tbsp., of each type of soil – sand, silt, clay and potting soil or loam – into each funnel.
3. Ask the students to hypothesis which soil will infiltrate the water most quickly and most slowly.
4. Ask four student volunteers to slowly pour 50 mL of water over each sample at the same time.
5. Have four student volunteers use the stopwatches to time how long it takes fort he water to infiltrate.
6. When water has finish passing through the soil, measure the amount of water collected for each type of soil.
7. Record results on the board and discuss.

Texture by Feel

1. Give each group one sample each of dry sand, clay and silt. Have students touch each and record observations in their lab notebooks.
2. Ask students to add a small amount of water to each sample and test the feel again. Record observations.
3. Show students the soil triangle and explain that soil often contains a mixture of these components. Soil scientists, in the field, use touch to determine the type of soil they have found. Then they relate that finding back to the soil triangle to determine the soil’s approximate composition.
4. Distribute soil texturing handouts and mystery soil samples.
5. Lead the class through the process of using the soil texturing handout.
6. Have students record what soil they believe they have. Ask them to determine, using the triangle, what the approximate soil composition might be.
7. Compare results with known composition for the sample.
8. Repeat the process with a sample from school or home.

Determining Composition through Layering

1. Show the short video at: http://www.youtube.com/watch?v=knrmCbctGEA
2. Add 2-3 tablespoons of a local soil sample to a graduated cylinder.
3. Fill the cylinder with water almost to the top.
4. Cover with plastic wrap and secure with a rubber band.
5. Shake vigorously.
6. Let sit overnight
7. Determine the composition of the soil sample.

Assessment:

Students have completed the experiment satisfactorily if they have properly identified the soil and/or can explain why they came to their results.

Resources:

Soil-Net.com: http://www.soil-net.com/dev/page.cfm?pageid=activities_sheets

Soil Science Web Page: http://soil.gsfc.nasa.gov/index.html

NRCS Soil Education: http://soils.usda.gov/education/index.html

The Dirt on Soil: http://school.discoveryeducation.com/schooladventures/soil/index.html