Lesson 11

Slip-Sliding Away

 

Activity:

Students will investigate the rate of soil loss under different conditions. This activity illustrates one of the most fundamental principles of soil and water conservation - the protection grass and other plants give soil against rain and running water.

Content Standards Addressed:

Common Core State Standards

 

Materials:

  • Two clementine boxes (or other produce boxes with solid bottoms), lined with scrap plastic sheeting (for example, an empty potting soil bag).
  • Leftover grass seed (rye or fescue is good because it grows fast). If time does not permit growing grass from seed, use a slab of sod or transplant some small, low profile plants into the soil. Continue with Part 2 of the activity.
  • Potting soil.
  • Water.
  • Coffee filters.
  • Spray bottle.
  • Watering can.
  • Two large containers (for holding water run-off). 
 
Part 1:
 
1. Fill produce boxes with potting soil to within 1 inch of top.
2. Sprinkle grass seed heavily on the soil in one of the boxes.
3. Cover seed with coffee filters.
4. Lightly spray the coffee filters with water. Keep them moist until the grass seed sprouts (about 4 days).
5. After the seed sprouts, remove the filters. Keep the soil lightly misted so it doesn't dry out.
6. In 10 days, the grass will have grown tall enough to continue with Part 2 of the investigation.
 
 

Part 2:

1. Set both boxes side by side at the edge of a table. Place large containers on chairs or stools beside the table's edge, to catch water that will pour off the boxes.

2. Fill the watering can with water.

3. Place some books or a board underneath one end of the box containing soil, to tilt it toward the edge of the table.

4. Holding the watering can about a foot above the soil surface, water the soil slowly.

5. Ask the students to note what happens.

  • The water will run off the bare soil into the large container, taking soil with it. The flow will stop soon, but the container will contain muddy water.

6. Repeat steps 2-5 with the box containing soil and plants/grass.

  • Not as much water will flow from this box. The water will be relatively clear. It will take longer for the flow to start and it will continue longer.
 
Discuss:
  • What are the three ways that grass (or plants) in soil slows water run-off?
  • How does water run-off contribute to erosion and sedimentation problems?
  • Have you seen bare soil with no vegetation? How did the soil get that way? What happens to this type of area when it rains?
  • How does the running water change the surface of the land? What can be done to stop this erosion?
 

Extension:

"The Dust Bowl," a term coined by AP writer Robert Geiger, referred to a region that included parts of Colorado, Kansas, New Mexico, Oklahoma and Texas. In the 1930s, soil depletion from years of overgrazing and relentless farming combined with a decade of drought to produce an erosion crisis of epic proportions. With no vegetation to anchor the topsoil, winds created dust storms that continued for days, covering everything, suffocating animals and making breathing nearly impossible for humans. With their lives in ruins, entire families left the area to seek work elsewhere. Some managed to make a meager wage, others were left penniless. The drought finally ended in the fall of 1939. By that time, Americans had learned a long-term, expensive lesson. Motivated by government incentives, farmers began practicing soil conservation techniques like planting native trees and grasses, terracing sloping fields and rotating crops.

Your students will be fascinated by the photos and stories within the pages of Martin Sandler's The Dust Bowl Through the Lens and Years of Dust by Albert Marrin. (See Level 2 Additional Resources for more information.)​ In response, they might write a short fictional first-person account of growing up during the time period. What did they see and experience? What lessons did their families learn about soil conservation? ​