Soil
and Agriculture:
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Soil Erosion
Introduction | Invitation | Exploration | Explanation | Taking Action | Conclusion
Introduction:
Soil erosion in agricultural systems is a very important problem to manage.
The productive layer of dirt is called the humus or topsoil. If this layer
is eroded away, then the ground is very unproductive in producing crops.
Soil can be eroded away by wind and water. High winds can blow away loose soils from flat or hilly terrain. Water erosion generally occurs only on slopes, and its severity increases with the severity of the slope. In many parts of the world much of the wind erosion occurs in winter when the ground is frozen, but the upper most soil layer is dry and loose. Water erosion occurs during the spring with the thawing and melting action of the snow.
There are a number of different methods of reducing soil erosion.
Soil erosion is the detachment and movement of soil particles by the erosive forces of wind or water. Soil detached and transported away from one location is often deposited at some other place. While soil erosion can be controlled, it is almost impossible to be completely stopped.
Objective:
- Students will list different types of soil erosion and describe ways to control the erosion.
Materials:
- Samples of Dirt, Sand, Gravel, and Rocks
- Plastic Bins
- Watering cans or bottles (May use coke bottles with a lid with holes.
- Bottle Caps
- Tissues
Invitation:
- What is soil erosion?
- Have you seen examples of soil erosion?
- Describe examples of soil erosion that you have seen. What do you think causes this soil erosion?
Exploration:
Following are four different investigations of soil erosion. Your teacher will instruct your team which one(s) you should do. Record your observations, data and conclusions on a chart like the one below.
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Activity 1:
Purpose: To see if particle size will affect erosion.Materials: Sand, Dirt, Gravel, Rocks, Plastic Bin
Procedure:
- Mix sand, dirt, gravel, and rocks.
- Pile up the mixture in one end of the plastic bin.
- Using a watering can or a cup with holes, water the pile equally on the top so that the water looks like rain.
- Water evenly across dirt. Observe the movement of the various size particles. Data: Describe what the dirt pile looked like as you added the water to the top of the pile. Record which particles moved first, which moved second, etc.
Conclusion: How does the size of the particles affect the rate of erosion? Would the amount of water, either volume of water or the hardness of the rain, effect the rate of erosion? If you wanted to control erosion on a hill, what type of particles would you use to do this?
Activity 2:
Purpose: To see how objects embedded in dirt will effect the rate of erosion.Materials: Dirt, bottle caps, plastic bin
Procedure:
- Pile the dirt in the middle of the plastic bin into a mound or hill of dirt.
- Press the bottle caps into the dirt on top of the mound.
- Water the dirt mound evenly across the top with a watering can or cup with holes so that the water looks like rain.
- Observe how the water effects the dirt.
Data: Record your observations about how the water affects the dirt and the rate of erosion.
Conclusion: Do the bottle caps affect the rate of erosion? How can you apply this lesson to a hill of dirt in your area? (How would you help prevent erosion on a dirt hill?)
Activity 3:
Purpose: To compare erosion on two sand hills, one with grass and one that has no vegetation.Hypothesis: Do you think there will be a difference in the erosion of the two hills? What do you think the difference will be?
Materials: Sand, plastic bin.
Procedure:
- Take 2 plastic bins and put a mound of sand in the center of each bin. Put a tissue over one mound of sand. This is to simulate grass on the hill.
- Water each hill evenly. Observe the erosion on each hill.
Data: Describe your observations about the rate and amount of erosion on each hill.
Conclusion: Would planting grass on all hills change the rate of erosion?
Activity 4:
Purpose: To compare the rate of erosion on two dirt hills, one with loose dirt and one with packed dirt.Hypothesis: Do you think there will be a difference in the rate of erosion on the two dirt hills? If so, what do you think the difference will be?
Materials: Dirt, plastic bin, watering can or cup.
Procedure:
- Put a loose mound of dirt in the center of one bin, and pack the dirt tightly into a mound in the other bin.
- Water each mound evenly with a watering can to simulate rain.
Data: Record your observations about the rate and amount of erosion on the two dirt hills.
Conclusion: Does packed soil erode faster, slower, or the same as loose soil? How can you apply this knowledge to your everyday life?
Explanation:
- Discuss the activities of this lesson in a class discussion.
- What have you learned about erosion?
- Describe some things that affect the rate of erosion.
- How could you help slow down erosion on a hill?
Taking Action:
- Have the students develop an erosion-saving example that would be applicable to their everyday lives.
- Have students develop an action plan that allows them to share their erosion-sharing example with students via the Internet.
- Have students describe erosion problems in their area and list ways that could be used to control the erosion.
- Let each student illustrate their plan and present it to the class.
You have seen how erosion can affect the landscape. In another lesson you will apply these strategies to planting seeds in various types of soil to determine the impact on erosion.
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