Soil and erosion unit: Section 2

This unit will involve descriptive information on North Carolina soil types and how the presence of plants affects soil erosion. This section should be begun only after completion of Soil and erosion unit: Section 1.

A lesson plan for grades 9–12 Science

By Amy Robertson

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Related topics

• Learn more about environmental science and science.

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Learning outcomes

Students will understand:

• The effect of vegetation removal on soil fertility.
• The relationship between climate and soil formation (descriptive).
• Environmental concerns in regards to soil mismanagement and predictability of the possible effects of soil mismanagement.
• Analyze common farming and agricultural practices to determine their impact on soil and the environment.

Teacher planning

Time required for lesson

2 weeks

Materials/resources

• vocabulary sheets for students
• textbook
• materials for lab activities, listed with the lab procedures

Pre-activities

Students should have informative objectives completed during Section 1, such as introduction of soil formation and soil types, as well as the knowledge completed on the processes involved in soil formation. Visual knowledge of soils through demos by teacher as well as hands on activities demonstrating soil formation, creation of a model of a soil profile for mature soil, and closure which will involve the student’s integration of English to write small paragraphs using terms they have learned as a result of this lesson.

Activities

Preliminary questions:

• What does soil erosion do to water quality?
• How do plants help prevent soil erosion as well as who and what causes soil erosion?
• What can be done to prevent the erosion of soil?

Discussion: soil/water as our two most important resources. Description of sedimentation in the water and its interference with fish life, reservoir fill-in, and the increase in the cost of drinking water.

Lab activity: Plants and soil loss

• pre-lab discussion, discussion of attachment on deforestation and soil erosion, formulate a hypothesis
• set up six stations with four lab partners per station
• materials needed:
  • two cardboard boxes, approximately sixteen-by-twelve-by-four-inches
  • two large plastic trash bags
  • two pouring vessels (I will use large liter containers)
  • samples of both soil and sod
  • two bowls
  • two sticks, approximately one inch thick
  • scissors

Directions: obtain the boxes and at one end of each one, cut a ‘V’ 1¹/₂ inches deep in the center. Line each box with a plastic trash bag to make it watertight. Cut a piece of sod (grass) to fit inside one of the boxes. Trim the grass with scissors to about one inch high. Fill the other box with soil from the same place without the grass, only soil. The idea is to have the same kind of soil in the boxes, one with grass and the other one bare. Set the boxes on a table so the V-cut end extends over the edge. Place the sticks under the other end to tilt the boxes. Put the bowls beneath the V-cuts of each box. Fill the two liter containers with five-hundred milliliters of water and pour the water on both boxes at the same time, and at the same speed. Begin timing the flow of water from the boxes as the first drip begins to occur. Have a student time each box. Make sure that each container is held twelve inches above each box. Pour the water steadily and make sure it is at the same speed. When the dripping stops, answer the following questions for each box type:

• How long in minutes or seconds before water flowed into the bowl?
• How long did the flow of water into the bowls last in minutes timed?
• How much water flowed into each separate bowl? (measure by liter container by pouring back into it)
• Was the water in each separate bowl clear, partly clear, or cloudy?
• Gather all analysis in lab stations. Make comparisons between the two soil types.

Reflection: Do you think that grass helps to prevent soil erosion, and if so, why?

Discuss: What happens to soil types as they are affected by environmental conditions? Put into play: sedimentation. Small open discussion on the causes of soil erosion-in particularly as in North Carolina, small and big farmers, and builders. Inclusion should be weathering, water erosion, glacial erosion, coastal erosion, and wind erosion. Introduce attachment of shoreline erosion and discuss.

Discuss/Laboratory Project: Prevention of soil erosion, such as blanket grass planting, pile rocks, silt fences, as well as farming techniques that could interplay such as contour farming and conservation tillage.

Small teacher demo on contour farming and control of erosion: use two large round low dishpans, two liter containers, sample of soil, and a pencil. Application: put same amount of soil in each pan and form a mound in each one. Make sure they look the same. With a pencil or finger, make rows up and down one hill and circles around the other hill. Sprinkle approximately 250 milliliters of water (from the same height, which should be around twelve inches) and also at the same speed on each hill. Look at the water at the bottom of the hills.

Materials needed for the lab (six lab stations with four students at each):

• plastic lab trays
• sandy soil
• metric ruler
• small wooden blocks of wood
• twigs or very small branches
• toothpicks
• fresh grass clippings
• dried peas or beans
• spray bottle filled with water
• fork
• very narrow strips of cut carpet
• materials of choice to be blended with soil (examples: sand, bits of clay, composted organic material, metal, and plastic)
• notebook
• pen or pencil

Question and Answer: Which hill had the least erosion? Why?

In conclusion, I pull everything together in a large laboratory project. It is called “Bulldog Model Farm”

The purpose of this is to make several inferences as to why weather conditions can make our land very susceptible to soil erosion. The model is done, along with its variations, to observe the effects of erosion in more detail and to study ways to reduce erosion.

First we need to do a pre-lab discussion on the above concepts, and begin to gather our necessary materials.

Procedure:

1. Fill the tray with sandy soil, building the hilltops to a height of 5–10 centimeters, and making valleys and depressions where streams and ponds will form. Do not add water to the model at this point.
2. Add small blocks of wood, plastic or metal to represent the house and farm buildings; add twigs to represent trees; and add toothpicks to represent fences.
3. Spread grass clippings over the areas that represent the pasture and an alfalfa field. Stick blades of grass upright into the soil in rows to represent the corn in the cornfield. Place small dried peas or beans in rows to represent potato plants in a potato field.

Action/Reaction:

• After the model is constructed, simulate precipitation using a spray bottle set on the “fine” setting. Continue spraying until water begins flowing in the valleys and accumulating in the pond area.

Question and Answer: (Write your observations in your notebook)

• What happens as you spray more and more water onto the land?
• Why are the streams becoming wider and shallower?
• What happens when you use a fork to punch small indentations into the pasture? Simulate tracks left by cows and indicate what occurs.
• What happens if you cut the alfalfa (remove the clippings covering the field)?

Modifications: you can modify in one or more of the following ways:

• Plant the rows of corn and potatoes in different directions.
• Change the location of the alfalfa and corn crops.
• Add materials to the soil that will reduce runoff.
• Place a narrow strip of carpet in the stream bed (placing carpet will simulate planting grass in the stream bed).

Conclusion:

• What could be done to help solve the erosion problems? List at least five different things that could be done to prevent soil erosion and to improve the quality of the soil.

Wrap-Up:

• Review all materials, discuss lab demos and hands on activities and incorporate all avenues that have been covered in section 1 with section 2.

Assessment

Teacher will perform several assessment activities:

• Review vocabulary words that were handed out to students prior to the beginning of unit.
• Take up and grade by acknowledgement of objectives all experimental questions and any scientific method implementation.
• Grade students by their active participation in round table discussion when applied.
• Grade project “Bulldog Farm” on each station’s originality and thinking processes.
• Information-based evaluation in the form of a unit test.
• Information-based evaluation in the form of a vocabulary test. I usually assess vocabulary words by using a simple matching quiz. Use the words given in the vocabulary sheet for section 2 and provide definitions in a matching format. Play the game of “Bluff”.

Supplemental information

Lab activities and hands on demos were performed with incorporating materials received from the North Carolina Soil and Water Conservation Department (check with your local office serving your county).

Resources for pertinent information regarding concepts presented were gathered from environmental education booklets and forestry services.

Critical vocabulary

• soil erosion
• sedimentation
• deforestation
• glacial erosion
• coastal erosion
• water erosion
• silt
• fencing
• pile rocks
• contour farming technique
• conservation tillage
• precipitation