Soil Permeability Experiment
Gail Bastarache


(The permeability tester)

Background:
Soil is a naturally occurring mixture of minerals, organic matter, water, and air which has definite structure and composition and forms on the surface of the land.
Permeability is the quality of soil that allows air or water to move through it.
Percolation is the downward movement of water in soil.

This activity would follow an orientation to soil profiles and soil types. Students should have a knowledge base about soil characteristics as a result of previous  inquiry activities.  Students should be able to recognize three common types of  topsoil and be knowledgeable about how soil is formed and  that organic and inorganic properties are contained in soils.
 

Grade Level
This activity is designed to teach students about the capacity of soil to retain water, and it was designed for nine to twelve year olds. Adjustments and extensions, as well as higher vocabulary, may be used for older students. For younger students phrases such as “holding in” and “letting go” may be used when discussing the capacity of the soil to hold water.
 

Connection to NCSCS:

Grade 3
Competency Goal 2: The learner will build an understanding of soil concepts
2.01 Differentiate the properties of soil such as color, texture, and capacity to retain water

Grade 6
Competency Goal 1 The learner will build an understanding of the lithosphere.
1.01 Analyze soil properties that can be observed and measured to predict soil quality:  horizon profile, infiltration, soil temperature, structure, consistency, texture
            particle size, soil pH, fertility, and soil moisture

Four Strands Involvement:
     Nature of Science: In this lesson, students will work together to conduct an
 experiment, collect data, and analyze results-endeavors that are well known to all
             investigators as they work to answer questions about the world around them.

     Science as Inquiry: During the hands-on activity, students will make observations,
             measure, experiment, make inferences, identify and attempt to control variables,
             collect, compare, and display data, and draw conclusions bases on their data.

      Science and Technology: The data collected may be displayed as a computer graphed
              printout. A data base could also be assembled using collected data.
      Personal and Social Perspectives- Students become aware of the concept of soil
       permeability, and the implications that it has for the provision of food sources for
       humans. Also, they will become aware of the importance of soil “percolation” for
       septic systems as part of public health awareness.

Process Skills:
Observing: Students will observe the characteristics of their soil sample before and after water has “perked” through it. They will observe and record specific time intervals as the water flows into the soil.

Communication: Students will work in groups of four and communicate with one another to collect data as they conduct the activity. They will then communicate with the whole group to compare data from three or more different soil samples.

Predicting: Students will use their observations to predict what effect compaction or changing other variables will affect their collected data.

Comparing: Students will compare and contrast the characteristics of their soil samples.

Experimenting: Students will conduct test to determine the level of permeability of their soil samples.

Recording data; Students will gather and share their information obtained through observation and experimentation.

Materials:
Samples of at least three varieties of soils: sandy soil, dark loam rich with humus (organic particles), and clay soil. Potting soil is made of mostly peat with added fertilizer. This could also be used for variety. Some groups will have the same soil type. This will be good to compare data and discussing controlling variables.

The easiest way to collect the soils is to distribute small zip lock bags to the students in the fall before the ground is frozen or wet, and ask them to bring in a soil sample from home. Once you begin the soil unit, the students can study the materials in their soil, classify it, and then use large buckets with specific labels for the student to pour their soil sample in. For example, all the clay soil would go in one bucket, sandy in another, etc.
When you are ready to do this activity you could distribute the different buckets to groups of four, and let each group gather their soil to measure from the bucket.

A clean, two liter bottle will be needed for each group. The bottle top should be discarded, and the bottle should be cut in two, about 15 cm. from the bottom of the bottle.
A small flexible screen measuring 10cm by 10cm should be given out with each bottle along with a rubber band. The students will use the screen as a filter which will fit over the mouth of the bottle. The rubber band will be wrapped around the screen at the base of the mouth of the bottle to tightly secure it. Some students may need help in making sure that this is securely wrapped.
Water should be made available as well as a measuring container that will measure up to 500 milliliters.

Newspapers can be used to protect the desks, or if lab trays are available, these should be used to collect any spilled soil or water. Have paper towels and a sponge handy for clean-up if an accident occurs.

Clean paper or science journal for recording data, pencil

Optional: A data sheet with the required questions and a place for identifying characteristic of each soil and any observations of unusual characteristics of the soil.
 

Activity Description
 

Engagement:
Tell the students that you are interested in doing some serious gardening, so you are thinking of purchasing some property. Before you purchase the property, you want to identify the kind of soil on the property and see how it “holds water”. You have gone and collected soil samples from three areas that are for sale. You ask the students if they can identify the soil and help you conduct a test to see which soil will be best for holding water for a garden.
 
Exploration:
Give each group of 4 students the materials that they will need to conduct the experiment.
Distribute containers of soil for the students. Give them measuring equipment to measure 500 ml of soil and pour it into the “funnel” part of their bottle.

Allow them to measure 500 ml of water which they will pour into the soil. They will fit the funnel shape into the bottom of the bottle, where the water will “perk” and be collected.

Before they begin the experiment, allow them to brainstorm some rules to control variables. Will they pack the soil?  What technique will be used to pour the water? Is there a timer for each group? Do they have any other variables that they want to control?

What data will they want to collect? Time if takes from first poured water until soil “lets it go”. Time from beginning of pouring time until soil no longer “lets go” of anymore water. Amount of water that “perks through”-what is its fractional ratio to the original
500 ml of water?

Allow all students time to conduct the experiment and collect the data.
 
 
 
 
 

Explanation:
Construct a data table on the board to collect information from each group about their soil type after each group has finished. Include in this chart each group (by number), name of soil type that they used, time (in minutes for soil to first let go), time for soil to completely finish letting go, and amount of water collected (fractional part, related to the whole 500ml of water). Allow the students to study the chart a few minutes and make some inferences about which soil is best for gardening.

For students who have the same soil type, allow them to compare and contrast their responses. If there is an obvious difference in their data, let them make inferences about what might have made the difference.

What does a fast “perk time” tell us about the soil?

What does a slow “perk time” tell us about the soil?

Which soil kept the most water?

Which soil let go of the most water?

Where do they see evidence of  soils absorbing soil quickly or slowly in real life? (sand, a muddy clay-packed road with puddles)

Which soil would be best for growing crops based on how much water it keeps? Why?

Are their any crops which would need soil which holds a lot of water? (rice) Where do they grow?
 

Expansion


Have the students to design a graph and display some of the data that they have obtained.

Have the students actually use pots and plant seeds in the different soils and make observations and comparisons of the roots as well as the plants themselves after the seeds germinate and the plants begin to grow.

Discuss with them the use of septic tanks in rural areas and why soil is tested for permeability before a tank is placed in the ground.

Research wetlands and find benefits of this super saturated soil to its environment.
 

Assessment:
Formative assessment would be ongoing as the instructor observes the students as they  conduct the experiment and record data. Also, after the data is collected for all to see, the students’ reflections and observations would be very indicative if they understand the concept of permeability.

Summative: As each student to write a paragraph explaining what they have observed and learned through today’s activity. Ask them to describe the soil they would choose if they were planting a garden and why they would choose that soil.

Higher Level: Have students use the information that they have collected to make a soil data base with different types of information about soils contained within it.
 
 

Integration:

Language Arts: Students write an essay about soil and why it is important to human existence.

Art: Students design a tee shirt emphasizing soil conservation
Students could research which minerals make up “clay”, and practice some clay sculpting.

Social Studies: Students could research historical issues involving soil such as “The Dust Bowl”

Students could research the soil crisis created in the rain forest as a result of “slash and burning” of rain forest areas.
 



 

Worksheet
 

Soil Permeability Data Sheet
Amount of Soil: 500 milliliters
Amount of  Water: 500 milliliters
 
Group Number    Soil Type Min. for first drip   Min. for final drip  Amount Recovered
 1
 2
 3
 4
 5
 6
 7
 8
 
 
 
 

Special Observations:
 

 
 

Which soil would be best for a vegetable garden?
Why?
 

Which soil would be best for a cacti garden?
Why?

 
Which soil would be best for growing rice?    Why?
 
 
 
 
 
 
 
 
 
 
 
 

Would your soil be suitable for growing rice? Why or why not?