Texture Test

Objective

In this activity, students determine the composition of a soil sample by performing a texture test. They will feel the texture of the soil when it is damp and use their data to classify the soil as sand, clay, or silt.

Making the connection:

Activity

Hypothesize

Is the soil at my field site mostly sand, silt, or clay?

Plan it!

  • If you haven't already done so, choose a field site and map it in your field journal.
  • Before going into the field, review the information about soil particles and texture on the Soil Properties Overview page.
  • If you are working with a group or as a class, be sure to spread out over the field site. Each student or group of students should set up a quadrant within which to work. If you are doing this activity along with the Soil Temperature, Compaction, and Percolation tests, you should do all four activities in the same quadrant.
    Doing all four activities within the same quadrant allows students to put the results of all the tests together to form a more complete picture of the soil. By spreading out over the study site, students create an opportunity to compare results from different areas within their field site, to note differences and similarities in the soil properties, and to get a more representative sample of the entire field site.
  • It is helpful for students to have some experience feeling pure examples of clay, sand, and silt. Contact your local Soil and Water Conservation District for information on how to get samples.

Do it!

  1. Take a handful of soil from your quadrant and spray it with water until it is damp, but not soaking wet.
  2. Rub the soil between your fingers and observe and feel its texture.
    • How does the soil feel? Is it sticky, slippery, or gritty?
    • Do the particles look and feel small, large, or somewhere in between?
    • Does the soil feel most like sand, silt, or clay?
  3. Use the Texture-by-Feel Analysis of Soil worksheet to figure out what type of soil you have.
  4. Return the soil to the ground when you have finished and use the wipes or damp paper towels to clean your hands.

Record it!

Remember, be sci-wise!

  • Don't let your soil sample get too wet or it will be difficult to make an accurate observation.
  • Be respectful of any creatures you find in the soil. Return them gently to the ground.
  • If students are working in groups, the same student or students should be the "feelers" for each trial. If several students feel the soil, each can discuss his or her observations of the texture.

Assessment and Reflections

  • What do your data tell you about the composition of your soil? Is the soil from your sample mostly sand, silt, or clay? How do you know?
    Students should be able to identify the predominant soil type in their sample (sand, silt, or clay) based on the way the soil feels. If the sample feels gritty and contains large visible particles, it is high in sand. If the sample feels smooth and slippery and not sticky between your fingers, it has a high percentage of silt. If the sample feels sticky and can be rolled into a worm shape without breaking apart, the sample has a high percentage of clay. A soil with a combination of all three particle types is called loam. Most samples will likely contain some percentage of all three soil types and therefore will be a loam.
  • Organic matter or humus is made up of decomposed plants and animals that enrich the soil with nutrients. There are many chemical tests that can help you identify the amount of humus in a soil sample, but looking at the soil color will give you a rough estimate. Generally, the darker black the soil, the more humus. Also look for twigs and leaves within the soil that have not finished decomposing.
  • Based on the data you collected, do you think your hypothesis was correct or incorrect? Why?
    Answers will vary.
  • How do your data compare with those of other students and from different areas of your field site? Results will vary according the overall composition of the soil at your field site.
    If some areas contain more clay than others, for example, students in that area would have very different results from students whose quadrant contains more sandy soil.
  • How do your data compare with those from the Mud Shake test? Did you expect the data to be the same or different? Why might they be the same? Different?
    Both tests show the composition of the soil, so the results from both tests should be the same. However, be prepared for significant variation between what the students felt and what the Mud Shake shows, particularly if the soil is a loam with a fairly even distribution of sand, silt, and clay.
  • How might the soil texture affect the types and numbers of creatures living in the soil? What data could you collect to help answer this question?
    Soil that is primarily composed of sand, silt or clay can make a poor home for organisms. Loam, a mixture of the different soil particles, is more conducive to underground life because sand helps open up the soil, silt holds the moisture, and clay releases minerals.
  • Looking at the bigger picture, how might the data you collected here help you answer your research question?
    Answers will vary depending on the research question, but students should begin to connect the data they collected here with data from other activities to help them answer the research question.
  • Fill in this section of the Soil Properties Overview worksheet .

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