Identifying types of soil samples

Key question: what are the different types of soil?      

What you need

• Three soil samples: A, B and C
  Water    Stirring rod
• Transparent beaker and a large bottle or a measuring cylinder

Measuring instrument for example a ruler or a tape measure

What to do

1. In groups, half fill the measuring cylinder with soil sample A and using a tape
   measure or a ruler, measure the level of soil in the measuring cylinder. Record the measurement as total soil.
2. Add water until the measuring cylinder containing soil is two-thirds full. Notice
   the air bubbles coming out of the soil.
   What does this tell you?
3. Cover the opening of the measuring cylinder using your palm or a lid. Shake it vigorously for about two minutes until all the particles are separated by the water. Place the measuring cylinder down and allow the soil to settle.
4. After 1 minute, measure the amountof soil in the bottom of the measuring Cylinder.
5. Record this measurement and label it as the “sand fraction.”Allow the sample to settle for 30 to 40minutes, then measure again and record the level.
6. The second layer indicates the silt fraction of the soil.
7. Determine the amount of clay in the soil by subtracting the combined sand and silt measurements from the total soil measurement.
8. Convert the measurements into percentages and repeat the procedure(1-5) above for soil samples B and C.
9. Record the percentage of each fraction of the soil samples in a suitable table. As you wait for soil samples to settle,
10. use the remaining portion of the soil samples  to  carry  out  the  following procedure:
    1. i) examine soil samples A, B and C and

    note the colour of each sample,

    ii) obtain a small portion of each soil sample, wet it with a small amount of water, and  rub the wet sample between your thumb and your first finger. How does each sample feel? From the observations above and with guidance from figure 1.1, i) name the type of soil from which soil

    samples A, B, and C were obtained?

    Give a reason for your answer in each case,

    ii) Identify the areas in your community where each type of soil named above

    is likely to be found. Write a  report of your findings and present it to the rest of the class.

    Suggested responses

    Observations

    1. Loam soil. This is a mixture of sand (about
       40%), clay (15%), and organic matter (1-
       4%). It is dark and has a stable crumb
    2. Sandy soil. It is light and has a gritty feel
       when wet.
    3. Clay soil, it is heavy and has fine particles
       with a sticky fee! when wet.
    4. ii) Loam soils are usually found almost everywhere especially in gardens, near compost pits and dumping areas.
    • Clay soil is found  in swamps and
      anthills.
    • Sandy soil is found on lake shores and

    hilly areas

    State the Observations