Soil sedimentation test.

Soil sedimentation test.

ZIMSEC O Level Combined Science Notes: Experiment comparing the particle size of soils


Materials: samples of sandy, loamy and clay soils, 3 measuring cylinders/tall transparent containers, water


  1. Place sample of each soil sample into a tall container to about a quarter of its height
  2. Add water to until the containers are about 3/4 full
  3. Stir the mixture to mix it well
  4. Repeat this with other soil samples and containers
  5. Leave the containers to settle
  6. Observe the containers after a day
  7. Compare the sedimentation of clay, sandy soils


  • When the containers are left to settle the heavier large particles settle at the bottom
  • Different layers of sediment are seen with the less heavier particles forming a layer on top
  • The heavier particles sink to the bottom with the heaviest particles sinking first
  • Clay particles take longer to settle
  • Humus forms the top most layer
  • Clay has very few larger particles and so the sand and gravel form a very small layer
  • The and particle layer is also small in clay
  • Sand has much more large particles and the sandy particle layer is bigger than the clay layer which is very small
  • Loamy soils have medium sized layers of the sand and clay particle layers


  • Different soils contain different particle sized particles and some organic matter
  • The size of layers are different in different types of soil
  • Sand soil containers larger particles than clay soils

To access more topics go to the Combined Science Notes page.