Answer to Question #104044 in Geography for Sarada prasan Mandal

Question

Describe the various ways to find out the exact percentage of sand, silt and clay particles in soil.

Answer 1

For instance, you can take a piece of soil and perform the following steps:

1. Remove all rocks, grass, bugs and other non-soil pieces from your portion. Try to make it more or less homogeneous.
2. Pulverize it.
3. Fill one-fourth of a cylindrical jar with your soil.
4. Add water until the jar is three-fourths full.
5. Add a teaspoon of non-foaming detergent.
6. Close the jar hermetically and shake it for 15 minutes.
7. Put it on a horizontal non-shaking surface and after 1 minute carefully mark the level of sand layers. Don't touch the jar anymore.
8. In 2 hours, accurately and carefully mark the level of silt.
9. Leave the jar in a dark place and try not to touch it 1 to 3 days until the water clears.
10. As the water clears, mark the level of clay.

Now you have all necessary information to find the percentage of sand, silt and clay particles in soil: just measure the thickness of each layer and divide it by the total thickness (or the sum of the previously measured particles). Multiply by 100%:

$$\omega[\text{particle}]=\frac{\text{thickness of particle}}{\text{total thickness}}.$$

Or you can use a centrifuge to determine the percentage even more accurately.