Soil types and water retention
The materials required for this science project experiment:
- 3 plastic pots
- 3 plastic containers
- 3 sheets of fine wire mesh, slightly larger than the size of the cover of the plastic container
- 600 ml of water
- 1 sack of sand
- 1 sack of clay
- 1 sack of silt soil
- 1 weighing machine
- 1 measurement cylinder
- 1 marker pen
1. For this science fair project, the independent variable is the type of soil used. The dependent variable is the amount of water retained in the soil. This is determined by measuring the water drained using the measuring cylinder and also checking the weight of the pot. The constants (control variables) are the amount of water used, the amount of soil used and the time taken for the water to drain from the soil.
2. The 3 pots are labeled A, B and C. The sand is placed inside pot A up to 20mm from the top. Similarly the clay soil and silt soil are placed in pots B and C up to 20mm from the top of the pot.
3. The pots A, B and C are put outside in the hot sun to dry and for the soil to settle down in the pots for 2 days. After the second day, the weight of the pots is measured and recorded in the table below.
4. The pots A, B and C are placed on the wire mesh and plastic collection container as shown in figure 1. Using the measuring cylinder, 200ml of water is poured into each of the pots and they are allowed to drain for 4 hours.
5. After 4 hours, the amount of water in the collection containers is noted using the measuring cylinder and the weight of pots A, B and C are checked and recorded in the table.
Basic safety requirements.