Vegetable oil for water retention in soil
The materials required for this science fair project:
- 20 plastic cups
- 3 spray containers
- 1 bottle of corn oil
- 1 bottle of sunflower oil
- 1 bottle of canola oil
- 2000g dry soil
- 500ml tap water
- 1 digital weighing scale
- 1 pail
- 1 black marker pen
1. For this science fair project, the independent variable is the type of oil used – corn oil, sunflower oil, canola oil, or none at all. The dependent variable is the amount of water that evaporates from the soil. This is determined by using the digital weighing scale to measure the weight of the cup. The constants (control variables) are the size of the cup, the soil-to-water mix ratio, the room temperature and the amount of oil used.
2. The 20 cups are separated into 4 groups of five cups each. The groups are accordingly labeled corn oil, sunflower oil, canola oil and no oil.
3. 2000 grams of dry soil is mixed with 500ml of tap water in a pail. Using the digital weighing scale, 100grams of mixed soil is placed in each of the 20 cups.
4. Corn oil, sunflower oil and canola oil are poured into the spray containers. 5ml of oil is sprayed onto the soil in the cups marked as corn oil, sunflower oil and canola oil, according to the labels on the cup.
5. The weight of the cups together with the soil is measured. The total weight for the 5 cups in each group is then divided by 5 to obtain the average weight and it is recorded in the table given below.
6. The 20 cups are kept in a place where the temperature and humidity are constant. The moisture from the cups is allowed to evaporate. Everyday, for the next 5 days, the weight of the 20 cups is measured. The total weight for each group is divided by 5 and the average weight is recorded in the table given below (rounded to the nearest gram).
Basic safety requirements