Nitrate leaching by organic and inorganic fertilizers
The materials required for this science fair project:
- 4 pots
- 4 pot trays
- Soil (enough to fill 4 pots)
- Carpet grass (enough for 4 pots)
- 1 packet of cow manure
- 1 packet of compost
- 1 bottle of liquid inorganic fertilizer
- 1 pack of granule inorganic fertilizer
- Tap water
- 1 nitrate test kit
1. For this science fair project, the independent variable is the type of fertilizer used - cow manure, compost, liquid inorganic fertilizer and granule inorganic fertilizer. The dependent variable is the concentration of nitrate in the runoff water. This is determined by testing the water using the nitrate test kit. The constants (control variables) are the size of the pot, the amount of soil and the amount of water used for watering.
2. Label each of the 4 pots as cow manure, compost, liquid and granule. Prepare the soil for the 4 pots, as follows:
a. Cow manure – fill the pot with a mixture of cow manure and soil.
b. Compost – fill the pot is fill with a mixture of compost and soil.
c. Liquid – fill the pot with soil and pour liquid fertilizer over the soil.
d. Granule – fill the pot with a mixture of granule inorganic fertilizer and soil.
3. Plant carpet grass over the topsoil in each pot and place a pot tray under each pot. For the next 3 days, water the grass. Using the nitrate test kit, test the nitrate content in the excess runoff water in each tray. Record the results in a table, as shown below.