EXPERIMENT IDEAS

(Lauren Teller, FRC)

Grade/Course Suitability: Sci20S (Ecology)

Objective: The purpose of this experiment is to determine if cattail mulch can be used as a natural fertilizer for the growth of radishes.

Materials:

Suggested Procedure:

Preparation and planting of radish seeds:

1. Cut cattails above water level, cattails preferably in fall when nutrient levels are highest. Separate the flower head from the stalk. Cut stalk into small pieces and then, using a food processor, chop until fine.
2. Measure 115.00 g of potting soil for each of 24 containers.
3. The first six containers will be the control plants, with only soil. Label as Control A - F.
4. Cattail Mulch: Add 3.00 g of mulch to each of six new containers. Stir to combine, and label.
5. Repeat step five twice, with one set containing 4.50 g of mulch and another set with 6.00 g.
6. Evenly space five radish seeds in the center of each container. Top with 5.00 g of soil and give each 30 mL of water.
7. Place in the plant chamber set to 24oC, 60% humidity, and 16 hours of daylight. Check on the radishes every day, and water as needed.
8. When the plants are unattended for more than one day, surround them with a clear plastic bag and use supports to distance the bag from the top of the plants. Ensure they are generously watered.

During and After Plant Growth:

1. Once radishes have sprouted (3-5 days), begin measuring the height of each sprout. Once most sprouts have exceeded two to three centimeters, thin all containers leaving the tallest and healthiest looking sprout in each one.
2. Continue monitoring growth by measuring the height of each sprout. Take observations, considering colour and condition of leaves and stems.
3. After 29 days of growth, remove from plant chamber. Carefully pull each radish and separate it and its roots from the soil. Save the soil in labeled containers for further testing.
4. To measure the mass of each radish, cut off its roots at the base and cut off the stem where green meets red. Brush off any excess soil. Place on the scale and record the mass. Repeat for each radish.
5. Follow the instructions in the soil testing kit to test the phosphorus and nitrogen levels.

Recommended Result Observation and Analysis:

1. Compare average plant height for each different group (control, 3.00 g, 4.50 g, 600 g mulch).
2. Compare average mass of radishes only for each different group (control, 3.00 g, 4.50 g, 600 g mulch).
3. Complete soil tests for nitrogen and phosphorous using the soil from individual samples.

Further Exploration/Project Extensions:

After completion of the experiment, it was noted that steps could be taken to improve the experiment in order to obtain more definitive results. For example:

• larger sample sizes were needed to provide more conclusive results.
• It was also found that cattail stalks and flower heads did not need to be separated, as they both impacted the growth of the radishes in a similar way.  (Although the procedure shown here did not include the flower heads in testing).
• A dry biomass measurement may offer more conclusive results.

This project also lends itself to many extensions, as few are listed below.

• In this study, the cattails were harvested, mulched, and mixed directly into the soil, not leaving enough time for the cattails to decompose and let their nutrients seep into the soil. Instead, cattail mulch could be composted until fully decomposed, and then mixed into the soil for testing.
• Another consideration is that this study only involved radishes, a type of plant that grows below the ground. An interesting experiment would be to test different types of crops to see how they are affected by cattails and compare the impact of above ground and below ground crops.

See the poster for more information: Click Here