Decomposition Tea

In the video for Session 8 (Material Cycles in Ecosystems), the focus was on how the chemical elements required by living things are cycled between the living and nonliving environments. The action of decomposers is important in this process. Bacteria and fungi use the bodies of dead things for food, and in doing so, break down and release the chemical elements within. These become a store of nutrients for new generations of living things.

Just how important is the process of decomposition to new life? In “Decomposition Tea,” you’ll plant seeds and supply them with three different types of water: distilled water, fertilizer solution, and water taken from the aquatic habitat in your EcoColumn. We call this water “decomposition tea.”

Materials Needed

• Stocked EcoColumn after 4-5 weeks.
• Three Bottle Growing Systems planted with Fast Plant seeds in nutrient-free “soil”
• One Light House (instructions from Brassica & Butterfly system)
• One turkey baster
• Distilled water (no nutrients)
• Fertilizer solution (nutrient levels determined to promote optimum growth)
• Decomposition tea (nutrients supplied by decomposition)
• Decomposition Tea Data Sheet (PDF)

Note: You can use seeds of any type for this activity. We suggest Fast Plants because of their rapid life cycle and predictable growth habits under the controlled conditions in a Light House. “Decomposition Tea” is water extracted from the aquatic habitat of your EcoColumn after it has developed for several (approximately four to five) weeks.

Instructions

1. Build three Bottle Growing Systems. We used 740 ml water bottles as the smaller size works best for this activity.
2. To each funnel, add material that is free or low in nutrients to act as soil. We used rock wool, which we purchased from Carolina Biological Supply Company (1-800–334–5551) or www.carolinabiological.com. Vermiculite, perlite, or dried peat moss can also be used.
3. Moisten the planting material with water.
4. Plant an approximately equal number of seeds in each system (15 - 20). Try to distribute the seeds evenly within the system.
5. Prepare fertilizer solution. Follow instructions on the container to make it full strength.
6. Use a turkey baster to extract decomposition tea from the aquatic habitat of your EcoColumn. Replace the water you removed with untreated tap water.
7. Add distilled water, fertilizer solution, and decomposition tea to different Bottle Growing Systems and apply appropriate labels.
8. Place each system in a Light House so that the seeds sprout about 10 cm from the light. Adjust this distance to the top of the plants as they grow. Your study period begins at this point.
9. Using your Decomposition Tea Data Sheet, track plant growth in each system for two weeks (or longer).
10. Be sure to keep each system supplied with the appropriate type of water.

Activity Questions

Before the study period begins

1. What plant characteristics might be affected by supplying different levels of nutrients in the water?
2. What do you predict will happen to the plants grown in distilled water? Fertilizer solution? Decomposition tea?

After the study period ends

1. What occurred during the study period to the plants in distilled water? In fertilizer solution? In decomposition tea?
2. How do you account for any differences you observed?
3. How does decomposition tea become a source of plant nutrients?
4. How does this compare to what happens in nature?
5. In the video, the nitrogen cycle was described. How does nitrogen cycle in your EcoColumn?
6. Draw a diagram to show how nitrogen cycles in your EcoColumn.

SHARE YOUR RESULTS: Decomposition Tea

TRACK OUR PROGRESS: Decomposition Tea

prev: when it rains...

next: track our progress