Grade Level: 5th - 10th; Type: Life Science
Student tests the effects of turning compost on decomposition time.
- Does turning compost speed the decomposition process?
- What organisms are active in compost?
- How do organisms break down solid waste?
- How does aeration speed the decomposition of waste?
Composting is an important technique used to break down solid organic waste and make it useful for growing plants. The process helps keep food, yard, and paper waste out of landfills and makes nutrient-rich organic fertilizer. Worms are often used in composting. The activity of the worms is thought to aerate the compost and make it decompose more quickly. In this experiment, a student will test the benefits of turning compost to aerate it. The student will set up two compost piles with soil and yard waste and place sheets of newspaper in each pile. Over a period of two to three months, the student will turn one pile with a shovel and leave the other pile undisturbed. The amount of decomposition will be determined based on the appearance of the newspaper in each pile.
- Shovel or metal rake
- Wire mesh to make round containers or large round containers (such as garbage cans) found at hardware or home supply stores
- Set up compost piles. While the piles may be left on the ground and out of containers, it is more precise and reliable to put compost in containers. Both containers should be the same size and made out of the same material. Use of bin, garbage can, or similar container is acceptable. If these are not available, the student may form wire mesh into a cylinder and secure it with wire.
- Inside the bin, layer topsoil with grass clippings and leaves. Add five sheets of newspaper into each bin. Take pictures of the newspaper before adding it. Take pictures while you set-up the bins as well. Top the newspaper with more soil, grass clippings, and leaves. Wet the bins with about 2 gallons of water each.
- Leave both bins for two-three months. One bin should not be disturbed (control). The other bin should be turned every two weeks. To turn the compost, gently lift the compost on the outside of the bin and turn toward the center of the pile. Take pictures of the bins every two weeks before turning.
- At the end of the two or three months, carefully remove the top compost to unearth the newspapers. Be sure to extract every piece of newspaper and put them together. Take pictures of the newspaper and estimate the percentage of the paper left after composting in each bin. Create a bar graph to compare the percent decomposition (100% - percent left after decomposition) in the two bins.
Terms/Concepts: Composting; Vermicomposting; Decomposition; Nutrient cycling
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