Compost in a Bottle

This experiment creates a mini compost system inside a plastic bottle. By layering soil and organic waste, students can observe how microorganisms break down materials over time, producing nutrient-rich compost that can later be used to grow plants.

1. Remove the label from a clear 2-liter soda bottle so the contents can be observed.
2. With adult supervision, cut the top off the bottle.
3. Place about 1 inch of soil at the bottom of the bottle.
4. Add about 1 inch of compostable organic material (leaves, grass, food scraps, etc.).
5. Continue layering soil and organic material until the bottle is nearly full.
6. Place the bottle in a sunny spot where it won’t be disturbed.
7. Observe changes over several weeks, recording decomposition progress and temperature if desired.
8. Once the materials are fully composted, use the nutrient-rich soil to plant seeds or seedlings.

Compost in a Bottle: A Science Project - Read and Learn with Ms. Pia:

Creativity TV: Composting with a 2 Liter Bottle - Creative Discovery Museum:

📄 Make Compost In A Bottle Ecology Science Experiment - Science Fun for Everyone: https://www.sciencefun.org/kidszone/experiments/make-compost-in-a-bottle-ecology-science-experiment/

• Test different compostable materials to see which decompose fastest.
• Compare results using different bottle sizes or shapes.
• Add worms to see if decomposition speeds up.
• Place bottles in different environments (sun, shade, indoors) and track differences.

• Adult supervision required when cutting the plastic bottle.
• Wash hands after handling soil and organic waste.
• Do not use meat, dairy, or oily foods as they may produce unpleasant odors.
• Keep the compost bottle sealed or covered to avoid attracting pests.

• What role do microorganisms play in composting? (They break down organic material into simpler nutrients.)
• Which materials decomposed the fastest? Why might that be? (Soft fruit/vegetable scraps break down faster than tough leaves or stems.)
• How does the composting process benefit plants? (It recycles nutrients, enriching soil fertility and improving growth.)
• How is composting in a bottle similar to composting in nature? (Both rely on microorganisms, moisture, and temperature to recycle organic matter.)
• Why should meat and dairy not be added to compost? (They decompose slowly, can smell bad, and attract pests.)