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Science Projects on OER Decomposition

Open Education Resources, or OER, is an online resource that consists of free teaching and learning materials for educators and students. The resources on the OER website define decomposition as the process of natural breakdown of dead plants and animals by bacteria and fungi. The decomposed plants and animals mix into the soil and form nutrients that promote the growth of new life. Decomposition, therefore, is an important step in the cycle of life on earth. The OER decomposition section describes several experiments to help students explore this concept.

Speed of Decomposition
- Students can conduct a simple experiment to study the different factors that promote decomposition of plants in nature. They can place a pre-weighed amount of soil and carrots in a plastic bag that can be sealed and check their weight everyday over a period of few weeks. They will notice that the carrots weigh less as each day passes. The rate of decomposition can be slowed down by placing the bag in the refrigerator. The low temperature in the refrigerator prevents the growth of bacteria that cause decomposition. Adding water to the carrot bag at room temperature, on the other hand, promotes increased growth of bacteria, and speeds up decomposition and occurrence of foul smell.
Decomposition of Grass
- You may create one cubic meter pile of grass, and record its internal temperature, appearance, volume and smell on the first day. You should have the students observe the grass pile each day over the next several days to note the changes as the grass decomposes. You may also bury a similar pile of grass under soil and notice that this pile will decompose faster than the open pile. This is because the bacteria in the soil increase the rate of decomposition.
Decomposition in Freshwater
- Students may understand the process of decomposition in freshwater by sticking a pack of soaked autumn leaves to a bar or rod and placing it in a freshwater stream during a field trip. The leaves should be left in water for two weeks. When the leaves are taken out of water, there is a significant change in their shape and weight, thereby demonstrating decomposition in freshwater.
Environment and Decomposition
- Take 12 glass beakers or jars and add equal amounts of soil and fruit or vegetable scrapings to them. Label each jar as: 1. Dry, warm, sunny; 2. Moist, warm, sunny; 3. Wet, warm, sunny; 4. Dry, warm, shady; 5. Moist, warm, shady; 6. Wet, warm, shady; 7. Dry, cool, sunny; 8. Moist, cool, sunny; 9. Wet, cool, sunny; 10. Dry, cool, shady; 11. Moist, cool, shady; 12. Wet, cool, shady. Place them according to their labels in different areas of your lab or classroom. Observe the jars over a period of two weeks and discuss how moisture, temperature and light affect the rate of decomposition.

Nature