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The Preferred Food Of Detritivores: A Composting Project

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Updated on Mar 18, 2010

Type
Life Science
Grade Level
Late Middle/High school
Difficulty of Project
Medium
Cost

Red wiggler worms are the lion’s share of the cost here. If you can find them locally, be prepared to spend about $22 for a lb, although you will likely not need that many. Many plant nurseries will sell them for about $10-$14 for approximately 300 worms- more than enough. The bonus about doing this project is that much of what you need in the project can be used to set up your own vermicomposting system at home afterwards, and all the other components are recyclable!

TOTAL: $10-$30
Safety Issues

Always wash hands after handling both worms and composted materials.

Material Availability

Outside of procuring the correct worms, all other materials are easily available.

Approximate Time Required to Complete the Project

While materials are easily available and the project may ignite a lifelong interest in ecology, it does take some time- you will get the best results if you give yourself not weeks but months- at least 2- to allow composting and the delicate underlying processes that bolster them to occur. It isn’t the most convenient of science fair projects in that respect, but considering our impact on the environment and our population growth, it may be the most important!

The project aims to discern whether or not composting worms reproduce and thrive better with a specific food source.

To quantify the effect of specific food sources on red worm (Eisenia foetida) livelihood.

  • Red Wriggler worms(Eisenia foetida)
  • 6 Empty 2-liter bottles
  • Scissors and/or razor blade
  • Sharp needles
  • Packaging tape
  • Screen or netting or cheesecloth
  • Rubber band
  • Three different types of ‘food waste’- remains from your household meals.

Most materials can be found around the house or at the grocery store, with the exception of the worms. If they aren’t available at either a pet/aquarium store or your local plant nursery, they can be purchased online at the link listed in the bibliography.

Landfills are becoming…well, full. We generate more trash and waste than ever before in our species’ history, and disposal of it might be our greatest environmental concern, all taken in balance. Composting is an effective way to return our wastes to the earth in a way that makes the materials available to be re-absorbed by natural and geo-chemical cycles.

Vermicomposting- composting with worms- is a fast and efficient way to do this. However, as a discipline, it is still relatively young, and the more informatiom that can be found on how to effectively compost with worms, the better.

A diagram of how to construct a composting column can be found here:

Research Questions
  • What is vermicomposting?
  • What is the life cycle of Eisenia foetida?
  • What is the difference between aerobic and anaerobic respiration?
  • What is decomposition?
  • What is a detritivore?
  • How can an effective composting unit be designed?
  • Describe the internal anatomy of an earthworm.
Terms, Concepts and Questions to Start Background Research

Detritivore, compost, humus, landfill, red wiggler, cocoon, decay, life cycle, nutrient recycling.

Preparation:
  1. To assemble a composting column, take 2 plastic 2-liter bottles. With the first bottle, cut around the circumference of the top of the bottle, near the top, just as the top is no longer tapering off. Cut near the bottom. You should have three pieces.
  2. Discard the very bottom. Save the top- it will serve as your lid.
  3. With the second bottle, cut around the circumference directly in the middle. Attach the top part of this bottle upside down to the middle section of the first bottle, so that the nozzle is pointing downwards. Seal with packaging tape.
  4. Cover the bottom nozzle with screen and secure it using a rubber band. This will serve as the ‘drain’ for your composting column.
  5. Insert the whole apparatus you have constructed into the bottom half of the second bottle, so that your composting column has something to drain into. Secure the lid on top, and voila- you are ready to begin composting!
  6. Repeat steps 1-5, so that you can have three different columns to conduct your experiment.

NOTE: Great diagrams and instructions for building columns can be found at the link listed in the bibliography.

Experimental Procedure:
  1. Place shredded newspaper or napkins in the bottom of each column to make sure the worms don’t fall into the bottom nozzle and so that they have some bedding to begin their lives in.
  2. Count out the same number of worms into each column, of approximately the same size. No less than 10, no more than 50.
  3. Choose three food substances that you will test. Keep it easy- use food substances that you often have extra of at meal times- rice, or lettuce or fruit should do nicely.
  4. Place approximately the same amount of food in each column to start with. Make sue the worms don’t run out of food!
  5. Place all three columns in a dark place. Check in on your worms weekly- add more food if it seems they are running out. If the bottom of the column is filling up with liquid, remove the bottom container and pour the liquid in the top.
  6. After at least one month, or up to four, pull out your columns. Sift through the humus and count how many worms now live in the column. Bedetailed- some of the new worms might be quite small!
  7. Record your data in a table, and make a great science fair board to present your findings!

You should take show all the data you took during the experiment in a table form. You should also include a graph of worm populations- a bar graph should do nicely. Any other statistical analysis- percent change, X-squared or t-tests (high school only)- can be added as well, if you know how to do them.

While no diagrams are required, it is always a good idea to photo document the process so you have great visuals for your science fair board!

Worms- and great information about worms- can be found here:

The very best directions for constructing a composting column out of 2-liter bottles can be found here: http://teams.lacoe.edu/DOCUMENTATION/classrooms/gary/plants/activities/articles/composting.html

Web based activities on worms:

Shumit DasGupta has worked for OSHA, UMBS, and Pfizer as a contract researcher, is a ten year veteran in science education, and has taught students in the International Baccalaureate program in both Chicago and San Francisco. Four of his students have made it to states, and one to nationals- the year it was held in Hawaii- and he was sad he couldn't chaperon. He also loves snorkeling.

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