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Earthworms: Nature's Tiller?

Time Required Long (2-4 weeks)
Material Availability Readily available
Cost Low ($20 - $50)


Everybody knows that worms are good for the soil, but not everybody knows why. Here's an idea for measuring how efficiently earthworms turn over organic surface material into the soil.


The objective of this project is to determine the effect of earthworm density (number of worms per unit volume of soil) on decomposition or reduction of surface residues.


Matt Mulanax

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MLA Style

Science Buddies Staff. "Earthworms: Nature's Tiller?" Science Buddies. Science Buddies, 6 Oct. 2014. Web. 30 Oct. 2014 <http://www.sciencebuddies.org/science-fair-projects/project_ideas/Zoo_p049.shtml>

APA Style

Science Buddies Staff. (2014, October 6). Earthworms: Nature's Tiller?. Retrieved October 30, 2014 from http://www.sciencebuddies.org/science-fair-projects/project_ideas/Zoo_p049.shtml

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Last edit date: 2014-10-06


Earthworms act as natures plow by incorporating surface plant material into the soil. They play a major role in maintaining soil fertility by recycling nutrients from the surface residues and soil structure by providing glue that holds soil particles together. Does the number of worms in the soil affect how fast surface plant material will be incorporated into the soil?

Terms and Concepts

In order to conduct this experiment, you should have a solid understanding of earthworms, how they live, what they eat, and the ideal environment for worms.

You also should probably read about earthworms and composting as this will help you understand the process of digesting organic matter.


Following are some articles on earthworms:

Materials and Equipment

  • Ten inch diameter clay or plastic pots
  • Top soil (available from landscaping companies)
  • Earthworms or redworms, available from a local bait shop or from an online supplier such as Carolina Biological, which has earthworms (item #141630) and redworms (item #141650)
  • Grass clippings (available from municipal parks and recreation departments)
  • Metric ruler
  • Kitchen measuring cup

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Experimental Procedure

  • Eartworm treatments:
    • 0 worms per pot
    • 10 worms per pot
    • 20 worms per pot
    • 50 worms per pot
    • 100 worms per pot
  • Five pots per treatment
  • Place the same volume of soil in each pot (there should be 2 inches from the soil surface to the rim of the pot).
  • If the soil is dry (does not form a ball when squeezed in your hand) put tap water (one cup at a time) slowly over the potting soil surface until water drains from the pot. Allow the pot to drain for 2 hours before adding worms.
  • Place the required number of worms per pot and allow them to work down into the potting soil.
  • Place 2 cups of grass clippings uniformly over the surface of the potting soil in each pot
  • Each week measure the depth of the grass clippings in each pot and record your findings.

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There are many different types of worms. Does the type of earthworm used make a difference in the amount of material that is decomposed?

What are the ideal conditions for encouraging earthworms to eat? How does the amount of light, water, heat change the speed with which earthworms decompose organic matter?

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I did this project I Did This Project! Please log in and let us know how things went.

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Related Links

If you like this project, you might enjoy exploring these related careers:

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