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Project Summary

Difficulty	5
Time required	Long (a couple of weeks)
Material Availability	Readily available
Cost	Low ($20 - $50)

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Objective

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.

Introduction

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, Concepts and Questions to Start Background Research

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.

Bibliography

Following are some articles on earthworms:
http://pubs.cas.psu.edu/freepubs/pdfs/UC182.pdf
http://www.oznet.ksu.edu/news/sty/2002/earthworms040302.htm
http://www.ext.colostate.edu/pubs/garden/07721.html

Materials and Equipment

• Ten inch diameter clay or plastic pots
• Top soil (available from landscaping companies)
• Earthworms (night crawlers available from bait shops)
• Grass clippings (available from municipal parks and recreation departments)
• Metric ruler
• Kitchen measuring cup

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.

Variations

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?

• For more science project ideas in this area of science, see Zoology Project Ideas.

Credits

Matt Mulanax

Last edit date: 2005-08-31 14:57:31

Career Focus

If you like this project, you might want to think about career opportunities in Zoology.

Ever wondered what wild animals do all day, where a certain species lives, or how to make sure a species doesn't go extinct? Zoologists and wildlife biologists tackle all these questions. They study the behaviors and habitats of wild animals, while also working to maintain healthy populations, both in the wild and in captivity. Learn more about this career: Zoologist and Wildlife Biologist.