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Earthworms and plant growthFeatured science projectScience project video

Abstract

This experiment was conducted to determine how the presence of earthworms in soil can affect plant growth. The experiment was done by comparing the germination and growth of tomato, green beans and radish plants in soil samples that contiained earthworms, with those that did not contain any earthworms.

Hypothesis

The presence of earthworms in soil will help plants grow faster.

Scientific Terms

Soil aeration, soil erosion, casting

Background

Earthworms and plant growth

The earthworm is a type segmented worm that lives in soil. They burrow holes in the ground and create networks of tunnels as they move inside the soil, and this helps aerate the soil. The size of the burrows depends on the diameter of the earthworm and this can range from 1mm to 10mm. These networks of tunnels by the earthworms help the soil to absorb more water during rainfall and thiss reduces the erosion caused by surface runoff.

Earthworms feed on soil and decaying organic matter in the ground. A single acre of land may have as many as 1 million earthworms and each worm can digest the equivalent of their bodyweight of soil and organic matter everyday. This helps to increase the turnover of decaying organic matter in the ground which the plants can absorb and reuse.

The organic matter and soil that is digested by the earthworms are returned to the soil as castings. Casting are very rich in nutrients and beneficial to plant growth. They consist of organic and inorganic materials that are broken down by the bacteria and enzymes found in the digestive tracts of earthworms. Earthworms also help by feeding on the organic material on the top layer of the soil and later redepositing the castings deeper into the soil, in closer proximity to  the roots of plants.
 

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Complexity level:
6
Project cost ($):
20
Time required:
1 day to prepare, 8 days for observation
Material availability:
Look for earthworms in your garden. The seeds may be obtained from a nursery.
Safety concerns:

None