Cochise College           Student Papers in Geology

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Roger Weller, geology instructor

by Sean Harvey
Physical Geology
Fall 2007



Many creatures help revitalize the earth, some through balancing the topsoil of our plant by enriching it with nutrients and air flow.  The mighty earthworm is our discussion point today.  The earthworm is efficient at creating and maintaining soil that, through growth of food products, can sustain the whole plant.  This industrious creature, by successfully accomplishing its day to day activities allows the circle of life to continue to flourish.

The earthworm family includes approximately 2,700 different species.  All 2,700 varieties offer the same benefits to our earth through maintaining and stabilizing our topsoil.  The most common earthworm found in North America is the Nightcrawler or Lumbricus Terristris.  This busy little earthworm helps the first and second layer of the topsoil.  The three most important items the earthworm does for our topsoil are:

·         The earthworm secretes nitrogen. 

·         While the earthworm is moving through the soil, it mixes the secretion with the A Horizon and B Horizon.  This compost, when completely mixed, creates a more balanced mineral composition.

·         Again, through the movement in the topsoil, the earthworm is aerating the soil, and as a byproduct, aerating the soil after a good solid rainstorm


Topsoil is essential to plant growth.  Making worms a key component for the creation of good topsoil. The Earthworm came to North America by European colonials in simple gardening plants.  This was one of the few introductions of a foreign species to have its advantages out weight its disadvantages.

The Earthworm utilizes its physical structure to help propagate the decomposition of debris. By having a slim-line body it can borrow itself deep into the earth, about 6 feet, and not burn much energy.  The worm when borrowing into the earth does not purposely make top soil rich in nitrogen, but it’s a bi-product of the worm decomposing matter.  When a worm ‘eats’ the soil in the earth is broken down into the nutrients it needs and secretes the minerals it does not need.  One of these minerals it secrets is nitrogen.  Nitrogen is very important to plants and other carbon based life forms.  This nitrogen is taken into the roots and the plants turn into lush green life.  Nitrogen from the plants can be then transformed into the nutrients the plant needs.  This plant now is rich in nitrogen and can be consumed by any herbivore or omnivorous creature that eats it. The worms also leave other trace minerals to help give the topsoil enriched minerals.

Worms travel deep into the earth and have been known to average about six feet into the soil.  This crosses the A horizon layer and B horizon layer found within the ground.  When the worm crosses the A horizon and B horizon the ground mixes its soil and mixes the minerals within the ground together within the two horizons.  This creates a more balanced composition within the ground and helps plants’ roots group deeper for the same nutrients.  This allows the plants roots to grow in a uniform fashion deep within the topsoil without little interference from the ground lacking sufficient minerals.  With the two inner mixing horizons the effective topsoil is deeper and allows for plants to become enriched with minerals wherever their roots may grow.

When an Earthworm borrows itself into the ground it leaves very small tunnels and allows oxygen to seep into the ground effectively loosening the soil.  Loose soil allows for plants to grow with great ease because it does not take as much effective energy to penetrate into the ground.  These tunnels also allow for more then just oxygen to penetrate into the ground.  When it rains the ground is very loose and can effectively hold more water within the ground creating a further moist environment for the worms as they enjoy and more importantly the plants have more water to tap into.


The worm does not purposely secrete, irrigate, and mix the horizons together for the creation of great topsoil, but it does this in the essence of Geology.  This shows all the pieces of the worm’s ecology working together but with an organized chaos of earth’s cycles and how its particular cycle of top soil is benefited from another cycle.  Just a few of the Earth’s cycles such as the water cycle, topsoil cycle, and earthworm life cycle shows how each of these are different but help each other in a global cycle of its massive perpetuation of the ‘Earth’ cycle.


In conclusion the Earthworm benefits the A horizon and B horizon greatly by creating a hearty topsoil made of a high Nitrogen concentrate which is great for Carbon based life.  The mixing of the two horizons makes thick topsoil and allows for greater root penetration into the ground for the key topsoil ingredients for plant growth. Lastly, the aerating the worms leave in the ground help the oxygen and water reach key parts of the soil to help growth.  These three key combinations the worms do in their interaction of the soil allow or great growth.  While they are not the purposeful effect the worms are trying to achieve, they also benefit from these benefits as well.  They benefit by the moist environment the aeration creates and when the plants grow, they die decompose and create even more food for the worms, creating even better soil for more plants to grow.  This shows two earth cycles working together forming a new unique cycle.



Facts about Earthworms




Work Cited

Interesting Facts about Earthworms. PilePro Compost Bins. Composting 201.


Worm Facts. Interesting things to know about worms.


Fun Earth Worm Facts.


Biology 203 Lab. Protostomes.


Common Earthworm.  National Geographic. Jason Edwards.