When you think of a web, you probably don't think of earthworms, do you? What comes to mind? A spider web? The World Wide Web? How about a duck's webbed feet? Well, there's another kind of web you might not know about. It's the soil foodweb.

The soil foodweb is the set of organisms that work underground to help plants grow. There are billions of organisms that make up the soil foodweb. These include bacteria, fungi, protozoa, nematodes, arthropods and earthworms. Each type of organism plays an important role in keeping the soil healthy for all living things.

Let's take a look at why earthworms are so important to the Earth's soil.

Earthworms eat just about every other organism in the soil. They're miniature topsoil factories—all the soil you have ever seen has passed through the stomachs of lots of earthworms. When they eat, they leave behind "castings," which are high in organic matter and plant nutrients and are a valuable fertilizer.

Earthworms move through the soil creating tunnels—areas that can be filled by air and water. Fields that are "tilled" by earthworm tunneling can absorb water at a rate 4 to 10 times that of fields without worm tunnels. This reduces water runoff, restores groundwater, and helps store more water for dry spells.

This burrowing also helps nutrients enter the subsoil at a faster rate and opens up pathways for roots to grow into. During droughts the tunnels allow plant roots to penetrate deeper, to reach the water they need to thrive.

Earthworms help keep soil healthy by moving organic matter from the surface into the soil. Normally a tree leaf may take three to five years to decompose and be incorporated into the soil. In forests infested with night crawlers, this process can take as little as four weeks! By speeding up the breakdown of plant material, earthworms also speed up the rate at which nutrients are recycled back to the plants.

Earthworms and other soil organisms are a necessary part of the soil foodweb. Without them, all the organic matter would build up on the soil surface and never get down into the soil. To grow healthy, productive plants, you need healthy, productive soil. Organisms in the soil provide the food for plants—how they need it and when they need it!

Fun facts about earthworms!

• An acre of land can contain more than a million earthworms!
• Earthworms are amazingly strong. They can easily shift stones 60 times their own weight!
• The largest earthworm ever was 22 feet long and was found in South Africa.
• Worms do not have eyes, but they can sense light. If they're in light too long they'll become paralyzed.
• Baby worms aren't born; they hatch from a cocoon no bigger than a grain of rice. Click here to see a video of a baby worm hatching! (You'll need QuickTime to play the video. Click here to download a free version.)
• Worms are very helpful in composting piles. They help increase air and water in the soil and break down grass and leaves so microorganisms can work to make the soil healthy and rich in nutrients. Click here to learn more about composting.

Sources:

• Soil Foodweb Incorporated
• Agroforestry Net Inc.
• Urban Programs Resource Network
• Discovery Kids
  University of Nebraska-Lincoln
• University of Minnesota