The mighty worm

Look out the window. See a patch of earth? How many worms do you think live there? Every acre is home to as many as 1 million worms. This means that for every square foot (12 inches by 12 inches), there could be 23 earthworms.

Fossil evidence shows that wormlike creatures have been around for more than half a billion years. They existed in the time of dinosaurs and even survived the mass extinction 65 million years ago - the one that finished off the dinosaurs. Earthworms typically live anywhere that's not extremely hot or extremely cold.

Glaciers are extremely cold. They also act like giant bulldozers, scraping off the top layer of soil. So by the end of the last Ice Age in North America (about 10,000 years ago), earthworms in what is now Canada and the US had been wiped out. Most of the earthworms found today in North America are immigrants. They came here in potted plants and ship ballasts from Europe. We're glad worms have found good homes here, for the most part.

As settlers moved West, worms moved with them. Worm eggs were carried on the soles of dirty shoes and in horses' hooves. They hitched rides on wagon wheels and, again, in pots. The worms arrived in California with the Forty- Niners during the Gold Rush. In all, it took only 200 years for earthworms to make their homes all across America.

Earthworms eat their way through soil. They ingest bacteria and small particles and enrich the earth with their waste products, called castings. The burrowing action also allows more water and air to enter the soil, making it richer. This deceptively simple creature is largely responsible for all the rich soil on Earth. Its journey across America has created some of the richest farmland in the world.

Nineteenth-century British scientist Charles Darwin, who wrote "The Origin of Species" about evolution in 1859, studied worms. He wrote a whole book about worms called "The Formation of Vegetable Mould Through the Action of Worms, With Observations on Their Habitats" in 1881. ("Vegetable mould" is what soil used to be called.)

Darwin called worms "ploughs of the earth" because of their ability to eat soil and eject it as castings. He believed that worm castings and the movement of worms were wholly responsible for the top layer of rich soil. Darwin claimed that worms were one of the most important creatures in the ecosystem. He also noted the amazing ability of worms to bury things in the soil - from coins to Roman ruins. Archaeologists should be very grateful for worms!

The worms in your garden are probably nightcrawlers. They pull organic material - leaves, remains of plants and animals - into their burrows. The best time to look for worms is at night. Worms are sensitive to light and dig away from it.

Red wigglers are another common worm, though probably not in your yard. They do not make burrows. They feed on the surface of the soil, eating organic material that has started to decompose. Red wigglers are popular with farmers and gardeners. Their diet also makes them perfect for composting kitchen scraps into rich soil. They are commonly used in worm composters. (These are special boxes with trays and lids where worms digest household scraps - except for meat and dairy waste.)

Red wigglers eat half their body weight in food every day. Matt Abbruscato, owner of Foothill Worm Farm in Pleasanton, Calif., does the math: "One pound of red worms eats one-half pound of food per day. Thirty-two pounds of worms eat 16 pounds of food waste a day." That's what he needs to feed his 30 bins of worms. That's a lot of waste not going to a landfill.

Mr. Abbruscato sells worm castings, red wigglers, and a fertilizer he calls "worm tea," made from worm castings. The "tea bag" is a large lump of castings in a cheesecloth sack. It is steeped in water to create a strong infusion that is poured over plants.

"Castings provide a really good defense against pests," he says.

Abbruscato sells mainly to private customers and to schools running composting projects. Customers love the effects of the castings and worm tea. Roses grow bigger. Vegetables taste better. Abbruscato says this is because chemical fertilizer makes food taste blander.

Page: 1 | 2