Worms Go, Plants Grow

6/16/2005

Lexington Herald-Leader

By Beverly Fortune

Worms in apples: bad.  Worms in soil: good.

Gardeners count themselves lucky when they turn over a spadeful of earth to find earthworms, and the more, the better.

These hard-working helpers are a sure sign of loose, organically rich soil, a great environment for plants.

But exactly how do worms help soil and plants?

Some of the lowly worm's benefits come from its castings, or worm excrement, tiny pieces about the size of a pin head,  100 percent organic and odorless.

"Castings improve soil porosity (and) moisture retention," stimulate plant growth and repel an array of insects and diseases, said Dave Riddle of Franklin County, Ky.

In February, he and his wife, Lynn, started a worm farm, selling castings as soil amendments, and selling worm cocoons and worms in bulk. Want 1,000 worms?

"What is really special about castings that you don't find with regular compost or fertilizer is there are special plant-growth hormones in the humic acids of the castings," said Rhonda Sherman, extension solid-waste specialist at North Carolina State University in Raleigh.

Don't confuse growth hormones with nitrogen, she said. The nitrogen content in vermicompost is very low.

"But something physiological takes place inside the worm that produces these plant-growth hormones," Sherman said in a phone interview earlier this week.

In studies in which one group of plants was given regular fertilizer and another given fertilizer plus vermicompost, "there's a striking difference," Sherman said.

"Seeds germinate more quickly and plants have deeper, broader, more secure root systems, bigger leaves and more leaves. The stalk is thicker and the plant will produce more fruits and vegetables."

Just a little bit of vermicompost goes a long way.

"Ten percent by volume is ideal, but even 5 percent produces results," Sherman said.

Beneficial qualities of castings depend on what worms are fed, according to a study at Ohio State University Worms were fed hog manure, dairy manure, paper waste and food waste.

"The castings produced by hog manure have far outperformed the other castings," Sherman said.

A two-day worm workshop she held this week was just a few miles away from a hog farm where the largest working worm farm in the Carolinas also is located.

"It's their vermicompost that performed so well in these studies," she said.

Vermicompost suppressed several diseases on cucumbers, radishes, strawberries, grapes, tomatoes and peppers, according to research from Ohio State extension entomologist Clive Edwards. It also significantly reduced parasitic nematodes, aphids, mealy bugs and mites.

Sherman worked on solid waste issues, including training and education programs, for 20 years, the last 12 at North Carolina State. In 1993, she wrote a small pamphlet on how to set up and maintain a worm bin.

"It just flew off the shelves. We reprinted it about four times," she said.

Things mushroomed like crazy. Sherman moved quickly into commercial vermicomposting. To answer all the e-mail messages and telephone calls coming from 35 countries.

"People really want to know more about vermicomposting and how to do it on a larger scale, like the Riddles," she said.

The Riddles decided to get into vermicomposting last year. They renovated an old barn, weatherizing one section so the temperature can be maintained at 72 degrees.

Their first shipment of 22,500 earthworms, bought from UNCO Industries in Racine, Wis., arrived February 22, and the couple, who formerly owned a computer business, started to work.

Here is the worm-production cycle:

A 3 gallon bucket is filled with three gallons of moist peat moss, one cup of dairy feed and 250 worms.

Two weeks later, the worms have eaten their way through the peat moss, turning it into odor-free organic castings and producing cocoons.

The contents are dumped on a big shaker to separate the castings, the cocoons and the worms. The castings are bagged and sold as a soil builder. Adult worms are put into another container of peat moss to start eating again.

Two quarts of cocoons are scooped into a container. Within seven days, 1,500 baby worms hatch. "We have learned more about worms and worm reproduction than I ever thought," said Lynn, 37.

The Riddles currently have 68,000 worms, with space for 150,000.

WAYS TO USE VERMICOMPOST

Vegetables and annual flowers: Line sides and bottom of plant holes and seed furrows with about 2 inches of earthworm castings. Set plants and seeds in place, then cover with soil. Every two months in growing season, side-dress plants at a rate of a cup castings per plant or 1 cup per linear foot.

Perennials: Work a cup into soil in spring, summer and early fall.

Potted plants and hanging baskets: Add an inch of castings to top of soil, then mix in. Water. Repeat every two months.

Roses: Mix 4 cups of castings in soil around each rose bush.

New lawns: Apply 15 pounds of castings per 100 square feet to soil.  Sow grass seed, then keep moist until germination.

Established lawns: Spread 7 pounds of castings per 100 square feet.

Sources: Rhonda Sherman, North Carolina State University, and Wiggle Worm Soil Builder. (c) 2005, Lexington Herald-Leader (Lexington, Ky.)