Earthworms for Soil Improvement

The potential market for earthworms and earthworm breeding stock is almost as wide as the field of horticulture itself; from the housewife who has a few flower pots or window boxes to the home or truck gardener, orchardist, florist, nurseryman or landscape gardener.

The large scale horticulturist could hardly afford the cost of earthworms at retail prices for all of his needs, but he CAN be interested in starting his own earthworm or vermicomposting project, becoming a prospect for breeding stock.

The earthworm has been aptly called "The Gardeners Unpaid Handyman". It tills the soil around root areas by its tireless burrowing. The burrows form channels through which root growth may reach down into the subsoil for minerals and moisture. They also absorb rainfall quickly for storage in the soil instead of allowing it to run off, carrying away valuable top soil. Most important of all, the earthworm eats, digests and enriches dead and decaying vegetable wastes in the soil, ejecting it in the form of castings, rich in plant food value, water-soluble and immediately available to plant roots.

Earthworms also break down thatch and the other the raw materials of organic matter, and spread it evenly throughout the top 12 inches of soil, further improving the soil. Millions of beneficial bacteria that break down thatch are produced in the gut of earthworms. These bacteria, along with a superior fertilizer produced by earthworms, are put into the soil with earthworm "castings". This top quality fertilizer contains nitrogen, phosphorus, potassium and many micronutrients in a form all plants can use. Earthworm castings contain five times more nitrogen, seven times more phosphorus, 11 times more potassium, and 1,000 times more beneficial bacteria than the material contained before the earthworm ingested it. The N-P-K ratio for worm castings is 0.5-0.5-0.3 consisting of 50% organic matter and 11 trace minerals. In a 10 x 20 foot garden with only five large earthworms per cubic foot of soil, over 35 pounds of this superior fertilizer is produced by the earthworms. In healthy soil with worm populations of 25 per cubic foot of soil, more than 170 pounds of highest grade fertilizer can be produced in a year in a 10 x 20 foot garden. This is more than 18.5 tons per acre per year. Gardening supply companies take advantage of the market for earthworm castings as fertilizer by selling the castings for about $12-$25 per pound.

Earthworms are probably the most important nonmicroscopic soil dwellers. Worms either drag their favorite foods of dried leaves and other organic materials down into their borrows or come to the surface to eat and digest them. One inch of organic matter laid on the surface of soil with a healthy earthworm population will be completely eaten and digested within a few months. Earthworms also secrete calcium carbonate, a compound which helps moderate acid or alkaline soil toward desirable neutral ph over time.

In advising your customers regarding the use of earthworms for soil improvement, it is advisable to recommend the use of spawn (young worms in all stages of growth) for two reasons: (1) the newly hatched worms will adapt themselves more readily than mature worms to their new environment, and (2) your customer will conserve his more valuable breeding stock for further egg capsule production. With the young worms, they should use a liberal amount of rich compost because it provides food for the transplanted worms.

It is well to remember that domestically grown worms are "compost" worms and not soil worms. When transplanted for horticultural purposes, they must be CONTINUOUSLY fed by mulching with organic matter such as leaves or grass clippings to supply them with food. It is in and under this layer of organic mulch where the worms live. They must also be watered in dry weather if they are to survive and continue to multiply.