What's the cheapest way to revive sterile earth where not even a blade of grass will grow, so that not only its grass returns, but crops may flourish as well? The answer is to let a few earthworms "run wild." Many nations have already verified that the impact of letting earthworms improve soil quality is startling. "It is the world's greatest fertilizer producer," says Kuo Teng-chih, a teacher at the Hsin-chu Teacher's College.

As the worm turns: Besides having "economic" uses like catching fish or feeding ducks, the earthworm has even more significance for mankind in that the history of its life is one of ecological balance.

The first scholar to note the importance of earthworms was Darwin. According to estimates by he and other scholars, 90 to 550 earthworms live in one square meter of soil. They continually penetrate the soil, eating an amount of soil each day equal to their body weight, while their digestive system is like a factory line sucking in rough earth and waste and producing "night soil beads," which are superior to bits of ordinary soil. Besides having greater air content, these "night soil beads" also have one third more water and microbes. Earthworm manure is excellent fertilizer. In Germany, the impact produced in the soil from the amount of worm waste per square meter per year was one to two times greater than that of the amount of fertilizer ordinarily used on farmland. "Earthworms show the greatness of nature's power of creating towers from sand," is how the German work Umwelt Schutz (Environmental Protection) puts it.

The busy little earthworm is even more like a shovel, and is a living tool for turning soil over. They can penetrate 1.5 meters into the loam. Broken up and turned over by them, the clay is loosened and softened, allowing it to circulate water and air more easily, and giving the root systems of plants even more room to absorb nutrients and to set themselves in. Living things in the earth are eaten by the worms, then expelled onto the topsoil or in the tunnels made by the worms. Also, the topsoil layer can penetrate deeper because of their drilling.

Chinese call the worm the "land magic." Perhaps this is because it is like a magic formula that turns earth into "gold."

Manufacturing revitalized land: Of course the ecology of soil relies on many types of creatures, but the life of an earthworm can be ten years long. Compared to ants, millipedes, and the larvae of many insects, you could say that they are the "backbone" of the soil. They are the primary creatures who break up clay; without them, the breaking up of the soil would create "fault lines" affecting the progress of the work of the secondary creatures who do the same task--bacteria and microbes. This would slow down the improvement of soil quality.

Because it can consume all kinds of decaying garbage, and produce richly organic fertilized soil, the earthworm has become a useful assistant employed by man to deal with garbage. Especially with the cost of handling garbage increasing rapidly--for example, the Six Year National Development Plan has set aside NT$100 billion for garbage disposal--employment prospects for the earthworm look sunny.

In many places in California, earthworms are used to clean the polluted mud at the end of sewer systems. Tainted land which has passed through the earthworm becomes revitalized soil, and can be sold and used. Reducing garbage can thus be profitable for people. People have also discovered that besides in the heavy-metals adulterated garbage produced by homes and industry, one can even discover earth-worms in abandoned mines, where the amount of heavy metals is extremely high.

Pollution control equipment: The body of the worm is like "pollution control equipment." No matter what the type pf waste, all will be altered by passing through the worm. Kuo Teng-chih explains that there is a calcium line in the body of the creatures which adjusts the acidity level in the soil; the amount of "positive" nutrients like potassium, magnesium, phosphorus, and calcium will be increased in soil which goes through a worm "out-of-body experience." The heavy metal zinc will be somewhat reduced.

"You could say that its body has a replacement capability," adds Kuo. Heavy metals which have passed through the worm can be more easily sucked out of the clay by plants. Its body structure can collect heavy metals in the loops below the skin of its intestines, up to twenty times the average amount that is in the soil.

If earthworms could be raised in polluted soil, and then after a time moved out, even if the total amount of heavy metals in the environment was not changed, the land could be improved in this way, and the speed at which heavy metals are "passed on'' could be increased, thus lowering the recuperation time for the land. In the recent "Soil Pollution Improvement Plan" of the Environmental Protection Administration, this idea has been put forward for study.

But researchers are concerned that even if it were feasible, "earthworms would be hard to find," says Huang Yi-tien, a researcher at the Taoyuan District Agricultural Improvement Station. Kuo Teng-chih adds that when she was small her family raised ducks, and her task was to dig up earthworms to feed the birds. "One shovelful could fill a tin can." Today vast stretches of land have been developed, and pesticides have been badly overused in cultivated areas. Earthworms are highly vulnerable to sudden acute poisoning, "so that in many hectares of farmland, you couldn't find a single worm," says Huang, who worked hard with Kuo looking for the creatures in agricultural areas in Hsinchu.

Even if in the future earthworms could conceivably be used to clean up contaminated soil, the costs would not be cheap.

[Picture Caption]

The earthworm is the best soil repairman; will it also become the terminator for heavy metals in farmland?(photo by Vincent Chang)