The Vicious Circle of our Ignorance

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The earthworm brings it to light

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The Earthworm, builder of our top-soil

Since ancient times, earthworms were animals very familiar to man. Also known as night crawlers, earthworms and microorganisms are the builders of good and productive soils. Aristotle called the worms, the intestines of the earth. In Egypt they knew of their importance, so Cleopatra imposed a law which prohibited the withdraw of night crawlers out the country. The tunnel-systems and the excreted mucilage insure that the fertility of the soil does not get destroyed by rain and wind. In 1837 Charles Darwin spoke to the 'Geologic Society' in London about their great importance for the creation of our top-soil. He was one of the first scientists that researched them systematically.

Night Crawlers lived here 200 million years before man.

Night crawlers possibly started to exist about 200 million years ago. Their mayor development goes hand in hand with the Jurassic Period and the development of flowering plants. Worldwide, there are at least 220 species of worms, of which 39 can be found in Europe.

The importance of their activities for the health of plants and thereby for the health of humans can be measured in the over 3000 books and texts written about them. Max Bieri lectures about them at the ETH, (Eidgenössische Technische Hochschule) of Zürich in Switzerland. In 1997 there was a moving exhibition 'Regenwurm (Earthworms)' which visited different Swiss museums. In Switzerland, you'll be able to find worm-composters which can be placed in apartments, schools or in basements.

Different areas of activities

The Earthworms that are common in Switzerland (unfortunately I have not done any research in Costa Rica yet) can be divided into three ecological groups. The first group lives in the top levels of the soil for instance the Compost-worm (Eisenia foetida). The next group moves around the upper areas of the roots of plants for instance the Common earthworm (Allolobophora caliginosa). And the third group makes tunnels into the mineral soils up to 10 feet deep for instance the Dew-worm (Lumbricius terrestris). These three and a few others are the main actors in our gardens, fields and compost piles. We want to have a closer look at them:

The Dew-Worm (Lumbricius terrestris)

Der Tauwurm (Lumbricius terrestris)

This happens to be the largest in Switzerland and is also called the Eal-Worm there. It can reach up to one foot in length. It drills vertical tunnels up to 20 feet into the ground. It is also the only worm that comes up to the surface mainly at night or early morning when there is dew. There it deposits the well-known little mounds at the different entrances of its living quarters, copulates and pulls leaves and other stuff into its tunnels. These tunnels, which are all plastered with worm-excrement, are also used by deep reaching roots. The tunnels have the additional duty to regulate water and gases in the top-soil.

The Common Earthworm (Allolobophora caliginosa)

Der Gemeine Regenwurm, Wiesenwurm oder Feldwurm (Allolobophora caliginosa)

This worm is also called the Grey-worm, Grass-worm or Field-worm. It is slimmer and greyer than the Dew-worm. It mostly moves around the areas of roots. It never comes to the surface voluntarily. Sometimes it goes as deep as 10 feet into the ground. It literally ploughs up the top three feet of the ground and for that reason is of extremely great value for gardens and agriculture.

Its tunnels, together with the ones of the Dew-worm, can be over 1000m long within a cubic-meter of soil. The volume of these tunnels can be up to 1% of the volume of the ground. When it rains, these mainly horizontally dug tunnels function like a sponge. Equally as with the Dew-worm, they are plastered with the important mineral, mucilage, and humus-soil mix. They create an excellent storage for nutrients that are safe from being washed away.

The Compost-worm (Eisenia foetida)

Der Kompostwurm (Eisenia foetida)

For this as well as for the Red-worm, clever worm-farmers have invented several fantasy names. For instance Manure-worm, Tennessee Wiggler, Red Californian, and Zebra-worm to mention just a few. It grows up to half a foot long and has visible yellow rings. It can only survive if it has sufficient organic material to feed on.

It finds this material in compost piles, manure piles, and under a thick cover of mulch. Opposed to the other worms, which are mostly active at temperatures of around 20º Celsius, they are more active with a temperature between 15 and 25ºCelsius. It seem that in Europe the preferred breeding-worm is the Compost-worm because it multiplies the fastest.

A fter Bieri identified the worms that I purchased at a fishing-supply store (supposedly their best-seller) as Eisenia foetida, I had great doubts about the statement found in many books that this worm is not apt for fish-bait. But the fact is that organic garbage will be composted about four times faster with them. In the German town called Rommersheim in 1983, the first public worm-compost installation for the town waste was introduced.

Red worm (Lumbricius rubellus rubellus)

Der Rotwurm (Lumbricius rubellus rubellus)

This worm only grows up to 12cm (little less than 1 foot) and it belongs, just like the Compost-worm, to the species that prefers the top layers of the ground as well as compost and manure-piles. It is the preferred breeding-worm in the United States. It also multiplies very fast and is used as fish-bait there. The Red worms as well as the Compost-worms have restricted usability in areas where there is winter-frost. Since they are only active as low as 20cm into the ground, a very thick layer of mulch is needed in these areas, to prevent the worms from freezing to death.

Other species of worms

In mineral-soils in Europe you'll find the so called Mucilage-worm (Allolobophora rosea). In the rotten wood of the forests lives the Stubben-worm (Dendrobaena octaedra) and in the fields we occasionally can see the Bluish Earthworm (Octolasion cyaneum). This looks very similar to the Garden-worm, (Allolobophora chlorotica) which we mainly - you guessed it - find in gardens. (See picture No. 4 at the very bottom). The poorer the soil is in organic matter, the longer the worm needs for its development and the larger they get. In Australia, there are Earthworms that are over 10 feet long and in some cases have a diameter of 8cm.

A heart but no Eyes and Teeth

Der Kopf des Regenwurmes

Earthworms are composed of 60 to 200 similar segments. Only the head-part is different. Its blood is red and the breathing occurs through the whole surface of the skin where he absorbs the freed oxygen of the water. In the open air, it would quickly suffocate. And in the sun, it would survive only a very short time. If a worm is cut in two only the front-part survives and only if it is long enough.

Worms move with muscle-contractions and with the 4 pairs of bristles that grow on each segment. The earthworm has no eyes but about 100 light-cells that are distributed on the front- and back-segments. Special sense organs for chemical stimulus make it a real gourmet. It mainly feeds on plant-substances that are humid and pre-digested by microorganisms or digested by plant-eating animals.

Der Darm des Regenwurmes Worms will draw in or suck their food because they have no teeth. For that reason earthworms cannot damage roots or plants. In their pre-stomach, the food will get moistened with drops of Kali and then go to the muscle-stomach where it gets mixed with tiny stones. That's how the so important mineral, mucilage, and humus-soil mix gets created. Then everything goes into the intestine. There, just as in humans, the nutrients pass through the skin of the intestines and the rest goes out the back-end as excrements.

Population Explosion in time laps photography

Earthworms are hermaphrodites. During pairing two worms lay together in opposite directions. Mucilage holds them together until the eggs are interchanged. These will be fertilized when there are favorable weather-conditions and a ring of mucilage with the eggs discharged from the body.

As soon as this ring is pulled off over the head, it will close over the eggs and form a so called cocoon. Depending on the kind of soil, temperature, worm species, and time of year, the time of incubation, the amount of cocoons, as well as the amount of eggs per cocoon vary. One worm can produce up to 500 worms per year!

Scientists regret

In a scientific study by the ETH (Eidgenössischen Hochschule in Zürich) the scientists determined that the importance of the earthworms for the entire life above the ground is far underestimated. That especially applies with regards to our food. Erhard Henning writes that the application of earthworms is one of the most important duties, if we want to have a chance to save our soils. Renowned scientists confess with rare openness, that the way agriculture is performed today, most of the arable land will be destroyed sooner or later (see Sahara) and that the makeup of our soils and the biological quality of our food is influenced very negatively.

Earthworms are unbelievably productive

If one would not constantly destroy the living space of the earthworms with spades, plows, chemicals, and un-composted manure, we could enjoy almost incredible amounts of free fertilizer. One average worm weights an average of 1gr.

Depending on the makeup of the soil and the crop, 1 square meter of soil shelters 10 to 400 earthworms. Again depending of the kind of soil, each of these worms produces half or the whole of its own weight in worm-excrements per day. Franz Häni, director of the 'Landwirtschaftlichen Technikums in Zollikofen' counted in a test hectare after three years of constantly planting a crop (without interruption) over 300 earthworms per square meter.

These worm-excrements with a total self-weight of over 3 tons, produce in one year the incredible amount of up to 1000 tons of worm-excrements. That is absolutely the best fertilizer that exists. Just about everything grows with it. It is the perfect top-soil for all plants. Research in the USA, Australia, Germany, Russia, and on the ETH in Zürich show that earthworms' excrements is 5 times richer in Nitrogen that plants can assimilate, 7 times richer in Kali, 2½ times richer in interchangeable magnesium, 1½ times richer in Calcium and 5 times richer in microbes as is the soil surrounding it.

Over 220 kg of free Nitrogen per hectare

Only 1g of worm-excrement contains around 50 million bacteria. They again increase the production of CO² which is indispensable to produce a good crop. A well maintained population of earthworms plows over the entire top-soil during a time period of ten years. Only taking in consideration the 10mg of nitrate produced by every worm that dies and its excrements amounts to 220kg of nitrogen pro hectare and year.

Worms plaster their Apartments

With very durable and nutritious excretions, the earthworms plaster their living-tubes. And they are durable! In the area between Göttingen and Kassel in Germany, they discovered some of these tubes that were created in a warm period of the last ice-age. Plants love these tunnels.

Even the strongest rains cannot destroy them. Soil that is full of these tubes can absorb up to three times more water as a conventionally worked soil. With the incredible strength of the worms - they can push 50 to 60 times their own weight - they drill relentlessly through the soil. To avoid injury, a mucus is constantly excreted. Half of the produced Nitrogen consists of mucus and proteins. The other half is excreted as urine and ammonia.

The Vicious Circle of our Ignorance

Over 3 billion organisms live in 1cm³ of good soil. It takes months until they organize themselves into to the right layers of soil that are apt for them. Some organisms need oxygen and light and for others it is deadly.

Some of them multiply every 20 minutes, others no as fast. Some of the most important micro-organisms can only survive near roots. And exactly here starts the vicious circle of our ignorance because by spading, plowing, and raking, everything is turned upside down. A signifficant number of the organisms and soil-creatures die. The worst such torture is performed in fall because in addition to the bad situation comes the cold, from which many of these organisms don't have enough time to escape into deeper soil.

The material that has been plowed under will now decay. Decay on the other hand causes many problems. With it, harmful and pathogen substances are created. The following year, more herbicides and pesticides will be needed. Using them, still more microorganisms get killed. The soil ceases to produce healthy produce. Since the soil lost its ability to maintain water, every spring there are larger and more damaging floods, top-soil and nutrients get washed away.

Where do worms love to live

Except in the desert and eternal ice, worms live just about everywhere. Together with insect-larva, ants, spiders, centipedes, lice, mites, bugs, bacteria, mushrooms, fungus, algae, and even larger creatures like snails, toads, and birds, the earthworms create a complicated network of relationships and effects.

To get a high worm-count per square-meter of soil, the soil should never or only for a very short time lay bare. It should only be worked when the sky is cloud-covered and does not have an extreme pH-count. But most important of all is that there is always enough organic material present. With enough food worms multiply fast and improve even poor soils just as fast.

They prefer waste that is well rotted, high in nitrogen and humid. The soil should be worked as little as possible and only with light-weight machinery. An increase in productivity is the reward for this effort. As proof you may look at the following scientific test from Holland: At new added grounds behind a water-dike they tested an area into which they injected 500 earthworms per m² of the Allolobophora calignosa species. The result was: Double yield with wheat, four times yield with hay and with clover the yield was even tenfold.

On can breed worms

Since it is impossible to cross the different species of worms, one should really say multiply. In the USA, as already mentioned, it is mainly the red worms that that get multiplied, while in Australia it is completely other species. In Germany, Austria, and Switzerland, it is the Compost-worm that is preferred.

Here in Costa Rica I saw some worm-breeding done by our Ex-President Mr. Rodrigo Carazo, but I have not looked at them more closely.

The following report from Canada may illustrate what has been said above: Captain C.E. Misener from Wellflect reports in the 'Better Soil' magazine: On our farm we plant 12 hectares raspberries, 8 of strawberries, 2 of blackcurrants, and 2 of blackberries. To maintain the fertility of our soil and to raise strong, resistant plants, we have used a worm-farm with over 100 Million red worms since 1952.

We multiply them in two worm-beds that are 1.2 meters deep, 1.2 meters wide and 25 meters long. The worms get fed two wagon-loads of manure that has rotted at least one month, sawdust, chaff, stone-powder, and wooden ashes. From here on it's the worms that take over the work. Since we are applying worm-compost, we are getting three time the yield and we are getting the highest prices on the market.

A new pet

Our new pet, the compost-worm, is the title of Max Bieri's case-study of the ETH Zürich. Some years ago I had a worm-composter from Australia with several thousand worms in my kitchen. (Unfortunately they are not available here in Costa Rica). They turn kitchen-garbage into priceless worm-compost. There was no bad odor coming from this kind of 'garbage-can'.

The excess worms can be taken to the garden. What they liked most was Onion peels, coffee-grounds, potato peels, and fruit leftovers. Spicy food and salty stuff can not be fed. The extra liquid is odorless and can be used as fertilizer for the house-plants.

The many uses

Besides the already mentioned uses, worm-manure can be used as surface-fertilizer for all plants. If you add about 10% to the soil to raise new plants it will do wonders. Excess worms can be used in the garden, in the compost-heap, or to start a new breeding bed. Also they are popular as fishing-bait or food for a trout- or chicken-farm. If you put some worm-compost into the seed-rows when planting, the plant will be much stronger and resistant against disease. Last but not least an extract from worm-compost serves as a good natural pesticide.


  • Original title of the article: Ein reger Wurm der Regenwurm, published in the magazine Natürlich.
  • ETH Zürich: Fallstudie Der Regenwurm.
  • Otto Graf: Unsere Regenwürmer, Lexikon für Freunde der Bodenbiologie.
  • Walter Buch: Der Regenwurm im Garten.
  • Rentner Aktiv Club: Praktische Gebrauchsanleitung zu Humusproduktion und Kompostwurmzucht.
  • Fredy Vetter: Regenwurm, Führer zur Ausstellung.
  • Werner Peters und Walter Waldorf: Der Regenwurm - Lumbricius terrestris L. Eine Praktikumsanleitung.
  • Charles Darwin: Die Bildung der Ackererde durch die Tätigkeit der Würmer.
  • The Staff of Organic Gardening Magazine: The Encyclopedia of Organic Gardening.
  • Allan Windust: Worms Down under for Farm, Garden, School, Profit, and Recycling, Australian Farm and Garden Series 1995.
  • Erhard Hennig: Die Rhizosphäre - Lebensraum für das Edaphon, Regenwürmer, Wurzel und Boden (Manuskript).
  • Erhard Hennig: Geheimnisse der Fruchtbaren Böden.
  • Eike Westermacher-Dotzler: Abundanz von Regenwürmern für den C- und N-Umsatz.

    Text and pictures Jörn Malek. The team of 1-CostaRicaLink wishes you the best of times in our little paradise called Costa Rica.

  • Der Gartenwwurm (Allolobophora chlorotica)Der Schleimwurm (Allolobophora rosea)
    Bläulicher Regenwurm (Octolasion cyaneum) Stubbenwurm (Dendrobaena chlorotica)