Contributions of various kinds are made to garden soils by "organisms" other than fungi and bacteria. I refer to creatures that live at least part of their lives in soil and are large enough to be seen with the naked eye. Most of them are outright garden or lawn enemies and are discussed (with recommended control measures) in Chapter Fifteen. The earthworm, however, defies such simple classification. Is it a "good guy" or a "bad guy"? I shall try to bring an answer-or at least a better understanding-out of the fog of controversies, misinformation and half-truths that surround the earthworm today as they have for many years.
Especially during the past two decades, flamboyant and extravagant advertising has created a picture which is completely false and misleading. The earthworm has been credited with being the source of all true fertility (ignoring completely the much more vital role of other soil organisms). It has been hailed as the savior of mankind. Articles have actually appeared in print which blame increases in human cancer on the destruction of earthworms by chemicals and modern tillage methods 1
The authority most frequently quoted to back up these claims is Charles Darwin, who in 1885 wrote a book, The Formation of Vegetable Mold, in which he reported his observations of the role of earthworms in soil formation and modification. This was a sound piece of observation, and obviously the work of a man familiar with the scientific approach to problems. Although today we can add a few facts to his original observations, we cannot refute bis conclusions. The difficulty lies not in what he said about earthworms but in how his account has been "doctored" or misinterpreted.
Darwin reported (and his findings have been confirmed by later observers) that earthworms in an acre of ground move as much as IS tons of soil a year. This adds up to a layer about 1/l0th of an inch deep over the acre. This does not mean they move only the upper 1/lOth inch, since they do go quite deep at times. However, the total mass moved from place to place in a year's time will equal that amount of soil. And this gives the worm credit for always turning over fresh soil, when it is obvious that considerable backtracking is inevitable so that the same soil may be moved several times a year. In any case, earthworms would take 70 to 100 years to turn over the same amount of soil that a man can turn over in one hour with a rotary tiller. Thus the soil-turning efforts of earthworms seem rather far from the magic process described for us in such glowing terms by earthworm-farm advertisers.