Fact Sheet One

  • What is the difference between composting with, or without worms?
As good as regular composting is (certainly better than the "landfill" solution), when we use worms to convert organic waste, the end product (compost) is enriched by the presence of large amounts of "worm casts" or "castings."
  • What is a "worm cast" or "casting"?
After a worm ingests organic matter, the material undergoes a change that is nothing short of a miracle. As Thomas J. Barrett once put it, "they (the worms) literally serve as colloid mills to produce the intimate chemical and mechanical mixture of fine organic and inorganic matter which forms their castings (excretions). In the mixing which takes place in the alimentary canal of the earthworm, the ingested materials undergo chemical changes, deodorization and neutralization, so that the resultant castings are a practically neutral humus, rich in water-soluable plant food, immediately available for plant nutrition."--(Harnessing the Earthworm, 1976, p.9)
  • You said that these worm casts were "a practically neutral humus." In what way is this beneficial?
Humus is beneficial to plants in at least three very important ways:
  1. By "capturing" toxins which are present in the soil. Humus (which is organic matter) has a high capacity to fix heavy metals in materials such as sewage sludge, farmyard manures, crop residues and peat, preventing plants from "taking up" more of these compounds than they need, then later releasing them when they are required.
  2. By acting as a "buffer." Humus can help plants overcome soil pH levels that are either too high, or too low. An acid-loving plant can still do well in a somewhat alkaline soil (and vice-versa), if large enough quantities of humus are present. This is due to the way humus prevents extreme pH levels from rendering soil nutrients "unavailable" to the plants.
  3. As a growth stimulator. "Experiments on wheat, barley, potatoes, grapes, tomatoes, beets, and other crops show that even in very low concentrations, humic acids (contained in humus) act to stimulate plant growth. Tests to determine just how humic acids work revealed that they are in an ionically dispersed state. In this form they are readily assimilated by the plants as a nutrient, over and above any normal mineral nutrition that plants get." --(The Rodale Book of Composting, 1992, p.26)
All of these benefits to plants, and more, are obtained by the presence of humus in the soil, and worm casts simply put, are biologically-active mounds that often contain as much as 40% more humus than is normally found in the top six inches of soil.
  • Aside from the humus content, are "worm castings" any more nutritious than regular compost?
Yes! As material in a compost heap decays (becoming humus), the various nutrients undergo chemical changes which make them more accessible to plants. In addition to this process, however, worms also reduce the overall volume of the material even further as they remove the ingredients necessary for their own survival, growth, and reproduction (mainly bacteria, rotifers, etc.) Thus, with the remaining substances compacted into less volume, the actual nutrient percentages rise accordingly. It has been noted by several researchers that earthworm casts usually contain more "total and nitrate nitrogen, organic matter, total and exchangable magnesium, available phosphorus, base capacity, and moisture equivalent" than their surrounding environment."--(C.A. Edwards and J.R. Lofty, in "Biology of Earthworms", 1977, p.201) This fact should hold true whether the surrounding environment is soil, manure, kitchen waste, or whatever.
  • Benefits to plants aside for a moment, how exactly does "vermicomposting" benefit people?
One of the most pressing problems we face as a society today, is what to do about the tremendous amounts of waste materials we produce. Landfills everywhere are reaching capacity, and even if we can find locations to establish new facilities, there will still be the problem of contamination and pollution caused by dumping these massive amounts of garbage. On the other hand, as our amount of waste increases, the available supply of many necessary resources diminishes. In the United States alone, "approximately 2% of all the natural gas that is consumed goes into the manufacture of nitrogen fertilizer."--(The Rodale Book of Composting, 1992, p.67)

Perhaps the lowly little worm will never completely solve either of these problems, but if given a chance, it could certainly lend a welcome hand. Approximately 70% of all the material currently entering our landfills, as well as all the farmyard manure in North America, and immeasurable amounts of yard wastes on top of that, are perfectly suitable as feed for worms. In return for this free "meal", the worm will replace roughly 60% of the volume we feed it with a soil enhancer of remarkable quality, and in the case of certain "waste" sources, a fertilizer not only as beneficial as expensive chemicals, but a natural and safe product to boot. And believe me when I say....if you feed them...they will eat! (My apologies to Mr. Costner for that last one, good-bye for now, and I hope to talk with you again.)


Copyright 1996 D. Brian Paley