Pittsburgh Permaculture

Be afraid… very afraid.  Non-native, invasive, alien species of worms such as the the European nightcrawler (Lumbricus terrestris) have been silently and invisibly invading the ground beneath our feet.  And–get this–they’re destroying the dynamics of forests thereby potentially leading to the detriment of native ecosystems.

This dangerous incursion by the legless burrowing lizard may be responsible for imperceptibly small but important changes to species composition prior to clear-cutting the land for timber before putting up another McMansion housing complex.  Thus, I suggest we start a decadal, multi-million dollar research project to determine the scope and hazards presented by the great worm invasion with investigation into worm removal and mitigation measures.

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Of course, I’m being facetious.  If there’s one thing that environmentalists (or permaculturalists) need to recognize is prioritizing risks and opportunities, and the threat of non-native colonizing earthworms is (how shall I say politely?) ridiculous in comparison to the threat of non-native colonizing humans.

In fact, worms may be one of the most under-appreciated but vital actors in maintaining soil health and fertility.  More than a few people would probably be surprised to learn that Charles Darwin spent the last 30-odd years of his life dedicated to the investigation of worms culiminating in the publication of his canonical worm text, “The Formation of Vegetable Mould Through the Action of Worms,” in which Darwin stated that,

“It may be doubted whether there are many other animals which have played so important a part in the history of the world as these lowly organised [sic] creatures,”

“Without the work of this humble creature, who knows nothing of the benefits he confers upon mankind, agriculture, as we know it, would be very difficult, if not wholly impossible.”

This might be a slight overstatement, yet it drives at the critical point: worms are pretty darn awesome.  They:

1) Convert residual carbonaceous materials into long last humus (referred to as “vegetable mould” by Darwin);

2) Create long-lasting macropores which allow for greater downward flow of water thereby preventing erosional events;

3) Decrease bulk density while increasing soil aeration, tilth, and root penetration;

4) Transfer recalcitrant organic compounds and fertility agents downward into deeper soil horizons;

The combined impact of these actions over an acre of land (which can contain 40,000 to 2 million of the invertebrates) is, in the words of Bill Mollison, like an “innumerable army of pistons pumping air [and nutrients and building miles of pipelines] in and out of the soils on a 24 hour cycle.” Thus, the process of “bioturbation,” the disturbance of soil by living creatures such as earthworms in temperate climates (and termites in tropical ones) is a vital aspect of soil health and agricultural systems such as no-till should be utilized in order to take care of these creatures who manage the soils for us free of charge.

Interestingly, one of Darwin’s theories (not involving evolution) has recently got some press.  Darwin suggested some 172 years ago that the response of worms to vibrations in the soil was due to their avoidance response from mole predation.  This story leads us conveniently to the wacky world of “worm grunting”:

In the “Origin of Species,” Chuck rather melodramatically remarked that, “Even in the worm that crawls in the earth there glows a divine spark.  When you slaughter a creature, you slaughter God.”  Now, I’m not against using worms as bait or angling for fish for that matter, but for goodness sake can we put things in a little perspective–it’s the human threat that’s the real concern, not worms.

-Ryan

Ryan Hottle has run several market farms, worked in a commercial orchard and is currently a PhD student at Ohio State’s Carbon Management and Sequestration Center in the Ohio Agricultural Research and Development Center.