April 1, 2005:
Amy Stewart's The Earth Moved: On the Remarkable Achievements
of Earthworms is a must-read for all farmers, gardeners, budding
oligochaetologists, and anyone curious about life underfoot.
Stewart, an avid organic gardener and vermicomposter herself, has
a smart and quirky style that makes this “everything you ever
wanted to know about terrestrial worms” tome as fun to read
as it is informative.
The author tracks down Charles Darwin, recently returned from his
famous voyage on the Beagle, discovering—in the unlikely world
of his uncle's backyard—the awesome power of the lowly earthworm
and its singular role in creating “vegetable mould”
(the contemporary term for the rich, uppermost layer of fertile
When Darwin wrote—in the last published work of his life—that
earthworms were essentially nature’s plow and that an acre
of good garden soil might contain 50,000 earthworms (we now know
that figure to be closer to 1 million) yielding 18 tons of castings,
or earthworm manure, annually, his contemporaries scoffed, just
as they had initially doubted his evolutionary theories, Stewart
As undaunted as Darwin himself, Stewart sets out—through
keen observation, interviews and research—to make her case
for the earthworm’s greatness.
“Over the last one hundred years, earthworm scientists…have
come to quantify what farmers have always known: that worms, through
their actions, substantially change the earth,” she writes.
“They alter its composition, increase its capacity to absorb
and hold water, and bring about an increase in nutrients and microorganisms.
In short, they prepare the soil for farming.”
And that’s not all, according to Stewart (and Darwin). Earthworms
are also capable of making complex decisions, such as selecting
the precise size and location for leaves and twigs when constructing
Another useful fact you will pick up on this subterranean sojourn
is that—as far as your farm and garden are concerned—different
types of earthworms are best suited to different types of activities.
Red wigglers (Eisenia fetida) for instance, are epigeic worms, living
a nomadic life in the topsoil. They have relatively short lifespans
and multiply rapidly to match the available food source, making
them a great choice for your worm bin or compost pile. Anecic worms
like nightcrawlers (Lumbricus terrestris), on the other hand, live
up to six years and build permanent vertical burrows deep into the
soil. These are a poor choice for captivity.
Ah, the rhizosphere, that favorite universe of organic gardeners
everywhere. It’s here, says Stewart, where you’ll find
endogeic worms, little yellowish-brown (sometimes gray or slightly
pink) creatures that rarely make it to the surface. Precisely because
they lie low, Stewart tells us, many farmers choose these when inoculating
their soil with earthworms (because they are less likely to be disturbed
by cultivating activities).
With utmost sincerity, Stewart laments that she’ll probably
never get to see a giant earthworm since many species—such
as Oregon’s 3-foot Driloleirus macelfreshi—are becoming
extinct even as they are being discovered.
Readily admitting she's not a scientist, Stewart does an excellent
job of conveying her sense of wonder and discovery as she progresses
from somewhat reservedly taking that first little red wiggler out
of the backyard bin she’s kept for years and watching it slither
across her palm, to a more intimate relationship with her subject.
“I pulled my glove off and ran a finger along the worm’s
back, from head to tail. It stretched as I touched it, lengthening
each segment under the pressure of my finger. Still, it didn’t
seem to be trying to escape, just extending itself. I stroked it
a few more times, slowly, guessing that a faster stroke would only
If that’s not enough to get the earth moving, how about this:
a single earthworm has both sets of sexual organs and reproduces
by lining up its body with a partner so the ‘he’ parts
match up with the ‘she’ parts.
If America is a great melting pot aboveground, Stewart reveals,
a similar mixture is going on below. Most garden variety earthworms,
we learn, hail from somewhere else. And ever-more-rare native species
are being displaced by habitat destruction as well as by competition
Of particular interest to farmers is the fact that many of these
non-native species—such as nightcrawlers, red wigglers and
field worms (Aporrectodea caliginosa)—arrived in North America
with early European settlers via “the soil of potted plants,
the ballast of ships, the hooves of horses, and the wheels of wagons.
Whether they came as stowaways or invited guests, there is no doubt
that foreign species of earthworms…came west with settlers
and helped turn the already rich valleys and plains of the Midwest
into some of the best farmland in the world.”
And how are these little pioneers faring?
“Over the last few decades, earthworm censuses have found
over a million worms per acre in Geneva, New York; Frederick, Maryland;
and La Crosse, Wisconsin."
Ironically, as Stewart reveals, just as earthworms spent the past
couple of centuries helping to turn the earth and increase the microbial
community that fosters healthy crops and fertile soil, these miracle
workers are also helping to clean up the pollution wrought be a
half-century of chemical agriculture.
In fact, we learn, it was none other than Rachel Carson herself
“who reported that worms have an amazing ability to absorb
whatever is in the soil, and they were able to take up huge concentrations
of DDT and still live.” Then there’s their use for processing
biosolids in state-of-the-art sewage treatment plants. The list
Public Servant No. 1? Stewart makes a good case for it. Read “The
Earth Moved” and you may think so, too.