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 soil).
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 tells us.
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 their burrows.
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 harm it.”
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 from non-natives.
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 goes on.
Public Servant No. 1? Stewart makes a good case for it. Read
The Earth Moved and you may think so, too.
|
