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Is The Redworm An Earthworm, Too? |
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Written by Administrator
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Sunday, 11 September 2005 |
by Stephen White & Zorba Frankel, from our issue #7
It is not the intention of Worm Digest to settle the controversy of
whether or not redworms can/should be called earthworms. But we would
like to bring some clarity to this issue so that when our editors talk
about worms and their functions, our readers will understand what we
mean. From one point of view it matters very little what you call
something as long as you and the person(s) you are communicating with
know what you are talking about and what "it" does. Let's see what we
can do as a lay journal towards establishing some clarity for our
readers.
The question involves our friend the redworm, and whether or not it can
rightly be called an earthworm. Two researchers, Matthew Werner and
Uday Bhawalkar have brought to our attention different points of view
regarding nomenclature for earthworms and redworms This discussion is
certainly not restricted to these two men, but since the Worm Digest
staff respect both and have and will continue to publish their works,
they will serve as the point of departure for this discussion.
Matthew Werner, staff researcher in the Agroecology Program at the
University of California, Santa Cruz has stated (Worm Digest #5, "Real
Earthworms") that the redworm should be called an earthworm as it lives
in the soil, albeit the "surface layer of fallen plant litter," which
he considers a part of the soil. Due to this location of habitat for
the redworm he refers to it as an epigeic species, but an earthworm
nonetheless.
Uday Bhawalkar of the Bhawalkar Earthworm Research Institute, Pune,
India, prefers not to call the redworm an earthworm due to their
difference in functions. While the redworm has a role in feeding on the
organically rich surface layer of the soil, it also serves as "nature's
agent which quickly grows when excessive amounts of organic wastes are
dumped on the soil. They help reduce this pollution by consuming it,
producing their own biomass quickly and then migrate to die on other
patches of soil." According to Bhawalkar, this process is nature's way
of distributing the nutrients contained in the excess wastes over a
wider area.
By comparison, Bhawalkar states that the earthworm is a burrower, a
soil processor, "eating dead organics and rock particles, grinding and
excreting them as a finely ground mix which serves as food for
bacteria. They do not assimilate the organics, to the same extent as
the redworms, for themselves." Thus their numbers do not multiply as
quickly as do the redworms, whose assimilation rate is far greater.
This high rate of assimilation means that the nutrients consumed by the
redworms go into building their own biomass while the earthworm passes
on these nutrients in
a soluble form in their castings.
Quoting from Werner's article "Earthworm Ecology for Farmers," (Worm
Digest #5), "Earthworm feeding and burrowing activities incorporate
organic residues and amendments into the soil. These behaviors enhance
decomposition, humus formation, nutrient cycling and the development of
soil structure. Earthworms increase the amount of nitrogen mineralized
from soil organic matter. Nitrogen-fixing bacteria are found in the gut
of earthworms and in earthworm casts, and higher nitrogenase activity,
meaning greater rates of N-fixation, are found in casts when compared
with soil." In addition, the increased ability of soils to absorb water
and therefore drain better is also a known result of earthworms.
Now, if you wanted to improve a plot of soil by increasing the
earthworm population therein, and someone sold you redworms for that
purpose, I believe that both Werner and Bhawalkar would shake their
heads, NO! No matter what you call it, it's not the right worm for that
function. Simple and clear.
So what is Worm Digest's position on the redworm/earthworm question?
Worm Digest will refer to both redworms and the burrowing species as
earthworms. We will also use the terms "redworm" and "burrowing
earthworms" to refer to those worms specifically. |
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Last Updated ( Sunday, 18 September 2005 )
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