Agriculture Reference
In-Depth Information
Edwards 1988); it is capable of decomposing large quantities of organic wastes rapidly and
incorporating them into the topsoil (Neuhauser et al. 1979, 1988; Edwards 1988; Kale and Bano
1988). The life cycle of
ranges from 50 to 70 days, and its life span can be 1 to 3
years. This species is more productive in terms of rates of growth than many other earthworm
species and would seem to be a suitable candidate for vermicomposting systems in regions where
maintaining its optimal temperature of 25
E. eugeniae
A
C is both feasible and economic. Although the large size
of
E. eugeniae
makes it much easier to handle and harvest than commonly used species such as
E. fetida
, it seems more sensitive to disturbance and handling and may occasionally
migrate from breeding beds. However, it has been grown commercially for fish bait for a long time
in the United States, which is evidence that is comparatively easy to rear. It is probably one of the
two preferred species, together with
and
P. excavatus
P. excavatus,
for vermiculture and vermicomposting in tropical
climates (Domnguez et al. 2001) (see
Chapter 19
, this volume).
Perionyx excavatus
Perrier, 1872
Perionyx excavatus
is an earthworm belonging to the Megascolecidae, commonly found over a
large area of tropical Asia (Stephenson 1930; Gates 1972), although it has also been transported
to Europe and North America. This is an epigeic species that lives solely in organic wastes. High
moisture contents and adequate amounts of suitable organic material are required for populations
to become fully established and to process organic wastes efficiently. The life cycle of
P. excavatus
takes 40 to 71 days from hatching to maturity. This species prefers high temperatures and may die
at temperatures below 5
This is a prolific species that, with about 90% hatching rate and 1.1
hatchlings per cocoon, has a net reproductive rate of nearly 20 cocoons week
A
C
.
(Edwards and
−
1
Bohlen 1996; Edwards et al. 1998).
Pheretima elongata
(Perrier, 1872)
Pheretima elongata
is a megascolecid earthworm species has been tested for use in vermicompost-
ing organic solids, including municipal and slaughterhouse wastes; human, poultry, and dairy
manures; and mushroom compost in India. A project in India using this species claimed it had a
commercially viable processing facility for the ÑvermistabilizationÒ of 8 tons of organic solid waste
day
. These workers developed a ÑvermifilterÒ (packed with vermicompost and live earthworms)
that produced reusable water from sewage sludge, manure slurries, and organic wastewaters from
food processing (Edwards and Bohlen 1996).
−
1
appears to be restricted to tropical
regions and may not survive severe winters such as those in temperate regions.
Pheretima elongata
Table 20.1
summarizes some aspects of the biology of these vermicomposting earthworm
species. A comparison of the duration of the life cycles and the reproduction potential of the
earthworm species suitable for vermicomposting is presented in
Figure 20.1
.
INFLUENCE OF ENVIRONMENTAL FACTORS ON SURVIVAL AND
GROWTH OF EARTHWORMS
Cocoon production, rates of development, and growth of earthworms are all affected critically by
environmental conditions. Species of earthworms that can be used successfully in vermicomposting
are relatively tolerant of the varied environmental conditions in organic wastes, so relatively simple
low-management windrow or ground bed systems have been used extensively in the past to process
wastes. However, it has been demonstrated clearly that these earthworm species have well-defined
limits of tolerance to certain parameters, such as moisture and temperature, and that the wastes are
processed much more efficiently under a relatively narrow range of favorable chemical and envi-
ronmental conditions. If divergence from these limits is great, the earthworms may move to more
