EFFECT OF EARTHWORM DENSITY AND WATER QUALITY ON VERMICULTURE AND VERMICOMPOSTINC
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Date
2002
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University of Agricultural Science, Dharwad
Abstract
"Investigations on the effect of earthworm density and water quality on vermiculutre
and vermicomposting were undertaken at University of Agricultural Sciences, Dharwad
during 2000-01.
Two crop residues, soybean harvest waste and cereal straw having varied C:N
ratios were used as substrates. With the increase in earthworm density from 100 to 250
worms per bed of 1.0 x 1.0 x 0.5 m, the fecundity, non-clitellate and clitellate worms in
numbers increased progressively. Similar increase was observed with vermicompost
production which ranged from 11.17 kg at 100 worms density to 15.17 kg at 250 worms
density. When observed on per worm basis, the rate of increase in earthworm
development was higher at 100 worms density (7.25 and 5.61 fold) followed with 150
worms (5.48 and 4.30 fold), 200 worms (4.44 and 3.51 fold) compared to 250 worms
(3.69 and 2.97 fold) which was the lowest in both soybean waste and cereal straw. The
productivity of vermicompost was also higher at 100 worms (0.13 and 0 1 kg) inoculation
density in both substrates and it decreased (lowest of 0.07 and 0.05 kg at 250 worms)
with the increase in earthworm density. Between the two residues, soybean residue was
a good substrate for cocoon production, development of worms and vermicompost
production compared to cereal straw where the population growth and quantum of
biodegradation were relatively less. Considering various parameters, 100 worms per bed
appears to be the optimum inoculation density in both the substrates.
Higher number of cocoons, population growth and vermicompost was obsen/ed in
potable water and sewage water - potable water mix (1:5 proportion). The treatments to
follow this were water with RSC of < 2.5 meL""\ water with EC of 2 dSm""^ and sewage
water - potable water mix (1:2 proportion). However, other treatments such as water with
RSC of 5 meL'\ water with EC 4 dSm""^ were moderate in their effect. Direct application of
sewage water exerted adverse effect on the development of worms. No development of
worms was seen in treatments, water with EC of 8 dSm'^ and RSC of 10 meL""' due to
initial mortality of the worms immediately after release indicating that they are unsuited for
vermiculture and vermicomposting for all three species.
The toxicity of salt water on the survival of worms was in the order of Eudhlus
eugeniae < Eisenia fetida < Perionyx excavatus whereas for sewage water it was
E. fetida < E. eugeniae < P. excavatus."
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