5.4.2.
Heap Method:
Thatched roof shed, with a flat ground is ideal
for vermicomposting. The vermicomposting beds can
be one metre wide while the length can run to the
entire length of the shed. Bricks may be used for
making beds and since the beds are only temporary
structures, mortar need not be used. Semi digested
compost is spread on the bed evenly to a thickness
of about 20 cm initially and then suitable species
of earthworms are introduced on the compost. The
rapidity with which vermicompost can be obtained
depends on the number of earthworms are introduced
in a unit area. Freshly prepared cow dung slurry
may be sprinkled on top of the compost containing
earthworms. It is desirable to maintain the moisture
at about 60 per cent for better earthworm activity,
throughout the vermicomposting process, by sprinkling
cow dung slurry periodically. Second layer of compost
to another 15 cm may be added on top of the first
layer once it is vermistablished.
It is estimated that 1000 tonnes of moist organic
matter can be converted by earthworms into 300
tonnes of compost (Bhawalkar, 1995; Ghosh Hajra,
1994). It is also estimated that 1800 worms, which
is an ideal population for one square meter can
feed 80 tonnes of organic waste per year. The
recovery of compost varies from 30 to 55 per cent
based on the type of agro waste used for vermicomposting.
Daily consuming or uptake of feed varies from
species to species. In general, daily uptake varies
from 100 to 300 mg/g. body weight. Various estimates
have been made. According to one estimate, an
earthworm can consume 8 to 20 g dung / year. So
at a population density of 1,20,000 adults / ha.,
dung consumption would be 17.20 tonnes / ha /year.
5.5. Screening and
separation:
Vermicompost should be heaped into small cones in
an open place. Within a few hours, almost all the
earthworms will settle down and the top and periphery
will be free from earthworms which may be removed
and dried in shade to reduce the moisture content
below 25 per cent. It may be sieved using 3 mm mesh
to separate uncomposted agro wastes which can be
reused. The earthworms at the bottom can be reused
for inoculation. The number of vermicompost beds
will vary depending on the quality of agro wastes
available in the estate. The natural enemies of
earthworms are ants, rats and bandicoots. The compost
beds may be covered with wire mesh of suitable thickness
and dimension facilitating adequate aeration.
5.6. Vermiwash:
In recent times, the commercial vermiculturists
have started promoting a product called vermiwash.
A liquid fertilizer collected after the passage
of water through a column of worm action is very
useful as a foliar spray. It is a collection of
excretory products and mucus secretions of earthworms,
along with the micronutrients from the soil organic
molecules (Ismail, 1997). Farmer in their own
ways have started collecting the liquid from the
culture tanks and are using it for foliar application.
One of the methods followed is to have outer and
inner vessels. The inner vessel will have an outlet
at the lower side of the vessels. The inner vessels
are filled with decomposing organic matter and
about 1 to 2 Kg earthworms are accommodated in
a 12 to 16 liters capacity vessel. As the earthworms
start feeding on the waste, water is slowly added
in to vessel in excess. The excess water flows
out through the outlet as thick syrupy fluid and
is collected in the outer vessel. The fluid so
collected is siphoned out and after diluting,
is used for foliar spray on different crops.
In some farmlands, the tank is built at an elevated
place from which the wash can be collected. The
slope provided in the tank, provides scope for
excess water to flow out in drops as thick syrupy
emulsion through a small outlet. This is collected
in a container and stored in bottles. It is opined
that this wash will have enzymes and secretions
of earthworms which stimulate the growth and yield
of crops and even helps to develop resistance
against pests and diseases in crops receiving
the spray. This vermiwash is sprayed on plants
as a foliar spray. If need be , the vermiwash
may be diluted with water before spraying, or
it may be diluted with 10 per cent cow’s
urine which is considered an effective pesticide.
6. Beneficial Effects
of earthworms:
6.1. Effect
on soil fertility:
Endogeices and anecices group of worms pass mixtures
of organic and inorganic litter through their
gut while feeding or burrowing through the soil.
Casts of surface feeding worms like Eiseina foetida
and Eudrils eugeniae contain only fragments of
litter. The humification process of organic residues,
takes place while passing through earthworm gut.
Their major role in decomposition appears to be
breaking down of organic residues and inorganic
fragments to smaller particles, enhancing microbial
activity.
|
