Vermiculture
Vermiculture is the culture of earthworms. The goal of vermiculture
is to continually increase the number of worms in order to obtain a
sustainable harvest. Vermicomposting is the process of converting
organic material into a humus-like material known as vermicompost.
Production of vermicompost requires maximum worm population density
all the time. However, to produce more worms, the population density
should be low enough that reproduction rates are optimised. The worm
Eisenia fetida commonly known
as 'compost worm', 'manure worm', 'red worm' or 'red wiggler' is
extremely tough and adaptable can be found wherever piles of manure
have been left to age for a few months. The
compost worm has a capacity for very rapid reproduction.
Advantages
Vermicompost is superior to
conventionally produced compost
Worms can be used on farms as high
quality animal feed
Vermicomposting and vermiculture
are potential sources of supplemental income to farmers
Disadvantages
Rapid production of vermicompost
requires more labour
It requires more surface area as
worms being surface feeders do not operate in material more than one
meter deep
Vermicomposting is more vulnerable
to environmental pressures like freezing and drought
Start-up resources in the form of
initial investment, time and labour are required
Compost worms need:
A conducive environment to thrive
called 'bedding'
Food
Adequate moisture (>50% water by
weight)
Adequate aeration
Protection from temperature
extremes
'Bedding' provides worms with a
stable habitat. It should have the following essential
characteristics:
High absorbency
Good bulking potential
High Carbon:Nitrogen (C:N) ratio
The bedding material may be made-up
of 'peat moss', 'horse manure', 'Newspaper' or 'paper mill sludge'.
Selection of bedding material is very important to successful
vermiculture. Manures are the most commonly used feed stock. The
bedding must hold sufficient moisture for the earthworms to thrive.
Worms cannot survive in anaerobic conditions. Earthworms
thrive in temperatures in the range of 20s(C). Such temperature
ranges stimulate reproduction. However, they die in temperatures
exceeding 35(C). Compost worms will redistribute themselves according
to temperature gradient.
Worms
can survive in the pH range of 5 to 9. Worms
are very sensitive to salts, preferring salt contents less than 0.5%.
Few toxic components to earthworms are:
De-worming medicine in manure
Detergent cleansers, industrial
chemicals and pesticides
Tannins
Earthworms in ideal conditions
reproduce quickly. Worm populations double every 60 to 90 days. Ideal
conditions being:
Adequate food
Well aerated bedding with moisture
content between 70 and 90%
Maintaining temperature between 15
to 30 C
Initial stocking densities more
than 2.5 kg/m2 but less than 5 kg/m2
Stocking density refers to the
initial weight of worm biomass per unit area of bedding. Starting
with a population density less than stocking density will delay the
onset of rapid reproduction. Population
density of worms greater than stocking density results in low
reproduction as there is greater competition
for food and space. The most
common densities for vermicomposting are between 5 and 10 kg/m2. Worm
growers tend to stock at 5 kg/m2 and tend to split beds when the
density has doubled. Following these guidelines, growers can expect
doubling of biomass in 60 days. Theoretically a stock of 10 kg of
worms can become 640 kg in after one year and 40 tonnes after two
years. The barriers in
achieving optimum rates of reproduction are:
lack of knowledge and experience
lack of dedicated resources
lack of preparation for winter
Rule of thumb is that one
ton of input results in one cubic yard of compost.
The
most common pests and diseases that earthworms are at a risk of are:
Moles
Birds
Centipedes
Ants
Mites
protein poisoning
The three basic types of
vermicomposting systems are:
windrows
beds or bins
flow-through reactors
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Vermiculture focuses on production
of worms rather than vermicompost.
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Vermicompost can be used as a method
for destroying pathogens.
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Vermicompost spread on land does not
cause contamination of ground or surface water.
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Vermicompost binds nutrients well
thereby preventing nutrient run-off from agricultural land and
ultimately preventing eutrophication of surface waters.
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There is potential for using compost
worms in natural filtration systems.
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One of the principal benefits of
vermicomposting is 'carbon sequestration'.
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Vermicomposting also addresses the
issue of worldwide depletion of carbon in soils. By
consistent application of compost or vermicompost an increased level
of carbon in soil has been seen.
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Worms aerate the matter as they move
through it resulting in fewer anaerobic areas and reduced methane
emission.
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One unit of vermicompost is as
effective as five to seven times of fertilizer in promoting plant
growth and yield.
Vermicompost is more
efficient at retaining nitrogen.
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Earthworms
have a very important role in counteracting 'the loss of
biodiversity'.
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Vermicompost has a high potential
value monetarily.
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Vermicomposting and vermiculture are
environmentally beneficial processes that have great potential as
components of sustainable agriculture.
