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 Worm Composting (Vermiculture)
Earthworms are nature’s
unique recycling machinery and provide a good way of
dealing with household fruit and vegetable scraps. They thrive on organic
matter and their presence indicates a healthy soil environment as organic
matter is passed through their digestive system producing worm castings
or vermicompost (100% organic fertilizer). The castings contain nitrogen
and phosphorus, which are excellent for plant growth. It also improves
soil structure and drainage and is suitable for potted plants, lawns and
gardens. The art of using earthworms to recycle food scraps and other
organic materials into a valuable soil amendment is called vermicomposting
or worm composting. Ordinary garden earthworms do not do well in wormeries,
because of the high concentration of organic matter. Instead special earthworms
called compost worms are used as they can tolerate the rich nutrient conditions
of the wormery. Common compost worms have exotic names like, Tiger Worms,
Red Wrigglers and Indian Blues. They savour fruit and vegetable scraps
and can also handle paper and cardboard
if prepared and introduced correctly.Vermiculture is simple and can be
done conveniently indoors or outdoors, all year round requiring little
effort and a small area. Worms are ideal for people living in flats or
houses with small backyards.
How can I start
a wormery?
Getting started is easy.
You can buy a ready made stackable wormery together
with worms from a supplier. You can find a list of suppliers under Worm Farms
in the Yellow Pages. Some Local Councils also sell wormeries to their residents.
If you prefer to make one yourself, boxes made from wood, styrofoam or other plastic
material are ideal. Wood is better as it is more absorbent and provides better
insulation for the worms. Even a simple hole in the ground will do. Metal containers
should be avoided as copper and zinc may concentrate in the finished vermicompost
. A 60 x 90 cm box with a depth of 30 cm is sufficient to compost food scraps for
a family of four people. Clean the box and punch small 1 cm holes all over the
sides and bottom for ventilation and drainage. Line the box with several sheets
of newspapers and half fill it with well-rotted moist compost. Alternatively, tear
newspapers or cardboard into strips and soak in water and let drain. Fill 1/3 of
the box with this shredded paper bedding and mix in soil to provide grit for the
worm’s digestive system. Other materials suitable for bedding are shredded
dead leaves, straw, sawdust and peat moss. Bedding made up of various materials
provide more nutrients for the worms and result in a better end product. You will
require about 1000 worms. Cover the top with a sheet of hessian, or several pieces
of newspaper to keep the environment moist and light out. Close with a tight fitting
lid to keep pests and rain water away. Water well to keep moist but
not soggy. Raise the box on bricks or wooden blocks and place a tray beneath to
capture excess liquid which can be used as liquid plant fertilizer. Start with
a small amount of fruit and vegetable scraps in the first week, about 500 grams
to begin with. Gradually increase the amount weekly as the worms begin to multiply.
Every few days add water if necessary to keep the hessian damp, and the wormery
moist. The worms will die if it becomes dry. After about six months, you will probably
have 8000 worms, which can devour up to 4 kilograms of food scraps a week. You
will need to remove some worms or start another box. Carefully transfer out the
top half of the contents into a second box which has been half filled with fresh
moist compost or moist paper bedding. Most of the worms are found in the top half.
What is left behind in the bottom half is mainly worm castings or vermicompost,
which is excellent for flower pots, garden beds and lawns. To separate and retrieve
the worms left in the castings, spread it out thinly in mild sunlight leaving a
few small mounds. The worms will migrate into these mounds to escape from light
and dryness. Sieving the vermicompost or picking them up with a fork will also
save the worms.
What
can I put in my wormery?
There are different opinions on what sort of materials can go into the wormery.
It is generally accepted that non-biodegradable materials like plastic bags, bottle caps,
rubber bands, sponges, aluminium foil and glass are to be avoided. Meat, bones and manure
have been vermicomposted successfully by some enthusiasts, but require caution, as they
can be problematic. Meat attracts vermin like rats and produces offensive odours as it
putrefies. Animal manure may harbour harmful pathogens. Highly acidic foods such as citrus
and onion peels are also not recommended as the acids can kill the worms.
Worm worked wastes, marketed as vermi-compost, have been shown to be suitable
as a soil conditioner. The concentrated organic matter can improve soil structure with
many of the essential nutrients readily available, vermi-compost is claimed to produce
spectacular increases in plant growth. It can be spread on the surface, under plants,
but should be covered with a straw or leaf mulch. Or it can be watered in well around
roots, or mixed with the soil when plotting or planting
Wormery
tips
Compost worms prefer a damp and dark
environment. The wormery bedding should be as moist as
a well-wrung sponge. The temperature should never be lower than 4ºC and never
above 27ºC. Keep wormery in a shaded and sheltered place. Remove the worm castings
or vermicompost as soon as possible when both bedding and food scraps are fully composted.
The worms will die in their own castings. Castings can be recognised as tiny dark brown
droppings with a sweet, rich earthy smell. After composting for about four to six months,
the wormery may become over crowded with worms as they can reproduce quickly. Remove
excess worms by giving them away to friends, releasing them in your garden or compost
bin or use as fish bait. Store food scraps in sealed containers to keep flies
or pests away. Refrigerate if necessary. When your wormery becomes established, you
will find that other small creatures appear and form part of the recycling community.
This is natural and they assist in the break down of organic matter. At the moment,
South Australia is lucky to not have fruit flies. However, if you are reading this
overseas or interstate, take note fruit flies may be an occasional problem but they
are not dangerous. Burying the fruit scraps under the bedding can help. A simple flytrap
can also be effective. Ants may also pose a minor problem at times. They can be discouraged
simply be spreading some talcum powder around the base of the wormery.
I’ve
got some problems in my wormery. What can I do?
Worms
dying or trying to escape
Problem Too wet - Too
dry - Not enough food - Bedding
is used up
Solutions
Add more bedding - Moisten bedding until
damp - Bury food into bedding - Remove
castings and add fresh bedding
Bin
smells rotten
Problem Not enough air
- Too much food - Non-compostables present
Solutions
Leave lid open or add more ventilation
holes - Stop feeding for a week or two - Remove
meats or fats
Did
you know?
Earthworms are hermaphrodites, which
means that every individual has both male and female sexual
organs. Although every worm can have babies, they still need to find a partner in order
to mate or reproduce. Under favourable conditions, the worms breed every 7-10 days
and can double their population every 90 days. If the wormery is over populated, the
worms stop breeding.
They have a healthy appetite and can eat between one quarter to half their
body weight in food a day. If there is insufficient food they shrink. They do not have
a solid skeleton like other creatures. Their bodies are made up almost entirely of water
(more than 90%), and their form and shape is maintained by what is termed a hydrostatic
skeleton. Although they do not have eyes and prefer darkness, they can still sense bright
light at the front end and will shun away from it.
Earthworms breathe through their skins. For the exchange or diffusion of
oxygen and carbon dioxide between the worm body and the atmosphere, the skin of the worm
has to be moist. However, if the wormery is flooded the worms will drown. There are
over 3000 species of earthworms in the world and some can live as long as 15 years. Australia
has 350 species. On dying they quickly decompose and are recycled by other worms along
with the food scraps.
Worm castings are toxic to the live worms themselves. When all food scraps
are eaten, the worms will eat the castings and be poisoned. Earthworms possess amazing
regeneration or healing power. When cut into halves, the head portion will live and regenerate
or grow a new tail, but the tail end will not survive. Cutting the worm up into many small
pieces or segments will not produce more worms, but will probably kill the head portion
as well if it loses too many vital organs. In nature not only do earthworms enrich the
soil by recycling organic matter; they are also great soil tillers. They mix layers of
soil and their tunnels allow air and water to reach
plant roots.
References
Appelhof M, 1982, Worms eat my garbage,
Flower Press, Kalamazoo Michigan USA.
CSIRO Division of Soils, 1992, Earthworms
for Gardeners and Fishermen.
Fauser All States Worms Pty Ltd, 1992,
Worms, Worms, Worms, Fact Sheet. Organic
gardening, Earthworms,
www.powerup.com.au/"dheaton/Earth%20worms.htm
Recycle 2000 Fact Sheets.
Worm composting, www.cle.cornell.edu/compost/worms/basics.html
Worm composting, www.gould.rdu.au/compost/wormery.htm
Worm composting, www.metrotor.on.ca/works/what/compost/wormway.htm
Worm composting, www.tnrcc.state.tx.us/admin/topdoc/gi/219
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