Vermicomposting Comparisons
Vermicomposting and traditional composting
In traditional composting, the compost piles are mixed and aerated mechanically. With vermicomposting it is the earthworms that fragment, mix and help aerate the waste.
While vermicomposting and traditional composting both involve the aerobic decomposition of organic matter by micro-organisms, there are important differences in the way the two processes are carried out. The most notable is that whereas the temperature of composting piles can exceed 70 °C, vermicomposting is carried out at relatively low temperatures (under 25 °C).
It is vitally important to keep the temperature below 35 °C, otherwise the earthworms will be killed.
Many years experience of vermicomposting has shown that it can be a useful method of composting and one which is suited to a wide variety of wastes, but the process has both advantages and disadvantages compared with traditional composting.
Advantages and disadvantages of vermicomposting
One big advantage of using earthworms to compost waste is that the resulting compost often contains much more nitrogen and plant available nutrients than windrow compost. For this and other reasons, vermicompost has proven to be highly marketable.
Vermicomposts have are usually sold for three- to five-times the price for garden waste compost.
In addition to the excellent compost produced, vermicomposting can produce a net excess of earthworms and these may be harvested for a variety of purposes.
Many vermicomposting systems have been started or sold on the basis of the profits to be earned from selling the worms.
The primary disadvantage of vermiculture, is that it can take many months, or even years, to build up a large working population of earthworms capable of vermicomposting significant quantities of waste. As well as this, earthworms (sometimes in large numbers) tend to escape during damp weather conditions or when food is in short supply.
Maintaining constant illumination and sealing the surface of vermicomposting beds or containers helps minimise escape.
Windrow composting systems involve high operating temperatures and intense microbial activity, so that pathogens are destroyed.
As vermicomposting works at relatively low temperatures, it is less easy to destroy most pathogens at lower temperatures. Many practitioners of vermiculture therefore use windrowing as the first stage of compost production, adding worms only in the final stages before the compost material is sent to market.
Complete elimination of pathogens during the vermicomposting process is not normally thought possible. It is recommended that wastes known to contain human pathogens, such as sewage sludge, are either pre-composted at controlled high temperatures before vermicomposting. or else the resulting casts should be sanitised as an additioanl final stage, before sale or use of the compost.
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