Make of this news item what you will.
"Are worm farms bad for the environment? Hamburg, DPA German
researchers have found that worm composting systems produce more
greenhouse gases than landfill sites.
So you thought you were doing your bit for the environment by setting up
a worm farm? Well think again. Worm composting could be doing the
environment more harm than good, according to German research. "Worms
produce a significant amount of greenhouse gases. Recent research done
by German scientists has found that worms produced a third of nitrous
oxide gases when used for composting," says Jim Frederickson, a senior
research fellow at Britain's Open Universities faculty of technology.
In an interview with a leading renewable resources journal, Frederickson
said the German research showed that worm composting has deleterious
effects on the environment that should be considered more seriously.
Worms naturally produce nitrous oxide gases when they are put into the
process of composting. Worms can be used for home grown composting or
commercial composting. Typically, the worms used are red worms. They
are used to recycle food scraps and other organic material into soil
worm compost known as vermicompost. This compost can be used to grow
plants. "We have concentrated on getting waste out of landfill and into
worm composting systems but they can actually produce more greenhouse
gases than landfill sites produce," Frederickson told Materials
Recycling Week, a leading publication for the recycling and waste
Many governments have supported composting waste in order to reduce
landfilling of biodegradable waste. This includes encouraging
householders to invest in home composting systems. Although
Frederickson says that worm composting is a positive thing, he claims
that not enough research has been done on worms releasing polluting
gases. "Everybody loves them because they think they can do no harm but
they contribute to global warming," he said. "People are looking into
alternative waste treatments but we have to make sure that we are not
jumping from the frying pan into the fire. "We need to investigate all
alternative systems for greenhouse potential. "The emissions that come
from these worms can actually be 290 times more potent than carbon
dioxide and 20 times more potent than methane. In all environmental
systems you get good points and bad points." This is because worms used
in composting emit nitrous oxide - a greenhouse gas 296 times more
powerful, molecule for molecule, than carbon dioxide. Landfill sites
produce methane which is 23 times more powerful a greenhouse gas than
Red worms appear naturally in country compost heaps but over the past
decade or so a thriving trade has grown up in domestic wormeries which
enable people with space as limited as a balcony to compost their
kitchen waste. Domestic wormeries are garbage bin-sized boxes
consisting of several trays, into which reared worms are introduced.
Some are even made to look like beehives, according to a report in The
Daily Telegraph of London which also cited the German research. The
worms are laid out on lime and vegetable peelings. When they have
digested this material they move to another level in search of more
food. The lower trays of compost can be used and a tap allows the liquid
collected to be drained off as fertiliser. The red worms used in
composting are extremely efficient at breaking down decomposing material
such as kitchen scraps and other organic material but they emit nitrous
oxide in the process of digestion.
Frederickson told Materials Recycling Week: "The amount of worm
composting is very, very small and the amount of landfill is huge. But
landfill sites are quite well run these days and it is possible to
extract about half the gas they generate and use it for electricity
generation. "So the amount of nitrous oxide emitted by large scale worm
composting is something we should be looking at before we go further
down that route." Frederickson said that the research he and his
colleagues had done was on very large commercial worm composting "beds"
which build up large amounts of nitrogen which is then emitted by the
worms as gas."
Geoff Read <g.read from niwa.co.nz>