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[Annelida] Gas from worm farms

Geoff Read via annelida%40net.bio.net (by g.read from niwa.co.nz)
Wed Jul 18 22:08:59 EST 2007

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 
management industry.

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 
carbon dioxide.

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>

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