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Written by Administrator
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Sunday, 11 September 2005 |
by Susannah Tymms, from our issue #13
Here in Melbourne, Australia, issues of waste management and recycling
have become a major priority area for industry. Recent legislation has
been passed to reduce the amount of waste going to landfill by 50% by
the year 2000, and to ban all green organic waste from landfill sites
by 1998. The increased interest in diverting organic wastes from
landfill has raised concerns about the need to ensure that the end
products are safe to use and meet minimum quality standards. One such
concern is that strategies are adopted that minimise the risk of
spreading pests, plant diseases (pathogens) and weeds in recycling
organic wastes.
Municipal landfills, councils and private operators are presently
recycling organic wastes directly onto municipal parks and gardens,
foreshore reserves or selling the material to home gardeners or
composting companies. At present landfill operators do not have the
knowledge to screen incoming wastes and unknowingly may be allowing
pests, weeds and plant pathogens (fungi, bacteria and viruses) into the
recycling processes.
At the Institute for Horticultural Development, Dr. Kevin Wilkinson and
Susannah Tymms are conducting a three-year project to investigate the
risk of spreading pests, plant pathogens and weeds through recycled
organic wastes (composts, mulches and vermicomposts). The project has
begun with an extensive monitoring program at six organic waste sites
around the city to record plant species entering the processes, collect
and identify samples of plant diseases, and predict diseases likely to
occur. Five of the sites are collecting yard waste and one is
collecting market waste. There are significant amounts of weeds in the
yard wastes and a very high percentage of the market waste is diseased.
In order to establish the survival or elimination of these organisms
through the recycling processes, inoculation trials with known pests,
weeds and pathogens are being conducted. For composting and mulching
processes this involves placing diseases and weeds into the heaps for
the duration of the processes and assessing survival of the organisms
at certain points along the way and at the end. For the vermicomposting
process, worms are fed diseased feedstock and weed seeds of different
sizes, and survival of these organisms are assessed at intervals during
and at the end of the process.
It is our hypothesis that composting, which involves heat, oxygen and a
regular turning regime, will be the only guarenteed method of pest,
weed and disease elimination. In the case of vermicomposting, various
bench-top preliminary trials suggest that worms will ignore seeds and
certain large fungal structures in the presence of other food, and thus
these problems may remain in the castings . This will be more
thoroughly investigated during the next few months, as will be the
potential of worm castings to suppress plant diseases. Very little
research has been carried out in this area, and we aim to rectify the
situation, and abolish any myths! |
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Last Updated ( Sunday, 18 September 2005 )
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