Posted By: Frank Teuton <firstname.lastname@example.org>
Date: Saturday, 11 March 2000, at 8:43 a.m.
In Response To: Vermicomposters UNITE & take ACTION! (Dorothy Benoy)
A part of my attraction to worm composting was the realization, through
participation in composting discussion groups and through reading current
research literature, of the superiority of mesophilic composting for the
quality of the product.
The standards outlined in the NRSC # 317 Conservation Practice Standard are
neither necessary nor beneficial to the organic grower.
At most, what would be needed for the processing of problem feedstocks such
as animal mortalities and specific manures (eg swine) would be a brief
period of high temperature composting, as laid out in the EPAs 503
After such a PFRP is achieved, it is much better to reduce the temperature
of the composting mass to below 50 degrees Celsius (122 degree Fahrenheit),
as the temperature at which ordinary composting proceeds fastest is between
40 and 50 degrees C (104-122 F).
The ceiling proposed in the NRSC document, 170 degrees F, is well in excess
of any reasonable standard I am aware of. The EPA 503 standards state 158
degrees F as a pasteurization standard, after one half hour of such a high
temperature pathogen control is considered to be accomplished.
Discussing temperature ceilings for composting processes, Finstein and Hogan
write: "For most purposes a maximum temperature of 55 degrees C (131 F) in
the uppermost material seems currently indicated for maximum decomposition.
In routine large scale field practice it is feasible to maintain essentially
all the material below 60 degrees C." (140 degrees Fahrenheit).---The
Science and Engineering of Composting, Hoitink and Keener, eds, Renaissance
Press, 1993, ISBN 0-936645-15-6, pp 1-26
In other words, the latest research in composting indicates that compost
temperatures should be maintained at or below what the NRCS suggests as a
floor temperature level!
Cooler composting confers a number of benefits to the organic grower,
including enhanced disease suppression, more rapid decomposition, fewer
odors and less loss of nutrients.
It is also more likely to achieve destruction of pesticides and other
neo-chemical contaminants. According to Hoitink, the range of decomposers is
much wider in the mesophilic range of composting, and therefore as a general
priniciple this temperature range should be preferred by organic growers,
for whom freedom from neo-chemical contaminants is a vital issue.
Studies of thermophilically produced yardwastes in New Jersey, published in
Biocycle, August 1998, found that while most common pesticides were
destroyed, chlordane was not, and was found in each of 12 samples of New
Jersey compost tested, at levels as high as 3.23 ppm (mg/kg).
There is no provision in the new regulations for testing compost for such
contaminants. Mesophilic composting has been shown to be preferable for the
bioremediation (biological destruction) of chlordane and other contaminants
in composting. Private and public research has demonstrated this.
Some research has also indicated destruction of organochlorines in
Moreover, vermicomposting is entirely excluded by this rule. Vermicomposting
occurs completely within the mesophilic range of composting, and has been
shown to be a satisfactory method of destroying bacterial and other
pathogens. It is also able to generate a stable product as quickly as, or
more quickly than, other composting methods.
Finally, the standard enunciated contains no performance criteria. Since
organic growers are typically composting materials with low pathogenicity,
the need for the high temperatures given is not present.
But if organic growers were composting, let us say, pig manure, it should be
an acceptable standard to allow a mesophilic approach followed by batch
testing to demonstrate that bacterial, viral and helminthic pathogens were
adequately reduced, as in the EPAs 503 regulations.
Organic growers should not be constrained to use outdated, unjustified and
fundamentally unnatural thermophilic composting standards, which reduce
their compost quality, may cause odors, result in sterilized composts that
could become recontaminated with pathogens, and create other management
Instead, rational composting by modern scientific standards, should not only
be allowed, but encouraged for organic growers. Organic growing is not based
on thermal sterilization, but fundamentally on the intelligent use of
biological controls to solve problems. What destroys disease in natural
composting is not simply high heat but the competitive microflora...indeed,
the whole compost foodweb, which operates at its best in the cooler
temperature ranges of mesophilia, whether with or without macro-organisms
such as annelids in large numbers.
The new rules should be re-written to encourage intelligent composting by
organic growers, in keeping with the findings of modern compost science and
the knowledge that nature does the vast majority of her composting in the
Frank Teuton----(This is a draft of comments I will be submitting on Monday,
when the comment period opens....)
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