Dear NOSB members and those interested in compost teas:
I have been informed in the last few days that the process of making
amplified aerobic microbial cultures starting with high quality compost,
aerated water and nutrients to create a high bacteria and fungal count
product useful in horticultural and agriculture has come under doubt, and
has been slated to be placed under 120 day restrictions similar to those for
raw manure.
The reason proposed for this is supposedly that, under certain conditions, a
nutrient solution will support growth of 'enteric pathogenic bacterial
organisms' such as E.coli and Salmonella spp.
I would very much like to see the specific details of the experiments which
underly the judgment reached by the National Organic Standards Board Compost
Task Force when it issued the following:
2. Compost and Vermicompost teas
The use of a liquid compost extract, or compost tea, raises special
issues. The
preparation and use of compost tea and compost extract has been increasing
in the
U.S. during recent years. Organic producers especially are interested in
compost teas
and extracts because the preparations reportedly provide some degree of
control of
foliar and root pathogenic organisms. Various methods and practices have
developed
for production of the teas or extracts since the practice originated some
years ago in
Europe. However, recent research at the USDA Agricultural Research Service's
labs in
Beltsville, MD and Corvallis, OR shows that certain approaches to compost
tea or
extract preparation are conducive to growth of enteric bacterial pathogenic
organisms,
such as enterotoxigenic E. coli and Salmonella. The practices and procedures
that lead
to pathogen growth in the prepared teas and extracts involve the addition of
supplemental nutrients such as sugars, molasses or other readily available
(soluble)
carbon sources during batch production.
The researchers did not observed growth of enteric pathogenic organisms when
compost tea or extract was prepared only with water and high quality
compost. By high
quality compost, they mean compost that has met criteria for destroying
pathogenic
organisms, i.e., 131ºF for 3 days, or compost that has less than 3 MPN
salmonella per 4
grams compost (dry weight) and less than 1000 MPN fecal coliforms. The
critical
determinant regarding pathogen growth in compost teas and extracts is the
addition of
the carbon sources like sugars, molasses, or yeast or malt extracts during
the brewing
phase.
Recommendation: Compost teas if used in contact with crops less than 120
days before
harvest must be made from high quality compost described above and not
prepared
with addition of supplemental nutrients such as sugars, molasses or other
readily
available (soluble) carbon sources.
http://www.ams.usda.gov/nop/CompostCMTTskFrceRec.pdf
This matter was brought to my attention in the pages of Dr. Elaine Ingham's
internet newsletter:
http://www.soilfoodweb.com/ezinearchives/may2002.html
I have been using compost tea for the last two years, using the
aerobic/nutrient added method. We are making extensive use of it in an apple
orchard, and I use it in landscaping, gardening and lawn care.
I have accepted as a working basis the judgment of Dr Ingham that good
compost, good aeration and appropriate amounts of nutrients would yield a
good quality tea that would offer benefits to plant growth and not pose a
significant risk to human health.
My results so far have given me no reason to doubt Dr. Ingham's judgment.
So, I find this recommendation of the NOSB's Compost Task Force needs closer
examination to see if in fact the experiments were properly done and
indicate a real problem, or if, as Dr Ingham asserts is likely, they were
poorly done and, used as the foundation for judgment, will result in the
unnecessary exclusion of a valuable biological technology for organic and
other growers.
So I would like to have a full, detailed account of the conditions under
which these experiments have been carried out. It strikes me as very
peculiar that Dr Ingham has not run into pathogen problems in the course of
working with hundreds of aerobic, nutrient added brewed compost teas, while
other researchers claim to find them. Something in the parameters of the
processes must be substantially different for such divergent results to
occur.
I feel it is crucial for the credibility of the organic movement to make
these kinds of scientific decisions as transparent and open to scrutiny as
possible. Replication of both positive and negative results and the use of
peer-reviewed publications would be very helpful in making clearer what
does, and what does not work in the use of microbial cultures, and thus what
should be allowed, restricted or excluded under an appropriate regulation
regime.
All comments and further information are welcome,
Frank L. Teuton III, BGS, JD
[EMAIL PROTECTED]
