[Compostteas] Re: Safety and E coli
fteuton at sympatico.ca
Tue Jun 18 17:11:37 EDT 2002
----- Original Message -----
From: William F. Brinton
To: compostteas at lists.ibiblio.org
Sent: Monday, June 17, 2002 2:54 PM
Subject: [Compostteas] Re: Safety and E coli
>It is inaccurate to state that if compost tea is "aerobic" then >there is
>risk of E. coli or other potential pathogens for that matter. Once >you
>added sugars and molasses, etc. etc. the tea "regresses" to a >condition of
>like fresh manure/compost, with high BOD. This by the way is >one reason
for the new exclusion
>by the USDA-National Organic Program of such "re-fermented" >products.
>E. coli is facultative and therefore can grow under any >condition
>aerobic when lots of available sugars are present. The best >precaution is
>use proven matured composts that have gone thought a proper >and long
>process but are not so done as to contain little microbial activity.
I believe the claim is that where compost tea is made from proper compost
and vermicompost, kept properly aerated, and fed an appropriate amount of
growth nutrients, that the risk of E.coli growth is minimal.
In other words, aerobicity plus compost of high quality plus nutrients in
reasonable amounts, is the proposed formula for good quality compost tea.
Obviously, aerobicity and nutrient load are contingent factors, and
aerobicity for a five gallon bucket requires something less than aerobicity
in a 500 gallon tank or vat, that 'something' being forced aeration of some
I have asked for, and still have yet to receive, the precise conditions
under which substantial growth of E.coli in a nutrient load/aeration/compost
situation can occur.
Dr Ingham has given specific recipes for making compost tea which, according
to her, will not engender substantial risk of E. coli growth.
So, my question for you is, under what specific conditions have you and
other scientists observed growth of E. coli in 'compost tea' settings such
that you feel the benefits of amplified microorganism counts that can only
be obtained by nutrient addition are overcome by the risks of pathogens?
Is it not possible that, if good quality compost, proper aeration, and
non-excessive nutrients are used, that the risks of E. coli, etc, are not
substantial? Is it not possible that the argument to the contrary is based
on poor compost, inadequate aeration and/or excessive nutrients?
I am reminded of the adage about shredding and grinding equipment: any sort
of equipment can clog if its limits are exceeded. If it is possible for
compost tea makers (the people) to make good or bad compost tea depending on
our adherence to appropriate parameters, then it is incumbent on the
composting professionals who are guiding us to issue the necessary
On the issue of 'good compost' it seems the compost task force and Dr Ingham
are in agreement and the definitions you have given are completely
compatible. Whether or not 'good compost' was used in the E.coli growth
experiments you are relying on is another issue.
On the issue of 'aeration' I think there is a fair amount of fuzziness; I do
not know what aeration standards were used in the experiments you are
relying on, and the aeration provided in various commercial machines is not
openly documented anywhere, as far as I know. But clearly aeration levels
cited in one paper on this topic are highly suspect, and cast doubt on the
conclusions its authors reached.
Re the nutrient load, specific quantities have been given by Dr Ingham, and
I imagine, exceeding them would yield low aerobic or anaerobic conditions
more conducive to pathogen growth. Again there is contingency with the
aeration parameters, as higher aeration might make a higher nutrient load
acceptable while inadequate aeration might make even very low nutrient
loading unacceptable, no?
What were the nutrient levels used in the experiments you rely on for the
>Do not add any
>readily available sugars etc unless research has documented >that this is
>the particular host-infection situation.
Pragmatically speaking, the compost tea situation that is promising is the
ability to brew a culture of tea sufficient to treat multiple acres of crop
in a timely and effective manner. This seems to require the amplification of
the compost organisms via nutrient addition.
>An acquaintance of mine recently got a severe eye infection >from spraying
>tea and what the doctors wanted to know was: where did you >get so much
>once in the eye?
Well, now, that is interesting, do you know what the infecting bacterium or
bacteria were? Will the case be written up in occupational health or other
I am asking because I recently consulted an opthalmologist on this question,
and he was quite unconcerned about the risks involved.
>Please be careful and especially watch the "myth of aerobic" >that has
been propagated in the country.
The 'myth of aerobic' as I understand it is the claim that quality compost,
adequate aeration and suitable nutrient additions are not conducive to
pathogen growth, in a compost tea situation.
If that is wrong, I would like to know the details, please. Those of you who
are lettered scientists should be eager to provide us the particulars of the
science you use to form judgments that affect all of our lives.
General statements like your letter consists of, along with anecdotal
alarmist tales, ought not to be considered a sufficiently detailed manner to
critique a promising practice such as the aerobic nutrient added brewing of
There is, at least at this time, too much of a risk that the baby is being
thrown out with the bath water, and people such as myself who have seen
benefits from aerobic, nutrient added compost tea would very much like to
be sure that it is being restricted from organic growing based on sound
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