Re: [compost_tea] Re: NOP regulations

From: <soilfoodweb_at_aol.com>
Date: Sun, 10 Aug 2003 02:49:26 EDT

Hi all -

I can't talk about what is going on in the Compost Tea Task Force. Not
kosher to make statements as if there were decisions being made, when there aren't
any decisions being made yet. Hopefully there will be a recommendation soon.

So, if people can continue to agitate gently with their political
connections, it might help.

Based on my opinion, which has been modified by the discussions in the task
force, the major points that need to be in regulations are:

If the compost used to make tea is documented to be made according to
certification requirements (i.e., made according to regs, whether organic or USDA),

OR

if the compost is tested for human pathogens and found to contain fewer than
the acceptable levels as established by EPA or USDA standards,

THEN

compost tea made from those sources can be used without restriction.

So far so good. If you make sure your compost was made correctly, no
problem. with or without manure.

The CURRENT USDA - NOP regs are for compost tea MADE WITH MANURE-BASED
COMPOST, the 120 day rule applies. Tea made with compost that does not contain
manure can be used without restriction. If certifiers are making rules different
from that, they need to talk to Bob Pooler, of the USDA - NOP.

Again, if composted correctly, pathogens should be out-competed, consumed,
and reduced below levels of concern in the compost. The tea from such compost
can be used without restriction.

The USDA just finished a study - from Pat Milner's program - that showed that
compost that reached temperature for an adequate period of time resulted in
reduction to acceptable levels of the human pathogens. Problem is, the USDA
doesn't recognize that things other than temperature can be involved in
reduction in pathogens.

Why hasn't the USDA recognized this? Because there are more than one or two
factors that have to be determined to know that the habitat is not
appropriate for the growth of human pathogens.

My view - which not everyone agrees with - is that you have to have adequate
aeration, adequate microbial activity, and adequate protozoan numbers in order
to know for certain that the human pathogens, if present to begin with, have
been reduced.

We have some data to show that is the case, but we haven't tested all the
possible situations.

We have data to show that molasses does NOT "cause E. coli to grow" as has
been claimed by one other researcher. Don't pick on molasses as the only thing
that E.coli can utilize, human pathogens can grow using a number of different
sugars. But it has to be more than just that one factor that will allow E.
coli to grow. The other factors have to be correct for E. coli to grow.

So, lack of proper aeration and lack of the other competitive organisms that
outcompete and consume human pathogens. Aerobic organisms - in high diversity
and in high numbers - outcompete and consume human pathogens most readily.

OK, one more caveat - if the conditions in the brew are very anaerobic, human
pathogens are also not able to grow. But, very anaerobic brews will not
remain anaerobic. There will be a period of time when that anaerobic brew will be
back in range to allow human pathogen growth. Are the human pathogens then
able to reach high enough numbers to be a problem? Don't know. Need data. My
feeling is, let's not allow use of those anaerobic brews until until someone
does the necessary research to let us all know what's going on.

Now, a couple other things to think about -

When you start to deal with aeration, you have to pay attention to
temperature and air pressure because they determine maximum oxygen concentration in the
water.

You have to pay attention to microbial growth, because microbes use oxygen
and respire carbon dioxide. Microbial growth may drop oxygen low enough that
human pathogens can outcompete the aerobic microbes. When you deal with
microbial growth, you have to pay attention to temperature (microbial growth rate
increases with temperature typically) and amounts of foods added (more food,
more microbes).

So really, in order to assess the habitat and make sure it is not conducive
to human pathogen growth, you have to assess:

temperature
air pressure
oxygen concentration
microbial foods
bacteria, fungi
protozoa

Did I forget anything?

Temperature should be monitored hourly through the brew. How fast will the
organisms grow, and how much oxygen can the water hold?

Air pressure should be known at the beginning of the brew (temp and air
pressure will tell you the max oxygen possible in the brew. There may be times,
with compost that you know contains pathogens, where you will not be able to
brew, because the temperature is too high, and therefore oxygen concentration
will be too low at the start of the brew to select against the pathogens)

Oxygen concentration should be monitored throughout the brew. We have seen
5.5 to 6 ppm to be the "cut-off" when dealing with typical aerobic microbe to
facultative anaerobic microbe growth conditions. Valid in all situations?
What is you have a fermentative lactic-acid bacteria community of organisms?

Microbial foods should be added relative to the set of microbes in the
compost, which will determine the growth achieved during the brew cycle, given that
oxygen concentration that can be maintained by the machine through the brewing
cycle. This is information machine manufacturers should determine, and which
all the tea machines manufacturers of AACT have performed. They haven't all
put their data on their websites. The machine makers that don't have data on
their websites are the ones whose machines can't achieve the microbial growth
to prevent pathogens from growing. The people showing their data are the ones
doing the work to make sure their machines CAN maintain aeration, microbial
growth, and suppress human pathogens.

The set of microbes, including protozoa, in the compost and thus the tea
should be known. Plate counts are not appropriate for assessing bacteria or fungi
in any environmental material since viability is not what is needed, but
activity and total biomass. As methods are developed, molecular methods must be
used to assess species composition.

Typically production methods for commercial composting should be such that
each batch of compost produces the same set of microbes, within certain ranges.
There may be variation based on starting materials and initial chemical
content, but these can be determined, and the variation in microbial content known
as seasons change.

The research that needs to be done is on composts that are of questionable
microbial content, where some level of significant human pathogen contamination
is left. We need research to assess what precisely is the habitat that allow
human pathogens to be reduced in number and activity, and what habitat allows
human pathogens to grow.

I've outlined the information needed for research to do the job of figuring
out what conditions select against human pathogens. If people want to do
bacterial or fungal plate counts so they can prove to themselves just how pointless
it is to do those determinations in order to assess the response of microbes
in compost or compost tea, fine.

The best approach we have for assessing human pathogens is E. coli plate
counts or broth MPNs. That use of plate count methods is appropriate. We know
the conditions that allow E. coli to grow in lab cultures. But don't mistake
those special conditions as being reflective of what happens in real world
conditions. Stop imagining that lab cultures represent real world situations.

So, that's where I think we're at, without being in any way specific about
what's being said or done in the CTTF.

Any questions, or places my logic is not clear, please discuss with me.

I am putting a summary of the regs for different state's irrigation water on
the SFI website. If conventional growers can water crops with those levels of
E. coli - and therefore potentially human pathogens - then higher standards
should not be imposed on organic growers. The summary is based on information
sent out by Pat Milner of the USDA.

Elaine Ingham
President, Soil Foodweb Inc.
www.soilfoodweb.com
SFI Oregon, USA
SFI Australia
SFI New York
SFI Europe
SFI New Zealand

"Hope is not a feeling. It is not the belief that things will turn out well,
but the conviction that what we are doing makes sense, no matter how things
turn out." -- Vaclav Havel, former President of the Czech Republic





Received on Sun Aug 10 2003 - 04:11:22 EDT

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