[compost_tea] Re: Searching for basic instructions on compost tea brewing

From: tomjasz <tom_at_livesoil.com>
Date: Wed, 17 Nov 2004 19:58:20 -0000

There's clearly some misinformation in this thread. We don't
have "years" of data. Most of us here support and believe aerobic
teas are likely, or the most likely to provide the extended and
consistent benefits. However we must consider that others methods
are, have been, and continue to be effective.

Please see compost tea notes form Steve Diver and ATTRA for a more
balanced approach.
http://www.attra.org/attra-pub/compost-tea-notes.html


More good stuff and an interesting design for a brewer;
http://whatcom.wsu.edu/ag/compost/pdfs/orf2.pdf



This link will take you to an interesting article as well;
http://www.ofrf.org/publications/Grant%
20reports/97.40.10.Merrill.Fall97.IB9.pdf

The following is also of interest!

"Compost extract preparation: Cattle compost from Greenleaf (Olds,
AB) and chicken manure compost from a poultry farm in Armstrong, BC
was  used for the extractions (see analysis in Results section). 
Both composts were actively turned for the first month  and  then 
only  once  a  month  for  the  next  3  months,  then  cured  for 
another  6  months.    A  method  of compost  extraction  proposed 
by  researchers  at  the  Wood's  Hole  Laboratory  was  used 
(Brinton,  1995).    This resulted in an 8:1 water to compost
dilution.  Water was added to the respective composts (cattle and
chicken) and the mixture was stirred for about 10 minutes every day
of the week long extraction period. Subsequently, the extract was
filtered through se  cbeesecloths, stored outside away from sunlight
until use on crops. "

Microbiological analyses of plant leaves after compost extract
application
Samples of broccoli and leek were sent away for microbiological
analysis.  No Salmonella was detected on any of these samples.  Total
and fecal coliforms were less than 3 MPN/g of broccoli and leek that
received cattle compost extract while total and fecal coliforms were
3 and 43 MPN/g for broccoli and leek tissue sprayed with chicken
compost extract, respectively.

Discussion of results The effects of compost extract application were
not consistent across all crops.  Yet, some trends did emerge. 
Extracts from cattle manure compost were effective in increasing
marketable number and weights of strawberries.  The same extract also
increased the weight of broccoli heads.  Lettuce and leeks did not
show any increased harvest weights or reduced disease incidence as a
result of cattle compost extract application.  Crops
that received applications of chicken compost extracts had lower
average harvest weights after diseased parts were removed, except for
lettuce.  It is possible that the chicken compost extract had some
microorganisms associated with it or metabolites thereof that may
have further contributed to disease progression or had some other
negative effect on plant growth.  It is also not clear why the cattle
compost extract would have had a similar effect to water spray,
unless after some storage time, the extract lost its 'potency' and
had attributes more similar to the water treatment.
Disease incidence in strawberries and broccoli did not vary
significantly among plots, yet compost
applications often resulted in a greater average percentage of
healthy crops compared to the control.  This seems to indicate that
there was some effect either related simply to the spraying of
something liquid or to something associated with the extracts. 
Lettuce and leeks, however, did not show any clear response to
compost extract application.  Possibly, if compost extracts are
effective as a result of an induced defense reaction of the plant as
suggested by Samerski and Weltzien (1988), lettuce and leeks may be
crops that are not readily induced in this way.  This study also
lends support to the idea that different crops respond different to
extracts from avariety of sources (e.g. lettuce did not react to
cattle extract as did the other crops). The dilution of extracts in
this study was 1:8 from the original compost; a recipe based on
various research literature (Brinton, 1995; Cronin et al, 1996).  It
is possible that this was too dilute for a consistent,
significant effect.  In fact, researchers have found that dilutions
of extracts can reduce disease inhibition
dramatically (Cronin et al., 1996; Elad and Shtienberg, 1994). 
Compost extract incubation time also appears to be a variable in
their effectiveness against disease.  Urban and Trankner (1993) found
that 24 hour extracts from horse and cattle manure composts
effectively controlled gray mold in beans.  Others, however, have
only found disease suppression after an extraction period ranging
from 7 to 14 days (Ketterer et al., 1992; Elad and Shtienberg,
1994).  Some researchers suggest that compost extracts lose their
efficacy if they are not used within about I week of preparation
(Brinton et al, 1996).  In this study, extracts were prepared in
larger batches,extracted over a I week period and were used up to 3
weeks after preparation.  It is possible that then that the mechanism
responsible for inhibiting disease was much reduced as the compost
extract 'aged'.  This phenomenon seems to coincide with increased
berry weights early on (when the extracts were freshly prepared) with
cattle compost extract application; this was not evident later on.
There appears to be some controversy about how the extracts are
prepared, anaerobically or aerobically.  Cronin and coworkers (1996),
for instance, found that anaerobically prepared extracts from spent
mushroom substrate were much more effective in inhibiting apple scab
than aerobically treated extracts.  Weltzien (1991) and Brinton
(1995) also promote the anaerobic method of compost extract
preparation.  These researchers suggest that the likely disease-
suppressive effect is a result of a metabolite produced by anaerobic
microorganisms
in the extract (Cronin et al., 1996).  In contrast, there is also
evidence that indicates that aerobically produced compost extracts
are much more effective (reviewed in Anonymous, 1996). 
Microbiological studies have also shown that aerobic microbes
dominate compost extracts (Sackenheim, 1993 in Hoitink et al.,
1997).  The method used in this experiment was largely anaerobic with
only occasional stirring during the extraction period.  If, indeed,
it is an aerobic microbial population that is responsible for disease
suppression, then the extracts in this study would have been
relatively ineffective. Given that this growing season was unusually
cool and wet, it is possible that populations of pathogens were
favoured and could easily outcompete any beneficial organisms
associated with the extracts.  High pathogen populations could also
be less  ted by inhibitory substances produced by organisms in the
extracts.

http://www.ofrf.org/publications/Grant%
20reports/99.31.10.Welke.Spr99.IB9.pdf









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Received on Wed Nov 17 2004 - 15:55:02 EST

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