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[compost_tea] Re: Weed Control and Compost Tea
Hi Elaine -
Nitrates exist in manures and immature composts,
and nitrates decrease as compost matures since the
nitrates become tied into larger structures
and compounds. So nitrates are probably involved
as weed signalers as well.
Yet I want to emphasize the terminology of
raw humic substances vs humified compost.
Poultry litter is a combination of raw poultry
manure mixed in with bedding. Bedding may
consist of sawdust, shredded wood, shredded
newsprint, or seeds hulls. So the chicken
"manure" has been in contact with organic matter
and moisture for some time. Raw humic substances
form under these conditions.
I use the term raw humic substances on purpose.
There are probably hundreds or thousands of
compounds in raw humic substances. Likewise,
there are probably hundreds or thousands of compounds
in humified compost, if not more, yet they will be
quite different than those in raw humic substances
since the compost has undergone transformation and
humification. Since I do not know which compound, or
complex combination of compounds, are functioning
as ecosystem signalers to weed seeds... then it is
best to leave it broad.
The broad terminology is also part of the
deep humus educational concept.
Signals between humified compost to soil
ecosystems and rhizospheres and mycorrhizae
fall into the deep humus concept. Controlling
weeds with humified compost vs raw litter is
pretty deep as far as agroecology. This observation
and the field plots designed to understand this
common farmer observation (weeds decrease over time
under organic farming and humus management) comes
from the organic farming experience, it is not an
item you will find in journal articles. There are
other examples that fall into the deep humus category.
Hoitink showed that compost in contact with root
systems turn on biochemical signals within the plant
to suppress pathogens attacking the plant 3 feet high
up above on the foliage. That's pretty deep, so
that goes in the deep humus basket. And so on.
This is a term so find what fits and add another
dimension to broaden the concept. Compost Teas are
certainly part of the Deep Humus story.
Steve Diver
--- In compost_tea@yahoogroups.com, soilfoodweb@a... wrote:
> What is needed is an understanding of the form of N in poultry
manure.
>
> Most weeds require high nitrate levels in order to germinate
rapidly. That
> is likely the signal that tells them to jump on up.
>
> Fresh, raw poultry manure is HIGH in nitrate. Therefore, weeds are
selected.
>
> There aren't many raw humic substances in manure. Chicken
digestive
systems
> are the wrong environment to allow humic substances to develop.
Nitrate, on
> the other hand, is normally quite high in manures.
>
> When you compost manure, the nitrates are taken up by the bacteria
and fungi
> and immobilized in organism biomass. thus, there may be the same
amount of N
> present, but in a very different, not-leachable form. A form that
weeds
> cannot access, and therefore does not help weeds grow.
>
> 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
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