Re: [compost_tea] Re: Simple is best

From: <soilfoodweb_at_aol.com>
Date: Sat, 18 Dec 2004 16:57:54 EST

I'm going back to discussion from the last couple weeks, because I have been
at ACRES. Someone wrote:

> Really finished compost is too low in microbial activity for tea purposes.
Absolute statements are scary, and this one scares me because it isn't
absolutely correct.

The reason we add food resources to tea is to improve activity of the
organisms extracted from the compost. So, you can take very mature compost, and
activate the organisms and get good, active tea.

Good compost - either worm or thermal - has food resources for the organisms
to remain active for at least 6 months after the compost has finished. After
that, foods do run out, and diversity starts to drop. After probably about 2
years as long as water and air are maintained, compost will lose diversity,
to the point that it is only as good as top soil.
Which is still darn good, actually. And these organisms can be re-woken up
and made active in the tea brewing process.

Again, the person wrote:
> So, indeed, a too low carbon to nitrogen ratio would indicate a
compost that is relatively spent for tea making. You want a younger compost
for teamaking, especially where bacterial activity is desired.

Elaine responds:
Low C:N could be a result of adding lots of manure, or alfalfa, and may be
indicative of a very hot, rapidly growing composting condition.

OR

low C:N could indicate a compost with lots of manure, but high in salt, where
the organisms can't decompose the material,

OR

low C:N could be the result of lots of recalcitrant, very immobilized N,
where bacteria have blown off lots of C.

So, C:N cannot always be used as the sole determinant of what's going on.

Person writes:
> As the compost matures, it will be lower in activity and more fungal in
character, and can be used to provide the fungal component to tea making.

Again, let me quibble a bit. Not really at odds here, just wanting to
clarify. IF fungal foods were used to a greater extent than bacterial foods, then
fungi will grow more than bacteria as compost matures. The bacteria use up the
simple sugars, proteins, etc, and so they go to sleep, while the fungi are
just getting started on the more complex, harder to use materials. So for
awhile, fungi are doing much better than bacteria, relatively speaking.

Once the fungi use up their relatively speaking easier to use fungal foods,
they too slow down. But they don't ever completely run out of food, so fungal
activity maintains much longer in compost than bacterial.

Elaine R. Ingham
Soil Foodweb Inc., Corvallis, Oregon
Soil Foodweb Inc., Port Jefferson, New York
Soil Foodweb Institute, Lismore Australia
Soil Foodweb Institute Cambridge, New Zealand
Laboratorios de Soil Foodweb, Culiacan, Mexico
Soil Foodweb Inc., Jerome, Idaho
Soil Foodweb Inc., South Africa







Received on Sat Dec 18 2004 - 20:54:06 EST

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