[compost_tea] Re: Mostly aeration... Some snails

From: Kirk Leonard <kirk_at_oregonatural.com>
Date: Mon, 17 May 2004 18:15:48 -0700
For new folks here, Mike Harvey and Scott Alexander are very well informed
makers and users of compost teas.  I appreciate a reply from Mike, and TED,
even!:-)

> Date: Mon, 17 May 2004 14:54:28 +0800
> From: "Mike Harvey" <mharvey_at_westnet.com.au>
> Subject: Re: Several Subjects (Sorry Jeff & Doc...) Mostly aeration...

> You said.
> > Micro-bubblers are sewer plant tank aerators that are not suitable for
compost tea because they inject air in too small bubbles, apparently.  They
can keep DO up dramatically but are destructive of organisms in suspension.
I think they are disc-shaped. < <

> Not all disc shaped diffusers are micro bubble size - they can range from
large to medium to micro. <
Agree.  Discs that are easily cleanable and have big enough bubbles can be
good tea aerators.  Discs are also made with the slitted rubbery membrane
stuff used in diffusion tubes.  Didn't mean to imply all discs are
micro-bubblers.  They're not.

> The problems with bubble size as I understood it related to varying bubble
size leading to different rates of ascent in the bubble, this then resulted
in shearing of the fungal hyphae. So as I understand it a consistent bubble
size is important. <
I don't know about ascent rates.  My impression is that micro bubblers can
be adjusted for that via flow or pressure control, but maybe tiny bubbles
inevitably rise too fast?  And yes, the shearing of fungi is the main
concern.  Doc E has said (I'm looking around a corner here wishing not to be
seen as part of a cult...:) that 20 micrometer bubbles can shear fungi, and
I think she said 1mm was a good minimum bubble size.  I believe she observed
that with equipment I don't have, so my data is limited...

I disagree on "consistent bubble size."  My understanding is that too-small
bubbles can whack organisms (at high velocity I can even imagine bacteria
being bashed) but I think a mix of larger bubbles is ok.  If the water and
critters need more air I think they'll grab it if it's there, whatever
bubble size.

> Ultra small bubbles are not good so we are told (based on
research). However it must be realised that bubble size is critical to
transfer of the oxgen into the water, smaller bubble size means huge
increases in Oxygen transfer rate. This is one of the reasons why how much
air for  compost tea ends up with the reply- it depends. <
Interesting insight.  If you accept that a variety of bubble sizes is ok and
want to use air power for extraction, bigger bubbles need more air supply
too, eh?

I like Ted's suggestion of adding more pumps as needed.  Been
vocal about that before, too. "SMOP" - simple matter of plumbing?  Though
good air pumps are not cheap (yet), several pumps variously connected can
support a broad range of compost and nutrient and tea-growing conditions.
Four scenarios occur to me.

Extraction -- good to have a robust pump pushing at compost first some
hours.  Growth -- good to have a base air capacity to accommodate compost
and nutrient load. Maintain -- good to be able to stabilize DO before/during
use.  And Emergencies -- good to be able to add air when your DO drops too
much (assuming you also have a DO meter...) Could be only two pumps, used
well.

But Ted, I think your snail experiment is flawed.  Folks who've seen slug
reduction haven't done that in such well-tended containers.  I think you're
more interested in eating snails than killing them:).  Being French way
back, I love escargot, too.  (sauteed in a simple garlic oil)

I'd also point out that snails and slugs are distinctly different if related
critters.  No snails I've found in Oregon like California's.

I've lived and gardened near where you live and noticed snails there I
haven't seen elsewhere in US.  Often I thought someone should be
cultivating them ( I believe that happens already) and by golly you may have
found a new way to do that!  Some snail food and compost tea and voila! -- a
new way of making delicious organic escargot?  Could be good bucks.  Good
job, guy, whether or not you intended that.

Point I think you may be missing is slug repulsion with tea likely has more
to do with existing soil and climate conditions and what critters the tea is
feeding than what's in the tea itself.  I would be real surprised if ACT
killed anything.

Anyone figured out good recipes for slugs?

-- Kirk

On another thing Doc E said recently, neither the CTTF report nor anything
USDA has done actually shows there is any danger with compost tea.  They've
shown there is the possiblity of pathogen growth in labs, but not any
field-tested, real danger, hmm?  I really think nature handles this stuff
well and we just need to pay attention. COMPOST TEA IS NOT DANGEROUS.




















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Received on Mon May 17 2004 - 22:04:20 EDT

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