Re: [compost_tea] detrimentals not beneficials

From: <soilfoodweb_at_aol.com>
Date: Thu, 28 Oct 2004 23:01:38 EDT

Hi Butch -

No one will, or should, claim compost tea as an herbicide. We have not
defined the conditions which will result in the tea containing compounds that could
kill plants.

However, if you brew compost tea that you purposefully make anaerobic, we
know that SOMETIMES, materials will be produced that can, and do, kill plants.
I've done it a few times when we were first playing with compost tea. Rather
disconcerting.

However, it is hard to control all the factors that need to be controlled to
make an herbicide brew, consistently.

So, I prefer to use simpler approaches, such as adding so much carbon to the
soil that the bacteria and fungi grow rapidly, take up all the excess nitrate,
which is what weed species require to germinate and out-compete the more
desired crop or grass species. Much more reliable.

The key is excess carbon, AND the organisms to use that carbon. The carbon
can be molasses, for example, orange oil, as another choice, or lots of woody
material, with just a touch of high nitrogen contaiing material to get the
bacteria and fungi going. All of these can do a good job of killing plants you
don't want, and enhancing the plants you do want.

Be careful though - too much of any of these, and you can kill all the
plants. We've done that too, and actually a graduate student of Mark Wilson's
published that information some years ago as part of a study on conditions that
allow native plants to grow.

Best way to approach this is to test the proper concentration of molasses or
other high carbon materials by adding to plots at higher and higher
concentrations. The concentration that kills the weed without killing the crop plants
is the one you want to apply over a larger area.

OK?

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 Fri Oct 29 2004 - 00:37:23 EDT

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