permaculture

[Keith Johnson <keithdj@mindspring.com>]

To quote from an article on Soil Fertility, by Lea Harrison, in the 
Permaculture
Activist (#26, May 92):
"Micro-organisms are extremely numerous in healthy soil; eg. one gram of 
healthy
topsoil contains about 1,000 million bacteria. All the micro-organisms that 
break down
organic matter, are aerobic organisms. That is, they can only function in the 
presence
of oxygen. All plant pathogens, which cause plant diseases, are also aerobic 
organisms.
Even in well aerated soils, aerobic organisms use up oxygen faster than it 
diffuses
into the soil. This creates, at any tiime, many microsites without oxygen, 
all through
the soil. Anaerobic bacteria, which function in the absence of oxygen, grow 
and
multiply at these reduced microsites. They produce ethylene, which 
inactivates, but
doesn't kill, aerobic micro-organisms. There is a complex rocking backwards 
and
forwards between the functioning of aerobic and anerobic bacteria, all the 
time, at
microsites scattered all through the soil."

In brief, the ethylene is the cycling back and forth in soils between aerobic 
and
anaerobic conditions. Under both conditions nutrients are rendered available 
which
would not otherwise be so. Both parts are essential for healthy balanced soil.

Keith Johnson



"Lawrence F. London, Jr." wrote:

> Still interested in a definition of ethylene cycles.
>
>
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