-----Original Message-----
From: owner-extropians@extropy.com
[mailto:owner-extropians@extropy.com]On Behalf Of Michael S. Lorrey
Sent: Sunday, May 28, 2000 11:40 PM
To: extropians@extropy.com
Subject: Re: Growing plants in space
<There are plants which grow in desert sand, and plants which grow on
pure rock. Many plants depend upon heavily organic soil... Such references
refer to the use of organic (i.e. carbon
chemistry) compounds dissolved in water.>
Could you specify some plants which depend on organic compounds dissolved in
water? It's my understanding that plants get all the carbon they need from
the air. The models of photosynthesis I've seen all show the carbon used
during the process coming from carbon dioxide. My observations in growing
plants bear this out. Plants don't need organic compounds in order to grow,
as long as they can get the elements they need from some other source (by
elements I mean C,O,H,N,P,K,Fe,Cu,Zn, etc.) If you want to keep growing the
plants indefinitely without adding additional elements, you have to recycle
the by-products of their metabolism when they're alive and their bodies
after they die. This is where organic compounds enter the cycle.
Bonnie
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