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Re: an(aerobic) substrates

>Date: Wed, 21 May 1997 13:46:22 +0800
>From: geoag at leonis_nus.sg (Anthony Greer)
>I know that this is moving away from the aquaria scale of things but if
>anyone is interested here it is...I work on freshwater swamp habitats in
>Southeast Asia and looking at soil cores from permanently flooded forest -
>it is possible to see a zone of oxidised Fe around the root hairs.  This
>sometimes amounts to large areas of aerobic substrate within a very
>unaerobic environment.  I have also  seen reference to some plants ie
>hyacinth being able to transfer oxygen to their root zones and rhizomes
>in this way create small pockets for aerobic degradation and
>I know this relates to quite specific environments but if this is of
>interest to anyone in the group I can dig up the reference.

I just read this and realized I've seen the same thing in one of my 30g
flats.  It has about 1 cm of water in it with tons of cyanobacteria in the
water.  Plants are amphibious, grown emerse (crypts, echinodorus,
hygrophila, alternathera, rotala).  The tank is experimental and I barely
pay any attention to it at all.

Occasionally I check on it and I like to look from underneath at the roots
that protrude through the substrate to the bottom of the tank.  The
substrate is vermiculite mixed with potting soil (peat, vermiculite, and a
little clay), with a teaspoon of micronized iron mixed in with it all.
Over this is a thin layer of Texblast.

When I plant, I just set the plants on top and let them attach.

The hygrophila roots have reached the bottom and spread out across the
tank.  The interesting part is that wherever a root traverses the bottom,
the area about 3mm on either side of the root is a different color and is
lighter.  I suspect that anaerobicity in the substrate prevents the iron
from oxidizing, but where the plant roots are, it's noticably reddish.

I guess that means that even an "anaerobic" substrate with plants isn't
really anaerobic.  :-)

David W. Webb           Corporate Business Systems
Texas Instruments Inc.  Dallas, TX USA
(972) 575-3443 (voice)  dwebb at ti_com
(972) 575-4853 (fax)    http://www.dallas.net/~dwebb
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