Date: Fri, 30 May 1997 10:28:47 -0700 From: Wim Leys <wim.leys@lin.vlaanderen.be> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg2124$foo@default> Subject: Re: CP roots
> I believe that the explanation may be a bit more complicated. For the Sarrs. I
> have plants that are many years old that regularly grow and sustain roots in
> the water trays. These trays are kept constantly filled with water, maybe 1
> and 1/2 inches in summer, and 1/2 inch or less in winter. And of course, the
> biggest forms of S. minor and S. psittacina are found in the Okee swamp,
> growing on sphagnum mats floating on water. Not only saturated, but almost
Oxigen can travel in water much more easily than in the rather compact
potting medium. I bet you will find much more oxigen in a water logged
Sphagnum mat than in a watter logged potting medium. This explains why
roots can grow out of the pots in the water, I think they will find much
more oxigen there than in the pot.
It seems my plants now grow in a comparable situation to yours, I only
keep the tables dry during winter.
> IMHO, the biggest issue is the breakdown of the potting medium that may be
> hastened by high water levels. In the wild, this breakdown simply does not
> occur in the same way it does in a small pot. An interesting question is
> whether small outdoor bogs suffer the same breakdown and collapse as do
> individual pots? I would hate the idea of "repotting" a bog of several cubic
> yards of rotton peat! HA
I thought the breakdown of potting medium is rather stopped by high
water levels. Of what I know, peat swamps originated because of high
(acidic) water levels. This prevented the bacteria to break down the
dead plant tissues.
In my outdoor bog, about 30 cm of peat is "gone" since I filled it.
Someone told me this is because the water level was not constantly high.
When air (oxigen) reaches the peat it gets decomposed.
> I am
> beginning to suspect a well-drained soil is better for root growth
> than one less so, as the potential for anoxia is less. Many cpers
> successfully use a 50/50 (volume) peat/sand mixture,
> and I'll bet the amount of sand could be increased with a positive
> effect on root growth, as long as there is adequate moisture. Perlite
> could also be added, to increase the "openness" of the soil, and thus
> increase the diffusion rate of oxygen. Conversely, the same size
> container filled with pure, fine-grained compacted peat and also set
> in 1 inch of water would be more likely to become anoxic and may
> result in root death.
That is exactly my point of vision
- pure peat : bad
- peat + sand + perlite (+ pine needles) : very good.
BTW Lately the CP digest arrives so late at evening that I can only read
and respond to them the other day (Bob Jewett can you do something about
this ?). So my responses will allways be one day off.
Kind regards
Wim
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