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Re: Bacteria, algae, and N:P

Thomas's remarks during the "Plant Node" thread concerning nitrogen ratios
sparked a couple of "links" to another set of similar ratios kicking about
in the back of my mind. So I sat down to start charting parallels between
aquatic plant growth and the classic "Carbon- Nitrogen Cycle" in terrestrial
growth. Alas, I am too slow a writer, for in the meantime, up crops

From: Thomas Barr
Date: Wed, 10 Jan 2001 21:26:38 -0800
(pulled from the archives - hint, hint)

> I found compelling evidence for not letting your N:P ratio
> fall below 16:1 for aquatic plants. Neat stuff. So if you
> have a NO3 of 5ppm your P would/should not fall below
> 0.3ppm or so. The optimum seemed to be about 10:1
> or so of the studies I looked at...

Hmm... "beaten to the punch", so to speak. But I _can_ lend a hand, as this
is an area I'd hoped to introduce anyway and have a couple of references
already to hand.

> I want to find out how far this ratio can go. What is the
> upper limit with a set of CO2 levels/light values and
> excess Fe, K+ and trace elements without algae build
> up?

Haven't gotten as far as comparing CO2 to PO4 yet, but in that light I've a
paper that helps fix carbon:nitrogen ratios. Should be able to draw the
appropriate conclusions by extension: Myers J. 1971, 1980 "Enhancement
studies on photosynthesis" Ann Rev Pl. Ph.

In addition to the question of N:P ratios vs. compound types, you must also
consider the price the plant pays in CO2 reduction capabilities for the
reduction of nitrates to ammoniums. Again - quite handily - this paper
discusses that topic also...


David A. Youngker
nestor10 at mindspring_com