Re: Nitrate and Redox

> From: Stephen.Pushak at saudan_HAC.COM
> Subject: Nitrate, soil, Calcium and redox
> In reference to house plants and Fe, similar mechanisms occur
> but things are a lot more precarious and it's extremely important
> that the moisture in the soil is neither too much nor too little.
> Often, gardeners help the house plants along with the addition of
> chelated Fe in small concentration during watering. 

	Can aquatic plants really not cope with FeIII in the substrate?
The chelated iron we add is a _very_ tightly bound FeIII complex with
EDTA, and they use that, it seems.  Why can they not use FeIII in solid
material in the substrate, provided the roots can reach it?  _Must_ the
substrate go anoxic?

> Nitrate is held in the complex organic molecules and is released
> by the bacterial action of decomposition.

	_Nitrogen_ is held, and changed to nitrate by bacteria.

> > 	Could you please explain this?  "mediate?"
> Soils are often acidic by virtue of the organic acids. CaCO3 or lime
> will mediate the pH by bringing it to a more neutral pH, more favourable
> to the bacteria responsible for organic decay. 

	Your dictionary is a bit different from mine!     :)

> Reference: Drew & Lynch "Soil Anaerobiosis, Microorganisms, and 
> Root Function", Annual Review Phytopathology, 1980. 18:37-66

	I now have to think of an excuse for asking my librarian for
this one!!!!      ;)

Paul Sears        Ottawa, Canada

Finger ap626 at freenet_carleton.ca for PGP public key.