"Kay Easton" wrote in message
...
In article , Franz Heymann notfranz.
writes


There are very, very few plants (if any?) which can utilise atmospheric
nitrogen directly.

Isn't that basically what nitrogen fixation (as in legumes and some
other plants) is about?

It is because I was aware of the fact that legumes and some grasses lived in
synmbiosis with nitrogen-fixing bacteria that I used the words "very, very
few".
{:-((
But that is only one (and probably not the major) mechanism by which
nitrogen fixing occurs.
Ultraviolet light in the upper atmosphere, lightning and free-living soil
organisms are, as far as I know, the major "fixers".
I admit to not knowing which of these process is responsible for what
fraction of the nitrogen harvested from the atmosphere

Franz