Nitrogen Study Could 'Rock' A Plant's World
by Richard Harris
http://www.npr.org/2011/09/06/140206913 ... k-nitrogen

Well now ,this is interesting.
Here's a tease, so you'll want to raed the entire article...

Conventional wisdom believes nitrogen for plants starts in the air and is converted by microbes in the soil into a usable form. But a report in the journal Nature finds that some nitrogen comes directly from rock. This discovery has implications for global warming.