Nitrogen-fixing Bacteria

I recently had a conversation with the Google crowd about how legumes are "nitrogen-fixing". A bacteria grows on their roots in a symbotic relationship, and it converts nitrogen (N2) into a form that plants can actually use (nitrate, N03-). (http://en.wikipedia.org/wiki/Nitrogen_fixation)

I had read that the bacteria forms small pink nodules on peas. Last year, I tried to find them, and couldn't, so I assumed they were rather small.

Imagine my surprise when I pulled up my peas this year.
Not exactly small. The largest are about the size of a nickel. I also wouldn't really describe them as "pink", more like a buff color.

Coolness. Chemistry in the backyard. No need to fertilize this garden.

Funny enough, this is why, back in the day, clover was a good thing to have in a lawn. You wanted clover in lawn, so that way it would add in nitrogen. Clover was even standard in lawn seed mixes.

Then the idea of fertilizer came up. How do you get people to buy fertilizer? Well, you do some awesome marketing to convince people that clover is bad. You convince them that a good, healthy lawn has only grass. Clover is a weed. How do you get a lawn like that? Buy our expensive fertilizer! Of course, since only the rich can afford this, we now associate lush, grass-only lawns with wealth. Which means everyone wants one. Fantastic.

I claim that my clover-spotted lawn is vintage, thank you very much.