spanish broom and nitrogen fixing

I am investigating nitrogen fixing shrubs for my garden here in the south of Spain.
I read that Spanish Broom is nitrogen fixing which sounds too good to be true as it grows wild everywhere here with very little water and can be obtained for next to nothing.
Are there any reasons not to use it amongst my fruit trees here? I have never seen it used locally amongst the millions of olive trees, almond or cherry trees so I thought I had better check.
S

It looks like Spanish broom like most nitrogen-fixers, is extremely successful (read: it'll take over...)
These type of plants tend to seed like mad and the seed is viable for a very long time.
English broom is a noxious plant over here, and it forms really dense monocultures.
I assume it eventually dies out as it fixes enough nitrogen to make the soil too rich for it,
but all I see is it spreading everywhere.

Hi Steve, I was researching Spanish Broom as a nitrogen fixer as it grows everywhere here and I came across this old post of yours.  Did you use it amongst your fruit trees or olives in the end? What did you discover? Any helpful tips? Many thanks.