PH question

I have looked through some of the forums manually not finding my answer. I know it is out there, I just can't find it. The search is working like a red headed step child. I see ph in the title of a forum and when I search ph it finds no threads . So, the answer I need is.

What is the natural method, like lime? to lower the ph in my soil. It's sitting at 7-7.3 amongst all my plants, I'd like to keep it a little under 7, what's the best method to lower the ph safely??

Thanks

 

K, thx