Here's another link with more information
Well, I'm sure that like most other rock dust/greensand/azomite, Portable Farm's special secret formula is also full of trace elements...but I didn't break my back washing and rinsing all that media to get the dust out, only to put it (dust and fines) back in again .
Personally, I get all the trace elements I need from either sea salt (no N) or humonia (with N)...and both are soluble (and free).
'Bloomin' plants certainly can benefit from a K boost come bloom/fruiting time, but a K based pH buffer (like potassium bicarbonate or potassium hydroxide...the later once again being totally free, and made from nothing more than some wood ashes and rainwater) seems to take care of things just fine.
I like the way she say's "chemicals" at the 30 second mark.