destruct007

not a bad start, you should team up with an animator, to get a better final.

you don't "create it" it's already there you basically just add it to the particle. The particleSampleI nfoNode already has it listed so you can make the connection before, you even add it to the particle... just it won't do anything until you add it to the particle and write the expression/add a ramp

streak of brown, hah that sounds bad but you know what I mean like earth looking bits. So it;s like dirt and smoke mixing in parts.

looks really nice. Couple a things you might try (not that you asked ;)
Since you're not using color, set it to dynamic and add some blacks and light gray maybe a streak of brown.
Also I'd cache that with an OS of like 5 or even 10 on the first 3 frames, then regular settings for the rest. It'll fix that initial blast shape.