I don't think I'd ad ashes from a trash burn nor from wood that has had lighter fluid or gasoline, etc. added to it. 'Ive read that chickens can eat some of the unburned yet chared bits (it's healthy to absorb toxins) and you don't want them to eat everything else that was in the fire. Plus, didn't someone say something about ash and water (and probably something else) makes lye (think granny's homemade soap) and lye is caustic.
I've wanted to add to the dust baths ashes from fallen trees/stumps but we always seem to put some kind of accellerant on it and then I can't use it
CG
Use dryer lint saved up as a starter. I melt a tiny candle and dip the lint. Let dry. It will start your fires.
