Lot of the stuff floating out there about growing isn't tested scientifically, not saying it isn't true, but you can't always believe everything you hear to be fact.
"quora How-do-ashes-get-their-colour"
Hey I am to new to post links but there's good data at this site ^^ if you Google it.
Saw this science article on ash colour. He explains the black white grey ash as caused by refraction of the base chemicals and metal salts.
Black ash is refracting the base metals and chemicals the grey is a mixture of grey and white ash once again the base metals and oxides combine to cause the refraction after burning.
How does this translates into bud? We can establish the colour of ash is determined by refraction of base metals and oxides.
Black ash has a different chemical composition to white ash.
Grey ash is a combination of white and black ash.
I can't say which is "better" other than subjective experience but hopefully this link can explain the science a little better than I can.
At least we can say for certain that the chemical composition and oxidisation after burning is different.
If we look at nutes composition it may have some clues but tbh there may be a lot of variables like curing drying flushing. I smoked a strain that was most of the time burnt well left grey white ash tasted great got me whacked but occasionally the same strain burnt black and wouldn't fully combust or the chemical oxidisation was different and can leave a lump in the cone that tastes like shit.
The weed isn't as good either effect wise it appears quite wet or bendy stems its bloated but after a couple of days dries out burns well smokes well but not as good. Its a very consistent strain it's just occasionally a bit rushed he prob doesn't flush or cure sells wet.
Oxidisation could be a variable maybe heat differences or moisture levels which could effect a similar chemical composition. Its the same bud just moisture has effected the oxidisation and base metals refract differently plus carbon might be a residual of organic chemicals that did not oxidise.
That is speculation but there is a difference according to the science but there maybe other variables idk