This time of year, the best use for me is sprinkling it on my icy driveway and sidewalks. I have freed many a vehicle from being stuck with a small patch of ashes spread about for traction. The ash grabs ice much better than any other material I have found. A bucket of ash travels with me everywhere all winter just for this purpose.
In the summer and spring, I just spread it around my forest areas with some in the gardens as well. I don't worry about PH, I just add anything and everything organic to my growing areas and count on Mother Nature to take care of the rest.
I never use glossy, colored paper in mine because I have the same concerns, so I can't help there.
old mail with plastic coated paper, ash from it is not what I want in the garden, wood ash from the stove goes directly into garden areas and will get tilled into the soil in spring.
in fact ive offered neighbors to take their trash to dump rather than have to smell the smoke from them burning plastic, its nasty stuff
I have mixed week old ash with coffee grounds, so even though it is cold, when I toss it outside in the snow it won't just blow away...or blow back at me. It usually goes on the walk way or where I want to darken a pile of snow.
I use wood ash in acidic soil. It does tend to neutralize it. Too much of anything probably isn't good but have never had a problem with reasonable amounts spread around the garden or in compost piles.
Paper ash in the garden? No. Not happening here. Too much potential for toxins & melted bits of plastic.
Argue for your limitations and they are yours forever.
I think burn temp matters and what you add to the fire as to the quality of the ash. I burn plain paper, card board (without tape), and untreated wood. Mostly just wood. It's in a high efficiency wood burner, which means it is fine dust when I am through with it. No plastic would survive. Ash has been used a garden fertilizer for thousands of years. Potash aka potassium garden fertilizer. I use it as a side dressing or around the base of trees. No problems yet. I might watch quantity on blueberries, but we have enough acidifiers here I don't worry.
I am sure that using of coloured newspaper as a firestarter in the stove / heater is no problem. The ash from such a paper mixes with a much larger ammount of subsequent wood ash and any potential odds from colours are dissolved into unimportant concentration. Any potential traces of heavy metals in this ash are even more dissolved in the soil then and does not elevate the level of them any significantly (in almost all soils there are traces of Cu, Cd, Pb and others..). That is my oppinion..
"Disturbance is critical" Joel Salatin
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