Marc,
After you're done burning, use a flat edged shovel to remove the thin layer of ash.
I planted a pear on a similar site, though 5 years+ after burn, and it was the only pear that died out. It began drying out on top in the fall, began sprouting in February from the rootstock, I attempted to graft onto rootstock in late march, but cambium was dry-dead.
There are some benefits to using ash, but from what I've read it's best to apply sparsely as the lye in it is caustic and will burn.

I don't know what else could have been in the burnpile. Gypsum boards...

how big a burn????

a giant burn.. can actually change the structure of the soil itself ...

ken

I vaguely recall reading that severe heating of some soils can lead to an over-availability of some nutrient element and toxicity problems. I think it was manganese but do not recall with confidence.

You are much better off chipping it and leaving there. That way you are sure you are improving the soil. It is reasonable to make sacrifices early for your trees.

I wish I had the resources to chip, but this is a huge pile--perhaps 25'x30' and 8' high. Much of it is honeysuckle we cleared, though some is gnarly wood too difficult to split and stack for firewood.

Marc

now thats a burn pile like mine.. lol ..

when i burn a pile like that.. its an 8 to 10 hour burn.. and my sand actually turns colors.. and crystallizes [probably not the right term] ..

i moved the pile once.. had no problem re-establishing grass ... provided i could get water out the 500 feet to the area ... so the soil cant be that bad.. but i probably wouldnt go planting $100 specimens out there ...

if you have that big of a pile.. i find it hard to believe.. you are so limited as to space ... that you have to plant right there..

ken

What about burning it damp, even if it takes a few attempts? Make lots of useful charcoal for the soil. If you have hose water, thoroughly wet the pile, let the outside dry a few feet down and burn it, scorching the damp brush underneath. Do it again if need be. Never let the very hot flames or large coals to last long at ground level, spraying when it gets near there.

Bananas....I like the idea. That's sort of what I'm hoping to do when the next--if it ever arrives--rain storm hits. No hose water available. Hadn't thought about the benefits of charcoal.

Marc

Rather than ignite the whole pile at once and affect the whole ground area beneath it, I put in the extra work to start a smaller fire nearby and feed it with additional cut-up branches from the giant pile until the big pile all goes up in smoke. It takes a day to do, but I can use the exercise. That way your paw paw planting plans won't be replaced by an Ash tree.