If the manure is older and composted, an inch or two deep in the fall sounds good to me.

Even if it hadn't already been composted, it would have been a nice addition and would have composted over the winter. Since it was already composted, it's a good thing as is.

Uncomposted chicken manure is high in nitrogen and can burn plants if it is used too heavily, but it should be fine composted, especially since it has all winter to continue breaking down if it isn't fully broken down now.

Nothing is destroyed. Since you are using this for your fall garden it might be a bit rich depending on the source's definition of finished. You mentioned no strong smell, but any ammonia smell at all? If not, you should be ok. What were you going to plant and how much of the composted manure was left?

tj

No strong smell, no ammonia. I only figured it out because it didn't smell loamy like the mushroom compost does. Then I started finding flecks of chicken grit: mica or very fine seashells.

I can probably get the coverage down to about 2" on the bed. It may be there already. This may be the event that forces me to get a little tiller to mix what's left in really well. I'll use a shovel to mix it deep, too.

J

Your beds will be fine and unless you plan on dumping nuclear waste or other super toxic substances on your beds the soil will be just fine. If you want to add some tilth to the sandy soil, add red clay with composted leaf mould and you will be amazed.

If it is composted, you can not have too much, just to little time(to get more)or space to put it.
For 20 year a local farmer raised onions & turnips for sale at the farmers market. This was long before Organic was a bran name for every con man who wanted to increase his/her sales. This farmer only used chicken manure on his sandy fields, which were black as coal by the time I came a lone to see them. He hauled the manure & sheet composted it (spread it & cut it in with a tractor)himself.
You are lucky, wish I had a friend like that here.