Are The Ashes From A Coal Burning Grill Good For Your Garden?

Question

I thought perhaps there was nitrogen, carbon and other elements contained in the ashes because of the coal.

Answer 1

Charcoal briquettes are made with chemical additives that you probably don't want in your garden. Ashes from burned trees and shrubs are fine, but take into consideration the increased acidity they will bring to your garden soil.
https://www.gardeningknowhow.com/composting/ingredients/composting-ashes.htm