bonfire ash disposal by soil amendment?
Hi - There is a large bonfire pit with several wheelbarrows of ash accumulated over the years. The bonfires were often started with diesel fuel. Is the ash safe to put on the edge of woodland lots or into gardens?
As long as the diesel was sprinkled on the wood/lumber/fuel so that it burned along with it, the ash should be diesel-free and okay to use. The oil contaminants would have gone up with the smoke. Only diesel poured on the soil or excessive amounts on the old accumulated ash so that it didn't burn would be a problem. You can probably judge that for yourself on-site.
Ash is about 1/2 as alkaline as lime. Avoid using it in quantity around acid-loving plants such as azaleas, or rhododendrons and not around blueberries at all.