I've got a lot of old wooden fence bits, often rotten, and the preservative which was once on them must have washed out by now. Is it OK to burn it and spread the ash over where I want to plant shrubs, potatoes and soft fruit? Thanks.
This is my slant on the subject;
https://www.thegardenersalmanac.co.uk/Content/F/Fertiliser/Fertiliser.htm (https://www.thegardenersalmanac.co.uk/Content/F/Fertiliser/Fertiliser.htm)
Thanks Tee Gee, that's useful.
Well TeeGee has fully covered the basic wood ash question. On the matter of the preservatives and the combustion products that might result I suspect that no-one knows. The fact that the preservatives are no longer effective and the wood is going rotten must be evidence they have degraded or at least have leeched away.