By Colin Hudson for the 7th Annual Conference of the BSTA 1989
Like so many soil amendment questions, there is a shortage of hard facts about the value of flyash, but there is considerable circumstantial evidence for its benefits.
Excerpt
In the early 1960’s, when ash arrestors became common and flyash was available by the truckload, some enterprising farmers spread it on fields which were felt to be substandard. Invariably good responses were observed.
Flyash = Soot = Good News pdf