What I know about the use of wood ashes as fertiliser or soil conditioner is that;
1). our ancestors (I think bronze age) used it, and
2). we, as a country, imported wood ash from America before the introduction of oil based fertilisers
3). I have been using it for the last few years successfully and no problem, my soil is good and crumbly and most of my veggies are fine, and the ones that aren't I can not directly blame on the ashes.
"So what is the question?", you ask.
Reading other gardening forums and web sites, there are such terrible stories of ground becoming too alkali and unusable (for three years one person claimed!), only put on one kilo per 100 meters another advises, others claim it's fine, chuck on as much as you want , etc. etc. there are anecdotes supporting either side of the argument.
Is there any one who has the definitive answer, 'Are bonfire/wood ashes good for the allotment, and is there a limit to how much you should use?' An answer based on scientific knowledge and understanding, not heresay, rumour or gossip would be appreciated. Thanks