I would also be very happy if you could share your result with high application of wood ashes. It looks like a great opportunity if you can have large amount for free.

Jonathan, what is the interaction between Mn and K? I did a quick search in the book “Mineral nutrition of higher plant” and did not found anything on this. On my understanding, the calcium could be a problem because the CaCO3 will raise the pH and reduce the avalaibility of Mn. I also read that sometimes, Mg 2+ can compete with Mn 2+. I would like to hear your thought on that. It might be helpfull.