I am by no means looking to apply it now, but I would love to know what my fellow maple growers use for a nitrogen source when fertilizing. I know that when it comes to JMs, not all sources are equal. A certain favorite book says, "Acer palmatum seems to resent the ammonium sources of nitrogen. Calcium nitrate works best, with other non-ammonium sources also working well." Keeping in mind that I prefer 'organic' fertilization options, I humbly beg for edification: what are the ammomium sources of nitrogen to avoid and what is/are the common form(s) of calcium nitrate? What are other non-ammonium sources? Thank you very much. I look forward to a wrinklier brain!