The calcium question: first off, calcium is a plant macronutrient. It
can be expected to be benificial to all plants. Different plants will
differ in their requirements and tolerance of different Ca++ levels.
Gypsum (CaSO4) is much used to replace problematic Na+ ions in soil, via
the phenomenon Mr. Maharaj has described. I can't guess how this might
translate to a peat medium, but it works for farmers with salty dirt
(why do you think they go around tasting the dirt, just a macho
pullover?) :-) I would like to hear about the natural habitat of
Mexican Pings. I bet that if they grow in limey(sp?) areas you won't
find sphagnum growing there. How about U.S. marl bogs?? I have heard
that P. gypsicola grows on limey sites, but I have also heard that many
Mex. Pings grow as epiphytes on mossy logs and even on tree trunks.
Are these sites alkaline? I would guess not. Why not run an
experiment: grow two sets of pings in pure perlite, water one set with
distilled H20 (tends to be slightly acid), water the other with alkaline
water. Unfortunately, alkaline tap water (like we have in AZ) may not
be the best source of alkaline H20, as our water has pleanty of other
stuff in it besides excess OH- ions! Still, it would be a great
experiment to try, just to see if tap water could be used out here. I
am not yet convinced that all Mex. pings like it alky, and I have too
few of 'em to risk it myself!
MJC