Horsetail has a very high silica content, but I don't know if that impacts preservation or not - although the chemistry for pickling may need special tweaking because of that. Hmmmm...mkaes me wish I had paid attention in chem class back in the day...
I'm just a girl trying to fix some seriously damaged land. Seriously.
I found this site mentioning pickled horsetail (http://livingwithbasics.com/naturesmedicinechest/horsetailgrass.html), but they don't give any special directions, so...I would just try to pickle it like anything else. I would, however, try traditional vinegar/heat pickling and cold lacto-fermentation to see which one turned out better.
I'm just a girl trying to fix some seriously damaged land. Seriously.