Ah, yes Epsom salts!
Does anyone remember when every self-respecting family had a crystal or glass container full of Epsom salts to make a nice foot bath to cure sore feet? Both my grandmothers used pounds and pounds of them. Of course a very magnesium-rich watery solution is no cure for sore feet, but it will quickly remove any wrinkling and reddening associated with wearing sweaty socks and non-traspiring footwear, so it looks like it works. Placebo effect and all of that.
The use in agriculture and gardening is debatable. Yes, there are magnesium-hungry plants of which roses (especially Thea hybrids) are formidable representitives, but magnesium deficiency is rare even in untended soils and these days 80% of commercially available NPK fertilizers contain "microelements", chief among which are magnesium sulfates.
I am not exactly saying it's snake oil because Epsom salts have their uses, but they are not the miracle cure they have been pushed for decades.The fact Epsom salts these days are cheap, much cheaper than when my grandmothers kept the industry going, may tempt folks into trying them: there's generally no harm done, but neither benefits.
