[Stewpot72]

Has anyone used this fairly new fertiliser, otherwise known as polysulphate. Apparently mined below the north sea and is the best thing since the last best thing.

[Subversive_plot]

Polyhalite will provide K, Ca, Mg and S, based on it's chemical formula. If your soil and crop need more of those, it might be beneficial.  I'd be careful to not over-apply (follow whatever directions are given).

Note that it does not provide N or P. You might need another fertiliser if you need more of those nutrients.