I have a jug of this from a few years ago. Would it still be OK to use? Also would egg shells be comparable to using Epsom salts in the garden?
Fish Emulsion Fertilizer
Certified GKH Gardening Expert
Yes, fish emulsion from a few years ago should still be good for your garden (it might smell a little worse though).
Egg shells can be used to add calcium to the garden, but they break down over several years, so they will provide more benefits for next year's plants than this year's:
Epsom salts are magnesium sulfate, so they add different nutrients: