You might consider holding off on Epsom Salts (magnesium sulfate) without having a soil test first.
It is not common in most of the country but some soils, scattered areas here in CT for example, have an above optimum level of magnesium. At best, adding more to these soils is a waste of money and, at worst, calcium uptake will be inhibited by the excess magnesium.
I have the soil tested every year at UConn. For $8 the university reports the pH and available calcium, magnesium, phosphorus, potassium, iron, manganese, copper, zinc, aluminum and boron in the soil along with how much of what to put in the soil to bring it up to par. Save me a lot of money knowing what is in that soil before buying this and that to try to improve it.
Carved a garden out of the lawn three years ago and every year so far the soil has had "above optimum" levels of magnesium. That means using dolomitic limestone and/or Epsom Salts are counterproductive. So I use calcitic limestone to raise the pH and gypsum (calcium sulfate) The sulfate in the gypsum binds with the magnesium in the soil forming magnesium sulfate (Epsom Salts) which washes out and leaves calcium--a element most soils have adequate levels of but which big biomass plants (I grow the large dalhias) flourish on.
