Well that is a heckuva lot of sulfur- are you sure 15%? A high level would be 1% or more!
If you INSIST on using it, it would be as a veg fert only, and to find the application level, look at other types of plant foods and find one with similar levels, and use that application rate.
But I sense that you will have trouble with that stuff. Really, fertilizer is something taht if you get the right stuff to start, it will save trouble down the road.