fertilizers all have a salt index! Some are higher than others, so you have to be carefull at the rate you apply fertilizers, for each application, and the total per year. I've seen the salt index on milorganite, extremely low, but so is uf, which is a sythetic fertilizer!
Timothy J Murphy Specializing in Quality Turf
Bs in Plant and Soil Science
Almost 40 yrs exp., 20 as GC superintendent
Primarly work with cool season turf