I found these with a quick Internet search:
To continue your seach go to your browser search and punch
"New England" AND "Liquid fertilizer"
Exactly like that even with the "'s with caps on 'AND'.
A 15 gal is great for special mixes, or concentrations, or light doses. I think you may find out that to do full lawns for multiple properties you will want a larger tank otherwise you will be spending a lot of time searching for water refills.
As for some:
Sometimes integrated PEST management just means ignoring certain things. hint hint...