Re: "second largest employer after agriculture"
I think a comma makes a difference.
The second ranked, after [by the way] agriculture -- the #2 employer
The second ranked after agriculture -- Ag is #1, something else is #2, and then this is second after you take agriculture out of the picture.
That said, I still think, with or without the comma, people will read this as "Ag is #1 and this is #2."
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.