That's a good question, I'm hoping some sciencey person comes along and answers that.
If you use diesel urea on your plants and it harms them, you might get pissed. Which reminds me...I suggest a morning squirt into a rinsed gallon milk jug, then filling the jug with decent water and using that as a quick nitrogen boost. Your plants will like it, and big fertilizer companies will be pissed.
I know, I know, ewwww, but it works!