They probably test them because there is a no smoking situation at their plant. Fertilizer is extremely flammable and they probably don't want to go boom. They do the same tobacco testing at places that dispense jet fuel.
Would be my guess anyway.
Dizzy1 Reviewed by Dizzy1 on . Miracle-Gro ... when I put my present clones into the flowering cabinet, I am going to sacrifice one to a test ... I will grow out one of my 12 Willie Nelsons, using only Miracle-Gro fertilizer ... I'm kinda curious myself, as I used only Miracle-Gro for many years (yes, MANY:D) ... I'll update from time to time :smokin: Rating: 5