Are hazardous chemicals blended for fertilizer exempted under agricultural use exemption?

Ammonia and phosphoric acid are held for sale by a retailer in large storage tanks.  The retailer sells both ammonia and phosphoric acid to farmers to be used as fertilizers.  The retailer also blends ammonia with phosphoric acid to produce a new compound which, in turn, is also sold to farmers as fertilizer.  Are the amounts of ammonia and phosphoric acid that are held for blending at the retailer's facility exempt from the definition of "hazardous chemical" under Sections 311/312?

Section 311(e)(5) exempts from the definition of hazardous chemical "any substance to the extent it is used in routine agricultural operations or is a fertilizer held for sale by a retailer to the ultimate customer".  In the above example, the ammonia and phosphoric acid are intended for blending are not exempt from the definition of "hazardous chemical" since they are not "... a fertilizer held for sale by a retailer to the ultimate customer."  They are, in essence, chemicals held for the purpose of producing a fertilizer. In other words, the ammonia and phosphoric acid held for blending are the starting materials used to make a fertilizer; they are not, in this instance, fertilizers themselves.  The retailer should report the amounts of ammonia and phosphoric acid that are held for blending to produce the new fertilizer.  The amounts of ammonia and phosphoric acid that are sold directly to the ultimate customer (without blending) are fertilizers exempt from the definition of "hazardous chemical" and would, thus, be exempt from reporting under Sections 311/312.