Tennessee Code Title 43. Agriculture and Horticulture § 43-11-125

(a) No political subdivision may regulate the registration, packaging, labeling, sale, storage, distribution, use and application of fertilizers; and, in addition, no political subdivision may adopt or continue in effect local legislation relating to the registration, packaging, labeling, sale, storage, distribution, use or application of fertilizers. Local legislation in violation of this section is void and unenforceable.

(b) Subsection (a) shall not apply in any county having a population in excess of two hundred thousand (200,000), according to the 2000 federal census or any subsequent federal census.