Sec. 4. As used in this chapter, "blending" means the physical mixing or combining:
(1) of one (1) or more commercial fertilizers and one (1) or more filler materials;
(2) of two (2) or more commercial fertilizers; or
(3) of two (2) or more commercial fertilizers and filler materials;
including mixing through the simultaneous or sequential application of any of the combinations referred to in subdivision (1), (2), or (3) to produce a uniform mixture.