1. Every manufacturer in this state shall be licensed and taxed on all raw material and finished products, except for grain and other agricultural crops in an unmanufactured condition, as defined in section 137.010, which are subject to assessment, valuation, and taxation under subsection 3 of section 137.115, as well as all the tools, machinery and appliances used by them, in the same manner as provided by law for the taxing and licensing of merchants; and no county, city, town, township, or municipal authority thereof, shall ever levy any greater amount of tax against a manufacturer than is levied against merchants for the same period.

2. Licenses issued under sections 150.300 to 150.370 shall be for one year, ending on the thirty-first day of December of the then current year.

3. Nothing in sections 150.300 to 150.370 shall be so construed as to apply to manufacturers whose raw material, finished products, tools, machinery and appliances in the aggregate amount are less than one thousand dollars.