V. When the commissioner finds, after public hearing following due notice under rules adopted by the commissioner under RSA 541-A, that the requirement for expressing the calcium and magnesium in elemental form would not impose an economic hardship on distributors and users of agricultural liming materials by reason of conflicting label requirements among the states, the commissioner may require by rule that the minimum percentage of calcium oxide and magnesium oxide and/or calcium carbonate and magnesium carbonate shall be expressed in the following form: Total Calcium (Ca) .................. percent Total Magnesium (Mg) .................. percent
The effective date of such a rule shall be not less than 6 months following the adoption of the rule, and for a period of 2 years following the effective date of the rule, the equivalent of calcium and magnesium may also be shown in the form of calcium oxide and magnesium oxide and/or calcium carbonate and magnesium carbonate.