When used in this chapter:
Total Nitrogen (N) ..... percent
Available Phosphoric Acid (P2O5) ..... percent
Soluble Potash (K2O) ..... percent
Total Nitrogen (N) ..... percent
Available Phosphorus (P) ..... percent
Soluble Potassium (K) ..... percent
Provided, however, that the effective date of the regulation shall be not less than six (6) months following the issuance of this regulation and provided further, that for a period of two (2) years following the effective date of the regulation, the equivalent of phosphorus and potassium may also be shown in the form of phosphoric acid and potash; provided, however, that after the effective date of a regulation issued under the provisions of this section, requiring that phosphorus and potassium shall constitute the grade.
R.I. Gen. Laws § 2-7-3