R.I. Gen. Laws § 2-7-9: Commercial value.

For the purpose of determining the commercial value to be applied under the provisions of § 2-7-8, the director shall determine and publish annually the values per unit of nitrogen, available phosphoric acid, and soluble potash in commercial fertilizers in this state. If guarantees are as provided in § 2-7-3(8)(ii), the value shall be per unit of nitrogen, phosphorus, and potassium. The values so determined and published shall be used in determining and assessing penalties.