The Secretary of Agriculture may by rules and regulations establish standards and procedures to be utilized in the determination of the effective neutralizing power of agricultural liming materials. Any agricultural liming material that is below the standard of effective neutralizing power established by the secretary shall not be sold or offered for sale in the Commonwealth as an agricultural liming material unless it is labeled “substandard.” Such labeling shall not be smaller than the largest labeling found elsewhere on the package and shall be prominently visible to the buyer.