It is further declared to be in the public interest and highly advantageous to the agricultural economy of the state that producers of beef, corn, pork, and eggs on a commercial basis shall be permitted, by referendum, to be among such respective producers and subject to this chapter, levy upon themselves an assessment on these products and provide for the collection of the assessment, for the purpose of financing or contributing towards the financing of a program of promotion, advertising and research designed to increase the consumption, use and sale of agricultural commodities in domestic as well as foreign markets.