Milk Marketing Supply Management Act of 1989

Milk Marketing Supply Management Act of 1989 - Amends the Agricultural Act of 1949 to direct the Secretary of Agriculture to conduct two referendums (one for 1990, the other for 1991 and 1992) among milk producers to determine whether to implement an alternative milk price support program for the respective periods based on individual milk marketing bases and a 70 percent of parity support level.

Directs the Secretary, prior to the beginning of 1996, to conduct a study of the economic impact of this Act and such alternative price support system. Continues such system beyond calendar year 1995 unless the Congress disapproves it, by joint resolution, prior to July 1, 1995. Sets the support level at 75 percent of the parity price if the Congress disapproves such system.