Agricultural Shipper Protection Act of 1986 - Delineates the essential terms of an agricultural commodities transportation contract which must be made available to the general public in tariff format. Deems any subsequent changes to such terms to be a new contract for purposes of this Act. Directs the Interstate Commerce Commission to promulgate within 60 days after enactment of this Act regulations which require such essential contract terms to be made available to the general public in tariff format. Proscribes rail transportation service under a contract until such contract receives Commission approval. Directs the railroad contract rate advisory service to: (1) assess the impact on competition among agricultural shippers of contract rate variations for various shipments and published single car rates; and (2) report to the Congress within 120 days after the enactment date of this Act.