In carrying out the provisions of this chapter it shall be the duty of the Secretary and the Broadcasting Board of Governors to utilize, to the maximum extent practicable, the services and facilities of private agencies, including existing American press, publishing, radio, motion picture, and other agencies, through contractual arrangements or otherwise. It is the intent of Congress that the Secretary and the Broadcasting Board of Governors shall encourage participation in carrying out the purposes of this chapter by the maximum number of different private agencies in each field consistent with the present or potential market for their services in each country.