In January, at the Texas A&M University Agricultural Program annual
conference, one of the keynote speakers talked about the centralization and
industrialization of agriculture in the U.S. and the world. For almost
every major commodity--corn, wheat, pork, etc.--five or fewer companies
controlled over 50% of the production.
The conference had no published proceedings, but the speaker was:
William D. Hefferman,Professor
Department of Rural Sociology
University of Missouri, Columbia
If you contact him or do a literature search, you should be able to find
some information on the subject.
Agricultural Engineering Department
Texas A&M University
College Station, TX 77843-2117
(409) 845-7686 (firstname.lastname@example.org)