Since my piece with Henry Miller on biotech wheat appeared in the New York Times, I've had several requests for good sources on the economics of agricultural biotechnology. Here are a few.
1) Agricultural biotechnology: the Promise and Prospects of Genetically Modified Crops in the Journal of Economic Perspectives in 2014 by Barrows, Sexton, and Zilberman
2) The Economics of Genetically Modified Crops in 2009 in the Annual Review of Resource Economics by Matin Qaim
3) The USDA Economic Research Service has several good papers.
In particular, see The First Decade of Genetically Engineered Crops in the United States
4) A book chapter on Consumer Acceptance of Genetically Modified Food by yours truly in 2011