Failure to Yield: Evaluating the Performance of Genetically Engineered Crops (2009) | Union of Concerned Scientists

Meanwhile, the report found that Bt corn likely provides a marginal operational yield advantage of 3 to 4 percent over typical conventional practices. Since Bt corn became commercially available in 1996, its yield advantage averages out to a 0.2 to 0.3 percent yield increase per year. To put that figure in context, overall U.S. corn yields over the last several decades have annually averaged an increase of approximately one percent, which is considerably more than what Bt traits have provided.

Monsanto's strain of Bt corn is just what Germany banned the other day.

The fact is that what we're experiencing right now is a top-down disaster. -Paul Krugman