Bakers have been dealing with sustainability for several years now, and this is an issue they have every reason to expect to retain its prominence for many years.

A new initiative by Wal-Mart Stores setting sustainability goals for agriculture underscored the need for bakers to be engaged in the issue, both on the input and the output side of baking. Another recent corporate announcement, though, underscored the ambiguity of the term “sustainability” and the fragility of the alliance between growers and those seeking to make agriculture more sustainable.

Yogurt maker Stonyfield Farms on Oct. 13 announced it begin using cups made from corn-derived plastic. The company, whose mission is a commitment to “healthy food, healthy people, a healthy planet, and healthy business,” said the new cup requires less fossil fuel to make than polystyrene. So far, so good.

But the company goes on to say that it has initiated an offset program to produce what it calls sustainably produced corn to offset the amount used in its packaging. Here, Stonyfield, in a vigorously disputed position, says sustainably produced corn is corn grown without biotechnology.

Recent data from the International Food Information Council indicate consumers are comfortable with biotechnology, including wheat, if it leads to sustainable production practices “to feed more people using fewer resources such as land and pesticides.”

The IFIC study suggests meaningful progress in the public’s understanding of biotechnology, but the Stonyfield announcement shows the road ahead will not be bump free.