There has been a great deal of conversation over the past several weeks about the possibility that U.S. corn and soybean yields might be much better than current estimates. That higher yield speculation is of course the result of great weekly crop condition ratings. In the past week, however, the tone of this yield chatter has started to change a bit. Following are a few reasons why:

The southern Plains drought situation hasn’t improved and has continued to slowly creep into southern Iowa, Missouri, eastern Kansas and Arkansas. Part of eastern South Dakota and western Illinois are also turning dry. The saving grace for these dry pockets might be that temperatures have returned to normal, which is also the extended forecast. What do...