"I realize that 5 or 6 million acres did not get planted to wheat."

Wheat double cropping was down a significant amount across the production belts primarily because of the late harvest prevented timely planting... but also because of the economics and production costs involved.

Realize that missing 5 or 6 mln wheat acres also removes about 5 or 6 mln acres for potential double crop.  The net effect is that you also have to subtract x amount of acreage from double crop beans to full season and y amount will go to full season corn.. but this is NOT the same as finding 5 or 6 million NEW acres.

In 2008 almost half of our wheat crop was doubled back.. and with nearly $10 Wheat and about $15 Soybeans it made sense to take those kinds of risks...  Today Wheat is more like $4.00 and new Crop Soybeans are closer to $8.30... so next year we probably won't double crop any acreage given those prices.