There are four states that have added 2 million plus acres to both Corn and Soybeans.. They are..

North Dakota + 2,210 Corn acres + 660 Soybeans = 2,870
South Dakota + 1,400 Corn + 1,000 Soybeans = 2,400
Nebraska +2,100 Corn - 50 Soybeans = 2,050
Kansas 1,150 Corn + 890 Soybeans = 2,040

This 9.370 Million acres expansion in the Corn and Soybean Acreage is significant especially when you consider that the average corn yield in ND is 110 bushels, 127 in Kansas and 138 in South Dakota vs the National average of 158.8.

On the Soybeans the state averages are 40 for South Dakota, 36.0 for Kansas and 30.0 for North Dakota.

Irrigated Nebraska production is pretty decent in both crops.

Take away:  We've added a lot of acreage since 2006.. over 9 myn acres in the Plains states.. (other than Ne) this is NOT very high yielding ground.