2007 was a good year for corn following corn. Many University of Illinois trial comparisons showed little difference in yields of same hybrids following corn and following soybean.

At the University of Illinois Agronomy Research and Demonstration Center near Monmouth, the average corn yield was 245 bushels per acre when following soybean and 235 bushels per acre when following corn. Statistically, the correlation between corn following soybean vs. corn following corn was 0.67, meaning that hybrids performed fairly similar regardless if following soybean or corn. Typically, continuous corn yields have been 10 to 15 percent less than rotated corn.

The same hybrids with different traits planted following soybean and corn were also compared at Monmouth. The results are shown in the table below.

Resistance Trait	No. of Hybrids	Soybean-Corn, average yield/acre	Corn-Corn, average yield/acre
Corn borer	5	248 bushels	237 bushels
Corn rootworm	6	251 bushels	242 bushels
Corn borer + corn rootworm	43	243 bushels	234 bushels

As shown, there was only 9 to 11 bushels per acre difference in corn following soybean vs. corn following corn for hybrids representing the three different resistance traits. Eric Adee, Research Specialist at Monmouth notes the lack of difference in corn yields between the two rotations can probably be attributed to the growing season, with the additional benefit of corn rootworm resistant hybrids contributing to the performance of continuous corn this year.

Emerson Nafziger, University of Illinois Extension corn specialist, indicates that correlations between yields of corn following corn and corn following soybean of the same hybrids were more consistent than in previous years. It appears that selecting hybrids, with confidence, for corn following corn may be getting easier.