2005 Year in Review

From the Fields

How effective is the 2-year corn-soybean rotation? That question and others related to the corn-soybean sequence was discussed at the recent Corn and Soybean Classics by Emerson Nafziger, University of Illinois crop specialist.

Reflecting back on 2004, many farmers feel that their continuous corn yielded as much, if not more that their corn following soybean. Also, some believe that growing corn for more than two years in sequence can “cure” the field loss from continuous corn.

Even though most research data does not support this, it is clear that as corn follows corn over several years, expectations may change so that yields become more “acceptable”, notes Nafziger.

University of Illinois has been conducting corn following corn and corn following soybean comparisons in the same field for the past seven years. The yield loss from corn following corn showed considerable variation, but there is no clear evidence of a trend in such yield differences over the years in northern Illinois. Large yield differences in favor of corn following soybean have occurred on an irregular basis. Corn following corn has yield about 12 percent less than corn following soybean in northern Illinois.

Does a corn-corn-soybean rotation offer better returns than corn-soybean? According to Nafziger, limited data on a new University of Illinois study show that yields of the second consecutive corn crop following soybean was considerablely higher than the yield of continuous corn, which in this case was the fourth year of corn. The study also suggests that hybrid choice can influence the response of corn to such changes in rotation. The response of soybean to this rotation differed among locations. Soybean following two years of corn yielded from one to eight bushels per acre more than soybean in the corn-soybean rotation.

Nafziger concludes by noting that there is a clear tradeoff between higher (and more stable) yields from crop rotation and producing enough of the crop that people, livestock and processors need in very large quantities. One cannot increase total corn production by switching large acreages out of corn into another rotation, unless that rotation produces much higher yield to compensate for reduced acreage.

What changes in rotation individual producers might make in their own fields will depend on how well individual fields can support continuous corn compared to rotation, and also what management changes producers are willing and able to make. Results from on-going University of Illinois crop rotation studies will be announced as the data becomes available.

by  Editor, theCity1.com
February 4, 2005