Inputs for Continuous Corn

FOR IMMEDIATE RELEASE
March 19, 2008

Various strategies have been suggested to improve the yield of continuous corn. Historically, that rotation has not yielded as much as corn grown in some rotation with soybean. A commonly asked question has been, "Does continuous corn require more and/or different inputs than corn grown in rotation with soybean?"

Lyle Paul, agronomist at the Northern Illinois Agronomy Research Center near Shabbona reported the results of a three year study involving two levels of tillage, fertility, and harvest population in continuous corn.

The "normal" tillage was coulter chisel plow, and the "more intense" tillage was either deep tillage shanks or the mini-moldboard plow. "Normal" fertility was 220 pounds nitrogen, 92 pounds P₂O₅ and 150 pounds of K₂O. The "higher" fertility program was 320 pounds nitrogen, 172 pounds P₂O₅ and 270 pounds K₂O. The "normal" harvest population was 32,000 plants per acre, and the "increased" harvest population was 40,000 plants per acre.

The three year (2005-2007) average yield for each level of the three variables did not differ greatly.

The "more intense" tillage variable produced three bushels per acre more than the "normal" tillage (207 bushels vs. 204 bushel). The "higher" fertility program yielded

five bushels per acre more than the "normal" fertility level (208 bushels vs. 203 bushels).

The "increased" harvest population produced one bushel per acre more compared to the "normal" harvest population (206 bushels vs. 205).

Paul noted that the most positive response to changing the variables was increasing the fertility program (5 bushels per acre increase). However, the cost of additional nitrogen would have been more than the value of the yield increase.

Based on the variables in this three year study, inputs for continuous corn do not differ greatly from corn that has soybean in the rotation. Details of the study are available from Paul, phone 815-824-2029, or email lylepaul@uiuc.edu