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Agronomy Day 2007

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Managing Corn Following Corn

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Eric Adee Emerson D. Nafziger
Extension Agronomist and
Professor of Crop Sciences

With 12.9 million acres of corn in Illinois in 2007 following 10.1 million acres of soybean in the state in 2006, about one-fourth of the corn crop in Illinois in 2007 follows corn. If the demand for corn means increased corn acreage into the future such that we have 2/3rds corn and 1/3rd soybean, then half of the corn crop will follow corn every year. We’re clearly on the road to corn following corn as a “normal” crop sequence in Illinois.

While management of continuous corn has usually been thought of as more challenging than management of corn following soybean, we are learning that with newer hybrids, the management differences between these two systems may be less than we once thought:

While we are continuing many of these studies to learn how to better manage CC, we do not find responses to management to be consistently different in CC compared to those in SC. Questions that remain to be answered include whether or not we can do less tillage, including strip-till, in CC, and what effect removal of residue (for conversion to biofuel) might have on yields and soils in CC.

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Figure 1. Yield advantage of SC over CC in 11 comparisons at Urbana, IL.

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Figure 2. Trends in optimum N rate, yield, and yield without fertilizer N over 8 years in a study at Urbana, IL

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Figure 3. Effects of tillage, higher fertilizer rate (+100 lb N), and plant population on yield of continuous corn in a 3-year study at Urbana, IL.