4. The heavy rainfall in May and June in some areas was a repeat of what we saw in 2010. But with the crop not nearly as far along in 2011 and with June temperatures not as high as in 2010, immediate effects of this heavy rain on the corn crop were not as severe in 2011 as in 2010. This did delay the return of the crop to normal color and growth in corn following corn.
5. When the rains stopped in many areas in late June, and soils dried in July and August, the effects were much more severe in most corn-on-corn fields than in fields where corn followed soybean. Due to drier soils, root systems generally developed better and remained healthier in 2011 than in 2010. But with compaction, slower growth due to less (and a less green) canopy, residue, possible tillage effects, and other factors at work in corn following corn, it seems that the ability of the roots to extract water compromised in corn following corn compared to corn following soybean. Both crops seemed to pollinate okay, but corn following corn showed more leaf stress in July and August, and reduced light interception was evident in many fields where corn followed corn. This increased kernel abortion and decreased the ability of the crop to fill the kernels it had.
6. In the driest areas, corn following corn lost canopy color and died prematurely, often before corn following soybean. This stopped the filling of kernels, and in many cases, led to more stalk quality problems.
After corn-on-corn has done so well in recent years, many growers are discouraged to have a second year of lower yields in many corn-on-corn fields. Many will find that their profitability will be higher with corn following soybean than corn following corn this year, even accounting for what have often been lower returns from soybeans than from corn in recent years, Nafziger said.
“We can’t simply decide to plant more corn acres following soybean in 2012 than we did in 2011; we planted only about 9 million acres of soybeans in Illinois both years, and acres of corn following soybean the next year can’t exceed that number,” he said. “So as long as corn acreage stays near the 12 million acres of recent years, some 20 to 25 percent of Illinois corn will have to be corn following corn.”
Given the severity of this problem and the fact that it has now happened a second year, Nafziger requests that anyone experiencing this problem send him an e-mail at email@example.com describing a) a brief description of the yield differences; b) where the problem is occurring the worst; and c) if there are any corn-on-corn fields that seem to have escaped this problem to yield nearly as well as corn following soybean and possible explanations for the differences.
For more information, read The Bulletin online at bulletin.ipm.illinois.edu/.