What is it with corn on corn?
Continuous corn and corn-on-corn used to be a snap to grow. But that hasn't been the case in 2010 and 2011 in some regions like central Illinois.
“There were pockets that have had really bad luck the past two years,” says Emerson Nafziger, University of Illinois (U of I) Extension agronomist. In some cases, reports of 100-bushel-per-acre yield differences for corn following corn vs. corn following soybeans under similar practices surfaced.
“Our corn-on-corn yields used to be tremendous,” says Clarke Kelso, Macomb, Illinois. “In 2008, our average corn yield was 240 bushels (per acre), and most of that was corn-on-corn. We have been disappointed the last two years, though. Frequently, corn-on-corn yields have been 20 to 40 bushels per acre below those of corn following soybeans.”
Still, excellent demand has caused many farmers to stick with corn following corn in 2012.
“We used to be in the low 20s (millions of acres),” says Ty Vaughn, U.S. corn product management lead for Monsanto. “Now, we are pushing 28 million acres of corn after corn.”
In agronomic jargon, corn-on-corn means corn in its second year following a crop like soybeans. Continuous corn means corn in at least its third year. Typically, second-year corn yields take a 10% yield hit compared to corn planted after soybeans. That dip, though, has been eased by the advent of insect-resistant traits protecting corn from European corn borer and corn rootworm.
“I have had farmers tell me, ‘We don't have any more problems with corn-on-corn. We have corn borer whipped. We have rootworm whipped.’ From an agronomic standpoint, our expectations got off a little bit,” says Nafziger.
Problems in 2010 started in the fall of 2009, where sopping soils during a hectic harvest nixed fall tillage in many areas of the Corn Belt. Spring tillage and subsequent planting in 2010 occurred in still-wet soils and sticky residue that hampered emergence.
“In 2010, lower yields were caused by a compromised root system damaged by saturated soil conditions,” says Nafziger. This was further compounded by limited July and August rainfall.
Last year was more straightforward, as a great autumn in 2010 paved the way for fall tillage. It set up a smooth planting season with excellent emergence. Then it turned dry.
“Most evidence points to lack of water during the critical grain-filling period as a major cause of lower corn-on-corn yields in 2011,” says Nafziger. “In both years, heavier and wetter soils tended to be affected the most. These are some of the better-producing soils in a normal year. In 2010 and 2011, some clay knobs did better than good soils.”
High input costs also accompanied plunging yields for corn following corn.
“Everything is more costly if you grow more corn,” says Gary Schnitkey, U of I Extension farm management specialist. “We see lots of additional tillage on corn-on-corn to break up cornstalks. This adds to costs and reduces the advantages of corn-on-corn.”