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Does corn after corn pay?

When yields and prices are good, corn planted on corn beats the pants off corn rotated with soybeans or other crops.

“Continuous corn yields (prior to 2011) were almost too good to be true,” says Jeff Hartz, marketing director for Wyffels Hybrids.

In 2011 and 2012, though, matters changed. A 2011 soggy spring followed by a late-summer drought curbed corn-on-corn and continuous yields in many parts of the Corn Belt. This left scant moisture for the 2012 drought that singed yields of all corn systems.  

Under such conditions, a corn/soybean rotation fared better than continuous corn in a 2012 analysis by Mike Duffy, Iowa State University Extension economist.

In that case, the $168-per-acre net revenue from a corn/soybean rotation edged that of continuous corn’s $138 per acre. Assumptions included:

  • 165-bushel-per-acre continuous corn priced at $6 per bushel.

  • 180-bushel-per-acre rotated corn priced at $6 per bushel.

  • 50-bushel-per-acre soybeans priced at $12 per bushel.

Much hinges on yields and prices, though. When Duffy boosted continuous corn yields 5 bushels per acre or the corn price to $8.24, though, returns were identical.

Snap Back to Reality

In some areas, corn after corn yields snapped back in 2013.

“It helped (in 2013) that July was fairly wet,” says Emerson Nafziger, University of Illinois Extension agronomist. “When corn gets into trouble, it’s often because July is dry. At the end of July, there was a lot of water in the soil in most areas. Crops could live on stored soil moisture during August.”

That’s one reason 2013’s estimated U.S. harvest tallies 14 billion bushels, far above 2012’s 10.8 billion-bushel corn crop.

For 2014, it appears corn might edge out soybeans for profitability. The corn/soybean yield ratio is a big factor in determining farm profitability. For 2013, the Illinois ratio was 3.51 (165-bushel corn vs. 47-bushel-per-acre soybean yields.) That was below the 3.59 average for good corn yields during the decade of the 2000s. It’s below the 3.08 average from 2010 to 2013, a period of down corn yield years.

An early yield ratio extrapolation for 2014 is a 3.43 ratio that’s favorable to corn. It’s important to note, though, that yield predictions are difficult to make.  

What To Consider

If the market gives favorable corn-growing signals, a good share of it will continue to be grown on corn ground. Challenges exist, though.

“Continuous corn is always a challenge, and that is due to all that extra residue,” says Bob Nielsen, Purdue University Extension agronomist. “Excessive residue slows soils from  warming up. You can have all kinds of diseases, and it can hamper emergence.”

All this can create yield drag. “Typically, continuous corn can reduce yields 5% (compared to rotated corn) and 15% for a bad job,” he says.

Good to Know

You’ll often hear corn-on-corn and continuous corn interchangeably used, but there is a difference.

Corn-on-corn means corn in its second year following a crop like soybeans. Continuous corn means corn grown the third and subsequent years.

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