Extension News

Cold Weather Dampens Corn Planting


Iowa farmers are planning to plant more corn than ever, but not just yet.

Roger Elmore, Iowa State University (ISU) Extension corn specialist, says the rain and snow across all of Iowa this week will delay corn planting. The possibility of delayed planting is a legitimate concern, considering that Iowa farmers intend to plant 10 percent more corn in 2007. 

“We are at a time when Iowa agriculture is undergoing a vast structural change due to the biofuels opportunity and the condition of Iowa’s corn crop has an impact on the state’s emerging bioeconomy” said Jack Payne, vice president for ISU Extension and Outreach. “The nation and Wall Street are now interested in how much corn Iowa produces.”

“Iowa corn planting dates have become progressively earlier over the last three decades,” said Elmore. “Half of the 2006 crop was planted by April 25, more than two weeks earlier than during 1975-1979.”

“The time required to plant all of Iowa’s corn acreage in 2006 was approximately six weeks, from April 16 to May 28. If 2007 planting intentions are carried out, Iowa producers will need about four more days to plant the expected increase of 1.3 million acres of corn, if using last year’s pace of planting,” he said. 

Four days does not sound like much of an addition, given normal weather in the spring. However, this year it appears the start of corn planting will be delayed until the week of April 23. If producers keep the same planting pace as in 2006, planting would be expected to finish during the first week of June. 

“In a recent issue of the Integrated Crop Management newsletter (http://www.ipm.iastate.edu/ipm/icm/2007/4-2/cornplant.html), we reported that optimum yields are obtained when corn was planted between April 15 and May 15. Using a conservative estimate, yields decreased approximately 0.75 percent per day after this optimum period. At a yield level of 180 bushels per acre that is equivalent to 1.3 bushels yield reduction per day,” said Elmore. 

He added that this yield reduction is an estimate, and will vary based on many factors such as location, weather and hybrid. 

“If planting starts during the week of April 23 and proceeds at a pace similar to that of 2006, then 80 percent of Iowa’s corn should be planted by mid May, thereby realizing full yield potential,” said Elmore.

However Elmore strongly cautions corn producers not to plant until field conditions are right.

“ ‘Mudding’ in corn will decrease yield potential not only in the short term through reduced plant stands and variable plant emergence rates, but can have long-term impacts such as poor root development caused by soil compaction,” he said.

Elmore added that most seed companies have reported that the more popular hybrids are already sold; many of these are transgenic hybrids. If large areas of corn need to be replanted this year, supplies of the popular hybrids will be limited, if available at all.

“The best plan is to keep the seed in the bag and the planter in the shed until seedbed conditions are conducive for planting corn,” said Elmore.


Contacts :

Roger Elmore, Agronomy, relmore@iastate.edu, (515) 294-6655

Lore Abendroth, Agronomy, labend@iastate.edu (515) 294-5692

Jean McGuire, Extension Communications and Marketing, (515) 294-7033, jmcguire@iastate.edu