Corn can handle a lot of moisture, but standing in water multiple days can ruin the yield potential of even the hardiest plants.
With any luck, the excess moisture Midwest farmers have recently endured will abate and allow corn growth to resume.
If the soil is able to dry out, some of the potential yield will be restored if developing ears have not been compromised too badly, according to Emerson Nafziger, University of Illinois Extension corn specialist.
He says plants standing in water suffer from a lack of oxygen in the roots.
“Applying foliar forms of nitrogen or dry forms such as urea will not do much good until the water goes away and the roots start to take up oxygen,” he writes in the June University of Illinois Integrated Pest Management newsletter.
“Roots do more than just take up nutrients; they produce plant hormones, they grow into the soil to reach more nutrients, and they anchor the plant,” he says. “They do none of these things well when they are sitting in saturated soils unable to take up oxygen. In addition, plant roots release carbon dioxide, which builds up in saturated soils and can poison the roots.”
Nafziger recommends applying nitrogen to corn in low, wet areas only after the water is gone and plants start to green up, which indicates they are getting some oxygen.
John Sawyer, Extension corn agronomist at Iowa State University (ISU), agrees.
In the June 2010 ISU newsletter, he writes, “If soils are dry enough and the corn is short enough, then injection of anhydrous ammonia would top the list of best options. Next would come urea-ammonium nitrate solution surface dribbled between corn rows, and then broadcast urea. Broadcast UAN solution should be avoided on corn larger than the V7 growth stage.”
With the late-season onset of heavy rainfall, planting or replanting corn and soybeans is not necessarily a feasible option at this point. Farmers unable to plant or replant will want to start exploring their crop insurance options, says George Patrick, Purdue University agricultural economist.
"In some instances, farmers may not have been able to plant their original crop and in other instances farmers may have lost crops due to flooding," Patrick writes in the June 24 issue of Ag Answers. "If producers have followed good farming practices, they may be eligible for different crop insurance benefits---depending on individual circumstances and the type of insurance they have."
A compilation of crop-related flood information is available on Purdue University's "Chat 'n Chew Café" Web site at http://www.agry.purdue.edu/ext/corn/cafe/flood/index.html.