Iowa State University Extension climatologist Elwynn Taylor is forecasting a 166 bushel per acre national average corn yield for 2014, but in the coming months that could change.
Taylor, who spoke at last week's Hawkeye Farm Show at the UNI-Dome in Cedar Falls, watches the El Nino-Southern Oscillation, which measures changes in ocean temperature off the coast of South America.
Sea surface temperatures that are warmer than normal indicate an El Nino condition that Taylor calls "the friend of the Midwest farmer." El Nino generally brings mild growing conditions with a 70 percent change of an above trend line yield. When the ocean temperatures cool, it brings a La Nina condition with harsher Midwest winters and summers. During La Nina, there is a 70 percent chance of a below-trend line yield and a stronger chance of drought. Current conditions are neutral — meaning there is a 50 percent chance of an above or below trend line yield.
But Taylor has observed signs that La Nina may be trying to establish itself.
"I hear people on the news talking about an El Nino, but I don't see the signs," Taylor said. "I keep track of the anomalies in ocean temperature off the west coast of South America, especially along the equator. It's colder now than in February and that was colder than January. That is not a good sign. This indicates it is moving toward La Nina."
Taylor won't know if a La Nina condition has established itself until around April 15.
"If it goes the way I'm suspecting and La Nina is established, my yield forecast will drop to below 160 bushels per acre which is the trend line," Taylor said.
Another signal that dry weather may be coming is an area of cold water in the Gulf of Alaska. When warm water forms there, low pressure sends growing season storms across the Yukon instead of into the United States. The last time the water was as warm as it is now was during the 1988 drought when there were no significant storms in a line from north and east of Kansas City to the East Coast.
Last year brought an amazingly wet spring which wiped out the 2012 drought, Taylor said. In July the rain quit with conditions switching to very dry. What saved the corn crop for many farmers was temperatures five degrees cooler than usual through the rest of the growing season. Illinois and states to the east all recorded record high yields. West of Illinois yields were lower than average but were saved from disaster.
If La Nina dominates in the coming weeks, there is a 70 percent chance of a 149-bushel national average corn yield and a $4.55 per bushel price on the December contract at harvest. If there is an El Nino, there is an 80 percent chance corn will be cheaper than $4.55 and a 75 percent chance with normal weather. Taylor's current forecast of 166 bushels would bring a $3.80 price on the December contract at harvest.
Taylor told farmers that they should track growing degree days, rainfall and heat stress for their farm and at other locations across the Corn Belt and compare this year to what happened in good, average and bad years.
"We are in a time when management of risk is increasingly important," Taylor said. "The profits are there for those who do."
The initial risk for the 2014 crop is that soil moisture, measured in late fall, is 40 percent of normal across Iowa.
This winter's ample snowfall will contribute to replenishing soil moisture where the snow is at least one foot deep, Taylor said.
"That provides enough insulation," he said. "The soil is a constant 55 degrees at seven feet and it works its way up melting snow from the bottom. With less snow, the ground freezes deeper and the snow melts from the top and runs off."
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