State climatologists forecast above-trend corn yields

Corn and soybeans are looking good so far in Iowa and Minnesota.   

For the week ending July 25, 89 percent of Minnesota corn was rated in good to excellent condition by USDA's National Agricultural Statistics Service. In Iowa, 70 percent of corn was in the good or excellent categories. 

"Whenever the crop is more than 50 percent good to excellent, we anticipate an above-trend yield," said Elwynn Taylor, Iowa State University Extension climatologist and agronomist, referring to a 30-year trend. 

That's typical of Iowa in the last five years, he said. 

NASS rates Minnesota soybeans at 85 percent in good to excellent condition as of July 25. In Iowa, 71 percent of soybeans ranked in those categories.


 "We would expect them to be above trend yield, but the chances aren't as high because August is so important to the soybeans," said Taylor. 

University of Minnesota Extension climatologist Mark Seeley anticipates Minnesota corn and soybean yield to be at or above the trend line. 

"It certainly sounds like we've had very good environmental conditions, particularly in the context of the last five summers, 2005 to 2009," Seeley said. "Each of those five growing seasons had drought break out somewhere in the state. So far in 2010, we've avoided that. That's a significant shift for what we've experienced."

Minnesota's first two weeks of August will start out normal then get more wet than normal, Seeley said. Crop maturation and development is expected to continue to run ahead of average dates with adequate moisture.  

Both climatologists mentioned a potential downside in their states because of the current La Nina episode. La Nina is a weather condition, defined along the equator in the Pacific Ocean, that can have dramatic weather impacts in the Corn Belt.

Taylor said a similar La Nina situation happened in 1983, when Iowa saw the most serious drought in the Corn Belt since the 1950s. 

"During the last week in July in 1983, temperatures continued above normal for the following six weeks and rainfall essentially stopped," said Taylor. "Crops that were not as deeply rooted into the soil as normal because of the excess moisture in the spring almost immediately suffered from lack of water, having expended the moisture in the top several inches of the soil and not having the deep roots to tap the deep water."

Not enough data exists for climatologists to give an estimate of the likelihood that will happen again. La Nina does not mean there will be a drought.


"We know that it happened once," Taylor said. 

It is wise to be cautious and take that into account while marketing and forward marketing potential crops, he said. 

In Minnesota, Seeley said the La Nina episode could bring more severe weather such as tornadoes, hail and wind. 

"We already had over 400 reports of severe weather in Minnesota this summer and we're not even through the month of July," Seeley said last week. "...I don't see this threat, if you will, of severe weather abating in the second half of summer. If anything, I think it will continue."

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