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Climatologist Says Heat Hurt Worse than Drought

Climatologist Says Heat Hurt Worse than Drought
Heat at wrong time took a bigger toll on corn.

One of the nation's leading climatologists says drought contributed to corn loss but heat was a bigger factor. Elwynn Taylor, climatologist at Iowa State University, spoke before a crowd of farmers crammed into the DuPont Pioneer exhibit at the recent Farm Progress Show to hear his assessment of current weather conditions, and what he thought the future might hold.

Temperatures were extreme this year in many areas of the Corn Belt when corn reached its critical pollination period, Taylor says. Corn could handle drought or heat, but not both. And the biggest factor this year was actually heat in many cases, he believes.

HEAT FACTOR: Elwynn Taylor says the extreme heat was the overriding factor that hurt corn yields in many fields.

Taylor has studied the effects of increasing heat on water use in corn. His data shows that at 75 degrees, corn uses about one inch of water per week during mid-season. Raise the temperature to 85 degrees and it needs two inches of water per week. Turn up the heat to 95 degrees, another 10 degree increase, and the water requirement doubles again. Now corn needs four inches of water per week.

Indiana had a string of 90 degree plus days over most of the state in late June through July. At Indianapolis nine of those days even topped 100 degrees. Moisture in the form of rain was minimal, meaning water used up or lost through transpiration was not replaced.

“At increasing temperatures, the crop could have run short of water even with normal rainfall,” Taylor says.

He has also looked at potential yield losses if temperatures reach a high level during the critical period for corn and there is no relief. By the 3rd day of 94 degree heat, yield loss is at 1%. Add a fourth day and losses are at 2%. Losses continue to increase as more days are added in a row.

It doesn't happen every year, Taylor says, but it certainly happened this year.

TAGS: Farm Shows
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