One point driven home to Zierden and other scientists in the last couple of decades is how much drier the month of May has become.

“The message we’re trying to hammer home is that May in the Southeastern United States has gotten drier,” he says. “May is a critical period in the growing season when we are trying to get seed in the ground and a stand established before the onslaught of summer dryness.

“While June rain hasn’t changed that much, May rains have declined to an average of about 2 inches — half of what was expected 25 years ago.”

Scientists have gained other insights from a close study of the ENSO pattern, which, when not in a neutral phase, is expressed either as an El Niño or La Niña phase.

Warmer surface water temperatures in the Pacific are associated with the El Niño pattern and typically contribute to wetter- and cooler-than-normal winters and springs in the Southeast. Cooler water surface temperatures with the La Niña effect are typically followed by winter and spring climate patterns much warmer and drier than normal, Zierden says.

Research has demonstrated that corn and wheat yields are affected by these phases, which become more pronounced closer to the Gulf Coast.

“Curiously, when we have El Niño — rainy or stormy winters —we actually get reduced corn yields across the Southeast, while the warmer, drier winters and springs associated with La Niña bring higher corn yields,” Zierden says.

Climate researchers were initially stumped by these findings until follow-up discussions with Extension specialists and agents cleared up the confusion.

“We finally figured out what was happening,” Zierden says. “Given enough water, especially with irrigation, the warmer temperatures and increased sunshine early in the season — May and April (during La Niña) —get corn off to a good start.”

On the other hand, in the cloudy, rainy conditions associated with El Niño, corn starts off slowly, he says.

At Auburn University, Brenda Oritiz an Alabama Extension specialist and assistant professor in the Department of Agronomy and Soils, cautions that these connections should be studied on a county-by-county basis.

Sorting out how these patterns play out with cotton initially proved challenging. Then a series of crop simulation models developed by researchers at the University of Florida and the University of Georgia shed some much-needed light on the problem, Zierden says.

The models revealed that early planting dates under the neutral phase — which happen to be the current and forecasted ENSO phase for spring and early summer 2013 — decrease the chances for low yields and also enhance the prospects for high yields. On the other hand, late planting dates produce exactly the opposite: an increased chance of low yields and reduced opportunities for high yields.

 “Putting all this together — and with the understanding that I’m neither an Extension specialist nor an agronomist — I think it demonstrates that planting early, getting a stand established and taking advantage of existing soil moisture from winter and early spring rainfall better equips the crop to withstand the dry periods that follow in May and June,” Zierden says.

Ortiz has also been at the forefront of efforts to acquaint Alabama producers with the merits of climate forecasting. While underscoring that these techniques are no panacea, they provide farmers with an added layer of protection, she says.

“Farmers have to understand that when we speak of climate forecasting, we’re talking about probability, not an ironclad guarantee,” she says.

“On the other hand, when you think back to the serious drought from 1953 to 1954 when farmers had little information and few, if any, tools, we’re better prepared than we’ve ever been.”