FOCUS ON AGRICULTURE: Pacific water temperatures affect Missouri corn, soybeans

Posted: Jul. 10, 2014 9:28 am Updated: Aug. 7, 2014 10:15 am

Water temperatures in the tropical Pacific can end up having a lot to do with the price of corn in Missouri, thanks to El Nino and La Nina, according to a University of Missouri atmospheric scientist.

In the American Midwest, the transition to El Nino -- the recurring period of warmer than normal waters in the equatorial Pacific -- tends to bring milder summers with more regular rainfall, said Tony Lupo, professor and chair of the MU Department of Soil, Environmental and Atmospheric Sciences.

By contrast, the transition to La Nina -- a period of cooling waters in the eastern equatorial Pacific -- tends to bring the Midwest hot summers and irregular rainfall. There also are "neutral" periods of normal water temperatures in the cycle called the El Nino-Southern Oscillation.

Atmospheric scientists long have thought that El Nino and La Nina usually don't have a major direct effect on crop yields in the United States, except in extreme cases such as the 2012 drought. El Nino is at peak strength in winter and weak in the summer, when U.S. crops are growing. In addition, yields per acre have generally gone up from year to year as technology advanced. So weather variations from ENSO, many assumed, were unlikely to make much difference.

However, a close look at historical data for crop yields in Missouri suggests otherwise, Lupo said.

One of his students, Jessica Donovan, analyzed harvest records for corn, soybean and wheat back to 1920. Controlling for the effects of technology on yields, Donovan found a definite correlation between El Nino/La Nina and Missouri's corn and soybean yields.

"We're finding that when it's transitioning into El Nino years, the corn yields are higher," Donovan said. "Then when it's transitioning into La Nina, the corn crops don't have as high yields."

The same is true of soybeans, though the effect is not as strong as with corn. Soybean plants have deeper roots than corn, and are less vulnerable to variations in temperature and precipitation.

"The research we're doing --trying to link El Nino-La Nina weather cycles to corn and soybean yields would give some ability to anticipate these things two to four seasons in advance," Lupo said.

The catch is that El Nino and La Nina don't follow a set schedule, and they can vary in duration and strength.

But Lupo said that growing understanding of ENSO and other weather cycles, combined with increasingly sophisticated computer models, is dramatically improving the reliability of long-range weather forecasting.

CSP renewals

Producers with expiring U.S. Department of Agriculture Conservation Stewardship Program contracts have from July 11 until Sept. 12 to renew and add conservation activities and fine-tune their conservation plans.

About 20,000 CSP contracts are reaching the end of their initial five-year contract period and may be renewed for an additional five years when participants agree to take additional conservation actions.

The program provides opportunities for farmers and ranchers who are already established conservation stewards, helping them improve water quality and quantity, soil health and wildlife habitat.

More than 58 million acres were enrolled in the program -- an area the size of Indiana and Wisconsin combined -- after the program launched in 2009.

More information about technical and financial assistance available through CSP is available from local USDA service centers and online at, the conservation stewardship webpage.

Compiled by Herald-Whig Staff Writer Deborah Gertz Husar.

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