January 17, 2008

La Nina poses significant risk to 2008 corn, ISU expert

A climatologist at Iowa State University is warning that La Nina conditions are now posing a significant risk to US corn production in 2008.

Elwynn Taylor said the Southern Oscillation Index (a key measure of barometric pressure differentials between points in Australia and the mid-Pacific Ocean) reached threshold levels on Christmas Day, and La Nina, which is also characterized by shifts in wind currents and sea surface temperatures, was officially confirmed January 4.

Taylor said in a recent online crop-weather update that at this time, the combined risk is a 68-percent chance of a below-trend US corn yield.

This risk is increased by scant subsoil moisture, the 19-year drought cycle, and existence of drought in the area of South Carolina, he explained.

Several research groups see some indication that the La Nina may diminish quickly and not pose a risk to US crops. Nevertheless, it is now at the level to be considered a risk, Taylor pointed.

US corn yields averaged 151.1 bushels per acre last season, which fell about 1.5-2.0 bushels below trendline expectations.

The chance of a near-record high yield (greater than 165 bushels per acre this season) is at 15 percent, and of drought (reduced-yields, averaging below 135 bushels an acre) is 35 percent.

The climatologist explained that that the US corn belt, which is on a fairly consistent 19-year drought cycle, is now overdue for a major drought. The last occurred in 1988, slashing corn yields in central/eastern production areas of the Corn Belt by 30 percent.