Iowa Public Television


Heat and No Rain Take a Toll on the Cornbelt

posted on July 6, 2012

Heat and No Rain Take a Toll on the Cornbelt

Large sections of the country saw an expansion and intensification of dryness this week, with only southern Texas reporting some moisture. Unfortunately, where rain did fall, it was not enough to make up for the blistering heat that covered the Midwest, reaching the central and southern Atlantic Coast by week’s end.

The drought continued to take a significant toll on some of the nation’s crops, pastures, and rangelands. U.S. corn prices have soared 17 percent in recent weeks as day after day of hot dry weather persists in the heart of the Midwest. 

This week’s USDA Crop Progress report showed a deterioration in the average condition of the corn crop, with the “good-to-excellent" combined category declining to 48 percent, versus 56 percent one week ago -- which was considered the lowest category rating since the drought of 1988. That year, U.S. farmers produced only 4.9 billion bushels of corn, 33 percent below the government's initial May estimate of 7.3 billion bushels.

Currently, USDA is forecasting a record U.S. corn crop of 14.8 billion bushels for 2012. That estimate came on June 12, before the latest drought pressures.

Among the Midwest states hardest hit by drought are Illinois and Indiana, which rank second and fifth in corn output. In each state, less than 40 percent of the young corn crop is now rated in good to excellent condition. Meanwhile, crop conditions in other key areas of the nation’s mid-section are rated much better including top producer Iowa. Minnesota’s corn crop is fairing the best at 82 percent in that category. And 56 percent of the corn crop in Nebraska is rated in good to excellent condition. 

The timing of corn silking and pollen shedding is critical to fertilization. Many of the states showing poor corn crop conditions are also showing early silking.

Roger Elmore, Iowa State University: “It’s speeding up the pollen drop or shed which is the male part of the flower and it’s slowing down silking, the female part of the flower. So, what’s happening is we may be missing that nick. For instance, if this is pollination period, the pollen shed, this is silking. Ideally, they overlap. But with stress, high temperature and drought combined, those two things start separating. And when they separate at this point, there are no kernels on the ear.”

Roger Elmore, a professor of agronomy at Iowa State University, says even with adequate soil moisture, extreme heat for more than four days in a row can lead to a 1 percent yield loss. On the fifth day there is an additional 2 percent loss; the sixth day an additional 4 percent loss.

Roger Elmore, Iowa State University: “We have almost a perfect storm here, and that’s in a negative context, because we have corn at the most critical period of time in terms of silking and pollinating. We have very high temperatures. We have very little probability of rainfall and we have dry soils. Those three things combined in this quote, unquote perfect storm, are not positive for yields.”

Tags: corn cornbelt crops drought dry hot midwest USDA