Trend-Line Yields: '12 Drought Could Be Better Than '88 Drought

Emerson Nafziger examines drought loss based on a percentage of expected trend-line yields. Viewed through that lens, 1988 was much worse than this year looks to be.

Published on: Aug 20, 2012

Many producers are wondering whether the development of genetically modified hybrids and the improvement in hybrid yield potential and stress tolerance has made the corn crop more "drought-proof" now than it was in 1988.

Emerson Nafziger, a professor of crop sciences at the University of Illinois, notes that as the drought worsened over the past weeks, he was regularly asked how this year's yields are likely to be affected and how they will compare with the yields after the 1988 drought.

On August 10, the U.S. Department of Agriculture's National Agricultural Statistics Service projected that the 2012 Illinois corn yield would be 116 bushels per acre, an estimate that could still change. Projected yields range from 143 bushels in the Northwest Crop Reporting District to 80 bushels in the East Southeast CRD.

Trend-Line Yields: 12 Drought Could Be Better Than 88 Drought
Trend-Line Yields: '12 Drought Could Be Better Than '88 Drought

In 1988, the average Illinois corn yield was 73 bushels per acre, and yields ranged from 87 bushels in the southeast (actually higher than the estimate of 86 bushels for this year in that CRD) to only 63 bushels in the northwest.

"The pattern of dryness in Illinois was very different in the two years, with southern Illinois relatively better than northern Illinois in 1988," Nafziger adds. "In 2012, dryness was more evenly distributed, which led to a closer correlation between soil water-holding capacity and yields."

To look at how much yield was lost to drought each year, Nafziger projected trend line yields for each of the drought years based on yields over the 30 previous years. The expected yield (trend line) for 1988 was 129 bushels per acre, and the actual yield that year was 73, so the loss was 56 bushels per acre. In 2012, the expected yield was 173 bushels per acre, and the estimated yield is 116, so the projected loss is 57 bushels per acre.