"The small percentage of the crop planted late this year
suggests that the U.S. average yield will be higher than if a
normal percentage had been planted late, but the level of yields
is still to be determined," said Darrel Good.
Good said that
the small percentage of the crop planted late this year and the
early conditions of the crop point to the potential for an
above-trend yield in 2012, but the most important part of the
season is just beginning.
"The corn market will continue to follow weather developments
and crop condition ratings in order to refine yield
expectations," he said. "At this juncture, two important
developments may be required in order to maintain high yield
expectations. The first is some convincing evidence that the
relatively long period (eight months or so) of above-average
temperatures is giving way to normal or below-normal
temperatures. The second is for soil moisture deficits in
important areas of the central, eastern and southern Corn Belt
to be eliminated."
Good said a second piece of early information relative to
corn yield potential is the crop condition rating provided in
the USDA's weekly Crop Progress report. He said there has
historically been a positive relationship between the percentage
of the crop rated good or excellent at the end of the season and
the U.S. average yield relative to trend.
"Early crop condition ratings are suggestive of yield
potential, but ratings can, and do, change substantially by the
end of the season," Good said. "The first crop condition rating
of the season this year showed that 77 percent of the crop was
in good or excellent condition as of May 20.
"Since 1986, an average of only 66 percent of the crop was
rated in good or excellent condition in the first report of the
season," Good said. "There were only six other years when the
initial ratings showed 75 percent or more of the crop in good or
excellent condition. The rating at the end of the season was
higher than the initial rating in two of those years (1987 and
1994), and the U.S. average yield was well above trend in both
years. The rating at the end of the season was below the initial
rating in four of the six years. The average yield was near
trend value in three of those years when the final ratings
showed 60 to 69 percent of the crop in good or excellent
condition. The U.S. average yield was well below trend in 1991,
when the final rating showed 53 percent in good or excellent
[to top of second column]
What do we know about yield potential as the summer growing
The most important development to date, Good said, is the
timely planting of the crop. There is a relatively wide window
of planting dates for maximum corn yield potential, with yield
penalties associated with late planting.
"Since corn planting dates vary considerably by geographic
area, corn planting occurs over a period of several weeks, and
has been occurring earlier over time, there may be a number of
ways to characterize timeliness of planting on a national
basis," Good said.
"For the period beginning in 1986, we defined late planting as the
percentage of the crop planted after May 20 in the major
corn-producing states that are included in the USDA's Crop Progress
report," Good said. "This year, only 4 percent of the corn crop in
the 18 major corn-producing states was planted after May 20. That is
the smallest percentage of the crop planted late during the 27-year
period since 1986."
Good reported that, on average, 18 percent of the crop was
planted after May 20 from 1986 through 2011. There were nine other
years when less than 10 percent of the crop was planted after May
20. In those nine years, the U.S. average yield was within two
bushels of the trend yield in five years.
Good said large deviations from trend yield occurred in the early
planted years of 1987 (up 8 bushels), 1988 (down 29 bushels) and
1992 (up 16.8 bushels).
"These yield results are not especially informative for
developing expectations about the average yield in 2012," Good said.
"With all else being equal, the planting date may be important for
yield potential, but summer weather conditions ultimately determine
the level of yields."
In addition to yield prospects, Good said the expected size of
the 2012 crop will be affected by the magnitude of planted and
harvested acreage. The USDA will provide survey-based estimates in
the Acreage report to be released on June 29. New-crop corn prices
are expected to remain under pressure as long as large crop
[Text from file received
from the University
of Illinois College of Agricultural, Consumer and Environmental