Clues on Corn Yields, Weather Conditions and Climate Patterns
By Ann Perry
June 3, 2009
New mathematical models developed by
Agricultural Research Service (ARS)
scientists and colleagues could eventually help farmers use climate patterns to
predict corn yields. Farmers could use this information, which indicates yield
cycles of about two years, to adjust their production practices. For instance,
crops grown in low-yield years may require less fertilizer.
These adjustments, in turn, could reduce the flow of excess nitrate
from crop fertilizers into the surrounding watershed, which may help control
hypoxia downstream in the Gulf of Mexico. Corn yield variability affects
nitrate loss because small changes in corn yield may have greater effects on
nitrate loss in fields with subsurface tile drainage systems.
Malone works at the ARS
Soil Tilth Laboratory in Ames, Iowa. He and other colleagues in ARS and at
Penn State gathered more than 50 years of
data on corn production from six high-yield corn-producing counties in Iowa to
see if they could identify key correlations among yield, weather conditions and
Malone’s modeling results indicated that high surface radiation
and low temperature early in the growing season often produce high yields when
followed by sufficient rainfall later in the growing season. This model
accounted for 89 percent of the variation in annual corn yields.
Changes in these weather variables are often associated with long-term
climate trends. So the team used established climate indices derived from the
large-scale flow of high- and low-pressure air masses and equatorial
stratospheric winds to develop models that accounted for the variability in
corn yields. This model detected an average difference between high- and
low-yielding years of 19 percent and identified an approximate two-year cycle
between high- and low-yielding years.
Malone’s research helps explain the combined effect of several
long-term climate trends on long-term U.S. corn yields. In addition, these
results provide information about how the annual variation in ground-level
solar radiation during the growing season affects long-term corn yield in the
This research was published in the journal
and Forest Meteorology.
ARS is the principal intramural scientific research agency of the
U.S. Department of Agriculture.