Madison, Wisconsin
October 4, 2006
In an ongoing bid to grow more
corn, farmers in the U.S. Corn Belt are planting seeds much
earlier today than they did 30 years ago, a new study has found.
Poring over three decades of agricultural records, Christopher
Kucharik, an associate scientist at the
University of Wisconsin-Madison,
discovered that farmers in 12 U.S. states now put corn in the
ground around two weeks earlier than they did during the late
1970s. His findings appear in the current issue of the Agronomy
Journal.
Earlier plantings-which mean longer growing seasons-have likely
contributed to the increasing corn yields of recent decades. But
Kucharik, a terrestrial ecologist at the UW-Madison's Center for
Sustainability and the Global Environment, warns the trend can
only continue for so long.
"Earlier plantings really can't continue forever because
ultimately, farmers will have to contend with wintertime
conditions and frozen soils," says Kucharik. "Several decades
from now we might see an unexpected drop in annual yield
increases when this trend plateaus, which could then increase
the threat to our food supply."
The Corn Belt is a major agricultural region of the U.S.
Midwest, where corn is a dominant crop. Centered in Iowa and
Illinois, the belt extends into Wisconsin, Michigan, Minnesota,
South Dakota, Nebraska, Kansas, Missouri, Indiana, Ohio and
Kentucky.
Kucharik had initially set out to explore the wider influence of
climate change on agricultural yields. But as he began to work
with census data maintained by the U.S. Department of
Agriculture, he accidentally noticed that over the decades,
farmers have been planting most of their corn crops earlier and
earlier in the year.
At first, he speculated that the pattern was simply a result of
earlier springtime temperatures brought on by global warming.
But on probing the last 30 years of the climate record, Kucharik
found little proof that warmer weather motivated the early
plantings.
"There is very weak or little to no correlation with springtime
temperatures over the majority of the Corn Belt and these
[earlier] planting dates," Kucharik says. Rather, other factors-
- such as improved land management practices and advances in
biotechnology - have been far more instrumental in the decision
to sow seeds earlier from year to year.
Farmers now have access to new types of seeds, for instance,
that are engineered so that plants are more resistant to the
colder soils of early spring. Another technologically enhanced
corn seed comes with a polymer coating that only switches "on"
when the soil reaches temperatures suitable for seed
germination. As technology has continued to revolutionize
agricultural methods, farmers have been increasingly confident
to put seeds in the ground as soon as they possibly can.
But Kucharik says they should be careful, because nature's
seasonal clock can only be manipulated so much. "If you start to
shift a plant's development too early, it may start to get out
of synch with the seasonal climate it is accustomed to," he
says.
While earlier corn plantings have helped crops grow more
plentiful over the years, Kucharik hopes the agricultural
community will take note of the continuing trend so that future
crop yields don't suddenly fall under the mark. |