Replicating Climate Change to Forecast its
Effects By Dennis O'Brien December 16, 2009
Service (ARS) scientists are replicating the effects of climate change to
see what the future holds for soybeans, wheat and the soils where they
Soybeans, wheat, and a number of other crops grow more when carbon
dioxide levels are elevated because the increased carbon is thought to give the
plants more "food." But those same plants are damaged and stunted by elevated
levels of ozone, a ground-level gas created when sunlight heats up automotive
and industrial pollutants. Levels of both gases are expected to rise as the
Fiscus, researchers at the
Plant Science Research Unit in Raleigh, N.C., are using 16 open-top
chambers to expose wheat and soybeans to the levels of carbon dioxide and ozone
that may be reached by 2050. By that time, carbon dioxide levels may be about
1.5 times greater than the current 380 parts per million, and daytime ozone
levels in the summer, now at about 50 to 55 parts per billion, may rise 20
percent. The goal of the study is to assess the effects of climate change on
growth rates, crop yields and soil chemistry.
The researchers have four sets of four chambers: a set with elevated
ozone, another with elevated carbon dioxide, a set with both gases elevated,
and four "control" chambers without elevated levels of either gas. They also
are leaving plant stems, empty pods and dead leaves in the chambers, and are
not plowing the soil to mimic conditions found in no-till farming. In this type
of cropping system, elevated carbon dioxide levels may increase soil
decomposition and slow down the accumulation of carbon in the soil.
Preliminary results show just slightly higher levels of soil carbon in
chambers with elevated carbon dioxide and in chambers with elevated levels of
both carbon dioxide and ozone, but not in chambers with elevated ozone alone.
Elevating carbon dioxide also reduced flour protein levels in wheat by 7 to 11
percent, but soybean protein concentrations were maintained because of
soybeans' ability to acquire nitrogen from the air.
This research supports the
U.S. Department of
Agriculture priority of responding to climate change.
more about the research in the November-December 2009 issue of
Agricultural Research magazine
ARS is USDA's principal intramural scientific research agency.