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Climate change
studies that
assess the full range of interactions among temperature, radiation,
precipitation and land use can better aid humans to prepare for extreme
shifts
in weather patterns, the scientists report in a special issue of the
journal Global
and Planetary Change. Climate change
impact models
often don't consider whether shifting weather will allow for
sustainable
agriculture, said Dev Niyogi, corresponding author of the journal
article and
Purdue agronomy, and earth and atmospheric sciences assistant
professor. Niyogi's team looked
at weather
factor interactions and their impact on two different crop plants by
using data
for weather and field conditions that occurred in a year considered
normal for
the test area. By designing a study that changed a number of variables
simultaneously, the researchers found that the complex interactions of
precipitation with other weather factors had the most impact on the
overall
health of crops and regional agricultural productivity. They concluded
that
lack of precipitation will have the most dramatic effect on living
conditions
in the future. "Even though the
question
often posed involves the impact of global warming on agriculture, the
real
question ought to be 'What is the effect of drought?'," said Niyogi,
who
also is Plants that are
stressed due to
lack of water threaten the future and sustainability of agricultural
crops.
Complicating the climate impact on crops is that growing demand for
agricultural products also can affect weather patterns, Niyogi said. "One basic issue we
still
need to understand is that population growth is a major driver for
climate
change," he said. "When we have more humans, we'll use more energy
and use more landmass." Land-use shifts can
impact temperature
and overall climate, as already evident in urban temperatures compared
with
rural temperatures, Niyogi said. This is a result of weather variable
interactions and can be demonstrated in Niyogi's research, which
involves
interaction of radiation, temperature and precipitation changes. "When temperature
rises, you
see more evaporation," Niyogi said. "More evaporation could lead to
more clouds. More clouds might lead to changes in radiation. Changes in
radiation can impact the amount of convection — the heating
of the environment
by the rising air. This leads to formation of rain, which can change
the soil
moisture and temperature again." Niyogi and his
collaborators
tried to reproduce how temperature, radiation and precipitation
interact and
how those interactions impact two types of crops: corn and soybeans.
The
scientists used data from an area in Niyogi's team ran 25
different
climate scenarios on each of the crops in order to assess the effect of
various
interactions of radiation, temperature and precipitation on corn and
soybeans. The scientists found
that
radiation could be beneficial in a medium range because it increases
the
plants' photosynthesis, the process by which plants take energy from
the sun to
spur growth. However, too much radiation or too little radiation both
lowered
crop yield because they changed the efficiency of photosynthesis. Radiation also
affected how much
water evaporated from the plants. This changed plants' water usage and
had an
impact on crop yield. While temperature
changes had a
more direct effect on crops than did radiation, the researchers found
that the
impact was dependent on when temperature changes occurred and how long
they
lasted. More refined studies
need to be
done on individual regions of the world to develop resource management
and
drought plans, according to Niyogi and his research team. "Right now, we would
be in
shock if we had a real drought in As the population
increases,
demand for agriculture products increases and regional climates change,
management of resources will become even more important. "As the region and
the world
brace for the necessity of higher crop yields, the role of weather
becomes more
critical and needs to be taken into account seriously in developing
agronomic
plans," Niyogi said. The other
researchers involved
with this study were lead author Roberto Mera, a graduate student in
Niyogi's
lab; and North Carolina State University researchers Fredrick Semazzi,
professor of marine, earth and atmospheric sciences and mathematics;
Gregory
Buol, crop science research scientist; and Gail Wilkerson, professor of
crop
sciences. NASA, the National
Science
Foundation and the U.S. Department of Agriculture provided funding for
this
research. ## Contact:
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