Download Climate Projections and Impacts on Soybean Production Jerry L

Climate Projections and Impacts on Soybean Production
Jerry L. Hatfield and Dennis B. Egli
Supervisory Plant Physiologist and Laboratory Director, USDA-ARS National Laboratory for Agriculture
and the Environment, Ames, Iowa ([email protected]); and Professor, Department of
Agronomy, University of Kentucky, Lexington, Kentucky
Soybean production over the United States has continued to increase in both area and total
grain production. Projections of future climate change will increase the variability in production among
years and increases in temperature in the southern United States may cause a reduction in area. To
fully appreciate and understand the complexity of the interactions between climate and soybean
production we have to combine the projections of temperature and precipitation change with the
growth and yield of soybean.
Projections of temperature increase over the next 30-50 years range from 0.5 to 1.0 C with a
greater increase in the southern US compared to the Midwest. Across all of these areas there is a
projection for a shift in the seasonality of precipitation with greater precipitation in the spring and
reduced amounts in the summer and coupled with more intense and less frequent rain events. The
increase in temperature will create an environment in which the soybean plant is exposed to
temperatures which will cause an increase in the growth rate and increase the rate of crop water use
throughout the growing season. This will be more evident in the southeastern United States where the
increase in temperature will exceed the optimum temperatures compared to the upper Midwest where
temperature increases will create an environment more closely aligned with the optimum
temperatures. These scenarios create an overall environment where soybean yields in the southern
United States will decrease and become more variable among years while in the Midwest soybean yields
will continue to increase but will exhibit variation among years because of the variability in precipitation.
Shifts in the seasonality of precipitation show a trend toward more spring (April through June)
precipitation compared to summer (July through September) coupled with more intense and less
frequent events. The combination of the changes in seasonality and increased atmospheric demand
during the summer will lead to situations in which the soybean crop is exposed to water stress during
the pod and seed development stage leading to decreased yields. Soybean yields have been related to
soil water holding capacity with better soils showing higher average years and less variation from
potential yield. This variation in soybean production indicates that soil water management will be a
critical factor in adaptation strategies on soybean production and a foundation factor in developing
soybean production systems resilient to climate change.
Climate will continue to impact soybean production. The challenge will be to develop an
integrated approach which couples genetics, the environment, and management into a G x E x M
complex in order to build viable soybean production systems. These efforts offer a challenge to us but
also the potential for building a more efficient soybean production system.