Effect of climate and atmospheric change on soybean water stress: a study of Iowa

The anthropogenic increase in radiatively active gases in the atmosphere has been well documented, and there is evidence that suggests an impact of this increase on the earth's climate. Agriculture is vulnerable to climatic changes, and estimating the likely response to such changes is critical. The current work examines the impact of climate change on water stress during the critical periods of soybean [Glycine max (L.) merr.] reproductive development. This is a time of particular interest because soybeans at these stages are believed to be particularly vulnerable to water stress. Climate scenarios from three General Circulation Models (GCMs) were adapted to produce daily, simulated weather datasets for the nine climate centroids (in the state of Iowa). The GCMs were the Goddard Institute for Space Studies (GISS), Geophysical Fluid Dynamics Laboratory, and United Kingdom Meteorological Office (UKMO) models. Soil association datasets were created for two counties within each of the centroids. Simulations were performed for each county and each GCM at climate samples corresponding to climate change at 350, 450, 550, and 650 ppm atmospheric [CO2], using the mechanistic soybean physiology model GLYCIM. The model provided data on the probability and magnitude of water stress during the reproductive development stages of soybean crops. The results indicated that water stress was most severe during the R2-R5 stages under the UKMO scenarios, and became progressively more severe as climate change progressed. Although stress occurred under the GISS and GFDL scenarios, it did not increase with changing climate. (C) 2000 Elsevier Science B.V. All rights reserved.