Does drought stress eliminate the benefit of elevated CO_{2,/sub> on soybean yield? Using an improved model to link crop and soil water relations}

Authors

Wenguang Sun, USDA-ARS, University of Nebraska-Lincoln
David Fleisher, USDA-ARS
Dennis Timlin, USDA-ARS
Chittaranjan Ray, University of Nebraska - LincolnFollow
Zhuangji Wang, USDA-ARS
Sahila Beegum, University of Nebraska-Lincoln, USDA-ARSFollow
Vangimalla Reddy, USDA-ARS

Date of this Version

10-23-2023

Document Type

Article

Citation

Agricultural and Forest Meteorology 343 (2023) 109747. https://doi.org/10.1016/j.agrformet.2023.109747

Comments

U.S. government works are not subject to copyright.

Abstract

Crop simulation models are indispensable tools that facilitate studies to assess climate impacts and adaptation responses, but have not been adequately tested in terms of accurately predicting crop growth and water stress responses to high carbon dioxide concentrations [CO₂]. The soybean model, GLYCIM, previously modified with a coupled leaf-level gas exchange – energy balance model, was integrated with a two-dimensional convectivediffusive root growth module which linked soil and leaf water potentials with the regulation of stomatal conductance. We evaluated the accuracy of this modified GLYCIM using experimental data from a Free-Air CO₂ Enrichment (FACE) site, SoyFACE, and used the calibrated model to quantify current and projected elevated CO₂ effects on soybean yields in the United States (US) Midwest. The model accurately matched SoyFACE observed data including canopy temperature (RMSE, 2.26 -2.4 ^◦C; IA, 0.89-0.90), photosynthesis rate (RMSE, 6.33 -12.88 μmol m^-2 s^-1; IA, 0.82-0.92), seasonal LAI (RMSE, 0.96 -1.08 cm² cm^-2; IA, 0.91-0.93), biomass (RMSE, 2.06 -2.34 Mg ha^-1; IA, 0.87-0.90), soil water contents (RMSE, 5.42 -7.82 %; IA, 0.80-0.85) and root length (RMSE, 2.12 -5.64 m plant^-1; IA, 0.70-0.86). GLYCIM also reproduced the observed declining response of yield to CO₂ fertilization with increasing drought. Using an ensemble of five climate model projections, GLYCIM showed that the CO₂ fertilization effect on yield was highest in northern counties and declined in southern and the western counties by late 21st century in response to increased drought characterized by higher daily maximum temperature and decreased rainfall. This study highlights the need to continue to test and improve crop models and use geospatially referenced adaptive strategies to capitalize the benefits from elevated [CO₂] to better counteract increasing drought.