Improving hydrological modeling to close the gap between elevated CO₂ concentration and crop response: Implications...

Area of Science:

• Agricultural Science
• Environmental Science
• Hydrology

Background:

• Rising atmospheric carbon dioxide concentrations ([CO2]) influence crop physiology, affecting stomatal conductance (gs) and leaf area index (LAI).
• These changes impact crop water consumption and the hydrological cycle, necessitating quantification under elevated [CO2].

Purpose of the Study:

• To investigate the effects of elevated [CO2] on grain maize water consumption, yield, and water/soil losses in the Upper Mississippi River Basin (UMRB).
• To develop and apply a SWAT-g_s-LAI model integrating nonlinear gs-CO2 and LAI-CO2 relationships.

Main Methods:

• Developed a SWAT-g_s-LAI model incorporating nonlinear gs-CO2 and LAI-CO2 relationships.
• Simulated responses of maize yield, water consumption, and water/soil losses under historical and future elevated [CO2] scenarios in the UMRB.

Main Results:

• Elevated [CO2] (495-825 ppm) increased maize yield and decreased water consumption during the historical period (1985-2014).
• Elevated [CO2] promoted surface runoff but suppressed sediment loss due to increased LAI and enhanced surface cover.
• Future climate change, rather than solely elevated [CO2], is projected to increase maize water consumption and yield across UMRB under various SSP scenarios, with increased surface runoff and sediment loss.

Conclusions:

• Physically-based models are crucial for accurately predicting crop growth and hydrological responses under elevated [CO2].
• The SWAT-g_s-LAI model provides a reliable tool for assessing climate change impacts on agricultural and hydrological systems.