Temperature sensitivity of N2O emissions from fertilized agricultural soils: Mathematical modeling in ecosys

摘要

N2O emissions have been found to be highly sensitive to soil temperature (T-s) which may cause substantial rises in emissions with rises in Ts expected in most climate change scenarios. Mathematical models used to project changes in emissions during climate change should be able to simulate the physical and biological processes by which this sensitivity is determined. We show that the large rises in N2O emissions with short-term rises in Ts (Q(10) > 5) found in controlled temperature studies can be modeled from established Arrhenius functions for rates of microbial C and N oxidation (Q(10) similar to 2) when combined with Ts effects on gaseous solubilities and diffusivities and with water effects on gaseous diffusivities, interphase gas transfer coefficients, and diffusion path lengths. Rises in N2O emissions modeled with a long-term rise in Ts during a climate warming scenario were smaller than expected from short-term rises in Ts. Nonetheless, annual N2O emissions rose by similar to 30% during three growing seasons in a cool humid maize-soybean rotation under a climate change scenario in which atmospheric CO2 concentration C-a was raised by 50%, air temperature T-a by 3 degrees C, and precipitation events by 5%. These model results indicate that climate warming may cause substantial rises in N2O emissions from fertilized agricultural fields in cool, humid climates.