Effects of warming and reduced precipitation on soil respiration and N2O fluxes from winter wheat-soybean cropping systems

The effects of experimental warming and reduced precipitation on soil respiration (SR) and nitrous oxide (N2O) fluxes have been of increasing concern but are poorly understood, particularly in agroecosystems. A plot experiment was conducted in a winter wheat-soybean cropping system over the 2014-2016 growing seasons in southeast China. A full two factorial design was used that included treatments with crop canopy temperature increased by similar to 2 degrees C (T), 30% reduction in precipitation (P), the combined soil warming and precipitation reduction (TP), and the control under ambient conditions (C). Seasonal patterns of SR and N2O fluxes did not significantly differ among the treatments. Over the 2014-2016 period, soil warming significantly increased SR rates and N2O emissions. Compared with the control, the reduced precipitation treatment significantly decreased SR rates, but its effects on N2O fluxes were not pronounced. There was no interactive effect of warming and reduced precipitation on SR rates and N2O fluxes. Overall, our results suggest that climate warming would lead to more soil CO2 and N2O emissions, potential but poorly understood changes in precipitation may thus control soil greenhouse gas emissions in a warming world.