Pulse diffusive nitrous oxide (N2O) emission following water application is well documented, whereas N2O emission caused by soil water-air displacement during the watering process (termed as soil degassing) has been largely overlooked. Watering-induced N2O emissions from ten different soils in China were quantified, and found to range from 74.4 ± 6.7 to 678.1 ± 36.6 μg N2O m-2 h-1 in surface watered (SW) soils, and from 45.6 ± 4.4 to 358.1 ± 23.6 μg N2O m-2 h-1 in subsurface watered (SUW) soils. These N2O fluxes were much larger than the diffusive N2O flux from the same soil either under dry (7.9%-9.6% water filled pore space, WFPS) or wet (85.1%-93.6% WFPS) conditions. The watering process (the water infiltration process upon irrigation/rainfall or the process of shallow groundwater uplifting) resulted in massive N2O emissions.
Keywords: Nitrous oxide; Rainfall; Shallow groundwater lifting; Soil degassing; Watering.
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