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Published on: December 16, 2022
Soil degassing during watering: An overlooked soil N2O emission process
Junzeng Xu1, Qi Wei1, Shihong Yang1
1State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing, 210098, China; College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing, 210098, China.
Abstract:
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.
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