Article ID Journal Published Year Pages File Type
5758664 Geoderma Regional 2017 29 Pages PDF
Abstract
Using a static chamber-gas chromatography technique, we simultaneously measured the emissions of N2O and CH4 from paddy soils under three cropping systems (rice-fallow (RF), rice-wheat (RW) and maize-wheat (MW)) with three nitrogen (N) levels (N0, no N; Nopt, optimized N fertilization; and Ncon, conventional N fertilization) in a two-year field experiment in southwest China. Annual mean global warming potential (GWP) of CH4 and N2O was lowest (1775 to 2288 kg CO2-eq ha− 1) in the RW system, medium in MW system (1915 to 6186 kg CO2-eq ha− 1) and highest in RF system (7324 to 8112 kg CO2-eq ha− 1). N2O emissions in N treatments accounted for approximately 90% of the GWP in MW system, and up to 40% of the GWP in RW system, and < 8% of the GWP in RF system. The ranking of the annual mean yield-scaled GWP of CH4 and N2O was RW system (0.22-0.24 kg CO2-eq kg− 1 grain) < MW system (0.36-0.96 kg CO2-eq kg− 1 grain) < RF system (1.04-1.36 kg CO2-eq kg− 1 grain). In the present study, the average N2O emission factor (EFd) was higher in WM system (Nopt: 1.82%, Ncon: 2.27%) than that in RW system (Nopt: 0.36%, Ncon: 0.55%) and in RF system (Nopt: 0.23%, Ncon: 0.37%). Given the comparable area- and yield-scaled GWP between the Nopt and Ncon treatments for RW and RF systems, the Nopt treatment that reduced local farmers' N fertilizer application rate by 33-40% maintained crop yields and decreased N2O emission and GWP of N2O plus CH4 in the subtropical rotation systems of southeast China.
Related Topics
Physical Sciences and Engineering Earth and Planetary Sciences Earth-Surface Processes
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