Quantifying annual N₂O emission fluxes from grazed grassland under a range of inorganic fertiliser nitrogen inputs [Erratum: 2010 Aug. 15, v. 138, no. 3-4, p. 356]

The objective of the present study was to measure emissions of N₂O from fertilized grazed grassland that can be used to add valuable information to the limited existing data on N₂O fluxes from grazed grassland and aid the development of new country-specific EFs for direct emissions from soils in the UK. This was done by evaluating the effect on N₂O emissions of inorganic fertiliser N applied to grazed grassland soils over the range of N inputs 0-350kgha⁻¹. Nitrous oxide fluxes were measured using closed static chambers at 3 sites in England and Wales over a two-year period. Cumulative fluxes were calculated and the total emission regressed against applied inorganic fertiliser N in order to estimate the emission factor for N₂O emissions from soils. The data showed that, the emission factor for N₂O from inorganic fertiliser applied to grazed grassland soils in the UK differs from the IPCC default value of 1.25%. A nonlinear response of N₂O emissions to fertiliser N application rates was observed. Annual emissions of N₂O were estimated from a modelled function fitted to the measured data and after subtraction of the background flux resulted in emissions of 0.5 and 3.9kgN₂O-Nha⁻¹ yr⁻¹ for an application of 100kg N for three locations in the UK, one in the East and the other two in the West of the UK (after combining the data from two sites), respectively.