Managing fertiliser nitrogen to reduce nitrous oxide emissions and emission intensities from a cultivated Cambisol in Scotland
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Emissions of nitrous oxide (N2O) were measured from an arable site in south east Scotland for twelve months during 2011–2012 using an intensive sampling strategy. This fully replicated and blocked field experiment aimed to provide accurate measurements of N2O emissions from one of the UK's principle geoclimatic zones supporting agricultural production and to produce robust N2O emission factors (EFs). Calculated EFs were compared to the IPCC's default Tier 1 EF of 1.25%, and the new value of 1%, to assess their suitability for use in locations throughout the UK. Emissions from ten treatments fertilised with either ammonium nitrate or urea at rates of 0 kgNha−1 to 200 kgN ha−1, and sownwith spring barley,were measured using the static closed chamber technique. Potential N2O mitigation options were investigated; these included the use of a nitrification inhibitor (NI), split fertiliser applications and variations in the formand quantity of fertiliser applied. Crop yieldswere measured to enable calculation of N2O emission intensities for each treatment; this is an important factor to consider when assessing N2O mitigation options due to the need to maintain crop yields. Cumulative N2O emissions varied between 1.32 kg N2O-N ha−1 and 3.82 kg N2O-N ha−1 with a mean 42% decrease in emissions associated with the use of the NI. Increases in crop yield were associatedwith increases inN fertiliser application, and the amendment of treatmentswith a NI and the use of a split fertiliser application significantly decreased crop yields by approximately 10% and 5% respectively. Annual EFs ranged between −0.28% to 1.35%. Emission intensities decreasedwith increasing fertiliser application at low N application rates, and the optimumfertiliser application rate to obtain minimum emissions but maximum crop yield was 160 kg N ha−1. © 2014 Published by Elsevier B.V.
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