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  • The influence of tillage on...
    Cowan, Nicholas J; Levy, Peter E; Famulari, Daniela; Anderson, Margaret; Drewer, Julia; Carozzi, Marco; Reay, David S; Skiba, Ute M

    Biogeosciences, 08/2016, Volume: 13, Issue: 16
    Journal Article

    Intensively managed grass production in high-rainfall temperate climate zones is a globally important source of N.sub.2 O. Many of these grasslands are occasionally tilled to rejuvenate the sward, and this can lead to increased N.sub.2 O emissions. This was investigated by comparing N.sub.2 O fluxes from two adjacent intensively managed grazed grasslands in Scotland, one of which was tilled. A combination of eddy covariance, high-resolution dynamic chamber and static chamber methods was used. N.sub.2 O emissions from the tilled field increased significantly for several days immediately after ploughing and remained elevated for approximately 2 months after the tillage event contributing to an estimated increase in N.sub.2 O fluxes of 0.85 ± 0.11 kg N.sub.2 O-N ha.sup.-1 . However, any influence on N.sub.2 O emissions after this period appears to be minimal. The cumulative N.sub.2 O emissions associated with the tillage event and a fertiliser application of 70 kg N ammonia nitrate from one field were not significantly different from the adjacent untilled field, in which two fertiliser applications of 70 kg N ammonia nitrate occurred during the same period. Total cumulative fluxes calculated for the tilled and untilled fields over the entire 175-day measurement period were 2.14 ± 0.18 and 1.65 ± 1.02 kg N.sub.2 O-N ha.sup.-1, respectively.