The influence of tillage on N 2O fluxes from an intensively managed grazed grassland in Scotland
Intensively managed grass production in high-rainfall temperate climate zones is a globally important source of N
2O. Many of these grasslands are occasionally tilled to rejuvenate the sward, and this can lead to increased N
2O emissions. This was investigated by comparing N
2O 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 2O 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 2O fluxes of 0.85 ± 0.11 kg N 2O-N ha −1. However, any influence on N 2O emissions after this period appears to be minimal. The cumulative N 2O 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 2O-N ha −1, respectively.