Nitrous oxide emission from a grassland soil fertilized with slurry and calcium nitrate

SUMMARY Concentrations of nitrous oxide (N 2 O) and oxygen were monitored over a 2‐yr period in an imperfectly drained grassland soil receiving applications of N as cattle slurry or Ca(NO 3 ) 2 . In both years N 2 O concentrations in the different treatments were in the order nitrate > slurry > control. Gaseous diffusion coefficients were determined in soil cores by a krypton‐85 tracer method and used to calculate approximate N 2 O fluxes from the soil. Only 1–5 kg N ha −1 was lost as N 2 O after a single application of > 1200 kg N ha −1 as slurry compared with 3–11 kg N ha −1 lost after 100 kg was added as NO 3 − . Total gaseous losses (N 2 O+N 2 ) could be expected to be higher in both cases.