Fig. 1. The mean effect of cattle slurry (CS) (average of ¹⁴CS¹⁵NO₃, ¹⁵CS¹⁵NO₃, and ¹⁵CS¹⁴NO₃ treatments) on the flux of N₂O when applied at the same time as KNO₃ to grassland on four occasions in 1997. (LSD values are for comparing any two means at P < 0.05).