Fig. 5. (a) Total N₂O-N emissions from April 2001 to March 2002 and (b) mean N₂O-N emission rates for the cutting period (April to July) and fertilizer-borne N₂O (%) at the Karkendamm experimental farm in northern Germany (Kelm et al., 2004). C = Control; S = ¹⁵N-labeled slurry; F = 100 kg N ha^–1 labeled with ¹⁵N; FS = nonlabeled slurry + 100 kg N ha^–1 labeled with ¹⁵N; SF = ¹⁵N-labeled slurry + nonlabeled 100 kg N ha^–1.