Fig. 2. Validation of the critical N curve using data from corn grown under limiting and nonlimiting N growing conditions. Solid line, critical N curve (N_c = 34.0W^–0.37) describes the relationship between the critical N concentration and shoot biomass of corn in France (Plénet and Lemaire, 2000); dashed line, critical N curve (N_c = 34.1W^–0.391) describes the relationship between the critical N concentration and shoot biomass of corn in Germany (Herrmann and Taube, 2004).