winter wheat, winter oil seed rape , and maize . According to Ple´net and Lemaire (2000), the critical %N–W
relationship model for maize is proposed as %Nc = 3.40 (DM)0.37. This equation is fitted to biomass values between 1 and 22 t ha1, i.e., the stages between nine to ten visible leaves and silking + 25 d. However, the relationship between shoot N concentration and aerial dry matter accumulation for 478 and Wu312 was N = 2.35 (DM)0.30 andN = 2.41 (DM)0.26, respectively