Fig. 2. Relationship between crop dry matter production (W; Mg ha^-1) and critical N concentration ([N]) in (A) potato (Greenwood et al., 1990) and (B) wheat (Justus et al., 1994). Symbols are 95% of the calculated maximum W (Eq. [2] in text), as derived from Fig. 1. Open symbols are for 1997 and closed symbols are for 1998.

Return to article