Fig. 1. Relationship between N uptake and total dry matter production of (A and B) potato and (C and D) wheat in (A and C) 1997 and (B and D) 1998. For each day after emergence (DAE), the line was fitted according to Eq. [2] (broken lines) and at each N level according to Eq. [3] (solid lines). Data values are DAE of periodic samplings. Open symbols represent potato cultivar Junior and wheat cultivar Axona, and closed symbols represent potato cultivar Agria and wheat cultivar Baldus for N1 (circles), N2 (triangles), and N3 (squares).
