Fig. 2. Relation of N rate for maximum beet (a) and sugar production (b) and optimum N rate for adjusted beet production (c) to preplant soil NO₃–N. Tile drained soils with high risk of leaching (furrow irrigation or winter rain higher than 470 mm–triangles) and rainfed locations in drought years (less than 350 mm–circles) are excluded from the regressions.