Fig. 1 Contour maps of grain yield (g per unit row) in (left) soybean and (right) wheat uniformity trials. For soybean, the contour interval is 30 g; the lightest shade corresponds to a value of 40 g and the darkest shade, 310 g. For wheat, contour interval is 60 g; the extreme shades correspond to values of 375 and 915 g. The scale used is representative of the true physical size of each field. Source of data: Wu et al. (1995) for soybean and Wiebe (1935) for wheat