Fig. 2. Shoot biomass produced (y axis) is presented vs. N concentration of biomass (x axis) for cover crops grown during the summer in the north, during the summer in the south, and during the winter in the north. The cover crops were categorized as either a nonlegume or a legume/mix (sole legume or a mixture with legume). The C/N ratio of 23 (equivalent to a tissue N concentration of 2%) bisects the figure and residues on the right side are expected to mineralize N. Data is from Creamer and Baldwin, 2000; Justes et al., 1999; Mutch et al., 2001; Schmidt et al., 2001; and Snapp et al., 2003.