Fig. 6. Simulated dry mass corn grain yield at (a) Sterling and (b) Stratton, simulated sorghum grain yield at (c) Walsh, and (d) simulated proso millet grain yield {wheat–corn (or sorghum)–millet–fallow [WC(S)MF] rotation only} at three locations against the observed values for two rotations {wheat–corn (or sorghum)–fallow [WC(S)F]: 1988–1999; WC(S)MF: 1988–1993}. Values in parentheses are root mean square error (RMSE) values (kg ha^-1).