Fig. 4 Time trends in (a) Iowa contest-winning rainfed maize yields and Iowa average yields in rainfed systems , and (b) Nebraska contest-winning yields in irrigated (NE-CW_i) and rainfed systems , and state average yields from irrigated and rainfed systems . All regression coefficients are significant at P < 0.001. The dashed horizontal line represents the mean irrigated contest-winning yield of 18200 kg ha^-1

Return to article