Fig. 3: Temporal changes in maize’s economic optimum nitrogen rate (EONR) over the last 30 years.
From: The optimum nitrogen fertilizer rate for maize in the US Midwest is increasing
The solid black line (and the corresponding equation) refers to the overall multi-dataset trend per a continuous maize and maize-soybean crop rotation, while the shaded bands around the lines are the 95% confidence interval. Colored lines refer to the overall trend per individual study (see “Methods” section “Enhanced optimum N rate database”). The full regression equations for the single-year lines are given in Table S1.
