In this paper we present a graphical alternative to Wald and likelihood-based confidence intervals for the Economical Optimum Nitrogen Rates (EONR). Quadratic models are commonly used to determine EONR, however by definition EONR is the point where the marginal returns from crop yield are equal to the marginal cost of fertilization, this makes the EONR parameter to be non-linear and therefore typical Wald intervals are inadequate. We present the Confidence Curves methodology and illustrate it with some corn yield data collected in South Central Minnesota.