Use of Standard Exponential Yield Curves

Economic interpretation of yield response to fertilizers based on use of standard exponential yield curves can be accomplished with a few calculations that involve only simple arithmetic. The method is useful to teachers, extension workers, researchers, or anyone interested in the economics of fertilizer use. Even those who are familiar with complex mathematical procedures can save time by using the standard curves. Fitting the curve does not require the use of a computing machine. However, a machine or a slide rule is needed in finding the most profitable rates of application and in related calculations. The procedure is illustrated here by describing its application to analysis of corn yield response to nitrogen. However, the method may be used in analyzing yield response to varying levels of different yield influencing factors capable of being applied in increments, such as other plant nutrients, or density of stand.