The delta yield concept holds much promise for production agriculture. It is based on the yield of a check strip where no nitrogen (N) has been applied. This strip serves as a biological indicator of the N supplying power of a particular area of land. This strip, combined with other strips where incremental rates of N are applied, provides all of the information needed to calculate the difference between the yield without N and the yield with an economically optimum rate of N, termed delta yield. Such field experiments also provide a measurement of how much N is needed to attain the delta yield response, expressed as kg N per unit of yield response. The relationship between delta yield and the amount of N needed to attain the delta yield response allows reasonable predictions of N rates to be made. This method of making recommendations has the advantage that it can be created locally, relies on simple mathematical relationships, and provides information that helps increase the effectiveness of N applications.