When fertilization capital is limited, the maximum economic rate which gives the greatest profit per unit area cannot be applied to all crops, therefore, a predicting method for the most profitable fertilizer rates for each crop is needed. This work describes a graphical method for sharing the available fertilizer between two different crops, or else the same crop in two different soils or crop sequences where the fertilizer needs are not the same. The method can also be used in the case of irrigation when the capital or the amount of the available water are limited.