A two-parameter phenomenological model for fertilizer granulation taking into account the growth and death function was developed. It was assumed that the growth and death functions were governed by layering and breakage mechanisms, respectively. Experiments were conducted in a rotary drum granulator on an N-K system and the data were used for obtaining the model parameters with reference to the operating conditions and to validate the model. It is concluded that the proposed model adequately describes the complexities of the fertilizer granulation process.