This paper presents results regarding the variation of the qualitative parameters of the organic fertilizer machines according to the parameters of the material and control, of the working regime. These results are obtained from mathematical models that interpolate experimental data. The functions thus obtained allow the investigation of the existence of optimal working regimes and, if confirmed, the identification of these operating modes (of the optimal control parameter set: rotational speed, inclination angles, flow rate, etc.). The analysis can be extended to other types of agricultural machinery for the administration of solid organic fertilizers, chemicals or amendments.