Product dosing system for agricultural machines, in particular for fertilizer distributors in which a single granular fertilizer like nitrogen, potassium or phosphorus, can be stored in independent hoppers (3, 3 and 3") disposed in line following the direction of advance of the machine, distributing the single fertilizer to the ground. The machine comprises an auger (8) for conveying the single fertilizer towards dosing means associated with each of the hoppers, allowing the distributed dosis to be adapted to the advancing speed to of the machine, the machine having to that end ground engaging means (4), through which the movement is transmitted to the regulating augers (8) and to the axles of the dosing means.
