An agricultural system comprises a baler (4) with a plunger (30) and a sensor (51) for sensing a plunger-related value; a vehicle (1) comprising a power source (2) operable to convey power to said plunger (30); a CVT (54) arranged to drive the plunger (30). In order to balance a fluctuating load of the plunger (30) over the working cycle, an electronic control unit (ECU) is coupled to the sensor (51) and to the CVT (54) and is configured to receive the signal from the sensor (51); and cause said CVT (54) to modify the gear ratio based on the signal from the sensor (51) and on a mathematical model defining a CVT gear ratio variation profile derived from an expected load applied by the crop on the plunger (30) over its operating cycle.