A system (100) and a method are provided for controlling a combine harvester (10). The method comprises the steps of receiving grain flow sensor signals from a plurality of grain flow sensors (210), based on the received grain flow sensor signals, determining a current load on a straw walker section (22), and based on the current load, adjusting an aggressiveness setting of a threshing and separation section of the combine harvester (10). The grain flow sensors (210) are provided underneath and adjacent to a crop transfer surface (260) of the straw walker section (22) of the combine harvester (10) and are distributed over a length of the straw walker section (22).
