A combine harvester having a chopper configured for chopping crop, which comprises a cutting cylinder fitted with chopper knives, a knife carrier fitted with counter knives, and a rasp bar arrangement. The counter knives and/or the rasp bar arrangement can be moved into a partial stream passing by the chopper. The harvester also has a crop spreading device configured for spreading the chopped-material stream emerging from the combine harvester on the ground in the rear region of the combine harvester, and a sensor unit configured for generating sensor data which represent at least one parameter influencing the spreading quality of the chopped-material stream emerging from the combine harvester. There is a control unit that adapts the position of the rasp bar arrangement and/or the counter knives depending on the spreading quality.
