When done with combines it is cut low, when done with foragers it is cut higher (average crop is waist to shoulder height before harvest). With the forager, you are only taking the capsule (Seed head) + a minimum of straw (say 20 -30 cm / 8-12 inches).
The crop is taken to the processing factory, from the harvester (no cleaning or processing is done on farm),
Regards,
TC.