Separably-driven rotor portions (30) for a combine harvester (10) and a method for threshing grain using separably-driven rotor portions are provided. The combine harvester is moved through harvest material comprising grain material and material-other-than-grain ("MOG"). The grain material is separated from the MOG using multiple processing areas. The auger portion (70) may be stopped or rotated at a slower speed with respect to rotation of the threshing portion (80) to simulate the gathering of a large amount of crop material even when small plots are involved, thereby providing the benefits of large- plot harvesting to small-plot applications.
