An agricultural harvester includes a straw hood having a hollow interior space for receiving material other than grain (MOG) from a threshing and separating system of the harvester and chaff from a cleaning system of the harvester. A drive system is provided for powering a straw chopper and a weed seed mill. The drive system includes a single belt positioned outside of the straw hood that is wound at least partially around (i) a straw chopper pulley that powers the straw chopper, (ii) a weed seed mill pulley that powers the weed seed mill, and (iii) a power take off shaft of the harvester that receives power from an engine or other power source of the harvester.