An accessory mountable to an ATV includes an extension rack that provides a substantially flat storage bed. A spreader assembly for storing and distributing granular material therefrom is supported in a position below the extension rack. In the preferred embodiment, the extension rack is mounted to the carrier rack of the ATV, and the spreader is mounted to the extension rack such that it is positioned under the extension rack. The extension rack preferably includes a door that provides a passageway to the spreader assembly and also includes side walls that are vertically disposed with respect to the substantially flat storage bed.