To prevent or minimize bridging of material to be dispersed within a containment vessel, a rotatable auger is positioned in close proximity to a curvilinear inner wall surface of the vessel. The auger has an axis that moves parallel to the curved wall surface in a manner such that the auger flights maintain a close working relationship relative to the curved wall surface as the auger is positioned for movement therealong. A spreader apparatus is positioned to receive material dispensed through the vessel outlet port to broadcast the dispensed material externally of the vessel.