Abstract: A rotor for a particulate material blender which form an outer tub or housing having at least a part cylindrical wall, and which is used for blending or mixing materials that are particulate using a plurality of arms moving paddles at their outer ends with adjustable, flexible wiper blades which engage the part cylindrical wall. The blender can be used for uniformly distributing materials that have different particle sizes, or for mixing two or more different materials together. The unit is particularly suitable for blending inorganic fertilizer materials quickly and efficiently.