Abstract: A plurality of rotary cutters for pulverizing soil for a subgrade, a conveyor for moving soil from the subgrade, and a leveling blade are connected successively on a slowly moving machine to prepare in a single pass a subgrade for concrete. Blades on the rotary cutter are revolved horizontally and are set at different levels to slice the soil evenly from the bottom of the subgrade and to pulverize the soil. The conveyor may be either a screw or a chain type, and a portion of the conveyor extends across the subgrade behind the rotary cutters. The leveling blade leaves a desired amount of leveled, pulverized soil, and when a screw conveyor is used, pushes the soil into the conveyor.