Abstract: The blades on the drum in composting apparatus are arranged obliquely relative to the direction of the helical spiral and also obliquely to the axis of the drum and to the direction of travel of the chassis of the vehicle for moving material toward the center of the drum. Blades adjacent the center of the drum attack the face of a pile of compost material first and create a void, which is then filled by material moved by the following blade, while it is creating another void to be filled by material moved by the next blade and so on to the end of the spiral and the outer ends of the drum.