Abstract: A compost windrow turning machine disintegrates an existing windrow of compost material, conveys the disintegrated material rearwardly, aerates the rearwardly conveyed material with a positive displacement of air into the rearwardly conveyed compost material, and re-forms a new windrow of remixed and aerated compost material rearwardly of the machine in line with the original windrow. The disintegration of the original compost windrow is accomplished with a rotor having segmented teeth arranged in a spiral to shred the original compost material and convey the disintegrated material to a central chain and slat conveyor positioned behind the rotor. A positive displacement of air is injected into the compost material on the central conveyor by a pair of laterally disposed fans mounting in conduits angled inwardly toward the central conveyor. The discharge of material off the central conveyor is passed through a set of windrow-forming shields to create a new windrow.