Abstract: A composting system for promoting maximum aerobic microbial activity in a composting bed. The system includes at least one composting bay for receiving composting material and an agitator for aerating and displacing composting material as it travels through the composting bay. The agitator has at least one structural frame member, and a conveyor, a feeder, and at least one bridge breaker that are mounted to the structural frame member. As the agitator travels through the bay, the feeder takes composting material from the bay and feeds it to the conveyor which discharges the composting material rearwardly into the bay behind the agitator. The bridge breaker displaces the composting material above the feeder causing the material to fall substantially evenly onto the feeder, thereby preventing large amounts of composting material from suddenly collapsing onto the feeder which can result in overload conditions on the feeder drive system.