Abstract: A rotary composter includes a rotatable composting drum, a motor for rotating the drum, an aeration system for supplying air to the drum and an open-loop computerized controller for controlling one or both of the motor and the aeration system based on animal growth data. The rotary composter may also have a wireless nitrogen gas sensor for sensing an amount of nitrogen gas in the drum and a load cell for measuring a mass inside the drum to enable the controller to further control one or both of the motor and the aeration system based on signals from the nitrogen gas sensor and the load cell.