Mushroom Phase I compost needs to be pasteurized before the mushroom grower can inoculate it with spawn. We have developed a unique facility to create Phase II compost. The photos to the right show an enclosed air tight concrete tunnel with an air floor. The air is forced through pipes in the concrete floor and through specialty calibrated nozzles to regulate air flow. The air is drawn off the top of the compost and recycled through the air floor until the compost is pasteurized and ammonia levels are reduced.