Phase II continues the conversion of nutrients into a selective food supply for the mushroom. First, pasteurization with live steam is performed to kill any insects, nematodes, competing fungi, or other pests that may be present in the compost. Second, any remaining ammonia levels which formed during Phase I composting are eliminated. Ammonia can damage mushroom spawn growth. Phase II composting can be viewed as a controlled, temperature dependent, ecological process using air and steam to maintain the compost in a temperature range best suited for thermophilic organisms to grow and reproduce. The growth of these thermophilic (heat-living) organisms depends on the availability of carbohydrates in a usable form and the presence of nitrogen, some of which is in the form of inbound ammonia.
Mountain Meadow uses a single zone bed of shelf growing system where the compost is placed directly in the stationary beds, which are in a room used for all steps of crop culture. This growing method is both energy efficient and minimizes the use of water in the growing process. As a result we use less than half the water in our growing rooms compared with “tray” farms (90% of all farms in California are tray farms). Hence we do not use as much clean up water or moisture replacement water due to evaporation.