Controlled environment composting for mushroom cultivation: substrates based on wheat and barley straw and deep litter poultry manure

Abstract

SummarySubstrates for mushroom cultivation were prepared, following a 2 day mixing and blending process, in bulk tunnels under a controlled temperature regime using forced ventilation. The temperature regime was based on a conventional bulk tunnel composting process, i.e. pasteurization at 60 °C for 6 h, followed by a conditioning phase at 47 °C until the substrate was clear of ammonia. With the exception of ammonia, which increased with increasing compost nitrogen content, this process did not result in strong odours. The substrates were ready for inoculation with mushroom ‘spawn’ 7–12 days after the initial mixing of the compost ingredients. Increasing the compost nitrogen content from 1·1 to 2·5% of the dry matter by increasing the quantity of deep litter poultry manure added to straw in the ingredients resulted in a greater subsequent yield of mushrooms. Further increases in the substrate nitrogen content resulted in prolonged tunnel processing times, substrate desiccation, incomplete clearance of ammonia from the substrate and subsequently low or no mushroom yields. Substrate bulk density at the time of spawning decreased with increasing nitrogen content, but was increased by chopping the straw ingredient. Mushroom yields from composts prepared with barley straw were significantly lower than those from wheat straw composts, at equivalent nitrogen contents. Supplementation of prepared substrates with the proprietary protein-rich ingredient, Betamyl 1000, increased yields by 13·6%.