How do I make good compost for button mushroom farming?

Mushroom compost is the specially prepared, selective growing medium for button mushroom, and getting it right is the single biggest factor in a button crop. It is made mainly from wheat or paddy straw plus nitrogen sources such as poultry manure or specific fertilisers, gypsum, and sometimes additives, which are wetted, stacked and turned through a controlled fermentation that heats up, breaks down the straw and builds a medium that favours mushroom over weed moulds. The two broad methods are long method composting in the open over several weeks, and short method composting using a pasteurisation tunnel with steam and controlled temperature, which gives more reliable, selective compost. A small grower can attempt long method compost, but it is labour intensive and quality varies, which is why many beginners buy ready spawned compost at first. Good compost smells sweet and earthy, not ammonia like, and is properly pasteurised so it is free of pests and competitor moulds. Learn the recipe and turning schedule hands on from DMR Solan or your KVK before relying on your own compost.