The present invention relates to a method for composting spent mushroom compost, comprising of composting the spent mushroom compost under conditions for providing composted spent mushroom compost with a dry matter content of 45% to 90%, preferably of 55% to 75%. According to another aspect, the present invention relates to composted spent mushroom compost comprising a dry matter content of 45% to 75%, a nitrogen content of 1% to 3% by weight, a phosphorus pentoxide (P205) content of 0.5% to 3% by weight and/or a potassium oxide content of 1% to 5%o by weight.
