Mushroom compost is a compost mixture usually composed of straw, hay, gypsum and chicken or horse manure used to grow mushrooms. It is sometimes called spent, meaning that the mushroom grower has used it several times. Compost is rotted organic material that is usually made up of decaying plants and manure, and used to enrich soils. Gardeners can purchase mushroom compost at their local lawn and garden store, if they wish to add it to a garden as fertilizer.
Compost is made by mixing various plant materials with manure. As the organic materials decompose, the bacteria in them will begin to multiply and the temperature inside the compost pile will gradually begin to rise. Once the temperature reaches and exceeds 160°F (about 71°C), all weeds and pathogens are killed. It usually takes about 30 days for mushroom compost to be ready for use.
As an added precaution, the mixture is pasteurized before the mushroom spores are added. The spores are very similar to plant seeds, but do not carry food resources like seeds. These spores will become mushrooms in the compost, and the same mixture can be used up to three times before being discarded. Mushroom growers often have a recipe for their mushroom compost to ensure that they produce a consistent product. This consistency also makes using spent mushroom compost a desirable product for gardeners.
Gardeners, however, should be cautious with certain types of mushroom compost because it can contain a large amount of soluble salts, which can damage or kill plants. The mixture should be used with care and in moderation. It may also contain fungicides and pesticides, which can be a concern for organic gardeners. Organic farming and gardening are free of chemicals and pesticides.
People can easily make their own compost using leftover organic food or plant materials. The organic materials can be put in a pile or an outdoor bin. There are pre-made compost bins available for purchase that rotate the materials so that the contents can be mixed. These bins can have an open or closed design. There are even sealed containers for the kitchen counter so that cooks can toss compostable items into them while they work.
Compost is typically used to improve the structure and nutrient quality of the soil. It can be applied as a mulch or mixed in before planting seeds or seedlings. Mushroom compost and homemade compost can also be used to make compost tea. This is also used as a fertilizer or preventive to protect plants from disease, and is made by simply soaking the compost in water for up to five days. It is then sprayed on the soil or non-edible parts of the plants.