Mushroom compost is a compost mixture that is usually made of straw, hay, gypsum, and chicken or horse manure that was used to grow mushrooms. It is sometimes referred to as spent — meaning the mushroom farmer has used it several times. Composts are rotted organic matter that are usually made of decomposing 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 a fertilizer.
Compost is made by mixing various plant matter with manure. As the organic materials decay the bacteria in it will start to multiply, and the temperature within the compost pile will begin to gradually 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 mushroom spores are added. Spores are very similar to plant seeds, but do not carry food resources like seeds. These spores will grow into mushrooms in the compost, and the same mixture may be used up to three times before it is discarded. Mushroom growers often have a recipe for their mushroom compost to ensure that they produce a consistent product. This consistency also makes the use of spent mushroom compost a desirable product for gardeners.
Gardeners, however, need to be careful with some types of mushroom compost because it can contain a large amount of soluble salts, which can damage or kill plants. The mixture must be used with caution and in moderation. It can also contain fungicides and pesticides, which may be a concern for organic gardeners. Organic farming and gardening are chemical and pesticide free.
People can easily make their own compost by using any leftover organic food or plant matter. Organic materials can be put into an outdoor pile or bin. There are pre-made compost bins available for purchase that rotate materials so the contents can be mixed. These bins may have an open or closed design. There are even sealed containers for the kitchen counter, so cooks can toss compostable items in it while they work.
Compost is generally used to improve the structure and nutrient quality of soil. It can be applied as mulch or mixed in before seeds or seedlings are planted. Mushroom compost and homemade compost can also be used to brew compost tea. This is also used as a fertilizer, or as a preventative to protect plants from disease, and is made by simply soaking compost in water for up to five days. It is then sprayed onto the soil, or onto the non-edible parts of plants.