Aging or curing the finished compost will also influence the quality. N ratio will have further decreased and the pile will have been recolonized by soil microorganisms, which can give the compost plant disease suppressing qualities. Alternatively, compost maturity can be ensured by providing a curing phase of six months after the last heating phase. Uses of Compost To a degree, we can let the intended end use determine the required quality of the compost. Compost destined for use as a component of potting mixes, for example, must be of the highest quality.
Compost alone can be too nutrient rich and porous.
Salt content in compost refers to the total of various ions, such as sodium, potassium, ammonium, nitrate, chloride, sulfate etc. Spent mushroom compost, for example, often contains high salt levels remaining from the fertilizer materials applied during mushroom cultivation. High or excessive soluble salts may be injurious to plants. Seedlings, bedding plants, potted flowers and foliage plants, and herbaceous perennials, in particular, are very sensitive to high salt and pH levels. Woody nursery crops tend to be more tolerant of high salt levels than herbaceous crops.