It is used in high-cost turf applications. Composting is a process in which organic matter is broken down by microorganisms over weeks or months. The organic matter that remains is much more stable than the starting materials. A great variety of composted materials are available. Composted municipal sewage sludge is a byproduct of the sewage treatment plant.
Heavy metals are a concern with some sludge composts.
If using a composted sludge in the home landscape, be certain it is cleared for this use. Sludge composts are also fairly high in nutrients. Humus is the decayed organic matter in soil. The term is sometimes used to describe well-composted organic soil amendments, such as 'leaf humus'. Cow and poultry manures are most suitable for use when well composted.