An apple where putrefaction has started

Putrefaction is a natural process of decay. Microorganisms break down organic materials. Usually it occurs after the death of a plant or an animal. The process consists of many steps. The total time it takes is dependent on various factors, such as the availability of oxygen.

Putrefaction involves fermentation. Putrefaction is important, because elements such as nitrogen, phosphorus and sulfur which are bound in the dead matter are converted into a form that is usable by plants.