Feedback processes in soil genesis

Feedback can be defined as the returning of a part of the effects of a given process to its beginning or to a preceding stage so as to reinforce or modify that process. Feedback processes are self-accelerating because of continuous reinforcement of the causes starting them. Up to a certain moment, reinforcement is proportional to the effects (or output) of the process. Later, de-acceleration and termination come as one of several factors (or reactants) in the process become limiting, e.g., depletion of easily weatherable minerals, hence cessation of clay formation. In soils there are many feedback, self-terminating processes such as accumulation of organic matter in Mollisols, clay accumulation in Argids, and development of windows in duripans and dayas in soils with petrocalcic horizons. The occurrence and constancy of some morphological features in many soil profiles and soilscapes can be explained by this concept.