S = f(cl,o,r,p,t,….)
Jenny pointed out that there are two principal methods that the state equation may be solved: first in a theoretical or conceptual manner by logical deductions from certain premises, and second empirically by experimentation or field observation. The empirical method is still mostly employed today, and soil formation can be defined by varying a single factor and keeping the other factors constant. This led to the development of empirical models to describe pedogenesis, such as climofunctions, biofunctions, topofunctions, lithofunctions, and chronofunctions. Since Hans Jenny published his formulation in 1941, it has been used by innumerable soil surveyors all over the world as a qualitative list for understanding the factors that may be important for producing the soil pattern within a region.
The term Clorpt is mainly used for empirical quantitative prediction with the purposes of making digital soil map. In this approach, the state-factor equation was put explicitly into a spatial framework and the factors were also observed in the same spatial domain. Some people have termed the approach environmental correlation, associated with using stratigraphy, digital terrain models and gamma radiometric survey, to predict and map soil properties.