What is the minimum thickness required for a cambic horizon?

A cambic horizon is a subsurface layer in soils that signifies a degree of alteration due to soil formation processes, particularly the processes of illuviation (the movement of materials downwards through the soil) and some level of clay accumulation. The minimum thickness requirement for a cambic horizon is 15 cm. This distinction is crucial as it helps classify and differentiate soil horizons according to international soil classification systems, such as the World Reference Base for Soil Resources (WRB).

While the other thickness options may seem plausible, they do not meet the standard criteria set for defining a cambic horizon. For a horizon to be classified as cambic, it must not only exhibit the necessary characteristics of development and alteration but also meet this minimum thickness requirement of 15 cm to ensure it is sufficiently developed for the classification. This requirement is vital for soil scientists and agronomists in their assessments and interpretations regarding soil health and usability.