We recognize that most irrigated rice paddy soils have a horizon at/near the base of the Ap that is formed through puddling. This water-limiting layer is also mentioned in the definition of anthric saturation in Ch. 3. They are quite stable and are produced intentionally and purposely by humans to facilitate flood irrigation and rice production. They are higher in bulk density than the horizon above and below, and many act as a densic contact. WRB has identified a hydragric horizon that is associated with wet cultivation. It is underneath a plough pan that is under an anthraquic horizon. It is the plough pan that would be equivalent to the horizon I am describing. Do you see a need to define a new diagnostic or master horizon that is dense and water-limiting and forms at the base of the plow layer when it is cultivated when wet, or is using the p and d subordinate letters sufficient?
