The concept of root-limiting layers is reserved for tangible physical restrictions to root growth or penetration (e.g., petrocalcic horizon).

Permafrost is not considered a root-limiting layer because it is a thermal condition in which soil material remains below 0 degrees Celsius for two or more years in succession. It is not a tangible physical restriction and is not synonymous with massive ground ice. Horizons with permafrost may be either impregnated by ice or they may be dry and ice-free.

Root-limiting layers also does not include chemical restrictions to root growth such as high soluble salts (i.e., salic horizon), high exchangeable sodium (i.e., natric horizon), or low pH plus high sulfur (i.e., sulfuric horizon).



Edited 1 time(s). Last edit at 06/19/2014 01:48PM by stladmin.