The reasons for the formation of light-colored acid eluvial horizons in the soil profile

Concepts concerning the origin of light-colored acid eluvial horizons within the soil profiles are considered. In Russia, the current concept is related to the polygenetic origin of these horizons indicating that their formation is affected by acidic hydrolysis, lessivage, and gleying. The acidic hydrolysis under aerobic conditions was shown not to provide the reduction of Fe (III) to Fe(II) and its transfer to soil solution. Lessivage is not an obligatory factor that controls the formation of light-colored acid eluvial horizons, since its signs are often absent in the profile of soils. The only process responsible for the eluviation of Fe, Mn, and Al; the removal of hydroxide and oxide iron coatings from mineral grains; increasing the relative Si content; and the appearance of the whitish color is gleying under conditions of a stagnant-percolative water regime. Precisely this factor is the single reason for the formation of light-colored acid eluvial (podzolic) horizons. Therefore, they are monogenetic in origin.