Classification of Gley Soils for the Purpose of Forest Management and Reforestation

Abstract

The degree of soil drainage is determined by the depth of the ground water table, or the upper limits of the waterlogged soil layer. Anaerobiosis and hydrolysis, dominating the strata of soil below the ground water table, produce a deoxidized, often highly dispersed, sticky zone, mottled with reduced oxides of iron, and called gley horizon (Wyssotzky, '05). At a certain depth the gley horizon is underlain by an impervious substratum, called dead horizon of dryness (Wyssotzky, '30). Soils in which the gley layer occurs within the reach of the root systems of trees or cultivated plants, i.e. at an approximate depth of 7 feet or less, are classified as gley soils. Hydromorphous and poorly drained are the other terms applied to the soils of this group. The process of gleyization may be superimposed upon any member of the great soil groups of the world. The resulting varieties are referred to as gley podzols, swamp podzols, gley laterites, vlei soils, meadow soils, lowland prairie soils, ferruginous soils of mountain valleys, marl soils, etc. Ordinarily, gley soils occur sporadically, being confined to depressions and areas underlain by impervious substrata. However, in certain regions of America, northern Europe, Siberia and Africa, gley soils are a dominating type occupying hundreds of thousands of acres. The