eluviatie

Eluviatie, known in English as eluviation, is a pedogenic process in which soluble substances and fine particles are removed from the upper part of a soil profile by downward-percolating water. As water moves through the soil, it dissolves and transports materials such as humus, clay minerals, and iron and aluminum oxides away from the upper horizons. The leached layer often becomes lighter in color and coarser in texture, forming an eluviated horizon commonly labeled the E horizon in soil profiles. The materials removed from the eluviated zone may be deposited in lower horizons through illuviation, the related process of deposition.

Eluviated soils typically form under conditions of adequate drainage and sufficient precipitation to promote leaching, though not so much that nutrients are washed away entirely. They are characteristic of temperate to cool climates and are associated with certain soil orders such as Podzols (Spodosols in some classifications) and Luvisols, among others. The eluviated horizon tends to be paler and lighter in color, often deficient in clay and organic matter, and it marks a boundary where eluviation is evident.

In practice, eluviation is identified by the presence of an E horizon in the soil profile and by the relative depletion of clay, humus, and oxides in that horizon. This process influences soil fertility, structure, drainage, and the vertical distribution of minerals and organic matter within the profile, with implications for land use and agricultural potential.

Terminology varies by language; in English the process is eluviation, while in some languages it is rendered as eluviatie or eluviation.