Which soil order is characterized by the presence of spodic horizons?

The soil order characterized by the presence of spodic horizons is Spodosol. Spodic horizons are distinctive layers in the soil that contain illuvial accumulations of organic matter, aluminum, and iron, which can give the soil a dark color. These horizons typically form under conditions of leaching in humid climates, where mineral and organic materials are washed down through the soil profile due to high precipitation.

Spodosols are most commonly found in forested regions, particularly in sandy or acidic soils where the process of podzolization, involving the leaching of base cations and the accumulation of iron and aluminum oxides and organic materials, occurs. This characteristic makes them quite different from other soil orders that do not develop such horizons.

In contrast, Mollisols, Alfisols, and Inceptisols do not typically exhibit spodic horizons. Mollisols are known for their rich organic matter and dark topsoil, Alfisols for their clay-rich horizons that provide good fertility, and Inceptisols are younger soils that exhibit weak horizon development without the definitive spodic layers. Understanding this distinction is crucial for soil classification and its implications for land use, agriculture, and ecological management.