Define pedogenesis and list major soil-forming processes (additions, losses, transformations, translocations).

• A. Pedogenesis is erosion of soil; major processes include deposition and compaction.
• B. Pedogenesis is plant growth in soil; major processes include photosynthesis and respiration.
• C. Pedogenesis is the process of soil formation; major processes include additions, losses, transformations, and translocations.
• D. Pedogenesis is weathering only; major processes include dissolution.

Answer: (C)

Pedogenesis refers to the process of soil formation, the way soils develop from their parent material through time as inputs, losses, changes, and movement of materials shape horizons and properties. The four major soil-forming processes are additions, losses, transformations, and translocations. Additions are inputs from outside the soil system, such as organic matter from plant litter, wind-blown dust, or mineral fragments added by weathering. Losses involve removal of components, for example leaching of soluble nutrients or erosion that physically removes soil. Transformations are the chemical, biological, and physical changes that alter soil constituents, such as weathering of minerals, oxidation-reduction reactions, and the decomposition of organic matter. Translocations are the movement of materials within the soil profile, like the downward movement of clays, organic matter, or iron oxides (eluviation and illuviation) that create distinct horizons.

The other descriptions don’t fit pedogenesis: defining it as erosion or as plant growth mischaracterizes the concept, since pedogenesis is about soil formation rather than a single process like erosion or biological activity alone. Limiting it to weathering also misses the broader set of processes that together form soils.