Soil Science Concepts and Terminology

Comprehensive vocabulary flashcards covering fundamental concepts, processes, horizons, and parent materials in soil science.

Catena (Toposequence)

A group or sequence of soils on a hillside formed primarily under the influence of slope and topography, typically transitioning from dry conditions at the top to wet conditions at the bottom as water moves downward.

Effective Precipitation

The portion of total precipitation that remains in the root zone of plants, directly impacting plant growth, agricultural productivity, and soil profile development.

Translocation

The soil-forming process involving the movement of inorganic and organic materials within a soil profile, occurring either downward through percolation driven by gravity or upward via capillary action.

Quartz

A common silicate mineral that is highly resistant to chemical weathering and is dominant in many soils, especially in sandy or infertile soils.

Lacustrine Deposit

Parent material consisting of silts and clays that have settled and deposited in the quiet, still, fresh waters of lakes.

Eluviation

The soil-forming process by which dissolved or suspended substances are washed out or leached from upper soil horizons down to lower layers.

Illuviation

The soil-forming process of accumulation and deposition of leached materials (such as clay, iron, or organic matter) in the lower soil horizons.

Loess

A windblown (eolian) parent material transported and deposited by wind that consists predominantly of silt-sized particles.

Addition

A basic soil-forming process consisting of the input of materials into the developing soil body by external forces.

Mineralization

The biological and chemical process by which nutrients and chemicals present in organic matter are decomposed or oxidized into plant-available inorganic forms.

Regolith

The layer of unconsolidated, weathered rock material overlying bedrock, comprising master horizons such as A, B, C, and E, but excluding hard, consolidated bedrock (the R horizon).

Mass Flow

The movement of dissolved nutrient ions through the soil solution to the root surface driven by the convective uptake and movement of water as transpiring plants draw water from the soil.

Pedoturbation

The biological or physical mixing and reworking of soil (such as the burrowing action of pocket gophers), which can accelerate soil erosion and inhibit distinct horizon development.

Caret (^) Prefix

A prefix placed before a master horizon symbol to indicate that the soil material in that layer was transported and deposited by human activity.

Hydrolysis

A chemical weathering reaction in which water molecules dissociate and react with mineral ions, exemplified by: $\text{mica} + \text{H}_2\text{O} \rightarrow \text{K}^+ + \text{OH}^- + \text{acid clay}$.

Soil Solution

The aqueous liquid phase of soil containing dissolved organic and inorganic substances rather than pure water, serving as the immediate source of nutrients for plants.

Soil Crust

A hard and compact surface layer formed on the surface of bare or disturbed soil that can restrict infiltration and seedling emergence.

Glacial Till

Unstratified and heterogeneous parent material deposited directly by melting glacial ice, containing an unsorted mixture of debris ranging in size from large boulders to fine clay.

Glacial Outwash

Stratified and sorted sediment deposited by flowing meltwater streams beyond the margins of a glacier.

E Horizon

A mineral master horizon characterized by the maximum eluviation (loss) of silicate clays, iron, and aluminum oxides, leaving an accumulation of resistant quartz and other light-colored sand and silt particles.

Aerosolic Dust

Extremely fine windborne particulate matter with particle sizes significantly smaller than those found in loess and dune sand.