Soil Formation Factors - Vocabulary Flashcards

A set of 20 vocabulary-style flashcards drawn from the lecture notes on soil formation, morphology, and characteristics.

Parent material

The base material from which soil forms, including igneous, sedimentary, and metamorphic rocks and wind- or water-deposited sediments; its mineral content determines soil properties (e.g., low calcium rocks yield acidic soil; wind deposits form loose sandy soils prone to erosion).

Topography

Shape of the land surface that controls water movement, drainage, erosion risk, and the type of soil (upland vs lowland; steep vs flat).

Time

The duration over which climate and organisms act on parent material; older soils tend to have more distinct horizons.

Organisms

Plants, animals, and microorganisms living in soil; influence organic matter accumulation and the soil microbiome; vegetation affects which microbes dominate (e.g., prairie vs forest).

Climate

Weather conditions (temperature and moisture) that influence weathering rates and soil development; higher temperatures can accelerate reactions and evapotranspiration; precipitation drives leaching.

Weathering

The breakdown of rocks and minerals by natural forces, forming the basis of soil development.

Physical weathering

Mechanical breakup of rocks (e.g., through wetting/drying, freezing/thawing) without chemical alteration.

Chemical weathering

Chemical alteration of minerals driven by water and air, producing soluble ions and clay minerals.

Biological processes

Soil processes driven by living organisms, including accumulation of organic matter and interactions with plant life cycles (annuals, biennials, perennials).

Microbiome

The community of microorganisms (fungi, bacteria, viruses, etc.) living in a specific area of soil.

Organic matter

Matter derived from plants and animals that accumulates in soil through litter, roots, and decomposing organisms.

Horizon

A distinct layer of soil; older soils often exhibit more pronounced horizons formed over time.

Leaching

Movement of dissolved minerals downward through soil with percolating water.

Evapotranspiration

Combined loss of water from soil and plants (evaporation plus plant transpiration).

Transpiration

Water loss from plants through stomata during gas exchange.

Precipitation

Water input (rain, snow, etc.) that can dissolve minerals and promote leaching through the soil.

Silicate minerals

Minerals containing silicon, oxygen and metals (e.g., Si, O, Al, Mg, K, Fe) that weather to soluble and insoluble products.

Clay minerals

Fine-grained minerals formed during chemical weathering; products of weathering that influence soil texture and properties.

Organic layer thickness influenced by vegetation

Soils under trees tend to have a thinner organic layer, while soils under grasses tend to have a thicker organic layer due to litter and root turnover.

Prairie bacterial dominance

In prairie vegetation, bacteria are the dominant microorganisms in the soil microbiome.