Soil Science Lecture Flashcards pt1

Vocabulary flashcards covering fundamental soil science concepts, including soil functions, essential elements, weathering, formation processes, soil profile horizons, landscape positions, texture, composition, and structure.

Regolith

The soil material above bedrock, formed from broken-down rock.

Biomass

Organic sources of energy used as fuel.

Terra Firma

Solid ground, referring to soil as an engineering medium.

Essential Plant Elements Mnemonic

"C. HOPKINS CaFe is Mighty Nice CuZine, Managed Closely by the MoB," representing all 17 naturally occurring elements required for plant growth.

Physical Weathering

The breakdown of rocks and minerals over time through temperature changes (freezing, thawing, heat, cooling), wind-abrasion, water, plants, and animals.

Chemical Weathering

The breakdown of rocks caused by the release of acids from plant decomposition and acids from the atmosphere.

Soil Forming Factors

The five primary factors in soil formation: parent materials, climate (precipitation and temperature), biota, topography, and time.

Lichens

A symbiotic relationship of algae and fungus that aids in soil formation; algae fixes nitrogen into a usable form for plants, captures sunlight, and creates sugars and oxygen.

Alluvial Soil

Soil that has been moved and deposited by flowing water.

Marine Soil

Soil deposited by the ocean.

Loess

Soil moved by wind, also known as aeolian sedimentation.

Glacial Soil

Soil moved by glaciers and deposited in mounds called moraines.

Moraines

Mounds of sediment deposited by glaciers.

Colluvial Soil

Soil moved by gravity that builds up at the base of slopes.

Residual Soils

Non-transported soils formed in place with bedrock as the parent material.

Cumulose Soils

Non-transported organic soils formed from the accumulation of deposited organic plant materials, occurring due to low oxygen and a high water table.

Peat Soils

A type of cumulose soil that may be very slow in nutrients.

Muck Soils

A type of cumulose soil that may be very fertile.

O-Horizon

The soil horizon made up of organic accumulations on the surface of mineral soil.

A-Horizon

The highest mineral horizon, known as topsoil, containing the highest makeup of organic matter and often possessing a dark color due to partially decomposed organic matter.

E-Horizon

The horizon characterized by maximum leaching (eluviation), composed of clays, iron oxides, and/or aluminum oxides, and often absent.

Eluviation

The process of maximum leaching of materials out of a soil horizon, characteristic of the E-horizon.

B-Horizon

The subsoil horizon forming below the O, A, and E horizons, recognized as the horizon of accumulation from above (illuviation).

Illuviation

The process of accumulation of soil materials washed down from horizons above, characteristic of the B-horizon.

C-Horizon

Loose material under the soil that has a rock-like look and is not weathered enough to be an A or B horizon, but is loose enough to break apart with a shovel.

R-Horizon

Consolidated rock showing little evidence of weathering, commonly known as bedrock.

Bottomland Soils

Young soils located in bottomlands that show little sign of age and are usually alluvial.

Upland Soils

Old soils formed in place from rock underneath, exhibiting distinct horizons.

Terrace Soils

Soils moved a long time ago that have distinct horizons, have not been covered by recent erosion, and often contain a claypan or hardpan.

Footslope Soils

Soils on a gently inclined, generally concave surface at the bottom of a slope, eroded from terrace or upland soils.

Sand Particle Size

Irregularly shaped soil separates ranging from $0.05\,\text{mm}$ to $2\,\text{mm}$ in size.

Silt Particle Size

Soil separates ranging from $0.002\,\text{mm}$ to $0.05\,\text{mm}$ in size.

Clay Particle Size

Flat, plate-shaped soil separates smaller than $0.002\,\text{mm}$ in size.

Soil Texture

The relative proportion and combination of sand, silt, and clay separates in a soil.

Soil Makeup Composition

The volumetric makeup of soil, consisting of approximately $\frac{1}{2}$ solid (mineral + organic matter) and $\frac{1}{2}$ void space (water + air).

Soil Structure

The arrangement of individual soil particles into groups, aggregates, or peds.

Aggregates (Peds)

Groups or clusters into which individual soil particles are arranged.

Puddled Condition

A condition that occurs when soil structure is destroyed in clay-like soils, often due to over-tilling.

Macropores

Larger pore spaces in soil that allow for good drainage and provide air space.

Micropores

Very small spaces or openings in soil that retain water against the force of gravity.

Flocculation of Clays

The aggregation process occurring because plate-shaped clay particles have negative charges that attract and hold cations, which in turn attract one another.