Soil Texture and Properties Flashcards

Vocabulary flashcards covering soil texture definitions, soil separates, rock types, wastewater classification groups, LTAR, and field/laboratory analysis techniques.

Mineral

A naturally occurring homogeneous solid with a definite (but generally not fixed) chemical composition and a highly ordered atomic arrangement, generally formed by inorganic processes.

Rock

A naturally occurring aggregate of minerals where the abundance and composition of minerals within a given rock type may vary somewhat.

Igneous Rock

A rock that solidified from molten or partly molten material, known as magma.

Metamorphic Rock

Any rock derived from pre-existing rocks by mineralogical, chemical, or structural changes in response to marked changes in temperature, pressure, and chemical environment at depth in the earth's crust.

Sedimentary Rock

A rock resulting from the consolidation of loose sediment or chemical precipitation from solution at or near the earth's surface, or an organic rock consisting of the secretions or remains of plants and animals.

Soil Texture

The relative proportion of sand, silt, and clay-sized mineral particles in the fine-earth fraction of the soil.

Fine-Earth Fraction

Mineral particles in soil finer than $2\,mm$ in diameter, containing the three soil separate sizes.

Rock Fragments

Mineral particles in soil that are $2\,mm$ in diameter or larger.

Coarse Fragments

Rock fragments in soil that are less than $10''$ in diameter.

Sand (Soil Separate)

Soil separate mineral particles ranging in size from $0.05\,mm$ to $2.00\,mm$.

Silt (Soil Separate)

Soil separate mineral particles ranging in size from $0.002\,mm$ to $0.05\,mm$.

Clay (Soil Separate)

Soil separate mineral particles that are less than $0.002\,mm$ in size.

Relative Particle Sizes Diagram

Diagram illustrating relative particle sizes where sand is $2.0 - 0.05\,mm$, silt is $0.05 - 0.002\,mm$, and clay is less than $0.002\,mm$ ($25.4\,mm = 1\text{ inch}$).

Group I Soil Group

Soil texture group for on-site wastewater consisting of Sand and Loamy sand, categorized as SUITABLE with an LTAR range of $1.2 - 0.8\,\text{gpd/ft}^2$.

Group II Soil Group

Soil texture group for on-site wastewater consisting of Sandy loam and Loam, categorized as SUITABLE with an LTAR range of $0.8 - 0.6\,\text{gpd/ft}^2$.

Group III Soil Group

Soil texture group for on-site wastewater consisting of Sandy clay loam, Silt loam, Clay loam, Silty clay loam, and Silt, categorized as SUITABLE with an LTAR range of $0.6 - 0.3\,\text{gpd/ft}^2$.

Group IV Soil Group

Soil texture group for on-site wastewater consisting of Sandy clay, Silty clay, and Clay, categorized as SUITABLE with an LTAR range of $0.4 - 0.1\,\text{gpd/ft}^2$.

Long Term Acceptance Rate (LTAR)

The volume (in gallons) of sewage effluent that a soil can absorb per unit area ($\text{ft}^2$) of trench bottom per time period (day), expressed as $\text{gpd/ft}^2$.

Stokes' Law

Equation used in laboratory soil texture determination defined as $V = \frac{h}{t} = \frac{r^2 g (d_p - d_l)}{\eta}$, where $V$ is fall velocity, $h$ is cylinder height, $t$ is fall time, $r$ is particle radius, $g$ is acceleration due to gravity, $d_p$ is particle density, $d_l$ is liquid density, and $\eta$ is fluid viscosity.

Bulk Density ($D_B$)

Mass divided by volume (where volume includes both pore spaces and solids). Sandy soils range from $75$ to $110\,\text{lb/ft}^3$, clayey/silty soils range from $65$ to $100\,\text{lb/ft}^3$, and compacted soils equal $125\,\text{lb/ft}^3$.

Sandy Soil Field Cast Test

Field test result where soil does not form a ball or cast when squeezed in hand, indicating the textural class is Sand.

Soil Ribbon Technique

Field procedure where moist soil is squeezed upward between thumb and forefinger to form a ribbon, measuring how long it extends before breaking from its own weight.

Weak Ribbon

A soil ribbon that is less than $1\text{ inch}$ ($2.5\,cm$) long before breaking.

Medium Ribbon

A soil ribbon that is $1\text{ to }2\text{ inches}$ ($2.5 - 5\,cm$) long before breaking.

Strong Ribbon

A soil ribbon that is $2\text{ inches}$ ($5\,cm$) or longer before breaking.

Characteristic Feel of Sand

Feels gritty.

Characteristic Feel of Silt

Feels smooth and velvety.

Characteristic Feel of Clay

Feels slick and sticky.

High Strength Effluent (HSE)

Wastewater effluent from facilities such as restaurants, food stands, delis, or meat markets that requires using the mean or lower LTAR.