[The Cooperative Soil Survey] Soils Tutorial: Glossary

Glossary

Definitions from the Soil Science Society of America (SSSA)

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Sand As a soil separate, individual rock or mineral fragments from 005 millimeter to 20 millimeters in diameter. Most sand grains consist of quartz As a soil textural class, a soil that is 85 percent or more sand and not more than 10 percent clay.

Sandstone Sedimentary rock containing dominantly sand-sized particles.

Sapric soil material (muck) The most highly decomposed of all organic soil material. Muck has the least amount of plant fiber, the highest bulk density, and the lowest water content at saturation of all organic soil material.

Sedimentary rock Rock made up of particles deposited from suspension in water. The chief kinds of sedimentary rock are conglomerate, formed from gravel

Seepage The movement of water through the soil Seepage adversely affects the specified use.

Sequum A sequence consisting of an illuvial horizon and the overlying eluvial horizon (See Eluviation).

Series soil A group of soils that have profiles that are almost alike, except for differences in texture of the surface layer or of the substratum. All the soils of a series have horizons that are similar in composition, thickness, and arrangement.

Shale Sedimentary rock formed by the hardening of a clay deposit.

Sheet erosion The removal of a fairly uniform layer of soil material from the land surface by the action of rainfall and surface runoff.

Shoulder The uppermost inclined surface at the top of a hillslope. The area comprises the transitional zone from the back slope to the summit of an upland. The surface is dominantly convex in profile and erosional in origin.

Shrink-swell The shrinking of soil when dry and the swelling when wet. Shrinking and swelling can damage roads, dams, building foundations, and other structures. It can also damage plant roots.

Side slope The slope bounding a drainageway and lying between the drainageway and the adjacent interfluve. A side slope is generally linear along the slope width, and overland flow is parallel down the slope.

Silica A combination of silicon and oxygen. The mineral form is called quartz.

Silica-sesquioxide ratio The ratio of the number of molecules of silica to the number of molecules of alumina and iron oxide. The more highly weathered soils or their clay fractions in warm-temperate, humid regions, and especially those in the tropics, generally have a low ratio.

Silt As a soil separate, individual mineral particles that range in diameter from the upper limit of clay (0002 millimeter) to the lower limit of very fine sand (005 millimeter). As a soil textural class, soil that is 80 percent or more silt and less than 12 percent clay.

Siltstone Sedimentary rock made up of dominantly silt-sized particles.

Similar soils Soils that share limits of diagnostic criteria, behave and perform in a similar manner, and have similar conservation needs or management requirements for the major land uses in the survey area.

Sinkhole A depression in the landscape where limestone has been dissolved.

Site index A designation of the quality of a forest site based on the height of the dominant stand at an arbitrarily chosen age For example, if the average height attained by dominant and codominant trees in a fully stocked stand at the age of 50 years is 75 feet, the site index is 75 feet.

Slope The inclination of the land surface from the horizontal. Percentage of slope is the vertical distance divided by horizontal distance, then multiplied by 100. Thus, a slope of 20 percent is a drop of 20 feet in 100 feet of horizontal distance.

Slope (in tables) Slope is great enough that special practices are required to ensure satisfactory performance of the soil for a specific use.

Slow intake The slow movement of water into the soil.

Slow refill The slow filling of ponds, resulting from restricted permeability in the soil.

Small stones Rock fragments less than 3 inches (76 centimeters) in diameter. Small stones adversely affect the specified use of the soil.

Soil A natural, three-dimensional body at the earth's surface. It is capable of supporting plants and has properties resulting from the integrated effect of climate and living matter acting on earthy parent material, as conditioned by relief over periods of time.

Soil separates Mineral particles less than 2 millimeters in equivalent diameter and ranging between specified size limits.

Solum The upper part of a soil profile, above the C horizon, in which the processes of soil formation are active. The solum in soil consists of the A, E, and B horizons. Generally, the characteristics of the material in these horizons are unlike those of the underlying material. The living roots and plant and animal activities are largely confined to the solum.

Stone line A concentration of coarse fragments in a soil. Generally, it is indicative of an old weathered surface. In a cross section, the line may be one fragment or more thick. It generally overlies material that weathered in place and is overlain by recent sediment of variable thickness.

Stones Rock fragments 10 to 24 inches (25 to 60 centimeters) in diameter.

Stony Refers to a soil containing stones in numbers that interfere with or prevent tillage.

Stratified Arranged in strata, or layers. The term refers to geologic material Layers in soils that result from the processes of soil formation are called horizons. Those inherited from the parent material are called strata.

Stripcropping Growing crops in a systematic arrangement of strips or bands which provide vegetative barriers to soil blowing and water erosion.

Structure, soil The arrangement of primary soil particles into compound particles or aggregates. The principal forms of soil structure are-platy (laminated), prismatic (vertical axis of aggregates longer than horizontal), columnar (prisms with rounded tops), blocky (angular or subangular), and granular. Structureless soils are either single grain (each grain by itself, as in dune sand) or massive (the particles adhering without any regular cleavage, as in many hardpans).

Stubble mulch Stubble or other crop residue left on the soil or partly worked into the soil. It protects the soil from soil blowing and water erosion after harvest, during preparation of a seedbed for the next crop and during the early growing period of the new crop.

Subsoil Technically, the B horizon roughly, the part of the soil below plow depth.

Subsoiling Breaking up a compact subsoil by pulling a special chisel through the soil.

Substratum The part of the soil below the solum.

Subsurface layer Any surface soil horizon (A, E, AB, or EB) below the surface layer.

Summer fallow The tillage of uncropped land during the summer to control weeds and allow storage of moisture in the soil for the growth of a later crop. A practice common in semiarid regions, where annual precipitation is not enough to produce a crop every year. Summer fallow is frequently practiced before planting winter grain.

Summit A general term for the top or highest level of an upland feature such as a ridge or hill.

Surface layer The soil ordinarily moved in tillage, or its equivalent in uncultivated soil, ranging in depth from about 4 to 10 inches (10 to 25 centimeters). Frequently designated as the "plow layer" or the "Ap horizon."

Surface soil The A, E, AB, and EB horizons It includes all subdivisions of these horizons.

Sand	As a soil separate, individual rock or mineral fragments from 005 millimeter to 20 millimeters in diameter. Most sand grains consist of quartz As a soil textural class, a soil that is 85 percent or more sand and not more than 10 percent clay.
Sandstone	Sedimentary rock containing dominantly sand-sized particles.
Sapric soil material (muck)	The most highly decomposed of all organic soil material. Muck has the least amount of plant fiber, the highest bulk density, and the lowest water content at saturation of all organic soil material.
Sedimentary rock	Rock made up of particles deposited from suspension in water. The chief kinds of sedimentary rock are conglomerate, formed from gravel
Seepage	The movement of water through the soil Seepage adversely affects the specified use.
Sequum	A sequence consisting of an illuvial horizon and the overlying eluvial horizon (See Eluviation).
Series soil	A group of soils that have profiles that are almost alike, except for differences in texture of the surface layer or of the substratum. All the soils of a series have horizons that are similar in composition, thickness, and arrangement.
Shale	Sedimentary rock formed by the hardening of a clay deposit.
Sheet erosion	The removal of a fairly uniform layer of soil material from the land surface by the action of rainfall and surface runoff.
Shoulder	The uppermost inclined surface at the top of a hillslope. The area comprises the transitional zone from the back slope to the summit of an upland. The surface is dominantly convex in profile and erosional in origin.
Shrink-swell	The shrinking of soil when dry and the swelling when wet. Shrinking and swelling can damage roads, dams, building foundations, and other structures. It can also damage plant roots.
Side slope	The slope bounding a drainageway and lying between the drainageway and the adjacent interfluve. A side slope is generally linear along the slope width, and overland flow is parallel down the slope.
Silica	A combination of silicon and oxygen. The mineral form is called quartz.
Silica-sesquioxide ratio	The ratio of the number of molecules of silica to the number of molecules of alumina and iron oxide. The more highly weathered soils or their clay fractions in warm-temperate, humid regions, and especially those in the tropics, generally have a low ratio.
Silt	As a soil separate, individual mineral particles that range in diameter from the upper limit of clay (0002 millimeter) to the lower limit of very fine sand (005 millimeter). As a soil textural class, soil that is 80 percent or more silt and less than 12 percent clay.
Siltstone	Sedimentary rock made up of dominantly silt-sized particles.
Similar soils	Soils that share limits of diagnostic criteria, behave and perform in a similar manner, and have similar conservation needs or management requirements for the major land uses in the survey area.
Sinkhole	A depression in the landscape where limestone has been dissolved.
Site index	A designation of the quality of a forest site based on the height of the dominant stand at an arbitrarily chosen age For example, if the average height attained by dominant and codominant trees in a fully stocked stand at the age of 50 years is 75 feet, the site index is 75 feet.
Slope	The inclination of the land surface from the horizontal. Percentage of slope is the vertical distance divided by horizontal distance, then multiplied by 100. Thus, a slope of 20 percent is a drop of 20 feet in 100 feet of horizontal distance.
Slope (in tables)	Slope is great enough that special practices are required to ensure satisfactory performance of the soil for a specific use.
Slow intake	The slow movement of water into the soil.
Slow refill	The slow filling of ponds, resulting from restricted permeability in the soil.
Small stones	Rock fragments less than 3 inches (76 centimeters) in diameter. Small stones adversely affect the specified use of the soil.
Soil	A natural, three-dimensional body at the earth's surface. It is capable of supporting plants and has properties resulting from the integrated effect of climate and living matter acting on earthy parent material, as conditioned by relief over periods of time.
Soil separates	Mineral particles less than 2 millimeters in equivalent diameter and ranging between specified size limits.
Solum	The upper part of a soil profile, above the C horizon, in which the processes of soil formation are active. The solum in soil consists of the A, E, and B horizons. Generally, the characteristics of the material in these horizons are unlike those of the underlying material. The living roots and plant and animal activities are largely confined to the solum.
Stone line	A concentration of coarse fragments in a soil. Generally, it is indicative of an old weathered surface. In a cross section, the line may be one fragment or more thick. It generally overlies material that weathered in place and is overlain by recent sediment of variable thickness.
Stones	Rock fragments 10 to 24 inches (25 to 60 centimeters) in diameter.
Stony	Refers to a soil containing stones in numbers that interfere with or prevent tillage.
Stratified	Arranged in strata, or layers. The term refers to geologic material Layers in soils that result from the processes of soil formation are called horizons. Those inherited from the parent material are called strata.
Stripcropping	Growing crops in a systematic arrangement of strips or bands which provide vegetative barriers to soil blowing and water erosion.
Structure, soil	The arrangement of primary soil particles into compound particles or aggregates. The principal forms of soil structure are-platy (laminated), prismatic (vertical axis of aggregates longer than horizontal), columnar (prisms with rounded tops), blocky (angular or subangular), and granular. Structureless soils are either single grain (each grain by itself, as in dune sand) or massive (the particles adhering without any regular cleavage, as in many hardpans).
Stubble mulch	Stubble or other crop residue left on the soil or partly worked into the soil. It protects the soil from soil blowing and water erosion after harvest, during preparation of a seedbed for the next crop and during the early growing period of the new crop.
Subsoil	Technically, the B horizon roughly, the part of the soil below plow depth.
Subsoiling	Breaking up a compact subsoil by pulling a special chisel through the soil.
Substratum	The part of the soil below the solum.
Subsurface layer	Any surface soil horizon (A, E, AB, or EB) below the surface layer.
Summer fallow	The tillage of uncropped land during the summer to control weeds and allow storage of moisture in the soil for the growth of a later crop. A practice common in semiarid regions, where annual precipitation is not enough to produce a crop every year. Summer fallow is frequently practiced before planting winter grain.
Summit	A general term for the top or highest level of an upland feature such as a ridge or hill.
Surface layer	The soil ordinarily moved in tillage, or its equivalent in uncultivated soil, ranging in depth from about 4 to 10 inches (10 to 25 centimeters). Frequently designated as the "plow layer" or the "Ap horizon."
Surface soil	The A, E, AB, and EB horizons It includes all subdivisions of these horizons.