[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

Reaction soil A measure of acidity or alkalinity of a soil, expressed in pH values. A soils that tests to pH 70 is described as precisely neutral in reaction because it is neither acid nor alkaline.

Regolith The unconsolidated mantle of weathered rock and soil material on the earth's surface, the loose earth material above the solid rock.

Relief The elevations or inequalities of a land surface, considered collectively.

Residuum (residual soil material) Unconsolidated, weathered or partly weathered mineral material that accumulated as consolidated rock disintegrated in place.

Ridge A long, narrow elevation of the land surface, usually sharply crested with steep sides forming and extended upland between valleys.

Rill A steep-sided channel resulting from accelerated erosion. A rill is generally a few inches deep and not wide enough to be an obstacle to farm machinery.

Rippable Bedrock or hardpan can be excavated using a single-tooth ripping attachment mounted on a tractor with a 200-300 draw bar horsepower rating.

Rock fragments Rock or mineral fragments having a diameter of 2 millimeters or more. For example, pebbles, cobbles, stones, and boulders.

Root zone The part of the soil that can be penetrated by plant roots.

Rooting depth Shallow root zone The soil is shallow over a layer that greatly restricts roots.

Runoff The precipitation discharged into stream channels from an area. The water that flows off the surface of the land without sinking into the soil is called surface runoff. Water that enters the soil before reaching surface streams is called ground-water runoff or seepage flow from ground water.

Reaction soil	A measure of acidity or alkalinity of a soil, expressed in pH values. A soils that tests to pH 70 is described as precisely neutral in reaction because it is neither acid nor alkaline.
Regolith	The unconsolidated mantle of weathered rock and soil material on the earth's surface, the loose earth material above the solid rock.
Relief	The elevations or inequalities of a land surface, considered collectively.
Residuum (residual soil material)	Unconsolidated, weathered or partly weathered mineral material that accumulated as consolidated rock disintegrated in place.
Ridge	A long, narrow elevation of the land surface, usually sharply crested with steep sides forming and extended upland between valleys.
Rill	A steep-sided channel resulting from accelerated erosion. A rill is generally a few inches deep and not wide enough to be an obstacle to farm machinery.
Rippable	Bedrock or hardpan can be excavated using a single-tooth ripping attachment mounted on a tractor with a 200-300 draw bar horsepower rating.
Rock fragments	Rock or mineral fragments having a diameter of 2 millimeters or more. For example, pebbles, cobbles, stones, and boulders.
Root zone	The part of the soil that can be penetrated by plant roots.
Rooting depth	Shallow root zone The soil is shallow over a layer that greatly restricts roots.
Runoff	The precipitation discharged into stream channels from an area. The water that flows off the surface of the land without sinking into the soil is called surface runoff. Water that enters the soil before reaching surface streams is called ground-water runoff or seepage flow from ground water.