Soil Survey of Murray and Whitfield Counties, Georgia

232 Soil Survey
Infiltration. The downward entry of water into the immediate surface of soil or other
material, as contrasted with percolation, which is movement of water through soil
layers or material.
Infiltration capacity. The maximum rate at which water can infiltrate into a soil under
a given set of conditions.
Infiltration rate. The rate at which water penetrates the surface of the soil at any given
instant, usually expressed in inches per hour. The rate can be limited by the
infiltration capacity of the soil or the rate at which water is applied at the surface.
Iron depletions. See Redoximorphic features.
Irrigation. Application of water to soils to assist in production of crops. Methods of
irrigation are:
Basin.—Water is applied rapidly to nearly level plains surrounded by levees or
dikes.
Border.—Water is applied at the upper end of a strip in which the lateral flow of
water is controlled by small earth ridges called border dikes, or borders.
Controlled flooding.—Water is released at intervals from closely spaced field
ditches and distributed uniformly over the field.
Corrugation.—Water is applied to small, closely spaced furrows or ditches in fields
of close-growing crops or in orchards so that it flows in only one direction.
Drip (or trickle).—Water is applied slowly and under low pressure to the surface of
the soil or into the soil through such applicators as emitters, porous tubing, or
perforated pipe.
Furrow.—Water is applied in small ditches made by cultivation implements.
Furrows are used for tree and row crops.
Sprinkler.—Water is sprayed over the soil surface through pipes or nozzles from a
pressure system.
Subirrigation.—Water is applied in open ditches or tile lines until the water table is
raised enough to wet the soil.
Wild flooding.—Water, released at high points, is allowed to flow onto an area
without controlled distribution.
Ksat. See Saturated hydraulic conductivity.
Large stones (in tables). Rock fragments 3 inches (7.6 centimeters) or more across.
Large stones adversely affect the specified use of the soil.
Leaching. The removal of soluble material from soil or other material by percolating
water.
Linear extensibility. Refers to the change in length of an unconfined clod as moisture
content is decreased from a moist to a dry state. Linear extensibility is used to
determine the shrink-swell potential of soils. It is an expression of the volume
change between the water content of the clod at 1 /3- or 1 /10-bar tension (33kPa or
10kPa tension) and oven dryness. Volume change is influenced by the amount and
type of clay minerals in the soil. The volume change is the percent change for the
whole soil. If it is expressed as a fraction, the resulting value is COLE, coefficient
of linear extensibility.
Liquid limit. The moisture content at which the soil passes from a plastic to a liquid
state.
Loam. Soil material that is 7 to 27 percent clay particles, 28 to 50 percent silt particles,
and less than 52 percent sand particles.
Low strength. The soil is not strong enough to support loads.
Masses. See Redoximorphic features.
Medium textured soil. Very fine sandy loam, loam, silt loam, or silt.
Metamorphic rock. Rock of any origin altered in mineralogical composition, chemical
composition, or structure by heat, pressure, and movement at depth in the earth’s
crust. Nearly all such rocks are crystalline.