Virginia Administrative Code › Title 12 - HEALTH › Agency 5 - DEPARTMENT OF HEALTH › Chapter 610 - SEWAGE HANDLING AND DISPOSAL REGULATIONS › Part V - Design and Construction Criteria › Article 11 - Nonpublic Drinking Water Supply Systems Utilized in Conjunction with Onsite Sewage Disposal Systems › Section 12VAC5-610-1170:1 - APPENDIX F. Field Guide To Soil Texture Classes

Current through Register Vol. 40, No. 24, July 15, 2024
Field Guide To Soil Texture Classes (USDA)
Introduction-The purpose of this test is to provide a
						standard procedure for estimating soil texture in the field. The texture is
						estimated by the "feel" of moist soil. The texture of a soil cannot be
						estimated by "feel" if it is either dry or wet.
Definitions
Particle Size Classes
Sand-Sand has a particle size ranging from 0.05
						millimeters (mm) to 2.0 millimeters (mm) in diameter. Sand imparts a gritty
						feel to soil due to the shape of the individual particles.
Silt-Silt has a particle size ranging from 0.002
						millimeters (mm) to 0.05 millimeters (mm) in diameter. When moist, silt has a
						floury feel and does not ribbon when pressed between the thumb and forefinger
						due to the shape of the individual particles. When placed between the teeth
						silt has a gritty feeling.
Clay-Clay has a particle size less than 0.002
						millimeters (mm) in diameter. Clay exhibits collodial properties, has a
						negative charge and is flat and platelike in shape. Moist clay is sticky and
						will ribbon readily when pressed between the thumb and forefinger. When placed
						between the teeth clay has a smooth slick feeling.
Soil Texture-Soil texture refers to the relative
						proportions of sand, silt and clay particles in a soil material that has a
						particle size less than two (2) millimeters (mm) in diameter. Soil texture is
						an indicator of infiltration capacity, permeability, degree of aeration and
						drainage as well as other physical characteristics of a soil material.
Soil Texture Classes-The United States Department of
						Agriculture (USDA) has identified twelve (12) soil texture classes as follows:
						sand, loamy sand, sandy loam, sandy clay loam, loam, silt loam, silt, silty
						clay loam, clay, clay loam, sandy clay and silty clay. Each texture class has a
						distinctive characteristic(s) which can be estimated in the field by trained
						personnel.
Distinguishing Characteristics-The following
						characteristics are based on moist soil.
Sand-Sand has a gritty feel, does not stain the fingers
						and does not form a ball when moist.
Loamy Sand-Loamy sand has a gritty feel, stains the
						fingers (silt and clay) and forms a weak ball but cannot be handled without
						breaking.
Sandy Loam-Sandy loam has a gritty feel, forms a ball
						that can be picked up with the fingers and handled with care without
						breaking.
Loam-Loam may have a slight gritty feel but does not
						show a finger print and forms only short ribbons of from 0.25 inch to 0.50 inch
						in length. Loam will form a ball that can be handled without breaking.
Silt Loam-Silt loam has a floury feel when moist and
						sticky when wet but will not ribbon and forms a ball that will tolerate some
						handling. Silt texture has not been found in any Virginia soils.
Sandy Clay Loam-Sandy clay loam has a gritty feel but
						contains enough clay to form a firm ball and may ribbon to form 0.75 inch to 1
						inch long pieces.
Silty Clay Loam-Silty clay loam is sticky when moist and
						will ribbon from one (1) to two (2) inches. Rubbing silty clay loam with the
						thumb nail produces a moderate sheen. Silty clay loam produces a distinct
						finger print.
Clay Loam-Clay loam is sticky when moist. Clay loam
						forms a thin ribbon of one (1) to two (2) inches in length and produces a
						slight sheet when rubbed with the thumb nail. Clay loam produces a nondistinct
						finger print.
Sandy Clay-Sandy clay is plastic, gritty and stocky when
						moist and both forms a firm ball and produces a thin ribbon to over two (2)
						inches in length.
Silty Clay-Silty clay is both plastic and sticky when
						moist and lacks any gritty feeling. Silty clay forms a firm ball and readily
						ribbons to over two (2) inches in length.
Clay-Clay is both sticky and plastic when moist,
						produces a thin ribbon over two (2) inches in length, produces a high sheen
						when rubbed with the thumb nail and forms a strong ball resistant to
						breaking.