Nebraska Soils Field Trip - Virginia Tech

4th IUSS Soil Classification Conference Field Tour Guidebook
Draft of new section on Artifacts for the National Soil Survey Handbook,
Part 618--Soil Properties and Qualities
618.5 Artifacts in the Soil
A. Definition.—“Artifacts” are objects or materials created or modified by humans, usually for a
practical purpose in habitation, manufacturing, excavation, or construction activities. Examples of
artifacts include bitumen (asphalt), brick, concrete, metal, paper, plastic, rubber, and wood products.
Artifacts are commonly referred to as “discrete artifacts” if they are 2 mm or larger in diameter and
are not compacted into a root-limiting layer that impedes root growth or water movement.
B. Significance.—Artifacts can constitute a significant portion of the soil. The amount and type of
particulate artifacts can contribute substantially to various trace metals and total carbon contents of
soils. Discrete artifacts which are both cohesive and persistent, defined below, are treated in a similar
manner as rock fragments when populating the standard sieves or in calculations involving sieve
entries. Discrete artifacts which are noncohesive, nonpersistent, or both are not considered fragments
for sieve entries or calculations involving those entries.
C. Measurement.—The fraction from 2 to 75 mm in diameter may be measured in the field.
However, 50 to 60 kg of sample material may be necessary if there is an appreciable amount of
fragments near 75 mm. An alternative means of measuring is to visually estimate the volume of the
20 to 75 mm fraction, then sieve and weigh the 2 to 20 mm fraction. The fraction 75 mm (3 inches)
or greater is usually not included in soil samples taken in the field for laboratory testing.
Measurements can be made in the field by weighing the dry sample and the portion retained on a 3inch
screen. The smallest dimension of discrete artifacts is used to determine whether these items
pass through a sieve. The quantity is expressed as a weight percentage of the total soil. A sample as
large as 200 pounds to more than a ton may be needed to assure that the results are representative.
Measurements of the fraction from 75 to 250 mm (3 to 10 inches) and the fraction greater than 250
mm (10 inches) in diameter are usually obtained from volume estimates.
D. Estimates
(1) Estimates of discrete artifacts are made similarly to the way estimates of rock fragments are
made. These estimates are usually made by visual means and are on the basis of percent by
volume. The percent by volume is converted to percent by weight by using the average bulk
unit weights for the soil and the specific artifacts. These estimates are made during
investigation and mapping activities in the field. They are expressed as ranges that include
the estimating accuracy as well as the range of values for a component.
(2) Treated and untreated wood products (e.g., lumber) are considered artifacts. They are not
considered wood fragments such as those associated with the woody materials (e.g., tree
branches) described in organic soils.
(3) Measurements or estimates of discrete artifacts less than strongly cemented are made prior to
any rolling or crushing of the sample.
E. Artifact Cohesion
(1) Definition.—“Artifact Cohesion” is the relative ability of the artifact to remain intact after
significant disturbance.
(2) Significance.—Artifacts that break down easily are similar to pararock fragments in that
these artifacts break down to become part of the fine-earth fraction of the soil. Noncohesive
artifacts are excluded from entries for the standards sieves and are not used in sieve
calculations.
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