Soil Survey of Jackson County, Texas Page: 65
vii, 147, [2] p., 50 folded p. of plates : ill., maps (some col.) ; 28 cm.View a full description of this book.
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65
Classification of the Soils
The system of soil classification used by the National
Cooperative Soil Survey has six categories (25).
Beginning with the broadest, these categories are the
order, suborder, great group, subgroup, family, and
series. Classification is based on soil properties
observed in the field or inferred from those observations
or on laboratory measurements. Table 21 shows the
classification of the soils in the survey area. The
categories are defined in the following paragraphs.
ORDER. Eleven soil orders are recognized. The
differences among orders reflect the dominant soil-
forming processes and the degree of soil formation.
Each order is identified by a word ending in sol. An
example is Alfisol.
SUBORDER. Each order is divided into suborders,
primarily on the basis of properties that influence soil
genesis and are important to plant growth or properties
that reflect the most important variables within the
orders. The last syllable in the name of a suborder
indicates the order. An example is Aqualf (Aqu,
meaning water, plus alf, from Alfisol).
GREAT GROUP. Each suborder is divided into great
groups on the basis of close similarities in kind,
arrangement, and degree of development of pedogenic
horizons; soil moisture and temperature regimes; and
base status. Each great group is identified by the name
of a suborder and by a prefix that indicates a property
of the soil. An example is Epiaqualf (Epi, meaning
saturated with water near the surface, plus aqualf, the
suborder of the Alfisols that has an aquic moisture
regime).
SUBGROUP. Each great group has a typic subgroup.
Other subgroups are intergrades or extragrades. The
typic is the central concept of the great group; it is not
necessarily the most extensive. Intergrades are
transitions to other orders, suborders, or great groups.
Extragrades have some properties that are not
representative of the great group but do not indicate
transitions to any other known kind of soil. Each
subgroup is identified by one or more adjectives
preceding the name of the great group. The adjective
Typic identifies the subgroup that typifies the great
group. An example is Typic Epiaqualfs.FAMILY. Families are established within a subgroup
on the basis of physical and chemical properties and
other characteristics that affect management. Generally,
the properties are those of horizons below plow depth
where there is much biological activity. Among the
properties and characteristics considered are particle-
size class, mineral content, temperature regime, depth
of the root zone, consistence, moisture equivalent,
slope, and permanent cracks. A family name consists of
the name of a subgroup preceded by terms that indicate
soil properties. An example is fine-loamy, siliceous,
hyperthermic Typic Epiaqualfs.
SERIES. The series consists of soils that have
similar horizons in their profile. The horizons are similar
in color, texture, structure, reaction, consistence,
mineral and chemical composition, and arrangement in
the profile. There can be some variation in the texture
of the surface layer or of the underlying material within
a series.
Soil Series and Their Morphology
In this section, each soil series recognized in the
survey area is described. The descriptions are arranged
in alphabetic order.
Characteristics of the soil and the material in which it
formed are identified for each series. A pedon, a small
three-dimensional area of soil, that is typical of the
series in the survey area is described. The detailed
description of each soil horizon follows standards in the
"Soil Survey Manual" (28). Many of the technical terms
used in the descriptions are defined in "Soil Taxonomy"
(20). Unless otherwise stated, colors in the descriptions
are for moist soil. Following the pedon description is the
range of important characteristics of the soils in the
series.
The map units of each soil series are described in
the section "Detailed Soil Map Units."
Aransas Series
The Aransas series consists of very deep, very
slowly permeable, poorly drained clayey soils on flood
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Miller, Wesley L. Soil Survey of Jackson County, Texas, book, May 1997; Washington D.C.. (https://texashistory.unt.edu/ark:/67531/metapth224539/m1/75/: accessed April 24, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu; crediting UNT Libraries Government Documents Department.