Soil Survey of Grayson County, Texas Page: 52
vii, 141 p., 75 fold. p. of plates : ill., maps ; 29 cm.View a full description of this book.
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SOIL SURVEY
The higher the value the more susceptible the soil is to
sheet and rill erosion by water.
Erosion factor T is an estimate of the maximum aver-
age annual rate of soil erosion by wind or water that can
occur without affecting crop productivity over a sustained
period. The rate is in tons per acre per year.
Wind erodibility groups are made up of soils that have
similar properties affecting their resistance to wind ero-
sion in cultivated areas. The groups indicate the suscep-
tibility of soil to wind erosion and the amount of soil lost.
Soils are grouped according to the following distinctions:
1. Sands, coarse sands, fine sands, and very fine
sands. These soils are generally not suitable for crops.
They are extremely erodible, and vegetation is difficult to
establish.
2. Loamy sands, loamy fine sands, and loamy very
fine sands. These soils are very highly erodible. Crops
can be grown if intensive measures to control wind ero-
sion are used.
3. Sandy loams, coarse sandy loams, fine sandy
loams, and very fine sandy loams. These soils are highly
erodible. Crops can be grown if intensive measures to
control wind erosion are used.
4L. Calcareous loamy soils that are less than 35 per-
cent clay and more than 5 percent finely divided calcium
carbonate. These soils are erodible. Crops can be grown
if intensive measures to control wind erosion are used.
4. Clays, silty clays, clay loams, and silty clay loams
that are more than 35 percent clay. These soils are
moderately erodible. Crops can be grown if measures to
control wind erosion are used.
5. Loamy soils that are less than 18 percent clay and
less than 5 percent finely divided calcium carbonate and
sandy clay loams and sandy clays that are less than 5
percent finely divided calcium carbonate. These soils are
slightly erodible. Crops can be grown if measures to
control wind erosion are used.
6. Loamy soils that are 18 to 35 percent clay and
less than 5 percent finely divided calcium carbonate,
except silty clay loams. These soils are very slightly
erodible. Crops can easily be grown.
7. Silty clay loams that are less than 35 percent clay
and less than 5 percent finely divided calcium carbonate.
These soils are very slightly erodible. Crops can easily
be grown.
8. Stony or gravelly soils and other soils not subject
to wind erosion.
Organic matter is the plant and animal residue in the
soil at various stages of decomposition.
In table 16, the estimated content of organic matter of
the plow layer is expressed as a percentage, by weight,
of the soil material that is less than 2 millimeters in
diameter.
The content of organic matter of a soil can be main-
tained or increased by returning crop residue to the soil.
Organic matter affects the available water capacity, infil-
tration rate, and tilth. It is a source of nitrogen and other
nutrients for crops.Soil and water features
Table 17 gives estimates of various soil and water
features. The estimates are used in land use planning
that involves engineering considerations.
Hydrologic soil groups are used to estimate runoff
from precipitation. Soils not protected by vegetation are
assigned to one of four groups. They are grouped ac-
cording to the intake of water when the soils are thor-
oughly wet and receive precipitation from long-duration
storms.
The four hydrologic soil groups are:
Group A. Soils having a high infiltration rate (low runoff
potential) when thoroughly wet. These consist mainly of
deep, well drained to excessively drained sands or grav-
elly sands. These soils have a high rate of water trans-
mission.
Group B. Soils having a moderate infiltration rate when
thoroughly wet. These consist chiefly of moderately deep
or deep, moderately well drained or well drained soils
that have moderately fine texture to moderately coarse
texture. These soils have a moderate rate of water trans-
mission.
Group C. Soils having a slow infiltration rate when
thoroughly wet. These consist chiefly of soils having a
layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These
soils have a slow rate of water transmission.
Group D. Soils having a very slow infiltration rate (high
runoff potential) when thoroughly wet. These consist
chiefly of clays that have a high shrink-swell potential,
soils that have a permanent high water table, soils that
have a claypan or clay layer at or near the surface, and
soils that are shallow over nearly impervious material.
These soils have a very slow rate of water transmission.
Flooding, the temporary inundation of an area, is
caused by overflowing streams, by runoff from adjacent
slopes, or by tides. Water standing for short periods after
rainfall or snowmelt and water in swamps and marshes
is not considered flooding.
Table 17 gives the frequency and duration of flooding
and the time of year when flooding is most likely.
Frequency, duration, and probable dates of occurrence
are estimated. Frequency is expressed as none, rare,
common, occasional, and frequent. None means that
flooding is not probable; rare that it is unlikely but possi-
ble under unusual weather conditions; common that it is
likely under normal conditions; occasional that it occurs
on an average of once or less in 2 years; and frequent
that it occurs on an average of more than once in 2
years. Duration is expressed as very brief if less than 2
days, brief if 2 to 7 days, and long if more than 7 days.
Probable dates are expressed in months; November-
May, for example, means that flooding can occur during
the period November through May.
The information is based on evidence in the soil pro-
file, namely thin strata of gravel, sand, silt, or clay depos-
ited by floodwater; irregular decrease in organic matter52
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General Soil Map, Grayson County, Texas (Map)
Map displays soil types along with creeks, towns, schools, churches, power transmission lines, oil and gas pipelines, roads, and railroads. Includes legend and symbols. Scale 1:253,400
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Cochran, Rex; Cail, Charles & Putnam, Lee. Soil Survey of Grayson County, Texas, book, 1980; Washington D.C.. (https://texashistory.unt.edu/ark:/67531/metapth130218/m1/62/: accessed May 21, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu; crediting UNT Libraries Government Documents Department.