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March 11 , 2020
Preface
Soil surveys contain information that affects land use planning in survey areas.
They highlight soil limitations that affect various land uses and provide information
about the properties of the soils in the survey areas . Soil surveys are designed for
many different users , including farmers , ranchers , foresters , agronomists , urban
planners , community officials , engineers , developers , builders , and home buyers .
Also, conservationists , teachers , students , and specialists in recreation , waste
disposal , and pollution control can use the surveys to help them understand ,
protect, or enhance the environment.
Various land use regulations of Federal , State , and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil
properties that are used in making various land use or land treatment decisions .
The information is intended to help the land users identify and reduce the effects of
soil limitations on various land uses . The landowner or user is responsible for
identifying and complying with existing laws and regulations .
Although soil survey information can be used for general farm , local , and wider area
planning , onsite investigation is needed to supplement this information in some
cases . Examples include soil quality assessments (http://www. nres. usda .gavlwpsl
portal/n reslm ain/so i l sf health/) and certain conservation and engineering
applications . For more detailed information , contact your local USDA Service Center
(https ://offices .sc. egov. usda .govllacatorlapp?agency=arcs) or your N RCS State Soil
Scientist (http ://www. nres .0 sda.gov/wps/portal/nresfd etail/soils/contactu sl?
cid =nres142p2_053951 ).
Great differences in soil properties can occur within short distances . Some soils are
seasonally wet or subject to flooding . Some are too unstable to be used as a
foundation for buildings or roads . Clayey or wet soils are poorly suited to use as
septic tank absorption fields . A high water table makes a soil poorly suited to
basements or underground installations .
The National Cooperative Soil Survey is a joint effort of the United States
Department of Agriculture and other Federal agencies, State agencies including the
Agricultural Experiment Stations, and local agencies . The Natural Resources
Conservation Service (NRCS) has leadership for the Federal part of the National
Cooperative Soil Survey.
Information about soils is updated periodically. Updated information is available
through the N RCS Web Soil Survey, the site for official soil survey information .
The U . S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, color, national origin , age, disability,
and where applicable , sex, marital status , familial status , parental status , religion ,
sexual orientation , genetic information , political beliefs , reprisal , or because all or a
part of an individual's income is derived from any public assistance program . (Not
all prohibited bases apply to all programs . ) Persons with disabilities who require
2
alternative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice
and TDD ) . To file a complaint of discrimination , write to USDA, Director, Office of
Civil Rights , 1400 Independence Avenue , S .W. , Washington , D . C . 20250-9410 or
call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity
provider and employer.
3
Contents
Preface 2
How Soil Surveys Are Made 5
Soil Map 8
Soil Map 9
Legend 10
Map Unit Legend 11
Map Unit Descriptions 11
Weld County, Colorado, Southern Part 13
46—Olney fine sandy loam , 0 to 1 percent slopes 13
47 Olney fine sandy loam , 1 to 3 percent slopes 14
72 Vona loamy sand , 0 to 3 percent slopes 15
Soil Information for All Uses 17
Soil Reports 17
Building Site Development 17
Dwellings and Small Commercial Buildings 17
Roads and Streets , Shallow Excavations , and Lawns and Landscaping 19
Construction Materials 21
Source of Reclamation Material , Roadfill , and Topsoil 21
Source of Sand and Gravel 23
Soil Health 25
Soil Health - Aggregate Stability (West US) 25
Soil Health - Compaction , Surface Sealing 28
Soil Physical Properties 30
Engineering Properties 30
Soil Qualities and Features 35
Soil Features 35
Water Features 38
Hydrologic Soil Group and Surface Runoff 38
Water Features 39
Water Management 42
Irrigation - Surface 42
Ponds and Embankments 44
References 47
4
■
How Soil Surveys
Soil surveys are made to provide information about the soils and miscellaneous
areas in a specific area . They include a description of the soils and miscellaneous
areas and their location on the landscape and tables that show soil properties and
limitations affecting various uses . Soil scientists observed the steepness , length ,
and shape of the slopes ; the general pattern of drainage; the kinds of crops and
native plants ; and the kinds of bedrock . They observed and described many soil
profiles . A soil profile is the sequence of natural layers , or horizons , in a soil . The
profile extends from the surface down into the unconsolidated material in which the
soil formed or from the surface down to bedrock. The unconsolidated material is
devoid of roots and other living organisms and has not been changed by other
biological activity.
Currently, soils are mapped according to the boundaries of major land resource
areas ( MLRAs). MLRAs are geographically associated land resource units that
share common characteristics related to physiography, geology, climate , water
resources , soils , biological resources , and land uses (USDA, 2006). Soil survey
areas typically consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that
is related to the geology, landforms, relief, climate , and natural vegetation of the
area . Each kind of soil and miscellaneous area is associated with a particular kind
of landform or with a segment of the landform . By observing the soils and
miscellaneous areas in the survey area and relating their position to specific
segments of the landform , a soil scientist develops a concept, or model , of how they
were formed . Thus , during mapping , this model enables the soil scientist to predict
with a considerable degree of accuracy the kind of soil or miscellaneous area at a
specific location on the landscape .
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles . Nevertheless , these observations , supplemented
by an understanding of the soil-vegetation-landscape relationship , are sufficient to
verify predictions of the kinds of soil in an area and to determine the boundaries .
Soil scientists recorded the characteristics of the soil profiles that they studied . They
noted soil color, texture , size and shape of soil aggregates , kind and amount of rock
fragments , distribution of plant roots , reaction , and other features that enable them
to identify soils. After describing the soils in the survey area and determining their
properties , the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts . Each taxonomic class has a set of soil
characteristics with precisely defined limits . The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States , is based mainly on the kind and character
of soil properties and the arrangement of horizons within the profile . After the soil
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Custom Soil Resource Report
scientists classified and named the soils in the survey area, they compared the
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research .
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that
have similar use and management requirements . Each map unit is defined by a
unique combination of soil components and/or miscellaneous areas in predictable
proportions . Some components may be highly contrasting to the other components
of the map unit. The presence of minor components in a map unit in no way
diminishes the usefulness or accuracy of the data . The delineation of such
landforms and landform segments on the map provides sufficient information for the
development of resource plans . If intensive use of small areas is planned , onsite
investigation is needed to define and locate the soils and miscellaneous areas .
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors , including scale of
mapping , intensity of mapping , design of map units , complexity of the landscape,
and experience of the soil scientist. Observations are made to test and refine the
soil-landscape model and predictions and to verify the classification of the soils at
specific locations . Once the soil-landscape model is refined , a significantly smaller
number of measurements of individual soil properties are made and recorded .
These measurements may include field measurements , such as those for color,
depth to bedrock, and texture , and laboratory measurements , such as those for
content of sand , silt, clay, salt, and other components. Properties of each soil
typically vary from one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented . Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties .
While a soil survey is in progress , samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests . Soil scientists
interpret the data from these analyses and tests as well as the field-observed
characteristics and the soil properties to determine the expected behavior of the
soils under different uses . Interpretations for all of the soils are field tested through
observation of the soils in different uses and under different levels of management.
Some interpretations are modified to fit local conditions , and some new
interpretations are developed to meet local needs . Data are assembled from other
sources, such as research information , production records , and field experience of
specialists . For example, data on crop yields under defined levels of management
are assembled from farm records and from field or plot experiments on the same
kinds of soil .
Predictions about soil behavior are based not only on soil properties but also on
such variables as climate and biological activity. Soil conditions are predictable over
long periods of time , but they are not predictable from year to year. For example ,
soil scientists can predict with a fairly high degree of accuracy that a given soil will
have a high water table within certain depths in most years, but they cannot predict
that a high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
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Custom Soil Resource Report
identified each as a specific map unit. Aerial photographs show trees, buildings ,
fields , roads , and rivers , all of which help in locating boundaries accurately.
7
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of
soil map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map , and a description of each soil map unit.
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Custom Soil Resource Report
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Custom Soil Resource Report
MAP LEGEND MAP INFORMATION
Area of Interest (AOl) IN Spoil Area The soil surveys that comprise your AOI were mapped at
Area of Interest (AOI) 1 :24,000.
Stony Spot
Soils Very Stony Spot
Soil Map Unit Polygons Warning : Soil Map may not be valid at this scale..
V. Wet Spot
Lj Soil Map Unit Lines
Other Enlargement of maps beyond the scale of mapping can cause
Soil Map Unit Points misunderstanding of the detail of mapping and accuracy of soil
Special Line Features line placement. The maps do not show the small areas of
Special Point Features contrasting soils that could have been shown at a more detailed
lull Blowout Water Features scale.
Streams and Canals
r4 Borrow Pit
Transportation Please rely on the bar scale on each map sheet for map
Clay Spot
Rails measurements .
Closed Depression
Interstate Highways
Source of Map: Natural Resources Conservation Service
FX Gravel Pit US Routes Web Soil Survey URL:
Gravelly Spot Coordinate System : Web Mercator (EPSG :3857)
Major Roads
Landfill Local Roads Maps from the Web Soil Survey are based on the Web Mercator
ss. Lava Flow projection, which preserves direction and shape but distorts
Background distance and area. A projection that preserves area, such as the
Marsh or swamp 1 Aerial Photography Albers equal-area conic projection , should be used if more
* Mine or Quarry accurate calculations of distance or area are required .
Miscellaneous Water This product is generated from the USDA-NRCS certified data as
Perennial Water of the version date(s) listed below.
Rock Outcrop Soil Survey Area: Weld County, Colorado, Southern Part
Saline Spot Survey Area Data: Version 18, Sep 13, 2019
. 4.O Sandy Spot
9 0 Soil map units are labeled (as space allows) for map scales
,e Severely Eroded Spot 1 :50,000 or larger.
Sinkhole Date(s) aerial images were photographed : Sep 20, 2015—Dec
31, Slide or Slip 4, 2018
Sodic Spot The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps . As a result, some minor
shifting of map unit boundaries may be evident.
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Custom Soil Resource Report
Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
46 Olney fine sandy loam, 0 to 1 1 .8 3 . 1 %
percent slopes
47 Olney fine sandy loam, 1 to 3 44.9 76 .4%
percent slopes
72 Vona loamy sand, 0 to 3 12.0 20 .5%
percent slopes
Totals for Area of Interest 58.7 100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area . The map unit descriptions , along
with the maps , can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas . A map unit is identified and named
according to the taxonomic classification of the dominant soils . Within a taxonomic
class there are precisely defined limits for the properties of the soils . On the
landscape , however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena . Thus , the range of some
observed properties may extend beyond the limits defined for a taxonomic class .
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes . Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils .
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting , or similar, components . They may or may not be mentioned in a
particular map unit description . Other minor components , however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting , or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used . Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps . If included in the database for a
given area , the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each . A few areas of minor
components may not have been observed , and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape .
The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
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Custom Soil Resource Report
landform segments that have similar use and management requirements . The
delineation of such segments on the map provides sufficient information for the
development of resource plans . If intensive use of small areas is planned , however,
onsite investigation is needed to define and locate the soils and miscellaneous
areas .
An identifying symbol precedes the map unit name in the map unit descriptions .
Each description includes general facts about the unit and gives important soil
properties and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major
horizons that are similar in composition , thickness , and arrangement.
Soils of one series can differ in texture of the surface layer, slope , stoniness ,
salinity, degree of erosion , and other characteristics that affect their use. On the
basis of such differences, a soil series is divided into soil phases. Most of the areas
shown on the detailed soil maps are phases of soil series . The name of a soil phase
commonly indicates a feature that affects use or management. For example, Alpha
silt loam , 0 to 2 percent slopes, is a phase of the Alpha series .
Some map units are made up of two or more major soils or miscellaneous areas .
These map units are complexes , associations , or undifferentiated groups .
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps .
The pattern and proportion of the soils or miscellaneous areas are somewhat similar
in all areas . Alpha-Beta complex, 0 to 6 percent slopes , is an example .
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps . Because of present
or anticipated uses of the map units in the survey area, it was not considered
practical or necessary to map the soils or miscellaneous areas separately. The
pattern and relative proportion of the soils or miscellaneous areas are somewhat
similar. Alpha- Beta association , 0 to 2 percent slopes , is an example .
An undifferentiated group is made up of two or more soils or miscellaneous areas
that could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion
of the soils or miscellaneous areas in a mapped area are not uniform . An area can
be made up of only one of the major soils or miscellaneous areas , or it can be made
up of all of them . Alpha and Beta soils , 0 to 2 percent slopes , is an example .
Some surveys include miscellaneous areas. Such areas have little or no soil
material and support little or no vegetation . Rock outcrop is an example .
12
Custom Soil Resource Report
Weld County, Colorado , Southern Part
46 Olney fine sandy loam , 0 to 1 percent slopes
Map Unit Setting
National map unit symbol: 362t
Elevation: 4, 600 to 5,200 feet
Mean annual precipitation: 11 to 15 inches
Mean annual air temperature: 46 to 54 degrees F
Frost-free period: 125 to 175 days
Farmland classification: Prime farmland if irrigated and the product of I (soil
erodibility) x C (climate factor) does not exceed 60
Map Unit Composition
Olney and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Olney
Setting
Landform: Plains
Down slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed deposit outwash
Typical profile
- 0 to 10 inches: fine sandy loam
H2 - 10 to 20 inches: sandy clay loam
H3 20 to 25 inches: sandy clay loam
144 - 25 to 60 inches: fine sandy loam
Properties and qualities
Slope: 0 to 1 percent
Depth to restrictive feature : More than 80 inches
Natural drainage class: Well drained
Runoff class: Low
Capacity of the most limiting layer to transmit water (} sat) : Moderately high to
high (0 . 57 to 2 . 00 inlhr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 15 percent
salinity maximum in profile: Nonsaline to very slightly saline (0 .0 to 2 . 0
mrnhoslcm)
Available water storage in profile: Moderate (about 7 .0 inches)
Interpretive groups
Land capability classification (`irrigated): 3e
Land capability classification (nonirrigated): 4c
Hydrologic Soil Group: B
Ecological site: Sandy Plains (R067BY024CO)
Hydric soil rating: No
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Custom Soil Resource Report
Minor Components
Zigweid
d
Percent of map unit: 8 percent
Hydric soil rating: No
Vona
Percent of map unit: 7 percent
Hydric soil rating: No
47—Olney fine sandy loam , 1 to 3 percent slopes
Map Unit Setting
National map unit symbol: 362v
Elevation: 4, 600 to 5,200 feet
Mean annual precipitation: 11 to 15 inches
Mean annual air temperature: 46 to 54 degrees F
Frost-free period: 125 to 175 days
Farmland classification: Prime farmland if irrigated and the product of I (soil
erodibility)b ility) x C (climate factor) does not exceed 60
Map Unit Composition
Olney and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transacts of the mapunit.
Description of Olney
Setting
Landform: Plains
Down-slope shape: Linear
Across -slope shape: Linear
Parent material: Mixed deposit outwash
Typical profile
HI - 0 to 10 inches: fine sandy loam
H2 - 10 to 20 inches: sandy clay loam
H3 - 20 to 25 inches: sandy clay loam
1-14 - 25 to 60 inches: fine sandy loam
Properties and qualities
Slope: 1 to 3 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Low
Capacity of the most limiting layer to transmit water sat, : Moderately high to
high (0 . 57 to 2 . 00 in/hi)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
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Custom Soil Resource Report
Calcium carbonate, maximum in profile: 15 percent
Salinity, maximum in profile : Nonsaline to very slightly saline (0 .0 to 2 . 0
mmhosicm )
Available water storage in profile: Moderate (about 7 .0 inches)
Interpretive groups
Land capability classification (irrigated): 3e
Land capability classification (nonirrigated): 4c
Hydrologic Soil Group: B
Ecological site: Sandy Plains (R067BY024CO)
Hydric soil rating: No
Minor Components
Zigweid
d
Percent of map unit: 10 percent
Hydric soil rating: No
Vona
Percent of map unit: 5 percent
Hydric soil rating: No
72 Vona loamy sand , 0 to percent lopes
Map Unit Setting
National map unit symbol: 363r
Elevation: 4,600 to 5,200 feet
Mean annual precipitation. 13 to 15 inches
Mean annual air temperature: 48 to 55 degrees F
Frost-free period: 130 to 160 days
Farmland classification: Farmland of local importance
Map Unit Composition
Vona and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Vona
Setting
Landform: Terraces , plains
Down-slope shape: Linear
Across-slope shape : Linear
Parent material: Alluvium and/or eolian deposits
Typical profile
Hal - 0 to 6 inches: loamy sand
H2 - 6 to 28 inches: fine sandy loam
H3 - 28 to 60 inches: sandy loam
Properties and qualities
Slope: 0 to 3 percent
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Custom Soil Resource Report
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Very low
Capacity of the most limiting layer to transmit water (Ksat) : High ( 1 . 98 to 6. 00
inlhr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 15 percent
salinity, maximum in profile: Nonsaline to slightly saline (0. 0 to 4 . 0 mmhos/cm)
Available water storage in profile: Moderate (about 6 .5 inches)
interpretive groups
Land capability classification (irrigated): Se
Land capability classification (nonirrigated): 4e
Hydrologic Soil Group: A
Ecological site: Sandy Plains (R067BY024CO)
Hydric soil rating: No
Minor Components
Remmit
Percent of map unit: 10 percent
Hydric soil rating: No
Ufa le nt
Percent of map unit: 5 percent
Hydric soil rating: No
16
Soil Information for All Uses
Soil Reports
The Soil Reports section includes various formatted tabular and narrative reports
(tables) containing data for each selected soil map unit and each component of
each unit. No aggregation of data has occurred as is done in reports in the Soil
Properties and Qualities and Suitabilities and Limitations sections .
The reports contain soil interpretive information as well as basic soil properties and
qualities . A description of each report (table) is included .
Building Site Development
This folder contains a collection of tabular reports that present soil interpretations
related to building site development. The reports (tables) include all selected map
units and components for each map unit, limiting features and interpretive ratings .
Building site development interpretations are designed to be used as tools for
evaluating soil suitability and identifying soil limitations for various construction
purposes. As part of the interpretation process , the rating applies to each soil in its
described condition and does not consider present land use . Example
interpretations can include corrosion of concrete and steel , shallow excavations,
dwellings with and without basements , small commercial buildings , local roads and
streets , and lawns and landscaping .
Dwellings and Small Commercial Buildings
Soil properties influence the development of building sites , including the selection of
the site , the design of the structure, construction , performance after construction ,
and maintenance. This table shows the degree and kind of soil limitations that affect
dwellings and small commercial buildings .
The ratings in the table are both verbal and numerical . Rating class terms indicate
the extent to which the soils are limited by all of the soil features that affect building
site development. Not limited indicates that the soil has features that are very
favorable for the specified use . Good performance and very low maintenance can
be expected . Somewhat limited indicates that the soil has features that are
moderately favorable for the specified use . The limitations can be overcome or
minimized by special planning , design , or installation . Fair performance and
moderate maintenance can be expected . Very limited indicates that the soil has one
or more features that are unfavorable for the specified use. The limitations generally
17
Custom Soil Resource Report
cannot be overcome without major soil reclamation , special design , or expensive
installation procedures . Poor performance and high maintenance can be expected .
Numerical ratings in the table indicate the severity of individual limitations . The
ratings are shown as decimal fractions ranging from 0. 01 to 1 . 00 . They indicate
gradations between the point at which a soil feature has the greatest negative
impact on the use ( 1 . 00 ) and the point at which the soil feature is not a limitation
(0 .00).
Dwellings are single-family houses of three stories or less. For dwellings without
basements, the foundation is assumed to consist of spread footings of reinforced
concrete built on undisturbed soil at a depth of 2 feet or at the depth of maximum
frost penetration , whichever is deeper. For dwellings with basements, the foundation
is assumed to consist of spread footings of reinforced concrete built on undisturbed
soil at a depth of about 7 feet. The ratings for dwellings are based on the soil
properties that affect the capacity of the soil to support a load without movement
and on the properties that affect excavation and construction costs . The properties
that affect the load-supporting capacity include depth to a water table, ponding ,
flooding, subsidence, linear extensibility (shrink-swell potential), and compressibility.
Compressibility is inferred from the Unified classification . The properties that affect
the ease and amount of excavation include depth to a water table, ponding,
flooding , slope, depth to bedrock or a cemented pan , hardness of bedrock or a
cemented pan , and the amount and size of rock fragments .
Small commercial buildings are structures that are less than three stories high and
do not have basements . The foundation is assumed to consist of spread footings of
reinforced concrete built on undisturbed soil at a depth of 2 feet or at the depth of
maximum frost penetration , whichever is deeper. The ratings are based on the soil
properties that affect the capacity of the soil to support a load without movement
and on the properties that affect excavation and construction costs. The properties
that affect the load-supporting capacity include depth to a water table, ponding ,
flooding , subsidence, linear extensibility (shrink-swell potential), and compressibility
(which is inferred from the Unified classification). The properties that affect the ease
and amount of excavation include flooding , depth to a water table, ponding , slope,
depth to bedrock or a cemented pan , hardness of bedrock or a cemented pan , and
the amount and size of rock fragments.
Information in this table is intended for land use planning, for evaluating land use
alternatives , and for planning site investigations prior to design and construction.
The information , however, has limitations . For example, estimates and other data
generally apply only to that part of the soil between the surface and a depth of 5 to 7
feet. Because of the map scale, small areas of different soils may be included within
the mapped areas of a specific soil .
The information is not site specific and does not eliminate the need for onsite
investigation of the soils or for testing and analysis by personnel experienced in the
design and construction of engineering works .
Government ordinances and regulations that restrict certain land uses or impose
specific design criteria were not considered in preparing the information in this table.
Local ordinances and regulations should be considered in planning, in site
selection , and in design .
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Custom Soil Resource Report
Report—Dwellings and Small Commercial Buildings
[Onsite investigation may be needed to validate the interpretations in this table and
to confirm the identity of the soil on a given site . The numbers in the value columns
range from 0 .01 to 1 . 00. The larger the value, the greater the potential limitation .
The table shows only the top five limitations for any given soil . The soil may have
additional limitations]
Dwellings and Small Commercial Buildings—Weld County, Colorado, Southern Part
Map symbol and soil Pct. of Dwellings without basements Dwellings with basements Small commercial buildings
name map
unit Rating class and Value Rating class and Value Rating class and Value
limiting features limiting features limiting features
46—Olney fine sandy
loam, 0 to 1 percent
slopes
Olney 85 Not limited Not limited Not limited
47—Olney fine sandy
loam, 1 to 3 percent
slopes
Olney 85 Not limited Not limited Not limited
72—Vona loamy sand,
0 to 3 percent
slopes
Vona 85 Not limited Not limited Not limited
Roads and Streets , Shallow Excavations , and Lawns
and Landscaping
Soil properties influence the development of building sites , including the selection of
the site , the design of the structure, construction , performance after construction ,
and maintenance. This table shows the degree and kind of soil limitations that affect
local roads and streets , shallow excavations , and lawns and landscaping .
The ratings in the table are both verbal and numerical . Rating class terms indicate
the extent to which the soils are limited by all of the soil features that affect building
site development. Not limited indicates that the soil has features that are very
favorable for the specified use . Good performance and very low maintenance can
be expected . Somewhat limited indicates that the soil has features that are
moderately favorable for the specified use . The limitations can be overcome or
minimized by special planning , design , or installation . Fair performance and
moderate maintenance can be expected . Very limited indicates that the soil has one
or more features that are unfavorable for the specified use. The limitations generally
cannot be overcome without major soil reclamation , special design , or expensive
installation procedures . Poor performance and high maintenance can be expected .
Numerical ratings in the table indicate the severity of individual limitations . The
ratings are shown as decimal fractions ranging from 0. 01 to 1 . 00 . They indicate
gradations between the point at which a soil feature has the greatest negative
impact on the use ( 1 . 00) and the point at which the soil feature is not a limitation
(0 . 00).
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Custom Soil Resource Report
Local roads and streets have an all-weather surface and carry automobile and light
truck traffic all year. They have a subgrade of cut or fill soil material ; a base of
gravel , crushed rock , or soil material stabilized by lime or cement; and a surface of
flexible material (asphalt), rigid material (concrete ), or gravel with a binder. The
ratings are based on the soil properties that affect the ease of excavation and
grading and the traffic-supporting capacity. The properties that affect the ease of
excavation and grading are depth to bedrock or a cemented pan , hardness of
bedrock or a cemented pan, depth to a water table, ponding , flooding , the amount of
large stones , and slope. The properties that affect the traffic-supporting capacity are
soil strength (as inferred from the AASHTO group index number), subsidence, linear
extensibility (shrink-swell potential ), the potential for frost action, depth to a water
table, and ponding .
Shallow excavations are trenches or holes dug to a maximum depth of 5 or 6 feet
for graves , utility lines , open ditches, or other purposes . The ratings are based on
the soil properties that influence the ease of digging and the resistance to
sloughing. Depth to bedrock or a cemented pan, hardness of bedrock or a
cemented pan , the amount of large stones , and dense layers influence the ease of
digging , filling , and compacting . Depth to the seasonal high water table, flooding ,
and ponding may restrict the period when excavations can be made . Slope
influences the ease of using machinery. Soil texture , depth to the water table , and
linear extensibility (shrink-swell potential) influence the resistance to sloughing .
Lawns and landscaping require soils on which turf and ornamental trees and shrubs
can be established and maintained . Irrigation is not considered in the ratings. The
ratings are based on the soil properties that affect plant growth and trafficability after
vegetation is established . The properties that affect plant growth are reaction ; depth
to a water table; ponding; depth to bedrock or a cemented pan ; the available water
capacity in the upper 40 inches; the content of salts , sodium , or calcium carbonate ;
and sulfidic materials . The properties that affect trafficability are flooding , depth to a
water table, ponding , slope, stoniness, and the amount of sand , clay, or organic
matter in the surface layer.
Information in this table is intended for land use planning, for evaluating land use
alternatives , and for planning site investigations prior to design and construction.
The information , however, has limitations . For example, estimates and other data
generally► apply only to that part of the soil between the surface and a depth of 5 to 7
feet. Because of the map scale , small areas of different soils may be included within
the mapped areas of a specific soil .
The information is not site specific and does not eliminate the need for onsite
investigation of the soils or for testing and analysis by personnel experienced in the
design and construction of engineering works .
Government ordinances and regulations that restrict certain land uses or impose
specific design criteria were not considered in preparing the information in this table.
Local ordinances and regulations should be considered in planning , in site
selection , and in design .
Report—Roads and Streets , Shallow Excavations , and Lawns
and Landscaping
[Onsite investigation may be needed to validate the interpretations in this table and
to confirm the identity of the soil on a given site . The numbers in the value columns
range from 0 . 01 to 1 . 00. The larger the value, the greater the potential limitation .
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The table shows only the top five limitations for any given soil . The soil may have
additional limitations]
Roads and Streets, Shallow Excavations, and Lawns and Landscaping—Weld County, Colorado, Southern Part
Map symbol and soil Pct. of Lawns and landscaping Local roads and streets Shallow excavations
name map
unit Rating class and Value Rating class and Value Rating class and Value
limiting features limiting features limiting features
46—Olney fine sandy
loam, 0 to 1 percent
slopes
Olney 85 Somewhat Limited Not limited Somewhat limited
Dusty 0.09 Dusty 0 .09
Unstable excavation 0 .01
walls
47—Olney fine sandy
loam, 1 to 3 percent
slopes
Olney 85 Somewhat Limited Not limited Somewhat limited
Dusty 0.09 Dusty 0 .09
Unstable excavation 0 .01
walls
72—Vona loamy sand,
0 to 3 percent
slopes
Vona 85 Somewhat Limited Not limited Somewhat limited
Low exchange 0.75 Unstable excavation 0 .01
capacity walls
Construction Materials
This folder contains a collection of tabular reports that present soil interpretations
related to sources of construction materials . The reports (tables) include all selected
map units and components for each map unit, limiting features and interpretive
ratings . Construction materials interpretations are tools designed to provide
guidance to users in selecting a site for potential source of various materials .
Individual soils or groups of soils may► be selected as a potential source because
they are close at hand , are the only source available , or they meets some or all of
the physical or chemical properties required for the intended application . Example
interpretations include roadfill , sand and gravel , topsoil and reclamation material .
Source of Reclamation Material , Roadfill , and Topsoil
This table gives information about the soils as potential sources of reclamation
material , roadfill , and topsoil . Normal compaction , minor processing , and other
standard construction practices are assumed .
The soils are rated good, fair, or poor as potential sources of reclamation material ,
roadfill, and topsoil . The features that limit the soils as sources of these materials
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Custom Soil Resource Report
are specified in the table. Numerical ratings between 0 .00 and 0 .99 are given after
the specified features . These numbers indicate the degree to which the features
limit the soils as sources of topsoil , reclamation material , or roadfill . The lower the
number, the greater the limitation .
Reclamation material is used in areas that have been drastically disturbed by
surface mining or similar activities. When these areas are reclaimed , layers of soil
material or unconsolidated geological material , or both , are replaced in a vertical
sequence . The reconstructed soil favors plant growth . The ratings in the table do
not apply to quarries and other mined areas that require an offsite source of
reconstruction material . The ratings are based on the soil properties that affect
erosion and stability of the surface and the productive potential of the reconstructed
soil . These properties include the content of sodium , salts , and calcium carbonate;
reaction ; available water capacity; erodibility; texture; content of rock fragments ; and
content of organic matter and other features that affect fertility.
Roadtll is soil material that is excavated in one place and used in road
embankments in another place. In this table , the soils are rated as a source of
roadfill for low embankments , generally less than 6 feet high and less exacting in
design than higher embankments . The ratings are for the whole soil , from the
surface to a depth of about 5 feet. It is assumed that soil layers will be mixed when
the soil material is excavated and spread .
The ratings are based on the amount of suitable material and on soil properties that
affect the ease of excavation and the performance of the material after it is in place.
The thickness of the suitable material is a major consideration . The ease of
excavation is affected by large stones, depth to a water table , and slope. How well
the soil performs in place after it has been compacted and drained is determined by
its strength (as inferred from the AASHTO classification of the soil) and linear
extensibility (shrink-swell potential ).
Topsoil is used to cover an area so that vegetation can be established and
maintained . The upper 40 inches of a soil is evaluated for use as topsoil . Also
evaluated is the reclamation potential of the borrow area . The ratings are based on
the soil properties that affect plant growth ; the ease of excavating , loading , and
spreading the material ; and reclamation of the borrow area. Toxic substances , soil
reaction , and the properties that are inferred from soil texture, such as available
water capacity and fertility, affect plant growth . The ease of excavating , loading , and
spreading is affected by rock fragments , slope, depth to a water table , soil texture ,
and thickness of suitable material . Reclamation of the borrow area is affected by
slope , depth to a water table, rock fragments , depth to bedrock or a cemented pan ,
and toxic material .
The surface layer of most soils is generally preferred for topsoil because of its
organic matter content. Organic matter greatly increases the absorption and
retention of moisture and nutrients for plant growth .
Information in this table is intended for land use planning, for evaluating land use
alternatives , and for planning site investigations prior to design and construction .
The information , however, has limitations . For example, estimates and other data
generally apply only to that part of the soil between the surface and a depth of 5 to 7
feet. Because of the map scale , small areas of different soils may be included within
the mapped areas of a specific soil .
The information is not site specific and does not eliminate the need for onsite
investigation of the soils or for testing and analysis by personnel experienced in the
design and construction of engineering works .
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Custom Soil Resource Report
Government ordinances and regulations that restrict certain land uses or impose
specific design criteria were not considered in preparing the information in this table.
Local ordinances and regulations should be considered in planning, in site
selection , and in design .
Report—Source of Reclamation Material , Roadfill , and Topsoil
[Onsite investigation may be needed to validate the interpretations in this table and
to confirm the identity of the soil on a given site . The numbers in the value columns
range from 0 .00 to 0. 99. The smaller the value, the greater the limitation]
Source of Reclamation Material, Roadfill, and Topsoil-Weld County, Colorado, Southern Part
Map symbol and soil Pct. of Potential as a source of Potential as a source of Potential as a source of
name map reclamation material roadfill topsoil
unit
Rating class and Value Rating class and Value Rating class and Value
limiting features limiting features limiting features
48—Olney fine sandy
loam, 0 to 1 percent
slopes
Olney 85 Fair Good Fair
Low content of organic 0. 13 Exchange capacity 0 .95
matter
Water erosion 0.99
47—Olney fine sandy
loam, 1 to 3 percent
slopes
Olney 85 Fair Good Fair
Low content of organic 0. 13 Exchange capacity 0 .95
matter
Water erosion 0.99
72—Vona loamy sand,
0 to 3 percent
slopes
Vona 85 Poor Good Fair
Wind erosion 0.00 Exchange capacity 0 .80
Low content of organic 0. 13
matter
Source of Sand and Gravel
This table gives information about the soils as potential sources of gravel and sand .
Normal compaction , minor processing , and other standard construction practices
are assumed .
Sand and gravel are natural aggregates suitable for commercial use with a
minimum of processing . They are used in many kinds of construction . Specifications
for each use vary widely. Only the likelihood of finding material in suitable quantity is
evaluated . The suitability of the material for specific purposes is not evaluated , nor
are factors that affect excavation of the material . The properties used to evaluate
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Custom Soil Resource Report
the soil as a source of sand or gravel are gradation of grain sizes (as indicated by
the Unified classification of the soil), the thickness of suitable material, and the
content of rock fragments . If the bottom layer of the soil contains sand or gravel , the
soil is considered a likely source regardless of thickness . The assumption is that the
sand or gravel layer below the depth of observation exceeds the minimum
thickness . The ratings are for the whole soil , from the surface to a depth of about
feet.
The soils are rated good, fair, or poor as potential sources of sand and gravel . A
rating of good or fair means that the source material is likely to be in or below the
soil . The bottom layer and the thickest layer of the soils are assigned numerical
ratings . These ratings indicate the likelihood that the layer is a source of sand or
gravel . The number 0 . 00 indicates that the layer is a poor source . The number 1 . 00
indicates that the layer is a good source . A number between 0.00 and 1 . 00 indicates
the degree to which the layer is a likely source .
Information in this table is intended for land use planning , for evaluating land use
alternatives , and for planning site investigations prior to design and construction .
The information, however, has limitations . For example, estimates and other data
generally apply only to that part of the soil between the surface and a depth of 5 to 7
feet. Because of the map scale , small areas of different soils may be included within
the mapped areas of a specific soil .
The information is not site specific and does not eliminate the need for onsite
investigation of the soils or for testing and analysis by personnel experienced in the
design and construction of engineering works .
Government ordinances and regulations that restrict certain land uses or impose
specific design criteria were not considered in preparing the information in this table.
Local ordinances and regulations should be considered in planning , in site
selection, and in design .
Report—source of Sand and Gravel
[Onsite investigation may be needed to validate the interpretations in this table and
to confirm the identity of the soil on a given site . The numbers in the value columns
range from 0 .00 to 0 . 99. The larger the value, the greater the likelihood that the
bottom layer or thickest layer of the soil is a source of sand or gravel]
Source of Sand and Gravel-Weld County, Colorado, Southern Part
Map symbol and soil name Pct. of Potential as a source of gravel Potential as a source of sand
map unit
Rating class and limiting Value Rating class and limiting Value
features features
46-Olney fine sandy loam, 0
to 1 percent slopes
Olney 85 Poor Fair
Bottom layer 0.00 Bottom layer 0.00
Thickest layer 0.00 Thickest layer 0.07
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Custom Soil Resource Report
Source of Sand and Gravel—Weld County, Colorado, Southern Part
Map symbol and soil name Pct. of Potential as a source of gravel Potential as a source of sand
map unit
Rating class and limiting Value Rating class and limiting Value
features features
47—Olney fine sandy loam, 1
to 3 percent slopes
Olney 85 Poor Fair
Bottom layer 0.00 Bottom layer 0 .00
Thickest layer 0.00 Thickest layer 0 .07
72—Vona loamy sand, 0 to 3
percent slopes
Vona 85 Poor Fair
Bottom layer 0.00 Bottom layer 0 .03
Thickest layer 0.00 Thickest layer 0 . 10
Soil Health
Soil health , also referred to as soil quality, is defined as the continued capacity of
soil to function as a vital living ecosystem that sustains plants , animals , and
humans . This folder contains the tabular reports that provide the information specific
to the education and importance of managing soils so they are sustainable for future
generations .
Soil Health - Aggregate Stability (West US)
Definition of What is Estimated
Aggregate stability is defined as the stability of macroaggregates ( 1 -2 mm in size)
against flowing water and is expressed as percent stable aggregates of the less
than 2mm fraction . It is estimated from the organic matter content, total clay, and
sodium adsorption ratio . Aggregate stability values are provided for horizons within
the upper 6 inches , but not for sandy and organic surface layers .
Significance
Soil aggregate stability is an important soil property affecting soil health and crop
production . It is important for stabilizing soil structure, increasing water infiltration ,
and reducing erosion .
Soil aggregates are the smallest unit of soil structure . They are composed of
decaying particulate organic matter, clay particles , microbial products , and fine
roots . Aggregates are generally divided into macroaggregates (greater than 250
pm) and microaggregates (less than 250 pm) . The size, strength , and stability of
aggregates depend upon the stabilizing agents involved . They can be classified as
temporary, transient, or persistent. Improved aggregate stability leads to increased
water infiltration and storage in the profile, reduced erosion , and soil structure that is
resistant to compaction . Increases in soil organic carbon improves aggregation and
aggregate stability, which protect carbon compounds enmeshed in the aggregates
from decomposition , leading to carbon sequestration .
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Custom Soil Resource Report
Factors Affecting Soil Aggregation and Aggregate Stability
Inherent Factors - Microaggregation is generally considered to be an inherent
property of the soil . Persistent binding agents include highly decomposed , high
molecular weight organic materials (e . g . , humic compounds), polymers , and
polyvalent cations (e.g . , calcium, aluminum , iron) that have a heterogeneous, non-
specific structure . These agents are associated with microaggregation as well as
soil organic carbon (SOC ) sequestration . These persistent compounds are found in
the interior of aggregates , forming organo-mineral complexes via the polyvalent
cations . These agents are long-lasting , and the degree of aggregation formed by
them is considered part of the inherent soil properties. Generally, management does
not impact soil microaggregation . Soils naturally high in clay and polyvalent cations
are likely to form more microaggregates .
Dynamic Factors - Transient binding agents consist mainly of complex
carbohydrates, or polysaccharides , and organic mucilages . As plant residues and
compounds extruded by plant roots decompose, bacteria release mucilages that are
complex carbon-rich carbohydrates . These carbohydrates serve as binding agents,
or "glues , " to which clay particles can be adsorbed and bound together. The
polysaccharides are non-humic compounds of high molecular weight and comprise
about 20 to 25% of the soil humus . They are critical for binding microaggregates
together, via polymer and polyvalent cation bridges , to form larger
macroaggregates . Although binding with clay particles does provide some
protection against decomposition , these binding agents generally decompose within
a few weeks and need to be continually renewed through actively growing plants,
decaying residues, or organic amendments .
Temporary binding agents consist of plant roots , especially fine roots and root hairs,
fungal hyphae , and bacterial and algal cells . These agents develop along with plant
roots , forming a network that entangles mineral particles, through adsorption, to
form macroaggregates . As roots cease to grow, the amount of these temporary
agents is reduced . Planting cover crops or perennial plants maintains living roots
longer in the soil, thus maintaining and strengthening the aggregates . Tillage
reduces the amount of roots and the microbial biomass , especially in the surface
horizon.
Consequences of Weak Aggregates
The first step in erosion is the breakdown of surface aggregates . Aggregates at the
soil surface are weakened if the binding agents degrade at rates exceeding
replenishment rates . These aggregates can be broken apart by outside forces, of
which raindrops , wind , and tillage are among the most important. Changes in soil
chemistry, such as increased sodicity of the soil , can also contribute to aggregate
breakdown . As aggregates are broken down , the component particles clog the
surface pores and surface sealing and crusting follow. This process results in
reduced water infiltration , ponding, increased runoff and erosion , and sediment
transport on and off site . Its occurrence can be minimized by strengthening
aggregates .
Additionally, reducing the size and strength of the aggregates throughout the profile
weakens soil structure so that it is more easily compacted by field operations,
especially if the soil is too wet. Poor structure can lead to ponding after rainstorms ,
which can result in increased evaporation and less water in the profile that might
otherwise have been available for crop growth .
Maintaining and increasing aggregation and aggregate strength can be
accomplished through the implementation of soil health management systems.
These systems may include reduced tillage operations (or preferably no tillage
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Custom Soil Resource Report
operations) and the incorporation of cover crops or a cash crop (such as winter
wheat) into the rotation . Having crops and cover crops with varied rooting structures
improves soil structure, as does maintaining living roots in the soil as long as
possible. Studies have shown that plants will push into the rhizosphere , via the root
system , about 20% of the carbon dioxide is fixed through photosynthesis . Those
carbon compounds can support the soil microbial population , which is critical to soil
structure, water infiltration , and nutrient cycling . Any management system that leads
to increased soil organic carbon is likely to improve aggregate stability.
Measuring Aggregate Stability
Aggregate stability is determined by a wet sieving technique preceded by vacuum
saturation of the 1 -2 mm size aggregates as described in USDA-ARS ( 1966). Stable
aggregates are corrected for sand greater than 0.25 mm as follows : Aggregate
stability (% ) = ((wt. of stable aggregates and sand ) — (wt. of sand )}l((wt. of sample)
— (wt. of sand)).
References
Blanco-Canqui , H . , and R. Lal . 2004 . Mechanisms of carbon sequestration in soil
aggregates . Criti . Rev. Plant Sci . 23:481 -504 . doi : 10 . 1080/07352680490886842
Cambardella , C .A. , and E.T. Elliott. 1993. Carbon and nitrogen distribution in
aggregates from cultivated and native grassland soils. Soil Sci . Soc. Am . J .
57: 1071 - 1076 . doi : 10.21361sssaj 1993 .03615995005700040032x
Denef, K. , J . Six, H . Bossuyt, S. D . Frey, E .T. Elliott, R. Merckx, and K. Paustian .
2001 . Influence of dry-wet cycles on the interrelationship between aggregate,
particulate organic matter, and microbial community dynamics . Soil Biol . Biochem .
33: 1599- 1611 . doi : 10. 1016/s0038-0717(01 )00076- 1
Gale , W.J . , and C .A. Cambardella. 2000. Carbon dynamics of surface residue- and
root-derived organic matter under simulated no-till . Soil Sci . Soc. Am . J .
64: 190- 195 . doi : 10 .2136/sssaj2000 . 641190x
Gale , W.J . , C .A. Cambardella, and T. B . Bailey. 2000a. Root-derived carbon and the
formation and stabilization of aggregates. Soil Sci . Soc. Am . J . 64 :201 -207. doi :
10.2136/sssaj2000. 641201 x
Gale , W.J . , C .A. Cambardella, and T. B . Bailey. 2000b. Surface residue- and root-
derived carbon in stable and unstable aggregates . Soil Sci . Soc. Am . J . 64 : 196-201 .
doi : 10 .2136/sssaj2000 . 641196x
Martin , J . P. 1971 . Decomposition and binding action of polysaccharides in soil . Soil
Biol . Biochem . 3 : 33-41 .
Six, J . , E .T. Elliott, and K. Paustian . 1999 . Aggregate and soil organic matter
dynamics under conventional and no-tillage systems . Soil Sci . Soc. Am . J .
63: 1350- 1358 .
Six, J . , K . Paustian , E.T. Elliott, and C . Combrink. 2000. Soil structure and organic
matter: I . Distribution of aggregate-size classes and aggregate-associated carbon .
Soil Sci . Soc. Am . J . 64 : 681 -689 .
Tisdall , J . M . , and J . M . Oades . 1982 . Organic matter and water-stable aggregates in
soil . J . Soil Sci . 33 : 141 - 163.
USDA-ARS . 1966. Aggregate stability► of soils from western United States and
Canada . Tech . Bull . No. 1355 . Agricultural Research Service , United States
Department of Agriculture in cooperation with Colorado Agricultural Experiment
Station . U . S. Govn't Printing Office . Washington , D . C .
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Custom Soil Resource Report
Report—Soil Health - Aggregate Stability (West US )
Soil Health - Aggregate Stability (West US)-Weld County, Colorado, Southern Part
Map symbol and soil Pct. of map Horizon Depth Aggregate Aggregate Aggregate
name unit Name (Inches) Stability low Stability RV (Pct) Stability high
(Pct) (Pct
46—Olney fine sandy loam,
0 to 1 percent slopes
Olney 85 H 1 0-10 46 54 60
47—Olney fine sandy loam,
1 to 3 percent slopes
Olney 85 H1 0-10 46 54 60
72—Vona loamy sand, 0 to
3 percent slopes
Vona 85 H 1 0-6 45 49 54
Soil Health - Compaction , Surface Sealing
Soil health is primarily influenced by human management, which is not captured in
soil survey data at this time. These interpretations provide information on inherent
soil properties that influence our ability to build healthy soils through management.
The ratings are both verbal and numerical . Numerical ratings indicate the propensity
of individual soil properties to influence specific aspects of soil health management.
The ratings are shown in decimal fractions ranging from 0. 01 to 1 . 00 . They indicate
gradations between the point at which a soil feature has the greatest ability to
enhance soil health ( 1 . 00) and the point at which the soil feature becomes least
likely to enhance soil health (0. 00).
The ratings forsoil susceptibility to compaction are based on soil properties in the
upper 12 inches of soil . Factors considered are soil texture , soil organic matter
content, soil structure, rock fragment content, and the existing bulk density. Each of
these factors contributes to the soil's ability to resist compaction . Rating class terms
indicate the potential for soil compaction . " Low" indicates that the potential for
compaction is insignificant. Soils with a low rating can support standard equipment
with minimal compaction . These soils are moisture insensitive, exhibiting only small
changes in density with changing moisture content. " Medium" indicates that the
potential for compaction is significant. The growth rate of seedlings may be reduced
following compaction . After the initial compaction (i . e . , the first pass of equipment) ,
soils with a medium rating are able to support standard equipment with only minimal
increases in soil density. These soils are intermediate between moisture insensitive
and moisture sensitive . " High" indicates that the potential for compaction is
significant. The growth rate of seedlings will be reduced following compaction . After
initial compaction , soils with a high rating are still able to support standard
equipment but will continue to compact with each subsequent pass . These soils are
moisture sensitive , exhibiting large changes in density with changing moisture
content.
The ratings forsoil susceptibility to surface sealing are based on soil properties at
the soil surface. They are applicable to conditions or times when the soil surface , or
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Custom Soil Resource Report
any portion of it, is exposed to the impact of raindrops and there is significant rain or
sprinkler irrigation. Soil surfaces that are void of vegetative, canopy, residue, litter,
or duff cover are the most vulnerable to surface sealing . Factors considered are
exchangeable sodium , a silt/crusting index, water dispersible clay, and organic
matter. Rating class terms indicate the soil's inherent potential to form a surface
seal . "'Low" indicates that the soil has a low inherent susceptibility to form a surface
seal . These soils are not likely to form a surface seal . " Moderate" indicates that the
soil has a moderate inherent susceptibility to form a surface seal . The potential to
form a surface seal is significant. "High " indicates that the soil has a high
susceptibility to form a surface seal . The inherent soil properties are highly
conducive to forming a surface seal . Management that protects the soil from
raindrop impact and minimizes soil disturbance helps prevent surface sealing . Plant
and mulch cover can shield the soil from raindrop impact and so reduce sealing in
otherwise susceptible soils. Soil management practices that increase organic matter
content combined with the use of plant or residue cover for protection help prevent
the formation of surface seals in most soils. Because tillage disrupts soil structure
and aggregates , it accelerates the formation of seals . Management that minimizes
soil disturbances and protects the soil from raindrop impact greatly increases
infiltration and reduces runoff.
Report—Soil Health - Compaction , Surface Sealing
[Onsite investigation may be needed to validate the interpretations in this table and
to confirm the identity of the soil on a given site . The numbers in the value columns
range from 0 .01 to 1 . 00. The larger the value, the greater the potential limitation .
The table shows only the top limitations for any given soil . The soil may have
additional limitations]
Soil Health - Compaction, Surface Sealing—Weld County, Colorado, Southern Part
Map symbol and soil name Pct. of Soil Susceptibility to Surface Sealing Soil Susceptibilty to compaction
map unit
Rating class and limiting Value Rating class and limiting Value
features features
46—Olney fine sandy loam, 0
to 1 percent slopes
Olney 85 High Medium
Low organic matter relative to 1 .00 Soil texture, 0- 12 inches 1 .00
clay
Moderate water dispersible 0.95 Rock fragments, 0-12 inches 1 .00
clay
Moderate silt/crusting potential 0. 37 Soil structure grade, 0-12 1 .00
inches
Organic matter content , 0- 30 1 .00
cm
Subaerial 1 .00
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Soil Health - Compaction, Surface Sealing—Weld County, Colorado, Southern Part
Map symbol and soil name Pct. of Soil Susceptibility to Surface Sealing Soil Susceptibilty to Compaction
map unit
Rating class and limiting Value Rating class and limiting Value
features features
47—Olney fine sand► loam, 1
to 3 percent slopes
Olney 85 High Medium
Low organic matter relative to 1 .00 Soil texture, 0- 12 inches 1 .00
clay
Moderate water dispersible 0.95 Rock fragments, 0-12 inches 1 .00
clay
Moderate silt/crusting potential 0.37 Soil structure grade, 0-12 1 .00
inches
Organic matter content, 0-30 1 .00
cm
Subaerial 1 .00
72—Vona loamy sand, 0 to 3
percent slopes
Vona 85 Moderate Low
Moderate water dispersible 0.45 Rock fragments, 0-12 inches 1 .00
clay
Moderate organic matter 0.34 Soil structure grade, 0-12 1 .00
relative to clay inches
Moderate silt/crusting potential 0.28 Organic matter content, 0-30 1 .00
cm
Subaerial 1 .00
Bulk density-compactibility to 0 .70
30c m
Soil Physical Properties
This folder contains a collection of tabular reports that present soil physical
properties . The reports (tables) include all selected map units and components for
each map unit. Soil physical properties are measured or inferred from direct
observations in the field or laboratory. Examples of soil physical properties include
percent clay, organic matter, saturated hydraulic conductivity, available water
capacity, and bulk density.
Engineering Properties
This table gives the engineering classifications and the range of engineering
properties for the layers of each soil in the survey area .
Hydrologic soil group is a group of soils having similar runoff potential under similar
storm and cover conditions . The criteria for determining Hydrologic soil group is
found in the National Engineering Handbook, Chapter 7 issued May 2007(http://
d irectives .sc. egov. usda .gav/Open NonWebContent. aspx?content= 17757.wba ).
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Listing HSGs by soil map unit component and not by soil series is a new concept for
the engineers . Past engineering references contained lists of HSGs by soil series .
Soil series are continually being defined and redefined , and the list of soil series
names changes so frequently as to make the task of maintaining a single national
list virtually impossible. Therefore , the criteria is now used to calculate the HSG
using the component soil properties and no such national series lists will be
maintained . All such references are obsolete and their use should be discontinued .
Soil properties that influence runoff potential are those that influence the minimum
rate of infiltration for a bare soil after prolonged wetting and when not frozen. These
properties are depth to a seasonal high water table , saturated hydraulic conductivity
after prolonged wetting , and depth to a layer with a very slow water transmission
rate . Changes in soil properties caused by land management or climate changes
also cause the hydrologic soil group to change . The influence of ground cover is
treated independently. There are four hydrologic soil groups , A, B, C , and D , and
three dual groups, AID , B/D , and CID. In the dual groups , the first letter is for
drained areas and the second letter is for undrained areas .
The four hydrologic soil groups are described in the following paragraphs :
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
gravelly sands . These soils have a high rate of water transmission .
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 transmission .
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 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 .
Depth to the upper and lower boundaries of each layer is indicated .
Texture is given in the standard terms used by the U . S . Department of Agriculture .
These terms are defined according to percentages of sand , silt, and clay in the
fraction of the soil that is less than 2 millimeters in diameter. " Loam ," for example, is
soil that is 7 to 27 percent clay, 28 to 50 percent silt, and less than 52 percent sand .
lithe content of particles coarser than sand is 15 percent or more, an appropriate
modifier is added , for example, "gravelly. "
Classification of the soils is determined according to the Unified soil classification
system (ASTM, 2005) and the system adopted by the American Association of
State Highway and Transportation Officials (AASHTO, 2004).
The Unified system classifies soils according to properties that affect their use as
construction material . Soils are classified according to particle-size distribution of
the fraction less than 3 inches in diameter and according to plasticity index, liquid
limit, and organic matter content. Sandy and gravelly soils are identified as GVV, GP,
GM , GC , SW, SP, SM , and SC ; silty and clayey soils as ML, CL, OL , MH , OH , and
OH; and highly organic soils as PT. Soils exhibiting engineering properties of two
groups can have a dual classification, for example , CL-ML.
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The AASHTO system classifies soils according to those properties that affect
roadway construction and maintenance. In this system , the fraction of a mineral soil
that is less than 3 inches in diameter is classified in one of seven groups from A- 1
through A-7 on the basis of particle-size distribution, liquid limit, and plasticity index.
Soils in group A- 1 are coarse grained and low in content of fines (silt and clay). At
the other extreme, soils in group A-7 are fine grained . Highly organic soils are
classified in group A-8 on the basis of visual inspection.
If laboratory data are available , the A- 1 , A-2 , and A-7 groups are further classified
as A- 1 -a, A- 1 -b , A-2-4 , A-2-5, A-2-6 , A-2-7, A-7-5, or A-7-6. As an additional
refinement, the suitability of a soil as subgrade material can be indicated by a group
index number. Group index numbers range from 0 for the best subgrade material to
20 or higher for the poorest.
Percentage of rock fragments larger than 10 inches in diameter and 3 to 10 inches
in diameter are indicated as a percentage of the total soil on a dry-weight basis . The
percentages are estimates determined mainly by converting volume percentage in
the field to weight percentage. Three values are provided to identify the expected
Low (L), Representative Value (R), and High ( H ).
Percentage (of soil particles) passing designated sieves is the percentage of the soil
fraction less than 3 inches in diameter based on an ovendry weight . The sieves,
numbers 4, 10 , 40, and 200 (USA Standard Series), have openings of 4 . 76, 2 . 00 ,
0 .420 , and 0 .074 millimeters , respectively. Estimates are based on laboratory tests
of soils sampled in the survey area and in nearby areas and on estimates made in
the field . Three values are provided to identify the expected Low ( L), Representative
Value ( R), and High (H ) .
Liquid limit and plasticity index (Atterberg limits) indicate the plasticity
characteristics of a soil . The estimates are based on test data from the survey area
or from nearby areas and on field examination . Three values are provided to identify
the expected Low (L), Representative Value (R), and High (H ) .
References :
American Association of State Highway and Transportation Officials (AASHTO).
2004. Standard specifications for transportation materials and methods of sampling
and testing . 24th edition .
American Society for Testing and Materials (ASTM ). 2005. Standard classification of
soils for engineering purposes . ASTM Standard D2487-00 .
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Absence of an entry indicates that the data were not estimated . The asterisk '*r denotes the representative texture; other
possible textures follow the dash . The criteria for determining the hydrologic soil group for individual soil components is
found in the National Engineering Handbook, Chapter 7 issued May 2007(http://directives. sc. egay. usda .gov!
OpenNonWebContent. aspx?content= 17757.wba). Three values are provided to identify the expected Low (L),
Representative Value ( R), and High ( H ).
Engineering Properties—Weld County, Colorado, Southern Part
Map unit symbol and Pct. of Hydrolo Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid Plasticit
soil name map gic - limit y index
unit group Unified AASHTO >10 3-10 4 10 40 200
inches inches
to L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
46—Olney fine sandy
loam, 0 to 1 percent
slopes
Olney 85 B 0-10 Fine sandy loam SC, SC- A-4 0- 0- 0 0- 0- 0 100-100 100- 100 70-78- 40-45- 25-28 5-8 -10
SM -100 -100 85 50 -30
10-20 Sandy clay loam, CL, CL- A-4, A-6 0- 0- 0 0- 0- 0 95-98-1 90-95-1 80-90-1 40-48- 25-30 5-10-15
sandy loam ML, SC, 00 00 00 55 -35
SC-SM
20-25 Sandy loam, sandy CL, CL- A-2, A-4 0- 0- 0 0- 0- 0 95-98-1 95-98-1 60-75- 30-43- 25-28 5-8 -10
clay loam, fine ML, SC, 00 00 90 55 -30
sandy loam SC-SM
25-60 Fine sandy loam, SC-SM, A-2 0- 0- 0 0- 0- 0 95-98-1 95-98-1 60-73- 30-40- 20-23 NP-3 -5
loamy fine sand, SM 00 00 85 50 -25
sandy loam
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Custom Soil Resource Report
Engineering Properties—Weld County, Colorado, Southern Part
Map unit symbol and Pet of Hydrolo Depth USDA texture Classification Pet Fragments Percentage passing sieve number— Liquid Plasticit
soil name map gic limit y index
unit group Unified AASHTO '10 3-10 4 10 40 200
inches inches
In L-R-H L-R-H L-R-H L-R-h► L-R-H L-R-H L-R-N L-R-H
47—Olney fine sandy
loam, 1 to 3 percent
slopes
Olney 85 B 0-10 Fine sandy loam SC, SC- A-4 0- 0- 0 0- 0- 0 100-100 100- 100 70-78- 40-45- 25-28 5-8 -10
SM -100 -100 85 50 -30
10-20 Sandy clay loam, CL, CL- A-4, A-6 0- 0- 0 0- 0- 0 95-98-1 90-95-1 80-90-1 40-48- 25-30 5-10-15
sandy loam ML, SC, 00 00 00 55 -35
SC-SM
20-25 Sandy loam, sandy CL, CL- A-2, A-4 0- 0- 0 0- 0- 0 95-98-1 95-98-1 60-75- 30-43- 25-28 5-8 -10
clay loam, fine ML, SC, 00 00 90 55 -30
sandy loam SC-SM
25-60 Fine sandy loam, SC-SM, A-2 0- 0- 0 0- 0- 0 95-98-1 95-98-1 60-73- 30-40- 20-23 NP-3 -5
loamy fine sand, SM 00 00 85 50 -25
sandy loam
72—Vona loamy sand,
0 to 3 percent slopes
Vona 85 A 0-6 Loamy sand SM A-2 0- 0- 0 0- 0- 0 100-100 100- 100 50-63- 15-23- - NP
-100 -100 75 30
6-28 Fine sandy loam, SC, SC- A-2, A-4 0- 0- 0 0- 0- 0 100-100 90-95-1 60-75- 30-38- 20-25 NP-5
sandy loam SM, SM -100 00 90 45 -30 -10
28-60 Sandy loam, loamy SC-SM, A-2, A-4 0- 0- 0 0- 0- 0 100-100 90-95-1 50-68- 15-28- 20-23 NP-3 -5
sand, loamy fine SM -100 00 85 40 -25
sand
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Custom Soil Resource Report
Soil Qualities and Features
This folder contains tabular reports that present various soil qualities and features .
The reports (tables) include all selected map units and components for each map
u nit. Soil qualities are behavior and performance attributes that are not directly
measured , but are inferred from observations of dynamic conditions and from soil
properties . Example soil qualities include natural drainage, and frost action . Soil
features are attributes that are not directly part of the soil . Example soil features
include slope and depth to restrictive layer. These features can greatly impact the
u se and management of the soil .
soil Features
This table gives estimates of various soil features . The estimates are used in land
u se planning that involves engineering considerations.
A restrictive layer is a nearly continuous layer that has one or more physical ,
chemical , or thermal properties that significantly impede the movement of water and
air through the soil or that restrict roots or otherwise provide an unfavorable root
environment. Examples are bedrock, cemented layers , dense layers , and frozen
layers . The table indicates the hardness and thickness of the restrictive layer, both
of which significantly affect the ease of excavation . Depth to top is the vertical
distance from the soil surface to the upper boundary of the restrictive layer.
Subsidence is the settlement of organic soils or of saturated mineral soils of very
low density. Subsidence generally results from either desiccation and shrinkage, or
oxidation of organic material , or both , following drainage . Subsidence takes place
gradually, usually over a period of several years . The table shows the expected
initial subsidence , which usually is a result of drainage , and total subsidence , which
results from a combination of factors .
Potential for frost action is the likelihood of upward or lateral expansion of the soil
caused by the formation of segregated ice lenses (frost heave) and the subsequent
collapse of the soil and loss of strength on thawing . Frost action occurs when.
moisture moves into the freezing zone of the soil . Temperature , texture , density,
saturated hydraulic conductivity ( Ks at) , content of organic matter, and depth to the
water table are the most important factors considered in evaluating the potential for
frost action . It is assumed that the soil is not insulated by vegetation or snow and is
not artificially drained . Silty and highly structured , clayey soils that have a high water
table in winter are the most susceptible to frost action . Well drained , very gravelly,
or very sandy soils are the least susceptible. Frost heave and low soil strength
during thawing cause damage to pavements and other rigid structures .
Risk of corrosion pertains to potential soil-induced electrochemical or chemical
action that corrodes or weakens uncoated steel or concrete. The rate of corrosion of
u ncoated steel is related to such factors as soil moisture, particle-size distribution ,
acidity, and electrical conductivity of the soil . The rate of corrosion of concrete is
based mainly on the sulfate and sodium content, texture , moisture content, and
acidity of the soil . Special site examination and design may be needed if the
combination of factors results in a severe hazard of corrosion . The steel or concrete
in installations that intersect soil boundaries or soil layers is more susceptible to
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Custom Soil Resource Report
corrosion than the steel or concrete in installations that are entirely within one kind
of soil or within one soil layer.
For uncoated steel, the risk of corrosion, expressed as low, moderate , or high, is
based on soil drainage class , total acidity, electrical resistivity near field capacity,
and electrical conductivity of the saturation extract.
For concrete , the risk of corrosion also is expressed as low, moderate , or high. It is
based on soil texture , acidity, and amount of sulfates in the saturation extract .
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Custom Soil Resource Report
Soil Features-Weld County, Colorado , Southern Part
Map symbol and Restrictive Layer Subsidence Potential for frost Risk of corrosion
soil name action
Kind Depth to Thickness Hardness Initial Total Uncoated steel concrete
top
Low-RV- Range Low- Low-
High High High
In In In In
46—Olney fine
sandy loam, 0 to
1 percent slopes
Olney — — 0 — Low High Low
47—Olneyfine
sandy loam, 1 to
3 percent slopes
Olney — — 0 — Low High Low
72—Vona loamy
sand, 0 to 3
percent slopes
Vona — — 0 — Low High Moderate
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Custom Soil Resource Report
Water Features
This folder contains tabular reports that present soil hydrology information . The
reports (tables) include all selected map units and components for each map unit.
Water Features include ponding frequency, flooding frequency, and depth to water
table.
Hydrologic Soil Group and Surface Runoff
This table gives estimates of various soil water features . The estimates are used in
land use planning that involves engineering considerations .
Hydrologic soil groups are based on estimates of runoff potential . Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation , are thoroughly 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
gravelly sands . These soils have a high rate of water transmission .
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 transmission .
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 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 .
If a soil is assigned to a dual hydrologic group (AID , BID , or C/D ), the first letter is
for drained areas and the second is for undrained areas .
Surface runoff refers to the loss of water from an area by flow over the land surface .
Surface runoff classes are based on slope , climate , and vegetative cover. The
concept indicates relative runoff for very specific conditions . It is assumed that the
surface of the soil is bare and that the retention of surface water resulting from
irregularities in the ground surface is minimal . The classes are negligible , very low,
low, medium , high , and very high .
Report—Hydrologic Soil Group and Surface Runoff
Absence of an entry indicates that the data were not estimated . The dash indicates
no documented presence .
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Hydrologic Soil Group and Surface Runoff-Weld County, Colorado, Southern Part
Map symbol and soil name Pct. of map unit Surface Runoff Hydrologic Soil Group
40—Olney fine sandy loam, 0 to 1 percent slopes
Olney 85 Low B
47—Olney fine sandy loam, 1 to 3 percent slopes
Olney 85 Low B
72—Vona loamy sand, 0 to 3 percent slopes
Vona 85 Very low A
Water Features
This table gives estimates of various soil water features . The estimates are used in
land use planning that involves engineering considerations .
Hydrologic soil groups are based on estimates of runoff potential . Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation , are thoroughly 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
gravelly sands . These soils have a high rate of water transmission .
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 transmission .
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 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 .
If a soil is assigned to a dual hydrologic group (AID , BID , or C/D), the first letter is
for drained areas and the second is for undrained areas .
Surface runoff refers to the loss of water from an area by flow over the land surface .
Surface runoff classes are based on slope, climate, and vegetative cover. The
concept indicates relative runoff for very specific conditions . It is assumed that the
surface of the soil is bare and that the retention of surface water resulting from
irregularities in the ground surface is minimal . The classes are negligible, very low,
low, medium , high , and very high .
The months in the table indicate the portion of the year in which a water table ,
ponding , and/or flooding is most likely to be a concern .
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Water table refers to a saturated zone in the soil . The water features table indicates,
by month , depth to the top ( upper limit ) and base ( lower limit ) of the saturated
zone in most years. Estimates of the upper and lower limits are based mainly on
observations of the water table at selected sites and on evidence of a saturated
zone, namely grayish colors or mottles (redoximorphic features) in the soil . A
saturated zone that lasts for less than a month is not considered a water table . The
kind of water table , apparent or perched , is given if a seasonal high water table
exists in the soil . A water table is perched if free water is restricted from moving
downward in the soil by a restrictive feature , in most cases a hardpan ; there is a dry
layer of soil underneath a wet layer. A water table is apparent if free water is present
in all horizons from its upper boundary to below 2 meters or to the depth of
observation . The water table kind listed is for the first major component in the map
u nit.
Porting is standing water in a closed depression . Unless a drainage system is
installed , the water is removed only by percolation , transpiration , or evaporation .
The table indicates surface water depth and the duration and frequency of ponding .
Duration is expressed as very brief if less than 2 days , brief if 2 to 7 days , long if 7
to 30 days, and very long if more than 30 days . Frequency is expressed as none ,
rare, occasional , and frequent . None means that ponding is not probable; rare that it
is unlikely but possible under unusual weather conditions (the chance of ponding is
n early 0 percent to 5 percent in any year) ; occasional that it occurs , on the average,
once or less in 2 years (the chance of ponding is 5 to 50 percent in any year) ; and
frequent that it occurs , on the average, more than once in 2 years (the chance of
ponding is more than 50 percent in any year).
Flooding is the temporary inundation of an area caused by overflowing streams , by
runoff from adjacent slopes , or by tides . Water standing for short periods after
rainfall or snowmelt is not considered flooding , and water standing in swamps and
marshes is considered ponding rather than flooding .
Duration and frequency are estimated . Duration is expressed as extremely brief if
0 . 1 hour to 4 hours, very brief if 4 hours to 2 days, brief if 2 to 7 days , long if 7 to 30
days , and very long if more than 30 days . Frequency is expressed as none, very
rare , rare, occasional , frequent, and very frequent . None means that flooding is not
probable; very rare that it is very unlikely but possible under extremely unusual
weather conditions (the chance of flooding is less than 1 percent in any year) ; rare
that it is unlikely but possible under unusual weather conditions (the chance of
flooding is 1 to 5 percent in any year) ; occasional that it occurs infrequently under
n ormal weather conditions (the chance of flooding is 5 to 50 percent in any year);
frequent that it is likely to occur often under normal weather conditions (the chance
of flooding is more than 50 percent in any year but is less than 50 percent in all
months in any year) ; and very frequent that it is likely to occur very often under
normal weather conditions (the chance of flooding is more than 50 percent in all
months of any year) .
The information is based on evidence in the soil profile, namely thin strata of gravel ,
sand , silt , or clay deposited by floodwater; irregular decrease in organic matter
content with increasing depth ; and little or no horizon development.
Also considered are local information about the extent and levels of flooding and the
relation of each soil on the landscape to historic floods . Information on the extent of
flooding based on soil data is less specific than that provided by detailed
engineering surveys that delineate flood-prone areas at specific flood frequency
levels .
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Custom Soil Resource Report
Map unit symbol and soil Hydrologic Surface Most likely Water table Ponding Flooding
name group runoff months
Upper limit Lower limit Kind Surface Duration Frequency Duration Frequency
depth
Ft Ft Ft
46—Olney fine sandy loam, 0 t0 1 percent slopes
Olney B Low Jan-Dec — — — — — None — None
47—Olney fine sandy loam, 1 to 3 percent slopes
Olney B Low Jan-Dec — — — — — None — None
72—Vona loamy sand, 0 to 3 percent slopes
Vona A Very low Jan-Dec — — — — — None — None
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Water Management
This folder contains a collection of tabular reports that present soil interpretations
related to water management. The reports (tables) include all selected map units
and components for each map unit, limiting features and interpretive ratings . Water
management interpretations are tools for evaluating the potential of the soil in the
application of various water management practices. Example interpretations include
pond reservoir area, embankments , dikes , levees , and excavated ponds.
Irrigation - surface
This table shows the degree and kind of soil limitations that affect irrigation systems
on mineral soils . The ratings are both verbal and numerical . Rating class terms
indicate the extent to which the soils are limited by all of the soil features that affect
these uses . Not limited indicates that the soil has features that are very favorable for
the specified use . Good performance and very low maintenance can be expected .
Somewhat limited indicates that the soil has features that are moderately favorable
for the specified use . The limitations can be overcome or minimized by special
planning , design , or installation . Fair performance and moderate maintenance can
be expected . Very limited indicates that the soil has one or more features that are
unfavorable for the specified use . The limitations generally cannot be overcome
without major soil reclamation , special design , or expensive installation procedures .
Poor performance and high maintenance can be expected .
Numerical ratings in the table indicate the severity of individual limitations . The
ratings are shown as decimal fractions ranging from 0. 01 to 1 . 00 . They indicate
gradations between the point at which a soil feature has the greatest negative
impact on the use ( 1 . 00 ) and the point at which the soil feature is not a limitation
(0 . 00).
Irrigation systems are used to provide supplemental water to crops, orchards ,
vineyards, and vegetables in area where natural precipitation will not support
desired production of crops being grown .
Irrigation, surface (graded) evaluates a soil for graded flood or furrow irrigation
systems . The ratings are for soils in their natural condition and do not consider
present land use . .
Graded surface irrigation systems include graded border and graded furrow
irrigation systems . Graded border irrigation systems allow irrigation water to flow
across the soil surface while being confined by borders . Graded furrow irrigation
systems are systems that allow irrigation water to flow down furrow valleys while the
crop being irrigated is planted on the furrow ridge . Generally, graded border
systems are suitable for small grains while graded furrow systems are suitable for
row crops .
The soil properties and qualities important in the design and management of graded
surface irrigation systems are depth , available water holding capacity, sodium
adsorption ratio , surface rocks , permeability, salinity, slope, wetness , and flooding .
Features that affect system performance and plant growth are salinity, sodium
adsorption ratio , wetness , calcium carbonate content, and available water holding
capacity. .
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Custom Soil Resource Report
Irrigation, surface (level) evaluates a soil for basin , paddy, level furrow, or level
border irrigation systems . The ratings are for soils in their natural condition and do
not consider present land use .
Level surface irrigation systems are irrigation systems that use flood irrigation
techniques to spread irrigation water at a specified depth across the application
area . Basin , paddy, and borders generally use external ridges or borders to confine
the irrigation application while level furrow systems use furrow valleys and end
blocks or border ridges to confine the irrigation application during irrigation . With
furrow irrigation the crop is usually planted on the furrow ridge . Generally, basin ,
paddy and level border irrigation systems are suitable for rice , small grain , pasture,
and forage production . Level furrow systems are generally suited for row crops .
The soil properties and qualities important in the design and management of level
surface irrigation systems are depth , available water holding capacity, sodium
adsorption ratio , permeability, salinity, slope , and flooding . The soil properties and
qualities that influence installation are depth , flooding , and ponding . The features
that affect performance of the system and plant growth are salinity, sodium
adsorption ratio , and available water holding capacity.
Information in this table is intended for land use planning , for evaluating land use
alternatives , and for planning site investigations prior to design and construction .
The information , however, has limitations . For example, estimates and other data
generally apply only to that part of the soil between the surface and a depth of 5 to 7
feet. Because of the map scale , small areas of different soils may be included within
the mapped areas of a specific soil .
The information is not site specific and does not eliminate the need for onsite
investigation of the soils or for testing and analysis by personnel experienced in the
design and construction of engineering works .
Government ordinances and regulations that restrict certain land uses or impose
specific design criteria were not considered in preparing the information in this table.
Local ordinances and regulations should be considered in planning , in site
selection , and in design . The irrigation interpretations are not designed or intended
to be used in a regulatory manner.
Report—Irrigation - Surface
[The information in this table provides irrigation interpretations for mineral soils .
Onsite investigation may be needed to validate the interpretations and to confirm
the identity of the soil on a given site. The numbers in the value columns range from
0 .01 to 1 . 00. The larger the value, the greater the potential limitation . The table
shows only the top five limitations for any given soil . The soil may have additional
limitations]
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Custom Soil Resource Report
Irrigation - Surface—Weld County, Colorado, Southern Part
Map symbol and soil name Pct. of Irrigation, Surface (graded) Irrigation, Surface (level)
map unit
Rating class and limiting Value Rating class and limiting Value
features features
46—Olney fine sand► loam, 0
to 1 percent slopes
Olney 85 Somewhat limited Somewhat limited
Rapid water movement 0.69 Rapid water movement 0 .69
Seepage 0.43 Seepage 0 .43
Low water holding capacity 0.01 Low water holding capacity 0 .01
47—Olney fine sandy loam, 1
to 3 percent slopes
Olney 85 Somewhat limited Somewhat limited
Rapid water movement 0.69 Rapid water movement 0 .69
Slope 0.50 Seepage 0 .43
Seepage 0.43 Low water holding capacity 0 .01
Low water holding capacity 0.01
72—Vona loamy sand, 0 to 3
percent slopes
Vona 85 Very limited Very limited
Rapid water movement 1 .00 Rapid water movement 1 .00
Seepage 1 .00 Seepage 1 .00
Slope 0.50 Low water holding capacity 0 .06
Low water holding capacity 0.06
Ponds and Embankments
This table gives information on the soil properties and site features that affect water
management. The degree and kind of soil limitations are given for pond reservoir
areas ; embankments , dikes , and levees ; and aquifer-fed excavated ponds . The
ratings are both verbal and numerical . Rating class terms indicate the extent to
which the soils are limited by all of the soil features that affect these uses . Not
limited indicates that the soil has features that are very► favorable for the specified
use. Good performance and very low maintenance can be expected . Somewhat
limited indicates that the soil has features that are moderately favorable for the
specified use. The limitations can be overcome or minimized by special planning ,
design , or installation . Fair performance and moderate maintenance can be
expected . Very limited indicates that the soil has one or more features that are
unfavorable for the specified use . The limitations generally cannot be overcome
without major soil reclamation , special design , or expensive installation procedures .
Poor performance and high maintenance can be expected .
Numerical ratings in the table indicate the severity of individual limitations . The
ratings are shown as decimal fractions ranging from 0. 01 to 1 . 00 . They indicate
gradations between the point at which a soil feature has the greatest negative
impact on the use ( 1 . 00) and the point at which the soil feature is not a limitation
(0 . 00).
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Custom Soil Resource Report
Pond reservoir areas hold water behind a dam or embankment. Soils best suited to
this use have low seepage potential in the upper 60 inches . The seepage potential
is determined by the saturated hydraulic conductivity ( Ksat) of the soil and the depth
to fractured bedrock or other permeable material . Excessive slope can affect the
storage capacity of the reservoir area .
Embankments, dikes, and levees are raised structures of soil material , generally
less than 20 feet high , constructed to impound water or to protect land against
overflow. Embankments that have zoned construction (core and shell) are not
considered . In this table , the soils are rated as a source of material for embankment
fill . The ratings apply to the soil material below the surface layer to a depth of 5 or
feet. It is assumed that soil layers will be uniformly mixed and compacted during
construction .
The ratings do not indicate the ability of the natural soil to support an embankment.
Soil properties to a depth even greater than the height of the embankment can
affect performance and safety of the embankment. Generally, deeper onsite
investigation is needed to determine these properties .
Soil material in embankments must be resistant to seepage , piping , and erosion and
have favorable compaction characteristics. Unfavorable features include less than 5
feet of suitable material and a high content of stones or boulders , organic matter, or
salts or sodium . A high water table affects the amount of usable material . It also
affects trafficability.
Aquifer-fed excavated ponds are pits or dugouts that extend to a ground-water
aquifer or to a depth below a permanent water table . Excluded are ponds that are
fed only by surface runoff and embankment ponds that impound water 3 feet or
more above the original surface. Excavated ponds are affected by depth to a
permanent water table , Ksat of the aquifer, and quality of the water as inferred from
the salinity of the soil . Depth to bedrock and the content of large stones affect the
ease of excavation .
Information in this table is intended for land use planning, for evaluating land use
alternatives , and for planning site investigations prior to design and construction.
The information, however, has limitations . For example, estimates and other data
generally apply only to that part of the soil between the surface and a depth of 5 to 7
feet. Because of the map scale, small areas of different soils may be included within
the mapped areas of a specific soil .
The information is not site specific and does not eliminate the need for onsite
investigation of the soils or for testing and analysis by personnel experienced in the
design and construction of engineering works .
Government ordinances and regulations that restrict certain land uses or impose
specific design criteria were not considered in preparing the information in this table.
Local ordinances and regulations should be considered in planning , in site
selection , and in design .
Report—Ponds and Embankments
[Onsite investigation may be needed to validate the interpretations in this table and
to confirm the identity of the soil on a given site . The numbers in the value columns
range from 0 . 0► 1 to 1 . 00. The larger the value, the greater the potential limitation .
The table shows only the top five limitations for any given soil . The soil may have
additional limitations]
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Custom Soil Resource Report
Ponds and Embankments-Weld County, Colorado, Southern Part
Map symbol and soil Pct. of Embankments, dikes , and Aquifer-fed excavated ponds Pond reservoir areas
name map levees
unit
Rating class and Value Rating class and Value Rating class and Value
limiting features limiting features limiting features
46—Olney fine sandy
loam, 0 to 1 percent
slopes
Olney 85 Somewhat limited Very limited Very limited
Dusty 0.09 Depth to water 1 .00 Seepage 1 .00
47—Olney fine sandy
loam, 1 to 3 percent
slopes
Olney 85 Somewhat limited Very limited Very limited
Dusty 0.09 Depth to water 1 .00 Seepage 1 .00
72—Vona loamy sand,
0 to 3 percent
slopes
Vona 85 Not limited Very limited Very limited
Depth to water 1 .00 Seepage 1 .00
46
References
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Service FWS/OBS-79/31 .
Federal Register. July 13, 1994 . Changes in hydric soils of the United States .
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detail/national/land u s e/rang ep astu re/?cid =stel p rd b 10430 84
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Custom Soil Resource Report
UnitedStates Department of Agriculture, Natural Resources Conservation Service .
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arcs/d etai I/soils/scientists/?cid = nres l 42 p2_054242
United States Department of Agriculture, Natural Resources Conservation Service.
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the Caribbean , and the Pacific Basin . U .S. Department of Agriculture Handbook
296 . http : //www. nres . usda . goviwpslportal/nres/detailinationallsoils/?
cid =nrcs142p2_053624
res 142 p2_6 63624
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capability classification. U .S . Department of Agriculture Handbook 210. http://
www. nrcs . usda.gov/InternetiFSE_DOCUMENTS/nrcs142p2_052290. pdf
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