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WELD COUNTY, COLORADO, SOUTHERN PART 3
— dug many holes to expose soil profiles. A profile is the The general soil map provides a broad perspective of
sequence of natural layers, or horizons, in a soil; it ex- the soils and landscapes in the survey area. It provides a
tends from the surface down into the parent material, basis for comparing the potential of large areas for
which has been changed very little by leaching or by the general kinds of land use. Areas that are, for the most
action of plant roots. part, suited to certain kinds of farming or to other land
The soil scientists recorded the characteristics of the uses can be identified on the map. Likewise, areas of soils
profiles they studied, and they compared those profiles having properties that are distinctly unfavorable for cer-
with others in counties nearby and in places more distant. taro land uses can be located.
Thus, through correlation, they classified and named the Because of its small scale, the map does not show the
soils according to nationwide, uniform procedures. kind of soil at a specific site. Thus, it is not suitable for
After a guide for classifying and naming the soils was planning the management of a farm or field or for select-
worked out, the soil scientists drew the boundaries of the ing a site for a road or building or other structure. The
individual soils on aerial photographs. These photographs kinds of soil in any one map unit differ from place to
show canals, buildings, field borders, roads, and other place in slope, depth, stoniness, drainage, or other charac-
details that help in drawing boundaries accurately. The teristics that affect their management.
soil map at the back of this publication was prepared
from aerial photographs. 1. Midway-Shingle
The areas shown on a soil map are called soil map units. Shallow, moderately sloping to strongly sloping, well
Some map units are made up of one kind of soil, others drained clays and loams formed in residuum from cal-
are made up of two or more kinds of soil, and a few have careous shale
little or no soil material at all. Map units are discussed in This moderately to strongly sloping map unit is in the
the sections "General soil map for broad land use southwestern part of the survey area. It is on the ridge
planning" and "Soil maps for detailed planning."
While a soil curve is i ro crests and side slopes along Coal Creek and its
y n p gress, samples of soils are drainageways.s. It makes up less than 1
taken as needed for laboratory measurements and for en- g y percent of the
per-
gineering tests. The soils are field tested, and interpreta-
cent acreage. About 40 percent is Midway soils, 35 tions of their behavior are modified as necessary during cent is Shingle soils, and 25 percent is soils of minor ex-
the course of the survey. New interpretations tent.
are added Midway and Shingle soils occupy similar positions on
to meet local needs, mainly through field observations of the landscape. Midway soils have a clay surface layer and
different kinds of soil in different uses under different underlying material. Shingle soils have a loam surface
levels of management. Also, data are assembled from layer and clay loam underlying material. Both soils are
other sources, such as test results, records, field ex- underlain by calcareous shale at depths of 10 to 20 inches.
perience, and information available from state and local Minor in this unit are the well drained Renohill and
specialists. For example, data on crop yields under Ulm soils. There are also small sandstone outcrops.
defined practices are assembled from farm records and This map unit is used mainly for rangeland. Small areas
from field or plot experiments on the same kinds of soil. have been cultivated. Shallowness is the main limitation
But only part of a soil survey is done when the soils in farming. The
ran-
have been named, described, interpreted, and delineated potential is fair for development of e
geland wildlife habitat.
on aerial photographs and when the laboratory data and
other data have been assembled. The mass of detailed in- 2. Ulm-Nunn
formation then needs to be organized so that it is readily Dee level to gently sloping,
available to different groups of users, among them far- p' P ng, well drained clay foams and
mers, managers of rangeland, engineers, loaves formed in alluvial and eolian deposits
g g gi planners,
developers and builders, homebuyers, and those seeking This level to gently sloping map unit is on plains and
recreation. old terraces in the southwestern part of the survey area.
It makes up about 1.5 percent of the total acreage. About
40 percent is Ulm soils, 35 percent is Nunn soils, and 25
General soil map for broad land use percent is soils of minor extent.
planning Ulm soils occupy the higher, gently sloping areas, and
Nunn soils the more nearly level areas or the swales. Ulm
The general soil map at the back of this publication soils have a clay loam surface layer and a clay loam sub-
shows, in color, map units that have a distinct pattern of soil.
soils and of relief and drainage. Each map unit is a unique Minor in this unit are the well drained Renohill and
natural landscape. Typically, a map unit consists of one or Wiley soils and the moderately well drained Heldt soils.
more major soils and some minor soils. It is named for This map unit is used mainly for irrigated and nonir-
the major soils. The soils making up one unit can occur in rigated cropland. Some areas are still in rangeland. Slow
other units but in a different pattern. permeability is the main limitation in farming. The poten-
4 SOIL SURVEY
tial for urban development is only fair to poor. The main This nearly level to moderately sloping map unit is on
limitations are moderate to high shrink swell, low plains and alluvial fans throughout the survey area. It
_ strength, and slow permeability. The potential is fair for makes up about 23.5 percent of the total acreage. About
development of openland wildlife habitat. 35 percent is Olney soils, 20 percent is Kim soils, 15 per-
cent is Otero soils, and 30 percent is soils of minor extent.
3. Weld-Colby The soils in this map unit occupy the same relative
Deep, nearly level to moderately sloping, well drained positions on the landscape (fig. 2). Olney soils have a
loans formed in calcareous eolian deposits loamy sand or sandy loam surface layer and a sandy clay
This nearly level to moderately sloping map unit is on loam subsoil. Kim soils have a loam surface layer and
plains mainly in the southeastern part of the survey area. loam and fine sandy loam underlying material. Otero soils
One small area is in the west-central part. The unit makes have a sandy loam surface layer and fine sandy loam un-
up about 10 percent of the total acreage. About 50 per- derlying material.
cent is Weld soils, 35 percent is Colby soils, and 15 per- Minor in this unit are the well drained Ascalon, Nelson,
cent is soils of minor extent. Thedalund, and Vona soils.
Weld soils occupy the broad nearly level areas. Colby This map unit is used for irrigated and nonirrigated
soils occupy the steeper side slopes. Weld soils have a cropland and for rangeland. The potential is good for
loam surface layer and a clay and clay loam subsoil. Colby urban development and fair for wildlife habitat.
soils have a loam surface layer and silt loam underlying 6. Otero-Thedalund-Nelson
material.
Minor in this unit are the well drained Adena and Kim Deep and moderately deep, nearly level to moderately
soils. sloping, well drained sandy loans and clay loams
This map unit is used mainly for cropland. About 65 formed in alluvium and eolian deposits and in residuum
percent is nonirrigated. Winter wheat is the principal from shale and sandstone
crop. If irrigated, the soils are well suited to all commonly This nearly level to moderately sloping map unit is on
grown crops. The potential is fair for development of p g
openland wildlife habitat. plains in the north-central part of the survey area. It
makes up about 3 percent of the total acreage. About 35
4. Wiley-Colby-Weld percent is Otero soils, 25 percent is Thedalund soils, 25
percent is Nelson soils, and 15 percent is soils of minor
Deep, nearly level to moderately sloping, well drained silt extent.
]Dams and loans formed in calcareous eolian deposits Otero soils are on the nearly level or smoother side
This nearly level to moderately sloping map unit is on slopes. Thedalund and Nelson soils are intermingled and
plains in the west-central and southwestern parts of the are on the steeper side slopes. Otero soils have a sandy
survey area. It makes up about 5.5 percent of the total loam surface layer and fine sandy loam underlying
acreage. About 30 percent is Wiley soils, 30 percent is material. Thedalund soils have a loam surface layer and
Colby soils, 15 percent is Weld soils, and 25 percent is underlying material. Shale is between depths of 20 and 40
soils of minor extent. inches. Nelson soils have a fine sandy loam surface layer
Wiley and Colby soils form an intermingled complex and underlying material. Sandstone is between 20 and 40
pattern on the steeper side slopes. Weld soils are along inches.
the narrow ridgetops and on the nearly level side slopes. Minor in this unit are the well drained Kim, Renohill,
Wiley soils have a silt loam surface layer and a silty clay Terry, and Vona soils.
loam subsoil. Colby soils have a loam surface layer and This map unit is used mainly for irrigated cropland. Soil
silt loam underlying material. Weld soils have a loam sur- depth is the main limitation in farming and urban
face layer and a clay loam subsoil. development. The potential is fair for development of
Minor in this unit are the moderately well drained openland wildlife habitat.
Heldt soils and the well drained Nunn and Ulm soils.
This map unit is used mainly for cropland. About 70 7, Tassel-Thedalund-Terry
percent is irrigated and is well suited to all commonly
grown crops. In nonirrigated areas, winter wheat is the Shallow to moderately deep, gently sloping to strongly
principal crop. The potential is fair for urban develop- sloping, well drained sandy loans to clay ]Dams formed
ment. Moderately slow permeability is the main limita- in residuum from sandstone and shale
tion. The potential is also fair for development of open- This gently sloping to strongly sloping map unit is in
land wildlife. the western part of the survey area, adjacent to and in-
cluding the sandstone breaks along some of the major
5. Olney-Kim-Otero streams. It makes up about 1 percent of the total acreage.
Deep, nearly level to moderately sloping, well drained About 50 percent is Tassel soils, 20 percent is Thedalund
sandy loans and loams formed in mixed alluvium and soils, 20 percent is Terry soils, and 10 percent is soils of
eolian deposits minor extent.
SOIL SURVEY
filter the leachate. Sewage lagoons require sealing. 60 percent of the unit. Aquents, which have a lighter
Lawns, shrubs, and trees grow well. Capability subclass colored surface layer. make up about 35 percent. About 5
IIs irrigated. percent is Aquepts and Bankard sandy loam.
2—Altvan loam, 1 to 3 percent slopes. This is a deep. These are deep, poorly drained soils that formed in
well drained soil on terraces at elevations of 4.500 to 4,900 recent alluvium. No one pedon is typical. Commonly the
feet. It formed in old alluvium deposited oy the major soils have a mottled, mildly alkaline to moderately al-
rivers. Included in mapping are small areas of soils that kaline loamy or clayey surface layer and underlying
show evidence of poor drainage. Also included are small, material and are underlain by sand or sand and gravel
long and narrow areas of sand and gravel deposits. within 48 inches. In places they have a gleyed layer in the
Typically the surface layer of this Altvan soil is grayish underlying material.
brown loam about 10 inches thick. The subsoil is brown Most of the acreage is subject to flooding. The water
and light yellowish brown clay loam and sandy clay loam table is at or near the surface early in spring and recede:,
about 14 inches thick. The substratum is calcareous loamy to as deep as 48 inches late in fall in some years.
sand about 5 inches thick over gravelly sand. These soils are used for rangeland and wildlife habitat.
Permeability and available water capacity are Some small areas have been reclaimed by major drainage
moderate. The effective rooting depth is 20 to 40 inches. and leveling and are used for irrigated crops.
Surface runoff is medium, and the erosion hazard is low. The potential native vegetation is dominated by alkali
This soil is used almost entirely for irrigated crops. It sacaton, switchgrass, and western wheatgrass. Saltgrass,
is suited to all crops commonly grown in the area, includ- sedge, rush, and alkali bluegrass are also prominent.
ing corn, sugar beets, beans, alfalfa, small rain, potatoes, Potential production ranges from 3,000 pounds per acre in
and onions. An example of a suitable cropping system is 3 favorable years to 2.000 pounds in unfavorable years. A
to 4 years of alfalfa followed by corn, corn for silage, range condition deteriorates, the switchgrass, alkali
sugar beets, small grain, or beans. Land leveling, ditch sacaton, and western wheatgrass decrease and saltgrass,
lining, and installing pipelines may be needed for proper
sedge, and rush increase.
water application.
Management of vegetation should be based on taking
Al] methods of irrigation are suitable, but furrow ir-
rigation is the most common. Barnyard manure and corn- half and leaving half of the total annual production. Seed-
mercial fertilizer are needed for top yields. ing is difficult and costly because numerous tillage prac-
Windbreaks and environmental plantins of trees and tices are required to eliminate the saltgrass sod.
shrubs commonly grown in the area are generally well Switchgrass, western wheatgrass, alkali sacaton, tall
suited to this soil. Cultivation to control competing wheatgrass, and tall fescue are suitable for seeding. They
vegetation should be continued for as many years as can be seeded into a clean, firm seedbed. Seedbed
possible following planting. Trees that are best suited and preparation usually requires more than 1 year to
have good survival are Rocky Mountain juniper, eastern eliminate the saltgrass sod. A grass drill should be used.
redcedar, ponderosa pine, Siberian elm, Russian-olive, and Seeding early in spring has proven most successful.
hackberry. The shrubs best suited are skunkbush sumac, Wetland wildlife, especially waterfowl, utilize this unit.
The wetland plants provide nesting and protective cover,
lilac, Siberian peashrub, and American plum.
This soil can produce habitat elements that are highly as well as some food. The nearby irrigated cropland,
suitable for openland wildlife including pheasant, cotton- where wildlife obtain much of their food and find protec-
tail, and mourning dove. Such crops as wheat, corn, and tive cover, makes this unit valuable to both wetland and
alfalfa provide suitable habitat for openland wildlife, openland wildlife.
especially pheasant. Tree and shrub plantings and Openland wildlife, especially pheasant, use this unit for
undisturbed nesting cover would enhance openland wil- cover and nesting. Deer find excellent cover in some
dlife populations. areas.
This Altvan soil has fair to good potential for urban These valuable wildlife areas should be protected from
and recreational development. The chief limiting soil fea- fire and fenced to prevent encroachment and overuse by
tures for urban development are the shrink-swell poten- livestock. They should not be drained.
tial of the subsoil as it wets and dries and the rapid These soils have good potential as a source of sand and
permeability of the sand and gravel substratum. Septic gravel. Capability subclass VIw; Salt Meadow range site.
tank absorption fields function properly, but in places the 4—Aquolls and Aquepts, flooded. This nearly level
substratum does not contain enough fines to properly map unit is in depressions in smooth plains and along the
filter the leachate. Sewage lagoons require sealing. bottoms of natural drainageways throughout the survey
Lawns, shrubs, and trees grow well. Capability subclass area. Aquolls, which have a dark colored surface layer.
IIe irrigated. make up about 55 percent of the unit. Aquepts. which
3—Aquolls and Aquents, gravelly substratum. This have a lighter colored surface layer, make up about 25
nearly level map unit is on bottom lands and flood plains percent. About 20 percent is soils that are well drained
of all the major streams in the survey area. Aquolls, and soils that have sandstone or shale within 48 inches of
which have a dark colored surface layer. make up about the surface.
WELD COUNTY, COLORADO, SOUTHERN PART 17
Typically the surface layer of this Colombo soil is dark Wildlife is an important secondary use of this soil. The
grayish brown clay loam about 14 inches thick. The upper cropland areas provide favorable habitat for ring-necked
7 inches of the underlying material is pale brown pheasant and mourning dove. Many nongame species can
stratified clay loam and loam. The lower part to a depth be attracted by establishing areas for nesting and escape
of 60 inches is very pale brown loam stratified with thin cover. For pheasants, undisturbed nesting cover is essen-
lenses of fine sand, medium sand, and clay loam. tial and should be included in plans for habitat develop-
Permeability is moderate. Available water capacity is ment, especially in areas of intensive agriculture. Range-
high. The effective rooting depth is 60 inches or more. land wildlife, for example, the pronghorn antelope, can be
Surface runoff is medium, and the erosion hazard is low. attracted by developing livestock watering facilities,
In irrigated areas this soil is suited to all crops corn- managing livestock grazing, and reseeding where needed.
Where this soil is on flood plains and is susceptible to
monly grown in the area, including corn, sugar beets,
beans, alfalfa, small grain, potatoes, and onions. An exam- flooding, it has poor potential for urban and recreational
ple of a suitable cropping system is 3 to 4 years of alfalfa development. On the higher terraces, potential is fair.
followed by corn, corn for silage, sugar beets, small grain, Dwelling and road designs may need to be modified to
or beans. Land leveling, ditch lining, and installing compensate for the limited capacity of this soil to support
a load and to protect it against frost action. Capability
pipelines may be needed for proper water application.
All methods of irrigation are suitable, but furrow ir- subclass lie irrigated, Ilknonirrigated; Clayey Plains
rigation is the most common. Barnyard manure and corn- range site.
21—Dacono clay loam, 0 to 1 percent slopes. This is a
mercial fertilizer are needed for top yields. deep, well drained soil on terraces at elevations of 4,550
In nonirrigated areas this soil is well suited to winter to 4,970 feet. It formed in mixed alluvium. Included in
wheat, barley, and sorghum if it is summer fallowed in al- mapping are small, long and narrow areas of sand and
ternate years. Winter wheat is the principal crop. The gravel deposits and some small leveled areas.
predicted average yield is 33 bushels per acre. If the crop Typically the surface layer of this Dacono soil is gray-
is winterkilled, spring wheat can be seeded. Generally ish brown clay loam about 12 inches thick. The subsoil is
precipitation is too low for beneficial use of fertilizer. grayish brown clay loam about 15 inches thick. The sub-
Stubble mulch farming, striperopping, and minimum til- stratum is very gravelly sand.
lage are needed to control soil blowing and water erosion. Permeability is moderately slow. Available water
Terracing also may be needed to control water erosion. capacity is moderate. The effective rooting depth is 20 to
— The potential native vegetation is dominated by 40 inches. Surface runoff is slow, and the erosion hazard
western wheatgrass. Blue grama, switchgrass, sand is low.
reedgrass, big bluestem, slender wheatgrass, indiangrass, This soil is used almost entirely for irrigated crops. It
and green needlegrass are also present. Potential produc- is suited to all crops commonly grown in the area, includ-
tion ranges from 1,000 pounds per acre in favorable years ing corn, sugar beets, beans, alfalfa, small grain, potatoes,
to 600 pounds in unfavorable years. As range condition and onions. An example of a suitable cropping system is 3
deteriorates, the tall grasses decrease, blue grama and to 4 years of alfalfa followed by corn, corn for silage,
buffalograss increase, and forage production drops. Un- sugar beets, small grain, or beans. Generally, such charac-
desirable weeds and annuals invade the site and erosion teristics as a high clay content or a rapidly permeable
can occur as range condition becomes poorer. substratum slightly restrict some crops.
Management of vegetation on this soil should be based All methods of irrigation are suitable, but furrow ir-
on taking half and leaving half of the total annual produc- rigation is the most common. Proper irrigation water
tion. Seeding is desirable if the range is in poor condition. management is essential. Barnyard manure and commer-
Western wheatgrass, switchgrass, sand reedgrass, cial fertilizer are needed for top yields.
Windbreaks and environmental plantings of trees and
sideoats grama, pubescent wheatgrass, intermediate
wheatgrass, and blueshrubs commonly grown in the area are generally well
gr grama are suitable for seeding. The suited to this soil. Cultivation to control competing
grass selected should meet the seasonal requirements of vegetation should be continued for as many years as
livestock. It can be seeded into a firm prepared seedbed. possible following v l planting.e Trees that are best p suited and
A grass drill should be used. Seeding early in spring has have good survival are Rocky Mountain juniper, eastern
proven most successful.
redcedar, ponderosa pine, Siberian elm, Russian-olive, and
Windbreaks and environmental plantings of trees and hackberry. The shrubs best suited are skunkbush sumac,
shrubs commonly grown in the area are generally well lilac, Siberian peashrub, and American plum.
suited to this soil. Cultivation to control competing Openland wildlife, such as pheasant, mourning dove,
vegetation should be continued for as many years as and cottontail are best suited to this soil. Wildlife habitat
possible following planting. Trees that are best suited and development, including tree and shrub plantings and
have good survival are Rocky Mountain juniper, eastern grass plantings to serve as nesting areas, should be suc-
redcedar, ponderosa pine, Siberian elm, Russian-olive, and cessful without irrigation during most years. Under ir-
hackberry. The shrubs best suited are skunkbush sumac, rigation, good wildlife habitat can be established, benefit-
ilac, Siberian peashrub, and American plum. ing, many kinds of openland wildlife.
18 SOIL SURVEY
This soil has only fair potential for urban and recrea- prepared seedbed. Seeding early in spring has proven
tional development. Above the sand and gravel sub- most successful.
stratum the soil has moderate to high shrink swell, low Windbreaks and environmental plantings of trees and
strength, and moderately slow permeability. These fea- shrubs commonly grown in the area are generally well
tures create problems in dwelling and road construction. suited to this soil. Cultivation to control competing
Excessive permeability in the substratum can cause con- vegetation should be continued for as many years as
tamination of the ground water supply from septic tank possible following planting. Trees that are best suited and
leach fields. Sewage lagoons need to be lined. Capability have good survival are Rocky Mountain juniper, eastern
subclass Its irrigated. redcedar, ponderosa pine, Siberian elm, Russian-olive, and
22—Dacono clay loam, 1 to 3 percent slopes. This is a hackberry. The shrubs best suited are skunkbush sumac,
deep, well drained soil on terraces at elevations of 4,550 lilac, Siberian peashrub, and American plum.
to 4,970 feet. It formed in mixed alluvium. Included in Openland wildlife, such as pheasant, mourning dove,
mapping are small, long and narrow areas of sand and and cottontail, are best suited to this soil. Wildlife habitat
gravel deposits and some small leveled areas. development, including tree and shrub plantings and
Typically the surface layer of this Dacono soil is gray- grass plantings to serve as nesting areas, should be suc-
ish brown clay loam about 12 inches thick. The subsoil is cessful without irrigation during most years. Under ir-
grayish brown clay loam about 15 inches thick. The sub- rigation, good wildlife habitat can established, benefiting
stratum is very gravelly sand. many kinds of openland wildlife. Rangeland wildlife, for
Permeability is moderately slow. Available water example, the pronghorn antelope, can be attracted by
capacity is moderate. The effective rooting depth is 20 to developing livestock watering facilities, managing
40 inches. Surface runoff is medium, and the erosion livestock grazing, and reseeding where needed.
hazard is low. This soil has only fair potential for urban and recrea-
In irrigated areas this soil is suited to all crops com- tional development. Above the sand and gravel sub-
monly grown in the area, including corn, sugar beets, stratum the soil has a moderate to high shrink-swell
beans, alfalfa, small grain, potatoes, and onions. An exam- potential, low strength, and moderately slow permeability.
ple of a suitable cropping system is 3 to 4 years of alfalfa These features create problems in dwelling and road con-
followed by corn, corn for silage, sugar beets, small grain, struction. Excessive permeability in the substratum can
or beans. Generally, such characteristics as a high clay cause contamination of the ground water supply from
content or a rapidly permeable substratum slightly septic tank leach fields. Sewage lagoons need to be lined.
restrict some crops. Capability subclass Ile irrigated, IIIc nonirrigated;
All methods of irrigation are suitable, but furrow ir- Clayey Plains range site.
rigation is the most common. Proper irrigation water 23—Fort Collins loam, 0 to 1 percent slopes. This is a
management is essential. Barnyard manure and commer- deep, well drained soil on terraces and smooth plains at
cial fertilizer are needed for top yields. elevations of 4,500 to 5,050 feet. It formed in alluvium
In nonirrigated areas most of the acreage is in small modified by thin eolian deposits. Included in mapping are
grain and is summer fallowed in alternate years. Winter some small leveled areas and few small areas of a soil
wheat is the principal crop. The predicted average yield is that is calcareous at the surface.
33 bushels per acre. If the crop is winterkilled, spring Typically the surface layer of this Fort Collins soil is
wheat can be seeded. Generally precipitation is too low grayish brown loam about 10 inches thick. The subsoil is
for beneficial use of fertilizer. brown and very pale brown clay loam and loam about 20
Stubble mulch farming, striperopping, and minimum til- inches thick. The substratum to a depth of 60 inches is
lage are needed to control soil blowing and water erosion. fine sandy loam.
The potential native vegetation is dominated by Permeability is moderate. Available water capacity is
western wheatgrass and blue grama. Buffalograss is also high. The effective rooting depth is 60 inches or more.
present. Potential production ranges from 1,000 pounds Surface runoff is slow, and the erosion hazard is low.
per acre in favorable years to 600 pounds in unfavorable This soil is used almost entirely for irrigated crops. It
years. As range condition deteriorates, a blue grama-buf- is suited to all crops commonly grown in the area, includ-
falograss sod forms. Undesirable weeds and annuals in- ing corn, sugar beets, beans, alfalfa, small grain, potatoes,
vade the site as range condition becomes poorer. and onions. An example of a suitable cropping system is 3
Management of vegetation on this soil should be based to 4 years of alfalfa followed by corn, corn for silage,
on taking half and leaving half of the total annual produc- sugar beets, small grain, or beans. Few conservation prac-
tion. Range pitting can help in reducing runoff. Seeding is tices are needed to maintain top yields.
desirable if the range is in poor condition. Western All methods of irrigation are suitable, but furrow ir-
wheatgrass, blue grama, sideoats grama, buffalograss, pu- rigation is the most common. Barnyard manure and com-
bescent wheatgrass, and crested wheatgrass are suitable mercial fertilizer are needed for top yields.
for seeding. The grass selected should meet the seasonal Windbreaks and environmental plantings of trees and
requirements of livestock. It can be seeded into a clean, shrubs commonly grown in the area are generally well
firm sorghum stubble or it can be drilled into a firm suited to this soil. Cultivation to control competing
28 SOIL SURVEY
40—Nunn loam, 1 to 3 percent slopes. This is a deep, vegetation should be continued for as many years as
well drained soil on terraces at elevations of 4,550 to 5,000 possible following planting. Trees that are best suited and
feet. It formed in mixed alluvium. Included in mapping have good survival are Rocky Mountain juniper, eastern
are small, long and narrow areas of sand and gravel redcedar, ponderosa pine, Siberian elm, Russian-olive, and
deposits and small areas of soils that are subject to occa- hackberry. The shrubs best suited are skunkbush sumac,
sional flooding. Some leveled areas are also included. lilac, Siberian peashrub, and American plum.
Typically the surface layer of this Nunn soil is grayish Wildlife is an important secondary use of this soil. The
brown loam about 12 inches thick. The subsoil is light cropland areas provide favorable habitat for ring-necked
brownish gray clay loam about 12 inches thick. The upper pheasant and mourning dove. Many nongame species can
part of the substratum is light brownish gray clay loam. be attracted by establishing areas for nesting and escape
The lower part to a depth of 60 inches is brown sandy cover. For pheasants, undisturbed nesting cover is essen-
loam. tial and should be included in plans for habitat develop-
Permeability is moderately slow. Available water ment, especially in areas of intensive agriculture. Range-
capacity is high. The effective rooting depth is 60 inches land wildlife, for example, the pronghorn antelope, can be
or more. Surface runoff is medium, and the erosion attracted by developing livestock watering facilities,
hazard is low. managing livestock grazing, and reseeding where needed.
In irrigated areas this soil is suited to all crops com- This soil has fair to poor potential for urban develop-
monly grown in the area, including corn, sugar beets, ment. It has moderate to high shrink swell, low strength,
beans, alfalfa, small grain, potatoes, and onions. An exam- and moderately slow permeability. These features create
ple of a suitable cropping system is 3 to 4 years of alfalfa problems in dwelling and road construction. Those areas
followed by corn, corn for silage, sugar beets, small grain, that have loam or sandy loam in the lower part of the
or beans. Generally such characteristics as a high clay substratum are suitable for septic tank absorption fields
content or a rapidly permeable substratum slightly and foundations. Some areas of this soil are adjacent to
restrict some crops. streams and are subject to occasional flooding. The poten-
All methods of irrigation are suitable, but fun-ow ir- tial is fair for such recreational development as camp and
rigation is the most common. Proper irrigation water picnic areas and playgrounds. Capability subclass Ile ir-
management is essential. Barnyard manure and commer- rigated, IIIc nonirrigated; Loamy Plains range site.
cial fertilizer are needed for top yields. 41—Nunn clay loam, 0 to 1 percent slopes. This is a
Most nonirrigated areas are used for small grain. The deep, well drained soil on terraces and smooth plains at
soil is summer fallowed in alternate years. Winter wheat elevations of 4,550 to 5,150 feet. It formed in mixed allu-
- is the principal crop. If the crop is winterkilled, spring vium and eolian deposits. Included in mapping are small,
wheat can be seeded. Generally precipitation is too low long and narrow areas of sand and gravel deposits and
for beneficial use of fertilizer. small areas of soils that are subject to occasional flooding.
Such practices as stubble mulch fanning, striperopping, Some small leveled areas are also included.
and minimum tillage are needed to control soil blowing Typically the surface layer of this Nunn soil is grayish
and water erosion. brown clay loam about 9 inches thick. The subsoil is light
The potential native vegetation is dominated by blue brownish gray clay loam about 14 inches thick. The upper
grama. Several mid grasses, such as western wheatgrass part of the substratum is clay loam. The lower part to a
and needleandthread, are also present. Potential produc- depth of 60 inches is sandy loam.
tion ranges from 1,600 pounds per acre in favorable years Permeability is moderately slow. Available water
to 1,000 pounds in unfavorable years. As range condition capacity is high. The effective rooting depth is 60 inches
deteriorates, the mid grasses decrease; blue grama, buf- or more. Surface runoff is slow, and the erosion hazard is
falograss, snakeweed, yucca, and fringed sage increase; low.
and forage production drops. Undesirable weeds and an- This soil is used almost entirely for irrigated crops. It
nuals invade the site as range condition becomes poorer. is suited to all crops commonly grown in the area, includ-
Management of vegetation on this soil should be based ing corn, sugar beets, beans, alfalfa, small grain, potatoes,
on taking half and leaving half of the total annual produc- and onions. An example of a suitable cropping system is 3
tion. Seeding is desirable if the range is in poor condition. to 4 years of alfalfa followed by corn, corn for silage,
Sideoats grama, little bluestem, western wheatgrass, blue sugar beets, small grain, or beans. Few conservation prac-
grama, pubescent wheatgrass, and crested wheatgrass are tices are needed to maintain top yields.
suitable for seeding. The grass selected should meet the All methods of irrigation are suitable, but furrow ir-
seasonal requirements of livestock. It can be seeded into rigation is the most common. Barnyard manure and com-
a clean, firm sorghum stubble, or it can be drilled into a mercial fertilizer are needed for top yields.
firm prepared seedbed. Seeding early in spring has Windbreaks and environmental plantings of trees and
proven most successful. shrubs commonly grown in the area are generally well
Windbreaks and environmental plantings of trees and suited to this soil. Cultivation to control competing
shrubs commonly grown in the area are generally well vegetation should be continued for as many years as
suited to this soil. Cultivation to control competing possible following planting. Trees that are best suited and
WELD COUNTY, COLORADO, SOUTHERN PART 29
have good survival are Rocky Mountain juniper, eastern The potential native vegetation is dominated by
redcedar, ponderosa pine, Siberian elm, Russian-olive, and western wheatgrass and blue grama. Buffalograss is also
hackberry. The shrubs best suited are skunkbush sumac, present. Potential production ranges from 1,000 pounds
lilac, Siberian peashrub, and American plum. per acre in favorable years to 600 pounds in unfavorable
Wildlife is an important secondary use of this soil. The years. As range condition deteriorates, a blue grama-buf-
cropland areas provide favorable habitat for ring-necked falograss sod forms. Undesirable weeds and annuals in-
pheasant and mourning dove. Many nongame species can vade the site as range condition becomes poorer.
be attracted by establishing areas for nesting and escape Management of vegetation of this soil should be based
cover. For pheasants, undisturbed nesting cover is essen- on taking half and leaving half of the total annual produc-
tial and should be included in plans for habitat develop- tion. Range pitting can help in reducing runoff. Seeding is
ment, especially in areas of intensive agriculture. desirable if the range is in poor condition. Western
This soil has fair to poor potential for urban develop- wheatgrass, blue grama, sideoats grama, buffalograss, pu-
ment. It has moderate to high shrink swell, low strength, bescent wheatgrass, and crested wheatgrass are suitable
and moderately slow permeability. These features create for seeding. The grass selected should meet the seasonal
problems in dwelling and road construction. Those areas requirements of livestock. It can be seeded into a clean,
that have loam or sandy loam in the lower part of the firm sorghum stubble, or it can be drilled into a firm
substratum are suitable for septic tank absorption fields prepared seedbed. Seeding early in spring has proven
and foundations. Some areas of this soil are adjacent to most successful.
streams and are subject to occasional flooding. The poten- Windbreaks and environmental plantings are generally
tial is fair for such recreational development as camp and well suited to this soil. Cultivation to control competing
picnic areas and playgrounds. Capability class I irrigated. vegetation should be continued for as many years as
42—Nunn clay loam, 1 to 3 percent slopes. This is a possible following planting. Trees that are best suited and
deep, well drained soil on terraces and smooth plains at have good strvival are Rocky Mountain juniper, eastern
elevations of 4,550 to 5,150 feet. It formed in mixed allu- redcedar, ponderosa pine, Siberian elm, Russian-olive, and
vium and eolian deposits. Included in mapping are small, hackberry. The shrubs best suited are skunkbush sumac,
long and narrow areas of sand and gravel deposits and lilac, Siberian peashrub, and American plum.
small areas of soils that are subject to occasional flooding. Wildlife is an important secondary use of this soil. The
Some leveled areas are also included. cropland areas provide favorable habitat for ring-necked
Typically the surface layer of this Nunn soil is grayish pheasant and mourning dove. Many nongame species can
brown clay loam aobut 9 inches thick. The subsoil is light be attracted by establishing areas for nesting and escape
brownish gray clay loam about 14 inches thick. The upper cover. For pheasants, undisturbed nesting cover is essen-
part of the substratum is light brownish gray clay loam. tial and should be included in plans for habitat develop-
The lower part to a depth of 60 inches is brown sandy ment, especially in areas of intensive agriculture. Range-
loam. land wildlife, for example, the pronghorn antelope, can be
Permeability is moderately slow. Available water attracted by developing livestock watering facilities,
capacity is high. The effective rooting depth is 60 inches managing livestock grazing, and reseeding where needed.
or more. Surface runoff is medium, and the erosion This soil has fair to poor potential for urban develop-
hazard is low. ment. It has moderate to high shrink swell, low strength,
In irrigated areas this soil is suited to all crops com- and moderately slow permeability. These features create
monly grown in the area, including corn, sugar beets, problems in dwelling and road construction. Those areas
beans, alfalfa, small grain, potatoes, and onions. An exam- that have loam or sandy loam in the lower part of the
pie of a suitable cropping system is 3 to 4 years of alfalfa substratum are suitable for septic tank absorption fields
followed by corn, corn for silage, sugar beets, small grain, and foundations. Some areas of this soil are adjacent to
or beans. Generally such characteristics as the high clay streams and are subject to occasional flooding. The poten-
content or the rapidly permeable substratum slightly tial is fair for such recreational development as camp and
restrict some crops. picnic areas and playgrounds. Capability subclass IIe ir-
All methods of irrigation are suitable, but furrow ir- rigated, IlIc nonirrigated; Clayey Plains range site.
rigation is the most common. Proper irrigation water 43—Nunn loamy sand, 0 to 1 percent slopes. This is a
management is essential. Barnyard manure and commer- deep, well drained soil on terraces at elevations of 4,700
cial fertilizer are needed for top yields. to 4,900 feet. It formed in alluvium along Box Elder
In nonirrigated areas most of the acreage is in small Creek. Included in mapping are small areas of soils that
grain and it is summer fallowed in alternate years. have a loamy subsoil and small areas of soils that are sub-
Winter wheat is the principal crop. The predicted average ject to rare flooding.
yield is 33 bushels per acre. If the crop is winterkilled, Typically the surface layer of this Nunn soil is brown
spring wheat can be seeded. Generally precipitation is too loamy sand overburden about 9 inches thick. The subsoil
low for beneficial use of fertilizer. is dark to very dark grayish brown clay loam about 21
Stubble mulch farming, striperopping, and minimum til- inches thick. The substratum to a depth of 60 inches is
lage are needed to control soil blowing and water erosion. loamy very fine sand, loamy sand, or sand.
.... ... .. ._
f WELD COUNTY, COLORADO, SOUTHERN PART 35
and switchgrass decrease and blue grama, sand dropseed, should be grown at least 50 percent of the time. Contour
and sand sage increase. Annual weeds and grasses invade ditches and corrugations can be used in irrigating close
the site as range condition becomes poorer. grown crops and pasture. Furrows, contour furrows, and
Management of vegetation on this soil should be based cross slope furrows are suitable for row crops. Sprinkler
on taking half and leaving half of the total annual produc- irrigation is also desirable. Keeping tillage to a minimum
tion. Seeding is desirable if the range is in poor condition. and utilizing crop residue help to control erosion. Main-
Sand bluestem, sand reedgrass, switchgrass, sideoats taining fertility is important. Crops respond to applica-
grama, blue grama, pubescent wheatgrass, and crested tions of phosphorus and nitrogen.
wheatgrass are suitable for seeding. The grass selected The potential native vegetation on this site is
should meet the seasonal requirements of livestock. It can dominated by sand bluestem, sand reedgrass, and blue
be seeded into a clean, rim stubble, or it can be drilled grama. Needleandthread, switchgrass, sideoats grama,
into a firm prepared seedbed. Seeding early in spring has and western wheatgrass are also prominent. Potential
proven most successful. production ranges from 2,200 pounds per acre in favora-
Windbreaks and environmental plantings are generally ble years to 1,800 pounds in unfavorable years. As range
suited to this soil. Soil blowing, the principal hazard in condition deteriorates, the sand bluestem, sand reedgrass,
establishing trees and shrubs, can be controlled by cul- and switchgrass decrease, and blue grama, sand dropseed,
tivating only in the tree row and by leaving a strip of and sand sage increase. Annual weeds and grasses invade
vegetation between the rows. Supplemental irrigation the site as range condition becomes poorer.
may be needed at the time of planting and during dry Management of vegetation on this soil should be based
periods. Trees that are best suited and have good survival on taking half and leaving half of the total annual produc-
are Rocky Mountain juniper, eastern redcedar, ponderosa tion. Seeding is desirable if the range is in poor condition.
pine, Siberian elm, Russian-olive, and hackberry. The Sand bluestem, sand reedgrass, switchgrass, sideoats
' shrubs best suited are skunkbush sumac, lilac, and Siberi- grama, blue grama, pubescent wheatgrass, and crested
an peashrub. wheatgrass are suitable for seeding. The grass selected
Wildlife is an important secondary use of this soil. should meet the seasonal requirements of livestock. It can
Ring-necked pheasant, mourning dove, and many non- be seeded into a clean, firm sorghum stubble, or it can be
game species can be attracted by establishing areas for drilled into a firm prepared seedbed. Seeding early in
nesting and escape cover. For pheasants, undisturbed spring has proven most successful. -
nesting cover is essential and should be included in plans Windbreaks and environmental plantings are generally
for habitat development, especially in areas of intensive suited to this soil. Soil blowing, the principal hazard in
agriculture. establishing trees and shrubs, can be controlled by cul-
Rapid expansion of Greeley and the surrounding area tivating only in the tree row and by leaving a strip of
has resulted in urbanization of much of this Otero soil. vegetation between the rows. Supplemental irrigation
This soil has excellent potential for urban and recrea- may be needed at the time of planting and during dry
tional development. The only limiting feature is the periods. Trees that are best suited and have good survival
moderately rapid permeability in the substratum, which are Rocky Mountain juniper, eastern redcedar, ponderosa
causes a hazard of ground water contamination from pine, Siberian elm, Russianolive, and hackberry. The
sewage lagoons. Lawns, shrubs, and trees grow well. shrubs best suited are skunkbush sumac, lilac, and Siberi-
Capability subclass IIIe irrigated, IVe nonirrigated; an peashrub.
Sandy Plains range site. Wildlife is an important secondary use of this soil.
52—Otero sandy loam, 3 to 5 percent slopes. This is a Ring-necked pheasant, mourning dove, and many non-
deep, well drained soil on plains at elevations of 4,700 to game species can be attracted by establishing areas for
5,250 feet. It formed in mixed outwash and eolian nesting and escape cover. For pheasants, undisturbed
deposits. Included in mapping are small areas of soils that nesting cover is essential and should be included in plans
have loam and clay loam underlying material. Also in- for habitat development, especially in areas of intensive
eluded are small areas of soils that have sandstone and agriculture.
shale within a depth of 60 inches. Rapid expansion of Greeley and the surrounding area
Typically the surface layer of this Otero soil is brown has resulted in urbanization of much of this Otero soil.
sandy loam about 10 inches thick. The underlying material The soil has excellent potential for urban and recreational
to a depth of 60 inches is pale brown calcareous fine development. The only limiting feature is the moderately
sandy loam. rapid permeability in the substratum, which causes a
Permeability is rapid. Available water capacity is hazard of ground water contamination from sewage
moderate. The effective rooting depth is 60 inches or lagoons. Lawns, shrubs, and trees grow well. Capability
more. Surface runoff is medium, and the erosion hazard is subclass file irrigated, Vie nonirrigated; Sandy Plains
low, range site.
This soil is used almost entirely for irrigated crops. It 53—Otero sandy loam, 5 to 9 percent slopes. This is a
is suited to the crops commonly grown in the area. deep, well drained soil on plains at elevations of 4,700 to
Perennial grasses and alfalfa or close growing crops 5,250 feet. It formed in mixed outwash and eolian
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