• TABLE OF CONTENTS
HIDE
 Front Cover
 Title Page
 Table of Contents
 Introduction
 Area covered in the analysis
 Erosion in the area
 Land type map
 Land types
 Crop yields
 Summary and conclusions
 Back Matter
 Land type map






Group Title: Bulletin
Title: Land types in eastern Colorado
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00082693/00001
 Material Information
Title: Land types in eastern Colorado
Alternate Title: Bulletin 486 ; Colorado Agricultural Experiment Station
Physical Description: 45 p. : ill., maps ; 23 cm. +
Language: English
Creator: Brown, L. A ( Lindsey Andrew ), 1906-
Romine, D. S.
Burdick, R. T.
Kezer, Alvin
Publisher: Colorado Agricultural Experiment Station, Colorado State College
Place of Publication: Fort Collins
Publication Date: June, 1944
Copyright Date: 1944
 Subjects
Subject: Land capability for agriculture -- Colorado   ( lcsh )
Land use, Rural -- Colorado   ( lcsh )
Soils -- Colorado   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: L.A. Brown ... et al..
 Record Information
Bibliographic ID: UF00082693
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 21880552

Table of Contents
    Front Cover
        Front Cover
    Title Page
        Page 1
    Table of Contents
        Page 2
    Introduction
        Page 3
    Area covered in the analysis
        Page 3
    Erosion in the area
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
    Land type map
        Page 10
    Land types
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
    Crop yields
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
    Summary and conclusions
        Page 44
        Page 45
    Back Matter
        Page 46
        Page 47
        Page 48
    Land type map
        Page 49
Full Text


BULLETIN 486


Peter E. Hildebrand
Agricultural Economics


andeT 7pea

em SEaternw oorado

L. A. BROWN, D. S. ROMINE,
R. T. BURDICK, AND ALVIN KEZER

COLORADO AGRICULTURAL EXPERIMENT STATION
COLORADO STATE COLLEGE
FORT COLLINS


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JUNE 1944






BULLETIN 486


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m Saatee o&4woad

L. A. BROWN, D. S. ROMINE,
R. T. BURDICK, AND ALVIN KEZER

COLORADO AGRICULTURAL EXPERIMENT STATION
COLORADO STATE COLLEGE
FORT COLLINS


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C OLOR





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JUNE 1944












CONTENTS


Page
Introduction .................... ........................... 3
Area covered in the analysis.................................... 3
Erosion in the area .................... ............................. 4
Land type map ................ ......................10
L and types ..................................... ........... ....... ...............11
Soils of the nearly level uplands and terraces ..............................11
Dark silty soils (hard lands) ...................................... ....... 11
Dark sandy soils (sandy lands) ................... ....................... 14
Brown silty soils (hard lands) ........................ ......... ............16
Brown silty soils (hard lands) of the rolling uplands ...................18
Soils of the nearly level to gently rolling uplands and terraces....20
Brown sandy soils (sandy lands) .....................................20
Light brown silty soils (hard lands) ......................................22
Clay soils (gumbo or heavy lands) ............................................23
Soils of the rolling to steep uplands ......... ...............................24
Undifferentiated shallow soils (hilly land) ......... ............24
Undifferentiated soils of the mountain-plains transition.........25
Sand soils and sands (sandhills) .................................................26
Irrigated and alluvial land ................................ ..................... .....27
Crop yields ........................ ....... .................27
Basis for crop yields and yield distribution .................................33
Interpretation of yield graphs .................... ....... .........33
Grouping average crop yields ...................... .................38
Cost of production in terms of crop yields ....................................39
Summary and conclusions ................................................... 44











4aad 7Tpe4 s Eastern eorado

Their Influence on Crop Yields and Land Use in the
Various Climatic Zones of the Area (Dry Land)

L. A. BROWN, D. S. ROMINE, R. T. BURDICK, AND ALVIN KEZER'

IN PLANNING LAND USE many criteria and indices of values
have been used. The physical features of the land too often have
been relegated to a place of secondary importance.
Whether a farmer is planning next year's crops, or a county is
planning for the coming generation, or a nation is planning its possi-
bilities of production under the burdens of war, plans can be no more
sound than the analysis of the basic data. Basic physical factors
include soils, slope or lay of land, and climate.
The primary object of an analysis of physical factors affecting
crop production is to determine their effect on yields of adapted
crops. It is the purpose of this bulletin to contribute to the knowl-
edge of the land resources of eastern Colorado by showing the dis-
tribution of the various land types in the area and how these land
types, in conjunction with the prevailing climatic conditions, influ-
ence crops grown, yields obtained, cultural practices, and land use
on non-irrigated lands in the various climatic zones.
A land type map, graphs, and tables are included to show some of
the relationships of land types and crop yields in eastern Colorado.

AREA COVERED IN THE ANALYSIS
Eastern Colorado is regarded as that portion of the State that is
in the High Plains region. It is east of the Rocky Mountain Range
front (fig. 1) and occupies about 45,000 square miles. Figure 2, a
relief map of Colorado, shows the eastern part of the State as a rela-
tively smooth eastward sloping plain crossed by the rather shallow
valleys of the South Platte, Republican, and Arkansas Rivers and
their major and minor tributaries.
Eastern Colorado is about 3,350 feet above sea level at its lowest
point where the Arkansas River flows into Kansas. The highest
portions of the area are the Platte-Arkansas Divide, known as the
'Brown, formerly associate agronomist, Colorado Agricultural Experiment
Station, now area soils scientist, Farm Security Administration; Romine, asso-
ciate agronomist (soils); Burdick, acting rural economist; Kezer,- chief
agronomist, Colorado Agricultural Experiment Station.
Credit is due R. H. Hausenbuiller and J. M. Allen, former student assistants
in agronomy, for drafting assistance on the land type map and graphs. J. F.
Brandon, superintendent, U. S. Dry Land Field Station, B. G. West and J. L.
Nielsen, soil scientists, Soil Conservation Service, contributed valuable com-
ments in the preparation of the final manuscript.











4aad 7Tpe4 s Eastern eorado

Their Influence on Crop Yields and Land Use in the
Various Climatic Zones of the Area (Dry Land)

L. A. BROWN, D. S. ROMINE, R. T. BURDICK, AND ALVIN KEZER'

IN PLANNING LAND USE many criteria and indices of values
have been used. The physical features of the land too often have
been relegated to a place of secondary importance.
Whether a farmer is planning next year's crops, or a county is
planning for the coming generation, or a nation is planning its possi-
bilities of production under the burdens of war, plans can be no more
sound than the analysis of the basic data. Basic physical factors
include soils, slope or lay of land, and climate.
The primary object of an analysis of physical factors affecting
crop production is to determine their effect on yields of adapted
crops. It is the purpose of this bulletin to contribute to the knowl-
edge of the land resources of eastern Colorado by showing the dis-
tribution of the various land types in the area and how these land
types, in conjunction with the prevailing climatic conditions, influ-
ence crops grown, yields obtained, cultural practices, and land use
on non-irrigated lands in the various climatic zones.
A land type map, graphs, and tables are included to show some of
the relationships of land types and crop yields in eastern Colorado.

AREA COVERED IN THE ANALYSIS
Eastern Colorado is regarded as that portion of the State that is
in the High Plains region. It is east of the Rocky Mountain Range
front (fig. 1) and occupies about 45,000 square miles. Figure 2, a
relief map of Colorado, shows the eastern part of the State as a rela-
tively smooth eastward sloping plain crossed by the rather shallow
valleys of the South Platte, Republican, and Arkansas Rivers and
their major and minor tributaries.
Eastern Colorado is about 3,350 feet above sea level at its lowest
point where the Arkansas River flows into Kansas. The highest
portions of the area are the Platte-Arkansas Divide, known as the
'Brown, formerly associate agronomist, Colorado Agricultural Experiment
Station, now area soils scientist, Farm Security Administration; Romine, asso-
ciate agronomist (soils); Burdick, acting rural economist; Kezer,- chief
agronomist, Colorado Agricultural Experiment Station.
Credit is due R. H. Hausenbuiller and J. M. Allen, former student assistants
in agronomy, for drafting assistance on the land type map and graphs. J. F.
Brandon, superintendent, U. S. Dry Land Field Station, B. G. West and J. L.
Nielsen, soil scientists, Soil Conservation Service, contributed valuable com-
ments in the preparation of the final manuscript.








4 COLORADO AGRICULTURAL EXPERIMENT STATION


Black Forest (fig. 3), which is about 7,500 feet, and Raton Mesa,
near Trinidad, which is about 9,000 feet above sea level.
The climate of eastern Colorado is continental and temperate. It
is characterized by high summer temperatures, low winter tempera-
tures, and variable, relatively low precipitation. Mean annual
precipitation varies from 11 inches in parts of the Arkansas Valley
to about 18 inches in the northeastern part of the area and in parts
of the Black Forest. Furthermore, precipitation as low as 2.4
inches and as high as 36.2 inches has been recorded for a single
year. This range in precipitation and differences in other climatic
factors produce a wide variation in soil properties and the effective-
ness of the moisture in producing plant growth. Dotted line bound-
aries on the accompanying land type map divide eastern Colorado
into four climatic zones, dependent on the effective precipitation.
The lines are based on U. S. Weather Bureau records of precipita-
tion, seasonal distribution of the rainfall, temperature, and evapora-
tion. Mature soil characteristics, altitude, and crop yields were
used in certain parts of the area as a guide in determining the
effective precipitation zone boundaries.

EROSION IN THE AREA
Land in eastern Colorado is subject to both wind and water
erosion. The susceptibility of the grass land to erosion depends
primarily on the extent of the vegetative cover. In general, the

Figure 1.-Looking eastward over the plains from Pikes Peak. The city of
Colorado Springs is in the middle background. Wooded areas of the Black
Forest show in upper left background.


Bulletin 486




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Figure 2.-Relief imap of Colorado showing Continental Divide and the
drainage basins of the South Platte, Republican, amd Arkansas Rivers.

damage to grazing land caused by soil removal, except in overgrazed
areas, is slight. However, severe damage to grassed areas by soil
deposition from wind action has occurred on range land adjacent
to eroding cultivated fields. These eroding areas are the source of
the accumulations that blow across and destroy the native grass
cover.
The land under cultivation varies widely in its susceptibility
to wind and water erosion, depending primarily on relief, degree
of protection by vegetative cover, intensity of the rainfall, and the
inherent erodibility of the soil itself. Many areas of highly erod-
ible soils that have been broken at various times in the past for
crop production have been severely damaged by both wind and
water erosion.
In general, sandy soils, particularly those low in organic mat-
ter, are more highly susceptible to wind action than are silty soils
in the same precipitation zone (fig. 4). Sand soils and sands blow
readily because of the low content of organic matter, silt, and clay
which are the binding substances necessary for the formation of
wind-resistant soil aggregates. The raw sands are loose and in-
coherent, and susceptibility to wind erosion is extremely high. In







6 COLORADO AGRICULTURAL EXPERIMENT STATION Bulletin 486

the sandhill areas many "blowout" spots occur near watering places
and bed grounds where the protective cover is usually thin or en-
tirely lacking.
In discussing the susceptibility of sandy soils and silty soils to
wind erosion, it is important to point out that under the same cli-
matic conditions revegetation and consequent stabilization are less
difficult to establish and maintain on the sandy soils than on the
hard-land soils. This favorable characteristic of the sandy soils, to
revegetate more easily and rapidly than the hard-land soils, con-
stantly prevails in the lower precipitation zones and holds true over
the entire area during years when precipitation is average or below.
Hard-land soils are less subject to wind erosion than sandy
soils after early spring cultivation and seeding. However, like the
sandy soils they are readily damaged by soil blowing if they are
low in organic matter or if there is not sufficient cover of vegeta-
tion or its residue to protect the soil during late winter and early
spring, the critical period when wind erosion is most likely to occur.
Their susceptibility to wind erosion is progressively higher in the
lower precipitation zones, because crop failures are more frequent
and vegetative protection and organic matter content become more
difficult to maintain. Large areas of hard-land soils as well as sandy
soils in southeastern Colorado were subjected to serious blowing
during the severe drought continuous from 1931 to 1940.
Serious damage to homesteads and fences (fig. 5) was caused
by soil deposition. Soil blowing also had harmful effects on people
and livestock in the area. Extensive damage occurred to crops,


Figure 3.-Eastern end of the Black Forest, El Paso County.































Figure 4.-Accumnulations caused by wind ire detrimental to cultivated
fields, pastures, tland fences. "Brown sandy soils of the nearly level uplands,"
Kit Carson County. Courtesy Soil Conservation Service.


native pastures, roads, railroads, farm machinery, and other prop-
erty. Dust storms during the drought period from 1931 to 1940
caused many areas in southeastern Colorado to be uninhabitable.
Abandoned homesteads stood and some still remain (1944) as pa-
thetic reminders of wasted human energy and resources.
Wind erosion becomes a hazard on nearly all cultivated areas
of eastern Colorado soils in direct proportion to the percentage of

Figure 5.-Typical dust storm il Baca County during the severe drought
that was continuous from 1931 to 1940. Picture taken November 17, 1938.
Courtesy Soil Conservation Service.


04







8 COLORADO AGRICULTURAL EXPERIMENT STATION


years when crops do not make sufficient vegetative growth to pro-
tect the soil. The danger is, therefore, much greater in the lower
precipitation zones. A very unstable condition occurs on many
tracts in these less favorable rainfall areas. As a result of wind
action, entire fields may be made unfit for cultivation, either be-
cause of soil movement within or from the fields, or because of
deposition from an adjacent unprotected area. These severely erod-
ed fields are a menace to adjoining lands. Crops and grass are often
cut off by moving soil or covered over and destroyed. Wind is re-
sponsible for the greater part of the erosion damage on lands of
less than 3-percent slope, while on the more sloping areas both
wind and water erosion may be active.
Water erosion in eastern Colorado occurs most frequently on
the sloping hard lands (fig. 6). Sloping areas of loose shallow sur-
face soils overlying dense subsoils with slow permeability are espe-
cially susceptible to water erosion.. The soils which are highly erod-
ible generally have thin surface layers and the removal of only a
few inches of soil may expose raw parent material. This loss of
surface soil is of more significance on the shallow soils of the hilly
lands than on the deeper soils. Water erosion on slopes of less
than 3 percent may be difficult to detect by examination of the soil
profile, but does occur as is evidenced by the presence of sheet and
rill washing and consequent alluvial deposits on the lower areas in
cultivated fields (fig. 7) and in adjacent roadside ditches. Gully
erosion is in evidence and occurs both on the sloping hard lands and
on sandy lands where definite drainage systems exist.
Under nearly all conditions sandy soils are less susceptible to
water erosion than are silty soils. The sandy surface is generally
more open and porous, thus permitting more rapid infiltration and
allowing a greater proportion of the water to enter the soil. Con-
sequently, surface runoff is reduced and soil removal is less than
on the silty soils. Evidence that the surface runoff is less on sandy
soils is the fact that in many of the sandy areas in eastern Colo-
rado the drainage patterns are weak and indefinite, while on the
adjacent hard-land areas the drainage systems are distinct and
well developed.
Some sandy soils, when low in organic matter, have a tendency
to seal over after a beating rain, causing runoff and erosion. This
condition is especially pronounced in the Black Forest area where
the soils are developed from arkosic materials. Soils with a sandy
surface overlying silty subsoils will erode freely when the surface
is saturated, particularly when the intensity of the rainfall is of tor-
rential proportions. Gully erosion on sandy soils may be severe
where a definite drainage system does occur and causes concentra-
tion of a head of water sufficient in size to move the saturated soil.


Bulletin 486










































Figure 6.-Sheet and gully erosion from an uncontoured field following a
rain storm. Seeds or seedlings are washed out on the slopes and covered by
soil in the lower areas. "Brown silty soils of the rolling uplands." Washington
County.



Figure 7.-Water erosion on the "dark silty soils of the nearly level up-
lands," Yuma County. Eight inches of soil were deposited at the foot of a
2-percent slope in one rain storm.


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10 COLORADO AGRICULTURAL EXPERIMENT STATION


The change in the fertility of soil which accompanies erosion
is difficult to evaluate in eastern Colorado because no quantitative
field tests have been made. Many of the cultivated areas that are
highly susceptible to erosion have suffered severe damage. Low
or unsatisfactory yields are the result, particularly in places where
unproductive subsoils, zones of high concentration of carbonates,
or areas with low organic matter content have been exposed by
removal of the surface soil. Where proper soil and moisture con-
servation practices are not in use, these severely eroded areas will
continue to increase in number, grow in size, and become an ever-
increasing menace.
Observation over a period of several years indicates that most
of the non-irrigated soils in eastern Colorado, except the extremely
sandy areas, have sufficient available plant nutrients to produce
as large a yield as is possible with the limited precipitation, thus
emphasizing the need for making best use of the precipitation
through water conservation practices.
The effects of erosion, however, are not confined to its influence
on the supply of available plant nutrients. Native plant food in
the soil is a valuable resource. It becomes immediately useful to
mankind only when transformed into agricultural products. The
environmental conditions and hazards which accompany active wind
erosion prevent full utilization of this potential capacity to produce.
Some of the most important reasons why uncontrolled wind ero-
sion greatly reduces the stability of the soil and lessens the oppor-
tunity to take full advantage of the production capacity of the land
in eastern Colorado are: (1) Erosion tends to accelerate erosion
because drifting soil gradually becomes more sandy in texture and
consequently more subject to wind action. (2) Stable soil aggre-
gates are destroyed and conditions become less and less favorable
for the natural formation of erosion-resistant aggregates. (3) Soil
lower in organic matter and consequently more susceptible to wind
erosion is exposed. (4) Crop stands become more and more diffi-
cult to establish, and replanting is necessary where the young seed-
lings are covered and killed by shifting soil during early spring.
(5) The unstabilized fields require extra control operations and
may not be in readiness for the operator to take full advantage of
the production capacity of the land when precipitation is favorable.
(6) The use of heavier machinery becomes necessary for the more
complex and intensive operations required to control wind erosion.
(7) The cost of production is increased.

LAND TYPE MAP
A generalized map showing the distribution of land types in
eastern Colorado is enclosed in the back of this bulletin. A small


Bulletin 486








LAND TYPES IN EASTERN COLORADO


sketch at the upper right hand corner of the land type map shows,
by shading, areas where semi-detailed and reconnaissance soil sur-
vey data were available for preparation of the map. Generalized
land class and soil maps were used as a basis for showing land
types where there is no shading. The map may be used as a basis
for general land planning over rather large areas (not less than
four townships), but will not serve as a detailed land resource in-
ventory for any portion of the State included in the area.

LAND TYPES
Soil types of eastern Colorado have been grouped into ten
land types. Each land type within itself represents a product of
soil characteristics, slope, and effective precipitation that have given
rise to areas similar in productivity and in general land use.
A few primary principles concerning precipitation-soil-crop re-
lationships must be kept in mind if one is to understand the reasons
for crop yield variations and the grouping of soils within this region.
First, the amount of yearly precipitation in various parts of eastern
Colorado varies from considerably less to slightly more than that nec-
essary to produce satisfactory crop yields. Second, most of the non-
irrigated soils contain enough available plant nutrients to produce
a higher yield of any adapted crop than is possible under the lim-
ited precipitation. The crop-producing power of nearly any arable
soil in the high plains is dependent on the amount of water it can
absorb and retain for the use of plants. It is, therefore, important to
catch and hold the rainfall on the land where it falls. All soils in
eastern Colorado, except sands and a few gravelly or stony areas,
are capable of holding all moisture they absorb close enough to the
surface to be reached by plant roots. Soils having silty surface
layers absorb water fairly rapidly, but they hold large amounts in
the upper few inches of soil where it can be lost by evaporation.
Sandy soils absorb water more rapidly, hold smaller amounts near
the ground surface, and thus lose less by evaporation than do silty
surface soils. Sandy soils, therefore, deliver more water to plants
than silty soils and, in general, produce higher crop yields where
precipitation is the limiting factor. The hard lands, however, serve
as a larger reservoir for holding stored rainfall during high precipi-
tation years.
A short description of the soil and slope characteristics and
soil-crop relationships of each land type follows.

Dark Silty Soils (Hard Lands) of the Nearly
Level Uplands and Terraces
This land type occupies most of the so-called "hard land" or
"wheat land" portion of the northeastern part of Colorado. (See


June 1944









12 COLORADO AGRICULTURAL EXPERIMENT STATION


map.)2 It is highly important to the dry-land wheat farmers of
the State, as it produces more wheat per unit area than any other
land type (fig. 8). More than 90 percent of the land shown as this
group on the map is nearly level." However, numerous rolling
areas, too small to be shown on a map of the scale used, are in-
cluded, as are the small basins that dot the uplands. These basin-
like depressions vary in depth from only a few feet to as much as
20 feet below the level of the surrounding land. Storm water col-
lects in the depressions to form intermittent lakes which persist
over varying but usually short periods.
SOIL CHARACTERISTICS.-Keith, Sherman, Dunlap, Goshen,
Rosebud, and Dawes loams, silt loams, and clay loams are included
in this group. These soils occur in a higher effective precipitation
zone than the adjacent brown soils of nearly level relief. This
environment has favored a more luxuriant grass vegetation under
virgin conditions. The accumulation of organic matter has, there-
fore, been greater, causing the surface soil of this group to be
darker in color than that of the adjacent brown soils. The first

-Land Type Terminology: Locally land types in eastern Colorado are given
such names as "hard land," "wheat land," "sandy land," and "row crop land."
In order to have terms consistent with each other, it has been necessary to
designate the land types according to texture of soils and their topography.
Relation of local terms and those textural terms used here follow: Silty soils
are hard lands, clay soils are gumbo or heavy lands, sandy soils are sandy
lands, and sand soils and sands include sandhills and the associated nearly
level to gently sloping sand soils.
sRelief Terminology: Nearly level areas are those having a slope of less
than 3 percent, gently rolling areas those having a slope of 3 to 7 percent,
rolling areas those having a slope of 5 to 12 percent, hilly to steep areas those
having a slope of more than 12 percent.

Figure 8.-Combining wheat on the "dark silty soils of the nearly level
uplands," Ynma County. Bumper wheat crops can be expected in from 1 to 3
years out of 10 over a large part of eastern Colorado.











w i(.::%'i~r~l


Bulletin 486








LAND TYPES IN EASTERN COLORADO


four named have mellow, dark grayish-brown surface soils 10 to
20 inches thick underlaid by brown silty subsoils 8 to 12 inches
thick that commonly become lighter colored with depth. They
contain an abundance of lime carbonate below depths of 20 to 30
inches. Goshen soils occupy swale positions and receive some
local runoff from adjoining soils. They are somewhat deeper than
the other soils of this group. The substrata of Keith, Sherman, and
Dunlap soils are limy, light-colored, silty materials. The Dawes
soils have thin (4 to 7 inches) grayish-brown surface soils under-
laid by dark grayish-brown columnar clay subsoils 8 to 12 inches
thick. The Rosebud and Dawes soils rest at shallower depths on
limy, light-colored, silty materials and soft sandstone.
LAND USE AND CROP YIELDS.-About 85 percent of this land
type is under cultivation. Wheat is the main crop with forage
sorghums and corn of less importance.
Crop yields vary widely from year to year and are remarkably
well correlated with the total precipitation for the 12-month period
ending when the crop is ready to harvest.'
TILLAGE PRACTICES AND EROSION CONTROL.-Farming practices
on these soils are much the same as on the wheat farming areas
throughout the High Plains. Wheat is planted in September, makes
a small growth in the fall, remains dormant through the winter,
resumes growth in the spring, and matures in July. Large type
machinery is used for most of the tillage, planting, and harvesting
operations. Alternating clean fallow with wheat is a common
practice. Continuous wheat cropping is often practiced on this
land type during cycles of favorable precipitation when the soil
is moist to a depth of 30 inches or more at seeding time. Forage
sorghums and corn are planted late in the spring, row-tilled until
midsummer, and harvested in the fall. Water erosion on these soils
is slight, except on the included sloping areas. However, there
may be considerable runoff and consequent loss of moisture from
fallow land even on slopes as low as 1 percent. Wind erosion may
become a hazard in years of relatively low precipitation.
To check wind erosion, farmers attempt to reduce wind veloci-
ties at the surface of the ground. This is accomplished by one or
more of the following practices: growing a crop, leaving a high
stubble, strip cropping, blank listing, and maintaining a cloddy con-
dition of the surface soil. The soils in this group retain a cloddy
surface much longer than the more sandy soils.

'Figures 21, 22, 23, and 24, pages 29, 30, 31, and 32, show the expected av-
erage yields and most probable yield distribution over an average 10-year
period of the main crops grown on this land type in comparison to those
obtained on other land types in eastern Colorado and in comparison to the
average "cost of production" yields. More detailed data on crop yield distribu-
tion are given under the discussion on "Crop Yields" on page 27.


June 1944








14 COLORADO. AGRICULTURAL EXPERIMENT STATION


A number of methods designed to increase yields on these
soils by retaining the precipitation where it falls are being prac-
ticed successfully by a number of farmers in eastern Colorado.
These methods include contour farming, the use of level broad
base terraces (fig. 9), and maintaining a trashy surface, generally
referred to as trashy tillage. Stubble mulching as a moisture con-
servation and erosion control practice is still under study in east-
ern Colorado. All these methods are designed to reduce surface
runoff. The stubble mulch also decreases evaporation losses.
Timely tillage and weed control to conserve moisture are valu-
able aids to increase production and may make the difference
between a crop and a failure.

Dark Sandy Soils (Sandy Lands) of the Nearly
Level Uplands and Terraces
The soils in this land type occupy most of the "corn land" in
northeastern Colorado. They are highly important to the dry-
land agriculture of the State even though they occupy a much
smaller total area than several other land types. This is because
their level of productivity for corn and adapted sorghums is the
highest of any major area of non-irrigated land in Colorado.
Most of the land shown as this type on the map is nearly level,
but many sandhill areas, too small to be shown on the map, are

Figure D.-Level broad base terrace on it 1~-percent slope. "Dark silty
soils of the nearly level uplands," Kit Carson County. Terraces like this, con-
structed without n channel above or below the terrace, can be farmed readily
with heavy machinery. Courtesy Soil Conservation Service.


Bulletin 486







LAND TYPES IN EASTERN COLORADO


included. Likewise, many small areas of dark sandy soils are
included in the "sandhill" land type on the map.
SOIL CHARACTERISTICS.-Haxtun sandy loams and loamy sands
are the major soil types in this group. They have dark grayish-
brown sandy surface soils 10 to 30 inches thick, and loamy to
sandy clay loam subsoils of lighter colors 8 to 16 inches thick. The
underlying material is limy and consists of any sandy or silty
mantle rock common to the region. In general, the physical char-
acteristics of these soils are nearly ideal for the maximum year
after year yields of dry-land crops, particularly corn. The sur-
face soils are high in plant nutrients and possess a rapid absorbing
rate for moisture but a rather low moisture holding capacity. Thus,
the surface soils pass a relatively large percentage of the precipita-
tion into the subsoil. The subsoils contain a higher percentage of
clay than the surface soils, so they are capable of holding large
amounts of water for plant use.
LAND USE AND CROP YIELDS.-Most of this land type is under
cultivation. Corn is the dominant crop, with sorghums and small
grains of minor importance.
Crop yields do not vary as widely from year to year as on
the dark silty soils, but vary with the total precipitation for the
12-month period ending when the crop ceases growing.
TILLAGE PRACTICES AND EROSION CONTROL.-Times of planting
and harvesting crops on this land type are about the same as on
the "dark silty soils," page 11. Tillage methods are, however, more
specifically designed to prevent wind erosion. Corn is planted in
deep furrows, the corn stubble is left standing through winter and
spring, and winter wheat, where grown, is seeded between corn
rows (fig. 10), harvested the following summer, and the stubble
listed in the fall crosswise to the prevailing wind. This procedure
provides a source of organic matter and helps to reduce wind ve-
locities at the surface of the ground so that shifting of the sandy
surface is held to a minimum.
Wind erosion, if not controlled on these soils, is a hazard to
young crops, but water erosion is seldom extensive enough for its
effects to be observed. Approved wind-erosion control practices
on this land type are drilling fall grain between rows of intertilled
crops, blank listing, and proper stubble management, which in-
cludes trashy tillage and leaving a high stubble. Such measures
as emergency tillage and emergency plantings become necessary
in some instances to control active wind erosion. A crop or crop
residue cover should be maintained as much of the time as pos-
sible. Keeping the topsoil well supplied with organic matter helps
to prevent wind erosion on this land type.


June 1944
































Figure 10.-Wheat seeded between corn rows on "dark sandy soils of the
nearly level uplands," Phillips County.

Brown Silty Soils (Hard Lands) of the Nearly
Level Uplands and Terraces
This is the most extensive land type in eastern Colorado. It
occupies large continuous areas in nearly all parts of Precipitation
Zones II and III. The agricultural utilization of these soils differs
markedly between the two zones, and the areas shown as this land
type on the map in reality represent two different groups of agri-
cultural lands shown in the same color but separated by the pre-
cipitation zone lines.
More than 90 percent of the land shown as this type on the
map is nearly level. However, numerous rolling areas, too small
to be shown on the map, are included, as are the small intermittent
lake basins.
SOIL CHARACTERISTICS.-Weld, Rago, Platner, Campo, Baca,
Nunn, Colby, and Fort Collins silt loams, clay loams, and loams are
the dominant soils in this group. The first six have grayish-brown
silt loam, clay loam, or loam surface soils, 3 to 8 inches thick,
underlaid by prismatic or columnar clay loam, 8 to 16 inches thick.
The substrata are dominantly limy loess and limy fine-grained
sandstones. The Fort Collins soils have brown, silty surface soils,
5 to 10 inches thick, underlaid by limy, light brown, silty material
extending to depths of 3 feet or more.








LAND TYPES IN EASTERN COLORADO


LAND USE AND CROP YIELDS.-In Precipitation Zone II, about
75 percent of this land type is or has been under cultivation. Wheat
and forage sorghums are the main crops, with corn grown to some
extent in the northern part of the zone, and grain sorghums be-
coming a major crop in the southern part.
In Precipitation Zone III, less than one-half the land area in
this type is under cultivation. Forage sorghum is the main crop
in the drier years, but the wheat acreage is high when soil mois-
ture conditions are favorable at seeding time. Corn is a minor
crop in the northern part, and grain sorghums are grown in the
southern part on this land type.
Crop yields vary widely from year to year and are remark-
ably correlated with the total precipitation for the 12-month period,
ending when the crop is ready for harvest.
TILLAGE PRACTICES AND EROSION CONTROL.-Farming practices
are essentially the same for these. soils as for the "dark silty soils
of the nearly level uplands and terraces," page 11. However, years
of low precipitation are more frequent on areas of the "brown
soils," and erosion hazards resulting from short crops or crop fail-
ures are more intense. Contour farming (fig. 11), strip cropping,

Figure 11.-Field of shocked sorghum planted on contour, "brown silty
soils of the nearly level uplands," Cheyenne County. High stubble was left
for soil protection against wind erosion.
Farming on the contour helps to hold moisture where it falls, giving it
ample time to penetrate ihe soil. The additional moisture held on the land
increases yields and helps to keep the soil in proper condition to resist blowing.


June 1944








18 COLORADO AGRICULTURAL EXPERIMENT STATION


broad base terracing, trashy tillage (fig. 12), rough cloddy tillage
(fig. 13), blank listing, proper stubble management, timely tillage,
and weed control are approved practices for erosion control and
moisture conservation on this land type. Emergency tillage and
emergency plantings are immediate measures used to prevent and
check active wind erosion on unstabilized areas.

Brown Silty Soils (Hard Lands) of the Rolling Uplands
These soils occur generally as long, rather narrow areas along
the larger streams in all four of the precipitation zones in eastern
Colorado. (See map.) The agricultural utilization of this land
differs from zone to zone and the areas shown as this land type
on the map in reality represent four different groups of agricul-
tural lands shown in the same color but separated by the precip-
itation zone lines.
Within this land type, the surface is rolling, but numerous
nearly level upland and long narrow stream valley areas, too small
to be shown on the scale used, are included.
SOIL CHARACTERISTICS.-Colby, Stoneham, Renohill, and Elbert
loams and silt loams are the dominant soils in this group. The first
three named have brown, commonly limy silt loam or loam surface
soils, 4 to 10 inches thick, and lighter colored, usually highly limy
subsoils, and substrata of any fine sandy or silty and clayey parent
materials common to the region. Elbert soils have brown or
grayish-brown non-calcareous surface soils, 4 to 8 inches thick, and

Figure 12.-Trashy tillage on the "brown silty soils of the nearly level
uplnnlld," Logan County. Courtesy Soil Conlservation Service.


AyftDp~


Bulletin 486






















Figure 13.-Rough eloddy tillage with crop residues left on the surface
prevents damage by wind erosion and helps to conserve moisture. "Brown
silty soils of the nearly level uplands." Lincoln County.

brown to dark brown clay loam to light clay subsoils, 14 to 20
inches thick. Lime occurs at from about 2 to 5 feet. The Colby
silt loam occupies over 85 percent of the land type. It is generally
a silt loam texture from the surface to depths of 3 feet or more.
LAND USE AND CROP YIELDS.-In Precipitation Zone I, about
one-third of this land is under cultivation; the remainder is utilized
as native pasture. The cultivated areas are used mainly for the
production of corn and forage sorghums.
In Zone II, about one-fifth of this land is under cultivation;
the remainder is utilized as a native pasture. The cultivated areas
are used mainly for the production of forage and grain sorghums.
In Zones III and IV, nearly all this land type is utilized as native
pasture.
Although these soils lose more water by surface runoff than
do silty soils of more nearly level land, they average a little higher in
fine sand content, absorb water more readily, and lose less mois-
ture by evaporation than do adjacent level silty soils. Vegetative
growth per plant is usually less, but plant survival is greater on
this land type than on the adjacent level silty soils. As a result,
the "brown silty soils of the rolling uplands" on slopes of less than
6 percent produce similar yields of most crops in years when pre-
cipitation is average or below average.
TILLAGE PRACTICES AND EROSION CONTROL.-Under cultivation,
soils of this land type are subject to considerable removal of sur-
face soils by water erosion. The "soil washing" often damages the
crop stand and may remove organic matter and available plant
nutrients to an extent sufficient to reduce crop yields.
Farming practices on these soils are similar to those used on
the adjacent level silty areas, as many cultivated fields consist o
both level and rolling silty soils. Contour tillage and terracing
are very effective for erosion control as well as for moisture con-








20 COLORADO AGRICULTURAL EXPERIMENT STATION


servation and increased production. Strip cropping, trashy tillage,
rough cloddy tillage, blank listing, timely tillage, conservation of
crop residue and stubble, and weed control are effective measures
for erosion control and moisture conservation on this land type.
Immediate measures used to prevent and check active wind erosion
are emergency tillage and emergency plantings. Contour furrows
(fig. 14) and water spreading are effective soil and moisture con-
servation practices on the range land.

Brown Sandy Soils (Sandy Lands) of the Nearly
Level to Gently Rolling Uplands and Terraces
The soils in this land type are highly important to the "dry-
land" production of field crops in Precipitation Zones II, III, and
IV, even though they occupy much smaller total area than the level
silty soils of those zones. (See map.) This is because their level
of productivity for corn and sorghums is much higher than that of
any other non-irrigated lands in the vicinities where they occur.
Most of the land shown as this type on the map is nearly level
to gently rolling, but many sandhill enclosures, too small to show
on a map of this scale, are included. Likewise, many small areas
of nearly level to gently rolling brown sandy soils are included
in the "sandhill" land type on the map.

Figure 14.-Snow held in contour furrows on range land, "brown silty
soils of the rolling uplands," Elbert County. Courtesy Soil Conservation
Service.








-I-






__ "-- -- -






-. -- -,-.
-. *P-a- ,- .


Bulletin 486



























Figure 15.--Grain sorghunms rarely fail on the sandy lands of eastern
Colorado. "Brown sandy soils of the nearly level to gently rolling uplands,"
Baca County.

SOIL CHARACTERISTICS.-Vona, Blakeland, Otero, Ascalon, Bres-
ser, and Greeley loamy sands and sandy loams are the main soils
included in this land type. They have brown sandy surface soils,
6 to 16 inches thick. Substrata are sandy, commonly limy, light
colored materials. Lime is at or near the, surface in the Otero,
below plow depth in the Vona and Greeley, and below 4 feet
in the Blakeland and Bresser soils. Ascalon and Bresser soils have
sandy clay loam subsoils and are generally referred to as mod-
erately sandy soils.
LAND USE AND CROP YIELDS.-In Precipitation Zone II, most
of this soil is under cultivation. Corn is the major crop in the
northern part and broomcorn, forage sorghums, and grain sorghums
(fig. 15) predominate in the southern part of the area."
In Precipitation Zone III, about two-thirds of this land type is
under cultivation; the remainder is utilized as native pasture. Corn
and forage sorghums are the main crops in the northern part, and
forage and grain sorghums predominate in the southern part of
the region.
In Precipitation Zone IV, less than one-fourth of these soils
are under cultivation; the remainder of the area is utilized as
native pasture. Forage and grain sorghums are the main crops as
a source oc supplemental feed. Because of the low rainfall and
wind erosion hazards, dry farming is not advisable in this zone.
"Broomcorn yields average from 200 to 250 pounds per acre. Other crop
yields are shown on Figures 21, 22, 23, and 24, pages 29, 30, 31, and 32.







22 COLORADO AGRICULTURAL EXPERIMENT STATION


TILLAGE PRACTICES AND EROSION CONTROL.-Farming practices,
type of erosion hazards, and methods of reducing these hazards are
essentially the same for this land type as for the "dark sandy soils
of the nearly level uplands," page 14. Strip cropping (fig. 16)
is more generally practiced on this land type than on the "dark
sandy soils." Contotr tillage is generally recommended as an ad-
ditional erosion control practice for this land type on slopes of
more than 3 percent. Terracing has given good results on the
moderately sandy soils in this group occurring on slopes of more
than 3 percent. Wind erosion on these soils becomes increasingly
severe in Precipitation Zones II, III, and IV, since the proportion
of years when a vegetative cover for the land is not produced be-
comes increasingly larger. Consequently, the need for such meas-
ures as timely tillage, emergency tillage, and emergency plantings
becomes more intense.

Light Brown Silty Soils (Hard Lands) of the Nearly
Level to Gently Rolling Uplands and Terraces
Soils of this group occur on nearly level to gently rolling silty
areas in Precipitation Zone IV. There are some areas of undulat-
ing silty soils and nearly level sandy soils, too small to be shown
on a map of the scale used, included with this light brown silty
land type.
SOIL CHARACTERISTICS.-Prowers, Tyrone, Minnequa, and
Rocky Ford silt loams and clay loams are the dominant soils in
this group. They all have light brown or light grayish-brown,
limy, silty surface soils '* to 5 inches thick. The subsoil and sub-
strata differ only slightly in visible characteristics from the surface

Figure 10.-Strip cropping with sorghum and beans. "Brown sandy soils
of the gently rolling uplands," Elbert County. The high sorghum stubble re-
duces soil blowing and catches drifting snow.


Bulletin 486







LAND TYPES IN EASTERN COLORADO


soils, being only slightly lighter colored and commonly slightly
more clayey in texture.
LAND USE AND CROP YIELDS.-Only a few fields are used to
produce cultivated crops on this land type, except where the soils
are irrigated. Dry-land crops have only a small chance of pro-
ducing a profitable crop yield."
TILLAGE PRACTICES AND EROSION CONTROL.-The soils in this
land type are highly erodible but generally are protected by native
grass. This grass cover should be maintained and protected by
controlled grazing and proper range management. Contour fur-
rowing, pasture corrugation, and water spreading are practiced for
moisture conservation on range land.

Clay Soils (Gumbo or Heavy Lands) of the Nearly Level
to Gently Rolling Uplands and Terraces
This land type is most extensive in the south central part of
eastern Colorado. On the map it includes numerous level to rolling
areas of silty or sandy soils that are too small to segregate on a
map of the scale used. In general, the land type is nearly level.
However, part of the land has slopes of 3 to 7 percent.
SOIL CHARACTERISTICS.-Pierre, Ordway, Orman, and Billings
clays are the most extensive soils in this group. They have light
to heavy clay, commonly limy, light brown to dark brown topsoils
3 to 10 inches thick. Under the surface soil is massive clay or clay
shales extending to depths of more than 3 feet. Layers of gypsum
or other alkali salts are common throughout these soils.
In general, the texture profiles of these soils are the least
adapted for crop production of any land type in eastern Colorado.
The surface soils are so high in clay that they are only slowly per-
meable to water; therefore, a large proportion of all torrential rain
is lost by surface runoff. They also hold large amounts of water
near the surface, where it is lost by evaporation. The amount of
available water remaining for plants is obviously quite small.
LAND USE AND CROP YIELDS.-Most of this land type is utilized
as native pasture. Some areas are under irrigation, and a few at-
tempts have been made to "dry farm" some of these soils with un-
satisfactory results. Crop yields are considerably lower than for
adjacent areas of silty soils on nearly level land.
TILLAGE PRACTICES AND EROSION CONTROL.-The soils in this
type, even when protected by native grass cover, are subject to
serious damage by gullying (fig. 17). Contour furrowing, pasture
corrugation, and water spreading, to reduce the velocity of runoff
'Figures 21, 22, 23, and 24, pages 29, 30, 31, and 32, compare expected av-
erage yields from these soils with those of other land types.


June 1944

























Figure 17.-Severe gully erosion on the "clay soils of the nearly level to
gently rolling uplands and terraces," Elbert County. Such destruction of the
terraces and sales by gully erosion greatly reduces the carrying capacity of
this land type. Courtesy Soil Conservation Service.

water and prevent water accumulation in channels or small gullies,
appear to greatly retard the gullying of these pasture areas. Proper
stocking is very important not only for erosion control but for
increasing production of pasture grasses.

Undifferentiated Shallow Soils (Hilly Land) of the
Rolling to Steep Uplands
This land type occupies many large and small areas through-
out eastern Colorado. Unfortunately, numerous areas of this type
are too small to show on a map of the scale used so were included
in other land types. In general, these soils and parent materials
are on slopes greater than 12 percent.
SOIL CHARACTERISTICS.-Canyon and Apache stony loams, Col-
by silt loams, steep phase, Travesilla stony sandy loam, Larimer
gravelly loam, Lismas clay, and exposures of the parent materials
of these soils occupy most of the areas shown on the map as be-
.longing to this land type. Except in coves or at the foot of slopes,
the surface soils are less than 6 inches thick and rest directly on
parent material of limy silty loess, soft limy sandstone, hard lime-
free sandstone, gravel, or shale.
LAND USE AND CROP YIELDs.-Practically all areas of these soils
are utilized as native pasture. Their maximum grass production
varies, depending on annual precipitation, soil characteristics, steep-
ness of slope, and proportion of area occupied by bare spots and
narrow alluvial valleys.







LAND TYPES IN EASTERN COLORADO


TILLAGE PRACTICES AND EROSION CONTROL.-On slopes as steep
as 12 percent or more, good range management practices have been
more successful in increasing the production of pasture grasses and
controlling soil erosion than have mechanical methods.

Undifferentiated Soils (Sandy Land and Hard Lands) of the
Rolling to Steep Mountain-Plains Transition
This land type occupies a rather extensive area along the
mountain front or west side of eastern Colorado. It is character-
ized by an intricate association of soils on a variety of slopes (fig.
18) from many widely different parent materials. However, most
of the land surface has a slope of greater than 12 percent. Numer-
ous small nearly level upland areas and narrow alluvial lands are
included in this land type on the map.
SOIL CHARACTERISTICS.-Falcon, Kettle, Peyton, Pring, and
Breece sandy loams, Table Mountain loam, Rampart, Travisilla,
and Amherst stony loams, and exposures of the parent materials
of these soils occupy most of the land area designated as this group
on the map. They have dark to light colored, sandy to heavy tex-
tured, usually non-limy surface soils 4 to 10 inches thick. Under
the surface soil is sand and gravel, loam, or some bedrock common
to the region. This group includes such a mixture of soils that a
general description would not give any definite information.
LAND USE AND CROP YIELDS.-Although most of this land type
is utilized as native pasture, small areas are cultivated and produce
variable yields of small grains, corn, beans, and potatoes. Part of
this area, known as the Black Forest, has only a limited utilization

Figure 18.-Mountain-plains transition, Douglas County.








4r.
:- -



nartq ';- .4 f. "


June 1944








26 COLORADO AGRICULTURAL EXPERIMENT STATION


as pasture and a source of small timber because of the high erod-
ibility and shallowness of the soils.
TILLAGE PRACTICES AND EROSION CoNTROL.-Tillage practices
on the cultivated areas are similar to those on other land types,
except that most of the farm machinery is smaller. Some cultiva-
tion is practiced on slopes over 8 percent. On these areas water
erosion is quite extensive. Gully erosion is especially severe. Con-
tour cultivation (fig. 19) and terracing have been practiced on
some fields with favorable results. Contour furrowing and water
spreading on pasture areas have reduced the flood hazards from
Monument and Cherry Creeks.

Sand Soils and Sands (Sandhills) of the
Dunelike or Hummocky Uplands
The sandhills of eastern Colorado occupy a large total area,
but are divided into a large number of small and large areas scat-
tered throughout most of the region. In general, the land surface
is characterized by a succession of irregularly distributed, sharply
rolling hillocks and ridges, most of which rise 10 feet or more above
intervening wind-formed valleys, pockets, and swales. Surface
drainageways are usually absent, because the sands rapidly absorb
the precipitation.
Sandhill swales large enough to furnish cultivable areas but
too small to segregate on a map of the scale used are included in
this land type.

Figure 19.-Contour strip cropping on terrace and alluvial slope soils
associated with "the mountain-plains transition land type," Douglas County.
Picture shows fence, wheat, corn, and alfalfa on the contour. Courtesy Soil
Conservation Service.


Bulletin 486







LAND TYPES IN EASTERN COLORADO


SOIL CHARACTERISTICS.-Dune sand (stabilized) and Valentine
and Dwyer sands and loamy sands occupy most of the sandhill area
in eastern Colorado. They are light brown sands or loamy sands
commonly darkened in the upper 4 to 8 inches by organic matter
staining, and containing some free lime at varying depths. They
are completely dominated by sands to depths of more than 4 feet.
LAND USE AND CROP YIELDs.-Nearly all this land type is util-
ized as native pasture. Grazing control and careful range manage-
ment serve to keep the carrying capacity at a maximum level and
prevent wind action from destroying the grasses.

Irrigated and Alluvial Land
In eastern Colorado the addition of irrigation water to many of
the soils greatly increases their productive capacities and reduces
the importance of effective precipitation. The increased produc-
tion intensifies problems of soil fertility maintenance.
Since soil problems on irrigated land in eastern Colorado differ
markedly from those on dry-land areas, irrigated land is segre-
gated as a specific land type on the map, but its highly complex
productivity and problems cannot be logically discussed on the
basis of a general land type map.
Most alluvial lands or soils occurring on stream flood plains
in eastern Colorado in areas large enough to show on the land type
map are partially or fully under irrigation or receive supplemental
water as runoff from higher levels. It appears logical, therefore,
to include these soils with the irrigated land on a map of the scale
used.
CROP YIELDS
Productivity ratings have been made for most of the soil types
of our more extensive agricultural regions during the past several
years. The methods used to express these ratings have varied
considerably, but the objective of "evaluating the soil in terms of
expected crop yields under the climate that generally prevails" has
at all times been kept in mind. In eastern Colorado, crop yields
are primarily limited by the amount of water available to the plants.
Since there is a wide range in precipitation from year to year, and
some seasons are too dry to produce certain crops, the distribution
of high, moderate, and low or failure crop yields becomes fully as
important as the average yield. Yields discussed are on a planted
acreage basis and may be considered as the best estimates possible
with the data available. They are based on good farming practices
and in general are somewhat higher than "county average" yields on
harvested acreages as given in Colorado Agricultural Statistics. In
some instances they are lower than those obtained by the most
successful farmers.


June 1944








28 COLORADO AGRICULTURAL EXPERIMENT STATION


Records of the "Dry Land Stations" at Akron, Colo., Colby
and Garden City, Kans., and Dalhart, Tex., based on planted acre-
ages, show that high yields of all major crops are obtained in years
when the total precipitation for the 12-month period ending when
the crop matures is more than 20 inches. Moderate crop yields
result when precipitation for a similar period is from 17 to 20 inches.
Lower yields result from precipitation of 14 to 17 inches.' Corn and
wheat fail, or nearly fail, on less than 14 inches of precipitation, but
sorghums usually produce profitable yields (fig. 20) even with this
small amount of precipitation.
Figures 21, 22, 23, and 24 show the most probable yield dis-
tribution, average yields, and the average "cost of production" levels
for corn, wheat, grain sorghum, and forage sorghum, the four
major crops grown in the dry-land portions of eastern Colorado."
These yields are shown only for those land types where information
available allowed a fairly satisfactory estimate of average yields.
Failure years were considered in determining the average yields.
The average "cost of production" in terms of crop yields is indicated
7A basis for rating the productivity of soils on the plains of eastern Colo-
rado. Colo. Exp. Sta. Tech. Bul. 25. 1938.
8See pages 39 to 43 for items involved and rates used.

Figure 20.-Dual purpose sorghum varieties are grown successfully on
both the hard lands and sundy lands over a large part of eastern Colorado.
Crop failures rarely occur. Courtesy Soil Conservation Service.


Bulletin 486










PRECIPITATION ZONEI PRECIPITATION ZONE r
III II


IARK SILTY 8OILS
OF THE NEARLY
LEVEL UPLANDS AND
TERRACES


DARK SANDY SOILS
OF THE NEARLY
LEVEL UPLANDS AND
TERRACES


BROWN SILTY SOILS BROWN SILTY SOILS
OF THE ROLLING OF THE NEARLY
UPLANDS LEVEL UPLANDS ANO
TERRACES


1111111111111 111111111111 1 111111111111 1 n IhIhIII II 1111111111. 1111111111 II
BROWN SANDY SOILS BROWN SILTY SOILS BROWN SILTY SOILS BROWN SANDY SOILS LIGHT BROWN SILTY BRuWN SANDY SOILS
OF THE NEARLY OF THE ROLLING OF THE NEARLY OF THE NEARLY SOILS OF THE NEARLY OF THE NEARLY
LEVEL TO GENTLY UPLANDS LEVEL UPLANDS AND LEVEL TO GENTLY LEVEL TO GENTLY LEVEL TO GENTLY
ROLLING UPLANDS TERRACES ROLLING UPLANDS I ROLLING UPLANDS ROLLING UPLANDS
AND TERRACES AND TERRACES AND TERRACES AND TERRACES


Figure 21.-Corn-average yield and most probable yield distribution over an average 10-year period on six land types in eastern
Colorado. Sandy soils have a much more favorable distribution of corn yields than do silty soils in the same precipitation zone.
Height (or length) of the black bars represent yields, while the number and thickness of the bars represent proportion of years.
For example, In Precipitation Zone I for each land type, two and one-half bars, representing 2 and one-half years in an average 10-
year period, are longer than the others, three bars representing 3 years are shorter, but all are above the average "cost of production"
yield, while four and one-half bars are below. Two bars are very short, representing quite low or failure years.









PRECIPITATION ZONE PRECIPITATION ZONE --, PRECIPITATION-, PRECIPITATION
y ZONEM I ZONEI M































S ARK SILTY SOILS DARK SANDY SOILS N 0. Y SILTY SOILS i .O ILTY SOILS SROWN SILTY SOILS SROWS SILTY SOILS LIGHT RO SILTY
I OF THE NEARLY OF THE NEARLY OF THE ROLLING OF THE NEARLY OF THE ROLLING OF THE NEARLY SOILS OF THE NEARLY
LEVEL UPLANDS AND LEVEL UPLANDS AND UPLANDS LEVEL UPLANDS AND UPLANDS LEVEL UPLANDS AND LEVEL TO GENTLY
TERRACES TERRACES TERRACES TERRACES ROLLING UPLANDS
AND TERRACES

Figure 22.-Wheat-average yield and most probable yield distribution over an average 10-year period on five land types in
eastern Colorado. Below "cost of production" yields must be paid for by the higher yields.
Wheat yields on allowed land: Summer fallow of land in preparation for the growing of wheat has been tested at the U. S. Dry
Land Field Station at Akron, Colo., for many years. The following conclusions can be drawn from these tests:
(1) Winter wheat yields on fallow are about twice those obtained by continuous cropping where the land is clean allowed and
operations are timely.
(2) Total wheat from a given area can be expected to be greater from continuous cropping during a series of years of favorable
precipitation and less during unfavorable years.
(3) Wheat failures are from two to three times as frequent on continuously cropped land as on fallow.











/- PRECIPITATION ZONE I






III


OA IT S OILTY Sl AR ANDY SOIL
O F THE NEARLY Of THE NEARLY
LEVEL UPLANDS AND LEVEL UPLANDS AND
TERRACES TERRACES


ZONE 3C PRECIPITATION ZONE X1






.. I .


BROWN SILTY SOILS I BROWN SILT SIS BROWN SANDY SOILS
OF THO ROLLING OF TTH NEARLY OF THE NEARLY
UPLANDS LEVEL UPLANDSAND LEVEL TO GENTL
TERRACES ROLLING UPLANDS
AND TERRACES


Figure 23.-Grain sorghum-average yield and most probable yield distribution over an average 10-year period on six land types
in eastern Colorado.




















- PRECIPITATION ZONE I PRECIPITATION ZONE_ PRECIPITATION ZONE













II III .II II I II


ROWN SILTY SOLS BROWN SILTY SOILS
OF THE ROLLING OF THE NEARLY
UPLANDS LEVEL UPLANDS AND
TERRACES


BROWN SILTY SOILS I BROWN SILTY SOILS
OF THE ROLLING F THE NEARLY
UPLANoS LEVEL UPLANDS ANO
TEIRttCES


BROWN SILTY SOILS LIGHT BROWN SILTY
OF THE ROLLING SOILS OF THE NEARLY
UPLANOS LEVEL TO GENTLY
ROLLING UPLANDS
AND TERRACES


Figure 24.-Forage sorghum-average yield and most probable yield distribution over an average 10-year period on six land types

in eastern Colorado.


DARK SILTY SOILS
OF THE NEARLY
LEVEL UPLANDS AND
TERRACES


BROWN SANOY SOILS
OF THE NEARLY
LEVEL TO OENTLY
ROLLING UPLANDS
AND TERRACES


DARK SANDY S OILS~
OF THE NEARLYI
LEVEL U LANII II
TERRACESEL


GROWN SANDY SOILS
.P THE E.R.L
LEVEL TO GENTLY
ROLLINGG UPLANDS
AN. FAA ACE.I


BROWN ANDY SOIlLS
OF THE NEARLY
LEVEL TO GENTLY
ROLLING UPLANDS
AND TERRACESS








LAND TYPES IN EASTERN COLORADO


on each figure by the horizontal dotted line. Figures 25, 26, 27,
and 28 illustrate the relationship between these "cost of produc-
tion" yields and the average yields which may be expected (based
upon past records) on the various land types in the different pre-
cipitation zones. The reader should bear in mind that this "cost of
production" yield will vary from farm to farm and from year to
year. It will not remain in the fixed position shown on these graphs,
but will rise or fall with changing conditions.

Basis for Crop Yields and Yield Distribution
Yield estimates foi eastern Colorado are based on the crop
yield-precipitation relationship, shown by crop yield and precipita-
tion records over a 30-year period at four dry-land stations located
in and near eastern Colorado. These were then extended over
eastern Colorado by studies of soil moisture relationships, by pre-
cipitation records of the U. S. Weather Bureau, and by relative
yield estimates of farmers and agricultural technicians of the area.
Frequency of crop failure or marked reduction in yields caused
by natural hazards other than limited or ill distributed precipitation
is quite variable over eastern Colorado. Hail, which generally is
associated with wet years, insect pests, and diseases are the most
common of these natural hazards. Although no quantitative data
are available concerning these hazards, it is reasonable to assume
they will reduce the yields of some crops more than of others. Wheat
yields may be cut by hail from a bumper crop prospect to crop
failure. Comparable damage to corn or grain sorghum by hail storms
is much less frequent. Loss of a forage sorghum crop by hail is rela-
tively infrequent, and heavy hail storms may reduce these yields
only slightly.
The 1943 State hail insurance rate for wheat was 10 percent
(8 percent in Range 67 and 7 percent in Range 68) for the following
counties within the area covered by the land type map: Baca, Bent,
Elbert, El Paso, Kit Carson, Las Animas; Lincoln, Logan, Morgan,
Otero, Phillips, Prowers, Pueblo, Sedgwick, Washington, Weld, and
Yuma Counties; 9 percent (8 percent in Range 67 and 7 percent in
Range 68) for Adams, Arapahoe, Cheyenne, Crowley, Douglas, and
Kiowa Counties; 7 percent for Huerfano County; and 5 percent for
Boulder, Larimer, and Jefferson Counties.

Interpretation of Yield Graphs
In the interpretation of the graphs showing distribution and av-
erage yields (figs. 21, 22, 23, and 24), it is necessary to point out
that crop adaptation differs from the northern to the southern part
of eastern Colorado. In general, the northern half of the area,
which has a mean annual temperature below 500, has a markedly
lower "growing season" evaporation rate than the southern half of


June 1944



















-PRECIPITATION ZONEI T PRECIPITATION ZONE I


OARP SANDY SOILS
OF THE NEARLY
LEVEL UPLANDS AND
TERRACES


iERAGE 'COST OF

























BROWN SiLTY SOILS
OF THE NEARLY
LEVEL UPLANDS AND
TERRACES


ODUCTION" YIELD

























BROWN 5ILTY SOILS
OF THE NEARLY
LEVEL UPLANDS AND
TERRACES


gROWN SANDY SOILS
OF THE NEARLY
LEVEL TO GENTLY
ROLLING UPLANDS
AND TERRACES


0 BU - -

























LIGHT BROWN SILTY
SOILS OF THE NEARLY
LEVEL TO GENTLY
ROLLING UPLANDS
ANDO TERRACES


.-VI0N S-1T SOILS
OF T E ROLLING
UPLANDS)


Figure 23.-Corn-relationship between average yields on six land type for an average 10-year period and average "cost of

production" yield for the 3-year period, 1937 to 1939, prior to World War II.

The dark mandy soils in Precipitation Zone I Is the only land type that produces corn yields well above the "cost of production"

yield.


ZONE 31 T PRECIPITATION ZONEIX---


MIRNSA SSOL.OIL
OF THE NEARLYI
LEVEL TO GENTLY
ROLLING UPLANDS(
AND TERRACE$I


BROWN SANDY BOILS
OF THE NEARLY
LEVEL TO GENTLY
ROLLING UPLANDS
AND TERRACES


OA;KT SI LT Y SOILS
0 HE PEARLI
LEVEL UPLAN 05 AN
TERRAICE$


EP-Nn SLTY Ii-S
OF TH ROLLING
JPLA...


JEACI'tjMA .. U.















PRECIPITATION ZONEI


DARK SILTY SOILS
OF THE NEARLY
LEVEL UPLANDS AND
TERRACES


DARK SANDY SOILS
OF THE NEARLY
LEVEL UPLANDS AND
TERRACES


- PRECIPITATION ZONE PRECIPITATION ZONE I PRECIPITATION ZONE )







EACH EQUALS 2 BU.


-OF- -P--PROD
















BROWN SILTY SOILS
OF THE NEARLY
LEVEL UPLANDS AND
TERRACES


TION'- -YIELD-
















SROWN SILTY SOILS
OF THE ROLLING
UPLANDS


BROWN SILTY SOILS
OF THE NEARLY
LEVEL UPLANDS AND
TERRACES


BROWN SILTY SOILS
OF THE ROLLING
UPLANUDS


Figure 26.-W heat-relationship between average yields on five land types for 11 average 10-year period and

production" yield for the 3-year period. 1937 to 1939. prior to World War II.
Average wheat yields are well above "cost of production" yield in Precipitation Zones I and II.


average "cost of


LIGHT BROWN SILTY
SOILS OF THE NEARLY
LEVEL TO GENTLY
ROLLING UPLANDS
AND TERRACES


rA







PRECIPITATION ZONEI PRECIPITATION ZONE --- ---PRECIPITATION ZONE m -- PRECIPITATION ZONE ISE


1.N ADYSS1




Of THE NEARLYI
LEVEL UPLANDS A I*
TERRACE'~


410~








-Mb-











SA NDY 111 I~LI
OF TI E __l
LEVEL 11 IE"T1
ROLL I N U PLANS
AID TEIRACES~


EACH E EQUALS 2


94-a- W

M ftI11OOL
Aft, 1 -r)L
qwI PL*I*
4wllE


QW,~d















UPLANDS


Figure 27.-Grain sorghum-relationship between average yields on six land types for an average 10-year period and average
"cost of production" yield for the 3-year period, 1937 to 1939, prior to World War II.
Yields that fall far short of paying cost of production are rare. Thus, sorghums furnish the most dependable grain crop for this
region.


-














RoEwN siTy So LH
LEVEL UPLANDS AND
erR Acs


WIVW~ij











0_6~







.1 THE EA 11I
LEVEL TO IENTLI
RIOLL'.4G UPLANDS
AND Te --CE


I T~ I BU lLT








L""RT e.ow. siLTy
SOls O. THE NEA.L~
LEVEL TO GENTLY
ROLLING UPLANos
ANO TE RaCES


OF THE NEARLY
LEVEL TO GUPTLY
ROLLING UPLANDS
AND TERRACES


a -











a~owk stLry so as
_ERODUCTIQI' YIELD















NO-N S5LT SOIL.
OF THE ` -L"n
UPLANDS


Nww.S~





-1 Vorl~









LEV*E EL ULADSAI
TERIIRIES


.F THE ROOLL_*
UPLANDS




















---- PRECIPITATION ZONEI .- PRECIPITATION


DARK S*NDY sOILS anowN SILTY SOILS
O0 TNE ENRLY Or T.E ROLLING
LEVEL PLANS AIND UPLANOS
TERRACES


EACH -t E 4TOM


Figure 28.-Forage sorghum-relationship between average yields on six land types for an average 10-year period and average

"cost of production" yield for the 3-year period, 1937 to 1939, prior to World War II.

Year in and year out the dry lands of eastern Colorado will come nearer paying cost of production for this crop than for any other.


ZONE M- PRECIPITATION ZONE 3SE


LEVEL IP=A. D11 L.R.ElTO E.111 Y~ltD
TE ... DEI L*OPL*O
I.. TE..ICE


LEVEL UPLINDS IND LEVEL TO GENTLI
TERRAIES "OLLI"O UL...
IND TENN.-CL


rarI IILTI I*IL1
11 T 11 N_ Ll
LEVEL L AND*J *
__E.ICT


LIGII I "IN -T'T
I._ DO THE NE-u
LEVEL TO I~`TL
ROLLIIG UPLAIDS
... TE.-EIL


TN TE "' L..*
JIL-IO








38 COLORADO AGRICULTURAL EXPERIMENT STATION


the area, which has a mean annual temperature above 500. Corn is
not well adapted to the southern portion of the area, so is not a
major crop in southeastern Colorado. Grain sorghums produce
good yields in the southern portion of the area, so replace corn as
a livestock feed. All soils in the northern part of the area tend to
produce slightly higher crop yields than are shown in figures 21, 22,
23, and 24, and those in the southern part slightly lower yields.
With these facts in mind, information contained in the produc-
tivity graphs may be interpreted as follows:
1. Silty soils of nearly level areas in Precipitation Zones I,
II, and III will produce high yields or bumper crops about 3 years
out of every 10.
2. In years of high precipitation sandy soils tend to produce
lower yields of all crops than do silty soils. In years of low pre-
cipitation crop yields are not so low on the sandy soils as on the
silty soils. Bumper crop years are not as likely on sandy soils as
on silty soils, and unsound expansion of farming operations is not
as much of an inducement. Crop failures, however, are less fre-
quent on the sandy soils. All these conditions encourage more
stable farming on sandy soils.
3. A comparison shows that sorghum yield variations are not
so great as those for wheat and corn and that the average yields
of these crops are not so high as those of grain sorghums. This
may lead to a still greater replacement of corn acreage by sorghums
and perhaps a replacement of some wheat acreage by this more
dependable crop.

Grouping Average Crop Yields
Average crop yields for corn, wheat, grain sorghum, and for-
age sorghum in eastern Colorado may be divided into four groups
as a simplified basis for assigning a productivity index to soil and
land types.
These groups or productivity ratings may be compared as
follows:
(1) Highest dry-land yield in eastern Colorado. Lands and soils
rated at this level should be utilized for these crops insofar
as it is possible to do so.
(2) Good for eastern Colorado. The range in average crop yields
expected is above the range in "cost of production" yields.
(3) Average yields expected are within the same range as "cost
of production" yields. It is questionable whether this land
should be used for the crop that yields in this range. Need
for livestock feed and ability of the farmer to reduce cost of
production may determine its utilization.


Bulletin 486








LAND TYPES IN EASTERN COLORADO


(4) Yields are so low that the crop cannot be expected to produce
an average yield that will pay the cost of production.
The range in expected average yields of corn, wheat, grain
sorghum, and forage sorghum in eastern Colorado within each
productivity index is shown in table 1.

TABLE 1.-Range in expected average yields represented by pro-
ductivity indices in eastern Colorado.
Productivity Crops
index Corn Wheat Grain sorghum Forage sorghum
Bushels Bushels Bushels Tons
1 15 to 19 11 to 14 15 to 20 1/4 to 214
2 11 to 15 8 to 11 11 to 15 114 to 13/
3 8toll 6to 8 8 to 11 3/4 to 1
4 5 to 8 4 to 6 ............. ................

Table 2 gives productivity indices and estimated portion of
area used for the main crops for six land types in the various pre-
cipitation zones.
Table 3 gives expected average acre yields and percentage of
years when yields of corn, wheat, grain sorghum, and forage sor-
ghum in eastern Colorado may be expected to be above "cost of
production" yield.

Cost of Production in Terms of Crop Yields
The final result of variations in productivity may be measured
by crop yields. Farmers need some basis for comparing probable
yield with possible costs and sale prices if they are to operate on
a sound basis.
Corn, wheat, grain sorghum, and forage sorghum are the crops
most extensively grown in eastern Colorado.' Therefore, estimates
have been made of the customary expenses involved in producing
these crops.'
Corn was analyzed under two methods of production: (a)
One duckfoot or subsurface tillage in the fall, another in the spring,
planting with two-row lister, and three cultivations with two-row
cultivator, (b) one spring disking followed by listing and cultiva-
tion as in the preceding method. In each case 5 pounds of seed
per acre were used.
Wheat was analyzed under conditions of continuous cropping
and under summer fallow. For the summer fallow wheat a total
of three and one-half surface tillages were assumed, while either
'The calculations as to labor and other expenses were based on an unpub-
lished method of analyzing labor requirements recently developed as part of
the doctorial dissertation of R. T. Burdick of the Economics and Sociology
Section, Colorado Agricultural Experiment Station.


June 1944








TABLE 2.-Productivity ratings and estimated percentage of each of six land types used for corn, wheat, grain
sorghum, and forage sorghum in the dry-land areas of eastern Colorado in four precipitation zones.
Effective Corn Wheat Grain sorghum Forage sorghum
precipitation Pet. of Prod. Pct. of Prod. Pct. of Prod. Pet. of Prod.
Land type zone area index area index area index area index
Dark silty soils of the nearly level
upland and terraces I 20-30 2 50-60 1 0-5 2 5-10 2
Dark sandy soils of the nearly level
uplands and terraces I 75-80 1 10-15 1 0-5 1 5-10 1
Brown silty soils of the rolling uplands I 30-40 2 5-15 2 0-5 2 5-10 2
Brown silty soils of the nearly level
uplands and terraces II 5-15 3 20-40 2 5-20 2 5-30 2
Brown sandy soils of the nearly level
to gently rolling uplands and terraces II 20-50 2 5-10 10-30 1 10-30 1
Brown silty soils of the rolling uplands II 0-10 3 0-5 2 5-15 2 5-15 2
Brown silty soils of the nearly level
uplands and terraces III 0-5 4 20-40 3 5-20 2 5-30 2
Brown sandy soils of the nearly level
to gently rolling uplands and terraces III 5-15 3 0-5 10-30 2 10-30 1
Brown silty soils of the rolling uplands III ** ** ** ** 5-10 2 5-10 2
Light brown silty soils of the nearly level
to gently rolling uplands and terraces IV 0-5 4 0-15 4 0-10 3 5-10 3
Brown sandy soils of the nearly level
to gently rolling uplands and terraces IV 5-10 4 0-5 5-20 2 5-20 2
*Wheat is seldom grown on the sandy soils in Zones II, III, and IV, because their level of productivity for corn and sorghum is
much higher than any other non-irrigated land in the vicinities in which they occur.
**Corn and wheat are not generally grown on the sloping hard lands in Zone III.







TABLE 3.-Expected average acre yields and percentage of years when yields of the four major dry-land crops in
Eastern Colorado may be expected to be above "cost of production" yield. (Crop yield and precipitation
records from four dry-land field stations in and near eastern Colorado served as a basis for estimating
probable yields and percentage of years above "cost of production" yield.)
Corn Wheat Grain sorghum Forage sorghum
Effective Years Years Years Years
precipi- Expected above Expected above Expected above Expected above
station ave. yield "C-P" ave. yield "C-P" ave. yield "C-P" ave. yield "C-P"
Land type zone yield* yield* yield* yield*
Bushels Percent Bushels Percent Bushels Percent Tons Percent
Dark silty soils of the nearly level
uplands and terraces I 12 55 12 '80 15 80 1.6 80
Dark sandy soils of the nearly level
uplands and terraces I 16 80 12 80 19 80 2.2 100
Brown silty soils of the rolling uplands I 13 55 10 80 15 80 1.7 80
Brown silty soils of the nearly level
uplands and terraces II 9 35 10 65 13 65 1.4 65
Brown sandy soils of the nearly level
to gently rolling uplands and terraces II 13 65 ** .... 17 65 2.0 100
Brown silty soils of the rolling uplands II 11 35 9 65 13 65 1.6 65
Brown silty soils of the nearly level
uplands and terraces III 7 25 7 50 11 50 1.3 50
Brown sandy soils of the nearly level
to gently rolling uplands and terraces III 11 50 ** .... 15 50 1.8 100
Brown silty soils of the rolling uplands III *** .... ** .... 11 50 1.4 50
Light brown silty soils of the nearly level
to gently rolling uplands and terraces IV 4 10 4 30 9 30 1.0 30
Brown sandy soils of the nearly level
to gently rolling uplands and terraces IV 7 30 ** .... 12 30 1.5 100
*"Cost of production" yield.


**Wheat is seldom grown on the sandy soils in Zones II, III, and IV, because their
much higher than any other non-irrigated land in the vicinities in which they occur.
***Corn and wheat are not generally grown on the sloping hard lands in Zone III.


level of productivity for corn and sorghum Is







42 COLORADO AGRICULTURAL EXPERIMENT STATION


one duckfoot or one disking was assumed for the continuous wheat.
In each case 30 pounds of seed per acre were used.
Grain and forage sorghums were analyzed under identical
methods as those used for corn (up to harvest), except that 42-inch
rows were assumed for sorghums in place of 44-inch rows for corn,
and 21/4 pounds ol grain sorghum seed or 5 pounds of forage sor-
ghum seed were used.
For all crops, taxes at 29 cents per acre and interest at 39
cents per acre were uniformly charged (6 percent on $6.50, 1938
dry-land assessed valuation). Labor and power costs for seedbed
preparation and planting were charged at $1.05 per tractor hour
(to cover men at 30 cents per hour, equipment at 25 cents per hour,
and tractor at 50 cents per hour). Harvesting costs were esti-
mated at 9.5 cents per bushel for corn (to include shelling), at
$1.00 or $1.50 per acre for combining wheat, at $3.10 per acre for
grain sorghum, and at $1.35 for forage sorghum.
To all costs 20 percent was added to cover overhead expenses.
With the values at 55 cents per bushel for corn, 45 cents per
bushel for grain sorghum, 70 cents per bushel for wheat, and $4.00
per ton for forage sorghum, the necessary yield was calculated to
cover estimated costs. It should be pointed out that the rates and
values used in the cost calculations are based upon typical condi-
tions for the 3-year period, 1937 to 1939, prior to World War II,
and that no allowance was made for variations either in. the pro-
ductive capacity of the land or in operators' practices. Table 4
gives an analysis of production costs on a per-acre basis of corn,
grain sorghum, forage sorghum, and wheat (continuous and fallow).


Bulletin 486







TABLE 4.-Estimates of comparative per acre expense, dry-land crop production.
Continuous Fallow
Corn Grain sorghum Forage sorghum wheat wheat
Duck- Disk Duck- Disk Duck- Disk Duck- Disk Duckfoot
foot foot foot foot
Hours Hours Hours Hours Hours Hours Hours Hours Hours
Operation
Duckfoot t .96 t .96 .96 .48 1.68
Disk .36 .36 .36 .36 ....
List .50 .50 .51 .51 .51 .51
Plant .. ... .24 .24 .24
Cultivates 1.50 1.50 1.53 1.53 1.53 1.53 ...
Total crew hours 2.96 2.36 3.00 2.40 3.00 2.40 .72 .60 1.92
Cost per acre
At $1.05 per hour $ 3.11 $ 2.48 $ 3.15 $ 2.52 $ 3.15 $ 2.52 $ .76 $ .63 $ 2.02
Seed .15 .15 .08 .08 .08 .08 .60 .60 .60
Tax .29 .29 .29 .29 .29 .29 .29 .29 .58
Interest .39 .39 .39 .39 .39 .39 .39 .39 .78
Sub-total 3.94 3.31 3.91 3.28 3.91 3.28 2.04 1.91 3.98
Harvest .95 .76 3.10 3.10 1.35 1.35 1.00 1.00 1.50
Sub-total 4.89 4.07 7.01 6.38 5.26 4.63 3.04 2.91 5.48
20 percent overhead .98 .81 1.40 1.28 1.05 .93 .61 .58 1.10
Total 5.87 4.88 8.41 7.66 6.31 5.56 3.65 3.49 6.58
Less fodder .... 3.00 3.00
Net cost of grain .... .... 5.41 4.66
Value per unit, bushel .55 .55 .45 .45 5.00 T 5.00 T .70 .70 .70
Necessary yield, bushel 10.67 8.87 12.02 10.36 1.26 T 1.11 T 5.21 4.99 9.40


*Once over.
tTwice over.
tThree times over.
IThree and one-half times over.
Note: This comparison is made


with 2-row lister and 2-row cultivater


acre costs by 85 cents. With 55-cent corn this would be 1.55 less bushels
less sorghum (or .17 less tons forage).


If 3-row lister and
of corn; with 45-cent


cultivator are used, this reduces per
sorghum this would be 1.89 bushels







44 COLORADO AGRICULTURAL EXPERIMENT STATION


SUMMARY AND CONCLUSIONS
In the analysis presented, eastern Colorado is divided into four
climatic zones. The zones are determined by the effective precipi-
tation, which in turn is dependent upon total precipitation, seasonal
distribution, temperature, evaporation, and altitude. Mature soil
characteristics and crop yields were used in certain parts of the
area as a guide in locating effective precipitation zone boundaries.
The soil types of eastern Colorado have been grouped into ten
land types. Each type within itself represents a product of soil,
slope, and effective precipitation. The important physical char-
acteristics of the soils within each land type are given. Tillage
practices and applicable erosion control measures are briefly dis-
cussed.
Wind and water erosion are hazards in eastern Colorado. Wind
erosion affects a larger percentage of the area than water erosion,
and the damage from soil blowing is of greater scope.
The change in the fertility of soil which accompanies erosion
is difficult to evaluate in eastern Colorado because no quantitative
field tests have been made. Observation over a period of several
years, however, indicates that most of the non-irrigated soils have
sufficient available plant nutrients to produce as large a yield as
is possible under the limited precipitation. This condition empha-
sizes the importance of catching and holding the precipitation on
the land where it falls.
Limited and erratic rainfall, high winds, and high evaporation
characterize the prevailing climate in eastern Colorado. Such cli-
matic conditions make the stability of the land and the physical
condition of the soil as important in dry-land crop production as
is the fertility level of the soil.
Expected average acre yields and the most probable yield dis-
tribution over an average 10-year period are given for corn, wheat,
grain sorghum, and forage sorghum in each precipitation zone on
the various land types where these crops are grown.
Yield estimates are based on the crop yield-precipitation rela-
tionships shown by crop yields and precipitation records over a
30-year period at four dry land field stations situated in and near
eastern Colorado. These estimates were then extended over eastern
Colorado by studies of soil-moisture relationships, precipitation
records of the U. S. Weather Bureau, and relative yield estimates
of farmers and agricultural technicians of the area.
Estimated cost of production in terms of crop yields are given
for corn, wheat, grain sorghum, and forage sorghum. Rates and
values used in the cost calculations are based upon typical con-
ditions for the 3-year period, 1937 to 1939, prior to World War II.


Bulletin 486








LAND TYPES IN EASTERN COLORADO


Analysis of crop yields, yield distribution, cost of production,
and the proportion of each land type used for corn, wheat, grain
sorghum, and forage sorghum indicates the following conclusions:
1. Sandy soils have a much more favorable distribution of corn
yields than do silty soils in the same precipitation zone.
2. The sandy soils in Precipitation Zones I and II are the most
satisfactory soils for corn production on the dry lands of
eastern Colorado.
3. Grain sorghums under dry farming produce more grain on
all land types than does corn in eastern Colorado.
4. Forage sorghums will yield some feed on nearly any tillable
area in eastern Colorado. However, yields are rather low
on the silty soils of Precipitation Zones III and IV.
5. In Precipitation Zone I, corn and wheat are grown most
extensively on the soils to which they are best adapted.
6. Corn and sorghums produce consistently higher yields on
sandy than on silty soils.
7. Yields of corn and sorghums are as high on silty soils of
the gently rolling areas as on the nearly level areas, but
yields of wheat are lower.
8. Wheat, where grown on sandy soils, produces about the
same average yield as on adjacent silty soils.
9. All land types that produce average wheat yields well above
"cost of production" yields are in Zones I and II.
10. Cost of production estimates show that it is cheaper to
produce wheat on fallow than on land continuously cropped.


June 1944












Colorado State College

COLORADO AGRICULTURAL EXPERIMENT STATION

FORT COLLINS, COLORADO

STATE BOARD OF AGRICULTURE
LEON S. McCANDLESS, President ......................................Craig
CHARLES W. LILLEY, Vice President .............................. Lakewood
GEORGE McCLAVE........................ ......... .............. McClave
ROBERT ROEMER.................................................. Boulder
J. W. GOSS........................................................... Pueblo
R. F. ROCKWELL ...................................... ........... Paonia
W. I. GIFFORD..................................................... Durango
REX EATON........................................................... Eaton
Ex-officio GOVERNOR JOHN C. VIVIAN
PRESIDENT ROY M. GREEN

EXPERIMENT STATION OFFICERS
ROY M. GREEN, M.S., D.Sc..........................................President
HOMER J. HENNEY, M.S................ ........................... Director
JAMES R. MILLER ......................... ...................... Treasurer
tMARVIN J. RUSSELL, A.B............................................ Editor
SADIE I. COOLEY, B.S............................................ Chief Clerk

AGRICULTURAL DIVISION SECTION CHIEFS
ALVIN KEZER, A. M. ........................................... Agronomy
R. C. TOM, M.S. ...................................... .Animal Investigations
L. W. DURRELL, Ph.D .......................... Botany and Plant Pathology
J. W. TOBISKA, M.A. ..............................................Chemistry
CHARLES R. JONES, Ph.D...................................... Entomology
INGA M. K. ALLISON, S.M...................................Home Economics
A. M. BINKLEY, M.S............................................Horticulture
FLOYD CROSS, D.V.M............................Pathology and Bacteriology
tH. S. W ILGUS, Jr., Ph.D.............................................Poultry
E. W. NELSON, A.M.......................... Range and Pasture Management
R. T. BURDICK, M.S. (Acting) ............... .Rural Economics and Sociology
BRUCE J. THORNTON, M.S................................. Seed Laboratory

ENGINEERING DIVISION SECTION CHIEFS
*N. A. CHRISTENSEN, Ph.D .......... ............................. Chairman
*N. A. CHRISTENSEN, Ph.D ............. ............... Civil Engineering
J. T. STRATE, M.S.. ................................ Mechanical Engineering

AGRONOMY STAFF
ALVIN KEZER, A.M....................................... Chief Agronomist
DAVID W. ROBERTSON, Ph.D....................................Agronomist
tWARREN H. LEONARD, Ph.D................................... Agronomist
ROBERT GARDNER, M.S........................ Associate Agronomist (Soils)
DALE S. ROMINE, M.S.......................... Associate Agronomist (Soils)
tRALPH WEIHING, Ph.D .............................. Assistant Agronomist
tROBERT WHITNEY, M.S....................... Assistant Agronomist (Soils)
tROBERT F. ESLICK, M.S.............................. .Assistant Agronomist
JASPER J. FRENCH, B.S. ............................... Assistant Agronomist

RURAL ECONOMICS AND SOCIOLOGY STAFF
R. T. BURDICK, M.S..................................Acting Rural Economist
J. L. PASCHAL, Ph.D.... ......................... Associate Rural Economist
R. W. ROSKELLEY, Ph.D......................... Associate Rural Sociologist
G. T. HUDSON, Ph.D ............................. Assistant Rural Sociologist

tOn military leave. *On leave.











BULLETIN SERVICE
The following late publications of the Colorado Agri-
cultural Experiment Station are available without cost to
Colorado citizens upon request to the Station or your
county extension office:

POPULAR BULLETINS
Number Title
443 Home-Made Farm Equipment
455 Colorado's Poisonous and Injurious Plants
461 Foxtail Millet in Colorado
462 Population Trends in Colorado
465 Colorado Potato Pests
466 Weeds of Colorado
468 Propagation of Plants
469 Pasture and Forage Crops for Irrigated Areas
470 Winter Wheat Production in Colorado
471 Cultural Factors Affecting Sour Cherry Production
in Colorado
473 Will We Help Youth Preserve Democracy?
474 Lamb Diseases in Colorado Feedlots
475 Starting Vegetable Plants
476 Mechanical Thinning of Sugar Beets
477 Making and Using a Food Dehydrator
478 Freezing Vegetables and Fruits
479 Psyllid Control on Potatoes and Tomatoes in the
Victory Garden
480 Growing Alfalfa in Colorado
481 Strawberry Production in Colorado
482 Field Bean Production Without Irrigation
483 Use of Ground Water for Irrigation in the South
Platte Valley of Colorado
484 Grape Growing in Colorado
485 Buying a Farm in Colorado

PRESS BULLETINS
93 Controlling the Squash Bug
94 Bacterial Ring Rot of Potato
95 'Do Your Bit-Keep Your Family Fit' (information
on nutrition)
97 Wartime Food Processing Aids

Colorado Agricultural Experiment Station
Colorado State College
Fort Collins, Colorado






LAND TYPE MAP


EASTERN COLORADO


COLORADO AGRICULTURAL EXPERIMENT STATION
HOMER J. HENNEY, DIRECTOR


Source of Soil Survey Data


SHADED PORTION FROM SOIL SURVEYS.
UNSHADED PORTION FROM VARIOUS
GENERALIZED SOIL MAPS.









LEGEND



I DARK SILTY SOILS OF THE
NEARLY LEVEL UPLANDS AND
TERRACES (HARD LANDS)






S DARK SANDY SOILS OF THE
NEARLY LEVEL UPLANDS AND
TERRACES (SANDY LANDS)






S BROWN SILTY SOILS OF THE
NEARLY LEVEL UPLANDS AND
TERRACES (HARD LANDS)






BROWN SILTY SOILS OF THE
ROLLING UPLANDS (HARD LANDS)







BROWN SANDY SOILS OF THE
NEARLY LEVEL TO GENTLY
ROLLING UPLANDS AND TER-
RACES (SANDY LANDS)






LIGHT BROWN SILTY SOILS OF
THE NEARLY LEVEL TO GENTLY
ROLLING UPLANDS AND TER-
RACES (HARD LANDS)





CLAY SOILS OF THE LEVEL
TO GENTLY ROLLING UPLANDS
AND TERRACES (GUM-
BO OR HEAVY LANDS)






UNDIFFERENTIATED S H A L L O W
SOILS OF THE ROLLING TO
STEEP UPLANDS (HILLY LAND)






A SAND SOILS AND SANDS OF
S THE DUNELIKE OR HUMMOCKY
UPLANDS (SANDHILLS)







UNDIFFERENTIATED SOILS OF THE
ROLLING TO STEEP MOUNTAIN-
PLAINS TRANSITION (S A N D Y
LANDS AND HARD LANDS)


I I


IRRIGATED AND ALLUVIAL LANDS


SCALE IN MILES


10 20


30


PUBLISVEPS PES.Or




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