|
RIO GRANDE COUNTY AREA, COLORADO
<br />Derrick Series
<br />The Derrick series consists of well drained soils 10
<br />to 20 inches deep over gravel and cobbles. These soils
<br />formed in cobbly alluvium on alhn ial fans and terraces.
<br />Slopes are 0 to 3 percent. Elevation is 7,600 to 8,200
<br />feet. 1\ ahu•al vegetation is dominantly blue grams, ring
<br />muhly-, sand dropseed, and tort rabbitbrush. The
<br />average annual precipitation is about 7 inches, the
<br />mean annual air temperature is about 41° F, anc] the
<br />frost-free season is 90 to 105 days.
<br />In a representative profile the surface ]aver is dark
<br />grayish brotrn cobbly-loam about 4 inches thick. The
<br />subsoil is dark brown very gravelly clay loam or very
<br />gravelly loam about 13 inches thick. The substratum
<br />is gravel, cobbles, and sand that extend to a depth of
<br />60 inches or more.
<br />Permeability- is moderate, and the available .rater
<br />capacity' is lots or moderate. Reaction ranges from
<br />neutral to moderateh• alkaline. The effective rooting
<br />depth is 10 to 20 inches.
<br />These soils are used for range, irrigated crops, and
<br />trildlife.
<br />Representative profile of Derrick cobbly loam, 1,500
<br />feet Crest of the northeast corner sec. 2, T. 37 N., R.
<br />i E.
<br />Al-0 to 9 inches; light brownish gray- (101"P. G/2)
<br />cobbly loam, dark grayish brown (101"P. 4/'?)
<br />moist; moderate fine granular stn[cture; soft, very
<br />friable; 3o percent cobbles and gravel; neutral;
<br />gradual smooth boundary'.
<br />B2t-4 to 14 inches; Drown (7.SYP. 5/3) very gravelly clay
<br />loam, dark brown (7.51'R 9/3) moist; weak
<br />medium prismatic structure parting to moderate
<br />fine subangutar blocky-; hard, friable; thin nearly
<br />continuous clay- films on peels and in root channels;
<br />GO pm'cent cobbles and gravel; mildly alkaline;
<br />clear wavy boundary-.
<br />Rica-14 [o li inches; brown (lOYP. 5/31 very- gravelly
<br />loam, dark brown (lOYR 4/3) moist; weak medium
<br />subangutar blocks structure; soft, very friable;
<br />few thin patchy c!ay films on peels; i0 percent
<br />cobLles and gravel; visible secondarc calcium car-
<br />bonate occurring as concretions in thin seams and
<br />streaks and as coatings on coarse fragments; cal-
<br />careous; moderately alkaline; gradual wave bound-
<br />at'c.
<br />IICca-1. •to GO inches; vet}- gravelly sand; carbonate
<br />coatings on coarse fragments; GO percent cobbles
<br />an[I gravel.
<br />The Al horizon is 3 to G inches thick and is cobbh_- loam
<br />to gravelly sandy loam. The }32t horizon is 4 to 12 inches
<br />thick and is ten- cobble clay loam in some pedons. The
<br />content of gravel•and cobbles in the A horizon ranges from
<br />35 to 60 percent and from 35 to i0 percent in the P, horizon.
<br />Depth to lime ranges from fi to 30 inches.
<br />De-Derrick cobbh- loam. This nearly level or vet}'
<br />gently- sloping soil occupies alluvial fans and terraces.
<br />Slopes are 0 to 3 percent. About 15 percent of this unit
<br />is included areas of Gravpoint gravelly sandy loam and
<br />small areas of Platoro loam and Dunul cobble sandy
<br />loam. •
<br />Runoff is slots. The erosion hazard is slight.
<br />This soil is used mainly for range and tyildlife. Some
<br />small areas are ^sed for irrigated crops. Capabilih-
<br />unit IAs-I irrigated, 1•IIs-7 nonirrigated; 111ottntain
<br />Outtcash range site.
<br />Dunul Series
<br />11
<br />The Dunul series consists of excessively- drained
<br />soils 6 to 10 inches deep over gravel, cobbles, and sand.
<br />These soils formed in cobble alhn•ium on alhn-ial fans.
<br />Slopes are 0 to 1 percent. Elevation is 1,600 to 7,900
<br />feet. natural vegetation is dominantly blue grams,
<br />Indian ricegrass, snakes eed, and tort rabbitbrush. The
<br />average annual precipitatiot is about 7 inches, the
<br />mean annual air temperature is about 41° F, and the
<br />frost-free season is 90 to 105 days.
<br />In a representative profile the surface layer is dark
<br />grayish bronco cobble sandy loam about 10 inches thick.
<br />The underlying material is dark gray very gravelly
<br />sand that extends to a depth of 60 inches or more.
<br />Permeability- is rapid, and the available hater
<br />capacity is lo~c-. Reaction is moderately alkaline. The
<br />effective rooting depth is 6 to 12 inches.
<br />These soils are used for irrigated crops and for
<br />range.
<br />Representative profile of Dunul cobbh• sands loam,
<br />1,x00 feet east and 300 feet north of the southlvest
<br />corner sec. 18, T. 40 \., R. 8 E.
<br />Ap-0 to 10 inches; grayish brown (lOFR 5/4) cobbly
<br />sandy loam, dark grayish brown (101-P. 4/E)
<br />moist; moderate fine granular structure; soft, very
<br />friable; 3..-i percent cobbles and ?5 percent gravel;
<br />slightly calcareous; moderately- alkaline; diffuse
<br />smooth boun[!arv.
<br />C-10 to fi0 inches; grad- (101-R 5,~1) very- gravell}~ sand,
<br />dark gray- (lOTR 4/1) moist; single grained;
<br />loose; SO percent gravel and cobbles; calcareous;
<br />moderately alkaline.
<br />The A horizon is 4 to 10 inches thick. It is gravelly sandy
<br />loam in some fields ~~~here most of the cobbles have been
<br />removed by rockpicking machinery-. The content of gravel
<br />and cobbles in the A horizon ranges from 35 to i0 Percent.
<br />The C horizon is eery gravelly sand or very cobble sand.
<br />Dn-Donal rnbbly sandy loam. This Heath- level
<br />soil occupies large areas at the upper end of alluvial
<br />fans in the north-central part of the Area. Slopes are
<br />0 to 1 percent. About 20 percent of this unit is included
<br />areas of Quamon gravelly sandy loam and 10 percent
<br />areas of \orte gracelh• sandy loam.
<br />Runoff is slog. The erosion hazard is slight.
<br />If Crater is available. most of the acreage is used for
<br />irrigated potatoes. email grain, alfalfa, and vegetables.
<br />Some areas are used for range. Capability trait Id's-1
<br />irrigated, ~'IIs-i nonirrigated; D~fountain Outtc-ash
<br />1'ange Slte.
<br />Embargo Series
<br />The Embargo series consists of moderately deep,
<br />trell drained soils. These soils formed in residuum
<br />~reathered from rhrolite on motmtainsides. Slopes are
<br />10 to 25 percent. Elevation is 9,000 to 10,000 feet.
<br />\atural vegetation is dominantly mountain muhlp,
<br />Arizona fescue, Parry oatgrass, and needleandthread.
<br />The average annual precipitation is about 16 inches,
<br />the mean annual air temperature is about 36° F, and
<br />the frost-free season is 70 to 90 days.
<br />In a representative profile the surface layer is dark
<br />brotrn very stony loam about 7 inches thick. The sub-
<br />soil is dark brotrn very stony loam, clay loam, or clay
<br />
|