Natural Resources
Conservation Service
Ecological site R035XB033NM
Sandy Loam Upland
6-10"
sodic
Last updated: 5/20/2025
Accessed: 04/23/2026
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Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
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Figure 1. Mapped extent
Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.
Ecological site concept
The soils are very deep and well drained. Surface textures include loamy sand. The subsoil has textures of fine sandy loam, clay loam, sandy clay loam, and loamy sand. The soils are moderately sodic (SAR 13-30), moderately saline (EC 8-16), and mildly to strongly alkaline (pH 7.4-9.0).
This site occurs on eolian-mantled fan terraces (fan remnants). Slopes range from 1 to 3 percent.Table 1. Dominant plant species
Tree Not specified
Shrub Not specified
Herbaceous (1) Sporobolus airoides
(2) Pleuraphis jamesiiPhysiographic features
This site occurs on eolian-mantled fan terraces (fan remnants). It benefits from run-in water from adjacent areas after high-intensity short-duration summer thunderstorms. Slopes range from 1 to 3 percent. Elevations range from 5,400 to 5,700 feet.
Table 2. Representative physiographic features
Landforms (1) Fan remnant
Elevation 5400 – 5700 ft Slope 1 – 3 % Aspect Aspect is not a significant factor Climatic features
Mean annual precipitation varies from 5 to 8 inches with about 60% of it coming as rain from April through October. May and June are the driest months. Most of the precipitation from November through March comes as snow. High-velocity winds are common in late winter and early spring.
Mean temperatures for the hottest month, July, are about 83 degrees F. The coldest month is January, when the mean temperature is about 27 degrees F. Extreme temperatures of 104 and -17 degrees F have been recorded. The frost-free period ranges from 140 to 160 days.
The cool-season plants start growth in March and end with plant maturity and seed dissemination about mid-June. Warm-season plants grow from June through September, taking advantage of the moisture and warmth from tropical air out of the Gulf of Mexico. About 40 percent of the total precipitation is received during these summer months. The other 60 percent, received from fall through spring, influences cool-season plants.
The tabular climate summary for this ESD was generated by the Climate Summarizer
(http://www.nm.nrcs.usda.gov/technical/handbooks/nrph/Climate_Summarizer.xls) using data
from the following climate stations (results are unweighted averages):
296098 Newcomb, NM (Period of record = 1948 to 1971)
298284 Shiprock, NM (Period of record = 1926 to 2006)Table 3 Representative climatic features
Frost-free period (average) 170 days Freeze-free period (average) 190 days Precipitation total (average) 10 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
This site occurs on eolian-mantled fan terraces (fan remnants). It benefits from run-in water from adjacent areas after high-intensity short-duration summer thunderstorms.
Soil features
The soils are very deep and well drained. They formed in eolium and alluvium derived from sandstone and shale. Surface textures include loamy sand. The subsoil has textures of fine sandy loam, clay loam, sandy clay loam, and loamy sand. Permeability is moderately slow. Available water holding capacity is high to very high. Runoff is slow, and the hazard of water erosion is moderate. The hazard of soil blowing is severe. The soils are moderately sodic (SAR 13-30), moderately saline (EC 8-16), and mildly to strongly alkaline (pH 7.4-9.0).
Shiprock SSA:
140 – Benally loamy sand, overblown
Additional information may be found in Section II of the Field Office Technical Guide.Table 4. Representative soil features
Surface texture (1) Loamy sand
Family particle size (1) Loamy
Drainage class Well drained Permeability class Moderately slow Soil depth 60 in Electrical conductivity
(0-40in)8 – 16 mmhos/cm Sodium adsorption ratio
(0-40in)13 – 30 Soil reaction (1:1 water)
(0-40in)7.4 – 9 Ecological dynamics
This site has a plant community made up primarily of midgrasses, shortgrasses, some shrubs, and a minor amount of forbs. The reference plant community contains a mixture of cool-season and warm-season grasses.
Plant species most likely to invade or increase on this site when it deteriorates are annual barley, Russian thistle, and other annual forbs. Continuous livestock grazing during winter and spring decreases the cool-season grasses and increases lower forage value grasses and shrubs.
The reference plant community has been determined by study of relict areas or areas protected from excessive grazing. Trends in plant communities going from heavily grazed areas to lightly grazed areas, seasonal use pastures, and historical accounts have also been used.State and transition model
More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textEcosystem states
State 1 submodel, plant communities
State 2 submodel, plant communities
State 1
Reference StateThis state represents the most ecologically stable conditions in terms of resistance to erosion. Moreover, this state has the highest potential for productivity and plant diversity.
Community 1.1
Reference Plant CommunityThis site has a plant community made up primarily of midgrasses, shortgrasses, some shrubs, and a minor amount of forbs. The reference plant community contains a mixture of cool-season and warm-season grasses.
Plant species most likely to invade or increase on this site when it deteriorates are annual barley, Russian thistle, and other annual forbs. Continuous livestock grazing during winter and spring decreases the cool-season grasses and increases lower forage value grasses and shrubs.
The reference plant community has been determined by study of relict areas or areas protected from excessive grazing. Trends in plant communities going from heavily grazed areas to lightly grazed areas, seasonal use pastures, and historical accounts have also been used.Figure 4. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
Plant type Low
(lb/acre)Representative value
(lb/acre)High
(lb/acre)Grass/Grasslike 460 620 770 Shrub/Vine 30 60 90 Forb 5 20 40 Total 495 700 900 Figure 5. Plant community growth curve (percent production by month). NM0381 , R035XB033NM-Sandy Loam Upland 6 to 10 inch sodic-Reference State. R035XB033NM-Sandy Loam Upland 6 to 10 inch sodic-Reference State.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec J F M A M J J A S O N D 6 6 7 6 6 5 11 14 12 12 8 7 Community 1.2
Grassland with Mixed ShrubsThis phase is a grassland with mixed shrubs
Pathway P1.1A
Community 1.1 to 1.2Season-long grazing providing little rest and recovery for preferred grazed plants during critical growing periods, coupled with high utilization.
Key drivers
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Livestock grazing or browsing
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Climate
Key ecosystem services affected
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Food and fiber: livestock forage
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Ornamental resources
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Climate regulation: carbon cycling and storage
Pathway P1.2A
Community 1.2 to 1.1Prescribed grazing
Conservation practices
Prescribed Grazing Key drivers
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Livestock grazing or browsing
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Climate
Key ecosystem services affected
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Nutrient cycling
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Food and fiber: livestock forage
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Climate regulation: carbon cycling and storage
State 2
Invaded Annuals StateThis state is characterized by established communities on invasive annuals.
Community 2.1
Perennial Grassland with AnnualsThis phase is dominated by native perennial grasses, but also contains invasive annuals.
Community 2.2
Mixed Grass and Shrubs with AnnualsThis phase is a mix of grasses and shrubs, which contains invasive annuals.
Pathway P2.1A
Community 2.1 to 2.2Season-long grazing providing little rest and recovery for preferred grazed plants during critical growing periods, coupled with high utilization.
Key drivers
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Livestock grazing or browsing
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Climate
Key ecosystem services affected
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Nutrient cycling
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Food and fiber: livestock forage
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Climate regulation: carbon cycling and storage
Pathway P2.2A
Community 2.2 to 2.1Prescribed grazing
Conservation practices
Prescribed Grazing Key drivers
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Livestock grazing or browsing
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Climate
Key ecosystem services affected
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Nutrient cycling
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Food and fiber: livestock forage
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Climate regulation: carbon cycling and storage
Transition T1A
State 1 to 2Season-long grazing providing little rest and recovery for preferred grazed plants during critical growing periods, coupled with high utilization.
Key drivers
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Livestock grazing or browsing
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Seed dispersal by livestock
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Climate
Key ecosystem services affected
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Nutrient cycling
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Food and fiber: livestock forage
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Climate regulation: carbon cycling and storage
Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 alkali sacaton 250–540 alkali sacaton SPAI Sporobolus airoides 250–540 – 2 galleta 50–130 James' galleta PLJA Pleuraphis jamesii 50–135 – 3 squirreltail 0–90 squirreltail ELEL5 Elymus elymoides 0–90 – 4 Indian ricegrass 5–90 Indian ricegrass ACHY Achnatherum hymenoides 5–90 – 5 sand dropseed 5–40 sand dropseed SPCR Sporobolus cryptandrus 5–45 – 6 other perennial grasses 5–40 Forb7 perennial forbs 5–30 8 annual forbs 0–20 Shrub/Vine9 fourwing saltbush 5–40 fourwing saltbush ATCA2 Atriplex canescens 5–45 – 10 other shrubs 0–40 Table 7. Community 1.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 8. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 9. Community 2.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Animal community
Livestock - This site is suitable for yearlong grazing by all classes of livestock, is easily traversed, and is well suited to planned grazing systems.
Wildlife – This site is well used by wildlife that require digging and those which require open grassland.Hydrological functions
Permeability is moderately slow. Available water holding capacity is high to very high. Runoff is slow, and the hazard of water erosion is moderate.
Recreational uses
This site is well suited to hunting, horseback riding, and wildlife observation. The fan terraces have a tremendous aesthetic appeal as grasslands.
Supporting information
Type locality
Location 1: San Juan County, NM Township/Range/Section T22N R17W S7 General legal description Sheep Springs Quad – 0.5 miles NE of Sheep Springs, NM – Navajo Reservation, NM. Contributors
John Tunberg
Michael Carpinelli
UnknownApproval
Kendra Moseley, 5/20/2025
Rangeland health reference sheet
Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.
Author(s)/participant(s) Contact for lead author Date 04/23/2026 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
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Presence of water flow patterns:
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Number and height of erosional pedestals or terracettes:
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Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
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Number of gullies and erosion associated with gullies:
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Extent of wind scoured, blowouts and/or depositional areas:
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Amount of litter movement (describe size and distance expected to travel):
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Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
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Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
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Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
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Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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Functional/Structural Groups (list in order of descending dominance by above-ground annual-production or live foliar cover using symbols: >>, >, = to indicate much greater than, greater than, and equal to):
Dominant:
Sub-dominant:
Other:
Additional:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
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Average percent litter cover (%) and depth ( in):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize degraded states and have the potential to become a dominant or co-dominant species on the ecological site if their future establishment and growth is not actively controlled by management interventions. Species that become dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the ecological site:
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Perennial plant reproductive capability:
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PrintThe Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
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