The Soils of Western Colorado
Mesa, Delta, Montrose and Ouray Counties
Curtis Swift, Ph.D.
Colorado State University
Extension
Tri River Area Agent (Horticulture)
- Soils of Western Colorado
The valleys in Mesa, Delta and Montrose counties were
carved by rivers from material laid down by the Mancos sea. This page discusses
the geological history of these valleys and the soils (problems and advantages)
created.
- Acid-Loving Plants - a listing
Soils in Western Colorado are typically high in pH (above a pH of 7) yet many
gardeners new to the area attempt to raise acid-loving plants. Hence the reason
for this list.
- Alkaline Soils and the Buffering
Affect of Calcium Carbonate
Soils in the valleys of Western Colorado typically have a pH of 7.5 to 8.5
creating a basic/alkaline condition. With up to four thousand feet of calcium-based
Mancos shale under these valley soils and with irrigation water containing
calcium carbonate, the possibility of reducing pH in gardens and lawns is
highly unlikely.
- Soil Reaction (pH)
Soil reaction or pH is a measure of the `active' hydrogen ions in the soil
water (solution). Changing the pH of the soils in Western Colorado is extremely
difficult if not impossible.
- Cation Exchange Capacity - CEC
The ability of a soil to hold cations is termed its cation
exchange capacity (CEC). Since many cations are plant nutrients the cation
exchange capacity is a measure of the soil's ability to hold such nutrients.
- Plant Nutrients
The essential plant nutrients, their role in plants and origin is provided.
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- The Gunnison Basin selenium Task Force is a group of private, local,
state, and federal interests committed to finding ways to reduce selenium
in our locally affected waterways, while maintaining the economic viability
and lifestyle of the Lower Gunnison River Basin of Western Colorado. These
pages cover the following topics:
- What is Selenium
- History of Selenium Issues
- Addressing the Problem
- Current Projects
- Maps
- Regional Meetings
- Task force Participants
- Sodium Adsorption Ratio (SAR)
Elevated concentrations of sodium ions in soil create a plant growth hazard.
The Sodium Adsorption Ratio (SAR), a measure of the proportion of sodium (Na)
ions compared to the concentration of calcium (Ca) plus magnesium (Mg), is
a common method of estimating this sodium hazard. SAR is discussed and a quick
and easy conversion chart to determine the SAR is provided.
- Soil phosphorus levels and
mycorrhizae-forming fungi
Mycorrhiza are an integral part of most plants. Very high and very low phosphorus
levels may reduce mycorrhizal infection and colonization. This literature
review provides details on the mycorrhiza and phosphorus relationship. References
are listed.
- Soil Reaction (pH)
Soil reaction or pH is a measure of the `active' hydrogen ions in the soil
water (solution). Changing the pH of the soils in Western Colorado is extremely
difficult if not impossible.
Soil Salts
- Mancos Shale
- The soils throughout the valleys of Western Colorado
originated from Mancos shale. The white deposits seen throughout the area
are a salt (gypsum).
- Manures
as Soil Amendments
and Mulches for Vegetables & Ornamental Plants
- Manures contain salts and may increase the soil
salt level when used as mulch or soil amendments. This elevated salt level
can be a serious problem when the resulting soil salt level is greater
than the salt tolerance of the plant.
- Methods Plants use to Tolerate
& Avoid Salts in Soil and Water
- This paper provides an abbreviated listing of methods
higher plants use to avoid/tolerate salts. References are provided.
- Salt Tolerance of Temperate Zone
Plants - a listing
- Soluble salts can cause harm to plants if they are
in high enough concentration in water or soil. Salt levels of up to 139
mmhos/cm have been recorded for our soils, an impossible situation when
attempting to grow plants. This listing should be considered a guide when
recommending trees, shrubs, vines and herbaceous plants for salty sites.
- Soil Salt Problem Areas - A Photograph
- Many salty areas are visible in Mesa, Delta and
Montrose counties - Western Colorado. The accumulation of these salts
on the soil surface are due to insufficient precipitation to wash these
salts below the root zone of plants.
- Soil Testing Procedures
- Soil testing can provide answers to many of the
questions related to pH, salts and plant nutrient availability that are
so necessary for the successful growth of plants. The way the soil sample
is collected and cared for, as well as the soil testing laboratory selected
can make a difference in the accuracy of the results.
- Soluble Salts of Soil
- The soluble salts in soils are mostly combinations
of the cations (+ charged ions) sodium, calcium, and magnesium potassium,
and the anions (- charged) bicarbonate, chloride and sulfate.
WebMaster
Dr. Curtis E. Swift, Area
Extension Agent, Horticulture
Colorado State Extension
2775 US Hwy 50, Grand Junction, CO. 81503
voice: 970-244-1834
fax: 970-244-1700
