2.4 SOIL
Introduction Soil is the unconsolidated mineral or organic material on the immediate surface of the Earth that serves as a natural medium for the growth of terrestrial plants. This unconsolidated mineral or organic matter has been subjected to and shows effects of genetic and environmental factors including climate, water, temperature, and macro- and microorganisms, conditioned by relief, acting on parent material over a period of time. Soil differs from the material from which it is derived in many physical, chemical, biological, and morphological properties. It is often characterized by horizons, or layers, that are distinguishable from the initial parent material as a result of additions, losses, transfers, and transformations of energy and matter or the ability to support rooted plants in a natural environment.
The upper limit of soil is the boundary between soil and air, shallow water, live plants, or plant materials that have not begun to decompose. Areas are not considered to have soil if the surface is permanently covered by water too deep for the growth of rooted plants. The lower boundary that separates soil from the non-soil underneath is most difficult to define. Soil consists of horizons near the Earth's surface that, in contrast to the underlying parent material, have been altered by the interactions of climate, relief, and living organisms over time. Commonly, soil changes at its lower boundary to hard rock or to earthy materials virtually devoid of animals, roots, or other marks of biological activity. For purposes of classification, the lower boundary of soil is usually set at approximately 6.5 feet / 78 inches. (See Soil Science Glossary, Soil Science Society of America)
Current Setting
Soilcomposition helps determinevegetation types, growthandwildlifehabitats.Soiltypesarealsorelatedtowaterquality,salinity,anderosion. Garfield County has consideredimpactson soils,includingsalinitycontrol,waterquality,anderosion,inrelationtoothermanagement decisions and desiredconditions. ThissectionprovidesanoverviewofsoilinGarfield Countandservesasabaselineforanalysisofresourcemanagementalternatives. The Natural Resource Conservation Service (NRCS) – formerly the Soil Conservation Service - has produced numerous soil reports for Garfield County and other areas in the region. Reports contain detailed data that is too voluminous to be included in this plan, including soil description, soil properties, maps, characteristics and other data. Reports are available to the public through the NRCS websites and include:
Canyonlands National Park, Current
Capitol Reef National Park, 2014
Dixie National Forest, Parts of Garfield, Washington, Iron, Kane, and Wayne Counties, Current
Glen Canyon National Recreation Area, Arizona and Utah, 2010
Grand Staircase-Escalante National Monument, 2005
Fishlake National Forest, East Portion, Parts of Sevier, Piute and Wayne Counties, Current
Henry Mountains Area, Parts of Garfield, Kane, and Wayne Counties, 1990
Loa, Marysvale Area, Parts of Piute, Wayne, and Garfield Counties, Current
Panguitch Area, Parts of Garfield, Iron, Kane, and Piute Counties, 1990
These soilsurveysand publicationsareajointeffortoftheUnitedStatesDepartmentofAgricultureandotherfederalagencies,stateagenciesincluding theAgriculturalExperimentStations,and localagencies. Majorfieldworkforthe surveysare described in the individual documents. Soilmapsmaybe copiedwithoutpermission.Enlargementofthesemaps,however,couldcausemisunderstandingofthedetailofmapping. Ifenlarged,mapsdonotshowthesmallareasofcontrastingsoilsthatcouldhavebeenshownatalargerscale.
The surveys containinformationthatcanbeusedinland-planning programsandcontainpredictionsofsoilbehaviorforselectedlanduses.Thesurveysalsohighlightlimitationsandhazardsinherentinthesoil,improvementsneededtoovercomethelimitations,andtheimpactofselectedlandusesontheenvironment.
Thesesoilsurveys aredesignedformanydifferentusers.Farmers,ranchers,foresters,andagronomistscanusethemtoevaluatethepotentialofthesoilandthemanagementneededformaximumfoodandfiberproduction.Planners,communityofficials,engineers,developers,builders,andhomebuyerscanusethesurveystoplanlanduse,selectsitesforconstruction,andidentifyspecial practicesneeded toensureproperperformance.Land managers,teachers,students,andspecialistsinrecreation,wildlifemanagement,wastedisposal,andpollutioncontrolcanusethesurveystohelpunderstand,protect,andenhancetheenvironment.
Greatdifferencesinsoilpropertiescanoccurwithinshortdistances.Somesoilsareseasonallywetorsubjecttoflooding.Someareshallowtobedrock. Somearetoounstabletobeusedasa foundationforbuildingsorroads.Clayeyorwetsoilsarepoorlysuitedtouseasseptictankabsorptionfields.Ahighwatertablemakesasoilpoorlysuitedtobasementsorunderground installations. Theseandmanyothersoilpropertiesthataffectlandusearedescribedinthissoilsurveys.Broadareasofsoilsareshownonthegeneralsoilmaps.Thelocationofeachsoilisshownonthedetailedsoilmaps.Eachsoilin thesurveyareaisdescribed.Informationonspecificusesisalso givenforeachsoil.HelpinusingthispublicationsandadditionalinformationareavailableatthelocalofficeofNRCSortheCooperativeExtensionService.
Soilmanagementis dependentonacombinationoffactors,includingsoiltype,climate, intensity of precipitation,geologicsetting,andvegetativecover,andhowtheresourcesareimpactedbymultipleuses(e.g.,recreation,mineraldevelopment,grazing, etc.). Vegetationcan besparseinportionsoftheCounty becauseoftheshortgrowingseasonanddistributionofeffectivemoistureinsomesoils. Rangelandand forest healthevaluationshavebeenconducted by the BLM and the Forest Service throughoutthearea. Theevaluationsincludeanassessmentofsoilconditionindicators.Theindicatorsincludequalitativeevaluationsofanarea’sdeparturefromanticipatedecologicalconditions,usuallyobtainedfromarepresentativesitedescription.Someoftheindicatorsincluderills,gullies,resistancetoerosion,compactionlayers,evidenceofwinderosion,andsoilsurfacelossordegradation.Generally,siteshave beenclassifiedasnonetoslightorslighttomoderatedeparturefromthesitedescription.Theseevaluationsindicatethelandscape-levelsoilconditionwithintheCountyislargelyproperlyfunctioning,althoughtheremaybesite-specificissuesofsoilimpactsordegradation.
Erosionandcompactionaretwoimportantfactorsofconcernintheplanningarea.SeveralareasofGarfield County may containsoilsthatareconsideredtobehighlysusceptibletoerosion. Almost anyactionthatincreasesvegetationcoverorimprovessoilstructureinthese areaswillbebeneficial,resultinginreducederosionandincreasedvegetationsurfacelitter.
Erosionisoneofthe soil related indicators that is examined whiledeterminingrangeland health. Erosionindicatorssuchasrills,waterflowpatterns,bareground,gullies,littermovement,soilresistancetoerosion, andsoilsurfacelossordegradationvary throughout the County. Generally,soilsonsteeperslopeswithlongerslopelengthandlessvegetativecovererodemorerapidlythansoilswithflatterslopes,shorterslopelength,andmorevegetation.
SomeGarfield Countysoilsare more pronetoerosion than others.Thesesoilsusuallyhaveseveralintrinsicpropertiesthatmakethemsusceptibletoerosion.Suchfactorsashighsaltconcentrations,fineorcoarsetextures,shallowdepths,orsteepslopescancontributetoasoil’serodibility. Soilsderivedfromsalinesedimentaryformationstendtobehighinsalts.Highsaltaccumulationsinfluencetheavailabilityofplantnutrientsandwaterforplantgrowth.Becauseoftheresultantsparsevegetativecoveronthesesoils,soilparticlesmaynotbe“anchored”inplaceandmayeasilybeerodedbywindorwater. Slopesteepnessalsoincreasestheerosionpotentialofsoilsbecauseitincreasestherateatwhichwaterwillflowoverlandandtransportsoilparticles.Manyscientists(SoilConservationService1984)identifyslopesof20-35percentaspotentiallycontributingtoasevereerosionhazard.Soiltexturecontributestothecredibilityofasoilaswell.Finetexturedsoilssuchasclaysorsiltyclayshaveslowinfiltrationratesandhighrunoffrates.Asaresult,rillsandgulliesareeasilyformedduringstormevents. Overlandflowandsedimenttransportintostreamscanbepronouncedduringintenseprecipitationeventsorduringperiodsofsevererunofforsnowmelt. Inareasoflimitedvegetativecover,thistransportisexacerbated.
Soilcompactioncanoccurasaresultofrepeatedimpactordisturbanceofthesoilsurfaceoveratimeperiod.Farmmachinery,herbivoretrampling,andrecreationvehicletraffic,oranyactivitythatrepeatedlycausesanimpactonthesoilsurface,cancauseacompactionlayer(ChanasykandNaeth1995,Cole1985,andThurowetal.1988).Compactionbecomesaproblemwhenitbeginstolimitplant growth,waterinfiltration,ornutrientcyclingprocesses(Wallace1987;WillatandPullar1983,Thurowetal.1988;Hassinketal.1993). Moistsoilismoreeasilycompactedthandryorsaturatedsoil(Hillel1998).However,somestudiesindicaterecoveryprocesses(e.g.,earthwormactivityandfrostheaving)aregenerallysufficienttolimitcompactionbylivestockinmanyuplandsystems(Thurowetal.1988). The physicalconditionofsoilisassessedaspartoftherangelandhealthevaluationprocessandduringotheractivityandimplementationlevelplanning.
Biological Soil CrustsBiologicalsoilcrustsarerecognizedashavinganinfluenceonterrestrialecosystemswheretheyoccur.Thesecommunitiesarereferredtoascryptogamic,cryptobiotic,microbioticormicrophyticsoilcrusts.Thesecrustsfunctionasalivingmulchbyretainingsoilmoistureanddiscouragingthegrowthofannualweeds.Theycanreducewindandwatererosion,fixatmosphericnitrogenintoaformuseablebyplants,andcontributetothesoilorganicmatter.Thesecrustscanbeusedasindicatorsofecologicalhealth,aswellasindicatorsofphysicaldisturbance.Biologicalsoilcrustsare present onvarioussoilsurfacesthroughouttheregion. When present, soil crusts can exist in various forms and are often pervasive over large areas. Surface disturbance can alter the form of the crusts but generally does not create significant mortality. When moisture and temperature conditions are favorable, crust development continues.
Totalcrustcoverisinverselyrelatedtovascularplantcover,aslessplantcoverresultsinmoresurfaceavailableforcolonizationandgrowthofcrustalorganisms(USDOI2001).Whenallcrusttypesarecombined(cyanobacterial,moss,lichen),coverisgreatestatlowerelevationinlandsites(duetolessvascularplantcover).Biologicalsoilcrustsin the areaaremostlycyanobacteria(Microcoleus)andnitrogen-fixinglichens(Collema).Thesecyanobacteriaandnitrogen-fixinglichensaregenerallylimitedandsparseintheCountyduetorelativelyhighelevationsandrelativelydensevascularplantcover.Smallareasofmoredensesoilcrustsdoexist, especiallyatlowerelevations anddrysiteswithlessdensevegetativecover, but crusts are not as prevalent as neighboring counties with even lower elevation, sparser vegetation and sandier soils.
Theimportanceofbiologicalsoilcrustsisoften recognizedbythescientificcommunityandby federal agencies.However,sciencehasnotdeterminedhowmuchsoilcrustisneededinacertainsoiltype,ecologicalrangesiteorwoodlandcommunity. No objective science exists indicating at what levelecologicalprocesseswilloperate and promotehealthy conditions for soil crust.Thereisnoclearbiologicalcrustevaluation toolsthat can be appliedonasite-specificbasistoallowsoundandreasoneddecisionsonthissubjector toquantifytheappropriateamountsanddistributionofcrusts.
Standardmethods toassesstheconditionsoftherangelandsinvolvestheuseofecologicalsitesandwoodlandcommunitydescriptionsdevelopedforspecificsoilsurveyareasinaccordancewithstandardsestablishedanddevelopedbytheNationalResourceConservationService,U.S.DepartmentofAgriculture(NRCS). Theseecologicalsitedescriptionsgenerallydonotcontainspecificinformationastothequantitiesofsoilcruststhatareexpectedtobeonthesite.
Prime Farmland Soils The U.S.DepartmentofAgriculture defines prime farmland soils as soilsthatarebestsuitedtoproducingfood,seed,forage,fiber,andoilseedcrops.Suchsoilshavepropertiesthatarefavorablefortheeconomicproductionandsustainedhighyieldsofcrops.Suchsoilsneedonlytobetreatedandmanagedusingacceptablefarmingmethods.Adequatemoistureandasufficientlylonggrowingseasonare also required. Primefarmlandsoilsproducethehighestyieldswithminimalinputsofenergyandeconomicresources,andfarmingthesesoilsresultsin theleastdamagetotheenvironment. Primefarmlandsoilsmaypresentlybeinuseascroplands, woodlands orpastures. However, developed areas larger than 10 acres, publicland,andareas covered with watercannotbeconsidered primefarmland.Soilsthathaveahighwatertable,aresubjecttoflooding,oraredroughtymayqualifyasprimefarmlandsoilsifthelimitationsareovercomebydrainage,floodcontrol,orirrigation.
During the past few decades prime farmland has been converted to residential, commercial and industrial uses in more urbanized areas of the state. Although this trend exists in Garfield County, it is of minimal impact at present. Bydefinition,primefarmlandoccursonly on private lands and is managed under the County’s existing planning and zoning ordinances. No State, Forest Service or BLMlandsin Garfield County qualify for prime or unique farmland status.However,somesoilscouldqualify asprimefarmlandifanadequateanddependablewater supply was available. Precipitation isinadequate,anddependableirrigationwaterislackingonfederallands.Consequently, no prime, uniqueorfarmlandsofstatewideorlocalimportancehavebeenidentifiedonany federallands.
Need for Management Change
1) Land managers need to increase, improve and enhance desirable vegetative cover consistent with ecological site descriptions to improve and preserve soil in Garfield County.
2) NRCS reports indicate soils are often producing at a rate far below their capacity, approaching only 25% in some cases. Land managers need to improve the vegetative productivity of soils for desirable native and non-native vegetative communities consistent with ecological site descriptions.
3) Encroaching conifers and conversion of historic sagebrush/semi-desert grasslands to pinyon/juniper woodlands threatens soil stability and health. Land managers need to actively and aggressively pursue restoration of historical sagebrush/semi-desert grasslands and conversion of Class II and Class III pinyon/juniper woodlands to desirable native and non-native vegetation communities.
4) Land managers need to increase the productivity of 80% of the soils in their jurisdiction to a minimum of 50% capacity prior to January 1, 2035 and an additional 1% of capacity per year for the succeeding 10 years.
5) Biological soil crusts are being used inappropriately to limit the use and productivity of public lands. Land managers need to reserve not more than 0.1% of their lands for management favoring biologic soil crusts while managing the remainder for optimization of desirable vegetation.
6) Soil loss needs to be reduced by land managers performing aggressive and appropriate land and vegetative treatments.
Desired Future Conditions
Garfield County desires:
a)80% of the soils in Garfield County are producing at least 60% of their capacity.
b)Encroaching Class I conifers are managed to limit their extent to pre-European settlement conditions.
c)Class II and Class III Pinyon/Juniper woodlands are managed to limit their extent to pre-European settlement conditions.
d)Soils are stabilized through vegetative treatments that utilize an optimum combination of native and non-native species.
e)Surface disturbing activities are managed consistent with Garfield County’s Best Management Practices. (See Appendix 2.4.1)
f)A reduction of soil loss on watersheds in Garfield County by performing appropriate land treatments and restoration of desirable sagebrush / semi-desert grassland vegetation communities.
g)Surfaces disturbances are reclaimed in a timely manner during or upon completion of authorized activities, as appropriate.
h)Temporary roads be evaluated to determine if continued use provides a benefit to the public without jeopardizing land health.
i) Fragile soils are identified during preparation of project-level plans, and necessary mitigation measures are developed to allow the project to move forward, while minimizing risks and degradation to soil resources.
Goals, Objectives, Policies & Findings
Goal:80% of the soils in Garfield County are producing a minimum of 50% of their capacity prior to January 1, 2035 and an additional 1% of capacity per year for the succeeding 10 years.
Goal: Encroaching Class I and Class II and Class III Pinyon/Juniper woodlands are managed to limit their extent to pre-European conditions.
Policy: Failure to restore Pinyon/Juniper woodlands to pre-European settlement conditions promotes soil erosion that constitutes non-point source pollution and negatively impacts water quality in Garfield County.
Finding:Consistent with ecological site descriptions, healthy and diverse native and non-native sagebrush / semi-desert grassland communities are the preferred method for stabilizing soils.
Policy: Soil resources are protected when Off Highway Vehicle use is limited to existing or designated OHV routes and 2% to 5% of the County’s federally managed land is available for open OHV use.
Policy:For surface disturbing activities, impacts to soils lasting less than 2 growing seasons are immediate; impacts to soils lasting 2 to 5 years are short term; impacts to soils lasting 6 to 20 years are long term; and impacts to soils lasting more than 20 years are considered permanent. For analysis purposes, the duration of impacts shall be measured from the date of disturbance to date designated reclamation actions are substantially complete, measured on an acre by acre basis.
Policy: Impacts on soils from surface disturbing activities will be minimized and mitigated by appropriate implementation of Garfield County’s Best Management Practices found in Appendix 2.4.1.
Policy: In order to soil loss in watersheds and improve water quality, land managers must perform appropriate land and vegetation treatments in accordance with the following priorities:
- Bare Ground
- Class III Pinyon/Juniper Woodlands
- Class II Pinyon/Juniper Woodlands
- Noxious and undesirable invasive weeds
- Class I Encroaching Conifers and Decadent Vegetative Communities
Policy: Surfaces disturbances shall reclaimed, as appropriate, in a timely manner during or upon completion of authorized activities unless otherwise approved by the Garfield County Commission
Policy: Temporary roads shall be evaluated on a case by case basis to see if a public benefit can be derived by leaving the road open without jeopardizing land health. Temporary roads may be closed upon completion of a project if it is determined soil resources will be degraded and no public benefit is derived from leaving the road open.
Policy: Where fragile soils are identified during preparation of project-level plans, necessary mitigation measures shall be developed to allow the project to move forward, while minimizing risks and degradation to soil resources.
Policy: Site -specific restrictions and/or mitigations for activities proposed infragile soil areas shall be implemented on a case-by-case basis and only where permanent degradation of soil resources will occur without appropriate restrictions or mitigations. Surface disturbing activities shall be allowed in fragile soil areas as long as impacts will be mitigated ordisturbance will be beneficial to land health. Land treatments (i.e., vegetation treatment and soil stabilization) shall be allowed in fragile soils where such treatment would reduce erosion and restore watersheds.
Policy: Land managers shall preclude open and cross-country OHV use in areas identified as fragile soils by designating 2% to 5% of their lands in suitable soils for open OHV use and by authorizing OHV use on existing and designated trails consistent with Garfield County’s Transportation and OHV management plan.
Policy: Land managers shall implement agency standards for land health to maintain orimprove soil conditions until such time that more effective standards are developed.
Policy: Land managers shall incorporate Best Management Practices (BMPs) and soil protection measures into developments on sensitive soils and on lands occupied by Class II and Class III Pinyon/Juniper woodlands. Measuresto stabilize soils and minimize surface water runoff are required for slopes greater than 33 percent and in areas where runoff from Class II and Class III Pinyon/Juniper woodlands is contributing water quality degradation.
Finding: Biologic soil crusts are living, renewable resources that are pervasive on lands where they are located. Individual developmental stages may be sensitive to surface disturbance and may take considerable time to reach maturity, but the basic life forms are resilient and are prone to restoration when environmental conditions are favorable.
Finding: Biologic soil crusts are inversely related to and competing interests with vegetative cover.
Policy: When competing management decisions must be made between vascular plants and biologic soil crusts, land managers shall not designate more than 0.1% of their lands for management options preferring soil crusts over vascular plants.
References
Biological Soil Crusts: Ecology and Management,Technical reference 1730-2, USDI Bureau of Land Management & U.S. Geological Survey, 2001