soils
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Soils. Soils are the result of weathering Mechanical Chemical Critical resources for food, timber, textiles... Waste filters Understanding soils is important for land-use planning, and engineering. Idealized soil profile from a humid climate at middle latitudes. Zone of Leaching. - PowerPoint PPT PresentationTRANSCRIPT
SoilsSoilsSoils are the result of weatheringSoils are the result of weathering
MechanicalMechanical ChemicalChemical
Critical resources for food, timber, Critical resources for food, timber, textiles...textiles...
Waste filtersWaste filters Understanding soils is important for Understanding soils is important for
land-use planning, and engineeringland-use planning, and engineering
Idealized soil profile from a humid climate at middle latitudes
Zon
e of
Lea
chin
g
Horizon Development and Horizon Development and Climate Climate
Soil textural classesSoil textural classes
Topsoil ecosystem Topsoil ecosystem in a temperate in a temperate climateclimate
Porosity and PermeabilityPorosity and Permeability
Water Water saturation saturation and air spaceand air space
Nutrients to Nutrients to plant rootsplant roots
The Water TableThe Water Table
The level The level below which below which the soil is the soil is saturated saturated with water with water (no air space)(no air space)
Soil waterSoil water
Representative Representative water budgetswater budgets
Deficiencies can Deficiencies can be remedied by be remedied by
storage andstorage and irrigationirrigation
Effect of climate on soil developmentEffect of climate on soil development
The Principal Soil TypesThe Principal Soil Types
Effect of climate on soil typesEffect of climate on soil types
tundra soils
Precipitation
Tem
pera
ture
cold
hot hot
coollow high50 cm/yr
pedalferspedocals
laterites
tundra soils
Principal soil types in the USAPrincipal soil types in the USA
Effect of climate on soil typesEffect of climate on soil types
A typical pedocal with A typical pedocal with white white calichecaliche (CaCO (CaCO33) )
deposits in a shallow B deposits in a shallow B horizonhorizon
Effect of climate on soilsEffect of climate on soils
Making Making laterite laterite bricksbricks
Temple at Temple at Angkor Angkor
Wat Wat CambodiaCambodia
(700 yrs (700 yrs old)old)
Laterite
Tundra soil
A Newer A Newer Classification Classification of Soil Typesof Soil Types
Pf
Pc
Pf
Pf, Pc
L
Pf, L
Rates of soil formation:Rates of soil formation:
Central USA: ~ 1 cm/100 years in very porous Central USA: ~ 1 cm/100 years in very porous and permeable rockand permeable rock
Humid N. Carolina: ~ 1 cm/5 yearsHumid N. Carolina: ~ 1 cm/5 years““
Granite may require over 1000 years for a cmGranite may require over 1000 years for a cm
Universal Soil Loss Equation Universal Soil Loss Equation A = RKLSCPA = RKLSCP
A = long-term average annual soil loss for siteA = long-term average annual soil loss for site R = long-term rainfall runoff erosion factorR = long-term rainfall runoff erosion factor K = soil erodibility indexK = soil erodibility index L = hill slope/length factorL = hill slope/length factor S = hill slope gradient (slope) factorS = hill slope gradient (slope) factor C = soil cover factorC = soil cover factor
P = erosion-control practice factorP = erosion-control practice factor
Both Ends of the Erosion ProblemBoth Ends of the Erosion Problem
Serious Serious soil erosionsoil erosion and gully and gully formation related to diversion of formation related to diversion of water runoff over a few months water runoff over a few months in central Californiain central California Sediment pollutionSediment pollution following following
heavy rains in North Carolinaheavy rains in North Carolina
Soil DegradationSoil Degradation ErosionErosion DeforestationDeforestation Agricultural depletionAgricultural depletion Contamination - PollutionContamination - Pollution
SalinizationSalinization PesticidesPesticides Chemical additions and spillsChemical additions and spills
UrbanizationUrbanization DesertificationDesertification OvergrazingOvergrazing
Raindrop impact: Raindrop impact: millions in a single millions in a single shower hit at ~ 30 mphshower hit at ~ 30 mph
Soil ErosionSoil Erosion
Rill-wash and gullying in loose Rill-wash and gullying in loose and poorly-consolidated soilsand poorly-consolidated soils
Soil ErosionSoil Erosion
Soil Lost (tons/km2/yr) % runoffWoods ~ 0 0.12Grass 10 6.5Corn 18087 42Fallow 17050 49
Soil Erosion for Various Uses
Soil ErosionSoil Erosion
Number of dust storms during the month of March, 1936Number of dust storms during the month of March, 1936
Soil ErosionSoil Erosion
Effects of logging in MadagasgarEffects of logging in Madagasgar
Soil ErosionSoil Erosion
Figure 3.12:Figure 3.12: (a) a natural forested slope(a) a natural forested slope(b) the same slope following a clearcut(b) the same slope following a clearcut
Soil ErosionSoil Erosion
Figure 3.12:Figure 3.12: (c) the same slope after conversion to farmland(c) the same slope after conversion to farmland(b) the same slope following urbanization(b) the same slope following urbanization
Soil ErosionSoil Erosion
Soil ErosionSoil Erosion
1968 motorcycles 1968 motorcycles first come to Deer first come to Deer
Creek near Creek near Bakersfield, CABakersfield, CA
1972 after only 4 1972 after only 4 years of ORV use years of ORV use little vegetation or little vegetation or
topsoil remainstopsoil remains
Soil ErosionSoil ErosionORV users increased ORV users increased from 21 to 38 million from 21 to 38 million
between 1982 and 1992between 1982 and 1992
ATVs rip through a marsh in ATVs rip through a marsh in West VirginiaWest Virginia
Great Grizzly Hike, MontanaGreat Grizzly Hike, Montana
Soil ErosionSoil Erosion
1985 photo of bulldozer and jeep tracks in 1985 photo of bulldozer and jeep tracks in Alaskan tundra made in 1946Alaskan tundra made in 1946
Soil ErosionSoil Erosion
Salt accumulation due to irrigation in Salt accumulation due to irrigation in an arid climate: San Fernando Valleyan arid climate: San Fernando Valley
Worldwide Distribution of Salt-affected SoilsWorldwide Distribution of Salt-affected Soils
Chemical Contamination of SoilsChemical Contamination of Soils
Grain production Grain production levels off while levels off while population population continues to growcontinues to grow
Cleaning Up Chemical ContaminationCleaning Up Chemical Contamination
Combating Soil Combating Soil DegradationDegradation
Combating Soil DegradationCombating Soil Degradation
Strip-croppingStrip-croppingand and
Contour plowingContour plowing
Combating Soil DegradationCombating Soil Degradation
Rice terraces in Rice terraces in AsiaAsia
Combating Soil DegradationCombating Soil Degradation
No-tillNo-tillFarmingFarming
Combating Soil DegradationCombating Soil Degradation
Soil Surveys and Adequate Soil Surveys and Adequate PlanningPlanning