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Ecology Lecture 3Ecology Lecture 3
Ralph KirbyRalph Kirby
What is soilWhat is soil
Before life invaded the land from the sea, there Before life invaded the land from the sea, there was probably little that looked like soil todaywas probably little that looked like soil today Dust like MarsDust like Mars Little organic matterLittle organic matter A few microorganisms perhapsA few microorganisms perhaps
However, soil is the basis of all terrestrial life and However, soil is the basis of all terrestrial life and without soil, there would be no plants, no soil without soil, there would be no plants, no soil microorganism and no land animalsmicroorganism and no land animalsPlants obtain many of their water and nutrients Plants obtain many of their water and nutrients from soil and it provides an place to attach to.from soil and it provides an place to attach to.
Definition of soilDefinition of soil
Soil is hard to define because it is so complexSoil is hard to define because it is so complex Soil is a natural product formed by the weathering of Soil is a natural product formed by the weathering of
rocks and the action of living organismrocks and the action of living organismDoes it include the ability to support lifeDoes it include the ability to support life
Soil is a collection of mineral and organic matter than Soil is a collection of mineral and organic matter than can support plant growthcan support plant growth
Does this include soil like material that does not support lifeDoes this include soil like material that does not support life
What if the climate at present does not support lifeWhat if the climate at present does not support life The stratum below vegetation and above hard rockThe stratum below vegetation and above hard rock
What if there is no vegetationWhat if there is no vegetation
Three dimensional matrixThree dimensional matrixSoil is a living system made up of a matrix Soil is a living system made up of a matrix of minerals and organic matter that includesof minerals and organic matter that includes plants, both roots and stemsplants, both roots and stems BacteriaBacteria FungiFungi ProtozoaProtozoa AlgaeAlgae Small animalsSmall animals Larger animalsLarger animals
A unit of soil large enough to define is A unit of soil large enough to define is calledcalled PedonPedon
Formation of soilFormation of soilProposed that five factors are involved in the formation of soilProposed that five factors are involved in the formation of soil
Parent MaterialParent MaterialIgneous rockIgneous rockSedimentary rockSedimentary rockMetamorphic rockMetamorphic rock
ClimateClimateTemperatureTemperatureRainfallRainfallElevationElevationLatitudeLatitude
Biotic FactorsBiotic FactorsInput factors from living organismsInput factors from living organismsDegradation by living organismsDegradation by living organisms
TopographyTopographyWater runoffWater runoffDrainingDrainingErosionErosion
TimeTimeWeathering, accumulation, decomposition and mineralization take timeWeathering, accumulation, decomposition and mineralization take timeInitial differentiation can be within 30 yearsInitial differentiation can be within 30 yearsFormation of true soil, 2000 to 20000 yearsFormation of true soil, 2000 to 20000 yearsSoil can ageSoil can age
Mechanical and Chemical WeatheringMechanical and Chemical Weathering Starting PointStarting Point
MechanicalMechanical WaterWater WindWind TemperatureTemperature Creates loose materialCreates loose material Sorted and movedSorted and moved
ChemicalChemical Acids produced by lichens and mossesAcids produced by lichens and mosses Addition of organic matterAddition of organic matter OxidizationOxidization etcetc
Living OrganismsLiving OrganismsWithout living organism there would be no soilWithout living organism there would be no soil Mars does not have soil as we know itMars does not have soil as we know it When plants colonized the land, they changed it by When plants colonized the land, they changed it by
producing soilproducing soil Plants introduce organic matter to soilPlants introduce organic matter to soil Microorganisms and small animals recycle the Microorganisms and small animals recycle the
organic matter to humusorganic matter to humus Humus can be on top of soil in some acidic Humus can be on top of soil in some acidic
environmentsenvironments Humus is usually mixed with the soil and changes it Humus is usually mixed with the soil and changes it
compositioncomposition Many microorganisms have evolved to fill this nicheMany microorganisms have evolved to fill this niche
ActinomycetalesActinomycetalesLignin degrading fungiLignin degrading fungi
Soil has many Soil has many layerslayers
OOOrganic layerOrganic layer
Fluctuates with seasonFluctuates with season
AAUpper layer of mineralized Upper layer of mineralized soilsoil
Large amount of organic Large amount of organic mattermatter
EEEluvial zoneEluvial zone
Maximum leachingMaximum leaching
BBIlluvial zoneIlluvial zone
Accumates leached Accumates leached material such as clays, material such as clays, silicates, etcsilicates, etc
CCUnweathered starting Unweathered starting materialmaterial
RRRock or parent materialRock or parent material
Soils show a great deal of Soils show a great deal of variationvariation
ColorColor No direct effect on how No direct effect on how
soil functionsoil function Allows classificationAllows classification
RedRed Possibly oxidesPossibly oxides
BlackBlack Possible high organic Possible high organic
contentcontent
TextureTexture Variation in size and Variation in size and
shape of soil particlesshape of soil particlesGravelGravel
>2mm>2mm
SandSand 0.05mm to 2mm0.05mm to 2mm
SiltSilt 0.002mm to 0.05mm0.002mm to 0.05mm
ClayClay <0.002mm<0.002mm
StructureStructure Space for roots etcSpace for roots etc Pore spacePore space
Amount of water heldAmount of water heldRate of water movementRate of water movementAerationAerationCompactionCompactionAggregationAggregation
Aggegates or pedsAggegates or peds
DepthDepth Depends onDepends on
SlopeSlopeWeatheringWeatheringParent materialParent materialVegetationVegetation
Grasslands are deepGrasslands are deep Forests are shallowForests are shallow
Water is essential for soilsWater is essential for soils
See lack (?) of water on MarsSee lack (?) of water on MarsSoil can become saturated if all Soil can become saturated if all pores filledpores filled
Normally at field capacityNormally at field capacityCapillary water is usually Capillary water is usually presentpresent
Extracted by plantsExtracted by plants Available water capacityAvailable water capacity Hygroscopic water unavailableHygroscopic water unavailable
DrainageDrainage Low drainage results in low Low drainage results in low
aerationaerationAll affected by soil textureAll affected by soil texture
Sand Sand Lower capacityLower capacity
ClaysClaysHigher capacityHigher capacity
Plants need minerals in the form of Plants need minerals in the form of ionsions
Cationic exchange resin Cationic exchange resin type structuretype structureChange in pH affects Change in pH affects binding capacity for ionsbinding capacity for ions ImmovableImmovable
HydrogenHydrogenAluminiumAluminium
Removable in orderRemovable in orderCalciumCalciumMagnesiumMagnesiumPotassiumPotassiumAmmoniumAmmoniumSodiumSodium
Soils vary with climate and vegetationSoils vary with climate and vegetation
EntrisolEntrisol MountainsMountains Where soil making process has Where soil making process has
been interupted by flooding etcbeen interupted by flooding etcInceptisolInceptisol
Mineral rich mountain soilMineral rich mountain soil Forests and pastureForests and pasture
AridisolAridisol Arid regionsArid regions Low in humusLow in humus Salinization due to low rainfallSalinization due to low rainfall
AndisolAndisol Volcanic in originVolcanic in origin Can be very fertileCan be very fertile
MollisolMollisol Dark organic rich A layerDark organic rich A layer Deep fertile Deep fertile
SpodosolSpodosol AcidicAcidic Coniferous forest soilConiferous forest soil
AlfisolAlfisol Temperate forestTemperate forest Organically richOrganically rich
UltisolUltisol Warm climate soilWarm climate soil Redish or yellowishRedish or yellowish Low nutriant contentLow nutriant content
OxisolOxisol Wet subtropical/tropical soil\Wet subtropical/tropical soil\ Lots of water movement through Lots of water movement through
soilsoil Low nutrientsLow nutrients
HistosolHistosol High water tableHigh water table Poor drainagePoor drainage PeatlandsPeatlands
GelisolGelisol PermafrostPermafrost
VertisolVertisol High % clayHigh % clay No B horizonNo B horizon Swell and shrinkSwell and shrink PasturePasture
Soil forms a biotic ecosystem on its ownSoil forms a biotic ecosystem on its own
Biotic System in soilBiotic System in soilNeedsNeeds
Living spaceLiving spaceVaries with soil typeVaries with soil type
OxygenOxygenVaries with water saturationVaries with water saturation
FoodFoodVaries with plant coverVaries with plant cover
WaterWaterCan vary with climateCan vary with climate
Environment is relatively constantEnvironment is relatively constant Water can change dramaticallyWater can change dramatically Mechanisms to survive droughtMechanisms to survive drought
Spores etcSpores etc
Only upper layer is really availableOnly upper layer is really availableDiversity is Diversity is very veryvery very large largeThe ecosystem is largely not understood in detailThe ecosystem is largely not understood in detail
Particularly the microorganismsParticularly the microorganisms
Man has an effect on soilMan has an effect on soil
Changes in plant coverChanges in plant cover EnglandEngland
1000 BC1000 BC ForestForest
20042004 Cities, towns, villages, farm land, monoculture forestsCities, towns, villages, farm land, monoculture forests
ErosionErosion Deforestation in AfricaDeforestation in Africa
Climate changeClimate change
DamsDams
Roads and storm drainsRoads and storm drains