BIOGEOGRAPHY

BIOGEOGRAPHY SYLLABUSGenesis of soils; Classification and distribution of soils; Soil profile; Soil erosion, Degradation and conservation Factors influencing world distribution of plants and animalsProblems of deforestation and conservation measures Social forestry; agro-forestry; Wild life Major gene pool centres. SOIL Soil is a dynamic natural body on the surface of the earth in which plants grow, composed of mineral and organic materials and living forms Genesis of soilsWeathering TranslocationPodzolisationGleyingDesilicationHumidificationHorizonisation

Weathering Physical weatheringChemical weatheringBiological weathering

Physical weathering

Change in temperatureAction of waterAction of windChemical weathering

HydrolysisCarbonationHydrationOxidationReductionBiological weathering

Man and animalsHigher plants and their rootsMicro organism Translocation

LeachingEluviationIlluviationCalcificationSalinisationAlkalisation

Podzolisation or cheluviationGleying

Desilication

Humidification

Factors influencing soil formation S = f(CL,O,R,P,T)Active soil forming factors Climate Organism Passive soil forming factors Parent materialTopographyTime

Soil profile The vertical section of the soil showing the various layers from the surface to the unaffected parent material is known as a soil profile.Soil profile

Theregolithincludes all of the weathered material within the profile. The regolith has two components: thesolumand thesaprolite.

The solum includes the upper horizons with the most weathered portion of the profile. The saprolite is the least weathered portion that lies directly above the solid, consolidated bedrock but beneath the regolith.Soil erosion, Degradation and conservationSoil erosion soil erosion is the process of detachment and transportation of soil particle by natural agents like water and windFactors responsible for soil erosion

Climate Topographic factorsLithological factors Natural factorsSoil FactorsAnthropogenic factors

Causes of soil erosionDeforestationOvergrazing Faulty agricultural practicesTypes of soil erosionNatural erosionAccelerated erosionGeological erosionWater erosion Splash erosionSheet erosion Rill erosionGully erosion

Soil degradation Soil degradationis the decline insoilquality caused by its improper use, usually for agricultural, pastural, industrial or urban purposes.Soil degradationis a serious global environmental problem and may be exacerbated by climate change. It encompasses physical, chemical and biological deteriorationCause DeforestationOver grazingUse of agrochemicals

IMPACTS Loss of arable landPollutionFloodingLoss of organic matter Decline in soil fertility Decline in structural condition Erosion Adverse changes in salinity, acidity or alkalinityEffects of toxic chemicals.CONSERVATION MEASURE MechanicalBiologicalAgronomical Mechanical measuresContour bundingBench terracingContour stone wallBasin listingPan breaking

Biological measure AfforestrationReforestrationVermicompost

Agronomical measureProper land useContour farmingStrip croppingCrop rotationMixed croppingCover cropsTillageMulchingOrganic manureWind brrakers Classification and Distribution of SoilsMethods of classificationEmprical GeneticTypes of classificationMasbut and Dukuchaiev Classification USDA classification

Masbut and Dukuchaiev Classification

Zonal soilsIntra zonal soilsAzonal soilsZonal soilsPodzols Tundra soilsBrown soilsCherozem /prraire soilsSierozems soilsGrumusolsFerralsols/latosols

Intrazonal soilsHydromorphicCalcimorphicHalomorphic

Azonal soilsRegosols Lithosols Criticisms of Masbut soil classificationUSDA CLASSIFICATION Entisols VertisolsInceptisolsAridisolsMollisolsSpodosolsAlfisolsUltisolsOxisolsHistosols