Soilisthe naturalbody ofmineral, organicandnutrientconstituents whichresultfromthe interactionof the country rock withthe environmentalfactorsofclimate, topography,plantandanimallife 1. Medium for plant growth. Soiliswhere mostplantsgrow.Soil providesanchorage forthe plantsas wellasprotectionofrootsfrom damage.Itiswhere ora medium throughwhichwater,airand nutrientsare made available to plants.The well-aeratedsoil facilitatesthe absorptionofwater andnutrientsfromthe soilby plants. 2. Soil support animal life. Assoilsupportplantlife italso supportanimallife because plants are the source offoodstoanimals andthisismostforherbivores.Also some animalseatsoilasfoodin formofsaltlicksforexample pregnantwomenwholack some mineralsintheirbodies. 3. Soil provide habitat for living organisms. Inthe soilthere are some animals livingthere example burrowing animalslike rodents,earthworms andtermites 4. Provide sites for agricultural activities. The fertile soilpromotesagriculture activities,bothanimalhusbandry andcropcultivation.Thisisbecause soilsupportsthe growthofpasture foranimals. 5. Provide settlement. Soilinfluencesdistributionof settlementforexample the areas withgoodfertile soilare densely populatedcomparedtothe areas withpoorsoil. 6. Soil provide building materials Soilisusedinmakingbricks,tiles andwhite wash.Allthese materials are usedinbuildinghouses,bridges etc.Alsosoilisuseddirectly inroad construction 7. Source of minerals There are some mineralsfoundin soilthatcanbe extractedfor commercialpurposes.Alsoitisused tomanufacture fertilizersasit containmineralsforexample the fertilizersthatcontainphosphate e.g.InMinjingu(Manyara) region. 8. It provides raw materials for pottery and ceramics. Soilisusedinmakingpotsandthese helptoprovide income tothose who engage inthisactivity. Organicmatter(humus) Inorganicmatters(minerals) Soilwaterandsoilair 1. Organic matter (humus). Thisform 5%ofthe totalvolume andismade upplantandanimalremains. Humusisformedasa resultof decompositionofanimal/plants remains. Itimprovesthe structure ofthe soil Itregulatesthe soil temperature. Itleadstohigheragricultural production. 1. Inorganic matter (minerals). This forms45%oftotalvolume andis made upofmineralsfromthe parentrock.Mineralsconstitute some nutrientsneededby plantsfor growth. 2. Soil water.Thisforms25%ofthe totalvolume.Itisone ofthe importantsoilconstituents.Itis derivedessentially fromrainfall especially frominfiltration;Too muchwaterinthe soilleadsto leachingandhence lossofnutrients. Dark (Black,grey,dark grey and dark brown) Bright(yellow,orange,red, redishbrown) Light(whitish–grey,white) 1. Course sand2 to0.2 mmdiameter 2. Fine sand0.2 to0.02 mmdiameter 3. Silt0.02 to0.00 mmdiameter 4. Clay lessthan0.002 mm 5. Loansoili.e.mixture ofsand,clay andsilt Itinfluencesthe soilporosity, permeability,compaction,and structure Itinfluencesplantgrowth Itinfluence cultivationduring the agriculturalactivities Itinfluencessoilresistance againsterosion Itinfluencessoilfertility Soilhascertaindegree of temperature andthistendto vary fromplace toplace due to the variationinthe climatic conditions.Incoldareaslike Tundra regionssoilisalsocold thisisdue tothe smallamount ofinsolationreceivedthere.In tropicalareassoilare warmdue tohighintensity ofinsolation heatingthe surface. Itdeterminesthe existence of micro-organismsina certain area. Itcontrolsthe amountof moisture inthe soil Soiltexture –The finerthe particlesthe greaterwillbe the totalsurface area.Hence the soilwithfine particleslike clay hasgreaterporosity. Structure ofthe soilalso influencespermeability. Itdetermineswaterretention capacity andaeration Itisanindicatorofsoilfertility orsustainability foragricultural activities Itinfluencesplantgrowthby influencingthe rootpenetration andwaterretention Ithelpsindeterminingthe selectionofcropsand agriculturaldistribution Itaffectsplantgrowthsuchthat where there istoomuchacidity there willbe poorplantgrowth. Thisisbecause the increase of acidity leadstothe increase in leachingwhichaffectssoil structure. Splash erosion causedby movingwaterfromrain,this tendstoremove some ofthe materialsfromone place to another. Sheer erosion whichinvolves the removalofthe uniform coverofthe soilby surface run-offongentle slopes. Rills erosion thatleadstothe formationofsmallchannels calledrillsonthe surface. Gully erosion, thatleadstothe formationofdeeptroughs calledgulliesdue tosevere undercutting River erosion, takesplace in the specificChanel calledriver valley 1. NORMAL GEOLOGICAL EROSION. Lossoffertility whichinturn causesthe reductioninyieldsor totalcropfailure Migrationofpeople fromareas affectedtothe areaswhich have notbeenaffectedby erosion. Overfloodingofthe riversasa resultofthe creationofthe smallchannelsleadingtothe riversystem. Deforestationasa resultofthe deathofplantsdue tothe loss ofsoil Lossofhabitatasa resultof deforestationcausedby the loss ofsoil Soilerosioncanleadand accelerate rock weatheringby exposingthe underlyingrock to the weatheringagentslike temperature Itleadstothe costincurredin duringthe processofconserving the soil,whichhasbeeneroded. Soilerosioncandestroy transportandcommunication systemslike roads,railway lines andtelephone posts Itcanleadtothe destructionof houses,renderingpeople homeless. Whenthe regionisseverely affectedby the soilerosion, where cropproductionis impeded,whenusefulsoilsare carriedaway,the region experiencesshortage offood. Thiscausesfamine and malnutrition.Withinadequate nutritionchildmortality rate goesupandpopulationgrowth isimpeded. Whenthe foundationofexisting buildingsandroadsare eroded. Accessibility toareasismade difficult.Suchareasare isolated intermsofsocialservicessuch ashospitalsandeducation.The generalhealthandwelfare of the people become poorleading toincrease inmortality and loweringofpopulation. Whenlife becomesunbearable inthe ruralareasbecause of severe soilerosion,able-bodied personsespecially menmigrate tourbanareastootherbetter areasinsearchofemployment. Thisreduce populationinthe affectedareasaswellasthe requiredmanpowertodevelop the areas. Afforestation and Reforestation Control of bush fires. Controlled open grazing. Erecting brushwood barriers. Construction of cut-off drains. Constructing of dams and weirs. Use of artificial waterways.