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1、第六章土壤微量元素Chapter6MicronutrientsinSoil高等植物必需的营养元素（16+1或+2）C,H,O,N,P,K,Ca,Mg,S,Cu,Zn,Mn,Fe,B,Mo,CI,Ni，Co大量元素微量元素Otherelements,suchassilicon(Si),vanadium(V),andsodium(Na),appearstoimprovethegrowthofatleastcertainplantspecies.Animals,includinghumans,alsorequiresmostiodine(I),and
2、fluorine(F),havebeenshowntobeessentialforanimalgrowthbutareapparentlynotrequiredbyplants.Intensiveplantproductionpracticeshaveincreasedcropyields,resultingingreaterremovalofmicronutrientsfromsoils.Thetrendtowardhigh-analysisfertilizershasreducedtheuseofimpuresaltsandorganicm
3、anures,whichformerlysuppliedsignificantamountsofmicronutrients.Increasedknowledgeofplantnutritionandimprovedmethodsofanalysisinthelaboratoryarehelpinginthediagnosisofmicronutrientdeficienciesthatmightformerlyhavegoneunnoticed.Increasingevidenceindicatesthatfoodgrownonsoilswi
4、thlowlevelsoftraceelementsmayprovideinsufficienthumandietarylevelsofcertainelements,eventhoughthecropplantsshownosignsofdeficiencythemselves.为何微量元素营养问题越来越重要？Theextentofmicronutrient-deficientsoilsarecomparabletothatofnitrogen-,phosphorus-,andpotassium-deficientsoils.Summaryd
5、ata(Table1)fromanextensiveeffortthatexamined190soilsamplesfrom15countriesrevealedthat49%ofthesesoilswerelowinzincand31%lowinboron(Sillanpaa,1990).Today,thereareover3.7billioniron-deficientindividualsandabout1billionpeoplethatareorareatriskofdevelopingiodinedeficiencydisorder
6、s.Additionally,thereareover200millionpeoplethatarevitaminAdeficient(WorldHealthOrganization,1999).Othermicronutrientdeficiencies(e.g.,Zn,Se,vitaminC,vitaminD,andfolicaciddeficiencies)maybeaswidespreadasiron,iodineandvitaminAdeficiencies,buttherearenoreliabledatatoconfirmthis
7、althoughcircumstantialevidencesuggeststhatthismaybeso(Combsetal.,1996;WorldHealthOrganization,1999).WelchRM.Theimpactofmineralnutrientsinfoodcropsonglobalhumanhealth.PlantandSoil247:83–90,2002.对人体健康的影响？Figure1.GlobaldistributionofFe,vitaminAandIdeficiencies(mapmodifiedfromSa
8、nghvi,1996).Toxicityofsomemicronutrientinsoils.Expandinginterestsinthefield
