安师大环境土壤学讲义14土壤退化与土壤质量.docx

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1、14土壤退化与土壤质量14. Soi1DegradationandSoi1Qua1ity目的要求：使学生了解土壤退化的概念、种类与退化的背景、态势；掌握土壤质量的内涵与其评价指标体系与方法；了解土壤退化的类型与防治。14.1 Initia1conceptsandtypesofsoi1degradation土壤退化的概念及分类14.1.1 Initia1conceptsofsoi1degradation土壤退化的概念土地（壤）退化指的是数量减少和质量降低。数量减少可以表现为表土丧失，或整个土体的毁失，或土地被非农业占用。质量降低表现在土壤物理、化学、生物学方面的质量下降。（1）土壤（地）退化是一

2、个非常复杂的问题，它是由自然因素和人为因素共同作用的结果。（2） 土壤（地）资源从数量上是无再生能力的，因而具有土壤（地）数量有限性的特点，但从质量上，可以改良培肥土壤，保持“地力常新”。耕地土壤是人类赖以生存最珍贵的土壤（地）资源，是农业生产最基本的生产资料。1. 1anddegradationandsoi1degradation土地退化与土壤退化 1anddegradation土地退化是指人类对土地的不合理开发利用而导致土地质量下降乃至荒芜的过程。包括森林的破坏及衰亡、草地退化、水资源恶化与土壤退化。土地退化的直接后果是：直接破坏陆地生态系统的平衡及其生产力；破坏自然景观及人类生存环境；通

3、过水分和能量的平衡与循环的交替演化诱发区域乃至全球的土被破坏、水系萎缩、森林衰亡和气候变化 Soi1degradation土壤退化在自然环境的基础上，因人类开发利用不当而加速的土壤质量和生产力下降的现象和过程。土壤退化的标志：对农业而言：土壤肥力和生产力的下降；对环境而言：土壤质量的下降14.1. 2Typesofsoi1degradation土壤退化的分类城镇化占地土壤面积萎“工矿土壤剥离不合理利用中废弃与转侈土壤退化土壤性质恶化物质损失喉:蓝与沙漠化J土壤贫瘠化过程干扰型土壤板结化土塘酸化、盐渍化、潜育化I土壤农药污染环境污染成土康重金属污染I土壤放射性污染联合国粮农组织(FAO)侵蚀盐碱

4、有机废料传染性生物工业无机废料农药放射性重金属肥料洗涤剂旱涝障碍土壤养分亏缺耕地非农业占用14. 2Backgroundandgenera1trendofsoi1degradationinChina我国土壤退化的背景与基本态势我国土壤退化的自然社会条件制约：1 .土壤(地)资源短缺，空间分布不均(1)人均土壤资源占有率低(2) 土地资源空间分布不均匀，区域开发压力大(3)生态脆弱区，范围大(4)耕地土壤质量总体较差，自维持能力弱2 .人口增长与社会经济发展对土壤退化的制约3 .水资源短缺对土壤退化的制约我国土壤退化的现状与态势：1土壤退化的面积广，强度大，类型多2.土壤退化的发展快、影响深远1

5、4.3 Soi1DegradationandContro1土壤退化与防治14.3.1 Basicconcepts14.3.1.1 Soi1degradationSoi1degradationhasbeendefinedasthedec1ineinsoi1qua1itycausedthroughitsmisusebyhumanactivity.Morespecifica11y,itreferstothedec1ineinsoi1productivitythroughadversechangesinnutrientstatus,organicmatter,structura1stabi1ityan

6、dconcentrationsofe1ectro1ytesandtoxicchemica1s(1a1andStewart,1990).土壤退化在自然环境的基础上，因人类开发利用不当而导致的土壤质量及生产力下降的现象和过程。Archaeo1ogica1evidencesuggeststhatsoi1degradationhasbeenon-goingsincethebeginningofsett1edagricu1turesevera1thousandyearsago.Thedec1ineofmanyancientcivi1isations,inc1udingtheMesopotamiansof

7、theTigrisandEuphratesva11eysinIraq,theHarappansoftheIndusva11eyinPakistanandtheMayansofCentra1America,wasdueinparttosoi1degradation(O1son,1981).Morerecent1y,aneventofmajorsignificancewasthedustbow1whichoccurredintheGreatP1ainsoftheAmericanmidwestduringthe1930s.14.3.1.2 Inf1uencedfactorsTheextentofso

8、i1degradationisinf1uencedbyanumberoffactorsinc1udingsoi1characteristics,topography,c1imate,1anduse,andsocio-economicandpo1itica1contro1s.影响因素：自然因素、人为因素AccordingtotheG1oba1AssessmentofSoi1Degradationproject,about15percentoftheg1oba11andareabetween72oNand57oSisstrong1ydegraded(Ayoub,1991),1arge1yasare

9、su1tofdeforestation,inappropriateofcropped1andandovergrazing.Inrecentdecadestheg1oba1rateofsoi1degradationhasincreaseddramatica11y,andis1ike1ytoincreasefurtherasweapproachthe21thcenturyo14.3.1.3 Tpesofsoi1degradation土壤侵蚀Erosion土壤沙化Desertication土壤盐渍化Sa1inasation土壤碱化Sodification土壤酸化Acidification土壤潜育化G

10、1eyizationSoi1degradationincorporatesanumberofenvironmenta1prob1ems,someofwhichareinterre1ated,inc1udingerosion,compaction,waterexcessanddeficit,acidification,Sa1inisationandSodification,andtoxicaccumu1ationofagricu1tura1chemica1sandurban/industria1po11utants.Inmanyinstances,thesehave1edtoaseriousde

11、c1ineinsoi1qua1ityandproductivity.Theeffectsofsoi1degradationarenotrestrictedtothesoi1a1one,buthaveanumberofoff-siteimp1ications.Soi1erosionisoftenassociatedwithincreasedincidenceoff1ooding,si1tationofrivers,1akesandreservoirs,anddespositionofmateria1in1ow-1yingareas.Soi1acidificationiscommon1y1inke

12、dwithacidificationanda1uminiumcontaminationofsurfacewater.Sa1inisationandSodificationofsoi1areoftenassociatedwithpoorqua1ityirrigationwater.Contaminationofsoi1sbyurbanandindustria1po11utants,suchasheavymeta1sandradionuc1ides,may1edtotoxicaccumu1ationinarab1eproduceandinherbageforgrazinganima1s,thush

13、avingimportantimp1icationsforhuman14.3.1.4 Managementofsoi1degradationWhetheratag1oba1,regiona1or1oca1sca1e,managementofsoi1degradationisc1ear1yacomp1exissueandrepresentsoneofourmostcha11engingenvironmenta1prob1ems.Emphasisshou1dbep1acedonsustainab1eratherthanexp1oitative1andusepractices.Managemento

14、fsoi1degradationrequiresaho1istic,mu1tidiscip1inaryapproachinvo1vingagronomists,soi1scientists,engineers,socio1ogists,economists,po1iticians,andmostimportant1y,the1andusersthemse1ves.Theapproachtosoi1conservationhasshiftedinrecentyearsfromarathertechnocentricstandpointtoamoreecocentricposition.Centr

15、a1tothisapproacharetheconceptsof1andhusbandryandsustainab1edeve1opment.14.3.2 ErosionSoi1erosionoccurswhentherateofremova1ofsoi1bywaterand/orwindexceedstherateofsoi1formation(1cm/100-400years,=0.3-1.3thaa,FAO).Itisimportanttodifferentiatebetweennatura1orbackgrounderosion,anderosionwhichhasbeenacce1erated1arge1yasaresu1tofhumanactivity.Backgrounderosionratesareoftensimi1artoratesofsoi1formationat200thaa,1oessp1ateauareaofChinaHima1ayanfoothi11sofNepa114.3.2.1 Thecausa1factorsTheextentofsoi1er