Soil Aggregate Stability(13)

土壤团聚体的经典文章

94JOURNALOFSUSTAINABLEAGRICULTURE

organicElliott,matteratdifferentsoilaggregatesizefractions(Christensen,1993;PugetAngers1986;etGuptaal.,andGermida,1988;CambardellaandElliott,1986;1992,fractionsetal.,Hassink,ofsoil1995)1993a,1995;Schultenetal.,1993;Beareetal.,1994b;organicaswellmatterasthedecompositionratesofsizeanddensityeffectgates,of1995).organicInmatteraddition,istosome(Golchinformauthorsetal.,1994;Golchinetal.,1995;ahydrophobichavereportedcoatingthatanotherpositivequentlyreducingsoilwettability,slowingdownthewettingaroundrate,andtheaggre-conse-van,Caron1990;reducingBlackman,thesensitivity1992;ZhangtoslakingandHartge,(Mbagwu1992,andcitedPiccolo,inZhang,1989;Sulli-anisms:Theet1994;dispersiveal.,1996).

negatively(1)theblockingeffectoforganicmatteristheresultofthefollowingmech-ionsofadsorbedbyorganicchargedorganicmatter,organicofpolymerand(3)anions,positivelylayersthesteric(2)thechargededgesofclaymineralsby(HeilrepulsioncomplexationandSposito,resultingof1993a,frompolyvalentcat-b).theoverlapFeandAlOxides

controversyTheinfluenceofsesquioxidesonsoilaggregationisstillamatterofEl-Swaify(1985),1990,Chiangandinliterature.Emersonetal.(1987),(1975),McNealandColeman(1966),McNealetal.(1968),ShainbergEl-Swaifyetal.(1976),(1987),DuPlessisandShainberg(1996)1991),Goldbergetal.(1990)andPinheiro-DickKerenandandSchwertmannSinger(1989,areandverystatedthatsoilshavingahighcontentofironandaluminumoxidesnegligible.Bartolistable.ity,Thisetal.However,Borggaard(1983,citedinvanDenBroek,1989)apparent(1991)contradictionshowedthatistheirrelatedeffectonaggregatestabilityisasmainlytoparticlethelevelsizeatandwhichdistributionoxidesact.oftheTheoxidemajor(vantoDenthevariationBroek,1989),incrystallin-aswellswelling.onsoilmicro-aggregation,andbasicallyeffectlimitingoftheseclaydispersioncompoundsismechanisms:Thequioxides(1)stabilizingironandeffectofthesesquioxidesarethroughdifferentandcanbindclayparticlesaluminumtotheinsolutionactasflocculants,(2)ses-(1976),Elprecipitateorganicmolecules,and(3)sesquioxidesRayahandasgelsonclaysurfaces.

KerenFrenkelandRowellShainberg(1973),(1980),El-SwaifyGoldbergandEmerson,and(1975),El-SwaifyeffectiveandSinger(1989,1990)establishthataluminumGlaubigpolymers(1987),aremoreandaluminumin(GoldbergaandpolymersaggregatingGlaubig,isduethanironpolymers.Thehigherefficiencyofthe1987,toand(1)Kerentheirhigherpointofzerocharge(pzc)tionhigherforces;chargeanddensity,(2)theplanarandconsequentlyandshapeofthetoSinger,Alstronger1989,precipitates,clay-polymers1990),leadingtodifferingattrac-tothe

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