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简介：AfieldexperimentwasconductedtostudytheeffectsofPb,Cd,Cu,ZnandAscoexistinginredsoilongrowthofrice(OryzasativaL.)mungbean(Vignarabiata(Linn.)Wilczek),alfalfa(MedicagosativaL.),Slashpine(PinuselliottiiEngelm.)andaspen(PopulusL.).Resultsshowedthatrice,mungbeanandalfalfaweresignificantlyinfluencedbycombinedpoollutionoftheheavymetals,thecontentsofPb,CdandAsinricegrainsgreatlyexceededtheNationalStandardsforFoodHygieneofChina.Heavymetalsatahighconcentrationseriouslyretardedgrowthofmungbeanandalfalfa,butnotsoobviouslywithslashpineandaspen.Thecompositeindexissuggestedforevaluatingtherelativityofcombinedpollutionwithheavymetalsinsoil.

简介：Potexperimentsandfieldtrialswereconductedtoinvestigatethechangesintrichloroaceticacid(TCA)solublesilicon(Si)intheleavesofrice(OryzasativaL.)andtoexaminethefeasibilityofusingTCA-solubleSicontentasanindexfordiagnosingSideficiency,TheTCA-solubleSicontentwassignificantlyhigherintheleavesofbothSi-treatedand-untreatedriceattheelongationstagecomparedwiththatattilleringstage,ItwashigherintheSi-treatedplantsthaninthecontrolsthroughoutthewholegrowthperiod.However,whetherdressedatelongationorbootinstage,siliconfertilzerresultedinasignificantincreaseinTCA-solubleSioneweektotendaysafterapplication,ThesamewastrueforthetotalSiaccumulationintheplants.AcolsepositiviecorrelationwafoundbetweenTCA-solubleSiandtotalSiinPlantsgrownonpotsoils(r=0.669,P<0.01,n=26).TheresultsobtainedinthefieldtrialsrevealedthattheavailableSiextrctedbysodiumacetate(pH4.0)couldnotpreicttheresponseofricetoaddedSiinthecalcareoussoilssatisfactorily.NosignificancorrelationwasfoundbetweensoilavailableSicontentandriceyield,butTCA-solubleSiintheleafbladesofricewassignificantlycoorelatedbothwithriceyield(r=0.57,P<0.01,n=30)andwithtotalplantSi(r=089,P<0.01,n=30),Inisrecommendedthat,whth95percentconfidence,thecriticalvalueofTCA-solubleSiintheleavesofriceshouldbe52-57mgSikg^-1,abovewhichnopositiveresponseofricetoaddedSiwouldbeexpected.

简介：Assessmentofsoilqualityisimportantforoptimumproductionandnaturalresourcesconservation.AgriculturalandpasturesoilqualitiesofDeh-SorkhregionlocatedatsouthofMashhad,northeasternIranwereassessedusingtheintegratedqualityindex(IQI)andNemeroqualityindex(NQI)modelsincombinationwithtwodatasets,i.e.,totaldataset(TDS)andminimumdataset(MDS).Inthisstudy6soilpropertiesconsideredasMDSwereselectedoutof18propertiesasTDSusingprinciplecomponentanalysis.Soilsamplesweredividedinto3groupsbasedonoptimumrangesof8soilphysicalqualityindicators.Soilsampleswiththemostindicatorsatoptimumrangewereselectedasgroup1andthesampleshavingfewerindicatorsatoptimumrangewerelocatedingroups2and3.Optimumrangesofsoilporesizedistributionfunctionswerealsodeterminedassoilphysicalqualityindicesbasedon8soilphysicalqualityindicators.Poresizedistributioncurvesofgroup1wereconsideredastheoptimumporesizefunctions.Theresultsshowedthatrelativelyhighorganiccarboncontentscouldimproveporesizedistribution.Meancomparisonsofsoilphysicalqualityindicatorsdemonstratedthatmeanweightdiameterofwetaggregates,structuralstabilityindex,theslopeofmoistureretentioncurveatinflectionpoint,andplantavailablewatercontentinagriculturallandusedecreasedsignificantlyinrelationtopasturelanduse.Inaddition,theresultsdemonstratedthatthestudiedMDScouldbeasuitablerepresentativeofTDS.78%ofpasturesoilshadtheoptimumporesizedistributionfunctions,whilethisparameterforagriculturalsoilswasonly13%.Ingeneral,thesoilsofthestudiedregionshowedhighlimitationsforplantgrowthaccordingtothestudiedindicators.

简介：Soilqualityassessmenthasbeensuggestedasaneffectivetoolforevaluatingsustainabilityofsoilandcropmanagementpractices.Theobjectiveofthisstudywastodevelopasensitivesoilqualityindex(SQI)basedonbulkdensity(BD),water-holdingcapacity(WHC),water-stableaggregates(WSA),aggregatemeanweightdiameter(AMWD),totalorganicC(TOC)andCinputtoevaluatetheimportantrice-wheatcroppingsystemonanInceptisolinIndia.Along-termexperimenthasbeenconductedfor18yearsattheIndianCouncilofAgriculturalResearch-IndianInstituteofFarmingSystemsResearch,Modipuram,India.Thetreatmentsselectedforthisstudywerecomprisedofano-fertilizercontrolandN,PandKfertilizers(NPK)combinedwithZnandSfertilizers(NPK+Zn+S),farmyardmanure(NPK+FYM),greengramresidues(NPK+GR)andcerealresidues(NPK+CR),laidoutinarandomizedcompleteblockdesignwiththreereplications.SoilsampleswerecollectedandanalyzedforBD,WHC,WSAandTOC.Correlationanalysisrevealedthatbothriceandwheatyieldssigni?cantlyincreasedwiththeincreasesinAMWD,TOCandCinput,butdecreasedwiththeincreaseinBD.TheSQIvalueswerethengeneratedbasedonregressionanalysisofBD,WSA,AMWD,TOCandCinputwithriceandwheatyieldsforthe0–15and15–30cmsoillayers,respectively.RegressionanalysesbetweencropyieldsandSQIvaluesshowedaquadratictypeofrelationwiththecoeffcientofdetermination(R~2)varyingfrom0.78to0.89.Withregardtosoilsustainability,applyingcropresiduestobothriceandwheatcouldmaintainsoilqualityforalongerperiod,whereasthehighestyieldsofboththecropswererecordedintheNPK+Zn+Streatment.Theregressionequationsdevelopedinthisstudycouldbeusedtomonitorsoilqualityinasubhumidtropicalrice-wheatcroppingsystem.