简介：Asimplemethodwasdevelopedtorelatesoilsorptivitytohydraulicdiffusivityandwaterabsorptionexperimentswereconductedutilizingone-dimensionalhorizontalsoilcolumnstovalidatetherelationship.Inaddition,anestimationmethodforhydraulicdiffusivitywithdiscinfiltrometerwasdeveloped.Theresultsindicatedafavorablefitofthetheoreticalrelationtotheexperimentaldata.Also,theexperimentwithdiscinfiltrometerforestimatingthediffusivityshowedthatthenewmethodwasfeasible.

简介：Theannualgrowthringsoftentreesandthesoilsnearthetreerootsweresampledfromtheminingaresoflead-andzinc-dominantmetalsintheXixiaMountain,Nanjing,forthedeterminationofchemicalelementcontents.Thestudyresultsshowedthattheelementalcontentsinthetreeringswerecorrelatedwiththoseinthesoils,i.e.,theelementalcontentsinthetreeringsincreasedwiththoseinthesoils,eveninthecasesofdifferentenvironmentsanddifferenttreespecies.Therefore,atime-concentrationsequencecouldbesetuponthebasisofdeterminingtheelementalcontentsinthesuccessiveannualgrowthringsoftreestoqualitativelyreflecttheannualvariationsofrelevantelementsinthesoils,andatime-concentrationsequenceofelementalcontentsinsoilscouldalsobeestablishedintermsofrelatedmodeltoreproducethedynamicchangesofthesurroundings.

简介：CorrelationandpathanalysismethodswereusedtostudytherelationshipbetweensoilpropertiesandthedistributionofdifferentsoilHgfractionswithninerepresentativesoilsfromChongqing,China.Resultsshowedthatclay(＜2m)couldincreasewater-solubleHg(r=0.700*).Soilorganicmatter(OM)couldenhancetheincreaseofelementalHg(r=0.674*).Thehigherthebasesaturationpercentage(BSP),themoretheresidualHg(r=0.684*).OrganicHg,thesumofacid-solubleorganicHg.andalkali-solubleHg,waspositivelyaffectedbysilt(2～20μm)butnegativelyaffectedbypH,withthedirectpathcoefficientsamountingto1.0487and0.5121,respectively.ThepositiveeffectofOMandnegativeeffectofBSPonorganicHgwerethemostsignificant,withthedirectpathcoefficientsbeing0.7614and-0.8527,respectively.Theindirecteffectofclay(＜2μm)viaBSP(pathcoefficient=0.4186)wasthehighest,showingthattherealinfluencingfactorintheeffectofclay(＜2μm)onacid-solubleorganicHgwasBSP.SincetheavailableHgfraction,water-solubleHg,waspositivelyaffectedbysoilclaycontent,andthequiteimmobileandnotbioavailableresidualHgbysoilBSP,suitablereductionofclaycontentandincreaseofBSPwouldbeofmuchhelptoreducetheHgavailabilityandHgactivityinHg-contaminatedsoils.

简介：Soilsamplesat0-10cmindepthwerecollectedperiodicallyatpairedfieldsinCorvallis,Oregon,USAtocomparedifferencesinsoilmicrobialandfaunalpopulationsbetweenorganicandconventionalagroecosystems.Resultsshowedthattheorganicsoilecosystemhadasignificantlyhigher(P＜0.05)averagenumberorbiomassofsoilbacteria;densitiesofflagellates,amoebaeofprotozoa;somenematodes,suchasmicrobivorousandpredaceousnematodesandplant-parasiticnematodes;aswellasCollembola.GreaternumbersofRhabditida(suchasRhabditisspp.),werepresentintheorganicsoilecosystemwhilePanagrolaimusspp.werepredominantintheconventionalsoilecosystem.TheomnivoresandpredatorsofAcarinaintheMesostigmata(suchasDigamasellidaeandLaelapid),andProstigmata(suchasAlicorhaiidaeandRhagidiidae),werealsomoreabundantintheorganicsoilecosystem.However,fungivorousProstigmata(suchasTerpnacaridaeandNanorchestidae)andAstigmata(suchasAcarida)weresignificantlyhigher(P＜0.05)intheconventionalsoilecosystem,whichsupportedthefindingthattotalfungalbiomasswasgreaterintheconventionalsoilecosystem.Seansonalvariationsofthepopulationdependedmostlyonsoilmoistureconditionandfoodwebrelationship.ThepopulationdeclinedfromMaytoOctoberforbothagroecosystems.However,higherdiversitiesanddensitiesofsoilbiotasurvivedoccurredintheorganicsoilecosysteminthedryseason.

简介：AmathematicalexpressionofFreundlichkineticequation,lnS=A'+B'lnt,ispresented,andthephysicalmeaningsofitsparametersareindicated.AlthoughtheFreundlichkineticequationandthetwo-constantequationarethesameintheform,thederivationoftheFreundlichkineticequationisprecise,whilethederivationofthetwo-constantequationhassomecontradictionsandisunreasonable,AnditissuggestedthattheFreundlichkineticequationshouldhaveprorityoverthetwo-constantequationtobeused.

简介：Thechangesofmicrobialbiomasscarbon(MBC)andnitrogen(MBN)andmicrobialcommunityinthetopsoiloftheabandonedagriculturallandonthesemi-aridLoessPlateauinChinaduringthenaturalsuccessionwereevaluatedtounderstandtherelationshipbetweenmicrobialcommunityandsoilproperties.MBCandMBNweremeasuredusingfumigationextraction,andmicrobialcommunitywasanalyzedbythemethodoffattyacidmethylester(FAME).ThecontentsoforganicC,totalN,MBC,MBN,totalFAME,fungalFAME,bacterialFAMEandGram-negativebacterialFAMEatthenaturalsuccessionsiteswerehigherthanthoseoftheagriculturalland,butlowerthanthoseofthenaturalvegetationsites.TheMBC,MBNandtotalFAMEwerecloselycorrelatedwithorganicCandtotalN.Furthermore,organicCandtotalNwerefoundtobepositivelycorrelatedwithfungalFAME,bacterialFAME,fungal/bacterialandGram-negativebacterialFAME.Naturalsuccessionwouldbeusefulforimprovingsoilmicrobialpropertiesandmightbeanimportantalternativeforsustainingsoilqualityonthesemi-aridLoessPlateauinChina.

简介：Arbuscularmycorrhizal(AM)共生者能极大地影响土壤富饶。然而，在AM共生发展层次之间的关系和柠檬mycorrhizosphere玷污微弱地在地里知道的富饶遗体。在我们的学习，AM殖民，孢子密度，菌丝的长度密度，和在柠檬(柠檬reticulataBlanco上的Robertson海军的橘子grafted)的glomalin相关的土壤蛋白质(GRSP)内容，沿着一个高度的坡度的果园在南部的中国季节地被调查。结果显示出那AM殖民和许多孢子，hyphae在不同季节和高度显著地波动。最高的AM殖民(83.03%)在夏天在海水平上面在200m在果园被观察，在在在秋天的400m的果园的孢子密度(16.8孢子g−1土壤)，并且在在在夏天的600个m果园的果园的菌丝的长度密度(2.36mg−1土壤)；当时最低价值(43.60%，2.7孢子g−1土壤和0.52mg−1AM殖民，孢子密度，和菌丝的长度玷污密度，分别地)都在冬季在800m在果园被观察。关联分析证明象土壤有机物，alkali-hydrolyzableN，可得到的P，和pH那样的土壤性质是显著地(P<0.05)断然与任何一个柠檬总数AM殖民或许多孢子和hyphae相关。GRSP是显著地(P<0.05)断然与土壤有机物和pH相关。冗余性分析支持了那严重地玷污象高度，GRSP，土壤有机物，和alkali-hydrolyzableN那样的环境因素(蒙特卡罗排列测试，P=0.002)在柠檬果园的影响AM殖民和许多孢子和hyphae。我们的数据表明了环境因素是的那土壤在在柠檬果园决定AM共生开发重要。

简介：NinePlatanusacerifolia(Ait),Willd.treesgrowingintheNanjingChildrenTeacher'sSchool,Nanjing,China,wereselectedtodeterminethecontentsof13chemicalelementsbothinthe1994'sgrowthrings,C(Z,t),andinthesoilsneartheroots,C′(Z,t),ofthetrees,Theresultsshowedthattherelationshipbe-tweenC(Z,t)andC′(Z,t)followedthelogarithmiclinercorrelationmoedl.lgC′(Z,t),=a(Z)+b(Z)lgC(Z,t),Basedonthismodelthechrono-sequencesofchemicalelementcontentsinthesoilswerereproducedfromtthoseihthetreerings;i.e.,thedynamicvariationsinthechemicalelementcontentsofthesoilsatthesitesweretrced.Inthisstudythechrono-sequencesofthechemicalelementsincludingCd,Pb,Mn,CoandZninthesoilsneartherootsofaPlatanusacerifoliatreefrom1957to1994wereestablished,andthebackgroundvaluesofCd,Pb,Mn,CoandZninthesoilwerecalcuatedbytakingthelowestvaluesofthechrono-sequencesoftheelementconentsasupperlimitsofthebackgroundvalues.

简介：Thechloroformfumigation-incubationmethowasusedtomeasurthesoilmicrobialbiomassC(SMBC)andN(SMBN)in16loessialsoilssampledfromAnsai,YongshouandYanglinginShaanxiProvince.TheSMBContentsinthesoilsrangedfrom75.9to301.0μgCg^-1withanaverageof206.μgCg^-1,accountingfor1.36%-6.24%ofthetotalsoilorganicCwithanaverageof3.07%,andtheSMBNcontentsfrom0.51to68.40μgNg^-1withanaverageof29.4μgNg^-1,accountingfor0.20%-5.65%ofthetotalNinthesoilswithanaverageof3.36%.AcloserelationshipwasfoundbetweenSMBCandSMBN,andtheybothwerepositivelycorrelatedwithtotalorganicC,totalN,NaOHhydrolizableNandmineralizableN.Theseresultsconfirmedthasoilmicrobialbiomasshadacomparativeroleinnutrientcyclesofsoils.

简介：Theradialbasisfunction(RBF)emergedasavariantofartificialneuralnetwork.Generalizedregressionneuralnetwork(GRNN)isonetypeofRBF,anditsprincipaladvantagesarethatitcanquicklylearnandrapidlyconvergetotheoptimalregressionsurfacewithlargenumberofdatasets.Hyperspectralreffectance(350to2500nm)datawererecordedattwodifferentricesitesintwoexperimentfieldswithtwocultivars,threenitrogentreatmentsandoneplantdensity(45plantsm-2).Stepwisemultivariableregressionmodel(SMR)andRBFwereusedtocomparetheirpredictabilityfortheleafareaindex(LAI)andgreenleafchlorophylldensity(GLCD)ofricebasedonreffectance(R)anditsthreedifferenttransformations,thefirstderivativereffectance(D1),thesecondderivativereffectance(D2)andthelog-transformedre?ectance(LOG).GRNNbasedonD1wasthebestmodelforthepredictionofriceLAIandGLCD.TherelationshipsbetweendifferenttransformationsofreffectanceandriceparameterscouldbefurtherimprovedwhenRBFwasemployed.Owingtoitsstrongcapacityfornonlinearmappingandgoodrobustness,GRNNcouldmaximizethesensitivitytochlorophyllcontentusingD1.ItisconcludedthatRBFmayprovideausefulexploratoryandpredictivetoolfortheestimationofricebiophysicalparameters.