简介：TheimpactofpHchangesonmicrobialbiomasscarbon(Cmic)andmicrobialbiomassphosphorus(Pmic)wereexaminedfor3redsoilsundercitrusproductionwithdifferentlengthsofcultivation.SoilpHsignificantlyaffectedCmicandPmic.TheCmicandPmicchanges,asafunctionofsoilpH,appearedtofollowanormaldistributionwiththeoriginalsoilpHvalueattheapexandaspHincreasedordecreasedcomparedtotheoriginalsoilpH,CmicandPmicdeclined.Moreover,therewerecriticalpHvaluesatbothextremes(3.0ontheacidicsideand8.0to8.5onthealkalineside),beyondwhichmostofmicroorganismscouldneversurvive.TheeffectofpHonCmicandPmicwasalsorelatedtotheoriginalsoilpH.ThehighertheoriginalsoilpHwas,thelessCmicorPmicwereaffectedbypHchange.ItissuggestedthatsoilmicroorganismsthatgrowinasoilenvironmentwithamoreneutralsoilpHrange(I.e.pH5.5-7.5)mayhaveagreatertolerancetopHchangesthanthosegrowinginmoreacidicormorealkalinesoilpHconditions.

简介：Thisstudywasdesignedtounderstandtheimpactofmethylbromide(MB)(CH3Br)anditsalternativesonbothfree-livingandroot-knotnematodesinthesoil.Arandomizedcompleteblockexperimentwithsixtreatmentsand4replicates(eachreplicateinaseparategreenhouse)wasestablishedinQingzhou,ShandongProvince,China.InadditiontoMBanduntreatedcontrol(CK)treatmentstherewerefouralternativesoilfumigationpracticesincludingMB+virtuallyimpermeablefilms(VIF),metamsodium(MS),MS+VIFandsoilsolarizationcombinedwithselectedbiologicalcontrolagents(SS+BCA).Twotomato(LycopersicumesculentumMill.)cultivars,cv.Maofen-802fromtheXianInstituteofVegetableScience,China,andcv.AF179BrillantefromtheIsraeliHazeraQualitySeeds,wereselectedastestcrops.TheresultsindicatedthatRhabditidaewasthemostdominantpopulationwithpercentageabundanceashighas85%ofthetotalnumberofidentifiedfree-livingnematodes,followedbythatofCephalobidae.Methylbromideanditsalternativesexceptforthenon-chemicalSS+BCAtreatmentcontrolledthetargetpest,root-knotnematodes.Also,theimpactofthethreechemicalalternativesonfree-livingnematodenumberandfunctionalgroupabundancewassimilartotheimpactassociatedwithatypicalmethylbromideapplication.Chemicalfumigationpractices,especiallythatwithMB,significantlyreducedthenumberofnematodesinthesoilandsimultaneouslysignificantlyreducedthenumberofnematodegeneratherebyreducingnematodediversity.Allthefoursoilchemicalfumigationactivitiesdecreasedsoilmicrobialbiomassandhadanobviousinitialimpactonmicroorganismbiomass.Furthermore,bothplant-parasiticandfungivorenematodeswerepositivelycorrelatedwithsoilmicrobialbiomass.

简介：Alaboratoryincubationexperimentwasconductedtostudytheinfluenceofcadmium(Cd),lead(Pb)andzinc(Zn)onthesizeofthemicrobialbiomassinredsoil.Allthethreemetalswereapplied,separately,atfivedifferentlevelsthatwere:Cdat5,15,30,60,and100μgg^-1;Pbat100,200,300,450and600μgg^-1andZnat50,100,150,200and250μgg^-1soil,InComparisontouncaontaminatedsoil,themicrobialbiomasscarbonandbiomassnitrogendecreasedsharplyinsoilscontaminatedwithCd,PbandZn,AmoreconsiderableincreaseinthemicrobialbiomassC:Nratiowasobservedinthemetalcontaminatedsoilsthanthenon-treatedcontrol.Amongthetestedmetals,CddisplayedthegreatestbiocidaleffectfollowedbyZnandPb,showintheirrelativetoxicityintheorderofCd>Zn>Pb.

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.