外文翻译--免耕播种机的新型双翼型开沟器对玉米种区土壤物理特性和根系固定的影响和双圆盘开沟器相比较 英文版.pdf

andclimateconditions,thuspotentiallyaffectingcropemergenceandearlygrowth.ofarablecrops,progressivelyachievedinrecentyears,hasbeenconsiderable,butnewimprovementsnowavailableneedtobeindividuallytested.InafieldtrialatUdine(NEItaly),theeffectsfourreductionbulkwasAsoil/seed#K/locate/stillSoil&TillageResearch89(2006)196209penetration0167-1987/$doi:10.1016/j.stwork)onsoilphysicalpropertiesintheseedzoneandoncropemergenceandearlyrootgrowthofmaizewereevaluatedindifferentsoilsovera2-yearperiod(20022003),incomparisonwiththewidelyuseddouble-diskopener.Withrespecttothedouble-diskopener,ingeneralthewide-sweeptypeledtohighersoilresiduemixingwithoutexcessiveofthesoil-coveringindexbeingobserved,C027andC06%,respectively.Thewide-sweepopeneralsoshowedlowerdensityandsoilpenetrationresistanceinthetop5-cmsoillayeroftheseedfurrow,althoughnogreaterrootlengthdensityfoundinmaizeatthethree-leafstage,probablyduetothesmoothingeffectcausedbythesidecoultersattheseedingdepth.certaindelayinplantemergenceinsomecaseswasalsorevealedforthewide-sweepopener,whichmayberelatedtothelowercontact.Deviationsfromthisgeneralbehaviourinthevarioussoils(textureandinitialconditions)arediscussed.2005ElsevierB.V.Allrightsreserved.eywords:Maize；No-tillage；Openertype；Rootgrowth；SeedzonephysicalpropertiesAbbreviations:CI,coveringindex；DAS,daysaftersowing；DDO,double-diskopener；FRSD,furrowroughnessstandarddeviation；PR,resistance；RI,residueincorporation；RLD,volumetricrootlengthdensity；SOC,soilorganiccarbon；WSO,wide-sweepopener*Correspondingauthor.Tel.:+390498272723；fax:+390498272774.E-mailaddress:matteo.bertocco.1unipd.it(M.Bertocco).seefrontmatter#2005ElsevierB.V.Allrightsreserved.ill.2005.07.011ofanewkindofwide-sweepopener(i.e.,sidecoulterscurvedofupwardsintheirfinalpartandslightlyangledtowardsthedirectionThetechnologicalevolutionofseedersfordirectdrillingzonepropertiesandrootestablishmentinmaize(Zeamays,L.):Acomparisonwithdouble-diskopenerT.Vameralia,M.Bertoccob,*,L.SartoribaDipartimentodiAgronomiaAmbientaleeProduzioniVegetali,UniversityofPadova,Agripolis,VialedellUniversita16,35020Legnaro,Padova,ItalybDipartimentoTerritorioeSistemiAgro-forestali,UniversityofPadova,Agripolis,VialedellUniversita16,35020Legnaro,Padova,ItalyReceived17February2005；receivedinrevisedform13July2005；accepted29July2005AbstractAccordingtothekindofopenerapplied,no-tillageseederscanvariouslymodifysoilphysicalpropertiesinrelationtosoilEffectsofanewwide-sweepopenerforno-tillplanteronseedResear1.IntroductionInthelastfewyears,theeconomicandenviron-mentalimplicationsofconventionaltillage,suchaserosion,compactionandinvertingsoillayers,haveledtore-examinationofno-tillageeveninItaly(SartoriandPeruzzi,1994).Especially,intheheavysoilsofthiscountry,deepploughingaimsatincreasingsoilporosity,atleasttemporarily,inordertocreatesuitableconditionsforbothseedgerminationandrootgrowth.Simplificationofweedmanagementandhighergrainyieldsofsummercropslikemaizearegenerallyachievedwithrespecttono-tillage,asevidencedbythefewdataavailableintheliteratureforItaly(e.g.,Bonaetal.,1995).Theperformanceofno-tillageseedersdependsonseveralfactorsrelatedtofieldconditions,includingtypeandamountofresiduesatsoilsurface,openerdesign(Morrison,2002)andthecroptobesown.Theimplementsoftheseseedersmusthavehighflexibility,sothatvariouscropscanbesownindifferingfieldconditionswithcorrectseeddeposition(e.g.,density,distance,depth).Inno-tillagepractices,thecharacter-isticsoftheseed-furrowplayanimportantroleingermination.Manyauthorshavepointedoutthatthemostsignificantfactorsregulatinggermination,suchassoilmatricpotential,temperature(Lindstrometal.,1976；SchneiderandGupta,1985)andsowingdepth(AlessiandPower,1971；Mahdietal.,1998)areaffectedbythesoil/openerinteraction(Tessieretal.,1991a,b).Inparticular,inordertomaintainconstantsowingdepth,varioustypesoflinkagesbetweenopenerandseedertoolbarhavebeenproposedduringthelastfewdecades.Forinstance,connectionwithaspringsystem,theoldestbutsimplestsolution,isnotalwaysadequatetoguaranteeuniformityofsowingdepth,especiallyinheavysoils.Greatimprovementshavebeenobtainedwithparallellinkage,sincethisallowstheopenertofollowsoilsurfaceprofilesaccurately.Manyofthecharacteristicsoftheseedzoneinno-tillagedependsonthetypeofopenerattachedtotheseeder(Wilkinsetal.,1983)andthetwomaintypesusedtineanddiskmayleadtogreatdifferences.ThetineopenertypicallycreatesanappreciableburstingeffectinthesoilandgenerallymovesaconsiderablequantityoffinedamperaggregatesT.Vameralietal./Soil&Tillagetowardsthesoilsurfaceafactparticularlyappreciableintoolshavinganasymmetricshape(DarmoraandPandey,1995)butwhichmaybenegativeifarainlessperiodoccursaftersowing,assoildryingisaccelerated(Chaudhuri,2001).Insimilarconditions,thediskopenermaycausemoreprogressivewaterlossinthesoillayerabovetheseedsthanthetineopener(Tessieretal.,1991a,b),althoughgreatdrawbacksareobservableinwetclaysoilsbecauseapermanentunclosedfurrowiscommonlycreated(SartoriandSandri,1995).Itiswidelyrecognisedthatmanagementofcropresidues(previouscrop)isoneofthemostimportantconstraintsforadoptingno-tillage(Carter,1994).Tineopenersshiftorganicdebrisinthesoilsurfacefromthecroprowsideways,withpossiblepluggingoftheseederinthecaseofheavyresidues,whereasdiskopenersmayleadtohairpinning,withaconsequentbadsoil/seedcontactandpossibletoxiceffectonseedlings(Hultgreen,2000).Unmanagedresiduescancreatemanyproblemsindirectsowing,buttheirpresenceatthesoilsurfaceisgenerallybeneficialinlimitingsomenegativeeffectsonsoil,likeerosionandwaterlosses(GillandAulakh,1990).Asregardssoilandclimateconditions,openersshouldachieveseveralaims,likeuniformityofsowingi.e.,spacinganddepthproductionofasuitableamountoffinesoilaggregatetoensuresoil/seedcontact,reductionofwaterlosses,avoidanceofseedcontactwitheitherfertilizersorcropresiduesandlimitationoffurrowcompaction,whichmayobstructrootgrowth(Willatt,1986；TsegayeandMullins,1994；Buenoetal.,2002).Thetypeofopenerwasfoundtoaffectemergenceandplantestablishmentmarkedly(McLeodetal.,1992),especiallyincrust-formingsoils,forwhichbetterresultsaregenerallyobtainedwiththedouble-diskopener(HemmatandKhashoei,2003).Thetechnologicalevolutionofno-tillageseedersforarablecrops,progressivelyachievedinthissector,hasbeengreat,butthelargenumberofimprovementsnowavailablemustbeindividuallytestedandcare-fullyevaluated.Inaddition,muchoftheliteratureonthissubjectrefersalmostexclusivelytoopener/soilinteractions,withoutanalysingeffectsoncropgrowth.Theeffectsoffurrowshapeanditspropertiesonthedraftforcerequiredbydifferentopenertypeshavebeenwidelystudiedinrelationtosoilconditionsch89(2006)196209197andoperatingparameters,suchasdepthorspeedcomparedwiththatofadouble-diskopener(DDO)thesoilprofilecanbefollowedbytheopenersasregularlyaspossible.Forthisreason,ithasthreeindependentjointedsections,each1.5mwideandlinkedtotherigidframewithfourelasticjoints.Eachsectionhasfiveopeners,foratotalof15sowingrows,whicharelaidonthreeseedinglinesandequippedwithasingleparallellinkageforimprovedstability.Inaddition,eachsectionissupportedbyafrontwheelandarearpackertandem(Fig.2).Thelatterisanessentialcomponentfortheworkingtheseedingunitinthisseeder；itismadeof10wheelspersection,with3.508tyresand0.9barpressure.TheseederequippedwiththeDDOisaneight-unitmountedno-tillplanterwithpneumaticseedmeteringand0.75mrowspacing,resultingina6mworkingwidth.TheDDOusedhereiscomposedofasingle,fluted,round-bladedcoulterandadouble-disk,associatedwithtwosiderollersandtworearV-mountedwheels(Fig.2).Performancevaluationofopenertypesrequiresdifferencesamongseederstobekepttoaminimum,Researtillairseeder:(a)frontchisel；(b)sidecoulter；(c)endofcoulter(curvedupwards)；(d)multipleseeddispenser；(e)partofparallellinkage.adoptedbytheno-tillplanterMaxEmerge2(JohnDeereItalia,Milan,Italy).TheWSOhasastraightaxis,endingwithafrontchiselandtworearside18-cmwidecoulters,whichareslightlyangledtowardsthedirectionofworkandcurvedupwards(908)intheirfinalpart(25mmhigh)(Fig.1).Thefrontchiselcutssoil2530mmdeeperthanthecoulters.Seeddeliverytoeachunitisthroughasinglepneumatictubefromthecentralisedvolu-metricmeteringsystem,whichallowstheseedertoassumeacertaindegreeofpolyvalence.Althoughvarioustypesofdeposition(i.e.,rowspacing)canbeset,inourfieldtrialasthefirsttestofthisprototypeopenermaizewassowninrows0.45mapart,adistancecommonlyusedintheexperimentalsite.ThestructureoftheseederequippedwiththeWSOincludesonerigidandonefoldingframe.Thefirstissupportedbyafronthead-shafttocoupletheseedertothetractorandtworearlow-pressurewheelsfor(GebresenbetandJonsson,1992；CollinsandFowler,1996；Sanchez-Gironetal.,2005).Instead,onlyafewstudieshaveexaminedsomecropparametersandtheygenerallydealwithdrillsforautumnsowingofcereals.Forinstance,ChaudhryandBaker(1988)foundthatvarioustypesofopenerledtodifferenttypesofgrowthofbarleyseedlings,i.e.,greatershootandrootweightswhenbothwinged(T-shapedgroove)orhoe(U-shapedgroove)typesareusedinsteadofthetriple-diskone.Inthisframework,thepresentstudyevaluatestheperformanceofaninnovativewide-sweepopener,linkedtotheframebyadoublelinkageunit.Itseffectsonsomesoilphysicalpropertiesintheseedzone,cropemergenceandearlyrootgrowthofmaizewereevaluatedinvarioussoilsovera2-yearperiodinNEItalyandcomparedwiththoseofadouble-diskopener,whichisthemostwidespreadinItaly.2.Mater