学科分类
/ 2
40 个结果
  • 简介:Excessivenitrogen(N)fertilizerapplicationtowinterwheatisacommonproblemontheNorthChinaPlain.TodeterminetheoptimumfertilizerNrateforwinterwheatproductionwhileminimizingNlosses,fieldexperimentswereconductedfortwogrowingseasonsateightsites,inHuiminCounty,ShandongProvince,from2001to2003.TheoptimumNrateformaximumgrainyieldwasinverselyrelatedtotheinitialsoilmineralNcontent(Nmin)inthetop90cmofthesoilprofilebeforesowing.TherewasnoyieldresponsetotheappliedNatthethreesiteswithhighinitialsoilmineralNlevels(average212kgNha-1).TheaverageoptimumNratewas96kgNha-1forthefivesiteswithlowinitialsoilNmin(average155kgNha-1)beforesowing.ResidualnitrateNinthetop90cmofthesoilprofileafterharvestincreasedwithincreasingfertilizerNapplicationrate.TheapparentNlossesduringthewheat-growingseasonalsoincreasedwithincreasingNapplicationrate.TheaverageapparentNlosseswiththeoptimumNrateswerelessthan15kgNha-1,whereasthefarmers'conventionalNapplicationrateresultedinlossesofmorethan100kgNha-1.Therefore,optimizingNuseforwinterwheatconsiderablyreducedNlossestotheenvironmentwithoutcompromisingcropyields.

  • 标签: 土壤化学 土壤矿物 冬小麦
  • 简介:Changesofsoilorganicnitrogenformsandsoilnitrogensupplyundercontinuousricecroppingsystemwereinvestigatedinalong-termfertilizationexperimentinJinhua,ZhejiangProvince,China.ThefertilizertreatmentsincludedcombinationofP-K,N-K,N-P,andN-P-Kaswellasthecontrol.Aftersixyearsofcontinuousdouble-ricecropping,totalsoilNandhydrolysableNcontentsremainedstableinplotswithNtreatments,whilethehydrolysableNcontentsweresubstantiallyreducedinthoseplotswithoutNapplication.Comparedtotheunbalancedfertilizationtreatments,PandKincreasedthepercentageofhydrolysableammoniumNinthetotalsoilNwiththebalancedapplicationofN,andalsomaintainedhigherricegrainyieldsandnitrogenuptake.GrainyieldwaspositivelycorrelatedwithtotalNuptake(r=0.875**),hydrolysableN(r=0.608**),hydrolysableammoniumN(r=0.560**)andthehydrolysableunknownN(r=0.417**).TotalNuptakewaspositivelycorrelatedwithhydrolysableN(r=0.608**),hydrolysableammoniumN(r=0.440**)andhydrolysableunknownN(r=0.431**).Soilnutrientdepletionand/orunbalancedfertilizationtoricecropreducedNcontentinsoilmicrobialbiomass,andthereforeincreasedC/Nratio,suggestinganegativeeffectonthetotalmicrobialbiomassinthesoil.

  • 标签: 微生物 土壤生物学 有机氮 水稻
  • 简介:到环境因素的空间的全体的土壤氮(N)同位素作文和时间的规模和他们的关系的模式说明N周期并且N采购原料,并且是到全球变化的陆上的N周期和它的反应的综合指示物。这研究的目的是:我)15N(15N)在Qinghai西藏的高原上在不同生态系统类型和土壤侧面珍视调查土壤N内容和自然许多的模式;ii)珍视在土壤N内容和土壤15N的模式上检验气候的因素和土壤特征的效果;并且iii)介绍越过生态系统和土壤测试在土壤15N价值和土壤C/N比率之间的关系。土壤侧面沿着二横断在51个地点被取样在长度的1875km和200km分开并且在Qinghai西藏的高原上的森林,草地和大草原里分布式。每个地点被取样从0~40厘米和每件样品的土壤深度的每10厘米为土壤N内容和15N价值被分析。我们的结果比的显示在草地的土壤N和15N价值(040厘米)高得多在荒芜的大草原。当沿着土壤侧面的土壤15N价值的变化不要不是土壤15N价值趋于与土壤深度增加的山草地,低地草地,和适度的大草原在大多数生态系统之中是统计上重要的时,土壤N为每个生态系统与土壤深度减少了。在土壤15N价值和吝啬的年度降水之间的寓言的关系显示土壤15N价值与在荒芜的大草原增加降水直到500公里增加了,然后与越过所有另外的生态系统增加降水减少了。而且,在15N价值之间的寓言的关系和吝啬的年度温度在所有单个生态系统类型存在。土壤N和15N价值(040厘米)随土壤淤泥和泥土内容的增加增加了。而且,大约11的C/N比率的阀值把在土壤15N价值和土壤C/N比率之间的寓言的关系划分了成积极(C/N<11)并且否定(C/N>11)分开,它越过所有生态系统和土壤侧面是有效的。为土壤15N价值的土壤C/N比率的大解释力量建议了那C和N集中,被降水和温度�

  • 标签: 土壤剖面 青藏高原 全氮 环境因子 生态系统 年平均温度
  • 简介:PotexperimentswerecarriedouttoestimateN2fixationbyvetch,milkvetch,sicklealfalfaandbroadbeaninpurestandusinga^15N-labelledsoil.Winterwheatwasusedasthenon-fixingcontrol.The15N-labelledsoilusedwaspreparedbygrowingcorn-wheat-cornsuccessivelyonanearlyorganic-matter-freeXiashuloesssupplementedwithadequateamountsof(15NH4)2SO4,P,Kandmicronutrients,thenincorporatingthese15N-labelledplantmaterialsintothesoilaftereachhavest,andallowingtheplantmaterialstobedecomposedaerobicallyfor410dafterincorporationoftheplantmaterialofthethirecrop.The15Nenrichmentofwheatplant-Nvariedslightlywithorgans,withamaximumdifferenceof9.8%,Basedon15NenrichmentofsoilNinferredfromthemeanvalueofthe15Nenrichmentindifferentorgansofwheat79%-91%oftotalNinthetopsand67%-74%oftotalNintherootsoflegumesstudiedwerederivedfromatmosphere.EstimatebyisotopedilutionmethodwasingoodagreementwiththatbytheconventionaldifferencemethodprovidedvaluesobtainedbythelatterwerecorrectedforseedN,andalsowiththatfromthemeasurementofNaccumulatedinthetopsofthelegumes.

  • 标签: 15N标记土壤 豆科植物 固氮作用 温室试验
  • 简介:An80-dincubationexperimentwasconductedtoinvestigatestrawdecomposition,theprimingeffectandmicrobialcharacteristicsinanon-fertilizedsoil(soil1)andalong-termorganicmanure-fertilizedsoil(soil2)withandwithout13C-labeledmaizestrawamendmentunderdifferentmoisturelevels.Thesoil2showedamarkedlyhigherprimingeffect,microbialbiomassC(Cmic),andβ-glucosidaseactivity,andmoreabundantpopulationsofbacteriaandfungithanthesoil1.Also,soilCO2emission,Cmic,β-glucosidaseactivity,andbacterialandfungalpopulationsizesweresubstantiallyenhancedbystrawamendment.Inthepresenceofstraw,theamountofstrawmineralizationandassimilationbymicrobesinthesoilat55%ofwaterholdingcapacity(WHC)weresignificantlyhigherby31%and17%,respectively,comparedtothoseat25%ofWHC.Incontrast,β-glucosidaseactivityandfungalpopulationsizewerebothenhancedasthemoisturecontentdecreased.Cmicdecreasedasstrawavailabilitydecreased,whichwasmainlyattributedtothereductionofstraw-derivedCmic.Amendedsoils,excepttheamendedsoil2at25%ofWHC,hadamoreabundantfungalpopulationasstrawavailabilitydecreased,indicatingthatfungaldecomposabilityofaddedstrawwasindependentofstrawavailability.Non-metricmultidimensionalscalinganalysisbasedonfungaldenaturedgradientgelelectrophoresisbandpatternsshowedthatshiftsinthefungalcommunitystructureoccurredaswaterandstrawavailabilityvaried.Theresultsindirectlysuggestthatsoilfungiareabletoadjusttheirdegradationactivitytowaterandstrawavailabilitybyregulatingtheircommunitystructure.

  • 标签: 土壤CO2排放 秸秆分解 水分含量 碳矿化 修订 生物属性
  • 简介:Fivehumicfractionswereobtainedfromauniformly^15N-labelledsoilbyextractionwith0.1molL^-1Na4P2O7,0.1molL^-1NaOH,andHF/HCl-0.1molL^-1NaOH,consecutively,andanalyzedby^13Cand^15NCPMASNMR(crosspolarizationandmagicanglespinningnuclearmagneticresonace).Comparedwiththoseofnativesoilshumicfractionsstudiedasawholecontainedmorealkyls,methoxylsandO-alkyls,being27%-36%,17%-21%and36%-40%,respectively,butfeweraromaticsandcarboxyls(bein14%-20%and13%-90%,respectively),Amongthosehumicfractions,thehumicacid(HA)andfulvicacid(FA)extractedby0.1molL^-1Na4P2O7containedslightlymorecarboxylsthancorrespondinghumicfractionsextractedby0.1molL^-1NaOH,andtheHAextactedby0.1molL^-1NaOHaftertreatmentwithHF/HClcontainedtheleastaromaticsandcarboxyls.Thedistributionofnitrogenfunctionalgroupsofsoilhumicfractionsstudiedwasquitesimilartoeachotherandalsoquitesimilartothatofhumicfractionfromnativesoils.Morethan75%oftotalNineachfractionwasinamidefrom,with9%-13%presentasaromaticand/oraliphaticaminesandtheremainderasheerocyclicN.

  • 标签: 芳香族化合物 腐殖质 赋存形态 土壤成分
  • 简介:与一个改编微生物引起的社区接种土壤比有在bioremediation的纯紧张的接种是一条更有效的bioaugmentation途径。然而,从有在土壤补习改变污染层次和污染历史的地点的不同inocula的潜力的信息正在缺乏。学习的目的是在土壤inocula调查改编微生物的潜力,与不同污染层次和污染历史,到降级1,2,4-trichlorobenzene(1,2,4-TCB)。从污染chlorobenzene的地点的三不同土壤被接种进农业土壤和与1,2,4-TCB刺的土壤暂停文化。结果证明36.52%开始应用的1,2,4-TCB在非接种的土壤是在场的,而大约19.00%1,2,4-TCB在在28天孵化以后与污染土壤接种的农业土壤是在场的。与改编微生物引起的生物资源接种的土壤(在土壤inocula)比非接种的土壤显示出更高的呼吸和更低的1,2,4-TCB挥发,建议1,2,4-TCB的存在在为接种使用的污染土壤改编了degraders。它进一步在污染土壤暂停文化被证实无机的氯化物离子的集中在全部试验性的时期上连续地增加了。更高的降级潜力带到不仅而且到更高的残余形成的inocula的更高的污染。然而,甚至低级污染的inocula在提高1,2,4-TCB的降级是有效的。因此,适用改编了在土壤形式的微生物特别与更低的污染层次,inocula能是为土壤补习的有效、环境友好的策略。

  • 标签: 微生物降解 农业土壤 悬浮培养 三氯苯 污染土壤修复 土壤接种
  • 简介:ExperimentswerecarriedoutonavegetablefieldwithPekingcabbage(Brassicapekinensis(Lour.)Rupr.),cabbage(Brassicachinensisvar.OleiferaMakinoandnemoto),greencabbage(BrassicachinensisL.),spinach(SpinaciaoleraceaL.)andrape(BrassicacampestrisL.)tostudytheeffectsofNformsandNratesontheirgrowthandnitrateaccumulation.Theresultsindicatedthatapplicationofammoniumchloride,ammoniumnitrate,sodiumnitrateandureasignificantlyincreasedtheyieldsandnitrateconcentrationsofPekingcabbageandspinach.Althoughnosignificantdifferencewasfoundintheyieldsafterapplicationofthe4Nforms,nitrateNincreasednitrateaccumulationinvegetablesmuchmorethanammoniumN.ThevegetableyieldswerenotincreasedcontinuouslywithNrateincrease,andoversupplyofNreducedtheplantgrowth,leadingtoayielddecline.Thistrendwasalsotruefornitrateconcentrationsinsomevegetablesandatsomesamplingtimes.However,asawhole,thenitrateconcentrationsinvegetableswerepositivelycorrelatedwithNrates.Thus,additionofNfertilizertosoilwasthemajorcauseforincreasesinnitrateconcentrationsinvegetables.Nitrateconcentrationsweremuchhigherinroots,stemsandpetiolesthaninbladesatanyNrate.

  • 标签: 蔬菜生长 硝酸盐 结构 含氮比率 甘蓝
  • 简介:钾(K)在植物影响生理的过程的一个范围并且是控制庄稼生产率和收益质量的一个关键因素。很少信息都不有关切割花植物的功能上的K营养的效果是可得到的。现在的学习被执行调查在K和N营养之间的相互作用,在花数量和毛莨属asiaticusL的质量上。植物与Kfertigation的三个层次被供应(60,120,或180mgKL−;1)不到50mgNL−;1应用,并且在120mgKL−的中间的水平;1,到N应用的三个层次(50,100,或150mgNL−;1)。二最低K治疗和最低N治疗由于更低的发生在花生产为佼佼者倒下茎,在很快扩展花茎的纸巾与局部性的Ca缺乏联系的混乱。有害效果在180mgKL−的供应下面已经以收益质量是明显的;1和50mgNL−;1,并且没在渗透的潜在的、相对的水内容或植物织物的膜稳定性与变化被联系,或与在除在高N申请下面的减少的Ca以外的叶子的矿物质内容的变化。我们的结果建议R的一个低营养的要求。asiaticusL。为K和N,在在K和N的高集中的申请下面的减少的花质量的织物水关系的参与的缺乏,和茎由Ca的减少的可获得性在N和K的高申请下面倒下到花的膨胀织物的正式就职起源。

  • 标签: 作物生产力 钾营养 花毛茛 亚洲 应用程序 切花植物
  • 简介:氮使用效率(NUE)在中国是很低的,差不多70%应用的氮化肥的损失在high-yielding稻田被报导。以便调查高亲密关系的铵运输或举起的分子的基础进米饭(OryzasativaL.),我们分析了九铵的表示侧面transporters(AMT),OsAMT1的三各个,OsAMT2和OsAMT3,根据外部N地位在象在这些表示模式的变化一样的米饭生长的二个不同N要求阶段(年轻幼苗阶段和tillering阶段)使用即时反向的抄写聚合酶链反应(RT-PCR)。结果建议九OsAMT基因在米饭植物的不同机关被表示,包括成熟的根,新根,茎,旧叶子和新叶子并且表示模式是相应蛋白质的位置在种系发生的树上特定、独立的机关。OsAMT11,3;2和3;3在根和射击被表示,首先旧的叶子,OsAMT1;2和1;3主要在根,和OsAMT2;1,2;2,2;3和3;1主要在射击,首先在新叶子,并且相对更在里面茎比另外的基因。在二个不同N要求阶段的表示模式是一样;在有更大的N要求的tillering阶段,然而,OsAMTs抄本层次比在有低N要求的年轻幼苗阶段的那些大。为48hN饥饿起来调整的OsAMT111;2,3;1,3;2,3;3并且下面调整的OsAMT1;3mRNA丰富。后面的N饥饿,NH4+和NH4NO3再供给下面调整的OsAMT1;2和3;3并且起来调整的OsAMT1;3,而NO3再供给下面调整的OsAMT111;2。这些建议OsAMT的器官特定的表示模式能被N要求和外部N地位调整。

  • 标签: 表达模式 水稻植株 氮素营养 硝酸铵 转运体 逆转录聚合酶链反应
  • 简介:Theclosed-jarincubationmethodiswidelyusedtoestimatethemineralizationofsoilorganicC.TherearetwoCpools(i.e.,organicandinorganicC)incalcareoussoil.ToevaluatetheeffectofadditionalcarbonatesonCO2emissionfromcalcareoussoilduringclosed-jarincubation,threeincubationexperimentswereconductedbyaddingdifferenttypes(CaCO3andMgCO3)andamountsofcarbonatetothesoil.TheadditionofcarbonatessignificantlyincreasedCO2emissionfromthesoil;theincreaserangedfrom12.0%intheCaCO3amendedsoilto460%intheMgCO3amendedsoilduringa100-dincubation.CumulativeCO2productionattheendoftheincubationwasthreetimesgreaterintheMgCO3amendedsoilcomparedtotheCaCO3amendedone.TheCO2emissionincreasedwiththeamountofCaCO3addedtothesoil.Incontrast,CO2emissiondecreasedastheamountofMgCO3addedtothesoilincreased.Ourresultsconfirmedthattheclosed-jarincubationmethodcouldleadtoanoverestimateoforganicCmineralizationincalcareoussoils.BecauseofitseffectonsoilpHandthedissolutionofcarbonates,HgCl2shouldnotbeusedtosterilizecalcareoussoiliftheexperimentincludesthemeasurementofsoilCO2production.

  • 标签: 土壤CO2排放 石灰性土壤 碳酸盐 二氧化碳排放量 有机碳矿化 孵化期间
  • 简介:在空气在农业土壤影响土壤质量和温室气体集中在土壤改变器官的碳(SOC)。干燥农田在中国盖住超过70%整个农田区域并且在减轻二氧化碳(CO2)起一个重要作用排出物。在这研究,4109个干燥农田土壤多角形用土壤层的空间覆盖分析被提取(1:500000)并且陆地使用层(1:500000)在安徽为干燥农田支持SOC动力学的世纪模型模拟省,从1980~2008的华东。就二个地确认地点而言,世纪模型在在省为干燥农田为SOC动力学建模相对表演了很好。模仿的结果证明区域加权的平均数玷污从18.77MgCha−增加的干燥农田的器官的碳密度(SOCD);1在1980~23.99MgCha−;10.18MgCha−与平均隐遁在2008评价;1year−;1。约94.9%全部的干燥农田区域扣押了碳当5.1%有的碳输了时。在过去的29年,在省的干燥农田土壤的网SOC获得是19.37Tg,与0.67TgCyear−的平均隐遁率;1。SOC的扩大主要由于氮化肥和农家庭院粪肥的增加的消费。而且,SOC动力学高度在干燥农田土壤组之中被区分。有一条好规模的土壤数据库途径的世纪模型的集成能方便地在地区性的规模为SOC动力学的精确模拟作为一个工具被利用。

  • 标签: 土壤有机碳密度 土壤数据库 中国东部 模型模拟 动态模拟 旱作农田
  • 简介:Aerobicstaticpilecomposting(mechanicalturningevery3days)ofpigmanurewaspreparedat8m3windrowheaps.Sawdustwasusedasthebulkingagenttoprovideadditionalcarbonandtoincreasetheporosityofthesubstrate.TwotreatmentsatinitialC/Nratiosof30and15,respectively,weredesignedinthestudy.Dissolvedorganiccarbon(DOC),solubleNH4+-N,C/Nratiosinsolidandaqueousphases,E4/E6ratios,andseedgerminationindex(GI)weredeterminedtoevaluatethematurityoftheco-composts.Seedgerminationindex,abiologicalparameter,wassuggestedasoneofthemostreliablematurityindicatorsfororganiccompost.TheresultsshowedthatthetreatmentattheinitialC/Nratioof30reachedmaturityafter49daysofcomposting;however,thetreatmentattheinitialC/Nratioof15shouldrequirecompostingtimeoflongerthan63daystoobtainmaturation.Chemicalmulti-indicatorevaluationwasnecessary,andtheGImeasurementwastherecommendedapproachformaturityevaluationinthestudy.

  • 标签: 碳/氮比值 猪粪 化学成分 生物学 壮年期 有机肥料
  • 简介:FieldlysimetermethodwasemployedtoinvestigatethedownwardmovementandleachingofNappliedtosummercorn(ZeamayL.)ondrylandsoilinBeijing,AN-fertilizer(120kgNhm^-2)andacontroltreatmentwerarrangedforthestudy.Soilsolutionwascollectedatdepthsof20,40,60,120and170cm,whileleachtewasollectedatthebottom(220cm)ofthelysimeter,TheresultsshowedthatthedownwardmovementofNO3^-Ninsoilprofilewasgreatlyaffectedbyrainfallpattern.ThepeakofleachedNO3^-Nfrombothtreatmentscoincidedwiththepeakoftherainfall.Inaddition,leachedNO3^-Nfrombothtreatmentsandrainfallweresignificantlycorrelated(P<0.05).TheamountofleachedNO3^-NwasnotgreatintheN-fertilizertreatment,TheresultsalsosuggestedthatNfertilizationcouldcauseNO3^--Ncontaminationofgroundeaterduringtherainyseason.

  • 标签: 玉米 地表水 氮流失 向下移动 土壤剖面 干旱地区
  • 简介:Nitrogenousfertilisersareunderconsiderationforpromotingthegrowthofnursery-rearedhooppine(AraucariacunninghamiiAitonexA.Cunn)seedlingsintheestablishmentphaseofsecondrotation(2R)plantations.Using15N-labelledfertilisers,weinvestigatedtheeffectofdifferentforms(ammoniumsulphate,ammoniumnitrate,potassiumnitrateandurea)andratesofapplication(0,150and300mgNkg-1driedsoil)offertilisersonthegrowth,15Nrecoveryandcarbonisotopecomposition(δ13C)ofhooppineseedlingsina12-monthglasshousetrialinsoutheastQueensland,Australia.The15N-labelledfertiliserswereappliedtonursery-rearedhooppineseedlings,whichwerethengrowninpots,containingca.1.2kgdriedsoil,underwellwateredconditionsfor12months.Fourseedlingsfromeachtreatmentwereharvestedat4-monthintervals,dividedintoroots,stemandfoliage,withafurthersubdivisionfornewandoldfoliage,andthenanalysedfor15N,totalN,δ13CandtotalC.Therewasnosignificantresponseintheseedlinggrowthtotheformorrateofapplicationofnitrogen(N)fertiliserwithinthe12-monthperiod,indicatingthattheseedlingsdidnotexperienceNdeficiencywhengrownonsecondrotationhooppinesoils.Whilethecombined15Nrecoveryfromsoilandplantremainedataround70%throughouttheexperiment,theproportionof15Nrecoveredfromtheplantsincreasingsteadilyovertime.Nitratecontainingfertilisersat150mgNkg-1soilgraduallyincreasedseedlingfoliageδ13Coverthe12-monthperiod,indicatinganincreaseinseedlingwateruseefficiency.

  • 标签: 肯宁南洋杉 水利用效率 森林土壤
  • 简介:Natural^15NabundancemethodwasusedinthisstudytoinvestigatetheN2-fiingcapacitiesofseveralherbaceousandshrublegumesbyafieldexperiment,Forherbaceouslegumes,theresultswereinconsistentwiththoseobtainedbyapotexperiment.CrotalariamucronataDesv.hadahigher,N2-fixingcapacitythanVignasinensis(L.)Savi.Forshurublegumes,N2-fixingCapacityunderfieldconditionwasslightlydifferentfromthatinpotexperiment.Theseresultsdemonstratedthatthenatural^15NabundancemethodwasapplicabletoevaluatingN2-fixingcapacitiesofherbaceousandshrublegumes,andthatpotexperimentwassuitableforevaluatingtheN2-fixingcapacitiesofnotonlyherbaceouslegumesbutalsoshrublegumes.LeguminousN2-fixingplantsdifferedinresponsetophosphorusfertilization,Phosphorusfertilizerappicationgreatlyincreasedthepercentageofnitrogenderivedfromair(%Ndfa)andtotalamountofN2fixedbyLespedezformosa(Vog.)Koehne(Jiangxi),PhosphorusfertilizershowednosignifcanteffectontheN2-fixingpercentageofCajanuscajan(L.)Millsp.butincreaseditstotalbiomass,thusincreasingthetotalamountofN2fixed.

  • 标签: 草本 自然氮 富集机理 灌木 固氮作用 磷肥
  • 简介:Theeffectsofsimulatednitrogen(N)depositiononsoilexchangeablecationswerestudiedinthreeforesttypesofsubtropicalChina.FourNtreatmentswiththreereplicationsweredesignedforthemonsoonevergreenbroadleafforest(matureforest):control(0kgNha-1year-1),lowN(50kgNha-1year-1),mediumN(100kgNha-1year-1)andhighN(150kgNha-1year-1),andonlythreetreatments(i.e.,control,lowN,mediumN)wereestablishedforthepineandmixedforests.Nitrogenhadbeenappliedcontinuouslyfor26monthsbeforethemeasurement.ThematureforestrespondedmorerapidlyandintensivelytoNadditionsthanthepineandmixedforests,andexhibitedsomesignificantnegativesymptoms,e.g.,soilacidification,Almobilizationandleachingofbasecationsfromsoil.ThepineandmixedforestsrespondedslowlytoNadditionsandexhibitednosignificantresponseofsoilcations.ResponseofsoilexchangeablecationstoNdepositionvariedintheforestsofsubtropicalChina,dependingonsoilNstatusandland-usehistory.

  • 标签: 交换性阳离子 亚热带森林 土壤酸化 森林类型 氮沉降 模拟
  • 简介:AfieldexperimentwasconductedonChinesecabbage(BrassicacampestrisL.ssp.pekinensis(Lour.)Olsson)inaNanjingsuburbin2003.Theexperimentincluded4treatmentsinarandomizedcompleteblockdesignwith3replicates:zerochemicalfertilizerN(CK);ureaatratesof300kgNha-1(U300)and600kgNha-1(U600),bothasbasalandtwotopdressings;andpolymer-coatedureaatarateof180kgNha-1(PCU180)asabasalapplication.Theacetyleneinhibitiontechniquewasusedtomeasuredenitrification(N2+N2O)fromintactsoilcoresandN2Oemissionsintheabsenceofacetylene.ResultsshowedthatcomparedtoCKtotaldenitrificationlossesweresignificantlygreater(P≤0.05)inthePCU180,U300,andU600treatments,whileN2OemissionsintheU300andU600treatmentsweresignificantlyhigher(P≤0.05)thanCK.IntheU300andU600treatmentspeaksofdenitrificationandN2OemissionwereusuallyobservedafterNapplication.Inthepolymer-coatedureatreatment(PCU180)duringtheperiod20to40daysaftertransplanting,higherdenitrificationratesandN2Ofluxesoccurred.Comparedwithurea,polymer-coatedureadidnotshowanyeffectonreducingdenitrificationlossesandN2OemissionsintermsofpercentageofappliedN.Astemperaturegraduallydecreasedfromtransplantingtoharvest,denitrificationratesandN2Oemissionstendedtodecrease.Asignificant(P≤0.01)positivecorrelationoccurredbetweendenitrification(r=0.872)orN2Oemission(r=0.781)fluxdensitiesandsoiltemperatureintheCKtreatmentwithastablenitratecontentduringthewholegrowingseason.

  • 标签: 氮肥 蔬菜 生长速度 施肥技术