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毕业论文外文资料翻译题目耕作方式与氮肥用量对土壤中有机物和氮的百分含量的影响学院资源与环境专业环境工程班级0701学生张学雷学号20070203070指导教师王惠二〇一一年三月二十日【原文】PakistanJournalofBiologicalSciences6(24):2017-2019,2003ISSN1028-88801M.S.Akter,2M.F.Hossain,3U.K.Majumder4M.S.I.Sikderand5M.M.A.A.Chowdhury1SoilAnalysisDivision,BangladeshRuralAdvancementCommittee(BRAC),Bangladesh济南大学毕业论文外文资料翻译2&4DepartmentofAgronomyand3DepartmentofStatistics,HajeeMohammadDaneshScienceandTechnologyUniversity,Dinajpur-5200,Bangladesh5SoilResourcesDevelopmentInstitute(SRDI),Dinajpur,BangladeshEffectofTillagePracticesandNitrogenRatesontheOrganicMatter(%)andN(%)ContentinSoilINTRODUCTIONTillageistheoldestandmostfundamentalactivityofhumanbeingforcropproduction.Differenttillageoperationsmayinfluenceorganicmatter,nitrogencontentandotherphysicalpropertiesofsoil(Singhetal.,1996).Theorganicmattercontentofthesoilimprovesthemainbiologicalandchemicalcapacitiesofthesoil.Growthpromotingsubstancesandenzymesinducecropgrowthandyieldandimprovethequantityoftheproduce.Theorganiccombinationofnitrogenwithorganicmatterinthesoilconstitutesthemajorstore-housefromwhichnitrogenisslowlymadeavailabletothecrop.Tillagetreatmentsignificantlyinfluencedtheorganicmattecontentofthesoiluptoadepthof0-30cm(Rahman,1977).Differentapplicationratesofnitrogeninfluencedonthetotal%Ncontentinsoil.Nitrogenplaysthekeyroleinplantnutrientanditsmanagementpracticesisanextremelyimportantaspectforcropproduction.OutofallnutrientstherequirementofNforplantisfarmorethanotherelements(Gilletal.,1978).Thesoilsoftropicalandsubtropicalzonesincludingallagro-ecologicalregionsofBangladeshareseriouslydeficientinnitrogen.Thismaybeduetolowleveloforganicmatterandcontinuouscroppingwithlittleornonitrogenfertilizerapplication.ThereforeorganicmatterandnitrogeninsoilcouldbeincreasedbypropertillageoperationalongwithoptimumNapplication.MATERIALSANDMETHODSTheexperimentwasconductedattheBangladeshAgriculturalUniversityFarm,Mymensinghduringamanseason,1998.ThesoilwassandyloamhavingpH6.9.Theexperimentwaslaidoutinsplit-plotdesignwiththreereplications.Threetillagetreatmentsarrangedtothemainplotandfournitrogenratestothesub-plots.Threetillagepractices,fournitrogenlevelswereusedinthisstudy(Table1).Theunitplotsizewas4.0x2.5m.TheexperimentalamanriceCV.BinashailplotswerefertilizedP2O5@40kgha•1K2O@33kgha•1withTSPandMPduringfinallandpreparation.Ureawastopdressedinthreeinstallmentsafter10,25and40daysaftertransplanting.Thesoilsamplesweretakenfromthreedifferentdepthandspotsattheareatomakeacompositsoilsamplebeforetransplantingandafterharvest.Thesampleswereairdriedandgroundtopassthrougha2mm(10mseh)sieve.Thegroundsamplewerestoredincleanplasticcontainersfor2济南大学毕业论文外文资料翻译chemicalanalysis.ThesoilsamplewereanalysedforthedeterminationofnitrogencontentinthelaboratoryofSoilScienceDepaartment,BangladeshAgriculturalUniversity,Mymensingh.NitrogencontentsofthesoilweredeterminedbymodifiedKjeldahlmethodafterdigestionwithcone.H2SO4,catalystmixture(K2SO4+CuSO4,5H2O+Scpowder,100:10:1)andH2O2andthendistillationwith10NNaOHsolution.TheammoniadistilledoverwasabsorvedinH3BO3indicatorsolutionandtitratedwith0.01NH2SO4(Jackson,1973).Theresultswereexpressedinpercentage.WetoxidationmethodwasfollowedtodeterminepercentageoforganiccarbonasdescribedbyBlack(1965)andtheorganicmatter...