简介：Inrecentyears,especiallyinthesummerof2002,themostseriousforestfiresoccurredintheDaxinganMountainofHeilongjiangprovinceandInnerMongolia.TherehasbeenlongtimeseriousforestfireenvironmentinsummerinDaxinganMountain.Thegrassintheforestisscorchedforlongtimedroughtandthemoisturecontentoflitterandturflayerdecreaserapidly.Theaccumulationanddrynessoffuelbuildthesummerforestfireenvironment,whicharemajorcausedbyMeteorologicalenvironment....

简介：FifteenuplandsoilscollectedfromthemajorarableareasinNOrthChinawereusedtoassesstheavailabilityofsoilsulfur(S)toplantsinapotexperiment.SoilswereextractedwithvariousreagentsandtheextractableSwasdeterminedusingturbidimetricmethodorinductivelycoupledplasmaatomicemissionspectrometry(ICP-AES),respectively.Inaddition,mineralizableorganicS,organicS,N/Sratio,sulfuravailabilityindex(SAI)andavailablesulfurcorrectionvalue(ASC)insoilswerealsodetermined.TheSamoutextractedby1.5gL^-1CaCl2wasnearlyequivalenttothatby0.25molL^-1KCl(40℃),andbothofthemwereslightlysmallerthanthatby0.01molL^-1Ca(H2PO4)2solution,asmeasuredbyturbidimetricmethodorICP-AES.TheextractableSmeasuredbyturbidimetricmethodwasconsistentlysmallerthanthatbyICP-AES.AllmethodstestedexceptthatfororganicSandN/SratioproducedsatisfactoyresultsintheregressionanalysesoftherelationshipsbetweentheamountsofSextractedandplantdrymatterweightandSuptakeinthepotexperiment,Ingeneral,0.01molL^-1Ca(H2PO4)2-extractedSdeterminedbyICP-AESorturbidimetricmethodand0.25molL^-1KCl(40℃)-extractedSdeterminedbyICP-AESappearedtobethebestindicatorsforevaluationofsoilavailableS.

简介：EcosystemdegradationoccursinparallelwithdesertificationprocessinsandyareasofNorthChina.ThevastsandyareasinNorthChinaarecharacterizedwithflexibleenvironmentsandfragileecosystemsaswellasintensivehumanactivities.DuetotheannualprecipitationgradientdecreasesfromeasttowestinNorthChina,thewholesandyregionfallsinto3mainclimaticzones:add,semi-addanddrysub-humidzones.Theecosystemsineachtypeofclimaticzonesaredifferentinclimaticconditions,humanactivities,culturaldimensions,vegetationcovers,landscapes,andcausesandprocessesofecosystemdegradation.Therefore,themosteffectiverehabilitationmeasuresofdegradedecosystemsindifferenttypesoftheclimaticzonesarealsodifferent.Forthearidsandyareas,vegetationrehabilitationofdegradedecosystemsneedstobecompletelyclosed,assistingwithartificialmeasures,suchasplantation,irrigationorothers.Forsemi-addsandyareas,theeffectivemeasuresofvegetationrehabilitationofdegradedecosystemsincludeincreasingofproportionofforestsandrangelandsandlimitationofreclamation;reducingthecarryingcapacityoflivestockonunitareaofrangelandsandgrowthoffodderplants;andplantationonthelowlandsbetweensanddunes.Forthedrysub-humidareas,themosteffectivemeasureisenclosureofdegradedecosystemscombinedwithplantation,andinsomecases,juststopusesbygrazingorreclamation.

简介：比较方法和录象带录音机被使用以防为记录二个组操作符的操作表演的学习。时间跨度是7个月，从9月到三月。在9月的操作的表演作为参考书被拿。测试调查和数据分析的结果证明掉落树的手术效率被冷天气影响，适当地减少了18.5%在里面平均。

简介：Nitrogen(N)lossesfromammoniumbicarbonateorureaappliedtowheatandthenfollowedimmediatelybyirrigationwereinvestigated.Ammoniavolatilizationwasdeterminedbyamicrometeorologicalmethod(ammoniasampler),totalNlosswasestimatedbythe^15Nmassbalancemethod,anddenitrificationlosswasmeasuredbythediferencemethod(calculatedfromthedifferencebetweenthetotalNlossandammonialoss)andadirectmethod(measuringtheemissionof(N2+N2O)-^15N).Totalammonialossesfromammoniumbicarbonateandureain33dayswere8.7%and0.9%oftheappliednitrogen,respectively.ThecorrespondingtotalNlosseswere21.6%and29.5%,Apparentdenitrificationlosses(bythedifferencemethod)wereratherhigh,being12.9%fromammoniumbicarbonateand28.6%fromurea.However,noemissionof(N2+N2O)-^15Nwasdetectedusingthedirectmethod.

简介：ＣｏｎｔｏｕｒＰｌａｎｔｉｎｇ－ＡＳｏｃｉａｌＦｏｒｅｓｔｒｙＭｏｄｅｌｏｆＣｏｍｐｒｅｈｅｎｓｉｖｅＤｅｖｅｌｏｐｍｅｎｔｏｆＡｒｉｄＭｏｕｎｔａｉｎＲｅｇｉｏｎｓｉｎＮｏｒｔｈＣｈｉｎａＢｙＦｅｎｇＸｉａｏｊｕｎＩｎｔｈｅａｒｉｄ，ｍｏｕｎｔａｉ...

简介：Fieldexperimentswereconductedinamaize(ZeamaysL.)fieldofacalcareousfluvo-aquicsoilinNorthChinaPlainforstudyingthefateandammonialossofurea-Nappliedatseedlingstage,aswellastheeffectivenessofcoatedcalciumcarbide(CCC)inreducingNlossandinimprovingtheyieldefficiencyofurea.Resultsshowthat:(1)Forthesurface-broadcasttreatmentammoniavolatilization(measuredwithmicro-meteorologicaltechnique)tookplacequickly,reachedthepeak20-26hrafterapplication,andthendeclinedgradually;thecumulativeammonialossapproachedthemaximum188hrafterapplication(30%oftheNapplied),andincreasedonlyto32%284hrafterapplication;thelatteraccountedfor71%ofthetotalloss(45%ofappliedN).(2)Inthecaseofpointplacementatadepthof5-10cm,ammonialoss188hrafterapplicationwasonly12%oftheNapplied,accountingfor40%ofthetotalloss.(3)Therewasnodifferenceintotallossbetweentheapplicationdepthsof6cmand10cm,thelossofthemwas30%and29%,respectively.(4)TotallossofNappliedatlowerrate(40kgN/ha)withpointdeepplacementat6cmdepthwasfoundonly4%oftheNapplied,itroseupto30%whentherateofapplicationincreasedto80kgN/ha.(5)Thenitrificationinhibitor,CCC,seemedtoenhanceNlossofurearatherthanreduceit,anddidnotshowanybenefiteffectinimprovingtheyieldefficiencyofurea,whichispresumablyduetothehighpotentialofammoniavolatilizationinthesoilandclimaticconditionsunderinvestigation.

简介：MicrometeorologicalandmicroplotexperimentswereconductedinthefieldoffreshlyharvestedgreencaneinQueensland,Australia.ResultsshowedthathighammonialossoffertilizerNcouldoccurunderrelativelydryconditionswhenureaorcommercialproductofmixtureofureaandmuriateofpotashwereappliedtothesurfaceofsugarcanetrash.ThemoisturecontentinthetrashandthepHoffertilizerweretwoimportantfactorscontrollingtheprocessesofureahydrolysisandammoniavolatilization.MostoftheNinthesoilwastransformedtothenitratel-nitritefromafter70daysoffertilizerapplication.Nosignificantleachingwasfound.Urea-freeNfertilizershadhigherNrecoveriescomparedtourea-containingfertilizers.