简介:Anincubationexperimentwascarriedoutinlaboratorytostudytheeffectoftemperature,moisture,phosphorus,organicmatter,croppingandpreviouselementalsulfurapplicationonelementalsulfuroxidationinfourselectedsoils,fluvo-aquicsoil,blacksoil,yellow-brownsoilandredsoil,Inallthesoilstested,sulfuroxidationratewasinfluencedbytemperatureandthetemperaturecoefficient(Q10)valuesattherangefrom10to30℃were4.41,,6.19and3.71forthefoursoils,respectively.Therateofsulfuroxidationwasparabolicallyrelatedtosoilwatercontent.Theoptimummoisturecontentforthemaximumoxiationratewasdifferentamongsoils,Phosphorusincreasedtheoxidationrateofelementalsulfurby57.7%,33.1%,21.7%and26.4%fortheabovefoursoils,respectively,comparedwiththecontrol(nophosphorusapplied).Organicmaterialofcornstrawwhichwasgoundandpassedthrougha0.5-mmsievealsoincreasedthoxidationrateofelementalsulfurinthefoursoilsby59.8%,7.8%,39.2%and540.4%,respectively.Elementalsulfurwhichwasappliedpreviouslytosoilssignificantlyenhancedtheoxidationofelementalsulfursubsequentlyaddedandincreasedsulfur-oxidizingpopulationssuchasautotrophicelementalsulfuroxidizerswithpHoptimum6.8,autotrophicthiosufateoxidizerswithpHoptimum6.8,heterotrophicthiosulfateoxidizersandheterotrophicsulfateproducers.Croppinghadlittleeffectonelementalsulfur-oxidizingpotentialityofsoils.
简介:Methaneoxidationbypaddysoilsinaclosedsystemcouldbesimulatedbytheequationx=k1xo/(k1+k2x0)exp(k2t)-k2x0wherex0andxaretheCH4concentrationsattimezeroandt,respectively;k1andk2areconstantsrelatedtotheconstantoffirst-order-kinetics.AccordingtotheequationthechangeofsoilabilitytooxidizeCH4couldbeestimatedbytheequationAc=k2/k1(x0-x)x0k2/k1-1.TheresultsshowedthatthesoilabilitytooxidizeCH4varied,dependingontheinitialCH4concentration.HighinitialCH4concentrationstimulatedsoilabilitytoconsumeCH4,whilelowconcentrationdepressedtheablility.Thischaracteristicofpaddysoilseemedtobeofconsiderablesignificancetoself-adjustingCH4emissionfromfloodedricefieldsifthereexistoxicmicrositesinthesoil.
简介:Effectsofnitrogenfertilizer,soilmostureandtemperatureandtemperatureonmethaneoxidationinpaddysoilwereinvestigatedunderlaboratoryconditions.Additionof0.05gNkg^-1soilasNH4ClstronglyinhibitedmethaneoxidationandadditionofthesamerateofKClalsoinhibitedtheoxidationbutwithmoreslighteffect,suggestingthattheinhibitoryeffectwaspartlycausedbyincreaseinosmoticpotentialinmicroorganismcell,NotonlyNH4^+butalsoNO3^-greatlyaffectedmethaneoxidation.Ureadidnotaffectmethaneoxidationinpaddysoilinthefirsttwodaysofincubation,butstronginhibitoryeffectwasobservedafterwards.Methanewasoxidizedinthetreatedsoilwithanoptimummoistureof280gkg^-1,andair-dryinginhibitedmethaneoxidationentirely.Theoptimumtemperatureofmethaneoxidationwasabout30℃inpaddysoil.whilenomethaneoxidationwasobservedat5℃or50℃。