Das et al.
exchangeableȱNH 4 + isȱrecordedȱinȱwaterloggedȱsystemȱ Comparativelyȱ higherȱ amountȱ ofȱ availableȱ Nȱ isȱ
overȱtheȱsoilȱmaintainedȱunderȱ60%ȱofȱtheȱmoistureȱ accumulatedȱinȱNȱtreatedȱoverȱtheȱuntreatedȱsystemȱ
holdingȱcapacityȱ(MHC)ȱatȱallȱstagesȱofȱincubation.ȱ (Tableȱ 4).ȱ Again,ȱ irrespectiveȱ ofȱ chloropyriphosȱ
Thisȱtrendȱofȱresultȱisȱobservedȱbothȱinȱpresenceȱandȱ treatmentȱ andȱ Nȱ fertilization,ȱ inȱ general,ȱ
absenceȱ ofȱ inorganicȱ Nȱ andȱ pesticidesȱ (endosulfanȱ comparativelyȱ higherȱ amountȱ ofȱ availableȱ Nȱ
andȱ chloropyriphos)ȱ addition.ȱ Higherȱ amountȱ ofȱ wasȱ recordedȱ inȱ waterloggedȱ overȱ thatȱ ofȱ theȱ
exchangeableȱ NH 4 + producedȱ inȱ waterloggedȱ soilȱ soilȱ maintainedȱ atȱ 60%ȱ ofȱ MHC.ȱ Theȱ explanationȱ
dueȱtoȱfasterȱrateȱofȱmineralizationȱofȱorganicȱNȱoverȱ furnishedȱearlierȱisȱequallyȱappreciableȱhereȱasȱwell.ȱ
unfloodedȱsituationsȱbutȱveryȱlittleȱisȱtransformedȱtoȱ Soilsȱmaintainedȱatȱ60%ȱofȱMHCȱandȱfertilisedȱwithȱ
NO 3 -ȱ formȱperhapsȱdueȱtoȱlowerȱNȱrequirementȱofȱtheȱ inorganicȱNȱshowedȱaȱdecreaseȱinȱavailableȱNȱoverȱ
microbialȱpopulationȱunderȱanaerobicȱenvironmentȱ theȱ experimentationȱ periodȱ isȱ dueȱ toȱ conversionȱ
andȱ toȱ theirȱ lowerȱ syntheticȱ efficiency (Sahaȱ andȱ ofȱexchangeableȱNH 4 + ȱtoȱotherȱformsȱofȱNȱandȱlossȱ
Mukhopadhyayȱ 1983b).ȱ Again,ȱ irrespectiveȱ ofȱ throughȱ volatilization (Broadbentȱ andȱ Tusneemȱ
N-additions,ȱ comparativelyȱ lowerȱ amountȱ ofȱ 1971)ȱ andȱ orȱ immobilizationȱ (Saharawatȱ 1982).ȱ
exchangeableȱNH 4 + isȱrecordedȱinȱwaterloggedȱsoilȱ Furthermoreȱ irrespectiveȱ ofȱ moistureȱ regimes,ȱ
treatedȱ withȱ higherȱ doseȱ ofȱ endosulfan,ȱ whereas,ȱ availableȱNȱincreasedȱupȱtoȱ30 th ȱdayȱinȱbothȱtheȱdosesȱ
almostȱ similarȱ amountȱ ofȱ exchangeableȱ NH 4 + isȱ ofȱChlorpyriphosȱtreatedȱsystems.ȱTheȱresultȱisȱatȱparȱ
recordedȱ inȱ waterloggedȱ soilȱ treatedȱ withȱ bothȱ withȱearlierȱworksȱofȱDasȱ(1997).ȱHowever,ȱafterȱ30ȱ
theȱ higherȱ andȱ lowerȱ dosesȱ ofȱ chloropyriphosȱ days,ȱaȱdecreasingȱtrendȱwasȱobservedȱupȱtoȱtheȱlastȱ
throughoutȱtheȱperiodȱofȱinvestigation.ȱHowever,ȱsoilȱ stageȱofȱincubation.ȱThisȱisȱbecauseȱofȱimmobilizationȱ
keptȱatȱ60%ȱMHCȱshowedȱanȱexactlyȱoppositeȱtrendȱ ofȱexchangeableȱNH 4 + ȱinȱsoil (Palȱ et al. 1987).
ofȱ resultsȱ bothȱ inȱ higherȱ dosesȱ ofȱ endosulfanȱ andȱ
Irrespectiveȱ ofȱ moistureȱ regimesȱ andȱ pesticidesȱ
chloropyriphos.ȱThusȱitȱisȱclearȱfromȱtheȱresultsȱthatȱ
addition,ȱinȱgeneral,ȱcomparativelyȱhigherȱamountȱofȱ
additionȱ ofȱ pesticidesȱ ofȱ differentȱ biodegradabilityȱ
totalȱhydrolysableȱNH + isȱaccumulatedȱinȱN-treatedȱ
4
hindersȱ theȱ ammonificationȱ processȱ particularlyȱ
overȱ theȱ untreatedȱ systemȱ throughoutȱ theȱ periodȱ
underȱwaterloggedȱsituationȱinȱpresenceȱofȱinorganicȱ
ofȱ investigationȱ (Tableȱ 5).ȱ Dataȱ alsoȱ revealȱ thatȱ inȱ
N (Okamotoȱ et al. 1999).
absenceȱofȱendosulfanȱbutȱpresenceȱofȱchloropyriphosȱ
Irrespectiveȱ ofȱ pesticidesȱ (endosulfanȱ andȱ andȱ inorganicȱ N,ȱ inȱ general,ȱ comparativelyȱ lowerȱ
chloropyriphos)ȱ addition,ȱ moistureȱ regimesȱ andȱ amountȱ ofȱ hydrolysableȱ NH 4 + -Nȱ isȱ recordedȱ inȱ
periodȱ ofȱ investigation,ȱ comparatively,ȱ higherȱ waterloggedȱ overȱ theȱ soilȱ maintainedȱ atȱ 60%ȱ ofȱ
amountȱofȱsolubleȱNO 3 -ȱ isȱaccumulatedȱinȱN-treatedȱ MHCȱinȱparticularlyȱatȱtheȱlaterȱstagesȱofȱincubation.ȱ
overȱ theȱ untreatedȱ systemȱ (Tableȱ 3).ȱ Inȱ general,ȱ Atȱlowerȱdoseȱofȱbothȱtheȱpesticides,ȱcomparativelyȱ
irrespectiveȱ ofȱ pesticidesȱ andȱ inorganicȱ N,ȱ higherȱ lowerȱ amountȱ ofȱ hydrolysableȱ organicȱ NH 4 + -Nȱ
amountȱ ofȱ solubleȱ NO 3 -ȱ isȱ recordedȱ inȱ soilȱ keptȱ atȱ wasȱ accumulatedȱ inȱ waterloggedȱ systemȱ overȱ theȱ
lowerȱmoistureȱregime.ȱHowever,ȱatȱtheȱlastȱstageȱofȱ soilȱkeptȱofȱ60%ȱMHC,ȱwhereas,ȱatȱhigherȱdoseȱnoȱ
incubation,ȱcomparativelyȱhigherȱamountȱofȱsolubleȱ definiteȱ trendȱ ofȱ resultsȱ wasȱ obtained.ȱ Conversionȱ
NO 3 -ȱ -Nȱ isȱ accumulatedȱ inȱ waterloggedȱ systemȱ ofȱhydrolysableȱNH 4 + -Nȱtoȱotherȱorganicȱformsȱandȱ
thanȱtheȱsoilȱmaintainedȱatȱ60%ȱMHCȱ(Tableȱ3).ȱTheȱ vice-versaȱ wasȱ suggestedȱ (Deviȱ 2009;ȱ Sahaȱ 1987).ȱ
higherȱdoseȱofȱendosulfanȱfavoursȱnitrificationȱevenȱ Thusȱitȱisȱclearȱthatȱintroductionȱofȱpesticidesȱinȱtheȱ
underȱ waterloggedȱ condition.ȱ Thisȱ findingȱ isȱ dueȱ systemȱslowedȱdownȱtheȱN-mineralizationȱprocessȱ
toȱlessȱscopeȱofȱlossȱofȱNȱthroughȱleachingȱasȱwellȱ (Ollivierȱ et al. 2011;ȱUkruȱ2005)ȱandȱmaintenanceȱofȱ
asȱdenitrification.ȱTheȱnitrificationȱprocessȱisȱfoundȱ lowerȱlevelȱofȱmoistureȱisȱcongenialȱforȱaccumulationȱ
toȱbeȱacceleratedȱatȱlastȱstageȱofȱincubationȱ(Saisonȱ ofȱhigherȱorderȱofȱhydrolysableȱNH 4 + ȱinȱsoilȱthroughȱ
et al. 2009).
inter-conversionȱofȱotherȱformsȱofȱorganicȱN.
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