Effect of moisture regimes and pesticides of different biodegradability on transformation
Table 1. General characteristics of the soil used for the
T 10ȱ =ȱT 2 ȱ+ȱChlorpyriphosȱatȱ1mgȱa.i.ȱkg -1
investigation
T 11ȱ =ȱT 10 ȱ+ȱNȱatȱ100ȱmgȱkg -1
Parameters
Characteristics
Soilsȱwereȱallowedȱtoȱincubateȱatȱroomȱtemperatureȱ
(30ȱ + 2) o ȱ Cȱ forȱ aȱ periodȱ ofȱ 60ȱ days.ȱ Fourȱ separateȱ
Sand (%)
22.07
setsȱ wereȱ maintainedȱ forȱ laboratoryȱ analysisȱ onȱ
Mechanical Separates
Silt (%)
33.88
0 th ,ȱ 15 th ,ȱ 30 th ȱ andȱ 60 th ȱ dayȱ ofȱ incubation.ȱ Samplesȱ
Clay(%)
44.05
ofȱallȱsetsȱwereȱidenticallyȱcollectedȱforȱanalysisȱofȱ
exchangeableȱNH 4 + ,ȱsolubleȱNO 3 - ,ȱtotalȱhydrolysableȱ
Moisture holding capacity (%)
49.45
organicȱ N,ȱ hexosamineȱ –ȱ N,ȱ hydrolysableȱ organicȱ
Bulk density (g c.c -1 )
1.22
NH 4 + ȱ-Nȱandȱaminoȱacidȱ-ȱN.ȱLossȱofȱmoistureȱdueȱ
pH
7.17
toȱ evaporationȱ wasȱ replenishedȱ byȱ theȱ additionȱ ofȱ
distilledȱwaterȱonȱeveryȱalternateȱdayȱbyȱdifferenceȱ
Electrical conductivity (dS m -1 )
0.35
inȱweight.
Cation exchange capacity [cmol (p + ) kg -1
11.39
2(M)ȱ KClȱ solutionȱ wasȱ employedȱ forȱ extractionȱ ofȱ
soil]
exchangeableȱNH 4 + ȱandȱsolubleȱNO 3 - ȱ-ȱNȱandȱwereȱ
Oxidisable organic carbon (%)
0.79
determinedȱbyȱtheȱmethodȱofȱBremnerȱandȱKeeneyȱ
Exchangeable NH + (mg kg -1 )
(1966).ȱExchangeableȱNH 4 + ȱsolubleȱNO 3 - ȱisȱconsideredȱ
4
111.194
asȱavailableȱNȱinȱtheȱtext.ȱDifferentȱformsȱofȱorganicȱ
Soluble NO 3 - (mg kg -1 )
52.595
NȱwereȱestimatedȱbyȱtheȱmethodȱofȱStevensonȱ(1996).
Available N (mg kg -1 )
163.789
Results and Discussion
Available Phosphorus (kg ha -1 )
68.08
Irrespectiveȱ ofȱ moistureȱ regimes,ȱ theȱ amountȱ ofȱ
Exchangeable potash (kg ha -1 )
334.58
exchangeableȱNH 4 + inȱsoilȱtendedȱtoȱdecreaseȱwithȱ
Nomenclature
according
to
USDA Aeric
Endo
increaseȱ inȱ theȱ periodȱ ofȱ investigationȱ (Tableȱ 2).ȱ
classification
Aquepts
Thisȱ trendȱ ofȱ resultsȱ isȱ observedȱ bothȱ inȱ presenceȱ
andȱ absenceȱ ofȱ inorganicȱ N.ȱ Theȱ decreaseȱ inȱ
Treatment adopted for the experiment may be
exchangeableȱ NH 4 + isȱ dueȱ toȱ lossȱ ofȱ Nȱ throughȱ
written as follows:
volatilization (BroadbentȱandȱTusneemȱ1971)ȱorȱdueȱ
toȱimmobilizationȱofȱNȱintoȱorganicȱforms.ȱHowever,ȱ
T 0ȱ =ȱSoilȱkeptȱatȱ60%ȱofȱM.H.C.
inȱpresenceȱofȱbothȱendosulfanȱandȱchloropyriphos,ȱ
T 1ȱ =ȱT 0 ȱ+ȱNȱatȱ100ȱmgȱkg -1
theȱamountȱofȱexchangeableȱNH 4 + tendedȱtoȱdecreaseȱ
uptoȱ15 th ȱday,ȱthereafterȱshowedȱanȱincreaseȱonȱ30 th
T 2ȱ =ȱSoilȱkeptȱunderȱwaterloggedȱcondition
dayȱfollowedȱbyȱdecreaseȱuptoȱ60 th ȱdayȱofȱincubation.ȱ
T 3ȱ =ȱT 2 ȱ+ȱNȱatȱ100ȱmgȱkg -1
Thisȱ trendȱ ofȱ resultȱ isȱ observedȱ irrespectiveȱ ofȱ
moistureȱ regimesȱ andȱ inorganicȱ Nȱ additions.ȱ Theȱ
T 4ȱ =ȱT 0 ȱ+ȱEndosulfanȱatȱ0.5mgȱa.i.ȱkg -1
suddenȱincreaseȱinȱexchangeableȱNH + onȱ30 th ȱdayȱ
4
T 5ȱ =ȱT 4 ȱ+ȱNȱatȱ100ȱmgȱkg -1
ofȱ incubationȱ isȱ perhapsȱ dueȱ toȱ spurtȱ inȱ activitiesȱ
ofȱ ammonifyingȱ bacteriaȱ (Dasȱ 1997).ȱ Dataȱ furtherȱ
T 6ȱ =ȱT 2 ȱ+ȱChlorpyriphosȱatȱ0.5ȱmgȱa.i.ȱkg -1
revealȱ thatȱ irrespectiveȱ ofȱ moistureȱ regimesȱ andȱ
T 7ȱ =ȱT 6 ȱ+ȱNȱatȱ100ȱmgȱkg -1
pesticideȱaddition,ȱcomparativelyȱhigherȱamountȱofȱ
T =ȱT ȱ+ȱEndosulfanȱatȱ1mgȱa.i.ȱkg -1
exchangeableȱNH 4 + isȱaccumulatedȱinȱtheȱN-treatedȱ
8ȱ
0
overȱtheȱuntreatedȱsystemȱthroughoutȱtheȱperiodȱofȱ
T 9ȱ =ȱT 8ȱ +ȱNȱatȱ100ȱmgȱkg -1
investigationȱ(Tableȱ2).ȱThisȱisȱtheȱeffectȱofȱN-addition.ȱ
Inȱ general,ȱ comparativelyȱ higherȱ amountȱ of
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