ContentslistsavailableatScienceDirect
Scientia
Horticulturae
j o u r n a l ho me p ag e :w w w . e l s e v i e r . c o m / l o c a t e / s c i h o r t i
Influence
of
farmyard
manure
application
and
mineral
fertilization
on
yield
sustainability,
carbon
sequestration
potential
and
soil
property
of
gardenpea–french
bean
cropping
system
in
the
Indian
Himalayas
Dibakar
Mahanta
a,∗,
R.
Bhattacharyya
b,
K.A.
Gopinath
c,
M.D.
Tuti
a,
Jeevanandan
K
a,
Chandrashekara
C
a,
Arunkumar
R
a,
B.L.
Mina
a,
B.M.
Pandey
a,
P.K.
Mishra
a,
J.K.
Bisht
a,
A.K.
Srivastva
a,
J.C.
Bhatt
aaVivekanandaInstituteofHillAgriculture(IndianCouncilofAgriculturalResearch),Almora263601,Uttarakhand,India
bIndianAgriculturalResearchInstitute,NewDelhi110012,India
cCentralResearchInstituteforDrylandAgriculture,Santoshnagar,Saidabad,Hyderabad500059,India
a
r
t
i
c
l
e
i
n
f
o
Articlehistory:
Received14April2013
Receivedinrevisedform23August2013 Accepted3October2013
Keywords:
Carbonsequestrationpotential Farmyardmanure
Soilcationexchangecapacity Soilcracking
Soiltemperature Sustainableyieldindex.
a
b
s
t
r
a
c
t
Sustainabilityofagriculturalsystemshasbecomeanimportantissueallovertheworld.Hence,
sustaina-bilityandclimateresilienceofgardenpea–frenchbeancroppingsystemwasevaluatedbyyieldtrends,C
sequestrationandemissionreductionandsoilpropertiesasaffectedbyfourapplicationratesoffarmyard
manure(FYM)(5–20tha−1)vis-à-vismineralfertilization,integratednutrientmanagement(INM)
prac-ticesas50%recommendedNPK+FYMat5tha−1andun-amendedcontrolaftersixyearsofcroppingin
theIndianHimalayas.Thehighestsustainableyieldindexof0.606wasachievedwiththeapplicationof
20tFYMha−1(FYM
20).ThecarbonsequestrationpotentialofFYM20plotswasabout459and193%more
thanNPKandINMplots,respectively.Thesameplotsreduced53and24%carbonequivalentemission
withcomparisontoNPKandINMapplication,respectively.Thesoilcationexchangecapacity(CEC)under
FYM20plotswas22and11%higherthanNPKandINMplots.ThesoilcrackingvolumeunderFYM20plots
(57cm3m−2area)wasverylesscomparedtoNPK(324cm3m−2area)andINM(154cm3m−2area)plots.
Themorningsoiltemperature(0–15cmdepth)incoldestweekoflastyearexperimentationunderFYM20
plotswasmoderatedby0.60and0.47◦CthanNPKandINMplots,respectively.Successiveincreaseof
FYMlevelimprovedsoilorganicC,microbialcolonyformationunit,dehydrogenaseactivity,bulk
den-sityandsoilcrackingsurfaceareaandthebestvaluesforallsoilpropertieswererecordedunderFYM20
plots.Applicationof20tFYMha−1produced54and29%highergardenpeaequivalentpodyieldofthe
systemthanmineralfertilizationandINM,respectively.Theprincipalcomponentanalysisrevealedthat
soilCECwasthemostimportantproperty(amongtheselectedsoilparameters)contributingtothepod
yield.Soilorganiccarbonmarkedlyimprovedothersoilpropertiesasevidentfromcorrelations.Organic
productionsystemwithFYM20tha−1couldberecommendedforclimateresilientsustainableyieldand
bettersoilpropertyofgardenpea–frenchbeancroppingsystemthanmineralfertilizationandINMinthe
IndianHimalayanregions.
©2013ElsevierB.V.Allrightsreserved.
1. Introduction
Adoptionofrecent agriculturalpracticesinvolvesoff-farmor
externalchemicalinputswhichreleaseCO2andothergreenhouse
gases(GHGs)toatmosphereduringproduction,transportationand
storage.Industrialagricultureinputscontributetonumerousforms
∗Correspondingauthorat:VivekanandaInstituteofHillAgriculture(Indian
Coun-cilofAgriculturalResearch),Almora263601,Uttarakhand, India.Tel.:+915962241005;fax:+915962241250.
E-mailaddress:dibakarmahanta@yahoo.com(D.Mahanta).
ofenvironmentaldegradation,includingairandwaterpollution,
soildepletionanddiminishingbiodiversityandsoilquality.Again
theincreaseinextremeclimaticvariabilityintheIndianHimalayan
regions(Pandayetal.,2009)isaddinguncertaintyofagricultural
productivity.Hence,sustainabilityofagriculturalsystemswithlow
orwithoutemissionofGHGshasbecomeanimportantissueallover
theworld.Conversely,organicsourcemayinfluenceagricultural
sustainabilitybyimprovingsoilquality(Sahaetal.,2008).Organic
farmingisincreasinglybecomingpopularbecauseoftheperceived
healthandenvironmentbenefits(Zhaoetal.,2009).Severalstudies
havereportedloweryieldsinorganicconditionswithcomparison
tomineralfertilizations(Astieretal.,1994;Gopinathetal.,2009;
0304-4238/$–seefrontmatter©2013ElsevierB.V.Allrightsreserved.
D.Mahantaetal./ScientiaHorticulturae164(2013)414–427 415
Liebhardtetal.,1989;MacRaeetal.,1990).Initiallyloweryields
onorganicfarmshavebeenattributedtothenegativeeffectsof
conventionalpracticesonthesoilmicroorganismsthatmineralize
soilorganicmatter,orthatcontrolsoil-bornepests(Martinietal.,
2004).But,theseorganicsystemsmayleadtomorebiological
activ-ityandimprovesoilqualitythanindustrialconventionalsystems
(CastilloandJoergensen,2001;Fliessbachetal.,2007;Garcia-Ruiz etal.,2008;Gopinathetal.,2009).Nutrientmanagementis,
there-fore,oneof themostcritical management practicesfor organic
growers.
Inthepastfivedecades,thetraditionalknowledgeand
prac-ticesoforganicfarminghavebeenalmosterodedfrommanyparts
ofIndiaduetoinfluxofmodern“greenrevolution”technologies
(Gopinathetal.,2009).However,formanyfarmers(especiallysmall
andmarginal)inHimalayas,thepurchaseofmanufactured
fertil-izersandpesticidesisandwillcontinuetobeconstrainedbytheir
highcostsand unavailability. Furthermore,useof locally
avail-ablenaturalresourcesandfarmers’knowledgearefarmorelikely
tomeettheneedsandaspirationsofresource-poorfarmersthan
thosethatrequirecostlyorscarceexternalinputs(Parrottetal.,
2006).Theworldorganicproductionsystemisconsideredtocover
anareaof37millionhectaresin162differentcountrieswith1.8
millionproducersandtheworldorganicmarketisestimatedat
morethan62.9billionUSdollarsin2011(Willeretal.,2013).This
organicmarketexpansionmakesitpossibleforHimalayanfarmers
toemergeasmajorsuppliersoforganicproductswithhighprice
premiums(Gopinathetal.,2009).Againthepercapitalivestock
populationinIndianHimalayanstatesisveryhighthanaverage
ofIndia(Anonymous,2012;Anonymous,2011).Thiswillhelpin
producingmoreorganicmanuresinthesestatesandcanfulfillthe
demandoforganicmanurefortheorganicproducerstocontinue
organicagriculture.Theorganicmanuresproducedfromlivestock,
ifnotutilizedwilladdGHGstotheenvironment.
VegetablefarmersinIndianHimalayasmostlyapplyfarmyard
manure(FYM)asnutrientsourceinorganiccultivation.However,
thereislimitedresearchontheeffectsofapplicationofhigherlevel
ofFYMvis-à-vismineralfertilization(recommendedNPKonly)and
integratednutrientmanagement(INM;50%oftherecommended
NPK+5tFYMha−1) onyield of crops,sustainability of cropping
systemandsoilquality(soilphysical,chemicalandbiological
prop-erties).Gardenpeaandfrenchbeanaretwoimportantleguminous
vegetablescultivatedinnorth-westernHimalayasofIndia.Hence,
wechosetoevaluatetheinfluenceofFYMongardenpea(Pisum
sativumvar. hortense L.)and frenchbean(PhaseolusvulgarisL.)
yieldtrendsintheIndianHimalayasaftersixyearsofcropping.The
hypothesisofthestudywere(i)Mediumterm(6years)
continu-ousmanureapplicationunderayear-roundvegetableproduction
systemwouldstoremoreCinsoilandreduceemissionofCO2and
wouldhavehighersustainableproductivitycomparedwith
min-eralfertilizationandINM;(ii)Constantmanuringwouldmoderate
winterandsummersoiltemperaturesbetterthanINMalongwith
improvementinsoilproperty,therebywouldhavethepotential
toadaptandmitigatetheclimatechangeimpacts intheIndian
Himalayas.Theobjectivesofthestudywere(i)tofindoutthemost
sustainablenutrientmanagementpracticesforgardenpea–french
beancroppingsystem;(ii)toestimatethecarbonsequestration
potentialofFYMandmineralfertilization and(iii)toassessthe
effectsofdifferentlevelsofFYMvis-à-vismineralfertilizationand
INMonselectedsoilproperties.
2. Materialsandmethods
2.1. Experimentalsiteandagronomicpractices
Thefieldexperimentwasconductedduring2002–2008atthe
experimental farm of Vivekananda Instituteof Hill Agriculture
Table1
Physicalandchemicalpropertiesoffarmyardmanure(meanofsixyears).
Particulars Characteristics
Color Brownishblack
Basicorganicmaterial Cattledungandurine+left-over materialoffodder+litter
Texture Smalllumps
bWaterholdingcapacitywasthedifferenceofmoisturecontentbetween−0.33
and−15barpressure.
c FYM:Moisture=1:5.
locatedintheIndianHimalayanregionatHawalbagh(29◦36′N
and79◦ 40′ Eand1250mabovemeansealevel)inthestateof
Uttarakhand,India.Thesoilwassiltyclayloam(TypicHaplaquept)
with the following characteristics in 0–15cm depth: pH 6.1
(1:2.5soil:watersuspension),easilyoxidizable(K2Cr2O7+H2SO4)
organicC11.3gkg−1,alkalineKMnO
4oxidizableN179.9mgkg−1,
0.5M NaHCO3 extractable P 6.79mgkg−1 and 1.0N NH4OAc
exchangeableK80.4mgkg−1soil.
Theclimaticconditionsattheresearchfarmindicatesthatthe
extremetemperatureconditionisincreasingi.e.minimum
temper-atureisdecreasingandmaximumtemperatureisincreasingover
theyears(Pandayetal.,2009;Pandayetal.,2003).Thefrequency
ofseveredroughtsastonishinglyincreasedfrom1.39to3.75years
outof10years(Pandayetal.,2009).
Thefieldexperimentconsistedofseventreatmentsandwaslaid
outinarandomizedcompleteblockdesignwiththreereplications
inafixedplot.ThetreatmentswerefourratesofFYMapplicationi.e.
5tha−1(FYM
5),10tha−1(FYM10),15tha−1(FYM15)and20tha−1
(FYM20),mineralfertilization asrecommendedNPK(NPK), INM
(50% recommended NPK as mineral fertilizer+FYM at 5tha−1)
and unfertilized control.All organicamendments were applied
onadry-weightbasis.Thenatureandcomposition(physicaland
chemical properties)of FYMwere analyzed prior to
incorpora-tionintoexperimentalplotsanddepictedinTable1.Themineral
fertilizersinNPKandINM(recommendedlevel:20-26.2-33.3kg
N-P-Kha–1forgardenpeaand50-30.6-41.7kgN-P-Kha−1forfrench
bean)wereappliedatthesowingtimeandthesourcesfor N,P
andK wereurea, singlesuperphosphateandmuriate ofpotash,
respectively.
2.2. Yielddatacollectionandsustainableyieldindex
Atharvestingtime,marketablegreenpodswerepickedin
dif-ferentphasesduringtheharvestingperiodforestimationofyield
parameterssuchaspodnumberperplant,podlength,and pod
yield (tha−1). Randomsamples of five plants were taken from
each plot for recording pod number plant−1 and plant height.
Podnumbersoftheseselectedplantswerecountedbysumming
fromfirstpickinguptothelastpicking.Plantheightwasrecorded
atthetimeof lastpickingofpods.Pod lengthwasrecordedby
averaging 20 pods in different pickingsof selected five plants.
The pod yield of netplot size of 3.0m×3.0mfrom gross plot
sizeof3.6m× 3.0mwasconsideredforestimationofpodyield
ha−1.
Observations were recorded onpod yield of gardenpea and
frenchbean.Thepodyieldoffrenchbeanwasconvertedinto
Fig.1.Weeklysoilminimumandmaximumtemperatureoflasteightyearsfrom theresearchfarmoftheexperiment.
frenchbeanandgardenpeaasfollows:
Gardenpeaeconomicequivalentyieldoffrenchbean
=(Yfb×Pfb)/Pgp (1)
whereYfbisthepodyieldoffrenchbean,Pfbisthepriceoffrench
bean,andPgpisthepriceofgardenpea.Thepricet−1offrenchbean
variedfromUS$400to500andthatofgardenpeafromUS$240to
360indifferentyears.
Minimumguaranteedyieldthatcouldbeobtainedrelativeto
maximumobservedyieldovertheyearsofgardenpea–frenchbean
croppingsystemwasquantifiedthroughsustainableyieldindex
(SYI),whichwascalculatedbythefollowingexpression(Singhetal.,
1990):
SYI=(Ya−)/Ym (2)
whereYaisthemeanyield,‘’thestandarddeviationofyieldfor
thattreatmentacrossyears,andYmisthemaximumyieldobtained
underthattreatmentinanyyear.IntheconceptofSYI,lowvalues
ofsuggestsustainabilityofthesystem(Efthimiadouetal.,2010),
becausemeasuresvariationinyieldcausedbysoilparameters
andclimaticfactors.Ifishigh,SYIwillbelowandthisindicates
unsustainablemanagementpractice(Singhetal.,1990).The
near-nessofSYIto1.0impliestheclosenesstoanidealsituationthatcan
sustainmaximumcropyieldsoveryears,whiledeviationfrom1.0
indicatesthelossestosustainability.
2.3. Soilphysicalproperties
Bulkdensity(BD,Mgm−3)ofthesurface(0–15cm)soillayerwas
determinedusingacoresampler(diameter7cmandheight8cm).
Thegravimetricwatercontentofthesoilinthesesleeveswas
deter-minedondryingat105◦C.Plantavailablewatercapacity(PAWC)
wasdeterminedasthedifferenceofpercentagewatercontentat
fieldcapacity(0.03MPa)andpermanentwiltingpoint(1.5MPa)
usingapressureplateapparatusmethod.Thewaterinfiltrationrate
(IR)wasmeasuredusingtapwaterateachoftheplotsonthesoil
surfaceusingadoubleringinfiltrometerwitha27cmouter
diame-teranda15cminnerdiameter,untilaconstantratewasachieved.
Soiltemperaturewasrecordedwiththehelpofsoilthermometer.
Theprevalenceofweeklysoilminimumandmaximum
tempera-tureoftheyearacrosslasteightyearsfromtheresearchfarmof
theexperimenthasbeendepictedinFig.1.Soiltemperaturewas
recordedinlastyearoftheexperimentduringcoldestandhottest
weekoftheyear.Thecoldestandhottestweekswerechosenonthe
basisofmeanoflastsixyearsatmospherictemperature.The
morn-ingtemperatureandafternoontemperaturewererecordedat6:45
AMand2:15PM,respectivelyduringcoldestseasonweek(January
secondweek)andat5:00AMand2:15PM,respectivelyduring
hottestseasonweek(22ndweekoftheyear–May27toJune2).
Thetemperaturedifferenceofthedaywascalculatedby
subtrac-tingmorningtemperaturefromtheafternoon.Themoderationof
soiltemperaturewasestimatedasdifferenceofsoiltemperature
betweentreatedandun-amended controlplotsduringmorning
andafternoonforcoldestandhottestweekofyear,respectively.
Fordeterminationofsoilcrackvolume(SCV)andsoilcrack
sur-facearea(SCSA),eachexperimentalplotwasdividedintofourparts
andsquaresof1m×1mweredemarcatedineachpart.Within
eachofthesesquares,cracklengthapparentonthesoilsurface
wasmeasuredbyaflexibletwinerunalongthecrackand
measur-ingthetotallengthofallthecracksinthe1m×1m(Dasogand
Shashidhara,1993).Theaveragedepthandwidthofcrackswere
basedonmeasurementsmadeat0.5mintervalalongthecourse
ofthecrack.Thecrackdepthwasmeasuredbya2mmdiameter
steelrodinserteduntilitofferedresistancetofurtherpenetration,
whilethewidthatthesamepointasthatofdepthrecordingwas
measuredwithanadjustabledividerat1cmbelowthesoilsurface
(Dasogetal.,1988).Adepthof1cmwaschosentoavoid
exagger-atedwidthscausedbysurfacedisturbance.Totalvolume(SCV,cm3)
andsurfacearea(SCSA,cm2)ofeachcrackwascomputedusing
thefollowingequationsassumingtriangularshapeofthecracks
(Bandyopadhyayetal.,2003;Sharmaetal.,1995):
SCV=
0.5wdl; (3)SCSA=
2Cl; (4)C=[(0.5w)2+d2]1/2 (5)
wherewisthemeanwidthofcracks(cm),dthemeandepthof
thecrack(cm),lthelengthofthecrack(cm),andCtheparameter
basedonwandd.
2.4. Soilbiologicalproperties
Microbialpopulationofthesoilattheendoftheexperimentwas
enumeratedbythesoildilutionplatemethod(Seeleyetal.,1991).
Nutrient,roseBengal,KenknightagarandTrichodermaselective
medium(TSM)wereusedforbacteria,fungi,actinomycetesand
Trichoderma species counts, respectively. To suppress bacteria,
streptomycin(30ppm)wasadded tonutrient agar.Inthe
con-ventionaldilution-plateprocedure,1gofsoilwasaddedto10ml
sterilewaterandtenfolddilutionwereprepared.Fromthe
result-ingsuspensionportionsof0.1mlofrespectivedilution(upto10−7,
10−5,10−4 and10−3 fortotalbacteria,fungiactinomycetesand
Trichodermaspecies,respectively)werespreadwiththeaidofa
Drigalskylooponthesurfaceof agarplates containing25mlof
Nutrient,RoseBengal,KenknightagarandTSMmedium.Theplates
wereincubatedat28◦Cforaweekandcolonyformationunitswere
recorded.
Soildehydrogenase activitywasestimated byreducing 2, 3,
5-triphenyltetrazolium chloride(TTC)(Casida etal., 1964).Five
gramsofsoilsampleweremixedwith50mgofCaCO3 and1ml
of3% (w/v)2,3, 5-triphenyltetrazoliumchloride andincubated
for24hat37±1◦C.DehydrogenaseenzymeconvertsTTCto2,3,
5-triphenylformazan(TPF).TheTPFformedwasextractedwith
ace-tone(3×15ml),theextractswerefilteredthroughWhatmanNo.5
andabsorptionwasmeasuredat485nmwithaspectrophotometer.
Acidphosphatasewasassayedusing1gsoil(wetequivalent),
D.Mahantaetal./ScientiaHorticulturae164(2013)414–427 417
p-nitrophenylphosphate(Tabatabai and Bremner,1969).After
incubationfor1hat37±1◦C,theenzymereactionwasstoppedby
adding4ml0.5MNaOHand1ml0.5MCaCl2topreventdispersion
ofhumicsubstances.Theabsorbancewasmeasuredinthe
super-natantat400nm;enzymeactivitywasexpressedasgp-nitro
phenolreleasedg−1soilh−1.
2.5. Soilchemicalproperties
Soilsampleswerecollectedfrom0–15cmdepthattheendofthe
6thcroppingcycle.SoilpHwasdeterminedin1:2.5soil:water
sus-pensionaftershakingfor30min.Thesesoilsampleswereanalyzed
fororganicC bywetdigestionusingK2Cr2O7 and concentrated
H2SO4 (WalkleyandBlack, 1934).Soil organicC concentrations
wereconvertedfromgkg−1toMgCha−1usingmeasuredsoilBD.
Cation exchange capacity (CEC) of thesoil wasdetermined by
leachingthesoilwithKClfollowedbyextractionofexchangeable
K+ byNH
4OAcand K+ in solutionwasdetermined
flamephoto-metrically(Rhoades,1990).Carbonsequestrationpotential(CSP;
Mgha−1year−1)ofa particulartreatmentwascalculatedbythe
followingrelationship(Bhattacharyyaetal.,2009):
CSP=(SOCfinal−SOCinitial)/n (6)
whereSOCfinalandSOCinitialrepresentSOCcontent(MgCha−1)
attheendofexperimentandinitialplots,respectively,and‘n’
indi-catesyearsofexperimentation.SoilorganicCbudgetingforthe
studiedsystemswasdoneas:
SOCbuilduprate(MgC ha−1year−1)
=(SOCtreatment−SOCcontrol)/n (7)
where SOCtreatment and SOCControl represent SOC content
(MgCha-1)intheFYMormineralfertilizerappliedplotsand
unfer-tilisedcontroltreatment,respectively.
Soilorganiccarbon(SOC)storedinthesoilindirectlyreducesthe
emissionofCO2 toatmosphere.CO2emissionreductionthrough
SOCstockwasestimatedbythefollowingformula:
CO2 emissionreductionthroughSOCstock(Mgha−1)
=(SOCamounttreatment−SOCamountcontrol)×3.67 (8)
TheC emissionforproduction,packaging,storageand
distri-butionoffertilizersare1.3kgcarbonequivalentgreenhousegas
emission(CE)/kgN,0.2kgCE/kgP2O5and0.15kgCE/kgK2O(Lal,
2004).TheCEofFYMisestimatedat0.15kg/kgN.TheCEcanbe
convertedtoCO2equivalentbymultiplying3.67.
2.6. Statisticalanalysis
StatisticalanalysisofthedatawasdonebyusingAnova
tech-niqueandfollowingSPSS10.0andSAS9.2software.Thetreatment
meanswerecomparedatP<0.05levelofprobabilityusingstudent
t-testandworkingoutLSDvalues.Formultifactorialcomparison,
principalcomponentanalysis(PCA)andagglomerative
hierarchi-calclustering(AHC)wereusedtodisplaythecorrelationbetween
thevariousparametersandtheirrelationshipwiththedifferent
nutrientmanagementpractices.Varimaxrotationwasperformed
toproduceorthogonaltransformationstothereducedfactorsto
identifythehighandlowcorrelationsbetter.Multifactorialanalysis
wascarriedoutusingtheXLSTATsoftware(XLSTAT2010).
3. Results
3.1. Yieldattributesandpodyield
Gardenpea and french bean showed significant response to
additionalnutrientsthroughFYM.Thehighestpodnumbersper
plantwererecordedintheplotsunderFYM15andFYM20for
gar-denpeaandfrenchbean,respectively(Table2).Theseapplications
producedsignificantlyhighernumberofpodsperplantthanother
treatments,exceptFYM20andFYM15treatedplotsforgardenpea
andfrenchbean,respectively.PlotsunderFYM15ingardenpeahad
34and18%higherpodsperplantthanNPKandINMtreatedplots,
respectively,whileFYM20treatedplotsunderfrenchbeanhad36
and22%higherthanNPKandINMtreatedplots,respectively.The
similartrendswerealsoobservedforpodlengthandplantheight
forrespectivecrops.
Thehighestmeanpodyieldofgardenpeawasobservedinthe
plotsunderFYM15(Table3).ThepodyieldofFYM20andINMplots
weresimilartoFYM15forgardenpeacrop.But,inthecasesoffrench
beanandtotalgardenpeaequivalentyieldofthesystem,the
high-estproductivitywasrecordedintheplotsunderFYM20.Twocrops
arerespondingtotwodifferentapplicationratesofFYM.Hence,we
haveconsideredtheyieldoftotalsystemforevaluation,asFYMhas
residualeffectfordifferentcropseasonsandtwodifferent
appli-cationratescannotberecommendedfortwocropsinasystem.
Thehighestproductivityofgardenpeaequivalentyieldofsystem
wasobservedunderFYM20,whichprovided54and29%higherpod
yieldthanNPKandINMtreatedplots,respectively.
3.2. Sustainableyieldindex
TheSYIofthecroppingsystemcontinuedtoincreasewith
suc-cessivelevelsofFYMandthehighestvalueof0.606wasrecorded
underFYM20comparedwith0.525and0.549underNPKandINM
treatedplots,respectively.Similartrendswereobservedforboth
crops(Table3).
3.3. Soilphysicalproperties
ThesoilBDdecreasedsignificantlyinalltreatmentscompared
withthecontrolplots(Table4).TheBDofplotsunder20tFYMha−1
(1.34Mgm−3)waslowerby0.04Mgm−3 and0.07Mgm−3 from
NPK and control plots, respectively after six years. PAWC was
clearlyimprovedbyfertilization(Table4).TheFYM20treatment
(15.75%PAWC)showedagainof5.18and0.79%availablemoisture
inthe0–15cmsoillayerovertheplotsunderNPKandINM
treat-ments,respectively.AdditionofFYMtomineralfertilization(INM)
improvedPAWCby42%overplotsunderNPK.
AlltreatmentssignificantlyreducedtheSCVandSCSAthanthe
unfertilizedcontrolplotsandthelowestvaluewasrecordedwith
applicationof20tFYMha−1forbothparameters.Thedecreasein
SCVunderFYM20plotswasby82and63%overNPK(324cm3m−2
surfacearea)andINM(154cm3m−2 surfacearea)plots,
respec-tively.TheplotsunderFYM20had83and63%lessSCSAthanNPK
(3111cm2m−2surfacearea)andINM(1424cm2m−2surfacearea)
treatedplots,respectively.
TheIRincreasedsignificantlywiththeapplicationofFYM,
min-eralfertilizerandINMthancontroltreatment.Thehighestvalueof
IR(1.06cmh−1)wasrecordedwiththeapplicationof20tFYMha−1.
INMsignificantlyincreasedtheIRcomparedtoNPKonly.There
wereimprovementsof0.39and0.14cmh–1IRsunderFYM
20over
NPKandINMtreatedplots,respectively(Table4).
Themorningsoiltemperatureofcoldestweek(secondweekof
January)increasedsignificantlyinalltreatmentscomparedtothe
controlplots.ThesoiltemperatureunderFYM20plots(10.78◦C)
Table2
Effectoffarmyardmanure(FYM)onyieldattributesofgardenpeaandfrenchbean(meanofsixyears).
Treatmentsa Gardenpea Frenchbean
Podnumberplant−1 Podlength(cm) Plantheight(cm) Podnumberplant−1 Podlength(cm) Plantheight(cm)
Control 6.53 6.29 43.6 7.6 10.5 31.9
FYM5 8.35 6.69 56.2 9.6 11.9 44.0
FYM10 9.54 6.86 63.7 11.7 12.6 51.3
FYM15 11.09 7.18 70.1 12.8 12.9 54.2
FYM20 11.02 7.10 68.1 13.7 13.2 57.2
NPK 8.30 6.69 55.8 10.1 12.3 46.5
INM 9.43 6.84 62.7 11.2 12.5 50.4
SEM± 0.36 0.07 1.9 0.5 0.2 1.6
LSD(P=0.05) 1.05 0.20 5.6 1.4 0.6 4.6
aSeeSection2fortreatmentdetails.LSD=Leastsignificantdifference.SEM=Standarderrorofmean.
Table3
Mean(ofsixyears)productivityandsustainabilityofgardenpea–frenchbeancroppingsystemunderdifferentnutrientmanagementpracticesintheIndianHimalayas.
Treatmentsa Meanpodyield(tha−1) Sustainableyieldindex
Gardenpea Frenchbean Gardenpeaequivalent yieldoftotalsystem
Gardenpea Frenchbean Gardenpea–french beancroppingsystem
Control 3.42 4.12 10.04 0.637 0.318 0.472
FYM5 6.04 8.93 20.12 0.676 0.399 0.482
FYM10 7.60 11.19 25.18 0.680 0.436 0.521
FYM15 9.12 12.83 29.24 0.682 0.486 0.564
FYM20 8.90 14.44 31.47 0.705 0.517 0.606
NPK 5.96 9.14 20.49 0.615 0.381 0.525
INM 7.07 10.97 24.36 0.684 0.466 0.549
SEM± 0.37 0.75 1.07 – – –
LSD(P=0.05) 1.06 2.16 3.08 – – –
aSeeSection2fortreatmentdetails.LSD=Leastsignificantdifference.SEM=Standarderrorofmean.
plots.TheFYM20treatmenthadasignificantdecreasein
temper-atureinthe0–15cmsoillayerovertheplotswithNPKandINM
duringafternoon ofthecoldest and hottestweekand morning
temperatureofthehottestweek.Thetemperaturedifference
dur-ingthedaywaslowestwithapplicationof20tFYMha−1 among
othernutrientsourceplots.Itindicatesthatthediurnalvariation
intemperatureislowwithapplicationofhighrateofFYM(FYM20)
comparedtoNPKandINMtreatedplots.
3.4. Soilbiologicalproperties
Ingeneral,itwasobservedthatcontinuousapplicationofFYM
hadabeneficialeffectonthepopulationlevelsoftotalbacteria,
fungi,actinomycetes and Trichoderma spp. in the surface layer
(0–15cm)ofsoilaftersixyearsofcropcycle(Table5).Theleast
populationwasrecordedintheunfertilizedcontrolplotsfor
afore-mentionedmicrobes.PlotsunderFYM20hadthehighestbacterial
population(3.92×107colonyformationunitsg−1soil),whichwas
significantlyhigherthanthepopulationlevelsrecordedintheplots
underNPKandINM.ThefungalpopulationunderFYM20(5.18×105
colonyformationunitg−1soil)were350and27%higherthanthe
plotsreceivingNPKandINM,respectively.Itwasfurtherobserved
thattheplotsunderFYM20recordedsignificantlyhigherlevelsof
actinomycetes(140and 48%higherthanNPK andINM,
respec-tively)and Trichodermaspp.(304and60%higherthanNPKand
INM,respectively).Therewasatleast150%increaseinmicrobial
populationwithadditionofFYMtomineralfertilizer over NPK
alone.
Basically, the enzyme involved in intracellular microbial
metabolism,i.e.,dehydrogenaseandtheenzymeresponsiblefor
solubilizingPfromsoili.e.acidphosphatase,increasedwith
appli-cationofFYM,mineralfertilizerandINM(Table5).Dehydrogenase
and acidphosphatase activity increasedwith each incremental
applicationofFYMandthehighestactivitiesoftheseenzymeswere
estimatedwithapplicationof20tFYMha−1amongalltreatments.
ThedehydrogenaseactivityunderFYM20plotswere93and26%
Table4
Effectsoffertilizationonsoilphysicalpropertiesaftersixyearsofirrigatedgardenpea–frenchbeancroppingsystem.
Treatmentsa BD (Mgm−3)b
PAWC (%)
SCV (cm3m−2area)
SCSA (cm2m−2area)
IR (cmh−1)
Soiltemperatureduringthelastyearofexperimentation(◦C)
Coldestweekofyear Hottestweekofyear Temperature difference withinyear Morn AN Tempdiff Morn AN Tempdiff
Control 1.41 8.89 401 4232 0.63 11.0 15.1 4.07 24.2 29.1 4.87 13.6
FYM5 1.37 10.09 186 1819 0.73 11.6 14.3 2.67 23.8 27.6 3.80 12.8
FYM10 1.36 11.84 206 1990 0.77 11.9 14.0 2.17 23.6 25.9 2.30 11.8
FYM15 1.35 14.09 177 1974 0.97 12.1 13.6 1.53 23.6 24.6 1.03 11.3
FYM20 1.34 15.75 57 531 1.06 12.5 13.3 0.77 23.5 24.1 0.60 10.9
NPK 1.38 10.57 324 3111 0.67 11.9 14.3 2.43 24.0 27.0 3.03 12.4
INM 1.35 14.96 154 1424 0.92 12.0 13.6 1.57 23.7 24.8 1.10 11.4
SEM± 0.005 0.79 15 101 0.004 0.1 0.1 0.1 0.3
LSD(P=0.05) 0.014 2.43 45 310 0.012 0.4 0.4 NS 0.9
aSeeSection2fortreatmentdetails.LSD=Leastsignificantdifference.SEM=Standarderrorofmean.
b BD=Bulkdensity;PAWC=Plantavailablesoilwatercapacity;SCV=Soilcrackvolume;SCSA=Soilcracksurfacearea;IR=Infiltrationrate;Morn=morning;AN=Afternoon;
D.Mahantaetal./ScientiaHorticulturae164(2013)414–427 419
Table5
Effectsoffertilizationonsoilbiologicalpropertiesaftersixyearsofirrigatedgardenpea–frenchbeancroppingsystem.
Treatmentsa Microbialpopulationcount(CFUbg−1soil) Soilenzymaticactivity
Bacteria (×107)
Fungi (×105)
Actinomycetes (×104)
Trichoderma spp.(×103)
Dehydrogenaseactivity (gTPFg−1soil24h−1)
Acidphosphataseactivity (gPNPg−1soilh−1)
Control 1.10 1.09 6.85 1.14 67.5 994
FYM5 1.72 2.11 12.59 2.08 78.7 1038
FYM10 1.91 3.26 13.45 2.59 103.9 1142
FYM15 2.68 4.59 22.73 4.45 127.1 1249
FYM20 3.92 5.18 27.15 4.96 148.1 1410
NPK 1.68 1.15 11.32 1.23 76.7 1031
INM 2.62 4.09 18.28 3.11 117.7 1238
SEM± 0.16 0.19 0.84 0.16 7.1 64
LSD(P=0.05) 0.50 0.59 2.60 0.48 21.9 197
aSeeSection2fortreatmentdetails.LSD=Leastsignificantdifference.SEM=Standarderrorofmean. bCFU=Colonyformingunit.
higherthanNPKandINMtreatedplots,respectively.About37and
14%higheracidphosphataseactivitieswererecordedundersoils
ofFYM20thanNPKandINMtreatments,respectively.
3.5. Soilchemicalproperties
ApplicationofFYM,mineralfertilizer(NPK)andintegrationof
bothorganicandmineralsourceofnutrients(INM)significantly
influenced all selected soil chemical properties in the 0–15cm
depth(Table6).ApplicationofNPKrecordedthelowestsoilpH
value(5.64),whichwas0.46(7.5%)lowerthantheinitialvalue.
AdditionofFYMtomineralfertilizerimprovedthesoilreactionin
INM.ThesoilpHincreasedsignificantlyinallplotstreatedwith
FYMcompared withmineralfertilization. Applicationof FYM20
recordedthehighest soilpHvalue(6.85)and wasnearneutral
range,whichwas∼21.5%higherthanNPKplots.ThepHincreased
from6.65to6.85asthelevelofFYMapplicationincreasedfrom5
to20tha−1.
SOCisanoverallindicatorofsoilquality(Lopezetal.,2012).
SoilorganicCconcentrationsdecreased fromtheirinitialvalues
intheplotsunderunfertilizedcontrol.SoilsunderFYM20
treat-ment(13.2gCkg−1)contained14.1and9.3% higherSOC inthe
0−15cm soil layercompared withNPK and INMtreated plots,
respectively.TheSOCconcentrationincreasedwithevery
succes-siveincrementofFYMapplicationfrom5 to20tFYMha−1.The
amountofSOCunderFYM20 plots(26.6Mgha−1)wasincreased
by2.6and2.1Mgha−1comparedtoNPKandINMtreatedplots.
AlltreatmentssignificantlyimprovedsoilCECthancontrolplots,
exceptplotsunderNPK.ApplicationofFYM20recordedthe
high-est soil CEC value (13.03cmolkg−1), which was 2.5 (24%) and
1.23cmolkg−1 (10%) higher than NPK and INM plots,
respec-tively.
Carbon sequestration potential(CSP), defined as therate of
increaseinSOCcontentovertheinitialsoilinthe0–0.15msoil
depth, ranged from −0.534MgCha−1year−1 in theunfertilized
controlplotsto0.527MgCha−1year−1 intheplotsunderFYM
20
(Fig.2).CSPwasnegativeintheunfertilisedcontrolplots.TheCSP
ofFYM20plotswasabout0.433and0.347MgCha−1year−1more
thanNPKandINMplots,respectively.Therewasanincreasenet
build-uprateoftotalSOCintheplotsunderFYM20,themean
mag-nitudebeing69and49%,respectively,overNPKandINMtreated
plots(Fig.3).Thegardenpeaequivalentpodyieldofthesystemwas
positivelyrelated(R2=0.934)toSOCcontent(Fig.4).TheCO
2
emis-sionreductionunderFYM20plotswasupto9.5and7.6Mgha−1
comparedtoNPKandINMplots,respectively,throughgaininSOC
stock.AgaintheCO2 equivalentannual emissionof GHGsfrom
productionof 20tFYMwas53and 24%less thanapplied
min-eralfertilizerandFYMunderrecommendedNPKandINMplots,
respectively(Table6).
Fig.2.Soilorganiccarbonsequestrationpotential(CSP)ofdifferentnutrient man-agementpracticesunderanirrigatedgardenpea–frenchbeancroppingsystemin theIndianHimalayas(seeSection2fortreatmentdetails).
3.6. CorrelationandPCAofpodyieldwithsoilproperty
Acorrelationmatrix(Table7)showedsignificantcorrelations
(P<0.05)betweenallthedifferentsoilparametersandpodyields
ofbothgardenpeaandfrenchbean,exceptsoilpH.Therewasvery
strongcorrelation(P<0.001)betweenSOCandCEC,SOCandBD,
PAWCwithbacterial,actinomycetepopulation,dehydrogenaseand
Table6
Effectsoffertilizationonselectedsoilchemicalpropertiesandcarbonequivalentemissionfromirrigatedgardenpea–frenchbeancroppingsystemaftersixyears.
Treatmentsa pH SOCb
concentration (gkg−1)
SOC amount/stock (Mgha−1)
CO2emission
reductionthroughSOC stock(Mgha−1)
CO2equivalentemissionfrom
productionofnutrient (kgha−1yr-1)
SoilCEC (cmolkg−1)
Control 6.11 9.54 20.2 – – 9.07
FYM5 6.65 11.88 24.4 15.5 56 11.36
FYM10 6.72 12.35 25.2 18.4 112 11.92
FYM15 6.78 12.59 25.5 19.5 168 12.30
FYM20 6.85 13.21 26.6 23.3 224 13.03
NPK 5.64 11.57 24.0 13.8 479 10.53
INM 6.30 12.08 24.5 15.7 295 11.80
SEM± 0.13 0.50 1.0 0.53
LSD(P=0.05) 0.39 1.53 3.1 1.63
aSeeSection2fortreatmentdetails.LSD=Leastsignificantdifference.SEM=Standarderrorofmean. b SOC=soilorganiccarbon.
acidphosphatase activity,frenchbeanpodyieldwithCEC,SOC
andBD,andIRwithfungal,actinomycetal,Trichodermalpopulation,
dehydrogenaseandacidphosphataseactivity.Therewerealsovery
strong(P<0.001)tostrong(P<0.01)relationshipsamongmicrobial
populationsandenzymatic activities.Themicrobial populations
andsoilenzymaticactivityweremorecorrelatedtoCEC(P<0.01)
thanorganiccarbon(P<0.05).Therewasalsoverystrongpositive
(P<0.001)correlationsbetweenIRandPAWCascontrarytogeneral
perception.SoilpHhadnocorrelation(P>0.05)toanyofthesoil
parametersandpodyieldofbothcrops,exceptTrichoderma
popu-lation.TheBD,soilcrackingvolumeandsurfacearea,temperature
athottestweekafternoonanddiurnaltemperaturedifferenceof
hottestweekwerenegativelycorrelatedwithotherparameters.
PCAisausefulstatisticaltechniquewhichhadfound
applica-tioninreductionoftheoriginalvariablesinasmallernumberof
underlyingvariables(principalcomponent)inordertorevealthe
interrelationshipsbetweenthedifferentvariablesandtofindthe
optimumnumberofextractedprincipalcomponents.Thedifferent
soilpropertiesandpodyieldofcropsweredepictedinFig.5.The
PCAcomprisingtwoprincipalcomponents(F1andF2)accounted
for93.1% and93.9% of variancefor gardenpeaand frenchbean
crops,respectively.
ThelongerthelineinPCA,thehigheristhevariance.The
vari-anceamongthevariablesinthebiplotwasalmostsimilarforboth
gardenpeaandfrenchbean(Fig.5).Thecosineoftheanglebetween
thelinesapproximatesthecorrelationbetweenthevariablesthey
represent.The closer theangle to90 or 270◦, thesmallerwas
thecorrelation.Anangleof0or180◦ reflectsa correlationof1
or−1,respectively(KohlerandLuniak,2005).ThebiplotinFig.5
showedastrongpositiverelationshipbetweenthepodyieldand
CEC,SOC,allmicrobialpopulationcount,bothenzymaticactivity,
IRandPAWCforbothvegetables.Thecutpointofaperpendicular
fromatreatmentpointtoavariablelineapproximatesthevalue
ofthatobservationonthevariablethatthelinerepresents.Ifthe
cutpointfallsontheorigin,thevalueoftheobservationis
approx-imatelytheaverageoftherespectivevariable.Cutpointsfaroff
inthedirectionofthevariablelineindicatehighvalues,whilecut
pointsfaroffonthevariableline,whichhasbeenextendedthrough
theorigin,representlowvalues(KohlerandLuniak,2005).
Super-impositionofnutrientmanagementpracticesandyieldalongwith
soilpropertiesshowedthatFYM20andFYM15showedhigher
corre-lationwiththeseparameters.Itwasconfirmedfromthecorrelation
inTable7andPCAinFig.5thatsoilCECfollowedbySOCwerevery
closelycorrelatedwithpodyieldofbothvegetables.Hence,SoilCEC
followedbySOCwerethemostimportantyieldcontributingsoil
properties.SoilpHwasleastimportantpropertyforcontributing
productivityandinfluencingothersoilproperty.
ThePCAofnutrientmanagementpracticescomprisingtwo
prin-cipalcomponents(F152.3%;F240.8%forgardenpeaandF189.4%;
F24.5%forfrenchbean)accountedfor93.1and93.9%ofvariancefor
gardenpeaandfrenchbean,respectively.TheF1andF2hada
clus-terofnutrientmanagementpractices(FYM20,FYM15andINM)with
largepositiveloadingforthefirstcomponent.Thesecond
compo-nentalsopositiveforgardenpea,exceptslightnegativeforINM,
whilethesewereslightnegativefor frenchbeancrop.Nutrient
managementpracticesNPKandcontrolhadnegativeloadingfor
firstandsecondcomponentforbothcrops.Othernutrient
man-agementpracticesoccupiedpositionseitheronleftupperorright
uppersideofthebiplot.
Thepositionof17parametersinrelationtotheirinfluenceby
nutrientmanagementpracticesaccountedfor93.1and93.9%
vari-anceforgardenpeaandfrenchbean,respectively.Forgardenpea,
allparametersexceptBD,soilcrackingvolumeandsoilcracking
surfaceareaoccupiedpositionssolelyontherightupperpartof
D.
Correlationbetweenpodyieldofgardenpeaandfrenchbeanandsoilproperties.
aGPY FBY SOC CEC pH Bact Fungi Actino Tricho DHA AcP PAWC BD SCV SCSA IR CWM HWA HWD
GPY 1.000 0.951** 0.959** 0.664 0.833* 0.894** 0.602** 0.899** 0.895** 0.846* 0.907** −0.945** −0.852* −0.832* 0.872* 0.913**
aGPY=Gardenpeapoyield;FBY=Frenchbeanpodyield;SOC=Soilorganiccarboncontent;CEC=Soilcationexchangecapacity;Bact=Bacterialpopulationcount[colonyformingunit(CFU)g−1soil];Fungi=Fungalpopulation
count(CFUg−1soil);Actino=Actinomycetepopulationcount(CFUg−1soil);Tricho=Trichodermaspeciespopulationcount(CFUg−1soil);DHA=Dehydrogenaseactivity(gTPFg−1soil24h−1);AcP=Acidphosphataseactivity
(gPNPg−1soilh−1);PAWC=Plantavailablewatercapacity(%);SCV=Soilcrackvolume(cm3m−2);SCSA=Soilcracksurfacearea(cm2m−2);IR=Infiltrationrate(cmh−1);CWM=Morningtemperatureofthecoldestweekinthe
year(◦C);HWA=afternoontemperatureofthehottestweekintheyear(◦C);HWD=Diurnaltemperaturedifferenceofthehottestweekintheyear(◦C).
*p<0.05.
Variables (axes F1 and F2: 93.8
Fig.6.Groupingofnutrientmanagementpracticesbasedonprincipalcomponentscores(seeSection2fortreatmentdetails).
highestmeanvaluesofpositiveinfluencing soilparameters and
lowestmeanvaluesfornegativeinfluencingsoilparameters.The
nextbestclusterwasII,whichretainedFYM5andFYM10nutrient
managementpractices,followedbyclusterIII(controlandNPK).
Thegroupingpatternofnutrientmanagementpracticesobserved
inclusterasderivedfromFIandF2ofcropproductivityandsoil
properties.
SOCandCECinfluencedsignificantlytothecropproductivity
(Table7,Figs.4and5).Thiswasfurtherillustratedwhenalinear
and quadratic increase in yield oftotal systemwithincreasing
ratewasobservedwithSOCandCEC,respectively(Fig.4).Close
dependence of system yield with SOC (R2=0.9686) and CEC
(R2=0.9636) indicated that gardenpea–french beansystemwas
highlyresponsivetoSOCandCEC.ThehighervalueofSYIwith
FYM20alsosuggeststhatproductivityofgardenpea–frenchbean
cropping system can not only be improved but also sustained
inthelong-runwithFYM.SOCwasfoundtobeoneofthemost
importantparameterinfluencingothersoilpropertiesasevident
fromFigs.5–9andTable7.Itisclearlyindicatedfromthe
regres-sion analysis of soil CEC, dehydrogenase activity, BD, cracking
volumeandmorningsoiltemperatureofcoldestweekwithSOC
(Figs.7–9).NearperfectlinearrelationshipofCECandBDwithSOC
showedthatdifferencesintheseparameterswereassociatedwith
differencesinSOC.Themoderationofsoiltemperaturethrough
nutrientmanagementduringcoldestandhottestweekcompared
toun-amendedcontrolplotswaspositivelyandlinearlycorrelated
withgardenpeaand frenchbeancrop, respectively.(R2=0.8339
and0.9075).TheplotsunderFYM20moderatedthesoil
temper-atureupto1.50,0.60and0.47◦Cduringmorningofcoldestweek
oftheyear2007–2008,whilethemoderationwasupto5.00,2.93
and0.73◦Cduringafternoonofthehottestweekoftheyear2008
comparedtoun-amendedcontrol,NPKandINMplots,respectively.
4. Discussion
Interestingly,thehighestproductivitywasnotachievedwith
mineral fertilization (NPK) and the yields were significantly
improvedwithINMandhigherlevelsofFYM.Evidently,the
rec-ommendedNPKwasinadequateorimbalancedinthelong-run,as
itlackedotheressentialnutrientsincludingmicronutrientswhich
mighthavebeenavailablefromFYM.Theresultshowedthat
max-imumyieldofcropcouldbeobtainedwhenhigherlevelofFYM
wasincorporated,indicatingthatpotentialproductivitywasnot
Table9
Meanvalueofcropproductivityandsoilpropertiesofthreeclustersofnutrientmanagementpractices.
Cropproductivity/soilproperty Clusters
I II III
Gardenpeapodyield(tha−1) 8.36 6.82 4.69
Frenchbeanpodyield(tha−1) 12.75 10.06 6.63
Soilorganiccarbon(gkg−1) 1.26 1.21 1.06
SoilCECa(cmolkg−1) 18.61 11.64 9.90
SoilpH 6.65 6.69 5.88
Bacteriapopulationcount(×107CFUg–1soil) 3.07 1.82 1.39
Fungipopulationcount(×105CFUg−1soil) 4.40 2.68 1.12
Actinomycetepopulationcount(×104CFUg−1soil) 20.6 13.0 9.1
Trichodermapopulationcount(×103CFUg−1soil) 4.17 2.34 1.19
Dehydrogenaseactivity(gTPFg−1soil24h−1) 136 90 73
Acidphiosphataseactivity(gPNPg−1soilh−1) 1335 1090 1012
PAWC(%) 14.41 10.96 9.73
SoilBD(Mgm−3) 1.35 1.37 1.40
Soilcrackingvolume(cm3m−2) 174 196 363
SCSA(Soilcrackingsurfaceareacm2m−2) 1735 1905 3672
Infiltrationrate(cmh−1) 0.90 0.75 0.65
Coldestweekmorningtemperature(◦C) 12.2 11.7 11.5
Hottestweekafternoontemperature(◦C) 24.5 26.8 28.0
Hottestweekdiurnaltemperaturedifference(◦C) 0.91 3.05 3.95
D.Mahantaetal./ScientiaHorticulturae164(2013)414–427 423
Fig.7.Responseofsoilorganiccarbon(SOC)tosoilcationexchangecapacityanddehydrogenaseactivity(SOC,soilcationexchangecapacityandsoildehydrogenaseactivity valuesofdifferenttreatmentsweretakenforthisresponsecalculation).
Fig.8.Responseofsoilorganiccarbon(SOC)tosoilbulkdensityandcrackingvolume(SOC,bulkdensityandsoilcrackingvolumevaluesofdifferenttreatmentsweretaken forthisresponsecalculation).
possiblewithapplicationofmineralfertilizersalone(Sharmaand
Behera,2009).Useoforganicmanureensuredprolonged
availabil-ityofnutrientsevenbeyondthegrowthperiodandtherebyshowed
itsresidualeffectonthenextcropintherotation.Itseemslikely
thattherewasacontinuousandregulatedsupplyofnutrientsin
theFYMamendedplotsduetotheslowreleaseactioncompared
withtherapidsolubilityofmineralfertilizers(Beheraetal.,2007).
Itisoftenassumedthatahighlevelofsynchronybetween
nutri-entreleasefromFYMandcropnutrientuptakemighthavetaken
place,becausethesameenvironmentalfactorsregulatethe
pro-cessesofdecompositionaswellasnetprimaryproductivityand
nutrientdemand(CrewsandPeoples,2005).Inadditiontomajor
andmicro-nutrientsupply,organicmanuringalsoprovidesother
beneficialeffectstocropplantslikereleaseofvariousgrowth
pro-motingsubstances(SharmaandBehera,2009).Again,increased
acidphosphatase activitycouldberesponsiblefor hydrolysisof
organicallyboundphosphateintofreeions,whichweretakenup
byplants.TarafdarandJungk(1987)reportedthatplantscanutilize
organicPfractionsfromthesoilbymeansofphosphataseactivity
enrichedinthesoil-rootinterface.Reddyetal.(1987)reportedthat
duetothereactionsofphosphatase,H2PO4−wasmadeavailable
toplants fromorganicsubstancesinsoils.Highersoilmicrobial
anddehydrogenaseactivityalsofavoredforsignificantlymorepod
yieldinplotsunderFYM20thanNPKandINMingardenpea–french
beansystem.Moreover,FYM20 providedbettersoilquality (soil
physico-bio-chemicalproperties)asrecordedinthisexperiment
(Tables 4–6), whichultimately reflectedhigherpodyieldofthe
gardenpea–frenchbeansysteminplotsunderFYM20thanNPKand
INM.Gardenpeaprovidedthehighestpodyieldwithapplication
of15tFYMha-1,butfrenchbeanachievedthehighest
productiv-itywithFYM20tha−1.ItmightbeduetohighNrequirementfor
frenchbeanthangardenpea,asfrenchbeanisalowN2fixingcrop
(Yadav,2010).TheavailableNcontentmighthavebeenhigherdue
tomoreadditionofNinFYM20thanFYM15treatedplots,which
mighthavereducedtheperformanceofgardenpeainFYM20with
comparisontolaterplots.
Application of FYM has several indirect long-term benefits
(improvementinnutrient-useefficiency,providingfavorablesoil
health with better soil physical, chemical and biological
envi-ronment), which also accounted for greater adoption ensuring
sustainableproductivity(SharmaandBehera,2009)underFYM20
plots withcomparisonto NPKand INMtreated plots. The
pro-ductivityofcropswasshowntobestabilizedorimprovedwith
gradualbuild-upofbettersoilquality(Tables4–6)following
appli-cation of higher level (FYM20) of organic manures than plots
under NPK and INM. However, the addition of leaf litter and
root biomass of crops might have increased with higher level
of FYM, which might have also helped in sustaining the
sys-temproductivity (Beheraet al., 2007)under FYM20 plots than
NPK and INM. Application of FYM enhances sustainability of
cropping system was also further supported by Nayak et al.
(2012).
Continuousapplication of organicamendmentsfor six years
decreasedtheBDofsoilsignificantlyandsimilarresultshavebeen
corroboratedbyMosavietal.(2012)andGeetal.(2013).
Applica-tionofFYMmighthaveimpactedsoilaggregationwithmoreroot
biomass,therebyreducingsoilBD(Bhattacharyyaetal.,2010).The
increaseinorganicmatter(carbon)(Table6)contentresultedin
greatertotalporosityandbettersoilstructure,whichcontributed
inloweringsoilBD(Herenciaetal.,2011;Celiketal.,2010).SoilBD
decreasedwithFYMapplicationduetohigherSOC(Table6)that
resultedinbettersoilaerationandimprovementofsoilstructural
properties(Kunduetal.,2007).ThereductionofBDinFYM20had
improvedtheporosityandthatmighthavehelpedsoilaggregation
andwaterholdingcapacityofsoilwithcomparisontoNPKandINM
plots.AnincreaseofSOCcontentanddecreaseinsoilBDinthesoil
underFYM20plotsmighthavecausedanincreaseinPAWC.Geetal.
(2013)havealsorecentlyreportedthesimilarresults.
LowSCVwithFYM20applicationmaybeattributedtogreater
soilwater contents thanNPK and INM plots (Table 4)and the
dataweresupportedby thepreviousresearch(Bandyopadhyay
etal.,2003).TheeffectofFYMapplicationoncrackvolumemaybe
attributedtoagreaterrootbiomassthantheplotsunderNPKand
INMtreatments.ThehighernumbersofrootsproducedduetoFYM
applicationmighthavereducedtheshrinkageprocessbyanchoring
thesoilmass.ApplicationofFYMreducedSCSAbyreducingcrack
width(Bandyopadhyayetal.,2003).
Theabilityofasoiltotransmitwaterdependsonthe
arrange-mentofthesoilparticlesandstability oftheaggregates.Higher
IRwith FYM20 couldbe attributed tohigher SOC content. The
applicationofFYMovertheyearsnotonlyincreasedtotal
poros-ity, as evident from reduced soil BD (Table 4), but also might
haveimprovedporesizedistribution,continuityandstabilityof
pores(Bhattacharyyaetal.,2006).FYMoftenmodifiessoil
struc-tureandimprovessoilaggregationandinfiltrationcharacteristics
(Bhattacharyyaetal.,2010).Inaddition,highersteady-stateIRmay
bethedirectresultofacceleratedwaterflowthrough
macropo-resandbio-channels(Bhattacharyyaetal.,2010).Applicationof
organicmanuretosoilgreatlyincreasedwaterinfiltration(Essien,
2011)andwasdirectlyrelatedtothequantityoforganicmaterial
applied(ParkerandJenny,1945).
Continuousapplicationoforganicamendments(FYM20tha−1)
forsixyearsimprovedtheSOCandPAWCsignificantlycompared
toplotsunderNPKandINMtreatmentsandsimilarresultshave
beenreportedbyGeetal.(2013).Again,theplantgrowthmight
havealsoimprovedasindicatedfrompodyieldunderFYM20plots,
which enhanced moisture retention capacity of soil by cooling
effecttothe soilthrough higher shadowand canopy coverage.
Due to high SOC, PAWC, moisture holding capacity and
cool-ingeffect,thesoilmoisturestatuswasimprovedandmoderated
thesoil temperature better in FYM20 plots than NPK and INM
plots.Hence, thesoiltemperature increasedduringmorning of
coldestweekanddecreasedduringafternoonofcoldestandhottest
weekand morningofhottestweek.Themoderationofextreme
soil temperature through high SOC,moisture holding capacity,
shadingandcanopyeffectwashighestunderFYM20plots,which
finallypositivelyreflectedinthepodyieldofbothgardenpeaand
frenchbean compared to NPK and INMtreated plots (Fig.10).
ItclearlyindicatedthatapplicationofFYMcouldbemore
adap-tivetoclimatechange (evenin theIndian Himalayas)for both
crops.
ThehighestmicrobialpopulationunderFYM20treatedplotswas
duetothepresenceofeasilywatersolubleC(Maliketal.,2013)
andNinFYM,whichactsasasourceofenergyforsoilorganisms,
whereastheeasilysolubleCcomponentwasmissinginmineral
fer-tilizer(Beheraetal.,2007)and,hence,themicrobialpopulationwas
lessintheplotsunderNPK.Theseareintheagreementwithresults
obtainedbyBonillaetal.(2012),Leeetal.(2004)andZhangetal.
(2012).AdditionofFYMprovidedtheeasilysolubleCandincreased
themicrobialpopulationinsurfacelayer(0–15cm)ofsoilinthe
plotsunderINM.Trichodermaspecies arecosmopolitanfungiin
soilsdecayingorganicsubstances.Theypossessdiversemetabolic
activityandareaggressiveinnature.Thesecharacteristicsmake
them significant decomposersand necrotrophicto other fungi,
whichhelp inplaying keyrolesin suppressingsoil-borneplant
diseasesandpromotingplantgrowth.TheserenderTrichoderma
as a beneficial ecosystem of soil (Doiand Ranamukhaarachchi,
2009).
Soildehydrogenaseactivityisagoodindicatorofoverall
micro-bial activity in soil and it can serve as a good indicator of
soilcondition(DoiandRanamukhaarachchi,2009).Theenzymes
assayedinthisstudywerechosenbecausetheyplaycentralrolesin
mediatingbiochemicaltransformationsinvolvingorganicresidue
decompositionandC,NandPcyclinginsoils.Itisbelievedthat
mostsoilenzymesoriginatefromsoilfungi,bacteriaandplantroots
(Tarafdaretal.,1988).Thevariableeffectoforganicamendment
applicationonexo-cellularenzyme activitywasdueto
interac-tion ofseveral factors.Firstly, organicamendment applications
increasedorganicmattercontentandmicrobialbiomass.Therefore,
thesoilhasthebetterpotentialforgreaterenzymeproduction.This
mayexplainthesignificantlyhigherdehydrogenaseandacid
phos-phataseactivitiesinplotsunderFYM20thanNPKandINM.These
areintheagreementwithresultsobtainedbyLiuetal.(2013).
Sec-ondly,soilpHcangreatlyinfluencetherateofenzymecatalyzed
reactions,asachangeinH+ionconcentrationinfluencesenzymes,
substrates,andcofactorsbyalteringtheirionizationandsolubility
(Tabatabai,1994).Underacidsoilconditions(i.e.pH5.64inNPK
plots),largeincreaseinconcentrations ofaluminium(Al3+)and
manganese(Mn2+)cationsinsoilsolutionoccur(Rowell,1988),and
highconcentrationsoftheseionscouldhaveinfluencedenzyme
functionadversely(Dick, 1997)inplotsunderNPK. ThesoilpH
of6.85(almostneutral)inplotsunderFYM20mighthavefavored
dehydrogenaseandacidphosphataseactivitiescomparedtoNPK
and INMplots.Thirdly, beingthesubstrate for microbial
activ-ity,soilorganicmatterplaysanimportantroleinprotectingsoil
enzymes,whichbecomeimmobilizedinathree-dimensional
net-workofclayandhumuscomplexes(Tabatabai,1994).Soilsunder
FYM20recorded14.1and9.3%higherSOCthanNPKandINMtreated
plots,respectively.ThelinearrelationshipbetweenSOCandsoil
organicmatter(SOM)providedhigherSOMinFYM20treatedplots
thanNPK and INMand,hence, moreenzymatic activity.It was
alsoreportedthatdehydrogenaseandacidphosphataseactivities
weremuchhigher insoilsunderFYMthaninmineral
fertiliza-tionandINMtreatedplots.AdditionofFYMtomineralfertilization
improvedbothenzymaticactivitiesinINMtreatedplotsthanNPK
(Giusquianietal.,1994).
Thesoilreactionwasmoreacidicwithapplicationofmineral
D.Mahantaetal./ScientiaHorticulturae164(2013)414–427 425
Fig.10. Responseofmorningsoiltemperatureofthecoldestweekandafternoonsoiltemperatureofhottestweekonproductivityofrespectivecrops.
ofsuccessiverateofFYM.Theapproachtoneutralsoilreaction
withapplicationoforganicmanurehasalsobeenreportedbyGe
etal.(2013).ApplicationofFYMtosoilresultedinincreasedsoil
pHby improvingsoil bufferingcapacity compared tothe plots
undermineralfertilization(Gopinathetal.,2009).Theacidification
withapplicationofmineralfertilizerisattributabletonitrification
ofappliedfertilizerNandsubsequentleachingofnitrate(NO3–)
formedduringmineralizationofmineralfertilizers(Grahametal.,
2002).
SOCistheoverallindicatorofsoilquality(Lopezetal.,2012).SOC
isattributabletohigheryieldsunderFYM20plots,whichmighthave
resultedinhigherinputsoforganicmattertothesoilintheform
ofFYM,rootturnoverandcropresidues(Braretal.,2013;Ghosh
etal.,2012)andfinallyincreaseinSOC(Maltasetal.,2013).The
enhancementoforganicCinFYM-treatedplotsisobviousbecause
theadditionofFYMitselfincreasestheCcontentinsoilascompared
tonoexternalCadditionthroughmineralfertilizers(Bhattacharyya
etal.,2009).
The concentration and amount of SOC under FYM20 plots
(Table6)providedhigherstoragepotentialoforganiccarbon,
car-bonsequestrationpotentialandSOCbuild-upratethanNPKand
INMtreatedplots.Fronningetal.(2008)alsoobservedthattotal
SOC in the 0−0.25m profile increased by 41 and 25% for the
compostandmanuretreatments,respectively,atMichigan,USA.
Manureisalreadypartlydecomposedandcontainsalarger
pro-portionofchemicallyrecalcitrantorganiccompounds,whichmight
haveenhanced C retention inmanureamended plots (Paustian
etal.,1992).ThehighestCO2emissionreductionthroughSOCstock
underFYM20plotswasobvious,asitwasdirectlyproportionalto
SOCamountinsoil.TheperunitCO2equivalentemissionofGHGs
forproductionofmanureislessthanmanufactureofmineral
fertil-izerofN,PandKtogether(Lal,2004)andhencethelowemissionfor
20tFYMha−1withcomparisontoNPKandINM.Itisclearlyproved
fromtheaboveemissionfactorthatapplicationof20tFYMha−1is
highlyclimateresilientandsustainablethanmineralfertilization
andINM.
SeveralfactorsdeterminethesoilCEC.HighCECinFYM20plots
mightbeduetohigherSOCandpH(nearneutral)recordedinthese
plotsthanNPKplots.ThisisinagreementwithGoladiandAgbenin,
1997,whoobservedSOCandpHareamongmostimportantfactors
contributingCECofsoil.FYMalsocontributesnutrients(Ca2+,Mg2+)
tosoils,resultinginrelativelyhighCEC(Geetal.,2013).Thisis
furthersupportedbythestrongcorrelationbetweenCECandSOC
(R2=0.983***).
5. Conclusion
Theresultsobtainedonasix-yearcycleofgardenpea–french
bean cropping system provide us withmajor findings on
sus-tainability and climate resilience of the system in the Indian
Himalayas.Through thePCAanalysis,soilCECwasfoundtobe
themost importantsoil propertyfor enhancingproductivityof
gardenpea–frenchbeancroppingsystem.Fromtheregression
anal-ysisand correlation,itwasfoundthatSOCmarkedlyinfluenced
othersoilparameters.Additionof20tFYMha−1(FYM
20)increased
soilorganicC(SOC)byabout14and9%,respectively,over
mineral-fertilized(NPK)andINMtreatedplots.IncreasedSOCmighthave
beenthecauseofbettersoilphysicalconditions,throughimproved
PAWCandIRandreducedsoilBDandsoilcrackingparametersin
FYM20treatedplotscomparedtoNPKandINMplots.Application
ofFYM20showedsignificantlyhighersoilCEC,microbial
popula-tion,dehydrogenaseandacidphosphataseactivitiesoverNPKand
INMplotsinthe0–15cmsoillayer.TheSYIincreasedwith
suc-cessiverateofFYMapplicationandFYM20treatedplotsprovided
higher sustainabilityindex thanNPK and INM.Thiswould also
providemorecarbonstoragepotentialtomaintainenvironment
friendlysituationthanNPKandINMtreatedplots.SoilC
seques-tration alsobenefitstheclimate, which is threatenedby global
increaseinatmospheric CO2.Fromthetemperaturemoderation
andCemissionreduction,itwasfoundthatapplicationofFYM20is
moreclimateresilientthanNPKandINMplots.ThePCAputFYM20,
FYM15andINMamongtreatmentsina singleclusterfor
differ-entsoilpropertiesandpodyieldofbothvegetables.UseofFYM
isabetteralternativetoachievesustainability.Theresultsofthis
studyindicatethat20tFYMha−1toeachcropcanbeusedfor
sus-tainableyield,climateresilientcropproductionandsoilqualityof
gardenpea–frenchbeancroppingsystem.
Acknowledgments
Theauthors aregratefultoMr.LaxmiDattMalkani and Mr.
Sanjayformaintainingthefield experiment overtheyears and
