ICAR-Indian Institute of Rice Research (ICAR-IIRR), Rajendranagar, Hyderabad, IndiaIndia
ADASCA, B-205-206, Dhanashree Heights, Veera Desai Road, Andheri (West), Mumbai – 400053, India Corresponding Author: Brajendra
Also available as PDF (figures and tables appear in the PDF).
Soil-based biostimulants are increasingly being evaluated as sustainable inputs for improving soil health, nutrient-use efficiency, and crop productivity. The present study was conducted to evaluate the effectiveness of N-Carb, an organic carbon- and nitrogen-based product, in improving growth, yield, nutrient uptake, and selected physiological indicators of rice. A field experiment was conducted during the kharif season of 2022 at the ICAR-Indian Institute of Rice Research farm, Hyderabad, using rice variety DRR Dhan 48. The experiment was laid out in a randomized block design with three replications and four treatments consisting of recommended dose of fertilizers (RDF) alone and RDF combined with N-Carb applied at different crop growth stages. N-Carb was applied at a concentration of 6.5 mL L−1 according to the respective treatment schedules. The initial soil was a slightly alkaline deep black clayey Vertisol with low available nitrogen, medium available phosphorus, and high available potassium. Application of N-Carb along with RDF generally improved plant growth, effective tillering, grain yield, and nutrient uptake compared with RDF alone. The highest grain yield (6.28 t ha−1 ) was recorded with three applications of N-Carb at basal, active tillering, and panicle initiation stages, followed closely by application at basal and active tillering stages (6.26 t ha−1 ). N-Carb application also increased SPAD meter readings and NDVI values and improved post-harvest soil nitrogen status. The results indicate that N-Carb has potential as a supplementary input for improving rice growth and productivity when integrated with recommended fertilizer practices.
Keywords: N-Carb; rice; biostimulant; nutrient uptake; grain yield; soil health; nutrientuptake; grainyield; soilhealth tainedlowavailablenitrogen(270kgha ); medium
Soilhealthisacriticalcomponentofsustainableagriculturalproductionbecauseitinfluencesnutrientavailability,waterretention,rootdevelopment,microbial activity,andcropproductivity.Continuousandintensivecultivation,togetherwithimbalancedfertilizeruse, canadverselyaffectsoilfertilityandnutrient-useefficiency. Therefore,theuseofsupplementarysoilinputsthatimprovenutrientavailabilityandplantnutrientuptakehasgainedincreasingattention.Soil-based biostimulantsarenaturalorbiologicalproductsthat stimulateplantgrowth,nutrient-useefficiency,microbialactivity,andtolerancetoenvironmentalstresses. Unlikeconventionalfertilizers,theirprimaryfunction isnotnecessarilytosupplynutrientsdirectlybutto
enhancenutrientavailability,uptake,andutilization bycrops.
N-Carbisanorganiccarbon-andnitrogen-basedproductdevelopedbyADASCAIndiaforagriculturalapplication.Itisintendedforbasalandsubsequentapplicationstoimprovenutrientabsorptionandbioavailabilityincrops.Theproductisalsoreportedtosupportsoil microbialactivityandimprovesoilphysicalandbiologicalproperties.Theadditionoforganiccarbonmay provideafavourableenvironmentforsoilmicroorganismsinvolvedinnutrientcyclinganddecomposition. Theeffectivenessofsuchproductsmayvarywithcrop, soiltype,applicationrate,andtimingofapplication. Therefore,systematicfieldevaluationisnecessaryto determinetheirsuitabilityunderdifferentcropproductionenvironments. Riceisanimportantcerealcrop withhighnutrientrequirements,andefficientnutrient managementisessentialformaintainingproductivity andsoilfertility.Hence,thepresentstudywasundertakentoevaluatetheeffectofN-Carbapplicationat differentcropgrowthstagesongrowth,yield,nutrient uptake,physiologicalindicators,andpost-harvestsoil nutrientstatusofrice.
Afieldexperimentwasconductedduringthekharifseasonof2022attheICAR-IndianInstituteofRiceResearch (ICAR-IIRR)farm,Hyderabad,India.Theexperimental fieldwaslocatedatapproximately17°19′ Nlatitude, 78°23′ Elongitude,and542mabovemeansealevel,
withameanannualrainfallofabout750mm.
Theexperimentwasconductedonadeepblackclayey VertisolclassifiedasTypicPellustert.Theselectedexperimentalplot(A-3)hadasoilpHof8.13andsoilorganicmattercontentof1.25%,correspondingtoapproximately0.71%soilorganiccarbon. Thesoilconavailablephosphorus(10.7kgha−1),andhighavailablepotassium(332kgha−1).Availablecalciumand
magnesiumwerehigh,whereasavailablesulphurwas low(8kgha−1). Thesoilalsohadhighavailablezinc
andcopperandlowavailableironandmanganese.
Theexperimentwasconductedinarandomizedblock designwiththreereplications.RicevarietyDRRDhan 48wasusedasthetestvariety.Theplotsizewas23.8 m2 (3.5m 6.8m). Fourtreatmentswereevaluated × todeterminetheeffectofdifferentN-Carbapplication schedulesincombinationwiththerecommendeddose offertilizers(RDF):
• T :Control(RDFalone) • T :RDF+N-Carbatbasalapplication@6.5mL L−1
• T :RDF+N-Carbatbasalapplication@6.5mL L−1 +activetilleringstage@6.5mLL−1
• T :RDF+N-Carbatbasalapplication@6.5mL L−1 +activetilleringstage@6.5mLL−1 +panicle initiationstage@6.5mLL−1
Therecommendeddoseoffertilizerwas120:80:60kg −1 N O Oha .Nitrogenwasappliedinsplitdoses,with 2 52 two-thirdsappliedinitiallyandtheremainingone-third duringthesubsequentcropstage.N-Carbwasapplied accordingtotherespectivetreatmentschedules.
Ricewassownon9July2022andtransplantedon10 August2022.UreaandN-Carbwereappliedaccording totheexperimentalschedule.Weedmanagementwas carriedoutaspertherecommendedpractice,andthe cropwasharvestedon28November2022.
Observations were recorded for plant growth, tiller production,drymatteraccumulation,yieldattributes, grainyield,strawyield,andnutrientuptake. Growth observationswererecordedatdifferentcropgrowth stages,includingactivetillering,panicleinitiation,and physiologicalmaturity.Yieldattributesincludedpaniclenumber,grainsperpanicle,andgrainweight.SPAD meterreadingsandnormalizeddifferencevegetation index(NDVI)valueswerealsorecorded.Post-harvest soilsampleswereanalysedforavailableN,P,andKusingtheIIRRsoiltestingkitandKrishiRASTAAmachine.
Theexperimentaldatawerestatisticallyanalysedusing AGRESstatisticalsoftware.Theresultsarepresented inTables1–4.
CD0.05 NS CV(%) 5.08
Table 2. EffectofN-CarbapplicationongrainandstrawyieldofricevarietyDRRDhan48
T –RDFalone(Control) T –RDF+N-Carbatbasal T –RDF+N-Carbatbasal+activetillering T –RDF+N-Carbatbasal+activetillering+panicleinitiation 6.28 6.75 CD 0.05 CV(%)
TheapplicationofN-CarbincombinationwithRDFgenerallyimprovedthegrowthandtilleringcharacteristicsofDRRDhan48comparedwithRDFalone(Table 2).Plantheightincreasedfrom83cmundertheRDF control(T )to86,87,and88cmunderT ,T ,andT , 1 2 3 4 respectively.Drymatteraccumulationwasalsohigher withN-Carbapplication.Thehighestdrymatteraccumulation(887gm−2)wasrecordedwithbasalapplicationofN-Carb(T ),comparedwith832gm−2 under RDFalone.Thenumberoftillersm−2 increasedfrom 304inT to357inT ,325inT ,and352inT .Similarly, 1 2 3 4 thenumberofpaniclesm−2 increasedfrom272inT to325,297,and313inT ,T ,andT ,respectively.The 2 3 4 percentageofeffectivetillerswas89%inthecontrol andincreasedto91%withT andT .TheseobservationsindicatethatN-Carbapplicationincombination withRDFfavourablyinfluencedvegetativegrowthand tillerdevelopment.Theimprovementmaybeassociatedwithenhancednutrientavailabilityanduptake underN-Carbapplication.Theseresultsarereported byBharamappanavaraetal. (2020),Brajendra,etal. (2020),Caon,andVargas,(2017).
GrainyieldofDRRDhan48waspositivelyinfluenced byN-Carbapplication(Table3).Thecontroltreatment (T )producedagrainyieldof5.78tha−1.Application
ofN-Carbatthebasalstage(T )increasedgrainyieldto 5.88tha−1,whileapplicationatbasal+activetillering stages(T )resultedin6.26tha−1. Thehighestgrain yield of 6.28 t ha−1 was recorded in T , in which N-
Carbwasappliedatbasal,activetillering,andpanicle − − − 832 304 272 89 887 357 325 91
87 854 325 297 91
852 352 313 89
33.98 NS NS 4.27 2.20 7.41 8.49 2.63 849 329 293 89
−1 −1
5.78 6.32 5.88 6.22 6.26 6.85
0.38 0.50 3.55 4.26 6.00 6.51
initiationstages.Thus,grainyieldincreasedbyapproximately8.7%underT comparedwiththeRDFcontrol. StrawyieldwasalsoimprovedwithmultipleN-Carb applications.Thehigheststrawyield(6.85tha−1)was recordedunderT ,followedbyT (6.75tha−1),com- 3 4 paredwith6.32tha−1 inthecontrol.Thehighergrain
yieldunderN-Carbtreatmentswasmainlyassociated withimprovedeffectivetilleringandpanicleproduction.Theresultssuggestthatrepeatedapplicationof N-Carbduringimportantcropgrowthstagesmaysupportcropgrowthandyieldformation.However,thedifferencesamongN-Carbapplicationschedulesshould beinterpretedbasedonthestatisticalsignificanceindicatedbytheanalysis.Theseresultsarereportedby Gopaletal.(2014),Gorlapallietal.(2022)andKaleet al.(2021).
2 3
SPADmeterreadingsandNDVIvalueswerehigherin N-Carb-treatedplotsthanintheRDFcontrol(Table4). TheSPADvalueincreasedfrom36.5inT to39.8,40.1, and43.0inT ,T ,andT ,respectively. Thehighest 2 3 4 SPADreadingwasthereforerecordedwiththreeapplicationsofN-Carb. NDVIvaluesfollowedasimilar trend, increasing from 0.72 in the control to 0.73 in T andT and0.74inT . ThehigherSPADandNDVI 2 3 4 readingssuggestimprovedcropcanopydevelopment andleafgreennessunderN-Carbapplication. These
physiologicalindicatorsmayreflectimprovedcropnutritionalstatus,particularlynitrogenstatus,although directrelationshipsshouldbeconfirmedthroughdetailednutrientanalysis.Theseresultsarereportedby
Kaleetal.(2020),Parmaretal.(2022)andRathodetal.
T –RDFalone(Control) T –RDF+N-Carbatbasal T –RDF+N-Carbatbasal+activetillering T –RDF+N-Carbatbasal+activetillering+panicleinitiation 43.0 0.74
Table 4. EffectofN-Carbapplicationonpost-harvestavailablenutrientstatusofsoil
T1 –RDFalone(Control) Low Medium High 302 16.5 345 T2 –RDF+N-Carbatbasal Medium Medium High 335 17.8 333
activetillering+ Medium Medium High 375 18.1 312
(2021).
Post-harvestsoilanalysisindicateddifferencesinavailablenutrientstatusamongthetreatments(Table5). AccordingtotheIIRRsoiltestingkit, availablenitrogenwasclassifiedaslowundertheRDFcontroland mediumunderallN-Carbtreatments.Availablephosphorusremainedinthemediumcategoryandavailable potassiumremainedhighacrossthetreatments.MeasurementsobtainedusingtheKrishiRASTAAmachine showedavailablenitrogenvaluesof302,335,362,and 375kgha−1 inT ,T ,T ,andT ,respectively.Available 1 2 3 4 phosphorusvaluesrangedfrom16.5to18.1kgha−1, whileavailablepotassiumrangedfrom312to345kg ha−1.Thehighestpost-harvestavailablenitrogenwas recordedunderT ,suggestingthatrepeatedN-Carbapplicationmayhavecontributedtomaintainingahigher soilnitrogenstatusaftercropharvest.However,longertermexperimentsarerequiredtoestablishtheeffects ofN-Carbonsoilfertilityandnutrientdynamics.These resultsarereportedbySahooetal.(2022),Srilathaet al.(2019)andTutietal.(2022).
ThefieldexperimentconductedwithricevarietyDRR Dhan48demonstratedthatN-Carbapplicationincombinationwiththerecommendeddoseoffertilizersimprovedseveralgrowthandyieldparameterscompared withRDFalone.ApplicationofN-Carbatbasal,active tillering,andpanicleinitiationstages(T )recordedthe highestgrainyieldof6.28tha−1,comparedwith5.78 tha−1 underRDFalone. N-Carbtreatmentsalsore-
sulted in higher tiller and panicle production, SPAD meterreadings,NDVIvalues,andpost-harvestavailablenitrogen.Overall,theresultsindicatethatN-Carb has potential as a supplementary input for improv-
36.5 0.72 39.8 0.73 40.1 0.73
N P K N(kgha−1) P(kgha−1) K(kgha−1)
Medium Medium High 362 17.6 323
ingricegrowth,nutrientavailability,andproductivity when used along with recommended fertilizer practices. Amongthetreatmentsevaluated, application at basal + active tillering + panicle initiation stages showedthemostconsistentoverallperformance.However,multi-seasonandmulti-locationstudiesarerequiredtoconfirmtheagronomicandsoil-healthbenefitsofN-Carbbeforemakingbroaderrecommendations.
TheauthorssincerelyacknowledgeM/sADASCAIndia, Nashik,Maharashtra,forprovidingfinancialsupport andtheN-Carbproductforevaluation. Theauthors aregratefultotheDirector,ICAR-IndianInstituteofRice Research,Hyderabad,forprovidingpermissionandfacilitiestoconductthefieldexperimentattheIIRRfarm. Theauthorsalsothankallcolleaguesandassociates whocontributedtothesuccessfulcompletionofthe study.