in the soil proﬁle The App a tool SOC to estimate plus and calculate organiccarbon Technology Journal of Applied Researchand

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Availableonlineatwww.sciencedirect.com

Journal of Applied Research and Technology

www.jart.ccadet.unam.mx JournalofAppliedResearchandTechnology14(2016)135–139

Original

The App SOC plus a tool to estimate and calculate organic carbon in the soil profile

Francisco Bautista

^a,b,∗

, Eduardo García

^c,1

, Ángeles Gallegos

^c,1

aCentrodeInvestigacionesenGeografíaAmbiental,UniversidadNacionalAutónomadeMéxico,AntiguacarreteraaPatzcuaroSN,Morelia,Michoacán,Mexico

bCentrodeBiologíayEdafologíaAplicadadelSegura,CSIC,Murcia,Spain

cSkiu,ScientiﬁcKnowledgeInUse,Mexico¹ Received14October2015;accepted17March2016

Availableonline11May2016

Abstract

Intheworld,researchersareworkingveryintensivelyinthedevelopmentofsoilorganiccarbon(SOC)inventories.Soilorganiccarbonisvery importantbecauseitconstitutesthelargestreservoirofcarboninterrestrialecosystems.Maintainingandincreasingsoilcarbonisanoptionto reducetheamountsofCO2intheatmosphere,andthereby,toreduceormitigateclimatechange.TheSOCisnowatopicofgreatinteresthenceit isrecommendedtoknowtheamountofSOCalongtheprofiletoselectandevaluatethoseareasthatshouldbepreserved.Theaimsofdeveloping AppSOCplusweretoeliminatethecalculateerrorsofSOCandtomakeatooltoestimateSOCinfield.Thecommonunitsofmeasurementof soilpropertieswereemployed:bulkdensityinmgmL⁻¹,horizonthicknessincentimetres,stoninessandorganiccarboninpercentage.TheApp SOCpluswasdevelopedintheAndroidplatform.AppSOCplusinvolvesathree-stepprocess:introductionofsoilproperties,calculationofSOC tohorizonandsoilprofile,andconversionofunitsusingtheinternationalandEnglishsystems.Asaresult,therewillnolongerbeconfusions withconversionunitsusingAppSOCplus;withAppSOCplusthesoilorganiccarboncannowbecalculatedor/andestimatedbecauseitprovides instructions(aids)toestimatethesoilpropertiesnecessarytocalculatetheSOCinthesoilprofile.YoucansavetimeinthecalculationofSOC.

AppSOCplusisatoolfordiagnosisinthefield.

Keywords:Carbonstock;Organicmatter;Androidapplication;Bulkdensity;Stoniness

1. Introduction

Intensiveworkisdevelopedataglobal,national andlocal leveltoelaboratethe inventoriesofsoilcarbonbecauseofits relationto the global climate change. Soil carbon is consid- eredthe largestcarbonreservoirof the terrestrialecosystems (Alvarez-Arteaga,Krasilnikov,&García-Calderón,2012.)Ata locallevel, areasofinterest forthe conservationmayappear, such as the natural protected areas, the national parks and thebiospherereserves. Theseareasare valuedbecause ofthe environmentalservicestheyoffertothesociety.Thepayment

∗Correspondingauthor.

E-mailaddress:[email protected](F.Bautista).

1 www.actswithscience.com.

PeerReviewundertheresponsibilityofUniversidadNacionalAutónomade México.

fortheseenvironmentalservices,amongwhichthefixationof organic carbonstands out,isplannedinsomeof theseplaces thesoilorganiccarboncalculation(Pérez,Ramírez,Bautista,&

Jaramillo,2013).

The studyof soilorganiccarbonisnow asubjectof great interest,whichiswhyitisrecommendabletoknowtheamount ofsoilorganiccarbonthroughoutthesoilprofiletoselectand valuetheareasthatmustbepreserved.

Normally,miscalculationsareshowninscientificmeetings because of the unfortunate selection of the properties of the soilthat isbeingmeasured, thewayof expressingthemwith inappropriateunitsandbecauseofmiscalculations.Besides,the numberofprofessionalswhoarenotedaphologistsinterestedin themeasurementofSOCgrowsdaybyday.

ThereasonstocreateAppSOCplusareasfollows:(a)normally,miscalculationsareshowninscientificmeetingsbecause oftheunfortunateselectionofthepropertiesofthesoilthatis

http://dx.doi.org/10.1016/j.jart.2016.03.002

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beingmeasured,thewayofexpressingthemwithinappropriate unitsandbecauseofmiscalculations;(b)thenumberofprofes- sionalswhoarenotedaphologistsinterestedinthemeasurement ofSOCgrowsdaybyday;(c)theneedtoperformrapidfield estimations.

The aims behindthe creationof App SOCplus are (a)to decreasethemiscalculationscausedbytheunfortunateselection ofthepropertiesofthesoil,theapplicationofthewrongequation andtheinappropriateunits,inwhichtheresultsareexpressed;

(b)tooffertheprofessionalswhoarenotedaphologistsatoolto measuretheSOC;(c)toperformrapidfieldestimations.

2. Materialsandmethods

2.1. Appdesignanddevelopmentplatform

AppSOCplusisanapplicationdesignedfortheestimation ofsoilorganiccarbonfromitsedaphicproperties.Thisappis compatiblewithallmobiledeviceswithanAndroidV4.0or thelatestoperatingsystem.InordertocreateAppSOCpluswe used:(a)SDK,thesoftwaredevelopertoolforAndroidand(b) IDEEclipse asan integrateddevelopmentenvironment. Both areopenaccesstools.Interfacesweredesignedtoallowcom- patibilitywithresolutioninsmartphonesandtabletsof7 and 10(Canós,Letelier,&Penadés,2003).

2.2. Soilorganiccarboncalculation

Inordertocalculatethesoilorganiccarbon(SOC)thefol- lowingformulaisapplied:

SOC=

i=1 i=n

BDi∗(THi∗0.01)∗

1−CRi

100

∗Ci

∗100

where SOC [Mgha⁻¹]: organic carbon full profile; n: total number of horizons full profile; BDi [gmL⁻¹]: bulk density of the horizoni; THi [cm]: thicknessof the horizoni incm;

CRi[vol.%]:volumeofcoarsefragmentsbyhorizoni;Ci[%]:

percentageoforganiccarbonhorizoni.

AppSOCplusincludesasimplifiedformula,inwhichthe soilpropertiesareshowninthecommonunitsinuse.

AppSOCplusmakesitpossibletocalculatetheorganiccar- bon inaneasyandrapidway.It isalsopossible tocarryout estimationsofthequantityoforganiccarbonbyusingthesoil profiledescriptiononthefield(itincludesoptionsfortheesti- mationofthebulkdensity,stoninessandorganiccarbononthe field).

2.3. Bulkdensityestimation

The bulk density is measured withacylinder of aknown volumewhichisinsertedineach horizon,thenit isdriedand weighedrightafter(Jahn,Blume,Asio,Spaargaren,&Schad, 2006;Siebe &Jahn, 1996).Whenthe horizonhasareduced thicknessoritistoocompacttoinsertthecylinderproperly,it ispossibletomeasurethesoildensitybymeansoftheaggre- gatedensitybyusingthe clodmethod(Gandoy,1992;NOM,

Fig.1.(a)Imagestoestimatestoninesspercentageinvolume.(b)Imagesto estimatepercentageinvolumestoniness.

2003.) Innon-aggregated soils,it isrecommendedtouse the coremethod(Gandoy,1992).

In stony soils,such as the ones onthe YucatanPeninsula, whichhavehighcarboncontentinfine earthbut,atthesame time,havescarcefineearth,itisnecessarytomeasurethebulk densitybydiggingaholeinthesoilandcollectingfineearth, thickfragments,andafterwards,measuringthevolumebylining aplasticandbyfillingitwithwater,orbyusingthecoremethod.

ThekeyfromTable1isusedinordertomakethebulkdensity estimationonthefield.

2.4. Horizonthicknessmeasurement

Ameasuringtapeisusedinordertoobtainahorizonthickness measurement. The difficulty inthe process appearswhen the boundarybetweenthehorizonsiswavy,irregularorbroken.In these cases, the averagedepth betweenthe horizons must be registered.

Thethicknessismeasuredincentimetres.

2.5. Stoninessorthickfragmentsvolume

The estimation of thestonefragmentsvolume, alsocalled stoniness,canbecarriedoutbycomparisontoFig.1(USDA, 2012).Theestimationofthisparameteriscarriedouthorizonby horizon.Itisrecommendedtoworkwithaknownsurface(e.g.

100cm²)usingacordthatwouldbeadaptabletothedifferent horizonthicknesses.

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Table1

Guidelinestoestimatebulkdensity(FAO,2006).

Observation Frequentpedshape Bulkdensity(gmL⁻¹)

Sandy,siltyandloamysoilswithlowclaycontent.

Manypores,moistmaterialsdropeasilyoutoftheauger;materialswith andicproperties.

Granular <0.9

Sampledisintegratesattheinstantofsampling,manyporesvisibleonthe pitwall.

Singlegrainorgranular 0.9–1.2

Sampledisintegratesintonumerousfragmentsafterapplicationofweak pressure.

Singlegrain,subangularorangularblocky 1.2–1.4

Knifecanbepushedintothemoistsoilwithweakpressure,sample disintegratesintofewfragments,whichmaybefurtherdivided.

Subangularandangularblocky,prismaticor platy

1.4–1.6

Knifepenetratesonly1–2cmintothemoistsoil,someeffortrequired, sampledisintegratesintofewfragments,whichcannotbesubdivided further.

Prismatic,platyorangularblocky 1.6–1.8

Verylargepressurenecessarytoforceknifeintothesoil,nofurther disintegrationofsample.

Prismatic >1.8

Loamysoilswithhighclaycontent,clayeysoils.

Whendropped,sampledisintegratesintonumerousfragments,further disintegrationofsubfragmentsafterapplicationofweakpressure.

Angularblocky 1.0–1.2

Whendropped,sampledisintegratesintofewfragments,further disintegrationofsubfragmentsafterapplicationofmildpressure.

Angularblocky,prismatic,platyorcolumnar 1.2–1.4

Sampleremainsmostlyintactwhendropped,furtherdisintegration possibleafterapplicationoflargepressure.

Coherent,prismatic,platy,columnar,angular blockyorwedge–shaped

1.4–1.6

Sampleremainsintactwhendropped,nofurtherdisintegrationafter applicationofverylargepressure.

Coherent,prismatic,columnarorwedge-shaped >1.6

Note:Iforganicmattercontentis>2%,bulkdensityhastobereducedby0.03kgdm⁻³foreach1%incrementinorganicmattercontent.

2.6. Soilorganiccarbon

In orderto measure the soil organic carbon in fine earth (sievedthrough a 2mm mesh)various methods are suitable.

Thecommon methodis the wetoxidationmethod inanacid potassiumdichromate solution;thereaction mixturetempera- turerisesand70%ofthesoilorganiccarbonisrecovered(Nelson

&Sommers,1982).

The method of wet oxidation with potassium dichromate maybemoreefficientifexternalheatisappliedtothereaction, since100%oforganiccarbonwilloxidize(Nelson&Sommers, 1982).

Themostrecommendedmethodistheuseofanauto-analysis equipmentfortotalorganiccarbon;withthisequipment,anoxi- dationbycombustionisperformed,thegasesfilterupandthe CO2ismeasured.100%ofthesoilorganiccarbonisrecovered withtheuseofthismethod.Thereareothermethodstoquantify thesoilorganiccarbonbymeansofUVandinfrared;neverthe- less,theyarenotfrequentlyused.Insoilswithinorganiccarbon, itseliminationmustbetakenintoaccount.Itwillbecarriedout withsomeacidthatwillnotinterferewiththeanalysismethod appliedlater.

Theorganicsoilcanbeestimatedonthefieldbyusing the guideinTable2.

Table2

Guidelinestoestimatesoilorganiccarbon(FAO,2006).

Colour Munsellvalue Moistsoil Drysoil

S LS,SL,L SiL,Si,SiCL,CL,SCL,SC,SiC,C S LS,SL,L SiL,Si,SiCL,CL,SCL,SC,SiC,C (%)

Lightgrey 7 <0.3 <0.5 <0.6

Lightgrey 6.5 0.3–0.6 0.5–0.8 0.6–1.2

Grey 6 0.6–1 0.8–1.2 1.2–2

Grey 5.5 <0.3 1–1.5 1.2–2 2–3

Grey 5 <0.3 <0.4 0.3–0.6 1.5–2 2–4 3–4

Darkgrey 4.5 0.3–0.6 0.4–0.6 0.6–0.9 2–3 4–6 4–6

Darkgrey 4 0.6–0.9 0.6–1 0.9–1.5 3–5 6–9 6–9

Blackgrey 3.5 0.9–1.5 1–2 1.5–3 5–8 9–15 9–15

Blackgrey 3 1.5–3 2–4 3–5 8–12 >15 >15

Black 2.5 3–6 >4 >5 >12

Black 2 >6

AdaptedfromSchlichting,BlumeandStahr(1995).

Note:Ifchromais3.5–6,add0.5tovalue;ifchromais>6,add1.0tovalue.S:sand;LS:loamysand;SL:sandyloam;L:loam;SiL:siltloam;Si:silt;SiCL:silt clayloam;CL:clayloam;SCL:sandyclayloam;SC:sandyclay;SiC:siltclay;C:clay.

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3. Resultsanddiscussion 3.1. Appfunctions

InAppSOCplus,clickfirsttheApplogo(newestimation) and insert the horizon key; subsequently, introduce the bulk densityingmL⁻¹,thehorizonthicknessincm,thestonevol- umeorthickfragmentsinpercentage(0–100),andfinally,the soilorganiccarboninfineearth(sievedthrougha2mmmesh) expressed in percentage (Table 3). Afterwards, click “calcu- latehorizon”whichwill becalculatedinSOCandexpressed inMgCha⁻¹.Later,introduce the horizondata(Fig.2).The totalorganiccarboninthesoilprofileappearsatthebottomof thescreen.OncethetotalSOCcalculationsarecompleted,itis possibletotransformtheunitsifnecessary(Fig.2).

Table3

FunctionsofthetwoversionsoftheAppSOC.

Characteristics SOCBETA SOC+

Simplifyingtheequationforcalculatingsoil organiccarbon

X X

Unitconversionusingtheinternationalsystem andtheEnglishsystem

X X

Aidforestimatingbulkdensity X

Aidforestimatingstoniness X

Aidforestimatingorganiccarbon X

Graphorganiccarboninthesoilprofile X

Graphorganiccarboninthesoilprofile comparedtoothersoilgroupsaccordingto theWRB

X

Fig.2.ExampleofuseofSOCApp.

50 40 30 20 10 0 Insertion time Calculation of organic carbon Conversion time

Minutes App SOC + Excel

Fig.3.CalculatetimeofsoilorganiccarbonusingtheAppSOCandexcel.

Itispossibletoestimatethecontentofthesoilorganiccarbon byusingthefunctionstoestimatethebulkdensityandorganic carbonwithtables.Besides,itispossibletoobtaingraphsfrom thecarboncontentthroughouttheprofileandcomparethemwith theorganiccarboncontentofsomesoilgroupsprovidedbythe WRB(Robert,2002).

ThereisnosimilartooltocomparetheefficiencyofAppSOC pluswith.

3.2. Quickcalculation

AppSOCplusperformsanaccuratecalculationandshowsa rapidperformanceofallitsfunctions.Bycomparison,anexpe- riencedtechnicianneeds70mintocalculateoneprofileoffive horizonswithExcel;however,withAppSOCplusthecalcula- tionsarequicklyfinishedinonly7min(Fig.3).Sinceworktime onthefieldisexpensive,thisdifferenceinminutesisveryvalu- able.Theappisdesignedtobehaveasafieldtool,withwhich calculationsandestimationscanbedonequicklyandreliably.

4. Conclusions

Wehavenow atoolwiththepossibility tobeused onthe fieldwhichallowsthefulfilmentofarapiddiagnosisofthecon- tentoforganiccarboninthesoilprofilewithcommonmeasure unitsappliedonthefield;iteliminatespossiblemistakeswhen calculatingorapplyingformulasandperformsrapidly.

Knowledgeofthecontentoforganiccarboninthesoilprofile isofprimaryimportancetolinkthesoilusagewithitsenviron- mentalfunctionswithin theecosystem orlandscape andwith otherecosystemsandnearbylandscapes.

Conﬂictofinterest

Theauthorshavenoconflictsofinteresttodeclare.

Acknowledgments

Francisco Bautista thanks Dirección General de Asuntos del Personal Académico (DGAPA) of Universidad Nacional AutónomadeMéxico(UNAM)forthefinancial supportfora sabbaticalstayatCEBAS-CSICinSpain.AngelesGallegosand EduardoGarcíathankthefinancialsupportfromSkiu.

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