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Backyard Composting of Yard Waste

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Title:
Backyard Composting of Yard Waste
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Nordstedt, Roger A.
Place of Publication:
Gainesville, FL
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University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
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Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Melanie Mercer.
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"Publication date: November 1991."
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"Circular 958"

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This document is copyrighted by the University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS) for the people of the State of Florida. UF/IFAS retains all rights under all conventions, but permits free reproduction by all agents and offices of the Cooperative Extension Service and the people of the State of Florida. Permission is granted to others to use these materials in part or in full for educational purposes, provided that full credit is given to the UF/IFAS, citing the publication, its source, and date of publication.

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Circular958 November1991BackyardCompostingofYardWaste1 RogerA.Nordstedt,AnneW.BarkdollandM.ElizabethWill2WHATISCOMPOSTING?Compostingisabiologicaldecompositionof organicwastesbybacteria,fungi,worms,andother organismsoccurringundercontrolledaerobic conditions.Theorganismsusecarbon,nitrogen,and othernutrientsreleasedfromtheorganicmatter duringthedecompositionprocess.Theresultisan accumulationofdark,friable,partiallydecomposed material.Inthehomeyard,theprocesscanbe managedbyplacingtheraworganicmaterialsina backyardcompostingstructure.Rawmaterialsfor compostingincludeleaves,pineneedles,twigs,grass, andvegetablewastesfromthegardenandkitchen. Propermanagementisakeyfactor,sincean unmanagedcompostheapmaybecomeaneyesore andanodornuisance.WHYCOMPOST?Compostingofyardtrashisanenvironmentally soundwayofreducingsolidwastebyrecyclinga usefulresourcewhereitisgenerated.Yardtrash materialmakesupabout20%ofthevolumeof collectedmunicipalsolidwaste,andseasonallyitmay accountforupto80%.Keepingthismaterialoutof thewastestreamwillextendtheusefullifeofexisting landfillsandslowtheneedtoacquiremorelandfor futurelandfills.Compostingalsocreatesausefulsoil amendment.Mostpeoplecompostforpersonal reasons,suchastheneedfororganicmaterialinthe garden,and/orasawayoffulfillingtheircommitment torecycling.Whateverthemotivation,an understandingoftherequirementsforsuccessful compostingisnecessary.WHATCANBECOMPOSTED?Manytypesoforganicmaterialsarereadily composted.Yardtrashsuchasfallenleaves,remains ofgardenplants,non-woodyplanttrimmings,and grassclippingscanbecomposted,aswellasvegetable kitchenscraps.Some"raw"(uncomposted)organic materials,suchasgrass,weeds,andgreengarden plantwaste,containfairlylargeamountsofnitrogen. Others,suchasleavesandsmalltwigs,containmuch lessnitrogenandahigherproportionofcarbon. Materialswithhighernitrogenlevelsmaydecompose sorapidlythatsomeofthenitrogenandother nutrientsarelostbeforetheycanbeusedbygrowing plants.Excessnitrogenlevelsmayalsocausenitrogen tobelostasammoniathuscausingodorproblems. Materialscontaininglowlevelsofnitrogenandhigh levelsofcarbonmaycausenitrogendeficienciesinthe plantsiftheyareaddeddirectlytothesoil.Thisis causedbythemicroorganismswhichusenitrogenas theydegradeorganicmaterialthuscompetingwith theplantsfornitrogen.Ifnitrogenispresentin insufficientquantitiesplantnitrogendeficienciesmay result.Toavoidthisproblem,rawmaterialswithhigh nitrogenshouldbecombinedwiththosewithlow nitrogen.Thiswillresultinabettercompost. 1.ThisdocumentisCircular958(availableonlyviaCD-ROM),FloridaCooperativeExtensionService,InstituteofFoodandAgricultural Sciences,UniversityofFlorida.Publicationdate:November1991. 2.RogerA.Nordstedt,associateprofessor;AnneW.Barkdoll,post-doctoralassociate;M.ElizabethWill,formerpost-doctoralassociate, AgriculturalDepartment,CooperativeExtensionService,InstituteofFoodandAgriculturalSciences,UniversityofFlorida,GainesvilleFL 32611. TheInstituteofFoodandAgriculturalSciencesisanequalopportunity/affirmativeactionemployerauthorizedtoprovideresearch,educational informationandotherservicesonlytoindividualsandinstitutionsthatfunctionwithoutregardtorace,color,sex,age,handicap,ornational origin.Forinformationonobtainingotherextensionpublications,contactyourcountyCooperativeExtensionServiceoffice. FloridaCooperativeExtensionService/InstituteofFoodandAgriculturalSciences/UniversityofFlorida/ChristineTaylorStephens,Dean

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BackyardCompostingofYardWaste Page2Withproperlawnmanagement,grassclippingsdo notneedtoberemovedfromthelawn.Ifgrass clippingsarecollectedandcomposted,theyshouldbe mixedwithotheryardwastetoprovidebulkanda properratiooftwoimportantplantnutrients,carbon andnitrogen(C/N).Otherwise,theclippingsmay compactandrestrictairflowinthecompostpileand causeunpleasantodors. Twigs,branchesgreaterthan1/4inchindiameter andfibrouspalmfrondsshouldbeprocessedina shredder/chipperbeforecomposting.Leaves, especiallywaxytypessuchasliveoak,laureloak, wateroak,andmagnolia,alsobenefitfrombeing shreddedbeforecomposting.Largerwoodymaterial canalsobecompostedbutrequiresalongertimeto decompose.Whenchippedtoasmallsizeand supplementedwithanitrogensource,decomposition canbeaccelerated. Mostplantdiseaseorganismsandplantseedsare destroyedbyhightemperatures(130-140F).These hightemperaturesmaybereachedinthepileduring propercomposting,howeveritisusuallydifficultina homecompostingsystemtomixapilewellenoughto bringallwastestothecenterandassurecomplete destructionofseedsandpathogens.Thisbeingthe case,itisnotadvisabletoaddlargeamountsofseedladenweedsordiseasedplantstothecompostpileif theresultingcompostistobeusedinthegarden. Thehightemperaturesgeneratedincompostalso inhibitharboringandbreedingofinsectsinthe compostpile.Plantstreatedwithpesticidesshould notbeaddedtothecompostpile. Kitchenwastes,suchasvegetableandfruitscraps, coffeegrounds,andeggshells,mayalsobeaddedto thecompostpile,buttheyshouldbeincorporated immediatelytoavoidodors.Althoughmeatscraps, fat,bones,grease,anddairyproductsare compostable,theyshouldnotbeincorporatedinthe homecompostpile.Theseitemsattractanimals, createnuisanceodors,andareslowtodecompose. Sawdustmayalsobeaddedtothecompostpilein moderateamountsifahighnitrogenmaterialisbeing compostedorifadditionalnitrogenisapplied. Approximately1poundofnitrogen(6cupsof ammoniumnitrate)isrequiredforevery100pounds ofdrysawdust.Woodashesareasourceoflimeand shouldbeaddedtoacompostpileonlyinsmall amountsifatall.Largeamountsoflimewillcause lossofnitrogenfromthepile. Althoughordinaryblack-and-whitenewspaperis compostable,ithasalownitrogencontentand decomposesslowly.Ittendstocompactandrestrict airflowunlessshredded.Itisrecommendedthat newspaperberecycledratherthancomposted.Other organicmaterialsthatcanbeusedtoaddnutrients, particularlynitrogen,toacompostpileinclude livestockmanures.COMPOSTINGPRINCIPLESRapidcompostingrequiresanenvironmentin whichmicroorganismswillthrive.Optimummoisture, aeration,temperature,particlesizeandcarbonto nitrogenratioareimportantforefficientcomposting.MoistureMicrobialactivityrequiresadequatemoisture, usually40-60%.Atthismoisturelevel,ahandfulof thecompostwillfeelwetbutwatercannotbe squeezedoutofit.Thecompostpilemustbekept moist,butnotsoggy.Materialswhicharetoowetwill compactandrestrictthemovementofairthroughthe pile.Itmaybenecessarytoaddmorewaterduring thecompostingperiodiftheweatherisdry.AerationMicrobesactiveincompostingrequireoxygento efficientlybreakdownorganicmaterials.Bulky materialssuchasleaves,pineneedles,chippedtwigs, andstrawkeepthecompostpilefromsettlingand allowairtoenter.Thecompostpileshouldbe periodicallyturnedormixedtoincorporateoxygen. Heatisgeneratedbythemicrobesduringthe decompositionprocess.Turningalsoshiftsmaterial fromtheouter(cooler)partofthepiletothecenter (hotter).Thefrequencyofturningdependsuponthe materialsbeingcomposted,thecomposttemperature andthemoistureconditions,butgenerallyshouldbe doneonaweeklybasisinwarmweather.Turning shoulddefinitelybedoneifthetemperatureinthe centerofthepilereaches140Forifodorsare present.TemperatureTemperatureisafunctionofpilesize,oxygenand moisturecontent.Toreachtemperaturesdesirablein composting,apilemustbelargeenoughtoprovide aninsulatingeffectfortheinteriorofthepile. Temperatureisanimportantenvironmentalfactor affectingbiologicalactivity,andcompostingis

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BackyardCompostingofYardWaste Page3dependentonthisactivity.Eachtypeoforganismhas anoptimumtemperaturerange.Compostingis designedtofunctionintherangeof95F-160F. Themosteffectiverangeforcompostingseemstobe 122F-131F.Highertemperaturesof131F-140F maybedesirabletodestroyweedseedsorplant pathogens.Attemperaturesabove149Fmanyofthe organismsinvolvedincompostingbecomeinactiveor die.ParticlesizeReductionintheparticlesizeofrawmaterialswill increasethespeedofthecompostingprocessby increasingthesurfaceareaavailableformicrobesto attack.Itisthereforeagoodideatoputsmalllimbs andtwigsthroughachipperbeforecomposting. Leavesmaybeprocessedinashredderorcutupwith alawnmower,preferablywithamulchingattachment. Thiswillbreakthewaxycoatingandexposethemore easilydegradedinteriorofleaves.Sizereductionalso reducesthevolumeofthecompostpile,thereby savingspace.Particlesizecouldbetoosmallifthe pilewereconstructedofmaterialthesizeofsawdust. Thiswoulddecreaseaeration,reducetherateof compostingandperhapscauseanaerobicconditions.NitrogenlevelMicrobialactivityisaffectedbytheC/Nratioof organicmaterial.Materialshighincarbonrelativeto nitrogen(i.e.C/N>30),suchasstrawandsawdust, willdecomposeveryslowlyunlessasourceofnitrogen isadded.MaterialswithalowC/Nratioaregood sourcesofnitrogenandincludemanure,inorganic fertilizer,vegetabletablescrapsandgrassclippings. TheoptimumC/Nratioforrapidcompostingisabout 30/1orless.TheapproximateC/Nratioformaterials (Table1)commonlyusedinbackyardcomposts rangesfromabout15to600.DESIGNINGANDBUILDINGACOMPOSTERThetypeofcomposterwhichisusedshouldbe theonethatbestsuitstheneedsandcapabilitiesof theuser.Theyvarygreatlyinexpenseandinthe amountofphysicallaborrequiredtomanagethem. Severaltypesofunitsaredescribedbelowthatcanbe madeathome,althoughunitsofsimilardesigncan alsobepurchased. Table1. ApproximateC/NRatioforvariousmaterials commonlyusedinbackyardcomposts. Material C/NRatio FruitWastes 35 GrassClippings 20 Leaves 60 RottedManures 20 Sawdust/Wood 600 Straw 100 TableScraps 15 Figure1. DrumComposterDrumcomposterIfyouhaveasmallamountofwasteorwantto makeonlyasmallamountofcompost,composting canbedoneinacoveredgarbagecanorothermetal orplasticcan(Figure1).Holes(tinchindiameter) shouldbemadeinthesidesandbottomofthedrum anditshouldbesetuponblockstoallowair circulationandwaterdrainage.Thematerialcanbe mixedandaeratedwithagardentoolorbyturning thedrumonitssideandrollingitaroundonthe groundifithasasecuredlid.Thedrumcanalsobe placedonrollersorcasterstomaketurningeasier. Moreelaboratedrumcomposterscanbefabricatedby mountingthebarrelonapipe.Thepipecanbe placedthroughthesidesorthroughtheendsofthe barrel.Reinforcingcanbeprovidedwithapipefloor flange.Pipefloorflangesareavailableatmost hardwarestores.Thebarrelcanbesuspendedby supportingthepipesonposts,blocks,orother structure.Ahingeddoorcanalsobeplacedonthe barreltofacilitateloadingandunloadingofthedrum composter.Turningofthecompostingmaterialis alsomucheasierwiththistypeofdrumcomposter.

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BackyardCompostingofYardWaste Page4 Figure2. WovenorWeldedWireBinWovenorweldedwirebinAnothermethodistobuildapilewithinapenof flexiblewovenwireorsnowfencing(Figure2).The structuremaybe3to5feetindiameterand4feet high.Advantagesofthisdesignarethataircan circulatefreelythroughthepile,anditiseasyand inexpensivetorelocate.Toturnthepile,thewire cylinderisdisconnected,removedfromaroundthe currentpile,andsetupagaincloseby.The compostingmaterialcanthenbeplacedbackinthe newlylocatedbin.Thisdesigncanbemademore stableandeasiertomanagebyattachingthewireto woodormetalfencepostswithagateorremovable panelononeside.Thematerialwouldbeturned withapitchforkoracompostturner(described below).Three-chamberbinAdurablestructureforrapidcompostingisthe three-chamberbin(Figure3).Itholdsafairlylarge amountofcompostandallowsgoodaircirculation. Thisdesignworksasanassemblylinewiththe compostineachbinbeingatadifferentstageinthe decompositionprocess.Therawmaterialisstartedin thefirstbinwhereitisallowedtoheatupfor1to2 weeks.Itisthenmovedintothenextbinandleftfor another1to2weekswhileanewbatchisstartedin thefirstbin.Finally,thematerialinthemiddlebin isplacedinthelastbintocuretoafinishedcompost. Thistypeofstructureisnotlimitedtothreebins. Fourormorebinsmaybeconstructed,alwaysleaving atleastoneemptybinforfreshmaterial. Goodconstructionmaterialsforthethreechamberbinarewoodthathasbeentreatedwitha preservativetopreventrottingandvinyl-coatedwire mesh.Eachbinshouldbeabout3feetby5feetand Figure3. Three-ChamberBin3ormorefeethigh.Thefloorinthebinscanbe earthen,wood,orotherporousmaterial.Removable woodslatsonthefrontofthebinscanbeheldin placebyposts.Theslatswillincreasethecapacityof thebinsandmaketheloadingandunloadingofthe binsmucheasier. Thethree-chamberbincanalsobemadewith concreteblocksorbrickslaidtogether.Spacesmay beleftbetweenthebricksorblockstoallowfreeair circulationintothecompostmaterial.Theblockscan alsobemortaredorfastenedtogetherwithsurface bondingcementforamorepermanentstructure. However,provisionsshouldbemadeforaeration holesiftheblocksaremortaredorbondedtogether.COMMERCIALLYAVAILABLECOMPOSTERS ANDACCESSORIESSeveraltypesofcompostunitsandavarietyof usefulaccessoriescanbepurchasedfromgarden supplystoresandmail-ordercatalogs.The compostingunitsrangeinpricefromlessthan$100 toafewhundreddollars.Theyofferanalternativeto thosewhodonotwanttoconstructtheirownunit. Durabilityandeaseofloading,unloading,andturning areimportantfeaturestolookforinacomposter. Thecommercialcomposters,designedtomake theprocessaslaborfreeandattractiveaspossible, aregenerallyoftwodesigns;drumtumblers(Figure 1)andbins(Figure2andFigure3).Thebinsare constructedofeitherplasticorgalvanizedmetal,sit directlyontheground,havehingedorremovablelids, andareattractivelymadeandanimal-resistant. Loadingandturninginstructionsareusuallyprovided withthecomposter.Thedrumstylecompostersare metalormoldedplasticbarrelsmountedonastand, eitherverticallyorhorizontally.Thematerialis loadedandunloadedthroughadooronthesideor ononeend.Thecompostisturnedbyrotatingor tumblingthedrum.Desirablefeaturesincludequality ofconstruction,heightandsizeoftheloadingdoor, andeaseofturning.Theloadingdoorshouldbehigh enoughtoaccommodateawheelbarrowbutnotso

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BackyardCompostingofYardWaste Page5highastonecessitateliftingthematerialabovethe Figure4. CompostAccessories:compostturner, thermometer,screen.waistduringloadingandunloading.Thevertical drumunitstendtobealittlemoreawkwardtoturn whenthedrumisfull. Availableaccessoriescanmakecompostingmore efficientandeasier.Asnotedearlier,iftheparticle sizeoftherawmaterialgoingintothecomposteris smaller,thecompostingprocesswilltakelesstime. Severalshreddersandchipperspoweredbyanelectric motororgasengineareavailable.Choosingthe properequipmenttodothejobisimportant. Machinesthatarecalled"leaf-shredders"areoften inexpensiveandpoweredbyelectricity.Thecutting oftheleavesmaybedonewitharapidlyrotating, replaceablenylonfilament.Theyarenotdesignedto shredlargematerial.Chipper/shredders,ontheother hand,comeinseveralsizesdependinguponthesize ofmaterialtobeprocessedanddesiredcapacity. Theyareconsiderablymoreexpensivethanleaf shredders,rangingfromafewhundredtoseveral hundreddollars. Otheraccessoriesincludethermometersfor measuringtheinternaltemperatureofthecompost pileandscreensforprocessingthefinishedcompost (Figure4).Thescreenscanbeusedtoremove materialstoberecycledforfurthercomposting,orto sizethecompostforspecificenduses.Thereisalso acompostturneravailablethat,wheninsertedintoa compostpileandthenwithdrawn,pullsmaterialfrom insidethepiletotheoutside(Figure4).Thisaction mixesandaeratesthecompostingmaterial.Various typesofinoculumarealsoavailableforcompostpiles. Theorganismsnecessaryforcompostingarerarelya limitingfactorastheyarealreadypresentonthe materialtobecomposted.Researchhasnotshown inoculumadditontobenecessaryforcomposting exceptperhapsinspecialcases.Theseaccessoriescan bepurchasedthroughmailordercatalogsadvertised ingardeningmagazines.GETTINGSTARTED-BUILDINGTHE COMPOSTPILEChoosealocationforthecompostpilewhichis nearawaterspigot.Considerhowyouwillgetthe rawmaterialstothepileandhowyouwillmovethe finishedcomposttoareasinwhichitwillbeused.A partlysunnyareaprotectedfromdryingwindsand withgooddrainageisbest.Thesizeofthepilemay varygreatlywiththeamountofmaterialsonhand.It shouldnotbelessthan3feethighand3feetwide,or itmaynotmaintainthehightemperaturesnecessary forrapiddecomposition.Drumcompostersshouldbe filledtonomorethanabout2/3oftheircapacityin ordertoassurepropermixing. Thecompostpileshouldbebuiltinlayersorall ingredientsshouldbethoroughlymixed.Thishelps ensurethepropermixingofnitrogen-richandcarbonrichmaterials.Thereareavarietyof"recipes"for addingmaterialstopiles;however,somegeneralrules apply.Successivelayers,each3to4inchesdeep,of differenttypesofmaterialsshouldbeused: 1.nitrogen-containingmaterialsuchasmanure, kitchenwaste,grassclippings,orinorganic fertilizerscontainingnitrogen. 2.bulkymaterialsuchasleaves,chippedtwigs, straw,orsawdust. Watershouldbeappliedbetweeneachcompleted setoflayerstoachievethepropermoisturecontent. Thematerialshouldbewet,butnotsowetthatyou cansqueezewateroutofitwithyourhand.MAINTAININGTHECOMPOSTPILEThecompostpileshouldbeperiodicallymixedto incorporateoxygen(whichisrequiredforcomposting) andtoexposeseeds,insectlarvae,andpathogens (disease-causingorganisms)tothelethaltemperatures atthecoreofthepile.Thiscanbedonewitha pitchfork,shovel,oratoolthatcanbepurchased whichisspeciallymadeforthistask.Checkthe internaltemperatureofthecompostpileregularly andturnthepilewhenitreachesabout140F.Piles shouldbeturnedimmediatelyifammoniaoroffensive odorsassociatedwithanaerobicconditions(lackof oxygenorair)aredetected.Anaerobicconditionscan becausedbytoomuchwaterorbycompaction.

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BackyardCompostingofYardWaste Page6Withinafewweeksafterstarting,thepileshouldbe hotinthecenter.Heatingindicatesthatthematerial iscompostingproperly.Temperatureswithinthe compostpileincreaseduringthedecomposition processandmayapproach150Forhigher.Failure toheatmaybetheresultoftoolittleortoomuch water,alackofnitrogen,airnotgettingintothe centerofthepile(materialpackedtootightly),orthe pilebeingtoosmall.Asthematerialdecomposes,the pilemayshrinktoaboutone-halfitsoriginalvolume. Thecompostingprocessiscompletewhenthereisno heatproducedinthepileafterturningandthe materialisdark,friableanddoesnotcontain distinguishableplantpartslikeleaves. Thecompostisreadytouseafter1to12months, dependingonthedegreeofinitialshreddingandlevel ofmanagement.Thematerialwillbedarkand crumblyintexture,fairlydry,andhaveanearthy odor.Dependingontheintendeduseofthe compost,itmaybedesirabletoputthematerial througha1/2inchscreenbeforeusing.Thelarger particlescanbereturnedtothecompostpileto decomposefurther.USINGCOMPOSTAROUNDTHEHOME SoilAmendmentAlayerofcompost1to3inchesthickmaybe workedintogardensoil.Whenincorporatedinthis way,compostaddssmallamountsofnutrientstothe soilandservesto: 1.increaseasandysoil'sabilitytoretainadded moisture,therebyreducingdroughtdamage, 2.makethesoileasiertocultivate, 3.improvedrainageandaerationofclayeysoils, 4.supplyverysmallamountsofmanyessential elementsneededforplantgrowth, 5.reduceadverseeffectsofexcessiveacidityand overfertilizationbyincreasingthebuffering capacityofthesoil, 6.increasethebiologicalactivityofearthwormsand othersoilorganisms,and 7.allowthesoiltoholdmoreplantnutrientsfor longerperiodsoftime.MulchCompostcanalsobeusedtoreplacematerials suchascypressmulchandstrawasamulching material.Itmaybeappliedina2to3inchlayeron topofthesoilaroundtrees,shrubs,flowers,and gardenplants.Organicmulchesarevaluablebecause they: 1.reducerainfallrunoff,therebyincreasingthe wateravailabletoplants, 2.decreasewaterevaporationlossfromsoil, 3.helppreventsoilerosionlossbywindorwater, 4.helpcontrolweeds, 5.keepthesoilcoolerinhotweatherandwarmerin coldweather,and 6.presentapleasingappearance.PottingMixCompostmayalsobeblendedwithsoil,perlite, sandandothermaterialstomakeapottingmixfor containerizedplants.