Effectiveness*of*Equipment*to*Speed*Hay*Drying C.*Alan*Rotz,* Hay*Drying

Transcription

1 Effectiveness*of*Equipment*to*Speed*Hay*Drying by#c.*alan*rotz,*agriculturalengineer USDA1ARS,PastureSystemsandWatershedManagementResearchUnit UniversityPark,PA16802 Highqualityforageisrecognizedasanimportantrequirementformaintainingmaximumproductionof cattle,particularlyindairyproduction.adequateroughageisneededindietstoprovidegoodrumen function,butasmoreroughageisfed,theenergydensityofthedietisreduced.highqualityforage allowstheanimaltoconsumeadequateforagewhileincreasingenergyintaketomaximizeproduction. Thegreatestobstacletoproducinghighqualityhayisrapidfieldcuring. Inourclimate,gooddryingconditionsareimportantanddifficulttoobtain.Adequateperiodswithout rainfallaresporadicandhardtopredict.althoughprocessesareavailabletospeedhaydrying,they mustbeusedalongwithgooddryingweathertobeeffective.newequipmentandprocesseshavebeen promotedtomakebetterhay,butfewhaveproventobeeffectivetools. Althoughhighqualityhayproductionisachallengeinourregion,therearepracticalstepsthatcanhelp. Usingtherightprocessattherighttimeisimportant.Conditioningandteddingtreatmentscanspeed drying,butsuchprocessesalsocauseloss.drymatterlossandnutritivechangesoccureachtimea machinepassesthroughthecropreducingthequalityofthefinalproduct.althoughsomelossis inevitable,goodmanagementcanreduceorcompensatefortheselossestoprovidethequalityforage needed.thebenefitsreceivedfromthesetreatmentsorprocessesmustbeweighedagainsttheadded coststodeterminethebestproceduresforhaymakingonyourfarm. Hay*Drying Theneedforrapidwiltingordryingofforagecropsinthefieldiswellrecognized,butaccomplishingthis taskremainsachallenge.manyfactorsaffectthefield1dryingrateofforage(rotz,1995).dryingis restrictedbythestructureoftheplant,swathstructure,andsoilandweatherconditions.themost restrictingfactorvariesthroughoutthedryingprocessandwithcropmanagement.whenahighyield cropislaidinanarrowswath,theswathtendstobemostlimitingbecausethemoisturecannotreadily moveoutoftheswath.whenforageisspreadinathinswath,themovementofmoistureoutofthe plantcanbecomelimiting.underthesecircumstances,conditioningofthecropismostbeneficialin allowingmoisturetoleavetheplantmoreeasily. Intemperateclimates,weatherisoftenthemostrestrictingfactorindrying.Ofallweatherinfluences, solarradiationlevelisthemostimportant(rotz,1995).thisenergyfromthesunisrequiredto evaporateandmovemoistureoutoftheplant.thedryingofhayrequirestheremovalofaboutthree tonsofmoistureforeverytonofhayproduced.thisrequires7billionjoulesofenergy,whichisthe

2 equivalentof70gallonsoffueloil.inhaymaking,wearefortunatethatfreeenergyfromthesuncanbe usedtocarryoutthisprocess.beskepticalwhenyouhearofnew,miraculousandinexpensiveprocesses thatcandryhaywithoutthesun.warmairtemperatureandlowhumidityalsoaidsdrying,butthesun istheprimarydrivingforce.wetsoilundertheswathalsoslowsdryingbyallowingmoisturetomoveup intotheswath. Drymatterlossesandqualitychangesoccurwhilethecropiswiltingordryinginthefield.Theseinclude plantrespiration,rain,andmachineinducedlosses.plantrespirationisanaturalprocessthatcontinues aftertheplantiscut.respirationconvertscarbohydratesstoredintheplanttissuetocarbondioxide, heat,andmoisturethatleavetheplantcausingadmloss.plantrespirationceaseswhenthecropdries toamoisturelevelbelow40%,sorapiddryingearlyinthefieldcuringprocesscanreducethisloss(rotz andmuck,1994).sincethislossisprimarilyreadilydigestiblecarbohydrates,thelossincreasesthefiber contentandreducestheenergycontentoftheforage.withrapiddrying,thislossislessthan5%,butit canbeexcessivewhendryingconditionsarepoor. Raindamage,whenitoccurs,canhavethegreatesteffectonlossandquality.Raincauseslossby knockingoffleavesandleachingsolublenutrientsfromwithintheplanttissue.sinceleavesarenormally higherinnutrientconcentrationsthanstemparts,thelossofleavesreducesthequalityoftheremaining forage.thegreaterlossthoughisthelessvisiblelossfromleaching.solublecarbohydrates,proteins, andmineralsarewashedfromtheplantmaterialleavingahigherfiberconcentrationandlowerenergy content.ingeneral,thegreatertheamountofrainandthedrierthecropatthetimeoftherain,the greaterthelossofdrymatterandnutrients.thegoalisalwaystoavoidraindamage,butwhenitoccurs, itisbettertohaveitearlyinthedryingprocessratherthanaboutthetimethecropisreadytobale.this issomewhatbeyondourcontrol,buttheproducercanbelessconcernedaboutrainthedayofmowing ifbetterweatherliesahead. Mowing*Equipment Producinghighqualityforagebeginswhenthecropismown.Foragecropsshouldbemownattheright maturitytooptimizeyieldandquality.qualityinmostforagecropsdeclinesratherrapidlyasthecrop entersareproductivestageofdevelopmentandgrowthbeginstoslow.theoptimummaturityvaries amongforagespecies,butnormallythisoptimumoccursinthelatevegetativetoearlyreproductive stages.mowingatthistimeprovidesagoodyield,arelativelylowfibercontentandadequateenergy andproteincontents. Achallengeinhayproductionistoobtainthisqualitylevelatatime1periodwhenweatherconditions aresuitablefordryingthecrop.whenheavyrainandpoordryingconditionsareexpected,itisnormally besttodelay.iftheforecastislightrainorabriefthunderstormwithadequatetogooddrying conditionsahead,itmaybebesttoproceedwithmowing.thelossinqualitymaybegreaterbydelaying harvestthenthatcausedbytherain. Thereareseveralmowerdesignsavailableforcuttingforagecropswiththeprimarytypesbeing cutterbarandrotarydiskmowers.thetypeofmowerusedhaslittleeffectondrying,mowinglossesand theresultingforagequality.rotarymowerstendtohaveahigherpowerrequirementandthusrequirea largertractorandmorefueltooperate.withahighermowingcapacity,though,lesstimeisrequired offsettingsomeoftheincreasedfueluseandreducingthelaborrequired.eventhoughthepurchase priceofrotarymowersisalittlehigherforagivenwidthofcut,theoverallcostofmowingissimilar betweenthesemajormowertypes.

3 * Conditioning*to*Speed*Drying Mechanicalconditioningtreatmentsareoftenusedtospeeddrying;thesecanbecategorizedaseither rollorflailconditioners.rollssmashand/orbreaktheplantstems,andflailsabradethewaxysurfaceof the plant and break stems. Both processes can improve drying, but for alfalfa, roll devices are more effectivewithlessfieldloss(rotz,1995).somerolldesignsarepromotedforfasterdrying,butfieldand laboratorystudiesconsistentlyshowlittleornodifferenceinthedryingofalfalfaorgrasstreatedwith commonlyusedcrushingrolldesigns.rollconditioningismosteffectiveonathickstemmedcropsuchas anearlycuttingofalfalfa.flailtypeconditionersarebettersuitedtograsscrops,andtheyprovidea greaterthroughputcapacitywhenharvestinghighyieldingorentangledcrops. Adjustmentoftheconditioningmechanismcanaffectdrying.Rollclearanceandpressureoftencanbe adjusted. A minimum clearance must be maintained. If the clearance becomes too close, excessive damageandlossofplantparticlesoccurs.withtoomuchclearance,plantmaterialflowsbetweenthe rollswithlittlecrushing.toolittleortoomuchpressureontherollshassimilareffects.onflailtype conditioners,theclearancebetweentherotatingflailsandastationarybarcanbeadjustedtocontrolthe amountofbreakingandabrasionthatoccurs. Drymatterlossesandtheassociatednutrientchangescausedorpromotedbyconditioningincreasewith cropmaturityandtheseverityofconditioning.althoughmoresevereconditioningcanprovidefasterfield curing,harvestlossesaregenerallygreater.normallymoderateconditioningisrecommendedtoobtain adequatedryingwithrelativelylowloss(112%ofyield).thisrelativelylowlosshaslittleeffectonforage quality. Considerableresearchanddevelopmenthasbeendevotedto intensiveconditioning overthepast20 years.severalmachinedesignshavebeenevaluated,whichshredtheplantmaterialtoallowmorerapid fieldcuring.dryingrateisincreasedby25to150%withthefastestdryinginthinwideswathsundergood dryingweather.powerrequirementisatleasttwicethatofamower1conditioner,andfieldlossescanbe veryhigh.toreducelosses,variousmethodshavebeenusedtopresstheshreddedmaterialintoamat. Whenrainoccurs,lossescanstillbeuptofourtimesgreaterthanregularconditioning.Duetoacomplex andexpensivemachinedesign,commercialapplicationhasnotoccurred. Achemicaltreatment,referredtoasaconditionerordryingagent,canbesprayedonalfalfaatmowing tohelpspeeddrying(rotz,1995).thechemicalaffectsthewaxysurfaceoftheplanttoalloweasier moisture removal. The most effective treatment found, is a potassium and sodium carbonate based solution. This treatment has only been effective on legume forage crops, and it is most effective on cuttingsharvestedinthesummermonths.chemicalconditioningworkswellwithmechanicalconditioning becauseitismosteffectiveonthecropswheremechanicalconditioningisleasteffective.thetreatment candoublethedryingrateofthecropwhenusedundergooddryingconditionswiththecropdriedina relativelythinswath.ontheaverage,thisincreasereducesfield1curingtimeabouthalfaday.fasterdrying reducesrespirationlossandoccasionallyavoidsraindamage.themajordeterrenttothisprocesshas beentheneedtohandlelargequantitiesoftheliquidtreatment(about30gallonsofsolutionperacre). * Swath*manipulation*to*speed*drying Asforagedriesinthefield,thetopoftheswathdriesmorerapidlythanthebottom.Manipulationofthe swathcanspeedthedryingprocessbymovingthewettermaterialtotheuppersurface(rotz,1995). Swath manipulation can also improve drying by spreading the hay over more of the field surface,

4 increasing exposure to the radiant solar energy and drying air. There are three operations used in haymakingtomanipulatetheswath:tedding,swathinversion,andraking. Teddingcanbeusedanytimeduringfieldcuring,butitisbesttodosobeforethecropistoodry(above 40%moisturecontent).Thestirringorfluffingofforagetypicallyreducesfield1curingtimeuptohalfa day.teddersaresometimesusedtospreadanarrowswathformedbythemower1conditioneroverthe entirefieldsurface.whendonesoonaftermowing,theaveragefieldcuringtimeisreducedupto2days comparedtodryinginanarrowswath.inadditiontospeedingdrying,teddingalsotendstocreatemore uniformdrying,sowetspotsintheswatharereduced. Disadvantagesofteddingincludeincreasedlossesandincreasedfuel,labor,andmachinerycosts.When teddingisdoneonarelativelywetcrop(above50%moisture),theresultinglossislessthan3%;however, appliedlateinthedryingprocess,thelosscanbemorethan10%.teddingwillalsoincreaserakingloss. Whenalightcrop(lessthan1ton/acre)isspreadoverthefieldsurface,rakinglosscanbemorethan doublethatwhenrakingnarrowswaths.spreadingthehaymaypromotebleachingofhaycolor.bleaching doesnotnecessarilyaffectthenutritivevalueofhay,butitoftenaffectsthemarketvalue.whenthecosts of performing the tedding operation are compared to the benefit received, routine use of tedding is difficulttojustify,particularlyforalfalfa.occasionaluseunderdifficultdryingconditionsmaybringgreater economicbenefit. Swath inversion machines have been used that gently lift and invert the swath. Exposing the wetter bottomoftheswathspeedsdrying,reducingtheaveragefield1curingtimeafewhours.swathinversion isnotaseffectiveforimprovingdryingastedding,butshatterlossisverylow.withlessdryingbenefit, thereislesspotentialforreducingrainandrespirationlosses.theaddedlabor,fuelandmachinerycosts oftheoperationaregenerallygreaterthanthebenefitreceived. Rakingisanotherformofswathmanipulation.Rakingtendstorollthewetterhayfromthebottomofthe swathtotheoutersurfaceofthewindrow,whichimprovesdrying.followingtheinitialimprovement,the increaseinswathdensitycanreducedryingrate,sothecropmoisturecontentatrakingisimportant. Rakingalsocausesloss,andthelossisrelatedtocropmoisture(2%whenwetto15%inverydrycrop). Thebestmoisturecontenttorakeforlowlossandgooddryingisbetween30and40%.Indryweather periods,haycanberakedintheeveningorearlymorningwhenleavesaremoistandlesspronetoshatter. Rakingatthepropertimecanreducefield1curingtimeafewhourstoallowanearlierstartatbaling. Inhaymaking,thebestrecommendationistodryhayrapidly.Mechanicalconditioningshouldbeused, andhighyieldingcropsshouldbespreadinwideswaths.teddingmaybeusefulindryinggrasscrops,but itshouldbeavoidedwithalfalfa,particularlyafterthecrophaspartiallydried.insilagemaking,dryingis alittlelesscritical.wiltinginnarrowswathscanreducerakingloss,particularlyforlowyieldingharvests. Rakingcanbeusedtoimproveharvestcapacity.Asubstantialeconomicbenefitcanoftenbeobtainedby rollingswathstogethertoallowlargebalersorforageharvesterstooperatemoreefficiently. Baling*High*Moisture*Hay Anotheroptionforshorteningthefieldcuringtimeistobalehaybeforeitisfullydry.Balersareavailable whichproducebalesofawidevarietyofshapesandsizesandthesafemoisturecontentforhaystorage varieswithsize.balingattheappropriatemoisturecontentisimportantforminimizingharvestlossand maintainingqualityfollowingharvest.forlow1density(smallrectangularandmostlargeround)bales,the recommendedbalingmoisturecontentisabout18%.forhigh1densitybales(largerectangular),drierhay

5 intherangeof12to14%isrecommendedtoimprovepreservation.harvestlossincreaseswhenhayis baledatlowermoisturecontents. Respirationofmicroorganisms(bacteria,fungi,andyeasts)onhaycausesheatingandfurtherDMand nutrientlossduringstorage.similarlossoccursinallsizesandtypesofbalesstoredinashed(rotzand Muck,1994).Greaterheatingoccursashaydensityincreases,particularlyinlargebales.Drymatterloss during the first month of storage varies from 1 to 8% increasing with hay moisture content. For hay containing more than 25% moisture, excessive loss and even spontaneous combustion can occur. Althoughmostlossoccursinthefirstmonth,asmalllossofabout0.5%DMpermonthcontinuesinhay storedinashed.unprotectedhaystoredoutsideexperiencesthissamelossplusanadditionallossfrom weatheringontheexposedbalesurface(outer10to20cm).lossesinlargeroundbalesstoredoutside varywidely,rangingfrom3to40%.thislossisprimarilyaffectedbyweather,lengthofstorage,and storagemethod. Fieldlossescanbereducedbybalingatamoisturecontentnear25%.Balingmoisthaymayreduceraking andbalinglossesprovidinganincreaseinharvestedyield(about7%)andharvestedquality.however, moisthaydeterioratesrapidlyinstorage,offsettingthebenefitofreducedfieldlossesunlesstreatedto enhance preservation. Additives commonly used for the preservation of high1moisture hay include propionicacid,organicacidmixtures,bufferedacidmixtures,andmicrobialinoculants. Propionicacid(oraneffectiveorganicacidmixture)whenappliedatratesof1to2%ofhayweight, normallyreducesmoldgrowthandheating.toreducecorrosionofequipment,bufferedacidproducts havelargelyreplacedthestraightacids.acidtreatmentreducesstoragelossduringthefirstfewmonths ofstorage,butthelossremainshigherthanthatindryhay.acid1treatedhayremainsmoisterthroughout storagemaintainingalittlehigherlevelofmicrobialactivity.overa61monthstorageperiod,thelossin acid1treatedhaycatchesup,providinglittledifferenceindrymatterandnutrientlossesbetweentreated anduntreatedhigh1moisturehays.whencomparedtodryhay,acid1treateddamphayisoftenhigherin fibercontentandlessgreenincolor.treatedhaywillcontainmoremoistureincreasingbaleweightand providingmoresupplehay. Bacterialinoculantsaresometimesappliedtohay.InoculationwithafewstrainsofLactobacillushave shownlittleeffectonmold,color,heating,dmloss,andqualitychangeinhigh1moisturehay.products containing Bacillus bacteria are better suited to the aerobic hay environment, but there is still little scientificevidencethattheycanprovidesubstantialimprovementinpreservingmoisthay. Based upon the scientific information available on chemical and biological treatments, my recommendationistobaledryhaywheneverpossible.whenmoisthayisbaled,organicacidtreatments canprovidearelativelysafemethodforinsuringagainstexcessiveheatingandbrowningofhay. Feeding*Considerations Forthecommercialhayproducer,highqualityhayisimportanteverytimehayismade.Whenhay qualitysuffersforanyoftheabovereasons,theeconomicvalueofthehaydecreasesandthisaffects farmprofit.thus,commercialhayproductionrequiresgoodmanagementalways,andtechniquesfor assuringqualitymaybemorecosteffectivethantheywouldbeforthelivestockproducer. Whenhayisproducedforon1farmuseinfeedingbeefcattleandevendairycattle,foragequalitycanbe lessimportant.thisassumesthoughthatgoodmanagementisusedtofeedthehighestqualityforageto

6 theanimalsthatrequirethatquality.fordairyanimalsinearlylactation,thehighestqualityforageis neededtomaximizetheirintake.maximizingintakeduringthiscrucialstagewillallowanimalstopeak theirproductionatahighlevel.thus,thevalueofforagequalitycannotbeoverestimatedforthese animals.forotheranimals,includingthoseinthelasthalfoftheirlactation,earlydrycowsandyearling heifers,foragequalityislesscritical. Thus,producersthatarefeedinganimalsmustfocusonproducingorbuyingthebestforagetheycan obtainfortheircriticalgroupswhilereservinglowerqualityforageforotheranimals.thismeansthat onlyone1fourthtoone1thirdofthetotalforageneededondairyfarmsmustbeofthishighestquality.in beefoperations,therequirementforhighqualityforageisevenless.forthedairyproducerthatkeeps thisinmind,producinghighqualityforagewillbealessstressfulprocess.concentrateonmakingsome ofthebestforageyoucanandfeedingitappropriately,anddonotworryaboutthetimesyoufail.some lowerqualityforagecanalsobeusedquiteeffectivelyonthefarm. Conclusions Rapidfieldcuringisimportantandagoodmechanicalconditionercanhelp.Spreadhayinwideswathsto furtherspeeddrying,butavoidverythinswathstoreducerakingloss. Teddingmaybeusefulindryinggrasscrops,butitshouldbeavoidedwithalfalfa,particularlyafterthe crophaspartiallydried. Balehayatabout18%moistureinlow1densitybales,butusealowermoisturecontentforhigh1density largebales. Avoidroutinebalingofhighmoisturehay.Whendamphayisbaled,useanorganicacidbasedtreatment tohelppreservehay. Rememberthatonthedairyfarm,onlyaboutonethirdoftheforageneedstobeofthehighestquality whenthatforageissegregatedbyqualityandfedtoanimalgroupsaccordingly. References Rotz,C.A.andR.E.Muck.1994.ChangesinForageQualityduringHarvestandStorage.In:ForageQuality, Evaluation,andUtilization,Eds.G.C.Fahey,Jr.etal.Am.Soc.Agron.,Madison,WI.pp Rotz,C.A.1995.FieldCuringofForages.In:Post1HarvestPhysiologyandPreservationofForages.CSSA SpecialPublicationno.22.CropSci.Soc.Agron.andAm.Soc.Agron.,Madison,WI.pp