SOILTESTINGFOROHIOLAWNS,LANDSCAPES,FRUITCROPS,ANDVEGETABLEGARDENS

O H I O S T A T E U N I V E R S I T Y E X T E N S I O N

extension.osu.eduagnr.osu.edu

HYG1132LastUpdated:07/08/2016

JoeBoggs,AssistantProfessorandExtensionEducator,AgricultureandNaturalResources,HamiltonCountyCindyMeyer,ExtensionEducator,AgricultureandNaturalResources,ButlerCountyGaryGao,AssociateProfessor,DepartmentofHorticultureandCropSciences,SouthCentersJimChatfield,AssociateProfessorandExtensionSpecialist,DepartmentofPlantPathology,DepartmentofHorticultureandCropScience

Soiltestsprovidemorehelpfulinformationonsoilsthananyotherresource.Itisaninexpensivewaytomaintaingoodplanthealthinlawnsandlandscapes,andtomaximizeproductivityofvegetablegardensandfruitcrops.Soiltestresultspinpointplantnutrientneedsandsoiltestlabrecommendationsguidefertilizerapplicationssojusttherightamountisused.Testresultsalsoprovideinformationformakingplantselectiondecisionsbasedonrightplantrightplace.Ifgoodplantsgobad,asoiltestcanhelpdiagnosewhatwentwrong.

Soilsamplesaresenttoanaccreditedsoiltestinglab(seelistatend).Resultswillbesentalongwithrecommendationsfortakingcorrectiveactionsifneeded.Thisincludestheamountoffertilizersandotheradditivesneededtosupporthealthyplants.Withanaccuratesoilsampleandtest,reliablefertilizerrecommendationscanhelphorticultureprofessionalsandgardeningenthusiastsimproveplantqualityandproductivity,reducenutrientrunoff,andsavemoney.

Astandardsoiltestprovidesinformationonchemicalpropertiesofthesoilthatrepresentssoilfertility.Thisincludestheamountofpositivelychargedplantnutrients(cations)foundinthesoilincludingphosphorous

(P+),potassium(K+),calcium(Ca++),andmagnesium(Mg++).Thesechemicalelementsarecalledmacronutrientsbasedontheamountneededandusedbyplantstomaintainhealthygrowthanddevelopment.Thetestwillalsorevealthecationexchangecapacity(CEC)ofthesoil,whichisameasureofhowwellthesoilholdsontothesechemicalelements.ThehighertheCEC,thebetterthesoilholdsontocationsagainstwaterleaching.

OneofthemostimportantchemicalpropertiesissoilpH.Figure1showshowsoilpHinfluencestheavailabilityofimportantchemicalelementstoplants.Thesameamountofthenutrientisinthesoilregardlessofthewidthofthebandhowever,wherethebandsarewide,theelementisinawatersolubleformtobetakenupbyplantroots.Wherethebandsarenarrow,elementsarechemicallyboundintoanonsolubleformthatplacesthemoutofthereachofplantroots.

Foradditionalfees,soiltestinglabswillprovideinformationonotherchemicalpropertiesofthesoilsuchas

theconcentrationofessentialmicronutrients(sometimescalledtraceelements).Micronutrientstatusisbased

ontheamountoftheelementrequiredbyplants.Theseincludeiron(Fe++),manganese(Mn++)zinc(Zn++),

andcopper(Cu+)aswellasafewotherelements.Micronutrientsarejustasimportantasmacronutrientsformaintaininggoodplanthealthamicronutrientdeficiencycanbejustasdamagingtoplanthealthasamacronutrientdeficiency.Althoughmostlabschargeanextrafeeforamicronutrientanalysis,theresultsareimportanttolearningifyouhaveaproblemwiththisgroupofelements.

Soiltextureisanimportantphysicalpropertyofsoilandisbasedonthepercentageofsand,siltandclayinthesoil.Thesearecollectivelyknownasthemineralcomponentsofthesoilandareseparatedbasedonparticlesizewithsandbeingthelargestandclaybeingthesmallestparticles.Soiltestinglabsusesievestoperformasoiltexturetestbyseparatingsoilparticlesintothethreesizeclasses.Oncethepercentsand,siltandclayisknown,yoursoilcanbeplacedintoatexturalclassificationastheyappearontheSoilTexturalTriangleinFigure2.

Soillabsusuallychargeanextrafeetoperformasoiltexturetesthowever,understandingthetextureofyoursoilisimportantifyouareplanningtoaddadditionalsoilsuchasbuyingandspreadingtopsoil.Waterdoesnotmovefreelybetweensoilswithextremesinparticlesizetheproblemisknownassoilincompatibility.Forexample,placingasiltyclayontopofaloamysand,orviceversa,couldhaveseriousconsequenceswithwaterdrainage.

Figure1:SoilpHinfluencestheavailabilityofcertainnutrientsforplantstouptake.GraphicbyJoeBoggs,

OhioStateUniversityExtension.

Figure2:Soiltexturesandpercentages.GraphicbyJoeBoggs,OhioStateUniversityExtension.

WhyDoINeedtoSoilTest?Theguidanceprovidedbysoilteststohorticultureprofessionalsandgardeningenthusiastsissometimescomparedtotheguidancethatbloodtestsprovidetophysicians.Inthisvein,asoiltestislikeabloodtestforthesoil.Soiltestscanbeusedforfourpurposes:maintainingpropersoilfertilityguidingplantselectionperformingplantproblemdiagnosticsandforconformingtoindustryapprovedstandardpractices.

1.MaintainingProperSoilFertility.Healthyplantsneedcertainlevelsofsoilnutrientstothrive.Duringthegrowingseason,thesoilnutrientsandfertilitymayfluctuate.Thisisinfluencedbythequantityand

Figure3:Coloradobluespruceshowingsymptomsofmanganese(Mn)deficiency.PhotobyJoeBoggs,Ohio

StateUniversityExtension.

availabilityofplantnutrientsthatarealteredbytheadditionoffertilizers,manure,compost,mulch,andlimeorsulfur,inadditiontoleaching.Furthermore,largequantitiesofplantnutrientsareremovedfromsoilsasaresultofplantgrowthanddevelopment,andtheharvestingofcrops.

Asoiltestwilldeterminethecurrentfertilitystatusandprovidethenecessaryinformationtomaintainoptimumfertilityyearafteryear.Soilteststaketheguessworkoutoffertilizationandareverycosteffectivetheyeliminatewastefulspendingonunnecessaryfertilizerproducts.Testresultsandrecommendationshelpprotectourenvironmentbydiscouragingtheoverapplicationofplantnutrients.Excessnutrientsnotusedbyplantsmayescapeintogroundwater,streamsandlakes.

2.GuidingPlantSelection.SomeplantswillgrowinawiderangeofsoilpHlevels,whileothersrequireanarrowrangeofpH.Mostturfgrasses,flowers,ornamentalshrubs,vegetables,andfruitsgrowbestinslightlyacidsoilswhichrepresentapHof6.1to6.9.Plantssuchasrhododendron,azalea,pieris,mountainlaurel,andblueberriesrequireamoreacidicsoiltogrowwell.

Asoiltestwilldeterminewhetherthesoilisacidicoralkaline.ItisthemostcosteffectivewaytomatchthepHrequirementsofplantsthatyouselectwiththepHofthesoilyoureplantingthemin.

3.PerformingPlantProblemDiagnostics.Soiltestsareanimportanttoolforlearningwhygoodplantsgobad.Forexample,iftreesareexhibitingyellowing(chlorotic)leavesorneedlesduringthegrowingseason,asoiltestmayrevealwhetherthesymptomiscausedbyalackofanessentialnutrientoraproblemwiththesoilpHorboth.AsshowninFigure1,mostsoilnutrientsarereadilyavailablewhensoilpHisat6.5.WhenpHrisesabovethisvalue,nutrientelementssuchasiron(Fe),copper(Cu),zinc(Zn),andmanganese(Mn)willbecomelessavailable.However,whensoilpHdropsbelow6.5,thereleaseofcertainelementssuchasmanganese(Mn)canreachatoxicitylevelforsomesensitiveplants.

AnexampleofusingasoiltestfordiagnosingaplantproblemisillustratedwiththeyellowingofinnerneedlesonaColoradobluespruceinfigure3.Thesymptomisconsistentwithamanganese(Mn)deficiency.ThelackofMncouldbeduetoadeficiencyofMninthesoil,highsoilpHmakingMnunavailabletothetree,orboth.BlindlyapplyingMntocorrectaperceivedMnsoildeficiencyorapplyingasoilacidifiertolowerthesoilpHtoreleaseMnwithouttestingthesoilcouldhavedamagingconsequencesexcessiveMncanbetoxictoplants.Inthiscase,asoiltestshowedthatthesoilpHwas6.8meaningthedeficiencywasnotapHproblem.However,thetestalsorevealedthesoiltobeextremelydeficientinMn.TheproblemwascorrectedwithanapplicationofMnbasedonthesoiltestrecommendation.TheslightacidityofthesoilmeantMnwouldbereadilyavailabletobetakenupbythetree.

Anotherexampleofwhysoiltestingissoimportantforcorrectlydiagnosingplantproblemsisshownwithfigures4and5.TheredmaplesymptomsareconsistentwithaMndeficiencyinthefoliageandtheproblemisoftenblamedonahighsoilpH.Likewise,thechlorosis(yellowing)ontheoakisfrequentlydiagnosedoffthecuffasaniron(Fe)deficiencythatislikewiseblamedonanalkalinesoilcondition.However,bothsymptomscouldbecausedbyanutrientdeficiencyinthesoilaswellasothersoilorrootrelatedissues.A

soiltestisthefirststepindiagnosingthetruecauseofthesymptoms.Otherwise,youarejustguessing.Astheoldaxiomstates,dontguess,soiltest!

4.ConformingtoIndustryApprovedStandardPractices.TheAmericanNationalStandardsInstitute(ANSI)isaprivatenonprofitorganizationthatoverseesthedevelopmentprocessandapprovalofvoluntaryconsensusstandardsfortheprivatesectorintheUnitedStates.TheTreeCareIndustryAssociation(TCIA)isaccreditedbyANSItodeveloptheactualstandardsknownasANSIA300TreeCareManagementstandards.Theyarethegenerallyacceptedindustrystandardsfortreecarepractices.

FollowingarerecommendationsfromtheANSIstandardsspecifictosoiltesting:A300(Part2)2011SoilManagement14.4.4Soiltestingshouldbedonepriortodesigning,plantselection,planting,and/ordevelopingmanagementplansforlandscapes.15.2Soiland/orfoliarnutrientanalysisshouldbeusedtodeterminetheneed,formulation,andrateoffertilizer.15.6.3Whennewplantsarespecified,theyshouldbetolerantofthenativesoilpH.

A300(Part6)2012PlantingandTransplanting63.3Plantandsiteinspectionsfortransplanting63.3.5SoilattheinstallationsiteshouldbeanalyzedandtestedforpH,structure,texture,density,nutrientsandpercolation.

Figure4:RedMapleChlorosis.PhotobyJoeBoggs,OhioStateUniversityExtension.

Figure5:OakChlorosis.PhotobyJoeBoggs,OhioStateUniversityExtension.

WhenDoISoilTest?Asoiltestisusedasaplanningtoolandthefirststepinlearningwhatyouneedtodo,ornotdo.Soilsamplescanbetakenanytimeoftheyear,aslongasthesoilisworkable.However,youshouldallowplentyoftimetoreceiveandevaluateyoursoiltestresults,andthentakeactiontoimproveyoursoilfertility.Anyrecommendedadjustments,suchasafertilizerapplication,shouldbemadeattheappropriatetimeoftheyear.Forexample,fallisthebesttimeoftheyeartomakealimeapplicationtoraisethesoilpH,whilespringisthemostappropriatetimeoftheyearforasulfurapplicationtolowerthepH.

HowFrequentlyShouldISoilTest?Asoiltesteverytwotothreeyearsisusuallyadequateformaintainingsoilfertility.Samplemorefrequentlyifyoudesireaclosermonitoringofthefertilitylevels,orifyougrowplantsthatrequiremorenutrients.Soiltestsfordiagnosticpurposescanbemadeasneeded.