8/8/2019 Soil Testing for Home Gardeners

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SoilTestingforHomeGardenersManyhomegardeningbooksrecommendasoiltesteachyeartodeterminenutrientneedsforplantsbeinggrown. Asa

homegardener,youmaywonderShouldIdoasoiltest? Itturnsoutthatthisisadifficultquestiontoanswer.

Whatasoiltestwilltellyou:Thepurposeofasoiltestistodeterminetheexistingleveloffertilityinagivensoiltoprovideguidanceinfertilizingyour

garden. Dependingonthepackagechosenfromtheanalyticallab,itwillmeasureprimarynutrients(nitrogen,

phosphorus,andpotassium),secondarynutrients(sulfur,calcium,andmagnesium)andmicronutrients(zinc,iron,

copper,manganese,boron,molybdenum,andchlorine). Differentlabsusedifferentmethodsforanalyzingsome

nutrientlevels,forexamplephosphorus. AsoiltestmayalsomeasurethepHandoftenthecationexchangecapacity

(CEC)whichwilltellyouhowwellthesoilwillholdandreleasemineralnutrients.

Insmallergrowingspaces(usuallythoseofahomegardener),thecostofasoiltestcanbemuchmorethanthecostof

allthesoilamendmentsthatwillbeneededforatleastonegrowingseason. However,theremaybesomecaseswhen

you

will

want

to

perform

a

soil

test.

Whenyoumightwanttoperformasoiltest:Ifyouareinvestingalotofmoneyinanewprojectandwanttomakesurethenewplantshavecorrect

fertility.

Ifyouhavebeengardeningforalongtimeandhavebeenregularlyapplyingfertilizer,youmaybeableto

reducetheuseofadditionalfertilizer. Aonetimesoilfertilitytestwillbeabletodetermineifexistingfertility

levelsareadequate,high,ordeficient.

Whenstartinganewvegetablegarden,asoiltestwillestablishabaselineandiffertilityishighoradequate,

youcanthenhaveanotheranalysisdone34yearslater. Thismayhelptodeterminewheredeficienciesexist

andhelptopreventexcessivebuildupsofsomenutrients.

Ifyouseeplantsymptomsindicativeofnutrientdeficiencyortoxicity,youmaywanttoperformasoiltest

andpossiblyaplanttissueanalysis. OnepublicationfromUniversityofMinnesotaExtensionmayhelpin

diagnosingnutrientdisorderscanbefoundat:

http://www.extension.umn.edu/distribution/horticulture/components/M1190.pdf

Ifyoudecidetohavesoilfertilitytestperformed:SoilSamplingCorrectsoilsamplingisthefirststepintheprocess. Someoftheimportantpointsofsoilsamplingare:

Samplewheretheplantwillbegrown,andthedepthtowhichtherootswillgrow.

Divide

the

area

into

smaller

sub

regions

depending

on

soil

type,

crop

grown,

amendments

used,

etc.

Take1020subsamplesfromthroughouteachregion,mixinacleanbucketandtakeasubsample.

Avoidunusualareassuchaswetlands,formermanurepiles,etc.

Avoidcontaminatingthesample;usecleansamplingtools.

Findpublicationswithmoredirectionsonsoilsampling:

http://extension.oregonstate.edu/catalog/pdf/ec/ec628.pdf(OregonStateUniversity)

http://info.ag.uidaho.edu/resources/PDFs/EXT0704.pdf(UniversityofIdaho)

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SoilAnalysisWashingtonStateUniversitynolongerperformssoiltests. Universitylabsthatareavailableforsoiltestingarethe

UniversityofIdahoAnalyticalSciencesLaboratory(http://www.agls.uidaho.edu/asl/)andUniversityofMassachusetts

(http://www.umass.edu/plsoils/soiltest/brochlink1.htmandwww.umass.edu/plsoils/soiltest/soilbrochure2009.pdf).

BothoftheselabsperformanalysisusingproceduresthatwillbeaccurateforsoilsinwesternWashingtonandwill

providerecommendations.

SeveralcommerciallabsareavailableinthePacificNorthwest. TheselabscanbefoundinpublicationsfromWashington

StateUniversity: http://wsprs.wsu.edu/AnalyticalLabsEB1578E.pdf orOregonStateUniversity:http://extension.oregonstate.edu/catalog/pdf/em/em8677.pdf

Forbestresults,choosealabwiselythefirsttimeasoiltestisdoneandcontinueusingthatlabforsubsequenttests.

CheckoutthelabsWebsiteandcontactthelabbeforesendingthesampletomakesurethattheywillprovidethe

servicethatyourequire. Differentlabsusedifferentmethodsforanalyzingsomenutrientlevels,forexample

Phosphorus. Havingaconversationwiththelabpersonnelisadvisedtomakesurethatyouwillbegettingthecorrect

analysisdoneforyourregionandrequirements. Somelabsproviderecommendationsforsoilfertility;thisisuseful

whenusingyourresultstodeterminenutrientrequirements.

MoreResources: WashingtonStateUniversityExtension:HomeGardenersGuidetoSoilsandFertilizers:

http://cru.cahe.wsu.edu/CEPublications/eb1971e/eb1971e.pdf

WashingtonStateUniversityExtension:OrganicGardening:

http://cru.cahe.wsu.edu/CEPublications/eb0648/eb0648.pdf

WSUsDr.CraigCoggerssiteonSoilsandSoilTesting: http://www.puyallup.wsu.edu/soilmgmt/Soils.htm

OregonStateUniversityExtensionSoilTestInterpretationGuide:

http://extension.oregonstate.edu/catalog/pdf/ec/ec1478.pdf

WashingtonStateUniversityExtension FertilizerGuide:VegetableandFlowerGardens,ExceptIrrigatedCentra

Washington: http://whatcom.wsu.edu/ag/homehort/FertilizerGuide.pdf

RayA.McNeilanandMichelineRonnengen. PacificNorthwestGuidetoHomeGardening. 1989. TimberPress,Portland.

SteveSolomon. GrowingVegetablesWestoftheCascades. 2007. SasquatchBooks,Seattle.

WSUWhatcomCountyExtension

1000NForestStreet,Suite201,Bellingham,WA 98225

Contactus:whatcom@wsu.edu|3606766736|OfficeHoursMF8:30a.m.to4:30p.m.